In-depth modeling of gas oil hydrotreating: From feedstock reconstruction to reactor stability analysis

The increasing world demand for clean fuels requires improving existing hydrotreating (HDT) technologies through comprehensive studies of these complex reactive systems. This work presents an exhaustive modeling approach of diesel cut hydrotreating which ranges from the chemical characterization of gas oil feeds, over the HDT kinetic modeling and the thermal stability analysis of the reactor. In this approach, a “statistical reconstruction” method was developed to represent the composition by chemical family and by carbon number of different gas oils starting from a set of global analyses. A kinetic model based on a Langmuir–Hinshelwood representation was developed to determine the most adequate operating conditions to attain on-road diesel specifications, including sulfur levels as low as 10 wt ppm. Finally, since hydrotreating reactions are highly exothermic, the thermal stability analysis of a HDT reactor is also presented. This analysis consists of determining a priori whether the reactive system is thermally stable and therefore predicting if runaway will occur. For the latter, a complete dynamic model of the reactor was developed and used to assess the thermal runaway analysis by the perturbations theory.