Facilitated transport membrane with functionalized ionic liquid carriers for CO/N, CO/O, and CO/air separations.

CO separations from cabin air and the atmospheric air are challenged by the very low partial pressures of CO. In this study, a facilitated transport membrane (FTM) is developed to separate CO from air using functionalized ionic liquid (IL) and poly(ionic liquid) (PIL) carriers. A highly permeable bicontinuous structured poly(ethersulfone)/poly(ethylene terephthalate) (PES/PET) substrate is used to support the PIL-IL impregnated graphene oxide thin film. The CO separation performance was tested under a mixture feed of CO/N/O/HO. Under 410 ppm of CO at 1 atm feed gas, CO permanence of 3923 GPU, and CO/N and CO/O selectivities of 1200 and 300, respectively, are achieved with helium sweeping on the permeate side. For increased transmembrane pressure (>0 atm), a thicker PIL-IL/GO layer was shown to provide mechanical strength and prevent leaching of the mobile carrier. CO binding to the carriers, ion diffusivities, and the glass transition temperature of the PIL-IL gels were examined to determine the membrane composition and rationalize the superior separation performance obtained. This report represents the first FTM study with PIL-IL carriers for CO separation from air.