Synergistic effects of ZnO–ZrO2@SAPO-34 core-shell catalyst in catalyzing CO2 hydrogenation for the synthesis of light olefins

Abstract

As a method for valorizing CO2 emissions, hydrogenation of CO2 into olefins remains viable. Herein, ZnO–ZrO2 and SAPO-34 were prepared and used as bifunctional catalysts in light olefins synthesis through CO2 hydrogenation. The combination of the two components includes layered filling, physically mixing, physically grinding, and core-shell composite. Based on the evaluation, different combinations resulted in diverse product distributions. ZnO–ZrO2@SAPO-34 core-shell catalysts are better suited for promoting synergistic effects, which facilitate light olefin production. Due to the unique core-shell structure, appropriate weak acidity, and moderate basicity, the light olefins selectivity was enhanced. Further, the calcination time and core-shell mass ratio were optimized over the ZnO–ZrO2@SAPO-34 core-shell catalyst to investigate the synergistic effects between catalytic structure and catalytic performance. With a 3:1 core-shell mass ratio and 3 h of calcination at 550 °C, the optimal ZnO–ZrO2@SAPO-34 (3:1) catalyst was obtained, which exhibited 73% selectivity to light olefins with CO2 conversion of 16.1%, whereas the selectivity of CO and CH4 was lower than 44% and 1.5%, respectively. This study provides new insights into the design and optimization of ZnO–ZrO2@SAPO-34 core-shell catalysts for CO2 hydrogenation and synthesis of light olefins.