【作者】 张文；

【导师】 李保山；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2012， 硕士

【摘要】 MCM-41型介孔分子筛具有六方排列的规则孔道、大比表面积、大孔容、均匀分布的孔径、组分可调控等特点，但由于其骨架缺陷较少，催化活性中心较弱的缺陷，极大地限制其在催化领域的应用。在分子筛的众多改性方法中，引入杂原子是其改性的重要手段之一。杂原子的引入首先会对分子筛的结构产生调变作用，改变其孔径和比表面积大小；并且杂原子金属本身也会具有某些特殊的催化性能，为功能性催化剂的设计提供一种途径。催化剂活性组分通常为比较贵的金属元素，为了有效的利用这些活性组分，一般将活性组分分散在大比表面积的载体上。高温焙烧和高温还原易造成金属活性组分的迁移集聚，导致金属组分分散度降低，但这恰恰是金属催化剂传统制备方法中的必经步骤，会对催化材料的性能造成很不利的影响。本论文通过条件温和的水热合成法，以NH3作为配体和金属Ni2+形成配合物[Ni(NH3)6]2+，避免了金属Ni2+生成氢氧化物沉淀，以S+I-I+I-机理为理论基础合成出了一系列骨架金属Ni-MCM-41介孔分子筛，综合利用多种测试手段对样品的结构、Ni在分子筛中的配位状态及分子筛的稳定性能进行了表征。结果表明：高含量的Ni主要以四配位体的结合方式均匀分布于Ni-MCM-41分子筛样品的骨架中，完整的保持了MCM-41型介孔分子筛特有的六方孔道结构。在此基础上，以Ni-MCM-41为前驱体，利用其金属Ni高度分散于骨架，并与骨架硅原子有较强相互作用的特点，通过H2还原得到金属镍高度分散的介孔分子筛。论文的主要研究成果有：1、利用水热合成法，成功合成出了高Ni含量的介孔分子筛Ni-MCM-41，研究了分子筛的合成工艺条件。分析测试结果表明：Ni-MCM-41中金属Ni含量可高达16.3wt%，不同Ni含量分子筛的孔径约为2.77-3.16nm，孔容为1.05-1.22cm3g-1，比表面积为580-800m2g-1，并且该类分子筛具有MCM-41型介孔分子筛特有的六方孔道结构。2、以Ni-MCM-41为前驱体，通过H2还原制备得到金属型高分散Ni·MCM-41介孔分子筛。分析测试结果表明：金属Ni高度分散于介孔分子筛基体中，Ni金属的平均颗粒小于20nm，均匀分散，同时该类分子筛依然保持了MCM-41型介孔分子筛特有的六方孔道结构。3、以焦化蜡油为原料，考察了骨架型介孔分子筛Ni-MCM-41样品的加氢裂化催化性能。结果表明：该类催化剂对焦化蜡油加氢裂化显示出了较高的转化率（70.0~83.0%）和较高的低沸点烃类产物的选择性（78.0~81.3%）。更多还原

【Abstract】 MCM-41is a type of mesoporous molecular sieve with uniformlyhexagonal pore structure， large specific surface area and excellentadsorption property.It is an important method to introducing heteroatominto molecular sieves for modification of the characters. On one hand, theintroduced heteroatoms may lead to the charge disequilibrium ofmolecular sieves bringing more acid sites. On the other hand, heteroatomwith inherent characteristics makes the molecular sieves asmulti-functional catalysts. Generally speaking, the active sites of catalystare noble metallic element. In order to take advantage of these active sites,those are dispered on the surface of carriers with large specific surfacearea. High-temperature calcination and reduction are essential in thetraditional preparation method of metal catalyst, which can make themetal components transfer and assemble reducing the dispersion andhaving bad effects on the catalyst.In this thesis, a series of Ni-MCM-41mesoporous molecular sieveswere synthesized through a facile hydro-thermal method basing onS+I-I+I-synthetic mechanism, in which NH3was used as coordination agent coordinating with Ni2+to form [Ni(NH3)6]2+avoiding theprecipitation of Ni2+. The structure of samples, the coordination status ofNi and the stability of molecular sieves were characterized with acollection of testing measures. The results turned out that the Ni contentis up to16.3wt%highly dispersed in the silica framework and the typicalhexagonal pore structure was still existed. Further more, in this thesis,highly dispersed metal catalysts were obtained using Ni-MCM-41asprecursor, taking advantages of the strong interaction between Ni and Siin the framework. The main research results are as following:1. Mesoporous molecular sieves with high Ni content Ni-MCM-41were successfully synthesized and the characterization results confirmthat the Ni content is up to16.3wt%, pore diameters are about2.77-3.16nm, pore volume are1.05-1.22cm3g-1and specific surface areas are580-800m2g-1. At the same time, the typical hexagonal pore structurewas still existed.2. Highly dispersed metal catalysts were obtained by reduction usingNi-MCM-41as precursors. The characterization results confirm that theNi particles under20nm were highly dispersed on the surfaces ofmesoporous molecular sieves, and the typical hexagonal pore structurewas still existed.3. In this thesis, the catalytical performance of Ni-MCM-41hasbeen investigated through hydrocracking of coker wax oil. The results reveal that these sort of catalysts showed high conversions (70.0~83.0%)and selectivity of low boiling point hydrocarbons (78.0~81.3%), these areexcellent catalysts for hydrogenation.更多还原