Insight into Deactivation of Commercial SCR Catalyst by Arsenic: An Experiment and DFT Study

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• 作者：Yue Peng ; Junhua Li ; Wenzhe Si ; Jinming Luo ; Qizhou Dai ; Xubiao Luo ; Xin Liu ; Jiming Hao
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：December 2, 2014
• 年：2014
• 卷：48
• 期：23
• 页码：13895-13900
• 全文大小：357K
• ISSN：1520-5851

文摘

Fresh and arsenic-poisoned V₂O₅鈥揥O₃/TiO₂ catalysts are investigated by experiments and DFT calculations for SCR activity and the deactivation mechanism. Poisoned catalyst (1.40% of arsenic) presents lower NO conversion and more N₂O formation than fresh. Stream (5%) could further decrease the activity of poisoned catalyst above 350 掳C. The deactivation is not attributed to the loss of surface area or phase transformation of TiO₂ at a certain arsenic content, but due to the coverage of the V₂O₅ cluster and the decrease in the surface acidity: the number of Lewis acid sites and the stability of Br酶nsted acid sites. Large amounts of surface hydroxyl induced by H₂O molecules provide more unreactive As鈥揙H groups and give rise to a further decrease in the SCR activity. N₂O is mainly from NH₃ unselective oxidation at high temperatures since the reducibility of catalysts and the number of surface-active oxygens are improved by As₂O₅. Finally, the reaction pathway seems unchanged after poisoning: NH₃ adsorbed on both Lewis and Br酶nsted acid sites is reactive.