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首页> 外文期刊>RSC Advances >The effect of redox properties of ceria-supported vanadium oxides in liquid phase cyclohexene oxidation
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The effect of redox properties of ceria-supported vanadium oxides in liquid phase cyclohexene oxidation

机译：二氧化铈负载的钒氧化物在液相环己烯氧化中的氧化还原性能的影响

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摘要

Several VO2/CeO2 based catalysts, with V loadings between 5 and 20 wt%, were prepared by impregnation and subsequently dried, calcined and reduced at 673 K. The structural characterization of these materials was carried out using X-ray diffraction (XRD), N-2 adsorption-desorption at 77 K, UV-vis diffuse reflectance spectroscopy (DR UV-vis) and Fourier-transform infrared spectroscopy (FTIR). Their catalytic activities in the epoxidation of cyclohexene, with TBHP as oxidant and heptane as solvent, were also examined. XRD results revealed a good dispersion of VO2 species on ceria. FTIR and DR UV-visible spectroscopy techniques indicated that polymeric vanadyl species are present on all catalysts and a crystalline VO2 phase appears on the 20 wt% vanadium sample. Experimental results revealed that catalyst activity decreases with increased vanadium loading, whereas the epoxide selectivity increased up to 90% when the vanadia loading reached 15 wt%. In the case of 20 wt% VO2/CeO2, the reaction switched towards a 100% enol, enone selectivity. The presence of CeVO4 was shown to influence the conversion and selectivity of the reaction.
机译：通过浸渍制备了几种V / CeO2基的VO2 / CeO2催化剂，然后进行浸渍，煅烧和还原，在673 K下进行V负载。使用X射线衍射（XRD）对这些材料进行结构表征， N-2在77 K下的吸附-解吸，紫外可见漫反射光谱（DR紫外可见）和傅里叶变换红外光谱（FTIR）。还考察了它们在以TBHP为氧化剂和庚烷为溶剂的环己烯环氧化中的催化活性。 XRD结果表明二氧化铈上VO 2种类良好分散。 FTIR和DR紫外可见光谱技术表明，所有催化剂上均存在聚合钒基物质，而20重量％的钒样品上出现结晶VO2相。实验结果表明，催化剂活性随钒载量的增加而降低，而当钒载量达到15 wt％时，环氧化物的选择性增加至90％。在20重量％VO 2 / CeO 2的情况下，反应转向100％烯醇，烯酮选择性。已显示CeVO4的存在会影响反应的转化率和选择性。

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