【作者】 朱国巍；

【导师】 裘式纶； 王润伟；

【作者基本信息】 吉林大学 ， 无机化学， 2014， 博士

【摘要】 微孔分子筛是晶化硅铝酸盐矿物的一个家族，其结构由均匀分子尺寸的微孔规则排列而成。由于微孔的高比表面积，微孔分子筛有高的气体吸附能力，这个“分子筛”作用使分子大小或择形性的发展应用在吸附分离和催化方面。近些年又有了新的应用，例如在光电子学，传感和药物输送等方面。分子筛在催化方面的巨大成功归因于它们的离子交换能力，固体酸性，骨架稳定性和择形孔径。在大多数分子筛中，三价Al与晶化硅酸盐骨架中的氧形成四配位态。这就引起了Al和氧化物骨架的电荷不匹配，这由非骨架Na+离子弥补，这些Na+离子也可由其他像K+和H+离子所替换。在这些分子筛中，H+离子交换型能呈现出Lewis酸和Br nsted酸中心，酸性相当于硫酸。此外，可通过骨架组成的选择来调节酸强和浓度。有还原-氧化性质的过渡金属，例如Ti，Co和Sn能被合并进分子筛骨架中。钛硅分子筛（TS-1）是高活性多功能的氧化催化剂，尤其是使用H2O2作为氧化剂，在各种催化氧化还原过程中被广泛应用，众所周知，TS-1中骨架钛含量越高，其催化能力越好，而锐钛矿TiO2则加速了H2O2的分解，所以有效地增加骨架钛含量而不形成非骨架钛物种仍然是一个巨大的挑战。此外，由于沸石晶体尺寸和形貌影响了沸石晶体的微孔体积内分散和滞留时间，进而也强烈的影响了其性能，所以晶体尺寸和形貌的控制是重要的。超临界流体由于其独特的溶解性和分散性，在分离技术和化学工程中提供了很多技术优势，在本论文中，研究了在超临界CO2存在下合成TS-1，超临界压力对晶体形貌，结晶度，晶化时间和Ti含量的影响。研究过程中还发现一种简便的方法即在CO2存在下制备富含骨架钛并且没有形成锐钛矿TiO2，制备的晶体具有可控的尺寸和形态。由于沸石L独特的一维孔道结构，在催化剂和可持续能源领域已经吸引了研究者强烈的注意力。其在任何领域都能成功的发挥作用，这与沸石L的尺寸和形状有密不可分的关系。有报道通过加入添加剂来合成沸石L，例如加入氟化物和醇胺。到目前为止，还没有人系统的研究铵盐（无机和有机铵盐）对沸石L合成和性质的影响，那么研究铵盐对沸石L合成和性质的影响是十分必要的，在这项工作中我们系统的研究了无机铵盐和有机铵盐的加入量对沸石L结晶度和形貌的影响。在第二章中，采用了一种新的路线来合成微孔TS-1，即用超临界二氧化碳（SCCO2）作为帮助晶化试剂，在这里超临界二氧化碳起到了双重作用：作为一种添加剂在晶化过程中改变了体系碱度，另外作为媒介消除了传质限制（大量液体之间和通过液体/气体，固体/气体或是固体/液体相界面）。在这个路线中，与没有通入SCCO2的传统合成路线相比，合成的TS-1中Ti含量增加了，但是随着SCCO2压力的增加Ti含量减少，所制备的晶体形态发生了显著变化，TS-1的晶化时间也缩短了。在第三章中，采用在合成凝胶中直接通入不同量的CO2来合成微孔TS-1，CO2起到了碱度调节剂的作用，制备的TS-1催化剂通过XRD，SEM，UV-vis，ICP和IR进行表征，发现骨架钛与总含量均增加了，Si/Ti降低为40，而没引入CO2的传统合成方法为56，形貌发生了变化，由传统的球状转变为孪晶，通入适量的CO2还可以抑制锐钛矿TiO2的生成，催化苯酚羟基化反应的能力有了很大的提高，苯酚转化率达到了26.1%。在第四章中，通过加入不同的添加剂进合成凝胶，进行了L沸石的合成和性质的研究。所有的无机铵盐都抑制了沸石L的晶化过程，不利的影响取决于铵盐的种类和加入的量。随着无机铵盐量的增加，制备的产物中发现有不纯相形成了。令我们惊奇的是除了醋酸按，当其他铵盐加入一定量时，均形成了透长石。而对于有机铵盐PDDA和CTAB的加入，也导致了晶体结晶度的下降，晶体形貌由长宽比为2-4六角棱柱形转变为长宽比为3-6的棒状晶体。通过我们系统的研究说明了LTL晶体的合成对于铵盐的加入是敏感的。而有机硅烷APTMS、TPOAC和TMPED的加入，得到了具有可调长宽比的沸石L晶体，长宽比的大小取决于有机硅烷加入的量。更多还原

【Abstract】 Microporous zeolites are a family of crystalline aluminosilicate mineral, whosestructure is composed by regular array of uniform micropores in a moleculardimension. Microporous zeolites have high gas adsorption capacity due to the highspecifc surface area of the microporous, this ‘molecular sieving’ effect has enabledthe development of molecular size-or shape-selective applications in adsorption,separation and catalysis. New applications, such as optoelectronics, sensing, and drugdelivery, were considered in recent years. The tremendous success of zeolites incatalysis is owing to their ion-exchange capacity, solid acidity and frameworkstability, as well as shape-selective pore diameters. In most zeolites, trivalent Alatoms are tetrahedrally coordinated by oxygen in the crystalline silicate framework.This causes a charge mismatch between Al and the oxide framework, which iscompensated by extra-framework Na+ions, these Na+ions can be exchanged by othercations like K+and H+. In some zeolites, H+-ion exchanged form can exhibit Lewisacidity and also Br nsted acidity, which is comparable to sulfuric acid. Furthermore,the acidity can often be tailored in strength and concentration by the choice of theframework composition. Transition metals with reduction-oxidation property, such asTi, Co and Sn, can be incorporated into zeolite frameworks.Ti-silicalite-1(TS-1) is a highly active and versatile oxidation catalystparticularly using diluted H2O2as oxidant in various catalytic oxy-reductive processes,it is known that, the more framework Ti the TS-1contains, the higher catalyticperformance it would present, while anatase TiO2would promote the decompositionof H2O2, so the effective way to increase the Ti content in the framework of TS-1 without forming extraframework Ti species is still a huge challenge. In addition, thecontrol of zeolite crystal size and morphology can stronglyaffect the performance byinfluencing the diffusion and resident time in the micropore volume of zeolite crystals,so the control of crystal size and morphology is important. Supercritical fluids (SCFs)offer a series of technical advantages in separation technology and chemicalengineering because of their unique solubility and diffusivity properties. In this article,the synthesis of TS-1in SCCO2has been investigated and the effects of supercriticalpressure on crystal morphology and crystallinity, thus on crystallization time and Ticontents have also been studied. In the presence of CO2, a facile method is showed forpreparation of framework Ti-rich TS-1without anatase TiO2, with the controllablecrystal size and morphology. Due to its unique one-dimensional pore structure, zeoliteL has attracted intense research attention in catalyst and in sustainable energy. It hasbeen observed that the successful implementation in either areas is strongly correlatedto the size and the shape of zeolite L. The synthesis of zeolite L though addingadditives have been reported, such as adding fluoride and alkanolamine. Up to now,however, nobody systematically investigated the effect of different ammonium salts（inorganic and organic）on the synthesis and properties of zeolite L. Thus, it wouldbe necessary to investigate the effects of different ammonium salts on the synthesisand properties of zeolite L. In this work, we systematically investigate the amount ofinorganic and organic ammonium salts effect on the morphology and crystallinity ofzeolite L.In the second chapter, a new route to synthesize TS-1has been developed usingthe supercritical carbon dioxide (SCCO2) as a crystallization-assistant agent. SCCO2plays a dual role: as an additive changing the alkalinity during the crystallizationprocess and as a medium eliminating mass-transfer limitations (both within the bulkfluid and across liquid/gas, solid/gas or solid/liquid phase boundaries). In this route, itwas shown that the Ti content in TS-1increase compared with that in the TS-1prepared without SCCO2, but decrease while the SCCO2pressure increase. Theprepared crystal morphology also underwent significant change. The crystallizationtime of TS-1can be shorten a lot. In the third chapter, a new method that CO2was directly added into prepared gelhas been developed to synthesize TS-1, the carbon dioxide (CO2) was used as analkalinity regulator, the resulted TS-1were characterized by XRD，SEM，UV-vis，ICP and IR, that had enhanced framework and total Ti contents, Si/Ti ratio was as lowas40in contrast to the ratio of56prepared through conventional synthesis. Themorphology was changed from the smaller spherical-shape crystal to the larger twincrystal via introduction of CO2. The appropriate amount of CO2can inhibit theformation of anatase TiO2. The catalytic ability to catalyse phenol hydroxylation wasgreatly enhanced, the phenol conversion rate reached26.1%.In the fourth chapter, effects of additives on the synthesis and characteristics ofzeolite L were studied by adding different additives to the synthesis gel. All of theseinorganic ammonium salts inhibited the crystallization process of zeolite L, and theunfavorable effect was dependent on the type and amount of ammonium salts. Theobtained products were demonstrated that the formation of these impurity phases withincreasing amount of ammonium salts. To our great surprise, in addition toCH3COONH4, orthoclase was formed when moderate amount of some ammoniumsalts are added. With the addition of CTAB and PDDA, the crystallinity is decreasing,the crystals were changed from hexagonal prism shape with the aspect ratio of2-4into rod-like morphologywith the aspect ratio of3-6. Our systematic approachdemonstrates the syntheses of LTL crystals are sensitive to the presence ofammonium salts in the synthesis gel. While zeolite L crystals with tuning aspect ratiowere obtained throughadding these organosilanes（APTMS、TPOAC and TMPED）,and the sizes of aspect ratio depend on the organosilanes concentration.更多还原