Distribution of Mo oxidation states in reduced Mo/Al{sub 2}O{sub 3} catalysts
- Univ. of Pittsburgh, PA (United States)
It is well known that given the appropriate reduction pretreatment Mo/Al{sub 2}O{sub 3} catalysts can be active for various reactions (isomerization, metathesis, hydrogenation and hydrogenolysis). This behavior suggests that the activity is associated with a specific Mo oxidation state. The objective of this study is to determine the distribution of Mo oxidation states is reduced Mo/Al{sub 2}O{sub 3} catalysts by ESCA and to correlate the results with catalytic activity for various probe reactions. The results showed that Mo oxidation states ranging from +6 to 0 are produced on reduction between 200{degrees}C and 900{degrees}C. The catalytic activity of the reduced Mo/Al{sub 2}O{sub 3} catalysts for propene hydrogenation, benzene hydrogenation and propane hydrogenolysis was measured as a function of the reduction temperature. The variation of catalytic activity of the reduced catalysts was compared with the distribution of Mo oxidation states obtained from ESCA. The results indicated that Mo oxidation states {<=}+4 are required for propene hydrogenation. Benzene hydrogenation and propane hydrogenolysis required a more severe reduction pretreatment; the catalytic activity correlated with the change in the abundance of Mo metal. This suggested that Mo metal is the most active species for these reactions.
- OSTI ID:
- 141314
- Report Number(s):
- CONF-930304--
- Country of Publication:
- United States
- Language:
- English
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