Non-faradaic electrochemical modification of catalytic activity. VIII. Rh-catalyzed C{sub 2}H{sub 4} oxidation
- Univ. of Patras (Greece)
The catalytic activity of polycrystalline Rh films deposited on 8 mol% Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} (YSZ), an O{sup 2-} conductor, can be altered dramatically and reversibly by varying the potential of the Rh catalyst film. The complete oxidation of ethylene was investigated as a model reaction in the temperature range 300 to 400{degrees}C and at atmospheric total pressure. The rate of C{sub 2}H{sub 4} oxidation can be reversibly enhanced by up to 100 times by supplying O{sup 2-} to the catalyst via positive potential application (up to 1.5 V). This is the highest rate enhancement observed so far with in situ electrochemical promotion studies. The steady-state rate increase is typically 10{sup 4} times larger than the steady-state rate of O{sup 2-} supply to the catalyst. It was also found that varying the catalyst potential causing the appearance of the well-known compensation effect with an isokinetic point at 372{degrees}C. As in previous studies of the effect of non-Faradaic electrochemical modification of catalytic activity (NEMCA) the observed behaviour is due to the promotional action of back-spillover oxide ions which migrate from the YSZ solid electrolyte onto the catalyst surface under the influence of the applied potential. The back-spillover oxide ions are less reactive with C{sub 2}H{sub 4} than normally chemisorbed oxygen and act as promoters by affecting the binding strength of chemisorbed oxygen and ethylene. 56 refs., 11 figs., 2 tabs.
- OSTI ID:
- 98972
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 154; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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