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

Aidan R. Mouat; Cassandra George; Takeshi Kobayashi; Marek Pruski; Richard P. Van Duyne; Tobin J. Marks; Peter C. Stair

doi:10.1002/anie.201505452

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

Aidan R. Mouat, Cassandra George, Takeshi Kobayashi, Marek Pruski, Richard P. Van Duyne, Tobin J. Marks, Peter C. Stair

Research output: Contribution to journal › Article › peer-review

49 Scopus citations

Abstract

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

Original language	English (US)
Pages (from-to)	13346-13351
Number of pages	6
Journal	Angewandte Chemie - International Edition
Volume	54
Issue number	45
DOIs	https://doi.org/10.1002/anie.201505452
State	Published - Nov 1 2015

Keywords

alcohol dehydration
atomic layer deposition
heterogeneous catalysis
silica-alumina
solid acid

ASJC Scopus subject areas

Catalysis
Chemistry(all)

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title = "Highly Dispersed SiOx/Al2O3 Catalysts Illuminate the Reactivity of Isolated Silanol Sites",

abstract = "The reaction of γ-alumina with tetraethylorthosilicate (TEOS) vapor at low temperatures selectively yields monomeric SiOx species on the alumina surface. These isolated (-AlO)3Si(OH) sites are characterized by PXRD, XPS, DRIFTS of adsorbed NH3, CO, and pyridine, and 29Si and 27Al DNP-enhanced solid-state NMR spectroscopy. The formation of isolated sites suggests that TEOS reacts preferentially at strong Lewis acid sites on the γ-Al2O3 surface, functionalizing the surface with {"}mild{"} Br{\o}nsted 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.",

keywords = "alcohol dehydration, atomic layer deposition, heterogeneous catalysis, silica-alumina, solid acid",

author = "Mouat, {Aidan R.} and Cassandra George and Takeshi Kobayashi and Marek Pruski and {Van Duyne}, {Richard P.} and Marks, {Tobin J.} and Stair, {Peter C.}",

note = "Publisher Copyright: {\textcopyright} 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.",

year = "2015",

month = nov,

day = "1",

doi = "10.1002/anie.201505452",

language = "English (US)",

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journal = "Angewandte Chemie - International Edition",

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publisher = "John Wiley and Sons Ltd",

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Highly Dispersed SiO_x/Al₂O₃ Catalysts Illuminate the Reactivity of Isolated Silanol Sites. / Mouat, Aidan R.; George, Cassandra; Kobayashi, Takeshi; Pruski, Marek; Van Duyne, Richard P.; Marks, Tobin J.; Stair, Peter C.

In: Angewandte Chemie - International Edition, Vol. 54, No. 45, 01.11.2015, p. 13346-13351.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Highly Dispersed SiOx/Al2O3 Catalysts Illuminate the Reactivity of Isolated Silanol Sites

AU - Mouat, Aidan R.

AU - George, Cassandra

AU - Kobayashi, Takeshi

AU - Pruski, Marek

AU - Van Duyne, Richard P.

AU - Marks, Tobin J.

AU - Stair, Peter C.

PY - 2015/11/1

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N2 - The reaction of γ-alumina with tetraethylorthosilicate (TEOS) vapor at low temperatures selectively yields monomeric SiOx species on the alumina surface. These isolated (-AlO)3Si(OH) sites are characterized by PXRD, XPS, DRIFTS of adsorbed NH3, CO, and pyridine, and 29Si and 27Al DNP-enhanced solid-state NMR spectroscopy. The formation of isolated sites suggests that TEOS reacts preferentially at strong Lewis acid sites on the γ-Al2O3 surface, functionalizing the surface with "mild" Brønsted 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.

AB - The reaction of γ-alumina with tetraethylorthosilicate (TEOS) vapor at low temperatures selectively yields monomeric SiOx species on the alumina surface. These isolated (-AlO)3Si(OH) sites are characterized by PXRD, XPS, DRIFTS of adsorbed NH3, CO, and pyridine, and 29Si and 27Al DNP-enhanced solid-state NMR spectroscopy. The formation of isolated sites suggests that TEOS reacts preferentially at strong Lewis acid sites on the γ-Al2O3 surface, functionalizing the surface with "mild" Brønsted 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.

KW - alcohol dehydration

KW - atomic layer deposition

KW - heterogeneous catalysis

KW - silica-alumina

KW - solid acid

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