【作者】 刘鑫；

【导师】 刘洪涛； 汪杰；

【作者基本信息】 北京化工大学 ， 化学工程（专业学位）， 2020， 硕士

【摘要】 ZSM-5分子筛在催化裂化、烷基化、芳构化等石油加工过程中起着重要的作用。但其较小的孔径限制了活性中心对大分子的可接近性,进而限制了其催化作用的发挥,因此在微孔中引入介孔构建多级孔分子筛可以降低微孔的位阻效应,对于提高大分子的催化转化至关重要。本文采用了几种方法在常规分子筛中引入介孔进而得到多级孔择形分子筛:1.以晶种和实验室自行合成的有机模板剂(Mesotemp)协同合成了多级孔ZSM-5分子筛,其中Mesotemp的加入会引导其与硅铝凝胶的结合,形成有序的中间相。此外晶种导向固有ZSM-5晶体结构的形成,锚定的Mesotemp引导晶内介孔的形成。对最佳条件下样品进行1 L放大合成,得到的多级孔ZSM-5相对结晶度为93%,总比表面积达到371.2 m2.g-1,介孔比表面积达到127.4 m2.g-1。2.以月桂酰胺丙基氧化胺(LAO)为介孔模板剂,四丙基溴化铵(TPABr)为微孔模板剂合成了多级孔ZSM-5分子筛。其中TPABr决定了是否导向MFI结构。通过XRD和BET表征发现LAO能够调节介孔孔隙率。合成的多级孔ZSM-5样品相对结晶度为95.6%,总比表面积达到397.8 m2.g-1,介孔比表面积达到150.6 m2.g-1,介孔孔容增大到0.10 cm3.g-1,孔径为3.5 nm。3.以氟硅酸铵溶液处理Y型分子筛,其通过脱铝补硅得到了多级孔高硅铝比Y。因在脱铝过程中会发生骨架坍塌所以合成样品的相对结晶度和骨架硅铝比成相反关系。多级孔高硅铝比Y型分子筛的相对结晶度保留60%以上,SiO2/Al2O3达到32.8,总比表面积达到450.5.5m2·g-1,介孔比表面积达到102.3 m2·g-1,平均孔径为3.3 nm。更多还原

【Abstract】 Zeolite ZSM-5 has been emerging as the one of the most promising active components in many chemical processes,such as catalytic cracking,alkylation and aromatization.However,one key problem remains unresolved in this typical shape-selective zeolite:its small pore size which limits the accessibility of active centers to macromolecules,remains far from application of conversion of large molecules.Therefore,the obtainging of hierarchical ZSM-5 by the introduction of mesoporous structure in the micropores remains a great challenging goal.1.In this article,a hierarchical ZSM-5 zeolite was synthesized by the synergy of crystal seed and bifunctional template(Mesotemp).Specifically,the addition of Mesotemp would lead to the bind formation of silica-aluminum gel with Mesotemp and the obtaining of well-ordered mesophase.On the other hand,the intrinsic ZSM-5 crystals would be inherited from crystal seeds.The intracrystalline mesopores were formed from the anchored Mesotemp.The hierarchical ZSM-5 obtained had a relative crystallinity 93%,total specific surface area 371.2 m27·g-1,mesoporous specific surface area 127.4 m2·g-1 by 1 L amplification under the optimal conditions.2.The hierarchical ZSM-5 zeolite was synthesized using TPABr as microprogen,and LAO as mesoprogen.TPABr determined whether to guide the MFI structure.From XRD and BET studied,it can be seen that adjusting of the mesoporous porosity can be achieved by the introduction of LAO.The hierarchical ZSM-5 obtained had a relative crystallinity 95.6%,total specific surface area 397.8 m2·g-1,mesoporous specific surface area 150.6 m2.g-1.It is very interesting that the mesoporous pore volume increased to 0.10 cm3·g-1,and average pore diameter was 3.5 nm.3.The hierachical zeolite Y with high Si/Al ratio was obtained by dealuminization and silicon supplementation in ammonium fluosilicate.In this strategy,an inverse trend of the relative crystallinity and Si/Al ratio can be observed due to collapse of skeleton in the process of dealuminization.The hierarchical high-silica Y obtained had a relative crystallinity more than 60%,SiO2/Al2O3 ratio 32.8,total specific surface area 450.5 m2·g-1,mesoporous specific surface area 102.3 m2·g-1,and average pore diameter 3.3 nm.更多还原