Mn doped CeO2-MoO3/γ-Al2O3 catalysts for the enhanced adsorption and catalytic oxidation of Hg0 in oxygen atmosphere

A series of Mn-doped CeO2-MoO3/gamma-Al2O3 catalysts were synthesized for the adsorption and catalytic oxidation of Hg0 from coal-fired flue gas using oxygen as the oxidizing agent. The results showed that the addition of Mn significantly promoted the adsorption and catalytic performances of CeO2-MoO3/gamma-Al2O3 catalysts. The 6 wt% Mn-doped catalysts exhibited the best Hg-0 catalytic oxidation efficiency of 86%. The catalysts were characterized to illustrate the structure-activity relationship of Mn-doped catalysts. It is found that the addition of Mn to the CeO2 and MoO3 lattice increases the concentration of oxygen vacancies on the catalyst surface which promotes the catalytic oxidation of mercury. HRTEM results indicate that the incorporation of Mn cracked CeO2 crystal plane with an angle of 105 and may generate more active sites at the interface. Besides, the in-situ DRIFT spectra show that the acidic sites on the Mn-doped catalyst surface were dominated by Bronsted acid sites at lower temperatures which play an essential role in the adsorption of mercury. Overall, This research reveals the effect of Mn additives on the promotion of adsorption capacity and catalytic oxidation efficiency of Hg-0, providing a promising approach to widen the effective temperature window of the catalyst.