Structure–activity relationships of Cu–ZrO2 catalysts for CO2 hydrogenation to methanol: interaction effects and reaction mechanism

Abstract

A series of Cu–ZrO₂ (CZ) catalysts with different surface area, copper surface area (S_Cu), oxygen vacancy concentration, and interaction between Cu and ZrO₂ features were synthesized. The factors that could affect catalytic activity of CO₂ hydrogenation to methanol were investigated. The interaction between Cu and ZrO₂ is crucial for determining the catalytic activity. The catalyst possessing the strongest interaction between Cu and ZrO₂, exhibited the optimum catalytic activity. The evolution of carbonaceous species and pyridine adsorption over CZ catalysts were investigated using in situ DRIFT spectroscopy. It is found that the hydrogenation of formate species is a rate-limiting step and H spillover plays an important role. The hydrogenation of formate species and H spillover are strongly dependent on the interaction. These results provide a new way of understanding the activity dependence and reaction mechanism of CO₂ hydrogenation to methanol over CZ catalysts.