New polyethersulfone (PESU) hollow fiber membranes for CO2 capture

Compared to cellulose acetate, silicon rubber, polysulfone, and polyimide, polyethersulfone (PESU) has received much less attention as a commercially viable material for gas separation membranes. This is because PESU has issues of low permeability but rapid physical aging behavior that limit its asymmetric hollow fiber membranes for gas separation applications. To overcome it, a new PESU was synthesized by replacing one diphenyl sulfone unit in the main chains with a bulky and rigid 1,2,4-trimethylbenzene moiety so that the new PESU (referred to as poly trimethyl phenylene ethersulfone (TPESU)) has a greater permeability and less aging behavior. The hollow fiber membranes spun from TPESU dopes exhibit excellent gas separation performance with significantly less aging phenomena. Not only do they have superior O-2 and CO2 permeance of 16 GPU and 85.1 GPU, respectively, but also possess O-2/N-2, CO2/N-2 and CO2/CH4 selectivity of 6.5, 34.0 and 35.5, respectively at 25 degrees C. The pure gases are tested at 3.5 atm except CO2 at 1 atm. The newly developed TPESU hollow fiber membrane has comparable gas separation performance with those fibers spun from Matrimid. The newly designed TPESU may have great potential as a membrane material for oxygen enrichment, natural gas separation and CO2 capture.