title: Highly Dispersed SiO(x)/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 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 (29)Si and (27)Al 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.
authors.affiliation: Chemistry Department and the Center for Catalysis and Surface Science, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208 (USA).
authors.forename: Aidan R
authors.initials: AR
authors.lastname: Mouat
authors.affiliation: Chemistry Department and the Center for Catalysis and Surface Science, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208 (USA).
authors.forename: Cassandra
authors.initials: C
authors.lastname: George
authors.affiliation: U.S. DOE Ames Laboratory, and Department of Chemistry, Iowa State University, Ames, IA 50011 (USA).
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: U.S. DOE Ames Laboratory, and Department of Chemistry, Iowa State University, Ames, IA 50011 (USA).
authors.forename: Marek
authors.initials: M
authors.lastname: Pruski
authors.affiliation: Chemistry Department and the Center for Catalysis and Surface Science, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208 (USA).
authors.forename: Richard P
authors.initials: RP
authors.lastname: van Duyne
authors.affiliation: Chemistry Department and the Center for Catalysis and Surface Science, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208 (USA). t-marks@northwestern.edu.
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks
authors.affiliation: Chemistry Department and the Center for Catalysis and Surface Science, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208 (USA). pstair@northwestern.edu.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Stair
keywords: alcohol dehydration; atomic layer deposition; heterogeneous catalysis; silica-alumina; solid acid