Interaction between Nickel Oxide and Support Promotes Selective Catalytic Reduction of NOx with C3H6

Abstract Selective catalytic reduction of nitrogen oxides (NO x ) with C 3 H 6 (C 3 H 6 ‐SCR) was investigated over NiO catalysts supported on different metal‐oxides. A NiAlO x mixed oxide phase was formed over NiO/γ‐Al 2 O 3 catalyst, inducing an immediate interaction between NiO x and AlO x species. Such interaction resulted in a charge transfer from Ni to Al site and the formation of Ni species in high oxidation state. In comparison to other NiO‐loaded catalysts, NiO/γ‐Al 2 O 3 catalyst exhibited the highest NO x conversion at temperature higher than 450 °C, but a poor C 3 H 6 oxidation activity due to the decreased nucleophilicity for surface oxygen species. By temperature‐programed NO oxidation, it is indicated that nitrate species were rapidly formed and stably maintained at high temperature over NiO/γ‐Al 2 O 3 catalyst. In situ transient reactions further verified the Langmuir–Hinshelwood mechanism for C 3 H 6 ‐SCR, where both gaseous NO and C 3 H 6 were adsorbed and activated on catalyst surface and reacted to generate N 2 . Due to the strong metal‐support interaction over NiO/γ‐Al 2 O 3 catalyst, both nitrate and C x H y O z intermediates were well preserved to attain high C 3 H 6 ‐SCR activity.