Surface science investigation of the water-gas shift reaction on Cu(111)
The authors have studied the kinetics of the water-gas shift reaction on a clean Cu(111) single-crystal surface using an apparatus which allows rapid transfer of the catalyst between a microreactor and an ultrahigh-vacuum chamber for surface preparation and postreaction surface analyses (AES), XPS, LEED). At 10 Torr H/sub 2/O, 26 Torr CO, and 612 K, the reaction proceeds with an activation energy of 17 kcal/mole and reaction orders in H/sub 2/O and CO pressures of zero and 0.5-1.0, respectively. The surface appears completely metallic and relatively free of adsorbed species in postreaction analysis, even when heavily preoxidized. The kinetics compare favorably with data for high-surface-area Cu/ZnO or Cu-based catalysts, indicating that metallic Cu is the active ingredient in these. The rate is limited by dissociative adsorption of water under their conditions. The authors were unable to produce significant coverages of oxygen species on Cu(111) by dosing pure H/sub 2/O at 10 Torr and 500-650 K. The mechanism is discussed in light of surface science measurements on Cu surfaces. The Cu(111) surface was also dosed with Zn from aqueous solution, and the resulting ZnO/sub x/Cu(111) surfaces were tested for activity as water-gas shift catalysts. No marked changes in activity compared to clean Cu(111) were observed. A new method for increasing gas chromatographic sensitivities for low sampling pressures (< 1 atm) is also described. 46 references.
- Research Organization:
- Indiana Univ., Bloomington
- OSTI ID:
- 5450008
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 104:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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10 SYNTHETIC FUELS
ACTIVATION ENERGY
AMMONIA
AUGER ELECTRON SPECTROSCOPY
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMATOGRAPHY
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COPPER
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ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
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GAS CHROMATOGRAPHY
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN PRODUCTION
KINETICS
METALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
REACTION KINETICS
SCATTERING
SEPARATION PROCESSES
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS
WATER
WATER GAS PROCESSES
X-RAY SPECTROSCOPY
ZINC