Relationships between the structure and the surface activity of nano-sized alumina in acid catalysis

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:51669

Coster, D; Gruver, V; Blumenfeld, A; Fripiat, J J ^[1]

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1. Univ. of Wisconsin, Milwaukee, WI (United States)

As shown in another communication to Symposium 5, nano-sized aluminas enriched in pentacoordinated aluminum (Al{sup V}) are obtained through the limited hydrolysis of aluminum alkoxides. Here the surface properties of these aluminas are investigated from the catalytic point of view. The goal is to obtain geometrical information on the Lewis acid sites. {sup 1}H{r_arrow}{sup 27}Al (cross-polarization) high resolution MAS NMR, using chemisorbed NH{sub 3} which acts as a {sup 1}H spin reservoir, allows the direct observation of surface Al involved in the catalytic site. The polarization transfer from these protons to surface Al is remarkably efficient because of the relatively short Al:N-H distance. It is observed that the main Lewis acid sites are located on distorted tetrahedral aluminum and pentacoordinated Al. These results are compared to low temperature infrared data of adsorbed CO.

• OSTI ID: 51669
• Report Number(s): CONF-940411--; ISBN 1-55899-246-4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ALUMINIUM OXIDES
AMMONIA
CARBON MONOXIDE
CATALYSTS
CHEMISORPTION
CRYSTAL STRUCTURE
FOURIER TRANSFORM SPECTROMETERS
LEWIS ACIDS
NUCLEAR MAGNETIC RESONANCE
SURFACE AREA
SURFACE PROPERTIES