Sulfur Dioxide Promoted Mercury Fast Deposition over a Selenite-Chloride-Induced Surface from Wet Flue Gas.

Gaseous elemental mercury (Hg) extraction from industrial flue gases is undergoing intense research due to its unique properties. Selective adsorption that renders Hg to HgO or HgS over metal oxide- or sulfide-based sorbents is a promising method, yet the sorbents are easily poisoned by sulfur dioxide (SO) and HO vapor. The Se-Cl intermediate derived from SeO and HCl driven by SO has been demonstrated to stabilize Hg. Thus, a surface-induced method was put forward when using γ-AlO supported selenite-chloride (SeO-Cl, named Se-Cl) for mercury deposition. Results confirmed that under 3000 ppm SO and 4% HO, Se-2Cl exhibited the highest induced adsorption performance at 160 °C and higher humidity can accelerate the induction process. Driven by SO under the wet interface, the in situ generated active Se has high affinity toward Hg, and the introduction of Cl enabled the fast-trapping and stabilization of Hg due to its intercalation in the HgSe product. Additionally, the long-time scale-up experiment showed a gradient color change of the Se-2Cl-induced surface, which maintained almost 100% Hg removal efficiency over 180 h with a normalized adsorption capacity of 157.26 mg/g. This surface-induced method has the potential for practical application and offers a guideline for reversing the negative effect of SO on gaseous pollutant removal.