Catalyst systems for the oxidation of phenol in water

The oxidation of phenol solutions (5 g/L) has been studied in a semibatch autoclave reactor. Activity screening experiments were performed over two com- mercial catalysts: CuO+ZnO (Topsoe) and CuO+NiO (Engelhard), and CuO/Al2O3 prepared in our labora- tory. Isothermal runs between 393 and 423 K were carried out under an oxygen pressure of 7 bar. Phenol conversion as well as pH and Chemical Oxygen De- mand (COD) measurements were recorded. Almost complete phenol conversion was obtained for all cata- lysts. However, conversion to CO2 was only partial. Laboratory prepared catalysts gave the best perform- ance in terms of activity and selectivity with the lowest induction period. Stability tests showed that catalysts remained moderately active after 60 h of operation. A simple kinetic model fits experimental results.