Green synthesis of shaped nano-ZSM-5 toward more efficient methanol-to-hydrocarbon conversion

Abstract

Commonly, in the synthesis of zeolites, calcination is necessary prior to ion exchange to remove organic templates. Herein, shaped nano-ZSM-5 was successfully prepared with the assistance of template-free nano-aggregate seed without the calcination step before ion exchange. This synthesis method dramatically increased mesopores volume compared with the one calcined prior to ion exchange. Besides, employing nano-aggregate as seed gave the synthesized ZSM-5 a markedly smaller particle size and higher yield than the one prepared with conventional silicate-1 as seed, and simultaneously accelerated the crystallization process by providing more nuclei. A possible formation mechanism of the shaped nano-ZSM-5 zeolites was proposed. The shaped nano-ZSM-5 possessed the smallest crystal size, largest mesopore volume, most acid sites and strongest acid strength, which endowed it highest catalytic activity and longest lifetime in methanol to hydrocarbons reaction. This work could attract more attention on the application of nanoscale ZSM-5 catalyst to industry.