Pore engineering of ZIF-8 with ionic liquids for membrane-based CO_(2)separation:bearing functional group effect

CO_(2)separation performance of polymer membranes can be significantly enhanced by selecting porous fillers with high CO_(2)affinity.Ionic liquids incorporation has been recognized as an effective strategy for improving the separation ability of pristine porous fillers.However,the influence of the specific functional groups of ILs in IL@MOF composites on separation performance of MMMs still remains unclear.Herein,we designed three microenvironment-tuned IL@ZIF-8 composites in which the three ILs contain different functional groups(-CH3,–SO3H,and–NH2).Molecular simulation results showed that the NH2-IL@ZIF-8 has a commendable CO_(2)adsorption capacity and CO_(2)/CH4 adsorptive selectivity,and the results were well confirmed by the following experimental data.More importantly,the prepared NH2-IL@ZIF-8 based MMMs also exhibit superior CO_(2)separation performance among the three IL@ZIF-8 based MMMs owning to its high CO_(2)affinity.Thus,this work can provide guidance for designing IL@MOF composites for MMMs fabrication towards gas separation,and the research mode combining molecular simulation prediction and experimental verification can afford valuable reference for material development in membrane separation field.

Coordination-driven structure reconstruction in polymer of intrinsic microporosity membranes for efficient propylene/propane separation

Polymers of intrinsic microporosity(PIMs),integrating unique microporous structure and solution-processability,are one class of the most promising membrane materials for energy-efficient gas separations.However,the micropores generated from inefficient chain packing often exhibit wide pore size distribution,making it very challenging to achieve efficient olefin/paraffin separations.Here,we propose a coordination-driven reconstruction(CDR)strategy,where metal ions are incorporated into amidoxime-functionalized PIM-1(AO-PIM)to in situ generate coordination crosslinking networks.By varying the type and content of metal ions,the resulting crosslinking structures can be optimized,and the molecular sieving capability of PIM membranes can be dramatically enhanced.Particularly,the introduction of alkali or alkaline earth metals renders more precise micropores contributing to superior C3H6/C3H8 separation performance.K+incorporated AO-PIM membranes exhibit a high ideal C3H6/C3H8 selectivity of 50,surpassing almost all the reported polymer membranes.Moreover,the coordination crosslinking structure significantly improves the membrane stability under higher pressure as well as the plasticization resistant performance.We envision that this straightforward and generic CDR strategy could potentially unlock the potentials of PIMs for olefin/paraffin separations and many other challenging gas separations.