The synergetic effect of Pd, In and Zr on the mechanism of Pd/In2O3–ZrO2 for CO2 hydrogenation to methanol

Abstract

The hydrogenation of CO₂ to methanol is of great significance from both the environmental and economic points of view. The excellent performance of Zr-doped or Pd-supported In₂O₃ catalysts has been reported in recent years. However, the mechanism of CO₂ hydrogenation in the coexistence of Pd, In and Zr is unclear. In this paper, the density functional theory method has been used to explore the synergistic relationship between In₂O₃, Pd and ZrO₂. The mechanism of methanol synthesis on the surface of the Pd/In₂O₃–ZrO₂ catalyst has been studied. The results show that ZrO₂ doping can increase the content of O atoms on the surface of In₂O₃, optimize the surface structure of In₂O₃, and strengthen the adsorption strength of CO₂ molecules on the surface of In₂O₃. In addition, ZrO₂ doping can reduce the bonding strength of the metal Pd cluster on the surface of In₂O₃, thereby inhibiting the formation of a PdIn alloy to maintain the efficient dissociation activity of metal Pd for H₂. Both the HCOO route and the COOH route are important pathways for the synthesis of methanol by hydrogenation of CO₂ molecules on the surface of the Pd/In₂O₃–ZrO₂ catalyst, and the H₂CO hydrogenation reaction is a key step in methanol synthesis.