Modelling of CO2 solubility in phase separation solvent composed of amine/ether/water system for CO2 capture

Abstract

Phase separation solvents for CO2 absorption constructed with amine/ether/water have been designed which transform into two liquid phases after CO2 absorption. We also found that phase separation solvent can reduce the temperature difference between absorber and desorber that can reduce the required energy for CO2 capture. In this study, we develop a model for the CO2 solubility of phase-separation type CO2 absorbent which is necessary for process simulation. Ion species in the liquid phase was estimated by 13C NMR, and the ion association form was inferred from the Walden plot based on conductivity and viscosity. The CO2 solubility model expressed the vapour-liquid equilibrium as the Henry's law constant, the liquid-liquid equilibrium as the non-random two-liquid activity coefficient model, and the liquid phase CO2 chemical absorption as the equilibrium constant. The model can predict CO2 solubility at temperature range (313–363 K) and CO2 partial pressure range (1–100 kPa) and compositions of CO2-lean and CO2-rich phases can be calculated when phase separation occurs.