Journal of Catalysis, Vol.384, 147-158, 2020
Structure and activity of mixed VOx-CeO2 domains supported on alumina in cyclohexane oxidative dehydrogenation
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 V-O-S (S, Support) bonds, and small clusters of CeO2 on Al2O3 favor total oxidation, similar to exposed CeO2 sites in VOx/CeO2. (C) 2020 Elsevier Inc. All rights reserved.
Keywords:Oxidative dehydrogenation;Cyclohexane;Supported vanadium oxide;Cerium oxide;Atomic layer deposition;DFT