Ham SW

Vol. 28,  No. 1, pp. 38-45, Mar.  2022
10.7464/ksct.2022.28.1.38

SO2 CuCl2-loaded V2O5-WO3/TiO2 SCR catalyst Mercury oxidation Mercury balance NOx removal by SCR

PDF

CuCl2-loaded V2O5-WO3/TiO2 catalyst showed excellent activity in the catalytic oxidation of elemental mercury to oxidized mercury even under SCR condition in the presence of NH3, which is well known to significantly inhibit the oxidation activity of elemental mercury by HCl. Moreover, it was confirmed that, when SO2 was present in the reaction gas together with HCl, excellent elemental mercury oxidation activity was maintained even though CuCl2 supported on the catalyst surface was converted to CuSO4. This is thought to be because not only HCl but also the SO4 component generated on the catalyst surface promotes the oxidation of elemental mercury. However, in the presence of SO2, the total mercury balance before and after the catalytic reaction was not matched, especially as the concentration of SO2 increased. In order to understand the cause of this, further studies are needed to investigate the effect of SO2 in the SnCl2 aqueous solution employed for mercury species analysis and the effect of sulfate ions generated on elemental mercury oxidation. It was confirmed that SO2 also promotes NOx removal activity, which is thought to be because the increase in acid sites by SO4 generated on the catalyst surface by SO2 facilitates NH3 adsorption. The composition change and structure of the components present on the catalyst surface under various reaction conditions were measured by XRD and XRF. These measurement results were presented as a rational explanation for the results that SO2 enhances the oxidation activity of elemental mercury and the NOx removal activity in this catalyst system.