Synergistic Effect of Copper and Indium Species for Highly Selective CO2 Hydrogenation to Methanol

CO2 hydrogenation to methanol over Cu-based catalysts faces challenges such as low methanol selectivity and poor stability. Here, we report a series of CuIn bimetallic catalysts with different Cu/In ratios prepared by the coprecipitation method. Among them, the methanol selectivity of Cu25In75 reaches as high as 92.5% at 200 degrees C and 64.5% at 260 degrees C, which is 1.3 times and 1.9 times higher than that of the commercial catalyst at 200 and 260 degrees C, respectively. Moreover, Cu25In75 exhibits high stability for 200 h time-on-stream at 260 degrees C. The high selectivity originates from a strong interaction between Cu species and In2O3-x with oxygen vacancies. On the interface between Cu and In2O3-x, dispersed Cu is the main contributor to the activation and dissociation of H-2, while the oxygen vacancies in In2O3 adsorb and activate CO2. During the reaction, the abundance of hydrogen facilitates the reduction of the In2O3 surface, promoting the generation of surface oxygen vacancies and providing the necessary hydrogen for the hydrogenation reaction. Our research unveils a promising synergistic strategy for the rational design and application of Cu-based catalysts in CO2 hydrogenation, offering avenues for further exploration and advancement in this field.