Insights into the Inhibitory Effect of H2O on Hg‐Catalytic Oxidation over the MnOx‐Based Catalysts

Abstract

AbstractMnOx‐based catalyst has been used for elemental mercury (Hg0) removal in the coal‐fired flue gas, but the H2O in the flue gas significantly inhibits its activity. Generally, it is believed the inhibitory effect is caused by competitive adsorption between Hg0/HCl and H2O. In this study, we found that the MnOx was also aged in the flue gas with high concentration of H2O. The results indicated that the catalysts would be aged by H2O. The characterization of the fresh and aged catalysts showed that the amount of Mn4+ and chemisorbed oxygen species decreased. H2O didn't inhibit HCl adsorption on the catalyst surface, but suppressed the formation of active chlorine species, which was active for Hg0 removal. Therefore, besides the generally known competitive adsorption mechanism, there should be other possible reasons to interpret the inhibitory effects of water vapor on Hg0 oxidation process.