Sulfur recovery process
View Patent ↗A process for the simultaneous removal of H 2 S and SO 2 from tail gases is disclosed. A tail gas stream is contacted with a sorbent in a sorption zone to produce a product gas stream and a sulfur laden sorbent, wherein the sorbent comprises Zn and a promoter metal. A process for the recovery of sulfur is also disclosed. A tail gas stream is contacted with a sorbent in a sorption zone to produce solid sulfur, wherein the sorbent comprises Zn and a promoter metal, wherein the promoter metal is manganese.
1. A sulfur recovery process, comprising;
a) providing a sorbent comprising a substitutional solid solution characterized by the formula Mn Z Zn (1-Z) Al 2 O 4
b) contacting the sorbent with a reducing agent in a reduction zone,
wherein as a result of said contacting, at least a portion of the promoter metal component of the sorbent is converted to a reduced-valence state,
c) contacting a tail gas stream comprising SO 2 and H 2 S with the sorbent in a sorption zone
wherein said contacting simultaneously reduces the quantity of SO 2 and H 2 S present in the tail gas, thereby producing a product gas stream, solid sulfur, and a sulfur laden sorbent, and,
wherein as a result of said contacting, the Mn promoter metal of the sorbent reacts simultaneously with both H 2 S and SO 2 to produce solid elemental sulfur and water according to the reaction:
Mn+H 2 S+SO 2 →2/xS x +MnO+H 2 O,
d) contacting at least a portion of said sulfur laden sorbent with a regeneration gas stream in a regeneration zone to produce a regenerated sorbent and an off-gas stream.
2. A process in accordance with claim 1 , further comprising, prior to step (d), drying at least a portion of said sulfur-laden sorbent to thereby provide a dried sulfur-laden sorbent and subjecting at least a portion of said dried sulfur-laden sorbent to said contacting of step (d).
3. A process in accordance with claim 1 , further comprising introducing at least a portion of said regenerated sorbent into said sorption zone, wherein said regenerated sorbent introduced into said sorption zone comprises a substitutional solid metal oxide solution characterized by the formula Mn X Zn Y O,
wherein X and Y are in the range from about 0.01 to about 0.99.
4. A process in accordance with claim 1 , wherein said tail gas stream comprises SO 2 in the range of up to about 5 volume percent, based on the total volume of said tail gas stream.
5. A process in accordance with claim 1 , wherein said tail gas stream comprises H 2 S in the range of up to about 5 volume percent, based on the total volume of said tail gas stream.
6. A process in accordance with claim 1 , wherein said tail gas stream has a ratio of H 2 S to SO 2 of about 100:1.
7. A process in accordance with claim 1 , wherein said tail gas stream has a ratio of H 2 S to SO 2 of about 10:1.
8. A process in accordance with claim 1 , wherein said tail gas stream has a ratio of H 2 S to SO 2 of about 2:1.
9. A process in accordance with claim 1 wherein said tail gas stream further comprises compounds selected from the group consisting of steam, syngas, CO 2 , and combinations of any two or more thereof.
10. A process in accordance with claim 1 wherein said reducing agent comprises an agent selected from the group consisting of hydrogen and carbon monoxide.
11. A process in accordance with claim 1 wherein said tail gas further comprises a reducing agent.
12. A process in accordance with claim 11 wherein said reducing agent comprises an agent selected from the group consisting of hydrogen and carbon monoxide.
13. A process in accordance with claim 1 wherein conditions in said sorption zone include a temperature in the range of from about 150° C. to about 1000° C.
14. A process in accordance with claim 1 wherein conditions in said sorption zone include a temperature in the range of from about 250° C. to about 700° C.
15. A process in accordance with claim 1 wherein conditions in said sorption zone include a temperature in the range of from about 350° C. to about 550° C.
16. A process in accordance with claim 1 wherein conditions in said sorption zone include a pressure in the range of from about atmospheric pressure to about 5000 psig.
17. A process in accordance with claim 1 wherein conditions in said sorption zone include a pressure in the range of from about atmospheric pressure to about 1000 psig.
18. A process in accordance with claim 1 wherein conditions in said regeneration zone includes a regeneration gas stream.
19. A process in accordance with claim 18 wherein said regeneration gas stream comprises oxygen.
20. A process in accordance with claim 18 wherein said regeneration gas stream comprises air.
21. A process in accordance with claim 1 wherein said off-gas stream comprises SO 2 .
22. A process in accordance with claim 21 wherein said off-gas stream is recycled to a SO 2 treatment zone.
23. A process in accordance with claim 22 wherein said SO 2 treatment zone comprises a Claus unit.
24. A process in accordance with claim 1 wherein at least a portion of said regenerated sorbent is returned to said sorption zone.