Effect of H2O and SO2 on the Selective Catalytic Reduction of NO with NH3 Over Ce/TiO2 Catalyst: Mechanism and Kinetic Study

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• 作者：Xin Xiao ; Shangchao Xiong ; Yijie Shi ; Wenpo Shan ; Shijian Yang
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：January 21, 2016
• 年：2016
• 卷：120
• 期：2
• 页码：1066-1076
• 全文大小：766K
• ISSN：1932-7455

文摘

Ce-based catalysts now were regarded as a promising alternative to substitute V₂O₅/WO₃–TiO₂ catalyst for the abatement of NO_x in the flue gas. However, H₂O and SO₂ showed a notable effect on NO reduction over Ce based catalysts and the mechanism was not very clear. In this work, the mechanism of H₂O and SO₂ effect on NO reduction over Ce/TiO₂ was studied using the steady state kinetic study and the reaction kinetic parameters were compared. Although H₂O and SO₂ both showed a promotion on NO reduction over Ce/TiO₂ at higher temperatures, their mechanisms were quite different. The effect of SO₂ on NO reduction over Ce/TiO₂ was mainly attributed to the sulfation. The selective catalytic reduction (SCR) reaction over Ce/TiO₂ at higher temperatures was promoted after the sulfation due to the promotion of NH₃ adsorption. Meanwhile, the catalytic oxidation of NH₃ to NO (i.e., the C–O reaction) over Ce/TiO₂ at higher temperatures was suppressed after the sulfation. Therefore, the promotion of NO reduction over Ce/TiO₂ at higher temperatures due to the introduction of SO₂ was related to not only the inhibition of the C–O reaction but also the promotion of the SCR reaction. However, the SCR reaction over Ce/TiO₂ at higher temperatures was restrained in the presence of H₂O due to the inhibition of NH₃ adsorption and the decrease of oxidation ability. Therefore, the promotion of NO reduction over Ce/TiO₂ at higher temperatures due to the presence of H₂O was mainly attributed to the inhibition of the C–O reaction.