Measuring the solubility of CO2 and H2S in sulfolane and the density and viscosity of saturated liquid binary mixtures of (sulfolane + CO2) and (sulfolane + H2S)

The density and viscosity of liquid sulfolane saturated (loaded) with single CO2 and H2S gases were measured simultaneously with the solubility of the single CO2 and H2S gases in sulfolane at temperatures ranging from (303.15 to 363.15) K and pressures of up to about 2.4 MPa using a new experimental set-up developed in our laboratory. The experimental density and viscosity values were correlated using a modified Setchenow-type equation. It was observed that the density and viscosity of mixtures decrease by increasing temperature and acid gas solubility (loading) in sulfolane. Acid gas loading has a much pro-founder effect on the viscosity of solutions than on their density, i.e. at a concentration of 1 mol CO2/H2S per kg of sulfolane the density decreases by less than 3%, but viscosity decreases by more than 30%. Results show that at fixed temperature and pressure H2S is more than four times as soluble as CO2 in sulfolane. The measured solubility and density values were respectively used to obtain Henry's law constants and partial molar volumes at infinite dilution for dissolution of CO2 and H2S gases in the liquid sulfolane at the temperatures studied. The Henry's law constants obtained at different temperatures were used to determine infinite dilution partial molar thermodynamic functions (Gibbs free energy, enthalpy and entropy) of solution. The measured solubility data were correlated by using a model comprised of the extended Henry's law and the Pitzer's virial expansion for the excess Gibbs free energy. (C) 2015 Elsevier Ltd. All rights reserved.