CO isotopic exchange reaction over Rh/Al/sub 2/O/sub 3/: nondissociative exchange on metallic Rh sites
Journal Article
·
· J. Phys. Chem.; (United States)
The isotopic exchange reaction /sup 12/C/sup 18/O + /sup 13/C/sup 16/O ..-->.. /sup 12/C/sup 16/O + /sup 13/C/sup 18/O has been studied over alumina-supported rhodium catalysts between 300 and 470 K. For a 2.2 wt % Rh/Al/sub 2/O/sub 3/ catalyst containing both metallic Rh/sub x//sup 0/ sites and Rh/sup I/ sites, the onset of the CO isotopic exchange reaction is observed at 373 K, and an activation energy of 10.8 kcal/times/mol/sup /minus/1/ is estimated. In the same temperature range, no CO disproportionation/dissociation reactions are observed. The rate of isotopic exchange per Rh site over 0.2% Rh/Al/sub 2/O/sub 3/ is found to be slower by a factor of 7 than that over 2.2% Rh/Al/sub 2/O/sub 3/, due to the low relative population of metallic Rh sites compared to Rh/sup I/ sites on the 0.2% Rh/Al/sub 2/O/sub 3/ surfaces. It is proposed that the CO isotopic exchange proceeds via a nondissociative mechanism on the metallic Rh sites of the Rh catalysts and that the exchange reaction will not occur on Rh/sup I/ sites. Mass spectrometric, chemisorption, and IR spectroscopic measurements have been employed.
- Research Organization:
- Univ. of Pittsburgh, PA (USA)
- OSTI ID:
- 6255262
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 92:21; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
ACTIVATION ENERGY
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON 12
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
DATA
ELEMENTS
ENERGY
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
INFORMATION
INFRARED SPECTRA
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
MASS SPECTROSCOPY
MEDIUM TEMPERATURE
METALS
NUCLEI
NUMERICAL DATA
OXIDES
OXYGEN 16
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PLATINUM METALS
RHODIUM
SEPARATION PROCESSES
SORPTION
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
TRANSITION ELEMENTS
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
ACTIVATION ENERGY
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON 12
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
DATA
ELEMENTS
ENERGY
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
INFORMATION
INFRARED SPECTRA
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
MASS SPECTROSCOPY
MEDIUM TEMPERATURE
METALS
NUCLEI
NUMERICAL DATA
OXIDES
OXYGEN 16
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PLATINUM METALS
RHODIUM
SEPARATION PROCESSES
SORPTION
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
TRANSITION ELEMENTS