Kinetic Models Study of Hydrodesulphurization Vacuum Distillate Reaction

Abstract

This study deals with kinetics of hydrodesulphurization (HDS) reaction of vacuum gas oil (611-833) K which was distillated from Kirkuk crude oil and which was obtained by blending the fractions, light vacuum gas oil (611 – 650) K, medium vacuum gas oil (650- 690) K, heavy vacuum gas oil (690-727) K and very heavy vacuum gas oil (727-833) K. The vacuum gas oil was hydrotreated on a commercial cobalt-molybdenum alumina catalyst presulfied at specified conditions in a laboratory trickle bed reactor. The reaction temperature range (583-643) K,liquid hourly space velocity range (1.5-3.75) h-1 and hydrogen pressure was kept constant at 3.5 MPa with hydrogen to oil ratio about 250 lt/lt. The conversion results for desulphurization reaction appeared to obey the second order reaction. According to this model, the rate constants for desulphurization reaction were determined. Finally, the apparent activation energy (Ea), enthalpy of activation ( H*) and entropy ( S*) were calculated based on the values of rate constant (k2) and were equal 80.3792 KJ/mole, 75.2974 KJ/mole and 197.493 J/mole, respectively.