Cumene disproportionation over zeolite β

Abstract

Two methods, silica deposition and steam pretreatment, have been developed to improve the catalytic stability of zeolite β for cumene disproportionation. It was found that deactivation resulted from coke formation deposited on the zeolite pore mouths. Two different mechanisms for these two stabilization methods are proposed. Steam pretreatment enhances the acid strength and results in the reduction of coke formation. Nevertheless, Si (OC₂H₅)₄ can only deposit and decompose on the sites at the external surface and/or near the pore mouth. Accordingly, pore mouth coking is eliminated.