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

• Published in: ChemSusChem 2024-03, Vol.17 (6), p.e202301329-n/a
• Main Authors: Qiu, Liqi, Fu, Yuqing, Yang, Zhenzhen, Johnson, Anna C., Do‐Thanh, Chi‐Linh, Thapaliya, Bishnu P., Mahurin, Shannon M., He, Liang‐Nian, Jiang, De‐en, Dai, Sheng
• Format: Article
• Language: English
• Subjects: Anions; Carbon dioxide; Carbon Dioxide Capture; Carbon sequestration; Carbonate Formation; Chemisorption; CO2 Chemisorption; Enthalpy; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ionic liquids; Oxidation; Pyrazolonate anion; Quinones; Robustness; Sorbents; Stability; Structural engineering; Superbase-derived Ionic Liquids
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202301329

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. A series of pyrazolonate‐derived superbase ionic liquids (SILs) have been developed towards efficient and stable carbon capture. High and tunable CO2 uptake capacity was achieved by producing the carbonates via O−C bond formation. The enhanced CO2 uptake and improved stability in long‐term utilization were enabled by combining the strong interaction strength of oxygenate species with CO2 and the involvement of aza‐fused rings in the anions.