Low-temperature SCR activity and SO₂ deactivation mechanism of Ce-modified V₂O₅-WO₃/TiO₂ catalyst

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• 作者：Ziran Ma^a ; ^b ; Xiaodong Wu^a ; ^{wuxiaodong@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Ya Feng^a ; Zhichun Si^c ; Duan Weng^a ; ^c ; ^{duanweng@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Lei Shi^d
• 关键词：V2O5-WO3/TiO2 ; Ceria ; NH3-SCR ; Low-temperature activity ; SO2 poisoning
• 刊名：Progress in Natural Science
• 出版年：2015
• 出版时间：August 2015
• 年：2015
• 卷：25
• 期：4
• 页码：342-352
• 全文大小：2626 K

文摘

The promotion effect of ceria modification on the low-temperature activity of V₂O₅-WO₃/TiO₂ catalyst was evaluated for the selective catalytic reduction of NO with NH₃ (NH₃-SCR). The catalytic activity of 1 wt% V₂O₅-WO₃/TiO₂ was significantly enhanced by the addition of 8 wt% ceria, which exhibited a NO_x conversion above 80% in a broad temperature range 190–450 °C. This performance was comparable with 3 wt%V₂O₅-WO₃/TiO₂, indicating that the addition of ceria contributed to reducing the usage of toxic vanadia in developing low-temperature SCR catalysts. Moreover, V1CeWTi exhibited approximately 10% decrease in NO_x conversion in the presence of 60 ppm SO₂. The characterization results indicated that active components of V, W and Ce were well dispersed on TiO₂ support. The synergetic interaction between Ce and V species by forming V–O–Ce bridges enhanced the reducibility of VCeWTi catalyst and thus improved the low-temperature activity. The sulfur poisoning mechanism was also presented on a basis of the designed TPDC (temperature-programmed decomposition) and TPSR (temperature-programmed surface reaction) experiments. The deposition of (NH₄)₂SO₄ on V1CeWTi catalyst was much smaller compared with that on V1Ti. On the other hand, the oxidation of SO₂ to SO₃ was significantly promoted on the CeO₂-modified catalyst, accompanied by the formation of cerium sulfates. Therefore, the deactivation of this catalyst was mainly attributed to the vanishing of the V–Ce interaction and the sulfation of active ceria.