Vanadium Oxide Supported on Mesoporous MCM-41 as Selective Catalysts in the Oxidative Dehydrogenation of Alkanes
Vanadium Oxide Supported on Mesoporous MCM-41 as Selective Catalysts in the Oxidative Dehydrogenation of Alkanes
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DOI：
10.1006/jcat.2001.3326
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发表时间：
2001-10
影响因子：
7.3
通讯作者：
B. Solsona;T. Blasco;J. Nieto;M. L. Peña;F. Rey;A. Vidal-Moya
中科院分区：
文献类型：
--
作者：
B. Solsona;T. Blasco;J. Nieto;M. L. Peña;F. Rey;A. Vidal-Moya
不同技术（51V NMR、漫反射和 TPR-H2）在介孔 MCM-41 催化剂负载的氧化钒表征中的应用表明，钒物质的性质取决于 V 负载量。在V含量低于7wt%的脱水催化剂中，钒主要处于四面体环境中。在存在水分的情况下，大多数放置在可接近位置的 V5+ 与水分子结合，成为六配位，而一些可能位于孔壁内的 V5+ 物种保持其四面体配位。催化剂中较高的 V 含量会导致形成类似 V2O5 的聚合物质。 XRD 和织构结果均表明，掺入钒后载体的介孔结构大部分保持不变，因此最终催化剂获得了高表面积。 MCM-41 负载的氧化钒催化剂在丙烷和乙烷的氧化脱氢中具有活性和选择性，尽管催化行为取决于 V 负载量。由于在载体表面上实现了V原子的高度分散，还观察到每单位时间每单位质量催化剂的丙烯或乙烯的高形成速率。
The application of different techniques (51V NMR, diffuse reflectance, and TPR-H2) in the characterization of vanadia supported on mesoporous MCM-41 catalysts shows that the nature of the vanadium species depends on the V loading. In dehydrated catalysts with V content lower than 7 wt%, vanadium is mainly in a tetrahedral environment. In the presence of moisture, most V5+, placed in accessible positions, binds to water molecules, becoming hexacoordinated, while some V5+ species, probably located within the pore walls, keep their tetrahedral coordination. Higher V contents in the catalyst leads to the formation of polymeric V2O5-like species. Both XRD and textural results indicate that the mesoporous structure of the support is mostly maintained after the vanadium incorporation, and therefore high surface areas were obtained on the final catalysts. MCM-41-suppported vanadia catalysts are active and selective in the oxidative dehydrogenation of propane and ethane, although the catalytic behavior depends on the V loading. A high rate of formation of propylene or ethylene per unit mass of catalyst per unit time have also been observed as a consequence of the high dispersion of V atoms achieved on the surface of the support.