Hydrogenation of CO₂ to Methanol by a Nickel Pincer Catalyst and Mechanistic Investigations by Density Functional Theory Studies

The hydrogenation of CO₂ into methanol by a nickel pincer catalyst has been studied in both aqueous and solid–gas phases. Hydrogenation occurs at the moderate temperatures of 60–95 °C. The solid–gas phase reaction is found to be more efficient than the aqueous reaction. At 95 °C and 1 MPa of H₂/CO₂ (3:1), 18 μmol of methanol is generated in the optimized solid–gas phase reaction versus 10 μmol in the aqueous phase. Methanol generation is also verified by hydrogenating ¹³CO₂ in the presence of KOH/KOD. The density functional theory studies support the mechanistic investigations for hydrogenating CO₂ into methanol.