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.