Intensification of CO2 separation performance via cryogenic and membrane hybrid process - Comparison of polyimide and polysulfone hollow fiber membrane

Cryogenic-membrane hybrid CO2 capture process has been considered as a promising alternative for the standalone processes to mitigate the critical challenge of energy penalty. In this work, two different commercial hollow fiber membranes were tested at low temperature condition to find the possibility of consisting a novel cold-membrane-cryogenic hybrid process. The gas permeation properties of membranes were evaluated at different operating temperature, CO2 concentration and stage cut. The experimental results indicated that cryogenic condition could facilitate to improve the CO2/N-2 selectivity with a minimum permeance reduction. Specifically, with the operating temperature dropped to - 20 degrees C and feed pressure set at 0.7 MPa, the CO2 selectivity of polyimide membrane increased by 166% with the permeance declined by 31%. Meanwhile, the CO2 recovery and purity of polyimide membrane achieved 92% and 49% at the temperature of - 20 degrees C and pressure 0.7 MPa, respectively. It can be observed that operating membrane at cold condition could be a promising approach to intensify the CO2 separation, and thus decrease the energy consumption of subsequent CO2 liquefaction or desublimation in the hybrid process.