Abstract A series of BaCeO3 modified with different rare earth elements (La, Y, Pr) were synthesized by co-precipitation and calcination and the effect of rare earth elements for catalytic ammonia synthesis under mild conditions was studied. The ammonia synthesis performance tests show that 2.5% Ru/BaCe0.9La0.1O3–δ catalyst (All the percentages of Ru in this article are in the mass fraction) exhibits the highest ammonia synthesis rate (34 mmol/(g·h)) at 3 MPa, 450 °C, and no sign of deactivation after 100 h of reaction. H2-TPR and XPS analyses indicate that the introduction of La increases the amount of oxygen vacancies of the catalyst, which is beneficial to increasing the electron density of Ru surface. HRTEM analysis shows that the Ru particle size is reduced greatly after La is introduced, which facilitates the catalyst generating more B5-type sites (active sites of Ru species for N N dissociation). CO2-TPD analysis indicates that BaCe0.9La0.1O3–δ has stronger basicity, which promotes electrons transfer from support to Ru. This work provides an effective method for design and synthesis of Ru-based multi-element composite perovskite oxide catalysts.

中文翻译：

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稀土元素（La、Y、Pr）在多元素复合钙钛矿氧化物载体合成氨中的影响

摘要 通过共沉淀和煅烧合成了一系列不同稀土元素(La、Y、Pr)改性的BaCeO3，研究了稀土元素在温和条件下催化合成氨的作用。氨合成性能测试表明，2.5% Ru/BaCe0.9La0.1O3-δ催化剂（本文中Ru的百分比均以质量分数计）表现出最高的氨合成速率（34 mmol/(g·h)）在 3 MPa、450 °C 下，反应 100 小时后没有失活迹象。H2-TPR和XPS分析表明，La的引入增加了催化剂氧空位的数量，有利于提高Ru表面的电子密度。HRTEM分析表明，引入La后Ru粒径大大减小，这有助于催化剂产生更多的 B5 型位点（用于 NN 解离的 Ru 物种的活性位点）。CO2-TPD 分析表明 BaCe0.9La0.1O3-δ 具有更强的碱性，促进电子从载体转移到 Ru。该工作为Ru基多元素复合钙钛矿氧化物催化剂的设计和合成提供了一种有效的方法。