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<p>Developing high-performance Ir-based catalysts for the selective catalytic reduction of NO<sub>x</sub> with CO (CO-SCR) under oxygen-rich conditions remains a formidable challenge. Here, we identify a hydroxyl-mediated reaction pathway over IrIn/Beta catalysts, termed the ammonium sulfate mechanism. Tailoring the support’s Si/Al ratio modulates surface hydroxyls (Si–OH–Al), governing the rapid transformation of ammonium sulfate intermediates. Density functional theory calculations confirm that the formation of these intermediates is thermodynamically spontaneous and highly exothermic. These in situ-generated species rapidly decompose at 167 °C to release NH<sub>3</sub>, triggering a built-in NH<sub>3</sub>-SCR cycle. Notably, the IrIn/Beta-30 catalyst achieves 88% NO<sub>x</sub> conversion under harsh simulated industrial conditions (15% O<sub>2</sub> and 200 ppm SO<sub>2</sub>). This work establishes SO<sub>2</sub> as a contributing factor, providing a rational design strategy for robust denitration catalysts applicable to real-world industrial flue gas.</p>

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Hydroxyl‑Mediated SO2 Promotion Enables Efficient NOx Reduction by CO over IrIn/Beta under Oxygen‑Rich Conditions

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月24日

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  • Yujie Yuan,
  • Yixi Wang,
  • Wenqing Xu,
  • Yanhong Wang,
  • Yang Yang,
  • Xiubiao Ma,
  • Tingyu Zhu

摘要

Developing high-performance Ir-based catalysts for the selective catalytic reduction of NOx with CO (CO-SCR) under oxygen-rich conditions remains a formidable challenge. Here, we identify a hydroxyl-mediated reaction pathway over IrIn/Beta catalysts, termed the ammonium sulfate mechanism. Tailoring the support’s Si/Al ratio modulates surface hydroxyls (Si–OH–Al), governing the rapid transformation of ammonium sulfate intermediates. Density functional theory calculations confirm that the formation of these intermediates is thermodynamically spontaneous and highly exothermic. These in situ-generated species rapidly decompose at 167 °C to release NH3, triggering a built-in NH3-SCR cycle. Notably, the IrIn/Beta-30 catalyst achieves 88% NOx conversion under harsh simulated industrial conditions (15% O2 and 200 ppm SO2). This work establishes SO2 as a contributing factor, providing a rational design strategy for robust denitration catalysts applicable to real-world industrial flue gas.