Synergistic catalytic oxidation of Hg0 and NH3-SCR of NO over MnCeTiOx catalyst in flue gas

The catalytic oxidation over the selective catalytic reduction (SCR) catalysts is efficient and economical for the removal of elemental mercury (Hg-0). Herein, we studied the catalytic oxidation of Hg-0 over the MnCeTiOx catalysts with different Ce contents synthesized by a polyethylene glycol-assisted (PEG) co-precipitation method. By increasing the contents of Ce loaded, the oxidizability of MnCeTiOx was reduced, but the NH3-SCR performance and H2O/SO2 resistance were improved. The MnCe(0.1)TiOx catalyst presented high NO conversion rate exceeding 80% at 160-360 C and gas space hourly velocity (GHSV) of 80, 000 h(-1) and Hg-0 oxidation efficiency beyond 95% at 100-300 C and 400, 000 h-1, respectively. The surface-active oxygen including chemisorbed surface O and unsaturated-coordinated surface lattice O acted as the active sites for Hg-0 oxidation. The competitive adsorption and oxidation of SO2 and NH3 could suppress the adsorption of Hg-0. NO and SO2 could be oxidized into active intermediates, such as NO3-* and SO42-* , which benefited the oxidation of Hg-0. However, the NH3 was a strong Lewis base and reducing agent, which could be oxidized to NH2* or NH* and then hinder the oxidation of Hg0. These results clarified the interaction among the multi-components during the oxidation of Hg0 over the SCR catalysts, which is beneficial to the development of Hg0 treatment techniques in low temperature flue gas.