NiO-V₂O₅/SiO₂ and Cu/NiO-V₂O₅/SiO₂ were prepared by surface reaction modification method and isometric impregnation method, on which photo-stimulated surface reaction ability of synthesis of dimethyl carbonate (DMC) from CO₂ and CH₃OH were studied. TPR, XRD, UV-Vis DRS, IR and TPD-MS techniques were used to study the structure, light adsorption ability and chemisorption abilities of such catalysts. The results showed that Ni^2＋—O—V^5＋ bond was formed on the surface of catalyst after NiO and V₂O₅ were coupled, and NiO and V₂O₅ on the surface of support could act with each other. NiO promoted the dispersion of V₂O₅ on the surface of silica, which effectively prevents V₂O₅ from aggregation, and the addition of Cu and NiO could expand the light-responding scope of photo catalyst. There were multiple active adsorption sites on the surface of catalyst, and the effective chemisorptions of CO₂ and methanol on the catalyst greatly promoted the photochemical synthesis of DMC even at lower temperature. Under the condition of normal pressure, space rate 300 h^－1, 140 ℃ and 125 W UV irradiation, the conversion of CH₃OH was up to 14.2% with the DMC selectivity of 89.9% over Cu/NiO-V₂O₅/SiO₂ catalyst.

Key words: photo-catalytic reaction, coupled semiconductor, carbon dioxide, methanol, dimethyl carbonate