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Catalytic phenol oxidation in aqueous phase under intermediate temperature and pressure has been carried out in order to determine the kinetic model of phenol uptake rate. The catalyst employed here was a commercial one based on copper supplied by Engelhard (Cu-0203T). Operational variables have been studied in the following ranges: temperature from 127 to 180 degrees C, oxygen pressure from 3.2 to 16 bar, initial phenol concentration from 680 to 1200 ppm, and catalyst concentration from 0 to 1550 g/L of liquid phase. Because of the wide interval here employed for the catalyst concentration, two experimental setups have been used: a basket stirred tank reactor (BSTR) with the liquid phase in batch and an integral fixed-bed reactor (FBR) with co-current upflow of gas and liquid phases. An important influence of the reaction in the bulk liquid was obtained in both types of reactor. This fact has been taken into account in the kinetic model according to different approaches. The first approach was a breakup of the reaction rate in two kinetic expressions, considering the homogeneous and heterogeneous contribution separately; the second approach was empirical where the reaction rate is a potential function of the catalyst concentration. It was found that the extent of reaction in the bulk liquid is also influenced by the catalyst concentration and that the first approach is not able to adequately predict the experimental results. Finally a kinetic model, based on the second approach, was discriminated, with a power law for the catalyst concentration with an order about 0.4. This model fits quite well the experimental data obtained in both experimental setups, BSTR and FBR, throughout the wide range of variables studied.

Phenol mineralization in the aqueous phase was studied employing oxygen as the oxidant. The reaction was carried out at intermediate oxygen pressures (3.2-16 bar) and temperatures (127-180 °C) employing a commercial catalyst supplied by Engelhard (Cu-203T). Two experimental setups were used: a basket stirred-tank reactor (BSTR) with the liquid phase in batch and an integral fixed-bed reactor (FBR) with concurrent upflow of the gas and liquid phases. These two apparatuses allowed the catalyst concentration to be changed over a wide range (4-1150 g/L) so that the influence of this variable could be more accurately determined. It was found that the reaction takes place to a significant extent both in the liquid phase and on the catalyst surface. A kinetic model for phenol mineralization was discriminated on the basis of a twostage power-law kinetic expression. The first stage corresponds to the induction period, and the second to the steady state. This model was able to predict accurately the experimental results over the entire range of the variables studied. The catalyst concentration was included in this model with a power-law order of about 0.5 found for both the induction and steady-sate regions.

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