MoO_x

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• 作者：N. Haddad ; E. Bordes-Richard ; A. Barama
• 关键词：Molybdenium oxides ; Vanadium oxides ; MoVPO oxides ; ODH ethane
• 刊名：Catalysis Today
• 出版年：2009
• 期刊代码：13_09205861
• 类别：ce
• 出版时间：30 April 2009
• 卷：142
• 期：3-4
• 页码：215-219
• 文件大小：330 K

摘要

The influence of vanadium and phosphorus on the physicochemical properties of the MoO_x oxide and on its catalytic properties in the oxidation of ethane to ethylene is examined. A series of MoO_x, MoVO_x (Mo/V = 11) and MoVPO_x (Mo/V = 11, V/P = 1) catalysts were prepared, characterized by several techniques (BET, XRD, XPS, LRS and ATG) and studied in the oxidative dehydrogenation of ethane to ethene at atmospheric pressure and at the temperature of reaction of 550 °C. Their structural properties, during reduction and re-oxidation, were examined by in situ X-ray diffraction and by X-ray photoelectron spectroscopy after pre-treatment. The sample containing phosphorus is the most active (conversion 14%) and selective to ethylene (SC₂H₄ = 67%). The formation of [PMo₁₁VO₄₀]⁴⁻ is assumed during preparation, and its decomposition during calcination leads to well dispersed phosphate groups and improved interactions between Mo and V species. During the catalytic reaction Mo^VI is stabilised by means of solid solutions of V in Mo₅O₁₄ and in MoO₃ (V_xMo_1−xO_3−x/2). A synergetic effect between these two phases could be responsible for the best performance of Mo₁₁VPO_x as compared to those of MoO_x and Mo₁₁VO_x.