Comparative study on transition element doped Mn–Zr–Ti-oxides catalysts for the low-temperature selective catalytic reduction of NO with NH 3

Abstract

The effect of Cu, Fe, Co, Ni, Cr and Zn on Mn–Zr–Ti mixed oxides catalysts introduced by co-precipitation was investigated. The Mn–Co catalyst showed the highest NO conversion near 100% and a good N₂ selectivity > 90% at 200–300 °C. Comparing with the Mn–non catalyst, the Mn–Co catalyst presented a higher reaction rate constant at 120 °C with 23.3 ml s⁻¹ g⁻¹. The Mn–Co catalyst possesses a high concentration of Mn⁴⁺ and surface labile oxygen, which should improve the redox property and increase catalytic activity. Additionally, the Mn–Co showed the highest ratio of Lewis acid sites. The resistance to SO₂ was improved by incorporation of Co. In summary, the Mn–Zr–Ti mixed oxides catalyst have a better N₂ selectivity than other Mn-based catalysts and could be improved by doping with Co.