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

Abstract

AbstractSupported 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.