| Summary: | 碩士 === 國立中正大學 === 化學工程所 === 98 === The goal of this study is to understand the effects of the structures of V2O5-TiO2, V2O5-SiO2, V2O5/ TiO2-SiO2 on the catalytic performance. Titania was grafted on SiO2 pellets to produce TiO2-SiO2 supports, and V2O5/TiO2-SiO2, V2O5/SiO2 and V2O5/TiO2 were prepared by grafting vanadia on the TiO2-SiO2, granular SiO2, and anatase nano-particles, respectively. The oxidation tests were carried out at a fixed bed reaction system under 1 atm and temperature ranged from 200 to 550˚C. The structures of catalysts were characterized by Synchrotron XRD (X-ray diffraction), XAS (X-ray adsorption spectroscopy).
The data show that V2O5 and TiVO4 of crystal grain size about 10 nm formed on anatase support. In contrast, isolated VO4 and small V2O5 clusters were formed on TiO2-SiO2 and SiO2, respectively. Since V2O5/SiO2 presents higher vanadia dispersion but lower activity than V2O5/TiO2, it is suggested that vanadia-titania interactions promote the oxidation reaction. The low vanadia dispersion for V2O5/TiO2 can be improved by the use of TiO2-SiO2; the mono-layer TiO2 on SiO2 helps anchor vanadia to form isolated VO4 species.
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