Kinetics and mechanism of carbon monoxide methanation over silica-supported nickel catalysts

Journal Article · Tue Nov 01 04:00:00 EST 1983 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(83)90084-2· OSTI ID:5403739

Dalmon, J A; Martin, G A

The rate, r, of CO hydrogenation into methane over Ni/SiO/sub 2/ catalysts is shown to vary in a complex way with temperature and pressure. The true activation energy, E/sub 0/, calculated from the Temkin relation (apparent activation energy against the order to CO and extrapolation to zero order), corresponds to that of the hydrogenation of carbon deposited on the surface from the CO dissociation reaction. It is deduced that the active intermediate is the surface carbon, and the rate-determining step the hydrogenation of this intermediate. Kinetic data are qualitatively accounted for assuming the following equation r = ke/sup -E/sub 0//RT/P/sub H/sub 2//(1 - theta/sub CO/)/sup W/ theta/sub CO/ is the surface coverage in nondissociated inactive adsorbed CO molecules which are considered as the most abundant species present on the surface. The parameter W is probably very large (W = 13 on the basis of data of CO + H/sub 2/ over NI-Cu/SiO/sub 2/). In this equation, the term (1 - theta/sub CO/)/sup W/ represents the probability of having W adjacent Ni atoms free from inactive adsorbed CO. This ensemble should be considered as the active site and is covered with one active monocarbon adspecies. 28 references, 6 figures, 1 table.

• Research Organization: Institut de Recherches sur la Catalyse, CNRS, Villeurbanne, France
• OSTI ID: 5403739
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 84:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

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ACTIVATION ENERGY
ALKANES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHROMATOGRAPHY
CORRELATIONS
DATA
ELEMENTS
EMISSION SPECTROSCOPY
ENERGY
EXPERIMENTAL DATA
FLUIDS
GAS CHROMATOGRAPHY
GASES
HELIUM
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN
INERT ATMOSPHERE
INFORMATION
KINETICS
LOW PRESSURE
MATHEMATICAL MODELS
METALS
METHANATION
METHANE
MINERALS
NICKEL
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
QUANTITY RATIO
RARE GASES
REACTION KINETICS
SAMPLE PREPARATION
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS GAS
TEMPERATURE DEPENDENCE
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
TIME DEPENDENCE
TRANSITION ELEMENTS
YIELDS