Deoxygenation of benzoic acid on metal oxides: 1. The selective pathway to benzaldehyde

The mechanism of the selective deoxygenation of benzoic acid to benzaldehyde was studied on ZnO and ZrO 2. The results show conclusively that the reaction proceeds as a reverse type of Mars and van Krevelen mechanism consisting of two steps: hydrogen activates the oxide by reduction resulting in the...

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Bibliographic Details
Published in:Applied catalysis. A, General General, 2001-10, Vol.220 (1), p.41-49
Main Authors: de Lange, M.W., van Ommen, J.G., Lefferts, L.
Format: Article
Language:English
Subjects:
Benzaldehyde
Benzoic acid
Catalysis
Catalytic reactions
Chemistry
Deoxygenation
Exact sciences and technology
General and physical chemistry
Mars and van Krevelen mechanism
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
ZnO
ZrO 2
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Summary:The mechanism of the selective deoxygenation of benzoic acid to benzaldehyde was studied on ZnO and ZrO 2. The results show conclusively that the reaction proceeds as a reverse type of Mars and van Krevelen mechanism consisting of two steps: hydrogen activates the oxide by reduction resulting in the formation of oxygen vacancies. Subsequent re-oxidation of these vacancy sites by benzoic acid yields benzaldehyde. Inhibition of the deoxygenation reaction can be achieved by addition of suitable polar compounds with a high affinity for the oxygen vacancy sites such as carbon dioxide or water. Differences in the catalytic activity and selectivity of ZnO and ZrO 2 can be attributed to differences in hydrogen activation, redox properties and extent of benzoic acid coverage.
ISSN:0926-860X
1873-3875
DOI:10.1016/S0926-860X(01)00703-7