Studies on Crystalline Microporous Vanadium Silicates III. Selective Oxidation of n-Alkanes and Cyclohexane over VS-2

✍ Scribed by P.R.H.P. Rao; A.V. Ramaswamy; P. Ratnasamy

• Book ID: 102577027
• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 442 KB
• Volume: 141
• Category: Article
• ISSN: 0021-9517
• DOI: 10.1006/jcat.1993.1167

✦ Synopsis

The oxyfunctionalization of (n)-alkanes ( (C 6, C 7), and (C 8) ) and cyclohexane over vanadium silicates (VS-2) with (\mathrm{Si} / \mathrm{V}=79,122), and 161 in presence of aqueous (\mathrm{H}{2} \mathrm{O}{2}) yields corresponding alcohols and carbonyl compounds at (373 \mathrm{~K}). Unlike titanium silicates, VS-2 is able to activate the primary carbon atoms of (n)-alkanes, giving rise to primary alcohols and aldehydes in addition to secondary alcohols and ketones. The latter are, however, the preferred products of oxidation. The oxidative conversions and the (\mathrm{H}{2} \mathrm{O}{2}) selectivities decreased in the order, (n \mathrm{C} 6>\mathrm{C}{7}>n \mathrm{C} 8>) cyclohexane, consistent with the decrease in the diffusivity of these alkanes in the zeolites. Solvents have considerable influence on the conversion, (\mathrm{CH}{3} \mathrm{CN}) being the most suitable. The formation of a radical-type intermediate has been confirmed by ESR spectral observations. A possible mechanism for the oxidation through a peroxo radical intermediate has been proposed. 1993 Academic Press. Inc.