High-pressure phase behavior of carbon dioxide in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Phase equilibrium data of carbon dioxide in the ionic liquid 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]) are presented at high pressures up to about 30 MPa and at temperatures between 298.15 K and 343.15 K. The solubilities at a given temperature were determined by measuring the bubble point pressure of the ionic liquid solution with carbon dioxide dissolved using the high-pressure equilibrium apparatus equipped with a variable-volume view cell. Solubility results are reported for carbon dioxide concentrations ranging from 0.21 up to 0.80 mole fraction. Carbon dioxide gave very high solubilities in the ionic liquid at lower pressures, while the equilibrium pressure increased very steeply at higher concentrations of carbon dioxide. The solubility of carbon dioxide in the ionic liquid decreased with an increase in temperature.