On the acid-catalyzed isomerization of light paraffins over a ZrO{sub 2}/SO{sub 4} system: The effect of hydration
- Univ. of Turin (Italy)
- Univ. of Venice (Italy); and others
Over a superacid ZrO{sub 2}/SO{sub 4} system (ZS8; microcrystalline tetragonal, SO{sub 4} content {approximately}2.6 groups per nm{sup 2}), the isomerization of n-butane proceeds rapidly and with high yield of i-butane at 423 K, if the catalyst is calcined in dry air at {approximately}823 K. The active catalyst typically shows: all surface sulfates in a highly covalent form, a high concentration of strong (aprotic) Lewis acid sites, and a fairly low (though never null) concentration of (protonic) Broensted acid sites. A partial rehydration of the catalyst gradually converts the surface sulfates first into a less covalent form and then into an ionic form, decreases the concentration of strong Lewis sites, and increases (up to a factor of {approximately}10) the concentration of Broensted sites, while the catalytic activity is gradually extinguished. Initial activity and initial surface features can be recovered by repeating the catalyst activation step. 17 refs., 5 figs.
- OSTI ID:
- 110986
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 149; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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