CO2 absorption using aqueous potassium lysinate solutions: Vapor – liquid equilibrium data and modelling

Abstract

The solubility of CO2 in aqueous potassium lysinate (LysK) solutions was measured in a stirred reactor at temperatures from 298 to 353K, for 9.0, 17.4, 25.3, 33.1 and 41.2mass% LysK and CO2 partial pressures up to 110kPa. The vapor-liquid equilibrium (VLE) data were interpreted using the modified Kent-Eisenberg model. The apparent equilibrium constants of carbamate hydrolysis and amino acid deprotonation were correlated as a function of temperature, CO2 loading (expressed as mole CO2 per mole LysK) and LysK concentration to fit the experimental solubility data. The proposed model satisfactorily predicted the VLE data for the H2O-LysK-CO2 system, especially at moderate to high CO2 loading, with an average absolute deviation within 3.2%. Liquid species in the CO2-loaded LysK solutions were also qualitatively characterized by 13C NMR experiments.