The origin of N₂O formation in the selective catalytic reduction of NO_x by NH₃ in O₂ rich atmosphere on Cu-faujasite catalysts

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• 作者：Delahay ; Gerard ; Coq ; Bernard ; Kieger ; Stephane ; Neveu ; Bernard
• 关键词：Selective catalytic reduction ; DeNO_x ; Cu-faujasite ; NH₃
• 刊名：Catalysis Today
• 出版年：1999
• 期刊代码：13_09205861
• 类别：ce
• 出版时间：December 17, 1999
• 卷：54
• 期：4
• 页码：431-438
• 文件大小：197 K

摘要

The selective catalytic reduction (SCR) of NO_x (NO + NO₂) by NH₃ in O₂ rich atmosphere has been studied on Cu-FAU catalysts with Cu nominal exchange degree from 25 to 195%. NO₂ promotes the NO conversion at NO/NO₂ = 1 and low Cu content. This is in agreement with next-nearest-neighbor (NNN) Cu ions as the most active sites and with N_xO_y adsorbed species formed between NO and NO₂ as a key intermediate. Special attention was paid to the origin of N₂O formation. CuO aggregates form 40–50%of N₂O at ca. 550 K and become inactive for the SCR above 650 K. NNN Cu ions located within the sodalite cages are active for N₂O formation above 600 K. This formation is greatly enhanced when NO₂ is present in the feed, and originated from the interaction between NO (or NO₂) and NH₃. The introduction of selected co-cations, e.g. Ba, reduces very significantly this N₂O formation.