【作者】 马广伟；

【导师】 葛学贵；

【作者基本信息】 中国地质大学 ， 矿物学、岩石学、矿床学， 2003， 硕士

【摘要】 论文研究意义沸石类分子筛由于具有均匀规整的、分子大小的孔道结构和巨大的表面积而导致的择形性质，被广泛用作吸附剂、催化剂以及离子交换剂等；又由于具有良好的热稳定性、化学稳定性和生物稳定性等优点，在环保工程、生物工程、石油化工、食品医药、精细化工、农林业、宇航、电子、新材料等国民经济众多部门及高科技领域有广泛的用途。微孔分子筛是现代石油工业中重要的择形催化剂，然而由于孔径较小，一方面大直径分子进入孔道困难，另一方面在孔道内形成的大分子不能快速地逸出，常导致副反应发生，而使其应用范围受限。自从1992年Mobile 公司合成出M41S系列中孔分子筛以来，中孔分子筛的合成技术、性能表征及结晶机理等问题一直是国际上研究的热点。但由于中孔分子筛的孔径均匀单一，处理复杂气体组份时受到限制，而且，中孔分子筛由于孔壁较薄，高温下孔道容易坍塌，所以其在工业上的应用也受热稳定性的限制。复合分子筛既有中孔结构又有微孔结构，既有强酸位又有弱酸位，这种多重结构的双重酸位和具有叠加功能的分子筛，可避免单一孔结构的缺陷，在处理诸如汽车尾气、工厂废气等组分复杂、分子孔径大小不一的混合物时适用性更强。复合分子筛由于中-微孔相共存，并且形成过程中，中孔孔壁可能发生再结晶，变得较厚，相应热稳定性提高，适用性更强。因为复合分子筛具有多个催化中心、比表面积大、热稳定性高等优点，在石油化工和环保等领域有着潜在的应用价值。近年来，杂原子负载于中孔分子筛作为催化剂引起了人们的广泛兴趣。将过渡金属或稀土离子引入分子筛也一直是人们比较重视的课题。由于这些金属离子具有较高的电荷密度，含有这些离子的分子筛脱水后含有的酸位多，催化活性较高。另外，稀土分子筛具有较高的热稳定性和抗水蒸汽性能，可广泛应用于石油化工领域。 目前，人们已经成功的将杂原子Al、Ti、W、V等引入到中孔分子筛骨架，并在相应的探针反应中显示出了良好的催化活性。关于稀土元素负载的微孔沸石分子筛的报道较常见，但关于稀土元素负载的中孔分子筛的研究、稀土元素进入分子筛骨架的研究和稀土元素引入复合分子筛方面的研究还未见报道。 论文主要研究内容及结论1. 通过控制不同的条件，分别合成了中孔分子筛MCM-41和微孔分子筛ZSM-3，应用XRD、IR、Raman光谱进行表征，结果证明，样品为中孔分子筛和微孔分子筛。2. 以少量的ZSM-3为预置晶种，以CTMAB和TMAOH为模板剂，用水热合成法合成出了同时具有中孔和微孔结构的复合分子筛MCM-41/ZSM-3，经XRD、IR、SEM、N2吸附脱附等温线及孔径分布曲线结果证明，合成样品和机械混合物有明显差别。样品为中微孔复合的分子筛，孔径集中分布在0.7nm和3.3nm。通过控制不同的合成温度，以表面活性剂CTMAB为单一模板剂，合成出了双中孔的复合分子筛，经XRD、IR和N2 吸附－脱附等温线表征，结果证明，分子筛为中－微孔复<WP=6>3. 合分子筛，中孔孔径集中在3nm和11nm左右。4. 利用水热合成方法合成出镧负载的中孔分子筛La-MCM-41，XRD、IR、Raman光谱分析结果表明，镧进入了分子筛骨架；以硅酸钠为硅源合成La-MCM-41时，最佳合成温度为100℃左右；以正硅酸乙酯为硅源时，最佳合成温度120℃左右。在100℃左右，以硅酸钠为硅源有利于形成中孔物相，且结晶度较好；而同温度下，以正硅酸乙酯为硅源，结晶度较低，不易形成中孔物相。在120℃左右，以硅酸钠为硅源可生成微孔物相，而不利于形成中孔物相；但以正硅酸乙酯为硅源，可形成结晶度较好的中孔物相，但晶面间距变小。溶液中镧离子的存在，对中孔物相的形成有一定的阻碍作用。5. 利用孔道修饰法合成了稀土镧孔道负载的中孔分子筛，XRD、IR、Raman光谱表征证明，镧取代孔道中的钠后，和硅氧四面体中的非桥氧成键，且键的力常数较大。6. 利用水热合成方法合成出了镧负载的复合分子筛La-MCM-41/ZSM-3，XRD、IR、RAMAN光谱分析结果表明，镧进入复合分子筛骨架。7. 利用孔道修饰法合成了孔道负载的复合分子筛，XRD、IR、Raman光谱表征说明，镧取代孔道中的钠后，和硅氧四面体中的非桥氧成键。 8. 探讨了分子筛的形成机理，并借助实验，讨论了复合分子筛的固相形成机理的合理性。主要特色及创新1. 本文在前人研究的基础上，用预置晶种的方法，首次合成了孔径集中分布在0.7nm和3.3nm的MCM-41/ZSM-3复合分子筛；用控制不同温度的方法，首次合成了中孔孔径集中分布在3nm和11nm左右的复合分子筛MCM-41/D沸石。2. 首次利用水热合成方法合成出了镧骨架负载的中孔分子筛La-MCM-41；应用孔道修饰法，合成出了镧孔道负载的中孔分子筛。3. 首次用水热合成方法合成出了镧骨架负载的复合分子筛MCM－41/ZSM-3，应用孔道修饰法，合成了孔道负载的复合分子筛。更多还原

【Abstract】 Research significance In virtue of the homogeneous molecular size pore structure and huge surface leading to selective adsorption, zeolite is widely used as adsorbent, catalyst and ion exchanging agent. Zeolite molecular sieves, due to their good thermal stability, chemical stability and biological stability, have been used in environment protection, biology engineering, petroleum chemistry, foodstuff, medication, agriculture, electronics industries and new materials fields. Microporous molecular sieves are important selective catalysts in petroleum and chemical industry. But their applications are limited because of small pore sizes, since big molecular are difficult to enter into the pores, at the same time big molecular produced in the pores are difficult to transgress, which results in side-reaction. Since Mobile Co. synthesized a series of mesoporous molecular sieves in 1992, the synthesis technology, properties testing and the study of crystallization mechanism have been the hot topic worldwide. However, because the pore sizes of mesoporous molecular sieves are simplex, their uses are impaired when dealing with complex gas group. As a result, the applications of mesoporous molecular sieves are limited. Moreover, the pore walls of mesoporous molecular sieves are thin, vulnerable to collapse at high temperatures. Obviously, the weak thermal stability also limits their wide application. Composite molecular sieves have mesoporous and micro-pore structures, and strong and week acid bit. This kind of structure can avoid the limitation of simplex pore structures, and has better adaptability when dealing with mixture of different molecular sizes, such as automobile gas, waste gas in factories. Because the mesoporous and micro-pore structures coexist in composite molecular sieves, and the pore walls become thick during the second crystallization, the thermal stability improves greatly. Also because the composite molecular sieves have multi-catalysis focuses, huge specific surface area, good thermal stability, they have potential applications in petroleum and chemical industry, environment protection and so on. Recently, the atom impurity adulterated mesoporous molecular sieves as catalysts have aroused extensive interests. Because the metal ions in them have high electric density, molecular sieves containing these metal ions have more acid bits and good catalyzing activity. Therefore, it is an important project to introduce transition metal ions and rare earth ions into molecular sieves. The molecular sieves with rare earth ions have high thermal stability and anti-vapor capability, so they are widely used in petroleum and chemical industry fields. At present, the impure atoms, such as aluminum，copper，tungsten, have been successfully introduced into the molecular sieves framework, and the molecular sieves show good catalyzing activities. It is ordinary for micro-pore molecular sieves to adulterate rare earth, but less ordinary for mesoporous molecular sieves, still less for the rare earth atoms to enter into<WP=8>molecular sieves framework. Further, there are no reports of composite molecular sieves with rare earth element adulteration. Brief researches and conclusions 1. Meso-pore molecular sieves MCM-41 and microporous molecular sieves ZSM-3 were synthesized by controlling different temperatures. The results of XRD, IR and Raman spectra show that the samples are virtually mesoporous and micro-pore molecular sieves.2. By use of CTMAB and TMAOH as the templates, meso-microporous composite molecular sieves were hydro-thermally synthesized. The as-synthesized composite molecular sieves have diffraction peaks in small and large angle regions in their XRD patterns, corresponding to the mesoporous and micro-pore structures. The IR spectra show that the as-synthesized samples have characteristic absorption bonds of mesoporous MCM-41 and micro-pore ZSM-3 molecular sieves, and their IR spectra are clearly different from those of the mechanical mixtur更多还原