Basicity-controlled DBN-based deep eutectic solvents for efficient carbon dioxide capture. (November 2022)

• Record Type: Journal Article
• Authors: Sang, Haina; Su, Li; Han, Weifang; Si, Fang; Yue, Wenhui; Zhou, Xinming; Peng, Zhihua; Fu, Hui
• Is Part Of: Journal of CO₂ utilization. Volume 65(2022)
• Publication Date: 2022-11
• Subjects: Deep eutectic solvents -- CO2 capture -- DBN -- Mechanism; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2022.102201
• Languages: English
• ISSNs: 2212-9820

Abstract

Abstract: Greenhouse gas emission reduction is an important factor to alleviate global warming. Therefore, the development of efficient and reversible carbon dioxide (CO2 ) absorbent to control and reduce CO2 gas emissions has become a hot topic of concern to the majority of researchers. In this study, 1, 5-diazabicyclo [4.3.0]-non-5-ene (DBN) was used as cation, and 1, 2, 4-triaz (Triz), 2-methylimidazole (2-MeIm), 2-Oxazolidone (Oxa) with different pKa were used as anions to synthesize ionic liquids (ILs). Using the above ILs as hydrogen bond acceptor (HBA) and ethylene glycol (EG) as hydrogen bond donor (HBD), DESs were prepared to achieve efficient and reversible absorption of CO2 . The results showed that the larger the pKa of anion, the better the CO2 absorption performance, and the DESs reach the absorption equilibrium faster than ILs. [DBNH][Oxa]-EG (1:0.5) had the best absorption performance with the maximum absorption capacity of 0.171 g CO2 /g DES. The results of 13 C NMR spectra analysis proved that IL and EG could react with CO2 simultaneously to produce carbamate and carbonate, thus realizing the synergistic absorption of imino and hydroxyl group. From a microscopic perspective, DFT calculations confirmed this mechanism and explained the effect of pKa on CO2 capacity. In addition, DBN-based DESs synthesized in this study exhibited excellent recyclability. Graphical Abstract: ga1 Highlights: Three kinds of basicity-controlled DBN-based ILs/DESs are synthesized for CO2 capture. The relationship between pKa and CO2 absorption capacity is investigated. Both IL and EG can react with CO2 to produce carbamate and carbonate, thus realizing the synergistic absorption.