Infrared spectroscopic investigation of the ethylene chemisorption reaction on supported metallic catalyst surfaces: ethylidyne formation on Pt, Rh, Pd, and Ru supported on alumina
The reaction of ethylene with Pt, Rh, Pd, and Ru supported on alumina has been studied at 300 K by transmission infrared spectroscopy. Small metal particles of all four elements form the ethylidyne species, identical with CCH/sub 3/, and the vibrational frequencies of these species are in close agreement with those reported for ethylidyne adsorbed on the close-packed faces of single crystals of these same metals. The authors PT and Rh surface produce ethylidyne IR bands of higher intensity than Pd and Ru. This is consistent with the presence of smaller Pt and Rh average particle sizes, where quantitative CO adsorption measurements indicate an approximately 2- to 3-fold greater chemisorption capacity of Pt and Rh surfaces than Pd and Ru surfaces. In addition, Pt and Rh surfaces exhibit relatively strong ethylidyne asymmetric modes (nu/sub as/(CH/sub 3/) and sigma/sub as/(CH/sub 3/)), indicating that the surface-dipole selection rule is not strictly in operation on these surfaces. This weakening of the selection rule for Pt and Rh surfaces is consistent with the small average particle sizes for Pt and Rh (19 and 28 A, respectively) compared to larger average particle sizes for Pd and Rh (84 and 66 A, respectively).
- Research Organization:
- Univ. of Pittsburgh, PA
- OSTI ID:
- 6874795
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ETHYLENE
ABSORPTION SPECTROSCOPY
CHEMISORPTION
PALLADIUM
PARTICLE SIZE
SORPTIVE PROPERTIES
PLATINUM
RHODIUM
RUTHENIUM
ALUMINIUM OXIDES
CATALYSTS
EXPERIMENTAL DATA
INFRARED SPECTRA
MEDIUM TEMPERATURE
VIBRATIONAL STATES
ALKENES
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
ELEMENTS
ENERGY LEVELS
EXCITED STATES
HYDROCARBONS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
SEPARATION PROCESSES
SIZE
SORPTION
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties