Effects of oxidant and solvent on the liquid-phase cyclohexane oxidation catalyzed by Ce-exchanged zeolite Y

• Published in: Applied catalysis. A, General General, 2000-10, Vol.203 (2), p.231-237
• Main Authors: Pires, Emerson L, Magalhães, João C, Schuchardt, Ulf
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts: preparations and properties; Cerium; Chemistry; Cyclohexane oxidation; Exact sciences and technology; General and physical chemistry; Molecular sieves; Redox catalysts; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/S0926-860X(00)00496-8

The effect of several solvents on the cyclohexane oxidation to cyclohexanol and cyclohexanone under mild conditions ( T=343 K, 24 h) using zeolite Y (Si:Al=12.5) exchanged with Ce(III) as catalyst, and tert-butyl-hydroperoxide ( t-BHP) and hydrogen peroxide (H 2O 2) as oxygen atom donors was studied. The results show that higher cyclohexane conversions are obtained in the following order: no solvent>1,2-dichloroethane>dichloromethane>acetone>acetonitrile>pyridine. Using t-BHP as oxidant, n-hexanal formation is observed as by-product and the selectivity increases when solvents with more basic characteristics (e.g. acetonitrile and pyridine) are used. Reactions with H 2O 2 as oxidant are highly selective yielding cyclohexanol as the major product, however, the conversion is low. Leaching experiments show that homogeneous Ce 3+ is not responsible for the catalytic activity. However, the catalyst is deactivated in recycling experiments, probably due to the formation of carboxylic acids, which block the pore entrances and/or complex to the active sites.