Gaseous Pyrolysis Products Research Articles

New insights into typical biodegradable plastics in rapid pyrolysis: Kinetics, product evolution and transformation mechanism

Biodegradable plastics (BP) have undergone rapid development in the field of replacing traditional packaging plastics. However, their recycling and disposal systems are unclear, and the standards are different, causing new environmental pollution. The rapid and appropriate disposal of BP has become a worthy direction of exploration. Here, rapid pyrolysis technology was used to explore the recycling of BP, and the product evolution and transformation mechanism of typical BP (BP1∼BP4) were analyzed. The results show that the main reaction stages of BP pyrolysis are concentrated at approximately 260∼450 °C. Most of the heat treatment stages of BP conform to the random nucleation and nuclear growth model An (n = 1.5, 2, 2.5. 3). The gaseous products of BP pyrolysis were mainly 1, 3-butadiene. The top four pyrolysis components are the same for the liquid products of BP1, BP2, and BP4, which are mainly benzoic acid (42.54%–44.67%). However, the proportion of polycyclic aromatic substances in the products of the BP3 pyrolysis solution was as high as 63.85%. For the transformation mechanism, BP containing polylactic acid (PLA) and polybutylene terephthalate-adipate (PBAT) is mainly composed of C–O bond fractures at the ester group and intramolecular hydrogen transfer to form a carboxyl group and CC. This study of BP pyrolysis provides an important scientific basis and theoretical reference for its rational and rapid treatment and product recovery and reuse.

Study on common amino acid pyrolysis products and analysis of pyrolysis products from interaction with aspartic acid

Nitrogen in nitrogen-rich biomass can be converted into high-value nitrogen-containing chemicals such as pyrroles, pyridines and indoles by pyrolysis. Understanding the nitrogen transport mechanism and reaction pathways is important for the utilization of nitrogen-rich biomass. In this study, the pyrolytic reaction pathways of 16 amino acids and interaction between others with aspartic acid were analyzed by pyrolysis in a closed U-tube reactor followed by gas chromatography/mass spectrometry (GC/MS) measurements. It was found that amino acids with lighter molecular tended to produce more gases during the pyrolysis, while amino acids with heavier molecular tended to produce more liquids and solids. The gaseous products of amino acid pyrolysis mainly consisted of CO2 and some CO, of which the content of CO2 reached 86.21% of glycine and 70.97% of aspartic acid, respectively. Liquid oils contain a large number of nitrogen-containing heterocyclic compounds, which are mainly produced by four types of reactions: cyclisation, R group removal, polymerization, and fragmentation reforming. And it was found that aspartic acid was able to promote the changes of the three phases of pyrolysis products and the formation of characteristic products.

Study on pyrolysis process and mechanism of organic coating of waste polyesterimide enameled wire based on density functional theory

The pyrolysis treatment of waste polyesterimide enameled wire offers significant advantages such as continuous processing, non-hazardous nature, and high resource recovery rate. However, research on its pyrolysis process and mechanism remains insufficiently explored. In this study, techniques including thermogravimetry (TG), Fourier transform infrared spectroscopy(FT-IR), pyrolysis–gas chromatography-mass spectrometry(Py-GC/MS) were employed to investigate pyrolysis temperature, weight loss rate, pyrolysis and kinetic parameters, composition and distribution of pyrolysis products, and changes in functional groups under different temperatures and heating rates. The pyrolysis of polyesterimide enameled wire can be divided into three stages: volatilization of specific components (314.8 °C,1.6 %), rapid decomposition of polyesterimide (435.2 °C, 44.7 %), and generation of small organic molecules with the fixation of pyrolytic carbon (750 °C, 9.0 %). The main components of the pyrolysis gas products include aromatic compounds, ethers, aromatics, ketones, and carbon dioxide. At 400 °C, a substantial amount of pyrolysis gas products and free radicals are produced, with an increase in aromatic hydrocarbons. The carbon distribution in the pyrolysis products mainly focuses on C6-C10 and C11-C15, and many organic compounds such as benzoic acid, phenol, and aniline are generated. Based on density functional theory, the bond dissociation energies in the polyesterimide were calculated. This clarified the possible thermal decomposition pathways of the polyesterimide and provided the energy barrier values, elucidating the generation mechanism of pyrolysis products during thermal decomposition. The copper atom in specific location reduces the negative ESP of O and increases the positive ESP of H in EPI, which makes H more likely to attach to O. The presence of Cu increases the ESP range and promote the pyrolysis process. This study provides a theoretical basis for the high-value recycling of waste polyesterimide enamelled wire.

Facile preparation of heptazine-covered Fe2O3 and its synergistic effect on the enhanced flame retardance of silicone rubber composite

The flammability of silicone rubber (SR) significantly limits its broad use in areas that require high flame retardancy. In this study, heptazine-covered Fe2O3, which exhibits effective flame retardancy, was prepared using simple ball milling and heat treatment, which are advantageous for large-scale production. The prepared filler was incorporated into SR. The addition of 7.02 wt% FM filler increased the thermal degradation onset temperature at 5 % weight loss from 492.5 °C for neat SR to 502.7 °C (FM 1:1 composite). Moreover, the peak heat release rate and peak smoke production rate of the FM 1:1 composite significantly decreased by 43.15 % and 68.42 %, respectively, indicating a significant enhancement in the fire safety and smoke suppression of the FM composites. The chemical, morphological, and electronic structures of the FM fillers, pyrolysis gas production, and char residue were thoroughly investigated to reveal the possible flame-retarding mechanisms of the SR composites.

Pyrolysis characteristics and hydrogen production mechanism of biomass impregnated with transition metals

The application of metal impregnation pretreatment to improve the quality of biomass pyrolysis gas production is considered as a promising upgrading technology. Transition metals have been well developed for the unique structural characteristics. After impregnation pretreatment, the product distribution of biomass pyrolysis was changed, and the transfer path of H atoms and the formation mechanism of H2 can be revealed through analysis. The effects of impregnation pretreatment with three different transition metals (iron, cobalt, and nickel) on the pyrolysis characteristics of corn straw were evaluated in this work. Three transition metal solutions with concentrations of 0.5 M, 1 M, and 2 M were used to explore the influence of impregnation concentration on the yield and composition of the pyrolysis products. The results showed that iron promoted the formation of liquid products, whose proportion increased by 37.29% upon increasing the impregnation solution concentration. The addition of cobalt and nickel led to more pyrolysis gas generation. When the impregnation solution concentration was greater than 0.5 M, the gas production rate exceeded 45 wt%. Nickel simultaneously promoted the generation of H2 and CH4 in pyrolysis gas, whose yields were increased by 63% and 20% respectively compared with raw materials. Py-GC/MS analysis showed that Co-CS had strong decarboxylation characteristics during pyrolysis. Metal impregnation decreased the content of aromatic compounds in tar, which increased the stretching vibrations of C-H bonds in char. Ring-opening rearrangements of polycyclic aromatic hydrocarbons were promoted, which formed more -H. Nickel catalyzed the removal of CH3 and H groups and the rearrangement of C-O in volatile products, which formed more H2 and CH4. These findings provide an avenue to optimize the metal impregnation conditions to produce hydrogen via biomass pyrolysis.

Energy potential of plant and animal biomass using in relation to its thermal processing

Relevance. The need for effective utilization of biomass waste generated in significant quantities. Pyrolysis, accompanied by exothermic reactions, is a promising way of biomass processing. Aim. Assessment of the possibility of covering the thermal costs of plant and animal biomass pyrolysis due to heat release during decomposition. Methods. Proximate and ultimate analysis of biomass are determined according to certified methods. Thermal analysis of the studied raw materials was carried out on a Netzsch STA 449 F5 Jupiter synchronous thermal analyzer with an integrated gas analyzer QMS 403 Aeolos; quantitative yield of pyrolysis products was determined according to GOST 3168-93, gas composition was established using the gas analyzer TEST-1 (БОНЭР, Russia). Results and conclusions. According to the results of thermal analysis, it was found that pyrolysis of plant (pine nut shells) and animal (cattle manure) biomass is accompanied by exothermic reactions associated with the organic part decomposition in the temperature range 240–700°C. The value of heat release of exothermic reactions during pine nut shell destruction is 1.39 MJ/kg, a similar value during manure decomposition is 0.31 MJ/kg. This amount of heat allows you to fully cover the thermal costs of pine nut shell pyrolytic processing, the share of covering the thermal costs of manure pyrolysis is ∼30%. An additional source of heat is pyrolysis gaseous products with energy potential equal to 3.28 and 1.58 MJ of thermal energy per 1 kg of processed pine nut shells and manure, respectively.

Eco-friendly, efficient and durable flame retardant lyocell fabrics prepared via a feasible grafting of taurine

Inspired by alkaline oxidative degradation of cellulose, a novel eco-friendly scenario for preparation of flame retardant lyocell fabrics was developed by the chemical grafting of biomass taurine. FTIR and XPS results verified the establishment of a covalent bond between taurine and lyocell fabric. Thermogravimetric analysis and vertical combustion test proved the improved char-forming ability and flame resistance of the grafted fabric. The THR and pHRR of the finished fabric were successfully reduced by 67.3 % and 89.9 % respectively after modification. In addition, after 50 wash cycles, the LOI value of the grafted fabric was maintained at 29.5 %. The gas-phase and condensed-phase flame retardant mechanisms were proposed from the analyses of pyrolysis gaseous products and char residue of the modified fabrics. The modification process is simple to operate and provides a feasible green flame retardant strategy for flammable lyocell fabrics.

Thermal decomposition and combustion of interior design materials

Research findings on the patterns of thermal decomposition and combustion are reported for widely used interior design materials. The experiments were conducted using a hardware and software system including a thermogravimetric analyzer (to record the characteristics of thermal decomposition), a gas analyzer (with H2, CH4, H2S, SO2, CO and CO2 sensors) and a high-speed camera (to record the characteristics of ignition and combustion). The temperature of the oxidizing medium ranged from 500 to 900°C to investigate the conditions of thermal decomposition initiation and sustained combustion. It was established that the highest concentrations of toxic emissions were typical of the combustion of polypropylene at a maximum temperature of the oxidizing medium (900°C). Wood showed the shortest ignition delay time and the longest duration of combustion. The experimental data were used for a physical problem statement and mathematical model of heat and mass transfer to explore the thermal decomposition and combustion of interior design materials in different rooms. A comparison of the experimental findings with the mathematical modeling results validates the developed model. The growth rates of carbon monoxide and carbon dioxide concentrations were determined for construction (wooden) and interior design (polymer) materials. The maximum concentrations of CO and CO2, and the minimum times taken to reach their threshold values corresponded to wood and polyvinyl chloride panels. This research provides a deeper insight into the thermal decomposition of a wide range of fuels and the formation of gaseous pyrolysis products of these fuels. The results obtained can be used to evaluate the toxicity of construction and interior design materials during compartment fires as well as to estimate the safe egress time and risks involved in the process. They can also serve as a database for the development and testing of mathematical models describing fire outbreaks and propagation in confined spaces.

Role of municipal solid waste incineration fly ash components in co-pyrolysis of oily sludge: Pyrolysis products and catalytic mechanism

The co-pyrolysis of oily sludge (OS) and municipal solid waste incineration fly ash (IFA) is a promising strategy for sustainable waste management. This study delves into the distinct catalytic roles of individual IFA components during co-pyrolysis and assesses their impact on the inherent Fe species in OS, highlighting their contributions to overall catalytic activity. Notably, in comparison to IFA, CaCl2 and KCl significantly enhance pyrolysis oil upcycling, while IFA components collectively exhibit a positive catalytic effect on pyrolysis gas and coke production. Ca(OH)2 notably boosts H2 yield by 137.16 %. Alkali chlorides facilitate gaseous hydrocarbon formation and convert oxygen-containing compounds to CO and CO2 which are subsequently consumed and absorbed by CaO and Ca(OH)2. CaCl2 and KCl promote heavy compound decomposition and alkane aromatization, reducing coke formation and increasing light aromatic production. Conversely, NaCl increases alkane proportions. However, CaSO4 and CaCO3 hinder catalytic reactions, promoting carbon conversion to coke. Importantly, IFA compounds aid the dispersion of inherent Fe-based species from OS on char surface, enhancing in-situ catalytic pyrolysis. Additionally, the augmented H2 production accelerates the reduction of Fe-based species. The findings expand waste utilization possibilities and provide insights for co-processing solid wastes.

Mesoporous Silica Nanocatalyst-Based Pyrolysis of a By-Product of Paper Manufacturing, Black Liquor

The valorization of black liquor, a by-product produced in considerable quantities from the paper manufacturing processes, has demonstrated the effectiveness of thermal reconversion into pyrolysis gas, bio-oil, and bio-char, a sustainable approach placing the feedstock into a circular economy concept. The present study focused on developing disposal solutions through energy recovery via pyrolysis at 300 °C and 450 °C when lignite and nanomaterials (such as Cu-Zn-MCM-41, Ni-SBA-3, or Ni-SBA16) were used as catalysts. The results were compared to those of non-catalytic pyrolysis. The use of the Cu-Zn-MCM-41 catalyst proved to be efficient for pyrolysis gas production, reaching 55.22 vol% CH4. The increase in the calorific value of the pyrolysis gas was associated with the use of the Cu-Zn-MCM-41, showing a value of 42.23 MJ/m3 compared to that of the non-catalytic process, which yielded 39.56 MJ/m3. The bio-oil resulting from the pyrolysis with Cu-Zn-MCM-41 showed the highest energy value at 6457 kcal/kg compared to that obtained with the other two nanocatalysts, Ni-SBA-3 and Ni-SBA-16, as well as that of the raw material, which had a value of 3769 kcal/kg. The analysis of bio-char revealed no statistically significant differences when comparing the outcomes from using the various nanocatalysts, suggesting their minimal impact on the energy content.

Kinetics and Composition of Gaseous Products of Pyrolysis of Organometallic Complexes of Nickel, Iron, and Copper with Inorganic Anions

Kinetics and Composition of Gaseous Products of Pyrolysis of Organometallic Complexes of Nickel, Iron, and Copper with Inorganic Anions

The utilization of phytic acid as a reactive flame retardant in the preparation of a fully waterborne biobased epoxy system

AbstractA fully biobased waterborne flame‐retarded epoxy system was prepared using sorbitol polyglycidyl ether epoxy resin (SPE) and phytic acid (PA) as a reactive flame retardant (FR). The flame‐retardant efficiency was evaluated by comparing the reference SPE‐PA system with solventborne and waterborne SPE systems. Additional enhancement of intumescence and reduction of flammability was achieved by incorporating ammonium polyphosphate (APP) and melamine (MEL) into the SPE–PA system. PA, serving as a curing agent, contributed approximately 1% phosphorous content, resulting in an increased limiting oxygen index (LOI). UL‐94 flammability tests demonstrated improved FR properties with PA, and the addition of 2% phosphorous from APP to SPE‐PA achieved a self‐extinguishing V0 UL‐94 rating. Thermogravimetric analysis (TGA) revealed enhanced thermal stability and higher char yield with PA compared with other curing agents. Mass loss calorimetry (MLC) confirmed the superior charring effect of PA compared with other curing agents. The thermal insulation properties of the residual char were assessed by measuring the temperature on the back surface (Tb) of coated steel plates exposed to a 25 kW/m2 heat flux for 1 h. The PA sample containing 3%P of APP exhibited a Tb decrease of 130°C compared with the solventborne reference sample. Scanning electron microscopy analysis of the char morphology supported these findings, indicating the effectiveness of the intumescent FR system. Infrared spectra of the char residues and pyrolysis gaseous products were obtained to gain insights into the flame‐retardant mechanism of the different systems.

Upcycling of composite packaging waste to carbon nanotubes via chemical vapor deposition of pyrolysis gas

Based on the necessity of evaluating composite packaging wastes from both environmental and economic perspectives, it aimed to obtain carbon nanotube (CNT) from the pyrolysis gas product of this material by the catalytic chemical vapor deposition method (CCVD) via an upcycling approach. In the first stage, composite packaging wastes were pyrolyzed. Secondly, the composition of the gas via gas chromatography was determined. In the third stage, CNT production studies were carried out by the CCVD method in a tubular reactor at four different temperatures between 600 and 900 °C with nickel catalyst. The effects of temperature and carbon source feeding ratio on the properties of the obtained CNTs were investigated. CNTs produced in this study were compared with a commercial product. As a result, high-quality multi-walled carbon nanotube of 20–30 nm diameter and in micrometer scale length comparable to commercial products were produced from the gaseous product at 800 °C under Ni-catalysis.

Pyrolysis–gas chromatography of hybrid rocket fuel comprising low-melting-point thermoplastics

Solid fuels comprising low-melting-point thermoplastics (LTs) have been developed as hybrid rocket fuels. However, it is necessary to improve the regression rate of such fuels for practical application. In this study, the pyrolysis mechanism of an LT fuel in the absence of oxygen was investigated and the combustion-inhibition species among the gaseous pyrolysis products were identified. Pyrolysis–gas chromatography was used to analyze the hydrocarbon compounds produced from the pyrolysis of the LT fuel and its constituents. Detailed chemical reaction simulations were performed to dissect the pyrolysis mechanism of paraffin oil, the principal constituent of the LT fuel. The results revealed that the pyrolysis and evaporation of the fuel components yield aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), which reduces fuel combustion. Notably, the C2H4 generated during paraffin pyrolysis considerably amplified the formation of aromatic hydrocarbons and PAHs, further inhibiting combustion. C2H4 was also identified as one of the potential chemical species that inhibit combustion. The C2H4 ratio in the fuel pyrolysis gas can be considered as an indicator for evaluating fuel compositions that enhance the fuel regression rate.

Enhancing hydrogen-rich fuel gas production from dewatered sludge pyrolysis: The effect of hybrid conditioning with peroxyacetic acid, polyaluminium chloride, and KOH-modified activated carbon

Pyrolysis is a promising technology for the disposal of sewage sludge, because it not only greatly reduces the volume of sludge but also converts it into high calorific and pollution-free clean energy, H2. Direct pyrolysis of raw sludge (with moisture content of about 98%) consumes a lot of energy, thus it is necessary to dewater the raw sludge before pyrolysis. However, sludge is a heterogeneous colloidal system, making it difficult to reduce water content with traditional pressurization. Conditioning agents often are needed to improve the dewatering efficiency. In this work, we applied peroxyacetic acid (PA) and polyaluminium chloride (PAC) combined with KOH-modified activated carbon (KAC) to condition the raw sludge (denoted as PA/PAC/KAC) before conducting dewatering and pyrolysis. We found that changes of organic matter composition of the dewatered sludge exerted by the conditioning significantly influenced pyrolysis gas production. The pyrolysis H2 yield from the conditioned sludge can be 4–5-fold higher than the unconditioned. The PA oxidation mediated by KAC led to more olefin substances appearing in the dewatered sludge, which further promoted the production of low aromatic hydrocarbons through the Diels-Alder reaction in pyrolysis and enhanced tar cracking rate. Potassium loaded on KAC catalyzed tar cracking. KAC remained in the dewatered sludge promoted water–gas-shift (WGS) and steam reforming reactions to produce more H2. This study provides a new path to enhance the resource utilization of dewatered sludge and facilitate the resource utilization of the dewatered sludge in potential applications.

Pyrolysis interaction of cellulose, hemicellulose and lignin studied by TG-DSC-MS

The pyrolysis kinetics, heat endothermic and exothermic characteristics and gases formation of cellulose, hemicellulose, lignin and their mixtures were investigated by TG-DSC-MS to understand the interaction of biomass three components and its influence on the pyrolysis gas products. It was found that there were complex interactions among three components, and the activation energy of mixtures pyrolysis was mainly divided into two stages. During the pyrolysis process, cellulose could promote the decomposition of lignin and hemicellulose, while hemicelluloses might restrain the decomposition of cellulose and lignin. Furthermore, lignin promoted the decomposition of hemicelluloses but inhibited the decomposition of cellulose. The interactions also had a great influence on the gas products. The gas products generated during pyrolysis of three components were mainly H2, CO, H2O and CO2. Hemicellulose and lignin promote H2 release, while cellulose and lignin inhibit the release of H2O and CO2, and all three components restrain the release of CO. The effect of hemicellulose on H2O and CO2 would depend on pyrolysis temperature of 325 °C.

High-temperature interaction mechanisms of typical igniting pyrotechnics with cellulose as the packing material

In order to study the effect of cellulose shell on the thermal behavior including pyrolysis gaseous products, ignition and combustion characteristics of typical pyrotechnics, three composites of pyrotechnics/cellulose were prepared in this paper. Various characterization techniques were used to investigate the prepared composites and their combustion condensed products (CCPs), including scanning electron microscopy (SEM), simultaneous thermal analysis (DSC-TG-FTIR), X-ray diffraction (XRD), bomb calorimetry, and home-made combustion diagnostic system. The results showed that the overall heat release of the black powder and Mg/PTFE decreased from 3108 J·g−1 and 1157.4 J·g−1 to 1045.4 J·g−1 and 810.4 J·g−1 in the presence of 33.3% cellulose, respectively. Moreover, the FTIR spectra showed that the cellulose did not change the reaction pathways of black powder and Mg/PTFE, which mainly include H2O, CO2, NO2 for the black powder, and HF, H2O, CO2, CF2 for Mg/PTFE. However, the condensed products of cellulose would interact with B/KNO3 at a higher temperature, so that the heat release was largely increased by 339%. The cellulose has obviously impact on the energy release rate of Mg/PTFE in comparison to the other two composites. Moreover, the negative impact on ignition of Mg/PTFE composite is significant, when the content of cellulose reaches over 33.3%, resulting in difficult self-sustainable combustion at ambient pressure. The cellulose can largely reduce the maximum flame temperature of the black powder and Mg/PTFE, whereas it has little effect on B/KNO3. The CCPs of the involved igniting pyrotechnics and their cellulose-based composites have different phases due to their strong thermal interactions with cellulose.

Pyrolysis of waste printed circuit boards: Parametric effects on product distribution, characterization and gas emissions

The efficient and environmentally friendly disposal of waste printed circuit board (WPCB) is of great significance for resource sustainability. This study focuses on the pyrolysis process of WPCB and the comprehensive characterization of the products. Meanwhile, the emission properties of the main gas products in the pyrolysis process of WPCB were investigated in real time. The results of pyrolysis experiments indicated that a solid yield of 79.03% was obtained by pyrolysis at 500 °C for 60 min, and 91.46% of copper and 95.36% of tin were recovered. The gas products mainly consisted of CO, CO2, CH4, H2, and C2H2. The liquid products contained phenols, aromatic hydrocarbons, ketones and furan derivatives. The pyrolysis gas and liquid products might be utilized as the raw material for fuel and other composite materials after purification. The process combines medium-temperature pyrolysis and crushing processes to recover metal fractions and high-value products from WPCB. This provides a solution for the large-scale pyrolysis of electronic waste.

Two-step valorization of invasive species Rosa rubiginosa L. husk waste through eco-friendly optimized pectin extraction and subsequent pyrolysis

This research studied chemical and thermal treatments of rosehip husk (RH), from invasive species in Patagonia Rosa rubiginosa, which is considered a main waste in the seed-oil extraction industry, to obtain added-value products by optimizing an eco-friendly pectin extraction, followed by pyrolysis of the remaining solid (RHW). The aim was to valorize the rosehip husk of an invasive species by finding the optimal conditions for pectin extraction (maximum yield and minimum CO2 emissions) and assessing the pyrolysis process together with the products obtained, finding the temperature of maximum production of each species in the gaseous product. By applying multi-objective optimization, it was found that the optimal yield was 17.83 % with 456.7 g of CO2 emitted for kg of pectin at temperature T = 79.6 ºC, time t = 30 min, and pH = 2.3. By TGA, 6 processes were identified in the pyrolysis of RHW: moisture evaporation and 5 consecutive reactions which were related to lignocellulosic biomass components decomposition. The kinetic parameters of each reaction were obtained by isoconversional method (activation energy), compensation effect method (pre-exponential factor), and master-plots method (conversion function). The pyrolysis gaseous products of energetic interest identified were CH4, H2, and C2H4, with maximum production at 630, 700, 850 ºC respectively. The main compounds found by GC-MS were diacetone alcohol, mesityl oxide, butylated hydroxytoluene, among others. The ash was analyzed by XRD and showed a high Ca concentration (46.9 %) with presence of Ca(OH)2, MgO, KCaPO4, and K4Ca(PO4)2.

Insights into the pyrolysis mechanisms of epoxy resin polymers based on the combination of experiments and ReaxFF-MD simulation

Epoxy resin offers promising properties in composites, while its cross-linked structure prevents the disposal of waste composites. Pyrolysis is an essential technique for the breakdown of epoxy resin polymers, but the fundamental reaction mechanisms need to be clarified. In this study, the combination of experimental studies and the reactive force field molecular dynamic (ReaxFF-MD) simulation were performed to determine the formation mechanisms of pyrolysis products considering the secondary reactions of intermediates. The pyrolysis process was divided into the cleavage and polycondensation stages based on the carbon atom numbers of the largest cluster. The cleavage stage began with the removal of side-chain substituents, followed by the breakdown of the primary epoxy resin chain, resulting in the generation of pyrolysis gas products, of which the OH, C-C-O, and CH3 groups were identified as the critical intermediates in the creation of H2O, CO, and CH4, respectively. Meanwhile, the simultaneous evolution of liquid pyrolysis products (bisphenol A, phenol, and benzene) was established. After the epoxy resin chains were completely cracked, the unsaturated hydrocarbon intermediates underwent the dehydrogenation and polymerization reactions, causing the formation of pyrolysis char and the continuous generation of H2, H2O, and CO. The findings could provide some guidance to selectively regulate the pyrolysis of epoxy resin matrix composites.