High-Pressure Phase Behavior of Carbon Dioxide with Ionic Liquids: 1-Alkyl-3-methylimidazolium Trifluoromethanesulfonate

Solubility data of carbon dioxide (CO 2 ) in the ionic liquids 1-alkyl-3-methylimidazolium trifluoromethanesulfonate ([C n mim][TfO]; n = 2, 4, 6, 8) are presented at pressures up to about 40 MPa and at temperatures between (303.85 and 344.55) K. The equilibrium pressure increased very steeply at high CO 2 concentrations. The solubility of CO 2 in the ionic liquids decreased with an increase in temperature. The CO 2 solubility increased with the increase in the alkyl chain length on the cation of the ionic liquids. The phase equilibrium data for the CO 2 + ionic liquid systems have been correlated using the Peng−Robinson equation of state.