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The adsorption of acetic acid on clean and oxygen-covered Au/Pd(100) alloy surfaces

Authors
Journal
Surface Science
0039-6028
Publisher
Elsevier
Volume
606
Identifiers
DOI: 10.1016/j.susc.2012.08.001
Keywords
  • Infrared Absorption Spectroscopy
  • Temperature-Programmed Desorption
  • Chemisorption
  • Palladium Gold Alloy
  • Acetic Acid
Disciplines
  • Physics

Abstract

Abstract The adsorption of acetic acid is studied on clean and oxygen-covered Au/Pd(100) alloys as a function of gold content by temperature-programmed desorption and reflection–absorption infrared spectroscopy. Au/Pd(100) forms ordered alloys such that, for gold coverages above ~0.5 monolayers, only isolated palladium atoms surrounded by gold nearest neighbors are present. Predominantly molecular acetic acid forms on Au/Pd(100) alloy surfaces for gold coverages greater than ~0.56ML, and desorbs with an activation energy of ~59kJ/mol. Heating this surface also forms some η1-acetate species which decompose to form CO and hydrogen. On alloy surfaces with palladium–palladium bridge sites, η1-acetate species initially form, but rapidly convert into η2-species. They thermally decompose to form CO and hydrogen, with a small portion rehydrogenating to form acetic acid between 280 and 321K depending on gold coverage. The presence of oxygen on both Pd(100) and Au/Pd(100) alloys facilitates acetate dehydrogenation so that only η2-acetate species form on these surfaces. The presence of oxygen also serves to stabilize the acetate species.

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