Water and Cu + Synergy in Selective CO 2 Hydrogenation to Methanol over Cu-MgO-Al 2 O 3 Catalysts.

The CO 2 hydrogenation reaction to produce methanol holds great significance as it contributes to achieving a CO 2 -neutral economy. Previous research identified isolated Cu + species doping the oxide surface of a Cu-MgO-Al 2 O 3 -mixed oxide derived from a hydrotalcite precursor as the active site in CO 2 hydrogenation, stabilizing monodentate formate species as a crucial intermediate in methanol synthesis. In this work, we present a molecular-level understanding of how surface water and hydroxyl groups play a crucial role in facilitating spontaneous CO 2 activation at Cu + sites and the formation of monodentate formate species. Computational evidence has been experimentally validated by comparing the catalytic performance of the Cu-MgO-Al 2 O 3 catalyst with hydroxyl groups against that of its hydrophobic counterpart, where hydroxyl groups are blocked using an esterification method. Our work highlights the synergistic effect between doped Cu + ions and adjacent hydroxyl groups, both of which serve as key parameters in regulating methanol production via CO 2 hydrogenation. By elucidating the specific roles of these components, we contribute to advancing our understanding of the underlying mechanisms and provide valuable insights for optimizing methanol synthesis processes.