Solubility of CO 2 in 15, 30, 45 and 60 mass% MEA from 40 to 120 °C and model representation using the extended UNIQUAC framework

Abstract

New experimental data for vapor–liquid equilibrium of CO 2 in aqueous monoethanolamine solutions are presented for 15, 30, 45 and 60 mass% MEA and from 40 to 120 °C. CO 2 partial pressures over loaded MEA solutions were measured using a low temperature equilibrium apparatus while total pressures were measured with a high temperature equilibrium apparatus. Experimental data are given as CO 2 partial pressure as function of loading in solution for temperatures from 40 to 80 °C and as total pressures for temperatures from 60 to 120 °C for the different MEA concentrations. The extended UNIQUAC model framework was applied and model parameters were fitted to the new experimental VLE data and physical CO 2 solubility data from the literature. The model gives a good representation of the experimental VLE data for CO 2 partial pressures and total pressures for all MEA concentrations with an average absolute relative deviation (AARD) of 24.3% and 11.7%, respectively, while the physical solubility data were represented with an AARD of 2.7%. Further, the model predicts well literature data on freezing point depression, excess enthalpy and liquid phase speciation determined by NMR.