Catalytic wet oxidation carried out in a continual three-phase trickle-bed reactor contributes to the sustainability of chemical technology. It was found that the hydrodynamics and the masstransfer of reactants could have a signi®cant impact on the performance of the trickle-bed reactor. An aqueous phenol oxidation was tested at different temperatures and liquid feed rates and the activities of both the CuO-supported catalyst and the extruded active carbon were compared. To avoid the impact of liquid maldistribution, a bed of catalyst particles diluted with ®ne glass spheres was also used. Ratelimited conditions of both liquid-and gas-phase presented reactants were determined. Under the conditions of gas component transfer limitation, a better wetting of the diluted catalyst bed can lead to a worsening in the reactor performance due to the lower overall reaction rates.

Catalytic activity of CuO-supported catalyst in phenol oxidation, and the influence of reaction conditions, viz. temperature (125-170 °C), oxygen partial pressure (1-7 MPa) and liquid feed (30-760 ml h-1), in the continuous operation using 17.9 mm i.d. trickle-bed reactor is presented. The hydrodynamic impact on the three-phase trickle-bed reactor performance in an environmental application of catalytic wet oxidation was also investigated. The results of trickle-bed operation were strongly influenced by wetting efficiency. An insufficient catalyst wetting can be to compensated by filling the catalyst bed voids by fine glass spheres. In the case of the gas transfer limited reaction, a better wetting of the catalyst can lead to worse reactor performance due to lower reaction rates.