Patent ID: 6824673
Filing Date: 2004-11-30
Classification: C10G

Abstract:
A multi stage process for hydrodesulfurizing and hydrogenating a distillate feedstock having a sulfur content greater than about 3,000 wppm, which process comprises:a) reacting said feedstream in a first hydrodesulfurization stage in the presence of a once through hydrogen-containing treat gas, said first hydrodesulfurization stage containing one or more reaction zones, each reaction zone operated at hydrodesulfurizing conditions and in the presence of a hydrodesulfurization catalyst, thereby resulting in a liquid product stream having a sulfur content less than about 3,000 wppm, wherein at least a portion of the hydrogen-containing treat gas for the first hydrodesulfurization zone is supplied from a source other than the present multi-stage process; b) passing the liquid product stream to a first separation zone wherein a vapor phase product stream and a liquid phase product stream are produced; c) passing the liquid phase product stream to a second hydrodesulfurization stage; d) reacting said liquid phase product stream in said second hydrodesulfurization stage in the presence of a hydrogen-containing treat gas cascaded from, or partially cascaded from, the next downstream stage herein, wherein the rate of introduction of the hydrogen portion of the treat gas in this second stage is less than or equal to 1.5 times the chemical hydrogen consumption in this second reaction stage, said second hydrodesulfurization stage containing one or more reaction zones operated at hydrodesulfurization conditions wherein each reaction zone contains a bed of first hydrodesulfurization catalyst, thereby resulting in a liquid product stream having less than about 100 wppm sulfur; e) passing the liquid product stream from said second hydrodesulfurization stage to a second separation zone wherein a vapor phase stream and a liquid phase stream are produced; f) collecting said vapor phase stream; g) passing said liquid phase stream to a stripping stage wherein said liquid phase stream is contacted with countercurrent flowing hydrogen-containing treat gas in the substantial absence of a catalyst thereby producing a stripped liquid phase stream; h) passing said stripped liquid phase stream from step e) to an aromatics hydrogenation stage; i) reacting said stripped liquid phase stream in said aromatics hydrogenation stage in the presence of a hydrogen-containing treat gas, said hydrogenation stage containing one or more reaction zones operated at aromatics hydrogenation conditions wherein each reaction zone contains a bed of aromatics hydrogenation catalyst comprising a zeolitic support material, thereby resulting in a liquid product stream having substantially reduced levels of sulfur and aromatics, and a hydrogen-containing vapor product stream that is cascaded to an upstream hydrodesulfurization stage; wherein said aromatics hydrogenation reaction stage contains two or more reaction zones operated at different temperatures wherein at least one of said two or more reaction zones is operated at a temperature at least about 25Â° C. lower than the other reaction zones; and j) combining the liquid product stream of step (h) with at least one of (i) one or more lubricity aid, (ii) one or more viscosity modifier, (iii) one or more antioxidant, (iv) one or more cetane improver, (v) one or more dispersant, (vi) one or more cold flow improver (vii) one or more metals deactivator, (viii) one or more corrosion inhibitor, (ix) one or more detergent, and (x) one or more distillate or upgraded distillate.