Reactions involved

The main reactions that are involved during hydrotreating processes are:

1. 1. Hydrodesulphurization (HDS): HDS can occur by direct removal of sulfur as H₂S or unsaturated complex molecule may initially undergo partial hydrogenation followed by sulfur removal.

Among the sulfur compounds the approximate order of activity is RSH > R-S-S-R´> R-S-R´ > thiophenes. The reactivity of thiophenes decreases in the order thiophene > benzothiophenoe > dibenzothiophene > alkyl-benzothiophenes. The 4,6 dibenzothiophene is the most refractory of the sulfur compounds hence, most difficult to be removed.