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Effect of Ceria Doping on the Catalytic Activity and SO2 Resistance of MnOx/TiO2 Catalysts for the Selective Catalytic Reduction of NO with NH3 at Low Temperatures

Category: Control Techniques and Strategy

Volume: 20 | Issue: 3 | Pages: 477-488
DOI: 10.4209/aaqr.2019.10.0546
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To cite this article:
Wang, Q., Zhou, J., Zhang, J., Zhu, H., Feng, Y. and Jin, J. (2020). Effect of Ceria Doping on the Catalytic Activity and SO2 Resistance of MnOx/TiO2 Catalysts for the Selective Catalytic Reduction of NO with NH3 at Low Temperatures. Aerosol Air Qual. Res. 20: 477-488. doi: 10.4209/aaqr.2019.10.0546.

Qiulin Wang1,2, Jianjian Zhou1, Jianchao Zhang1, Hao Zhu1, Yuheng Feng 3, Jing Jin1,2

  • 1 School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
  • 2 Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
  • 3 Thermal and Environmental Engineering Institute, Tongji University, Shanghai 200092, China

Highlights

  • The surface acidity and redox ability of MnOx/TiO2 is improved by Ce addition.
  • The MnOx -CeO2/TiO2 catalytic activity is correlated with the exposure of Mn atom.
  • Appropriate amount of Ce increase the surface exposure of Mn atom.
  • The presence of Ce speeds up the reoxidation from Mn3+ to the active Mn4+ species.
  • CeO2 helps enhance the oxygen storage/release capability of MnOx -CeO2/TiO2 catalyst.

Abstract

With its industrial applicability and low energy consumption, a process for implementing the NH3-SCR of NO at low temperatures is urgently needed. In this study, MnOx-CeO2/TiO2 (MnCe/Ti) catalysts doped with different amounts of Ce were prepared and experimentally examined for their NH3-SCR activity between 100°C and 400°C. Adding a small amount of Ce (at the Ce/Ti mole ratio of 0.05) elevated the exposure of Mn atoms on the catalyst surface, resulting in the highest NH3-SCR activity occurring between 100°C and 200°C (with a conversion rate of above 98% for the NO at 175°C). Further increasing the Ce content, however, diminished the catalytic performance. Moreover, the NH3-SCR of NO during oxidization or reduction atmosphere confirmed that oxygen species bound to the exposed Mn atoms were released more easily and the resulting vacancies were more likely to be replenished by O2 at low temperatures. In addition, incorporating Ce enhanced the SO2 resistance of the MnCe/Ti, mainly by inhibiting the accumulation of ammonium sulfates and the preferential sulfation of the Ce dopants.

Keywords

MnOx/TiO2 Ce modification Low temperature SCR deNOx SO2 poisoning


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