The Effect of Mn Content on Catalytic Activity of the Co-Mn-Ce Catalysts for Propane Oxidation: Importance of Lattice Defect and Surface Active Species
The Effect of Mn Content on Catalytic Activity of the Co-Mn-Ce Catalysts for Propane Oxidation: Importance of Lattice Defect and Surface Active Species
复制标题
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
DOI：
10.1007/s10562-019-03061-6
复制
发表时间：
2020
影响因子：
2.8
通讯作者：
Lei Lili
中科院分区：
文献类型：
--
作者：
Wang Pan;Cui Chenrui;Li Kai;Yi Jing;Lei Lili
采用共沉淀法制备了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。采用X射线衍射（XRD）、X射线光电子能谱（XPS）、电子顺磁共振（EPR）、H2程序升温还原（H2-TPR）和原位DRIFTs等手段对催化剂的晶相结构、元素价态、氧空位和还原性能进行了表征。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。采用流动反应器研究了Mn含量对Co-Mn-Ce催化剂上丙烷氧化反应起燃温度（T10）和完全氧化温度（T90）的影响。结果表明，当x = 1时，催化剂具有最高的活性（T10= 200 °C，T90= 307 °C）和耐水性。结果表明，当x = 1时，Mn的引入可以提高Co-Mn-Ce催化剂的丙烷氧化性能。基于Langmuir-Hinshelwood理论，构建了丙烷氧化的表面化学反应途径，揭示了Co-Mn-Ce催化剂的主要活性中心主要取决于表面氧空位和表面活性物种（Mn 4+，Oads）。
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), H2temperature program reduction(H2-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 (T10) and complete oxidation temperature (T90) 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 (T10= 200 °C, T90= 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 (Mn4+,Oads).Graphic Abstract