Kinetic modelling of catalytic wet air oxidation of phenol by simulated annealing

A detailed reaction network for the catalytic wet air oxidation (CWAO) of p henol on a CuO/gamma -Al2O3 catalyst is proposed in this study. The reactio n network proposed accounts for all detected intermediate products of pheno l oxidation overcoming the usual lumping of compounds. The model is compose d by several consecutive and parallel reactions. The parameters of the mode l were adjusted using experimental data obtained from a continuous trickle bed reactor using air as oxidant at different temperatures (120-160 degrees C) and oxygen partial pressures (0.6-1.2 MPa). Simple power law as well as Langmuir-Hinshelwood (L-H) expressions accounting for the adsorption effect s were checked in the modelling of the reaction network. A robust non-linea r multiparameter estimation approach called simulated annealing was used to simultaneously evaluate the high number of model parameters (up to 38). Ap proach by simple power law only succeeded in fitting phenol disappearance. Instead. when L-H expressions are incorporated for the intermediate reactio n steps, the model accurately describes all the experimental concentration profiles, giving mean deviations below 8%. In addition, all estimated param eters have physical meaning. In particular, activation energies mostly agre e with those reported in the literature. (C) 2001 Elsevier Science B.V. All rights reserved.