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Mesoporous (Cr)MCM-41: A mild and efficient heterogeneous catalyst for selective oxidation of cyclohexane

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Title Mesoporous (Cr)MCM-41: A mild and efficient heterogeneous catalyst for selective oxidation of cyclohexane
 
Creator SAKTHIVEL, A
SELVAM, P
 
Subject liquid-phase oxidations
diffuse-reflectance spectroscopy
supported chromium catalysts
molecular-sieves
ethylene polymerization
electron-transfer
mcm-41 materials
oxygen
complexes
silicate
cyclohexane
cyclohexanol
cyclohexanone
(cr)mcm-41
oxidation
mesoporous molecular sieves
 
Description Liquid-phase oxidation of cyclohexane was carried out at moderate reaction conditions over mesoporous (Cr)MCM-41 molecular sieves using acetic acid as solvent, hydrogen peroxide as oxidant, and methyl ethyl ketone as initiator. Under these conditions, the catalysts showed high substrate conversion and excellent product selectivity. Although the activity of the catalyst decreased after the first recycle, owing to leaching of nonframework chromium ions, it, however, remained nearly the same thereafter. This observation was further confirmed by washing experiments where the nonframework chromium ions were removed upon ammonium acetate treatment or under reaction conditions. Further, the washed catalyst also showed a activity similar to that of the recycled catalyst. The recycled or washed (Cr)MCM-41, therefore, behaves truly as a heterogeneous catalyst, and thus it forms the first example of a nonleaching chromium-based catalyst reported so far. The use of a stronger oxidizing agent, e.g., tertiary butyl hydroperoxide, resulted in the formation of cyclohexanone as the major product. On the other hand, the use of solvents like methanol, dioxan, and acetone showed lower conversion. Likewise, the use of initiators such as acetone, cyclohexanone, and acetaldehyde also resulted in lower activity. .
 
Publisher ACADEMIC PRESS INC ELSEVIER SCIENCE
 
Date 2011-07-12T15:58:34Z
2011-12-26T12:48:57Z
2011-12-27T05:34:30Z
2011-07-12T15:58:34Z
2011-12-26T12:48:57Z
2011-12-27T05:34:30Z
2002
 
Type Article
 
Identifier JOURNAL OF CATALYSIS, 211(1), 134-143
0021-9517
http://dx.doi.org/10.1006/jcat.2002.3711
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3371
http://hdl.handle.net/10054/3371
 
Language en