Abstract In heterogeneous catalysis, developing robust catalysts and preventing the metal leaching during the reactions still remain challenging. Herein, a porous honeycomb-like nanostructure with bimetallic Ce–Cr oxide supported on N-doped carbon was prepared via a facile in-situ pyrolysis method. The prepared catalyst was highly active, selective, and stable in the transformation of cyclohexane to KA oil with H2O2 as the oxidant. The N-doped carbon served as an excellent support for the metal nanoparticles and greatly promoted their dispersion, and displayed a comparable or superior catalytic activity compared to the other traditional supports. It was found that the pyridinic N and pyrrolic N species of N-doped carbon were the main active sites for the metal immobilization, and the strong electronic interaction between N-doped carbon and Ce–Cr oxide was formed. The results revealed that the increased low-valence metal species might be responsible for the improved catalytic activity, and EPR analysis indicated that the hydroxyl radicals played a crucial role during the oxidation process. Besides, the catalyst can be easily separated and still remained stable after recycling seven times, making it a promising candidate for the catalytic oxidation of cyclohexane to KA oil under mild conditions.

中文翻译：

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蜂窝状多孔Ce-Cr氧化物/N掺杂碳纳米结构：实现环己烷选择性氧化成KA油的高催化性能

摘要 在多相催化中，开发稳定的催化剂和防止反应过程中的金属浸出仍然具有挑战性。在此，通过简便的原位热解方法制备了一种多孔蜂窝状纳米结构，其在掺氮碳上负载了双金属 Ce-Cr 氧化物。所制备的催化剂在以H2O2为氧化剂的环己烷转化KA油中具有高活性、选择性和稳定性。N掺杂的碳作为金属纳米颗粒的极好载体，极大地促进了它们的分散，与其他传统载体相比表现出相当或优越的催化活性。发现N掺杂碳的吡啶N和吡咯N物种是金属固定的主要活性位点，并且在 N 掺杂的碳和 Ce-Cr 氧化物之间形成了强电子相互作用。结果表明，增加的低价金属物种可能是提高催化活性的原因，EPR 分析表明羟基自由基在氧化过程中起着至关重要的作用。此外，该催化剂易于分离且循环使用7次后仍保持稳定，使其成为在温和条件下催化氧化环己烷为KA油的有希望的候选者。