AbstractHydrocracking is a significant process in a refinery which is commonly used for converting heavy fractions such as vacuum gas oil (VGO) to the valuable products such as naphtha and diesel. In this research, VGO hydrocracking process was studied in a pilot scale plant in the presence of a zeolite and two amorphous based commercial catalysts called RK-NiY, RK-MNi and KF-101, respectively. In order to study the effect of support on the yield of the process, a discrete 4-lump kinetic model, including feed (vacuum gas oil and unconverted materials), distillate (diesel and kerosene), naphtha and gas was proposed for each catalyst. At first, each network had six reaction paths and twelve kinetic coefficients, and then by using the model reduction methodology, only four main routes for RK-MNi and RK-NiY, and three ones for KF-101 were designated. Results showed that the absolute average deviation (AAD%) of reduced models decreased from 5.11 %, 10.1 % and 21.8 % to 4.54 %, 8.9 % and 19.67 % for RK-MNi, KF-101 and RK-NiY, respectively. Moreover, it was confirmed that amorphous and zeolite catalysts could be selected for producing middle distillate and naphtha products, respectively.