The Influence of Hydrodearomatisation Reaction Kinetics on the Modelling of Sulphur and Aromatics Removal from Diesel Fuel in an Industrial Hydrotreating Process

Abstract

Over the years, the hydrotreating process has been considerably improved in order to facilitate the production of environmentally friendly diesel fuels by reducing sulphur and aromatics concentrations, as mandated by contemporary emissions regulations. In this study, different kinetic models for the hydrodearomatisation reaction and the influence of reaction rate on performance of the industrial trickle bed reactor for hydrotreating of gas oil and light cycle oil fractions were analysed. The impact on reactor temperature, catalyst wetting efficiency, and conversion of sulphur and aromatics were determined. The results of simulations were compared with experimental data from an industrial test run and the best model for the observed process is proposed. Reactor performance and overall efficiency of the process is strongly dependent on the kinetics of hydrodearomatisaton with respect to aromatics conversion but even more so with respect to the temperature increase in the reactor, which affects all key catalytic reaction parameters, catalyst wetting efficiency, and thus the sulphur conversion. Based on the obtained simulation results, it could be concluded that reactor performance is strongly dependent on the hydrodearomatisation reaction. The best predictions of outlet temperature as well as sulphur and aromatic conversion (deviation from the experimental value 0.87 K, 0.01% and 2.57%, respectively) are achieved with the Langmuir–Hinshelwood kinetic model proposed by Owusu-Boakye.