Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Heterogeneous catalysis II

O 35.5: Vortrag

Dienstag, 23. März 2010, 16:00–16:15, H33

Electrochemical promotion of catalytic ethylene oxidation on Pt/YSZ catalyst under low pressure conditions — •Arafat Toghan, Liz Michaela Rösken, and Ronald Imbihl — Institut für Physikalische Chemie und Elektrochemie, Universität Hannover, Callinstrasse 3-3a, D-30167 Hannover, Germany

The catalytic oxidation of C2H4 on Pt catalyst film interfaced with the oxygen-ion conducting yttria-stabilized zirconia solid electrolyte (YSZ) has been studied in the 10-5 and 10-4 mbar range. Photoemission electron microscopy (PEEM) was used as spatially resolving method. Under open circuit conditions (VWR= 0 V) the CO2 production increases by rising p(C2H4) and then at a critical point decreases sharply, showing a pronounced hysteresis. The hysteresis and the abrupt rate decrease are attributed to the build-up of a carbonaceous CHx layer inhibiting O2 adsorption and hence poisoning the catalyst. Applying an anodic potential of +1V leads to trigger a transition from the unreactive branch of the reaction to an active branch. The huge non-Faradayicity reported in the literature for this reaction system is explained as an ignition effect caused by the partial removal of the inhibiting carbonaceaous layer. The electrode has been characterized by SEM, XRD and a profilometer.

[1] S. Bebelis and C. G. Vayenas, J. Catal. 1989, 118, 125-146.