Effect of Surface Hydroxyls on CO2Hydrogenation Over Cu/γ-Al2O3Catalyst: A Theoretical Study

Catalytic hydrogenation of CO 2 to methanol is a promising way to recycle and utilize CO 2 . In this study, the elementary steps leading to HCOO and CO formation have been explored to identify hydroxylation effect of the oxide support on the selectivity in CO 2 hydrogenation on Cu/γ-Al 2 O 3 catalyst by the density functional theory (DFT) slab calculations. Two models: Cu4 cluster supported on the dry γ-Al 2 O 3 (110) surface, D(Cu4), and on the hydroxylated γ-Al 2 O 3 (110) surface, H(Cu4), have been used to model Cu/γ-Al 2 O 3 . On D(Cu4), the formation of HCOO is preferred kinetically. On H(Cu4), HCOO formation is still kinetically favorable. These results indicate that the hydroxylation of γ-Al 2 O 3 support cannot alter the pathway of CO 2 hydrogenation forming the dominate product HCOO, and ultimately, the selectivity of CO 2 hydrogenation for HCOO formation on Cu/γ-Al 2 O 3 is higher, which supports the experimental fact that Al 2 O 3 -supported Cu catalyst is widely used to synthesize methanol by CO 2 hydrogenation.