Volumetric and phase behaviour of mixtures of fluoroalkylphosphate-based ionic liquids with high pressure carbon dioxide

• High solubility of CO2 in tris(pentafluoroethyl)trifluorophosphate‐based ionic liquids.
• Higher than usual CO2-induced volume expansion of tris(pentafluoroethyl)trifluorophosphate‐based ionic liquids.
• Strikingly visible liquid volume expansions in sapphire tube apparatus.

The high-pressure solubility of carbon dioxide in ionic liquids based on tris(pentafluoroethyl)trifluorophosphate ([eFAP]) anion, combined with 1-ethyl-3-methylimidazolium ([emim]), 1-butyl-3-methylimidazolium ([bmim]) and 1-hexyl-3-methylimidazolium ([hmim]) cation, was determined experimentally at the temperature of 313.15 K and pressures up to 10 MPa. Measurements of the volume expansion of the liquid phase upon carbon dioxide dissolution are also reported. The obtained results show that the solubility of CO2 in ionic liquids with the fluoroalkylphosphate anion, as well as the CO2-induced volume expansion of the liquid, are among the highest so far reported for ionic liquids where CO2 dissolves through “physical” mechanisms.

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