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<p>Fly ash (FA) is rich in SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub>, exhibiting potential as a catalyst support for selective catalytic reduction (SCR) reactions. However, its practical application is restricted due to inert oxygen species and insufficient acidic sites. Herein, a series of fly ash-based catalysts were prepared via a sequential method combining acid pretreatment and wet impregnation. The synthesized Mn-Ce/AFA catalyst exhibited outstanding low-temperature denitration performance, reaching a NO<sub><i>x</i></sub> conversion rate of 100% at 150 °C. Additionally, the Mn-Ce/AFA catalyst showed satisfactory H<sub>2</sub>O vapor tolerance, with the NO<sub><i>x</i></sub> conversion rate maintaining approximately 95% when exposed to 5 vol% water vapor. Compared with the Mn-Ce/Ti catalysts, the Mn-Ce/AFA catalyst exhibited elevated levels of Mn<sup>4+</sup> and Ce<sup>3+</sup>, indicating enhanced electron transfer in the Mn<sup>3+</sup> + Ce<sup>4+</sup> ⇌ Mn<sup>4+</sup> + Ce<sup>3+</sup> cycle. Results from H<sub>2</sub>-temperature-programmed reduction (H<sub>2</sub>-TPR) and NH<sub>3</sub>-temperature-programmed desorption (NH<sub>3</sub>-TPD) suggested that Ce-Mn co-doping enhanced the catalyst’s reducibility and the adsorption strength of NH<sub>3</sub> on Lewis acid sites. <i>In-situ</i> diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results and NO oxidation tests revealed that the enhanced NO oxidation capacity promoted the generation of key monodentate nitrite species, while the strengthened Lewis acidity facilitated the NH<sub>3</sub> activation process. This work introduces an innovative approach to convert fly ash into efficient catalysts for environmental remediation, demonstrating waste valorization in green chemistry.</p>

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Mechanistic insight into Mn-Ce synergy drives efficient low-temperature SCR over fly ash

  • 期刊论文

  • 发表日期：

    2026年1月20日

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  • Kaili Chi,
  • Luyang Zhao,
  • Xiao Zhu,
  • Hongyuan Ma,
  • Yue Xuan,
  • Penghao An,
  • Bin Wang,
  • Yang Yun,
  • Dong Wang

摘要

Fly ash (FA) is rich in SiO2 and Al2O3, exhibiting potential as a catalyst support for selective catalytic reduction (SCR) reactions. However, its practical application is restricted due to inert oxygen species and insufficient acidic sites. Herein, a series of fly ash-based catalysts were prepared via a sequential method combining acid pretreatment and wet impregnation. The synthesized Mn-Ce/AFA catalyst exhibited outstanding low-temperature denitration performance, reaching a NOx conversion rate of 100% at 150 °C. Additionally, the Mn-Ce/AFA catalyst showed satisfactory H2O vapor tolerance, with the NOx conversion rate maintaining approximately 95% when exposed to 5 vol% water vapor. Compared with the Mn-Ce/Ti catalysts, the Mn-Ce/AFA catalyst exhibited elevated levels of Mn4+ and Ce3+, indicating enhanced electron transfer in the Mn3+ + Ce4+ ⇌ Mn4+ + Ce3+ cycle. Results from H2-temperature-programmed reduction (H2-TPR) and NH3-temperature-programmed desorption (NH3-TPD) suggested that Ce-Mn co-doping enhanced the catalyst’s reducibility and the adsorption strength of NH3 on Lewis acid sites. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results and NO oxidation tests revealed that the enhanced NO oxidation capacity promoted the generation of key monodentate nitrite species, while the strengthened Lewis acidity facilitated the NH3 activation process. This work introduces an innovative approach to convert fly ash into efficient catalysts for environmental remediation, demonstrating waste valorization in green chemistry.