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Modification of covalent organic frameworks with dual functions ionic liquids for membrane-based biogas upgrading
Journal of Membrane Science ( IF 8.4 ) Pub Date : 2020-04-01 , DOI: 10.1016/j.memsci.2020.117841
Rui Zhao , Hong Wu , Leixin Yang , Yanxiong Ren , Yutao Liu , Zihan Qu , Yingzhen Wu , Li Cao , Zan Chen , Zhongyi Jiang

Abstract Development of high-performance membranes for biogas upgrading is an urgent demand for the application of membrane technology in the field of renewable energy. Covalent organic frameworks (COFs) exhibit promising potential in membrane-based separation for their highly ordered crystalline porous structure, total organic backbone and tailored functionality. However, the limited functional groups on frameworks and relatively larger pore size of existing COFs restrict further improvement in the separation efficiency especially for gas mixtures. This work reports a novel strategy for modifying the pore of COF-300 with imidazolium-based ionic liquid [bmim][Tf2N] by post-impregnation and then incorporate the composite particles IL@COF-300 into Pebax matrix to prepare mixed matrix membranes (MMMs). The IL decreases the pore size of COF-300 from 1.28 nm to 1.09 nm and increases the diffusion coefficient difference (DCO2/DCH4) between CO2 and CH4. Moreover, the presence of IL with high CO2 solubility endows the COF-300 pores with CO2-facilitating ability and thus increasing the solubility difference (SCO2/SCH4). The dual functions of IL lead to an enhanced separation performance of the resultant IL@COF-300/Pebax MMMs with an optimal permeability of 1601 Barrer and a CO2/CH4 gas selectivity of ~39, i.e. 209% and 87% higher than the pristine Pebax membrane, respectively, breaking the trade-off between permeability and selectivity and surpassing the Robeson 2008 upper-bound. The membrane also exhibits superior long-term operation stability during two months.

中文翻译:

用双功能离子液体改性共价有机骨架用于膜基沼气升级

摘要 开发用于沼气提质的高性能膜是膜技术在可再生能源领域应用的迫切需求。共价有机骨架 (COF) 因其高度有序的结晶多孔结构、总有机骨架和定制功能而在基于膜的分离中显示出广阔的潜力。然而,骨架上有限的官能团和现有COFs相对较大的孔径限制了分离效率的进一步提高,尤其是对于气体混合物。这项工作报告了一种通过后浸渍用咪唑基离子液体 [bmim][Tf2N] 修饰 COF-300 孔的新策略,然后将复合颗粒 IL@COF-300 掺入 Pebax 基质中以制备混合基质膜( MMM)。IL 将 COF-300 的孔径从 1 减小。28 nm 至 1.09 nm 并增加 CO2 和 CH4 之间的扩散系数差异 (DCO2/DCH4)。此外,具有高 CO2 溶解度的 IL 的存在赋予 COF-300 孔以促进 CO2 的能力,从而增加溶解度差异 (SCO2/SCH4)。IL 的双重功能提高了所得 IL@COF-300/Pebax MMM 的分离性能,最佳渗透率为 1601 Barrer,CO2/CH4 气体选择性为~39,即比原始高 209% 和 87% Pebax 膜分别打破了渗透性和选择性之间的权衡,并超过了 Robeson 2008 的上限。该膜在两个月内还表现出卓越的长期运行稳定性。具有高 CO2 溶解度的 IL 的存在赋予 COF-300 孔隙促进 CO2 的能力,从而增加溶解度差异 (SCO2/SCH4)。IL 的双重功能提高了所得 IL@COF-300/Pebax MMM 的分离性能,最佳渗透率为 1601 Barrer,CO2/CH4 气体选择性为~39,即比原始高 209% 和 87% Pebax 膜分别打破了渗透性和选择性之间的权衡,并超过了 Robeson 2008 的上限。该膜在两个月内还表现出卓越的长期运行稳定性。具有高 CO2 溶解度的 IL 的存在赋予 COF-300 孔隙促进 CO2 的能力,从而增加溶解度差异 (SCO2/SCH4)。IL 的双重功能提高了所得 IL@COF-300/Pebax MMM 的分离性能,最佳渗透率为 1601 Barrer,CO2/CH4 气体选择性为~39,即比原始高 209% 和 87% Pebax 膜分别打破了渗透性和选择性之间的权衡,并超过了 Robeson 2008 的上限。该膜在两个月内还表现出卓越的长期运行稳定性。IL 的双重功能提高了所得 IL@COF-300/Pebax MMM 的分离性能,最佳渗透率为 1601 Barrer,CO2/CH4 气体选择性为~39,即比原始高 209% 和 87% Pebax 膜分别打破了渗透性和选择性之间的权衡,并超过了 Robeson 2008 的上限。该膜在两个月内还表现出卓越的长期运行稳定性。IL 的双重功能提高了所得 IL@COF-300/Pebax MMM 的分离性能,最佳渗透率为 1601 Barrer,CO2/CH4 气体选择性为~39,即比原始高 209% 和 87% Pebax 膜分别打破了渗透性和选择性之间的权衡,并超过了 Robeson 2008 的上限。该膜在两个月内还表现出卓越的长期运行稳定性。
更新日期:2020-04-01
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