Mechanism of N2O Formation during the Low-Temperature Selective Catalytic Reduction of NO with NH3 over Mn鈥揊e Spinel

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• 作者：Shijian Yang ; Shangchao Xiong ; Yong Liao ; Xin Xiao ; Feihong Qi ; Yue Peng ; Yuwu Fu ; Wenpo Shan ; Junhua Li
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：September 2, 2014
• 年：2014
• 卷：48
• 期：17
• 页码：10354-10362
• 全文大小：526K
• ISSN：1520-5851

文摘

The mechanism of N₂O formation during the low-temperature selective catalytic reduction reaction (SCR) over Mn鈥揊e spinel was studied. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and transient reaction studies demonstrated that the Eley鈥揜ideal mechanism (i.e., the reaction of adsorbed NH₃ species with gaseous NO) and the Langmuir鈥揌inshelwood mechanism (i.e., the reaction of adsorbed NH₃ species with adsorbed NO_x species) both contributed to N₂O formation. However, N₂O selectivity of NO reduction over Mn鈥揊e spinel through the Langmuir鈥揌inshelwood mechanism was much less than that through the Eley鈥揜ideal mechanism. The ratio of NO reduction over Mn鈥揊e spinel through the Langmuir鈥揌inshelwood mechanism remarkably increased; therefore, N₂O selectivity of NO reduction over Mn鈥揊e spinel decreased with the decrease of the gas hourly space velocity (GHSV). As the gaseous NH₃ concentration increased, N₂O selectivity of NO reduction over Mn鈥揊e spinel increased because of the promotion of NO reduction through the Eley鈥揜ideal mechanism. Meanwhile, N₂O selectivity of NO reduction over Mn鈥揊e spinel decreased with the increase of the gaseous NO concentration because the formation of NH on Mn鈥揊e spinel was restrained. Therefore, N₂O selectivity of NO reduction over Mn鈥揊e spinel was related to the GHSV and concentrations of reactants.