碳纳米管/环糊精金属有机骨架协同强化混合基质膜的CO_(2)分离

Synergistic of carbon nanotube/cyclodextrin metal organic framework for enhancing CO_(2) separation of mixed matrix membranes

为了实现混合基质膜中CO_(2)的高效分离,设计了羧基化多壁碳纳米管(CNT)和氨基化β-环糊精金属有机骨架(β-CD MOF)双填料(CM),并将其引入磺化聚醚醚酮(SPEEK)基质中,在膜内同时构建CO_(2)扩散通道和亲和位点,增强了混合基质膜的分离性能。采用FTIR和BET表征了CM的化学结构和孔结构,借助膜的SEM、FTIR和力学性能表征了填料-聚合物界面相互作用。研究了CM的合成比例、含量、压力、温度和混合气等因素对混合基质膜分离性能的影响。结果表明:CM与SPEEK之间具有良好的相容性并为气体分子提供了快速的传递通道。在改性CNT与MOF的质量比为5∶5、添加量为7%(质量)以及0.1 MPa和25℃的条件下,混合基质膜的分离性能最优,CO_(2)渗透性为844 Barrer,CO_(2)/N_(2)选择性为84,与纯SPEEK膜相比,分别提升了178%和163%,超过2019年上限。羧基化CNT的直孔通道缩短了CO_(2)的扩散路径,同时改性β-CD MOF表面的氨基载体提升了CO_(2)的溶解性,两者协同提高了混合基质膜的分离性能。此外,负载双填料的膜比单独负载相同含量的羧基化CNT或氨基化MOF的膜具有更好的分离性能。在360 h的测试过程中,混合基质膜保持较好的分离稳定性。

To achieve the CO_(2) efficient separation in mixed matrix membranes(MMMs),a dual-filler(CM)of carboxyl modified multi-walled carbon nanotubes(CNT)and amino modified β-cyclodextrin metal organic framework(β-CD MOF)was designed and introduced to sulfonated poly(ether ether ketone)(SPEEK)to construct both CO_(2) diffusion channels and affinity sites within the membranes,which enhanced the separation performance of MMMs.The chemical and pore structures of the dual-filler were characterized by FTIR and BET,and the fillerpolymer interfacial interactions were verified by SEM,FTIR and mechanical properties of the membranes.The effects of the proportion,content,pressure,temperature and mixed gas on the separation performance of MMMs were investigated.The results showed that CM was compatible with SPEEK and provided fast transport channels for gas molecules.The SPEEK/CM-7 MMMs with mass ratio of 5∶5 displayed the optimal separation performance with a CO_(2) permeability of 844 Barrer and a CO_(2)/N_(2) selectivity of 84 at 0.1 MPa and 25℃,which were 178% and 163% higher than those of the pristine SPEEK membrane,respectively,surpassing the 2019 upper bound.The straight pore channels of functional CNT shortened the CO_(2) diffusion path,while the amino carriers on the surface of modified MOF enhanced the CO_(2) dissolution,which synergistically improved the separation performance of MMMs.Moreover,the membranes loaded with dual-filler had preferable separation performance than those loaded with the same amount of carboxyl modified CNT or amino modified MOF alone.During 360 h testing,the SPEEK/CM-7 MMMs remained good stability.