Shape-Selective Alkylation of Toluene with Dimethyl Carbonate into p-Xylene Over MgO/MCM-22 Prepared by a Novel Pre-impregnation Method

The MgO/MCM-22 catalysts were prepared by a novel pre-impregnation method and their catalytic performances for the shape-selective alkylation of toluene with dimethyl carbonate into p-Xylene were investigated. Characterization results indicated that the Brønsted acid sites on the external surface of MCM-22 were efficiently covered by the as synthesized MgO without influencing the inner acidic sites in the sinusoidal channels and the internal pore entrance was efficiently adjusted by the pre-impregnation method. The as prepared MgO/MCM-22(PI) catalysts exhibited comparative para-selectivity but much higher toluene conversion than those over MgO-modified MCM-22 catalysts by general impregnation. The 10% MgO/MCM-22(PI) catalyst exhibited the best shape-selective performance for the highly uniform dispersion of the as synthesized MgO. Graphical Abstract