Hydrodesulfurization Kinetics of Middle Distillates: A Four-Lumping Model with Consideration of Nitrogen and Aromatics Inhibitions

Abstract

The objective of the present study is to develop a better hydrodesulfurization (HDS) kinetic model on the basis of a fundamental and comprehensive understanding of the different HDS reactivities of various sulfur compounds in middle distillates and the inhibition effects of the coexisting nitrogen and aromatic compounds. Five middle distillates blended from straight run gas oil, heavy gas oil, and coker gas oil were hydrodesulfurized over a commercial catalyst at 300 °C, 4.0 MPa H2 pressure, a H2/oil volume ratio of 200, and different liquid hourly space velocities. Identification and quantification of sulfur compounds in the feedstocks and their hydrodesulfurized products were conducted by using GC-PFPD to classify the sulfur compounds into four groups according to their molecular structures and reactivities. It was found that the HDS of each sulfur group follows pseudo-first-order kinetics. Correlation of the obtained first-order rate constants with both the nitrogen concentration and the feedstock dens...