Mesoporous MnOx-CeO2 composites for NH3-SCR: the effect of preparation methods and a third dopant

In this study, different preparation methods including an oxalate route, a nano-casting strategy and a traditional co-precipitation route were applied to obtain MnOx-CeO2 mixed oxides for selective catalytic reduction (SCR) of NO with NH3. The catalyst prepared from the oxalate route showed improved performance for NOx conversion and SO2 + H2O durability. To further improve the SO2 and H2O resistance of catalysts, ternary oxides were prepared from the oxalate route. The catalysts were studied by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy (XPS), H-2 temperature-programmed reduction (H-2-TPR), NH3 temperature-programmed desorption (NH3-TPD), SO2 temperature-programmed desorption (SO2-TPD), and in situ diffuse reflectance infrared fourier transform spectroscopy (in situ DRIFTS). The nickel-manganese-cerium ternary oxide showed the best SO2 and H2O durability. The reason can be ascribed to its smaller pores, amorphous structure, and moderate amount of surface Mn3+/oxygen species, which could decrease chemical adsorption of SO2.