Influence of MgO-modified SBA-15 on the structure and catalytic activity of supported vanadium oxide catalysts
Influence of MgO-modified SBA-15 on the structure and catalytic activity of supported vanadium oxide catalysts
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DOI：
10.1016/j.jcat.2013.08.031
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发表时间：
2014
影响因子：
7.3
通讯作者：
J. Scholz;Anke Walter;T. Ressler
中科院分区：
文献类型：
--
作者：
J. Scholz;Anke Walter;T. Ressler
引入碱性高表面积 MgO/SBA-15 载体上的钒氧化物作为模型系统，用于研究选择性氧化反应中的结构-活性相关性。通过 X 射线衍射、N2 物理吸附、X 射线吸收光谱和漫反射紫外可见光谱研究了负载型氧化钒催化剂。氧化钒物种由四面体单元组成，而低聚度取决于催化剂负载量和氧化钒分散度。由于氧化物载体的碱性表面，低低聚[VO4]四面体可以稳定在较高的覆盖率下。该结构与酸性载体（例如 SBA-15）上存在的高低聚氧化钒物质进行了比较。采用气相色谱法研究了氧化物催化剂在丙烯选择性氧化中的催化性能。丙烯醛周转频率作为表面覆盖度的函数表现出火山型行为。在最佳表面覆盖度下，催化剂结构主要由二聚[V2O7]单元组成。
Vanadium oxides on an alkaline, high-surface-area MgO/SBA-15 support are introduced as a model system for investigating structure–activity correlations in selective oxidation reactions. The supported vanadium oxide catalysts were investigated by X-ray diffraction, N2physisorption, X-ray absorption spectroscopy, and diffuse reflectance UV–vis spectroscopy. The vanadium oxide species consisted of tetrahedral units, while the oligomerization degree depended on catalyst loading and vanadium oxide dispersion. Low-oligomeric [VO4] tetrahedra could be stabilized at comparably high coverage due to the alkaline surface of the oxide support. The structure was compared to higher-oligomeric vanadium oxide species present on acidic supports such as SBA-15. Catalytic performance of the oxide catalysts in selective propene oxidation was investigated by gas chromatography. Acrolein turnover frequency as a function of surface coverage exhibited volcano-type behavior. At optimal surface coverage, the catalyst structure consisted mainly of dimeric [V2O7] units.