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), Vol. 93:24; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CATALYSTS
PHENOLS
REACTIVITY
ADSORBENTS
CARBON MONOXIDE
DATA ANALYSIS
EXPERIMENTAL DATA
MEASURING INSTRUMENTS
MEASURING METHODS
RHODIUM
ULTRAHIGH VACUUM
AROMATICS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DATA
ELEMENTS
HYDROXY COMPOUNDS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
TRANSITION ELEMENTS
400000* - Chemistry
400201 - Chemical & Physicochemical Properties