Photocatalytic reduction of CO2 into methanol over Cu–Ni–TiO2 supported on SiO2-Al2O3 catalyst

The photocatalytic reduction of carbon dioxide into hydrocarbon over bimetallic-loaded TiO2 supported on SiO2-Al2O3 (Ni–Cu–TiO2 /SiO2-Al2O3) catalyst was studied. The study also compared the performance of the catalyst with Degussa P25 (TiO2), prepared TiO2, SiO2-Al2O3 loaded with TiO2. The investigation of catalytic performance was carried out in a batch reactor under UV irradiation. All the samples were characterized by X-ray diffractometer (XRD), N2 gas adsorption–desorption, and Ultraviolet–visible diffuse reflectance spectrometer (UV–Vis-DRS). The result showed SiO2-Al2O3loaded with Ni–Cu–TiO2 yielded the highest production rate of methanol (405.08μmol/gcat ) after 2 h of reaction under UV at room temperature and a pressure of 1 atm. The photocatalytic reduction rate over the bimetallic-loaded TiO2 supported on SiO2-Al2O3 catalysts was found to be approximately 2.4 times that over SiO2-Al2O3 loaded with TiO2. This can be explained by the presence of nickel and copper on the catalyst which reduced the energy bandgap of the catalyst and decreased the recombination of electron–hole pairs.