Alkali promotion of nickel catalysts for carbon monoxide methanation

Journal Article · Sun Jan 01 04:00:00 EST 1978 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(78)90232-4· OSTI ID:5358774

Huang, C P; Richardson, J T

Differential reactor studies of carbon monoxide hydrogenation have been carried out on a series of 8 percent Ni/SiO/sub 2/--Al/sub 2/O/sub 3/ catalysts in which the supports have been impregnated with increasing amounts of sodium. Magnetic measurements show that the extent of reduction and the nickel crystallite size are not influenced by the sodium on the support. Hydrogen adsorption measurements reveal that the exposed surfaces are in agreement with the crystallite sizes and are not significantly poisoned by the alkali. The turnover number increases with sodium content and passes through a maximum at 0.3 percent Na with an enhancement by a factor of 6. Kinetic data best fit the surface reaction mechanism for which rate = kK(/sub CO/P/sub CO/P/sup /sup 1///sub 2///sub H//(1 + K/sub CO/P/sub CO/)/sup 2/. For K/sub CO/, the pre-exponential factor and heat of adsorption are unchanged by Na, but the parameters of k are not. The pre-exponential factor passes through a maximum and the activation energy decreases as the Na level increases. These results are best explained by an initial decrease in acidity, which keeps the nickel surface clean, followed by a poisoning via direct metal interaction or support modification by the alkali.

• Research Organization: Univ. of Houston, TX
• OSTI ID: 5358774
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 51:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

090121* -- Hydrocarbon Fuels-- Chemical Synthesis-- (1976-1989)
10 SYNTHETIC FUELS
ALKALI METALS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELEMENTS
KINETICS
METALS
METHANATION
NICKEL
OXIDES
OXYGEN COMPOUNDS
PROMOTERS
REACTION KINETICS
SILICON COMPOUNDS
SILICON OXIDES
SODIUM
TRANSITION ELEMENTS