An exceptional reactivity between NO₂ and probably HNCO was demonstrated over an oxide-based catalyst during NO₂-SCR experiments with urea as the injected reductant. This was observed when only NO₂ was used as NO_x, but not with gaseous NH₃ as the reductant. Roughly, one third of the injected reductant reacted with NO₂ and two thirds appeared to be oxidized by O₂, the main product being N₂. 28 reactions may be involved in the observed results. A cooperative effect of NO₂ with O₂ was demonstrated and the observed global stoichiometry did not depend on the NO₂ concentration for (NO₂/eq. NH₃)_{inlet ratio} ≤1.

中文翻译：

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在氧化物基催化剂上通过尿素法研究HNCO /脲与NO _x SCR中NO ₂的显着反应性

在使用尿素作为注入还原剂的NO ₂ -SCR实验中，基于氧化物的催化剂在NO ₂和可能的HNCO之间表现出出色的反应性。当仅使用NO ₂作为NO _x而不使用气态NH ₃作为还原剂时，可以观察到这一点。大致而言，注入的还原剂中有三分之一与NO ₂反应，三分之二似乎被O ₂氧化，主要产物为N ₂。观察到的结果可能涉及28个反应。证明了NO ₂与O _2的协同作用，并且观察到的整体化学计量不依赖于NO ₂（NO ₂ / eq。NH ₃）_入口比≤1时的浓度。