高等学校化学学报 ›› 2020, Vol. 41 ›› Issue (12): 2813-2821.doi: 10.7503/cjcu20200327

• 物理化学 • 上一篇    下一篇

MFI型分子筛膜的两段变温合成及对二甲苯异构体的分离性能

夏敦焰, 彭莉, 吴政奇, 王林之, 贾逸民, 张春, 顾学红()   

  1. 南京工业大学材料化学工程国家重点实验室, 南京 210000
  • 收稿日期:2020-06-04 出版日期:2020-12-10 发布日期:2020-12-09
  • 通讯作者: 顾学红 E-mail:xhgu@njtech.edu.cn
  • 基金资助:
    国家重点研发计划项目(2018YFB1501701);国家自然科学基金(21776128);江苏省“333”高层次人才项目和材料化学工程国家重点实验室自主课题(ZK201719)

Two-stage Varying-temperature Synthesis of MFI Zeolite Membrane and Their Separation Performance for Xylene Isomers

XIA Dunyan, PENG Li, WU Zhengqi, WANG Linzhi, JIA Yimin, ZHANG Chun, GU Xuehong()   

  1. State Key Laboratory of Materials?Oriented Chemical Engineering,Nanjing Tech University,Nanjing 210000,China
  • Received:2020-06-04 Online:2020-12-10 Published:2020-12-09
  • Contact: GU Xuehong E-mail:xhgu@njtech.edu.cn

摘要:

分别采用恒温和变温两种方法在氧化铝支撑体上原位制备了MFI型分子筛膜. 恒温法合成的MFI型分子筛膜晶体颗粒较大, 在高温脱除模板剂时会形成较大的缺陷, 没有对二甲苯/邻二甲苯(PX/OX)分离性能. 变温法合成的MFI型分子筛膜晶体在a, b方向尺寸较小, 在高温脱除模板时不会形成较大缺陷, 对PX/OX有良好的分离性能, 在300 ℃下, PX/OX分离因子高达42, PX的渗透性为9.57×10-9 mol·m-2·s-1·Pa-1. 采用低温臭氧脱除模板剂能够有效减小分子筛晶体热收缩产生的应力, 提高MFI型分子筛膜的分离性能. 两种方法合成的分子筛膜在低温臭氧的条件下脱除模板剂后, 都具有PX/OX分离性能, 其中变温法合成的分子筛膜PX/OX分离因子高达76, PX的渗透性为1.02×10-8 mol·m-2·s-1·Pa-1.

关键词: MFI型分子筛膜, 变温合成, 缺陷, 二甲苯分离, 模板剂脱除

Abstract:

MFI zeolite membranes were prepared in situ on alumina supports by constant temperature and two-stage varying-temperature synthesis methods, respectively. The MFI zeolite membranes synthesized by the constant temperature method were composed of large crystals and had no separation performance for PX/OX due to the large defects caused by template removal at high temperature. The membranes synthesized by two-stage varying-temperature synthesis method were composed of the zeolite crystals with smaller sizes in a and b directions, and the formation of defects can be avoided during template removal at high temperature. A good separation performance for PX/OX at 300 ℃ with a separation factor of 42 and the PX permeance of 9.57×10-9 mol·m-2·s-1·Pa-1 can be obtained. Detemplation at low temperature in ozone atmosphere can effectively avoid the formation of large defects to improve the membranes, performance by reducing the stress caused by the thermal shrinkage of zeolite crystals. The membranes synthesized by both the two methods showed separation abilities for the xylene isomer after detemplating at low temperature in ozone atmosphere. The MFI zeolite membranes synthesized by variable synthesis temperature showed a PX/OX separation factor up to 76 and PX permeance of 1.02×10-8 mol·m-2·s-1·Pa-1.

Key words: MFI zeolite membrane, Varying-temperature synthesis, Defect, Xylene separation, Detemplation

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