Fluorinated and sulfonated poly (ether ether ketone) and Matrimid blend membranes for CO2 separation

The gas separation performance and miscibility of Matrimid and fluorinated sulfonated aromatic poly (ether ether ketone) (F-SPEEK) blend membranes prepared by solution casting method were studied. F-SPEEK polymer with fixed degree of sulfonation (40%) was used for membrane synthesis. Physical miscibility of both Matrimid and F-SPEEK was observed over the whole composition range, as confirmed by DSC studies and visual observation. The effect of variation in F-SPEEK composition on gas permeability and selectivity of blend membranes was investigated. The gas permeability and selectivity values fall in between those of the individual polymers, varying systematically with variation of F-SPEEK content in the blend. The addition of F-SPEEK in the blend led to simultaneous increase in the gas permeability and selectivity. In order to further study the stability and potential industrial application of these membranes, they were tested at different conditions of feed temperature (298-338 K), feed pressures (10-40 bar) and CO2 concentration in feed. The effect of feed pressure on CO2 permeation was linked to CO2 plasticization of the membranes. The addition of F-SPEEK component in the blend shifted the plasticization pressure thereby imparting anti-plasticization properties to the blend. Improvement in anti-plasticization properties along with enhanced gas separation properties confirms F-SPEEK/Matrimid blend membranes as an excellent candidate for the separation of gaseous mixtures at industrial scale.