Characterization and SO₂ Sorption Performance of Zn₃[OAc]₈[C₂mim]₂, a Metal-Based Ionic Liquid

The metal-containing ionic liquid, Zn₃[OAc]₈[C₂mim]₂, was synthesized, characterized, and incipiently impregnated onto the high-surface-area, nanoporous coconut-shell-activated carbon to evaluate its potential for acidic gas capture using SO₂ as the probe gas molecule. The Zn₃[OAc]₈[C₂mim]₂-impregnated sorbents were tested for SO₂ sorption performance under a simulated polluted air environment of 10 ppm of SO₂, relative humidity of 50%, and a temperature of 28 °C relevant to fuel cells. Surprisingly, the 5 wt % Zn₃[OAc]₈[C₂mim]₂ sorbent had the highest SO₂ breakthrough performance compared to the 10 wt %, as well as the pure activated carbon. The material properties were elucidated by using FTIR, TGA, DSC, SEM, and EDS techniques. The absorption of SO₂ was directly confirmed as S-O vibrations at 1100 cm^-1 in ATR-FTIR spectra and sulfur peaks in EDS. The results clearly indicate that metal-containing ionic liquids are good candidates for practical acidic gas mitigation at low contaminant concentrations in the future.