Photocatalytic Reduction of CO2 to CH3OH Coupling with the Oxidation of Amine to Imine

Abstract

The photocatalytic reduction of CO2 to organic molecules is one promising approache for both decreasing CO2 concentration in the atmosphere and storing energies. However, most of the photocatalytic reduction of CO2 cannot avoid the utilization of sacrificial agents, which are not atomic economy and restricts the practical application of the photocatalytic reduction of CO2. In this contribution, an atomic economy photocatalytic reduction of CO2 to CH3OH coupling with the oxidation of amine to imine by Cu/TiO2 was reported, which can avoid using the sacrificial agents in the reaction systems. CO2 was reduced to CH3OH by photo-induced electrons; meanwhile benzylamine was selected as the reductant to react with photo-generated holes and converted into imine with high selectivity. The results showed that the maximum conversion of benzylamine to imine is 88.7% with selectivity of 98%, and the highest yield of CH3OH is 961.4 µmol g−1 using ca.0.5 wt% Cu/TiO2 as the catalyst. And also, the reaction mechanism was also investigated by DFT calculation, which would give a detailed explanation for the reaction process. Schematic illustration is that maximum conversion of benzylamine to imine is 88.7% with selectivity of 98%, and the highest yield of CH3OH is 961.4 μmol g−1 using ca.0.5 wt% Cu/TiO2 as the catalyst