【作者】 史慧贤；

【导师】 张天永；

【作者基本信息】 天津大学 ， 工业催化， 2011， 博士

【摘要】 采用溶胶-凝胶法制备了双稀土元素、稀土和杂多酸、以及稀土、杂多酸和分子筛多组分共掺杂改性的纳米TiO₂光催化剂:La-Y/TiO₂、La-Eu/TiO₂、La-PWA/TiO₂、Ce-PMoA/TiO₂、ZLW-TiO₂和ZPMo-TiO₂纳米光催化剂。表征了光催化剂的晶体结构、形貌、比表面积和孔径分布、表面形态、光吸收能力等性质。以亚甲基蓝（MB）的降解为探针反应,研究了催化剂晶型、离子掺杂量、MB溶液的pH值对MB光催化降解过程的影响。分析光催化剂结构和表面性质与其吸附和光活性之间的关系。（1）所制得的催化剂为锐钛矿型TiO₂,晶粒尺寸较小,稀土离子的掺杂使TiO₂晶型发生膨胀和畸变,提高了光催化剂的稳定性,有效抑制了TiO₂在高温下的晶相转变。经掺杂改性后TiO₂的光吸收能力增强,吸光波长向可见光区移动。改性后催化剂的比表面积增大,尤其是多组分催化剂ZLW-TiO₂和ZPMo-TiO₂的比表面积是纯TiO₂的5倍。（2）进行了一系列光催化降解MB实验。与纯TiO₂相比,La-Y/TiO₂、La-Eu/TiO₂、La-PWA/TiO₂、Ce-PMoA/TiO₂、ZLW-TiO₂和ZPMo-TiO₂的光催化活性明显增强。La-PWA/TiO₂、Ce-PMoA/TiO₂、ZLW-TiO₂和ZPMo-TiO₂的等温吸附实验表明,MB在催化剂表面的吸附符合Langmiur吸附等温式,且其光催化降解MB的速率常数增大。通过离子吸附法和化学合成法制备了Fe-Al-silicate和PG-Fe光催化剂,对其结构进行表征,通过光催化羟基化苯酚实验来评价其光催化活性,两种催化剂的光催化活性和选择性均较好。（1） Fe-Al-silicate具有类方石英晶型,比表面积较大,有强的吸收紫外光能力。PG-Fe在紫外区和可见区均有较强的吸光能力。（2）以Fe-Al-silicate和PG-Fe为光催化剂,考察了各种影响因素对光催化羟基化苯酚反应的影响。在优化实验条件下,Fe-Al-silicate光催化羟基化苯酚的转化率、邻苯二酚和对苯二酚收率、选择性分别为64.9%、39.3%、22.3%和95%。PG-Fe光催化羟基化苯酚的转化率、邻苯二酚和对苯二酚收率、选择性分别为87.8%、37%、27.4%和73.3%。（3）推测了两种催化剂的光催化机理。Fe-Al-silicate和PG-Fe受紫外光辐射时,反应体系中生成?OH,?OH和苯酚发生反应生成邻苯二酚和对苯二酚。更多还原

【Abstract】 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.更多还原