The Pd distribution and the CeO₂–Al₂O₃ combination are among the decisive factors for the performance of commercial three-way catalysts. Generally, the sufficient doping of Pd into ceria-based oxides and the intimate interaction between CeO₂ and Al₂O₃ could both benefit the three-way catalytic reactions. However, in the present work, the moderate doping of Pd into CeO₂ and less intimate CeO₂–Al₂O₃ interaction were found to be responsible for the much higher catalytic activity (the decrease in T₅₀ was 52, 119, or 55 °C for C₃H₆, CO, or NO) in PdCe/Al₂O₃-CP than PdCe/Al₂O₃-Imp, for which the Pd and Ce species were co-loaded onto Al₂O₃ through the co-precipitation or impregnation method, respectively. It was intriguing to find that the co-precipitated PdCeO_x in PdCe/Al₂O₃-CP showed less sufficient doping of Pd into CeO₂ than the co-impregnated PdCeO_x in PdCe/Al₂O₃-Imp; as a result, both a higher fraction of highly active metallic Pd and a higher Pd dispersion were realized in PdCe/Al₂O₃-CP. Moreover, due to the less intimate CeO₂–Al₂O₃ interaction, specifically the less severe penetration of the Pd and Ce species into Al₂O₃, PdCe/Al₂O₃-CP showed higher Pd dispersion, specific surface area, pore volume and size than PdCe/Al₂O₃-Imp. The presence of more abundant reactive Pd⁰, and the higher accessibility of the active Pd and CeO₂ sites, together with improved redox properties and enriched oxygen vacancies contributed much to the enhanced three-way catalytic activity of PdCe/Al₂O₃-CP. Additionally, simultaneously optimizing the Pd distribution and the CeO₂–Al₂O₃ combination in a single step, as reported in this work, is also highly desirable in industry.

中文翻译：

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调节 Pd、CeO2 和 Al2O3 之间的相互作用以改进三效催化剂

Pd 分布和 CeO ₂ –Al ₂ O ₃组合是商业三效催化剂性能的决定性因素。通常，Pd 充分掺杂到二氧化铈基氧化物中以及 CeO ₂和 Al ₂ O ₃之间的密切相互作用都可以有利于三元催化反应。然而，在目前的工作中，发现 Pd 在 CeO ₂中的适度掺杂和不太密切的 CeO ₂ -Al ₂ O ₃相互作用是造成更高催化活性的原因（T ₅₀的降低为 52、119 或 55 C ₃的°C_{PdCe/Al 2} O ₃ -CP 中的H ₆、CO 或 NO)比 PdCe/Al ₂ O ₃ -Imp 中的 Pd 和 Ce 物种通过共沉淀或浸渍共同负载到 Al ₂ O ₃上方法，分别。有趣的是，PdCe/Al 2 O 3 -CP 中的共沉淀 PdCeO _x与_{PdCe /} Al 2 _O 3 _-Imp中的共浸渍 PdCeO _x相比，Pd 向 CeO ₂中的掺杂不足；结果，在 PdCe/Al _{2中实现了更高比例的高活性金属 Pd 和更高的 Pd 分散度}O ₃ -CP。此外，由于 CeO ₂ –Al ₂ O ₃相互作用不那么密切，特别是 Pd 和 Ce 物质对 Al ₂ O ₃的渗透不那么严重，PdCe/Al ₂ O ₃ -CP 显示出更高的 Pd 分散度、比表面积，孔体积和尺寸比PdCe/Al ₂ O ₃ -Imp。更丰富的反应性 Pd ⁰的存在，以及活性 Pd 和 CeO _{2位点的更高可及性，以及改善的氧化还原性能和富集的氧空位对 PdCe/Al 2} O增强的三元催化活性做出了很大贡献₃ -CP。此外，如本工作所述，同时优化 Pd 分布和 CeO ₂ –Al ₂ O ₃组合在工业上也是非常理想的。