Solubility of Carbon Dioxide in the Ionic Liquid 1‑Ethyl-3-methylimidazolium Tris(pentafluoroethyl)trifluorophosphate

Recently, the use of ionic liquids (ILs) for gas separation processes has attracted much attention because of the high solubility of different gaseous species in ILs. This contribution presents new experimental measurements of the carbon dioxide (CO2) solubility in the IL 1-ethyl-3 methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([emim][FAP]). This solubility has been determined by measuring the bubble point pressures of the binary mixture of [emim][FAP] + CO2 for CO2 concentrations ranging from (10.03 to 60.00) mol % and within a temperature range of (283.75 to 364.13) K using a synthetic method. The obtained values are compared to the solubilities of CO2 in other 1-ethyl-3-methylimidazolium based ILs, to study the effect of the anion. This comparison shows that the solubility of CO2 in the various ILs decreases in the order: [emim][FAP] > [emim][Tf2N] > [emim][EtSO4] = [emim][PF6] > [emim][BF4]. Therefore, the use of [emim][FAP] results in highest absorptive capacity, which makes this IL an attractive solvent for gas separation processes.