Claims
- 1. A method for the regeneration of sulfur-containing cerium compounds formed by the desulfurization of fluid materials containing sulfur with cerium oxide back to its original form, CeO.sub.2, comprising the steps of:
- (a) Removing the sulfur-containing cerium compounds from contact with the fluid material containing sulfur;
- (b) Raising the temperature of the sulfur-containing cerium compounds above the temperature at which cerium sulfate dissociates; and
- (c) Exposing the sulfur-containing cerium compounds whose temperature is above the temperature at which cerium sulfate dissociates to an oxidizing atmosphere.
- 2. The method as claimed in claim 1 wherein the sulfur-containing cerium compound being regenerated is cerium oxysulfide (Ce.sub.2 O.sub.2 S).
- 3. The method as claimed in claim 1 wherein the fluid material being desulfurized is a fuel gas resulting from the incomplete combustion of a sulfur-containing hydrocarbon.
- 4. The method as claimed in claim 1 wherein the fluid material being desulfurized is a flue gas resulting from the incomplete combustion of a sulfur-containing hydrocarbon.
- 5. The method as claimed in claim 1 wherein the fluid material being desulfurized is iron or steel.
- 6. The method as claimed in claim 1 wherein the temperature of regeneration is greater than 872.degree. C. (1572.degree. F.) and less than 2500.degree. C. (4502.degree. F.), the reported melting point of some forms of cerium oxide.
- 7. The method as claimed in claim 6 wherein the temperature of regeneration is between 900.degree. C. (1652.degree. F.) and 1400.degree. C. (2552.degree. F.), at Which temperature there would be a significant reduction in the porosity of the pellets or granules of cerium oxide.
- 8. The method as claimed in claim 6 wherein the temperature of regeneration is between the temperature of 920.degree. C. (1688.degree. F.) and 1250.degree. C. (2282.degree. F.), at which temperature there should be essentially complete dissociation of the Ce.sub.2 (SO.sub.4).sub.3 and a significant amount of porosity retained in the sorbent.
- 9. The method as claimed in claim 1 wherein the oxidizing atmosphere used for regeneration utilizes a mixture of oxygen and an inert gas as the oxidizing agent.
- 10. The method as claimed in claim 9 wherein the inert gas is nitrogen.
- 11. The method as claimed in claim 1 wherein the oxidizing atmosphere used for regeneration contains water as an oxidizing agent.
- 12. The method as claimed in claim 1 wherein the oxidizing atmosphere used for regeneration contains oxygen, water and an inert gas.
- 13. The method as claimed in claim 12 wherein the inert gas is nitrogen.
- 14. The method of claim 1 wherein the oxygen content of the oxidizing atmosphere used for regeneration is limited to an amount no greater than that which would limit the temperature attained during the regeneration to that of the sintering temperature of said cerium compounds.
- 15. The method as claimed in claim 1 wherein the oxygen content of the oxidizing atmosphere used for regeneration is limited to promote the formation of elemental sulfur according to the reaction:
- Ce.sub.2 O.sub.2 S (s)+O.sub.2 (g)=CeO.sub.2 (s)+1/2S.sub.2 (g)
- 16. The method as claimed in claim 1 wherein the oxygen content of the oxidizing atmosphere used for regeneration contains less than 4% by volume of oxygen resulting in the formation of elemental sulfur as one of the gases occurring during the regeneration process.
- 17. The method as claimed in claim 1 wherein the oxygen content of the oxidizing atmosphere used for the regeneration contains less than 4% by volume of oxygen as a means of limiting the increase in temperature due to the exothermic reaction between the oxygen and the sulfided cerium oxide to prevent the temperature in the reactor from exceeding the temperature at which the pellets or granules are sintered to insure sufficient strength to prevent attrition during successive cycles of sulfidation and regeneration of the sorbent while retaining a significant amount of porosity to improve the utilization of the cerium oxide sorbent.
- 18. The method as claimed in claim 1 wherein the temperature of regeneration is greater than 900.degree. C. (1652.degree. F.) so that the amount of hydrogen necessary to eliminate any Ce.sub.2 (SO.sub.4).sub.3 remaining after the oxidation of the sulfided sorbent is minimized.
- 19. The method as claimed in claim 18 wherein the temperature of regeneration is greater than 920.degree. C. (1688.degree. F.) and less than 1250.degree. C. (2282.degree. F.).
Parent Case Info
This application is a continuation-in part of our co-pending application Ser. No. 099,058, now U.S. Pat. No. 4,826,664 which is a continuation of our co-pending application Ser. No. 846,272 filed Mar. 31, 1986, which was a division of application Ser. No. 718,989, filed Apr. 2, 1985, now U.S. Pat. No. 4,604,268, which was a continuation-in-part of our application Ser. No. 471,773 filed Mar. 3, 1983, now abandoned which was a continuation of our application Ser. No. 174,024 filed July 31, 1980 now U.S. Pat. No. 4,397,683.
US Referenced Citations (16)
Non-Patent Literature Citations (1)
Entry |
Philip S. Lowell et al., "Selection of Metal Oxides for Removing SO.sub.2 from Flue Gas", Ind. Eng. Chem. Process Des. Develop., vol. 10, No. 3, 1971. |
Divisions (1)
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Date |
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Parent |
718989 |
Apr 1985 |
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Continuations (2)
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Date |
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846272 |
Mar 1986 |
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Parent |
174024 |
Jul 1980 |
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Continuation in Parts (2)
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99058 |
Sep 1987 |
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Parent |
471773 |
Mar 1983 |
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