SAFT prediction of vapour-liquid equilibria of mixtures containing carbon dioxide and aqueous monoethanolamine or diethanolamine

We extend the Statistical Associating Fluid Theory, SAFT, to vapour-liquid equilibria of fluid mixtures in which all components hydrogen bond. We refi t parameters for carbon dioxide and water to obtain better agreement with e xperiment, and more consistency with parameters for other associating molec ules. For monoethanolamine and diethanolamine, we obtain deviations in the individual mole fractions of 1 to 2% between the SAFT predictions and the s moothed experimental data. For aqueous mixtures we determine values of the single temperature-independent binary parameters, and then use these parame ters to predict phase equilibria of ternary aqueous mixtures of monoethanol amine or diethanolamine with carbon dioxide. Our results deviate an average of 0.01 in mole fraction units from the experimental mole fractions. The S AFT equation slightly overpredicts the amount of alkanolamine, and underpre dicts the amount of carbon dioxide in the liquid mixture. Small deviations in the liquid mole fraction produce large deviations in the carbon dioxide loading ratio, the ratio of moles of carbon dioxide to moles of alkanolamin e in the liquid, giving average deviations of 43%. (C) 1999 Elsevier Scienc e B.V. All rights reserved.