Study on microporous supported ionic liquid membranes for carbon dioxide capture

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 (CO2) capturing abilities of both SILMs were evaluated. The evaluations include the gas permeation of pure CO2 and nitrogen (N-2), the mixed CO2-N-2 gases containing 50%, 10% and 1% CO2, and the directly compressed ambient air. The results demonstrated that pure CO2 showed the highest permeance, followed by CO2-air and then N-2. Compared with asymmetric SILMs which had higher gas permeance, the symmetric SILMs had better selectivity for CO2/N-2, to more than 20 of CO2/N-2 selectivity, for both single and mixed gases. The SILMs also were found to be capable of capturing CO2 from air from 2 to more than 5 of CO2/air selectivity for separation of air enriched with low CO2 concentrations (10%, 1% and zero) as the transmembrane pressure increased to 0.25 MPa. Thus, this work might provide a potential method for sequestering CO2 directly from atmosphere to avoid the need for extensive CO2-transportation. (C) 2013 Elsevier Ltd. All rights reserved.