Origin of the Activity Trend in the Oxidative Dehydrogenation of Ethanol over VOx/CeO2

Supported vanadia (VOx) is a versatile catalyst for various redox processes where ceria‐supported VOx have shown to be particularly active in the oxidative dehydrogenation (ODH) of alcohols. In this work, we clarify the origin of the volcano‐shaped ethanol ODH activity trend for VOx/CeOx catalysts u...

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Bibliographic Details
Published in:Angewandte Chemie 2023-04, Vol.135 (18), p.n/a
Main Authors: Zabilska, Anna, Zabilskiy, Maxim, Nuguid, Rob Jeremiah G., Clark, Adam H., Sadykov, Ilia I., Nachtegaal, Maarten, Kröcher, Oliver, Safonova, Olga V.
Format: Article
Language:English
Subjects:
Alcohols
Catalysts
Cerium
Cerium oxides
Chemistry
Dehydrogenation
Ethanol
Heterogeneous Catalysis
Optimization
Oxidative Dehydrogenation
Reaction Mechanisms
Supported Catalysts
Vanadium
X-Ray Absorption Spectroscopy
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Summary:Supported vanadia (VOx) is a versatile catalyst for various redox processes where ceria‐supported VOx have shown to be particularly active in the oxidative dehydrogenation (ODH) of alcohols. In this work, we clarify the origin of the volcano‐shaped ethanol ODH activity trend for VOx/CeOx catalysts using operando quick V K‐ and Ce L3‐ edge XAS experiments performed under transient conditions. We quantitatively demonstrate that both vanadium and cerium are synergistically involved in alcohol ODH. The concentration of reversible Ce4+/Ce3+ species was identified as the main descriptor of the alcohol ODH activity. The activity drop in the volcano plot, observed at above ca. 3 V nm−2 surface loading (ca. 30 % of VOx monolayer coverage), is related to the formation of spectator V4+ and Ce3+ species, which were identified here for the first time. These results might prove to be helpful for the rational optimization of VOx/CeO2 catalysts and the refinement of the theoretical models. Using operando time‐resolved X‐ray absorption spectroscopy, we investigated the origin of the volcano‐shaped activity trend in the oxidative dehydrogenation of ethanol over VOx/CeO2 catalysts as a function of VOx surface coverage. Vanadium and cerium synergistically change their oxidation states during the catalytic cycle. The catalytic activity correlates with the concentration of reversible Ce4+/3+ species.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.202301297