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.