Structural determination of supported V[sub 2]O[sub 5]-WO[sub 3]/TiO[sub 2] catalysts by in situ Raman spectroscopy and x-ray photoelectron spectroscopy

Journal Article · Thu Nov 28 00:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100177a059· OSTI ID:6837338

Vuurman, M A; Wachs, I E ^[1]; Hirt, A M ^[2]

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1. Lehigh Univ., Bethlehem, PA (United States)
2. Materials Research Labs., Inc., Fords, NJ (United States)

A series of supported V[sub 2]O[sub 5]/TiO[sub 2], WO[sub 3]/TiO[sub 2] and V[sub 2]O[sub 5]-WO[sub 3]/TiO[sub 2] samples have been characterized by means of Raman spectroscopy under ambient as well as in situ dehydrated conditions and by x-ray photoelectron spectroscopy. Under ambient conditions two different hydrated surface vanadia species and crystalline V[sub 2]O[sub 5] have been identified in V[sub 2]O[sub 5]/TiO[sub 2] as a function of surface coverage. Under dehydrated conditions two types of surface vanadium oxide species are found in V[sub 2]O[sub 5]/TiO[sub 2] samples: a highly distorted vanadium oxide species and a moderately distorted vanadium oxide species, and their relative concentration is a function of the vanadia surface coverage. Under ambient conditions tetrahedrally coordinated surface tungsten oxide species, octahedrally coordinated surface polytungstate species, and crystalline WO[sub 3] are observed in WO[sub 3]/TiO[sub 2] samples as a function of surface coverage. Dehydration converts all the two-dimensional tungsten oxide species into a highly distorted octahedrally coordinated structure. The molecular structures of the V[sub 2]O[sub 5]-WO[sub 3]TiO[sub 2] mixed samples are not influenced by the sequence of impregnation of the starting materials. Under ambient conditions and low vanadia coverage, the hydrated surface vanadium oxide species undergo a structural change due to the acidic nature of tungsten oxide species. Crystalline V[sub 2]O[sub 5] and crystalline WO[sub 3] are not influenced by the presence of the other metal oxides. Under dehydrated conditions, both the highly distorted surface vanadium oxide species and the octahedrally coordinated surface tungsten oxide species do not appear to be influenced by each other at all loadings. The only influence observed in this study is that the moderately distorted vanadium oxide species becomes more abundant in the presence of tungsten oxide.

• OSTI ID: 6837338
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:24; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
TITANIUM OXIDES
MOLECULAR STRUCTURE
TUNGSTEN OXIDES
VANADIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
EXPERIMENTAL DATA
HYDRATES
PHOTOELECTRON SPECTROSCOPY
RAMAN SPECTROSCOPY
X-RAY SPECTROSCOPY
CHALCOGENIDES
DATA
ELECTRON SPECTROSCOPY
INFORMATION
LASER SPECTROSCOPY
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SPECTROSCOPY
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
VANADIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties