【作者】 李可心；

【导师】 郭伊荇；

【作者基本信息】 东北师范大学 ， 物理化学， 2010， 博士

【摘要】 杂多酸(HPA)以其独特的结构和优异的催化性能受到广泛的关注。然而,由于HPA的比表面积小(< 10 m2 g?1)、热稳定性差且易溶于极性溶剂,限制了其在许多催化过程中的实际应用。因此,将HPA固载到具有大比表面积、大孔径和高孔容的介孔材料上可克服它们在催化反应中的局限性并且获得更好的催化性能。本文致力于设计制备系列具有不同孔道结构有序性和几何形貌的二氧化硅或二氧化钛负载型H3PW12O40/SiO2和H3PW12O40/TiO2非均相催化材料,并分别通过双酚酸合成反应和水中典型有机污染物降解反应研究其非均相酸催化和光催化性能,具体研究内容如下。1.在聚乙氧基?聚异丙氧基?聚乙氧基三嵌段共聚物(PEO?PPO?PEO,P123)的结构导向作用下,采用一步溶胶?凝胶共缩合与水热处理相结合技术,制备了系列H3PW12O40担载量(4.0?65.1%)可调控的三维交联介孔结构H3PW12O40/SiO2复合催化剂。通过光谱技术、X射线粉末衍射技术、氮气吸附测定和电镜技术,对复合材料的组成与结构、表面物理化学性质和形貌进行了详细表征。当H3PW12O40的担载量低于20%时,这些材料呈现出较大的BET比表面积(604.5?753.0 m2 g?1)、较大的孔径(6.1?8.6 nm)和较高的孔隙率(0.75?1.2 cm3 g?1),而且,Keggin单元在整个材料中均匀分散。通过在无溶剂条件下以生物平台分子(乙酰丙酸)为原料合成双酚酸的反应,系统考察了这些复合材料的酸催化性能,并评价了其活化和循环使用情况。2.在低聚非离子型表面活性剂C18H37(OCH2CH2)10OH(C18EO10,Brij76)的作用下,通过一步共缩合技术,制备出了一系列介孔结构H3PW12O40/SiO2复合材料;通过调控前躯体的成分比例(主要是水与其它物质的摩尔比)和制备条件,分别获得了具有二维六方p6mm、三维六方P63/mmc和三维海绵状等不同孔几何构型的H3PW12O40/SiO2复合材料。这些材料具有较大的BET比表面积(590?1050 m2 g?1)、较高的孔隙率(0.4?1.3 cm3 g?1)和较大的孔径(3.0?5.4 nm)。作为一种可重复使用的新型固体酸催化剂,在无溶剂条件下,以上材料成功地应用于通过生物平台分子(乙酰丙酸)合成双酚酸的反应,并以此模型反应考察了复合材料的结构有序度、孔几何构型、H3PW12O40担载量及模板去除方法对催化反应活性和选择性的影响,并评价了其活化和循环使用情况。3.以非离子型表面活性剂为结构导向剂(P123和F127),分别采用蒸发诱导自组装(EISA)和水热处理技术,一步制备出了系列具有二维六方p6mm、三维立方Im3m和三维交联海绵结构的介孔H3PW12O40/TiO2复合材料,详细表征了这些复合材料的介孔结构、形貌、孔隙率、光吸收特性和组成与结构。随后,在模拟太阳光照射下(? > 320 nm和? > 400 nm),这些复合材料成功地应用于水溶液中环境激素邻苯二甲酸二乙酯和染料甲基橙及罗丹明B的光催化降解,同时,考察了H3PW12O40/TiO2复合材料的结构有序度、孔几何构型、H3PW12O40担载量、焙烧温度及入射光波长对光催化反应性能的影响。最后,评价了其活化和循环使用情况。更多还原

【Abstract】 Heteropoly acid (HPA) have attracted significant attention because of their special properties. However, HPA exhibit low surface area(< 10 m2 g?1), low thermal stability, high solubility in polarity solvent which limit their utility in many catalytic reactions. Thus, the dispersion of HPAs on mesoporous supports with high surface area, large pore diameter, and high specific pore volume is seen as a critical means of improving their properties and obtaining better performance in many potential heterogeneous catalytic applications.1. Periodic mesoporous H3PW12O40/SiO2 composite catalysts with controllable H3PW12O40 loadings (4.0?65.1%) were prepared by a direct sol-gel co-condensation technique in the presence of triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) copolymer followed by hydrothermal treatment. Powder X-ray diffraction patterns and nitrogen sorption analysis indicate the formation of ordered mesoporous materials. With H3PW12O40 loadings lower than 20%, the materials exhibit higher BET surface area (604.5?753.0 m2 g?1), larger pore size (6.1?8.6 nm), larger pore volume (0.75?1.2 cm3 g?1), and highly dispersed Keggin unit throughout the materials. Raman scattering spectroscopy studies confirm that the primary Keggin structure remained intact after formation of the composites. The acid catalytic properties of as-prepared materials was tested by the reaction of solvent-free synthesis of diphenolic acid from levulinic acid. Remarkably high catalytic activity and stability were observed.2. A series of mesostructured H3PW12O40/SiO2 materials were developed by using a single step co-condensation technique in the presence of nonionic oligomeric surfactant, C18H37(OCH2CH2)10OH (C18EO10, Brij76). By tuning the composition ratios of the starting precursors (mainly the molar ratios of water to the other materials) and the preparation conditions, the materials exhibited ordered two-dimensional (2D) hexagonal p6mm, three-dimensional (3D) hexagonal P63/mmc, and 3D disordered sponge-like pore geometries, respectively. The materials possessed unique textural properties including very large BET surface area (590?1050 m2 g?1), very high porosity (0.4?1.3 cm3 g?1), and well-distributed pore diameter (3.0?5.4 nm). As a novel type of reusable solid acid catalyst, as-prepared materials were applied for the synthesis of diphenolic acid (DPA) from biomass-derived platform molecule, levulinic acid (LA), under solvent-free condition, and special attention was paid to investigate the influences of the structural orderings, pore geometries, H3PW12O40 loadings, and template removal methods on the reactivity and selectivity of H3PW12O40/SiO2 materials to the target reaction.3. A series of mesostructured H3PW12O40/TiO2 materials with two-dimensional hexagonal p6mm, three-dimensional cubic Im3m, and three-dimensional interconnected sponge-like pore geometries were developed by using a single step nonionic-surfactant-templating strategy combined with evaporation-induced self-assembly (EISA) or hydrothermal treatment technique. The mesostructure, morphology, porosity, optical absorption property as well as composition and structure of as-prepared materials were well-characterized. Subsequently, the materials were successfully applied to the degradation of an aqueous phthalate ester (a kind of endocrine disrupting chemicals) under the simulated sunlight irradiation (? > 320 nm and ? > 400 nm), and special attention was paid to investigate the influences of the structural orderings, pore geometries, H3PW12O40 loadings as well as calcination temperature on the photocatalytic performance of the H3PW12O40/TiO2 materials to the target reaction.更多还原