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Accurate measurement and prediction of the phase behaviour of mixtures involved in a chemical process are crucial for its optimisation. Given the importance of CO 2 conversion technologies and considering possible benefits of CO 2 -ionic liquid biphasic systems, i.e., facilitating a product separation, we investigated the high-pressure behaviour of components of interest in a recently developed process of cyclic carbonate synthesis directly from CO 2 and potentially bio-based alcohols. The solubility of 1,2-butanediol and 1,2-butylene carbonate in a dense carbon dioxide phase was determined experimentally at the temperature of 313.2 K and pressures between 6 and 18 MPa. The influence of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid, [hmim][FAP], as a solvent, on the solubility of these compounds in CO 2 -rich phase, in ternary (CO 2 + 1,2-butanediol + [hmim][FAP]), CO 2 + butylene carbonate + [hmim][FAP]) and quaternary (CO 2 + 1,2-butanediol + butylene carbonate + [hmim][FAP]) mixtures was investigated. The experimental results of the two binary systems were correlated using the density-based Chrastil equation. The knowledge of phase equilibria behaviours reported in this work will be useful for designing chemical conversions of carbon dioxide using [hmim][FAP] ionic liquid as reaction solvents. [Display omitted] • solubility of 1,2-butanediol and butylene carbonate in dense CO 2. • phase behaviour of ternary and quaternary CO 2 -IL biphasic mixtures. • 1-hexyl-3-methylimidazolium tris(pentafluoroalkyl)trifluorophosphate ionic liquid as solubility modifier. [ABSTRACT FROM AUTHOR]

The high-pressure solubility of carbon dioxide in ionic liquids based on tetracyanoborate anion, 1-ethyl-3-methylimidazolium tetracyanoborate ([emim][B(CN) 4 ]) and 1-hexyl-3-methylimidazolium tetracyanoborate ([hmim][B(CN) 4 ]), was determined experimentally at the temperature of 313.15 K and pressures up to 19 MPa. Additionally, measurements of volume expansion of a liquid phase, based on a change in total or molar volume of a liquid upon carbon dioxide addition, are reported. The obtained results show that CO 2 has a high solubility in tetracyanoborate-based ionic liquids, comparable, or even slightly higher, to the CO 2 solubility in fluorinated CO 2 -philic ionic liquids. Approximately 60% CO 2 -induced volume expansion of the liquid was observed at the highest pressures, an unprecedented result for ionic liquid+ CO 2 systems. [ABSTRACT FROM AUTHOR]

Abstract: The solubility of carbon dioxide in ionic liquids was measured in a new apparatus. The ionic liquids chosen have ammonium-based cations and show melting temperature decreases under CO2 pressure that range from low (25K) to extremely high (120K). The main purpose of this study was to check whether the solubility of the gas in each liquid could explain the previously reported wide differences in melting point depression (MPD). The results show there is no correlation between solubility and MPD. [Copyright &y& Elsevier]

Abstract: Solid–liquid, liquid–liquid and vapour–liquid equilibrium measurements for binary and ternary systems containing building blocks of biomass origin such as propionic acid, lactic acid and alternative solvents like carbon dioxide and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid have been carried out at 313.15K. The binary solid–liquid and liquid–liquid equilibrium measurements were performed at ambient pressure. The vapour–liquid equilibrium was studied in the range of pressure from 3.54 to 12MPa while ternary systems were examined at 9, 10 and 12MPa. The samples from the coexisting phases were taken and the compositions of both liquid and vapour phases were determined experimentally. The three-phase system was observed for lactic acid+ionic liquid+CO2 as well. The achieved results were correlated using the Peng–Robinson equation of state with the Mathias–Klotz–Prausnitz mixing rule. The set of interaction parameters for the employed equations of state and the mixing rule for the investigated systems were obtained. [Copyright &y& Elsevier]