期刊
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
卷 -, 期 -, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/anie.202301297
关键词
Heterogeneous Catalysis; Oxidative Dehydrogenation; Reaction Mechanisms; Supported Catalysts; X-Ray Absorption Spectroscopy
In this study, the origin of the volcano-shaped activity trend for VOx/CeOx catalysts in ethanol oxidative dehydrogenation (ODH) was clarified using operando quick V K- and Ce L-3- edge XAS experiments. It was found that both vanadium and cerium synergistically contribute to the alcohol ODH activity, with the concentration of reversible Ce4+/Ce3+ species being the main descriptor. The activity drop observed at a surface loading above ca. 3 V nm(-2) (ca. 30% VOx monolayer coverage) was attributed to the formation of spectator V4+ and Ce3+ species, which were identified for the first time.
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 L-3- 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.
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