Solubilities of Carbon Dioxide in Aqueous Potassium Carbonate Solutions Mixed with Physical Solvents

The solubilities of carbon dioxide in aqueous potassium carbonate (K₂CO₃) solutions mixed with physical solvents were measured at 298.2 and 323.2 K with a CO₂ partial-pressure range of 5 kPa to 2 MPa. 1,2-propanediol and propylene carbonate were selected as physical solvents. The aqueous solutions treated in this study were 5 mass% K₂CO₃–15 mass% 1,2-propanediol, 5 mass% K₂CO₃–30 mass% 1,2-propanediol, 5 mass% K₂CO₃–7.5 mass% propylene carbonate, and 5 mass% K₂CO₃–15 mass% propylene carbonate. The experimental solubility results were presented by the mole ratio of CO₂ and K₂CO₃ contained in the liquid mixture. The addition of 1,2-propanediol to 5 mass% K₂CO₃ solution lowered the solubility of CO₂ at constant temperature and pressure conditions within the CO₂ partial-pressure range of 5 kPa to 2 MPa. In the case of propylene carbonate, the addition of propylene carbonate increased the experimental solubilities in the region of low CO₂ partial pressures and decreased as the CO₂ partial pressure was increased above atmospheric. The solubilities of CO₂ decreased with increasing temperature in the range of 298.2 to 323.2 K.