Comparison of the Oxidation of Phenol with Iron and Copper Supported on Activated Carbon from Coconut Shells

Home-made Fe/activated carbon (Fe/AC) and Cu/activated carbon (Cu/AC) catalysts were tested for the wet oxidation of phenol in a standard wet oxidation unit (Trickle Bed Reactor), at the bench scale and under strong conditions (453-473 K and P = 30 atm). A complete conversion of phenol was reached at 473 K and 30 atm with the Fe/AC catalyst at a metal load of 2 %, while maximum conversion with the Cu/AC catalyst was 75 % with a metal load of 2 %. The Fe/AC catalyst was also found to have good chemical stability under changes of temperature and pH. The results show that the oxidation of phenol takes place on the catalyst surface via a heterogeneous mechanism, whilst the contribution of the homogeneous reaction was not significant. Some oxidation intermediates were identified, consisting of ring intermediates (p-benzoquinone, p-hydroxybenzoic acid and traces of hydroquinone), which were further oxidized to short chain acids (mainly maleic, malonic, acetic and formic acids).