Enthalpies of Absorption of CO2 in Aqueous Alkanolamine Solutions from e-NRTL Model

Differential enthalpies of absorption of CO2 with aqueous solutions of 2-aminoethanol (MEA) and N-methyldiethanolamine (MDEA) were calculated from reaction equilibrium constants of each of the key reactions taking place in the MEA + H2O + CO2 and MDEA + H2O + CO2 systems. A set of equilibrium constants was selected for the modeling, based on comparison of existing correlations for the reaction equilibrium constants, K-eq, and corresponding heats of reaction, Delta H-r, with experimentally measured K-eq and Delta H-r found in literature. Activity coefficients of all species in the solutions were calculated using the electrolyte NRTL model. Enthalpies of absorption from this work are compared with experimental data from literature and with predictions from the Aspen and Deshmukh-Mather models. The importance of good correlations for the temperature dependencies of the equilibrium constants is shown. (C) 2008 Elsevier Ltd. All rights reserved.