V5在磷酸钒催化正丁烷氧化反应中的动力学意义
The Kinetic Significance of V5 in n-Butane Oxidation Catalyzed by Vanadium Phosphates.
作者信息
Coulston GW, Bare SR, Kung H, Birkeland K, Bethke GK, Harlow R, Herron N, Lee PL
机构信息
G. W. Coulston, R. Harlow, N. Herron, DuPont Company, Wilmington, DE 19880-0262, USA. S. R. Bare, Dow Chemical Company, Midland, MI 48674, USA. H. Kung, K. Birkeland, G. K. Bethke, Ipatieff Laboratory, Northwestern University, Evanston, IL 60208-3000, USA. P. L. Lee, Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA.
出版信息
Science. 1997 Jan 10;275(5297):191-3. doi: 10.1126/science.275.5297.191.
Maleic anhydride, a precursor to polyester resins, is made by oxidation of n-butane over vanadium phosphate catalysts. This system is of general interest because it is the only heterogeneously catalyzed, alkane-selective oxidation reaction in commercial use. Time-resolved in situ x-ray absorption spectroscopy shows that when either alphaI-VOPO4/SiO2 or (VO)2P2O7/SiO2 catalysts are exposed to n-butane, the rate of maleic anhydride formation is proportional to the rate of decay of V5+ species in the catalyst. Thus V5+ species are kinetically significant for the production of maleic anhydride and not just for the production of by-products. The results also suggest that V5+ species may play a role in the initial hydrogen abstraction from n-butane, the rate-determining step in the reaction sequence. V4+ sites appear to be responsible for by-product formation.
马来酸酐是聚酯树脂的前体，它通过正丁烷在磷酸钒催化剂上的氧化反应制得。该体系备受关注，因为它是商业应用中唯一的非均相催化烷烃选择性氧化反应。时间分辨原位X射线吸收光谱表明，当αI-VOPO4/SiO2或(VO)2P2O7/SiO2催化剂暴露于正丁烷时，马来酸酐的生成速率与催化剂中V^5+物种的衰减速率成正比。因此，V^5+物种在马来酸酐的生成中具有动力学意义，而不仅仅是在副产物的生成中。结果还表明，V^5+物种可能在正丁烷的初始氢提取中起作用，这是反应序列中的速率决定步骤。V^4+位点似乎是副产物形成的原因。
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