Sorbent compositions and methods for the removal of contaminants from a gas stream
A sorbent composition for the sequestration of mercury from a gas stream, a method for sequestering mercury from a gas stream and a method for the manufacture of a sorbent composition. The sorbent composition includes a highly porous particulate sorbent and at least two additive components, namely a non-halogen metal compound comprising a metal cation and an inorganic sulfur-containing compound, where at least a portion of the sulfur in the sulfur-containing compound has an oxidation state of equal to or less than +4. The method includes injecting the highly porous particulate sorbent and the two additive components into a gas stream, either discretely or as a single sorbent composition, to sequester mercury in the particulate sorbent. The method has a high degree of efficacy for mercury removal without requiring the addition of halogens to the gas stream.
1. A free-flowing sorbent composition comprising:
carbonaceous particulates having a median particle size of at least about 2 μm and not greater than about 50 μm, a total pore volume of at least about 0.2 cc/g, and a ratio of micropore volume to mesopore volume of at least about 0.7 and not greater than about 1.5;
a non-halogen metal compound comprising a metal cation; and
an inorganic sulfur-containing compound, wherein at least a portion of the sulfur in the inorganic sulfur-containing compound has an oxidation state of equal to or less than +4,
wherein the non-halogen metal compound and the inorganic sulfur-containing compound are coated onto and/or impregnated in at least a portion of the carbonaceous particulates.
2. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises not greater than about 0.5 wt. % halogens.
3. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises substantially no halogens.
4. The free-flowing sorbent composition recited in claim 1 , wherein the carbonaceous particulates are activated carbon.
5. The free-flowing sorbent composition recited in claim 1 , where the carbonaceous particulates are derived from coal.
6. The free-flowing sorbent composition recited in claim 1 , wherein the carbonaceous particulates have a median particle size of not greater than about 30 μm.
7. The free-flowing sorbent composition recited in claim 1 , wherein the carbonaceous particulates have a total pore volume of at least about 0.3 cc/g and a ratio of micropore volume to mesopore volume of at least about 0.9 and not greater than about 1.5.
8. The free-flowing sorbent composition recited in claim 1 , wherein the carbonaceous particulates have a surface area of at least about 350 m 2 /g.
9. The free-flowing sorbent composition recited in claim 1 , wherein the metal cation is selected from the group consisting of cations of Fe, Cu, V, Mn, Co, Ni, and Zn.
10. The free-flowing sorbent composition recited in claim 9 , where the metal cation has an oxidation state of +2 or +3.
11. The free-flowing sorbent composition recited in claim 1 , wherein the non-halogen metal compound is selected from the group consisting of a sulfate compound and a nitrate compound.
12. The free-flowing sorbent composition recited in claim 11 , wherein the non-halogen metal compound is selected from the group consisting of Fe 2 (SO 4 ) 3 , FeSO 4 , and CuSO 4 .
13. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises at least about 0.1 wt. % of the metal cation.
14. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises at least about 0.5 wt. % of the metal cation.
15. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises not greater than about 20 wt. % of the metal cation.
16. The free-flowing sorbent composition recited in claim 1 , wherein the sulfur in the inorganic sulfur-containing compound is a constituent of a sulfur-containing anion.
17. The free-flowing sorbent composition recited in claim 16 , wherein the sulfur-containing anion is selected from the group consisting of thiocyanate (SCN) 1− , tetrathionate (S 4 O 6 ) 2− , and polythionate (SO 3 —S n —SO 3 ) 2− .
18. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises is at least about 0.1 wt. % sulfur from the inorganic sulfur-containing compound.
19. The free-flowing sorbent composition recited in claim 1 , wherein the sorbent composition comprises not greater than about 25 wt. % sulfur from the inorganic sulfur-containing compound.
20. The free-flowing sorbent composition recited in claim 1 , wherein the non-halogen metal compound is different from the inorganic sulfur-containing compound.
21. The free-flowing sorbent composition recited in claim 1 , wherein the inorganic sulfur-containing compound does not comprise elemental sulfur.
22. A free flowing sorbent composition comprising:
a carbonaceous particulate sorbent having a median particle size of at least about 2 and not greater than about 50 μm, a total pore volume of at least about 0.2 cc/g, and a ratio of micropore volume to mesopore volume of at least about 0.7 and not greater than about 1.5;
a non-halogen metal compound comprising a metal cation; and
an inorganic sulfur-containing compound comprising a sulfur-containing anion selected from the group consisting of thiocyanate (SCN) 1− , tetrathionate (S 4 O 6 ) 2− , and polythionate (SO 3 —S n —SO 3 ) 2− .
23. The free-flowing sorbent composition recited in claim 22 , wherein carbonaceous particulate sorbent comprises activated carbon.
24. The free-flowing sorbent composition recited in claim 22 , wherein the carbonaceous particulate sorbent has a total pore volume of at least about 0.3 cc/g and a surface area of at least about 350 m 2 /g.
25. The free-flowing sorbent composition recited in claim 22 , wherein the metal cation is selected from the group consisting of cations of Fe, Cu, V, Mn, Co, Ni, and Zn.
26. The free-flowing sorbent composition recited in claim 22 , wherein the non-halogen metal compound is selected from the group consisting of a sulfate compound and a nitrate compound.
27. The free-flowing sorbent composition recited in claim 22 , wherein the non-halogen metal compound is selected from the group consisting of Fe 2 (SO 4 ) 3 , FeSO 4 , and CuSO 4 .
28. The free-flowing sorbent composition recited in claim 22 , wherein the sorbent composition comprises at least about 0.1 wt. % and not greater than about 20 wt. % of the metal cation.
29. The free-flowing sorbent composition recited in claim 22 , wherein the sorbent composition comprises is at least about 0.1 wt. % and not greater than about 25 wt. % sulfur from the inorganic sulfur-containing compound.
30. The free-flowing sorbent composition recited in claim 22 , wherein the sorbent composition comprises substantially no halogens.
31. The sorbent composition recited in claim 22 , wherein the non-halogen metal compound and the inorganic sulfur-containing compound are coated onto and/or impregnated in the carbonaceous particulate sorbent.
32. The sorbent composition recited in claim 22 , wherein the sulfur-containing anion is selected from the group consisting of tetrathionate (S 4 O 6 ) 2 and polythionate (SO 3 —S n —SO 3 ) 2−.
33. A sorbent composition comprising:
a free-flowing carbonaceous particulate sorbent having a median particle size of at least about 2 μm and not greater than about 50 μm, a total pore volume of at least about 0.2 cc/g, and a ratio of micropore volume to mesopore volume of at least about 0.7 and not greater than about 1.5;
a non-halogen metal-containing compound comprising a metal cation selected from the group consisting of Fe, Cu, V, Mn, Co, Ni, and Zn; and
an inorganic sulfur-containing compound comprising a sulfur-containing anion selected from the group consisting of thiocyanate (SCN) 1− , tetrathionate (S 4 O 6 ) 2 and polythionate (SO 3 —S n —SO 3 ) 2− .
34. The sorbent composition recited in claim 33 , wherein the free-flowing carbonaceous particulate sorbent comprises activated carbon.
35. The sorbent composition recited in claim 33 , wherein the non-halogen metal-containing compound and the inorganic sulfur-containing compound are coated onto and/or impregnated in the free-flowing carbonaceous particulate sorbent.