(334e) Solubility of Mixed Gases Containing Carbon Dioxide in Imidazolium Based Ionic Liquids

Ionic liquids (ILs) can be used for a wide range of gas separations because there are significant differences in the solubility of various gases in ILs. Also, of primary importance in evaluating CO2/ILs systems for chemical reactions involving permanent gases is the solubility of those gases in ILs in the presence of CO2. Recently several groups have reported that the presence of CO2 increases the solubility of other gases that are poorly soluble in the ionic liquid phase. However, some other groups demonstrated that there is no significant improvement of the gas solubilities in the CO2/ ILs biphasic systems compared to pure gas solubilities. Therefore, it is important to further investigate the phase behavior of these ionic liquid / CO2 systems. Here, we investigate the solubility of pure N2, and gas mixtures with different compositions (90/10 and 75/25 N2 to CO2 mole ratios) in imidazolium based ionic liquids and compare these results to pure gas solubilities and previous reports. A series of experiments were performed at preset temperatures and liquid compositions by means of a very precise fixed volume view-cell coupled with an online gas chromatography. A temperature range from (296 to 333) K was investigated with pressures up to about 1000 psi. The enhancement of the solubility of N2 by CO2 is relatively modest under the conditions investigated. Further investigation will focus on the solubility of multicomponent gas mixtures (argon, nitrogen and oxygen) in the ionic liquids in the presence of CO2.