【作者】 杨贺勤；

【导师】 谢在库；

【作者基本信息】 华东理工大学 ， 工业催化， 2010， 博士

【摘要】 近年来,复合孔结构的沸石整体材料引起了人们的广泛关注。由于复合孔整体材料是在介孔／大孔的孔壁中引入一定数目的沸石晶粒,因此这种材料除了具有一体成型的形貌外,还具有介孔或大孔材料开阔的孔道结构,以及沸石微孔材料强酸性和高活性的性能,这使它有可能成为集组成、结构和性能一体化的多功能催化剂,因此具有潜在的应用价值,可望在催化、环保以及新材料等领域得到广泛的应用。本论文采用溶胶-凝胶和相分离结合的方法制备了同时具有贯通大孔和有序介孔的硅铝氧化物整体材料、钛硅氧化物整体材料以及硅磷铝氧化物整体材料,并通过干凝胶转化的方法成功制备出相应的沸石化整体材料,同时,对合成材料的催化性能进行了考察,具体研究方法和结果如下：1.采用相分离和模板支撑相结合的方法制备了具有贯通大孔和有序介孔的无定形硅铝氧化物整体材料。通过改变相分离剂和三嵌段共聚物的加入量可以对材料的大孔和介孔孔径分布实现有效调控。该材料在1,3,5-三异丙基苯的催化裂解反应中表现出较高的转化率和稳定性。2.采用干凝胶转化的方法成功制备出具有贯通大孔的Beta分子筛整体材料。无定形硅铝氧化物的大孔孔壁在维持双连续大孔结构的同时,部分转晶生成了Beta纳米晶粒。与传统的Beta分子筛相比,复合孔结构的Beta分子筛整体材料在多异丙苯的烷基转移反应中表现出较高的活性和稳定性。3.采用溶胶凝胶法和气相接枝法制备了具有贯通大孔和有序介孔的无定形钛硅氧化物整体材料。该材料经过硅烷化处理后,表面疏水性增强,酸性下降,在环己烯环氧化反应中表现出比非硅烷化复合孔结构钛硅氧化物以及硅烷化的SBA-15分子筛更高的转化率和选择性。4.采用干凝胶转化的方法成功制备出具有贯通大孔的钛硅沸石分子筛整体材料。沸石化后,材料的大孔孔壁由钛硅沸石纳米晶粒组成,材料中的钛原子仍以四配位状态存在。氯丙烯环氧化反应结果表明,贯通大孔的钛硅沸石分子筛整体材料具有较高的转化率和选择性。5.采用相分离的方法制备了具有双连续大孔结构的硅磷铝氧化物整体材料。在材料的制备过程中,通过调变相分离剂PEO、凝胶剂PO和陈化温度可以实现对大孔形貌和孔径分布的有效调控。6.采用干凝胶转化的方法制备了不同形貌的复合孔结构的SAPO-34分子筛整体材料。分析结果表明,P／Al和晶化方法的改变对分子筛的形貌有较大的影响；Si/Al的调变主要对材料的酸性起着决定性的作用；晶化时间和晶化温度对晶核的形成和生长有着重要的影响；而模板剂的种类制约着分子筛的类型。7.甲醇转化制低碳烯烃反应结果表明,相对于传统SAPO-34分子筛,复合孔结构SAPO-34分子筛,无论是在甲醇和二甲醚的转化率上,还是在乙烯和丙烯的收率上,都表现出较高的反应活性和稳定性。其中球状SAPO-34分子筛在反应中表现出相对较高的活性,而层状结构的SAPO-34则表现出较好的稳定性。更多还原

【Abstract】 Zeolite monoliths with hierarchical porosity have attracted much attention due to their potential applications in the industrial fields. These materials have been proven to be the promising catalysts because the incorporation of interconnected macropores in microporous materials not only greatly increases mass transfer but also makes reactant easier access to the active sites, which favors the improvement of the catalytic performance. In this dissertation, we first prepared meso/macroporous aluminosilica monoliths, titania-silica monoliths and silicoaluminophosphate monolith by phase separation in sol-gel process, and then by the dry gel conversion technology, we got zeolite monoliths with hierarchical porosity. Finally, we investigated the catalytic performance of these zeolite monoliths with hierarchical porosity respectively. The main results in this dissertation are shown as follows:1. Aluminosilica monoliths with bicontinuous macropores and ordered mesopores were successfully prepared by phase separation combined with template technique. The bimodal meso-macroporous structure can be respectively controlled through adjusting PEG amount, surfactant amount and surfactant kinds. The aluminosilica monolith with bicontinuous macropores and ordered mesopores showed best performance on the cracking 1,3,5-Triisopropylbenzene reaction compared with other aluminosilica monolith.2. Bicontinuous beta zeolite monolith was prepared by the dry gel conversion technology. The results showed that the amorphous skeletons of the original silicoalumin monolith are partly converted into zeolite structure with maintenance of the bicontinuous structure. Moreover, catalytic performance of the hierarchical beta zeolite prepared via dry gel conversion method has higher activity and better stability for the transalkylation reaction in the liquid catalytic circumstance.3. Titania-silica monoliths with bicontinuous macropores and interconnected mesopores were successfully prepared by sol-gel method and vapor-phase grafting method. The hydrophobicity of the titania-silica monolith was improved after silylation. The results showed the titania-silica monolith with hierarchical porosity modified by silylation showed enhanced catalytic activity in the epoxidation of cyclohexene compared with SBA-15 silylanized.4. TS-1 zeolite monoliths with bicontinuous macropores were prepared by the dry gel conversion technology. TS-1 zeolite crystals were formed and the bicontinuous macroporous structure was not destroyed during the crystallization process, and the Ti species were incorporated into the skeletons of TS-1 zeolite monolith with tetrahedral coordination. Moreover, catalytic performance of the hierarchical TS-1 zeolite monolith prepared via dry gel conversion method has higher activity and selectivity due to the existence of bicontinuous macropores and interconnected mesopores, which make zeolite crystals fully exposed and make materials possess better mass transfer.5. Silicoaluminophosphate monoliths were prepared by phase separation in sol-gel process. The results showed that the macropore morphology and macropore size distributions could be controlled by adjusting PEO amount, PO amount and aging temperature.6. Hierarchical SAPO zeolite monoliths with different morphology were prepared by the dry gel conversion technology. The results showed that P/Al molar ratios and crystallization methods have an important effect on zeolite morphology; Si/Al molar ratios influence the acidity of zeolite; crystallization time and crystallization temperature determined the formation and growth of crystalline nucleus; template kinds work on zeolite type.7. The catalytic activity of hierarchical SAPO-34 zeolite monoliths with different morphology was investigated for methanol conversion to light olefins (MTO) reaction. The results showed that hierarchical SAPO-34 zeolite monoliths have higher catalytic activity and better stability compared with the conventional SAPO-34 zeolite. Moreover, it is also found by comparison that the hierarchical SAPO-34 with sphere-shaped morphology exhibits higher catalytic activity and the hierarchical SAPO-34 with layer-shaped morphology possess better stability.更多还原