Mechanistic investigation of CO2 hydrogenation to methanol on W-doped Cu surfaces

Abstract

Density functional theory (DFT) computations were applied to study the adsorption of intermediates, the thermodynamic and kinetic mechanism of the conversion of CO2 to methanol upon the W-doped Cu surface, and the effect of W-doping on the decomposition and selectivity of methanol. For this reason, the adsorption structures and energies for the most stable structures were calculated. The outcomes displayed that the adsorption of intermediates over the surface of Cu-W is more powerful than the surface of Cu due to strain and ligand effect. Two reaction pathways of methanol synthesis (formate and carboxyl routs) were studied. The transition situation configurations and the potential energy profiles associated with each primary stage upon the surfaces of Cu (111) and Cu-W (111) were explored. The relevant activation barrier, rate constant, reaction energy, and Gibbs free energy for each primary stage were computed and the rate-limiting stages were determined. The Brønsted-Evans-Polanyi (BEP) relationships were used to study which pathway of conversion of CO2 to methanol is better. The outcomes indicated that W weakens the performance of the catalyst and the carboxyl route is more suitable than the formate route due to the low activation barrier for most of its primary stages. Also, the outcomes indicated that W-doping increased the methanol decomposition and reduced the selectivity of methanol.

Keywords

• CO2 hydrogenation
• Density functional theory
• Mechanism
• Methanol