Characterization of supported cobalt and cobalt-rhodium catalysts. II. Temperature-programmed reduction and oxidation of Co/TiO/sub 2/ and Co-Rh/TiO/sub 2/
The reduction-oxidation behavior of cobalt supported on titania has been studied by temperature-programmed reduction and oxidation (TPR and TPO). Cobalt, supported on titania, was rather easy to oxidize and subsequently hard to reduce. Because of this ease of oxidation, during passivation a considerable amount of cobalt was oxidized. The reduction of Co/sub 3/O/sub 4/ supported on TiO/sub 2/ proceeded in two stages, namely a primary reduction of Co/sub 3/O/sub 4/ to CoO and a subsequent reduction of CoO to Co. The addition of rhodium to cobalt caused the resulting bimetallic catalyst to be more difficult to oxidize, while the reducibility of the catalyst depended on the oxidation temperature. When oxidized below 800 K, the reduction proceeded at low temperatures, indicating that Rh/sub 2/O/sub 3/ was present in the surface of the bimetallic particles. To complete the oxidation, however, higher temperatures were needed and under these circumstances cobalt rhodate, CoRh/sub 2/O/sub 4/, was formed. The reduction behavior of a thoroughly oxidized catalyst revealed that only cobalt oxide was exposed, demonstrating that oxygen-induced surface enrichment of cobalt had occurred.
- Research Organization:
- Eindhoven Univ. of Technology (Netherlands)
- OSTI ID:
- 5353306
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 97:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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400201* -- Chemical & Physicochemical Properties
ALCOHOLS
BIMETALS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
COBALT
COBALT COMPOUNDS
COBALT OXIDES
ELEMENTS
FISCHER-TROPSCH SYNTHESIS
HYDROXY COMPOUNDS
MEASURING METHODS
METALS
METHANOL
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REDUCTION
REFRACTORY METAL COMPOUNDS
RHODIUM
RHODIUM COMPOUNDS
RHODIUM OXIDES
SURFACE PROPERTIES
SYNTHESIS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS