介孔在ZSM-5分子筛体系中的构建
发布时间：2018-12-26 07:19
【摘要】：多级孔结构的ZSM-5型分子筛克服单独微孔分子筛扩散局限性问题,可以提高重油等大分子对活性中心的可接近性,提高催化效率,在重油催化裂化中具有良好的应用前景。使用有机胺模板剂合成ZSM-5分子筛是研究较多的方法,目前存在的问题:(1)模板剂成本高、产率低、存在污染。(2)合成工艺复杂且产生介孔难以调控,易发生相分离。为解决以上问题,利用两亲性有机硅烷和晶种辅助的方法制备多级孔ZSM-5分子筛。晶种可以诱导微孔的生成,有机硅烷TPHAC通过亲水端与晶化体系中硅铝凝胶或者部分溶解的晶种表面硅羟基键合,疏水端的烷基长链通过自组装作用形成的胶束引导介孔生成,进而引入分子筛孔道。该体系下最佳条件进行10 L放大合成:晶化温度170 ℃,晶化时间18 h,模板剂用量3.12 g,水浴温度50 ℃,搅拌速率500 r/min。产物的总比表面积为367.3 m2/g,介孔比表面积为110.1m2/g,总孔容为 0.312cm3/g,介孔孔容为 0.178cm3/g。利用TPHAC和TPABr双模板合成多级孔ZSM-5分子筛。研究发现,有机硅烷溶液中的乙醇含量影响有机硅烷临界胶束浓度。乙醇质量的增加,会提高TPHAC的临界胶束浓度导致胶束尺寸减小,孔径分布集中,一定程度上与模板剂具有协同作用。过量的乙醇会阻碍胶束的聚集以及与晶种的键合作用,导致TPHAC在该体系中胶束状态的变化,TPHAC的多聚物数量增加,导致介孔分布不均。该体系中最佳条件:晶化温度170 ℃,晶化时间36 h,模板剂含量6.15 g,乙醇4.15 g。产物的总比表面积为368.5 m2/g,介孔比表面积为106.1 m2/g,总孔容为0.367 cm3/g,微孔孔容为0.121 c·m3/g,介孔孔容为0.246 cm3/g。合成了双功能的双子型表面活性剂,加强反应凝胶与表面活性剂的相互作用,合成出介孔分布均一的多级孔ZSM-5分子筛。该条件下总比表面积为378.5 m2/g,介孔比表面积为92.5 m2/g,总孔容为0.35 cm3/g,微孔孔容为0.11 cm3/g,介孔孔容为0.24 cm3/g。
[Abstract]:ZSM-5 molecular sieve with multilevel pore structure can overcome the limitation of single microporous molecular sieve diffusion, can improve the accessibility of heavy oil and other macromolecules to the active center, improve the catalytic efficiency, and have a good application prospect in heavy oil catalytic cracking. The synthesis of ZSM-5 molecular sieve by using organic amine template is a lot of research methods. The existing problems are as follows: (1) the cost of template is high, the yield is low, and there is pollution. (2) the synthesis process is complex and the mesoporous is difficult to control. It is easy to separate phases. In order to solve the above problems, the multiporous ZSM-5 molecular sieve was prepared by using amphiphilic organosilane and crystal seed assisted method. The formation of micropores can be induced by seed. Organosilane TPHAC is formed by bonding silica hydroxyl group on the surface of silica aluminum gel or partially dissolved seed by hydrophilic end, and the long alkyl chain of hydrophobic end leads to the formation of mesoporous pores by micelles formed by self-assembly. Then the molecular sieve channel was introduced. The optimum conditions were as follows: crystallization temperature 170 鈩，
本文编号：2391724
[Abstract]:ZSM-5 molecular sieve with multilevel pore structure can overcome the limitation of single microporous molecular sieve diffusion, can improve the accessibility of heavy oil and other macromolecules to the active center, improve the catalytic efficiency, and have a good application prospect in heavy oil catalytic cracking. The synthesis of ZSM-5 molecular sieve by using organic amine template is a lot of research methods. The existing problems are as follows: (1) the cost of template is high, the yield is low, and there is pollution. (2) the synthesis process is complex and the mesoporous is difficult to control. It is easy to separate phases. In order to solve the above problems, the multiporous ZSM-5 molecular sieve was prepared by using amphiphilic organosilane and crystal seed assisted method. The formation of micropores can be induced by seed. Organosilane TPHAC is formed by bonding silica hydroxyl group on the surface of silica aluminum gel or partially dissolved seed by hydrophilic end, and the long alkyl chain of hydrophobic end leads to the formation of mesoporous pores by micelles formed by self-assembly. Then the molecular sieve channel was introduced. The optimum conditions were as follows: crystallization temperature 170 鈩，
本文编号：2391724
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