Thermodynamic modeling of CO2 and H2S solubilities in aqueous DIPA solution, aqueous sulfolane–DIPA solution, and aqueous sulfolane–MDEA solution with electrolyte NRTL model

A thermodynamic model developed for CO2 and H2S solubilities in aqueous MDEA solution is extended to cover CO2 and H2S solubilities in aqueous DIPA solution, aqueous sulfolane–DIPA solution, and aqueous sulfolane–MDEA solution. The model makes use of the 2009 version of the electrolyte NRTL model for liquid phase activity coefficient calculations and the PC-SAFT equation of state for vapor phase fugacity coefficient calculations. The NRTL binary parameters for the molecule–electrolyte pairs required for the H2O–DIPA–CO2 ternary and the H2O–sulfolane–DIPA–CO2 quaternary are regressed against the solubility data of CO2 in aqueous DIPA solution and aqueous sulfolane–DIPA solution, respectively. The NRTL binary parameters for the molecule–electrolyte pairs required for the H2O–DIPA–H2S ternary and the H2O–sulfolane–DIPA–H2S quaternary are regressed against the solubility data of H2S in aqueous DIPA solution and aqueous sulfolane–DIPA solution simultaneously. The NRTL binary parameters for the electrolyte–electrolyte pairs involved in the H2O–DIPA–CO2–H2S quaternary are regressed against the solubility data of the acid gas mixtures in aqueous DIPA solution. Likewise, the NRTL binary parameters for the sulfolane–electrolyte pairs required for the H2O–sulfolane–MDEA–CO2 quaternary and the H2O–sulfolane–MDEA–H2S quaternary are regressed against the solubility data of the acid gases in aqueous sulfolane–MDEA solution. The predicted enthalpies of acid gas absorption are compared favorably with the literature data available for the H2O–DIPA–CO2 system, the H2O–DIPA–H2S system, and the H2O–sulfolane–MDEA–CO2 system.

► A thermodynamic model is developed for CO2 and H2S solubilities in aqueous sulfolane with amines.
► The model is validated for VLE with amine concentrations up to 40 wt% for DIPA or 20 wt% for MDEA.
► The model is based on the electrolyte NRTL activity coefficient model and the PC-SAFT equation-of-state.
► The model enables process modeling of CO2 capture processes with sulfolane–amine mixed solvents.