Regenerative process for removal of mercury and other heavy metals from gases containing H
A method for removal of mercury from a gaseous stream containing the mercury, hydrogen and/or CO, and hydrogen sulfide and/or carbonyl sulfide in which a dispersed Cu-containing sorbent is contacted with the gaseous stream at a temperature in the range of about 25° C. to about 300° C. until the sorbent is spent. The spent sorbent is contacted with a desorbing gaseous stream at a temperature equal to or higher than the temperature at which the mercury adsorption is carried out, producing a regenerated sorbent and an exhaust gas comprising released mercury. The released mercury in the exhaust gas is captured using a high-capacity sorbent, such as sulfur-impregnated activated carbon, at a temperature less than about 100° C. The regenerated sorbent may then be used to capture additional mercury from the mercury-containing gaseous stream.
1. A method for removal of mercury from a gaseous stream comprising said mercury, at least one of molecular hydrogen and carbon monoxide, and at least one of hydrogen sulfide (H 2 S) and carbonyl sulfide (COS) comprising the steps of:
contacting a dispersed Cu-containing sorbent with said gaseous stream at a temperature in a range of about 25° C. to about 300° C. until mercury concentration in said gaseous stream subsequent to contacting said sorbent exceeds a predetermined breakthrough level, forming a spent sorbent comprising sorbed mercury;
contacting said spent sorbent with a substantially mercury- and H 2 S/COS-free gaseous stream comprising a reducing gas, producing released mercury and a regenerated sorbent; and
capturing said released mercury using a high capacity sorbent at a temperature less than about 100° C.
2. A method in accordance with claim 1 , wherein said reducing gas is selected from the group consisting of H 2 , CO, and mixtures thereof.
3. A method in accordance with claim 1 , wherein said high capacity sorbent comprises sulfur.
4. A method in accordance with claim 3 , wherein said high capacity sorbent is selected from the group consisting of sulfur-impregnated activated carbon, copper sulfide, and mixtures thereof.
5. A method in accordance with claim 1 , wherein said gaseous stream comprises a fuel gas produced in a gasification process.
6. A method in accordance with claim 1 , wherein said gaseous stream is at a pressure in a range of about 1 bar to about 100 bar.
7. A method in accordance with claim 1 , wherein said dispersed Cu-containing sorbent is selected from the group consisting of CuO, Cu, CuS and mixtures thereof.
8. A method in accordance with claim 1 , wherein said dispersed Cu-containing sorbent is supported on a support material selected from the group consisting of high surface area alumina, silica, fumed silica, aluminates, silicates, aluminosilicates, zeolites, clays, activated carbon, and mixtures thereof.
9. A method in accordance with claim 1 , wherein said spent sorbent is regenerated at a temperature in a range of about 150° C. to about 300° C.
10. A method in accordance with claim 1 , wherein said at least one of said hydrogen sulfide and said carbonyl sulfide is captured with said mercury by at least one of said dispersed Cu-containing sorbent and said high capacity sorbent.
11. A method in accordance with claim 10 , wherein said gaseous stream further comprises at least one of arsenic, cadmium, and selenium which is captured with said mercury by at least one of said dispersed Cu-containing sorbent and said high capacity sorbent.
12. A method in accordance with claim 11 , wherein said at least one of hydrogen sulfide, carbonyl sulfide, arsenic, cadmium, and selenium is released from said spent sorbent together with said mercury.
13. A method in accordance with claim 10 , wherein said at least one of said hydrogen sulfide and said carbonyl sulfide is further processed to produce elemental sulfur after release by said dispersed Cu-containing sorbent.
14. A method in accordance with claim 1 , wherein said released mercury is captured at a temperature less than about 25° C.
15. A method in accordance with claim 1 , wherein said dispersed Cu-containing sorbent comprises Cu atoms in a monolayer, sub-monolayer, multilayer, or nanocrystallite form.
16. A method in accordance with claim 8 , wherein said Cu comprises in a range of about 5 wt. % to about 40 wt. % of said supported sorbent.
17. A method for removal of mercury from a gaseous stream comprising said mercury, at least one of molecular hydrogen and carbon monoxide and at least one of hydrogen sulfide and carbonyl sulfide comprising the steps of:
adsorbing said mercury using a dispersed Cu-containing sorbent at a temperature in a range of about 100° C. to about 300° C., forming a spent dispersed Cu-containing sorbent;
regenerating said spent dispersed Cu-containing sorbent using a gaseous regenerating stream comprising at least one reducing gas, producing released mercury and a regenerated dispersed Cu-containing sorbent; and
capturing said released mercury with a high capacity sorbent at a temperature less than about 100° C.
18. A method in accordance with claim 17 , wherein said high capacity sorbent comprises sulfur.
19. A method in accordance with claim 18 , wherein said high capacity sorbent is selected from the group consisting of sulfur-impregnated activated carbon, copper sulfide, and mixtures thereof.
20. A method in accordance with claim 17 , wherein said gaseous stream is a fuel gas produced by a gasification process.
21. A method in accordance with claim 17 , wherein said gaseous stream is at a pressure in a range of about 1 bar to about 100 bar.
22. A method in accordance with claim 17 , wherein said dispersed Cu-containing sorbent comprises at least one of CuO, Cu, and CuS.
23. A method in accordance with claim 17 , wherein said dispersed Cu-containing sorbent is supported on a support material selected from the group consisting of high surface area alumina, silica, fumed silica, aluminates, silicates, aluminosilicates, zeolites, clays, activated carbon, and mixtures thereof.
24. A method in accordance with claim 17 , wherein said spent dispersed Cu-containing sorbent is regenerated at a temperature in a range of about 150° C. to about 300° C.
25. A method in accordance with claim 17 , wherein said reducing gas is selected from the group consisting of H 2 , CO, and mixtures thereof.