A spinel solid solution expressed by a composition formula of Cu x Ni 1? x Al 1.8 Cr 0.2 O 4 (0 ≤ x ≤ 0.2) was studied focusing on the role of Cu species in the catalytic activity toward NO reduction under a simulated three-way catalysis condition. X-ray Rietveld analysis revealed that Cu and Cr prefer to occupy the tetrahedral site and the octahedral site, respectively, whereas Ni and Al are distributed across both sites. Although NiAl 1.8 Cr 0.2 O 4 ( x = 0) showed negligible catalytic activity for NO reduction, the partial replacement of Ni by Cu significantly enhanced the activity, achieving the highest activity at x = 0.05 not only for NO reduction but also for CO and C 3 H 6 oxidation. Based on the infrared spectra and pulsed reaction experiments, it was concluded that the monovalent Cu site in the tetrahedral site plays a key role in CO chemisorption, oxygen vacancy formation, and subsequent NO reduction via the Mars–van Krevelen mechanism.
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机译:由Cu x Ni 1的组合式表达的尖晶石固溶溶液?研究了X Al 1.8 Cr 0.2 O 4(0≤x≤0.2),专注于Cu物种在催化活性中的作用,在模拟的三元催化条件下没有减少。 X射线RIETVELD分析显示CU和CR分别占据四面体部位和八面体部位,而Ni和Al分布在两个位点。虽然Nial 1.8 Cr 0.2 O 4(x = 0)显示出可忽略不计的催化活性,但Cu通过Cu的部分替代液显着增强了活性,不仅在没有减少的情况下实现x = 0.05的最高活动,而且C 3 H 6氧化。基于红外光谱和脉冲反应实验,得出结论是,四面体部位中的一价Cu位点在Co Chem吸附,氧空位形成和随后通过MARS-VAN KREVELEN机制进行了关键作用。
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