Effect of the catalyst wettability on the performance of a trickle-bed reactor for ethanol oxidation as a case study

A comparative study on the performance of a trickle-bed reactor packed either with hydrophilic, hydrophobic catalyst particles or mixtures of hydrophobic catalyst-hydrophilic inert support in different mass proportions is carried out. Ethanol oxidation at moderate temperature and atmospheric pressure is selected as a model reaction. Experimental runs employing pure oxygen, relatively high ethanol concentrations and different liquid and gas flow rates are performed for each type of bed. A remarkable improvement in the reactor performance is found when the hydrophobic catalyst is employed, whether the bed is completely hydrophobic or diluted with hydrophilic support. An increase in ethanol conversion of even 100% is achieved for certain conditions. Experimental results are examined through a comprehensive model that rakes into account the influence of particles' wettability on the reactor behavior. It allows us to understand the role of particles' wettability and, consequently, to explain the large improvement in the performance of the trickle-bed reactor when hydrophobic catalyst is used. The model properly describes the effect of bed wetting characteristics on the reactor performance in a wide range of operating conditions. (C) 1999 Elsevier Science Ltd. All rights reserved.