A high-resolution electron microscopy investigation of TiO sub 2 (B)-supported vanadium oxide catalysts

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(90)90063-P· OSTI ID:5531437

Wallenberg, L R; Sanati, M; Andersson, A ^[1]

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1. Lund Institute of Technology (Sweden)

TiO{sub 2}(B) crystals were found to be isomorphic with those of its precursor, K{sub 2}TI{sub 4}O{sub 9}. The former crystals had a large number of facetted voids, 3-30 nm, formed as a result of the removal of potassium and water in preceding hydrolysis and calcination steps, respectively. TiO{sub 2}(B)-supported vanadium oxide catalysts with loadings in the range 0.25-10 theoretical layers were prepared by impregnation of the support with an oxalic acid solution of NH{sub 4}VO{sub 3} followed by calcination in air. HREM micrographs of catalysts with a low vanadium loading, recorded using a low electron-dose imaging technique, showed that the surfaces, in the initial stage, were without any anomalous surface structure. This observation may be due to a similar structure of the support and the deposited vanadia phase. At high vanadium loadings, both amorphous and crystalline particles were seen, in agreement with the features revealed by the use of IR spectroscopy. For catalysts with low vanadium loadings, the IR difference spectra showed the presence of tetrahedrally coordinated V{sup 4+} and V{sub 5+} species. In a fully converged electron beam, reduction of the support and the vanadia phases occurred, resulting in the formation of small crystallites. The catalysts were used for the oxidation of toluene to benzaldehyde. However, contrary to what has been observed for the ammoxidation producing benzonitrile, no enhanced catalytic properties, in comparison with those of crystalline V{sub 2}O{sub 5}, were obtained using TiO{sub 2}(B) as support.

• OSTI ID: 5531437
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 126:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALDEHYDES
ALKYLATED AROMATICS
AROMATICS
BENZALDEHYDE
CALCINATION
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
DECOMPOSITION
ELECTRON MICROSCOPY
HYDROCARBONS
HYDROLYSIS
IMPREGNATION
INFRARED SPECTRA
LOADING RATE
LYSIS
MICROSCOPY
MICROSTRUCTURE
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE TESTING
PYROLYSIS
REDUCTION
SOLVOLYSIS
SPECTRA
SURFACE PROPERTIES
SYNTHESIS
TESTING
THERMOCHEMICAL PROCESSES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TOLUENE
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES