In situ Raman spectroscopy of supported chromium oxide catalysts: Reactivity studies with methanol and butane

Journal Article · Thu Aug 22 04:00:00 EDT 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp960543o· OSTI ID:380780

Weckhuysen, B M; Wachs, I E ^[1]

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1. Lehigh Univ., Bethlehem, PA (United States)

The interactions of methanol and butane with supported chromium oxide catalysts under oxidizing and reducing conditions were studied by in situ Raman spectroscopy as a function of the specific oxide support (Al{sub 2}O{sub 3}, ZrO{sub 2}, TiO{sub 2}, SiO{sub 2}, Nb{sub 2}O{sub 5}, 3% SiO{sub 2}/TiO{sub 2}, 3% TiO{sub 2}/SiO{sub 2}, and a physical mixture of SiO{sub 2} and TiO{sub 2}) and chromium oxide loading (1-6 wt% CrO{sub 3}). Two surface chromium oxide species were observed on the TiO{sub 2}, ZrO{sub 2}, Al{sub 2}O{sub 3}, 3% SiO{sub 2}/TiO{sub 2}, and a physical mixture of SiO{sub 2} and TiO{sub 2} surfaces: a monomeric species (characterized by a Cr=O stretching frequency at nearly 1030 cm{sup -1}) and a polymeric species (possessing a Cr=O stretching frequency at nearly 1005-1010 cm{sup -1} and a Cr-O-Cr bending mode at nearly 880 cm{sup -1}). The SiO{sub @} and 3% TiO{sub 2}/SiO{sub 2} surfaces possess only the monomeric species. The extent of reduction of the surface chromium oxide species, reflected by the decrease in the Raman intensity of the Cr=O bonds, demonstrates that the polymeric surface chromium oxide species is more easily reducible than the monomeric chromium oxide species on the same support. The extent of reduction of the surface chromium oxide species strongly depends on the specific oxide support (3% TiO{sub 2}/SiO{sub 2} = 3% SiO{sub 2}/TiO{sub 2} = (SiO{sub 2} + TiO{sub 2}) = TiO{sub 2} > ZrO{sub 2}). 30 refs., 9 figs., 1 tab.

• DOE Contract Number: FG02-93ER14350
• OSTI ID: 380780
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 34 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ACTIVATION ENERGY
ALUMINIUM OXIDES
BUTANE
CATALYST SUPPORTS
CATALYSTS
CHROMIUM OXIDES
METHANOL
NIOBIUM OXIDES
RAMAN SPECTRA
REDUCTION
TITANIUM OXIDES
ZIRCONIUM OXIDES