Shape-selective synthesis of para-xylene through tandem CO2 hydrogenation and toluene methylation over ZnCeZrOx/MCM-22 catalyst

Selective synthesis of value-added xylenes and para -xylene (PX) by CO 2 hydrogenation reduces the dependence on fossil resource and relieves the environment burden derived from the greenhouse gas CO 2 . Herein, modified MCM-22 zeolite combined with ZnCeZrO x solid solution is reported to catalyze the tandem CO 2 hydrogenation and toluene methylation reaction at a relatively low temperature (< 603 K), showing xylene selectivity of 92.4% and PX selectivity of 62% (PX/X, 67%) in total aromatics at a CO 2 conversion of 7.7%, toluene conversion of 23.6% and low CO selectivity of 11.6%, as well as giving high STY of xylene (302.0 mg·h –1 ·g cat –1 ) and PX (201.6 mg·h –1 ·g cat –1 ). The outstanding catalytic performances are closely related to decreased pore sizes and eliminated external surface acid sites in modified MCM-22, which promoted zeolite shape-selectivity and suppressed secondary reactions.