Promotion effect of Zr incorporation on catalytic performance over MnV₂O₆ catalyst for NO_x removal in a wide temperature range

The Zr-incorporated MnV₂O₆ catalyst was synthesized using the hydrothermal method for the selective catalytic reduction (SCR) of NO with NH₃. The optimized catalyst exhibited superior catalytic performance, achieving over 80% NO conversion and nearly 100% N₂ selectivity in a wide temperature from 225 to 375 °C. Various characterization techniques, including XRD, SEM, N₂ adsorption–desorption, XPS, H₂‒TPR, and NH₃‒TPD, were performed to investigate the influence of Zr incorporation on the SCR performance. The introduction of Zr raised the specific surface area to 125.5 m²/g and elevated the proportions of Mn³⁺ (26.8%), V⁵⁺ (60.2%), and O_α (25.1%) ratio, which was conducive to the activation and adsorption of reactants. The Zr also boosted total H₂ consumption (224.3 μmol/g) and increased medium acid amount (128.4 μmol/g). This adjustment improved the surface acidity and redox ability of the catalyst to an optimal level, which is conducive to the activation of NH₃ and the reduction of NO. The enlarged specific surface area of Zr–MnV₂O₆ also diluted the surface acidic and redox ability per unit surface area, thus inhibiting the unnecessary oxidation of NH₃ to N₂O and further improving the N₂ selectivity.