Study On Preparation And Performance Of Nanometer Photocatalyst

A series of nano photocatalysts La-Y/TiO₂, La-Eu/TiO₂, La-PWA/TiO₂, Ce-PMoA/TiO₂, ZLW-TiO₂ and ZPMo-TiO₂ were prepared by Sol-Gel method. The properties such as crystal structure, specific surface area, pore distribution, surface properties and optical adsorption properties were characterized. The degradation of methylene blue （MB） was chosen as the probe reaction to examine the photocatalytic activities of as prepared nano photocatalysts, the influence of the crystal phase, amount of ions dopping and pH value of MB solution to the process of MB photo degradation were studied. The relationships among the structure properties of the photocatalysts and their photocativities were analyzed.（1） The photocatalysts are anatase phase, and have litter crystalline size. Rare earth ions doping could swelled and aberrated the crystalline, improved the stability of anatase phase, and inhibited the crystalline phase transition. The ions doping could enhance optical adsorption in ultraviolet region, and the wavelength moved to visible region. The modified catalysts have larger specific surface area, especially the specific surface area of ZLW-TiO₂ and ZPMo-TiO₂ is 5 times as pure TiO₂.（2） The results of MB photocatalytic degradation showed, compared to pure TiO₂, the photocatalytic activities of La-Y/TiO₂, La-Eu/TiO₂, La-PWA/TiO₂, Ce-PMoA/TiO₂, ZLW-TiO₂ and ZPMo-TiO₂ have improved. The results of La-PWA/TiO₂, Ce-PMoA/TiO₂, ZLW-TiO₂ and ZPMo-TiO₂ isothermal adsorption showed that isotherm curve of MB on the surface of catalysts can be well described by Langmuir equation and the rate constant of photocatalytic degradation MB improved obviously.The photocatalysts Fe-Al-silicate and PG-Fe were prepared by ions adsorption and chemistry synthesis method respectively, and their structures were characterized. The photocatalytic activities were evaluated by phenol hydroxylation, and the results showed that two kinds of catalysts exhibit excellent photocatalytic activity and higher selectivity.（1） Fe-Al-silicate was identical to the typical pattern characteristic of cristobalite-like phase, has larger specific surface area and stranger adsorption ability in ultraviolet and visible region. PG-Fe has stronger adsorption ability in both ultraviont and visible region.（2） The effects of various parameters on photocatalytic hydroxylation of phenol were studied using Fe-Al-silicate and PG-Fe as photocatalysts. In optimize reaction condition, the phenol conversion, yield of catechol and hydroquinone, selectivity can reach 64.9%, 39.3%, 22.3%, and 95% respectively, when using Fe-Al-silicate as photocatalyst. The phenol conversion, yield of catechol and hydroquinone, selectivity can reach 87.8%, 37%, 27.4% and 73.3 respectively, when using PG-Fe as photocatalyst.（3） The mechanism of photocatalysis of the catalysts was inferred. When the Fe-Al-silicate and PG-Fe were radiated by ultraviolet light, the ?OH was formed in the reaction system, ?OH can react with phenol to form catechol and hydroquinone.