Nickel-Doped Mn/TiO2 As an Efficient Catalyst for the Low-Temperature SCR of NO with NH3: Catalytic Evaluation and Characterizations

The current technology for post-combustion removal of NO is the selective catalytic reduction (SCR) of NO at medium to high temperatures. Industrially adopted catalysts and the existing commercial catalytic system suffers from the drop of N₂ selectivity at high temperatures (573-673 K), high conversion of SO₂ to SO₃, need to reheat the stack gas. The development of low-temperature SCR catalysts working at 150–250 °C would be the great resolution to avoid all the problems associated with the existing commercial catalytic system. For this purpose, we have prepared a series of titania-supported manganese-nickel catalysts by adopting a solution-impregnation method and evaluated for the low-temperature SCR of NO with NH₃ by varying Ni/Mn atomic ratio. Rationale for the best activity of our catalyst is investigated by various physico-chemical techniques such as XRD, N₂ physisorption, oxygen chemisorption, H₂-TPR, and XPS spectroscopy. XPS results illustrated extremely dominant MnO₂ phase over the Mn₂O₃ phase (Mn⁴⁺/Mn³⁺=96%), and high Mn⁴⁺/Ti ratio in the Mn-Ni(0.4)/TiO₂ catalyst. TPR results revealed that the addition of nickel oxide to titania-supported manganese results in stabilization of the former in the form of MnO₂, which is reduced at lower temperatures, compared to Mn₂O₃. Structural, elemental characterizations and the catalytic performance of the materials will be discussed in the presentation.