Kinetic Study on Hydrogenation of 2, 4-Dinitrotoluene to 2, 4-Tolylenediamine Catalyzed by Ni/HY Catalysts

Reaction mechanism, optimization conditions and kinetics of the catalytic hydrogenation of 2, 4-DNT to 2, 4-TDA with Ni/HY catalysts were investigated in a 1 L batch reactor using ethanol as the solvent. There were two routes using 2, 4-DNT to synthesize 2, 4-TDA. 2, 4-DNT preferred to be converted into intermediate 4A2NT (less converted into 2A4NT) due to the steric resistance of methyl and then transformed into target products. Effects of stirring rates, reaction temperatures and hydrogen pressure on 2, 4-DNT conversion and 2, 4-TDA yields were investigated. The results demonstrate that the reaction is under intrinsic regime when the stirring rate is 600 r·min^-1. Temperature and pressure have great effects on intermediate conversion. Reaction kinetic parameters were determined based on dynamic studies. The activation energy from 2, 4-DNT to 4A2NT is 31.3 kJ·mol^-1 with adsorption heat of -29.9 kJ·mol^-1. The activation energy from 4A2NT to 2, 4-TDA is 26.4 kJ·mol^-1 with adsorption heat of -9.3 kJ·mol^-1. The activation energy from 2, 4-DNT to 2A4NT is 28.7 kJ·mol^-1 with adsorption heat of -15.0 kJ·mol^-1. The activation energy from 2A4NT to 2, 4-TDA is 31.0 kJ·mol^-1 with adsorption heat of -16.8 kJ·mol^-1. The dynamic simulation results are consistent with the experimental results.