Spectroscopic studies of methanol decomposition on Pd 111. Technical report
The thermal decomposition of methanol on a clean Pd 111 surface has been investigated using X-ray photoelectron spectrometry (XPS), secondary ion mass spectrometry (SIMS), and thermal desorption spectrometry (TDS). In this work, the authors observe that the methanolic C-O bond activation on Pd 111 is a strongly coverage dependent process. At lower and higher coverages, XPS data suggest that CH3O ads is the principle product. At near monolayer coverage, the methanolic C-O bond dissociates at 175 K to produce CH3, ads, which is characterized by a Cls binding energy of 283.8 eV, and is stable up to 400 K. A stepwise dehydrogenation of CH3, ads to form CH2, ads (methylene) and CH ads (methylidyne) is observed above 400 K. Surface methyl and its dehydrogenated forms are characterized both by the chemical shift of the XPS Cls peak from 283.8 to 284.8 eV and by positive ion SIMS peaks with m/e 15, 14, and 13. The gaseous products detected by TDS are methanol, CO, hydrogen, methane and water. This observation implies that the methanolic C-O bond cleavage is contingent upon a special molecular arrangement of precursors before reaction and that the CH3, ads product is stabilized by ancillary reaction products, such as CO.
- Research Organization:
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemistry
- OSTI ID:
- 220325
- Report Number(s):
- AD-A--301904/9/XAB; TR--77-ONR; CNN: Contract N00014-91-J-1410
- Country of Publication:
- United States
- Language:
- English
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