Tunable and facile preparation of chelate-based ionic liquids for highly efficient SO2 separation under low concentration in flue gas.

Tunable chelate-based ionic liquids were synthesized through a one-step method, which exhibited excellent desulfurization performance in flue gas. [Display omitted] • Novel and tunable chelate-based ionic liquids were prepared conveniently by one-step method. • Highly efficient separation of SO 2 in flue gas was achieved through tuning the effect of the anion, ligand and metal ion. • Absorption mechanism was explained via the combination of experimental absorption, spectroscopic investigation and DFT calculation. A strategy for facile preparation of chelate-based ionic liquids (ILs) by simple chelation was developed, where a series of chelate-based ILs with tunable functionalized anions (azole), cheap ligands (PEG400), and simple metal ions (Li+, Na+, and K+) were designed for SO 2 capture under 2000 ppm in flue gas. Both the anion-tunable strategy and the fine-tuned strategy were used to explore the effect of anions, ligands, and metal ions. The experimental absorptions, spectroscopic investigations, and DFT calculations indicated that the process of SO 2 capture was mostly based on the nucleophilic effect of electronegative N site toward SO 2. Furthermore, the tuning of alkali metal ions was proved to have little influence on SO 2 absorption. The ideal IL, [Na(PEG400)][Tetz], exhibited splendid available absorption capacity of SO 2 (0.57 mol/mol), excellent selectivity (63 under 2000 ppm SO 2 /15% CO 2), and outstanding reversibility, indicating good potential for industrial application. [ABSTRACT FROM AUTHOR]