Kinetic model for hydrocracking of heavy oil in a CSTR involving short term catalyst deactivation

A five-lump model previously reported in the literature was used for the kinetic modeling of an atmospheric residue (312 °C+) hydrocracking. The model has ten reaction rate coefficients, makes a distinction of different hydrocarbon groups based on boiling ranges, and includes the following lumps: unconverted vacuum residue (538 °C+), vacuum gas oil (VGO; 343–538 °C), middle distillates (204–343 °C), naphtha (IBP-204 °C), and gases. The kinetic study was carried out in a CSTBR at the following operating conditions: 380–420 °C, 100 kgf/cm2, 5000 std ft3 H2/bbl of oil, and 0.5–1.25 mlfeed/(mlcat h). Experiments were performed with a commercial size tetra lobular catalyst. The model also incorporates the effectiveness factor, and a time-dependant deactivation function for obtaining the intrinsic kinetic parameters. The hydrocracking of vacuum residue, VGO and middle distillates exhibited a higher selectivity toward the heavier lumps as temperature is increased. The predicted product composition is in good agreement with experimental values with an average absolute error less than 5%.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► An atmospheric residue (312 °C+) was hydroprocessed. ► Experiments were performed in continuous stirred tank basket reactor. ► A five-lump kinetic model to represent the hydrocracking reactions was used. ► A time-dependant non-selective catalyst deactivation expression was considered. ► Activation energies and kinetic constants for heavy oil hydrocracking are reported.