DEEP DESULFURIZATION OF DISTILLATES

In response to the need for production of very low-sulfur distillates (< 0.05 wt % sulfur) in medium pressure hydrodesulfurization (HDS) units, we studied desulfurization of individual feed components. A total of eight feedstock components were evaluated, including straight-run gas oil (GO), coker gas oil (CGO), and FCC light cycle oil (LCO). The results show that, under typical HDS unit conditions (2.5 liquid hourly space velocity (LHSV), 625 psig, and 1500 ft3(STP)/barrel H-2) over a commercial CoMo/Al2O3 Catalyst, the temperature requirement for desulfurization to 0.05 wt % sulfur can be correlated with the concentration of 600+ degrees-F sulfur and total nitrogen in the feed, independent of the feedstock source. A simple empirical correlation was developed to describe the temperature required for desulfurization of distillates to 0.05 wt % sulfur. This correlation can be used by refineries to rank feed components and to develop a strategy for manufacturing 0.05 wt % sulfur diesel fuel.