Coke-resistant (Pt + Ni)/ZSM-5 catalyst for shape-selective alkylation of toluene with methanol to para-xylene

Abstract

Shape-selective alkylation of toluene with methanol is one of the most attractive promising synthetic routes to para-xylene. To date, modified ZSM-5 zeolites are considered to be one of the best candidate catalysts for this reaction. Although the para-selectivity could be tuned to approaching 100% by modification of the zeolite and optimization of reaction conditions, at present, there is still a lack of effective means to inhibit the rapid deactivation of the catalysts due to coke formation. In this work, a coke-resistant (Pt + Ni)/ZSM-5 zeolite with excellent stability for shape-selective alkylation of toluene with methanol to para-xylene is developed. The pore structure and acid properties of the zeolite are effectively tuned to ensure high para-selectivity. Meanwhile, the co-existence of Pt and Ni species in this catalyst plays the critical role in inhibiting coke formation, as the two species concurrently impede the formation of olefins, the main coking precursors, via two distinctive mechanisms.