WET OXIDATION OF PHENOLIC SOLUTIONS OVER HETEROGENEOUS CATALYSTS - DEGRADATION PROFILE AND CATALYST BEHAVIOR

Removal of phenol by wet air oxidation (WAO) from dilute aqueous solut ions was conducted in the presence of oxygen over a 1 wt% Pt/Al2O3 and Mn/Ce (7/3) composite oxide catalysts. The reaction was carried out i n a batch slurry reactor using pure oxygen as an oxidizing agent under mild reaction conditions, i.e., temperature from 80 to 175 degrees C and oxygen pressure from 0.5 to 1.5 MPa. The platinum catalyst was fou nd to be moderately active, while the Mn/Ce catalyst was remarkably ef fective in reducing both phenol concentration and total organic carbon . On both catalysts the kinetics of phenol removal was characterized b y a fast reaction step followed by a slower one. During WAO reaction, a carbonaceous material was formed and deposited on the catalysts surf ace. This deposit was characterized by temperature-programmed oxidatio n coupled to mass spectrometry detection and X-ray photoelectron spect roscopy. (C) 1998 Academic Press.