Controlling CO2 hydrogenation selectivity by tuning surface properties of Cu/ZnxAlyOz catalysts

Abstract

CO2 hydrogenation to methanol and/or dimethyl ether (DME) holds promise for mitigating greenhouse gas effects and addressing energy scarcity. However, the relationship between product selectivity and the collective nature of the catalysts remains ambiguous due to the intricate reaction network. Here, a series of Cu/ZnxAlyOz catalysts with different surface properties have been engineered by manipulating the Zn/Al ratio to achieve product controllability for CO2 hydrogenation. The results unveil the pivotal role of the H2 dissociation capability in governing CO2 conversion, which is regulated by the concentration of Cu0 species. Furthermore, the number of surface hydroxyl groups, the proportion of moderately strong basic sites and moderately strong acidic sites show desirable linear correlations with the selectivity of CO, CH3OH, and DME, respectively. Importantly, the ZnAl2O4-Al2O3 or Cu-ZnAl2O4-Al2O3 interface notably enhances moderately strong acidic sites, aiding methanol dehydration to DME. This work offers a comprehensive guide to the rational design of catalysts for oriented product synthesis from CO2 hydrogenation.