Catalytic performance and mechanism of Mn-Fe/TiO₂ for low-temperature selective reduction of NO with NH₃

Mn-Fe/TiO₂ catalyst was prepared by co-precipitation depositing method. It has high catalytic activity in the range of 80-160°C. The NO_x conversation obtains 92.5% as low as 80°C, with φ(H₂O)=6% and φ(SO₂)=0.01%, it yields 95% at 120°C steadily. The x-ray diffraction (XRD) profiles show iron oxide interacts with manganese dioxide, enhances the dispersion and reduces the crystallinity of both oxides on titania. The Fourier transform infrared (FT-IR) and in-situ infrared (Situ IR) spectra suggest that NH₃ adsorbs on Lewis acid sites of MnO₂ mainly in amide -NH₂ specie, then reacts with NO to intermediate product NH₂NO, giving rise to N₂ and H₂O, while a few of it adsorb on Br0nst acid sites in the form of NH⁴⁺. O₂ can increase both of routes on the above two kinds of acid sites.