Unexpectedly promoted SO2 capture in novel ionic liquid-based eutectic solvents: The synergistic interactions

A series of novel deep eutectic solvents (DESs) composed of equimolar solid ionic compounds (EmimX and EPyY; X, Y = Cl-, Br-) were developed for SO2 absorption in this work. Effects of absorption temperature, SO2 partial pressure, gas flow rate and moisture content on SO2 absorption capacities of the DESs were investigated. These DESs exhibited an extremely high SO2 loading capacity and excellent reversibility. Concretly, the solubilities of SO2 in 1-ethyl-3-methylimidazolium chloride (EmimCl)- Nethylpyridinium chloride (EPyCl) were 1.483 and 0.777 g SO2/g solvent under the SO2 partial pressure of 1.0 and 0.1 atm at 20 degrees C, respectively, which were the highest values to date under the same conditions. Furthermore, EmimCl-EPyCl exhibited a reasonable SO2 capacity of 0.193 g SO2/g solvent when the SO2 concentration in the feed gas was 2000 ppm. The absorption mechanisms based on the results of H-1 NMR and DFT calculation indicated that the high SO2 absorption capacity was mainly attributed to the synergistic interactions of the two components in the DESs rather than a simple combination of the capacities of EmimCl and EPyCl. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A series of novel deep eutectic solvents (DESs) composed of equimolar solid ionic compounds were developed for SO2 absorption, exhibiting high absorption capacity and reversibility. The solubilities of SO2 in these DESs were found to be the highest reported values under certain conditions.