Studies on hydrodesulfurization of heavy distillates. Part 2. Reaction kinetics of hydrocracking, hydrodesulfurization, and hydrodenitrogenation.

Abstract

Kinetic studies on hydrocracking (HC), hydrodesulfurization (HDS), and hydrodenitrogenation (HDN) reactions of vacuum gas oil derived from mixed Middle Eastern crude oils have been made. Hydroprocess experiments were carried out over a Co-Mo/Al2O3 catalyst at temperatures of 380, 400, and 420°C and at pressures of 4.0 and 7.9MPa. The HC and HDN reactions have been found to be of first order kinetics. However, the order of reaction for HDS reaction decreases with increasing temperature. The sensitivity of these reaction rates to pressure decreases in the following order: HDN>HDS>HC. In addition, with increase in temperature, the effect of pressure on the HC and HDS reaction rates decreases, whereas its effect on the HDN reaction rate is unvaried. These observations are interpreted by assuming that HC and HDS reactions follow at least two parallel reaction routes, which are differently influenced by pressure, and that the selectivity between the parallel reaction routes varies with temperature.