Hydrogenation of 2,4-dinitrotoluene using a supported Ni catalyst: reaction kinetics and semibatch slurry reactor modeling

Abstract

The kinetics of hydrogenation of 2,4-dinitrotoluene (2,4-DNT) using a 10% Ni supported on zeolite Y (10% Ni/HY) powdered catalyst (d_p = 1 × 10^-5 m) was studied experimentally in a semibatch slurry reactor over a temperature range of 333-363 K. The effects of reaction temperature, H₂ pressure, concentration of 2,4-DNT and catalyst loading on the concentration-time and H₂ consumption-time profiles were studied under isothermal conditions. To explain the rate behavior of this complex, consecutive, and parallel reaction, several rate expressions were derived based on Langmuir-Hinshelwood type rate mechanisms. The rate equations that were derived assuming the reaction between competitively adsorbed organic species and dissociatively adsorbed hydrogen as the rate-limiting step were found to represent the kinetics best. Quantitative analysis of the experiments performed under the chosen conditions (temperature, 333-363 K; H₂ pressure, 1.3-5.4 MPa; 2,4-DNT concentration, 0.14-0.55 kmol/m³) indicated that the rate data obtained were under the kinetic regime. The rate and equilibrium parameters were evaluated for the different steps involved in the reaction network. A semibatch slurry reactor model has been developed to predict both integral concentration-time and H₂ consumption-time profiles and was compared with experimental data at different sets of initial conditions. An excellent agreement between the model predictions and the experimental data was observed.