Characterization of silica- and alumina-supported vanadia catalysts using temperature programmed reduction

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1217· OSTI ID:6858908

Koranne, M M; Goodwin, Jr, J G; Marcelin, G ^[1]

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1. Univ. of Pittsburgh, PA (United States)

Supported and bulk vanadia catalysts are important catalysts for the partial oxidation of hydrocarbons. The nature of the vanadia-support interaction for silica and alumina-supported V[sub 2]O[sub 5] catalysts was investigated using temperature programmed reduction (TPR), temperature programmed oxidation, and solid-state [sup 51]V NMR. Solid-state [sup 51]V NMR for the V[sub 2]O[sub 5]/SiO[sub 2] catalysts indicated the presence of microcrystalline bulk-like vanadia species even at low vanadia loadings. Temperature programmed reduction of V[sub 2]O[sub 5]/SiO[sub 2] exhibited multiple peaks. It is suggested that the low temperature peak is due to reduction of surface vanadia. This appears to be the case also for bulk V[sub 2]O[sub 5]. [sup 51]V NMR indicated that bulk-like vanadia species are present for V[sub 2]O[sub 5]/Al[sub 2]O[sub 3] catalysts only at high vanadia loadings. Vanadia was more highly dispersed on alumina than on silica as evidenced by NMR and TPR. The two lowest temperature TPR peaks appear to be related to the reduction of surface vanadia on V[sub 2]O[sub 5]/Al[sub 2]O[sub 3]. It was found that for V[sub 2]O[sub 5]/Al[sub 2]O[sub 3] the average oxidation state of V after reduction to 900[degrees]C is consistent with the stoichiometry V[sup +5] [yields] V[sup +4], whereas the V[sub 2]O[sub 5]/SiO[sub 2] catalysts exhibited 70% reduction of the V[sub 2]O[sub 5] to V[sub 2]O[sub 3] as did bulk V[sub 2]O[sub 5]. The amount of surface vanadium as determined by TPR correlates reasonably to the amount of tetrahedral V found by NMR. It is concluded that TPR provides an excellent means by which vanadia dispersion can be estimated on supported vanadia catalysts. 32 refs., 5 figs., 6 tabs.

• OSTI ID: 6858908
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 148:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
100200 -- Synthetic Fuels-- Production-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
MAGNETIC RESONANCE
MINERALS
NUCLEAR MAGNETIC RESONANCE
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
REDUCTION
RESONANCE
SILICA
SILICON COMPOUNDS
SILICON OXIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES