【作者】 袁金芳；

【导师】 王连军；

【作者基本信息】 南京理工大学 ， 环境工程， 2011， 博士

【摘要】 有序介孔材料因其具有2-50 nm均匀可控的孔径,大的比表面积和孔容、规则的孔道、易于修饰的表面等特性使其在催化、吸附、分离、生物医药等领域具有重要应用价值,备受国内外研究人员的关注。传统SBA-15呈棒状或纤维状,孔道较长(1-2μm),且颗粒往往呈聚集状。当其作为载体应用于吸附、分离和催化领域时,物质在微米级孔道范围内较慢的传递和扩散是制约动力学的主要因素之一。本论文针对传统SBA-15孔道较长而引起的扩散速度慢的问题,采用新的合成路线制备了六方板状、短孔道有序介孔材料。围绕合成过程中的影响因素进行系统研究,获得了六方板状短孔道有序介孔材料的可控合成优化条件。在此基础上,以合成的短孔道、六方板状介孔材料为基体,制备了氨基、巯基功能化介孔吸附材料和负载型铜锰复合氧化物介孔催化剂,考察了短孔道载体对吸附材料和催化剂性能的影响。结果表明,以ZCS为载体得到的吸附材料和催化材料,其性能与传统SBA-15相比有显著的改善。本论文主要进行了以下几个方面的研究工作：1.以非离子表面活性剂P123为模板剂,正硅酸乙酯(TEOS)为硅源,氧氯化锆(ZrOCl2·8H2O)和硝酸亚铈(Ce(NO3)3·6H2O)为无机前驱盐,在不外加任何无机酸的条件下,利用无机前驱盐自身水解产生的弱酸性环境,采用水热合成路线一步合成了不同形貌的Zr-Ce-SBA-15(ZCS)介孔材料。考察了合成体系中不同的合成条件,包括nZr(Ce)/nSi摩尔比、nCe/nZr摩尔比、反应温度和晶化温度等对合成产物的形貌和结构的影响,利用扫描电子显微镜(SEM)和小角X射线衍射(SXRD)对不同条件下制备的一系列样品形貌和孔道有序性进行了表征,研究并讨论了合成条件对介孔材料形貌和介孔结构有序性的影响规律。2.在ZCS介孔材料的一步法水热合成体系中,控制nZr(Ce)/nSi摩尔比为0.05、nZr/nCe摩尔比为1、反应温度为35℃,制备了高度有序、大径轴比、短孔道、六方板状形貌ZCS介孔材料。利用电感耦合等离子体原子发射光谱(ICP-AES)、粉末X射线衍射(XRD)、透射电子显微镜(TEM)、SEM、氮气吸附/脱附(BET)等手段对所合成样品的元素和相组成、形貌和微观结构进行了详细表征。结果表明：合成的材料形状规则,颗粒的径向长度约为1.5-1.7μm,轴向长度约为0.4-0.5μm,具有类似于SBA-15的二维六方介孔结构。孔径、孔容和比表面积分别为6.4nm、0.96 cm3/g和776 m2/g。3.分别采用共缩聚和后接枝方法,以非离子表面活性剂P123为模板剂,N-(2-氨基乙基)-3-氨丙基三甲氧基硅烷(AAPTS)、3-巯基丙基-三甲氧基硅烷((MPTMS)为有机修饰剂,分别合成了氨基和巯基官能团化的短孔道有序介孔材料。通过物理化学手段分析测试,结果表明AAPTS和MPTMS成功地引入到有序介孔材料上,短孔道功能化材料仍保持了类似于传统SBA-15高度有序的二维六方介孔结构。功能化短孔道介孔材料对大分子有机染料的吸附性能研究表明,和传统长孔道SBA-15相比,这种功能化新型介孔材料具有更好的传输能力,可使有机大分子快速达到吸附平衡。4.以ZCS为载体,通过浸渍法制备了负载型铜锰复合氧化物介孔催化剂(Cu-Mn/ZCS)。以甲苯催化燃烧为模型反应,以传统的SBA-15负载型铜锰复合氧化物介孔催化剂(Cu-Mn/SBA-15)为参照,研究了Cu-Mn/ZCS催化剂对甲苯燃烧反应的催化性能、优化制备条件及机制。结果表明,与传统Cu-Mn/SBA-15相比,Cu-Mn/ZCS催化剂具有更好的催化效果。控制Cu-Mn质量比为1：1、Cu-Mn负载量为20%(质量分数)、经500℃焙烧4h制备的催化剂具有良好的催化活性。甲苯催化燃烧的起燃温度(T50)和完全燃烧温度(T95)分别为247℃和270℃。铜锰氧化物等活性组分在ZCS介孔分子筛孔道中高度分散,且晶化度较低是Cu-Mn/ZCS催化剂有较高催化活性的原因。研究结果为短孔道介孔材料在催化领域中的应用提供了一定的理论和实验依据。更多还原

【Abstract】 Well-ordered mesoporous materials have been found great applications in the fields of catalysis, adsorption, separation and biomedicine because of their highly ordered pore structure, uniform pore size, large pore volume, high special surface area, the presence of voids of controllable dimensions at 2-50 nanometer scales, and easily modified surface characteristics. The morphology of conventional SBA-15 are usually bar or fiber aggregates. The slow transfer and diffusion of reactants in the relatively long channels has been the main problem for dynamic reaction when SBA-15 was used as catalyst, sorption and separation media. For solving such problem, a new one-step hydrothermal routine was used to synthesis highly ordered SBA-15 mesoporous material with hexagonal platelet morphology and short channels. The controlling factors for the synthesis of the new mesoporous material were systematically studied and the optimized condition was obtained. Amino-functionalized H2N-Zr-Ce-SBA-15 (H2N-ZCS) catalyst and Cu-Mn/ZCS catalyst were prepared based on the newly formed hexagonal platelet SBA-15. The catalytic and adsorption property of the catalysts based on ZCS were superior to the conventional SBA-15. The main research work and results are summarized as follows.(1) The mesoporous Zr-Ce-SBA-15 (ZCS) materials with various morphologies were synthesized by a one step hydrothermal route using tetraethyl orthosilicate as a silica source, Pluronic P123 as a template, zirconyl chloride and cerous nitrate as a precursor under a moderate self-generated acidic condition produced by the hydrolysis of the precursor, without the addition of mineral acids. The effects of the controlling factors on the morphologies and structures of ZCS, including molar ratios of nZr(Ce)/nSi and nZr/nCe, hydrothermal temperature and crystallization temperature, were systematically studied. Scanning electron microscope (SEM) and small angel X-ray diffraction (SXRD) were used to characterize the morphology and order of the arrangement of the mesopores. The relationship between synthetic parameters and the morphology and structure of mesopores was established.(2) With such a one step hydrothermal method, highly ordered mesoporous ZCS with hexagonal-platelet morphology was synthesized by controlling the reaction temperature at 35℃and molar ratios of nZr(Ce)/nSi and nZr/nCe at 0.05 and 1, respectively. Inductively coupled plasma atomic emission spectrometry (ICP-AES), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and N? adsorption/desorption were used to characterize the elemental and phase composition, morphology and microstructure of the as synthesized ZCS. Characterization reveals that the ZCS possesses a 2D hexagonal mesoporous structure similar to SBA-15. The average pore size, pore volume and specific surface area of the materials are 6.4nm,0.96 cm3/g and 776 m2/g, respectively.(3) Amino-functionalized H2N-Zr-Ce-SBA-15(H2N-ZCS) and thiol-functionalization HS-Zr-Ce-SBA-15(HS-ZCS) mesoporous materials with unique hexagonal platelet morphologies and short channels were respectively synthesized by post-grafting and co-condensation methods using [1-(2-amino-ethyl)-3-aminopropyl] trimethoxysilane (AAPTS), and 3-mercaptopropyltrimethoxysilane (MPTMS) as organic modifiers. The physical and chemical analysis indicates that AAPTS and MPTMS were successfully grafted to the host mesopores and the functionalized mesoporous materials have unique hexagonal platelet morphologies with short channels and they possess a highly ordered two-dimensional hexagonal mesoporous structure similar to conventional SBA-15. The study on the sorption of organic dye indicates that functionalized mesoporous materials have higher adsorption rates and adsorption capacities compared with conventional SBA-15. The improved performance is attributed to the short channels in the functionalized ZCS materials which facilitate molecular diffusion and quickly achieve the balance of adsorption/desorption.(4) Cu-Mn/ZCS catalyst was prepared by impregnation method. The catalytic activity of the catalyst was evaluated in the model reaction of toluene combustion. The synthetic condition was optimized and the mechanism was discussed. Results indicate that Cu-Mn/ZCS possesses a superior catalytic activity when it was prepared at such conditions as Cu/Mn mass ratio of 1 and 20 wt.% of Cu-Mn, being sintered at 500℃for 4hrs. With such a catalyst, the ignition temperature and total combustion temperature of the toluene combustion was 247℃and 270℃, respectively. The improved catalytic activity was due to the highly distribution of Cu-Mn reactants in the short channels in ZCS and relatively low crystallization degree of Cu-Mn oxides. These results provide a theoretic and experimental foundation for the application of the short channels mesoporous materials in the catalyst field.更多还原