Correlation and prediction of the solubility of carbon dioxide in aqueous alkanolamine and mixed alkanolamine solutions

The solubility of carbon dioxide in aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), 2-amino-2-methyl-l-propanol (AMP), MEA + AMP, and DEA + AMP was measured at 40, 60, and 80 degreesC. Equilibrium partial pressures of CO2 ranged from approximately 0.1 to 50 psia. The modified Kent-Eisenberg model was used to determine the deprotonation constant and carbamate stability constant for TMEA, DEA, and AMP solutions at different temperatures. The solubility of CO2 in aqueous mixtures of AMP with MEA or DEA has been predicted using the modified Kent-Eisenberg model and reaction equilibrium constants, which were determined from each amine. The predicted values were in good agreement with the experimental data over a wide range of equilibrium CO2 partial pressure, temperature, and solution concentration. The concentration of the liquid-phase species was calculated as a function of CO2 loading, and some qualitative trends were obtained.