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<p>Ammonia fuel, as a promising zero-carbon energy carrier, faces environmental challenges due to high-concentration NH<sub>3</sub> slip in exhaust emissions. Here we develop an efficient Ag-Mn/Al<sub>2</sub>O<sub>3</sub> bimetallic catalyst for NH<sub>3</sub> selective catalytic oxidation (NH<sub>3</sub>-SCO). Mechanistic investigations reveal the dual role of Mn in this catalytic system: On one hand, Mn preferentially occupies the hydroxyl anchoring sites on Al<sub>2</sub>O<sub>3</sub> surface, inducing Ag species aggregation to form nanoparticles with superior O<sub>2</sub> activation capability; on the other hand, highly dispersed Mn species provide abundant Lewis acid sites, significantly enhancing NH<sub>3</sub> adsorption and activation. Through this synergistic effect, the 2Ag3Mn/Al<sub>2</sub>O<sub>3</sub> catalyst achieves complete conversion of 7.5 mg/L NH<sub>3</sub> at 300 °C. Further studies demonstrate a distinct temperature-dependent effect on the catalyst’s reaction mechanism, transitioning from -NH-dominated pathway at low temperatures to i-SCR mechanism at high temperatures. This work not only elucidates the mechanism of Mn’s dual role in structural regulation and functional sites but also provides new insights into the rational design of efficient NH<sub>3</sub>-SCO catalysts.</p>

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Dual role of Mn in regulating structural and functional sites of Ag-based catalysts for selective catalytic oxidation of high-concentration NH3

  • 期刊论文

  • 发表日期：

    2025年8月30日

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  • Yating Wang,
  • Zhao Li,
  • Shaoxin Chen,
  • Fulai Lin,
  • Chunxue Wang,
  • Yixing Ma,
  • Kai Li,
  • Ping Ning,
  • Fei Wang

摘要

Ammonia fuel, as a promising zero-carbon energy carrier, faces environmental challenges due to high-concentration NH3 slip in exhaust emissions. Here we develop an efficient Ag-Mn/Al2O3 bimetallic catalyst for NH3 selective catalytic oxidation (NH3-SCO). Mechanistic investigations reveal the dual role of Mn in this catalytic system: On one hand, Mn preferentially occupies the hydroxyl anchoring sites on Al2O3 surface, inducing Ag species aggregation to form nanoparticles with superior O2 activation capability; on the other hand, highly dispersed Mn species provide abundant Lewis acid sites, significantly enhancing NH3 adsorption and activation. Through this synergistic effect, the 2Ag3Mn/Al2O3 catalyst achieves complete conversion of 7.5 mg/L NH3 at 300 °C. Further studies demonstrate a distinct temperature-dependent effect on the catalyst’s reaction mechanism, transitioning from -NH-dominated pathway at low temperatures to i-SCR mechanism at high temperatures. This work not only elucidates the mechanism of Mn’s dual role in structural regulation and functional sites but also provides new insights into the rational design of efficient NH3-SCO catalysts.