Hydrogenation kinetics of m-dinitrobenzene in a continuous micro-packed bed reactor

The hydrogenation of m-dinitrobenzene to m-phenylenediamine is a significant transformation for the synthesis of dyes and pigments in the fine chemical industry. Owing to the complexity of this reaction mechanism and negative effect of the first amino group on the reduction of the second nitro group, it is difficult to inhibit eminently the generation of side products and obtain m-phenylenediamine efficiently. Hence it is imperative to establish kinetic network and investigate the intrinsic kinetic parameters of this reaction for further optimization. In this study, a continuous flow system based on micro-packed bed reactor was developed and a kinetic model of the hydrogenation of m-dinitrobenzene was established successfully. The activation energies and pre-exponential factors were acquired using the kinetic network and the kinetic model exhibited reasonable fit for the transformation of each substance. Moreover, the influence of pressure was investigated, and the accuracy of kinetic model was validated by the comparison with the values in literature. This kinetic model enabled the accurate determination of kinetic parameters with Pt/C and Ni/SiO2 catalysts, and provided the rate determining steps and characteristics of different catalysts for the process optimization.