Solubility of CO sub(2) in 15, 30, 45 and 60 mass% MEA from 40 to 120 &; deg; C and model representation using the extended UNIQUAC framework

New experimental data for vapor-liquid equilibrium of CO sub(2) in aqueous monoethanolamine solutions are presented for 15, 30, 45 and 60 mass% MEA and from 40 to 120 degree C. CO sub(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 sub(2) partial pressure as function of loading in solution for temperatures from 40 to 80 degree C and as total pressures for temperatures from 60 to 120 degree 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 sub(2) solubility data from the literature. The model gives a good representation of the experimental VLE data for CO sub(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.