Selective oxidation of benzyl alcohol to benzaldehyde in the vapor phase has drawn growing interest recently. In this work, MnO_x–CeO₂ mixed oxide compositions have been prepared by a coprecipitation method and tested for their oxidation activities of benzyl alcohol to benzaldehyde in the vapor phase. Detailed structural analyses have indicated that MnO_x–CeO₂ catalysts contain two phases, namely, α-MnO₂ and fluorite CeO₂ phases. The benzyl alcohol oxidation activity of pure MnO₂ is more than 7 times higher compared to that of CeO₂, indicating a much higher intrinsic oxidation ability of the MnO₂ phase. Further, enhancement of the benzyl alcohol oxidation rate over MnO₂ in 10%MnO_x–CeO₂ catalyst by 13 times is observed in relation to pure MnO₂. The role of CeO₂ in the MnO_x–CeO₂ catalyst has also been investigated, which indicates that the oxidation activity is almost independent of CeO₂. However, stronger adsorption of benzyl alcohol over the MnO_x–CeO₂ catalysts compared to that of MnO₂ points to the role of CeO₂ in adsorption. Thus, both the CeO₂ and the MnO₂ components have different roles in the catalytic process—adsorption of benzyl alcohol on the CeO₂ surface and its oxidation on MnO₂ at the interface. The cooperation between the two sites toward oxidation could happen due to jumping of adsorbed benzyl alcohol from the surface of the CeO₂ phase to the closest Mn⁴⁺ site in the MnO₂ phase at the contact surface with MnO₂ by thermal motion.

中文翻译：

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在气相中使用空气中的 O2 在双相 MnOx-CeO2 催化剂中实现 MnO2 高苄醇氧化活性的双位点合作

苯甲醇在气相中选择性氧化为苯甲醛最近引起了越来越多的兴趣。在这项工作中，MnO _x -CeO ₂混合氧化物组合物已通过共沉淀法制备，并测试了它们在气相中将苯甲醇氧化成苯甲醛的活性。详细的结构分析表明，MnO _x -CeO ₂催化剂包含两相，即α-MnO ₂和萤石CeO ₂相。纯MnO ₂的苯甲醇氧化活性比CeO ₂高7倍以上，表明MnO ₂具有更高的内在氧化能力阶段。此外，观察到与纯 MnO _{2 相比，}在 10% MnO _x -CeO ₂催化剂中苯甲醇氧化速率比 MnO ₂提高了13 倍。CeO ₂在MnO _x -CeO ₂催化剂中的作用也已被研究，这表明氧化活性几乎与CeO ₂无关。然而，苄醇在所述的MnO吸附更强_X -CeO _2个催化剂相比的MnO ₂点的CeO的作用₂中吸附。因此，CeO ₂和 MnO ₂组分在催化过程中具有不同的作用——苯甲醇在 CeO ₂表面的吸附和在界面处在MnO ₂上的氧化。由于热运动，吸附的苯甲醇从CeO ₂相的表面跃迁到MnO ₂相中与MnO ₂接触表面最近的Mn ⁴⁺位点，从而可能发生两个位点之间的氧化合作。