Theoretical study of the promotional effect of ZrO2 on In2O3 catalyzed methanol synthesis from CO2 hydrogenation

Abstract

Abstract Methanol synthesis from CO 2 hydrogenation on the ZrO 2 doped In 2 O 3 (110) surface (Zr-In 2 O 3 (110)) with oxygen vacancy has been studied using the density functional theory calculations. The calculated results show that the doped ZrO 2 species prohibits the excessive formation of oxygen vacancies and dissociation of H 2 on In 2 O 3 surface slightly, but enhances the adsorption of CO 2 on both perfect and defective Zr-In 2 O 3 (110) surface. Methanol is formed via the HCOO route. The hydrogenation of CO 2 to HCOO is both energetically and kinetically facile. The HCOO hydrogenates to polydentate H 2 CO ( p -H 2 CO) species with an activation barrier of 0.75 eV. H 3 CO is produced from the hydrogenation of monodentate H 2 CO (mono-H 2 CO), transformation from p -H 2 CO with 0.82 eV reaction energy, with no barrier whether there is hydroxyl group between the mono-H 2 CO and the neighboring hydride or not. Methanol is the product of H 3 CO protonation with 0.75 eV barrier. The dissociation and protonation of CO 2 are both energetically and kinetically prohibited on Zr-In 2 O 3 (110) surface. The doped ZrO 2 species can further enhance the adsorption of all the intermediates involved in CO 2 hydrogenation to methanol, activate the adsorbed CO 2 and H 2 CO, and stabilize the HCOO, H 2 CO and H 3 CO, especially prohibit the dissociation of H 2 CO or the reaction of H 2 CO with neighboring hydride to form HCOO and gas phase H 2 . All these effects make the ZrO 2 supported In 2 O 3 catalyst exhibit higher activity and selectivity on methanol synthesis from CO 2 hydrogenation.