Testing solubility data of H2S and SO2 in ionic liquids for sulfur-removal processes

• Solubility data of mixtures containing hydrogen sulfide and sulfur dioxide are analyzed.
• Data for 12 mixtures of H2S and for 3 SO2 + ionic liquid are tested for thermodynamic consistency.
• The modified Peng–Robinson equation of state of Kwak and Mansoori is used for modeling solubility.
• A flexible thermodynamic consistency method is applied to analyze 80 isothermal P-x data sets.
• Thermodynamic consistency method gives a clear conclusion about consistency or inconsistency.

Solubility data of mixtures containing hydrogen sulfide in ionic liquids and sulfur dioxide in ionic liquids at several temperatures and pressures have been tested for thermodynamic consistency. Accurate and consistent data of these mixtures are needed for the design of separation processes for removing sulfur compounds from industrial gases, processes in which ionic liquids present tremendous potential as solvents and extracting agents. The study considers data of twelve binary hydrogen sulfide + ionic liquids mixtures and three binary sulfur dioxide + ionic liquid mixtures. The modified Peng–Robinson equation of state proposed by Kwak and Mansoori is used for correlating the solubility data and a flexible thermodynamic consistency method is applied to analyze 80 isothermal P-x data sets including 630 data points available in the open literature. Modeling is found acceptable in all cases and the thermodynamic consistency method gives a clear conclusion about consistency or inconsistency of each set of data.