Photocatalytic Reduction of CO₂ into Hydrocarbon over Cu-TiO₂/SiO₂-Al₂O₃ Catalyst

Abstract

This research aimed to study the photocatalytic reduction of CO₂ into methanol over TiO₂ supported on SiO₂-Al₂O₃ catalysts. The effects of reaction time and the influence of copper (1-4 %wt) doped on SiO₂-Al₂O₃ on the methanol yield were investigated. The experiments were carried out in a 50 ml batch reactor under UV irradiation. The catalysts prepared by the sol-gel method were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The result indicated that the maximum of methanol production was obtained after the irradiation of 2 h and slightly reduced after that, probably due to the methanol oxidation process. The highest methanol production of 1258.8 µmol gcat^-1 was obtained when 2%wt Cu-TiO₂/SiO₂-Al₂O₃ catalyst. This was 5.98 times that obtained from the undoped photocatalyst. The presence of the CuO phase could separate the electron from the TiO₂ conduction band to move into the CuO conduction band. However, the high content of CuO could increase the TiO₂ crystal size. Moreover, the catalysts could be reused seven times for the purpose. Therefore, the result of this research indicated the potential of using Cu with TiO₂/SiO₂-Al₂O₃ catalyst for reducing CO₂ emission to the environment.