Infrared and x-ray photoelectron spectroscopy study of CO and CO/sub 2/ on Pt/CeO/sub 2/
The adsorptions of CO and CO/sub 2/ on Pt/CeO/sub 2/ were studied by infrared and X-ray photoelectron spectroscopy. A heterogeneous distribution of linearly adsorbed CO on Pt at terrace, step, and corner sites was proposed based on changes in the absorption of the CO infrared stretching frequencies from 2084 to 2060 cm/sup -1/ upon heating under vacuum from 300 to 473 K. Pretreatment of the sample with O/sub 2/ above 373 K lead to a blue-shifted peak at 2091 cm/sup -1/, interpreted as arising from CO adsorbed on Pt with an atom of oxygen at a neighboring site, and a new peak at 2131 cm/sup -1/, assigned to CO coadsorbed with an oxygen atom on the same Pt atom. Adsorption of CO/sub 2/ at room temperature resulted in the appearance of an IR band at 2065 cm/sup -1/, assigned to CO adsorbed on a Pt atom on a step or corner. The intensity of the CO band from CO/sub 2/ adsorption was sensitive to pretreatment of the sample, being completely suppressed by preoxidation but enhanced by prereduction. Lattice oxygen vacancies in the support, CeO/sub 2/, in the vicinity of the Pt particles are responsible for the formation of CO from CO/sub 2/. XPS spectra show that Ce/sup 3 +/ is formed by the prereduction treatment, supporting the proposal that lattice oxygen vacancies play an important role in the CO/sub 2/ decomposition. Preoxidation is shown to lead to the formation of Pt/sup 2 +/ XPS (4f) spectra, which is removed by flash heating. Disproportionation of CO to carbon and CO/sub 2/ was shown not to occur by pretreatment of the surface with CO at 573 K.
- Research Organization:
- Univ. of Texas, Austin
- OSTI ID:
- 5927101
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:23
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON DIOXIDE
ADSORPTION
HEATING
CARBON MONOXIDE
CERIUM OXIDES
SORPTIVE PROPERTIES
PLATINUM
ABSORPTION SPECTROSCOPY
EXPERIMENTAL DATA
HIGH TEMPERATURE
INFRARED SPECTRA
LOW PRESSURE
MEDIUM TEMPERATURE
MEDIUM VACUUM
PHOTOELECTRON SPECTROSCOPY
X RADIATION
CARBON COMPOUNDS
CARBON OXIDES
CERIUM COMPOUNDS
CHALCOGENIDES
DATA
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ELEMENTS
INFORMATION
IONIZING RADIATIONS
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
RADIATIONS
RARE EARTH COMPOUNDS
SORPTION
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties