The fragmentation and pulverization behavior of particles during rapid coal pyrolysis directly affect the quality and dust content of pyrolysis products. This study investigated the differences in fragmentation behavior between vitrinite and inertinite particles of Xiaolongtan lignite upon collision with a wall under rapid pyrolysis conditions using a visualizable rapid pyrolysis experimental system. The pore structure characteristics of the resulting vitrinite and inertinite char particles were systematically analyzed through N2 physisorption, mercury intrusion porosimetry, and scanning electron microscopy. Combined with blackbody furnace temperature calibration and high-speed imaging, the temperature evolution of particles before and after collision with the wall was captured and analyzed in real time, revealing the influence of differences in heat transfer rates between macerals on fragmentation behavior under high-temperature conditions. As the pyrolysis temperature increased from 700 degrees C to 900 degrees C, the fragmentation probability of both macerals increased significantly. The fragmentation probability of vitrinite particles rose from 4.60 % to 16.60 %, while that of inertinite increased from 3.40 % to 7.60 %. The fragmentation probability of vitrinite was consistently higher than that of inertinite, with the difference becoming more pronounced at elevated temperatures. This phenomenon is primarily attributed to the higher volatile content of vitrinite, which leads to rapid volatile release during pyrolysis, generating greater expansion pressure; its char possesses a more developed macropore structure, resulting in lower stability and a tendency toward collapse and fragmentation; additionally, the relatively lower thermal conductivity of vitrinite causes higher thermal stress accumulation within the particles, leading to a stronger propensity for fragmentation during rapid pyrolysis.

Steam co-gasification of mixed agricultural and plastic wastes in a single reactor for hydrogen production represents an effective pathway for waste valorization and clean energy generation. Yet the underlying synergistic mechanism remains unclear, which limits process optimization and large-scale application. In this study, the ReaxFF molecular dynamics method was employed to systematically investigate the interaction mechanism during co-gasification by constructing a co-gasification reaction system comprising hardwood lignin and polyethylene molecules. The results show that co-gasification promoted H2 production, with the most significant synergistic effect observed at a feedstock mass ratio of 1:1, where the actual H2 yield was 29.3 % higher than the theoretical value. High-temperature conditions enhanced the hydrogen production pathway, whereas excess steam inhibited tar dehydrogenation reactions. In the reaction pathway, active hydrogen radicals generated from polyethylene cracking promote H2 production by inducing deep dehydrogenation of tar; in contrast, hydrogen atom recombination and hydrogen transfer reactions involving H2O and CH4 make a relatively minor contribution. This study elucidates that the synergistic mechanism underlying hydrogen production via co-gasification stems from the enhancing effect of active ∙H radicals on the dehydrogenation pathway of tar, thereby providing a theoretical basis for optimizing the hydrogen production process by co-gasification of waste biomass and plastics.

Tar is the principal impediment to the commercial deployment of biomass gasification technology. Tar steam reforming, which converts tar into syngas while enhancing gasification efficiency and ensuring cleaner operation, is considered the most promising tar removal approach. CaO-based materials have garnered significant attention due to their high efficiency and economic advantages. An understanding of their catalytic mechanism is therefore crucial. This study investigates the catalytic mechanism of CaO in the biomass tar steam reforming process by combining fixed-bed gasification experiments with ReaxFF MD simulations. Experiments demonstrate that the H2 yield increases 31%, while the yields of light hydrocarbon gases increase correspondingly. Furthermore, CaO catalyzed the cracking of large tar molecules into smaller compounds with lower molecular weights and more oxygen-containing functional groups. ReaxFF MD simulations demonstrated that CaO facilitates H2O dissociation through a hydration reaction (Ca + H2O ↔ H2CaO), generating highly reactive ⋅H and ⋅OH radicals. The ⋅OH radicals subsequently interact with tar molecules, inducing C–H bond cleavage to release ⋅H and form oxygenated molecules (e.g., CH2O2), thereby providing a crucial hydrogen source for syngas formation. DFT calculations further revealed that the coordination of Ca with the oxygen atom of oxygenated molecules triggers a reconstruction of the local electronic structure, generating an electrostatic polarization effect. This effect reduces the C–O bond dissociation energy from 114 to 21 kcal·mol-1, thereby facilitating molecular dissociation. This work elucidates the role of CaO in enhancing syngas production via catalytic cracking, laying a theoretical groundwork for deploying CaO-based catalysts in tar steam reforming.

Residual carbon is a major challenge for entrained-flow gasification technology advancement, compared to the study of other factors such as temperature and pressure, the nature of coal macerals is often ignored. Therefore, in this study, a Joule heating device was used to simulate the rapid temperature rise and short residence time in the entrained-flow gasifier for the preparation of residual carbon. And the fragmentation behavior of char particles was explored by combining the visualization drop tube furnace and high-speed camera system. The thermal sensitivity properties of the char and the structure of the residual carbon were analyzed by different characterizations. The results show that the vitrinite has higher thermal sensitivity and is more susceptible to fragmentation, leading to a higher carbon conversion. Moreover, the vitrinite is more reactive due to the greater number of active sites available on the branched chain, resulting in a relatively slower graphitization process. These results deepen the understanding of coal structure and reactivity.

Torrefied biomass-coal co-pyrolysis was a promising route to realize high-efficiency utilization of renewable and fossil energy. Volatiles-char interaction during co-pyrolysis impacts char structure and downstream applications. However, the relevant mechanism remains unclear, and thus decoupling study was necessary. In this study, dry/ wet torrefied biomass (RST300/RSH300) was prepared at 300 degrees C using autoclave reactor and fixed-bed reactor, respectively. Decoupled co-pyrolysis experiments were subsequently conducted at different pyrolysis temperatures (600, 700 and 800 degrees C) using a staged fixed-bed reactor. Furthermore, various structural characterization techniques (SEM, Raman and FTIR) were coupled to explore the pathway influencing the char structure evolution. The decoupling studies of RST/RSH300-BC co-pyrolysis showed that compared to BC char from individual pyrolysis, RST-BC co-pyrolysis led to significantly more surface deposits. In contrast, RSH-BC co-pyrolysis produced BC char with diverse crack morphologies. At all temperatures, the-OH and C=C peak intensities in RSH-BC chars were much higher than in RST-BC chars. The graphitic ordering of BC chars from both co-pyrolysis systems decreased compared to individual pyrolysis, with RSH300-BC showing a more pronounced reduction. The decoupling results of BC-RST/RSH300 revealed that compared to individual RST/RSH chars, co-pyrolyzed RST char had partially blocked cracks at 700 degrees C and 800 degrees C. Both co-pyrolyzed RST/RSH300 char showed higher-OH and C-O-C peak intensities. Notably, at 600 degrees C and 700 degrees C, the graphitic ordering improved in both co-pyrolyzed RST/RSH300 chars, with RSH chars showing significant enhancement.

The growth of the petroleum and chemical industries has increased the production of petroleum coke (PC) and oily sludge (OS), creating environmental challenges. Co-slurry gasification of PC and OS offers a clean solution for resource utilization and harmless treatment. However, the stability mechanisms of petroleum coke-sludge slurry (PCSS) remain poorly understood, which is key to optimizing slurry preparation and gasification. In this study, oil, solid, and water were separated from OS, and their effects on slurry rheology were analyzed. The results show that adding OS from 1 wt.% to 20 wt.% causes the apparent viscosity to first decrease and then increase by 208 mPa & centerdot; s, with the lowest viscosity and best stability at 10 wt.% OS in PC. The oil phase improves flowability by lubricating and dispersing particles but increases thixotropic behaviour. The solid phase stabilizes the slurry by forming a skeletal structure and preventing sedimentation, though it increases viscosity due to internal friction. Porous sludge particles create a stabilizing network between PC particles. This study provides theoretical support for the industrial application of OS and PC co-slurry gasification.

From both environmental and economic perspectives, there is an urgent need for effective management of the large amounts of gasification fine slag currently stored and landfilled. This study has developed a rapid, efficient and energy-saving method to address this challenge. It can utilize the carbon and silicon in gasification fine slag in situ. These elements can be directly converted into silicon carbide (SiC) without additional carbon sources. The temperature (1600-2000 degrees C) and residence time (5-60 s) of the carbothermal reduction reaction were precisely controlled using a Joule reactor, resulting in the successful synthesis of SiC with diverse morphologies including clustered, needle-like, and rod-shaped structures. The characterization results from XRD, FTIR, and Raman spectroscopy indicate that as the carbothermal reduction reaction temperature and residence time increase, the SiC crystal structure demonstrates a transition trend from cubic to hexagonal phases. TEM analyses further confirmed the (111) facet diffraction of beta-SiC and (101) facet diffraction of alpha-SiC. Moreover, the growth route for SiC with different morphologies may primarily involve vapor-solid (VS) and vapor-liquid-solid (VLS) mechanisms in chemical vapor transport. This study proposes an innovative strategy for the high-value utilization of coal gasification fine slag, offering a novel approach for the sustainable development of solid waste.

To address the high residual carbon content in fine slag during entrained-flow gasification, this study focuses on the gasification reaction mechanisms of pyrolyzed char derived from coal macerals at the molecular level. Using Meihuajing coal (MHJ-R) as a representative sample, inertinite (MHJ-R-I) and vitrinite (MHJ-R-V) macerals were separated to prepare chars MHJ-I and MHJ-V. Multiscale characterizations via solid-state 13C NMR, XPS, Raman, and FTIR revealed that MHJ-I consists mainly of large polyaromatic clusters with high graphitization (aromaticity fa = 78.74 %), whereas MHJ-V contains more long aliphatic side chains relatively (average methylene chain length Cn= 3.30). Molecular models were constructed (MHJ-I: C233H156O28N2; MHJ-V: C283H256O28N2) and validated by matching simulated and experimental 13C NMR spectra. ReaxFF molecular dynamics simulations (300-3000 K, in CO2/H2O atmosphere) were then performed to analyze gasification behaviors. The results indicate that MHJ-V undergoes early cleavage of aliphatic chains, generating reactive radicals and promoting CO/H2 formation efficiently under gasifying atmospheres. In contrast, MHJ-I requires higher temperatures to depolymerize its aromatic cores, resulting in a significantly lower gasification reactivity. This study provides a molecular-level theoretical basis for reducing the residual carbon content in entrained-flow gasification fine slag through targeted regulation of coal macerals.

The interaction between alkali metal salts in biomass and silicon-aluminum minerals in petroleum coke (PC) is closely related to the gasification reaction activity and the deactivation of active K catalysts during the gasification. This work investigates the structural evolution, mineral transformation of biomass ash (CSA) and its catalytic mechanism on PC gasification. The results show that the addition of 30% CSA enhances the gasification reactivity of PC, while an excess weakens the catalytic effect due to the formation of low-activity aluminosilicates. Moreover, the role of alkali metals and their structural evolution are the core factors regulating gasification reactivity. As the gasification reaction proceeds, free potassium, on the one hand, combines with silicon-aluminum components in PC to form KAlSi2 O6 minerals with high catalytic activity, thereby strengthening the gasification of PC. On the other hand, potassium preferentially and selectively activates the disordered carbon structures in PC, leading to a decrease in the orderliness of carbon structures and a significant inhibition of the graphitization process, which further improves gasification reactivity. When the temperature rises to 900–1100 °C, the morphological transformation of potassium enters a stabilization stage. Alkali metals react with silicon-aluminum oxides to form stable potassium aluminosilicate minerals such as KAlSi2 O6 and KAlSi3 O8, resulting in the attenuation of their catalytic activity. Meanwhile, char is encapsulated by the molten phase, the graphitization degree of PC and the orderliness of carbon structures are both recovered, ultimately leading to a reduction in gasification reaction rate. This work provides important implications for regulating the migration/catalytic behavior of alkali metals during gasification and promoting the industrial application of co-gasification technology.

With the large-scale development and utilization of solar energy resources, the number of end-of-life photovoltaic (PV) modules has grown rapidly, and their green recovery and resource utilization have become an urgent challenge. In this study, a chloroaluminate ionic liquid, 1-butyl-3-methylimidazolium chloroaluminate (AlCl3/[BMIM]Cl, denoted as BmA), was employed as the reaction medium to explore an efficient method for PV panel delamination under mild conditions. The effects of ionic liquid molar ratio, reaction temperature, and concentration on the separation performance were systematically investigated. The results demonstrate that complete delamination of 4.3 cm × 3.8 cm PV panel slices into glass, silicon cells, backsheet, and electrode grids can be achieved at 20 °C within 4 h, while the ethylene-vinyl acetate (EVA) encapsulant is concurrently decomposed into hydrocarbon liquid products. Increasing the reaction temperature significantly accelerates the separation rate, and a higher molar fraction of AlCl3 in the ionic liquid leads to superior separation efficiency. Scale-up experiments further validated the effectiveness of this system for the separation of a full-sized PV panel (31 cm × 21 cm). Moreover, using commercial EVA powder along with n-dodecane (representing the main-chain C–C skeleton) and isopropyl acetate (representing the side-chain ester groups) as model compounds, combined with in-situ FTIR, TG-MS, and GC-MS analyses, the mild decomposition mechanism of EVA in the chloroaluminate ionic liquid was elucidated. This study provides both theoretical foundation and technical reference for the development of green and low-carbon recycling processes for end-of-life PV modules under ambient conditions.

Utilizing carbon-neutral biomass reduces reliance on fossil fuels and lowers carbon emissions. Although thermochemical conversion is efficient, it consumes feedstock for heat, reducing biomass conversion efficiency. Molten salts can enhance reactions and store solar energy; consequently, the coupling of solar energy with molten-salt-assisted biomass thermochemical conversion has attracted significant attention. This study evaluated bio-oil and gas production characteristics from biomass, cellulose, and lignin via conventional and catalytic pyrolysis (the latter using ZnCl2, CaCl2, and NiCl2) in molten salts. Analysis of the pyrolysis gases and bio-oil revealed the effects of molten salts and catalysts on product generation from biomass, cellulose, and lignin, and suggested potential reaction mechanisms. Results show molten salts and catalysts boost hydrogen intensity: conventional pyrolysis of biomass in molten salts raises it by up to 62.50%, and catalytic pyrolysis by up to 172.67%. Molten salts and catalysts also reduce bio-oil peak area. Catalysts promote deep decomposition, reducing oxygen-containing compounds in detectable volatile compounds. Ni catalysts promote dehydration-condensation, consuming the most water but producing the least H2. Zn catalysts promote dehydration, dehydrogenation, and in-situ water reforming, greatly reducing bio-oil oxygenates; and polycondensation releases large-scale H2. Ca catalysts show pronounced decarboxylation and dehydrogenation, with feedstock-dependent performance.

To address the environmental challenges posed by the substantial stockpiling of coal gasification fine slag (CGFS), combustion is regarded as a promising technology for realizing its large-scale disposal. The residual carbon (RC) in CGFS exhibits poor reactivity due to its highly graphitized structure and low volatile content, which hinders its utilization in combustion processes. This study focuses on RC and aims to enhance its oxidative combustion activity through ozone-induced surface modification. Hydroxyl functionalization of RC was achieved via an ozone-pulsing method, and the role of hydroxyl groups in regulating combustion behavior and reaction mechanisms was systematically investigated using TG, XPS, Raman, and DFT. The results demonstrate that ozone modification successfully introduces hydroxyl functional groups onto the RC surface, significantly reducing the ignition and burnout temperatures while improving the comprehensive combustion characteristic index. Kinetic analysis reveals that the modified RC combustion reaction follows a two-stage mechanism-chemical control at low temperatures (O1 model) and diffusion control at high temperatures (D3 model)-with the introduction of hydroxyl groups primarily enhancing the reaction rate by increasing the pre-exponential factor A. Characterization results confirm an increase in surface hydroxyl content and greater structural disorder in the carbon matrix, whereas the pore structure remains largely unchanged. DFT calculations based on representative small molecule models of the key surface functional groups in CGFS, namely aromatic, aliphatic, aldehyde, and bridged oxygen structures, further reveal that hydroxyl groups enhance the reactivity of functional groups by reducing key bond dissociation energies, narrowing the HOMO-LUMO energy gap, and optimizing the electrostatic potential distribution. This study elucidates, from both experimental and theoretical perspectives, the hydroxylmediated activation mechanism of functional groups, offering a novel strategy for the efficient energy utilization of CGFS.

Soot is a particulate pollutant generated from the incomplete combustion of coal, which not only reduces combustion efficiency but also poses substantial threats to environmental quality and human health. The organic matrix of coal consists of a macromolecular, three-dimensional network of aromatic units, with mobile low-molecular-weight compounds (LMCs) dispersed within this framework. These inherent structural and compositional features of coal significantly influence soot formation. In this study, four solvents were employed to extract distinct types of LMCs from coal, and their role in soot formation was systematically investigated. The flame morphology and combustion behavior of variously extracted coal samples were recorded in real time using high-speed cameras. Soot concentration was monitored in situ via laser-induced incandescence (LII), while an ultraviolet camera was used to track free radical concentrations during combustion. Furthermore, representative aliphatic, aromatic, and oxygenated model compounds were loaded into extracted coal to simulate LMCs, enabling a deeper exploration of the mechanistic influence of LMCs on soot formation. This study reveals that LMCs in coal substantially promote soot formation, with aliphatic hydrocarbons enhancing soot nucleation and aromatic compounds facilitating surface growth and particle agglomeration. More importantly, oxygen-containing LMCs were found to exert a dual effect: they partially suppress soot yield by promoting oxidation, yet also alter soot morphology and nanostructure. The real-time diagnostics confirm that LMCs modulate soot formation primarily by regulating radical pool dynamics and hydrogen transfer during devolatilization. The outcomes establish a fundamental basis for the precise regulation of particulate emissions through coal pretreatment or LMCs-specific control strategies, contributing to the advanced clean utilization of coal in line with sustainable energy and environmental objectives

A series of Cu/Ce0.9M0.1O2 catalysts were prepared by introducing Zn2+, In3+, and Zr4+ into the CeO2 lattice via solvothermal method. The influence of the dopant ion radius on CO2 hydrogenation to methanol was systematically investigated. The results showed that Cu/Ce0.9Zn0.1O2 exhibited the best activity, with CO2 conversion reaching 12.1 % and methanol selectivity as high as 93.8 % under the conditions of 3 MPa, 280 degrees C, and 24,000 mL gcat-1 h-1. This performance was significantly better than that of the undoped Cu/CeO2 catalyst. Since the radii of Zn2+, In3+, and Zr4+ were smaller than that of Ce4+, they induced lattice relaxation and deformation in CeO2, which enhanced the dispersion of CuOx species on the support and strengthened the interaction between CuOx and the support. This promoted electron transfer from CeO2 to CuOx species and facilitated the formation of oxygen vacancies, accelerating CO2 activation and H2 dissociation, ultimately improving the methanol production activity. Among them, Zn2+ with the smallest radius, induced the strongest lattice contraction, the most significant electron transfer effect, and the highest oxygen vacancy concentration, leading to the best methanol selectivity and production activity.

Catalytic pyrolysis is a promising method for converting biomass into high-value bio-oil, but the high water (15 %-35 %) and oxygen content in bio-oil limits its application. A dual-catalyst system of CaO and Ni/Char has shown effectiveness, but improving their interaction to reduce water formation and enhance bio-oil quality requires further research. This study investigated the effect of carrier type and Ni loading on bio-oil composition and water yield during the pyrolysis of corn straw in Py-GC/MS and a fixed-bed reactor. Results revealed that AC, compared to other supports like bio-char, showed weaker activity and selectivity in cracking bio-oil components. When a Ca-Ni binary catalyst was introduced, the water yield decreased by 9 % compared to Ni/AC, dropping from 31 % in non-catalytic pyrolysis of CS to 21 %. Interestingly, the amount of CaO in the binary system was only half of that in pure CaO catalysts, yet it achieved similar results in reducing water yield. The lowtemperature water vapor adsorption of CaO and the catalytic role of Ni/AC synergistically promoted water conversion and bio-oil formation. Additionally, the improvement of Ni/AC on phenol formation combined with the inhibition of CaO on phenol decomposition increased phenolic content by 49 % from 40 % in non-catalytic pyrolysis. Higher Ni loading reduced oil yield but selectively retained phenols through the suppression of phenols cracking. The study also explored the different effects of high-activity and low-activity Ni-CaO systems.

The catalytic effect of biomass ash on carbonaceous material gasification reactions is determined by the property evolution and interactions among key components (i.e., K, Ca and Si) of biomass ash during gasification. This study established biomass ash model systems (BAMS) using KCl, CaCO3 and SiO2 to investigate the property (chemical occurrence form, microscopic morphology) evolution, and the interactions of unary, binary, and ternary model compounds under steam gasification atmosphere using a fixed-bed reactor. In addition, FactSage thermodynamic simulation software was also used to predict and confirm the evolution pathway of BAMS under steam gasification atmosphere. Results revealed that KCl reacts with SiO2 to form K2Si4O9, while the presence of CaCO3 promotes KCl volatilization and forms K2CaSiO4 and CaSiO3. At 800 degrees C-900 degrees C, Si inhibits KCl release (as K is fixed in silicates), whereas Ca enhances KCl volatilization by preferentially reacting with SiO2 and generating molten CaO particles. At 1000 degrees C, temperature becomes the dominant factor, leading to convergent KCl release rates. Additionally, the insoluble silicates formed by the model material in the gasification atmosphere decreased with increasing temperature, primarily due to increased K volatilization as KCl and hindered reactant contact caused by molten phases (K2O-SiO2, K2O-CaO-SiO2). Finally, the evolution pathways of BAMS under steam gasification atmosphere were elucidated.

Ammonia-methane co-combustion represents a promising carbon-neutral pathway, yet the coupled formation mechanisms of nitrogen oxides and soot remain poorly understood. This study develops a unified kinetic model by integrating Okafor's nitrogen chemistry with soot precursor sub-mechanisms to investigate pollutant formation in NH3/CH4 counterflow diffusion flames under operating conditions with ammonia blending ratios ranging from 0 to 40% and equivalence ratios from 0.7 to 1.3. Results demonstrate that ammonia reduces benzene formation by up to 90% through dual thermal-chemical inhibition, while nitrogen oxide distribution broadens with ammonia addition. The NH3 pyrolysis pathway dominates nitrogen oxide formation. This work provides the first framework for simultaneous nitrogen oxide and soot analysis under varying equivalence ratios, identifying optimal conditions for synergistic pollutant reduction as 20-30% ammonia, & Fcy;= 0.9-1.1, and offering mechanistic guidance for clean ammonia combustion systems.

Gasification is one of the most promising approaches for large-scale utilization of coal gasification fine slag (CGFS). However, achieving efficient gasification remains challenging due to its fine particle size and poor reactivity of residue carbon. Co-briquetting CGFS with biomass for fixed-bed gasification can effectively address these technical difficulties. This study systematically investigated the mechanical strength, co-gasification reactivity, and ash fusion behavior of briquette fuels with different blending ratios of CGFS and wheat straw (WS). The results indicate that as the CGFS blending ratio increased, the cold compressive strength of the briquette fuel first increased and then decreased. The adhesion effect of lignin in WS and the skeletal support effect of large particles as well as the pore-filling effect of small particles in CGFS collectively enhance the cold strength of co-briquetting fuels. During the co-gasification process, the catalytic effect of alkali metals in WS significantly enhances the reaction activity, demonstrating a notable synergistic effect, and the activation energy of the co-gasification reaction is significantly lower compared to that of CGFS gasification alone. Notably, the formation of high-melting-point leucite mineral phases in the co-gasification slag significantly increased the ash softening temperature and effectively reduced sintering tendency. Comprehensive analysis of performance indicators revealed that when the CGFS blending ratio was controlled within the range of 10%-40%, the briquette fuel not only met the strength requirements for fixed-bed gasification but also exhibited high gasification reactivity while maintaining a low risk of ash slag sintering.