Enhanced methanol formation in CO2 hydrogenation through synergistic copper and gallium interaction

Abstract

Methanol production from CO2 hydrogenation has attracted great attention, due to the demand for carbon neutralization. Ga-promoted Cu catalysts show promising properties for methanol formation in CO2 hydrogenation, urging a fundamental investigation of the active state. In this study, we synthesized CuGa species on mesoporous SiO2, varying the amount of Ga. The structural characterizations revealed that Ga existed mostly in highly dispersed GaOx species with Cu in the form of metallic Cu clusters. The addition of Ga significantly increased the methanol formation with an optimum Ga value compared to Cu and Ga on SiO2. The surface-sensitive measurements showed the mixed form of Cu+ and Cu0 on the Cu surface exhibited, where the Cu+ state was proportional to the methanol formation rate. Therefore, we conclude that the Cu+-GaOx interface constitutes an active site for methanol production. Furthermore, we found that the Ga addition influences the oxidation state and dispersion of Cu.