Development of a Mathematical Model for Vacuum Gas Oil Hydrotreating Considering the Kinetics of Desulfurization and Denitrogenation

A mathematical model is developed to describe the hydrotreating of vacuum gas oil, based on the transformation of individual sulfur- and nitrogen-containing compounds. The study presents an analysis of changes in the composition of nitrogen- and sulfur-containing compounds in vacuum gas oil during hydrotreatment in an industrial KT-1/1 unit. The results indicate that the degree of desulfurization does not exceed 93 rel %, with the products containing only dibenzothiophene homologs and benzonaphthothiophenes. Structural modifications in the average molecular composition of high- and low-molecular-weight nitrogenous bases result from hydrogenolysis of C–N and C–S bonds, hydrogenation of aromatic structures, and destruction of aliphatic molecular frameworks. The findings reveal that neutral and basic nitrogen compounds exhibit an inhibitory effect on the hydrodesulfurization of dibenzothiophene and benzonaphthothiophene derivatives, potentially due to competitive adsorption at the catalyst’s active sites. Using the developed mathematical model, the study demonstrates the influence of temperature on the residual sulfur and nitrogen content in vacuum gas oil hydrotreatment products.