Reaction Calorimetry Study of Hydrogenation of Nitroaniline Isomers to Phenylenediamine Isomers

In this work, a detailed reaction calorimetry study of hydrogenation of ortho-, meta-, and para- isomers of nitroaniline to the corresponding phenylenediamine isomers was carried out. An automated high-pressure power compensation reaction calorimeter was used in an isothermal mode in the temperature range of 60–150 °C and pressure ranging from 7 to 20 bar. Reactions were performed using heterogeneous palladium- and ruthenium-based catalysts in the presence of solvent. The process safety data comprising heat rate, heat of reaction (ΔH), adiabatic temperature rise (ΔT_ad), maximum temperature of the synthesis reaction (MTSR), and pressure rise in the case of cooling failure were determined for these reactions. The maximum heat rate of the hydrogenation process was found to be 14.30, 27.47, and 10.81 W for ortho-nitroaniline, meta-nitroaniline, and para-nitroaniline, respectively. The heat of reaction was found to be −567.54 kJ/mol, −611.41 kJ/mol, and −555.01 kJ/mol for ortho-nitroaniline, meta-nitroaniline, and para-nitroaniline hydrogenation, respectively. The highest MTSR for all isomers is estimated along with the corresponding pressure rise.