Separation of carbon dioxide (CO2) from gas mixtures by calcium based reaction separation (CaRS-CO2) process

• US 20060093540A1
• Filed: 10/20/2005
• Published: 05/04/2006
• Est. Priority Date: 02/06/2003
• Status: Active Grant

• Current Assignee: Ohio State University
• Original Assignee: Ohio State University
• Inventors: Gupta, Himanshu, Fan, Liang-Shih, Iyer, Mahesh V.
• Granted Patent: US 7,618,606 B2
• Time in Patent Office: Days
• US Class Current: 423/247
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2253/10 Inorganic adsorbents
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/508 by treating the gases with solids
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/06 comprising oxides or hydroxides of metals not provided for in group B01J20/04
• CPC Class Codes: B01J 20/28057 Surface area, e.g. B.E.T specific surface area
• CPC Class Codes: B01J 20/28071 being less than 0.5 ml/g
• CPC Class Codes: B01J 20/3085 Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
• CPC Class Codes: B01J 20/3433 of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425
• CPC Class Codes: B01J 20/3466 with steam
• CPC Class Codes: B01J 20/3483 by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
• CPC Class Codes: B01J 8/06 in tube reactors; the solid particles being arranged in tubes
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01F 11/06 of carbonates
• CPC Class Codes: C01P 2002/32 spinel-type (AB2O4)
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2006/12 : Surface area
• CPC Class Codes: C01P 2006/14 : Pore volume
• CPC Class Codes: C01P 2006/17 : Pore diameter distribution
• CPC Class Codes: C10J 2300/0996 : Calcium-containing inorganic materials, e.g. lime
• CPC Class Codes: C10J 2300/1807 : Recycle loops, e.g. gas, solids, heating medium, water
• CPC Class Codes: C10J 3/482 : Gasifiers with stationary fluidised bed
• CPC Class Codes: C10K 1/024 : by filtration
• CPC Class Codes: C10K 3/04 : reducing the carbon monoxide content , e.g. water-gas shift [WGS]
• CPC Class Codes: H01M 2008/1293 : Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 8/0668 : Removal of carbon monoxide or carbon dioxide
• CPC Class Codes: Y02C 20/40 : of CO2
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 20/151 : Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

A reaction-based process has been developed for the selective removal of carbon dioxide (CO₂) from a multicomponent gas mixture to provide a gaseous stream depleted in CO₂ compared to the inlet CO₂ concentration in the stream. The proposed process effects the separation of CO₂ from a mixture of gases (such as flue gas/fuel gas) by its reaction with metal oxides (such as calcium oxide). The Calcium based Reaction Separation for CO₂ (CaRS—CO₂) process consists of contacting a CO₂ laden gas with calcium oxide (CaO) in a reactor such that CaO captures the CO₂ by the formation of calcium carbonate (CaCO₃). Once “spent”, CaCO₃ is regenerated by its calcination leading to the formation of fresh CaO sorbent and the evolution of a concentrated stream of CO₂. The “regenerated” CaO is then recycled for the further capture of more CO₂. This carbonation-calcination cycle forms the basis of the CaRS—CO₂ process. This process also identifies the application of a mesoporous CaCO₃ structure, developed by a process detailed elsewhere, that attains >90% conversion over multiple carbonation and calcination cycles. Lastly, thermal regeneration (calcination) under vacuum provided a better sorbent structure that maintained reproducible reactivity levels over multiple cycles.

Claims

1. A method for separating carbon dioxide from a flow of gas comprising carbon dioxide, said method comprising the steps of:

directing said flow of gas to a gas-solid contact reactor, said gas-solid contact reactor containing at least one sorbent, said at least one sorbent comprising at least one metal oxide;

reacting said carbon dioxide with said at least one sorbent so as to remove said carbon dioxide from said flow of gas, thereby converting said at least one sorbent into spent sorbent;

calcining said spent sorbent so as to liberate said carbon dioxide from said spent sorbent, thereby regenerating said sorbent; and

repeating the aforementioned steps.

2. The method according to claim 1 wherein said at least one metal oxide is selected from the group consisting of:

ZnO, MgO, MnO₂, NiO, CuO, PbO, and CaO.

3. The method according to claim 1 wherein said spent sorbent is a metal carbonate.

4. The method according to claim 1 wherein said sorbent has a sorption capacity of at least about 70 grams of carbon dioxide per kilogram of sorbent.

5. The method according to claim 1 wherein said sorbent has a sorption capacity of at least about 300 grams of carbon dioxide per kilogram of sorbent.

6. The method according to claim 1 wherein said sorbent has substantially the same sorption capacity after calcining as said sorbent had prior to adsorbing said carbon dioxide.

7. The method according to claim 1 wherein said calcining is performed under at least partial vacuum.

8. The method according to claim 1 wherein said calcining is performed by steam.

9. A facility practicing the method according to claim 1.

10. A method for separating carbon dioxide from a flow of gas comprising carbon dioxide, said method comprising the steps of:

directing said flow of gas to a first gas-solid contact reactor, said first gas-solid contact reactor containing at least one sorbent, said sorbent comprising at least one metal oxide;

reacting said carbon dioxide in said flow of gas on said sorbent in said first gas-solid contact reactor so as to remove said carbon dioxide from said flow of gas;

directing said flow of gas to a second gas-solid contact reactor when said sorbent in said first gas-solid contact reactor is spent thereby forming spent sorbent, said second gas-solid contact reactor containing at least one sorbent, said sorbent comprising at least one metal oxide;

reacting said carbon dioxide in said flow of gas on said sorbent in said second gas-solid contact reactor so as to remove said carbon dioxide from said flow of gas;

calcining said spent sorbent from said first gas-solid contact reactor so as to generate carbon dioxide and to regenerate said sorbent;

directing said flow of gas to said first gas-solid contact reactor when said sorbent in said second gas-solid contact reactor is spent, thereby forming spent sorbent; and

calcining said spent sorbent from said second gas-solid contact reactor so as to generate carbon dioxide and to regenerate said sorbent.

11. The method according to claim 10 wherein said calcining of said spent sorbent from said first gas-solid contact reactor is performed under at least partial vacuum.

12. The method according to claim 10 wherein said calcining of said spent sorbent from said first gas-solid contact reactor is performed by steam.

13. The method according to claim 10 wherein said calcining of said spent sorbent from said second gas-solid contact reactor is performed under at least partial vacuum.

14. The method according to claim 10 wherein said calcining of said spent sorbent from said second gas-solid contact reactor is performed by steam.

15. The method according to claim 10 wherein said at least one metal oxide is selected from the group consisting of:

ZnO, MgO, MnO₂, NiO, CuO, PbO, and CaO.

16. The method according to claim 10 wherein said sorbent has a sorption capacity of at least about 70 grams of carbon dioxide per kilogram of sorbent.

17. The method according to claim 10 wherein said sorbent has a sorption capacity of at least about 300 grams of carbon dioxide per kilogram of sorbent.

18. The method according to claim 10 wherein said sorbent has substantially the same sorption capacity after calcining as said sorbent had prior to adsorbing said carbon dioxide.

19. A facility practicing the method according to claim 10.

20. A method for regenerating a spent sorbent for carbon dioxide, said method comprising the steps of:

providing a spent sorbent, said spent sorbent comprising metal carbonate; and

calcining said spent sorbent so as to liberate carbon dioxide gas and so as to regenerate said spent sorbent thereby forming a sorbent comprising a metal oxide.