Sorbents for the oxidation and removal of mercury

• US 8,821,819 B2
• Filed: 08/14/2013
• Issued: 09/02/2014
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Midwest Energy Emissions Corp.
• Original Assignee: Energy & Environmental Research Center (GE Aerospace)
• Inventors: Olson, Edwin S., Holmes, Michael J., Pavlish, John Henry
• Primary Examiner(s): ORLANDO, AMBER ROSE
• Application Number:
  US13/966,768
• Publication Number:
  US 20140056787A1
• Time in Patent Office: 384 Days
• Field of Search: 951/34, 951/42, 423/210, 110/345
• US Class Current: 423/210
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/25 Coated, impregnated or composite adsorbents
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/10 with dispersed adsorbents
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01J 20/02 comprising inorganic material
• CPC Class Codes: B01J 20/0262 Compounds of O, S, Se, Te
• CPC Class Codes: B01J 20/027 Compounds of F, Cl, Br, I
• CPC Class Codes: B01J 20/04 comprising compounds of alkali metals, alkaline earth metals or magnesium
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/10 comprising silica or silicate
• CPC Class Codes: B01J 20/106 Perlite
• CPC Class Codes: B01J 20/12 Naturally occurring clays or bleaching earth
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/22 comprising organic material
• CPC Class Codes: B01J 20/223 containing metals, e.g. organo-metallic compounds, coordination complexes
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/28016 Particle form
• CPC Class Codes: B01J 20/3416 : of sorbents or filter aids comprising free carbon, e.g. activated carbon
• CPC Class Codes: B01J 2220/42 : Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: Y10S 95/901 : Activated carbon

Abstract

A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

Claims

1. A method for separating mercury in a gas stream comprising:

contacting carbon including at least some graphene and a promoter selected from the group consisting of an elemental halogen, a group V halide, a group VI halide, a hydrohalide, and combinations thereof, to form a promoted sorbent particulate;

modifying at least some edge structures of at least some of the graphene of the carbon for forming carbocations for the promoted sorbent for accepting at least some electrons from mercury atoms of the mercury; and

contacting the mercury-containing gas stream and the promoted sorbent particulate for forming a stabilized mercury-sorbent particulate from the gas stream.

2. The method of claim 1, wherein the promoter is an elemental halogen or a hydrohalide, or a combination.

3. The method of claim 2 wherein the elemental halogen is bromine, or wherein the hydrohalide is hydrogen bromide, or both.

4. The method of claim 1, wherein the promoter is a group V halide or a group VI halide.

5. The method of claim 4 wherein the promoter is PBr₃ or SCl₂.

6. The method of claim 1 further comprising contacting the promoted sorbent particulate, the mercury-containing gas stream, or both, with an alkaline material.

7. The method of claim 1, wherein the promoter is in gaseous form.

8. The method of claim 1, wherein the promoter is in an organic solvent.

9. The method of claim 8, wherein the organic solvent is a hydrocarbon, a chlorinated hydrocarbon, or supercritical carbon dioxide.

10. The method of claim 1, wherein the mercury-containing gas stream is a product of coal or petroleum combustion.

11. A method for separating mercury in a gas stream comprising:

contacting carbon including at least some graphene and a promoter including at least one of bromine, bromine compounds, and combinations thereof to form a promoted sorbent particulate;

modifying at least some edge structures of the graphene for forming carbocations for accepting some electrons from mercury atoms of the mercury; and

contacting the mercury-containing gas stream and the a promoted sorbent particulate for forming a stabilized mercury-sorbent particulate from the gas stream.

12. The method of claim 11, wherein the promoter is an elemental halogen or a hydrohalide, or a combination.

13. The method of claim 12 wherein the elemental halogen is bromine, or wherein the hydrohalide is hydrogen bromide, or both.

14. The method of claim 11, wherein the promoter is a group V halide or a group VI halide.

15. The method of claim 14 wherein the promoter is PBr₃ or SBr₂.

16. The method of claim 11 further comprising contacting the promoted sorbent particulate, the mercury-containing gas stream, or both, with an alkaline material.

17. The method of claim 11, wherein the promoter is in gaseous form.

18. The method of claim 11, wherein the promoter is in an organic solvent.

19. The method of claim 18, wherein the organic solvent is a hydrocarbon, a chlorinated hydrocarbon, or supercritical carbon dioxide.

20. The method of claim 11, wherein the mercury-containing gas stream is a product of coal or petroleum combustion.