Wet air oxidation of phenol using active carbon as catalyst

Catalytic wet air oxidation is a promising alternative for the treatment of phenolic waste water which cannot be treated in conventional sewage plants . Catalytic wet air oxidation of an aqueous phenol solution was conducted i n a fixed bed reactor operating in trickle flow regime. Either active carbo n or a commercial copper oxide supported over gamma-alumina was used as cat alyst. The performance of both materials was compared in terms of phenol co nversion in 240 h tests. The results showed that the active carbon, without any active metal supported, gives the highest phenol conversion. The suppo rted copper catalyst undergoes a rapid deactivation due to the dissolution of the metal active species in the acidic medium in which the reaction take s place. On the other hand, the active carbon maintains a higher activity t hroughout the test, although a decrease of the phenol conversion was also o bserved due to both the loss of active carbon by combustion and the reducti on of its surface area. The phenol oxidation was proved to occur through a first order mechanism with respect to phenol. After the ten-day run, the ca talytic activity of the active carbon was found to be about eight times hig her than that of the commercial catalyst, also showing high selectivity to the production of carbon dioxide. (C) 1998 Elsevier Science B.V. All rights reserved.