Polymer Composite Membrane with Penetrating ZIF‐7 Sheets Displays High Hydrogen Permselectivity

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Oriented and penetrating molecular sieving membranes display enhanced separation performance. A polyimide (PI) solution containing highly dispersed ZIF‐7(III) sheets in CHCl 3 was deposited on a glass side and subjected to flat‐scraping with a membrane fabricator. In this way we developed a novel oriented and penetrating ZIF‐7@PI mixed matrix membrane (MMM) with 50 wt. % ZIF‐7 loading. Because the height of the ZIF‐7 sheets (5 μm) is higher than the film thickness, every ZIF‐7 sheet penetrates both surfaces of the polyimide film. Since the ZIF‐7 channels are the dominant pathway for gas permeation, the ZIF‐7@PI MMM displays a high molecular sieve performance for the separation of H 2 (0.29 nm) from larger gas molecules. At 100 °C and 2 bar, the mixture separation factors of H 2 /CO 2 and H 2 /CH 4 are 91.5 and 128.4, with a high H 2 permeance of about 3.0×10 −7 mol m −2 s −1 Pa −1 , which is promising for hydrogen separation by molecular sieving.