Kinetic modeling of diesel hydrogenation on a NiMo/γ-Al2O3 catalyst in the RTS process

Abstract

The high and low temperature dual reaction zone RTS (removing trace sulfur) technology is a novel hydrotreating process but lack of in-depth understanding of its kinetics. Three-lump and five-lump kinetic models were developed based on the diesel hydrogenation experimental data which were carried out in the RTS process under various operating conditions to predict the concentrations of ultra-level sulfur and aromatics in hydrotreated oil samples, respectively. Moreover, the inhibiting effect of the hydrogen sulfide (H2S) on the hydrodesulfurization rates of S-compounds has been studied by performing calculations with the actual adsorption concentration of H2S in the catalytic active center. The proposed models were able to reproduce the RTS process with good adjustment and accuracy, and relative deviations below 10.7 % at sulfur content below 10 ppm and polycyclic aromatics hydrocarbons content below 3 wt%. Therefore, these models can serve as an effective guide for diesel hydrotreatment, and the calculated results indicate that the optimal operating conditions in the 1st and 2nd reactors are 350 °C and 340 °C, respectively, at a constant pressure of 6.4 MPa and H2/oil volume ratio of 300 v/v.