Advances in applications of ionic liquids for phase change CO2 capture

Phase change absorbents exhibit phase change after absorbing CO 2 and offering potential for energy savings. This review introduced applications of 3 types of phase change absorbents based on ionic liquids in CO 2 capture. • Application of ionic liquids for CO 2 capture with phase change was reviewed. • Three classes of phase change CO 2 absorbents based on ionic liquids were discussed. • Various mechanisms triggering phase separation in absorbents were elaborated. • Advantages and limitations of ILs-based phase change CO 2 absorbents were provided. Research and development of novel absorbents with high efficiency and low energy consumption is the key to achieve large-scale carbon dioxide (CO 2 ) emissions reduction by chemical absorption method. Due to the advantages of adjustable structure, negligible vapor pressure, low specific heat capacity, and moderate reaction heat, the CO 2 capture technology based on ionic liquids (ILs) absorbents has remarkable potential for energy conservation. The applications of ILs in CO 2 capture process with phase change can further cut down the regeneration energy penalty. In this article, we reviewed the recent progress in ILs-based phase change absorbents for CO 2 capture technology, focusing on phase change behaviors, reaction and phase change mechanisms, and process flow and energy consumption analyses. Applications of ILs as solvents or absorbents in phase change absorbents were discussed including liquid–liquid biphasic absorbents, liquid–solid biphasic absorbents, and phase change ILs. We have provided challenges and outlooks on novel ILs-based phase change absorbents for CO 2 capture from laboratory research to industrial applications.