Amine-functionalized zeolite FAU/EMT-polyimide mixed matrix membranes for CO2/CH4 separation

This study describes the preparation, characterization and application of mixed matrix membranes (MMMs) made from as-synthesized FAU/EMT intergrowth zeolites grafted with 3-aminopropylmethyldiethoxysilane (APMDES) as the inorganic phase and as-synthesized 6FDA–ODA polyimide as the organic phase. The amine grafting reaction was carried out under four different conditions in order to obtain zeolites having various amounts of amine groups grafted on their external surface. The percentage of amine-grafted on zeolites as well as the adsorption capacity for CO2 of the samples have been measured for comparison. XRD, BET, and TG were performed to characterize the grafted zeolites. Finally, the grafted zeolites were incorporated in a 6FDA–ODA polyimide matrix, MMMs were casted and CO2/CH4 gas separation tests were performed. MMMs were also characterized using ATR-FTIR, and SEM. The obtained results showed that at 25 wt.% zeolite in MMM and optimum grafting conditions, both the permeability and selectivity are increased compared to neat polyimide membrane.