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<p>MnO<sub><i>x</i></sub>–CeO<sub>2</sub> catalysts for the low-temperature selective catalytic reduction (SCR) of NO remain vulnerable to water and sulfur poisoning, limiting their practical applications. Herein, we report a hydrophobic-modified MnO<sub><i>x</i></sub>–CeO<sub>2</sub> catalyst that achieves enhanced NO conversion rate and stability under harsh conditions. The catalyst was synthesized by decorating MnO<sub><i>x</i></sub> crystals with amorphous CeO<sub>2</sub>, followed by loading hydrophobic silica on the external surfaces. The hydrophobic silica allowed the adsorption of NH<sub>3</sub> and NO and diffusion of H, suppressed the adsorption of H<sub>2</sub>O, and prevented SO<sub>2</sub> interaction with the Mn active sites, achieving selective molecular discrimination at the catalyst surface. At 120°C, under H<sub>2</sub>O and SO<sub>2</sub> exposure, the optimal hydrophobic catalyst maintains 82% NO conversion rate compared with 69% for the unmodified catalyst. The average adsorption energies of NH<sub>3</sub>, H<sub>2</sub>O, and SO<sub>2</sub> decreased by 0.05, 0.43, and 0.52 eV, respectively. The NO reduction pathway follows the Eley–Rideal mechanism, NH<sub>3</sub>* + * → NH<sub>2</sub>* + H* followed by NH<sub>2</sub>* + NO* → N<sub>2</sub>* + H<sub>2</sub>O*, with NH<sub>3</sub> dehydrogenation being the rate determining step. Hydrophobic modification increased the activation energy for H atom transfer, leading to a minor decrease in the NO conversion rate at 120°C. This work demonstrates a viable strategy for developing robust NH<sub>3</sub>-SCR catalysts capable of efficient operation in water- and sulfur-rich environments.</p>

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Stability enhancement of MnOx–CeO2 via hydrophobic modification for NO reduction by NH3

  • 期刊论文

  • 发表日期：

    2025年12月22日

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  • Boyu Wu,
  • Shengen Zhang,
  • Shengyang Zhang,
  • Bo Liu,
  • Bolin Zhang

摘要

MnOx–CeO2 catalysts for the low-temperature selective catalytic reduction (SCR) of NO remain vulnerable to water and sulfur poisoning, limiting their practical applications. Herein, we report a hydrophobic-modified MnOx–CeO2 catalyst that achieves enhanced NO conversion rate and stability under harsh conditions. The catalyst was synthesized by decorating MnOx crystals with amorphous CeO2, followed by loading hydrophobic silica on the external surfaces. The hydrophobic silica allowed the adsorption of NH3 and NO and diffusion of H, suppressed the adsorption of H2O, and prevented SO2 interaction with the Mn active sites, achieving selective molecular discrimination at the catalyst surface. At 120°C, under H2O and SO2 exposure, the optimal hydrophobic catalyst maintains 82% NO conversion rate compared with 69% for the unmodified catalyst. The average adsorption energies of NH3, H2O, and SO2 decreased by 0.05, 0.43, and 0.52 eV, respectively. The NO reduction pathway follows the Eley–Rideal mechanism, NH3* + * → NH2* + H* followed by NH2* + NO* → N2* + H2O*, with NH3 dehydrogenation being the rate determining step. Hydrophobic modification increased the activation energy for H atom transfer, leading to a minor decrease in the NO conversion rate at 120°C. This work demonstrates a viable strategy for developing robust NH3-SCR catalysts capable of efficient operation in water- and sulfur-rich environments.