(68f) Evaluation of Ionic Liquids as Novel Post-Combustion Carbon Dioxide Capture Solvents

Ionic liquids (ILs) are salts with low melting points, many below room temperature. Even though they are liquids, they have negligible vapor pressure. Typical ILs are composed of a imidazolium, pyridinium, ammonium or phosphonium cation with any of a wide variety of anions. Their properties can be varied tremendously by the choice of anion, cation and substituents. In research supported by the U.S. Department of Energy's National Energy Technology Laboratory and in collaboration with several industrial partners, we have shown that CO2 and SO2 both have remarkably high physical solubilities in some ILs. Since ILs are non-volatile, they have an advantage over conventional solvents used in carbon capture because they will not evaporate during absorption or regeneration. By making the substituent groups capable of forming a chemical complex with CO2, it is possible to greatly enhance capacity. By tuning the binding strength, the energy to regenerate the solvent can be minimized while maintaining high capacity.

In this talk, we will describe our recent progress in the development of new ionic liquids that can be used in carbon capture applications. Through a combined experimental and computational modeling effort, we have been able to greatly increase the solubility of CO2 in ionic liquid solvents. We report results of pure and mixed gas solubility and discuss preliminary process design and engineering studies that investigate the feasibility of using ionic liquids for post-combustion carbon capture.