Selective catalytic reduction (SCR) of NO_x with NH₃ by supported vanadium oxide catalysts is an important technology for reducing acidic NO_x emissions from stationary sources and mobile diesel vehicles. However, rational design of improved catalysts is still hampered by a lack of consensus about reaction pathways and kinetics of this critical technology. The SCR fundamentals were resolved by applying multiple time-resolved in situ spectroscopies (ultraviolet–visible light (UV-vis), Raman and temperature-programmed surface reaction (TPSR)) and isotopically labeled molecules (¹⁸O₂, H₂¹⁸O, ¹⁵N¹⁸O, ND₃). This series of experiments directly revealed that the SCR reaction occurs at surface V⁵⁺O₄ sites that are maintained in the oxidized state by O₂ and the rate-determining step involves the reduction of V⁵⁺O₄ sites by NO and NH₃, specifically the breaking of N–H bonds during the course of formation or decomposition of the NO–NH₃ intermediate.

中文翻译：

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NH _3对发电厂酸性NO _x排放进行选择性催化还原（SCR）的反应途径和动力学

NO选择性催化还原（SCR）_X与NH ₃通过支持钒氧化物催化剂是用于减少酸性NO的重要技术_X从固定源和移动柴油车辆排放。然而，由于对该关键技术的反应途径和动力学缺乏共识，仍然阻碍了改进催化剂的合理设计。通过应用多种时间分辨的原位光谱仪（紫外可见光（UV-vis），拉曼光谱和温度程序化表面反应（TPSR））和同位素标记的分子（¹⁸ O ₂，H ₂ ¹⁸ O，¹⁵ N ¹⁸ O，ND ₃）。这一系列实验直接表明SCR反应发生在表面V ⁵⁺ O ₄位点，该位点被O ₂保持在氧化状态，并且速率确定步骤涉及NO和NH ₃还原V ⁵⁺ O ₄位点。，特别是在NO-NH ₃中间体的形成或分解过程中，NH键的断裂。