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.