Activated formation of a H-CO complex on Ni/Al sub 2 O sub 3 catalysts
- Univ. of Colorado, Boulder (USA)
Temperature-programmed desorption (TPD) of coadsorbed H{sub 2} and CO was used to detect the presence of a H-CO complex on a Ni/Al{sub 2}O{sub 3} catalysts, and isotope labeling was used to separate adsorbed species that were present on separate sites. The surface complex was shown to be present on the Al{sub 2}O{sub 3} support and to have the stoichiometry of methoxy (H/CO = 3). The complex formed through an activated process carried out at 385 K. Much more CO and H{sub 2} adsorbed at 385 K than at 300 K. Both CO and H{sub 2} adsorbed on the Ni, after which they transferred to the Al{sub 2}O{sub 3}; activated adsorption of H{sub 2} appeared to limit the transfer. At high coverage, a new CO desorption state was detected on the Ni surface. During TPD following CO and H{sub 2} adsorption at 385 K, decomposition of the complex limited formation of CO and H{sub 2}. During temperature-programmed reaction (TPR), the two CH{sub 4} peaks previously reported are shown to result from two forms of adsorbed CO: on the Ni surface and on the Al{sub 2}O{sub 3} as a complex. Hydrogenation of the complex is limited by its decomposition, which is slower than CO hydrogenation on Ni. Good agreement is shown between TPD and TPR.
- OSTI ID:
- 6960504
- Journal Information:
- Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 115:1; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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010408* -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL REACTIONS
COMPLEXES
CONTROL
DECOMPOSITION
DESORPTION
ELEMENTS
HYDROCARBONS
HYDROGENATION
METALS
METHANATION
METHANE
NICKEL
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
STOICHIOMETRY
SURFACE PROPERTIES
SYNTHESIS
TEMPERATURE CONTROL
TRANSITION ELEMENTS