Selective Synthesis of para-Xylene in the Alkylation of Toluene via Regulation of MgO Location in Co-modification Over HZSM-5

The alkylation of toluene catalyzed by modified HZSM-5 was an economical and efficient way to produce para-xylene (PX) due to the full utilization of toluene and fewer by-products. It has attracted significant attention in optimizing the modification method for both high activity and PX selectivity. In this study, we employed SiO2 and MgO to co-modify HZSM-5 for the alkylation of toluene with dimethyl carbonate. The catalysts in which SiO2 was deposited first with trimethoxysilane (TMOS) as the precursor, showed significantly higher activity and PX selectivity than that of depositing MgO first. When the content of SiO2 and MgO was both 5