A comprehensive study of CO2 solubility in aqueous 2-HEAA and MEAÂ +Â 2-HEAA solutions - Measurements and modeling

The solubility of CO2 in aqueous MEA + 2-HEAA solutions decreased as the 2-HEAA mass fraction increased. Thus, the formation of 2-HEAA through MEA degradation into acetic acid was found to decrease the CO2 capture capability of the aqueous MEA solution. A chemical equilibrium model was developed to correlate the experimental data. The model is based on the well-known chemical equilibrium between aqueous MEA and CO2. The computationally straightforward ionic activity coefficient model was used to include the effect of both MEA and 2-HEAA on the CO2 absorption. The model correlates the partial pressure of CO2 over all the measured data points, covering all the measured systems, with the average deviation of 23 kPa. The absolute average deviation of the model was 6.8% for the data points measured at over 25 kPa and 17% for all of the data points. In addition, the model was used to simulate CO2 solubility in aqueous benzoic acid + MEA systems by changing the acid dissociation constant to that of benzoic acid. The simulation results were in good agreement with the experimental values found in the open literature, demonstrating the models capability in describing the effects on CO2 solubility of various types of acidic impurities found in aqueous MEA solutions.