SO{sub 2} promoted propane oxidation over Pt(111) and Pt(111)/AlO{sub x}
- Cambridge Univ., Cambridge (United Kingdom)
SO{sub 2} strongly promotes the catalytic oxidation of propane over conventional Pt/Al{sub 2}O{sub 3} catalysts where sulphate species on the alumina are thought to play a critical role. However there is little fundamental understanding of the processes involved. Our TPR, HREELS and XPS results for SO{sub 2}{sup -} modified propane oxidation over Pt(111) and Pt(111)/AlO, planar model systems show that strong promotion occurs over Pt alone. The reaction is therefore not just support mediated. HREELS and XPS measurements identify SO{sub 4} as a crucial surface species and HSO{sub 4}{sup -} is observed in the HREEL spectra when propane adsorbs on the activated metal surface. Thus H abstraction from the hydrocarbon by SO{sub 4}{sup 2-} is the likely initiation step. During oxidation SO{sub 2} and CO{sub 2} desorb coincidentally, suggesting complex formation between SO{sub x} and reactively produced CO. This hypothesis is supported by isotope tracing experiments and by the observation of a S-O-C stretching mode in the HREEL spectra. Submonolayer films of AlO{sub x} strongly enhance the yield of oxidation products by stabilizing the surface sulphate.
- OSTI ID:
- 370129
- Report Number(s):
- CONF-960376--
- Country of Publication:
- United States
- Language:
- English
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