Interaction between Nickel Oxide and Support Promotes Selective Catalytic Reduction of NO with C H.

Selective catalytic reduction of nitrogen oxides (NO ) with C H (C H -SCR) was investigated over NiO catalysts supported on different metal-oxides. A NiAlO mixed oxide phase was formed over NiO/γ-Al O catalyst, inducing an immediate interaction between NiO and AlO 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 O catalyst exhibited the highest NO conversion at temperature higher than 450 °C, but a poor C H 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 O catalyst. In situ transient reactions further verified the Langmuir-Hinshelwood mechanism for C H -SCR, where both gaseous NO and C H were adsorbed and activated on catalyst surface and reacted to generate N . Due to the strong metal-support interaction over NiO/γ-Al O catalyst, both nitrate and C H O intermediates were well preserved to attain high C H -SCR activity.