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<p>CeMn-rare earth tailings catalysts with wide temperature window and high denitrification were prepared by hydrothermal method. The results show that the optimum ratio of Ce/Mn is 1:1, and the NO<sub>x</sub> conversion can reach 90% at the range of 100–300&#xa0;°C. The introduction of Mn improves the dispersion of CeCO<sub>3</sub>F on the catalyst surface, exposing more active adsorption sites. In addition, the interaction of MnO<sub>x</sub> with Ce and Fe in the rare earth tailings promotes redox, which facilitates the oxidation of NO to NO<sub>2</sub>. Meanwhile Mn also increases the abundance and stability of NO adsorption species and Lewis acid sites, forming important intermediates such as Mn<sup>4+</sup>-ONO<sub>2</sub>, NH<sub>4</sub>NO<sub>3</sub> and NH<sub>2</sub>NO. But the strong oxidizing ability of Mn and the reaction between monodentate nitrate and adsorbed NH<sub>3</sub> results in N<sub>2</sub> selectivity decrease rapidly. Catalysts follow both E-R and L–H mechanism in the NH<sub>3</sub>-SCR reaction. Moreover, the excellent redox performance and Lewis acid sites improve the NH<sub>3</sub>-SCR catalytic activity together.</p>

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Denitrification performance and mechanism of NH3-SCR rare earth tailings catalyst modified by Ce combined with Mn

  • 期刊论文

  • 发表日期：

    2025年1月8日

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  • Limin Hou,
  • Xiankang Sun,
  • Jiaming Li,
  • Linbo Lu,
  • Tiantian Wang,
  • Wenfei Wu

摘要

CeMn-rare earth tailings catalysts with wide temperature window and high denitrification were prepared by hydrothermal method. The results show that the optimum ratio of Ce/Mn is 1:1, and the NOx conversion can reach 90% at the range of 100–300 °C. The introduction of Mn improves the dispersion of CeCO3F on the catalyst surface, exposing more active adsorption sites. In addition, the interaction of MnOx with Ce and Fe in the rare earth tailings promotes redox, which facilitates the oxidation of NO to NO2. Meanwhile Mn also increases the abundance and stability of NO adsorption species and Lewis acid sites, forming important intermediates such as Mn4+-ONO2, NH4NO3 and NH2NO. But the strong oxidizing ability of Mn and the reaction between monodentate nitrate and adsorbed NH3 results in N2 selectivity decrease rapidly. Catalysts follow both E-R and L–H mechanism in the NH3-SCR reaction. Moreover, the excellent redox performance and Lewis acid sites improve the NH3-SCR catalytic activity together.