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), Vol. 97:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
01 COAL, LIGNITE, AND PEAT
10 SYNTHETIC FUELS
CATALYSTS
CHEMICAL PROPERTIES
COBALT
OXIDATION
REDUCTION
FISCHER-TROPSCH SYNTHESIS
RHODIUM
BIMETALS
CATALYST SUPPORTS
CATALYTIC EFFECTS
COBALT OXIDES
MEASURING METHODS
METHANOL
RHODIUM OXIDES
SURFACE PROPERTIES
SYNTHESIS
TITANIUM OXIDES
ALCOHOLS
CHALCOGENIDES
CHEMICAL REACTIONS
COBALT COMPOUNDS
ELEMENTS
HYDROXY COMPOUNDS
METALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REFRACTORY METAL COMPOUNDS
RHODIUM COMPOUNDS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
010408 - Coal
Lignite
& Peat- C1 Processes- (1987-)
090221 - Alcohol Fuels- Chemical Synthesis- (1976-1989)