CATALYTIC-OXIDATION OF ORGANICS IN AQUEOUS-SOLUTIONS .1. KINETICS OF PHENOL OXIDATION

Liquid-phase oxidation using a solid catalyst provides a potential method for removal of dissolved toxic organic pollutants from waste waters. Catalytic oxidation of phenol in an aqueous solution was studied in a semibatch slurry reactor. A catalyst comprising ZnO, CuO, and A1203 was found to be effective for converting phenol to nontoxic compounds via different intermediate products at pressures slightly above atmospheric and temperatures below 130°C. Rate measurements showed that the reaction progressed autocatalytically and involved a heterogeneous-homogeneous free radical mechanism and stepwise addition polymerization. The proposed rate equation for the phenol disappearance, which exhibits linear behavior with respect to the phenol concentration and one-fourth power of the oxygen partial pressure, is expressed in terms of the initial phenol concentration as well as the catalyst concentration. Apparent activation energy for thecatalytic oxidation of phenol was found to be 84 kJ/mol in a temperature range of 105 to 130°C. © 1992.