Oxalate sorbents for mercury removal
Disclosed are oxalate sorbent compositions, methods for their manufacture, and methods for removing mercury species from waste streams employing oxalate sorbent compositions.
1. A sorbent composition comprising at least one carbon sorbent, at least one oxalate, and at least one transition metal cation, wherein the transition metal cation is a cobalt cation.
2. The sorbent composition of claim 1 , wherein the carbon sorbent comprises activated carbon.
3. The sorbent composition of claim 1 , wherein the oxalate and transition metal cation are a transition metal oxalate.
4. The sorbent composition of 3 , wherein the transition metal oxalate is potassium cobalt(III) oxalate.
5. The sorbent composition of claim 1 , wherein the amount of oxalate is from about 0.1 wt % to about 10 wt % of the total weight of the sorbent composition.
6. A method comprising contacting a gas comprising Hg(II) compounds with a sorbent composition, wherein the sorbent composition comprises at least one carbon sorbent, at least one oxalate, and at least one transition metal cation, wherein the transition metal cation is a cobalt cation.
7. The method of claim 6 , wherein the carbon sorbent comprises activated carbon.
8. The method of claim 6 , wherein the oxalate and transition metal cation are a transition metal oxalate.
9. The method of claim 8 , wherein the transition metal oxalate is potassium cobalt(III) oxalate.
10. The method of claim 6 , wherein the amount of oxalate in the sorbent composition is from about 0.1 wt % to about 10 wt % of the total weight of the sorbent composition.
11. The method of claim 6 , wherein the contacting is performed at about 50° C. to about 350° C.
12. The method of claim 6 , wherein the sorbent composition is injected into the gas at the rate of about 0.5 lb/MMacf to about 200 lb/MMacf.
13. The method of claim 6 , further comprising capturing the sorbent composition from the gas by electrostatic precipitation, bag filtration or both.
14. The method of claim 6 , wherein the gas comprises flue gas.
15. The method of claim 14 , wherein the flue gas is from a coal-fired plant or from a waste incinerator.
16. A method of manufacture comprising contacting a carbon sorbent, an oxalate, and a transition metal cation to provide a sorbent composition, wherein the transition metal cation is a cobalt cation.
17. The method of claim 16 , wherein the contacting is in a liquid.
18. The method of claim 17 , wherein the liquid is an aqueous solution.
19. The method of claim 17 , further comprising separating the sorbent composition from the liquid.
20. The method of claim 17 , further comprising drying the sorbent composition.
21. The method of claim 16 , wherein the contacting is in an absence of a liquid.
22. The method of claim 16 , wherein the oxalate and transition metal cation are a transition metal oxalate.
23. The method of claim 22 , wherein the transition metal oxalate is potassium cobalt(III) oxalate.