Regulating Al distribution of ZSM-5 by Sn incorporation for improving catalytic properties in methanol to olefins

Abstract

Regulating Al distribution of zeolite is an efficient strategy to enhance its catalytic performance of methanol to olefins (MTO). Herein, controlling spatial and framework Al distribution of ZSM-5 by Sn was firstly investigated. Incorporation of Sn has little impact on the morphology, texture properties, Brønsted acid strength and amount of ZSM-5, but causes a more homogeneous Al spatial distribution, as confirmed by EDS and XPS results. 27Al MAS NMR and 1-hexene cracking probe tests reveal that introduction of Sn leads to an increase in the amount of Al atoms located at 10R straight channels. This fine regulation of Al distribution by Sn is adverse to the aromatic-based cycle, thus generating less aromatics and coke species, as confirmed by in situ DR UV–vis for MTO, GC–MS and TGA results. As a result, the Sn-containing catalysts show a higher propene selectivity and catalytic stability in MTO.