Amine functionalized supported ionic liquid membranes (SILMs) for CO₂/N₂ separation

Supported ionic liquid membranes (SILMs), containing aprotic N-heterocyclic anion ionic liquids (AHA ILs) in an inorganic inert support, exhibit CO₂/N₂ permselectivity values as high as 640 at 35.0 °C and 0.03 bar CO₂, which represents conditions similar to post-combustion carbon capture (PCCC) from a natural gas power plant. A Fickian model fit to the experimental data estimates CO₂ permeability at direct air capture (DAC) conditions of 10,400 barrer and a CO₂/N₂ permselectivity of 4000 for the best performing IL, triethyl(octyl)phosphonium 4-bromopyrazolide ([P₂₂₂₈][4-BrPyra]). The most important criterion for high selectivity is a large equilibrium constant for binding between the IL and CO₂, which results in high CO₂ solubility. ILs with smaller molar volumes and with no fluoroalkyl chains enhance N₂ rejection. As a result, low viscosity and high IL molar density also enhance CO₂/N₂ permselectivity and CO₂ permeance.. Authors: Chamoun-Farah, Antoine [University of Texas at Austin, TX (United States); McKetta Department of Chemical Engineering, The University of Texas at Austin] (ORCID:0009000706624390); Keller, Austin N. [University of Texas at Austin, TX (United States)] (ORCID:0009000206340324); Balogun, Mariam Y. [University of Texas at Austin, TX (United States)] (ORCID:0009000105045377); Cañada, Louise M. [University of Texas at Austin, TX (United States)] (ORCID:0000000229599876); Brennecke, Joan F. [University of Texas at Austin, TX (United States)] (ORCID:0000000279352134). DOE Contract: SC0023343. Subjects: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY