Modelling and prediction of the solubility of acid gases in diethanolamine solutions

The pseudo-equilibrium model proposed by Kent and Eisenberg is used in this study to model the absorption of acid gases (H2S and CO2) in aqueous diethanolamine solutions at equilibrium. A wide range of experimental data available in the literature is used to obtain the values of the pseudo-equilibrium constants of the amine reactions. These data cover amine concentrations from 0.5 to 8 N, temperatures from 273 to 413 K, and acid gas loadings from zero to unity. New correlations for the pseudo-equilibrium constants and solution pH are obtained as a function of temperature, amine concentration, and acid gas loading for loading up to unity. The partial pressure of H2S is much better predicted by the new correlation compared to the work of Kent and Eisenberg. The predictions of the partial pressure of CO2 are improved mainly at high temperatures and amine concentrations.