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.