Dissertation
Dissertation > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst

Visible oxide catalyst with high activity and mechanism of Design and Synthesis

Author XieMingZheng
Tutor JingLiQiang
School Heilongjiang University
Course Physical and chemical
Keywords Non-metal doped TiO2 Phase-separated hydrolysis-solvothermal process Nano-sized BiVO4 modified hydrothermal process visible light photocatalysis
CLC O643.36
Type Master's thesis
Year 2011
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Photocatalytic technology which is developed in recent years is a new environmental control technology, and has caught people’s attention widely. Preparing the visible-light photocatalyst is the key for making this technology practical. To the problems of complicated technology and poor wide suitability in preparing nonmetal doped TiO2 and large particle size and poor photocatalytic activity of BiVO4 samples prepared by normal methods, we carried out the study of developing new methods to prepare non-metal doped TiO2 and nano-sized BiVO4 photocatalysts.On the basis of combining the advantages of hydrolysis process and solvothermal process, we developed the phase-separated hydrolysis-solvothermal process, and through it we prepared the TiO2 which doped with N, S, Si et al controllable, the effects of reaction temperature et al on the photocatalytic activity of samples were mainly investigated. The results show that, comparing to the TiO2 prepared by hydrolysis-hydrothermal process, the TiO2 we prepared has better UV-photocataltic activity due to the higher crystalline degree and dispersibility. By introducing the ammonia et al into the water phase, we obtain the N et al non-metal doped TiO2 simply. The non-metal doping enhances the visible light absorption of TiO2 effectively, and the sample exhibits a good Vis-photocatalytic activity, it is worth noting to that the N-doped TiO2 exhibits better photocatalysis activity than the sample prepared by high-temperature nitriding. In addition, the Si-doped TiO2 with high thermal stability and photocatalytic activity which is better than the photocatalytic activity of P25 also can be obtained by introducing the C8H20O4Si into the organic phase.To the problems the BiVO4 particle is easy to grow too large in synthesis process, we developed a new method to prepare nano-sized BiVO4 by introducing EDTA. And the effects of reaction temperature et al on the particle size of samples were mainly investigated. The results show that reducing the reaction temperature and time and increasing the addition of EDTA are benign to the controlling the particle size of BiVO4, the BiVO4 samples with an average particle size of 20 nm can be obtained. Based on the IR spectra, it is confirmed that the introduction of EDTA can be coordinate with Bi3+ to form a stable compound, consequently keeping a low-content free Bi3+ in the reaction system and then inhibiting the growth of BiVO4 crystallites during the hydrothermal processes. The nano-sized BiVO4 particles show a high Vis-photocatalytic activity, that is mainly due to its small particle size and large surface area.

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