(211a) CO2 Separation with Supported Ionic Liquid Membranes Containing AHA Ionic Liquids

Ionic liquids (ILs) with aprotic heterocyclic anions (AHAs), including pyrrolides, pyrazolides and triazolides, can be tailored for use in a variety of CO₂ capture applications. These range from flue gas from coal-fired power plants to direct air capture. Here we focus on their use in supported ionic liquid membranes (SILMs), where the AHA can participate in facilitated transport of the CO₂. In particular, we examine the influence on the choice of the anion, which determines the enthalpy of reaction of the AHA IL with CO₂, on the CO₂ permeability and CO₂/N₂ selectivity. Likewise, we explore the effect of the choice of cation, which affects viscosity and AHA molar concentration. In concert with gravimetric and volumetric measurements of CO₂ and N₂ solubility in the AHA ILs, we determine the effective diffusivities and CO₂/N₂ diffusivity selectivity. This information is used to discern the mechanism for the facilitated transport. Overall, we demonstrate the potential for the use of AHA ILs in SILMs for applications ranging from capture of CO₂ from post-combustion flue gas to direct air capture of CO₂.