Four types of core-shell materials with magnetic Fe₃O₄ microparticles as the core were prepared through different approaches using dopamine, glucose, tetrabutyl orthotitanate (TBOT), and tetraethyl orthosilicate (TEOS) as the shell precursor, respectively. CeO₂ nanoparticles (NPs) was successfully immobilized onto these supports to fabricate efficient catalysts for the tandem catalytic synthesis of imines from benzyl alcohols and anilines at low temperature under air atmosphere. The as-prepared catalysts were detailedly characterized by TEM, EDX, XRD, FT-IR, XPS VSM, ICP, and CO₂-TPD. Interestingly, these prepared catalysts showed higher catalytic activity than reported CeO₂ catalysts. Most attractively, the catalyst with a shell of nitrogen-doped-carbon derived from dopamine exhibited the best catalytic property, and outstanding stability and recyclability in the cycle experiment. According to the XPS and CO₂-TPD characterization, the enhanced performance of Fe₃O₄@[email protected]₂ composites can be attributed to two reasons as follows: (1) the immobilization of CeO₂ improved its alkalinity at low reaction temperature, and alkalinity is beneficial to promote the oxidation of alcohols to benzaldehyde, which is the rate-determining step for this tandem reaction; (2) the doped nitrogen generated Lewis basic site could satisfactorily stabilize Ce³⁺/Ce⁴⁺ pair of CeO₂, which determined the catalytic activity and stability of CeO₂ based catalysts for this tandem reaction. Moreover, the prepared catalysts could be facilely recovered from the reaction mixture with an external magnet. This work may provide a useful strategy for constructing CeO₂ based catalysts for green and sustainable catalysis.

分别采用多巴胺，葡萄糖，原钛酸四丁酯（TBOT）和原硅酸四乙酯（TEOS）作为壳前体，通过不同的方法制备了四种以磁性Fe ₃ O ₄微粒为核的核-壳材料。将CeO ₂纳米颗粒（NPs）成功固定在这些载体上，以制备有效的催化剂，用于在低温，大气气氛下从苄醇和苯胺串联催化合成亚胺。所制备的催化剂通过TEM，EDX，XRD，FT-IR，XPS VSM，ICP和CO ₂ -TPD进行了详细表征。有趣的是，这些制备的催化剂显示出比报道的CeO ₂更高的催化活性。催化剂。最吸引人的是，具有多巴胺衍生的氮掺杂碳壳的催化剂在循环实验中表现出最佳的催化性能，出色的稳定性和可回收性。根据XPS和CO ₂ -TPD表征，Fe ₃ O ₄ @ [email protected] ₂复合材料性能的提高可归因于以下两个原因：（1）CeO ₂的固定化提高了其在低反应温度下的碱度。 ，碱度有利于促进醇类氧化为苯甲醛，这是该串联反应的决定速率的步骤；（2）掺杂氮产生的路易斯碱性位点可以令人满意地稳定Ce ³⁺ / Ce⁴⁺对CeO ₂，确定了此串联反应的CeO ₂基催化剂的催化活性和稳定性。而且，可以用外部磁体容易地从反应混合物中回收制备的催化剂。这项工作可能为构建基于CeO ₂的绿色和可持续催化催化剂提供有用的策略。