No abstract

To develop a process for upgrading heavy residual oils, experimental investigations were conducted to study the effect of presulfiding on performance of hydrodesulfurization (HDS) catalyst: activity and life. The authors used straight gas oil from Khafji crude for studied on presulfiding of (Ni)-Co-Mo/Al2O3 type catalysts. The results indicated that presulfiding affected catalyst life, but not catalyst activity, in the residual oil HDS. One of the effects of presulfiding was the suppression of coke deposition. When Co-Mo/Al2O3 type catalysts having smaller pores were employed, presulfiding gave longer catalyst life; while those having larger pores did not improve life because of the greater effectiveness factor. When Ni-Co-Mo/Al2O3 type catalysts were employed, the magnitude of the effectiveness factors did not play a meaningful role. Presulfiding of Ni-Co-Mo/Al2O3 type catalysts also suppressed removal of vanadium. This effect was not observed with the use of Co-Mo/Al2O3 type catalysts.