Catalytic performance of nano zeolite ZSM-5 for dealkylation reaction of alkylphenols

Abstract

To further enhance the dealumination reactivity and catalytic stability of zeolite, nano zeolite with reduced thickness along the b-axis were successfully synthesized via a hydrothermal method using dual templates of tetrapropylammonium hydroxide (TPAOH) and cetyltrimethylammonium bromide (CTAB), leveraging the pore structure characteristics of ZSM-5 zeolite. Compared to commercial zeolite, the b-axis thickness was reduced from 700 nm to 50-100 nm. The catalytic performance of the nano zeolite was systematically compared with hierarchical and commercial zeolite.Results demonstrated that the nano zeolite exhibited significantly improved phenol selectivity and the highest phenol yield.In terms of catalytic stability, the nano zeolite showed enhanced performance over three reaction cycles, with mixed phenol conversion rates increasing by 10%, 32%, and 17% (compared to hierarchical zeolite) and 53%, 59%, and 37% (compared to commercial zeolite), respectively. Analysis of coke deposition revealed that the hierarchical zeolite benefited from its abundant mesoporous structure, which enhanced carbon tolerance and delayed pore blockage by coke deposition. In contrast, the nano zeolite's shorter micropore channels improved molecular diffusion efficiency, preventing micropore clogging and fundamentally addressing zeolite deactivation. Additionally, the nano zeolite demonstrated superior catalytic performance and stability in the dealkylation of phenolic oil.