【作者】 金长子；

【导师】 王祥生； 李钢；

【作者基本信息】 大连理工大学 ， 工业催化， 2008， 博士

【摘要】 1983年钛硅分子筛被首次合成,由于其在以H₂O₂为氧化剂、温和条件下进行的有机物分子的选择氧化中具有优异的催化性能,引起了国内外学者的广泛关注。传统的钛硅沸石催化剂具有较高的活性和稳定性,但是狭窄的孔道使得它们不能有效催化大分子的反应。中孔钛硅分子筛的出现在一定程度上解决了这个问题,由于其具有2.0nm以上的宽阔孔道和巨大的比表面积,在大分子的催化转化以及吸附分离等领域中展示出良好的应用前景。然而,与沸石晶体材料不同,中孔钛硅分子筛的孔壁呈无定形,这使得它们的固有催化活性较低,严重限制了它们在工业上的广泛应用。本论文以克服现有钛硅催化材料的缺陷为出发点,在开发新型含钛多孔材料上进行了较为深入的研究。论文的主要内容如下:对Ti-HMS中孔分子筛的合成过程、样品的结构及催化性能进行了研究。研究发现常规的Ti-HMS分子筛的合成体系呈弱碱性,合成Ti-HM9-carboxylicS较为适宜的n（HCl）/n（DDA）为0.07,对应合成体系的pH值为10.72。在合成过程中增加钛源的用量,所得Ti-HMS分子筛中的骨架钛和非骨架钛含量均增加。较高的晶化温度对Ti-HMS分子筛的合成不利。Ti-HMS晶化过程中母液pH值的变化不大。Ti-HMS分子筛具有无序的蠕虫状结构。Ti-HMS分子筛能够满足大分子硫化物氧化反应的要求,而对于受扩散限制不明显的小分子氧化反应,其催化活性不及TS-1分子筛。以水溶性硅酸钠为硅源也可以合成出含钛中孔分子筛Ti-HMS。以TS-1分子筛前驱体溶液为硅源和钛源,长链烷基胺为模板剂,在室温条件下合成出一种新型的具有蠕虫状结构的中孔分子筛Ti-WMS。与常规的Ti-HMS相比,Ti-WMS分子筛的有序度较低,孔壁较厚,骨架中包含TS-1沸石的基本结构单元,并可能具有类似于沸石晶体环境中的骨架钛物种。除了均一的中孔,Ti-WMS分子筛中还含有一定量的微孔。Ti-WMS分子筛具有比Ti-HMS分子筛更强的氧化能力,在小分子硫化物噻吩的氧化脱除反应中表现出更高的活性,而在其它大分子硫化物的氧化反应中Ti-WMS分子筛表现出与Ti-HMS分子筛相当的活性。利用部分晶化的TS-1胶液与十二胺自组装,在室温下制备出一种既包含中孔结构,又含有TS-1沸石相的中孔—微孔复合含钛分子筛Ti-HMS/TS-1。通过对所得样品进行表征和催化性能的考察,发现Ti-HMS/TS-1分子筛中的中孔相与沸石相并非独立存在,沸石的晶粒被包裹或镶嵌于中孔相的团聚体中。Ti-HMS/TS-1分子筛中的中孔相不同于常规的Ti-HMS中孔材料,其孔壁更厚,有序度较低。Ti-HMS/TS-1结合了Ti-HMS和TS-1分子筛的优势,对于噻吩、苯并噻吩和二苯并噻吩的氧化脱除均具有较高的活性。更多还原

【Abstract】 Since titanium silicalite was synthesized first in 1983,it has attracted much attention for its excellent catalytic performance in the selective oxidation of organic molecules with H₂O₂. Though traditional Ti-containing zeolites possess high activity and stability,the narrow channel make thern inacitive in the reactions of bulky molecules.Ti-containing mesoporous silicas have capacious framework pores（＞2.0nm） and large surface area and exhibit high activity in some large molecular reactions.However,the relative lower oxidation ability and stability of these mesoporous materials,arising from the amorphous nature of their pore walls prevent their wide uses in the industrial process.The purpose of this paper is synthesizing novel materials with multiporous and highly active sites,in order to overcome the shortcoming of existing catalytic materials.The paper has the following main contents.The synthesis,characterization and catalytic performance of Ti-HMS mesoporous molecular sieve are studied.It has been shown that traditional Ti-HMS is synthesized under slightly alkaline condition.When the n（HCl）/n（DDA） is 0.07 and the corresponding pH value is 10.72,the obtained Ti-HMS has high quality.With the increase of the amount of titanium source,the contents of both framework and extra-framework titanium species in the products are increased and the optimal n（SiO₂）/n（TiO₂） is 50.Higher crystallization temperature is adverse to the synthesis of Ti-HMS and the pH value of mother liquid change little during the crystallization process.Traditional Ti-HMS possesses wormlike structure.Ti-HMS exhibits excellent performance in oxidation of bulky sulfides.For the reaction of small molecules, however,the activities of Ti-HMS are not as good as TS-1.Ti-containing mesoporous silicas Ti-HMS can also be synthesized with soluble sodium silicate as silica source.A novel Ti-containing mesoporous material with wormlike structure（Ti-WMS） is assembled from the preformed TS-1 precursors with long-chain alkylamine under ambient temperature.The structural and catalytic performances of obtained Ti-WMS have been researched.The results show that comparing with conventional Ti-HMS,Ti-WMS has a lower order degree and a larger wall thickness.Ti-WMS contains the structural units of TS-1 and the zeolite-like active sites.Besides the uniform mesopores,there are some micropores in the Ti-WMS.Ti-WMS possesses highly oxidation ability and exhibits much higher activity than Ti-HMS in thiophene oxidation.In oxidation of some bulky sulfides,Ti-WMS is also active,with similar activities to Ti-HMS.A novel Ti-containing meso-microporous material Ti-HMS/TS-1 is synthesized by assembly of TS-1 gel with partial crystallization with dodecylamine at ambient temperature. The material is characterized by a series of techniques and its catalytic performance is investigated by means of sulfides oxidation.It has been shown that Ti-HMS/TS-1 possesses simultaneously a mesoporous phase and a crystalline zeolitic phase and two phases are composite rather than the physical mixture.In addition,relative to conventional Ti-HMS,the mesoporous phase in the Ti-HMS/TS-1 has lower order degree and larger pore wall thickness and may contain the zeolitic structural units.Ti-HMS/TS-1 combines the advantage of single Ti-HMS and TS-1 and exhibits high activity in oxidation of both bulky and small molecular sulfides.更多还原