The effect of catalyst film thickness on the magnitude of the electrochemical promotion of catalytic reactions
The effect of catalyst film thickness on the magnitude of the effect of electrochemical promotion was investigated for the model catalytic reaction of C2H4 oxidation on porous Pt paste catalyst-electrodes deposited on YSZ. It was found that the catalytic rate enhancement ρ is up to 400 for thinner (0.2 μm) Pt films (40,000% rate enhancement) and gradually decreases to 50 for thicker (1 μm) films. The Faradaic efficiency Λ was found to increase moderately with increasing film thickness and to be described semiquantitatively by the ratio 2Fr o/I 0, where r o is the unpromoted rate and I 0 is the exchange current of the catalyst–electrolyte interface. The results are in good qualitative agreement with model predictions describing the diffusion and reaction of the backspillover O2- species, which causes electrochemical promotion.
Keywordselectrochemical promotion NEMCA effect ethylene oxidation catalyst thickness effect promoter reaction-diffusion yttria-stabilzed zirconia support sacrificial promoter
Unable to display preview. Download preview PDF.
- Foti, G., Wodiunig, S., Comninellis, C 2001Curr. Topics Electrochem.71Google Scholar
- I. Metcalfe, J. Catal. 199 (2001) 247; J. Catal. 199 (2001) 259Google Scholar
- Douvartzides, S.L., Tsiakaras, P.E. 2002J. Catal.211521Google Scholar
- C. Sanchez, E. Leiva, in: Handbook of Fuel Cells: Fundamentals, Technology and Applications, Vol. 2, eds. W. Vielstich, H. Gasteiger and A. Lamm (John Wiley & Sons Ltd., England, 2003)Google Scholar
- Grzybowska-Swierkosz, B., Haber, J. 1994Annual Reports on the Progress of ChemistryThe Royal Society of ChemistryCambridgeGoogle Scholar
- C.G. Vayenas, M.M. Jaksic, S. Bebelis, S.G. Neophytides, in: Modern Aspects of Electrochemistry, Vol. 29, eds. J.O.M. Bockris, B.E. Conway and R.E. White (Kluwer Academic/Plenum Publishers, New York, 1996), p. 57Google Scholar
- C.G. Vayenas, S. Bebelis, C. Pliangos, S. Brosda and D. Tsiplakides, Electrochemical Activation of Catalysis: Promotion, Electrochemical Promotion and Metal-Support Interactions (Kluwer Academic/Plenum Publishers, New York, 2001); references thereinGoogle Scholar
- Wieckowski, A.Savinova, E.Vayenas, C.G. eds. 2003Catalysis and Electrocatalysis at NanoparticlesMarcel Dekker IncNew YorkGoogle Scholar
- Vayenas, C.G., Pitselis, G. 2001I&EC Res.404209Google Scholar
- C. Koutsodontis, A. Katsaounis, J. Figueroa, C. Cavalca and C.G. Vayenas, in preparationGoogle Scholar
- C. Koutsodontis, A. Katsaounis, J. C. Figueroa, C. Cavalca, Carmo. J. Pereira and C.G. Vayenas, Topics Catal, in press (2006)Google Scholar