Surface characterization of zirconia-coated alumina and silica carriers

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1997.1671· OSTI ID:539467

Damyanova, S ^[1]; Grange, P; Delmon, B ^[2]

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1. Institute of Catalysis, Sofia (Bulgaria)
2. Universite Catholique de Louvain, Louvain-la-Neuve (Belgium)

Silica- and alumina-supported zirconia samples have been prepared by impregnation of the supports with a solution of zirconium alkoxide (n-propoxide) in n-propanol containing ZrO{sub 2} in the ranges 1.2-28.6 and 2.2-23.2 wt%, respectively. The samples were characterized by the SBET method, XRD, XPS, and FTIR. The x-ray diffraction showed that zirconia on silica was amorphous for all concentrations of ZrO{sub 2}. Zirconia on alumina was amorphous up to 17.1 wt% ZrO{sub 2}; beyond this value crystallites were formed. The increase in the XPS IZr 3d/ISi 2p indicates that ZrO{sub 2} appears as a monolayer on silica near the theoretical monolayer coverage (about 28.6 wt%), whereas for alumina-supported zirconia samples the monolayer is formed at lower ZrO{sub 2} content (between 12.9 and 17.1 wt%). It was observed by pyridine adsorption that the strong Lewis acid sites on alumina decreased after deposition of zirconia. However, the number of Lewis acid sites on silica-supported zirconia samples, evoked by an increase of the positive charge on Zr atoms compared to pure zirconia, increases with increasing ZrO{sub 2} content. Some Bronsted acid sites were detected on ZrO{sub 2}/SiO{sub 2} samples due to the slightly higher electron density on the oxygen associated with Si atoms detected by XPS. 42 refs., 8 figs., 4 tabs.

• OSTI ID: 539467
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 168; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
ALUMINIUM OXIDES
ELECTRON DENSITY
INFRARED SPECTRA
PYRIDINE
SILICA
SURFACE PROPERTIES
X-RAY DIFFRACTION
ZIRCONIUM OXIDES