par Visart de Bocarmé, Thierry 
Référence Conference Days of Doctoral Schools MAIN and CHIM (2009-01-20: Bruxelles, Belgique)
Publication Non publié, 2009-01-20
Référence Conference Days of Doctoral Schools MAIN and CHIM (2009-01-20: Bruxelles, Belgique)
Publication Non publié, 2009-01-20
Communication à un colloque
| Résumé : | A number of catalysts used in industry or in automotive pollution control are conditioned as a dispersion of small catalytic particles on a support of high specific area. Assuming a similar bulk composition, the extremity of a sharp metallic tip is quasi-hemispherical (∅ : 10-60 nm) and can mimic one of these catalytic particles. Field ion microscopy (FIM) is used to characterize these surfaces at the atomic scale at cryogenic temperatures and subsequently to image catalytic surface reactions at temperatures where they usually occur. As examples, a few elementary chemical systems will be briefly addressed such as the H2+O2 reaction over Rh, the water gas shift (CO+H2O) reaction over gold and the NO+H2 over Pd and Pt crystals. Depending on the system, surface sensitivity, bistability and oscillations may be observed in association with a variety of surface patterns. Local chemical analysis of the observed features is systematically accomplished by combining FIM with time of flight mass spectrometry during the ongoing processes to determine the surface composition at the different steps of the observed phenomena. |
