CO2 hydrogenation to methanol over partially embedded Cu within Zn-Al oxide and the effect of indium

Abstract

Developing effective catalysts for CO2 hydrogenation to methanol is an important step to improve the efficiency of a promising process for green synthesis of fuels and chemicals. Optimizing the Cu dispersion is often the main goal in preparing Cu/ZnO-based catalysts due to the strong dependence of the catalytic activity on the Cu surface area. However, the catalytic properties are also related to the nature of the Cu-ZnO interface. Herein, a series of hydrotalcite-derived Cu/ZnO/Al2O3 catalysts were prepared for CO2 hydrogenation to methanol. The preparation method results in partially embedded Cu particles within the Zn-Al oxide matrix. This microstructure exhibits significantly enhanced intrinsic activity and methanol selectivity. Loss of the interfacial area between Cu and Zn-Al mixed oxide phase due to sintering of Zn-Al matrix is identified as the main reason for deactivation of the HT-derived catalysts. The influence of In on Cu/ZnO-based catalysts is also investigated. It is found that In decreases the activity but increases the methanol selectivity and stabilizes the Cu particles and the Zn-Al mixed oxide phase. The lower activity of the In-containing catalysts is linked to the inhibition of Cu active sites by CuxIny species.