Constructing double-faced CO2-capture domains by sandwich-like fillers in membranes for efficient CO2 separation

The sandwich-like composites were used as fillers, and prepared MMMs for effective CO2 separation by incorporating them into Pebax matrix. Zeolite imidazolate framework-8 (ZIF-8) was grown on two faces of a 2D amino-functionalized Al-metal organic framework (NH2-MIL-53(Al)) to fabricate the sandwich-like ZIF-8/NH2-MIL-53(Al) (ZM). Wherein, ZIF-8 in ZM was long-range ordered because ZIF-8 was evenly distributed throughout the double faces of NH2-MIL-53(Al). And the long-range ordered ZIF-8 constructed double-faced CO2-capture domains to quickly enrich CO2, contributing to improving CO2/CH4 selectivity of MMMs. The introduced NH2-MIL-53(Al) can endow MMMs with the increased CO2 permeability of MMMs. Therefore, the excellent CO2 separation performance was shown by using Pebax/ZM MMMs. The best CO2 separation performance was exhibited in Pebax/ZM MMM with the loading of 6 wt% ZIF-8/NH2-MIL-53(Al), which had a CO2 permeability of 488 ± 9 Barrer and a CO2/CH4 selectivity of 37.5 ± 0.6. It suggests that an efficient method for CO2 separation is the introduction of fillers that resemble sandwiches.