Photocatalytic Reduction Of CO₂ On CuO/TiO₂ Catalyst With Water Vapor

CO2, as one of the important main greenhouse gases, is chemically stable, so the conversion of CO2 in conventional methods leads to several troubles such as high enegy-consuming and strict condition. The photocatalytic reaction can converts CO2 into more useful compounds such as methane, methanol,. and formaldehyde. In addition, by harnessing solar energy the photocatalytic process is less energy-consuming than the conventional methods. Therefore, the photocatalytic conversion of CO2 with water vaper in the presence of TiO2 has been studied in this paper and the photocatalyst has been modified for better activity.Nano-anatase-TiO2 particle has been synthesized via sol-gel methods. Different CuO content supported/composite photocatalysts were synthesized via impregnation methods. The composition and structure property of these photocatalysts were characterized by XPS, XRD, HRTEM, PL, BET and XRF. The photocatalytic conversion reaction of CO2 was examined in a self-designed fixed-bed photocatalytic reactor. The influence of different kind of CuO/TiO2, reaction temperature, H2O/CO2 ratio of the raw material and irradiation intensity were systematically studied in the photocatalytic reduction of CO2 with H2O.Methane (CH4), carbon monoxide(CO), ethene(C2H4) and trace amout of ethane has been found in the reactor as the prouduct of photocatalytic reduction of CO2 in contact with water using CuO/TiO2 catalysts under the UV irradiation at mild conditions of low pressure and temperature. The photocatalytic activity could be significantly improved with appropriate CuO content and the optimal content of CuO was 1.5 w.% in CuO/TiO2 nano particle catalysts which was prepared by P25, CH4 yield reached 6.375μmol·g·cat-1 after 17 h irradiation at 333 K with H2O/CO2=0.02. Meanwhile, the catalysts synthesized via sol-gel methods show lower reactivity than others. The CH4 yield can be enhanced by increasing the reaction temperature, H2O/CO2 ratio and UV irradiation duration. By using the coating treatment on the catalyst during the experimentation, efficiency of the reaction has been improved.