Segregation of vanadia-molybdena catalysts in the course of oxidation and reduction processes
Journal Article
·
· J. Catal.; (United States)
OSTI ID:6811694
Segregation of vanadia-molybdena catalysts in the course of oxidation and reduction processes was determined by X-ray microprobe analyses of 10 3< and 30 3< MoO/sub 3//V/sub 2/O/sub 5/ samples prepared by fusion at 700/sup 0/C. The same areas of the crystallites were analyzed as prepared, after air-oxidation at 450/sup 0/C, and after reduction with benzene at 450/sup 0/C. Homogeneity remained unchanged during treatment, but the molybdenum/vanadium ratio of the outer crystallite layers decreased during oxidation and increased during reduction. If the concentration of molybdenum trioxide in the crystallite interior during oxidation exceeds its solubility limit in vanadium pentoxide, it would form V/sub 9/Mo/sub 6/O/sub 40/, which would first be redissolved on reduction. As reduction continues, molybdenum would migrate to the surface faster than vanadium and would form V/sub 9/Mo/sub 6/O/sub 40/ when its surface concentration exceeds the solubility limit. Such processes lead to the phase segregration of vanadia-molybdena catalysts observed during benzene oxidation to maleic anhydride.
- Research Organization:
- Jagillonian Univ., Krakow
- OSTI ID:
- 6811694
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 57:2; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AROMATICS
BENZENE
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
HYDROCARBONS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REDUCTION
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AROMATICS
BENZENE
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
HYDROCARBONS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REDUCTION
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES