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过程工程学报 ›› 2021, Vol. 21 ›› Issue (2): 134-143.DOI: 10.12034/j.issn.1009-606X.220100

• 反应与分离 • 上一篇    下一篇

超临界流体沉积制备[Emim][BF4]支撑型离子液体膜及其气体分离性能

王雨晴,刘居陶,徐琴琴,银建中*   

  1. 大连理工大学化工学院,辽宁 大连 116024
  • 收稿日期:2020-03-22 修回日期:2020-04-28 出版日期:2021-02-22 发布日期:2021-03-01
  • 通讯作者: 银建中
  • 基金资助:
    木质纤维素催化转化制高附加值化学品乙醇酸甲酯;二氧化碳辅助制备高稳定性支撑型离子液体膜的热力学基础及其表征

Gas separation performance of [Emim][BF4]-supported ionic liquid membranes prepared by supercritical fluid deposition

Yuqing WANG, Jutao LIU, Qinqin XU, Jianzhong YIN*   

  1. School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning 116024, China
  • Received:2020-03-22 Revised:2020-04-28 Online:2021-02-22 Published:2021-03-01

摘要: 为了进一步提高支撑型离子液体膜的制备效率及其CO2气体分离性能,将离子液体[Emim][BF4]以超临界流体沉积法负载到非对称的Al2O3支撑体内,制备了一系列支撑型离子液体膜,分别测定了CO2和N2两种纯气体在其中的渗透率,探究了制备参数(沉积时间、离子液体加入量和共溶剂加入量)对膜性能的影响规律。结果表明,基于[Emim][BF4]制备支撑型离子液体膜时,制备效率高且成品性能好。在最佳制备条件(沉积时间1 h、离子液体加入量1.875 mg/mL和共溶剂加入量11.25vol%)下所制得的支撑型离子液体膜的离子液体的负载量为2.6 mg/g,CO2和N2的渗透率分别为6.4和0.14 GPU,CO2/N2选择性为45.3。该支撑型离子液体膜既接近[Emim][BF4]的理论选择性上限,又达到了Robeson上限,同时具有良好的CO2气体渗透率和CO2/N2选择性。通过对比基于其他三种离子液体的支撑型离子液体膜的制备工艺和成品性能,发现在超临界流体沉积法中,用表面张力更大的离子液体并提高其在超临界流体中的浓度有利于大幅提升制备效率,其中离子液体浓度主要由其种类、加入量和共溶剂加入量等因素决定。选用低黏度和高CO2/N2溶解选择性的离子液体有利于提升支撑型离子液体膜的气体分离性能。

关键词: CO2捕捉, 膜分离, 支撑型离子液体膜, 超临界流体沉积法, 离子液体, [Emim][BF4], 共溶剂, Robeson上限

Abstract: Supported ionic liquid membrane (SILM) technology is an attractive way for CO2 separation and capture, because of its combined advantages of both ionic liquid and membrane. The supercritical fluid deposition is a novel and promising preparation method to improve the CO2 permeation of the SILMs by confining ionic liquid only in the thin effective layer of support, leaving the large pores in the substrate open. To improve the preparation efficiency and the gas separation performance, the ionic liquid, [Emim][BF4], was confined into the asymmetry alumina supports to prepare SILMs by supercritical fluid deposition. The performance of SILMs was evaluated by analyzing the IL addition, the N2 and CO2 permeance and the ideal CO2/N2 selectivity. And the influences of deposition time, IL and ethanol addition were investigated. Comparing to those prepared with other ILs, [Emim][BF4]-SILMs can achieve better CO2 separation performance in a shorter time. The SILM prepared under the optimum condition, exhibited the IL addition of 2.6 mg/g, the CO2 and N2 permeance of 6.4 and 0.14 GPU, the CO2/N2 selectivity of 45.3. It was close to the upper limit of CO2/N2 selectivity of [Emim][BF4], and reached the Robeson upper bound as well, showing both high permeance and selectivity. It was found that higher surface tension of IL and higher IL concentration in supercritical CO2 improved the preparation efficiency significantly, while the IL concentration was mainly determined by IL type, ethanol and IL addition. Besides, using ILs with low viscosity, high CO2/N2 selectivity was conductive to obtaining SILMs with both high CO2 permeance and CO2/N2 selectivity.

Key words: CO2 capture, membrane separation, supported ionic liquid membrane, supercritical fluid deposition, ionic liquid, [Emim][BF4], co-solvent, the Robeson upper bound