Surpassing the Performance of Phenolate‐derived Ionic Liquids in CO₂ Chemisorption by Harnessing the Robust Nature of Pyrazolonates

Abstract

Superbase‐derived ionic liquids (SILs) are promising sorbents to tackle the carbon challenge featured by tunable interaction strength with CO2 via structural engineering, particularly the oxygenate‐derived counterparts (e.g., phenolate). However, for the widely deployed phenolate‐derived SILs, unsolved stability issues severely limited their applications leading to unfavorable and diminished CO2 chemisorption performance caused by ylide formation‐involved side reactions and the phenolate‐quinone transformation via auto‐oxidation. In this work, robust pyrazolonate‐derived SILs possessing anti‐oxidation nature were developed by introducing aza‐fused rings in the oxygenate‐derived anions, which delivered promising and tunable CO2 uptake capacity surpassing the phenolate‐based SIL via a carbonate formation pathway (O–C bond formation), as illustrated by detailed spectroscopy studies. Further theoretical calculations and experimental comparisons demonstrated the more favorable reaction enthalpy and improved anti‐oxidation properties of the pyrazolonate‐derived SILs compared with phenolate anions. The achievements being made in this work provides a promising approach to achieve efficient carbon capture by combining the benefits of strong interaction strength of oxygenate species with CO2 and the stability improvement enabled by aza‐fused rings introduction.

CO2 Absorption by Solvents Consisting of TMG Protic Ionic Liquids and Ethylene Glycol: The Influence of Hydrogen Bonds

“…ILs have also been used as absorbents to capture CO 2 and exhibit promising performance. Functionalized ILs which can chemically capture CO 2 have received a great deal of interest owing to their high CO 2 capture capacities [9][10][11]. Amino-functionalized ILs, which have amino groups on cations or anions, could absorb CO 2 through the reaction between CO 2 and amino groups by forming carbamate species [12].…”