The selective hydrogenation of fatty acids is critical for producing sustainable chemicals from natural oils. Here, We prepared a carbon encapsulated nickel catalyst, denoted as Ni@C-N2, which achieved over 99% conversion of oleic acid under mild conditions (210 degrees C, 1 h) with in situ hydrogen supplied by methanol, yielding 96.8% octadecanol. After eight cycles, no loss in catalytic activity was observed, with conversion above 96.0% and octadecanol yield exceeding 91.0%. The catalyst is also effective for other fatty acids, including palmitic, lauric, and stearic acids, producing the corresponding fatty alcohols in yields above 88.0%. Analysis of structure and activity shows that oxygen-containing functional groups on the catalyst surface are crucial. By adjusting the calcination atmosphere (N2, H2, etc.) of the catalyst precursor, the content of oxygen-containing functional groups can be modulated. Mechanistic studies reveal that a higher abundance of oxygen-containing groups facilitates oleic acid adsorption, accelerating the reaction, while the octadecanol product rapidly desorbs. This selective adsorption and rapid desorption mechanism results in favorable octadecanol yield. This work elucidates the role of oxygen-containing functional groups in regulating product distribution in fatty acid hydrogenation and provides theoretical support for understanding substrate adsorption in alcohol self-supplying hydrogen systems.

Clogging is a prevalent issue in fields such as shale oil and gas development, colloidal contaminant control, and chemical processing engineering. Particularly in the coal chemical industry, clogging induced by complex multiphase flow not only impairs production efficiency but can also result in catastrophic equipment damage. In this study, high-speed imaging technology was employed to investigate the clogging behavior and mechanisms of gasification slag particles within multi-stage orifice pipes, focusing on the influence of particle size and injection rate. The particle flow behavior and wall impact characteristics were analyzed. Experimental results demonstrate that clogging within multi-stage orifice pipes is governed by the ratio of the orifice width to the minimum particle dimension (W/dmin) and the particle concentration. A clogging mechanism map was established based on W/dmin and the particle aspect ratio (AR). Stable two-particle and, to a lesser extent, three-particle bridging structures were observed, with two-particle bridging being the predominant form. Further analysis indicates that particles prone to bridging-induced clogging typically cluster within the ranges of W/dmin = 1.43–2.22 and AR = 1.25–1.70, where particles form stable bridging structures via interlocking. Single-particle jamming occurs within the ranges of W/dmin = 1.05–1.54 and AR = 1.25–1.45, typically resulting from excessive particle size or unfavorable orientation at the orifice. Clogging predominantly occurs near the orifice edges. The probability of clogging increases with particle concentration and injection rate, and is most frequently observed at the first-stage orifice. These findings provide a theoretical basis for the design and optimization of multi-stage orifice pipes.

The gasification of heavy oil is hindered by high soot production and steam consumption, necessitating a deeper understanding of the underlying chemical processes. To accurately simulate the pyrolysis and gasification of complex real fuels, an advanced multi-component surrogate model comprising linear, branched, and cyclic hydrocarbons was developed. Utilizing reactive force field molecular dynamics simulations combined with gasification experiments, this study investigated the gasification process of vacuum residue oil, aiming to optimize gasification performance and reveal the mechanisms of oxygen and steam on gasification. Results show that increasing the oxygen oil ratio and optimizing the water oil ratio enhanced carbon conversion, achieving a maximum of 93.54%. The scanning electron microscope results of soot revealed complementary oxidation pathways: oxygen primarily attacked the interior of soot nuclei, while steam reacted preferentially at the surface. Simulations further demonstrated that the presence of these oxidizers suppressed soot particle growth by fragmenting carbon chains and nascent soot clusters. This atomic-scale insight explains the experimentally observed promotion of carbon conversion, providing guidance for the optimization of gasification processes.

To elucidate the conversion mechanism of Naomaohu coal-derived asphaltenes (NMH-ASP) in the high-temperature stage during the two-stage liquefaction (TSL) process, various catalysts, including Fe2O3, alpha-FeOOH, iron stearate (FeSA) and NiMo/gamma-Al2O3, were presulfurized at low-temperature to reveal the effect of their active phase on liquefaction performance and products selectivity. The results showed that NMH-ASP conversion and oil yield dropped in the following order at 430 degrees C for 60 min: NiMo/gamma-Al2O3 (85.32 wt%; 71.20 wt%) > FeSA (70.97 wt%; 63.71 wt%) > alpha-FeOOH (68.79 wt%; 61.50 wt%) > Fe2O3 (63.46 wt%; 54.76 wt%). The NiMoS phase from NiMo/gamma-Al2O3 sulfurization exhibited superior H-2 activation ability, facilitating aromatic-ring hydrogenation and the cleavage of C-al-O and C-ar-O bonds, resulting in deep deoxygenation. Consequently, the liquefied oil showed the highest cycloalkane content (10.39 %) and the lowest oxygen-containing compounds (1.89 %), along with higher CO2 content (1.50 wt%) in the gas. The Fe1-xS phase of FeSA showed smaller, more uniform crystallite sizes, promoting the cleavage of aliphatic side chains and C-al-C-al bonds, leading to increased formation of chain alkanes (20.82 %) and C-1-C-4 gases (2.34 wt%). alpha-FeOOH-derived Fe1-xS enhanced solvent hydrogen transfer to free radical fragments and promoted C-al-C-ar dealkylation, resulting in a higher benzene series content (29.62 %). However, the Fe1-xS phase of Fe2O3 exhibited lower efficiency in C-ar-O bond cleavage, leading to the accumulation of phenols (8.21 %) and a higher content of the naphthalene series (43.49 %) due to insufficient aromatic-ring hydrogenation. This work provides theoretical guidance for catalyst design and process optimization in TSL.

This work aims to study the slagging behavior of Zhundong (ZD) high-sulfur coal ashes, with a view to enabling these coals to be applied in liquid-slagging entrained-flow gasification. The fusion temperatures and slag viscosities of four selected ZD coal ashes were characterized by ash melting tester and high-temperature rotational viscometer, and the underlying mechanism was revealed by combination of X-ray diffractometer (XRD), thermodynamic calculation, and Scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS). It was found that the four high-sulfur ZD coal ashes exhibited relatively low content of acidic oxides but significantly higher contents of basic oxides, with quartz (SiO2), anhydrite (CaSO4), and hematite (Fe2O3) identified as the predominant crystalline phases. Despite similar sulfur content and mineralogy, these four coal ashes could be categorized into two groups according to their viscosity-temperature characteristics. Hongshaquan (HSQ) and Yima (YM) coal ashes had relatively low fusion and liquidus temperatures. At high temperatures, their slags became fully molten, and the sulfur in these coal ashes was completely decomposed during pre-melting, which contributed to their favorable viscosity-temperature characteristics. However, due to excessive CaO and MgO in Tianchijiangjun (TCJJ) and Tianchinan (TCN) coal ashes, their liquidus temperatures and high-temperature viscosities were relatively high. The sulfur in the pre-melted slags failed to fully decompose, thereby exerting an adverse effect on slag viscosity. Therefore, in industrial applications, when regulating the viscosity-temperature characteristics of high-sulfur coal ash, priority should be given to optimized the chemical composition of coal ash to reduce its liquidus temperature and high-temperature viscosity.

Entrained flow gasification technology represents a critical advancement in the clean utilization of coal and organic waste materials. The burner, a core component of gasification systems, has historically suffered from limited operational lifespans due to issues such as erosion, thereby compromising process safety and long-term reliability. This paper proposes an intrinsically safe design principle based on the combustion/gasification reaction process and oxygen jet entrainment within the furnace, which utilizes the isolation of an inert process medium to reduce combustion intensity. Numerical simulations demonstrate that this inert process media isolation method effectively reduces combustion intensity and flame temperature near the burner exit. Based on the proposed design principle, three kinds of gasification burner isolated by coal water slurry, steam, and pulverized coal are developed and applied in industry. The industrial applications show that the service life of the newly developed burners is greatly improved compared with the traditional burner. The service life of a novel coal water slurry burner with partial coal water slurry isolation has exceeded 180 days, and the service life of pulverized coal burner with steam and pulverized coal (oxygen stream in an annular pulverized coal jet) have surpassed 490 and 360 days, respectively.

To investigate the synergistic mechanism of co-gasification between oily sludge (OS) and deoiled asphalt (DOA) under a CO2 atmosphere, single-factor experiments were conducted in a high-frequency furnace. The characteristics of the co-gasification reaction were examined using the syngas (CO + H2 + CH4) yield as the primary indicator. Process parameters were optimized via orthogonal experiments, with synergistic factors during gasification analyzed. The morphological characteristics of the gasification residues were characterized. The results indicate that the optimal conditions were determined to be an OS/DOA ratio of 6:4, a temperature of 1200 degrees C, and a reaction time of 20 min. Under this optimized setup, the maximum syngas yield reached 1.27 m3/kg, accompanied by an LHV of 11.69 MJ/Nm3. Moreover, the cold gas efficiency (CGE) and carbon conversion efficiency (CCE) peaked at 66.61% and 80.09%, respectively. The blending ratio and reaction temperature are important factors and show significant synergy during co-gasification. At the blending ratio of 6:4, the residue exhibited the roughest surface morphology with a significant development of pores. The specific surface area increased to 22.57 m2/g, accompanied by a concentrated distribution and a greater population of mesopores in the 2-50 nm range, as determined by BET analysis. Under this specific ratio, OS facilitated the conversion of DOA and activated the alkali and alkaline earth metals (AAEMs) and iron (Fe) in the mixture. This led to the formation of abundant pore structures and active centers on the residues surface, which in turn significantly promoted the synergistic gasification effect.

Hydrodeoxygenation (HDO) effectively reduces oxygen content and enhances fuel quality in biomass pyrolysis oil (bio-oil), though catalyst sensitivity to impurities - particularly potassium ions (K+) absorbed during biomass growth - remains understudied. This investigation systematically examines K+'s impact on HDO product distribution and fuel properties using CuMgAlOx catalysts. Experimental results demonstrate that under optimal conditions (360 degrees C, 2 h), the K+-free system increased the higher heating value (HHV) from 25.6 MJ/kg to 32.9 MJ/kg, accompanied by significant reduction of oxygenated compounds (phenols, ketones) and a left-shifted boiling point curve. K+ introduction suppressed alcohol formation while increasing ester content (HHV decreased to 30.4 MJ/kg), concurrently hindering light fraction conversion of heavy components. Mechanistic studies employing model compounds suggest that K+ may alter deoxygenation pathways through dual mechanisms: (1) facilitating the dehydration-condensation of carboxyl/carbonyl groups to form macromolecular esters, and (2) enhancing the hydrogenation of aromatic hydroxyl groups to produce cyclohexanol intermediates.

Coal gasification is one of the important ways to achieve clean and efficient utilization of coal, and the fusion characteristics of coal ash play a crucial role in guiding industrial gasifier operations. This paper establishes prediction models for the fusion characteristic temperature (FT) of coal ash based on machine learning (ML) algorithms using a comprehensive dataset that encompasses a vast majority of coal types in China. It was found that the XGBoost model optimized by Bayesian optimization algorithm exhibited the best predictive performance, achieving a test set R2 of 0.886 and a test set RMSE of 29.166. Feature importance analysis revealed that Al2O3 and A/B have higher importance in predicting FT. The constructed ML model is further applied to guide the optimization of FT of high silica-aluminum content coal through the addition of CaO. It was found that the optimization strategies obtained by ML follow the experimental validations. The fundamental difference between the ML model and the FactSage model is also elaborated. Overall, this work presents important progress on coal ash flow temperature prediction and optimization using machine learning approaches and could be applicable to industrial applications.

Catalytic pyrolysis of low-rank coal was performed in a decoupled triple bed reactor (DTBR) using natural magnetite as a catalytic solid heat carrier. The DTBR consists of a pyrolysis reactor, a catalytic reactor, and a combustion reactor. The coal is fast pyrolyszed in the pyrolysis reactor with the help of the hot heat carrier. The generated volatiles then pass through the catalytic reactor, where tar upgrading and particulate interception occur simultaneously. The spent heat carrier and char are subsequently transported to the combustion reactor for regeneration. The effects of particle size of coal, catalytic temperature and heat carrier to coal mass ratio (HC/C) on product distribution, tar composition, gas formation, attrition behavior, and dust removal were systematically investigated. The results showed that coal particle size negligibly affects product distribution in the 0.18-0.85 mm range. The magnetite significantly improved tar quality compared with quartz sand by increasing the light tar fraction and aromatic compound content. At 550 degrees C, the light tar fraction obtained with magnetite increased to 82.1%, compared with 70.7% for quartz sand, while the aromatic compound content increased to 50.7%, compared with 38.2% for quartz sand. Variation in HC/C caused no significant change in overall product distribution, but the phenol content increased from 18.9% to 28.1% as the ratio increased from 10/1-20/1. The attrition rate of magnetite is slightly higher than that of quartz sand that ranged from 2.5% to 4.5%. The dust yield decreased from 5.32 g/kgcoal without a solid heat carrier to 0.35 g/kgcoal with solid heat carrier, representing a dust removal efficiency of 93.4%. These results demonstrate that the DTBR provides an effective route for the integrated upgrading of coal tar and removal of pyrolysis dust.

Residual oil is prone to irreversible coking at high temperatures, which diminishes heat transfer efficiency and leads to pipeline blockage. Therefore, elucidating the coking mechanism is essential for extending industrial operation cycles. In this study, molecular structural models of saturates, aromatics, resins, and asphaltenes were constructed using component separation and an improved Brown-Ladner method. The coking process was investigated through reactive-force-field molecular dynamics (ReaxFF-MD) simulations combined with X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy and Elemental analyses. The results indicated that at the simulated temperature of 3250 K, the early stage of the reaction was dominated by side-chain cleavage and gas release, followed by synergistic chain scission and aromatic rearrangement, which promoted structural ordering. Notably, cross-linking of aromatic sheets induced rapid carbon-cluster growth: the largest cluster consisted of 2,080 carbon atoms, accounting for 83.74% of the total carbon in the system, while the H/C atomic ratio decreased from 1.27 to 0.39. In later stages, dehydrogenation and polycondensation, accompanied by structural stabilization, produced highly aromatized, densely packed coke with an H/C atomic ratio of 0.1. The change in the number of aromatic rings and the radial distribution function demonstrated a dynamic transition from disorder to order, which was also confirmed by experimental characterization. This study validates the reliability of ReaxFF-MD in elucidating the coking mechanisms of residual oil and supports the molecular design of coke inhibitors.

The enhancement of tar yield during rapid pyrolysis of pulverized coal is governed by the balance between primary volatile release and secondary reactions, yet the underlying mechanisms remain unclear. In this study, a drop-tube furnace was used to investigate the product distribution of pulverized Naomaohu coal at various residence times, temperatures, and atmospheres. A coupled model was then developed, integrating kinetics, intraparticle heat transfer, and gas-phase secondary reactions, to elucidate the critical mechanisms governing the enhancement of tar yield. Experimental results demonstrated that the tar yield achieved a peak value of 19.14wt.% at 1.5L·min-1 and 500 °C under an N2 atmosphere. Notably, the N2:H2 atmosphere exhibited optimal performance, increasing the tar yield by 29% and the light oil content by 13%. Model analysis revealed that residence time dictates the temporal competition between intraparticle thermal penetration and gas-phase thermal quenching, whereas temperature governs the reaction kinetics and thermal homogenization processes. Both synergistically achieve the optimal balance between primary volatile release and secondary cracking suppression, thereby maximizing tar yield. The reducing atmosphere, compared to N2, effectively compressed the radial temperature gradient and promoted intraparticle thermal synchronization, reducing the particle thermal response time from 96 to 64 ms, representing a ~50% increase in the heating rate. Concurrently, its hydrogen-donating capability stabilizes primary volatiles via hydrogenation and hydrogen transfer, thereby suppressing polycondensation and char formation, and ultimately protecting the integrity of tar precursors. These findings provide a basis for maximizing volatile survival during rapid coal pyrolysis.

Traditional methods for predicting coal pyrolysis tar yields often fail to integrate both static coal properties and dynamic reaction mechanisms. To address this limitation, this study proposes a cross-scale modeling strategy driven by temporal graph attention. By coupling ReaxFF molecular dynamics simulations with a multimodal machine-learning framework, we developed a hybrid model that incorporates static bonding topologies, graphembedded chemical topological features, and dynamic bond evolution behaviors. The model achieves ultra-high predictive accuracy (R2 = 0.9986) even with a small dataset of 20 coal types, reducing the root-mean-square error (RMSE) by 95% compared to previous approaches. The low fracture energy barriers (110-227 kJ/mol) of aliphatic (Cal-Cal, Cal-H) and oxygen-containing bonds (O-H, Cal-O) were found to be the kinetic essence of tar formation, according to a joint analysis of SHAP and activation energy. In contrast, the high activation energy (368.76 kJ/mol) of the aromatic bond (Car-Car) caused high-temperature condensation and reduced tar yield. Simultaneously, the thermodynamic origin of energy-efficient conversion was revealed through dynamic energy distribution as the synergistic effect between stepwise cleavage of aliphatic bonds and free-radical reactions, while the equilibrium between hydrogen transfer and aromatization pathways was modulated by synergistic cleavage of oxygen-containing bonds. Additionally, the distinction between the efficient bond cleavagerecombination of aliphatic structures and the inherent inertness of aromatic frameworks was further elucidated through an analysis of energy conversion efficiency (eta). In summary, this hybrid model accurately predicts tar yield and clarifies the underlying formation mechanisms, providing a refined, multi-scale understanding of coal pyrolysis.

As an auxiliary method in the acid gas (H2S<50.0% (vol)) combustion, fuel gas combustion generally promoted the SO2 production, which is unfavorable for improving sulfur recovery efficiency. In this research, pure oxygen combustion method was applied to the acid gas combustion for decreasing SO2 production. An equilibrium model was utilized to perform a thermodynamic analysis of acid gas combustion, and combustion experiments were performed in a coaxial jet double channel burner for analyzing the distribution of flame temperature and gas concentration during the pure oxygen combustion and CH4 co-combustion, respectively. The results indicated that pure oxygen combustion of acid gas could decrease the SO2 formation and increase the S2 yield compared to the fuel gas combustion of acid gas. S2 yield maintained stable at different equivalence ratios, and in the pure oxygen combustion its yield was higher about 3.5 percentage points compared to the fuel gas combustion, and SO2 yield was decreased by about 1.21 percentage points when the H2S/SO2 value was closer to the ideal value of 2.0. SO2 was mainly formed in the oxidation process of H2S, and the formation of S2 was in the whole H2S combustion process under Claus conditions. The formation of SO2 was mainly through the oxidation reaction between the sulfur species released by H2S. The application of pure oxygen combustion to acid gas with a H2S concentration below 50.0% (vol) achieve the objective of decreasing SO2 formation and forming a stable flame under Claus conditions.

The decarbonization of aviation urgently demands efficient pathways to produce renewable jet fuels meeting stringent ASTM D7566 specifications. Current hydrodeoxygenation (HDO) of aqueous phase bio-oil (APBO) suffers from low carbon efficiency (<40%) and undesired short-chain hydrocarbons, due to its high acidity, water content, and low-carbon oxygenates. Herein, we propose a tandem catalytic strategy using a dual-bed system to achieve precise fraction-based conversion of APBO into jet-range hydrocarbons. The first bed, 10Ni/CeZrOx, leverages synergistic Lewis acid-base pairs and highly dispersed Ni sites to catalyze carboxylic acid ketonization, completely converting acetic acid and furans into C8+ ketones at 280°C and WHSV = 1h-1 while suppressing decarboxylation (gas yield ≤ 13.5%). The second bed, PtNiCo/β, facilitates deep hydrodeoxygenation via Pt-Ni-Co alloy-enabled H2 dissociation and Brønsted acid-mediated deoxygenation, attaining > 89.7% conversion of cyclopentanone and guaiacol under 280°C and WHSV = 2h-1. Notably, the integrated systemdemonstrates remarkable synergy: conversion of refractory oxygenates exceeds 90% (a 23-25% gain over single catalysts), C8-C16 hydrocarbon yield reaches 70.2% with > 85% carbon efficiency, and cycloalkanes selectivity attains 80.8%-ideal for high-density jet fuel-while aromatics are suppressed to 4.0%. Gas byproducts are minimized to 1.6% (>80% reduction), and coke formation is markedly lowered (5.1% weight loss shifted to 400-700°C). Operated under mild conditions (280°C, 3 MPa H2), this approach offers a scalable and carbon-conserving route to sustainable aviation fuel (SAF), overcoming key limitations of conventional APBO upgrading.

The integrated co-pyrolysis of biomass and coal with CO2 reforming of CH4 (CP-CRM) is regarded as an effective route to enhance tar yield, however, the effect of inherent minerals in coal and biomass on tar yield and quality remains unclear. In this work, a two-stepwise acid-leaching pretreatment was applied to demineralize NMH coal and cotton stalk, and their co-pyrolysis under N2 (CP-N2) and CP-CRM was investigated to elucidate the role of the inherent minerals in improving tar yield and compositions. Results showed that the minerals influenced the products distribution during co-pyrolysis. Demineralization pretreatment significantly enhanced the tar yield. With the stepwise removal by HCl and HCl/HF, the maximum tar yield at 450 degrees C in CP-N2 was improved from 18.88 wt% to 24.28 wt% and 27.21 wt%, respectively, indicating that AAEMs and transition metal salts in raw coal and biomass could catalyze the cracking of tar precursors and/or the condensation of volatiles. In CP-CRM, the maximum tar yield at 500 degrees C was increased by 18%, 6% and 6% in comparison with that in CP-N2 with the gradual demineralization by HCl and HCl/HF leaching, respectively, which was attributable to the stabilization of large free radicals and suppression of the condensed aromatic rings by the generated center dot H and center dot CHx radicals. Meanwhile, the inherent minerals also affected the quality and compositions of the resultant tar from CP-CRM. The light oil content gradually increased, while the content of anthracene oil and pitch decreased in the tar from CP-CRM, which was attributed to the suppression of polycondensation reactions by center dot H and center dot CHx. Additionally, the removal of AAEMs and Fe- species in raw materials decreased the contents of phenols and aliphatic compounds and boosted the content of aldehydes, ketones and benzenes. The naphthalenes content in resultant tar was higher than that in CP-N2, but gradually decreased with further removal of the minerals, different from the increase trend in CP-N2, which was attributed to the contribution of center dot H and center dot CHx from CRM. This work is helpful for efficient utilization of coal and biomass and improving the yield and quality of tar in co-pyrolysis.

The conventional lock-hopper systems, operating in batch mode, are a major source of operational instability and frequent downtime in coal gasification processes, leading to significant economic losses and reliability challenges. To overcome these limitations, this study proposes a novel multistage pressure-reducing structure designed to replace traditional lock-hopper configurations, enabling continuous slag discharge with a radically simplified design and significantly higher operational efficiency. Utilizing an integrated experimental and two-way coupled computational fluid dynamics (CFD) approach, the research systematically investigates the complex multiphase erosion mechanisms inherent in continuous slag handling. Key findings identify three critical erosion hotspots: the impact zone at the decompression chamber inlet, the rebound-circulation zone near the segment root, and the sharp edges of orifice openings. Particle behavior analysis reveals a three-stage process in the rebound-circulation zone—deceleration, quasi-stagnation, and secondary acceleration—which results in helical trajectories and repeated wall impact. The maximum erosion rate follows a cubic power-law relationship with flow rate, while larger particles, contrary to conventional wisdom, reduce overall erosion due to complex flow-structure interactions. These insights offer practical design strategies for developing erosion-resistant continuous slag discharge systems, ultimately enhancing the reliability and efficiency of coal gasification operations.

Oil-soluble catalyst is a promising alternative to non-oil-soluble catalyst due to excellent dispensability in coal-oil slurry and relatively high activity. To reveal evolution behavior of active phase of the oil-soluble Fe-based catalysts in direct liquefaction of Shangwan coal, three oil-soluble Fe-based catalysts (FeLA, FeOA, FeSA) were synthesized via saponification method with linoleic acid, oleic acid and stearic acid as organic ligands, and were compared with two traditional iron oxide catalysts (Fe2O3, FeOOH). The evolution of active compositions during different temperatures was studied by XRD, SEM, XPS and HRTEM. Results demonstrated superior stability and catalytic activity of oil-soluble catalyst during direct liquefaction. TG and FTIR analyses confirmed the decomposition at lower temperatures, and formed active phases more readily than Fe2O3 and FeOOH catalysts. The oil yields were significantly improved up to 62.82 wt%, 64.38 wt% and 66.36 wt% for FeLA, FeOA and FeSA, which were higher than those of Fe2O3 and FeOOH catalysts. FeOA and FeLA catalysts particularly excelled in promoting the formation of cycloalkanes, thereby improving oil quality. The characterizations by XRD and XPS analyses of the samples indicated that these oil-soluble catalysts rapidly form Fe0.875S at lower temperatures, avoiding intermediate oxide phases. Smaller crystallite sizes were produced for oil-soluble catalysts compared than Fe2O3 and FeOOH. Especially, substantial amounts of Fe0.875S were generated for FeSA during initial coal pyrolysis, which activated hydrogen to stabilize coal macromolecular radicals and enhanced coal conversion and yield. This work provides a guide for the development of highly efficient catalysts in direct coal liquefaction.

During the biomass gasification process, the migration of chlorine can corrode the membrane walls and gas pipelines of the gasification system. This study investigates the forms and migration behaviour of chlorine under different operating conditions in the gaseous phase, bottom ash, and fly ash via response surface methods. The results demonstrate that chlorine release can be effectively regulated. As the temperature rises and particle size decreases, the proportion of released gaseous chlorine can reach 55.9 %. The addition of steam also promotes chlorine migration into the gaseous phase. X-ray photoelectron spectroscopy reveals a key C-Cl intermediate, providing mechanistic evidence for secondary reactions between volatilised chlorides and the residual char that prolong chlorine retention. Kinetics analysis reveals a low activation energy (17.76 kJ/mol), indicating that the release process is dominated by diffusion and evaporation rather than chemical bond cleavage. This work delivers actionable strategies for regulating chlorine distribution and offers fundamental insights into its migration mechanisms, providing a viable approach to mitigating chlorine-induced corrosion in industrial gasification systems.