Composite oxide catalysts with Co/Mn/Ce molar ratio of 3:x:2(x = 1, 3, 5 and 7) have been successfully prepared by co-precipitation method. The crystal phase structure, elemental valence, oxygen vacancy and reductivity of the catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), H 2 temperature program reduction(H 2 -TPR) and in situ DRIFTs. The results demonstrated that when x = 1, the Co–Mn–Ce catalyst had the smallest grain size and oxygen vacancy. A flow reactor experimental system was used to analyze the effect of Mn content on light-off temperature (T 10 ) and complete oxidation temperature (T 90 ) of propane oxidation over Co–Mn–Ce catalysts under anhydrous condition and 5% vol of water vapor. The results showed that when x = 1, the catalyst exhibits the highest activity (T 10 = 200 °C, T 90 = 307 °C) and water tolerance among the four catalysts. It indicated that when x = 1, the incorporation of Mn content can improve the ability of Co–Mn–Ce catalysts for propane oxidation. Based on the Langmuir–Hinshelwood theory, the surface chemical reaction pathway of propane oxidation was constructed and it revealed that the major active sites of Co–Mn–Ce catalysts mainly depend on surface oxygen vacancy and the surface active species (Mn 4+ ,O ads ). Graphic Abstract

中文翻译：

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Mn 含量对 Co-Mn-Ce 催化剂丙烷氧化催化活性的影响：晶格缺陷和表面活性物质的重要性

采用共沉淀法成功制备了Co/Mn/Ce摩尔比为3:x:2(x=1、3、5和7)的复合氧化物催化剂。通过X射线衍射(XRD)、X射线光电子能谱(XPS)、电子顺磁共振(EPR)、H 2 升温程序还原(H 2 -TPR）和原位漂移。结果表明，当 x = 1 时，Co-Mn-Ce 催化剂的晶粒尺寸和氧空位最小。流动反应器实验系统用于分析Mn含量对Co-Mn-Ce催化剂在无水和5%体积水条件下丙烷氧化的起燃温度（T 10 ）和完全氧化温度（T 90 ）的影响汽。结果表明，当 x = 1 时，该催化剂在四种催化剂中表现出最高的活性 (T 10 = 200 °C, T 90 = 307 °C) 和耐水性。这表明当 x = 1 时，Mn 含量的加入可以提高 Co-Mn-Ce 催化剂的丙烷氧化能力。基于Langmuir-Hinshelwood理论，构建了丙烷氧化的表面化学反应途径，表明Co-Mn-Ce催化剂的主要活性位点主要取决于表面氧空位和表面活性物质（Mn 4+ ,O广告）。图形摘要 构建了丙烷氧化的表面化学反应途径，表明 Co-Mn-Ce 催化剂的主要活性位点主要取决于表面氧空位和表面活性物质（Mn 4+ ,O ads ）。图形摘要 构建了丙烷氧化的表面化学反应途径，表明 Co-Mn-Ce 催化剂的主要活性位点主要取决于表面氧空位和表面活性物质（Mn 4+ ,O ads ）。图形摘要