Kinetics of the Electrochemically Assisted Autoxidation of Toluene in Acetic Acid

Abstract

The oxidation of toluene in acetic acid solution by dioxygen was studied at 100 and 109 °C in a classic gas-liquid reactor supplied with two electrodes of graphite. The cobalt(III) acetate, the catalyst of the autoxidation process, was continuously regenerated on an anode of graphite. The average concentration of cobalt(III) acetate was higher than in absence of electric current; this led to an appreciable improvement of the kinetics of the oxidation of toluene by dioxygen. The obtained products were benzyl acetate, benzaldehyde, and benzoic acid. Benzyl acetate arises mainly from the direct electrochemical oxidation of toluene on the anode. The variations of the concentrations of toluene, benzaldehyde, and benzoic acid result from the two successive autoxidation reactions of toluene and benzaldehyde. It was verified that the kinetics of disappearance of toluene obeys the law:The values of the rate constant k 1 were found equal to 0.36 h -1 at 100 °C and 0.51 h -1 at 109 °C. The limiting step of the mechanism of the toluene autoxidation should be the loss of the proton from the radical C 6 H 5 CH 3 +• .

Liquid-phase oxidation of toluene by molecular oxygen over copper manganese oxides

“…For example, selective catalytic oxidation of methylbenzenes to corresponding alcohols, aldehydes and carboxylic acid by molecular oxygen is of great economic and industrial importance [1,2]. For instance, industrial grade benzoic acid is used as a chemical intermediate and as a diverting agent in crude-oil recovery applications, in addition, the oxidation of toluene to benzoic acid with O 2 is a key step for synthesizing e-caprolactamin in Snia-Viscosa process [3,4].…”

Liquid-phase oxidation of toluene by molecular oxygen over copper manganese oxides

“…[1] For example, selective catalytic oxidation of methylbenzenes to corresponding alcohols, aldehydes and carboxylic acid by molecular oxygen is of great economic and industrial importance [1,2]. For instance, industrial grade benzoic acid is used as a chemical intermediate and as a diverting agent in crude-oil recovery applications, in addition, the oxidation of toluene to benzoic acid with O 2 is a key step for synthesizing e-caprolactamin in Snia-Viscosa process [3,4].…”

Modelling Toluene Oxidation: Incorporation of Mass Transfer Phenomena

“…Since the development of the process (Keading et al, 1965) a large number of studies on the chemistry of toluene oxidation and related hydrocarbons have been published. Most of the earlier publications have in common that the main focus is on the kinetics and that other process items are not considered (Borgaonkar et al, 1984;Lozar et al, 2001;Mulkay and Rouchaud, 1967;Quiroga et al, 1980;Scott and Chester, 1972). This approach is not sufficient when considering scale-up and modelling of the plant reactors.…”