Investigations on the Antimony Promotional Effect on CeO2-WO3/TiO2 for Selective Catalytic Reduction of NOx with NH3

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• 作者：Lijun Yan ; Yangyang Liu ; Hang Hu ; Hongrui Li ; Prof. Liyi Shi and Prof. Dengsong Zhang
• 刊名：ChemCatChem
• 出版年：2016
• 出版时间：July 6, 2016
• 年：2016
• 卷：8
• 期：13
• 页码：2267-2278
• 全文大小：2590K
• ISSN：1867-3899

文摘

Antimony-doped CeO₂–WO₃/TiO₂ catalysts were prepared by a conventional ultrasonic-assisted impregnation method and employed for selective catalytic reduction of NO_x with NH₃ at low temperature. Both experimental work and theoretical studies were employed to elucidate the effect of the antimony on promoting the CeO₂–WO₃/TiO₂ catalyst. The catalytic activity of CeO₂–WO₃/TiO₂ was largely improved after the addition of antimony oxide. It was found that antimony doping reduced the crystal size and strengthened the synergistic effect between the metal cations, which resulted in a favorable catalyst surface status with abundant active surface oxygen, Brønsted acid sites, and effective electron transfer. Both in situ diffuse reflectance infrared Fourier transform analysis and DFT calculation results revealed that the ammonia and NO_x desorption behavior over the catalyst surface were considerably different. For the ammonia species, rather large amounts of the active NH₄⁺ and NH₃ species anchored on the surface of the Sb-doped CeO₂–WO₃/TiO₂. In view of the NO_x species, the amount of nonactive bidentate nitrate species was largely reduced and the amount of active gaseous NO₂ species was clearly enhanced, which lowered the activation energy of the catalytic process and gave rise to the elevated low-temperature NH₃ selective catalytic reduction activity. All these preferable properties resulted in the elevated de-NO_x activity of the Sb-doped CeO₂–WO₃/TiO₂ catalyst.