Anodic oxidation of unsaturated hydrocarbons on platinized electrodes

Abstract

The anodic oxidation of a number of unsaturated hydrocarbons at 80°C in 1N H2S04 on a platinized Pt electrode has been studied. The mechanism previously established for the anodic oxidation of ethylene was shown to apply to all unsaturated hydrocarbons studied which involve single or conjugated double bond systems. Essentially the same kinetic parameters were observed for all doublebonded hydrocarbons. The small decrease of reaction rate at constant potential with increasing size and polarizability of the organic was attributed to differences in coverage and to an effect of the organic on the stability of the -OH radicals formed on the surface in the water discharge step, assumed to be the rate-determining step in all these systems. The origin of the observed variation of the current with time at constant potential was shown to be due to diffusion-controlled rate of adsorption of ethylene in the initial stages (up to about 15 min) and then to slow activated adsorption.

The Mechanism of Electrochemical Oxidation of Organic Fuels

“…Their work, however, might be considered a forerunner to the present water discharge mechanism for the electrochemical oxidation of unsaturated hydrocarbons as suggested by Wroblowa, Pier sma and Bocknis. 32 , 33 Glasstone and Hickling also contributed one of several books on the subject of organic electrochemistry34 (others are by Fichter, 35 Allen,6 and Brockman 36 ).…”

“…Then, (32) and E2 = E~ -/lX + ReE (33) where E'1 and E~ are the non-field dependent interactions of water in its two positions with the metal surface, e is a coordination number on the surface, E is the energy of interaction between dipoles, and R is given by…”

“…It appears that allene and butadiene delay the formation of oxide, perhaps because of a more anodic desorption potential for these two compounds. A comparison of the capacity-potential curves for ethylene and butadiene 33 (Figure 26) shows an increase of the double-layer capacity in the potential region of passivation which is more anodic in the presence of butadiene. This increase in capacity corresponds to a pseudocapacity of the oxide formed in this region, .8…”

Anodic Oxidation of Ethylene Glycol on Platinum: a Mechanistic Study

“…The general experimental procedures were similar to those used in our previous work (4) and in other recent work in electrode kinetics (13,14). Some specific features are listed below, however.…”

High-Pressure Electrochemical Oxidation of Benzene at a Lead Dioxide Electrode in Aqueous Bisulfate Solutions at 25 to 250 deg C

“…This full oxidation can occur readily at a platinum electrode. 15 Lead dioxide is the only reported electrode material that produces large quantities of benzoquinone or maleic acid. A lead dioxide electrode will perform the first stage oxidation to benzoquinone readily in acidic sulfate media, however the yield and current efficiency vary greatly depending on the specific conditions of electrolysis.…”