Surface tailoring on bifunctional CuOx/MnO2 catalyst to promote the selective catalytic reduction of NO with NH3 and oxidation of CO with O2

Abstract

NO and CO are two primary pollutants in the sintering flue gas emission, posing significant challenges for the treatment. Under oxygen-enriched conditions, CO was easily oxidized to CO2 before participating in CO-SCR reaction as a reducing agent. Consequently, NH3-SCR technology coupled with CO oxidation reaction is a promising approach for simultaneous NO and CO removal. In this study, a series of bifunctional CuOx/MnO2 catalysts were synthesized using a combine of hydrothermal and wet impregnation methods, and their catalytic performance for simultaneous removal of NO and CO was assessed. CuOx/α-MnO2 catalyst displayed outstanding catalytic activity for both NO and CO, achieving over 80 % NO removal efficiency and 96 % CO conversion rate at 150 °C, while CuOx/β-MnO2 catalyst exhibited poor catalytic activity in the entire temperature range. Moreover, the interplay between the NH3-SCR and CO catalytic oxidation reactions was also explored. XPS results revealed that the concentration of Mn4+ and Cu+ species significantly influenced the catalytic activity of the catalysts for the simultaneous removal of NO and CO. Particularly, the presence of Mn4+ species promoted “fast SCR” reaction, whereas Cu+ species demonstrated higher reactivity for both NO reduction and CO oxidation. In situ DRIFTS analysis of transient reactions revealed that the L-H mechanism was followed over CuOx/α-MnO2 catalyst in the NH3-SCR reaction, while both the M-K and L-H mechanisms were observed in CO catalytic oxidation reaction.