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Structure and activity of mixed VOx-CeO2 domains supported on alumina in cyclohexane oxidative dehydrogenation
Journal of Catalysis ( IF 7.3 ) Pub Date : 2020-03-10 , DOI: 10.1016/j.jcat.2020.02.017
Izabela A. Samek , N. Scott Bobbitt , Randall Q. Snurr , Peter C. Stair

Alumina-supported VOx-CeO2 materials are synthesized by atomic layer deposition (ALD) and evaluated in cyclohexane oxidative dehydrogenation (ODH). The order of deposition of the two metal oxides by ALD influences the size, geometry and oxidation state of the resulting surface species as indicated by Raman spectroscopy coupled with density functional theory (DFT) calculations and XPS. The individual contributions of VOx and CeO2 surface sites to the cyclohexane ODH reaction mechanism are investigated through a comparison of the catalytic activity of the supported mixed metal oxide materials, VOx/Al2O3, VOx/CeO2 and a bare CeO2 support. The highest activity is observed for CeO2, and different surface active sites are distinguished by introducing cyclohexane and cyclohexene in the reactant feed mixture. The catalytic behavior is dependent on the nature of VOS (S, Support) bonds, and small clusters of CeO2 on Al2O3 favor total oxidation, similar to exposed CeO2 sites in VOx/CeO2.



中文翻译:

氧化铝在环己烷氧化脱氢中负载的VO x -CeO 2混合结构域的结构和活性

通过原子层沉积(ALD)合成氧化铝负载的VO x -CeO 2材料,并在环己烷氧化脱氢(ODH)中进行评估。通过拉曼光谱结合密度泛函理论(DFT)计算和XPS可以看出,通过ALD沉积两种金属氧化物的顺序会影响所得表面物种的大小,几何形状和氧化态。通过比较负载型混合金属氧化物材料VO x / Al 2 O 3,VO x / CeO 2的催化活性,研究了VO x和CeO 2表面位点对环己烷ODH反应机理的单独贡献。和裸露的CeO 2支持。对于CeO 2观察到最高的活性,并且通过在反应物进料混合物中引入环己烷和环己烯来区分不同的表面活性部位。催化行为取决于V O S(S,支撑)键的性质,Al 2 O 3上的CeO 2小簇有利于完全氧化,类似于VO x / CeO 2中暴露的CeO 2位。

更新日期:2020-03-10
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