Facet effect of In2O3 for methanol synthesis by CO2 hydrogenation: A mechanistic and kinetic study

Density functional theory (DFT) calculation and microkinetic modeling were performed to study the methanol synthesis from CO2 hydrogenation on indium-terminated In2O3(100), defective In2O3(110) and In2O3(111) surfaces. It is found that these surfaces can adsorb and activate CO2 and drive dissociative H-2 adsorption. As for adsorbed CO2, it may be transformed into HCOO, COOH and CO. Based on the calculation results, adsorbed CO2 prefers to be hydrogenated to HCOO on these surfaces compared to decomposition of CO2 and CO2 hydrogenation to COOH. According to transient state calculation, indium-terminated In2O3(100) surface displays low catalytic activity due to the high energy barrier. On the defective In2O3(110) and In2O3(111) surfaces, CO2 hydrogenation to methanol will undergo HCOO, H2CO and H3CO intermediates because this pathway has the lowest energy barriers. Microkinetic analysis reveals defective In2O3(110) is the optimal surface for methanol synthesis from CO2 hydrogenation and high ratio of H-2/CO2 favors CH3OH formation. [GRAPHICS] Density functional theory calculation and microkinetic modeling were performed to study the methanol synthesis from CO2 hydrogenation on In2O3 surfaces.