Carbon Dioxide Capture

• US 20100034724A1
• Filed: 06/19/2009
• Published: 02/11/2010
• Est. Priority Date: 06/20/2008
• Status: Active Grant

• Current Assignee: 1446881 Alberta Limited, Carbon Engineering ULC (Occidental Petroleum Corporation)
• Original Assignee: Carbon Engineering Limited Partnership
• Inventors: Keith, David, Mahmoudkhani, Maryam
• Granted Patent: US 8,119,091 B2
• Time in Patent Office: Days
• US Class Current: 423/438
• CPC Class Codes: B01D 2251/304 of sodium
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01D 53/77 Liquid phase processes
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: B01D 53/96 Regeneration, reactivation or recycling of reactants
• CPC Class Codes: C01D 1/04 Hydroxides
• CPC Class Codes: C01D 7/07 Preparation from the hydroxides
• CPC Class Codes: C01D 7/37 Densifying sodium carbonate
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

A method of carbon dioxide capture is disclosed. In a step (a) anhydrous sodium carbonate is separated from a first aqueous solution formed by reacting carbon dioxide and an aqueous solution of sodium hydroxide. In step (b) the anhydrous sodium carbonate is treated by causticization to generate carbon dioxide and sodium hydroxide. The first aqueous solution of step (a) is formed by scrubbing a gas containing carbon dioxide with an aqueous solution of sodium hydroxide.

Claims

1. A method, comprising:

(a) separating anhydrous sodium carbonate from a first aqueous solution formed by reacting carbon dioxide and sodium hydroxide; and

(b) causticizing the separated anhydrous sodium carbonate to generate carbon dioxide and sodium hydroxide.

2. A method of claim 1, wherein the causticizing comprises:

reacting the anhydrous sodium carbonate with sodium tri-titanate to produce carbon dioxide gas and sodium penta-titanate; and

regenerating sodium hydroxide and sodium tri-titanate from the sodium penta-titanate.

3. A method of claim 2, in which reacting with sodium tri-titanate is carried out at temperatures at or above the melting point of anhydrous sodium carbonate.

4. A method of claim 1, in which the first aqueous solution is formed by scrubbing a gas containing carbon dioxide with an aqueous solution of sodium hydroxide.

5. A method of claim 2, further comprising:

separating additional anhydrous sodium carbonate solution formed by reacting additional carbon dioxide with the sodium hydroxide remaining in the first aqueous solution after the first separation of anhydrous sodium carbonate; and

causticizing the additional anhydrous sodium carbonate to generate carbon dioxide and sodium hydroxide.

6. A method of claim 5, further comprising hydrolyzing the sodium penta-titanate.

7. A method of claim 1, in which separating further comprises:

(x) separating a hydrate of sodium carbonate from the first aqueous solution;

(y) dissolving the hydrate of sodium carbonate in a second aqueous solution and heating the second aqueous solution to a temperature at or above the transition temperature of monohydrate sodium carbonate and anhydrous sodium carbonate precipitation to produce the anhydrous sodium carbonate.

8. A method of claim 7, in which the concentration of sodium carbonate in the first aqueous solution is lower than the concentration of sodium carbonate in the second aqueous solution.

9. A method of any claim 7, in which separating further comprises cooling the first aqueous solution to separate the hydrate of sodium carbonate from the first aqueous solution.

10. A method of claim 7, in which the anhydrous sodium carbonate is produced at elevated pressure.

11. A method of claim 7, in which the hydrate of sodium carbonate comprises sodium carbonate decahydrate.

12. A method of claim 7, in which the pH of the first aqueous solution is high enough during causticizing to reduce co-crystallization of sodium bicarbonate.

13. A method of claim 1, in which the causticizing occurs in the presence of at least 10% CO₂.

14. A method of claim 1 in which the causticizing occurs in the presence of steam.

15. A method comprising:

(a) scrubbing a gas containing carbon dioxide with an aqueous solution of sodium hydroxide to react the carbon dioxide to form a first aqueous solution containing sodium carbonate;

(b) separating anhydrous sodium carbonate from the first aqueous solution; and

(c) treating the anhydrous sodium carbonate by causticization to generate carbon dioxide and sodium hydroxide.

16. A method of claim 15 further comprising:

treating the anhydrous sodium carbonate by causticization with sodium tri-titanate to generate carbon dioxide and sodium hydroxide.

17. A method comprising:

(a) scrubbing a gas containing carbon dioxide with an aqueous solution of alkali metal hydroxide resulting in a first aqueous solution containing alkali metal carbonate;

(b) separating anhydrous alkali metal carbonate from the first aqueous solution; and

(c) treating the anhydrous alkali metal carbonate by causticization to generate carbon dioxide and alkali metal hydroxide.

18. A method of generating carbon credits comprising:

(a) scrubbing a gas containing carbon dioxide with an aqueous solution of sodium hydroxide to react the carbon dioxide to form a first aqueous solution containing sodium carbonate;

(b) separating anhydrous sodium carbonate from the first aqueous solution;

(c) treating the anhydrous sodium carbonate by causticization to generate carbon dioxide and sodium hydroxide thereby generating carbon credits based on the carbon dioxide removed from the gas.