Selective catalytic reduction of NO by NH₃ over supported vanadium oxide catalysts has been studied for decades, but the studies mostly concentrated on the dominant N₂ product with much less attention paid to the formation of the undesired N₂O product. In the present study, fundamental aspects of the N₂O formation reaction were elucidated by a series of temperature-programmed surface reaction studies with isotopic labelled reactants. The surface vanadium oxide species on the TiO₂ support are active sites for the N₂O formation reaction, while tungsten species mainly function as promoters. Oxygen from NO, gaseous O₂ and catalyst oxygen all function as oxygen sources for formation of N₂O (∼50%, ∼30% and ∼20%, respectively). The rate-determining-step for N₂O formation involves breaking of the ammonia NH bond. These new molecular level insights have the potential to guide the rational design of improved SCR catalysts for diesel engines with reduced N₂O produced.

数十年来，已经研究了在负载的钒氧化物催化剂上用NH ₃选择性催化还原NO的研究，但研究大多集中在占主导地位的N ₂产物上，而对形成不希望的N ₂ O产物的关注则少得多。在本研究中，通过一系列用同位素标记的反应物进行的程序升温表面反应研究，阐明了N ₂ O形成反应的基本方面。TiO ₂载体上的表面钒氧化物是N ₂ O形成反应的活性位，而钨主要起促进剂的作用。NO，气态O _2中的氧气催化剂氧和催化剂氧都是形成N ₂ O的氧源（分别为〜50％，〜30％和〜20％）。N ₂ O形成的速率确定步骤涉及到氨N H键的断裂。这些新的分子水平的见识有可能指导合理设计改进的SCR催化剂，以减少N ₂ O的产生。