Journal of Applied Electrochemistry

, Volume 30, Issue 11, pp 1223–1228 | Cite as

Electrochemical promotion of Rh catalyst in gas-phase reduction of NO by propylene

  • G. Fóti
  • O. Lavanchy
  • C. Comninellis
Article

Abstract

The concept of non-faradaic electrochemical modification of catalytic activity (NEMCA) has been applied for the in situ control of catalytic activity of a rhodium film deposited on YSZ (yttria stabilized zirconia) solid electrolyte towards reduction of 1000 ppm NO by 1000 ppm C3H6 in presence of excess (5000 ppm) O2 at 300 °C. A temporary heating at this feed composition results in a long-lasting deactivation of the catalyst under open circuit conditions due to partial oxidation of the rhodium surface. Positive current application (5 μA) over both the active and the deactivated catalysts gives rise to an enhancement of N2 and CO2 production, the latter exceeding several hundred times the faradaic rate. While active rhodium exhibits a reversible behaviour, electrochemical promotion on the deactivated catalyst is composed of a reversible and an irreversible part. The reversible promotion results from the steady-state accumulation of current-generated active species at the gas exposed catalyst surface whereas the irreversible effect is due to the progressive reduction of the catalyst resulting in an increased recovery rate of lost catalytic activity. The results are encouraging with respect to application of rhodium for the catalytic removal of NO from auto-exhaust gases under lean-burn conditions.

electrochemical promotion lean-burn catalysts NO reduction propylene rhodium 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    M. Iwamoto, Catal. Today 29 (1996) 29.Google Scholar
  2. 2.
    A. Fritz and V. Pitchon, Appl. Catal. B: Environmental 13 (1997) 1.Google Scholar
  3. 3.
    J.N. Armor, Catal. Today 26 (1995) 99.Google Scholar
  4. 4.
    W. Held, A. König, T. Richter and L. Puppe, Society of Automotive Engineering Paper Series No. 900496 (1990).Google Scholar
  5. 5.
    C.G. Vayenas, S. Bebelis and S. Neophytides, J. Phys. Chem. 92 (1988) 5083.Google Scholar
  6. 6.
    C.G. Vayenas, M.M. Jaksic, S. Bebelis and S. Neophytides, 'Modern Aspects of Electrochemistry', No. 29 (edited by J.O'M. Bockris, B.E. Conway and B.E. White), (Plenum Press, New York, 1996), p. 57.Google Scholar
  7. 7.
    E. Varkaraki, J. Nicole, E. Plattner, Ch. Comninellis and C.G. Vayenas, J. Appl. Electrochem. 25 (1995) 978.Google Scholar
  8. 8.
    D. Tsiplakides, J. Nicole, C.G. Vayenas and Ch. Comninellis, J. Electrochem. Soc. 145 (1998) 905.Google Scholar
  9. 9.
    C.G. Vayenas, S. Bebelis and S. Ladas, Nature (UK) 343 (1990) 625.Google Scholar
  10. 10.
    J. Pritchard, Nature (UK) 343 (1990) 592.Google Scholar
  11. 11.
    J. Nicole, D. Tsiplakides, S. Wodiunig and Ch. Comninellis, J. Electrochem. Soc. 144 (1997) L312.Google Scholar
  12. 12.
    C. Pliangos, I.V. Yentekakis, X.E. Verykios and C.G. Vayenas, J. Catalysis 154 (1995) 124.Google Scholar
  13. 13.
    S. Neophytides and C.G. Vayenas, J. Phys. Chem. 99 (1995) 17063.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • G. Fóti
    • 1
  • O. Lavanchy
    • 1
  • C. Comninellis
    • 1
  1. 1.Institute of Chemical EngineeringSwiss Federal Institute of TechnologyLausanneSwitzerland

Personalised recommendations