| Abstract
| - Aiming to examine the catalytic wet air oxidation process in three-phase reactors, we investigated a slurryreactor for kinetic studies and a pilot-unit trickle-bed reactor, considering reaction aspects as well as thetransport mechanisms involved in the treatment of an aqueous vanillic acid solution, which is a compoundtypically found in olive mill wastewater. Kinetic studies were performed to bring up the lumped kineticparameters in terms of total organic carbon (TOC) over a Mn−Ce−O laboratory-made catalyst. A hydrodynamicmodel for the prediction of pressure drop and liquid holdup for a trickle-bed reactor has been developed bymeans of computational fluid dynamics (CFD) according to data taken from the open literature. First, single-phase flow pressure drop was studied in a region of flow rates that is of particular interest to trickle-bedreactors (10 < ReG< 400), and it was demonstrated that the Eulerian model is able to predict reasonably thepressure drop of single-phase flow over spherical particles when the Ergun equation adjusts pressure dropmeasurements within 10% on average. The two-phase flow operating regime is then investigated, and theCFD Eulerian model predicts very well liquid holdup in the range of gas flows studied (G = 0.10−0.70kg/(m2 s)). Finally, CFD runs were performed in unsteady state for the catalytic wet air oxidation of theaqueous vanillic acid solution. TOC profiles indicated that complete reduction of organic matter was achievedat space times up to 1.5 h. Moreover, CFD demonstrated the considerable effect of temperature, whereas theair partial pressure only has a minor influence.
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