This study demonstrates that an isolated Cu²⁺ species formed by interacting with tetrahedral Al species on γ-Al₂O₃ shows a high catalytic activity for NO reduction with C₃H₆ and CO under high oxygen concentrations (lean conditions), and that an infinitesimal amount of Rh (0.01 wt%, 100 ppm) loaded on 0.5 wt% Cu/Al₂O₃ is a more effective catalyst for the reactions, under a wide range of oxygen concentrations, than 0.5 wt% Pd/Al₂O₃ or 1.0 wt% Rh/Al₂O₃. Although 0.5 wt% Cu/Al₂O₃ itself is effective for the reaction at lean conditions, it shows low catalytic activity under stoichiometric and low oxygen concentrations (rich conditions). On the other hand, the loading of 0.01 wt% Rh on Cu/Al₂O₃ dramatically improves catalytic activities under stoichiometric and rich conditions, with maintaining the high NO reduction activity of Cu/Al₂O₃ itself under lean conditions. Therefore, a Rh species in the Rh/Cu/Al₂O₃ system must play a role as an active site under stoichiometric and rich conditions. Under lean conditions using Rh/Cu/Al₂O₃, an isolated Cu²⁺ species on γ-Al₂O₃ mainly contributes to the NO reduction properties of the catalyst. No such advantage was observed for Pd/Cu/Al₂O₃; that is, the catalytic activity of Cu/Al₂O₃ under lean conditions is diminished by Pd loading. Hence, we reveal that the roles of the Rh and Cu species in the Rh-loaded Cu/Al₂O₃ catalyst are effectively shared according to oxygen concentration in selective reduction of NO, when loaded with an infinitesimal amount of Rh. These observations provide novel guidelines for the development of catalysts that more beneficially use precious metal resources.

这项研究表明，一种分离的Cu ²⁺物种通过与四面体Al物质相互作用的γ-Al形成₂ ö ₃示出了用于还原NO用C高的催化活性₃ ħ ₆在高氧浓度和CO（贫燃条件），并且负载在0.5 wt％Cu / Al ₂ O ₃上的微量Rh（0.01 wt％，100 ppm）比0.5 wt％Pd / Al ₂ O是在宽范围的氧气浓度下更有效的反应催化剂₃或1.0重量％的Rh / Al ₂ O ₃。尽管0.5wt％的Cu / Al ₂ O ₃本身对贫油条件下的反应有效，它在化学计量比和低氧浓度（富氧条件下）下显示出低催化活性。另一方面，Cu / Al ₂ O ₃上0.01wt％Rh的负载在化学计量和浓条件下显着改善了催化活性，而在稀条件下保持了Cu / Al ₂ O ₃本身的高NO还原活性。因此，Rh / Cu / Al ₂ O ₃系统中的Rh物种必须在化学计量和浓条件下起活性位点的作用。下，使用的Rh /铜/铝贫燃条件₂ ö ₃，一种分离的Cu ²⁺对物种的γ-Al ₂O ₃主要有助于催化剂的NO还原性能。对于Pd / Cu / Al ₂ O _3则没有观察到这种优势。即，贫钯条件下的Cu / Al ₂ O ₃的催化活性因Pd负载而降低。因此，我们揭示了当负载无限量的Rh时，根据氧浓度有效地共享了Rh和Cu物种在Rh负载的Cu / Al ₂ O ₃催化剂中的作用，从而选择性地还原NO。这些发现为开发更有益地使用贵金属资源的催化剂提供了新的指导原则。