ZIF-L membrane with a membrane-interlocked-support composite architecture for H/CO separation

具有膜-载体互锁型复合微结构的ZIF-L膜应用于H_(2)/CO_(2)分离

Metal–organic framework(MOF)membranes hold great promise in energy-efficient chemical separations.The outstanding challenges of the microstructural design stem from(1)thinning of membranes to immensely reduce the mass-transfer resistance(for high permeances);(2)tuning of orientation to optimize the selective transport of gas molecules,and(3)reinforcement of intercrystalline structure to subside leakage through defective gaps(for high selectivity).Here,we propose the ZIF-L membrane that is completely confined into the voids of the alumina support through an interfacial assembly process,producing an appealing membrane-interlocked-support(MIS)composite architecture that meets the requirements of the microstructural design of MOF membranes.Consequently,the membranes show average H2 permeances of above 4000 GPU and H_(2)/CO_(2) separation factor(SF)of above 200,representing record-high separation performances of ZIF-L membranes and falling into the industrial target zone(H_(2) permeance>1000 GPU and H_(2)/CO_(2) SF>60).Furthermore,the ZIF-L membrane possessing the MIS composite architecture that is established with alumina particles as scaffolds shows mechanical stability,scraped repeatedly by a piece of silicon rubber causing no selectivity loss.

金属-有机骨架(MOF)膜在低能耗化工分离领域具有广阔应用前景.其关键在于膜的微结构设计,所面临重要挑战有:(1)如何降低膜层厚度以极大减小传质阻力;(2)如何调控膜的孔道取向以优化分子选择性传输;(3)如何强化晶界结构以最大程度减少缺陷流,进而实现高渗透率和高分离选择性.本文利用原位界面组装策略制备ZIF-L膜.通过调变配体浓度,可将膜层完全限制在载体孔隙内,形成高度取向的膜-载体互锁型复合微结构,膜表观厚度为零,充分满足了上述设计原则.ZIF-L膜的气体测试结果显示,其H_(2)/CO_(2)分离因子超过200,H_(2)渗透率达4000 GPU以上,性能位于工业应用目标区域(H_(2)渗透率>1000 GPU,H_(2)/CO_(2)分离因子>60),为迄今H_(2)/CO_(2)分离性能最优的ZIF-L膜.再者,这种具有膜-载体互锁型复合微结构的ZIF-L膜,展现出良好的机械稳定性.以硅橡胶垫反复刮擦膜表面,不会造成选择性下降.这为MOF膜的微结构设计提供了重要方向.