Photocatalytic Synthesis Of Methanol From CO₂ And H₂O Over Cu/CeO₂-NiO And Cu-CeO₂/TiO₂

Recently, the effective utilization of CO₂ has been attracting attention because it isnot only a main greenhouse gas, but also one of the most abundantcarbon-containing resources. Methanol is one of the most important industrialchemical materials. Therefore, the photocatalytic reaction for methanol from carbondioxide and water could not only make full use of carbon-containing to synthesizeindustrial materials, but also be benefit to dealing with pollution of atmospheric.Since synthesis of methanol from CO₂ and H₂O is very difficult for thermal surfacecatalysis, application for photo stimulating surface reaction technique into thereaction system is of great value in both theory and application.The content of this thesis is divided into two parts. Firstly, n-p coupledsemiconductor material Cu/CeO₂-NiO was prepared by solid-mixing method and theeffects of different catalysts on methanol synthesis from carbon dioxide and waterwere further investigated. The catalysts were characterized by X-ray powderdiffractometer (XRD),infrared ray (IR),Temperature programmed reduction (TPR)and electrochemistry analyses for their surface structure and light-respondin abilityEventually, the optimal copper loading, concentration and illumination time of thethree types of catalysts were respectively obtained. By calcined at 500℃, thecatalyst photocurrent intensity was reached maximum. The optimal amount of Culoading was 0.5wt.% and the methanol yield could reach up to 156.6μmol/g-Cat.following 8h of UV irradiation.The second part focuses on the Cu/TiO₂ catalysts modified by CeO₂. ThreeCu-CeO₂/TiO₂ catalysts prepared by equal-bulk impregnation method and wereperformed by XKD, Brunauer-Emmet-Teller (BET), Raman spectroscopy, H₂-TPRand electrochemistry analyses. Their catalytic properties determined in aqueoussuspension systems for synthesis of methanol from CO₂ and H₂O. The resultssuggest that comparing with Cu/TiO₂, Cu-CeO₂/TiO₂ catalysts can obviouslyenhance the efficiency of photocatalytic reduction of CO₂ and three differentCu-CeO₂/TiO₂ catalysts prepared by equal-bulk impregnation method can lead to major differences in the physicochemical properties (e.g., Raman, Redox andphotovoltaic) and the catalytic properties. The catalytic activity for methanolsynthesis depends strongly on reaction temperature and the amount of Cu loading.The optimal reaction temperature is 50℃and the optimal amount of copper loadingis 2wt.% in the present catalyst system. In that case, the methanol yield could reachup to 180.3μmol/g-Cat. under the experimental conditions of this work.