A new catalytic process for the synthesis of para-xylene through benzene methylation with CH3Br

A new process for the generation of para-xylene (p-xylene) through benzene alkylation with CH3Br has been proposed for the first time. CH3Br is prepared by the catalytic bromination of methane (the main component of natural gas), and benzene can be prepared from methane dehydroaromatization. Over the optimized P2O5-ZnO/HZSM-5 catalyst, benzene conversion is 43.6% and p-xylene selectivity is 91.2% at 475 degrees C, and the molar ratio of p-xylene in the liquid product is 28.7%. The relationship between the acidity and the catalytic efficiency of the modified H-ZSM-5 samples was investigated. It is found that isomerization of p-xylene occurs on the strong acid sites rather than on the weak acid sites, and benzene conversion is subject to the influence of strong acid sites. (C) 2014 Elsevier B.V. All rights reserved.