Ethylbenzene Production via Benzene Alkylation: Tailoring Diffusion and Acidity in ZSM-5 Zeolite Nanosheets

A clear understanding of the structure–acidity–activity relationship is a crucial prerequisite for designing efficient catalysts for benzene alkylation with dilute ethylene to produce ethylbenzene. This study systematically investigates the application of ZSM-5 zeolite nanosheets (NSs) with short b-axis thickness and tailored acid properties in this reaction. Comprehensive physiochemical studies demonstrate that ZSM-5 NSs have significant structural advantages, including shortened straight channel lengths, enhanced specific surface areas, and increased mesopore volumes. These structural features substantially facilitate the diffusion of reactants and products and improve the accessibility and utilization efficiency of acid sites, thereby enhancing catalytic reactivity, inhibiting side reactions, and reducing coke formation. Moreover, the adjustment of Si/Al ratios and the incorporation of framework iron species enable the optimization of the acid concentration and acid strength (especially the strong acid sites) of zeolite, thus endowing the catalysts with proper acidity, consequently showing a strong inhibition effect on the side reactions, such as the isomerization, cracking, and deep alkylation of ethylbenzene. This work not only elucidates the critical relationship between physicochemical properties and alkylation activity but also successfully develops high-performance alkylation catalysts.