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. CH ₃Br 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 °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.