Selective hydroprocessing and mercaptan removal

• US 20030127362A1
• Filed: 10/18/2002
• Published: 07/10/2003
• Est. Priority Date: 04/18/2000
• Status: Abandoned Application

• Current Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Inventors: Halbert, Thomas R., Greeley, John P., Welch, Robert C.
• Application Number:
  US10/273,834
• Publication Number:
  US 20030127362A1
• Time in Patent Office: Days
• US Class Current: 208/212
• CPC Class Codes: C10G 67/0418 The hydrotreatment being a hydrorefining
• CPC Class Codes: C10G 67/12 including oxidation as the refining step in the absence of hydrogen
• CPC Class Codes: C10L 1/02 essentially based on components consisting of carbon, hydrogen, and oxygen only

Abstract

A process for the production of naphtha streams from cracked naphthas having sulfur levels which help meet future EPA gasoline sulfur standards (30 ppm range and below).

Claims

1. A method for producing a gasoline blendstock having a decreased amount of sulfur comprising the steps of:

(a) selectively hydroprocessing a petroleum feedstream comprising cracked naphtha and sulfur-containing species to produce a first naphtha product comprising mercaptan sulfur having more than 5 carbon atoms, olefins, non-mercaptan sulfur, and hydrogen gas;

(b) removing at least a portion of said hydrogen sulfide and at least a portion of said hydrogen gas from said first naphtha product to obtain a second naphtha product having a decreased amount of hydrogen sulfide and hydrogen gas;

(c) contacting said second naphtha product with a liquid extractant and removing or converting at least a portion of said mercaptan sulfur from said second naphtha product to obtain a third naphtha product having a decreased amount of said mercaptan sulfur; and

(d) fractionating said third naphtha product to obtain at least one higher boiling point product comprising at least a portion of said converted mercaptan sulfur and at least one lighter boiling point product.

2. The method of claim 1 wherein said lighter boiling point product has a boiling point below about 480°

F., and said higher boiling point product has a boiling point above about 480°

F.

3. The method of claim 1 wherein said first naphtha product contains less than 50 ppm non-mercaptan sulfur.

4. The method of claim 1 wherein said first product contains less than 30 wppm non-mercaptan sulfur.

5. The method of claim 1 wherein said removal step (c) is accomplished by a process selected from the group consisting of extraction, adsorption, fractionation, sweetening followed by fractionation, thermal decomposition and membrane separation.

6. The method according to claim 5 wherein said mercaptan sulfur is removed or converted by sweetening in the sweetening unit already existing with the base hydrotreating unit.

7. The method according to claim 1 wherein about 1% to about 100% of said hydrogen gas is removed from said first naphtha product.

8. The method according to claim 1 wherein step (d) is conducted in a disulfide fractionator.

9. The method according to claim 1 wherein step (d) is conducted in the existing stripper of the base hydrotreating unit.

10. The method of claim 2 wherein step (b) of claim 1 comprises:

(a) separating from said first naphtha product at least a portion of hydrogen gas and at least a portion of hydrogen sulfide in a separation drum to produce a naphtha product having reduced levels of hydrogen sulfide and hydrogen gas;

(b) passing said naphtha product having reduced levels of hydrogen sulfide and hydrogen gas to a monoethanolamine scrubber to produce a naphtha product having reduced levels of non-mercaptan sulfur; and

,

(c) regenerating said monoethanol amine.

11. The method of claim 8 or 9 wherein a hydrocarbon stream is injected into said existing stripper such that the flow of said hydrocarbon stream is countercurrent or co-current to the flow of the product stream from the mercaptan conversion reactor.

12. The method according to claim 11 wherein said hydrocarbon stream is diesel oil.