Amine promotion for CO2 capture

• US 9,707,512 B2
• Filed: 11/21/2013
• Issued: 07/18/2017
• Est. Priority Date: 12/21/2012
• Status: Active Grant

• Current Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Inventors: Kortunov, Pavel, Siskin, Michael
• Primary Examiner(s): NASSIRI MOTLAGH, ANITA
• Application Number:
  US14/085,999
• Publication Number:
  US 20140205525A1
• Time in Patent Office: 1,335 Days
• Field of Search: None
• CPC Class Codes: B01D 2252/20431 Tertiary amines
• CPC Class Codes: B01D 2252/602 Activators, promoting agents, catalytic agents or enzymes
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: C10L 2290/541 Absorption of impurities during preparation or upgrading of a fuel
• CPC Class Codes: C10L 3/104 Carbon dioxide
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

Promoter amines are used to enhance CO₂ uptake by sterically hindered or tertiary amines. The promoter amines can be cyclic amines, including aromatic cyclic amines or bridged cyclic amines. The combination of a promoter amine plus a sterically hindered or tertiary amines allows for improved uptake kinetics while reducing or minimizing the amount of formation of carbamate salts. The promoted sterically hindered or tertiary amines can be used as part of a CO₂ capture and release system that involves a phase transition from a solution of amine-CO₂ products to a slurry of amine-CO₂ precipitate solids.

Claims

1. A method for separating carbon dioxide from a gas stream, comprising:

contacting a gas stream containing CO₂ in a sorption zone with a sorption solution comprising a promoter amine, wherein the promoter amine comprises a bridged derivative of piperidine or piperazine and at least one of a sterically hindered amine and a tertiary amine, the sorption solution having a total amine concentration of at least about 3.0 M, at a temperature of at least 10°

C. to sorb at least a portion of the CO₂ into the sorption solution and form a rich stream of the sorbed CO₂ in the sorption solution comprising one or more amine-CO₂ reaction products dissolved in the solution;

passing the rich stream from the sorption zone to a second zone and precipitating at least a portion of the amine-CO₂ reaction products to form a precipitate slurry;

separating the precipitate slurry to form a portion enriched in precipitate solids and a first recycle stream, the first recycle stream comprising a majority of the solvent from the precipitate slurry; and

passing the portion enriched in precipitate solids to one or more regeneration zones and desorbing the sorbed carbon dioxide as gas to form a second recycle stream, the second recycle stream containing a lower concentration of carbon dioxide than the rich stream and containing an increased concentration of total amine relative to the rich stream,

wherein the aqueous sorption solution comprises at least a portion of the first recycle stream and at least a portion of the second recycle stream.

2. The method of claim 1, wherein the sterically hindered amine comprises an alkanolamine or an aminoether.

3. The method of claim 1, wherein the tertiary amine comprises an alkanolamine.

4. The process according to claim 1, wherein the total sterically hindered amine concentration or the total tertiary amine concentration in the sorption solution is at least about 2.5 M.

5. The process according to claim 1, wherein the total sterically hindered amine or the total tertiary amine concentration in the sorption solution is from about 5.0 M to about 8.0 M.

6. The process according to claim 1, wherein the promoter amine concentration in the amine solution is from 0.1 M to about 1.5 M.

7. The process according to claim 1, wherein the promoter amine concentration in the amine solution is about 9 wt % or less.

8. The process according to claim 1, wherein the CO₂ is contacted with the amine solution in the sorption zone at a temperature of about 25°

C. to about 45°

C.

9. The process according to claim 1, wherein the rich stream has a carbon dioxide loading of at least 0.4 mol CO₂ per mol of amine.

10. The process according to claim 1, wherein the CO₂ is contacted with the amine solution in the sorption zone at a carbon dioxide partial pressure of at least 0.025 bar.

11. The process according to claim 1, wherein the rich stream has a viscosity of about 10 cP or less.

12. The process according to claim 1, wherein the sorbed CO₂ is desorbed from the rich stream in at least one regeneration zone at a temperature higher than the temperature of the sorption zone.

13. The process according to claim 12, wherein the sorbed CO₂ is desorbed from the rich amine stream in at least one regeneration zone at a temperature of 95°

C. or less.

14. The process according to claim 12, wherein the sorbed CO₂ is desorbed from the rich amine stream in at least one regeneration zone at a temperature of at least about 120°

C.

15. The process according to claim 1, wherein the at least one regeneration zone comprises a flash desorption regeneration zone.

16. The process according to claim 1, wherein at least 70 wt % of the precipitate solids comprise a bicarbonate salt.

17. The process according to claim 1, wherein the CO₂-containing gas stream is contacted with the sorption solution at a temperature that is greater than a temperature in the precipitation zone by 20°

C. or less.

18. The process according to claim 1, wherein the sorption solution comprises an aqueous sorption solution, a non-aqueous sorption solution, or a combination thereof.

19. A method for separating carbon dioxide from a gas stream, comprising:

contacting a gas stream containing carbon dioxide in a sorption zone with an aqueous sorption solution comprising a promoter amine and a sterically hindered amine, the sorption solution having a total amine concentration of at least about 3.0 M, at a temperature of at least 10°

C. to sorb at least a portion of the carbon dioxide into the sorption solution and form a rich stream of the sorbed carbon dioxide in the sorption solution comprising amine-carbon dioxide reaction products dissolved in the solution;

passing the rich stream from the sorption zone to one or more regeneration zones and desorbing the sorbed carbon dioxide as gas to form a recycle stream, the recycle stream containing a lower concentration of carbon dioxide than the rich stream and containing an increased concentration of amine relative to the rich stream, the aqueous sorption solution comprising at least a portion of the recycle stream,

wherein the promoter amine comprises a bridged derivative of piperidine or piperazine.

20. The method of claim 19, wherein the sterically hindered amine comprises an alkanolamine or an aminoether.

21. A method for separating carbon dioxide from a gas stream, comprising:

contacting a gas stream containing carbon dioxide in a sorption zone with an aqueous sorption solution comprising a tertiary amine and about 9 wt % or less of a promoter amine, the sorption solution having a total amine concentration of at least about 3.0 M, at a temperature of at least 10°

C. to sorb at least a portion of the carbon dioxide into the sorption solution and form a rich stream of the sorbed carbon dioxide in the sorption solution comprising amine-carbon dioxide reaction products dissolved in the solution;

passing the rich stream from the sorption zone to one or more regeneration zones and desorbing the sorbed carbon dioxide as gas to form a recycle stream, the recycle stream containing a lower concentration of carbon dioxide than the rich stream and containing an increased concentration of amine relative to the rich stream, the aqueous sorption solution comprising at least a portion of the recycle stream, wherein the promoter amine comprises a bridged derivative of piperidine or piperazine.