Method of reducing sulfur in hydrocarbon feedstock using a membrane separation zone

• US 7,267,761 B2
• Filed: 09/26/2003
• Issued: 09/11/2007
• Est. Priority Date: 09/26/2003
• Status: Active Grant

• Current Assignee: W R Grace & Company - CONN (Standard Industries Holdings, Inc.)
• Original Assignee: W R Grace & Company - CONN (Standard Industries Holdings, Inc.)
• Inventors: Balko, Jeffrey William
• Primary Examiner(s): Nguyen; Tam M.
• Application Number:
  US10/671,807
• Publication Number:
  US 20050067323A1
• Time in Patent Office: 1,446 Days
• Field of Search: 208/208.R, 208/211, 585/818, 585/819, 201/649, 201/650
• US Class Current: 208/208.00R
• CPC Class Codes: C10G 25/003 Specific sorbent material, not covered by C10G25/02 or C10G25/03
• CPC Class Codes: C10G 53/08 including at least one sorption step
• CPC Class Codes: C10G 53/16 plural parallel stages only
• CPC Class Codes: C10G 69/02 plural serial stages only
• CPC Class Codes: C10G 69/14 plural parallel stages only

Abstract

A membrane is used in combination with fractionation and hydrodesulfurization to reduce the sulfur content of hydrocarbon feeds, preferably sulfur-containing naphtha feeds. A membrane separation zone is employed to treat a fraction of effluent from a fractionation zone containing sulfur-containing non-aromatic hydrocarbons to produce a sulfur rich permeate and sulfur deficient retentate. The sulfur rich permeate and a second fraction of the fractionation zone, which contains sulfur-containing aromatic hydrocarbons, are further treated in a hydrodesulfurization zone. The stream from the hydrodesulfurization zone and the sulfur deficient retentate from the membrane separation zone are then processed as low sulfur hydrocarbon streams, especially those streams being processed in the manufacture of gasoline when the initial hydrocarbon stream is naphtha from a fluidized catalytic cracking unit.

Claims

1. A process for reducing sulfur content in a hydrocarbon feedstock containing sulfur, the process comprising:

(a) contacting the hydrocarbon feedstock with a Fractionation Zone to produce under catalytic distillation conditions at least Fraction (1) and Fraction (2), wherein each fraction contains sulfur, and Fraction (1) has a final boiling point that is lower than that of Fraction (2),

(b) contacting Fraction (1) with a Membrane Separation Zone, said Membrane Separation Zone containing a membrane having a sufficient flux and selectivity to separate a sulfur-enriched permeate fraction and a sulfur deficient retentate fraction, and said sulfur enriched permeate fraction being enriched in sulfur compared to Fraction (1);

(c) recovering the sulfur deficient retentate fraction;

(d) contacting said sulfur enriched permeate fraction of (b) and said Fraction (2) of (a), separately or as a combination, with a Desulfurization Zone to reduce the sulfur content of the sulfur enriched permeate fraction and Fraction (2); and

(e) recovering a hydrocarbon stream from the Desulfurization Zone wherein the hydrocarbon stream has a reduced sulfur content, relative to the sulfur-containing feedstock.

2. A process according to claim 1 wherein the membrane in (b) comprises a member selected from the group consisting of polyimide, polyurea-urethane, polysiloxane and combinations thereof.

3. A process according to claim 1 wherein the membrane in (b) comprises a polyurea-urethane.

4. A process according to claim 1 wherein the hydrocarbon feedstock is a naphtha feed.

5. A process according to claim 4 wherein the naphtha feed contains at least 150 ppm sulfur.

6. A process according to claim 4 wherein the naphtha feed is an effluent from a fluidized catalytic cracking unit.

7. A process according to claim 1 wherein Fraction (1) has a final boiling point in the range of about 50°

C. to about 200°

C.

8. A process according to claim 1 wherein Fraction (1) has a final boiling point in the range of about 50°

C. to about 130°

C.

9. A process according to claim 1 wherein Fraction (1) contains sulfur-containing aromatic hydrocarbons.

10. A process according to claim 7 wherein Fraction (1) contains sulfur-containing aromatic hydrocarbons.

11. A process according to claim 4 wherein Fraction (1) contains sulfur-containing aromatic hydrocarbons.

12. A process according to claim 1 wherein Fraction (1) contains sulfur-containing aromatic hydrocarbons.

13. A process according to claim 9 wherein Fraction (1) contains thiophene or alkylthiophene.

14. A process according to claim 10 wherein Fraction (1) contains thiophene or alkylthiophene.

15. A process according to claim 11 wherein Fraction (1) contains thiophene or alkylthiophene.

16. A process according to claim 12 wherein Fraction (1) contains thiophene or alkylthiophene.

17. A process according to claim 16 wherein Fraction (1) is substantially free of mercaptan-containing compound.

18. A process according to claim 1 wherein Fraction (2) contains a member selected from the group consisting of benzothiophene, alkylbenzothiophene, and thioethers.

19. A process according to claim 1 wherein the sulfur deficient retentate fraction of step (b) contains 70 ppm or less sulfur.

20. A process according to claim 1 wherein the Membrane Separation Zone operates under pervaporation conditions.

21. A process according to claim 1 wherein the membrane has a sulfur enrichment factor of at least 1.5.

22. A process according to claim 1 wherein sulfur deficient retentate fraction of (b) is transferred as a gasoline blend stock.

23. A process according to claim 1 wherein the Desulfurization Zone of (d) operates under hydrodesulfurization conditions.

24. A process according to claim 1 wherein the Desulfurization Zone of (d) operates under catalytic hydrodesulfurization conditions.

25. A process according to claim 24 wherein the sulfur content of reduced sulfur-containing hydrocarbon streams from the Desulfurization Zone in (f) is 50 ppm or less sulfur.