Linker-exchanged zeolitic imidazolate framework membranes for efficient CO2 separation

Metal organic framework (MOF) membranes have exhibited great potential for efficient gas separation owing to their excellent chemical and structural tunability. To realize CO 2 separation from flue gas, linker modification or exchange is generally required to functionalize MOF membranes. However, the reported linker-exchanged polycrystalline MOF membranes have not yet achieved attractive CO 2 separation performance due to the sacrificed permeance of the overly reduced pore apertures when employing bulky linkers. Herein, we report a 3-amino-1,2,4-triazole (Atz)-exchanged polycrystalline ZIF-8 membrane (Atz-ZIF-8) with Atz molar ratios ranging from 3% to 29% which shows an excellent CO 2 /N 2 separation performance that significantly surpasses that of other linker-exchanged ZIF-8 membranes. The as-synthesized Atz-ZIF-8 membranes possess additional uncoordinated amines for CO 2 -preferential adsorption, resulting in an excellent CO 2 /N 2 selectivity of 29. What's more, the size and configuration of Atz is similar to 2-methylimidazole (2-mIm), so the window size of Atz-ZIF-8 membranes is not significantly reduced, and thus high CO 2 permeance (690 GPU) is achieved. Considering the superior performance and accessible manufacturing process, we conclude that our work could provide guidelines on designing advanced linker-exchanged ZIF-8 based polycrystalline membranes towards post-combustion carbon capture.