Effects of CeO2 support facets on VOx/CeO2 catalysts in oxidative dehydrogenation of methanol

• VOx/CeO2 catalysts with well-defined CeO2 facets are highly desirable as promising model catalysts.
• Morphology and exposed facets of CeO2 supports affect the activity of oxidative dehydrogenation of methanol.
• VOx preferentially occupy the CeO2 (1 0 0) facets, followed by the (1 1 0) and (1 1 1) facets.
• VOx active centers on (1 1 0) facets exhibit highest activity, likely related to their high oxygen defect density.

CeO2 supports with dominating facets, i.e., low index (1 0 0), (1 1 0) and (1 1 1) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (1 0 0) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (1 0 0) facets show better dispersion, followed by (1 1 0) and (1 1 1) facets. The VOx species on CeO2 nanorods with (1 1 0) and (1 0 0) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (1 1 1) facets and CeO2 nanocubes with dominating (1 0 0) facets. The higher activity for VOx/CeO2 (1 1 0) might be related to the more abundant oxygen vacancies present on the (1 1 0) facets, evidenced from Raman spectroscopic measurements.

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