Carbon formation and CO methanation on silica-supported nickel and nickel-copper catalysts in CO + H{sub 2} mixtures
- Universidade do Minho, Guimaraes (Portugal)
- Haldor Topsoe Research Labs., Lyngby (Denmark)
The steady-state rates of simultaneous carbon formation and methanation on silica-supported nickel and nickel-copper catalysts in CO + H{sub 2} gas mixtures have been measured in the partial pressure range 10-30 kPa and the temperature range 583-873 K. The steady-state kinetic results for carbon formation can be explained by a model previously used for carbon formation in pure CO gas, but modified to take into account the influence of hydrogen. Comparisons between the results for Ni/SiO{sub 2}, Ni{sub 0.99}Cu{sub 0.01}/SiO{sub 2}, and Ni{sub 0.75}Cu{sub 0.25}/SiO{sub 2} show that the specific rate of carbon formation is increased when 1 at.% of Cu is added to a nickel catalyst, but that the rate decreases when the Cu content is increased to 10 at.%, and that no carbon formation is seen for the Ni{sub 0.75}Cu{sub 0.25}/SiO{sub 2} catalyst. The addition of a small amount of Cu, on the other hand, decreases the methanation rate while at higher Cu contents the rate goes up again and a maximum is observed at about 7 at.% Cu. Thus a simple ensemble model cannot explain the influence of copper on the rate of carbon formation or methanation. Comparison of carbon formation and methanation rates for the Ni/SiO{sub 2} and the Ni{sub 0.99}Cu{sub 0.01}/SiO{sub 2} catalysts indicates that the two reactions have different rate-controlling steps and that the carbon formation influences the methanation rate mainly through poisoning of the catalysts. 27 refs., 9 figs., 5 tabs.
- OSTI ID:
- 263695
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 158; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
40 CHEMISTRY
CARBON
CARBON MONOXIDE
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
COPPER
LOW PRESSURE
METHANATION
NICKEL
PARTIAL PRESSURE
PRESSURE DEPENDENCE
SILICA
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K