The use of carbon materials as catalytic support or direct catalyst in catalytic wet air oxidation (WAO) of organic pollutants is reviewed. The discussion covers important engineering aspects including the characterisation, activity and stability of carbon catalysts, process performance, reaction kinetics and reactor modelling. Recommendations for further research in catalytic WAO are outlined.

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The wet air oxidation of phenol over a commercial active carbon catalyst has been studied in laboratory-scale and pilot-plant fixed-bed reactors at mild temperatures and oxygen partial pressures of 120-160°C and 0.05-0.2 MPa, respectively. The performances of the fixed-bed reactors have been assessed and compared to each other for both up-and downflow operation mode. Depending on the flow mode and reactor scale, distinct phenol destruction rates have been observed in the experiments. A series of batch experiments are carried out to obtain phenol removal kinetics, which are subsequently implemented in the modeling of the pilot-plant fixedbed reactor. A one-dimensional, nonisothermal piston dispersion model is developed to describe in detail the interplay of reaction kinetics, gas-liquid hydrodynamics, and heat and mass transfer in both flow directions. The model predicts reasonably well the experimental data, thus allowing for a thorough explanation of the observed pilot-plant reactor performance.