A study by in situ laser Raman spectroscopy of VPO catalysts for n-butane oxidation to maleic anhydride. 1. Preparation and characterization of pure reference phases
- Ecole Centrale de Lyon, Ecully (France)
- CNRS, Villeurbanne (France)
An in situ laser Raman spectroscopy (LRS) cell has been constructed in order to study the evolution of the local structure of the vanadium phosphate catalysts for n-butane oxidation to maleic anhydride in catalytic conditions. The LRS cell is described with the on line disposal for detection of the evolving gases. The first issue concerns the preparation and the physicochemical characterization of the reference phases of the VPO system: (VO){sub 2}P{sub 2}O{sub 7}, {alpha}{sub 11}, {beta}, {gamma}, and {delta} VOPO{sub 4}. Their purity was controlled by X-ray diffraction and {sup 31}P and {sup 51}V solid NMR and their LRS spectra were studied in the 800-1,200 cm{sup {minus}1} range characteristic of the P-0 and V-O bonds. Among these phases only {delta} VOPO{sub 4} is partly transformed (into {alpha}{sub 11} VOPO{sub 4}) in the catalytic conditions. From the evolution of their respective Raman spectra with temperature and with conditions of hydration, new proposals for the structure of {gamma} VOPO{sub 4} are given. They are in agreement with the solid state NMR data. Raman spectra of the phases exhibit features specific enough to allow identification of the different VPO structures.
- OSTI ID:
- 6977573
- Journal Information:
- Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 134:1; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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ALKANES
ANHYDRIDES
BUTANE
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL PREPARATION
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
HYDROCARBONS
INTERMEDIATE MASS NUCLEI
ISOTOPES
LASER SPECTROSCOPY
LIGHT NUCLEI
MAGNETIC RESONANCE
MORPHOLOGY
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
PHOSPHATES
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHYSICAL PROPERTIES
RAMAN SPECTROSCOPY
RESONANCE
SCATTERING
SPECTROSCOPY
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM 51
VANADIUM COMPOUNDS
VANADIUM ISOTOPES
VANADIUM PHOSPHATES
X-RAY DIFFRACTION