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<p>In the NH<sub>3</sub> selective catalytic oxidation (NH<sub>3</sub>-SCO) reaction, non-noble metal catalysts have attracted much attention due to their low cost and high N<sub>2</sub> selectivity at low temperatures. However, the significant decrease in N<sub>2</sub> selectivity at high temperatures remains a significant challenge. In this work, we treated TiO<sub>2</sub> support with sulfuric acid to balance redox performance and surface acidity, thereby improving the N<sub>2</sub> selectivity of Cu–Ce/TiO<sub>2</sub> catalyst. Compared to Cu–Ce/TiO<sub>2</sub> catalyst, (Cu–Ce/TiO<sub>2</sub>)-S<sub>0.05</sub> catalyst (sulfuric acid added during Cu and Ce co-impregnation, where the molar ratio of S to Ti is 0.05) showed a 20.8% increase in N<sub>2</sub> selectivity at 400&#xa0;°C. After treating TiO<sub>2</sub> with an excessive amount of sulfuric acid, its catalytic activity significantly decreased. This was attributed to the excessive sulfuric acid treatment resulting in the aggregation of Cu species, thereby decreasing the number of redox sites on the catalyst surface and severely disrupting the balance between redox and acid properties. In situ DRIFTS results showed that, in the NH<sub>3</sub>-SCO reaction, Cu–Ce/TiO<sub>2</sub> and (Cu–Ce/TiO<sub>2</sub>)-S<sub>0.05</sub> catalysts followed dual pathways involving internal selective catalytic reduction and amide (–NH) mechanisms. However, after sulfuric acid treatment, the number of acid sites on the catalyst surface increased significantly, and abundant NH<sub>3</sub> species on the surface could effectively reduce NO<sub><i>x</i></sub> to N<sub>2</sub> and H<sub>2</sub>O through the i-SCR mechanism.</p>

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Enhancing N2 selectivity via acidity modulation of Cu–Ce/TiO2 catalyst in NH3 selective catalytic oxidation

  • 期刊论文

  • 发表日期：

    2025年11月1日

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  • You Tian,
  • Zhitao Han,
  • Hongzhe Zhao,
  • Qingliang Zeng

摘要

In the NH3 selective catalytic oxidation (NH3-SCO) reaction, non-noble metal catalysts have attracted much attention due to their low cost and high N2 selectivity at low temperatures. However, the significant decrease in N2 selectivity at high temperatures remains a significant challenge. In this work, we treated TiO2 support with sulfuric acid to balance redox performance and surface acidity, thereby improving the N2 selectivity of Cu–Ce/TiO2 catalyst. Compared to Cu–Ce/TiO2 catalyst, (Cu–Ce/TiO2)-S0.05 catalyst (sulfuric acid added during Cu and Ce co-impregnation, where the molar ratio of S to Ti is 0.05) showed a 20.8% increase in N2 selectivity at 400 °C. After treating TiO2 with an excessive amount of sulfuric acid, its catalytic activity significantly decreased. This was attributed to the excessive sulfuric acid treatment resulting in the aggregation of Cu species, thereby decreasing the number of redox sites on the catalyst surface and severely disrupting the balance between redox and acid properties. In situ DRIFTS results showed that, in the NH3-SCO reaction, Cu–Ce/TiO2 and (Cu–Ce/TiO2)-S0.05 catalysts followed dual pathways involving internal selective catalytic reduction and amide (–NH) mechanisms. However, after sulfuric acid treatment, the number of acid sites on the catalyst surface increased significantly, and abundant NH3 species on the surface could effectively reduce NOx to N2 and H2O through the i-SCR mechanism.