Sweetening of sour natural gases by mixed‐solvent absorption: Solubilities of ethane, carbon dioxide, and hydrogen sulfide in mixtures of physical and chemical solvents

Solubilities of ethane, carbon dioxide, and hydrogen sulfide have been measured in propylene carbonate, N-methyl-2-pyrrolidone and tetramethylene sulfone (sulfolane); and in mixtures of these physical solvents with monoethanolamine and diglycolamine, in the range −10 to 100°C. Thermodynamically consistent equations are given for gas absorption with chemical reaction at equilibrium. Henry's law describes physical equilibrium between the acidic gas in the vapor phase and free acid solute in the liquid phase. Equilibrium constants describe chemical equilibria for the absorbed gas and the chemical solvent. Preliminary design calculations for sweetening natural gases by absorption with mixed solvents suggest that, under some circumstances, mixed-solvent absorption may be more economical than using conventional aqueous alkanolamine.