Thermodynamic Properties of a System for CO2 Absorption with Liquid–Liquid Phase Split: EvA25 + H2O + CO2

Solvent systems with liquid–liquid phase split are potentially interesting for designing advanced CO2 absorption processes. However, physico-chemical data for assessing the benefits of such processes are scarce in the literature. Therefore, a comprehensive study on thermodynamic properties of such a system (N,N-diethyl-propylamine-triacetonediamine (EvA25) + H2O + CO2) was carried out in the present work. More than 750 experimental data points of different physico-chemical properties of that system were taken at temperatures between 20 and 120 °C, pressures of up to 75 bar, and CO2 loadings of up to 3 mol/mol. They comprise data for liquid–liquid equilibrium, CO2 solubility, liquidus temperature, chemical speciation, heat capacity, density, viscosity, and vapor pressure. The liquid–liquid phase split occurs at elevated temperatures and reduces the solubility of CO2 in the solvent. The organic liquid phase contains only little CO2, so that only the aqueous phase has to be regenerated. Based on the new data, options for using the liquid–liquid phase split in the design of CO2 absorption processes are discussed.