Method for reducing mercaptans in hydrocarbons

Patent metadata

Field	Value
Publication number	US-9296956-B2
Application number	US-201113281114-A
Country	US
Kind code	B2
Filing date	Oct 25, 2011
Priority date	Oct 28, 2010
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A method for reducing mercaptan concentration in a crude oil is disclosed. The method comprises contacting the crude with a treating solution comprising a hypochlorite solution, whereby the mercaptan sulfur is oxidized and converted to at least one sulfur oxoacid or salt thereof, yielding a treated crude oil having less than 50 ppm mercaptan sulfur and residual organic chloride. The treated crude oil containing residual organic chloride is brought in contact with a caustic solution at a molar ratio of caustic to chloride of 0.1:1 to 50:1, generating an upgraded crude oil with less than 10 ppm organic chloride. In one embodiment, the spent treating solution is recycled to form a regenerated hypochlorite stream for use in the treatment solution.

First claim

The invention claimed is:

1. A method for selectively treating a crude oil feed containing mercaptans to remove mercaptans while retaining other non-mercaptan sulfur species, comprising:
contacting a crude oil feed containing mercaptans and non-mercaptan sulfur species with a treatment solution comprising a hypochlorite, wherein the crude oil feed is not a petroleum distillate, wherein the molar ratio of hypochlorite to mercaptans in the crude oil feed ranges from 1:1 to 10:1, whereby the hypochlorite oxidizes the mercaptans generating a treated crude oil having a reduced concentration of mercaptans of less than 50 ppm and a first concentration of chloride and a spent treatment solution containing at least a sulfur oxoacid or salt thereof, having the formula [RSO x ] n Y, wherein R is a hydrocarbyl group; x is an integer from 1 to 3; n is 1 or 2; and Y is hydrogen, an alkaline metal, or alkaline earth metal and wherein the majority of mercaptans are removed from the treated crude oil and the majority of non-mercaptan sulfur species remain in the treated crude oil;
recovering the spent treatment solution and the treated crude oil;
contacting the treated crude oil with a caustic solution at a molar ratio of caustic to organic chloride of 0.1:1 to 50:1, generating a spent alkaline solution and an upgraded crude oil having a reduced concentration of mercaptan and a reduced concentration of organic chloride;
recovering the spent alkaline solution and the upgraded crude oil having a reduced concentration of mercaptan and a reduced concentration of organic chloride of less than 10 ppm by weight.

2. The method of claim 1 , further comprising treating the spent treatment solution via at least one of filtration and ion exchange to generate a first brine solution containing at least 99 wt. % as NaCl and water.

3. The method of claim 2 , further comprising regenerating the first brine solution to form a regenerated hypochlorite stream.

4. The method of claim 3 , further comprising routing the regenerated hypochlorite stream for use in the treatment solution.

5. The method of claim 3 , wherein the first brine solution is regenerated by electrolyzing in an electrolyzer cell to form the regenerated hypochlorite stream.

6. The method of claim 2 , further comprising removing at least 20% of water from the first brine solution to produce a second brine solution and electrolyzing the second brine solution in an electrolyzer cell.

7. The method of claim 3 , further comprising adding a second brine solution to the electrolyzer cell to form the regenerated hypochlorite stream for use in the treatment solution.

8. The method of claim 1 , wherein the crude oil feed is contacted with a treatment solution comprising sodium hypochlorite having a concentration ranging from 1 to 15% by weight.

9. The method of claim 1 , wherein the treated crude oil is contacted with a caustic solution comprising sodium hydroxide having a concentration of sodium hydroxide ranging from 0.001N to 10N.

10. The method of claim 1 , wherein the crude oil feed is contacted with the treatment solution in a contact zone comprising at least one of a packed tower, a bubble tray column, a stirred mixing tank, a fiber contactor, and a rotating disc contactor.

11. The method of claim 1 , wherein the crude oil feed is contacted with a treatment solution comprising a regenerated hypochlorite stream obtained from a hypochlorite regeneration unit.

12. The method of claim 1 , wherein the crude oil feed is contacted with the treatment solution in a contact zone comprising fibers and wherein the contact of the crude oil feed with the treatment solution forms an admixture that flows over and along the fibers.

13. The method of claim 1 , wherein the treated crude oil is recovered in a separation zone comprising fibers, and wherein the spent treatment solution and the treated crude oil form an admixture that flows over and along the fibers to form two liquid layers, a lower layer comprising the spent treatment solution and an upper layer comprising the treated crude oil.

14. The method of claim 1 , wherein the treated crude oil is contacted with the caustic solution in a contact zone comprising fibers and wherein the contact of the treated crude oil with the caustic solution forms an admixture that flows over and along the fibers.

15. The method of claim 1 , wherein the upgraded crude oil is recovered in a separation zone comprising fibers, and wherein the spent alkaline solution and the upgraded crude oil form an admixture that flows over and along the fibers to form two liquid layers, a lower layer comprising the spent alkaline solution and an upper layer comprising the upgraded crude oil.

16. A method for selectively treating a crude oil containing mercaptans while retaining other non-mercaptan sulfur species in the crude oil feed, comprising:
combining a sodium hypochlorite solution with a least a base to form a treatment solution having a pre-select pH;
contacting a crude oil feed which is not a petroleum distillate with the treatment solution comprising the sodium hypochlorite at a pre-select pH under intimate contact conditions sufficient for the hypochlorite to oxidize the mercaptans generating a treated crude oil having a reduced concentration of mercaptans of less than 50 ppm by weight and a first concentration of chloride and a spent treatment solution and wherein the majority of mercaptans are removed by the treated crude oil and the majority of non-mercaptan sulfur species remain in the treated crude oil;
recovering the spent treatment solution and the treated crude oil;
separating the spent treatment solution and the treated crude oil to recover the spent treatment solution and the treated crude oil as separate streams;
contacting the treated crude oil stream with a caustic solution under mixing conditions sufficient to generate a spent alkaline solution and an upgraded crude oil having less than 50 ppm by weight, mercaptan and less than 10 ppm by weight organic chloride;
separating the spent alkaline solution and the upgraded crude oil;
treating the spent treatment solution to generate a brine solution comprising at least 99 wt. % as sodium chloride in solution;
regenerating the brine solution to form a hypochlorite stream for use in the treatment solution.

17. The method of claim 16 , wherein the crude oil and the treatment solution are intimately contacted by a contacting method selected from non-dispersive and dispersive contacting methods.

18. The method of claim 17 , wherein the non-dispersive contacting method is selected from packed inert particle beds and fiber film contactors.

19. The method of claim 16 , wherein the treated crude oil stream and the caustic solution are intimately contacted by a contacting method selected from non-dispersive and dispersive contacting methods.

Assignees

• Li Lin
• He Zunqing
• Zhou Zhen
• Ng King T
• Hajdu Paul E
• Chevron Usa Inc

Inventors

• Li Lin
• He Zunqing
• Zhou Zhen
• Ng King T
• Hajdu Paul E

Classifications

• C10G17/07 Primary

  using halogen acids or oxyacids of halogen (acids generating halogen C10G27/02) · CPC title

• C10G2300/202

  Heteroatoms content, i.e. S, N, O, P · CPC title

• C10G53/10

  including at least one acid-treatment step · CPC title

• C10G19/02

  with aqueous alkaline solutions · CPC title

• C10G2300/1033

  Oil well production fluids · CPC title