ABSTRACT. Pyrolysis plays a central role in a wide range of fields related to energy conversion and material synthesis, encompassing key areas such as engine combustion and flame synthesis of nanomaterials. This lecture provides a systematic review of recent advances in the study of pyrolysis processes, covering fundamental experimental investigations, kinetic model development, and the extension toward engineering applications. Particular emphasis is placed on frontier topics including fuel active cooling, reaction control of ammonia combustion in gas turbines, and flame synthesis of silicon-based nanoparticles.

First, recent advances in experimental methodologies for studying pyrolysis are introduced. Through the development and application of experimental platforms such as constant-volume combustion vessels, shock tubes, and flow reactors, precise control of pyrolysis reaction pathways and reaction progress has been achieved over wide ranges of temperature and pressure. When combined with advanced diagnostic techniques such as synchrotron vacuum ultraviolet photoionization mass spectrometry, quantitative measurements of stable species, radicals, and key intermediates become possible. These experimental approaches provide unprecedented insights into radical pool evolution and reaction pathway competition during fuel pyrolysis.

Second, the lecture presents recent progress in the development and validation of pyrolysis kinetic models. Based on high-level quantum chemical calculations and kinetic calculations, accurate rate constants for key pyrolysis pathways have been obtained. Comprehensive kinetic models capable of describing fuel decomposition, radical formation, and molecular growth have been constructed. By integrating newly acquired experimental data with literature data, the models have been cross-validated against multiple types of experimental data. The results demonstrate excellent predictive capability over a wide range of operating conditions, laying a solid foundation for practical applications of these models under realistic conditions.

Finally, recent advances in the application of pyrolysis processes across multiple scenarios are highlighted. In propulsion and energy systems employing active cooling, fuel pyrolysis serves not only as an efficient heat sink but also as a critical source of reactive intermediates, making accurate prediction of pyrolysis initial temperatures and conversion rates essential. In the context of reaction control for ammonia combustion as a novel zero-carbon gas turbine fuel, strategies based on ammonia pre-cracking and oxygen enrichment driven by self-promoted fuel pyrolysis offer new perspectives toward addressing the long-standing “holy grail” challenge of simultaneously enhancing reactivity and controlling pollutant formation. In addition, the application of pyrolysis in flame synthesis is explored, with particular attention to the decisive role of reaction pathways and intermediate evolution in the transformation of precursors into silicon-based nanoparticles.

ABSTRACT. The use of renewable energy sources, including biomass, represents a viable pathway for reducing the global net greenhouse gas emissions through partial or full substitution of fossil fuels. Biocarbon, the solid product of biomass pyrolysis, has various applications, which require specific physicochemical properties of the carbon source. Key characteristics include volatile matter amount and composition, biocarbon yield and fixed carbon content, while ash content and its composition is critical for determining the suitability for industrial uses, i.e., specific metallurgical processes. Metallurgical applications require substantial quantities of biocarbon to partially or fully replace fossil carbon with a renewable alternative. Although stem wood yields high-quality biocarbon with low ash content, its limited availability and high alternative economic value constrain its use for biocarbon production. Consequently, a less intensively used and cheaper feedstock is needed for the biocarbon production. Bark, an abundant and low-cost by-product of the wood processing industry, is a potential alternative feedstock. However, its inorganic content, which is higher than that of stem wood, must be reduced to make it a suitable feedstock for carbonization and subsequent application in certain metallurgical processes. This study investigates water leaching as a pretreatment for birch, spruce and pine bark to reduce their water-soluble inorganic contents in both the feedstock and the resulting biocarbon. Leaching experiments were conducted on ground bark (d < 1 mm) using deionized water at 25 and 60 °C under static and stirred leaching conditions. The influence of water leaching on the bark physicochemical properties was evaluated using ICP-OES and TG/MS methods. Results indicated that water leaching removed significant amounts of organic material alongside the targeted inorganics. Consequently, the chemical profile of the leachates was characterised by Py-GC/MS, performed both with and without thermally assisted hydrolysis and methylation (THM). Using the THM-GC/MS method improved the volatility of the leachate components, enabling the GC/MS analysis of a larger fraction of the samples. Significant differences in leachate profiles were observed, reflecting a species-specific composition. Birch extract was dominated by rhododendrol and platyphylloside derivatives, while spruce leachate was primarily characterised by stilbene derivatives. Significant amounts of carbohydrate decomposition products in the spruce leachate indicated the effective water leaching of stilbene glycosides. The compositional characterisation of the solubilized organics can reveal the potential of the leachates for direct valorisation, tuning a waste remediation step into a source of valuable chemicals.

ABSTRACT. This study investigated fast pyrolysis and the products thereof form brewer's spent grains (BSG), in comparison with BSG that underwent water leaching and protein extraction (PWBSG) prior to pyrolysis. This allowed us to investigate value creation from this voluminous industrial residue through cascaded protein removal and pyrolysis. Proteins were removed and comparatively quantified through different laboratory techniques (Kjeldahl-N based, bicinchoninic acid assay and trichloroacetic acid precipitation). After protein extraction of BSG (N content of 4.42 wt.%), a crude protein fraction was obtained in a yield which had a nitrogen content of 9.17 wt.%. This corresponds to a nitrogen recovery in the extracted proteins of 28.72%. Thermogravimetric analyses showed that the protein removal step (using NaOH) altered the physicochemical properties of the BSG from which the proteins were removed (PWBSG). Indeed, this residue (PWBSG) resulted in a smaller relative peak area for levoglucosan upon micropyrolysis, compared to BSG, while also having a reduced peak area for protein-derived N-containing compounds. Performing fast pyrolysis in a 250g·h-1 continuous fast pyrolysis (mini-plant) set up resulted in bio-oil yields of 47.27 ± 0.55 wt.% and 53.45 ± 1.97 wt.% for BSG and PWBSG, respectively. Upon fractionation of the bio-oil in an aqueous and organic phase (EtOAc), a desired decomplexation of the bio-oil was observed, retaining valuable biorefinery chemicals (phenol, 2-furanmethanol, etc.). This renders these bio-oil fractions good streams for further downstream processing.

ABSTRACT. Historical “gold” varnishes—hereafter defined as oil- and resin-based transparent coatings applied over silver leaf to produce a gold-like appearance, and not as varnishes containing metallic gold—are characteristic surface finishes of gilt leather objects. In these artefacts, silver leaf is adhered to a leather-type support and subsequently coated with a yellow varnish whose optical properties create the visual effect of gold. These complex varnishes, composed of oils, resins, colorants, and minor additives, pose significant analytical challenges due to the difficulties in their exact identification as well as their extensive ageing, degradation, and the severe micro-sampling constraints imposed by cultural heritage materials. While Pyrolysis–GC/MS (Py-GC/MS) has been applied to a wide range of heritage materials, its potential has never been systematically explored for historical “gold” varnishes of this type. This study presents the first comprehensive evaluation of a multifunctional Py-GC/MS workflow applied to “gold” varnish samples from a 17th-century gilt leather panel, The Triumph of David. The objective is to assess which pyrolytic configurations are best suited for characterizing both major and minor components in these highly complex coatings and to establish a methodological framework for future studies. Selected varnish samples were analyzed using a suite of Py-GC/MS-based techniques, complemented by conventional GC/MS. The analytical strategy targeted lipidic, resinous, waxy, and proteinaceous components. Historical samples were systematically compared with gilt-leather gold-varnish model systems reproducing documented historical recipes. The Py-GC/MS configurations investigated included reactive Single-Shot (SS) Py-GC/MS, partially reactive Double-Shot (DS) Py-GC/MS, Evolved Gas Analysis (EGA)-MS, Heart-Cut EGA-GC/MS, and a recently developed SS Py-GC/MS mode employing Functional-Splitless injection for high-sensitivity detection of trace constituents. Each configuration was evaluated in terms of qualitative and semi-quantitative performance, sensitivity to minor compounds, sample-amount requirements, and practical considerations such as analysis time, data complexity, and robustness. This represents the first systematic comparison of these techniques applied specifically to historical “gold” varnishes. The results demonstrate that the multifunctional workflow provides unprecedented insight into the composition of historical “gold” varnishes. Reactive SS Py-GC/MS enabled rapid identification of major organic classes, while DS Py-GC/MS and EGA-based methods improved interpretation of complex degradation patterns and overlapping thermal behaviors typical of aged coatings. Notably, the Functional-Splitless SS Py-GC/MS configuration significantly enhanced detection of minor diagnostic compounds, such as specific resins and additives, demonstrating its value for the study of historical “gold” varnishes. The integrated dataset allowed a more refined interpretation of the “gold” varnish composition on The Triumph of David, supporting attribution hypotheses and offering insights into workshop practices. This research establishes the necessity of multimodal pyrolytic approaches for the characterization of highly aged varnish systems under strict sampling constraints and provides practical guidance for future analytical studies of gilt leather and other historically layered coatings.

Acknowledgements: We thank Laurianne Robine, Marie Radepont, and Sylvie Heu-Thao (Centre de Recherche sur la Conservation, Muséum national d’Histoire naturelle, Ministère de la Culture, CNRS, Paris, France) for providing gilt-leather gold-varnish models and for sharing their expertise.

ABSTRACT. The curing and ageing of an oil paint is the process through which the organic molecular composition of an oil evolves from polyunsaturated triglycerides into a more complex system, whose composition changes over time and includes low molecular weight compounds; oxygenated derivatives, such as epoxides, ketones, free fatty acids and free dicarboxylic acids; mono-, di- and triglycerides; and cross-linked fractions.[1] The curing process can be described as a competition between two phenomena: cross-linking and oxidative degradation.[2, 3] It is not yet entirely clear which conditions favour cross-linking and which promote oxidative degradation; however, it has been shown that the balance between these two competing phenomena may play a crucial role in the emergence of degradation issues in oil paintings. Achieving a detailed molecular characterization of the oil polymeric network, and thus determining the degree of cross-linking and oxidation of an oil paint layer, still remains a significant analytical challenge. Analytical pyrolysis coupled to mass spectrometry (MS) is the only MS–based technique that allows the analysis of the entire organic fraction of the sample, including the crosslinked fraction, although the data obtained are often difficult to interpret.[4] To address this issue, in the present work a new set of experiments was designed using methyl linoleate and methyl linolenate as model binders, representing a semi-drying oil and a drying oil, respectively. Owing to their simpler molecular architecture, polyunsaturated methyl esters lead to the formation of curing products whose mass spectra are more informative, since polymerized triglyceride-based films are largely dominated by aliphatic chain fragmentation, whereas methyl esters preserve more diagnostic ions.[5] Model paint layers were prepared by admixing methyl linoleate or methyl linolenate with three pigments: lead white, ultramarine blue and cadmium red. These systems were systematically analysed over a period of seven months by evolved gas analysis coupled with mass spectrometry (EGA-MS). This technique was employed to investigate the molecular structure of components with different thermal stability, from the volatile fraction up to the polymeric network, to assess how they differ across binder–pigment combinations and how they evolve during curing. The data presented in this work demonstrate that the use of methyl esters as model oil binders greatly simplifies the mass spectral features of the lipid paint fraction. EGA-MS enables the detection of oxidation and cross-linking products and the kinetics of evolution with an unprecedented level of molecular detail, thereby improving our understanding of the chemistry of oil paints. [1] Bonaduce, I., et al., Accounts of Chemical Research, 2019. 52(12): p. 3397-3406. [2] Caroti, G., et al., Journal of Cultural Heritage, 2025. 76: p. 239-250. [3] Pizzimenti, S., et al., Scientific Reports, 2023. 13(1): p. 8094. [4] Nardelli, F., et al., Scientific Reports, 2021. 11(1): p. 14202. [5] Vannoni, L., et al., Microchemical Journal, 2022. 173: p. 107012.

ABSTRACT. Although the pyrolysis mechanism of cellulose remains not fully understood, one of the main challenges lies in its complex structure: cellulose consists of microcrystalline aggregates with a degree of polymerization around 200 and includes amorphous (or paracrystalline) regions. For instance, under isothermal pyrolysis conditions, a characteristic inductive time is observed between the point at which the target temperature is reached and the onset of significant weight loss due to pyrolysis. To describe this behavior, the Broido–Shafizadeh kinetic model introduced the concept of "active cellulose," though the detailed nature of this state remains unclear. Our research focuses on elucidating this activation behavior.

In this study, we investigated the isothermal pyrolysis of cellulose below 320 °C using thermogravimetry–mass spectrometry (TG–MS). We report that a zero-order reaction first occurs, followed by a degradation behavior that can be described by a radial degradation pathway, assuming the cellulose microcrystals degrade inward from their cross-sections without shortening along their longitudinal axis.

Isothermal TG–MS analysis of cellulose at various temperatures revealed a clear difference in pyrolytic behavior around the temperature range of 310–320 °C. Below 310 °C, cellulose exhibited a linear decrease in weight over time, indicating a zero-order reaction. In this temperature range, levoglucosan—a typical depolymerization product—was not detected. Instead, water and low-molecular-weight fragments were selectively generated. In contrast, above 320 °C, the weight loss rate increased rapidly after an inductive time, and a significant production of levoglucosan was observed under these conditions.

Upon prolonged heating below 310 °C, it was found that, regardless of the set temperature, the rate of weight loss and the generation rates of water and fragments remained constant until approximately 30% of the mass had been lost—consistent with zero-order kinetics. Beyond this point, the rate of degradation began to decrease linearly with time. This behavior can be rationally explained by a radial degradation pathway, where degradation proceeds inward from the outer cross-section of cylindrical cellulose microcrystals. Activation energies determined via Arrhenius plots were 173 kJ/mol for the zero-order reaction and 186 kJ/mol for the radial degradation process. The former is attributed to a peeling reaction initiated at the reducing ends of cellulose chains via a dehydration mechanism. GPC analysis of pyrolysis residues also supported the occurrence of the peeling reaction.

ABSTRACT. The pyrolysis of biomass is a promising technology for the sustainable production of renewa-ble platform chemicals and energy. However, this endothermic process, which is carried out in the absence of oxygen, requires the addition of energy. In order to improve the energy effi-ciency of the process, microwave-assisted pyrolysis (MAP) has recently gained in importance [1,2]. In MAP, the biomass is heated volumetrically by dielectric losses [3,4]. This enables a more direct heating with accelerated heating rates in large wood pieces as compare to conven-tional heating. However, microwave heating results in complex interactions between the elec-tromagnetic field, the reactor geometry, and the material to be heated, which undergoes sig-nificant changes during the conversion process [5]. These interactions must be taken into ac-count in the design of new innovative microwave reactors. It is therefore necessary to develop robust and versatile simulation tools that reliably predict the influence of the electromagnetic field, flow conditions in the reactor, and thermal transport processes on biomass heating. For this purpose, a modeling approach for the electromagnetic field within a microwave reactor was implemented in this work and coupled with a multi-region solver in the open-source soft-ware OpenFOAM. The accuracy of the solver was demonstrated by simulating the heating of a wooden block and verified using data from the literature [5]. The influence of the sample on the shape of the electromagnetic field is clearly visible in simulation results, emphasizing the importance of correct implementation. Dielectric losses in the wood block create two hot spots that are in-troduced as energy sources in the multi-region solver. The wood sample heats up particularly in these two hot spots and transfers heat to the surrounding nitrogen through conjugate heat transfer due to the coupling of the solid and gas phases. The simulation results showed good agreement with literature data for the heating of biomass and are therefore well suited for simulating the heating of solids. An extension of the solver to take into account pyrolysis reactions and the associated material changes is currently under development.

[1] Zhang Q, Li Z, Liu Z, Prasetyatama YD, Oh WK, Yu IKM. Microwave-assisted biore-fineries. Nat. Rev. Clean Technol. 2025; 1(4):269–87. [2] Che Y, Yan B, Li J, Zhao Z, Gao X, Chen G et al. Microwave applied to the thermo-chemical conversion of biomass: A review. Renewable and Sustainable Energy Reviews 2025; 216:115674. [3] Vorhauer-Huget N, Seidenbecher J, Bhaskaran S, Schenkel F, Briest L, Gopalkrishna S et al. Dielectric and physico-chemical behavior of single thermally thick wood blocks under microwave assisted pyrolysis. Particuology 2024; 86:291–303. [4] Appleton TJ, Colder RI, Kingman SW, Lowndes IS, Read AG. Microwave technology for energy-efficient processing of waste. Applied Energy 2005; 81(1):85–113. [5] Ciacci T, Galgano A, Di Blasi C. Numerical simulation of the electromagnetic field and the heat and mass transfer processes during microwave-induced pyrolysis of a wood block. Chemical Engineering Science 2010; 65(14):4117–33.

ABSTRACT. The thermal conversion behavior of reconstituted tobacco (RT) directly determines the aerosol release efficiency of heated tobacco products. This study focuses on regulating the pyrolysis and release characteristics of RT through structural design strategies, without relying on specific functional fillers. Two main approaches were developed and evaluated: (1) constructing integrated thermal networks within the fiber matrix through nanofiber-stabilized dispersion combined with wet papermaking processes; (2) fabricating multilayer functional sheets via coating and self-assembly techniques. The in-situ constructed three-dimensional thermal network significantly improved the thermal conductivity of RT, leading to more uniform temperature distribution during heating. Pyrolysis analysis demonstrated that the optimized thermal pathway altered the decomposition kinetics, increasing the release rate of key aerosol constituents compared to conventional RT. Release performance evaluation under programmed heating revealed enhanced release controllability and reduced temperature lag effect. Through the structural integration of components with distinct release properties, a multilayer functional sheet was designed. This approach achieved an improvement in total release efficiency by establishing synergistic thermal-mass transfer pathways. The structural designs effectively addressed challenges in filler dispersion and retention while creating controllable thermal conduction pathways. These methods provide valuable strategies for thermal management of RT and demonstrate significant potential for developing next-generation heated tobacco products with optimized aerosol release profiles.

ABSTRACT. The depletion of fossil fuel resources and escalating environmental issues (such as CO2 emissions and pollution) require a transition to renewable alternative energy sources. Biomass energy, as the only carbon-rich and abundant renewable resource, provides a sustainable pathway for the production of fuels and chemicals. The catalytic conversion of volatile from biomass pyrolysis into high-value platform chemicals such as light aromatic hydrocarbons (LAHs), represents an effective strategy to enhance energy security and facilitate carbon neutrality. Among them, ZSM-5 stands out from other zeolites due to its high thermal stability, unique pore structure, and adjustable acid sites, making it the most suitable for LAHs production. However, traditional commercial ZSM-5 zeolites still need improvement in terms of catalytic activity and stability. Therefore, this study employed a series of modifications using metallic zinc on ZSM-5, analyzed the structure-activity relationship between catalyst performance and products during its application in the catalytic pyrolysis of cellulose, and evaluated its stability in the catalytic pyrolysis reaction of corncobs. Initially, ZSM-5 was modified using a simple impregnation method. Results indicated that optimal performance was achieved at a metal Zn loading of 0.2 wt.%, with a significant increase in LAHs yield compared to commercial ZSM-5. However, issues such as poor catalyst stability still exist. Subsequently, the LAHs yield was further enhanced by directly doping metallic Zn during a one-step hydrothermal synthesis process. Research revealed that the catalyst's pore size, specific surface area, and particle size significantly influence its performance. Therefore, a seed-induced and Dry Gel Conversion-Steam Assisted Crystallization method was employed to synthesize a multi-porous, nano-doped Zn-ZSM-5 catalyst, which further enhanced the LAHs production capacity, achieving a maximum yield of 174.68 mg/g. The results indicate that the formation of mesopores and nanocrystals during synthesis promotes the generation of ZnOH+ active sites, thereby enhancing the dehydrogenation and aromatization reaction capacity and improving the mass transfer capability of the catalyst. To further enhance catalyst stability, a catalyst was synthesized by coating nano-ZSM-5 with Zn/SiO2. By adjusting the core-shell ratio, the catalyst's stability was significantly improved. Compared to commercial ZSM-5, which exhibited complete deactivation after 160 min of reaction, the LAHs yield decreased by only 14.6% after 320 min of reaction.

ABSTRACT. Biochar production via pyrolysis is a strategic thermochemical pathway for the sustainable valorization of diverse biomass feedstocks [1]. To elucidate the critical interplay between feedstock origin and process parameters, this study presents a systematic investigation of biochars produced from four distinct biomass classes: a marine macroalga (Sargassum sp.), two lignocellulosic woods (Black Locust and Niaouli), and an agricultural residue (sugarcane bagasse). The selection of these biomasses is motivated by their representativeness of Caribbean resources, as well as by the environmental issues associated with the proliferation of certain species. The primary objective is to identify and quantify how the feedstock’s biochemical composition and the pyrolysis temperature influence the yield, key physicochemical properties, and functional performance of the resulting biochars.

A comprehensive characterization of the raw biomasses including proximate, ultimate, and ash composition established the initial conditions governing their pyrolysis behavior. Biochars were produced under an inert atmosphere for pyrolysis temperatures ranging between 500 and 900°C. The products were analyzed using a suite of complementary techniques (N2 and CO2 sorption analysis, electronic microscopy, X-Ray diffraction, elemental analysis) to determine the evolution of key properties: porosity and surface area, carbonaceous structure (aromatization level), morphological features, elemental stoichiometry (H/C, O/C), and the transformation of inorganic constituents.

Results demonstrate that increasing pyrolysis temperature generally drives carbonization, aromatization, and pore development, yet the magnitude and nature of these changes are profoundly feedstock-dependent [1,2]. Distinct property profiles emerged for each biomass class: algal-derived biochars exhibited notably high ash and inorganic content, lignocellulosic biochars displayed well-developed aromatic structures and porosity, and bagasse biochar showed an intermediate characteristic with significant silica content. The inorganic fraction underwent temperature-dependent transformations, significantly altering biochar reactivity and functionality.

Based on these results, the valorization potential of the biochars is discussed with respect to their textural, chemical, and mineral properties. Targeted applications include adsorption of gaseous or aqueous pollutants [3,4], soil amendment for fertility improvement and carbon sequestration [2] as well as their use as catalysts or catalyst supports. This study underlines the importance of controlling both biomass selection and pyrolysis conditions to tailor biochar properties toward specific, high value-added environmental and energy-related applications [1].

[1] M. Belhachemi, B. Khiari et M. Jeguirim, “Characterization of biomass-derived chars”, dans M. Jeguirim & L. Limousy (éd.), *Char and Carbon Materials Derived from Biomass: Production, Characterization and Applications*, ISBN 978-0-12-814893-8, Elsevier, 2019, pp. 69–108, doi:10.1016/B978-0-12-814893-8.00003-1. [2] M. Jeguirim et L. Limousy, “Biochar for soil amendment”, dans *Char and Carbon Materials Derived from Biomass: Production, Characterization and Applications*, ISBN 978-0-12-814893-8, Elsevier, 2019, pp. 109–145, doi:10.1016/B978-0-12-814893-8.00004-3. [3] M. Zbair, M. Drané et L. Limousy, “NO2 Adsorption on Biochar Derived from Wood Shaving Litter: Understanding Surface Chemistry and Adsorption Mechanisms”, *Clean Technologies*, vol. 6, no. 3, pp. 973–993, 2024, doi:10.3390/cleantechnol6030049. [4] M. Drané, M. Zbair, S. Hajjar-Garreau, L. Josien, L. Michelin, S. Bennici et L. Limousy, “Unveiling the Potential of Corn Cob Biochar: Analysis of Microstructure and Composition with Emphasis on Interaction with NO2”, *Materials*, vol. 17, no. 1, art. 159, 2024, doi:10.3390/ma17010159.

ABSTRACT. Biomass fast pyrolysis has emerged as a highly promising technology for producing renewable fuels and chemicals. However, the inherent multiscale and multiphase nature of the process and the heterogeneous nature of biomass feedstocks typically lead to low selectivity toward each bio-oil molecule, posing significant commercialization challenges. A molecular-level understanding of the biomass pyrolysis reaction kinetics considering the interactions between the main constituents (i.e., cellulose, hemicellulose, and lignin) is essential to advance the macroscopic design, scale-up, and optimization of the process. In this work, microreactor experiments were conducted to determine the effects of lignin structures on the yields of cellulose-derived products during pyrolysis. We show that levoglucosan (LG) formation is inhibited by the β-O-4 lignin linkages or catalyzed by the 5-5 linkages, glycolaldehyde (GA) formation is catalyzed by the β-O-4 linkages or inhibited by the 5-5 linkages, and 5-hydroxymethylfurfural (5-HMF) formation is inhibited by either linkage. Density functional theory calculations reveal that these catalytic and inhibitory effects on cellulose fast pyrolysis are induced by noncovalent interactions between cellulose and lignin. The molecular-level picture of cellulose–lignin interactions uncovered in this work paves the way for further use of genetic engineering to grow new genotypes of biomass for selective production of value-added chemicals and machine learning approaches to obtain correlations between biomass structures and product yields for biomass fast pyrolysis.

Figure caption: (a) DFT-calculated rate constant ratios (R) of the two elementary steps leading to LG formation in the presence of propane (C3, model compound for C28 as a control), G-β-O-4-G, or H-5-5-H at 500°C. (b) Comparison of experimental selectivity toward LG from CE+C28, CE+G-β-O-4-G, or CE+H-5-5-H against the DFT-calculated R values for the rate-limiting step (2 → 3 + i2) of LG formation. (c) Mass yields of CE-derived products from neat CE pyrolysis and co-pyrolysis of CE with C28 (CE+C28), G-β-O-4-G (CE+G-β-O-4-G), or H-5-5-H (CE+H-5-5-H). Mass yields are shown for LG, dianhydroglucopyranose (DAGP), 1,6-anhydroglucofuranose (AGF), GA, acetic acid (AA), 5-HMF, 2-(5H)-furanone (FO), furfural (FF), carbon monoxide (CO), carbon dioxide (CO2), and char.

ABSTRACT. The performance of catalysts for dry methane reforming strongly depends on the properties of the catalyst support, particularly its surface area, pore structure, and accessibility of active sites. Biochar is an attractive precursor for catalyst supports due to its renewable origin, low cost, and the possibility of achieving a high surface area and well-developed porosity. The optimized activated carbons (ACs) exhibit textural properties that make them highly promising carbon-based catalyst supports for DMR. Moreover, it is expected that ACs used as catalyst supports will potentially facilitate coke mitigation by improving reactant diffusion and reducing the accumulation of carbonaceous deposits on the catalyst surface. During the methodology development, biochar was subjected to physical and chemical activation applied in different sequences. A synergistic effect resulting from the combination of both activation methods was observed, and the influence of their order on the structural and textural properties of the resulting carbon materials was investigated. The aim was also to prepare carbon catalyst supports for the DMR process and to examine their effect on coke deposition. The results demonstrate that the combined physical and chemical activation leads to a pronounced synergistic effect, producing AC with significantly higher specific surface areas and more developed hierarchical porosity compared to single-step activation. The coexistence of micro-, meso-, and macropores enhances both the dispersion of the active catalytic phase and mass transport within the material.

ABSTRACT. Biomass gasification for hydrogen production has received widespread attention in recent years as a sustainable energy technology. However, the biomass gasification process produces tar. This can seriously affect subsequent gas cleaning and utilization. In this study, toluene was used as a tar model compound. The effects of different catalyst carriers, reforming temperatures, S/C ratio, and in-situ CO2 capture on the yield of toluene steam reforming were investigated. The results showed that under the same working conditions, the hydrogen yield of the SiC carrier catalyst was much higher than that of the SiO2 and Al2O3 carriers. This is due to the excellent thermal conductivity and suitable acid-base properties of the SiC carrier. CaO could effectively adsorb CO₂ and increase the hydrogen yield. The hydrogen yield reached 90.63% with the addition of 0.3g of CaO, which was 13.7% higher than that without the addition of CaO. In addition, to investigate the structural changes and chemical state of the catalysts the differences between the catalysts before and after use were analyzed using a variety of characterization methods. This study provides critical insights into the design of efficient catalysts and processes for overcoming the challenges associated with biomass-derived tar.

ABSTRACT. Archaeological objects are made up of complex mixtures that may include binders or organic adjuvants of various origin (animal, plant, fossil), comprising chemical families with different properties (terpenes, fatty acids, amino acids, sugars) and which come from more or less complex technical manufacturing processes (heat treatments, mixing, fermentation, grinding). Therefore, it is appropriate to provide an analytical response with a very high resolving capacity to the challenges presented by their study, whether for archaeometry studies or for understanding the degradation phenomena observed on these objects. As an analytical method, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) has become a versatile technique commonly used in the domain of cultural heritage since the middle of the 20th century [1]. However, a one-dimensional GC separation is often insufficient for separating the individual constituents in complex mixtures. As a consequence, more resolutive techniques are needed, and comprehensive gas chromatography GCxGC provides an adapted answer to this challenge. The coupling of two capillary columns connected via a modulation system optimizes the complementary separation capabilities of columns of different polarities. The addition of a mass spectrometer as a detector adds another dimension to the separation capability. As a result, a comprehensive two-dimensional gas chromatography/mass spectrometry (GC×GC-MS) system offers much higher resolution, peak separation capacity, selectivity and lower detection limit for the analysis of volatile organic molecules, making it one of the most powerful analytical systems available for analysts today [2]. As expected, the coupling of pyrolysis with GCxGC-MS demonstrated promising applications for the investigation of cultural heritage materials [3]. With an experience of almost ten years, we can explore the benefits of using GCxGC-MS in conjunction with pyrolysis for the analysis of several cultural heritage artefacts: East Asian papers, Chinese inks, East Asian lacquers, archaeological collagen, beeswax, or bitumen oil paints. In particular, the advances in the investigation of cultural heritage materials can be seen in: (i) the identification of numerous fiber’s plant markers for botanical origin assignment, (ii) the identification of inks components used in ancient Chinese recipes, (iii) the chromatographic separation of regioisomers of alkylphenols, and alkylcatechols in lacquer saps. Besides providing an improved depiction of these materials, Py-GCxGC-MS revealed as well the presence of other additives difficult to detect using Py-GC-MS alone (polycyclic aromatic hydrocarbons as markers of soots, diketopyperazines as markers of animal glues) and unexpected series of 2-methyl ketones in some of these materials (Asian lacquer artefacts, beeswax) raising interesting questions about the pyrolysis degradation mechanisms of these materials. Concomitantly, Py-GCxGC-MS reduced the necessity of using tetramethyl ammonium hydroxide (TMAH) as derivatization reactant when characterizing these materials. Research cases reported above thus demonstrate the potential of a Py-GCxGC/MS approach in the characterisation of cultural heritage materials, making it relevant for the study of complex samples in general, and extending beyond the field of cultural heritage.

[1] Shedrinsky, A.M. et al. J. Anal. Appl. Pyr. 15, 393 (1989). [2] Mondello, L. et al. Nat Rev Methods Primers 5, 7 (2025). [3] Han, B. et al. J. Anal. Appl. Pyr. 122, 458 (2016).

ABSTRACT. Cyclohexanone (ketone) resins were first used as a substitute for natural resins by conservators and artists in the early 1940s at the latest. These synthetic resins were low–molecular weight oligomeric compounds, produced by condensation reactions involving cyclohexanone, and, sometimes, methylcyclohexanone and formaldehyde with an alkaline catalyst. These reactions led to amorphous products with unknown exact chemical structures. First formulations were patented in 1918 by BASF and produced as “AW2” between 1930–1967. This was later substituted by “Keton Resin N” (1967–1980) and then “Laropal K80” (1980–2014). The first hydrated – and thus more stable – ketone resins were introduced in the late 1950s (“MS2A” by Howards). This study presents evolved gas analysis-mass spectrometry (EGA-MS) and double-shot pyrolysis -gas chromatography mass spectrometry (DS-Py-GC/MS) results of several type of ketone resins, namely “AW2”, “MS2A” and “Keton Resin N”, with the aim to identify the principal markers characteristic for each type of resin. Sixteen different cyclohexanone resins dating from the 1950s to the 1980s (as well as undated samples) were investigated. The EGA-MS provided thermal decomposition profiles of the resins enabling a first categorization of the resin types in particular in the first part of the thermogram (until 300 °C), corresponding to the desorption of the oligomers. Further characterization of these fractions was carried out by DS-Py-GC/MS. In the thermal desorption step peaks corresponding to monomers, dimers and trimers, were detected. Among the “AW2” samples, two main resin groups were recognized, which presented similar monomer markers (such as as cyclohexanol, 2-methylcyclohexanol and 3-methylcyclohexanol), but distinct dimers. The first group (AW2-g1) has dimer markers with characteristic ions m/z 98, 194, 212 and m/z 98, 111, 192, 210, while the second group (AW2-g2) has markers with m/z 95, 111, 206 and m/z 95, 125, 220, 238. Within these major AW2 groups, heterogeneities could be detected which require further investigation. The “MS2A” samples presented a characteristic monomer fraction composed by 4-methylcyclohexanol and 4-methylcyclohexanone and a dimer fraction characterized by the markers 4-methyl-2-(5-methylcyclohex-1-enyl)cyclohexanol, 2,2´-methylenebis(4-methylcyclohexanol) and 2-((2-hydroxy-5-methylcyclohexyl)methyl)-4-methylcyclohexanone. The “Keton Resin N”, which is composed only of cyclohexanone, was characterized by cyclohexanol in the monomer fraction. The dimer fraction had peaks with m/z 98, 194, 212 ions as the main marker, followed by those with m/z 133, 162, 180, m/z 111, 192 and m/z 98, 111, 192, 210 ions. In the second step of the DS-Py-GC/MS, a division into monomer, dimer and trimer pyrolysis products was also observed for each resin, with the markers 3-methylenecyclohexene and the compound with m/z 93, 108 ions for the resins “AW2” and “MS2A”, respectively. However, in general the resulting pyrograms were complex and did not provide additional information compared to thermal desorption. This study enabled the distinction of different groups of cyclohexanone resins, primarily through the characterization of their volatile fractions, which can support the identification and categorization of previously uncharacterized samples. “AW2” resins were shown to consist of several distinguishable groups, which eventually might become attributable to different procedures of productions, companies or decades.

ABSTRACT. Evolved Gas Analysis Mass Spectrometry (EGA-MS), Double Shot pyrolysis GCMS (DS-py-GCMS) and Fourier Transform Infrared Spectroscopy (FTIR) were performed on polyester urethane (PU-ES) closed-cell foam samples after artificial ageing (70 °C and 98 %RH for up to 56 days) in 2017. A convolute of samples that had not been artificially aged in 2017, instead undergoing natural ageing until 2025, were then artificially aged for up to 49 days and analysed with the same techniques. Similar, but naturally aged material from the 1980s-90s was also available. The aim of the study was to verify proposed markers for degradation, namely adipic acid and 4,4’-methylenebisbenzeneamine (MDA) [1], which could enable an evaluation of the current state of degradation of a given material, as well as to identify further potential markers for this purpose. A systematic approach allowed bringing to light several repeatability issues in DS-py-GCMS [2]. These seemed to affect species with COOH groups. For example, MDI and adipic acid only occurred simultaneously in 25 % of all measurements of comparable material; in the rest of the measurements, either 4,4'-diphenylmethane diisocyanate (MDI) or adipic acid appeared. Several possible causes were identified for this, most importantly, high temperatures in combination with the appearance of highly reactive species such as MDI that seem to be further reacting with species appearing upon degradation [3, 4]. As a consequence, MDA seems not to be a suitable marker for degradation for carbamate hydrolysis, since it could be appearing as an artifact in the pyrolysis chamber due to secondary reactions of MDI. The comparison of the EGA-MS results between the measurements performed after artificial ageing in 2017 and in 2025 highlighted chemical changes in the material due to natural indoor ageing. These changes are observed in the final stages of artificial ageing after 49 and 56 days, but not for smaller periods.

[1] A. Lattuati-Derieux, S. Thao-Heu, B. Lav´edrine, Assessment of the degradation of polyurethane foams after artificial and natural ageing by using pyrolysis-gas chromatography/mass spectrometry and headspace-solid phase microextractiongas chromatography/mass spectrometry, J. Chromatogr. A 1218 (2011) 4498–4508, https://doi.org/10.1016/j.chroma.2011.05.013. [2] S. Kunz, S. Brunner, J. Köppen, E. Rettler, E. Bresolin, I.D. Gaudio, B. Staal, T. Gruendling, E. Gómez-Sánchez, Comparative study of the artificial and natural, indoor ageing of crosslinked, polyurethane ester closed-cell foams, Polymer Degradation and Stability 245 (2026) 111905. https://doi.org/10.1016/j.polymdegradstab.2025.111905. [3] H. Ohtani, T. Kimura, K. Okamoto, S. Tsuge, Y. Nagataki, K. Miyata, Characterization of polyurethanes by high-resolution pyrolysis-capillary gas chromatography, J. Anal. Appl. Pyrolysis 12 (1987) 115–133. [4] M. Matsueda, M. Mattonai, I. Iwai, A. Watanabe, N. Teramae, W. Robberson, H. Ohtani, Y.-M. Kim, C. Watanabe, Preparation and test of a reference mixture of eleven polymers with deactivated inorganic diluent for microplastics analysis by pyrolysis-GC–MS, J. Anal. Appl. Pyrolysis 154 (2021) 104993, https://doi.org/10.1016/j.jaap.2020.104993.

ABSTRACT. The Oddy test remains the standard approach to determine the suitability of a material for use in the display or storage of artwork. In this test, volatile pollutants emitted from a test material react with lead, silver, and copper metal coupons under conditions of elevated temperature and humidity. If corrosion is noticed after a 28-day incubation, the material is classified as unsuitable for use in a museum environment. While simple to perform, this test is limited due to the subjective nature of evaluating the metal coupons for corrosion as well as by its focus on only metal reactivity in the presence of a pollutant; a pollutant that may corrode metals may or may not have a similar deleterious effect on non-metal art materials.

Newer methods like direct thermal desorption – gas chromatography – mass spectrometry (DTD-GC-MS) have been explored to establish a more objective approach to material suitability testing. Chemical information such as the identity and, with calibration, concentration of volatile organic compounds (VOCs) can be used to understand reactivity of emitted pollutants toward a variety of artists’ materials. However, these methods often rely on some inherent knowledge of chemical reactivity – what we call “chemical intuition” – to decide if a detected VOC is a pollutant that will negatively impact an artwork. Efforts are underway to develop material-specific suitability tests to run in tandem with a traditional Oddy test. One example relies on the exposure of a paper surrogate to potential pollutants emitted from a test material for 14 days at elevated temperature and humidity. Under these conditions, the cellulose and hemicellulose components of the surrogate undergo catalyzed hydrolysis and liberate monosaccharide degradation products that are extracted from the paper and detected using ion chromatography or colorimetric assays.

In this work, we will present the results of our efforts to use pyrolysis – gas chromatography – mass spectrometry (PY-GC-MS) to observe directly the degradation products formed from the exposure of a paper surrogate to potential pollutant molecules in a paper-based material suitability test. Monosaccharides formed from the degradation of the paper surrogate are converted into trimethylsilyl derivatives using BSTFA to increase volatility and ease of detection using a GCMS system. Three different analysis protocols will be discussed: (1) offline solution-phase derivatization of extracted monosaccharides using BSTFA; (2) direct derivatization of extracted monosaccharides using BSTFA in the PY furnace; (3) generation of volatile derivatized monosaccharides directly from the paper surrogate in the PY furnace without prior extraction. The goal of the work is to produce a rapid and quantitative method for analysis of monosaccharides to support material suitability testing for paper-based collections. Results from material suitability testing will be discussed and compared with a standard colorimetric analyses.

Figure 1: Analysis scheme for detection of arabinose from aged paper

ABSTRACT. In the field of cultural heritage, silk is a highly valued material, appreciated since the Chinese Empire. Silk is a proteinaceous fibre inherently delicate which becomes brittle and fragile with ageing. The preservation of silk artefacts requires not only the development of conservation and cleaning methodologies that minimize their impact on the material, but also a thorough understanding of the degradation processes involved.

Building on previous applications of EGA-MS to proteinaceous materials [1], [2], this approach was applied to investigate the molecular modifications occurring during silk ageing. Upon progressive heating, the EGA-MS profile of silk shows a main degradation peak at approximately 330 °C, followed by a shoulder at around 390 °C. The first degradation peak is unexpectedly dominated by the m/z 107 ion, traditionally attributed to methylphenol. Although this ion may be associated with the pyrolysis of tyrosine, its high abundance is difficult to reconcile with the low tyrosine content of silk fibroin (~5%), suggesting a possible contribution from secondary pyrolytic reactions promoted by progressive heating during EGA-MS. Compared to aged silk, aged samples exhibited a marked decrease in thermal stability and a variation in the abundance of the ion m/z 107.

To clarify the formation pathway of methylphenol, two complementary experiments were performed using Py-GC-MS coupled with a cryotrap: a single-shot flash pyrolysis at 350 °C and a progressive heating experiment from 50 °C to 350 °C at a rate of 10 °C/min (same used for EGA-MS experiments). The comparison of the relative abundance of the m/z 107 ion under the two experimental conditions demonstrates that methylphenol is not a secondary product formed during progressive heating but rather a primary pyrolysis product of tyrosine. Variations in the m/z 107 signal observed in the first EGA peak of aged silk can therefore be directly related to modifications of tyrosine occurring during ageing.

This study demonstrates how Py-GC-MS coupled with a cryotrap under controlled progressive and instantaneous heating conditions enables the discrimination between primary and secondary pyrolysis products in silk, improving the interpretation of molecular pathways from EGA-MS data for proteinaceous materials.

[1] S. Orsini, C. Duce, and I. Bonaduce, “Analytical pyrolysis of ovalbumin,” J. Anal. Appl. Pyrolysis, vol. 130, pp. 249–255, Mar. 2018, doi: 10.1016/j.jaap.2018.01.026.

[2] F. Sabatini, T. Nacci, I. Degano, and M. P. Colombini, “Investigating the composition and degradation of wool through EGA/MS and Py-GC/MS,” J. Anal. Appl. Pyrolysis, vol. 135, pp. 111–121, Oct. 2018, doi: 10.1016/j.jaap.2018.09.012.

ABSTRACT. As an analytical method designed for polymer analysis, online pyrolysis had been explored for its practical application as early as 1950s and was quickly applied in cultural heritage and archaeology studies. Since then, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has been widely used for the characterization of organic materials used in artworks and archaeological samples. Also, Py-GC/MS is among the most frequently used techniques for archaeological organic residue studies due to its ability to provide information on their molecular structure. In archaeological research practice, pyrolysis is a way to permit the analysis of archaeological organic residue by GC/MS with minimum quantity and a simple sampling process. We have explored an approach based on the use of the coupling of pyrolysis, gas chromatography and mass spectrometry (Py-GC/MS) to screen potential biomarkers in organic residue to reveal their composition and further implications in social use and meanings in antiquity. For instance, potential vegetation biomarkers such as certain terpenes, lignin monomers, sesamin, miliacin can be easily screened by pyrolysis aiding material identification in archaeometry studies. A review of research cases in our group, as well as other groups for organic residue analysis in China, confirm the efficiency and usefulness of analytical pyrolysis for promotion of organic residue analysis in Chinese archaeological practice.

ABSTRACT. This study investigated the apparent global kinetic parameters governing biochar formation during the fast pyrolysis of main biomass components isolated from Zea mays. The cellulose, hemicelluloses, and lignin fractions were obtained through an isolation process to allow individual component analysis. Controlled fast pyrolysis experiments were carried out in a micropyrolyzer coupled with GC-MS/FID at temperatures between 300 and 500°C, and the global kinetic parameters were determined using a single-step and first-order global reaction model. The Evolved Gas Analysis (EGA) was used to estimate pyrolysis times and determine the pre-exponential factors. The kinetic parameters obtained were E = 18.63 kJ mol⁻¹ and A = 0.409 s⁻¹ for lignins; E = 20.55 kJ mol⁻¹and A = 0.648⁻¹ for hemicelluloses; and E = 105.98 kJ mol⁻¹, A = 6.04 × 106 s⁻¹ for cellulose. Because of methodological differences, the direct comparison of our kinetic datasets with literature was not straightforward. However, numerical modelling using a new lumped and distributed activation energy model [1] allowed the validation of experimental final biochar yields (Figure 1) and indirectly the measured overall and global kinetics. [1] Mercier, Z., Carrier, M. & Marias, F. Lumped and distributed activation energy modelling of biomass pyrolysis. Chemical Engineering Journal Advances 25, 100998 (2026).

ABSTRACT. The pyrolysis of lignocellulosic biomass represents a key technology for the sustainable production of biofuels and bio-based materials. However, the molecular-level understanding of biomass thermal decomposition remains incomplete, limiting the development of predictive kinetic models. Hemicellulose, and in particular xylan, plays a crucial role in biomass pyrolysis, yet its intrinsic reactivity and decomposition chemistry are still poorly understood. This work aims to elucidate the pyrolysis mechanisms of representative xylan molecular constituents, xylopyranose, xylobiose, and xylotriose, through a combined computational, experimental, and kinetic modeling approach. Reaction pathways will be systematically explored using the automated reaction discovery program AutoMeKin[1] coupled with semiempirical molecular dynamics, followed by high-level quantum chemical refinement of all stationary points. Accurate thermochemical and kinetic parameters will be obtained using density functional theory and DLPNO-CCSD(T)-F12 calculations, combined with RRKM/transition state theory to derive temperature-dependent rate coefficients relevant to fast pyrolysis conditions. Solvent effects will be evaluated using a polarizable continuum model to support condensed-phase kinetic applications. Experimentally, the thermal behavior of the selected mono-, di-, and tri-saccharides will be characterized using thermogravimetric analysis coupled with FTIR spectroscopy, complemented by Py-GC/MS micropyrolysis experiments to identify and quantify primary volatile products. Additional laboratory-scale pyrolysis tests will provide gas, liquid, and solid product characterization [2]. These datasets will enable direct validation of the computational reaction mechanisms and kinetic parameters. The experimental and theoretical results will be integrated into a semi-detailed chemical kinetic model describing the pyrolysis of xylan constituents [3]. The model will be hierarchically extended from xylopyranose to xylobiose and xylotriose and coupled with an existing gas-phase kinetic framework. Using molecular group additivity concepts, the model will provide a foundation for describing the pyrolysis of real xylan polymers and hemicellulose in softwood and hardwood biomasses. This integrated methodology will deliver a mechanistically consistent and predictive kinetic model, offering new insights into hemicellulose pyrolytic reactivity and supporting the development of more reliable biomass pyrolysis simulations.

[1] Martínez‐Núñez, E.; Barnes, G. L.; Glowacki, D. R.; Kopec, S.; Peláez, D.; Rodríguez, A.; Rodríguez‐Fernández, R.; Shannon, R. J.; Stewart, J. J.; Tahoces, P. G.; Vazquez, S. A. AutoMeKin2021: An Open‐Source Program for Automated Reaction Discovery. J. Comput. Chem. 2021, 42, 2036–2048.

[2] Ferreiro, A. I.; Giudicianni, P.; Grottola, C. M.; Rabacal, M.; Costa, M.; Ragucci, R. Unresolved Issues on the Kinetic Modeling of Pyrolysis of Woody and Nonwoody Biomass Fuels. Energy Fuels 2017, 31, 4035–4044.

[3] Ranzi, E.; Debiagi, P. E. A.; Frassoldati, A. Mathematical Modeling of Fast Biomass Pyrolysis and Bio‐Oil Formation. Note I: Kinetic Mechanism of Biomass Pyrolysis. ACS Sustainable Chem. Eng. 2017, 5, 2867–2881.

ABSTRACT. Carbon-based resources include traditional fossil energy sources (coal, oil shale, crude oil is its derived heavy oil), renewable/waste energy sources (biomass, waste plastics, municipal sludge) and light oils, etc. The radical reaction network triggered by the cleavage of covalent bonds in the molecular structure of carbon-based resources dominates the distribution characteristics of gas, liquid, and solid products. However, limited by experimental techniques to observe the real-time reaction process, most experimental studies can only determine the apparent synergistic effects by comparing pyrolysis behavior, product distribution and yields of characteristic compounds, which lacks in insights for building the detailed multi-channel reaction pathways among different feedstocks and pyrolyzates in solid and liquid phases. The combination of reactive force field (ReaxFF) that based on bond order concept and molecular dynamics (MD) can continuously describe the interatomic formation and bond breaking evolution of the reaction system without pre-designing the reaction pathways. In order to reach spatio-temporal scales of nanometers and nanoseconds for complex systems, the first graphics processing unit (GPU) enabled ReaxFF MD software, GMD-Reax, was created, both for the increase of system size and acceleration of ReaxFF MD running on desktop workstations. Any possible care has been taken in the implementation to have the ReaxFF algorithms mapped to the proper organization of GPU treads and data structures. In this work, the thermal characteristics of carbon-based fuels were evaluated under pyrolysis and catalytic pyrolysis conditions by using the large-scale ReaxFF MD simulation rooted in high-performance computing and cheminformatics-based reaction analysis. For example, the blend models containing six mixtures of polymers (polyethylene, polypropylene, polystyrene) and biomass (cellulose, hemicellulose and lignin) were constructed for the first time, which is close to the real utilization of waste materials. A unique ReaxFF MD simulation strategy for decoupling pyrolysis stage formation and char formation stage was carried out to obtain char-like structures with acceptable computational cost. ReaxFF MD simulation results indicate that the polymer would promote biomass pyrolysis at low temperature, while biomass would delay polymer decomposition at high temperature. Co-pyrolysis does not generate new species, but greatly affects the product yields through interactive reactions of hydrogen transfer and hydroxyl transfer, where more oxygen-containing oils are produced with the aid of polymer providing hydrogen atoms. Since oxygen-containing functional groups in biomass provide the initial cross-linking sites to produce large fragments, the formation of char precursors is reduced significantly with polymer addition. As compared to pyrolysis of only binary components, the observed qualitative synergistic results in co-pyrolysis of biomass-polymer mixtures provide important insights into the detailed reactions for co-pyrolysis process, which can complement experimental observations to modulate the nature and yield of the desired bio-oils and bio-chars.

ABSTRACT. The biomass/plastic fast pyrolysis fluidized bed reactor is a typical complex reaction system characterized by multiphase, multicomponent, and multiscale interactions. This presentation presents the research progress of our team in multiscale modeling, artificial intelligence, and experimental validation of thermochemical conversion reactors for biomass/plastic. Using high-speed photography and machine learning-based image processing methods, we investigated the multicomponent fluidization phenomena in biomass fast pyrolysis fluidized bed reactors. A machine learning-based drag force model was developed to study the fluidization behavior of biomass and quartz sand mixtures and their segregation. An interpretable pyrolysis kinetics model based on neural networks was constructed to optimize the parameters of the pyrolysis kinetics model. A machine learning-accelerated discrete particle simulation algorithm was developed to enable fast and accurate discrete particle simulations. The SuperDEM solver for non-spherical particle simulations was created, allowing large-scale parallel simulations of discrete particles and studying the fluidization phenomena of non-spherical particles. A multiscale modeling framework was established to couple complex reaction kinetics models, intraparticle transport-reaction models, and fluidized bed reactor models, enabling the simulation, optimization, and scale-up of biomass/plastic fast pyrolysis fluidized bed reactors.

ABSTRACT. Pyrolysis provides a promising saccharification method for cellulose, a main component of woody and herbaceous biomass, as it produces large amounts of levoglucosan (1,6-anhydro-beta-D-glucopyranose, LG), which can be hydrolyzed into glucose under mild conditions. However, the reaction mechanism and kinetic behavior of cellulose pyrolysis remain unclear due to variations in thermal reactivity among cellulose samples and the presence of a crystalline structure that includes paracrystalline regions. In contrast, our group has shown that metal-cation-exchanged cellulose exhibits distinct thermal reactivity, with alkaline earth metal salts promoting cellulose decomposition at temperature approximately 30℃ lower than those of alkali metal salts. In this study, a partially deuterated cellulose—where only regions inaccessible to water in aqueous suspension were deuterated—was employed to elucidate the thermal reactivity of crystalline region. This sample enabled a clear distinction between the reactivity and product selectivity of accessible and inaccessible regions using TG–MS analysis. This study further investigated how metal cations influence the pyrolysis behavior of cellulose. The deuterated cellulose sample was prepared by heating Whatman No.42 cellulose in deuterium oxide (D2O) at 220℃ for 5 minutes, then washing with purified water and freeze-drying. Metal-cation-exchanged cellulose was prepared by immersing the deuterated cellulose sample in a 0.05 M metal acetate solution (Na+, K+, Ca2+, Mg2+) at room temperature, followed by washing with purified water and drying at 105℃. These samples were analyzed by TG-MS. TG-MS analysis of deuterated cellulose sample revealed that D2O was released at higher temperatures than H2O, and that LG was preferentially formed in association with D2O. These results indicate that the accessible regions of cellulose have lower thermal stability, whereas LG originates primarily from the more stable inaccessible regions, likely located within the crystal core. In metal-cation-exchanged cellulose, a similar tendency was observed: D2O and LG were produced at higher temperatures than H2O. However, the onset temperatures of D2O and LG varied depending on the type of metal cation. To evaluate the effects of metal cations on the production temperature of each product—H2O, fragmentation products (FP) such as glycolaldehyde, CO2, D2O, LG, furfural (FF), and 5-HMF—“onset temperature” was defined as the temperature at which the signal intensity reached 3% of the maximum peak intensity”. H2O, FP, and CO2 were produced at lower temperatures than D2O, indicating that these products originate from accessible regions. Their onset temperatures were nearly identical across different metal cations, expect for Mg2+. In contrast, LG, FF, and 5-HMF were produced at higher temperatures than D2O, suggesting that these compounds form after reactions in the crystalline core have progressed. Furthermore, their onset temperatures differed depending on the metal cation, with reactivity following the order: Mg2+ > Ca2+ > Na+ ≈ K+. Since the cation-exchange treatment was performed at room temperature, metal cations are localized only in the accessible regions of cellulose. These results indicate that metal cations in the accessible regions alter the thermal reactivity of the crystalline core.

Figure caption: Image of cellulose containing paracrystalline regions and cations.

ABSTRACT. Pyrolytic conversion is a key biomass valorization route, capable of producing platform biomolecules for sustainable energy and a wide range of bioproducts. Lignocellulosic biomasses are complex composite materials where cellulose, hemicellulose, and lignin are interconnected through covalent and hydrogen bonds in a three-dimensional structure. These component interactions strongly influence conversion dynamics, product distribution and decomposition kinetics. To investigate these aspects, physical or native mixing approaches are commonly employed. However, physical mixing ignores real biomass structure, while native mixing offers better insights but is limited by structural changes from harsh pretreatments (1). To account for mutual interactions and overlapping degradation ranges of natural constituents, further influenced by the presence of alkali metals and non-structural components, kinetic modelling for the thermal degradation of lignocellulosic materials relied on pseudo-components, representing lumped volatile fractions. However, pseudo-components lack physical meaning and their composition is widely variable depending on the mathematical treatment of the experimental data, leading to significant variability in kinetic parameters even for standard biomasses such as wood. This study introduces an innovative kinetic description of wood decomposition based on natural components rather than artificial pseudo-components (1,2). First, non-invasive wood pretreatments (washing and washing-torrefaction) are applied to reduce overlap in the decomposition ranges of hemicellulose, cellulose, and lignin, and produce binary mixtures without severe structural alterations. A five-step devolatilization mechanism is then formulated, and kinetic parameters are estimated using a model-fitting techniques applied to thermogravimetric curves under varying heating conditions of the obtained native mixtures for both hardwood (beech wood) and softwood (fir wood). The introduction of natural components, in terms of quantity, properties and mutual interactions has permitted the formulation of a new kinetic model for the primary decomposition of wood which owns a physical meaning and shows greater validity and applicability. Results reveal that natural components decompose differently from isolated or model compounds. For instance, interactions and synergies among components consistently lead to char yields significantly lower (factors around 2-3) than those observed from model compounds or chemically isolated compounds, along with remarkable different conversion dynamics.

References 1) Analysis of component interaction in beech wood pyrolysis by native mixing with mildly invasive pretreatments, Branca, C., Di Blasi, C., Journal of Analytical and Applied Pyrolysis, 187 (2025). 2) Pretreatments and model fitting to identify in-situ decomposition of fir wood constituents, Branca, C., Di Blasi, C., Journal of Energy Institute, 119 (2025)

ABSTRACT. This study investigates the pyrolytic decomposition of a nitrochitosan (NCS)-based energetic composite plasticized with diethylene glycol dinitrate (DEGDN, 50:50 w/w). FTIR analysis confirmed that the characteristic functional groups of NCS and DEGDN were preserved, indicating a physical mixture without new chemical bonds. Thermal behavior was studied by differential scanning calorimetry under nitrogen atmosphere using 1–2 mg samples heated from 50 °C to 350 °C at 10, 15, 20, and 25 °C/min. DSC revealed two consecutive exothermic events: a low-temperature peak at 132.1 °C attributed to N–NO₂/O–NO₂ bond cleavage, followed by a broader high-temperature peak at 198.1 °C corresponding to polymer main chain decomposition. The total heat released was 2462 J·g⁻¹. Kinetic analysis of deconvoluted DSC data was performed using TAS, it‑KAS, and Vyazovkin isoconversional methods. The average activation energies were ~68 kJ·mol⁻¹ for the first stage and ~140 kJ·mol⁻¹ for the second stage. These results provide mechanistic insight into the pyrolytic decomposition pathways of nitro-polysaccharide energetic materials, supporting their potential application in propellant formulations and other energetic systems.

ABSTRACT. Given its nature, bio-oil from lignocellulosic biomass pyrolysis is a promising source of both biofuels and biochemicals, even if it often needs further processing after its production. The high content of oxygenated species and the complex physical-chemical equilibrium of the whole bio-oil system makes the material unstable. During storage, bio-oil undergoes a series of chemical reactions that progressively alter its physical properties and chemical composition; this phenomenon is commonly referred to as bio-oil aging. Bio-oil obtained from slow pyrolysis, which is typically optimized for biochar production tailored to specific applications, has been far less investigated than bio-oil produced under fast pyrolysis conditions. Although bio-oil obtained under slow pyrolysis conditions has long been regarded as a low-value by-product, it has recently attracted increasing attention as a potential feedstock for the production of bio-based materials and, in some cases, for energy applications. Consequently, a proper understanding and assessment of its aging behavior during storage has become increasingly important. Slow pyrolysis bio-oil composition differs from fast pyrolysis bio-oil in terms of chemical species distribution and, in particular, it has a higher water content usually ranging between 40 and 60 %. The high water content of slow pyrolysis bio-oils can easily cause the phase separation of the whole bio-oil in an aqueous and an oily phase. However, phase separation can be considered from a different perspective as a strategy for the further valorization of this type of liquid. Indeed, centrifugation after water addition is a low-cost and environmentally friendly method for achieving effective phase separation. This process allows the separation of an aqueous phase, enriched in low molecular weight polar compounds such as carboxylic acids, ketones, and sugars, from an oily fraction that is nearly water-free and contains heavier, less polar and more aromatic compounds. Due to their differing composition and water content, the two phases are expected to exhibit different aging behaviors. This work aims to assess the influence of phase separation on slow pyrolysis bio-oil aging, considering how the chemical composition of the whole bio-oil and of the two phases, aqueous and oily, changes over a storage time of 145 days. Bio-oil produced from the slow pyrolysis of poplar at 600°C is generated in a lab-scale fixed bed reactor and subjected to characterization and phase separation through water addition and centrifugation. Samples of the whole bio-oil and of the two separated phases were stored at room temperature or refrigerated at 4 °C, aiming to evaluate how the storage temperature can affect aging. The primary organic species in all bio-oil samples (whole bio-oil, aqueous fraction, and oily fraction) were identified and quantified using GC-MS analysis and grouped into classes (carboxylic acids, ketones, phenols, etc.). All samples were analyzed repeatedly throughout the storage period. The results reveal an initial phase characterized by pronounced fluctuations in the concentrations of the identified compounds, followed by a general decrease after storage times exceeding 20 days. Storage temperature influenced only selected compound classes, with noticeable effects observed mainly for furans.

ABSTRACT. The catalytic reductive amination of aldehydes and ketones derived from lignocellulosic biomass represents a sustainable alternative to petrochemical-based amines. In this context, the amination of furfural (FUR) with aniline has attracted increasing attention due to its renewable origin and industrial relevance. However, reductive amination involves two reaction steps that require acidic and metallic sites: (i) Imine formation and (ii) subsequent C=N bond hydrogenation to produce furfuryl aniline (FFA). Pd/ZrO₂–TiO₂ catalysts are attractive for this reaction due to their bifunctional nature, combining Lewis-acid sites and metallic Pd⁰ domains. In this system, the imine may interact with the catalyst surface through σ-type coordination via the nitrogen lone pair to Lewis-acid sites, while hydrogen activation occurs on Pd⁰. The balance between these interactions strongly affects reaction selectivity. Herein, we assess the bifunctional role of Pd/ZrO₂–TiO₂ catalysts in furfural reductive amination by decoupling acidity and metal particle size effects. In a first catalyst series, Zr loading on TiO₂ was varied between 0 and 25 wt.% to tune Lewis’s acidity while preserving comparable textural and structural properties. Catalytic performance was evaluated in terms of turnover frequency (TOF), imine conversion, product selectivity, and catalyst stability. The most active support composition was subsequently selected to prepare a second catalyst series with controlled Pd nanoparticle sizes (2–20 nm), enabling the assessment of structural sensitivity. Catalysts were characterized by XRD, TEM/HRTEM, N₂ physisorption, CO-Chemisorption, NH₃-TPD, FTIR-pyridine, H₂-TPR, ICP-OES, and XPS. Catalytic tests were conducted between 30 and 100 °C under 5 bar H₂ using equimolar furfural and aniline solutions. Regardless of Zr loading, all catalysts exhibited similar textural and structural properties, including specific surface areas (SBET = 35–56 m² g⁻¹), mesoporosity, and predominant anatase TiO₂ phases. In contrast, acidity characterization revealed that Zr incorporation selectively strengthened Lewis’s acid sites without significantly altering the total acid site density (5.0–8.7 µmol NH₃ m⁻²). Secondary amine selectivity and TOF showed no clear correlation with bulk acidity; however, maximum FFA selectivity (~60%) and TOF (6.7 s-1) were achieved for Pd/(15 wt.%) ZrO₂–TiO₂, which exhibited the a weak-to-total Lewis’s acid site ratio (W/T = 3). This suggests that σ-type coordination of the imine on moderately strong Lewis sites favors selective hydrogenation, whereas stronger acidity leads to excessive stabilization of reaction intermediates, in agreement with Sabatier’s principle. For the catalysts with different particle sizes, we found that the TOF (measured under initial conditions) increased from 1.5·10-3 s-1 to 2.5·10-1 s-1 for catalysts with 14.1 and 60% Pd dispersion respectively. Assuming an icosahedron structure, the outperformance of 60% dispersion Pd is correlated with its higher fraction of low-coordinated sites (>90% Edge+Corner) and demonstrate that FUR amination is sensitive to the structure. The pronounced structure sensitivity, together with the weak dependence on total acidity, indicates that the rate of furfural reductive amination is controlled by the initial hydrogenation of the imine coordinated to Lewis-acid sites. This step, involving σ-activated imines and hydrogen transfer from coordinatively unsaturated Pd sites, constitutes the kinetically relevant step of the reaction.

ABSTRACT. This study compares the pyrolysis behaviour of sugar bagasse in a pressurised fixed-bed reactor. The effects of temperature, heating rate and pressure were studied. The primary objective of this study was to investigate the feasibility of enhancing the selectivity of high-value-added products, including H-rich syngas, activated carbon, and other chemical raw materials, at high pressures. The pyrolysis temperature and pressure ranged between 400-700 ℃ and 0.1-1.6 MPa, respectively. Temperature, heating rate and pressure were found to dramatically impact the yield and composition of pyrolysis products. The secondary reaction pathways and elemental transformation mode during pyrolysis were also investigated. The results showed that, for sugarcane bagasse, the concentration of H2 in the gas fraction increased drastically with pyrolysis temperature, heating rate and pressure, which indicated that those parameters enhanced the transfer of hydrogen from char and tar into the gas phase. Tar samples generated at the tested conditions were mainly composed of sugars, phenols, and other oxygenated compounds. While pressure and temperature promoted the formation of Polycyclic aromatic hydrocarbons (PAHs), they were suppressed at higher heating rates due to shortened residence time for secondary reactions, such as cyclisation, aromatic ring growth mechanism and other polycondensation reactions. The results obtained in this study implied that the pyrolysis of sugarcane bagasse at elevated pressures and heating rates can be an effective method for poly-generation of hydrogen-rich syngas and other chemical feedstocks.

ABSTRACT. This study focuses on the development and characterization of novel carbon-based adsorbents derived from animal manure for the removal of azo dyes from aqueous solutions. Biochar was prepared from camel manure by torrefaction at 300 °C under oxygen-free conditions. The resulting material was subsequently chemically activated with sulfuric acid and modified with Fe²⁺/Fe³⁺ ions to enhance its surface properties and adsorption performance. The prepared adsorbents were characterized using Fourier-transform infrared spectroscopy (FTIR), zeta potential measurements, and scanning electron microscopy (SEM) to evaluate changes in surface functional groups, surface charge, and morphology. The adsorption performance of both non-activated and activated biochar was investigated using Congo red as a model anionic dye. Adsorption experiments were conducted under batch conditions, and equilibrium data were evaluated using the Langmuir adsorption isotherm model. The results showed that chemical activation and iron modification led to a significant increase in adsorption capacity, from 48.4 mg g⁻¹ for non-activated biochar to 77.2 mg g⁻¹ for the activated and modified material. The enhanced adsorption performance was attributed primarily to the change in surface charge, as the zeta potential shifted from −31 mV to +12 mV after activation, increasing the affinity of the adsorbent toward negatively charged dye molecules. The findings demonstrate that biochar derived from animal manure, especially after appropriate activation and modification, represents a promising low-cost and sustainable adsorbent for the removal of anionic pollutants from wastewater. In addition, non-activated biochar with a negative surface charge may be suitable for the adsorption of positively charged contaminants, such as heavy metal cations.

ABSTRACT. Various types of renewable lignocellulosic biomass are a common source of carbon and are of great interest as a precursor to various carbon materials and a source of green energy . Efficient valorisation of biomass and its by-products has set the task for scientists and the industrial community to use them for the development of cheap and environmentally friendly functional materials with high added value. The presence of carbohydrates and aromatic polymers in the biomass allows obtaining carbon materials and precursors for their synthesis of various structures, and the flow of by-products can be used to synthesize chemicals , . Carbonaceous materials play a promising role in the energy sector due to their unique properties such as high surface area, good electrical conductivity and corrosion resistance .

Various types of biomass carbonization have a great potential to become an eco-friendly process for producing carbon products for environmental, catalytic, electronic and agricultural applications. Hydrothermal carbonization (HTC) is an environmentally friendly technology for producing solid carbon material, e.g. hydrochar, with attractive properties, as well as water-soluble products of biomass components hydrolysis. The aim of this study is to investigate the effect of the composition of different biomass derivatives (anhydrosugars and lignin) on the morphology and properties of solid products and composition of liquid products obtained in the process of HTC. The study of processing of these model derivatives will contribute to the understanding of the reaction mechanisms of the synthesis processes. Hydrothermal carbonization will be carried out in a 250 ml high pressure autoclave. After separation the carbonized solid particles will be studied by elemental analysis, Py-GC/MS and SEM. Liquid by-products will be tested by potentiometric titration of acids and aldehydes, spectrophotometric analysis, GC-FID/MS and HPLC-UV/ELSD/MS.

The research was funded by project lzp-2024/1-0525 “Lignin-containing products for synthesis of N-doped carbon microspheres as electrochemical catalyst and electrode materials (LIGsp)”

ABSTRACT. This study investigates the synthesis and characterization of nitrochitin (NCT), a promising energy-rich biopolymer derived from chitin. The nitration process was adapted from previous work on nitrochitosan. The chemical structure and morphology of NCT were analyzed using infrared spectroscopy, elemental analysis, scanning electron microscopy, and X-ray diffraction. Thermal behavior was evaluated by differential scanning calorimetry, revealing two consecutive decomposition events between 135–185 °C and 192–244 °C. The designed NCT (nitrogen content = 13.63%) demonstrated notable properties, including a higher crystallinity index compared to the conventional nitrocellulose, a density of 1.71 g/cm³, a nitrogen content of 13.63%, and an impact sensitivity of 18 J. These results highlight the significant potential of NCT for use in energetic formulations.

ABSTRACT. Droppings of four ZOO animals (giraffe, deer, camel, reindeer) and a sample of pellets of zebra manure were torrefied at 250°C and 300°C to study their potential as an alternative fuel. Combustion calorimetry and thermal (DTA/TG) analysis were used to quantify heating parameters and dynamics of the combustion process of the biomass materials, respectively. Marked increase in heating values of torrefied droppings was found, by about 20% in comparison with non-torrefied, original state. However, differences between heating values of the samples torrefied at 300°C and 250°C were rather insignificant.

ABSTRACT. Fast pyrolysis is widely employed for bio-oil production, yet the efficient utilization of its solid and condensable by-product remains a challenge. It is desirable to valorize the char but it lacks the essential surface properties needed for high-value applications. The aim of this study is to develop an integrated post-pyrolysis activation reactor that valorizes fast pyrolysis by-products and yields a high-quality activated biochar. No studies so far, have reported the utilization of pyrolysis by-products as biochar activation agents. Biochar from wheat straw and beechwood will be activated using liquid and gaseous by-products of pyrolysis and will then be characterized using surface and functional techniques. The integrated activation is expected to enhance the surface characteristics of the biochar produced in the pyrolysis unit, demonstrating the feasibility of this approach. This approach will omit the need for additional inputs (both material and less energy) for activating the biochar being produced in the fast pyrolysis process. Moreover, it will provide an economically feasible alternative to the field burning of the harvest residues. As a first step towards enhancing the utilization of char, a simple thermal post treatment strategy was applied to improve its physiochemical and environmental performance. The two main factors that restrict the valorization of fast pyrolysis char are the surface area and the presence of PAH content. Characterization results from the post-treatment revealed the enhancement of the textural properties and a substantial reduction in PAH content for both feedstocks. The specific surface area increased from 6 to 375 m2g-1 and 1 to 447 m2g-1 for wheat straw and beechwood derived chars respectively. In parallel, the polycyclic aromatic hydrocarbon (PAH) content for both the samples were reduced from 13mg/kg to less than 1 mg/kg after the post treatment. In conclusion, this simple thermal post treatment is already a promising step to control biochar quality parameters. (Future work will focus on the physical activation).

ABSTRACT. Utilization of the droppings from the animals which are kept in the ZOO represents serious issue. Thermal treatment of the material such as pyrolysis can stabilize contained pollutants as well as kill microbes which can otherwise limit the utilization of the droppings. Traditional pyrolysis is highly energy-intensive, therefore another approaches (torrefaction, hydrothermal processes) are tested. Torrefaction represents process of formation of carbonaceous material at relatively low temperatures and often without use of inert gas as atmosphere. Resulting materials can be used for soil improvement, as adsorbents or source of energy [1, 2]. Droppings from camel (Camelus bactrianus), giraffe (Giraffa camelopardalis), deer (Elaphurus davidianus) and reindeer (Rangifer tarandus) were supplied by ZOO Brno (Czech Republic), they were dried at 80 °C to the constant mass in the laboratory dryer. Camel droppings were torrefied at 2 temperatures (250 and 300 °C) and at 2 times (1 hour and 2 hours) in the ceramic crucibles with caps without use of inert atmosphere. It was found out, that both temperature and time have statistically significant effect on the torrefaction yield for camel droppings but the effect of time is lower than the effect of temperature. Therefore, experiments with other types of droppings were carried out at torrefaction time 2 hours and for both temperatures. The type of animal has the significant effect on the torrefaction yield as well. The yield of torrefaction was between 50 and 75 % depending on animal and temperature. Both torrefaction temperature and type of animal influences bulk density of prepared materials as well as contents of organic functional groups in the resulting materials, which was proven by infrared spectrometry and elemental analysis.

[1] Z. Sun, J. Li, X. Wang, S. Xia, and J. Zhao, ‘Enhanced heavy metal stabilization and phosphorus retention during the hydrothermal carbonization of swine manure by in-situ formation of MgFe2O4’, Waste Management, vol. 174, pp. 96–105. DOI: 10.1016/j.wasman.2023.11.024. [2] N. Šantl, J. Stergar, M. Bozicko, D. Goričanec, D. Urbancl, and A. Petrovič, ‘The utilisation of thermally treated poultry farm waste for energy recovery and soil application’, Renewable Energy, vol. 221, no. C, 2024. DOI: 10.1016/j.renene.2023.119809.

ABSTRACT. This study investigates slow pyrolysis as a potential thermochemical valorization pathway for mixed greenhouse agricultural waste streams, consisting of tomato plant harvest residues contaminated with polypropylene (PP) supports for plant growth. Co-pyrolysis was applied to the waste stream as a pretreatment step prior to further plasma gasification of the produced biochar. The influence of reaction temperature and residence time on the char yield and properties were evaluated, with particular emphasis on the biochar suitability for syngas production during subsequent treatment in a plasma torch.

The experimental work was performed on mixed biomass composed of waste plant material from the Xandor XR tomato cultivar contaminated with PP clips and ropes, with plastic-to-biomass ratio of 0.35 on dry basis. The feedstock was collected after the harvest season, dried at 60 °C for 48 h and subsequently ground to 2 mm particle size. The ground material was pyrolyzed in a Carbolite Gero tube furnace at temperatures of 400, 500, 600 and 700 °C for residence times of 30 and 90 min, under a constant nitrogen flow of 20 mL/min and a heating rate of 10 °C/min. Elemental and proximate analyses were performed on both the feedstock and the produced biochars to determine composition and higher heating value (HHV). The metal and mineral contents were quantified by ICP-OES. The results showed average biochar yields ranging between 30.7 and 42.7 %, with carbon contents between 53.0 and 58.0 %. The calculated HHVs ranged between 18.6 and 21.4 MJ/kg.

Based on the outcomes of the current research activity, optimization criteria for downstream biochar conversion in plasma torches were determined according to char yield, energy yield and carbon enrichment. The combined application of pyrolysis and plasma gasification provides a promising alternative to conventional disposal practices for mixed agricultural residues, most of which are currently landfilled due to plastic contamination, and promotes more improved value recovery from this challenging biomass.

ABSTRACT. Catechol is an important platform chemical, with an annual production between 40 000 – 50 000 tonnes per year, due to its central role as key chemical intermediate for various applications in the pharmaceutical and agrochemical sector. The current production of catechol virtually entirely depends on fossil-based carbon: benzene is first converted into phenol, and is then hydroxylated. This yields not only catechol, but also hydroquinone in a ratio of 3:2 catechol:hydroquinone. Hence, it is most worthwhile to develop new production routes for catechol, which tackle both the dependency on fossil feedstock and the selectivity of the conversion.

This conference contribution therefore addresses both hurdles by demonstrating and optimizing the conversion of 2-acetylfuran into catechol. 2-Acetylfuran is a furan that can be obtained from renewable resources. In early work, Vargha et al. (1943) observed the conversion of 2-acetylfuran into catechol (Fig. 1). Some years later, Luijkx et al. (1993) revisited this conversion, aiming the optimization of catechol production, using a continuous subcritical reactor, operated at 340°C and 27.5 MPa for 16 min, using no or 5 mM HCl as catalyst. However, they observed at best a catechol yield of 4.6 mol% (at 13.2% conversion), which caused this route to remain dormant – until now.

Acknowledging the demand for green and innovative catechol synthesis, we optimized the hydrothermal conversion scheme. In this work, we increased the residence times to between 40 – 150 minutes, and operated at temperatures between 300 °C – 380 °C. Also, we used ZnCl2 as catalyst. After optimization, the best results were obtained at 360 °C, after 120 min reaction time, resulting in a catechol yield of 46.1 mol% at 88.5% selectivity (Fig. 2). This is an increase of one order of magnitude, compared to earlier results of Luijkx et al. Hence, this conference contribution demonstrates the viability of using hydrothermal conversion technology to provide green catechol.

ABSTRACT. As a key bio-based platform chemical, levoglucosenone (LGO) holds great promise for sustainable chemical synthesis. This study demonstrates the enhanced production of LGO from cellulose via solvothermal catalysis over sulfonated carbon, empowered by tailored pretreatments. Air plasma modification of the catalyst introduced nitrogen doping and additional oxygen-containing groups (-COOH, -OH), which facilitated cellulose adsorption and strengthened glycosidic bond cleavage. This boosted the LGO yield to 22.5 wt%, a significant increase from the 16.4 wt% obtained with the untreated system. Alternatively, ball milling pretreatment of cellulose dramatically reduced its crystallinity and particle size, achieving an even higher LGO yield to 24.7 wt% (31.8% mole yield), which increased by 50% compared to untreated system. Interestingly, applying both pretreatments simultaneously did not yield a synergistic effect, indicating that the observed enhancements are predominantly governed by single-mode modifications. Furthermore, the sulfonated carbon catalyst exhibited excellent stability, retaining high activity over five consecutive recycling cycles. This work provides efficient pretreatment strategies and insight into their distinct roles, highlighting a practical pathway for valorizing cellulose into high-value chemicals.

ABSTRACT. Ash generated from biomass power plants in Korea is treated as power plant waste and mostly landfilled, resulting in significant environmental and economic losses. This biomass ash possesses high carbon content and can be recycled into bio-coke by reducing ash and volatile matter content. Therefore, this study aimed to remove ash and volatile matter from biomass bottom ash through acid washing and carbonization processes, ultimately increasing its fixed carbon content. In addition to acetic acid, commonly used for biomass acid washing, lactic acid and citric acid which biodegrade in natural environments were used to mitigate environmental and safety concerns associated with strong acids, such as facility corrosion and waste liquid discharge. Particle size analysis of the raw material determined the optimal particle size range to be 850 μm – 2 mm based on ash content per size fraction. Acid washing was performed at 40–80 °C with the acid solution pH set to 1–3. Subsequently, the washed samples were carbonized in a horizontal reactor under a nitrogen atmosphere to remove residual volatile matter. The washing and carbonization processes confirmed that the ash reduction rate increased with rising washing temperature and decreasing solution pH. It was also confirmed that volatile matter could be effectively removed by increasing the carbonization temperature and time. These research results will serve as foundational data for future recycling of biomass bottom ash into bio-coke.

ABSTRACT. The transition toward a carbon-neutral energy system requires innovative strategies that integrate renewable energy use with carbon capture and recycling. CO₂ methanation, a key Power-to-Gas (PtG) technology, enables the conversion of captured CO₂ and renewable hydrogen into synthetic methane, a storable and grid-compatible fuel. Realizing its full potential depends on the development of robust catalysts. Nickel-based catalysts are widely employed due to their high activity and low cost; however, their performance is strongly influenced by the physicochemical properties of the support, which affect metal-support interactions, reducibility, dispersion, and resistance to sintering. Biochar and activated carbon are of particular interest as catalyst supports because of their tunable surface chemistry and porosity, but the relationship between biochar surface properties, metal-support interactions, and methanation performance remains insufficiently understood. This research systematically investigates a series of Ni catalysts supported on biochar and activated carbon, prepared from different feedstocks and pyrolysis conditions. Three lignocellulosic feedstocks—pine wood, wheat straw, and lignin-rich digested stillage—were pyrolyzed at 400°C, 550°C, and 700°C and subsequently activated with CO₂ to obtain a range of contrasting materials. The resulting biochars and activated carbons were thoroughly characterized using CHNS analysis, proximate analysis, N₂- and CO₂-physisorption, ICP-MS, FTIR, TPD-MS, XPS, and Raman spectroscopy to assess their surface chemistry, porosity, and structural properties. For catalytic testing, Ni was deposited onto the biochars and activated carbons, and CO₂ methanation was performed at 300°C and 10 bar. Conversion, selectivity, and stability data were then correlated with the physicochemical properties of the supports to establish structure–performance relationships. This work provides a systematic comparison of nine distinct biochar matrices and their activated carbon counterparts, exploring how feedstock composition and pyrolysis temperature influence metal-support interactions and catalytic behavior. By combining comprehensive surface characterization with catalytic testing, the study aims to clarify how biochar surface chemistry affects Ni dispersion and methanation performance. The insights gained from this research contribute to the rational design of biobased catalyst supports for synthetic methane production. They also strengthen the role of biochar valorization within the carbon circular economy and provide guidance for optimizing carbon-based supports for scalable CO₂ utilization and renewable energy storage via Power-to-Gas technologies.

ABSTRACT. There is a growing demand for biocarbon in metallurgical applications. The production of biocarbon via pyrolysis of biomass feedstock generates significant amounts of liquids and gases as byproducts. The liquid condensate, however, can be a valuable material with detailed characterization and proper upgrading. Biocarbon for metallurgical applications is currently produced primarily from stem wood, but it is important to exploit different biomass materials for feedstock of sufficient quality, high availability and low costs deriving from a sustainable source. Wood bark is a considerable waste stream from forestry and can be a potent feedstock for biocarbon production. In the present work, pine bark chips were pyrolyzed in a fixed bed reactor to produce pyrolysis condensate besides biocarbon. Prior to carbonization, some of the pine bark feedstock was leached by water to reduce the inorganic contents, which are higher in bark than in stem wood. The effect of water leaching on the condensate composition produced was evaluated by the GC/MS analysis. Direct utilization of raw pyrolysis condensates is challenging, as one of their issues is that they contain large amounts of water. Therefore, subsequent thermal treatments were also performed on the collected pyrolysis condensates of both leached and unleached pine bark. The thermal treatment of the condensates was performed in a muffle furnace at 140 and 160 °C for 2 h. The composition of volatile organic compounds in the thermally treated condensates was also determined by GC/MS analysis. The condensates heated at 140 °C showed a significant improvement in the ratio of organic contents as the intensity of the compounds identified was measured with a much higher intensity than it was found on the chromatograms of raw condensates. A similar tendency was observed in the cases of the condensates treated at 160 °C. The presence of larger compounds (e.g., levoglucosan) increased to a higher extent than in the samples treated at 140 °C. However, the fraction of the compounds of higher volatility was measured in a considerably lower ratio (e.g., acetic acid). The evaluation of leaching effects on the condensate of pine bark and the thermal treatment of the liquid byproducts was performed to provide useful data for the biocarbon industry to widen feedstock selection and for the utilization of the pyrolysis condensates.

ABSTRACT. Against the backdrop of accelerating global energy transition and stringent aviation-sector decarbonization targets, renewable feedstocks that combine high energy density with low lifecycle greenhouse-gas emissions are urgently sought. Owing to its rapid biomass turnover, intrinsically elevated lipid content, and non-competition with arable land, Spirulina represents a promising candidate for hydrothermal liquefaction (HTL)-derived bio-oil. However, the comparatively high nitrogen and oxygen loadings of the resulting biocrude constrain downstream upgrading efficiency and compromise fuel specifications. Herein, a dilute-acid pretreatment (5 wt% HCl) for nitrogen removal prior to catalytic HTL is proposed in this study. The synergistic effects of catalysts, temperature (300–450 ℃) and pressure (10–20 MPa) on biocrude yield, elemental distribution and molecular composition were systematically elucidated. Comprehensive physicochemical characterization and structural analysis were performed to benchmark the biocrude against aviation-fuel precursors. By optimizing reaction coordinates, the process simultaneously maximizes biocrude yield while minimizing nitrogen content, thereby providing critical process insights for low-nitrogen microalgal biocrude production and establishing a scientific foundation for subsequent hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) toward specification-compliant sustainable aviation fuel.

ABSTRACT. This research aims to investigate the production of wood vinegar from canola stalk, a common agricultural residue in the Thrace region of Turkiye, via slow pyrolysis, and to assess its antifungal properties. Laboratory scale fixed bed pyrolysis system was designed and used to pyrolyze canola stalks at eight different temperatures ranging from 280°C to 600°C. The chemical composition of the wood vinegar, separated from the pyrolysis liquid, was characterized using Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform Infrared (FT-IR) spectroscopy. The antifungal efficacy of the wood vinegar was tested in vitro against the economically significant phytopathogenic fungus Alternaria alternata at three different dilution ratios (1/100, 1/300, and 1/500). The experimental results showed that the pyrolysis temperature significantly influenced both product yield and the distribution of constituents within the vinegar. While the maximum wood vinegar yield (31.51%) was obtained at 350°C, chemical analyses revealed that the vinegar possessed a complex composition, primarily consisting of phenols, acetic acid, and ketones. Notably, the relative quantity of phenolic compounds was observed to increase with rising pyrolysis temperatures up to 500°C. Antifungal assays indicated that the wood vinegar significantly inhibited the mycelial growth of A. alternata in a clear dose-dependent manner. The most pronounced inhibitory effect was consistently achieved with the 1/100 dilution across all production temperatures. Furthermore, wood vinegar produced at mid-range temperatures, particularly between 400°C and 500°C, exhibited the strongest antifungal activity. This enhanced efficacy correlated well with the higher concentrations of phenolic compounds identified in the chemical profiles of these samples. In conclusion, slow pyrolysis has proven to be an effective method for transforming canola stalk waste into wood vinegar with considerable antifungal potential.

*This abstract was derived from Tamer Akçay's PhD Thesis.

ABSTRACT. Agro-industrial pruning residues represent an underexploited biomass resource that can play a key role in circular economy strategies at farm and cooperative scale. This study investigates the valorisation of agricultural residues generated by a fruit-processing cooperative located in Vitulazio (Italy), using real production and management data to assess the feasibility of biochar production via pyrolysis for internal agricultural use and carbon credit generation. The analysis focuses on three representative pruning residues, kiwi branches (KB), peach branches (PB) and apple branches (AB), selected based on their annual availability, physicochemical properties and temporal distribution. Production data indicate significant and stable biomass streams, associated with cultivated areas of tens to hundreds of hectares, with pruning availability spanning different seasons of the year. Proximate and ultimate analyses show comparable elemental compositions with a carbon content around 48-49 wt% dry basis (db) and relatively low ash contents (1.9-2.7 wt% db), making these residues suitable feedstocks for thermochemical conversion. Pyrolysis experiments were conducted in the temperature range 500–700 °C to quantify biochar yields and co-product formation. Biochar yields were found to range approximately between 23 and 29 wt% db, depending on feedstock and operating temperature, while significant fractions of liquid and gaseous by-products were also produced. The energy content of gases (8-12 MJ/kg) and liquids (18-20 MJ/kg) highlights the potential for internal energy recovery, contributing to the overall efficiency of the value chain. Biochar characterisation focused on parameters relevant for agronomic application and long-term carbon sequestration, including elemental composition, ash content, pH and indicators linked to stability. The results support the suitability of the produced biochars as soil improvers and as carbon sink. A comprehensive technoeconomic value chain analysis is presented to assess the economic viability of various feedstock and conversion pathways (pelletization or pyrolysis), covering residue generation, collection, pre-treatment, pyrolysis conversion, and potential carbon credit acquisition. The study demonstrates how an integrated, locally based pyrolysis system can enable the internal valorisation of pruning residues, closing nutrient and carbon loops while providing environmental and economic benefits to agro-industrial cooperatives.

ABSTRACT. This study investigated potential of biochar derived from coconut husk (CH), an abundant agricultural waste in tropical regions, in terms of biochar yield, CO2 adsorption performance, and adsorption kinetics. The effects of pyrolysis temperature were examined at 500 °C and 600 °C, selected based on thermogravimetric analysis (TGA) results. Pyrolysis was conducted under a nitrogen atmosphere with a heating rate of 5 °C min-1, a residence time of 1 h, and a nitrogen flow rate of 100 mL min-1. Characterization techniques, including ultimate analysis, Brunauer-Emmett-Teller (BET) surface area analysis, TGA, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), were employed to evaluate the composition and structural changes of the biochar. The CO2 adsorption performance was determined using a quartz-tube fixed-bed reactor packed with 1 g of adsorbent. Adsorption experiments were conducted at an initial CO2 concentration of 500 ppm, a temperature of 25 °C, and a pressure of 1 bar. The CO2 adsorption kinetics were analyzed using the Avrami kinetic model, while adsorption equilibrium behavior was evaluated using the Toth isotherm model. The results demonstrate that pyrolysis temperature significantly influenced the physicochemical properties of coconut husk biochar. Ultimate analysis revealed an increase in carbon content from 38.50% in raw coconut husk (Raw CH) to 54.53% at 500 °C (CH-500), followed by a slight decrease to 50.15% at 600 °C (CH-600). In contrast, oxygen content decreased progressively with increasing temperature, indicating enhanced deoxygenation during pyrolysis. Biochar yield decreased from 53.55% at 500 °C to 44.84% at 600 °C due to intensified devolatilization and thermal degradation at higher temperatures. XRD analysis illustrates the structural evolution of the material from its raw state (Raw-CH) through pyrolysis. The diffraction pattern of Raw-CH confirmed its amorphous nature, characterized by a broad diffraction halo centered at 2θ ≈ 22°, attributed to lignocellulosic components, along with a minor native crystalline silica (SiO2) phase. Upon pyrolysis, the amorphous halo diminished and sharp diffraction peaks corresponding to potassium chloride (KCl) emerged, indicating thermal decomposition of the organic matrix and crystallization of inorganic salts. FTIR analysis was employed to investigate changes in surface functional groups of coconut husk biomass before and after pyrolysis. Increasing pyrolysis temperature led to modification of oxygen-containing functional groups and promoted the development of aromatic carbon structures. Hydroxyl, phenolic, ether, and aromatic functional groups were identified on the biochar surface, providing active sites for CO₂ adsorption through hydrogen bonding and π–π interactions. The optimal pyrolysis condition was observed at 600 °C, providing a balance between biochar yield and pore structure development. The maximum CO2 adsorption capacity reached 0.079 mmol g-1. Kinetic analysis showed that the Avrami model adequately described the breakthrough behavior (R² = 0.74-0.94), indicating that both surface interactions and diffusion processes govern adsorption. Isotherm analysis using the Toth model (R2 = 0.96–0.99) confirmed favorable adsorption behavior. This study demonstrates that coconut husk biochar produced via optimized slow pyrolysis represents a promising, low-cost, and environmentally sustainable adsorbent for CO2 capture, contributing to biomass valorization and climate change mitigation.

ABSTRACT. Lignin is one of the most abundant aromatic polymers on earth and shows promising potential for the development of bio-based phenolic products through pyrolysis. In this study, a central composite design and response surface methodology were employed to evaluate the effect of pyrolysis temperature and heating rate on the phenolic yield in bio-oils obtained from pyrolysis of Kraft lignin. Pyrolysis experiments were carried out in a fixed-bed reactor at temperatures of 400-600 °C and heating rates of 5–25 °C.min⁻¹. The bio-oils were mostly composed of phenolic compounds (selectivity > 70%), mainly guaiacol, 4-methyl guaiacol and 4-ethylguaiacol, and exhibited remarkable antioxidant activity. The optimization model indicated that maximal phenolic yield from Kraft lignin pyrolysis is reached at 542 °C and 12 °C.min-1. An innovative phenolics-rich bio-additive was subsequently obtained by distilling the optimized bio-oil in order to remove water and light compounds. The antioxidant effectiveness of bio-additive was evaluated in an asphalt binder subjected to oxidative aging. The results showed that the incorporation of the bio-additive improved the binder's resistance to oxidative aging, reducing the carbonyl index by 25%. The aging mitigation effect was attributed to high phenolic content of bio-additive, particularly guaiacyl type phenols. This work highlights the potential of bio-oils derived from Kraft lignin as functional bio-based additives for the formulation of sustainable pavement materials and proposes a novel pathway for the valorization of technical lignin.

ABSTRACT. Understanding the effect of operating conditions during biomass pyrolysis is very important. The role of heating rate and final temperature has been extensively studied in the literature and is well understood. However, few studies have specifically addressed the impact of pressure on biomass pyrolysis and conflicting results have been reported. Most findings suggest that increasing pressure favors the formation of char and enhances exothermic phenomena [1], while others indicate that it primarily affects product quality rather than the overall yields [2]. Therefore, this work investigates the effect of pressure (ranging from 1 to 30 bar) and sweep gas velocity (ranging from 1 to 14 cm/s) on the yields and composition of products resulting from the slow pyrolysis of cellulose as a macromolecular model, as well as real lignocellulosic biomass particles including oak and miscanthus, in a fixed-bed reactor. Since the velocity of the carrier gas plays a crucial role in controlling mass transfer within the fixed bed, the experimental setup was designed to provide precise control over both gas flow rate and pressure, while also accounting for bed properties. The composition of the products has been characterized using micro gas chromatography for permanent gases, gas chromatography-mass spectrometry (GC-MS) for bio-oils, and proximate and ultimate analysis alongside scanning electron microscopy (SEM) for biochars. Additionally, the effect of pressure on vapor-char secondary conversion of primary volatiles has been investigated using a double-bed configuration (with a second bed of char).

References [1] Mok, W. S.-L. & Antal, M. J., Thermochim. Acta 68, (1983),165–186. [2] F. Melligan et al., Bioresour. Technol. 102, (2011), 3466–3470.

ABSTRACT. The slaughterhouse industry generates large amounts of solid waste and wastewaters, posing both environmental challenges and opportunities for energy recovery [1, 2]. Coupling biochemical and thermochemical processes, such as anaerobic digestion (AD) and digestate gasification, seems to be a promising alternative to convert slaughterhouse waste (SHW) and solid digestate into energy carriers including biogas, char, and syngas. This work investigates the potential of using SHW digestate to produce energy as an alternative to fossil fuels. Two feedstocks were examined: raw, and previously pyrolyzed SHW digestate. They were first characterized by proximate and ultimate analysis. Calorific values were also determined. The SHW digestate exhibited a high carbon content (46 wt%), H/C (1.6) and O/C (0.4) molar ratios, and a higher heating value (HHV) of 18.7 MJ/kg, making it well suited for gasification. Isothermal gasification tests (800 °C) were performed in a thermogravimetric analyzer (TGA) using an O2/N2 mixture as a gasifying agent. The gas composition was simultaneously analyzed by micro-gas chromatography (MicroGC) [3]. The effect of key process parameters such as feedstock loading, gas flow and heating rates was carefully examined to maximise gasification efficiency and improve syngas quality, allowing to reach hydrogen-rich syngas composition (~48 mol%) with H₂/CO molar ratios between 1.4 and 2.4, and lower heating values (LHV) of producer gas up to 7.8 MJ/m3, for ideal energy recovery. These results highlight the potential of coupling AD and digestate gasification (AD-gasification) as an alternative route for upgrading digestates into hydrogen-rich syngas, supporting their integration into advanced biomass valorization and waste-to-energy systems.

[1] Ashilenje, D.; Ashour, F.; Barz, M.; Belandria, V.; Borello, A.; Bostyn, S.; Boushaki, T.; Branciari, R.; Bwapwa, J.K.; Cerza, E.; et al. Resour. Conserv. Recycl. 2026, 224, 108571. [2] Habchi, S.; Pecha, J.; Sanek, L.; Karouach, F.; Bari, H.E. J. Environ. Manag. 2024, 366, 121920. [3] Sangaré, D.; Belandria, V.; Bostyn, S.; Moscosa-Santillan, M.; Gökalp. I. Biomass Conv. Bioref., 2024, 14, pp. 9763–9775.

ABSTRACT. Energy transition demands integrated thermochemical platforms delivering low-carbon carriers and managing carbon. Hydrogen underpins decarbonization but faces safety, infrastructure, and water limits. Biofuels complement hard-to-electrify transport. Carbon capture and storage is increasingly vital for achieving climate-neutral energy systems across aviation, shipping, and heavy-duty sectors globally today. In this framework, an integrated biomass–metal redox approach in which products of biomass pyrolysis act as reducing agents for metal oxides, enabling the co-production of hydrogen, biofuels, and functional materials. As highlighted by the Ellingham diagram, the best metal that allows this type of energy transition, for its kinetic and thermodynamic characteristics, and for its availability in the world is iron. Pyrolysis converts biomass and residual organic materials into biochar and a spectrum of volatile compounds whose composition and reactivity can be tailored through operating conditions. These carbonaceous products drive the reduction of iron oxides through coupled solid–solid reactions, generating metallic iron as a stable and transportable solid. Subsequent oxidation of the reduced iron with steam releases high-purity hydrogen on demand, eliminating the need for molecular hydrogen production, compression, storage, or long-distance transport. Beyond hydrogen generation, metallic iron also shows potential as a novel combustible in advanced metal burners, Scheme 1. The paper presents experimental results obtained by combining the pyrolysis of different biomass feedstocks and solid carbonaceous materials with iron-based solids under controlled conditions, using thermogravimetric apparatus and lab-scale reactors. The kinetics of the redox reactions are analyzed, with particular attention also devoted to the physicochemical properties of the solid and gaseous products formed during the pyrolysis/redox reactions. Solid products are characterized in terms of phase composition, microstructure, porosity, and surface chemistry, highlighting the impact of biomass type and pyrolysis conditions on iron reduction efficiency and material evolution. The microstructure, porosity, and surface chemistry of iron-based solids indicate promising perspectives for the production of multifunctional materials, linking energy conversion and CCS within a circular framework.

ABSTRACT. The present study explores the catalytic co-pyrolysis of rain tree pods (SS) and natural black rubber (NBR) in a semi-batch reactor for sustainable bio-oil production. Experiments were conducted over a temperature range of 450-650 °C, with NBR blending ratios of 10-40 wt.% and catalyst loadings of 5-15 wt.% using Al₂O₃ and ZnO. Physicochemical characterisation confirmed the suitability of SS and NBR as promising feedstocks for biofuel generation. Thermogravimetric analysis revealed that SS exhibited a maximum mass loss of 61.21% between 150 and 600 °C, while NBR showed elastomeric chain degradation of 43.33% between 170 and 470 °C. FTIR analysis further identified key functional groups, including C=C, C–H, –OH, and C=O, associated with both the biomass and polymer components. Thermal pyrolysis of SS resulted in a maximum bio-oil yield of 30.45% at 600 °C, which increased by 3.19% upon blending with 40 wt.% NBR. The produced pyrolysis oil demonstrated enhanced fuel quality, with increased carbon and hydrogen contents of 82.05% and 12.27%, respectively, alongside a 29.56% reduction in oxygen content. Moreover, the incorporation of 10 wt.% Al₂O₃ and ZnO improved the carbon content and higher heating value (HHV) of the pyrolysis oil, while significantly reducing its moisture content compared to thermally produced oil. The addition of NBR at varying ratios marginally increased char yield, whereas catalytic co-pyrolysis led to an approximate 8% increase in char production. The resulting catalytic char exhibited an alkaline pH and elevated ash content, suggesting its potential for soil amendment and fertility enhancement. The findings highlight the effectiveness of catalytic co-pyrolysis in converting waste biomass and rubber into value-added products, supporting sustainable resource utilisation and circular economy principles

ABSTRACT. This study examines the stabilizing performance of lignin, extracted from Eucalyptus globulus, on nitrated cellulose carbamate (NCC), compared with conventional stabilizers 2-nitrodiphenylamine (2-NDPA) and 1,3-dimethyl-1,3-diphenylurea (C-II). FTIR spectroscopy confirms that lignin efficiently scavenges nitroxyl radicals generated during thermolysis of nitrocarbamate and nitrate ester bonds, thereby suppressing autocalytic decomposition. Thermal analyses (DSC and TGA) reveal a systematic increase in the main decomposition peak temperature following NCC < NCC/C II < NCC/lignin < NCC/2-NDPA, indicating progressively enhanced thermal stability. TGA-FTIR further demonstrates that stabilizer identity modulates the intensity of gaseous products without altering their composition. NH2 intermediates formed during NCC degradation facilitate nitrogen conversion and reduce toxic NO emissions. Collectively, these findings establish lignin as an effective bio-derived stabilizer, providing a sustainable alternative to conventional stabilizers while improving both thermal performance and safety of energetic cellulose derivatives.

ABSTRACT. The reactive molecular dynamics using ReaxFF force field (ReaxFF MD) is becoming an effective means in unraveling the detailed reactions at molecular level for pyrolysis of realistic fuel mixtures [1]. However, understanding the pyrolysis chemistry of radical-driven process remains challenging due to the large number of intermediates and reactions involved. To discover the major pathways and kinetics contained in simulations, a new method of SRG-Reax (Skeleton Reaction network Generation for ReaxFF MD) was developed. SRG-Reax can predict reaction classes automatically in pyrolysis and oxidation mainly by machine learning on basis of reaction centers [2-3].

With SRG-Reax, the major species distribution in PP pyrolysis detectable experimentally become explainable by the predicted major reaction classes [4], which demonstrates the application potential of SRG-Reax in understanding the complex chemistry of polymer pyrolysis. The comparison of reaction class distributions predicted by SRG-Reax allows for explaining pyrolysis chemistry differences among similar fuel surrogates. The reaction class distributions for RP-3 surrogates in Fig. 1 shows a visual confirmation that the optimized 3-component model by machine learning and ReaxFF MD simulations [5] is more proper a surrogate to real fuel representative of the 45-component model of RP-3 fuel. Extension of SRG-Reax in predictions of oxidation reaction class [3] enhanses evaluation capability of diesel fuel surrogates with varied component structures and composition.

In a word, in addition to as an potential alternative approach in generating the skeleton reaction network of pyrolysis directly from ReaxFF MD simulations for kinetic modeling, SRG-Reax can be an feasible approach in evaluation the global pyrolysis chemistry differences of fuel surrogates that helps in refining fuel surrogate or development of new fuels.

References [1] Xiaoxia Li, Mo Zheng, Chunxing Ren, and Li Guo. ReaxFF Molecular Dynamics Simulations of Thermal Reactivity of Various Fuels in Pyrolysis and Combustion, Energy & Fuels 2021, 35, 15, 11707–11739 [2] Shanwen Yang, Xiaoxia Li et al., Generating a skeleton reaction network for reactions of large-scale ReaxFF MD pyrolysis simulations based on a machine learning predicted reaction class Phys. Chem. Chem. Phys., 2024, 26, 5649–5668 [3] Jinlin Zhou, Mo Zheng, Chunxing Ren, Xiaoxia Li. Reactivity evaluation of diesel surrogate models with combined approach of ReaxFF MD simulation and reaction classification, Fuel 2026, 407, Part C, 137469 [4] Wenyao Li, Mo Zheng, Jiangang Li, Chunxing Ren, Xiaoxia Li. Revealing global reaction mechanisms of polypropylene pyrolysis by reactive molecular dynamic simulation and reaction class predictio, Polymer Degradation and Stability, 2025, 239, 111419 [5] Song Han, Xiaoxia Li et al., "Refining Fuel Composition of RP-3 Chemical Surrogate Models by Reactive Molecular Dynamics and Machine Learning." 2020, Energy & Fuels 34(9): 11381-11394

ABSTRACT. Lignin is the most structurally heterogeneous component of lignocellulosic biomass, and its thermal decomposition behavior is strongly influenced by the method and severity of extraction. Lignins obtained through different isolation routes such as kraft, organosolv, soda, and milled wood processes exhibit substantial variations in elemental composition, functional group content, and interunit linkages. These structural differences pose a major challenge for the development of transferable kinetic models capable of reliably predicting lignin devolatilization behavior and product distributions during pyrolysis. In the CRECK-S framework, lignin is represented by three pseudo-components (LIGC, LIGH, and LIGO), whose distribution is determined via elemental CHO balance (Faravelli et al., 2010). This work presents the development of an improved kinetic modeling framework for lignin pyrolysis that accounts for structural variability arising from different extraction methods. A comprehensive literature survey was conducted to compile reported elemental analysis data and structural descriptors for a wide range of lignins, enabling the identification of systematic trends linking extraction severity to changes in lignin composition and thermal behavior. In particular, the analysis indicates that lignin extraction severity systematically alters elemental O/C ratios, which effectively differentiates the relative contributions of the carbon-rich, hydrogen-rich, and oxygen-rich pseudo-components used in the CRECK-S representation. Less severely treated lignins, such as milled wood and mild alkali lignins, retain a higher proportion of ether linkages (Zhao et al., 2019) and oxygenated functional groups, resulting in higher O/C ratios and earlier devolatilization. In contrast, lignins obtained through more severe extraction routes exhibit increased carbon content, enhanced structural condensation, and reduced oxygen functionality, leading to lower O/C ratios and higher thermal stability. These severity-dependent elemental trends can therefore be used as proxies for structural variability in the proposed kinetic model updates. Figure 1 compares the thermal stability of different lignins extracted using milled wood and organosolv processes, with milled wood lignins having higher O/C ratios of 0.613, 0.537 and 0.574 for red ork, pine and corn stover compared to 0.393, 0.38 and 0.399 for organosolv lignins, respectively and a higher intensity of the low temperature DTG peak. The proposed framework aims to improve predictions of mass loss kinetics, volatile release rates, and detailed product distributions across different lignin types and biomass sources. Adjustment of global kinetic parameters and key reaction pathways according to elemental composition and structural characteristics in the proposed model will provide a more flexible and physically consistent representation of lignin pyrolysis. Preliminary simulations using the existing CRECK-S-B lignin model indicate lack of agreement with reported devolatilization trends and less consistency in the prediction of phenolic and aromatic product classes across lignins derived from varying extraction routes. The proposed approach represents a step toward more robust and transferable lumped kinetic models for lignin pyrolysis, bridging the gap between experimentally observed structural heterogeneity and predictive thermochemical modeling.

Figure 1: Comparison of thermal degradation characteristics of lignins extracted using milled wood process and organosolv process for different biomass types

References Faravelli, T., et al. (2010). https://doi.org/10.1016/j.biombioe.2009.10.018 Zhao, C., et al. (2019). https://doi.org/10.1021/acs.iecr.9b00499

ABSTRACT. Capability for large-scale reactive molecular simulation would be beneficial for understanding the complex pyrolysis reactions of cellulose and other carbohydrates. Quantum mechanical methods are a tool of choice for accurately studying reactions, but their high computational cost limits their applicability. Reactive force fields, on the other hand, are a tool for studying reactions in large systems, involving sequential reactions and gradual structural changes. The ReaxFF reactive force field [1] has been one of the few tools applicable to pyrolysis and carbonization simulations of cellulose, and polymers in general.

In our ongoing study on the chemical and structural pathways of cellulose carbonization, we utilize the ReaxFF force field for atomistic simulations and have observed several possible challenges in its ability to describe the reactions and structural changes. Our first modelling studies using (unbiased) molecular dynamics (MD) simulations [2, 3] showed predictions that were compatible with mechanisms proposed for cellulose fast pyrolysis, but the absence of reactions forming anhydrosugars, and particularly levoglucosan (LGA), were seemingly inconsistent with experimental results. To confirm that this is not a shortcoming of the force field or its parameter set, we are performing systematic force field evaluation for cellulose pyrolysis studies. Our work follows an earlier evaluation study related to cellulose condensed phase properties [4].

To assess the performance of ReaxFF, we generated a systematic set of glucose conformers and evaluated their optimized relative energies against density functional theory (DFT) calculations and the (non-reactive) CHARMM carbohydrate force field [5]. The analysis focused on the 4C1 and 1C4 ring forms due to the expected role of transitions between the two in the LGA forming reaction [6]. We observed that ReaxFF, using currently available parameter sets, was not able to sufficiently replicate the set of stable conformers found with both DFT and CHARMM optimizations. More accurate description of the early-stage pyrolysis reactions of cellulose, and carbohydrates in general, would thus benefit from dedicated force field training. Our resulting glucose conformer data can be utilized as a starting point for such training ReaxFF carbohydrate simulations.

For more thorough evaluation, we also compare ReaxFF, DFT and CHARMM predictions for the potential energy surface of glycosidic linkage rotations in cellobiose, and the stability and structure of crystalline forms of cellulose, including microfibrils – the natural form of plant cellulose. The purpose of these analyses is to assess how well ReaxFF describes the dynamics of individual cellulose chains, and their relevant condensed phase structures, at elevated temperatures.

The comparability between high-temperature simulations and pyrolysis in natural and industrial processes remains a central question for future studies. Systematic force field evaluation should, in our opinion, begin from the pyrolysis chemistry of simple sugars, especially that of glucose.

[1] van Duin, J. Phys. Chem. A 105 (2001) 9396–9409

[2] Paajanen et al. Cellulose, 24(7) (2017) 2713–2725

[3] Paajanen et al. Cellulose 28(14) (2021) 8987–9005

[4] Dri et al. (2015) Comput. Mater. Sci. 109:330–340

[5] Guvench, J. Chem. Theor. Comput. 5(9) (2009) 2353–2370

[6] Hosoya, ChemSusChem 6(12) (2013) 2356–2368

ABSTRACT. The natural structure of bamboo, characterized by hollow stems and densely interspersed nodes, contributes to its lightweight yet high-strength material properties through longitudinal fiber arrangement. Its rapid growth and widespread distribution further confer unique ecological, economic, and cultural values. As a vital biological resource, the distribution and utilization of bamboo reflect both technological craftsmanship and regional climatic conditions. A prevalent hypothesis in paleoclimatology posits that the North China Plain experienced a relatively warm and humid period during the 4th century BC—commonly referred to as the "Warring States Warm Period." Bamboo species exhibit notable sensitivity to climatic variations, including temperature and precipitation fluctuations, rendering them effective indicator species for climate change studies, providing direct archaeological evidence for climate variability of the North China Plain in that era. However, the severe degradation of excavated bamboo artifacts often eliminates their morphological features, thereby complicating their identification. To address this, the current study systematically employed pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to analyze organic residues from tombs dating to the Warring States period in Yiyuan, Shandong Province, aiming to determine material composition and infer paleoenvironmental conditions.

Py-GC/MS analysis conducted at a pyrolysis temperature of 500°C revealed that the thermal decomposition products predominantly consisted of phenolic compounds, identified as derivatives of guaiacyl (G-type) and syringyl (S-type) lignins, typical chemical signatures of Poaceae bamboo subfamily plants. Notably, a characteristic ion fragment at m/z 418 was stably detected in archaeological samples, corresponding to a compound identified as syringaresinol. Its presence aligns with modern bamboo material, indicating its specificity as a biomarker for bamboo. Integrating morphological characteristics, high lignin content, and biomarker detection, we preliminarily identified the sample as bamboo. Further plant anatomical analysis examined the microstructure using scanning electron microscopy (SEM). The observation of vascular bundle arrangements and fiber characteristics confirmed the residue as bamboo, which was consistent with the Py-GC/MS findings. Compared to traditional anatomical methods that rely on whole-structure preservation, Py-GC/MS requires only minute sample quantities, offers rapid analysis, and is particularly suited for highly degraded archaeological materials.

The characterization of bamboo presence in Yiyuan during the 4th century BCE holds significant environmental implications. Located at the eastern fringe of the North China Plain, Shandong’s modern climate no longer favors extensive natural bamboo growth. Archaeological bamboo artifacts from this period strongly imply a regional climate that was subtropical and humid enough to sustain bamboo forests and facilitate resource utilization. This microarchaeological chemical evidence substantiates the macro-level paleoclimate model of the Warring States Warm Period, directly linking specific archaeological sites to regional climate transitions. In summary, this study not only introduces innovative methodological approaches within archaeobotany but also provides direct evidence supporting key paleoclimatic variations. It exemplifies the critical role of pyrolysis-based analysis in addressing complex environmental questions within archaeological science.

ABSTRACT. The chemical analysis of ancient cosmetic products is challenging, as the original substances are rarely preserved, often leaving only trace residues sequestered within the pores of their containers. Iconographic and literary evidence is essential for associating these vessels with cosmetic and ritual practices and for obtaining information on the most widely attested perfumes and ingredients. However, such evidence does not always resolve the issue of their original contents, particularly given that the same containers may have been used for different products. Therefore, selective and sensitive analytical techniques are required to gain insight into their chemical composition and production processes. In this research, the contents of ancient Greek vessels known as lekythoi were investigated. These small balsamaria were recovered at Spina (Ferrara, Italy) from the Etruscan necropolis of Valle Trebba, inside a tomb belonging to a sub-adult individual, thus representing a closed funerary context. Samples were collected by scraping the inner bottom of the vessels and analyzed by gas chromatography–mass spectrometry (GC–MS) combined with analytical pyrolysis, the latter performed with and without TMAH. A wide array of pyrolytic markers characteristic of both animal- and plant-based materials was identified. Their origin could be associated with typical components of ancient cosmetic products, such as balms, ointments, and others [1,2]. Linear alkanes, long-chain fatty acids, and branched aryl hydrocarbons suggested the use of oils, fats, and/or waxes to create the perfume base, together associated with the presence of PAHs. The pyrolysates of several samples exhibited alkylated (benzo)thiophenes and sulfur dioxide suggesting the presence of sulfur-containing components. Other samples displayed nitrogen-containing compounds (pyrrole, indole, pyrocoll) indicative of proteinaceous materials, suggesting their involvement in the preparation of the final products. Although factors such as recipe complexity and ingredient variability complicate data interpretation, this study demonstrates that a targeted analytical approach can be successfully applied to obtain preliminary information on ancient cosmetics.

References [1] Bodiou, L., Frère, D., Mehl, V. (eds.). (2008). Parfums et odeurs dans l’Antiquité. Presses Universitaires de Rennes, Rennes. [2] Colombini, M.P., Giachi, G., Iozzo, M., Ribechini, E. (2009). J Archaeological Science 36(7):1488–1495.

ABSTRACT. The introduction of plastics in the 19th century marked the onset of a revolutionary era, characterised by the widespread use of semi-synthetic and synthetic polymers across all fields of human activity. Originally used in the production of everyday and technological objects, these materials soon expanded into art and design. Today, plastic artworks and design objects represent a significant component of modern and contemporary museum collections. However, the limited long-term stability of plastic materials poses major challenges, that are difficult to address also due to their heterogeneous and complex composition. The development of effective analytical and investigative methods, recognised as a priority in Heritage Science, is therefore even more critical for plastic artworks, given their vulnerability, heterogeneity, and material complexity. These factors hinder the standardization of reliable and repeatable conservation and restoration procedures. Within the interdisciplinary project PRIN2022 PERSPECTIVE—PolymEr Research Studies for PreventivE Conservation Through non-invasIVe analytical strategiEs (https://perspective.cnr.it), aimed at developing multimodal analytical approaches for the study, monitoring, and preservation of plastic heritage, several samples from 20th-century plastic objects in the Triennale Milano (Milan) collection were analysed, and the results are presented in this work. The adopted analytical protocol relies on thermoanalytical techniques, namely analytical pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS) and evolved gas analysis–mass spectrometry (EGA-MS), which have been reported in the literature as unsurpassed methods for the molecular-level characterization of heritage plastics and textiles with high chemical detail [1,2]. The results achieved from this diagnostic campaign enabled the identification of different materials representative of the 20th-century universe, including cellulose acetate [3], polyurethanes [4], and polycarbonates [1], added with various plasticizers ranging from phthalates to adipates. Most importantly, comparison of the thermoanalytical results from the Triennale samples with those obtained for artificially aged reference materials developed within the PERSPECTIVE project allowed us to assess the degradation state of the investigated artworks.

Acknowledgments The Centre for the Instrument Sharing of the University of Pisa (CISUP); Grazia De Cesare from the Academy of Fine Arts of L’Aquila (Italy), and Rafaela Trevisan from the Triennale Design Museum of Milan (Italy). Funding was provided by Italian Ministry for Research (MUR), PRIN2022 project “PERSPECTIVE - PolymEr Research Studies for PreventivE Conservation Through non invasIVe analytical strategiEs”, https://perspective.cnr.it coordinated by Francesca Rosi CNR-SCITEC Perugia.

References [1] J. La Nasa et al., 2020, Molecules, doi:10.3390/molecules25071705. [2] T Nacci et al.,2022,J. of Physics: Conference Series, https://doi.org/10.1088/1742-6596/2204/1/012012. [2] R. King et al., 2020, Heritage Science, https://doi.org/10.1186/s40494-020-00466-0. [3] J. La Nasa et al., 2018, J. Analytical and Applied Pyrolysis, https://doi.org/10.1016/j.jaap.2018.08.004.

ABSTRACT. Lacquerware, prized for its durability, adhesive properties, and decorative appeal, has played a vital role from ancient times to the modern era as both ceremonial objects and daily necessities. Therefore, elucidating the materials and production processes of lacquerware provides a crucial foundation for understanding the historical and cultural context of the period. During the Kamakura period (1185–1333), while high-end lacquerware like maki-e lacquerware—decorated by painting patterns with lacquer and sprinkling metallic powders like gold or silver on top—was produced, mass production of common tableware also advanced. Alongside this, stamped patterns emerged as a decorative technique enabling efficient production and uniform decorative quality. Stamped patterns are a lacquerware decoration technique where designs—such as plant motifs, animal motifs, or abstract patterns—are applied using carved stamps. This technique was widely used from the late 13th to the 14th century. However, due to the difficulty in expressing complex designs and the unknown materials used for the stamps, many aspects of its production techniques and material properties remain unclear [1]. This study aimed to elucidate the production techniques of stamped patterns by analyzing and comparing lacquered fragments from the Kamakura period, featuring stamped patterns, lacquer painting, and multicolored designs, excavated from an archaeological site in Kamakura City, Kanagawa Prefecture, using scientific methods. The analytical methods employed included cross-section observation under transmitted light and reflected polarized light for examining the layered structure, energy-dispersive X-ray fluorescence (ED-XRF) for elemental composition analysis, and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) for identifying organic materials. Cross-section observations revealed a four-layer structure in transmitted light. Under reflected polarized light, red interference colors were observed in the upper layer, suggesting the use of red pigments. Py-GC/MS analysis revealed a group of peak-shaped peaks with 3-heptylphenol as the peak at m/z 108 and a peak for 3-pentadecylphenol in the ion chromatogram extraction results, suggesting the use of Toxicodendron vernicifluum from Japan, China, or Korea. The detection of palmitic acid (C16) and stearic acid (C18) in the m/z 60 ion chromatogram extraction suggested the use of drying oils. Furthermore, differences in the intensity ratios of fatty acid peaks were observed in samples of stamped patterns, lacquer paintings, and multicolored patterns. In drying oil analysis using Py-GC/MS, the peak intensity and peak ratio of fatty acid-derived components serve as effective indicators for identifying drying oil types [2]. Based on this, the differences in fatty acid peaks observed in this study also suggest that the lacquer preparation methods and added materials may have differed for each decorative technique, providing important clues for elucidating the production techniques of stamped lacquerware.

References [1]Yotsuyanagi Kasho, Production and Distribution of Middle-age lacquerware, National Museum of Japanese History, (2019), 163 [2] Schilling, M. R., et al. Beyond the basics: A systematic approach for comprehensive analysis of organic materials in Asian lacquers. Studies in Conservation, (2016)61, 3-27

ABSTRACT. Beeswax was widely used in antiquity due to its versatile properties and nevertheless its chemical lability was reported in the literature [1], [2], [3], its long-term degradation remains under-researched. This study addresses this gap by investigating the photo-oxidative susceptibility of beeswax. An analytical approach, integrating double-shot Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS), and Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) was employed. Double-shot Py-GC/MS was used to sequentially analyse volatile fraction followed by the polymer matrix, with an online UV irradiator enabling real-time monitoring of degradation products. SPME-GC/MS tracked the evolution of volatile organic compounds under natural aging conditions. The results indicate that beeswax undergoes significant chemical degradation, yielding smaller, oxidized compounds upon exposure to UV and solar radiation [4]. [1] X. Y. Liu, M. C. Timar, and A. M. Varodi, “A comparative study on the artificial UV and natural ageing of beeswax and Chinese wax and influence of wax finishing on the ageing of Chinese Ash (Fraxinus mandshurica) wood surfaces,” J. Photochem. Photobiol. B, vol. 201, no. January, p. 111607, 2019, doi: 10.1016/j.jphotobiol.2019.111607. [2] M. C. Timar, A. M. Varodi, and X. Y. Liu, “the Influence of Artificial Ageing on Selected Properties of Wood Surfaces Finished With Traditional Materials – an Assessment for Conservation Purposes,” Bulletin of the Transilvania University of Brasov, Series II: Forestry, Wood Industry, Agricultural Food Engineering, vol. 13, no. 62–2, pp. 82–94, 2020, doi: 10.31926/BUT.FWIAFE.2020.13.62.2.7. [3] K. Čížová, K. Vizárová, A. Ház, A. Vykydalová, Z. Cibulková, and P. Šimon, “Study of the degradation of beeswax taken from a real artefact,” J. Cult. Herit., vol. 37, pp. 103–112, 2019, doi: 10.1016/j.culher.2018.04.020. [4] M. Mattonai, A. Watanabe, A. Shiono, and E. Ribechini, “Degradation of wood by UV light: A study by EGA-MS and Py-GC/MS with on line irradiation system,” J. Anal. Appl. Pyrolysis, vol. 139, no. February, pp. 224–232, 2019, doi: 10.1016/j.jaap.2019.02.009.

ABSTRACT. Hydrothermal conversion technology is a promising technique for resource utilization. In this study, the influence of reaction conditions on the distribution of hydrothermal conversion products was investigated, and the resource utilization methods of all components of hydrothermal conversion products were discussed. The results showed that the highest bio-oil yield was obtained at 310 ◦C, which was 36.75 %. The higher heating value and energy recovery rate of bio-oil can reach 39.68 MJ/kg and 78.55 % respectively. And it had great potential as an alternative fuel. When wheat seeds cultured by aqueous were diluted 100 times at 310 ◦C with GI ≥ 80 %, the phytotoxicity disappears. At this time, the contents of total nitrogen, total phosphorus, and total potassium were 1234.80, 150.34, and 1640.36 mg/L respectively, and the heavy metal content was lower than the national standard for foliar fertilizer. The optimal conditions for biochar to adsorb methylene blue were adsorbent dose 2 g/L, 180 rpm, temperature 70 ◦C, and time 120 min; The gas phase yield increased with the increase of temperature (0.15–7.45 %). The yield at 310 ◦C was 2.76 %. The main component of the gas phase was CO2, accounting for 93.71–97.92 %. The innovation of this study was that food waste can be converted into bio-oil through high-temperature hydrothermal reaction, achieving energy recovery. The aqueous phase product of hydrothermal conversion was used as water-soluble liquid fertilizer, achieving resource utilization. At the same time, the reaction was carried out under high temperature and pressure, which can completely kill pathogens in food waste and has extremely high biological safety.

ABSTRACT. Microplastics in air have recently gained attention as an emerging environmental contaminant with potential implications for human exposure and atmospheric transport. Reliable characterization of microplastics in air requires analytical methods that can be effectively applied to field-collected samples while accounting for particle size and site-specific environmental characteristics. Analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) offers a powerful approach for polymer-specific identification and quantification; however, its field applicability for size-segregated microplastics in air remains insufficiently evaluated.

In this study, the field applicability of analytical pyrolysis–GC/MS for microplastics in air was assessed using size-segregated particulate matter samples collected at representative sites in the Seoul metropolitan area. Sampling was conducted separately for PM10 and PM2.5 fractions to evaluate particle size–dependent characteristics of microplastics in air. Prior to instrumental analysis, a series of pyrolysis-oriented pretreatment experiments was performed to optimize sample handling and thermal degradation conditions for the analysis of microplastics in air, focusing on minimizing matrix interference while preserving polymer-specific pyrolysis signals.

Field samples were collected from two contrasting environments. A residential area in Gwacheon, characterized by low industrial activity and proximity to Mt. Gwanak, was selected to represent an urban background influenced by natural surroundings. In contrast, an industrial complex in Ansan was selected to represent an industrialized urban environment with potential contributions from manufacturing activities and traffic-related sources. These sites enabled comparative evaluation of microplastics in air under different regional and environmental conditions.

Py-GC/MS analysis targeted characteristic pyrolysis products and marker ions of major polymer types commonly reported in microplastics in air. The occurrence and composition of microplastics were evaluated according to sampling site and particle size fraction, allowing assessment of size-dependent distribution patterns and site-specific features. The results demonstrate distinct differences in polymer composition between PM10 and PM2.5 fractions as well as between residential and industrial environments, highlighting the importance of particle size–resolved sampling for microplastics in air assessment.

This study demonstrates that analytical pyrolysis–GC/MS, combined with optimized pretreatment and size-segregated sampling, is an effective and practical tool for field-based characterization of microplastics in air. The findings provide methodological insights for future monitoring studies and contribute to the development of standardized approaches for microplastics in air analysis.

ABSTRACT. Microplastics in air have recently emerged as an important environmental concern due to their potential impacts on human exposure and atmospheric processes. While analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) has been increasingly applied for polymer-specific identification of microplastics, its field applicability and its relationship with organic components of fine particulate matter remain insufficiently understood. In particular, the role of microplastics within the organic fraction of PM2.5 has not been systematically evaluated under real atmospheric conditions.

In this study, the field applicability of analytical pyrolysis–GC/MS was evaluated for the characterization of microplastics in air, with a specific focus on their compositional features and spectral characteristics within PM2.5. Size-segregated particulate matter samples (PM10 and PM2.5) were collected at representative metropolitan sites in the Seoul metropolitan area, including a residential area in Gwacheon influenced by natural surroundings and an industrial area in Ansan affected by industrial and traffic-related emissions. Prior to instrumental analysis, pyrolysis-oriented pretreatment experiments were conducted to optimize sample handling and thermal degradation conditions, aiming to minimize matrix interference while preserving polymer-specific pyrolysis signals.

To investigate the relationship between microplastics and organic aerosol components, PM2.5 samples collected in Ansan were analyzed in parallel using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), an OC/EC analyzer (OCEC), and Py-GC/MS-based microplastic analysis. Organic matter (OM) measured by HR-ToF-AMS exhibited pronounced short-term variability at high temporal resolution, reflecting the influence of local emissions and secondary organic aerosol formation. In contrast, organic carbon (OC) derived from filter-based OCEC analysis showed smoother temporal variations due to its integrated sampling characteristics.

Microplastic concentrations in PM2.5 ranged from approximately 9 to 38 ng/m3, corresponding to about 0.04–0.16% of the PM2.5 mass. Although the absolute mass contribution of microplastics was minor, periods with elevated microplastic concentrations generally coincided with higher average OM and OC levels. Scatterplot analyses further indicated that microplastic concentrations tended to increase under conditions of enhanced PM mass and organic dominance, suggesting that microplastics are not entirely independent of the organic fraction of PM2.5. However, short-term OM peaks were not always accompanied by increases in microplastic concentration, reflecting differences in formation mechanisms and temporal response characteristics between gaseous organic aerosols and solid polymer particles.

Characteristic pyrolysis products and marker ions enabled the derivation of polymer-specific spectral features of microplastics in air. The results suggest that microplastics can be conceptualized as a distinct but co-varying subcomponent within the organic fraction of PM2.5 rather than as an isolated particulate species. This study demonstrates that analytical pyrolysis–GC/MS is a practical and effective tool for field-based characterization of microplastics in air and provides insights into their compositional role within fine particulate matter. The findings contribute to the development of standardized analytical frameworks and improved understanding of microplastics in atmospheric environments.

ABSTRACT. Due to its high sensitivity and selectivity, Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) is a powerful tool for quantifying micro- and nanoplastics (MNPs) in environmental and biological samples at sub-microgram levels. Polymers can be diluted using inert solids or by dissolving them in a solvent. The latter is often unfeasible because many polymers, especially polyolefins such as polyethylene (PE), are poorly soluble in common organic solvents. For this purpose, microwave-assisted extraction (MAE) has been explored by Hermabessiere & Rochman (2021)[1] as an alternative for extracting polyolefins from environmental samples, achieving high recovery rates (>90%) with dichloromethane (DCM) under high-pressure, high-temperature conditions. The effects of this treatment on the particles' physicochemical properties remain unexplored, as does its applicability to PE of varying characteristics. Additionally, recent studies have examined how different polymer reference materials affect the accuracy of Py-GC-MS when analyzing real samples.[2] This is especially true for PE, which encompasses polymers with very different properties (e.g., low-density PE (LDPE), high-density PE (HDPE), ultra-high-molecular-weight PE (UHMWPE)). More recently, Chae & Choi (2025)[3] explored how PE of different molecular weights exhibits different pyrolysis behaviors, leading to distinct Py-GC-MS responses. This overlooked factor can introduce additional uncertainty into MNP quantification when analyzing samples with known polymer characteristics, such as commercial materials and ecotoxicological assessments. In this ongoing work, we use the MAE strategy to produce a polymer suspension in DCM from commercial PE microbeads. This suspension can later serve as a reference material to build calibration models for Py-GC, achieving a low limit of quantification without requiring expensive weighing equipment. The tests are performed using HDPE and UHMWPE microbeads (130 and 50 μm, respectively) to assess the method's efficiency across different starting materials. All particles are characterized before and after the MAE treatment using Fourier-Transform Infrared Spectroscopy (FTIR, for chemical composition), Scanning Electron Microscopy (SEM, for size and morphology), Py-GC-FID (for pyrolysis behavior), Dynamic Light Scattering (DLS, for Zeta potential), and Differential Scanning Calorimetry (DSC, for thermal transitions). This array of analyses allows us to explore the impact of thermal treatment on the physical-chemical properties of PE particles, the mechanisms underlying the stability of the PE suspension, and, lastly, the extent to which different PE types yield distinct pyrolysis products in Py-GC-MS. MAE treatment successfully produced a PE suspension in DCM, yielding a polydisperse suspension with an average particle size below 10 μm and a recovery rate of 95%. Moreover, HDPE and UHMWPE showed distinct pyrolysis profiles, with different alkane, alkene, and dialkene ratios, highlighting the importance of carefully selecting the reference polymer when building regression models for the analysis of environmental samples.

References: 1 L. Hermabessiere and C. M. Rochman, Environ. Toxicol. Chem., 2021, 40, 2733–2741. 2 M. Brits, B. van Poelgeest, W. Nijenhuis, M. J. M. van Velzen, F. M. Béen, G. J. M. Gruter, S. H. Brandsma and M. H. Lamoree, Polym. Test., 2024, 137, 108511. 3 E. Chae and S.-S. Choi, Polymers, 2025, 17, 576.

Acknowledgment: The authors thank the São Paulo Research Foundation (FAPESP, Proc. 2022/12104-4 and 2025/02149-9).

ABSTRACT. Aviation decarbonization is a key challenge in mitigating climate change due to its emissions of greenhouse gases and fine particulate matter, as well as its strong reliance on energy-dense liquid fuels and the limited availability of scalable low-carbon alternatives compatible with existing infrastructure. In this context, the European Union has established strict mandates for the progressive use of Sustainable Aviation Fuels (SAF). p-cymene, a terpenoid compound with potential as a SAF, has emerged as a promising candidate in this transition. To support its evaluation, it is necessary to study its thermal conversion and the products it generates. Therefore, this work investigates p-cymene pyrolysis and the formation of light gases, soot, and polycyclic aromatic hydrocarbons (PAHs) in soot. Experiments were performed in a flow-reactor installation using a p-cymene concentration of 2000 ppm over a temperature range of 973–1473 K. Selected light gases, such as, hydrogen and acetylene, were analyzed using an Agilent Technologies gas chromatograph. Soot particles were collected at the reactor outlet using a quartz fiber filter with a pore size below 1 µm. The collected soot was subjected to Soxhlet extraction to analyze the 16 EPA-priority PAHs, which were quantified using an Agilent 7890A gas chromatograph coupled with a 5975C mass selective detector (GC–MS). The results indicate that p-cymene exhibits a high soot formation propensity. Soot yield increases with rising temperature, whereas the yields of gaseous species and PAHs contained in soot reach a maximum. At all temperatures, low-molecular-weight PAHs (LMW) (2–3 rings) dominate, followed by medium-molecular-weight PAHs (MMW) (4 rings) and, to a much lesser extent, high-molecular-weight PAHs (HMW) (5-6 rings). The LMW fraction is mainly dominated by naphthalene (NAPH), acenaphthylene (ACNY), and phenanthrene (PHEN), whereas fluoranthene (FANTH) and pyrene (PYR) are the most abundant compounds within the MMW group, and benzo[a]pyrene (B[a]P) is the dominant species among the identified HMW PAHs.

ABSTRACT. The ubiquitous presence of microplastics (MPs) in the environment represents a global challenge, requiring accurate analytical protocols for their identification and quantification. MPs must be unequivocally and unambiguously identified and quantified. Vibrational spectroscopy enables optimal identification and morphological analysis of MPs, micro- and nanoplastics, and plastic additives. However, the size’s LOD is related to the instrument and the pretreatment employed. Additionally, in Micro-FTIR, dark or opaque particles, such as tire wear particles, can be challenging to identify. Conversely, Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) provides robust mass-based quantification and detailed polymer identification, including additives, but loses all information regarding particle shape and size distribution; and it requires a meticulous selection of specific pyrolytic tracers and quantification ions to avoid over- or underestimation of concentrations caused by matrix interferences or co-eluting peaks. Our research group is implementing an integrated analytical workflow that leverages the strengths of both spectroscopic and thermoanalytical platforms. The core of our approach is the sequential or parallel application of EGA/Py-GC/MS (Frontiers EGA-Py 3030D, coupled with Agilent GC 8890 – MS 5977c) and microFTIR (Nicolet iN 10, Thermo Fisher Scientific), on samples of various environmental matrices. This synergy allows us to cross-validate results. Each matrix requires specific pre-treatment and purification steps, optimized to maintain the integrity of the plastic particles for subsequent analysis. Preliminary applications focus on samples collected from various environmental compartments (e.g., sediments, snow), highlighting that the integration of Py-GC/MS significantly improves the quality of the results, cross-validating spectroscopic identification. This integrated approach significantly enhances the robustness of our findings compared to standalone techniques, providing a more comprehensive assessment of the plastic mass balance. However, several methodological challenges are currently under evaluation, including the potential influence of the pretreatment employed formicro-FTIR analysis, on the overall recovery of target polymers in Py-GC/MS. Investigating this aspect is crucial to enable a truly sequential analytical workflow (performing Py-GC/MS directly on the same sample previously analyzed by micro-FTIR), thereby avoiding the need for sample splitting during the preparation phase. Furthermore, we are focusing on optimizing the sample transfer efficiency from the filter to the pyrolyzer cup. Addressing these technical hurdles is essential to harmonize spectroscopic and thermoanalytical data, ultimately providing a more accurate and intercalibrated assessment of microplastic pollution across the environmental compartments investigated. References 1 La Nasa et al., 2020. https://doi.org/10.1016/J.JAAP.2020.104841. 2 Dümichen et al, 2017. https://doi.org/10.1016/j.chemosphere.2017.02.010. 3 Elert et al. 2017 https://doi.org/10.1016/j.envpol.2017.08.074.

ABSTRACT. Analytical techniques based on pyrolysis are now widely recognized as powerful and sensitive tools for characterizing and quantifying polymers in environmental samples. Among all microplastics, Tire and Road Wear Particles (TRWP) form a distinct class of polymeric microparticles, generated through the friction between tires and road surfaces during driving and braking. Tires are complex industrial formulations, composed of rubber polymers such as Styrene-Butadiene copolymer (SBR), and Butadiene rubber (BR), alongside carbon black, silica, vulcanisation agents, and various additives. Despite their prevalence, the transport pathways, environmental fate, and toxicological impacts of TRWP remain poorly understood. However, TRWP are believed to contribute significantly to the microplastics (MP) load in terrestrial environments.

In 2017, an ISO/TS 21396:2017 technical specification based on pyrolysis coupled to gas chromatography and mass spectrometry (Py-GC/MS) was published, establishing several recommendations for TRWP quantification. However, challenges remain, and several improvements are still ongoing with significant refinements published since.

In this work, a robust and thorough instrumental development was carried out, integrating two thermal analytical devices based on pyrolysis: Rock-Eval® and Py-GC/MS (CDS 6200 Pyroprobe Pyrolyzer). Polymer standards and deuterated internal standards were used to calibrate the instruments. Pyrolysis conditions were optimized, and the complementarity of both instruments was especially useful to accelerate this step. Characteristic dimers were proposed, and specific ions (both target and diagnostic m/z) were identified for Py-GC/MS analysis.

Once the method was optimized, it was applied to real tire formulations representative of the current market. A dedicated sample preparation workflow was developed, including cryomilling. The method demonstrated satisfactory recoveries, with biases remaining below 20% in soil samples spiked with 200 µg of crushed tire material. Additionally, ageing processes were examined through a comparative analysis of the inner and outer layers of a tire retrieved from a landfill. The inner layer, protected from weathering, exhibited a distinctly different molecular fingerprint compared to the outer layer, which had undergone environmental exposure. These findings highlight specific alterations in the outer layer and raise concerns regarding the leaching of compounds into the environment during tire ageing.

ABSTRACT. Per- and polyfluoroalkyl substances (PFAS) are increasingly regulated because of their persistence and potential risks to human health. With the proposed EU Packaging and Packaging Waste Regulation (PPWR), polymeric PFAS such as polytetrafluoroethylene (PTFE) are now subject to stricter regulatory requirements in packaging materials, driving the need for reliable analytical methods for complex polymer systems. For polymeric PFAS, qualitative analysis by pyrolysis-GC/MS (Py-GC/MS) and quantification of total fluorine by combustion ion chromatography (CIC) are commonly used. However, CIC has limitations in the analysis of mixed polymer systems. In this study, we aimed to improve the quantitative performance of Py-GC/MS for polymeric PFAS by optimizing analytical conditions for PTFE in different polymer matrices.

Polystyrene (PS)-0.17 % PTFE mixture was prepared by weighing 500 mg of PS powder and 0.85 mg of PTFE powder and homogenizing them at 2000 rpm for 1 h using a rapid cryogenic mill (IQ MILL-2070). Nylon-6,6 (N66)-0.18 % PTFE mixture was prepared in the same manner using 500 mg of N66 powder and 0.90 mg of PTFE powder. Measurements were carried out using a Py-GC/MS system equipped with a pyrolyzer (EGA/PY-3030D, Frontier Laboratories), an Auto-Shot Sampler (AS-2020E, same above), a Selective Sampler for temperature-fractionated gases (SS-2010E, same above), and a MicroJet Cryo-Trap (MJT-2030E, same above). A deactivated pre-column (0.25 mm i.d., 2 m length, same above) was connected to a metal capillary separation column (5% diphenyl polysiloxane, 30 m length, 0.25 mm i.d., 0.25 µm film, same above). Conventional Py-GC/MS (PY) measurements were carried out by introducing the mixture sample into a furnace preheated at 650 °C, followed by cryogenic trapping and chromatographic separation of pyrolyzates. For double-shot Py-GC/MS (DS), the sample was initially heated from 100 to 540 °C to remove PS- or N66-derived fractions. Subsequently, the residue containing PTFE was pyrolyzed at 650 °C, and the pyrolyzates were cryogenically trapped and analyzed. Quantitative analysis was performed using the peak area of the extracted ion chromatogram (EIC) at m/z 81 which is a characteristic ion of tetrafluoroethylene derived from PTFE. Reproducibility was evaluated by five repeated measurements of 1 mg each of mixture samples. 10 µg of PTFE standard sample was measured before and after the measurements of the mixture samples, and responses were compared after correction by the sample amount.

Pyrograms of the PS-based sample obtained by both PY and DS methods are shown in Figure 1. In PY, various pyrolyzates derived from both PTFE and the polymer matrix were detected. In contrast, DS showed very simple pyrograms, with tetrafluoroethylene being the dominant peak, indicating the significant reduction of polymer matrix interferences. However, even in the DS measurements, the N66-based sample showed a lower response of tetrafluoroethylene than the PS-based sample. This difference is likely attributable to co-pyrolysis of PTFE with partially undecomposed N66 remaining after the 1st heating step in DS. Since the reduction of the response of tetrafluoroethylene was much smaller in DS compared to PY, the use of double-shot pyrolysis improves the quantification of trace PTFE in polymer materials.

ABSTRACT. 1. Introduction Since the early 2000s, microplastic pollution in the ocean has been recognized as a global environmental issue. In 2016, microplastics were found to exist not only in the ocean but also in the atmosphere1). Analysis of airborne microplastics (AMP) has been advanced by numerous research groups following this report. However, several challenges remain, including the lack of standardized analytical methods and the limited number of samples. In this study, airborne particles collected at our laboratory since 2000 for environmental behavior of radionuclides. AMP were qualitatively and quantitatively analyzed using evolved gas analysis-mass spectrometry (EGA-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Various analytical conditions were determined based on the study by Mizuguchi et al.2). AMP samples were continuously collected in Kanagawa Prefecture, located in the urban area of Japan. Therefore, we aimed to investigate the long-term variations in AMP within urban areas. 2. Experiment The airborne particles samples were collected at the Meiji University in Kanagawa Prefecture (35°35’52” N, 139°32'59" E), using a high-volume air sampler (Sibata Scientific Technology Ltd., Japan, HV-500R). The air was vacuumed at a flow rate of 500 dm3 min-1 for 24 hours. The AMP collected on glass fiber filters (Advantech Co., Ltd., Japan, GB-100R). Airborne particles samples collected in 2005, 2011, 2015, 2018, and 2025 were analyzed to investigate chronological variations. Each filter was punched out in 4 mm diameter disks, and the three disks were put into a sample cup (Frontier Laboratories Ltd., Japan, Eco-Cup LF) for measurement of EGA-MS and Py-GC/MS. 3. Results and discussion The evolution of CO2 (m/z 44), hydrocarbons (m/z 57), and phthalate esters (m/z 149) were detected by EGA-MS in all measured samples. Comparison of the extracted ion chromatograms (EIC) at m/z 149 revealed intensity differences between samples. The abundance of the ion (m/z 149) contained in 1 mg of the sample (compound amount 149) was calculated for each sample. The investigation of the chronological variations in the compound amount 149 showed a steady upward trend. The EIC of m/z 149 is a typical indicator for phthalates2). Therefore, an increase in the amount of microplastics contained in the airborne particles has been suggested. 1) R. Dris, et. al.: Marine Pollution Bulletin, 104, 290 (2016). 2) H. Mizuguchi, et. al.: Journal of Analytical and Applied Pyrolysis, 171, 1 (2023).

ABSTRACT. The increasing generation of waste biomass and its associated greenhouse gas (GHG) emissions necessitate effective waste management strategies. This study provides a comparative assessment of greenhouse gas reduction potential between pyrolysis and combustion technologies for waste biomass. Pyrolysis, a thermochemical process that converts organic material into biochar, bio-oil, and syngas, is evaluated alongside combustion, which directly converts biomass into energy through oxidation.Through a detailed analysis of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions, we quantify the GHG emissions associated with both processes. The study employs life cycle assessment (LCA) methodologies to evaluate the environmental impact and overall sustainability of each technology. Results indicate that pyrolysis significantly reduces GHG emissions compared to combustion by sequestering carbon in biochar and producing less CO2 per unit of energy generated.In addition, the economic viability and scalability of both technologies are discussed, highlighting the importance of policy frameworks in promoting sustainable waste management practices. This research underscores the need for transitioning towards pyrolysis as a more environmentally friendly alternative in the quest to mitigate climate change while effectively managing waste biomass.

ABSTRACT. This study developed a microwave (MW)-based pre-treatment of tire wear particles (TWPs) to remove inorganics and investigated the effect of such pretreatment on their pyrolytic behavior. Tire and road wear particles (TRWPs) are among the major sources of plastic pollution in the environment. Their detection and characterization remain challenging due to their high carbon black content, which strongly interferes with commonly used spectroscopic techniques for microplastic (MP) analysis, such as infrared and Raman spectroscopy. As a result, alternative analytical approaches are required. Thermo-analytical techniques, including pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), have therefore gained increasing interest for the detection and analysis of TRWPs through their characteristic thermal degradation products. However, the complex and heterogeneous composition of tire materials complicates both the detection and accurate quantification of these particles. Matrix interferences and variability in pyrolysis products can significantly affect analytical results. Consequently, the development and optimization of appropriate sample pre-treatment strategies are essential to reduce matrix effects and improve the reliability and accuracy of TRWP quantification in environmental samples. MW-assisted extraction and digestion is a promising tool for MP analysis in environmental samples, as it provides high efficiency while requiring shorter times compared to other methods. However, no application of MW to TWPs has been presented in the literature. In this study, MW digestion was used to remove zinc from TWPs. Zinc is a characteristic constituent of tire materials and is known to impact polymer pyrolysis behavior. Experimental conditions were optimized based on the zinc concentration extracted into the filtrate following digestion and filtration. Calibration curves obtained by Py-GC-MS using cryo-milled tire tread as standard revealed significant discrepancies between treated and untreated particles, indicating an impact of the pre-treatment on the pyrolytic response of the investigated polymers. Additionally, this study investigated the importance of the use of internal standards. When deuterated standards, including deuterated styrene butadiene rubber and deuterated polyisoprene were added directly to the pyrolysis cups, the previously observed linear relationship between sample mass and pyrolysis product peak area was no longer observed. These results suggest potential interactions between the internal standards and the polymers within the tire matrix.

ABSTRACT. In the current era of plastic pollution, human exposure to micro- and nanoplastics (MNPs) has emerged as a critical global health concern. Emerging evidence indicates that MNPs are present across diverse biological systems. However, insufficiently developed, standardized, and sensitive analytical protocols continue to limit accurate exposure assessment and biomonitoring. Reliable detection strategies based on minimally invasive human biomarkers such as keratinous tissues (hair, nails) and blood are therefore essential for evaluating both long-term accumulation and recent exposure. This study focuses on the optimization of pre-treatment protocols for the isolation and detection of MNPs from human biological matrices using analytical pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). Keratinous tissues pose a major analytical challenge due to their highly cross-linked keratin structure and associated proteins. Alkaline digestion using potassium hydroxide (KOH) was systematically optimized to cleave keratin-associated proteins and disrupt disulfide crosslinks, enabling efficient matrix breakdown. A combined KOH–hexane treatment was further employed to enhance lipid removal, reduce matrix interference, and improve polymer recovery. For blood and clot samples, alkaline digestion effectively disintegrated fibrin networks and protein aggregates, facilitating the release of potentially entrapped MNPs. The optimized protocol is being refined to enable processing of larger sample quantities with reduced biological interference, with the aim of improving detection sensitivity. Py-GC/MS analysis demonstrated enhanced signal-to-noise ratios and improved reproducibility, enabling more reliable intensity-based relative quantification. While endogenous aromatic and aliphatic compounds posed challenges in differentiating polymer-specific ion markers, careful spectral interpretation enabled robust identification of characteristic pyrolysis products. Recurrent detection of styrene-derived peaks and associated additives across multiple trials indicated the presence of polystyrene-related residues, confirming the analytical applicability of the developed method. Comparison of MNP signatures in blood and hair matrices is expected to elucidate their complementary roles as biomarkers, where blood may reflect recent exposure and keratinous tissues may indicate long-term accumulation. The proposed workflow establishes a practical and scalable framework for human biomonitoring of MNP exposure and provides a foundation for future epidemiological studies and health risk assessment. The development of harmonized analytical protocols such as this is essential for advancing large-scale monitoring efforts and informing evidence-based policy measures aimed at mitigating plastic-related health risks.

ABSTRACT. Each year in the United States, more than 280,000 tons of plastic is dumped into rivers across the country. While there are many major waterways and bodies of water that have become contaminated with plastics contamination throughout the country, the mid-Atlantic region of the United States has uniquely defined positioning, being within the boundaries of both the Chesapeake Bay and Delaware Bay Watersheds, which is home to nearly 8% of the United States total population. The Chesapeake Bay Watershed is the country’s largest estuary, with more than 150 rivers known to drain into the Chesapeake Bay. It is additionally well-known for its biodiversity and contribution to agricultural production. On the other hand, the Delaware Bay Watershed contains the major port city of Philadelphia, supplying water to other major metropolitan areas outside its geographic boundaries such as New York City. The Delaware Bay Watershed is considered to be a top contributor of microplastics pollution flowing into the Atlantic Ocean in North America.

Due to the ecological and economical importance of both watersheds to the coastal mid-Atlantic regions of the US, the characterization of microplastics has already gathered interest in recent years. In each instance, the primary focus of such studies has been characterizing particle concentrations in either the bay or coastal areas via Raman spectroscopy. While other information, such as size and shape, is gained about the microplastics particles, it is not possible to quantify the concentrations of individual polymers. Consequently, the contributing polymers discussed have largely been limited to polyethylene (PE) and polypropylene (PP). This is to be expected, as they are the most widely used polymers in consumer plastic products.

To this point, there is a lack of contributing datasets to microplastics contributions in the mid-Atlantic region of the US using pyrolysis-gas chromatography mass spectrometry (py-GC-MS). Both the headquarters of CDS Analytical and Lincoln University are located in Chester County, in southeast Pennsylvania, US, which is geographically influenced by rivers emptying into both the Chesapeake Bay and Delaware Bay Watersheds. The work presented here establishes a geographic layout for collecting water samples from various locations along selected rivers leading down to the mouth of the rivers emptying into the bay. After the collection of water samples, a sample preparation procedure of filtration onto a quartz filter followed by cryogenic milling is utilized. Final polymer identification and quantification is then done using py-GC-MS. The results are expanded to polymers other than PE and PP to include other known plastic contaminants in water such as polyethylene terephthalate, polystyrene, and nylon. Furthermore, the results are further described by the potential implications on ecology, the economy, and human health.

ABSTRACT. Microplastic (MP) pollution has been acknowledged as a global threat and presently one of the most pressing environmental issues. Different analytical techniques have been applied and optimized for the analysis of MP and of non-polymeric organic compounds associated with them, such as additives, persistent organic pollutants, and polymer degradation products. Nevertheless, there is still a major lack of understanding of the interaction mechanisms between these classes of pollutants and ecosystems. Analytical pyrolysis-based techniques have proven to be effective in the analysis of MP in environmental samples, providing mass-based quantification of different polymers, along with the quantification of MP-associated organic contaminants. However, depending on the environmental matrix, sample pretreatment before analysis can require numerous and time-intensive steps. In this work, we tested and optimized a new one-pot microwave sample pretreatment that allows for a comprehensive overview of the contaminants and microplastics present in the sample. The method was developed using mussels fed with microplastics (PP, PE, and N6), in order to work with a complex and challenging matrix rich in protein and lipids. We combined microwave-assisted extraction with thermal desorption and analytical pyrolysis coupled with gas chromatography and mass spectrometru (Py-GC-MS) to characterize and quantify different classes of pollutants frequently associated with MPs in biological samples [1,2], such as phthalate plasticizers, as well as contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and other contaminants of emerging concern (CECs). The same sample was subsequently processed through microwave digestion in order to characterize and quantify the MPs content. Different conditions were tested to obtain the most efficient digestion approach while limiting polymer degradation. This new rapid method paves the way for future applications to other biological samples, particularly human samples. Such an extension would enable direct assessment of human exposure to microplastics and related pollutants, offering valuable data for public health research and environmental risk assessment.

Acknowledgement: This work was carried thanks to the financial support of NAMC (North Atlantic Microplastic Centre), the funding from the European Union - Next-GenerationEU - National Recovery and Resilience Plan (NRRP) – MISSION 4 COMPONENT 2, INVESTIMENT N. 1.1, CALL PRIN 2022 D.D. 104 02-02-2022 – DIORAMA (A deep dive into the study of microplastics in aqueous matrices), and the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4 of MUR by the European Union’s NextGenerationEU (Project CN 00000033, Decree No. 1034 of June 17, 2022 adopted by the MUR, CUP I33C22001300007, Project title “National Biodiversity Future Center-NBFC”). We acknowledge the NORCE Mass Spectrometry Lab for instrument access and expert support.

References: [1]. Biale et al., Characterization and quantification of microplastics and organic pollutants in mussels by microwave-assisted sample preparation and analytical pyrolysis, Environmental Science: Advances, 2024, https://doi.org/10.1039/D3VA00216K [2]. La Nasa et al., Microwave-assisted solvent extraction and double-shot analytical pyrolysis for the quali-quantitation of plasticizers and microplastics in beach samples, Journal Of Hazardous Materials, 2021, https://doi.org/10.1016/j.jhazmat.2020.123287

ABSTRACT. Hypercrosslinked polymers (HCPs) are a versatile class of porous organic polymers characterised by their micro/mesoporous networks formed through extensive covalent crosslinking. Typically synthesised via Friedel–Crafts alkylation of aromatic precursors, HCPs can be constructed from a wide range of monomers and linking strategies, enabling the fine-tuning of chemical functionality, pore structure, and surface polarity. Application of such materials is in the capture of (very) volatile organic compounds for analytical purposes, water harvesting from air, or efficient removal of various cations from wastewater [1]. Due to their highly crosslinked nature, structural characterization possibilities of the material are very limited. Using analytical pyrolysis, we have developed a means of not only identifying different monomers incorporated into the HCPs, but also providing a quality control to monitor remaining crosslinking agents and impurities.

[1] Paul Schweng, Elias Rippatha, Clemens Schwarzinger, Robert T. Woodward, Hypercrosslinked Polymers for Volatile and Very Volatile Organic Compound Capture Beyond Commercial Benchmarks, Angew. Chem. Int. Ed. (2025), https://doi.org/10.1002/anie.202513362

ABSTRACT. Plastic debris is now ubiquitous in natural environments and progressively accumulates within sedimentary systems such as rivers, beaches, and the deep seafloor. During transport with natural sediments, plastics are exposed to repeated mechanical stresses that promote abrasion and fragmentation through sediment-plastic interactions. This results in the formation of micro and nanoplastics and increases the exposed surface area, thereby enhancing the release of plastic associated chemicals. To date, more than 16,000 chemicals have been identified in plastics, including functional additives, processing aids, starting substances, and non-intentionally added substances. As most of these compounds are not covalently bound to the polymer matrix, they can leach into the environment. However, the mechanisms governing plastic fragmentation in sedimentary systems and its interaction with chemical leaching processes are still poorly understood, due to analytical challenges and therefore limiting robust assessments of the related ecological risk. In this scenario, the PLASTICAL project (Fragmentation and Abrasion of Plastics by Sediments and Chemical Additive Leaching) aims to address these knowledge gaps by investigating plastic fragmentation and abrasion during sediment transport and its relationship with additive release. For this purpose, we investigated two conventional polymers (polyethylene terephthalate and polyamide 6.6) and two biodegradable ones (polylactic acid and polybutylene adipate terephthalate) selected for their different mechanical properties. Plastic samples were produced in-house by injection moulding in two formulations: (i) neat polymers and (ii) polymers compounded with the additives Irgafos 168 and Irganox 1010. Samples were analysed using a combination of large-volume pyrolysis adsorption with thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS/MS). Pyrolysis was performed in a stand-alone tube furnace with programmable temperature with the resulting pyrolyzates trapped on a non-polar sorbent tube and subsequently desorbed in a TD unit coupled to a GC-MS/MS system. Analytical methods were optimised to identify characteristic pyrolysis markers for each polymer and for both additives, with emphasis on reproducibility, selectivity, and sensitivity. These markers will be applied in laboratory experiments simulating sediment induced abrasion and fragmentation to trace plastic particles and additive leaching under varying sediment grain characteristics.

ABSTRACT. Microplastics (MPs) are generally described as small plastic particles, with dimensions between 1 mm and 1 µm, classified as primary and secondary MPs. While the presence of microplastics (MPs) in marine and terrestrial environments is well documented [1], the impact of airborne MPs remains a topic of ongoing research, especially in indoor environments, making them relevant for assessing long-term exposure risks [2]. In this study, we quantified the mass concentrations of airborne microplastics in indoor working environments using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Air sampling was conducted in different factories and treatment plants in central Italy, where various plastic materials are mechanically processed. For each factory, sampling was performed in three working areas: (i) primary production areas, where plastic materials undergo intensive handling and are expected to generate the highest MPs concentration; (ii) secondary production areas, characterized by lower plastic manipulation; and (iii) offices, where minimal plastic processing occurs, and airborne MPs concentrations are expected to be lower. Air samples were collected through active sampling using quartz filters for Py-GC-MS, which were subsequently punched and directly analyzed by Py-GC-MS. By using this approach, we accurately quantified the concentrations of airborne MPs in different areas of the working environment. Py-GC-MS analysis enabled the determination of eleven different polymers: polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), acrylonitrile butadiene-styrene (ABS), styrene-butadiene rubber (SBR), polyethylene terephthalate (PET), polycarbonate (PC), nylon 6 (N6), and nylon 66 (N66). The results for a plastic waste separation plant showed a spatial trend in airborne MPs concentrations, with higher levels detected in primary production areas and in the workers’ personal air samples, followed by secondary production areas, and the lowest concentrations observed in offices (Figure 1).

Figure 1: MPs concentrations (µg/m3) in different working areas in a plastic waste recycling plant.

References [1]: X. Zhai et al., “Characterization and quantification of microplastics in indoor environments,” Heliyon, vol. 9, no. 5, p. e15901, May 2023. [2]: D. Pomata et al., “Plastic breath: Quantification of microplastics and polymer additives in airborne particles,” Science of The Total Environment, vol. 932, p. 173031, Jul. 2024.

ABSTRACT. Micro- and nanoplastics (MPs and NPs) are among the most debated emerging contaminants of the last decade. Despite the substantial expansion of scientific research on this topic, their comprehensive assessment remains challenging. N/MPs are known to be globally distributed, as they can be resuspended and transported over long distances by wind and atmospheric processes. Therefore, atmospheric deposition (dry and wet) acts both as a dispersal pathway and as a sink, transferring plastic particles from the atmosphere to terrestrial and aquatic environments, with potential implications for ecosystems and human exposure. Identification methods for MPs have been optimized across various analytical approaches, mainly spectroscopic and thermal techniques; however, accurate quantification remains challenging. This difficulty largely stems from the heterogeneity of the polymers, as well as from the heterogeneity and complexity of environmental matrices, which complicate the isolation of plastic particles. In addition, the smallest size fractions (sub-micrometric particles, NPs) frequently remain undetected, despite their potential relevance due to possible interactions at cellular and subcellular levels. This study proposes a methodological framework for the identification and quantification of N/MPs in the size range from 0.3 μm to 0.3 mm in total atmospheric deposition (dry and wet). Samples were collected over a four-month period using a Bulk® deposition sampler in the urban area of Rimini (Italy). The workflow included a pre-concentration step in which deposition samples were sieved at 0.3 mm to remove visible macrofragments and coarse biogenic material, followed by chemical pretreatment with an optimized sono-Fenton oxidation to reduce the organic load. The treated samples were then filtered onto quartz membranes (pore size: 0.3 μm). The loaded filters were subsequently analyzed qualitatively and quantitatively by pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS), enabling direct measurement of polymer components associated with airborne particulates collected on quartz filters. Reactive Py-GC-MS was employed using tetramethylammonium hydroxide to minimize interactions between polymer pyrolysis products and those originating from the residual matrix. An internal standard calibration protocol was developed to ensure repeatability and reproducibility. Method validation was performed on commercial plastic particles, both unaged and after UV aging, without matrix inclusion in recovery tests. Preliminary results indicated the presence of the most common polymers and mean atmospheric deposition over the sampling period was approximately 40 μg m⁻² day⁻¹. The method showed good precision, and recovery tests were satisfactory. However, the presence of refractory organic compounds, particularly humic substances and lignin, was highlighted. Consequently, Py-GC-MS quantification must account for matrix-specific interferents, underscoring the need for site-specific method validation prior to routine application.

ABSTRACT. A novel approach based on pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) using Benzothiazole as a marker that is tightly bound to the tyre matrix will be described (1 -3). Benzothiazole is a pyrolysis product from benzothiazole sulfenamides which act as crosslinking agents for vulcanization. They act as cure accelerators and control the vulcanization rate and crosslink density. Benzothiazole moieties are bound into the polymeric structure and released by cleavage of weaker C-S bonds during pyrolysis. Chromatograms from the Py-GC/MS of riverine sediments from the Thames, Avon and Medway will be presented (Fig. 1) and a calibration curve based on a deuterated internal standard will be discussed giving a Limit of Quantification (LOQ) of ~ 1 ng/ mg of sediment. Other markers will also be described for some synthetic car tyre rubbers including Styrene-Butadiene Rubber (SBR) and Butadiene Rubber (BR).

Figure 1. Fig. 1 Total ion chromatograms from the Py-GC/MS of riverine sediments from the rivers Thames, Medway and Avon

ABSTRACT. Environmental contamination by plastic debris is a major global challenge, driving rapid growth in the development and use of bioplastics (BPs) as alternatives to conventional polymers. Although BPs are often perceived as less harmful because they can degrade, their chemical safety and environmental fate remain poorly understood. Many BP products contain additives similar to those used in petroleum-based plastics, and their leachates may exhibit comparable toxicity to ecosystems and humans. Moreover, under soil conditions, bio-based polymers are frequently not readily decomposed by microorganisms, and complete mineralization typically requires specific conditions (e.g., elevated temperature, sufficient moisture, oxygen availability, and active microbial communities) that are uncommon in natural ecosystems and more representative of industrial composting [1,2]. Consequently, materials marketed as biodegradable may persist and fragment rather than fully mineralize, generating micro- and nanobioplastics (BMPs/BNPs) with potential impacts similar to conventional micro- and nanoplastics. Emerging evidence also suggests that BPs can alter soil microbial community structure and influence plant growth [3], yet data on BP occurrence in soils and effects on soil processes remain limited. This study assessed the effects of biodegradable bioplastics on soil organic matter (SOM) and dissolved organic matter (DOM) and investigated the formation and persistence of residual fragments and BMPs/BNPs in soil under controlled laboratory conditions at two application rates. An analytical characterization was performed on soils amended with commercial biodegradable polymers and incubated for 100 days. Soil samples were analyzed before amendment and after incubation with polylactic acid and starch-based bioplastics using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), evolved gas analysis-mass spectrometry (EGA-MS), thermogravimetric analysis (TGA), headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS) and particle size analyzers (PSA) to elucidate changes in SOM/DOM composition and the polymer/additive signatures associated with soil exposure. Overall, the thermoanalytical results were consistent across Py-GC-MS, EGA-MS, and TGA, indicating no detectable compositional changes in the bioplastics attributable to the applied aging treatment over the timescales investigated. However, EGA-MS and TGA allowed differentiation between aged and unaged commercial bioplastics, indicating that incorporation into soil for 100 days can modify their thermal behavior and related properties. In addition, Py-GC-MS analyses of incubated soils, complemented by PSA, suggested the possible presence of in situ micro-bioplastic formation, supporting the view that fragmentation can occur even for materials marketed as biodegradable under typical soil conditions. Furthermore, combined evidence from Py-GC-MS and HS-SPME/GC-MS suggested that bioplastic residues can affect the soil DOM pool, implying shifts in DOM quality and turnover dynamics. Collectively, these findings improve our understanding of the environmental fate of biodegradable plastics in soil and underscore the need to evaluate both particle generation and SOM responses when judging the sustainability of bioplastic alternatives.

References [1] Withana, P. A., Yuan, X., Im, D., Choi, Y., Bank, M. S., Lin, C. S. K., Hwang, S. Y., Ok, Y. S. (2025). Environ. Sci.: Process. Impacts, 27, 3321–3343. [2] Fan, P., Yu, H., Xi, B., Tan, W. (2022). Environ. Int., 163, 107244. [3] Liu, X., Wen, Z., Zhou, W., Dong, W., Ren, H., Liang, G., Gong, W. (2025). Microorganisms, 13(2), 259.

ABSTRACT. Basaltic lava tubes are considered excellent natural testbeds to evaluate how biosignatures are introduced, altered, and ultimately preserved under low-light, mineral-rich, and microbially active conditions. In this contribution, we integrate bulk and molecular approaches, such as elemental analysis coupled to isotope ratio mass spectrometry (EA/IRMS), traditional analytical pyrolysis (Py-GC/MS), and the novel pyrolysis compound-specific isotope analysis (Py-CSIA) for carbon and hydrogen (δ¹³C and δ²H, respectively), to decipher the molecular composition and isotope systematics of organic matter (OM) preserved in speleothems from the Corona Lava Tube (Lanzarote, Canary Islands, Spain), a Mars analogue subsurface environments. During the ESA PANGAEA-X astronaut training program, we investigated four different matrices representing potential OM sources and sinks along a surface-to-cave gradient: a dark microbial mat enriched in organics, a whitish cave deposit dominated by mineral phases, the soil layer directly above the cave, and nearby Euphorbia balsamifera vegetation. The Py-GC/MS fingerprints showed clear differences between surface-derived inputs and cave-associated organics, while the Py-CSIA added a decisive layer of information by tracking δ¹³C and δ²H at the compound level. The cave matrix exhibited isotope patterns that are distinctive from the surface endmembers, consistent with different transformation pathways and substantial microbial overprinting. In particular, ¹³C compound-specific value changes in sterol- and lignin-related pyrolysates suggest intensive recycling and/or selective stabilization within the mineral framework, whereas hydrogen isotopes (δ²H) point to meteoric water signals combined with diagenetic modification during subsurface residence. Taken together, these results demonstrate that Py-CSIA can resolve subtle biosignature-relevant information even when total OM is low and strongly altered. The combined molecular and isotope workflow presented here offers a transferable strategy to assess the detectability and interpretation of organic traces in volcanic subsurface environments, and supports the development of life-detection concepts for Martian lava tubes. Acknowledgments: This work was supported by the Spanish Ministry of Science and Innovation (MCIN/AEI/ 10.13039/501100011033) under the research project TUBOLAN PID2019-108672RJ-I00 and by the Spanish National Research Council (CSIC) through the intramural project PIE_20214AT021. We acknowledge the financial support from the Portuguese Foundation for Science and Technology (FCT) under the MICROCENO project (10.54499/PTDC/CTA-AMB/0608/2020), and from the MICROLAVA project (PROYEXCEL_00185) funded by the Andalusia Regional Government. N.T.J.M. thanks the support from the Ramón y Cajal contract (RyC2021-031253-I) funded by MCIN/AEI/10.13039/501100011033 and the European Union “NextGenerationEU”/PRTR. We thank the Cabildo de Lanzarote and the Lanzarote and Chinijo Archipelago Geopark for granting permission to access the La Corona Lava Tube system and collect samples. Field activities and sample collection were partially supported by the ESA PANGAEA-X training program. We are grateful to ESA astronaut Matthias Maurer for his dedicated involvement in collecting the samples analyzed in this study during the field training. We also thank Loredana Bessone, director of ESA’s PANGAEA program, for her leadership and support in facilitating this multidisciplinary campaign.

ABSTRACT. For the analysis of microplastics (MPs) in water by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), MPs are usually collected by filtration after appropriate sample pretreatment and subsequently introduced into a pyrolyzer. A commonly used approach involves filtering MPs onto a fiber filter, folding the filter, and placing it into a pyrolysis sample cup. However, microplastic particles are known to adsorb onto glassware surfaces, making thorough rinsing essential to achieve acceptable recovery. Previously, we developed a filtration device to address the issue1). Nevertheless, the effective filtration area remained limited, requiring several hours to process water samples on the order of tens of liters, and the filter section was prone to clogging, resulting in a significant decrease in filtration efficiency. In this study, we developed an improved device, which achieves a substantially higher processing speed while simplifying sample handling. This paper reports on the performance evaluation of the device and its application to the collection and pyrolysis of MPs in clean water.

The device consists of a 300 mL funnel, a filtration/collection unit, a 1000 mL receiving flask, and a vacuum pump. A 1 µm opening-size metal filter was placed in a deactivated stainless-steel sample cup (4 mm i.d., 8 mm height) with a 1 mm through-hole at the bottom, referred to as the collection cup. This collection cup covered by a metal filter enables both filtration of MPs from water and direct Py-GC/MS measurements using the same cup. To improve processing speed, the filtration unit was newly designed to tightly seal the collection cup, minimizing the inflow of ambient air during filtration. Py-GC/MS measurements were carried out using a micro-furnace pyrolyzer (EGA/PY-3030D, Frontier Laboratories) directly coupled to a GC/MS system. To improve the sensitivity for trace-level MPs, F-splitless Py-GC/MS measurements were carried out using a Multi-Functional Splitless Sampler (MFS-2015E, same as above)2). Processing speed was evaluated using 300 mL of ultrapure water. For recovery tests, 0.150 mg of polyethylene (PE) microparticles (average diameter 10 µm) was dispersed in a water/ethanol (3:2) mixture and filtered using the device. Recovery was determined gravimetrically. For application to clean water analysis, ultrapure water stored in a PE container (10 L) was filtered, and the collected particles were pyrolyzed at 600 °C.

The processing speed of the device was approximately 180 mL/min, representing 3.2 times faster than the previously reported device. Recovery tests using PE microparticles yielded recoveries exceeding 80% in all measurements with the RSD value of 3.8 % (n=5). As shown in Figure 1, the pyrogram obtained from particles collected from the ultrapure water stored in the PE container showed clear peaks attributable to pyrolyzates of PE, such as 1,20-heneicosadiene. Quantitative results indicated a PE concentration of 11.8 ppb in the stored ultrapure water. These results demonstrate that the combination of the new collection device and Py-GC/MS enables rapid and reliable collection and quantification of trace MPs in water.

References: 1) Y-M. Kim et al., Anal. Methods, 39 (2024) 6751. 2) K. Tei et al., J. Anal. Appl. Pyrolysis, 168 (2022) 105707.

ABSTRACT. With the increasing detection of micro- and nanoplastics (MNPs) in human biological samples, addressing concerns regarding exposure and health risks has become a priority. Exposure assessments currently rely on pyrolysis coupled to gas chromatography–mass spectrometry (Py-GC-MS), which quantifies plastics based on polymer-specific markers. A major challenge in Py-GC-MS is the risk of overestimating polymer concentrations when non-plastic matrix components generate identical markers during the pyrolysis process. Such interferences can distort toxicological findings and heighten public concern, yet consistent quality control measures to prevent these misidentifications are often lacking, leaving the reliability of much exposure data in question.

To address these limitations, we utilized cyclic ion mobility spectrometry (cIMS) combined with high-resolution mass spectrometry (HRMS) for MNP quantification. The enhanced resolving power and background reduction of Py-GC-cIMS-HRMS provide greater analytical specificity, helping to eliminate false-positive results. We implemented a non-target screening approach to detect MS features that uniquely correspond to PE, PP, PS, PET, PVC, and PMMA. In our analysis, peak picking identified 35,365 MS features, which were then evaluated using linear calibration models. Based on the resulting coefficients of determination (R2) and matrix effects, we identified optimal markers for each polymer that remained stable even within complex sample matrices.

Preliminary results show that PE is particularly prone to overestimation when using standard short-chain α-alkene markers; however, long-chain α-alkenes and α,ω-alkadienes proved to be more robust against matrix effects. For PET, we observed potential underestimation, likely due to co-pyrolysis with residual matrix. These matrix interferences appear more significant than previously reported, which we attribute to the use of single-shot pyrolysis, the common standard in MNP analysis. By contrast, double-shot pyrolysis allows for the removal of volatiles before polymer degradation, reducing the production of nonspecific fragments like α-alkenes and minimizing co-pyrolysis for reactive polymers like PET. These findings highlight the efficacy of Py-GC-cIMS-HRMS in refining marker selection and improving the overall accuracy of MNP exposure data.

ABSTRACT. Pyrolysis coupled with gas chromatography-mass spectrometry (Pyr-GC-MS) is a rapidly evolving technique for microplastic analysis. However, its application to biological matrices is analytically challenging due to their high organic matter contents, co-pyrolyzing biomacromolecules and the formation of overlapping pyrolysates that can complicate polymer quantification. In this study, we discuss how we addressed these challenges by optimizing Pyr-GC-MS conditions: the retention time was locked to styrene monomer and a post-column backflush was installed, which together minimised matrix-induced challenges related to instrument instability, retention time shifts and ion source fouling. The C21-α,ω-alkene (1,20-heneicosadiene) proved to be a reliable marker that prevented false positive detection of polyethylene. Nylon 6, styrene-butadiene rubber and poly(vinyl chloride) were reliably quantified at concentrations of 0.24–10.60 µg/g in edible crab tissues. Polystyrene, polypropylene, poly(ethylene terephthalate) and nylon 66 were detected below their limits of quantification. Interference from several discrete propylene oligomers led to false negative detection of polypropylene by suppressing the relative yield of its target quantification marker (2,4-dimethyl-1-heptene). By monitoring more pyrolysates per polymer and qualitative inspection of pyrograms, it was possible to identify samples that contained polypropylene and poly(methyl methacrylate), complementing results obtained by micro-Fourier transform infrared imaging.

ABSTRACT. This research leveraged metagenomic sequencing to assess microbial diversity and functional activity structures during solid-state co-anaerobic fermentation of cattle manure with weathered coal, aiming to evaluate key metabolic pathways. Results demonstrated that co-anaerobic fermentation significantly enhanced biomethane production, concomitant with substantial upregulation of carbohydrate-active enzymes including cellobiose phosphorylase (GH94), glycosyltransferase (GT4), and glycoside hydrolase (GH18). The process reinforced microbial interspecies electron transfer through enrichment of 2-oxoglutarate/2-oxoacid ferredoxin oxidoreductase subunit α, pyruvate ferredoxin oxidoreductase α subunit, and methyl-coenzyme M reductase β subunit, while glucose-6-phosphate isomerase and fructose-1,6-bisphosphatase II played pivotal roles in cellulose degradation within mixed substrates. Combined Solid-state co-anaerobic fermentation was dominated by methane production from the acetyl fragmentation pathway, and that the two synergistically promoted the CO₂ reduction pathway. This study provides a mechanistic study for the treatment of weathered coal and cattle manure, which provides new ideas for solid waste treatment and clean energy.

ABSTRACT. Biochar is considered as an interesting alternative to remediate some environmental issues, especially by storing carbon to mitigate global warming, in addition to the wide range of applications it offers in different sectors, including soil management, air/gas cleaning, water purification, buildings and catalysis.[1] Its potential for these applications depends on its properties (high carbon content, porous and stable structure, high surface area, etc.), which are determined by the raw starting biomass and the pyrolysis conditions (temperature, pyrolytic regime, etc.).[2] Thus, an accurate characterization of biochar composition is essential to provide the desired properties for a given application [3] and contribute to the understanding of pyrolysis chemical mechanisms. Nevertheless, some analytical techniques used to study the elemental composition of biochars present uncertainties (i.e oxygen and inorganic characterization and quantification). For this reason, this study aims to gather and compare the different methods in order to provide more accurate atomic mass balances. Biochars were produced in tubular reactor by slow (10 K/min) and intermediate (1 K/s) pyrolysis at 550°C and 700°C final temperatures from several types of biomasses (oak, douglas, corn cobs, digestate, poultry droppings and cattle manure). Complementary analyses were carried out: elemental analysis (C, H, O, N, S), thermogravimetric analysis (TGA), muffle furnace, inductively coupled plasma (ICP), X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD). For biochars containing low mineral content, the quantification methods of ash have low effect on atomic mass balances determination. Then, direct oxygen quantification appears to be a reliable method as it reaches approximately 100% (between 98 and 102%). Concerning biochars with high mineral content (above 3%wt. db), the atomic mass balances accuracy is function of the method used for inorganics’ quantification. Direct quantification by elemental analysis (C, H, N, S, O) combined with TGA (proximate analysis) shown the best results (between 100 - 106%wt. db), whereas, muffle furnace method for ashes quantification gave overestimated atomic mass balances (up to 120%). Then, more specific methods (XRF or ICP) were combined with elemental analysis (C, H, N, S, O). Both combinations provided accurate atomic mass balances (between 99 - 106%wt. db) with similar results (less than 2% difference).

1. Haghighi Mood, S., Pelaez-Samaniego, M. R. & Garcia-Perez, M. Perspectives of Engineered Biochar for Environmental Applications: A Review. Energy Fuels 36, 7940–7986 (2022). 2. Weber, K. & Quicker, P. Properties of biochar. Fuel 217, 240–261 (2018). 3. Lebrun Thauront, J., Soja, G., Schmidt, H. & Abiven, S. A critical re‐analysis of biochar properties prediction from production parameters and elemental analysis. GCB Bioenergy 16, e13170 (2024).

ABSTRACT. Analytical pyrolysis has become one of the standard characterization techniques for many complex materials, such as natural and synthetic polymers, lignocellulosics, composites, etc. While it works best with non polar materials such as polyolefins or vinyl polymers, polar materials with heteroatoms sometimes undergo more complex degradation reactions and yield products that do not allow straight forward identification of the material. John Challinor was the first to introduce pyrolysis experiments in the presence of tetramethyl ammonium hydroxide (TMAH), a strong organic base that favours hydrolysis reactions over pyrolytic cleavage [1]. Thus, polar materials are broken down mostly to their monomers and are simultaneously transferred into their less polar and more volatile methyl derivatives by TMAH. Since its first use the techniques has been applied to samples such as polyesters, polyethers, resins, varnishes, bio- and geopolymers, carbohydrates, triglycerids, and many more. Alternatives to TMAH have been tested, which allow e.g. the separation of free fatty acids besides esterified fatty acids, milder hydrolysis conditions to suppress unwanted side reactions or use of silicon-based reagents to achieve silylation. This talk will give an overview on what has been done in the field of thermally assisted hydrolysis and methylation (THM) as well as closely related techniques since their introduction in 1989, walk through the mechanisms involved and show the scopes but also limitations of such techniques.

Fig. 1. Fatty acid profiling in anopheles arabiensis using thermally assisted hydrolysis and methylation (THM) [2].

[1] J. Challinor, A pyrolysis derivatisation gas chromatography technique for the structural elucidation of some polymers, J. Anal. Appl. Pyrolysis, 16 (1989), 323-333 [2] R. Hood-Nowotny, B. Schwarzinger, C. Schwarzinger, S. Soliban, O. Madakacherry, M. Aigner, M. Watzka, J. Gilles, An Analysis of Diet Quality, How It Controls Fatty Acid Profiles, Isotope Signatures and Stoichiometry in the Malaria Mosquito Anopheles arabiensis, PLOS one, 7/10 (2012), e45222

ABSTRACT. Converting algal biomass to clean energy via a thermochemical pathway is an emerging technique for tackling environment and energy issues. Traditional kinetic studies on biomass pyrolysis employ a thermogravimetric analyzer (TGA) which heats the biomass sample at a rate of 0 ~ 2 K s−1, so TGA could only replicate the thermal behavior of the biomass sample in a fixed bed reactor. However, biomass samples can be heated at a rate over ~102 K s−1 in industrial reactors, including fluidized beds, spouted beds, or rotary kilns due to the direct contact between biomass samples and the solid heat carriers, thus TGA is incapable to reproduce these thermal behaviors. In view of the limitation of TGA in fast heating cases, this study has developed a fast-heating thermo-balance consisting of wire-mesh and wireless power supply technique to investigate the kinetics of fast pyrolysis. Seaweed is fast-growing and can be considered a promising feedstock for biofuel production. Therefore, this study selected seaweed as representative biomass waste and compared the pyrolysis behaviors under both slow and fast pyrolysis conditions. A key finding was the TGA-derived kinetic parameters were unable to describe the pyrolysis rate under fast pyrolysis conditions with significant overestimation. When compared to slow pyrolysis, fast pyrolysis can increase bio-oil yield by about 3–17%, but the N- and S-containing compounds in the bio-oil increase by about 1.1% and 0.15% respectively at a final temperature of 700ºC. Fast pyrolysis produced about 16–53% more CO2 than slow pyrolysis above a final temperature of 500 ºC. The polarity of compounds in biochar was reduced with increasing temperature and the presence of CaO was only found in biochar at a high temperature of 700 ºC. The specific surface area of biochar was higher under fast heating pyrolysis (5.534–7.469 m2 g−1) than that under slow heating pyrolysis (4.076–6.414 m2 g−1).

ABSTRACT. Biomass pyrolysis produces high-value chemical products and is important for developing energy applications. Nitrogen-doped biochar, which has a porous structure, active nitrogen/oxygen-containing groups, and catalytic sites, can be used directly as a high-performance functional carbon material such as a catalyst, adsorption, and energy storage material. How to prepare porous N-doped biochar is very important for the high-quality utilization of biomass. Chemical activation and nitrogen doping are the main upgrade methods for biochar. This study explored the preparation mechanism for nitrogen-doped biochar materials via one-step “pyrolysis-activation-doping” of biomass. The interaction of biomass pyrolysis, chemical activation, and NH3 modification was explored in depth, and the evolution mechanism of pore structure, nitrogen content, and active functional groups of porous N-doped biochar was discussed in detail. Results showed that there was a significant synergistic effect of KOH and NH3 on the development of pore structure and nitrogen doping. KOH reacted with active functional groups in biomass and removed large amounts of O-containing groups to generate abundant active vacancies. NH3 reacted with biomass and formed lots of NH2* and NH*, which occupied active vacancies quickly, thus enriching large amounts of nitrogen in biochar product (10.4 wt.%). NH3 and KOH also etched biochar fragments to form large quantities of pores, thus obtaining N-doped biochar materials with high specific surface area and developed mesoporous structure (2800 m2/g). Thus, one-step “pyrolysis-activation-doping” of biomass can easily prepare for the porous N-doped biochar with a developed porous structure and high nitrogen content.

ABSTRACT. Thermochemical conversion of lignocellulosic biomass via pyrolysis offers a versatile pathway for producing renewable energy carriers and chemicals. However, the utilization of bio-oil is often hindered by its high oxygen and water content, chemical instability, and complex heterogeneity. While previous studies (1-3) have explored external bio-oil recirculation to enhance biochar yield and quality, the role of internal in-situ vapor recirculation remains poorly understood in continuous pyrolysis systems. This study addresses this gap by systematically investigating how controlled vapor–solid interactions influence product yield distribution and bio-oil quality. The experiments were performed in a laboratory-scale continuous auger reactor with pine bark (500 g/h) at the highest treatment temperatures (HTTs) of 600, 700, and 800C. The reactor’s five independently controlled heating zones and multiple selectable vapor outlet ports allowed the manipulation of temperature profiles and vapor flow trajectories. Three configurations (Figure) were evaluated: a conventional parallel-flow (PF) and two counter-flow (CF). In PF, vapors travel co-currently with the biomass. In CFs, the flow is reversed to pass through cooler upstream zones, promoting in-situ condensation of heavy vapors onto incoming biomass and promoting secondary pyrolysis reactions. In the experiments, bio-oil was recovered in a three-stage condensation system, and non-condensable gas composition was analyzed online (microGC). The mass and carbon balance closures were performed to assess the impact of flow configurations on product yield and properties. To investigate the effect on bio-oil composition and properties, the collected bio-oils were fractioned into water-soluble and water-insoluble (heavy oil) phases by using MgSO4-assisted fractionation. The fractions were characterized by GC–MS/FID to identify and semi-quantify volatile species, such as acids, furans, and phenols. NMR spectroscopy provided deep structural insights: one-dimensional 13C NMR was applied to determine the distribution of carbon functional groups, while two-dimensional 1H–13C HSQC NMR was used to resolve overlapping signals and track changes in molecular motifs, including carbohydrate-derived units and lignin-derived methoxy groups. The results demonstrate that in-situ vapor recirculation offers an in-situ upgrading for bio-oil, enhancing carbon retention and controlled selectivity among biochar, bio-oil, and gas in continuous pyrolysis systems.

(1) Huang, Y.; Kudo, S.; Norinaga, K.; Amaike, M.; Hayashi, J. I. Selective Production of Light Oil by Biomass Pyrolysis with Feedstock-Mediated Recycling of Heavy Oil. In Energy and Fuels; 2012; Vol. 26, pp 256–264. https://doi.org/10.1021/ef2011673. (2) Phounglamcheik, A.; Wretborn, T.; Umeki, K. Increasing Efficiency of Charcoal Production with Bio-Oil Recycling. Energy and Fuels 2018, 32 (9), 9650–9658. https://doi.org/10.1021/acs.energyfuels.8b02333. (3) Cen, K.; Zhuang, X.; Gan, Z.; Zhang, H.; Chen, D. Biomass Pyrolysis Polygeneration with Bio-Oil Recycling: Co-Pyrolysis of Heavy Bio-Oil and Pine Wood Leached with Light Bio-Oil for Product Upgradation. Fuel 2023, 335. https://doi.org/10.1016/j.fuel.2022.127057.

ABSTRACT. Magic Chemisorbers are solid-phase extraction (SPE) devices useful for analyzing trace amounts of volatile compounds in air or aqueous solutions. Their distinctive feature, compared to other solid-phase extraction devices, is the use of a pyrolyzer to desorb the extracted components, to be analysed by gas chromatography/mass spectrometry (GC/MS). Although applications have been reported in the fields of food analysis, materials emissions, and environmental analysis, only few applications have been reported in the field of cultural heritage. This study presents the results of the first air quality monitoring campaign conducted at the Deutsches Museum in 2025. Polar and apolar Magic Chemisorbers were used to investigate air composition in three showcases and in a historical car. Prior to the in situ campaign, laboratory tests were conducted on cellulose nitrate and cellulose acetate objects to evaluate the methodology´s ability of these devices to detect problematic plastic emissions and to gain experience for in situ applications. The results are discussed and compared with those obtained using Radiello passive sampling devices exposed in parallel. The data indicate that Magic Chemisorbers were able to detect several target pollutants of interest both under laboratory conditions and during in situ measurements. In laboratory tests, compounds associated with the degradation of malignant plastics were identified, including camphor and nitrogen oxide for cellulose nitrate, and acetic acid, phthalates, and triphenyl phosphate for cellulose acetate (Fig. 1). During the in situ monitoring in display cases and inside a historic car, the results were more complex to interpret due to the presence of multiple potential emission sources. These were related both to the materials used in the construction of the display cases—often based on wood-derived products—and to the heritage objects themselves, which are frequently made of natural or synthetic organic materials. Aldehydes, phthalates, organic acids, and acetates are typical volatile compounds associated with the degradation of these materials, and were also detected in this study. No clear overall superiority has been established between polar and apolar Chemisorbers, as their performance varied depending on the specific case study; consequently, the combined use of both types is advisable to obtain a more comprehensive qualitative characterization of air composition. Magic Chemisorbers proved to be a useful tool for the qualitative characterization of air composition and represent a promising technique for preventive conservation. They are effective for preliminary screening and selection of case studies for further investigation with more costly techniques, supporting an efficient use of museum resources. Their application appears particularly suitable for laboratories that routinely perform Py-GC/MS analyses and are interested in extending their activities to air quality monitoring.

Fig 1: Chromatograms obtained using Magic Chemisorbers during laboratory tests on a cellulose acetate historical object from the 1940ies. Plastic additives (dimethyl and diethyl phthalate and triphenyl phosphate) were detected by both polar and apolar Chemisorbers, while acetic acid was only detected by the polar one.

ABSTRACT. Synthetic polymers have influenced contemporary artists since the beginning of last century; among these materials, polyurethanes (PU) are widely present in 20th century artworks and design objects, mainly as flexible and rigid foams. Adopted by artists from the late 1960s for their distinctive properties, such as lightness and softness, polyurethane foams exhibit limited durability and can degrade within a few decades after production. The wide variety of possible compositions and formulations for these materials makes the degradation of PU foams a critical conservation issue for 20th century art and design collections, that requires suitable tools to evaluate, monitor, and ultimately mitigate it through appropriate conservation strategies. This is one of the aims of the PRIN2022 interdisciplinary project PERSPECTIVE - PolymEr Research Studies for PreventivE Conservation Through non invasIVe analytical strategiEs (https://perspective.cnr.it) for plastic heritage. Within the framework of the project, this work focuses on the application of thermoanalytical techniques to provide a comprehensive evaluation of PU items, including polymers and additives such as consolidant formulations and UV absorbers tested/used in the conservation of PU artworks [1]. Reference PU samples, unaged and subjected to artificial ageing, were analyzed by means of evolved gas analysis-mass spectrometry (EGA-MS) and double shot pyrolysis-gas chromatography-mass spectrometry (DS-Py-GC-MS) to characterize their thermal degradation behavior, optimize the DS-Py-GC-MS temperatures, and determine the composition of the material. Part of the reference PU samples were treated with two different consolidant dispersions and a light stabilizer. The analysis allowed the characterization not only of the diisocyanate and polyol fractions of the PU, but also of the light stabilizer and the consolidant dispersions tested by the restorers. Differences in the thermal degradation profiles due to ageing and to the different additives used were highlighted by comparing the EGA profiles of the various samples. The different PU samples (unaged, artificially aged, both treated and untreated with consolidant dispersions and light stabilizer) were then subjected to accelerated UV degradation using the online micro UV Irradiator system (UV-1047Xe, Frontier Laboratories) and subsequently analyzed by EGA-MS and DS-Py-GC-MS to evaluate changes in the untreated (Figure) and differently treated PU samples. The use of the light stabilizer proved effective, while the two different consolidant dispersions showed distinct thermal degradation behaviors due to their chemical compositions, and thus different performance in terms of consolidation. The optimized protocol, based on thermoanalytical techniques, was applied to polyurethane artworks from the Triennale Design Museum of Milan and proved effective in monitoring the degradation of PU heritage objects through micro-invasive sampling.

Figure EGA-MS profiles of unaged and artificially aged reference PU samples.

References [1] T. van Oosten, Pur Facts Conservation of Polyurethane Foam in Art and Design. 2011: Amsterdam University Press.

Acknowledgements The Centre for Instrument Sharing of the University of Pisa (CISUP); Grazia De Cesare from the Academy of Fine Arts of L’Aquila (Italy), and Rafaela Trevisan from the Triennale Design Museum of Milan (Italy). Funding was provided by the Italian Ministry of University and Research (MUR), PRIN2022 project “PERSPECTIVE” coordinated by Francesca Rosi (CNR-SCITEC, Perugia).

ABSTRACT. Dancheong is a traditional Korean polychromy technique applied to wooden architecture since at least the 4th century, serving both protective and decorative functions on temple and palace buildings. Despite long-term outdoor exposure, dancheong painting layers were produced using organic binders such as animal glue and starch pastes (wheat or rice). Previous studies have mainly focused on patterns and inorganic pigments, while the identification of organic binders remains a challenge due to their low concentration and extensive degradation. As contemporary artisans have limited experience with traditional natural binders, scientific investigation of these materials is necessary for informed conservation and restoration. This study investigates the original dancheong painting technique through the analytical characterization of organic binders. Based on historical documents and interviews with artisans, mock-up samples were prepared using animal glue, wheat and rice starch pastes, and a commercial acrylic emulsion. Their analytical characteristics were examined using Fourier-transform infrared spectrocopy (FTIR), evolved gas analysis (EGA), pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS), and enzyme–linked immunosorbent assay (ELISA). EGA confirmed the presence of organic binders in paint layers, while Py–GC/MS identified diagnostic markers specific to each binder type: pyrrole-based compounds for animal glue, furan- and glucosan-related compounds for starch pastes, and acrylic monomers (ethyl acrylate, butyl acrylate, and butyl methacrylate) for the synthetic binder. Application of these diagnostic markers to multiple 17th–18th century dancheong samples consistently indicated the use of animal glue in the painting layers and starch paste in the ground layer (gachil), in agreement with historical descriptions. In heavily degraded samples, binder-related signals were detected at trace levels, demonstrating the sensitivity of Py-GC/MS for aged architectural paint layers. Our findings show that Py-GC/MS can be effectively applied to the identification of trace organic binders in architectural surface decorations that have been exposed for over 200–300 years. These results contribute to the accurate restoration of traditional dancheong techniques and expand the application of pyrolysis analysis in cultural heritage science.

* Acknowledgment: This research was supported by the National Research Institute of Cultural Heritage, Korea (NRICH-2605-A83F-1-1).

ABSTRACT. Hydrocarbon pyrolysis is an increasingly attractive route for low-emission hydrogen production, offering the advantage of coupling hydrogen generation with the formation of value-added carbon materials. In this context, a key challenge lies in accurately describing the evolution of the gas-phase composition, particularly under operating conditions relevant to the formation of structured carbon phases. The predictive capability of kinetic models strongly depends on their ability to capture the formation and consumption of key intermediates governing both hydrogen yield and carbon precursor availability. In addition, experimental challenges in fully resolving gas-phase composition and carbon forms (amorphous, surface) [1] further motivate the development of accurate mechanistic kinetic models.

This work presents the validation of an integrated kinetic framework combining detailed gas-phase chemistry with a dedicated model for carbon deposition and growth via non-catalytic Chemical Vapor Deposition (CVD) and carbon nanoparticle formation. The framework consistently links homogeneous pyrolysis chemistry with heterogeneous carbon formation pathways, enabling a unified description of gas-phase reactions and solid carbon growth.

The CRECK gas-phase kinetic mechanism[2,3] is tested both independently and through systematic comparison with established literature mechanisms[4], focusing on key intermediates such as acetylene, benzene, and polycyclic aromatic hydrocarbons, which play a central role as precursors to solid carbon formation. Validation is performed against experimental data obtained in ideal reactor configurations, assessing the effects of temperature, residence time, pressure, and C/H ratio on feedstock conversion, hydrogen yield, and gaseous product distribution. This analysis enables evaluation of the robustness and consistency of the gas-phase description across relevant conditions.

Building upon the validated gas-phase framework, a solid-phase kinetic module is introduced to describe carbon deposition and growth via gas-surface reactions. Theoretical studies[5,6] indicate growth mechanisms analogous to soot and pyrocarbon formation in non-catalytic CVD environments. Reaction classes and rate rules are formulated by analogy with established PAH growth mechanisms[7] and supported by kinetic scaling relationships, ensuring thermodynamic and mechanistic consistency. The modular structure allows progressive inclusion of surface reactions while preserving coherent coupling with the gas-phase chemistry.

The combined validation of gas-phase kinetics and solid deposition modeling demonstrates the capability of the framework to consistently link hydrocarbon pyrolysis chemistry to carbon formation pathways. The results highlight the strong sensitivity of carbon growth behavior to gas-phase precursor chemistry and operating conditions. Overall, this work represents a step toward predictive multiscale kinetic models for methane pyrolysis reactors, supporting experimental interpretation and the development of modeling tools for process optimization in hydrogen and value-added carbon production.

[1] E. Busillo et al., Carbon 248 (2026) 121153. [2] A. Nobili et al., Combust. Flame 269 (2024) 113697. [3] L. P. Maffei et al., Appl. Energy Combust. Sci. 24 (2025) 100385. [4] Z.-M. Wang et al., J. Anal. Appl. Pyrolysis 182 (2024) 106668. [5] C. Giudici et al., React. Chem. Eng. 9 (2024) 2505–2519. [6] F. Serse et al., Carbon Trends 11 (2023) 100263. [7] M. Mehl et al., Nat. Protoc. (2025).

ABSTRACT. Understanding the influence of fragments of coal macromolecular network (metaplast and tar）on char during coal pyrolysis is beneficial for studying the mechanism of coal conversion and realizing the regulation of coal pyrolysis products. The solvent extraction and swelling treatment of rapid pyrolysis char were carried out to reduce the content of metaplast. The metaplast extracted with tetrahydrofuran (THF) solvent contained abundant aromatic compounds with a low degree of polycondensation, and its orientation distribution in char was disordered. After solvent extraction and swelling, the reactivity of the residues was enhanced, making more residues convert into liquid and gas products during the re-pyrolysis. Solvent extraction and swelling only increased the specific surface area of the char from 4 m²/g to 5 m²/g and 7 m²/g, respectively, indicating that metaplast cannot directly influence pyrolysis by occupying pores. In re-pyrolysis, the relative growth rates of 4×4 and larger aromatic sheets in the extraction and swelling residues were decreased from 66.35% (char without solvent treatment) to 52.21% (char after extraction treatment) and 36.4% (char after swelling treatment), respectively. It indicates that metaplast can promote the polycondensation. After solvent treatment, the orientational concentration of aromatic cores in the char increased during re-pyrolysis, whereas that in the untreated char did not. It indicates that the metaplast was more likely to being trapped by the char's skeletal framework through cross-linking reactions or pore adsorption and was further polycondensed with the volatiles to form amorphous aromatic cores within the char matrix. In addition, the rapid-pyrolyzed chars prepared at different temperatures were re-pyrolyzed under atmospheres containing different tar model compounds. For char prepared at 600 ℃, the proportion of ≥3×3 aromatic rings increased from 28% in N₂ atmosphere to 35% and 39% under 1-methylnaphthalene and quinoline atmospheres, respectively, bigger than those in toluene (31%) and o-cresol (29%) atmospheres. Moreover, the proportion of large-sized aromatic cores in the 600 °C rapid-pyrolyzed char was significantly higher than that in the 800 °C rapid-pyrolyzed char under all atmospheres. 1-Methylnaphthalene, with its bicyclic structure serving as the growth unit for polycondensation, exhibits the most pronounced promotion effect due to its side-chain methyl group facilitating radical cross-linking. Quinoline reduces the activation energy of polycondensation through strong adsorption of its nitrogen-containing ring to the char surface, demonstrating the second-strongest effect. Toluene-1 and o-cresol, however, exhibit relatively weak regulatory effects on the degree of macromolecular polymerization in char due to limitations of their monocyclic structures and spatial steric hindrance from their side chains. They condense within pores to form microcrystalline structures with some stacking but insufficient extension. Metaplast and tar exhibit similar reaction characteristics with the char macromolecular framework: the larger aromatic ring structures undergo polycondensation at lattice edges, while smaller aromatic cores condense within the pores.

ABSTRACT. Ketones have garnered considerable interest as promising biofuels or fuel additives due to their high-octane number and knock resistance. Beyond their utility as fuels, ketones are also significant intermediates formed during the combustion of oxygenated fuels (e.g., ethers, alcohols) and large n-alkanes. Therefore, a precise understanding of ketone combustion kinetics governs the optimization of combustion efficiency and the control of pollutant formation (such as aldehydes, CO, soot, etc.). A fundamental understanding of the relationship between molecular-structure and combustion kinetic necessitates advanced ketone-based biofuel design. 2-hexanone and 3-hexanone, with the combination of a carbonyl group and moderate alkyl chain lengths, are promising candidates for balancing energy content and anti-knock performance. However, studies on the combustion chemistry of 2- and 3-hexanone remain scarce. To elucidate the decisive role of oxygen-functional group position in combustion chemistry, an isomer-specific kinetic model was established. It integrates high-level CBS-QB3 quantum calculations with jet-stirred reactor experiments at 1.0 atm and 723-1048 K. As the first isomer-specific kinetic model for C6 ketones, it incorporates pressure-dependent rate constants derived from master equation analysis and rigorously calculated H-abstraction barriers. The pyrolysis products, including C0-C4 hydrocarbons and oxygenated intermediates closely linked to fuel consumption, were identified and quantified using GC-MS and online GC-FID/TCD analyses. Results demonstrate that 3-hexanone exhibits higher pyrolysis reactivity than 2-hexanone, attributable to its symmetric structure featuring two low-BDE α-C-H sites for favorable H-abstraction and distinct unimolecular scission pathways. Among them, 2-hexanone preferentially forms acetone and C3-C4 hydrocarbons, whereas 3-hexanone generates more ethylene and specific ketenes. The identified effect of functional group position provides a broader framework for oxygenated fuels (ketones, alcohols and ethers), supporting a generalized principle that higher molecular symmetry correlates with enhanced pyrolysis reactivity. The fundamental insights gained in this study enhance the understanding of branched ketone combustion chemistry and support their potential application as clean fuels or fuel additives.

ABSTRACT. To explore the decomposition behaviors of C5 cyclic hydrocarbons and extend this understanding to high-energy-density liquid fuels, the pyrolysis of basic C5 rings (cyclopentane, cyclopentene, and cyclopentadiene) and four derived C5-containing high-density fuels was investigated. Experiments were conducted using a flow tube reactor across a wide pressure range (1.0–30.0 atm), supported by high-level theoretical calculations. First, a universal kinetic model for the basic C5 fuels was proposed, revealing that unsaturation significantly impacts reactivity and pathway selection. Saturated rings favor ring-opening to generate small hydrocarbons, whereas increased unsaturation promotes the formation of monocyclic and bicyclic aromatic hydrocarbons (MAHs and BAHs) via cyclopentadienyl resonance-stabilized radicals (RSR). Building on this foundation, the study examined four typical high-density fuels: tetracycloheptane (QC), ethylnorbornane (EthNB), tetrahydrodicyclopentadiene (exo-TCD), and tetrahydrotricyclopentadiene (THTCPD). Adopting a "hierarchical structure" strategy with the C5 and aromatics mechanism as the core, comprehensive kinetic models were developed and validated. The results indicate that specific carbon-ring structures dictate the initial fuel consumption pathways; for instance, the norbornane structure predominantly undergoes open-ring isomerization. Regarding aromatics formation, MAHs are primarily generated through the multi-step dissociation of fuel radicals, whereas PAH formation is dominated by the bi-molecular addition reactions of CPDyl and CPD. This PAH growth mechanism is largely independent of specific fuel chemistry, with the exception of the highly strained QC, which exhibits distinct pathways involving acetylene and toluene due to its unique cage structure.

ABSTRACT. Posidonia Oceanica is an abundant plant of the Mediterranean area, and its debris wastes naturally accumulate up to the coast. Their management should be carefully evaluated, expecially considering that unpleasant inconveniences during the bathing season may occur. In the perspective of identifying new exploitation opportunities, in this work, fibrous spheres of Posidonia Oceanica have been thermally treated by slow-pyrolysis, comparing the traditional heating with the microwave (MW)-assisted one. For this investigation, similar processing conditions (e.g. heating rate, set-point temperature and residence time) were proposed, thus characterizing the corresponding streams. The use a nitrogen flow in the conventional heating approach reduced the residence times of the evolved vapours in the hot zones of the reactor, favoring the formation of typical probe intermediates, such as levoglucosan, originating from the thermal degradation of the holocellulose. The degradation of biomass components was more advanced in the MW system, due to the absence of nitrogen flow. Some modifications of the MW apparatus were considered, in particular the addition of a dephlegmator unit, which further promoted cracking and aromatization reactions. Remarkably, when the Posidonia Oceanica-derived biochar was employed in blend with the fresh biomass, the efficiency of the MW heating greatly improved, exploiting the biochar as an efficient MW absorber, thus enabling the gasification regime and, consequently, the selective formation of CO and H2. Life Cycle Assessment (LCA) evaluations confirmed the similar environmental impact of both technologies on the laboratory scale, where MW-assisted pyrolysis still presents some drawbacks for the development on a larger scale, mainly related to the energy supply/management. MW technology still has significant potential of improvement on these aspects, and it is reasonable that it will be more competitive respect to the conventional heating technology, already in the next future.

Acknowledgements The authors thank the project NEST “Network 4 Energy Sustainable Transition” (code PE0000021) funded by the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.3 – Call for tender No. 1561 of 11.10.2022 of MUR, funded by the European Union – NextGenerationEU.

ABSTRACT. Hydrothermal carbonization (HTC) of fish-based biomass was investigated to elucidate the effects of reaction temperature (180, 220, and 240 °C) and residence time (2 and 4 h) on product yield, elemental composition, and carbon partitioning, with emphasis on biocrude fractions and downstream thermal behavior. At 180 °C, HTC was dominated by hydrolysis and condensation reactions, resulting in hydrochar formation and extensive solubilization of organic carbon into the aqueous phase, without formation of a distinct biocrude phase. Increasing the temperature to 220 and 240 °C promoted partial liquefaction and the appearance of a separable biocrude fraction, while the overall hydrochar yield decreased with increasing temperature. Residence time showed only a minor influence on hydrochar yield, indicating that carbon redistribution approaches a quasi-equilibrium within the shorter residence time under the conditions studied. Elemental analysis revealed strong differentiation between product streams: hydrochars exhibited low carbon content (~19 wt%) with nitrogen retention, whereas the biocrude fractions were highly enriched in carbon (~71–74 wt%) and hydrogen, reflecting preferential partitioning of reduced, hydrophobic compounds at higher HTC severity. Thermal conversion of HTC-derived biocrude was examined using a tandem micro-reactor (TMR) coupled with GC–MS/FID. Pyrolysis at 300 °C predominantly released oxygenated and nitrogen-containing volatiles, while pyrolysis at 500 °C resulted in extensive cracking and secondary reactions, producing lighter hydrocarbons and aromatic species. The introduction of zeolite catalysts in the secondary reactor qualitatively shifted the vapor composition toward increased aromatic hydrocarbons and reduced oxygenated compounds, highlighting the role of catalytic vapor-phase upgrading. These results demonstrate that HTC temperature governs carbon partitioning and bio-oil formation, while residence time plays a secondary role, and that coupling HTC with catalytic pyrolysis provides a versatile pathway for valorizing fish-derived biomass into upgraded hydrocarbons, aromatic chemicals, and functional carbon materials.

ABSTRACT. Fluidized-bed (FB) pyrolysis represents a promising route for biocarbon production due to improved heat and mass transfer, uniform temperature distribution, and continuous solids handling, compared with conventional pyrolysis reactor configurations (e.g., fixed-bed, auger, and rotary kiln systems). At the same time, FB operation introduces a distinctive mechanical environment where particle–bed collisions promote attrition. Previous experiments with Ca–K-rich pine bark conducted under a weakly oxidizing flue-gas-like atmosphere (86.2 vol% N2, 10 vol% CO2, 3.8 vol% O2), showed that the depletion of ash-forming species such as K, P and Ca could not be explained solely by volatilization pathways. It was therefore proposed that additional removal via a coupled mechanism, whereby ash-forming phases become enriched at the particle surface during conversion (through migration and/or exposure) and are subsequently removed by attrition-driven loss of surface material (Arango-Durango et al., 2025). The present work examines this hypothesis by using particle-scale imaging to determine whether, when, and to what extent dense mineral phases migrate towards or are exposed to the external surface under inert and weakly oxidizing atmospheres. X-ray microtomography (XMT) was applied to individual pine bark particles before and after pyrolysis to quantify whether dense inclusions become preferentially located closer to the external surface. The primary XMT descriptor employed is the distance-to-surface distribution of high-density regions (before vs after conversion). A representative three-dimensional XMT rendering of a pine bark particle is provided in Figure 1 to illustrate the density-contrast features analyzed.

Figure 1. High-resolution X-ray microtomography images showing the overall pine bark particle structure and the segmentation of calcium oxalate crystals (high-density phase).

Complementarily, in situ experiments using a micro-electro-mechanical system (MEMS) chip-based heated microreactor inside a scanning electron microscope (SEM) will be used to track surface evolution during heating from ambient temperature to 1000 °C. The main microscopy output will be the surface area fraction of mineral-rich regions, obtained by image segmentation, as a function of temperature and time. SEM coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) will be performed at the beginning and end of the in-situ sequence to assess changes in surface elemental signatures, focusing on major pine bark ash constituents (notably K, P, and Ca). The influence of atmosphere will be evaluated by comparing inert N2 against the weakly oxidizing N2/CO2/O2 mixture, testing whether selective surface oxidation modifies the formation, exposure, and evolution of mineral-rich surface features. By linking dense phase spatial distribution derived from XMT with time-resolved surface evolution observed by in situ microscopy under well-defined atmospheres, this study aims to clarify the mechanism governing ash-element behavior during biomass pyrolysis and to provide a basis for the development of mitigation strategies for applications sensitive to ash chemistry.

References Arango-Durango, E., Pachchigar, S., Öhman, M., & Umeki, K. (2025). Exploring fluidized bed technology for biocarbon production with mitigation of ash-forming elements. Fuel. https://doi.org/10.1016/j.fuel.2025.134949

ABSTRACT. Among various industrial sectors, leather is one of the significant contributors to export revenues and ranks among the top 10 foreign exchange earners for many developing countries, particularly India. Large quantum of leather solid wastes is produced during leather manufacturing, i.e. ~ 50-60 wt.% of process solid wastes are generated while processing 1 ton of raw hides/skins to finished leather, posing significant environmental challenge. In this study, various leather solid wastes (LSW) generated during different stages of leather processing were collected, and detailed characterization was performed to understand their elemental and biochemical composition, thermal decomposition behaviour, and the presence of various functional groups. Thermogravimetry hyphenated with infrared spectroscopy (TG-IR) analysis was performed at 10 oC/min upto 900˚C, and analytical pyrolysis coupled with gas chromatograph/mass spectrometry (Py-GC/MS) was performed in thermal desorption (TD) (100-300oC at 10 oC/min) and fast pyrolysis (600 oC) modes to evaluate the evolution key functional groups in the vapor phase at different temperatures, and the specific organics during devolatilization of the samples. Squalene was consistently detected in the thermal desorption profiles of all the leather samples below 300 ˚C, indicating its prevalent presence in the thermal decomposition products. In addition, nitrogen-containing compounds like pyrrole derivatives constituted 10-30% in both TD and pyrolysis. C10-C30 hydrocarbons were the major pyrolysates from the samples. More interesting results on product distribution at different temperatures and from different LSW will be discussed during the presentation. The study demonstrates that leather solid wastes could be a potential feedstock for recovering valuable hydrocarbons that can be utilized for fuel/chemicals production, upon subsequent upgradation, targeting commercial use.

ABSTRACT. Lignin is currently considered as one of the main sustainable alternatives to the petrochemical raw materials. It has been established as a very promising carbon-based raw material, given that it is an abundant, non-food biomass obtained from very diverse sources, including residual. However, its industrial use remains limited due to the complexity of its molecular structure preventing the final materials from achieving desirable properties and functionalities. Therefore, the chemical modification of lignin is being used as a key strategy to increase its reactivity and overcome these challenges. The present work aims to carry out the characterization of lignin modified through different chemical reactions introducing specific functional groups. The objective is to paving the way for accurate and efficient characterization that can be extrapolated to further lignin derivatives and types, such as nanolignins. The chemical modification of lignin depends primarily on the accessibility and activation of its core functional groups. But, the inherent complexity of lignin’s macromolecular structure significantly controls the success of these reactions. Steric hindrance often impedes reagents from reaching internal reactive sites, leading to incomplete transformations. Also, the high stability of certain inter-unit linkages can induce resistance in modification attempts. For that reason, the characterization techniques are fundamental for evaluating whether a given reaction has worked instead of following standardized protocols to guarantee success. While various analytical methods are used to confirm the addition of functional groups and improvements in physical properties, Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) remains a relatively underexplored but valuable tool for tracking these structural changes. In the present it is presented the results of four different types of lignin samples (unmodified, demethylated, glyoxylated and epoxidated lignin) analyzed by PY-GC-MS. The results indicated that guaiacyl-type units and other oxygenated aromatic compounds dominated the pyrolysis products, consistent with the characteristic pyrolysis fingerprint of softwood lignin. The epoxidized lignin showed the lowest number of pyrolysis derivative products. Nevertheless, the most distinct variations between samples were observed in the relative proportions of side-chain and demethylated-linked pyrolysis products. For instance, the glyoxylated and epoxidized lignins presented the highest total side-chain contents. Specifically, epoxidized lignin was associated with higher proportion of guaiacol, whereas glyoxylated lignin was primarily associated with a higher yield of 4-methylguaiacol. This distinction is attributed to the high selectivity of epoxidation for side-chain hydroxyl groups. In contrast, while glyoxylation primarily targets aromatic rings, it is also prone to secondary reactions along the aliphatic side chains. In contrast, demethylated lignin was characterized by a significantly lower proportion of side-chain products. Instead, it yielded a higher proportion of catechol that was not detected for epoxidized and glyoxylated lignin samples. In fact, this may suggest the fundamental structural differences introduced by the demethylation process. Finally, the findings of the present study demonstrate the potential of analytical pyrolysis as significant for assessing the chemical modifications in lignin. Further investigation will be undertaken to develop innovative methodological approaches aiming to supplement existing tools, to provide deeper understanding of lignin modification processes and to facilitate its introduction as sustainable material into bio-based applications.

ABSTRACT. Pyrolysis coupled with Gas Chromatography-Mass Spectrometry (Py-GC/MS) is an important technique for the rapid chemical profiling of complex organic macromolecules, particularly within lignocellulosic biopolymers. Despite its utility, the widespread adoption of Py-GC/MS is hindered by a significant data-processing bottleneck; current workflows are typically labor-intensive, demand specialized expertise, and struggle with the effective deconvolution of complex, overlapping pyrograms. This project introduces a high-throughput, user-friendly, and open-source software solution designed to automate and accelerate Py-GC/MS data processing. By integrating efficient peak deconvolution, robust compound annotation, and user-defined classification for carbohydrates and lignin (including S/G/H unit ratios), the software makes sophisticated chemical screening accessible to a broader range of researchers. The software architecture is optimized for high-performance screening, utilizing multithreading and streamlined code to process large-scale datasets efficiently. The workflow begins with critical preprocessing steps, including noise reduction, baseline correction, and sample alignment. Data analysis is driven by automatic peak detection and chromatogram windowing, followed by peak deconvolution with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). The software offers a choice of distinct initial estimation strategies: Principal Component Analysis (PCA), Singular Value Decomposition (SVD), or Vertex Component Analysis (VCA). Peak quality is further validated through a signal-to-noise ratio (SNR) filtration algorithm and automated unimodal peak area integration. Compound annotation is achieved using a refined, class-categorized specific library. To resolve the common challenge of composite spectra, the software applies directional weight filtering and comprehensive mass spectrum comparisons to enhance identification accuracy. This tool transforms a time-consuming process into a rapid, automated screening tool. Equipped with an intuitive Graphical User Interface (GUI), the software enables the characterization of large sample sets in a much shorter time than traditional methods, providing valuable insights into biopolymer composition.

ABSTRACT. Use of biomass as the feedstock for pyrolysis is aimed at promoting a bioeconomy, where value-added products are obtained from renewable resources, instead of fossil ones. The scientific objectives of our work are related to the thermochemical destruction of carbohydrates and the equilibrium between monosaccharide derivatives and their isomers as pyrolysis products under various pre-treatment conditions, as well as the extraction of the resulting products. We aim to elucidate the mechanisms of the formation of various anhydrosugars as a potential source of green chemicals.

Levoglucosan (LG) or 1,6-anhydro-ꞵ-D-glucopyranose is the main product of cellulose depolymerisation and dehydration during pyrolysis. LG has a unique chiral structure, and it can find applications in various chemical and pharmaceutical synthesis. We propose to expand the array of complementary anhydrosugar products in lignocellulose pyrolysis with a biorefinery approach to increase added value to the pyrolysis process. The main anhydrosugar-type by-products of LG in pyrolysis include 1,6-anhydro-ꞵ-D-glucofuranose (AGF), 1,4:3,6-dianhydro-⍺-D-glucopyranose (DAG), and levoglucosenone (LGO). The yields of these anhydrosugars are influenced by the carbohydrate feedstock, pre-treatment, use of catalysts, and the pyrolysis temperature.

Commercially available standard carbohydrates, as well as lignocellulosic materials were used in the Py-GC/MS experiments with a Frontier Lab Micro Double-shot Pyrolyser Py-2020iD directly coupled with Shimadzu GC/MS—QP 2010 instrument (capillary column RTX-1701 (Restec, USA), 60 m × 0.25 mm × 0.25 µm film).

The screening of the pyrolysis products obtained from glucose, fructose, cellobiose, cellobiosan, levoglucosan, cellulose, starch, and birch wood at 500 ℃ showed the influence of the carbohydrate structure on the formation of LG, AGF, DAG, and also furan derivatives as pyrolysis by-products. Furthermore, the pyrolysis experiments were done with the carbohydrates treated with sulfuric acid in 0.2-4 % concentration range (sulfuric acid m / feedstock m) to evaluate the catalytic effect of acids. In the absence of acid, LG as a feedstock showed thermochemical stability, while the yield of LG from the pyranoses increased in the following order: glucose < cellobiose < cellulose. Addition of acid significantly increased the yield of LG in case of glucose, but not significantly in case of its oligomer and polymer - cellobiose and cellulose, respectively. Moderate addition of sulfuric acid promoted the formation of AGF, but maximum acidity was in favour of the formation of DAG, while the yields of LG and AGF significantly dropped. At 4% sulfuric acid addition, the main pyrolysis products of all carbohydrates were furfural and levulinic acid. Two types of birch lignocellulose (with sulfuric acid and phosphoric acid pre-treatment) were tested at 350 ℃ and 500 ℃, and the ratio of carbohydrate pyrolysis products was influenced both by the temperature and the pretreatment. Sulfuric acid was more favourable for the formation of LG and AGF, but phosphoric acid pre-treatment promoted the formation of LGO and DAG. Optimising the pre-treatment and pyrolysis conditions could enable the production of several valuable green chemicals in the same process.

Acknowledgements to ERDF PostDoc Latvia project No. 1.1.1.9/LZP/1/24/005.

ABSTRACT. Formic acid (HOCHO) is a fundamental oxygenated fuel and a promising liquid organic hydrogen carrier, yet accurate predictive modeling of its gas-phase kinetics remains a significant challenge. Despite its structural simplicity, the pressure-dependent competition between its dehydration (HOCHO→CO+H2​O) and decarboxylation (HOCHO→CO2​+H2​) channels are frequently misrepresented in kinetic models. This lecture identifies specific gaps in current modeling approaches and presents a robust resolution through a two-stage investigation.

We first evaluate the baseline capabilities of automated kinetic generation. We demonstrate that a "Vanilla" model generated by the Reaction Mechanism Generator (RMG) successfully captures oxidation speciation and laminar flame speeds without manual tuning, in contrast to recent claims in literature. We isolate a critical breakdown under pyrolysis conditions, traced to an inaccurate pressure-dependent branching ratio on the CH2​O2​ potential energy surface.

To resolve this bottleneck, we recomputed the relevant potential energy surfaces using CCSD(T)-F12 theory. Finding that rigorous theory alone still underestimates low-temperature decomposition rates compared to historical data, we developed a hybrid model that integrates the theoretical network with independent targeted experimental rate coefficient constraints. The resulting mechanism successfully reproduces challenging non-monotonic speciation profiles observed in pyrolysis while retaining high accuracy in oxidation, establishing a physically consistent framework for formic acid kinetics.

Figure caption: A comparison of the present work model (solid lines) and the non-refined model (dadhed lines) with JSR experimental data (symbols) for key species under pyrolysis conditions at 1 atm, with a 2 s residence time.

ABSTRACT. Pyrolysis, as a thermochemical process, decomposes solid waste in the absence of oxygen, thus helping to limit its environmental impact. This process converts the material into valuable products, such as syngas, bio-oil, and biochar. However, the wide chemical and structural diversity of these residues results in varied thermal and kinetic behaviors, necessitating a unified methodological approach for their study and valorization. This study presents a comparative analysis of the pyrolysis of three major waste categories: biomass (argan residues and beech wood), biopolymers (cellulose, hemicellulose and lignine), and synthetic polymers (polystyrene, low-density polyethylene, high-density polyethylene, and polypropylene). Thermogravimetric analysis (TGA/DTG) is used to characterize thermal decomposition under different heating rates. The experimental data are then processed using the kinetic method based on nonlinear least squares minimization (NLSM), allowing for the estimation of the activation energy and the pre-exponential factor for each type of material. The NLSM method relies on the numerical integration of the kinetic equations describing thermal decomposition, followed by an iterative optimization process to automatically adjust the kinetic parameters, including the activation energy and the pre-exponential factor. The goal of this optimization is to minimize the discrepancy between experimental TGA/DTG curves and those calculated by the model, thus ensuring a faithful representation of the actual thermal behavior of the materials. This approach eliminates the need for subjective manual adjustment and provides robust identification of kinetic parameters from experimental data. The use of a unique kinetic method, based on optimization, ensures a consistent and reliable comparison of the thermal and kinetic behavior of the different materials studied. The results highlight significant differences between biomass, biopolymers, and synthetic polymers, emphasizing the influence of macromolecular structure, compositional heterogeneity, and physicochemical interactions on thermal degradation mechanisms. This approach allows for the comparison of the thermal and kinetic behavior of different solid materials, providing a robust methodological framework for studying their energy or chemical valorization.

Fig. 1. DTG curves fitted with NLSM method for beechwood for 15 °C.min-1

ABSTRACT. Carbon materials are important for our everyday life, as they are essential for a range of products from electrical devices to fiber-reinforced plastics. Currently used carbon materials are almost solely produced from non-renewable precursors, and there is a growing need for sustainable alternatives. One such alternative is cellulose, which is both renewable and abundantly available. Unfortunately, cellulose-based carbon materials remain notably inferior to fossil-based ones, largely because carbon structure formation in cellulose pyrolysis is not adequately understood.

In our ongoing work, we study the chemical and structural pathways of cellulose carbonization using atomistic simulations based on the ReaxFF reactive force field [1]. We both evaluate the capability of the method to reproduce known reactions and products of cellulose pyrolysis and predict chemical changes that occur at different stages of its carbonization. Our modelling work is linked to an experimental campaign to understand the transformation of cellulose into an intermediate thermostable condensed phase (TSCP) and ultimately carbon [2, 3].

Our first modelling studies focused on the mechanism and kinetics of cellulose chain scission at high temperatures and heating rates, which are accessible using (unbiased) molecular dynamics (MD) simulations [4, 5]. We found that direct MD simulations could not reproduce the formation of the TSCP, which is the initial carbonization intermediate and has polyfuranic nature [3]. We could, however, access the early reactions that precede TSCP formation, particularly the crosslinking of cellulose chains with levoglucosan (LGA) end groups [2]. Our findings support the view that LGA end groups participate in the char forming pathway.

Starting from a glucose-derived humin as a model for the TSCP, based on NMR evidence [3, 6], we have now carried out simulations of the further stages of carbonization at higher temperatures, including the deoxygenation, dehydrogenation and gradual graphitization of the polyfuranic intermediate (Fig. 1). We study the process at an elevated pressure, a crucial modelling feature to observe carbon production and to prevent excessive fragmentation and vaporization. Another key feature is the periodic removal of volatiles, enabling us to predict the evolution of elemental ratios and the residual carbon mass. Comparison with experimental thermogravimetric and elemental analysis shows that the simulations capture adequately the removal of oxygen and the carbon yield, but likely underestimate the removal rate of hydrogen. We describe the underlying chemical transformations with focus on competing fragmentation and polymerization events, and the formation of carbon rings and their fused polycyclic forms. We backtrack the formation of six-membered carbon rings, showing which initial structures are most likely to contribute to the carbon residue.

Figure 1. From the humin-like structure of the TSCP (left) [6] to molecular dynamics simulations with elevated pressure and volatile removal (middle, right) that predict chemical transformations underlying cellulose carbonisation

[1] van Duin, J. Phys. Chem. A 105 (2001) 9396–9409 [2] Fliri, J. Anal. Appl. Pyrol. 175 (2023) 106153 [3] Fliri, J. Anal. Appl. Pyrol. 181 (2024) 106591 [4] Paajanen, Cellulose, 24(7) (2017) 2713–2725 [5] Paajanen, Cellulose 28(14) (2021) 8987–9005 [6] van Zandvoort, Green. Chem. 17 (2015) 4383–4392

ABSTRACT. High energetic 2,4,5,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) has limited applications due to its low safety, which can be improved by synthesis of CL-20 cocrystals by cocrystallization strategy. Understanding the reaction mechanisms of thermal decomposition of CL-20 cocrystals and the interactions between components are fundamental for modulating material structure and properties properly by co-crystallization method. However, the thermal decomposition mechanisms of CL-20 cocrystals remain unclear due to the complexity of multi-component systems, rapid dynamic reactions under extreme conditions, and limitations of traditional experimental techniques (e.g., TG, DSC, and chromatography) that only provide several final products, weight loss, and apparent kinetic data. The reactive molecular dynamics using ReaxFF force field (ReaxFF MD) has been found useful to improve the understanding of microscopic chemical behaviors of multi-component energetic materials.

Aimed at unraveling reaction mechanisms of CL-20 cocrystals thermolysis, thermal decomposition of CL-20 cocrystals is systematically investigated using ReaxFF MD simulations with varied heating history. A novel three-stage classification strategy was proposed based on the double peaks of NO2 evolution obtained by ReaxFF MD simulations of adiabatic thermolysis of CL-20 cocrystals, which facilitates to depict the similarities and differences of chemical behaviors and product distribution in thermolysis of varied CL-20 cocrystals. The similarities of chemical behaviors and product distribution in thermolysis of CL-20 cocrystals to that of pure CL-20 under are rooted in the CL-20 chemistry dominating over the whole process from the very initial response to thermal stimuli and primary decomposition to the secondary reactions. The chemical interactions between different components contribute significantly to the kinetic property differences among varied CL-20-involved reactive systems in energy-releasing process, decomposition of CL-20 molecules and stable product generation.

The strategy of ReaxFF MD coupled with the three-stage framework provides an efficient approach of revealing the thermolysis mechanism of CL-20 cocrystals, which may be useful for evaluating the reaction properties of varied CL-20-based multi-component energetic systems.