Mathematical modeling of the hydrocracking kinetics of a heavy oil fraction using the discrete lumping approach: the effect of the variation of the lump number

Abstract

The mathematical modeling of hydrocracking kinetics of a heavy oil fraction was carried out using the discrete lumping approach and different number of lumps, using all reaction routes among them. We use data previously reported for the implementation of the models; the information used was taken at 663, 683 and 703 K, and LHSV ranging from 0.5 to 3 h⁻¹. For modeling the reaction rate, we use the power law kinetic model, assuming a first order on hydrocarbon concentration. We developed six approaches that represented well the experimental data. Some relevant features of the discrete lumping were observed, such as the slight differences among the overall rate constant from residue to the whole products, and those obtained from summing the contribution of each rate constant from simultaneous reaction of residue to diverse distillates. Close agreement between simulated profiles and experimental data was found for all kinetic model approaches; the maximum error was 1.1 × 10^–3 while the minimum was 8.76 × 10^–5. Using the rate constants at each temperature and model approach, we obtain the activation energies, and those were of about 10⁵ J/mol.