Kinetics towards mechanism and real operation for ultra-deep
hydrodesulfurization and hydrodenitrogenation of diesel
Abstract
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 nitrogen inhibition to HDS, for
less than 300℃ the nitrogen inhibition becomes even more potent despite
nitrogen removal by HDN reactions. Subsequently, the HDS kinetics of
total sulfur are deciphered as multi stages exist in the whole reaction
coordinate. Accordingly, a four-stage conceptual model involving
mechanism and rate laws is proposed to offer a better understanding of
nitrogen inhibition, thermodynamics and kinetics in UHDS.