Single event kinetic modeling for paraffin hydrocracking over an industrial Ni–W silica–aluminum catalyst

Abstract

The hydrocracking of n-octane on a Ni–W silica–aluminum catalyst was performed over a fixed-bed reactor. A detailed reaction network was generated based on the hydrocracking behavior and the carbenium ion chemistry. By introducing Golender's potential energy concept, a computer-aided method was developed to calculate the global symmetry numbers of the species and their transition states accurately and conveniently. The single event kinetic models for n-octane hydrocracking were derived and the related physicochemical properties were calculated. A re-lump method to extend the real application of the model was mentioned. Totally, 19 independent kinetic parameters were drawn from the rate equations and were estimated by the genetic algorithm and the Marquardt algorithm. The predicted component evolutions (e.g., the changes of C₃, n-C₄, mono-C₄, n-C₅, mono-C₅, n-C₈, mono-C₈, di-C₈ and tri-C₈) along the reactor corresponded to existing experience in hydrocracking and were logically reasonable. The calculated results at the reactor outlet were in good agreement with the experimental data. This kinetic modeling method is of great significance in kinetic studies and hydrocracking reactor simulation.