ZSM-22 zeolites were synthesized using different structure-directing agents (SDAs) with varying alkyl chain lengths, including n-alkyldiamines (DAB, DAH, DAO, and DAD) and lauryl amine (LA). The characteristics of the resulting samples (denoted as “Z-SDA”) revealed that optimal elongation of SDA alkyl chains brought about a decrease in crystallization time while retaining ZSM-22 crystal phase stability. The morphology and acidity of the samples varied as the alkyl chain length of the SDAs increased. The average crystal length ranged from 13 μm to 250 nm, and the total acid content showed a downward trend, while each sample possessed nonlinear acid site distributions. Additionally, ZSM-22-supported Pt catalysts were obtained and probed using the n-hexadecane hydroisomerization process. It was found that the activity and i-hexadecane selectivity gradually increased with the alkyl chain length of the SDAs (C4–C10). Notably, Pt/Z-DAD achieved >70% yield under specific reaction conditions, which could be attributed to the abundant mesopore network and high proportion of weak Brønsted acid site distributions.

This study explores the aerobic Baeyer-Villiger oxidation of cyclohexanone into ε-caprolactone using metalloporphyrin and benzaldehyde, a greener process to replace hazardous concentrated peroxyacid. The reaction mechanism involves a series of free radical reactions, identified through in-situ EPR. In this complex three-component reaction, we developed an intrinsic kinetic model based on the proposed mechanism. Utilizing a hyperbolic equation, the model well fits experimental data, describing biomimetic catalytic behavior of the aerobic Baeyer-Villiger oxidation. The reaction orders for the three reactants corroborate the kinetic model, with the activation energy of oxygen (130.27 kJ/mol) surpassing cyclohexanone (94.85 kJ/mol) and benzaldehyde (40.73 kJ/mol), implying slow initial oxygen activation while rapid subsequent benzaldehyde oxidation, making oxygen transfer and activation key steps. This unified approach to elementary reaction, mechanism, and intrinsic kinetics provides robust forecasts and lays the groundwork for additional studies, such as side reactions control and mass transfer enhancement and reactor design.

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The effects of Ti modification on the structural properties and catalytic performance of vanadia on hexagonal mesoporous silica (V-HMS) catalysts are studied for selective methanol-to-dimethoxymethane oxidation. Characterizations including N2 adsorption–desorption (SBET), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS UV-Vis), Micro-Raman spectroscopy, FTIR spectroscopy, and H2 temperature-programmed reduction (H2-TPR) were carried out to investigate the property and structure of the catalysts. The results show that Ti can be successfully incorporated into the HMS framework in a wide range of Si/Ti ratios from 50 to 10. Ti modification can effectively improve the distribution of vanadium species and thus enhance the overall redox properties and catalytic performance of the catalysts. The catalytic activity of the V-Ti-HMS catalysts with the Si/Ti ratio of 30 is approximately two times higher than that of V-HMS catalysts with comparable selectivity. The enhanced activity exhibited by the V-Ti-HMS catalyst is attributed to the improved dispersion and reducibility of vanadium oxides.

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The stability of catalysts perhaps is the most important issue for catalysis whatever fundamental or application. This study evaluates the stability of MnOx-CeO2 catalysts in the oxidation of ethyl acetate by comparing the performance of fresh catalysts with those treated under high-temperature hydrothermal conditions (750 ℃ and 5% steam for 12 h). Three different methods, namely redox-precipitation (RH), co-precipitation (CP), and impregnation (IP), were used to synthesize the catalysts and adjust the Mn-Ce dispersion. The activity difference between the fresh and treated catalysts decreased in the following order: RH-MnCe > CP-MnCe > IP-MnCe. Based on detailed characterizations and density functional theory calculations, the molecular dispersion of MnCeOx in RH-MnCe is key to ensuring the collapse resistance of Ce-doped Mn3O4, which yields the highest activity during ethyl acetate oxidation. This finding is supported by experiments conducted on RH-MnCe with different Mn/Ce ratios. Although the introduction of Ce can enhance the stability of Mn3O4, it must be carefully controlled at a moderate level to enable recycling between MnO2/Mn3O4.