Kinetic Modeling of 2,4-dinitrotoluene hydrogenation over Pd/C

The kinetics of liquid phase hydrogenation of 2,4-dinitrotoluene (2,4-DNT) to 2,4-diaminotoluene (2,4-DAT) were studied in ethanol with a 5% Pd/C catalyst using a slurry reactor, in the temperature range between 278 and 323 K and at a pressure of 0.1 MPa. The reaction pathway has been described by a Langmuir-Hinshelwood model with a noncompetitive adsorption of the organic species and hydrogen on the active sites. Different reaction mechanisms have been tested. The best fitting of the experimental data was obtained with a reaction mechanism involving three parallel routes leading from 2,4-DNT to 4-(hydroxyamino)-2-nitrotoluene (4HA2NT), 4-amino-2-nitrotoluene (4A2NT), and 2-amino-4-nitrotoluene (2A4NT) which are then hydrogenated to 2,4-DAT through a series of consecutive reactions. The rate constants and activation energy for each reaction step have been reported.