(338i) Thermodynamics and Phase Behavior of Ionic Liquids with Gases

Ionic liquids are salts with low melting points. They are attractive as solvents for gas separations due to their low volatility, wide liquid operating range, extremely low vapor pressures and thermal stability. More importantly, their structure and, therefore, affinity for various gases can be tuned almost limitlessly by judicious choice of anion, cation and substituents. In general, CO2, SO2 and H2S are highly solubility in many ionic liquids, whereas O2, N2, CO and H2 are not. Hydrocarbon solubilities vary significantly with alkyl chain length and degree of saturation. Here we will show how the solubility of these gases can be varied by manipulation of the ionic liquid structure. In particular, we will show how CO2 solubility can be enhanced by the introduction of targeted physical interactions, as well as weakly and strongly associating chemical complexing groups.