Synergy of carbanion siting and hydrogen bonding in Super-nucleophilic
deep eutectic solvents for efficient CO2 capture
Abstract
Carbanion-based ionic liquids are proposed and utilized as the key
components for the construction of five super-nucleophilic deep eutectic
solvents (SNDESs) in the paper. The super-nucleophilic nature of
carbanion-based ILs is found to enable the capture of
CO2 with large absorption capacity. However, the
absorption is very slow in the IL due to high viscosity. The synergy of
carbanion siting and hydrogen bonding is found to enable high and fast
absorption of CO2 in
[N2222][CH(CN)2]-ethylimidazole
(Eim), and a synergistic absorption mechanism is proposed and validated
from spectroscopic analyses and quantum calculations. The enthalpy
change of CO2 absorption in
[N2222][CH(CN)2]-Eim is
calculated to be -39.6 kJ/mol according to the thermodynamic model, and
the moderate value implies that both absorption and desorption of
CO2 in the DES are favored and well balanced. The
synergism of carbanion and hydrogen bond mediated by SNDESs provides a
novel insight into the efficient CO2 capture.
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