Novel-ordered hierarchical ZSM-5 zeolite with interconnected macro–meso–microporosity for the enhanced methanol to aromatics reaction

Abstract

The methanol to aromatics (MTA) process is an attractive non-petroleum route to produce high-value aromatics but suffers from a high rate of carbon deposition and deactivation and relatively low BTX selectivity. Herein, we first prepared a three-dimensional ordered macro–mesoporous carbon material (3DOMmC) with a network structure by dropping-suction filtration. Then the obtained 3DOMmC was utilized as a hard template to synthesize the ordered hierarchical ZSM-5 zeolite with interconnected macro–meso–microporosity by bottom-up confined steam-assisted crystallization. Compared with the conventional microporous ZSM-5, the BTX selectivity and lifetime of the ordered hierarchical ZSM-5 zeolite (3DOMmC-Z5) have been greatly improved from 18.02% to 24.01% and 6.5 h to 8 h, respectively, due to the highly ordered and fully interconnected intercrystalline porous hierarchy. After that, we in situ introduced Zn into the synthesized ZSM-5 zeolite, and the BTX selectivity of 3DOMmC-Zn-Z5-0.5 was significantly improved from 24.01% to 29.9% along with a comparable lifetime (from 9 h to 8 h), which is still longer than 6.5 h for conventional catalysts. These findings mark the significance of precise tailoring of ordered hierarchical Zn-ZSM-5 zeolites with interconnected macro–meso–microporosity for enhanced catalytic conversion and product selectivity, excellent long-term catalytic stability, low coke formation in the methanol to aromatics reaction.