Kinetics of wet air oxidation of phenol

Abstract

Aqueous solutions of phenol were oxidized in a batch reactor at temperatures between 150 and 300 “C and pressures from 100 to 200 bar. The initial phenol concentrations were between 460 and 1650 ppm and the initial oxygen concentration was always above 800% excess. The oxidation experiments covered essentially the entire range of phenol conversions and included all temperature ranges studied by previous workers. The reduction of COD during oxidation was also measured. Furthermore, pyrolysis experiments were carried out to verify that phenol is not degraded by this mechanism in the conditions studied. Due to disagreement in the previous published data about the activation energy, an effort has been made to obtain reliable kinetic data, assuring great oxygen excess and minimum disturbance in the sampling procedure. The oxidation reaction was found to be pseudo-first order with respect to phenol, with an activation energy of 34.4 kJ mol- ‘. The influence of pressure and temperature on the induction time was also