| Photocatalytic reduction of carbon dioxide to methanol is one of the important topics of today’s concerns and research. In this paper, we study in the gas-solid-liquid phase reaction system using multi-metal oxide semiconductor composites as a catalyst for the photocatalytic reduction of carbon dioxide and water methanol synthesis reaction.Using sol-gel method to prepare nano-composite catalyst La2O3-TiO2and Fe2O3-TiO2, and were characterized by XRD, UV-Vis DRS. Experiments show that: when the calcination temperature is700℃, the composite volume is1%, the photocatalytic activity is highest; the best preparation conditions of Fe2O3-TiO2is at700℃calcination,1%complex quantity. Using citric acid complexing-sol-gel method to prepare LaFeO3-TiO2nano composite catalyst,and characterized by TG-DTA, FTIR, UV-Vis, XRD haracterization of its structure, resarching the calcination temperature, LaFeO3quantity to light catalysis catalytic reduction of CO2to methanol, the influence of performance and optimization of reaction conditions. The results show that LaFeO3composite with TiO2can inhibit the crystal phase transition of TiO2, improve the degree of crystallinity of anatase phase, broaden the catalyst light response range, improve the photocatalytic performance; when the catalyst calcination temperature is800℃, LaFeO3composite mass fraction is3%, the photocatalytic performance is best.The experiment studies the influence of the reaction conditions of catalytic reduction reaction. Research shows that:the catalyst dosage, reaction time, flowing rate of CO2, reaction temperature both have an impact on response. The results showed that the catalyst dosage is2.0g/L, the reaction time is7h, the CO2flow rate is200ml/min, the reaction temperature is90℃, concentration of NaOH and Na2SO3in reaction liquid is0.10mol/L, the yield of methanol was325.49umol/g.Integrated various studies show that:anatase TiO2, rutile TiO2and LaFeO3of LaFeO3-TiO2, three phase formed in three-phase heterojunction structure effectively expand the light response range and improve phase transition temperature, crystallinity increase anatase phase, reduce the carrier recombination rate, improve the photocatalytic activity. This method of perovskite and TiO2semiconductor compound also provides reference for the preparation of high efficient photocatalyst. |
