【作者】 赵忠林；

【导师】 吴鹏；

【作者基本信息】 华东师范大学 ， 物理化学， 2009， 博士

【摘要】 本文以提高沸石分子筛催化活性中心的可接近度，改善其扩散性能，扩大沸石分子筛在处理大分子反应物方面的应用范围为目的，在含有介孔的杂原子分子筛的制备和层状分子筛层间结构改性两个方面，开展了以下四部分研究工作。首先，我们在常规TS-1合成体系中引入两亲有机硅烷，以期在其辅助作用下一步合成出含有介孔的TS-1分子筛，合成过程中各因素的影响进行了考察，所得样品的催化性能通过正己烯和环己烯反应进行了表征，并与常规TS-1分子筛进行了比较。结果表明，合成体系中两亲有机硅烷的用量和体系碱度是影响最终样品结构的最重要因素，两亲有机硅烷用量较低时很难将均一介孔引入到最终样品，而用量较高时则抑制体系晶化。在两亲有机硅烷用量一定的条件下体系碱度越高越不利于含有均一介孔的材料的形成。通过优化实验条件，我们成功得到了既拥有高结晶度和良好的活性中心配位状态又拥有孔径为3．7nm的均一介孔孔道的TS-1分子筛。含有介孔的TS-1虽然在正己烯反应中与常规TS-1差别不大，但由于介孔孔道增加了大分子反应物与催化剂活性中心接触的机会同时改善了扩散性能，其在环己烯环氧化反应中表现出近2．5倍于常规TS-1的催化活性，同时凭借着较为疏水的表面，含有介孔的TS-1有效避免了目的产物环氧化物的开环，因此其对环氧化物的选择性是常规TS-1的2倍。依照相同的实验策略，我们在常规Zr-MFI的合成体系中引入两亲有机硅烷，以期通过一步法合成出含有均一介孔的Zr-MFI分子筛。合成体系中有机硅烷用量及锆含量对最终样品性能的影响进行了考察，样品的Lewis酸催化性能通过环己酮的Meerwein-Ponndorf-Verley（MPV）反应进行了表征，并与常规Zr-MFI分子筛进行了比较。结果表明，在两亲有机硅烷的辅助作用下不同含锆量（合成体系中Si/Zr≤100）的含有介孔的Zr-MFI被成功合成出来。新材料不仅拥有常规Zr-MFI的高结晶度和0．55nm的微孔孔道，而且拥有一个孔径为3．5nm的均一介孔孔道。此外相比于常规Zr-MFI，含有介孔的Zr-MFI拥有更多的Lewis酸催化中心和更为疏水的表面。含有介孔的Zr-MFI在环己酮的MPV反应中表现出的催化活性是常规样品的30倍，其单位催化中心的催化性能甚至优于介孔含锆材料。此外，含有介孔的Zr-MFI催化剂在环己酮MPV反应中表现出良好的稳定性，可以重复使用。再次，我们以MCM-22分子筛层状前驱体为出发点，尝试采用先室温溶胀，再利用有机硅烷插层的新结构改性方法。MCM-22层状前驱体的溶胀程度，有机硅烷类型，插层过程中有机硅烷用量及体系酸度等因素对最终样品结构的影响进行了考察，并与已报道的利用含有单个硅的有机硅烷Me₂Si（OEt）₂对MCM-22分子筛层状前驱体直接进行插层处理得到的MCM-22（Si）进行了比较。通过优化实验条件，我们成功得到了MCM-22（Si-Si）、MCM-22（Si-O-Si）、MCM-22（Si-CH₂-CH₂-Si）和MCM-22（Si-benzene-Si）等一系列既较好地保留了MCM-22分子筛层状前驱体的层内结构和晶体形貌，又实现了层间扩张的扩孔型MWW分子筛。而且相比于MCM-22（Si），新方法所得到各材料层间距要大2．0（?）左右。即通过对分子筛层状前驱体先溶胀再插层的新结构改性方法，可以制备出较一步插层得到的材料层间扩张程度更大的扩孔型分子筛。最后，我们以镁碱沸石层状前驱体（PREFER）为出发点，选择ClMe₂Si-SiMe₂Cl、ClMe₂Si-O-SiMe₂Cl、ClMe₂Si-CH₂-CH₂-SiMe₂Cl和OHMe₂Si-benzene-SiMe₂OH等一系列有机硅烷在酸性条件下对其进行插层后处理，以拓宽利用有机硅烷制备层间扩孔型分子筛这一方法的适用范围。后处理过程中有机硅烷的种类，有机硅烷的用量及体系的酸度等因素对最终样品结构的影响进行了考察，并与已报道的利用含有单个硅的有机硅烷Me₂Si（OEt）₂对PREFER进行插层处理得到的FER（Si）进行了比较。通过优化实验条件，我们成功得到了FER（Si-Si）、FER（Si-O-Si）、FER（Si-CH₂-CH₂-Si）和FER（Si-benzene-Si）等一系列既较好地保留了PREFER的层内结构和晶体形貌，又实现了层间扩张的扩孔型FER分子筛。相比于FER（Si），本实验中利用大分子有机硅烷所得的新材料层间距最高可扩大2．0（?）左右，而且通过改变有机硅烷的类型，所得扩孔材料的层间距可以在一定范围内进行调变，这为其进一步在不同大小分子的催化反应中的应用奠定了基础。更多还原

【Abstract】 The dissertation has been carried out to increase the accessibility of the catalyticactive sites in the framework of zeolite and then to improve the diffusion properties ofzeolite so as to broaden the scope of its utility.The researches are composed of twotopics,one of which is the synthesis of mesoporous metallosilicates and the other isthe interlayer expansion of zeolitic lamellar precursors by post-silylation.Firstly,mesoporous TS-1 were hydrothermally synthesized with the aid ofamphiphilic organosilane and the effects of various parameters on the structural andtextural properties of the resultant materials were investigated.The physicochemicalproperties of the samples were characterized by various techniques and their catalyticperformance was investigated by the epoxidation of hexene and cyclohexene withhydrogen peroxide.The content of organosilane added was essential for the formationof uniform mesopore in TS-1,and it greatly influenced the crystallinity.The basicityof the synthesis system also was of importance as high basicity did not contribute tothe formation of uniform mesopore.By optimizing the synthesis conditions,highlycrystallized TS-1 with uniform mesopores of 3.7 nm diameter was successfullysynthesized.The mesoporous TS-1 preserved tetrahedrally coordinated Ti ions in theframework,but it was featured with more hydrophobic surface and less defect sites incomparison to conventional TS-1.Mesoporous TS-1 showed a higher conversion forthe epoxidation of cyclohexene owing to an easier access of bulky molecules to thecatalytic active sites,while showing similar activity for the epoxidation of hexene incomparison to conventional TS-1.Besides,mesoporous TS-1’s higher hydrophobicitymade its epoxide selectivity two times as much as that of conventional TS-1.Under similar approach,mesoporous Zr-MFI with different Zr contents werehydrothermally synthesized with the aid of amphiphilic organosilane.Theirphysicochemical properties were characterized by various techniques,and theircatalytic performance was investigated for Meerwein-Ponndorf-Verley （MPV）reduction of cyclohexanone with 2-propanol.The mesoporous Zr-MFI preserved theproperties of conventional Zr-MFI such as high crystallinity and incorporation oftetrahedral Zr ions in framework,and was further featured with mesoporosity of 3.5nm diameter,enlarged external surface area,more Lewis acid sites and less defectsites.Compared with conventional Zr-MFI,the mesoporous Zr-MFI showed drastically improved activity for the MPV reduction of cyclohexanone,which waspredominantly attributed to the contribution of the mesopores supplying an easieraccessibility to the catalytic active sites for bulky molecules.Moreover,themesoporous Zr-MFI was a stable and reusable catalyst.Then,interlayer expanded MCM-22 was prepared by a new postsynthesismethod,that is swelling the precursor of zeolite MCM-22 （MCM-22 （P）） under roomtemperature firstly and then silylating the swollen materials with ClMe₂Si-SiMe₂Cl,ClMe₂Si-O-SiMe₂Cl,ClMe₂Si-CH₂-CH₂-SiMe₂Cl and OHMe₂Si-benzene-SiMe₂OHin nitric acid solution.The effects of postsynthesis conditions such as theconcentration of nitric acid solution and the amount of silylation agent on thestructure of final samples were investigated in details.The resultant samples preparedunder the most optimized conditions preserved highly crystallized MWW intralayerstructure and had much larger interlayer space of 2.0 （?） in comparison to that ofMCM-22 （Si） prepared by silylation of MCM-22 （P） directly with monomeric Sisource （Me₂Si （OEt）₂） as reported before.That is to say,the new postsynthesis methodis more effective for the synthesis of interlayer expanded MCM-22 with largerinterlayer space.Finally,FER with expanded interlayer pore windows was synthesized bysilylating the precursor of FER zeolite （PREFER） with ClMe₂Si-SiMe₂Cl,ClMe₂Si-O-SiMe₂Cl,ClMe₂Si-CH₂-CH₂-SiMe₂Cl and OHMe₂Si-benzene-SiMe₂OHin nitric acid solution.The effects of postsynthesis conditions such as theconcentration of nitric acid solution and the amount of silylation agent on thestructure of final samples were investigated.The structure of the resultant materialswere compared with the sample prepared with monomeric Si source （Me₂Si （OEt）₂）under the same conditions.Results evidenced that by optimizing the postsynthesiscondition,samples with larger interlayer space with comparison to that of FER （Si）can be synthesized with newly chosen silylation agent.Besides,the interlayer space ofFER can be modified by varying the silylation agent,which is helpful for its use incatalytic process involving substrates with different molecular dimensions.更多还原