The Preparation And Photocatalytic Performance Of Rare Earth Elements,heteropoly Acid,gold Doping And Modifing TiO2

The thesis introduces the development, theory and practical significance of semiconductor photo-catalysis, and explains TiO2 photo-catalytic elimination mechanism of organic pollutants and its current research condition in detail.The (C5H7N2)3AsMo12O40?5H2O/TiO2 and RE(RE=La,Ce,Pr,Nd)/TiO2 are prepared. The photo-catalytic activity of the photocatalysts is performed in a home-made continuous flow photo-catalytic tube reactor. The photo-catalytic elimination of methanol or acetone is used as model reaction to evaluate the photocatalytic activity of the photo-catalysts under ultraviolet light irradiation or visible light. Spectroscopic properties and structural morphology of catalysts are investigated through means of characterization, such as Infrared Spectrum, DTA-TG, X-ray diffraction, fluorescence spectra, scanning electron microscope, etc.RE(RE= La,Ce,Pr,Nd)/TiO2 photo-catalysts are prepared by sol-gel, The influence of a single rare earth element doping TiO2 on the photo-catalytic activity are researched. The effects of doping content, different types of rare earth elements and activation temperature on the catalytic activity are investigated by photo-catalytic elimination methanol experiment. The TG-DTA and Fluorescence results show that as the doping of rare earth elements, phase transition temperature from TiO2 anatase to rutile are increased and the photo-induced electron and hole recombination rate are decreased,the catalytic performance of rare earth elements doped are significantly improved. The best is Pr/TiO2. When the initial concentration of methanol is 12.0g?m-3and the flow rate is 10.0ml?min-1, the elimination rate of methanol can reach to 84.0% over the 0.1g Pr/TiO2 catalyst. The dynamics law of photocatalytic reaction over the Pr/TiO2 catalyst has been studied. The activation energy of the raection is 20.0KJ/mol, which accords to the first order dynamics law.The composite photo-catalyst (C5H7N2)3AsMo12O40 ? 5H2O/TiO2 are prepared through impregnation and studied through a series of characterization methods. The scanning electron microscope and XRD show that particle size become miniaturized and uniform; The fluorescence emission spectra of TiO2 and composite photo catalyst with different doping content of (C5H7N2)3AsMo12O40?5H2O show that the relative intensity of emission spectrum of (C5H7N2)3AsMo12O40?5H2O/TiO2 is obviously lower than pure TiO2. It indicates that the doping of (C5H7N2)3AsMo12O40?5H2O can help inhibit electron-hole recombination, and fully elaborate the synergistic effect of these two substances. The composite catalyst doped with 5.0wt.% has the highest activity. When the initial concentration of methanol and acetone is 3.2g?m-3 and 3.5 g?m-3 respectively, and the flow is 10.0ml?min-1, the elimination rate of methanol and acetone can reach to 100.0%.On the basis of research on elimination of methanol under UV light, the role of the visible light has been studied. Through orthogonal test, the effection of doping amount, calcination temperature, calcination time on catalytic activities have been investigated. The catalyst doped with 1.0wt.% and activated under 200℃has the highest activity. When the initial concentration of methanol is 35.0g?m-3, and the flow is 5.0ml?min-1, the elimination rate of methanol can reach to 62.3% under visible light.