多级孔ZSM-5纳米晶团聚体分子筛的合成与优化研究

Synthesis and optimization of ZSM-5 nanocrystallite aggregates with hierarchical pores

采用纳米粒子自组装策略,选择传统微孔模板剂四丙基氢氧化铵(TPAOH)为单一模板剂和廉价的硅溶胶为硅源,合成了多级孔ZSM-5纳米晶团聚体分子筛。考察了硅铝摩尔比和体系Na^(+)摩尔分数对纳米晶团聚体ZSM-5分子筛形貌的影响,并追踪了不同晶化时间下纳米晶团聚体的形成过程,最后利用XRD､SEM和氮气吸附/脱附等表征手段对所合成分子筛的性质进行分析。结果表明,低硅铝摩尔比有利于纳米晶团聚体分子筛的形成,同时合成体系中的Na^(+)对团聚体的形成具有重要作用。经优化调控后,小试可合成固体收率达94.2%的ZSM-5纳米晶团聚体分子筛,经3 L合成釜进行40倍的放大合成可成功获得高结晶度､高产率的产品。

ZSM-5 nanocrystalline aggregates zeolites with hierarchical pores are synthesized by means of the nanoparticles self-assembly strategy,using tetrapropyl ammonium hydroxide(TPAOH)as the single template and cheap silica sol as silicon source.The effects of SiO2/Al 2O3 ratio and the contents of Na^(+)on the morphology of ZSM-5nanocrystalline aggregates zeolites are investigated.The formation process of nanocrystalline aggregates is tracked at different crystallization times.The properties of the synthesized molecular sieve are analyzed by means of XRD,SEM,nitrogen adsorption/desorption and other characterization measurements.The results show that the lower SiO2/Al 2O3 ratio is conducive to the formation of molecular sieve of nanocrystalline aggregates,and Na^(+)in the synthetic system plays an important role in the formation of the aggregates.After the optimization and regulation,ZSM-5 nanocrystalline aggregates with a solid yield of 94.2%can be synthesized in the pilot test.The product with high crystallinity and high yield can be successfully synthesized by a 3-L synthesis reactor with a 40-fold amplification.