The formation of titanium oxide monolayer coatings on silica surfaces

Journal Article · Sun Sep 01 04:00:00 EDT 1991 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(91)90343-3· OSTI ID:5757118

Srinivasan, S; Datye, A K; Hampden-Smith, M ^[1]; Wachs, I E; Deo, G; Jehng, J M; Turek, A M ^[2]; Peden, C H.F. ^[3]

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1. Univ. of New Mexico, Albuquerque (United States)
2. Lehigh Univ., Bethlehem, PA (United States)
3. Sandia National Labs., Albuquerque, NM (United States)

The formation of a dispersed titanium oxide layer on Cabosil-fumed silica and on nonporous silica spheres was studied by infrared and Raman spectroscopies and by transmission electron microscopy (TEM). The procedure for obtaining the titania coatings involved reacting the silanol groups on the silica surface with titanium alkoxides under a N{sub 2} atmosphere. This self-limiting reaction led to a coating of dispersed titania on the silica spheres with a weight loading between 0.5 and 1.4 {times} 10{sup {minus}3} g/m{sup 2}. The dispersed titanium oxide on the silica spheres was visible as a surface texturing of the silica in TEM images, and led to over two orders of magnitude increase in the reactivity of the silica spheres for 1-propanol dehydration. Raman spectroscopy and TEM confirmed that the dispersed titania was stable to calcination in dry air at 973 K or to heating under a vacuum of 2 {times} 10{sup {minus}7} Torr up to 1,058 K. However, under alcohol dehydration reaction conditions, the dispersed titania transformed into crystals of anatase, 3 nm in diameter. On Cabosil-fumed silica, on the other hand, a similar preparation resulted in a titania loading (per square meter) that was only 7% of that seen on the silica spheres. Higher loadings caused the appearance of bands due to crystalline TiO{sub 2} (anatase) in the Raman spectra. The lower monolayer capacity on Cabosil silica can be correlated with the presence of singly bound hydroxyls as seen by IR. The Stober spheres on the other hand show hydroxyl bands that show significant hydrogen bonding.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5757118
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 131:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
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36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALCOHOLS
CALCINATION
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COATINGS
DECOMPOSITION
DEHYDRATION
DEPOSITION
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
HYDROXY COMPOUNDS
INFRARED RADIATION
LASER SPECTROSCOPY
MICROSCOPY
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PROPANOLS
PYROLYSIS
QUANTITY RATIO
RADIATIONS
RAMAN SPECTROSCOPY
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
SURFACE COATING
SYNTHESIS
THERMOCHEMICAL PROCESSES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY