Correlation and Prediction of the Solubility of Carbon Dioxide in a Mixed Alkanolamine Solution

Aqueous alkanolamine solutions are frequently used for the removal of acidic gases, such as CO[sub 2] and H[sub 2]S from industrial and natural gases. The Clegg-Pitzer equations, expressed on a mole fraction basis, comprise an extended Debye-Hueckel term which is a function of composition and a Margules expansion carried out to the three-suffix level, with some simplifications are used to correlate and predict the vapor-liquid equilibrium data for the CO[sub 2]-mixed amine aqueous system. The interaction parameters determined from data for the binary and ternary (single amine) systems can be used to predict the quaternary mixed amine system without any additional parameters. The model is applied to the CO[sub 2]-MDEA-MEA-H[sub 2]O system containing three neutral solvents (MDEA, MEA, and H[sub 2]O) and four ionic species (MDEAH[sup +], MEAH[sup +], HCO[sub 3][sup [minus]], and RNHCOO[sup [minus]]) with four chemical equilibria simultaneously involved.