Poly?amide-6-b-ethylene Oxide?/Microporous Polyaminal Mixed Matrix Membranes For CO₂ Separation

The membrane materials with high separation performance are the key to the development of CO₂ separation membrane technology.The mixed matrix membranes?MMMs?usually have both high permeability and selectivity,because of the combination of the easy processability of polymers with the superior gas separation properties of the inorganic materials,which is quite promising in gas separation membranes.In this work,poly?amide-6-b-ethylene oxide??Pebax 1657?and microporous polyaminal were used to prepare mixed matrix membranes by solvent evaporation method.The effects of solvents and microporous polyaminal content on morphologies and CO₂ separation performance of Pebax 1657/microporous polyaminal MMMs were studied systematically.Firstly,Pebax 1657/microporous polyaminal MMMs were prepared with 70 wt% ethanol aqueous solution as solvent.The membranes prepared were characterized by SEM,XRD and FT-IR,the results showed that Pebax 1657/microporous polyaminal MMMs were a dual layer membranes,which is similar to the common composite membranes.The addition of microporous polyaminal reduced the crystallinity of Pebax 1657 and increased the amorphous region.The permeabilities of CO₂,H2,CH4 and N2 increased significantly with increasing microporous polyaminal content in the MMMs,meanwhile,the ideal selectivities of CO₂/N2,CO₂/CH4 and CO₂/H2 remained unchanged.Compared with the pristine Pebax 1657 membrane,CO₂,H2,CH4 and N2 permeabilities of the mixed matrix membrane with 30 wt% microporous polyaminal loading increased by 177%,184%,180% and 170%,respectively.Secondly,DMSO was used as solvent to fabricate MMMs of uniform morphologies.The addition of microporous polyaminal careated a more tortuous diffusion path which increased the gas diffusion resistance.In comparision with the pristine Pebax 1657 membrane,CO₂/N2 ideal selectivity of MMMs was hardly changed.However,permeabilities of CO₂ and N2 decreased with the increase of microporous polyaminal content.