The improper disposal of plastic waste represents both the loss of valuable resources and significant environmental threat. To address this issue, this study investigates the thermal liquefaction of high-density polyethylene (HDPE) using low-pressure superheated methanol. It systematically evaluates the effects of the reaction temperature and the ratio of reactant to methanol on the liquefaction efficiency and product characteristics. Results indicate that the complete conversion of HDPE could be achieved in low-pressure superheated state methanol (<0.5 MPa) at a minimum external heating temperature of 260 °C. Under this condition, the oil yield reached 77.1% with alkanes comprising 62.3% of the product alongside minor oxygenated compounds. As temperature increased, the average carbon number of hydrocarbons gradually decreased. Below 260 °C, the HDPE conversion decreased significantly, and the products were primarily waxy. At 290 °C, the proportion of gasoline-like fractions (C6–C12) increased markedly from 16.6% to 80.9%. Furthermore, reactant ratio plays a critical regulatory role; extremes in ratio—either too high or too low—diminish heat transfer efficiency and reduce conversion. Mechanistically, the liquefaction primarily involved the cleavage of secondary C−C bonds, where the resulting oligomers further cracked into free radicals to form diverse hydrocarbons through secondary reactions. This work demonstrates that low-pressure superheated methanol liquefaction is a mild, efficient, and pretreatment-free method to upcycle polyethylene into valuable fuels. Optimizing these process parameters can pave the way for industrial application, aiding in both plastic pollution management and sustainable resource recovery.

Alumina microspheres with a lamellar-assembled morphology were synthesized via a urea-assisted hydrothermal method, and a Pd/Al₂O₃-M catalyst was prepared by incipient wetness impregnation. Its catalytic performance was systematically evaluated and compared with that of a commercial alumina-supported Pd catalyst in both the selective hydrogenation of isoprene and the hydrogenation of 2-ethylanthraquinone for hydrogen peroxide production. Characterization results reveal that the alumina microspheres exhibit a well-defined flower-like structure composed of stacked nanosheets, which promotes high Pd dispersion. Compared to Pd/Al₂O₃, the Pd/Al₂O₃-M catalyst shows higher Pd dispersion, stronger metal-support interaction, and more abundant surface-active sites. Under the reaction conditions of 60 ℃ and 1 MPa H₂, the Pd/Al₂O₃-M catalyst exhibits superior performance in the hydrogenation of isoprene, achieving a conversion of 95.2% and a total selectivity of 98.3% to semi-hydrogenated isoamylenes. In the anthraquinone hydrogenation reaction, it reaches a hydrogenation efficiency of 15.8 g/L, representing a 27.4% enhancement over the reference catalyst. This study demonstrates that rational modulation of carrier morphology can significantly improve the performance of Pd catalysts in various hydrogenation reactions, providing a promising strategy for designing highly efficient hydrogenation catalysts.

To investigate influence of mixing modes on integrated process of co-pyrolysis of coal and biomass with CO₂ reforming of methane (CP-CRM), Naomaohu coal (NMH) and elm (ELM) were chosen and three mixing modes (NMH/ELM, ELM/NMH and Blends) were examined over Ni-based reforming catalysts prepared by ball milling, and compared with co-pyrolysis under N₂ atmosphere (CP-N₂). The results show that the products distribution was significantly affected by the mixing mode. Tar yield during CP-CRM under Blends model was higher than those of NMH/ELM and ELM/NMH, increasing by 35.29% compared with CP-N₂. Meanwhile, light oil content in the tar was higher than those of NMH/ELM and ELM/NMH, but the pitch content was opposite. Phenols content in tar from Blends model was 19.52% higher than that of CP-N₂, along with more free radicals in tar than that of CP-N₂, which was mainly ascribed to the enhanced heat and mass transfer between raw material particles by mechanical mixing, making the co-pyrolysis process more complete. At the same time, the mechanical mixing was conducive to more efficient action of hydrogen-rich free radicals (such as ·H, ·CH_x) on pyrolysis products, suppressing the secondary cracking and polymerization. The results provide a good guidance for regulating tar yield and compositions of the co-pyrolysis process.

Co-pyrolysis of oil-rich coal and biomass is an effective approach to maximize the oil and gas production from oil-rich coal. To address the challenge of unclear mechanisms for the enhancement of synergistic effects during the co-pyrolysis of oil-rich coal and biomass, a Huangling coal (H) and an enzymatic hydrolysis lignin (E) were used as the research samples and the structural evolution of raw materials and those by hydrothermal pretreatment (HTP) was systematically investigated using a suite of techniques such as proximate analysis, ultimate analysis, scanning electron microscopy (SEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and nuclear magnetic resonance (¹³C-NMR). Combined with fixed-bed pyrolysis experiments, the mechanism by which hydrothermal pretreatment strengthens the co-pyrolysis synergistic effect of the Huangling coal and enzymatic hydrolysis lignin blend was explored. The results indicate that after hydrothermal pretreatment, the oxygen content of the raw materials decreases, the pore structure becomes more developed, and the concentrations of inorganic metal ions (e.g., calcium, potassium, and iron) in the aqueous phase increase. The structure of Huangling coal and enzymatically hydrolyzed lignin undergoes significant modification, with the contents of aliphatic carbon, aromatic carbon and carbonyl/carboxyl carbon in enzymatically hydrolyzed lignin approaching those in Huangling coal, and with the bridge carbon ratio increasing, resulting in improved thermal stability for the enzymatically hydrolyzed lignin and a pyrolysis temperature approaching that of Huangling coal. By the hydrothermal pretreatment, the co-pyrolysis of Huangling coal and enzymatic hydrolysis lignin generally exhibit an increase in tar yields. When the H/E ratio is 8∶2 and hydrothermal pretreatment is conducted for 24 h, the co-pyrolysis tar yield increases by 80.52%, with significant increases in the contents of aliphatic compounds and monocyclic aromatic hydrocarbons in the tar. Meanwhile, the yields of H₂, CO and CH₄ in the gas increase by 5.47%, 10.98% and 9.27%, respectively, the generation of CO₂ and pyrolysis water is inhibited, and the pore structure of semi-coke is enriched. This is primarily attributed to the multiple mechanisms of “component interaction-structural modification-catalytic cracking” during hydrothermal pretreatment, which enhance the co-pyrolysis synergistic effect of the H/E blend. The findings provide theoretical support for developing the technologies to enhance the co-pyrolysis synergistic effect between oil-rich coal and biomass, and expand new avenues for the low-carbon, high-quality utilization of oil-rich coal.

Ni/Al₂O₃ is regarded as one of the most promising catalysts for industrial application in CO₂ methanation, but is still plagued by issues of inadequate low-temperature activity and thermal sintering. In response to these challenges, an Ni/CaO-ZrO₂-Al₂O₃ catalyst with high low-temperature activity and robust high-temperature sintering resistance was prepared by introducing Ca and Zr promoters. Under the reaction conditions of 250 °C and a space velocity of 30000 mL/(g·h), the CO₂ conversion and methane space-time yield reached 96% and 257.5 mmol/(g·h), respectively. In addition, the Ca-Zr dual-promoted Ni/CaO-ZrO₂-Al₂O₃ catalyst exhibited a smaller increase in the Ni particle size and less activity loss than the Ca-promoted catalyst in a 200 h aging test at 600 °C. The Ca and Zr promoters can not only improve the Ni dispersion but also enhance the surface basicity, resulting in excellent low-temperature activity. Moreover, the Zr promoter suppresses the transformation of Ca species into CaCO₃ through solid-phase reaction under operating conditions, thereby inhibiting Ni sintering and ensuring high-temperature stability. This work provides a new promoter design strategy for the development of high-performance Ni-based catalysts for CO₂ methanation.

Aldehydes and ketones, valuable oxygen-containing organic intermediates, play a fundamental role in the synthesis of fine chemicals, fuels and materials. Renewable carbon resources, represented by lignocellulosic biomass, enable the green production of platform carbonyl compounds such as furfural, 5-hydroxymethylfurfural, and low-molecular-weight aliphatic ketones via pyrolysis. This approach is of great significance for mitigating dependence on fossil resources and reducing carbon emissions. This review provides a systematic overview of recent progress in the catalytic pyrolysis of biomass for aldehyde and ketone production. First, the structural features, types, and biomass-derived origins of typical carbonyl platform molecules are summarized. Second, the decomposition pathways and intermediate evolution behaviors of cellulose-rich, hemicellulose-rich, and lignin-rich biomasses under non-catalytic pyrolysis conditions are compared, clarifying the influence of multicomponent synergistic effects on aldehyde and ketone formation. On this basis, particular emphasis is placed on the mechanistic roles and dominant reaction pathways of metal salts, metal oxides, and carbon-based catalytic systems in regulating key steps such as dehydration, decarbonylation, C−O/C−C bond cleavage, and skeletal rearrangement. Finally, the main challenges in biomass catalytic pyrolysis toward aldehydes and ketones are analyzed, including unclear catalyst structure-activity relationships, inadequate active site stability, and limited product selectivity. Future perspectives are proposed regarding the rational design of multilevel structured catalysts for efficient and controllable conversion, the integration of in situ characterization with multiscale simulation to elucidate reaction mechanisms, and the development of green scale-up and process integration strategies. This work aims to provide a systematic theoretical reference and research guidance for the high-value utilization of biomass and the conversion of renewable carbon resources.

Para-xylene (PX), as a pivotal chemical feedstock, plays an indispensable role in ensuring nation energy strategic security and propelling the low-carbon and green development of the chemical industry. The review systematically summarizes the recent advancements in catalysts for the direct conversion of syngas into p-xylene-enriched aromatics, focusing on three distinct catalytic systems: the Fischer-Tropsch synthesis catalyst/zeolite coupling system, the methanol synthesis catalyst/zeolite synergistic system, and the dual engine driven/zeolite catalytic system. Through a comprehensive and in-depth analysis of critical parameters, including the electronic structure features of active components, the synergistic action mechanism of promoters, and the pore topology of zeolite within each catalytic system, the governing principles of catalytic activity, selectivity, and stability are thoroughly revealed. Simultaneously, based on the reaction intermediate evolution pathways, the reaction mechanisms involving olefin, methanol, and olefin-methanol dual intermediate routes are systematically explored. The current scientific bottlenecks confronted by the catalyst systems, such as the intricate challenge of achieving coordinated optimization of activity and stability, and the lack of clarity in the regulatory mechanism of PX directional selectivity, are meticulously expounded. Building upon these identified issues, prospective research directions are comprehensively summarized.

This study systematically investigated the CO adsorption behavior and electron transfer mechanism on Pt_n/γ-Al₂O₃ catalysts using density functional theory (DFT) calculations. Combined with infrared vibrational spectroscopy (FT-IR), electron difference density (EDD) and charge decomposition analysis (CDA), the authors revealed how Pt cluster size regulated CO adsorption configuration, electron transfer, and C−O bond vibrational frequency. The results show that small Pt₄ sub-nanometric clusters, due to their highly coordinated unsaturated Pt atoms, have strong d-electron feedback, resulting in full filling of CO’s π* antibonding orbitals, a significant weakening of the C−O bond, and a redshift in the IR frequency. Large Pt₁₃ sub-nanometric clusters, due to their dense structure, experience electron delocalization, weaken feedback, enhance C−O bonding, and have a blueshift in the IR frequency. The electron transfer intensity increases in linear, bridge, and multi-terminal adsorption, respectively. Bridge adsorption is most sensitive to size, with an IR blueshift of 81 cm⁻¹ observed when the number of Pt atoms increases from 4 to 13. Multi-terminal adsorption exhibits a stable frequency due to a “saturation effect”. This study establishes a comprehensive correlation among Pt size, electronic structure, adsorption properties, and infrared response, elucidating the CO adsorption mechanism on Pt-based catalysts and providing atomic-scale theoretical guidance for the design of efficient catalysts.

Hydrogen as the energy carrier is a promising solution to mitigate the environmental issues associated with the use of fossil fuels. Efficient and inexpensive electrocatalysts for oxygen evolution in alkaline media are crucial for advancing the widespread application of alkaline water electrolyzers for hydrogen generation. Transition metal phosphides are promising candidates as the (pre-)catalysts for electrocatalytic oxygen evolution reactions. This dataset compiles and compares the electrocatalytic oxygen evolution reaction activity of nickel- and cobalt-based phosphides. The metal phosphides reported were synthesized using solvothermal phosphidization or electrodeposition methods, and the oxygen evolution activities of these phosphides were evaluated using linear sweep voltammetry in 1 mol/L KOH. Besides, cyclic voltammetry and electrochemical impedance spectroscopy were performed on these metal phosphides. The total volume of this dataset is 14.5 MB, comprising 312 files. It serves as a valuable reference for the design of active metal phosphide-based materials for electrocatalysis.

Catalytic cracking of gasoline and diesel to produce olefins is crucial for the high-value utilization of surplus fuels. This process typically employs zeolite catalysts. In order to reveal the effects of zeolite type and acidic properties on the catalytic cracking performance for the diesel model compound dodecane, SAPO-34, ZSM-5-38 (SiO₂/Al₂O₃ ratio of 38, the same below), ZSM-5-85, ZSM-5-200 and USY were taken as research subjects. These zeolites were characterized by X-ray diffraction, scanning electron microscope, N₂ physical adsorption, NH₃-temperature programmed desorption and pyridine adsorption Fourier-transform infrared spectroscopy, and their catalytic cracking performance was systematically evaluated on a fixed-bed reactor. Results indicated that the zeolite type was the primary determinant of dodecane conversion and product distribution. SAPO-34, with a 0.38 nm pore size, exhibited low catalytic activity, achieving a dodecane conversion of 24.33% and nearly zero BTX aromatics yield. Although SAPO-34 showed high light olefins selectivity, severe coking occurred on its external surface. In contrast, ZSM-5-38, with a moderate pore size and acid amounts, demonstrated excellent catalytic activity, achieving nearly 100% dodecane conversion. Its liquid products were predominantly BTX aromatics, with the relatively highest light olefins yield of 18.40% and minimal coke yield of 0.18% among the three different zeolites. USY, featuring the largest pore size, also fully converted dodecane but primarily produced light alkanes and coke. Secondly, based on the identified zeolite type, adjusting the acidic properties could further refine product distribution. Experimental data indicated that the number of acid sites in ZSM-5, especially the Brønsted acid sites, decreased as the SiO₂/Al₂O₃ ratio increased. Among ZSM-5 with different acidic properties, ZSM-5-200 showed superior catalytic cracking performance for dodecane, achieving a total gas product yield nearing 65% and a conversion of 97.79%. Additionally, the yields of ethylene, propylene and butene rose to 11.11%, 20.33% and 10.49% respectively, while maintaining a low coke yield of 0.43%. Finally, based on the above findings, the reaction pathway and regulation mechanism of dodecane catalytic cracking were proposed, including cracking, hydrogen transfer, oligomerization, aromatization and coking. The zeolite type and its acidic properties significantly influenced the conversion and product distribution by modulating the relative strength of these reactions. This study elucidates the structure-activity relationship between zeolite type, acidic properties and catalytic performance, enhances the understanding of catalytic reaction mechanisms and guides the optimization of gasoline and diesel catalytic cracking processes toward olefins production.