Solubility of carbon dioxide in the aqueous $K_2CO_3, K_2CO_3+PEG, and K_2CO_3+$ 1,2-Propanediol solutions

Abstract

The solubilities of $CO_2$ in the aqueous potassium carbonate solutions and potassium carbonate solutions mixed with Poly(ethylene glycol) and 1,2(propanediol at 298.2 and 323.2 K were measured over the pressure range of 5 to 2000 kPa. The concentrations of the aqueous mixtures by mass were 5 \% $K_2CO_3$, 5 \% $K_2CO_3$(15 \% PEG, 5 \% $K_2CO_3$(30 \% PEG, 10 \% $K_2CO_3$, 10 \% $K_2CO_3$(15 \% PEG, and 5 \% $K_2CO_3$(15 \% 1,2(propanediol. The experimental solubility results were presented by the mol ratio of $CO_2$ and $K_2CO_3$ contained in the liquid mixture. The solubilities of $CO_2$ in the liquid solution increased with the partial pressure of $CO_2$ and decreased with the solution temperature. Even if the increase of the initial amount of potassium carbonate in the solution decreased the $CO_2$ loading, the totally absorbed amount of $CO_2$ increased. The addition of PEG and 1,2-propanediol to the liquid solution decreased the solubility of $CO_2$ at a fixed temperature and pressure. A simple theoretical modeling of the absorption phenomena was considered semi-empirically in the amine and potassium carbonate solutions. For the system containing amine, the model of Li and Shen as adapted and the calculated equilibrium partial pressure of $CO_2$ was compared with the experimental data of 15.3 mass \% MEA aqueous solution at 313.2 K. The predicted results were well correlated with the experimental data. For the system containing potassium carbonate, the use of the equilibrium constant in the literature predicted a results with somewhat large deviations from the experimental data. This is because there was no consideration of the liquid phase non-ideality. When the liquid phase non-ideality was lumped into the parameters in the equilibrium constant, the calculated results were satisfactorily correlated with the experimental data.