Currently, the conversion of waste plastics into high-value products via catalytic pyrolysis enables the advancement of plastics’ open-loop recycling. However, enhancing selectivity remains a critical challenge. This study introduces a novel approach to catalytic pyrolysis, utilizing a combination of MCM-41 and modified gallium-based HZSM-5 catalysts, to achieve exceptional selectivity for aromatic liquid-phase products from linear low-density polyethylene. Firstly, to enhance the probability of dehydroaromatization optimization, the type and proportion of metal active sites within the HZSM-5 catalyst are fine-tuned, which would establish equilibrium with acid sites, resulting in a remarkable 15.72% increase in the selectivity of aromatic hydrocarbons. Secondly, to enhance the accessibility of volatiles to active sites, mesoporous MCM-41 with cracking capabilities is introduced. The doping ratio of MCM-41 is meticulously controlled to facilitate the diffusion of cracked volatiles to the active centers of modified gallium-based HZSM-5, enabling efficient reforming reactions. Experimental findings demonstrate that MCM-41 significantly enhances the dehydroaromatization activity of the modified gallium-based HZSM-5 catalyst. Under the influence of MCM-41:Zr₂Ga₃/HZSM-5 = 1:2 catalyst, the selectivity for aromatic hydrocarbons reaches an impressive 93.11%, with a notable 60.01% selectivity for benzene, toluene, ethylbenzene, and xylene. Lastly, this study proposes a plausible pathway for the generation of high-value aromatic hydrocarbons using the combined catalyst.

With the advantages of low raw material cost and 100% atom utilization, the synthesis of high value-added chemical product cyclic carbonates by the cycloaddition of CO₂ to epoxides has become one of the most prospective approaches to achieve the industrial utilization of CO₂. In the reported catalytic systems, the complexity of the catalyst synthesis process, high cost, separation difficulties, and low CO₂ capture limit the catalytic efficiency and its large-scale application. In this paper, Ag nanoparticles loaded on polyethyleneimine (PEI)-modified UiO-66-NH₂ (Ag/PEI@UiO-66-NH₂) are successfully synthesized by in situ immersion reduction. The Ag nanoparticles and the amino groups on the surfaces of PEI@UiO-66-NH₂ contribute to the adsorption of CO₂ and polarization of C–O bonds in epoxides, thereby boosting the conversion capability for the CO₂ cycloaddition reaction. At the amount of propylene oxide of 0.25 mol and the catalyst dosage of 1% of the substrate, the yield and selectivity of propylene carbonate are up to 99%. In addition, the stability and recyclability of Ag/PEI@UiO-66-NH₂ catalyst are attained. The Ag/PEI@UiO-66-NH₂ catalyst also demonstrates a wide range of activity and distinctive selectivity toward cyclo-carbonates in the cycloaddition of CO₂ to epoxides. This work provides a guide to designing a highly efficient catalyst for in situ capture and high-value utilization of CO₂ in industrial applications.

Herein, we introduced a nitrogen-alkali lignin-doped phenolic resin (N@AL_nPR) to produce palladium nanoparticles through an in situ reduction of palladium in an aqueous phase, without the need for additional reagents or a reducing atmosphere. The phenolic resin nanospheres and the resulting palladium nanoparticles were extensively characterized. Alkali lignin created a highly conducive environment for nitrogen incorporation, dispersion, reduction, and stabilization of palladium, leading to a distinct catalytic performance of palladium nanoparticles in vanillin hydrodeoxygenation. Under specific conditions of 1 mmol of vanillin, 40 mg of catalyst, 1 MPa H₂, 90 °C, and 3 h, the optimized Pd/N@AL₃₀PR catalyst exhibited a nearly complete conversion of vanillin, 98.9% selectivity toward p-creosol, and good stability for multiple reuses. Consequently, an environmentally friendly lignin-based catalyst was developed and used for the efficient hydrodeoxygenation conversion of lignin-based platform compounds.

Separating monomeric cycloalkanes from naphtha obtained from direct coal liquefaction not only facilitates the valuable utilization of naphtha but also holds potential for addressing China’s domestic chemical feedstock market demand for these compounds. In extractive distillation processes of naphtha, relative volatility serves as a crucial parameter for extractant selection. However, determining relative volatility through conventional vapor-liquid equilibrium experiments for extractant selection proves challenging due to the complexity of naphtha’s compound composition. To address this challenge, a prediction model for the relative volatility of n-heptane/methylcyclohexane in various extractants has been developed using machine-learning quantitative structure-property relationship methods. The model enables rapid and cost-effective extractant selection. The statistical analysis of the model revealed favorable performance indicators, including a coefficient of determination of 0.88, cross-validation coefficient of 0.94, and root mean square error of 0.02. Factors such as α, E_HOMO, ρ, and logP_oct/water collectively influence relative volatility. Analysis of standardized coefficients in the multivariate linear regression equation identified density as the primary factor affecting the relative volatility of n-heptane/methylcyclohexane in the different extractants. Extractants with higher densities, devoid of branched chains, exhibited increased relative volatility compared to their counterparts with branched chains. Subsequently, the process of separating cycloalkane monomers from direct coal liquefaction products via extractive distillation was optimized using Aspen Plus software, achieving purities exceeding 0.99 and yields exceeding 0.90 for cyclohexane and methylcyclohexane monomers. Economic, energy consumption, and environmental assessments were conducted. Salicylic acid emerged as the most suitable extractant for purifying cycloalkanes in direct coal liquefaction naphtha due to its superior separation effectiveness, cost efficiency, and environmental benefits. The tower parameters of the simulated separation unit provide valuable insights for the design of actual industrial equipment.

The Fe-Mn bimetallic catalyst is a potential candidate for the conversion of CO₂ into value-added chemicals. The interaction between the two metals plays a significant role in determining the catalytic performance, however which remains controversial. In this study, we aim to investigate the impact of tuning the proximity of Fe-Mn bimetallic catalysts with similar nanoparticle size. And its effect on the physicochemical properties of the catalysts and corresponding performance were investigated. It was found that closer Fe-Mn proximity resulted in enhanced CO₂ hydrogenation activity and inhibited CH₄ formation. The physiochemical properties of prepared catalysts were characterized using X-ray diffraction, H₂ temperature programmed reduction, and X-ray photoelectron spectroscopy, revealing that a closer Fe-Mn distance promoted electron transfer from Mn to Fe, thereby facilitating Fe carburization. The adsorption behavior of CO₂ and the identification of reaction intermediates were analyzed using CO₂-temperature programed desorption and in situ Fourier transform infrared spectroscopy, confirming the intimate Fe-Mn sites contributed to CO₂ adsorption and the formation of HCOO* species, ultimately leading to increased CO₂ conversion and hydrocarbon production. The discovery of a synergistic effect at the intimate Fe-Mn sites in this study provides valuable insights into the relationship between active sites and promoters.