Cu–Ni/AC Catalyst for Low-Temperature CO-Selective Catalytic Denitration Mechanism

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% O2 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 (Cu2+ + Ni2+ → Cu+ + Ni3+) 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, O2, 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.