Sorbents for the oxidation and removal of mercury

Abstract

A promoted carbon and/or non-carbon base sorbent are described that are highly effective for the removal of mercury from flue gas streams. The promoted sorbent comprises a carbon and/or non-carbon base sorbent that has reacted with and contains forms of halogen and halides. Optional components may be added to increase and/or preserve reactivity and mercury capacity. These may be added directly with the base sorbent, or in-flight within a gas stream (air, flue gas, etc.), to enhance base sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The promoted sorbent can be regenerated and reused. Base sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active base sorbent into the mercury contaminated gas stream are described.

1 . (canceled) 
     
     
         2 . A method of separating mercury from a mercury-containing gas, the method comprising:
 combusting in a combustion chamber coal fed to the combustion chamber to provide the mercury-containing gas, wherein the combustion chamber comprises the coal and a halogen or halide promoter, a promoter precursor that transforms into the promoter, or a combination thereof, added to the coal, added to the combustion chamber, or a combination thereof,   adding a sorbent comprising a carbon sorbent material and/or a non-carbon sorbent material into the mercury-containing gas downstream of the combustion chamber;   contacting mercury in the mercury-containing gas with the sorbent; and   separating the sorbent from the mercury-containing gas;   wherein the halogen or halide promoter, the promoter precursor that transforms into the promoter, or a combination thereof, added to the coal, added to the combustion chamber, or a combination thereof, is about 1 g to about 30 g per 100 g of the sorbent added to the mercury-containing gas.   
     
     
         3 . The method of  claim 2 , comprising removing greater than 70 wt % of the mercury in the mercury-containing gas. 
     
     
         4 . The method of  claim 2 , wherein the halogen or halide promoter, the promoter precursor that transforms into the promoter, or a combination thereof, is added to the coal. 
     
     
         5 . The method of  claim 2 , wherein the halogen or halide promoter, the promoter precursor that transforms into the promoter, or a combination thereof, is added to the combustion chamber. 
     
     
         6 . The method of  claim 2 , wherein the sorbent comprises the carbon sorbent material. 
     
     
         7 . The method of  claim 6 , wherein the carbon sorbent material comprises activated carbon. 
     
     
         8 . The method of  claim 7 , wherein the activated carbon comprises powdered activated carbon, granular activated carbon, or a combination thereof. 
     
     
         9 . The method of  claim 2 , wherein the sorbent comprises the non-carbon sorbent material. 
     
     
         10 . The method of  claim 9 , wherein the non-carbon material comprises a porous felsic material, a vesicular felsic material, a porous basaltic material, a vesicular basaltic material, a clay-based compound, an alkaline compound, a calcium hydroxide compound, a sodium acetate compound, a bicarbonate compound, or a combination thereof. 
     
     
         11 . The method of  claim 2 , wherein the sorbent comprises a combination of the carbon sorbent material and the non-carbon sorbent material. 
     
     
         12 . The method of  claim 2 , wherein the halogen or halide promoter, the promoter precursor that transforms into the promoter, or a combination thereof, is a halogen or halide compound. 
     
     
         13 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises Br − , Br 2 , HBr, or a combination thereof. 
     
     
         14 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises Br −  and is a bromide compound. 
     
     
         15 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises HBr. 
     
     
         16 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises Cl − , Cl 2 , HCl, or a combination thereof. 
     
     
         17 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises Cl −  and is a chloride compound. 
     
     
         18 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises I − , I 2 , HI, or a combination thereof. 
     
     
         19 . The method of  claim 2 , wherein the halogen or halide promoter and/or the promoter precursor that transforms into the promoter comprises I −  and is an iodide compound. 
     
     
         20 . The method of  claim 2 , further comprising:
 monitoring the mercury content of the mercury-containing gas after the separating of the sorbent therefrom; and   controlling, in response to the mercury content of the mercury-containing gas,
 an injection rate of injecting the sorbent into the mercury-containing gas, 
 a rate of addition to the coal or the combustion chamber of the added halogen or halide promoter, the promoter precursor that transforms into the promoter, or a combination thereof, or 
 a combination thereof, 
   so that the mercury content of the mercury-containing gas after the separating of the sorbent therefrom is maintained at or below a desired level.   
     
     
         21 . The method of  claim 20 , comprising controlling, in response to the mercury content of the mercury-containing gas, the injection rate of injection the sorbent into the mercury-containing gas. 
     
     
         22 . The method of  claim 20 , comprising controlling, in response to the mercury content of the mercury-containing gas, the rate of addition to the coal or the combustion chamber of the added halogen or halide promoter, the promoter precursor that transforms into the promoter, or a combination thereof.