Catalytic wet air oxidation of phenol over active carbon catalyst -: Global kinetic modelling using simulated annealing

The catalytic wet air oxidation of phenol has been studied in an integral trickle bed reactor using active carbon as catalyst. Temperature, oxygen partial pressure and liquid space time have been varied from 120 to 160 degrees C, 1-2 bar and 0.05-0.55 kg, kg(cat) kg(L)(-1) h, respectively. The active carbon catalyst employed is stable and performs phenol and COD conversions over 99% and 85% with a low residual content of bio-toxic aromatic compounds. The distribution of the main intermediates has been quantitatively assessed by means of HPLC analysis to develop a global kinetic model for the phenol oxidation over active carbon. Several rate models and reaction pathways have been tested in the kinetic modelling. The involved model parameters have been optimised with the stochastical simulated annealing algorithm leading to a very satisfactory fit of the whole experimental data. On cost of a higher, but still reasonable, computational time demand, this easy to implement algorithm proves to be a robust alternative to the classical gradient-based Levenberg-Marquardt algorithm for multi-parameter identification. (c) 2006 Elsevier B.V. All rights reserved.