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Abstract Series of Fe-modified MnO 2 catalysts were prepared to improve low-temperature NO oxidation. Introduction of Fe3+ resulted in a phase transformation from α-MnO 2 to ε-MnO 2. Hexagonal Fe 0.32 MnO 2 exhibited the highest activity with the lowest T 50 of 156 °C and the maximum NO conversion of 80% at 250 °C. It also possessed the best reducibility and abundant readily available oxygen species, which facilitated the oxidation of NO. Major differences in the NO oxidation reaction route between α-MnO 2 and Fe 0.32 MnO 2 were the adsorption sites and the type of intermediates. The synergetic effect between Fe and Mn enhanced the activation of NO and O 2. Highlights • Hexagonal Fe 0.32 MnO 2 exhibited the highest NO oxidative activity with the T 50 of only 156 °C. • The introduction of Fe could greatly help to promote the reducibility and increase available oxygen species. • The introduction of Fe changed the type of intermediates during reactions. [ABSTRACT FROM AUTHOR]

Mn/Ce/Ti and Mn/Ce/Nb/Ti catalysts were synthesized using a precipitation method and their catalytic activities for NO selective reduction with NH 3 at low temperatures were evaluated. Nb doping not only improved the activity of the catalyst over a wide temperature range but also restricted the generation of NO 2 and N 2 O. The Mn/Ce/Nb/Ti catalyst displayed 100% NO conversion from 150 to 250 °C and >90% N 2 selectivity below 250 °C. The specific surface area of the catalyst was increased and its surface acidity was strengthened after Nb doping. Moreover, Nb doping increased the NO oxidation ability and lowered the NH 3 oxidation activity of the catalyst. All the above factors contributed to enhancing the overall NH 3 -SCR performance of the Mn/Ce/Nb/Ti catalyst compared with that of the Mn/Ce/Ti one. The long-term stability and resistance to H 2 O and SO 2 of the Mn/Ce/Nb/Ti catalyst were also evaluated. [ABSTRACT FROM AUTHOR]