Temperature-Dependent Microstructural Evolution of Seed-Assisted Low-Template ZSM-5 and Its Catalytic Behavior in Benzene Alkylation with Methanol.

Low-cost synthesis of ZSM-5 zeolite is critical for its large-scale industrial application. Herein, a seed-assisted low-template hydrothermal route was employed to fabricate ZSM-5 zeolites. The regulatory effects of gradient crystallization temperatures on the crystallization kinetics, morphology, pore structure and acid properties of ZSM-5 were systematically investigated, and the structure-activity relationship linking temperature-driven evolution and catalytic behavior in benzene alkylation with methanol was established. The results reveal that increasing the crystallization temperature shortens the amorphous induction period, facilitates framework aluminum (Al) incorporation and increases the concentration of Brønsted acid sites. Meanwhile, crystallization temperature modulates the specific surface area and intercrystalline mesopore volume, thereby tuning the accessibility of acid sites and the mass transfer efficiency of reactants and products. The sample synthesized at a moderate temperature of 170 °C achieves an optimal balance between textural properties and acid concentration. Benefiting from its large specific surface area, abundant intercrystalline mesopores and high Brønsted acid concentration, the catalyst affords a benzene conversion of 69.1% and a methanol utilization of 79.1%, and maintains stable operation over 135 h on stream. The temperature-dependent regulation insights uncovered in this work facilitate low-cost synthesis of ZSM-5 and rational design of high-performance catalysts for aromatic alkylation.