Novel Hydrazide-Based Ionic Liquid Aqueous Solutions Realize CO2 Capture through the Multisite Synergistic Action of N and O Atoms.

A new strategy for enhancing the hydrazine structure based on the inductive effect and conjugation effect of strong electron-withdrawing groups has been designed to effectively absorb CO2 with hydrazide-based ionic liquids (ILs). All three ILs aqueous solutions (diethylenetriamine oxalyl dihydrazide [DETAH]2[ODH], diethylenetriamine propanedioyl dihydrazide [DETAH]2[PDH], and diethylenetriamine succinic dihydrazide [DETAH]2[SDH]) exhibit good absorption performance. Through a combination of absorption-desorption experiments, FT-IR and NMR characterizations, and density functional theory (DFT) calculations, the results indicate that the unique structure of anions enables physical adsorption to occur again after chemically absorbing CO2. The special absorption process is responsible for the unusual regeneration properties. Hopefully, the results of this work are helpful in providing a new method for designing highly efficient gas absorbents.