Studies on the preparation of supported metal oxide catalysts using JRC-reference catalysts II.Vanadia-titania catalyst: effect of starting solution and phase of titania

摘要

The effect of preparation conditions on the structure of vanadia-titania catalysts was investigated using two series of 5 wt.%V_2O_5/TiO_2 catalysts prepared by impregnation of ammonium metavanadate using JRC-TIO-3 (rutile) and JRC-TIO-4 (mainly anatase) as supports. The structure and chemical perperties of supported vanadia were investigated by FT-IR, Raman, XPS, UV-VIS, NARP, and TPR. The dispersion of surface vanadia was affected by preparation conditions and by the phase of titania, i.e.the catalysts impregnated from oxalic acid solution exhibited higher dispersion of surface vanadia species. The effect of the starting solution was more drastic on the selective oxidation of benzene into maleic anhydride. The production of maleic anhydride was observed in the catalysts prepared from oxalic acid solution of ammonium metavanadate. On the contrary V_2O_5/TiO_2(rutile) prepared without oxalic acid solution only formed carbon oxides. The correlation between preparation method and catalytic performance in the oxidation reaction was discussed on the basis of the dispersion, surface species, and chemical properties of surface vanadia species.