Mn/TiO2 and Mn–Fe/TiO2 catalysts synthesized by deposition precipitation—promising for selective catalytic reduction of NO with NH3 at low temperatures

• Mn–Fe/TiO2 catalysts prepared by deposition precipitation showed superior low-temperature SCR of NO with NH3.
• Superior low-temperature activity can be due to high acidity and ease of reduction of active elements.
• The optimum formulations might be used as tail-end SCR catalysts.

Mn/TiO2 and Mn–Fe/TiO2 catalysts have been prepared by impregnation (IMP) and deposition-precipitation (DP) techniques and characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR, XPS and TGA. 25 wt% Mn0.75Fe0.25Ti-DP catalyst, prepared by deposition precipitation with ammonium carbamate (AC) as a precipitating agent, showed superior low-temperature SCR (selective catalytic reduction) of NO with NH3. The superior catalytic activity of the 25 wt% Mn0.75Fe0.25Ti-DP catalyst is probably due to the presence of amorphous phases of manganese oxide, iron oxide, high surface area, high total acidity, acid strength and ease of reduction of manganese oxide and iron oxide on TiO2 in addition to formation of an SCR active MnOx phase with high content of chemisorbed oxygen (Oα). The optimum catalyst might be used as tail-end SCR catalysts in, e.g., biomass-fired power plants and waste incineration plants.

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