Novel ionic liquids phase change solvents for CO2 capture

•Amino-functional ILs were used in the phase change systems to obtain high capacities and avoid volatilization, and these ILs are easily prepared with cheap raw materials.•Performances of CO2 absorption and desorption in such mixtures were studied and such systems showed better absorption capacities than that of traditional MEA processes.•The CO2 absorption products were mainly concentrated in the lower phase after saturation, thus only one phase needs to be regenerated.•Such absorbents can be regenerated and recycled with no remarkable activity loss.•13C NMR was applied to verify the absorption mechanism of these ILs phase change solvents. Phase change solvents have a great potential to reduce the energy consumption in the CO2 capture process. In this work, a class of novel phase change solvents composed of ionic liquids with some solvents are developed and the performances for capturing CO2 are investigated. Such a class of phase change solvents present very competitive CO2 capture capability, e.g., the CO2 capacity by [TETA]Br-PMDETA-water system is high to 2.631 mol CO2/L under the conditions of 303 K, 4 M, [TETA]Br and PMDETA mole ratio 3:7, while avoid the solvent loss, a major problem in traditional phase change solvents, because ionic liquids are not volatile. Further, the phase change solvents can be regenerated at 423 K and the regeneration efficiency remains above 95% after four cycles. The absorption and phase transition mechanism are revealed with 13C NMR, and such a high capture capability is ascribed to the mutual promoting effect of [TETA]Br and PMDETA.