Cu-Ga3+-doped wurtzite ZnO interface as driving force for enhanced methanol production in co-precipitated Cu/ZnO/Ga2O3 catalysts

A detailed understanding of the interactions among the active components in gallium promoted Cu/ZnO catalysts, depending on the speciation of the gallium, are reported using in situ/operando spectroscopic studies, and their effect in the CO2 hydrogenation to methanol unraveled. In this contribution, the promoting effect of Ga3+-doped in the wurtzite ZnO lattice of a Cu/ZnO/Ga2O3 catalyst is compared to that of a zinc gallate (ZnGa2O4) phase. Remarkably, a strong inhibition of CO formation, together with an enhanced methanol formation, are observed in the Ga3+-doped ZnO sample, specifically at conditions where the competitive reverse water gas shift reaction predominates. The catalytic performance has been correlated with the microstructure of the catalyst where a surface enrichment with reduced ZnOx species, together with the stabilization of positive charged copper species and an increase in the amount of surface basic sites for CO2 adsorption are observed on the most selective sample.