Patent ID: 7419586
Filing Date: 2008-09-02
Classification: C10G

Abstract:
1. A process for hydrodesulfurizing olefinic naphtha feedstreams and retaining a substantial amount of the olefins, which feedstream boils in the range of about 50° F. (10° C.) to about 450° F. (232° C.) and contains organically-bound sulfur and an olefin content of at least about 5 wt. %, which process comprises: a) hydrodesulfurizing the olefinic naphtha feedstream in a first hydrodesulfurization stage in the presence of hydrogen and a hydrodesulfurization catalyst, at hydrodesulfurization reaction conditions including temperatures from about 232° C. (450° F.) to about 427° C. (800° F.), pressures of about 60 to about 800 psig (about 515 to about 5,617 kPa), and hydrogen treat gas rates of about 1000 to about 6000 standard cubic feet per barrel (about 178 to about 1,058 m b) conducting said sulfur-containing first product stream to a first separation zone operated at a temperature from about 93° C. (200° F.) to about 177° C. (350° F.) where it is contacted with a countercurrent flow of hydrogen treat gas to produce a first lower boiling naphtha product stream and a first higher boiling naphtha product stream, wherein the higher boiling product stream contains greater than about 50 wt. % of the sulfur from the first product stream; c) conducting said first lower boiling naphtha product stream to a second separation zone operated at a temperature at least 15° C. (27° F.) lower than that of said first separation stage wherein a second lower boiling naphtha product stream and a second higher boiling product stream are produced, which second higher boiling product stream contains substantially all of the sulfur from said first lower boiling naphtha product stream; d) conducting said second lower boiling product stream from said second separation stage to a third separation stage which is maintained at a temperature at least about 15° C. (27° F.) lower than that of said second separation stage thereby resulting in a hydrogen containing vapor recycle stream and a desulfurized naphtha product stream; e) conducting said first higher boiling naphtha product stream from said first separation zone and at least a portion of said second higher boiling naphtha stream from said second separation zone to a second hydrodesulfurization stage in the presence of hydrogen treat gas and a hydrodesulfurization catalyst, at hydrodesulfurization reaction conditions including temperatures from about 232° C. (450° F.) to about 427° C. (800° F.), pressures of about 60 to about 800 psig (about 515 to about 5,617 kPa), and hydrogen treat gas rates of about 1000 to about 6000 standard cubic feet per barrel (about 178 to about 1,068 m f) recycling at least a portion of the hydrogen containing vapor recycle stream from said third separation zone to said first hydrogenation stage; g) stripping substantially all remaining hydrogen from said desulfurized naphtha product stream from said third separation zone; and h) collecting said stripped desulfurized naphtha product stream.