Preparation and characterization of copper-thorium oxide catalysts. 2. ESR study of copper(II) ion pairs and correlation with the selective hydrogenation of isoprene
- Universite des Sciences et Techniques de Lille Flandres-Artois, Villeneuve d'Ascq (France)
- Universite Libanaise (France)
CuThO oxides prepared with an atomic ratio Cu/Th > 0.01 were extensively studied by electron spin resonance (ESR) and X-ray photoelectron spectroscopies (XPS). The XPS analysis of these solids showed that the thoria surface is enriched with copper. The X-ray diffraction patterns for Cu/Th > 0.25 revealed two distinct phase systems, ThO{sub 2} and CuO. ESR studies evidenced two signals of monomeric Cu{sup 2+} species (M{sub 1} and M{sub 2}) and a well-resolved D signal ({Delta}m{sub 2} = 1) of Cu{sup 2+} ion pairs, accompanied by a weak signal at half magnetic field intensity ({Delta}m{sub s} = 2). From the {Delta}m{sub 2} = 2/{Delta}m{sub s} = 1 intensities ratio and from the fine splitting observed for the D signal, the distance between the Cu{sup 2+} ions in the pair have been calculated. These copper-thorium oxide catalysts are active for selective hydrogenation of isoprene at 373 K after reduction of the oxide phase at 523 K. A correlation between this activity and the relative intensities of M{sub 1}, M{sub 2} and D signals was established.
- OSTI ID:
- 5470331
- Journal Information:
- Chemistry of Materials; (United States), Journal Name: Chemistry of Materials; (United States) Vol. 2:5; ISSN CMATE; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
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ACTINIDE COMPOUNDS
CATALYSTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DIENES
DIFFRACTION
ELECTRON SPECTROSCOPY
ELECTRON SPIN RESONANCE
HYDROCARBONS
HYDROGENATION
ION PAIRS
ISOPRENE
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
POLYENES
RESONANCE
SCATTERING
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
THORIUM COMPOUNDS
THORIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION