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<p>High NO<sub><i>x</i></sub> emission concentrations and H<sub>2</sub>O contents in ammonia engine exhaust pose significant challenges to the catalyst activity and hydrothermal stability of conventional selective catalytic reduction (SCR) catalysts. This study involved synthesizing the Cu-SSZ-13 catalyst via a one-spot hydrothermal method and evaluating its efficacy for SCR after-treatment in ammonia engines, focusing on the effects of the NO<sub><i>x</i></sub> concentration and H<sub>2</sub>O content on the SCR reaction. The catalyst exhibited excellent SCR activity between 300 and 400&#xa0;°C, even under extreme conditions of 2000×10<sup>−6</sup> NO<sub><i>x</i></sub> and 20% H<sub>2</sub>O content, achieving conversion efficiencies exceeding 95% for both NO<sub><i>x</i></sub> and NH<sub>3</sub>. At temperatures below 300&#xa0;°C, H<sub>2</sub>O significantly inhibits catalyst activity; however, while increased NO<sub><i>x</i></sub> concentrations can mitigate this effect, excessively high NO<sub><i>x</i></sub> levels also impair catalyst performance. Above 300&#xa0;°C, the inhibitory effect of H<sub>2</sub>O diminishes, and elevated NO<sub><i>x</i></sub> concentrations enhance catalyst activity. Ammonia temperature programmed desorption (NH<sub>3</sub>-TPD) and in-situ diffuse reflectance infrared Fourier transform spectroscopy tests showed that at low temperatures, H<sub>2</sub>O competes with NH<sub>3</sub> for adsorption at Z<sub>2</sub>Cu sites, inhibiting the catalyst activity. At high temperatures, while this competition persists, the H<sub>2</sub>O-Z<sub>2</sub>Cu interaction becomes unstable, weakening the inhibitory effect. This research confirms the adaptability of Cu-SSZ-13 catalysts for the ammonia engine after-treatment and provides insights for developing more applicable after-treatment catalysts for future ammonia engines.</p> Graphical abstract <p></p>

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Mechanistic insights into the impact of high H2O and high-NOx exhaust from ammonia-fueled engines on Cu-SSZ-13 SCR catalyst activity

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Dongwei Yao,
  • Yi Fu,
  • Jiangling Song,
  • Yihe Zhang,
  • Jinpeng Du,
  • Haibin He,
  • Feng Wu,
  • Yinhuan Wang

摘要

High NOx emission concentrations and H2O contents in ammonia engine exhaust pose significant challenges to the catalyst activity and hydrothermal stability of conventional selective catalytic reduction (SCR) catalysts. This study involved synthesizing the Cu-SSZ-13 catalyst via a one-spot hydrothermal method and evaluating its efficacy for SCR after-treatment in ammonia engines, focusing on the effects of the NOx concentration and H2O content on the SCR reaction. The catalyst exhibited excellent SCR activity between 300 and 400 °C, even under extreme conditions of 2000×10−6 NOx and 20% H2O content, achieving conversion efficiencies exceeding 95% for both NOx and NH3. At temperatures below 300 °C, H2O significantly inhibits catalyst activity; however, while increased NOx concentrations can mitigate this effect, excessively high NOx levels also impair catalyst performance. Above 300 °C, the inhibitory effect of H2O diminishes, and elevated NOx concentrations enhance catalyst activity. Ammonia temperature programmed desorption (NH3-TPD) and in-situ diffuse reflectance infrared Fourier transform spectroscopy tests showed that at low temperatures, H2O competes with NH3 for adsorption at Z2Cu sites, inhibiting the catalyst activity. At high temperatures, while this competition persists, the H2O-Z2Cu interaction becomes unstable, weakening the inhibitory effect. This research confirms the adaptability of Cu-SSZ-13 catalysts for the ammonia engine after-treatment and provides insights for developing more applicable after-treatment catalysts for future ammonia engines.

Graphical abstract