Ethylene Oxidation on Pt

S. Bebelis, and C.G. Vayenas, Non-Faradaic Electrochemical Modification of Catalytic Activity 1. The case of Ethylene Oxidation on Pt, J. Catal. 118, 125-146 (1989). 

C.G. Vayenas, C.Georgakis, J. Michaels, and J. Tormo, The role of PtOx in the isothermal rate and oxygen activity oscillations of the Ethylene Oxidation on Pt, J. 

P.D. Petrolekas, S. Balomenou, and C.G. Vayenas, Electrochemical promotion of Ethylene Oxidation on Pt Catalyst Films deposited on Ce02, J. Electrochem. Soc. 

Figure 5.13. Effect of catalyst overpotential, AUWR, on catalytic rate and on catalyst work function changes, AO, during ethylene oxidation on Pt/YSZ at 400°C.34Reprinted with permission from Elsevier Science.

Electrochemical Modification of Catalytic Activity 9. Ethylene oxidation on Pt deposited on Ti02, /. Catal. 159, 189-203 (1996). 

Ethylene oxidation on Pt/Ti02 was investigated at temperatures 450°C to 600°C and was found to exhibit strong electrochemical promotional behaviour at temperatures near 500°C.24... 

Ethylene oxidation on Pt/p"-Al203 was studied1 at temperatures 150° to 300°C, but most of the NEMCA experiments were carried out at 290°C. Experimental details about the cell can be found in ref. 1. The open-circuit kinetic behaviour was found to be similar to the case of C2H4 oxidation on Pt/YSZ (Chapter 8), i.e. the rate expression ... 

Figure 9.4. Effect of pcaw (a) and p02 (b) and catalyst potential on the rate of ethylene oxidation on Pt/NASICON.20 Reproduced by permission of The Electrochemical Society, Inc.

Figure 12.5. Ethylene oxidation on Pt finely dispersed on Au supported on YSZ.7 Effect of the current 1 on x 1, where x is the time constant measured during a galvanostatic transient experiment with I as the applied current x is obtained by fitting either r/r0=exp(-t/x) or l-exp(-t/x) to the experimental data depending on the sign of the current and whether the reaction is electrophilic or electrophobic, (a) Positive values of I for electrophilic (squares, T=371°C, pO2=18.0 kPa, Pc2H4=0-6 kPa) and electrophobic behavior (circle, T=421°C, p02=l 4.8 kPa, Pc2H4 CU kPa) (b) negative currents, electrophilic behavior (T=421°C, p02=14.8 kPa, pC2H4=0.1 kPa. Reprints with permission from Academic Press.

Addresses of suppliers of catalyst pastes included in Table B.l are presented below. Other companies (e.g. Johnson-Matthey) may also supply similar products. The suitability of these products for preparing catalyst films for electrochemical promotion studies should be tested on the basis of the requirements already mentioned. A useful approach before proceeding with the study of new systems is to try to reproduce results of electrochemical promotion studies in model systems, such as ethylene oxidation on Pt, which has been thoroughly studied. It has to be pointed out that in general suppliers do not provide calcination procedures or the provided calcination procedures aim to the production of very dense and non-porous films not necessarily suitable for electrochemical promotion studies. 

Vayenas et al. (J89) developed a model for ethylene oxidation on Pt based on solid-state electrolyte measurements that resembles the Sales-Turner-Maple model described in Section IV,A. However, Vayenas et al. balanced gas-phase concentrations and considered the surface coverages of only two species, namely active and inactive oxygen. Ethylene was assumed to react very rapidly, thus never reaching a significant surface coverage. This model semiquantitatively reproduced the experimentally observed behavior. 

We can now concentrate on Figure 15, which shows a galvanostatic catalytic rate transient during ethylene oxidation on Pt/YSZ at 370 °C [Figure 15(a)] [26] together... 

Bebelis S, Vayenas CG (1989) Non-faradaic electrochemical modification of catalytic activity 1. The case of ethylene oxidation on Pt. J Catal 118 125-146... 

The kinetics and mechanism of ethylene oxidation on Pt have been studied for years on Pt films deposited on doped Zr02. It has been found that at temperatures above 280°C the open-circuit catalytic kinetics can be described quantitatively by the rate expression... 

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