Regulating phase change behaviors of water-lean absorbents containing potassium prolinate and 2-butoxyethanol for CO2 capture: Effect of water content

Water-lean phase change amino acid salts (AAS) are of great interest as potential absorbents for post-combustion CO2 capture. In this work, effect of water content in the absorbent containing potassium prolinate (ProK) and 2butoxyethanol (EGBE) on the phase behavior and capture performance was investigated to mimic water accumulation during wet flue gas treatment. Three types of phase separation behaviors were observed for the first time after CO2 absorption from the homogenous liquid, as increasing water content in the absorbent. Phase change mechanisms were proposed based on composition analysis of each phase, which can well explain the improved regeneration efficiency by desorbing CO2-rich phases for the three-phase system. Noticeably, forming liquid-liquid-solid phase change for water-lean ProK/EGBE absorbent shows a promising strategy with advantages of high energy efficiency and water balance management for CO2 capture.