Constructing Directional Component Distribution in Cu-Modified FAU Zeolite To Boost the Reaction of Toluene Side-Chain Alkylation

Abstract

The reaction of toluene side-chain alkylation with methanol represents a potential route to reduce the energy consumption in large-scale styrene production. In this study, we design a dual zeolite-based Cu–Cs catalytic system that constructs a catalytic enhancement path to produce styrene by leveraging the distribution of Cu–Cs sites. The reaction results demonstrate that the catalyst in the stacking model of a dual bed manner (Cu/NaX-CsX-DB) exhibits higher toluene conversion (8.1%), methanol utilization efficiency (60.2%), and styrene selectivity (84.3%), accompanied by an extended catalytic stability (>100 h), than conventional Cu-modified CsX (Cu/CsX) and parent CsX catalysts. The excellent catalytic performance is realized on the basis of the triple functions of the optimal catalyst: (i) the introduction of Cu sites and the original Cs sites synergistically facilitates the dehydrogenation of methanol to formaldehyde, thereby improving the utilization of methanol; (ii) meanwhile, the introduced Cu species act as a new Lewis acid site, which modulate the surface Lewis acid-base pairs; (iii) the oriented component distribution in the Cu/NaX-CsX-DB catalyst greatly promotes the transfer of the HCOO* intermediate and provides a directional spatial pathway to improve the reaction efficiency of toluene and methanol to styrene.