Reduction behavior and metathesis activity of WO sub 3 /Al sub 2 O sub 3 catalysts II. The role of W(V) - an EPR investigation

Journal Article · Thu Jun 01 00:00:00 EDT 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90357-6· OSTI ID:6469663

Gruenert, W; Feldhaus, R; Anders, K ^[1]; Moerke, W ^[2]

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1. Central Institute of Organic Chemistry, Leipzig (German Democratic Republic)
2. Technical Univ., Merseburg (German Democratic Republic)

WO{sub 3}/Al{sub 2}O{sub 3} catalysts of varying WO{sub 3} contents (4-10 wt%) were subjected to various thermal and reductive treatments, used in the metathesis of propene (573 K, 0.1 MPa), and investigated by EPR spectroscopy. Three characteristics EPR signals were obtained, two of which were assigned to W(V) in different distorted octahedral sites. The third was due to a Mo trace impurity. Tetrahedral sites expected to be predominant on the surface were not detected by EPR probably due to their low reducibility. It was found that Mo impurities may affect the EPR spectra of such systems considerably. By evaluation of spin concentrations it was shown that less than 1% of the tungsten present was reduced to W(V). This percentage was increased by a treatment with dry HCl at 295 K, which was accompanied by a simplification of the spectrum, but it was concluded that the HCl treatment does not unambiguously prove the presence of W(V) paired structures in this system. By analysis of spin concentrations and metathesis activities it was demonstrated that W(V) is not relevant to the metathesis reaction but should be considered by a by-product of the activation processes, which probably involve W(VI) as an active site precursor.

• OSTI ID: 6469663
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 117:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMICAL STATE
ELECTRON SPIN RESONANCE
ELEMENTS
HYDROCARBONS
HYDROCHLORIC ACID
HYDROGEN COMPOUNDS
IMPURITIES
INORGANIC ACIDS
ISOMERIZATION
MAGNETIC RESONANCE
METALS
MOLYBDENUM
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PROPYLENE
REDUCTION
REFRACTORY METAL COMPOUNDS
RESONANCE
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN COMPOUNDS
TUNGSTEN OXIDES