In the process of denitrification, the reaction between NO and CO (NO + CO → N2 + CO2) occurs. There will be a redox reaction between copper, nickel and cerium (Cu2+ + Ce3+ → Cu+ + Ce4+, Ni3+ + Ce3+ → Ni2+ + Ce4+).

To study the preparation principle of Cu−Ni/AC catalysts and the mechanism of low-temperature CO-selective catalytic reduction (SCR) denitration, Cu−Ni/AC catalysts with different metal loadings were prepared by the isometric ultrasonic impregnation method. It was determined that the 10Cu−4Ni/AC catalyst had the best CO-SCR low-temperature denitration rate of 94.2% in 5% O 2 and at the denitration temperature of 150 °C. The characterization of Cu−Ni/AC by scanning electron microscopy (SEM), Brunauer−Emmett−Teller (BET), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and CO temperature-programmed desorption (TPD) confirmed that the copper−nickel-coordinated loading resulted in the Cu−Ni/AC catalyst having a rich pore structure and a large number of acidic oxygen-containing functional groups. The spherical particles of copper−nickel oxide with good thermal stability were highly dispersed on the AC surface, allowing the copper and nickel metal ions to enter the graphite or graphite-like microcrystalline structure and split into smaller irregular graphene fragments, thus forming a large number of denitration reaction units on the AC surface. The oxidation−reduction reaction (Cu 2+ + Ni 2+ → Cu + + Ni 3+ ) between copper and nickel metal oxides produced active oxygen vacancies, which increased the amount of oxygen (Oa) adsorbed on the surface, especially acidic adsorption sites on the surface; this promoted the higher adsorption of reaction gases (CO, O 2 , NO), leading to the conversion of a standard SCR reaction to a fast SCR reaction, which, in turn, improved the denitration efficiency. The CO-SCR denitrification mechanism model of the Cu−Ni/AC catalyst was discovered and established according to the experimental results and theoretical analysis. The related research provides a reference for carbon-based catalysts for low-temperature CO-SCR denitration.

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