Solubility of CO2 in 15, 30, 45 and 60 mass% MEA from 40 to 120 °C and model representation using the extended UNIQUAC framework

New experimental data for vapor–liquid equilibrium of CO2 in aqueous monoethanolamine solutions are presented for 15, 30, 45 and 60 mass% MEA and from 40 to 120 °C. CO2 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 CO2 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 CO2 solubility data from the literature. The model gives a good representation of the experimental VLE data for CO2 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.

► Vapor–liquid equilibrium measurement for 15, 30, 45, 60 mass% MEA. ► Modeling with extended UNIQUAC thermodynamic framework. ► Physical (N2O) solubility of CO2 used in modeling. ► Liquid phase speciation, excess enthalpy, freezing point depression predicted.