【作者】 武加峰；

【导师】 李瑞丰；

【作者基本信息】 太原理工大学 ， 化学工程与技术， 2013， 博士

【摘要】 介孔SiO2材料因其具有高的比表面积、较大孔容及孔径可调,成为多相催化领域研究的热点。由于纯硅介孔材料骨架为非晶态,骨架没有缺陷位,呈电中性,纯硅介孔材料无酸性位,没有催化活性。纯硅介孔材料骨架非晶态化,相比微孔沸石容易进行改性。对介孔材料进行金属功能化修饰,能够改善介孔SiO2材料的催化性能。选择不同的前驱体和不同合成路线,可以得到不同载体类型和不同物种结构的活性组分。通过对催化剂结构分析和催化性能分析,可以选择适宜的合成路线、合适的催化剂载体类型和对制备条件进行优化,进一步获得催化性能与活性物种类型、载体类型和制备方法相关的信息,以寻求对催化剂在原子水平进行设计。介孔材料MSU-X与SBA-15和MCM-41相比,具有三维蠕虫状介孔结构,孔道较短,有利于反应物和产物扩散。此外,MSU-X一般是在中性条件合成,模板剂与介孔材料表面静电作用和氢键作用较弱,模板剂可以采用乙醇抽提的方式脱出,提高了模板剂的可重复利用性,降低了合成成本。同样,介孔材料SBA-16具有三维有序结构,有利于基质的传输,是催化反应的优良载体。本文采用中性模板合成路线,以正硅酸乙酯(TEOS)为硅源,以嵌段共聚物F127为模板剂,制备了具有高比表面积、蠕虫状结构特征的Fe、Cr-MSU-X材料,在催化反应中表现出较高的催化活性和选择性。调节pH值水热嫁接合成路线制备了具有较高比表面和孔径均一的介孔材料Fe、Cr-SBA-16,催化反应中表现出较高的催化活性和选择性。合成体系pH值影响Fe、Cr的配位环境和催化性能中性模板合成路线制备了具有高度有序介孔结构的Sn-MSU-X材料,该材料具有高的比表面积、较大的孔容,孔径分布均一,而且富含微孔结构,酸性研究表明,材料表面同时具有Bronsted和Lewis酸性位,Lewis酸是主要酸性位。更多还原

【Abstract】 Mesoporous SiO2materials are subject to extensive research in heterogeneous catalysis because of their high surface areas, large pore volumes and tunable pore diameters. However, these mesoporous materials show poor catalytic performances owing to their amorphous framework, electrical neutrality, no defects and acid sites on the surface. The amorphous framework results in easy modification of mesoporous SiO2compared with zeolite. The catalytic performance of these mesoporous materials can be enhanced by metal modification owing to new active sites introduced. Catalysts with different supports and active species can be prepared by choosing different precursors and synthesis routes. Combining the correlation between catalytic performance and the properties of active species, supports and their interrelations, the design and preparation of a highly effective catalyst can be achieved.MSU-X is a new type of mesoporous SiO2material with three dimensional (3D)"worm-like" pore and shorter channel. Compared with SBA-15and MCM-41(2D pore structure), MSU-X shows better diffusion performance of the reaction substrate and product owing to the3D structure. Moreover, MSU-X is usually synthesized under neutral conditions. The electrostatic interaction and hydrogen bond between the template and materials surface is weak, which results in the template can be easily removed by ethanol extraction. Thus the templates can be reused and the synthetic cost can be reduced. Similarly, mesoporous material SBA-16with3D ordered structure can be used as an excellent catalytic support. Herein, Fe/Cr-MSU-X catalysts with hierarchical mesopores were successfully prepared by neutral-template route with TEOS as silica source and plouric F127as template. Fe/Cr-MSU-X catalysts showed high catalytic activity and selectivity for liquid phase oxidation of phenol with hydrogen peroxide as oxidant agent.A series of Fe/Cr-SBA-16with different Fe/Cr content were synthesized by adjusting the pH value of synthesis system, respectively. Fe/Cr species types can be affected by the pH value in the synthesis system. These Fe/Cr-SBA-16showed high surface area and uniform pore size distributions. And Fe/Cr-SBA-16showed high catalytic activity and selectivity in catalytic applications.Sn-MSU-X with high ordered structure was synthesized under neutral condition. Sn-MSU-X possessed high surface area and large volume. The pore sizes were uniform and Sn-MSU-X was rich in microporous structure. The pyridine FTIR revealed that there were both Bronsted and Lewis acidic sites on the surface, in which, Lewis acid was the dominant one.更多还原