Copper oxide mounted on activated carbon as catalyst for wet air oxidation of aqueous phenol. 1. Kinetic and mechanistic approaches

This paper describes the kinetics and an approach to the mechanism of the catalytic wet air oxidation of aqueous phenol. Copper oxide supported over activated carbon was used as catalyst. Experiments were performed in a batch spinning basket reactor at 160-200 degreesC and the total pressure 2.6-4.0 MPa. The experiments showed the suitability of applied catalyst for phenol degradation. The influence of important operating parameters including agitation speed, catalyst particle size, oxygen partial pressure, temperature, and pH of the inlet aqueous solution on the reactor performance was studied. These studies showed unequivocally the interfacial reaction as the limiting step. The proposed kinetics for the phenol removal are based on the Langmuir-Hinshelwood kinetic approach. The reaction order with respect to oxygen was found to be 0.5, and the apparent activation energy was calculated to be 78.6 kJ/mol in the temperature range between 160 and 200 degreesC. Experiments also revealed the positive effect of high pH on the disappearance rate of phenol. Finally, p-benzoquinone and acetic acid were identified as main intermediates of the phenol oxidation.