Dispersion and valence state of MnO2/Ce(1 − x)ZrxO2–TiO2 for low temperature NH3-SCR

• CeO2 aggregation in the MnOx/CeO2–TiO2 is suppressed with Zr doping.
• Mn4 +/Mn3 + ratio is enhanced with increasing Zr/Ce ratio.
• Catalytic activity is improved by increase of dispersion and Mn4 +/Mn3 + ratio.

Zr-doped MnOx/CeO2–TiO2 for high temperature stability was investigated in terms of its dispersion and oxidation state. Aggregation of cerium oxide was observed in MnOx/CeO2–TiO2, but the Zr-doped catalyst was well dispersed. An increase of the Mn4 +/Mn3 + ratio was confirmed with a Zr addition through valence state analysis. De-NOx efficiency of the catalyst was increased to 40–45% by Zr addition at low temperature (150–200 °C). The substitution of Zr led the catalyst to improve the de-NOx efficiency, with a high dispersion and MnO2 ratio.