CO2 absorption into a phase change absorbent: Water-lean potassium prolinate/ethanol solution

Phase change solvents are attractive energy-efficient absorbents for carbon dioxide (CO2) capture due to CO2-rich phase formation. Potassium prolinate + water + ethanol (ProK/W/Eth) solution has shown good capture characteristics as a promising one in our previous work. In this work, absorption rate of CO2, solubility of N2O, and heat of absorption for ProK/W/Eth solution were investigated using a stirred cell reactor and a CPA201 reaction calorimeter and these results were also compared with the aqueous ProK and 30 mass% MEA solutions. Using ethanol as a solvent can substantially increase the CO2 physical solubility and the absorption rate of CO2 in ProK/W/Eth solutions is far higher than that in aqueous 30 mass% MEA solutions especially at a low CO2 loading range. Solid precipitation, obtained from the liquid-to-solid phase change absorption, was analyzed by 13C NMR and DSC-TGA. The enthalpy change for ProK/W/Eth solutions at various CO2 loading was also discussed.