Nature of surface deposits on sulfated zirconia used as catalyst in the benzoylation of anisole

The benzoylation of anisole with benzoic anhydride over sulfated zirconia has been investigated, especially with regard to catalyst deactivation and regeneration. Calcined sulfated zirconia and spent catalysts have been characterized by BET analysis, C-H elemental analysis, DRIFTS, NH3-TPD, 13C-NMR...

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Bibliographic Details
Published in:Catalysis letters 2002-11, Vol.83 (3-4), p.271-279
Main Authors: TRUNSCHKE, A, DEUTSCH, J, MÜLLER, D, LIESKE, H, QUASCHNING, V, KEMNITZ, E
Format: Article
Language:English
Subjects:
Ammonia
Anhydrides
Anisole
Benzoates
Benzoylation
Catalysis
Catalysts
Catalytic reactions
Chemistry
Deactivation
Exact sciences and technology
General and physical chemistry
NMR
Nuclear magnetic resonance
Protonation
Reaction products
Regeneration
Roasting
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Zirconium dioxide
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Summary:The benzoylation of anisole with benzoic anhydride over sulfated zirconia has been investigated, especially with regard to catalyst deactivation and regeneration. Calcined sulfated zirconia and spent catalysts have been characterized by BET analysis, C-H elemental analysis, DRIFTS, NH3-TPD, 13C-NMR and UV-Vis spectroscopy. In batch-mode experiments, a moderate deactivation attributed to the deposition of carbonaceous surface species has been observed. The surface deposits consist of benzoate species and strongly adsorbed molecules of anisole. A color change of the solid, observed immediately after the introduction of the catalyst into the reaction mixture, has been attributed to the protonation of the reaction products 2- and/or 4-methoxybenzophenone. The surface species formed may cover or modify surface acid sites and, in this way, reduce the accessibility of active centers. Removing the deposited and adsorbed species by calcination in air restores the initial activity of sulfated zirconia.
ISSN:1011-372X
1572-879X
DOI:10.1023/A:1021050401227