The role of the carbonaceous deposits in the Catalytic Wet Oxidation (CWO) of phenol

Different CeMn composites have been used as catalyst for the Catalytic Wet Oxidation (CWO) of Phenol under different operating conditions in the range of 80–160 °C and 0.5–2 MPa PO2. High mineralization performances were observed by operating at moderate temperatures (130–160 °C) and oxygen partial pressures (1–2 MPa). The mechanism proposed for the mineralization process includes the initial polymerization of phenol with the rapid formation of a carbonaceous deposit on the catalytic surface (favoured by the presence of Mn), which is later oxidized to CO2 and H2O (the richest Ce catalysts being more active in this process). At milder conditions, i.e. temperatures below 110 °C, no mineralization was observed and only the first process operates producing the irreversible polymer deposition until the total activity loss of the catalyst for phenol elimination.