Reactivity of CO on vanadium-promoted rhodium catalysts as studied with transient techniques
- Eindhoven Univ. of Technology (Netherlands)
The effect of vanadium promotion on the kinetics of CO methanation on silica-based rhodium catalysts was probed. Transient model experiments employing temperature-programmed surface reaction spectroscopy and pulse surface reaction rate analysis were used to unravel changes in rates of elementary reaction steps. CO dissociation is the rate-limiting step in the overall methanation reaction. The rate of CO dissociation is found to be enhanced by vanadium. The activation energy is lowered from 90 kJ/mol for Rh/SiO{sub 2} to 65 kJ/mol for the promoted catalyst. The activation energy for CO dissociation is not dependent on the hydrogen partial pressure, while it is a strong function of the CO surface coverage. CO adsorption at temperatures above 250 C results in very reactive surface carbonaceous intermediates. Even at {minus}15 C methane formation was observed upon hydrogenation. This reactive surface carbon can be incorporated in higher hydrocarbons. This process is favored by vanadium promotion.
- OSTI ID:
- 6984950
- Journal Information:
- Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 134:1; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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ACTIVATION ENERGY
ADSORPTION
ALCOHOLS
ALKANES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CONTROL
DISSOCIATION
ELEMENTS
ENERGY
FLUIDS
GASES
HYDROCARBONS
HYDROGEN
HYDROGENATION
HYDROXY COMPOUNDS
KINETICS
METALS
METHANATION
METHANE
METHANOL
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PLATINUM METALS
PROMOTERS
REACTION KINETICS
RHODIUM
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SURFACE PROPERTIES
SYNTHESIS
SYNTHESIS GAS
TEMPERATURE CONTROL
TRANSITION ELEMENTS
VANADIUM