Catalytic Hydrogenation of Carbon Dioxide to Methanol: Synergistic Effect of Bifunctional Cu/Perovskite Catalysts

As the increasing concentration of the atmospheric CO2 is being progressively recognized as a global environmental problem due to its greenhouse effect, the catalytic hydrogenation of carbon dioxide to methanol has been repeatedly put forward as a way of carbon fixation. Time and again have been copper-based heterogeneous catalysts shown to be best suited for this technological purpose, but their performance must be improved with secondary metal oxides, dopants, and supports. Herein, first-principles surface simulations of a Cu phase with four prospective perovskite substrate materials were performed. Cu/CaTiO3, Cu/SrTiO3, Cu/BaTiO3, and Cu/PbTiO3 were systematically studied. After extensive density functional theory (DFT) calculations, aimed at elucidating their stable structure, mapping out a complex reaction network, and pinpointing the rate-determining mechanism steps, the results were fed into a kinetic Monte Carlo (kMC) setup at industrially relevant operating conditions (the temperature of 420–660 K, pressure 0.001–100 bar, and different reactant ratios). It was found out that all studied systems outperformed the pure Cu. Among them, Cu/PbTiO3 was shown to offer very high selectivity and an overall good activity. With lead-containing metallic compounds being problematic due to their toxicity, Cu/SrTiO3 is a very good alternative, closely followed by Cu/BaTiO3. In all instances, CH3OH was observed to form via the formate route (from CO2 to HCOO, HCOOH, H2COOH, H2CO, H3CO, and CH3OH), while CO is produced from CO2 through t-COOH and c-COOH. The direct dissociation pathway of CO2 or CO hydrogenation was not notable, as indicated by the linked multiscale description.