Douglas GIN1, Chamaal KARUNAWEERA1, Richard NOBLE1
1University of Colorado, Boulder, Boulder, United States
CO2/light gas (CH4 and N2) separation performance, physical aging and plasticization of cross-linked poly(ionic
liquid)-ionic liquid (PIL-IL) composite membranes were evaluated at elevated temperatures (up to 50 C) and feed
pressures (up to 40 atm). PIL-IL composite membranes made with IL-based multifunctional cross-linkers exhibited
higher CO2 permeability and CO2/light gas selectivity compared to the membranes made with a conventional, nonionic cross-linker, divinylbenzene (DVB). We also show that the gas separation performance of PIL-IL membranes
can be further tuned by varying the wt % of cross-linker, PIL:IL ratio, and both simultaneously. For example, a crosslinked PIL-IL composite membrane prepared using 70 wt % 1-vinyl-3-methylimidazolium bistriflimide as the IL
monomer, 30 wt % 1-ethyl-3-methylimidazolium bistriflimide as the free IL, and 8 wt % 1,3,5-tris(1’-methylene-3’-
vinylimidazolium bistriflimide)benzene as the IL cross-linker exhibited a ca. 50% increase in CO2 permeability and
a comparable CO2/CH4 selectivity compared to an analogous PIL-IL-zeolite MMM cross-linked with DVB.