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Highly Dispersed SiOx/Al2O3 Catalysts Illuminate the Reactivity of Isolated Silanol Sites

TitleHighly Dispersed SiOx/Al2O3 Catalysts Illuminate the Reactivity of Isolated Silanol Sites
Publication TypeJournal Article
Year of Publication2015
AuthorsMouat, AR, George, C, Kobayashi, T, Pruski, M, van Duyne, RP, Marks, TJ, Stair, PC
JournalAngewandte Chemie-International Edition
Volume54
Pagination13346-13351
Date Published11
Type of ArticleArticle
ISBN Number1433-7851
Accession NumberWOS:000363691500034
Keywordsalcohol dehydration, amorphous aluminosilicates, atomic layer deposition, bronsted acid sites, chemical-vapor-deposition, gamma-alumina, Heterogeneous catalysis, infrared-spectroscopy, nmr-spectroscopy, silica-alumina, solid acid, surface hydroxyl-groups, xylene isomerization
Abstract

The reaction of -alumina with tetraethylorthosilicate (TEOS) vapor at low temperatures selectively yields monomeric SiOx species on the alumina surface. These isolated (-AlO)(3)Si(OH) sites are characterized by PXRD, XPS, DRIFTS of adsorbed NH3, CO, and pyridine, and Si-29 and Al-27 DNP-enhanced solid-state NMR spectroscopy. The formation of isolated sites suggests that TEOS reacts preferentially at strong Lewis acid sites on the -Al2O3 surface, functionalizing the surface with mild BrOnsted acid sites. For liquid-phase catalytic cyclohexanol dehydration, these SiOx sites exhibit up to 3.5-fold higher specific activity than the parent alumina with identical selectivity.

DOI10.1002/anie.201505452
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