Preparation and Characterization of Vanadium Oxide Deposited on Thermally Stable Mesoporous Titania

摘要

Vanadium oxide was deposited on mesoporous titania by the molecular designed dispersion method to investigate the potential properties of these catalysts.Mesoporous titania was synthesized following the evaporation-induced self-assembly (EISA) method with a subsequent treatment with ammonia to increase the thermal stability.As a result,the mesoporous titania obtained shows a high surface area (approx 350 m~2/g) and high stability.Vanadium oxide was deposited by the MDD method using a vanadyl acetylacetonate complex that was transformed into VO_x after a controlled calcination in air flow at 300 deg C.The mesostructure and porosity characteristics of titania remain even until the maximum V-loading was reached (0.4 mmol/g),as it was shown by N_2 sorption measurements at -196 deg C.The catalysts were characterized by chemical analysis,Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS),UV-vis diffuse reflectance (DR),and Fourier transform Raman spectroscopy.Raman spectra showed isolated V species for the different V-containing catalysts.Furthermore,UV-vis-DR revealed a higher contribution of polymeric species as the V loading increases.The VO_x/mesoporous titania catalysts were highly active in the selective catalytic reduction of NO_x.A high activity in the NO conversion was observed,which increases with increasing metal loading.