As the state-of-the-art catalyst for the selective catalytic reduction (SCR) of NOx, Cu-CHA has been extensively investigated in both its practical and fundamental aspects. Among the latter, how Z₂Cu²⁺, an active site for SCR, participates in low-temperature (LT) SCR reactions remains debated. Here, we propose a scheme involving the hydrolysis of Z₂Cu²⁺ to ZCu²⁺(OH)⁻, a thermodynamically and kinetically favorable process under LT-SCR conditions, based on multiple pieces of evidence from a probe reaction (transient CO oxidation), transient Cu²⁺ reduction kinetic runs, in situ FTIR spectroscopy, and first-principles calculations. Such an integrated investigation reveals unambiguously that the hydrolysis of Z₂Cu²⁺ to ZCu²⁺(OH)⁻ occurs facilely in the presence of NH₃, which may thus reconcile the identical quadratic kinetics of Z₂Cu²⁺/ZCu²⁺(OH)⁻ reduction with the inactivity of Z₂Cu²⁺ in the formation of Cu²⁺ pairs. Accordingly, we highlight that NH₃-assisted hydrolysis plays a critical role in LT-SCR and should be taken into account especially when discussing SCR reaction details over Z₂Cu²⁺.

中文翻译：

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解开 Z2Cu2+ 水解为 ZCu2+(OH)− 及其对 Cu-CHA 催化剂上 NO 的低温选择性催化还原的后果

作为国家的最先进的催化剂对NO的选择性催化还原（SCR）X，的Cu-CHA已经被广泛地在其两个实际和基本方面的影响。在后者中，SCR 的活性位点Z ₂ Cu ²⁺如何参与低温 (LT) SCR 反应仍有争议。这里，我们提出，涉及Z的水解的方案₂的Cu ²⁺到ZCu ²⁺（OH）^-，LT-SCR条件下热力学和动力学上有利的方法，基于来自探针反应的多条证据（瞬时CO氧化), 瞬态 Cu ²⁺还原动力学运行、原位 FTIR 光谱和第一性原理计算。这种综合研究清楚地表明，Z ₂ Cu ²⁺水解为ZCu ²⁺ (OH) ^-在NH ₃存在下很容易发生，因此可以调和Z ₂ Cu ²⁺ /ZCu ²⁺的相同二次动力学(OH) ^-还原，Z ₂ Cu ²⁺在形成 Cu ²⁺对时没有活性。因此，我们强调 NH ₃辅助水解在 LT-SCR 中起着关键作用，尤其是在讨论 Z ₂ Cu ^{2+ 上的}SCR 反应细节时应予以考虑。