Role of coverage in determining adsorbate stability: Phenol reactivity on Rh(111)
- Harvard Univ., Cambridge, MA (USA)
The reaction of phenol on Rb(111) has been studied by use of temperature programmed reaction and X-ray photoelectron spectroscopies under ultrahigh vacuum. Phenol undergoes competing molecular desorption and O-H bond cleavage to form adsorbed phenoxy below 300 K. Phenoxy quantitatively reacts to form carbon monoxide (400-500 K) and stoichiometric amounts of surface carbon and dihydrogen. O-H bond cleavage of phenol occurs at temperature as low as 120 K, but no C-H bond cleavage occurs until above 350 K. The decomposition kinetics of the adsorbed phenoxy are strongly dependent on its coverage. At low coverage phenoxy decomposes below 400 K to form adsorbed CO which desorbs near 500 K, while at saturation coverage, phenoxy decomposes about 450 K to CO, a large fraction of which is evolved directly into the gas phase at 495 K. Comparison of the reactivity of phenoxy on Rh(111) with previous studies of Mo(110) suggests that the strength of the metal-oxygen bond results in different selectivities on the two surfaces. On Mo(110), all C-O bonds are broken by 450 K leaving an oxygen overlayer on the surface whereas no C-O bond breaking is induced by the Rh(111) surface.
- OSTI ID:
- 7197315
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:24; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400000* -- Chemistry
400201 -- Chemical & Physicochemical Properties
ADSORBENTS
AROMATICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CHALCOGENIDES
DATA
DATA ANALYSIS
ELEMENTS
EXPERIMENTAL DATA
HYDROXY COMPOUNDS
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHENOLS
PLATINUM METALS
REACTIVITY
RHODIUM
TRANSITION ELEMENTS
ULTRAHIGH VACUUM