Vanadium oxide supported on mesoporous SBA-15 as highly selective catalysts in the oxidative dehydrogenation of propane
Vanadium oxide supported on mesoporous SBA-15 as highly selective catalysts in the oxidative dehydrogenation of propane
复制标题
DOI：
10.1016/j.jcat.2004.03.010
复制
发表时间：
2004-06-10
影响因子：
7.3
通讯作者：
Fan, KN
中科院分区：
文献类型：
--
作者：
Liu, YM;Cao, Y;Fan, KN
结合不同的技术（DR UV-vis，V-51 NMR，UV-Raman，FTIR和H-2-TPR）在介孔SBA-15催化剂上负载的氧化钒的表征表明，钒物种的分散性和性质强烈依赖于V负载量。在V含量低于2.8wt%的脱水催化剂中，钒主要处于四面体环境中。催化剂中V含量越高，催化剂中的V2 O 5类聚合物越多。织构、SEM/TEM和XRD结果表明，钒的引入保持了载体的有序六方介孔结构和大孔径结构，从而提高了催化剂的比表面积。锚定到表面的钒物种表现出类似的结构性能上的介孔V-MCM和传统的V-SiO2催化剂，但更高的表面浓度的孤立或低聚合的VOx物种可以实现对V-SBA样品。酸中心的数量和性质也随钒负载量而变化。本发明的介孔SBA-15催化剂在丙烷氧化脱氢中的上级性能归因于V物种在具有大孔径的SBA-15载体上实现的较高分散以及催化剂的低表面酸性。(C)2004年爱思唯尔公司All rights reserved.
The combination of different techniques (DR UV-vis, V-51 NMR, UV-Raman, FTIR, and H-2-TPR) in the characterization of vanadia supported on mesoporous SBA-15 catalysts shows that the dispersity and the nature of the vanadium species depend strongly on the V loading. In dehydrated catalysts with V contents lower than 2.8 wt%, vanadium is mainly in a tetrahedral environment. Higher V contents in the catalyst lead to the formation of polymeric V2O5-like species. Textural, SEM/TEM, and XRD results indicate that the ordered hexagonal mesoporous structure with large pore diameters of the support is retained upon the vanadium incorporation, and therefore high surface areas were obtained on the final catalysts. Vanadium species anchored to the surface show structural properties similar to those on mesoporous V-MCM and conventional V-SiO2 catalysts, but a higher surface concentration of isolated or low polymeric VOx species could be achieved on the V-SBA samples. The number and nature of the acid sites also change with the vanadium loading. The superior performance of the present mesoporous SBA-15 catalysts in the oxidative dehydrogenation of propane has been attributed to a higher dispersion of V species achieved on the SBA-15 support with large pore diameters as well as the low surface acidity of the catalyst. (C) 2004 Elsevier Inc. All rights reserved.