Seminars Archive
Partial oxidation of methanol over copper: What are the adsorbate species during formaldehyde production? - A never ending story
Abstract
Wednesday, May 25, 2005, 11:00
TASC Seminar Room
Sincrotrone Trieste, Basovizza
Partial oxidation of methanol over copper: What are
the adsorbate species during formaldehyde production? - A never ending
story concerning the pressure gap in catalysis
Sebastian Gnther
(LMU Mnchen, Department Chemie )
Abstract
The reactivity of the Cu(110) surface during the partial methanol oxidation
has been determined under stationary reaction conditions. The reaction
kinetics were studied in detail varying the total pressure and the gas
mixing ratio. In an in situ XPS study we could relate the catalytic reactivity
to the adsorbates species covering the Cu(110) surface. In particular,
we were able to clarify that formate is present on the Cu surface under
reaction conditions at 10-5 mbar and that its decomposition ignites the
low temperature reaction on Cu(110). Nevertheless, this reaction channel
decays when increasing the total pressure. Extending the investigation
into the 10-2 mbar range shows that at high total pressure the reaction
proceeds in a different regime, where the surface has to be activated by
oxygen treatment which introduces immense morphological changes on the
Cu sample. It seems to be that copper represents a good example for the
pressure gap in catalysis, since UHV and "high pressure" ambient lead to
different reactive surfaces.