Fabrication and characterization of polyimide–zeolite L mixed matrix membranes for gas separations

Mixed matrix membranes composed of zeolite L dispersed in a 6FDA-6FpDA-DABA polyimide matrix were fabricated and characterized for gas separation performance. The interfacial contact between the two phases relied on introducing amine functional groups on the zeolite surface and covalently linking them with carboxylic acid groups present along the polyimide backbone. While certain gas permeabilities in the membranes increased with the addition of zeolite L, overall these mixed matrix membranes did not offer substantial selectivity improvements. Separate gravimetric sorption measurements indicated that the sorption capacity of zeolites modified with silane coupling agents is substantially lower than the gas sorption in unmodified zeolites.