ZIF-based water-stable mixed-matrix membranes for effective CO₂ separation from humid flue gas

Water stable mixed-matrix membranes (MMM) were developed to abate global warming by capturing and sequestrating CO₂ from humid flue gas originated from burning of fossil fuels. MMM of different compositions were prepared by doping glassy polymer Ultrason^® S 6010 (US) with nanocrystals of zeolitic imidazolate frameworks (ZIF-302) in varying degrees. A solution-casting technique was used to fabricate various MMM to optimize their CO₂ capturing performance from both dry and wet gases. The prepared composite membranes indicated enhanced filler-polymer interfacial adhesion, consistent distribution of nanofiller, and thermally stable matrix configuration. CO₂ permeability of the membranes was enhanced as demonstrated by gas sorption and single gas permeation tests carried out under dry and moist circumstances. Compared to neat Ultrason^® membrane, CO₂ permeability and expected CO₂/N₂ permselectivity of the mixed membrane doped with 40 g/g ZIF-302 nanocrystals were greatly enhanced.