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|Type:||Artigo de periódico|
|Title:||Cyclohexane oxidation over rare earth exchanged zeolite Y|
|Abstract:||Rare earth exchanged zeolites Y (REY) were prepared from HY with Si:Al ratios of 2.6, 12.5 and 28 by solid-state ion exchange with CeCl3, NdCl3, SmCl3, EuCl3 or YbCl3. The resulting REY were used as catalysts for the liquid-phase oxidation of cyclohexane with tert-butyl hydroperoxide. Cyclohexene, n-hexanal, cyclohexanone and cyclohexanol are the principal products formed. The activity of the catalysts depends on the Si:Al ratio: 12.5 > 2.6 > 28, on the rare earth cations: Ce much greater than Yb > Sm > Eu > Nd, and on the temperature. Using CeY with a Si:AI ratio of 12.5, at 50, 70 and 90 degrees C, cyclohexane conversions of 4.7, 7.3 and 10% and turnover numbers of 236, 366 and 505, respectively, are observed after 24 h. However, at 90 degrees C large amounts of carboxylic acids are formed. Leaching experiments with CeY show that most of the products are formed in a heterogeneously catalysed reaction. (C) 1998 Elsevier Science B.V. All rights reserved.|
|Subject:||rare earth metals|
|Editor:||Elsevier Science Bv|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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