NH₃ emissions from industrial sources and possibly future energy production constitute a threat to human health because of their toxicity and participation in PM_2.5 formation. Ammonia selective catalytic oxidation to N₂ (NH₃–SCO) is a promising route for NH₃ emission control, but the mechanistic origin of achieving high N₂ selectivity remains elusive. Here we constructed a highly N₂-selective CuO/TiO₂ catalyst and proposed a CuO_x dimer active site based on the observation of a quadratic dependence of NH₃–SCO reaction rate on CuO_x loading, ac-STEM, and ab initio thermodynamic analysis. Combining this with the identification of a critical N₂H₄ intermediate by in situ DRIFTS characterization, a comprehensive N₂H₄-mediated reaction pathway was proposed by DFT calculations. The high N₂ selectivity originated from the preference for NH₂ coupling to generate N₂H₄ over NH₂ dehydrogenation on the CuO_x dimer active site. This work could pave the way for the rational design of efficient NH₃–SCO catalysts.

中文翻译：

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揭示 CuO 基催化剂上氨选择性催化氧化高 N2 选择性的机理起源


工业来源和未来能源生产中的 NH ₃ 排放对人类健康构成威胁，因为它们具有毒性并参与 PM _2.5 的形成。氨选择性催化氧化成N ₂ (NH ₃ –SCO) 是控制NH ₃ 排放的一条有前途的途径，但实现高N ₃ 的机理根源< b5> 选择性仍然难以捉摸。在这里，我们构建了一种高度N ₂ 选择性的CuO/TiO ₂ 催化剂，并基于对NH的二次依赖性的观察提出了CuO _x 二聚体活性位点 ₃ – CuO _x 负载上的 SCO 反应速率、ac-STEM 和从头算热力学分析。将此与通过原位 DRIFTS 表征对关键 N ₂ H ₄ 中间体的鉴定相结合，综合 N ₂ H ₄ -通过DFT计算提出了介导的反应途径。 N ₂ 的高选择性源于 NH ₂ 优先于 NH ₂ H ₄ CuO _x 二聚体活性位点上的脱氢。这项工作可以为高效 NH ₃ –SCO 催化剂的合理设计铺平道路。