Preparation of MgO/MCM-22 catalysts by a novel two-step impregnation and their shape-selective performance in the synthesis of p-xylene

•MgO/MCM-22 catalysts were prepared by a novel two-step impregnation method.•The coverage of external acid sites and the adjustment of pore size of zeolite were achieved.•Excellent para-selectivity in alkylation of toluene with DMC was realized.

Shape-selective catalysts of MgO/MCM-22 were prepared by a novel two-step impregnation method and evaluated in the catalytic synthesis of p-xylene by alkylation of toluene with dimethyl carbonate. The two-step impregnation process combines the advantages of general impregnation and complexation impregnation for the preparation of metallic-oxide modified zeolite shape-selective catalysts. The coverage of the acidic sites on the external surface of the zeolite and the adjustment of the pore size of the zeolite can be achieved by two-step impregnation. Consequently, significant improvement in selectivity for p-xylene over the MgO/MCM-22 catalyst was realized.

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