Thermal decomposition of CH sub 3 OH adsorbed on Pd(111): A new reaction pathway involving CH sub 3 formation

Journal Article · Wed Jun 21 04:00:00 EDT 1989 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00195a013· OSTI ID:7157828

Levis, R J; Zhicheng, Jiang; Winograd, N ^[1]

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1. Pennsylvania State Univ., University Park (USA)

The adsorption and subsequent decomposition of CH{sub 3}OH on Pd(111) has been examined with X-ray photoelectron spectroscopy and secondary ion mass spectrometry (SIMS) over the temperature range 110-600 K. The authors find that the thermal decomposition reaction pathway after adsorption at 110 K is strongly dependent on the initial CH{sub 3}OH exposure. Below the saturation CH{sub 3}OH exposure of 1.5 langmuirs the primary decomposition products are observed to be CH{sub 3ads}, OCH{sub 3ads}, and H{sub 2}O{sub ads}. This chemistry suggests that the methanolic C-O bond is activated at the metal surface. These products are observed to form at temperatures as low as 125 K. For exposures above 1.5 langmuirs this decomposition pathway is no longer observed, possibly due to a site blocking effect, and molecular desorption occurs with trace decomposition. Interestingly, they find no evidence that CH{sub 3}OH adsorbed at 110 K with initial exposures below 1.5 langmuirs decomposes to CO at any temperature below the thermal desorption temperature of CO at 490 K. finally, the SIMS ion observed at m/e 15 (CH{sub 3ads}) and associated with the decomposition of CH{sub 3}OH is found to persist over the rather wide temperature range 125-400 K. The unusual stability of CH{sub 3ads} suggested by these findings may be related to the effectiveness of Pd-based catalysts to produce CH{sub 3}OH.

• OSTI ID: 7157828
• Journal Information: Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:13; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400000 -- Chemistry
400201 -- Chemical & Physicochemical Properties
ADSORPTION
ALCOHOLS
ALKYL RADICALS
DATA
DATA ANALYSIS
ELECTRON SPECTROSCOPY
ELEMENTS
EXPERIMENTAL DATA
HYDROXY COMPOUNDS
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
METHANOL
METHYL RADICALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PALLADIUM
PHOTOELECTRON SPECTROSCOPY
PLATINUM METALS
RADICALS
SORPTION
SPECTROSCOPY
THERMAL DEGRADATION
TRANSITION ELEMENTS