1. Tuning the structure of pyridinolate-based functional ionic liquids for highly efficient SO2 absorption.
- Author
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Cui, Guokai, Lyu, Shuzhen, Wang, Huiyong, Li, Zhiyong, Zhang, Ruina, and Wang, Jianji
- Subjects
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ABSORPTION , *SULFUR dioxide , *ANIONS , *IONIC liquids , *PHYSISORPTION , *CHEMISORPTION , *APROTIC solvents - Abstract
[Display omitted] • Pyridinolate-based functional ILs with different structures were designed for SO 2 capture. • Anion order of SO 2 capacity is [4-PyO] > [3-PyO] > [2-PyO]. • Cation order of SO 2 capacity is [P 66614 ] > [P 4442 ] > [TMG]. • Viscosity of system increased first and then decreased with the increase of absorption capacity. A series of pyridinolate anion-functional ionic liquids (ILs) containing different kinds of cations were designed and prepared, including tri- n -hexyltetradecylphosphonium [P 66614 ], tri- n -butylethylphosphonium [P 4442 ], and 1,1,3,3-tetramethylguandinium [TMG] cations and pyridinolate [PyO] anions with different N positions. Densities and viscosities at different temperatures were measured because of their importance for the absorption of SO 2. Effect of different structures on the absorption of SO 2 was studied, including the type and the alkyl chain length of cations, and the N positions of [PyO] anions (2-, 3-, and 4-). Additionally, effects of SO 2 concentration and temperature for absorption were investigated. Especially, up to 6.00 and 2.53 mol SO 2 per mole IL could be obtained by [P 66614 ][4-PyO] at 1 bar and 0.1 bar of SO 2 , respectively, when absorptions performed at 20 °C. The results indicate that (1) the aprotic cations weakened the cation⋯anion interaction and resulted in the released active sites on the anions, and (2) N position has an influence on charge distribution of [PyO] anions and resulted in the tunable absorption of SO 2. Reversible SO 2 absorption and [P 66614 ][4-PyO] regeneration could be performed several times without losing efficiency. Furthermore, the mechanism of absorption was studied through FT-IR and NMR methods and the results showed that the absorption of SO 2 by [P 66614 ][4-PyO] includes physisorption and chemisorption. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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