Composite membranes based on ether oxygen-rich polyimide with superior CO2/N2 separation properties prepared by interfacial polymerization

Ether oxygen-rich polymeric membranes emerge as promising membranes in CO2 separation due to the high affinity between CO2 molecules and ethylene oxide segments. However, there is a massive challenge in developing asymmetric membranes with high CO2 permeation performance and CO2/light gas separation performance. This work revealed composite membranes with ether oxygen-rich polyimide separation layers were developed by interfacial polymerization between 1,2,4,5-benzenetetracarbonyl tetrachloride and commercial diamines named o,o'-bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol followed by thermal imidization. The influences of the polymerization time and monomer concentrations on the gas transport and separation properties of the composite membranes were studied based on single-gas permeation. The optimum membrane possessed a superior high ideal CO2/N2 separation factor of 429 accompanied with a moderate permeance of 150 GPU for CO2 at 25oC and 0.2 MPa. The performance stability was studied by operating the membrane at various pressures and temperatures. The result showed the composite membrane possessed excellent plasticization resistivity at high pressures. The separation property of composite membranes for CO2/N2 binary mixture was also evaluated. The influences of the operation parameters, including stage-cut and pressure ratio on the product purity and recovery were investigated. The results showed great practical application potential in efficient separation of flue gas.