Study on microporous supported ionic liquid membranes for carbon dioxide capture

Abstract To capture carbon dioxide directly from ambient air, the fabrication of supported ionic liquid membranes (SILMs) on asymmetric and symmetric microporous poly(vinylidene fluoride) (PVDF) membranes were studied. The effect of support membrane structure on the IL loading, the stability of fabricated SILMs, and the carbon dioxide (CO 2 ) capturing abilities of both SILMs were evaluated. The evaluations include the gas permeation of pure CO 2 and nitrogen (N 2 ), the mixed CO 2 –N 2 gases containing 50%, 10% and 1% CO 2 , and the directly compressed ambient air. The results demonstrated that pure CO 2 showed the highest permeance, followed by CO 2 –air and then N 2 . Compared with asymmetric SILMs which had higher gas permeance, the symmetric SILMs had better selectivity for CO 2 /N 2 , to more than 20 of CO 2 /N 2 selectivity, for both single and mixed gases. The SILMs also were found to be capable of capturing CO 2 from air from 2 to more than 5 of CO 2 /air selectivity for separation of air enriched with low CO 2 concentrations (10%, 1% and zero) as the transmembrane pressure increased to 0.25 MPa. Thus, this work might provide a potential method for sequestering CO 2 directly from atmosphere to avoid the need for extensive CO 2 -transportation.