Influence of Co-Doped Metals On Mn/TiO2 Catalyst and Its Effect On Selective Reduction of NO with NH3 At Low-Temperatures

In recent years, there is an increasing interest in developing a novel low-temperature (353–523 K) SCR catalyst for the removal of NO_x. In our earlier studies, manganese-based titania-supported catalysts have been established successfully for the low-temperature selective catalytic reduction (SCR) of NO. In continuation of our research in low-temperature SCR of NO, we prepared a series of Mn-Me/TiO₂ (Me = Cr, Fe, Co, Ni, Cu, Zn, Ce, and Zr) catalysts by adopting wet-impregnation method and investigated for the low-temperature SCR of NO with NH₃ by varying Me/Mn atomic ratio. The catalytic performance of these materials has been carried out with a high gas hourly space velocity (GHSV) 50,000 h^-1, at the temperature range 433-523K. Physico-chemical techniques such as XRD, N₂ physisorption, TPR, XPS, and in-situ FTIR were used to investigate the influence of co-doped metals. Our XPS results illustrated that the MnO₂ phase is extremely dominant over the Mn₂O₃ phase (Mn⁴⁺/Mn³⁺=22.31, 96%) in our best catalyst Mn-Ni(0.4)/TiO₂ anatase, whereas Mn₂O₃ phase is in competition with MnO₂ in other catalysts (Mn⁴⁺/Mn³⁺=1.34-12.67). Increase in reducibility of manganese and absence of the high-temperature (736 K) peak in H₂-TPR studies, suggested that the dominant phase is MnO₂ in Mn-Ni/TiO₂ catalyst. The catalytic performance and characterizations of optimized materials will be discussed in the presentation.