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Ionics

, Volume 1, Issue 2, pp 159–164 | Cite as

In situ controlled promotion of catalyst surfaces via solid electrolytes: Ethylene oxidation on Rh and propylene oxidation on Pt

  • A. C. Kaloyannis
  • C. A. Pliangos
  • I. V. Yentekakis
  • C. G. Vayenas
Article

Abstract

The kinetics of C2H4 oxidation on Rh and C3H6 oxidation on Pt were investigated on polycrystalline metal films interfaced with ZrO2(8mol%Y2O3) solid electrolyte in galvanic cells of the type:
$$\begin{gathered} C_2 H_4 ,O_2 ,Rh/YSZ/Pt,O_2 and \hfill \\ C_3 H_6 ,O_2 ,CO_2 ,Pt/YSZ/Au,C_3 H_6 ,O_2 ,CO_2 \hfill \\ \end{gathered} $$
It was found that by applying positive potentials and thus, supplying O2- to the catalyst surface, up to 100-fold increases in catalytic rate can be obtained (electrophobic NEMCA effect) for the case of C2H4 oxidation on Rh. For the case of C3H6 oxidation on Pt, up to 6-fold increases in catalytic rate were observed by negative potentials, i.e. removing of O2- from the catalyst surface (electrophilic NEMCA effect).

The induced changes in catalytic rates for both reactions were found to be 103 to 5×104 higher than the rates of ion transfer to or from the catalyst-electrode surface. For both reactions it was found that varying the catalyst potential, and thus work function, causes pronounced changes in activation energy and preexponential factor, leading to an interesting demonstration of the well-known “compensation” effect.

The results can be rationalized on the basis of the theoretical considerations invoked to explain previous NEMCA studies, i.e. the effect of changing work function on chemisorptive bond strengths of electron acceptor and electron donor adsorbates.

Keywords

Solid Electrolyte Catalytic Rate Catalyst Potential Faradaic Efficiency Catalyst Electrode 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© IfI - Institute for Ionics 1995

Authors and Affiliations

  • A. C. Kaloyannis
    • 1
  • C. A. Pliangos
    • 1
  • I. V. Yentekakis
    • 1
  • C. G. Vayenas
    • 1
  1. 1.Department of Chemical Engineering and ICE/HTUniversity of PatrasPatrasGreece

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