Kinetics toward mechanism and real operation for ultra-deep hydrodesulfurization and hydrodenitrogenation of diesel

As the hydrodesulfurization (HDS) of diesel achieves ultra-deepness, our understanding of its kinetics is still far from in-depth. Therefore, herein, two lumped kinetic models for the ultra-deep hydrodesulfurization (UHDS) and hydrodenitrogenation (HDN) are established based on experiments under a wide range of operating conditions. Meanwhile, a four-lump kinetic model of the aromatic hydrosaturation (AHS) is erected. Our kinetic models disclose thermodynamic decisiveness in UHDS, which is unreachable beyond a temperature upper limit or a pressure lower limit. We also reveals the unexpected temperature dependence of organonitrogen inhibition to HDS, for less than 300 degrees C this inhibition becomes even more potent despite nitrogen removal by HDN reactions. Subsequently, the HDS kinetics of total sulfur are deciphered as multi stages existed in the whole reaction coordinate. Accordingly, a four-stage conceptual model involving mechanism and rate laws is proposed to better understand organonitrogen inhibition, thermodynamics, and kinetics in UHDS.

Automated summary

In the process of ultra-deep hydrodesulfurization of diesel, two lumped kinetic models and a four-lump kinetic model of aromatic hydrosaturation are proposed. The study found that thermodynamics play a crucial role in UHDS, and also revealed the temperature dependence of organonitrogen inhibition on HDS.