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

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