Process for reversibly absorbing acid gases from gaseous mixtures

• US 5,338,521 A
• Filed: 11/10/1992
• Issued: 08/16/1994
• Est. Priority Date: 11/10/1992
• Status: Expired due to Term

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Appleby, John B., Quinn, Robert, Pez, Guido P.
• Primary Examiner(s): Lewis, Michael
• Assistant Examiner(s): Lovern, Wendy
• Application Number:
  US07/973,897
• Time in Patent Office: 644 Days
• Field of Search: 423/230, 423/210.5, 423/244.01, 423/243.06, 423/242.2, 423/220
• US Class Current: 423/210.5
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: C01B 17/167 Separation

Abstract

A process is disclosed for reversibly absorbing acid gases from gaseous mixtures wherein a salt hydrate is heated to a temperature above its melting point and exposed to an acid gas which is absorbed by the salt hydrate to form a salt hydrate melt. This melt is thereafter cooled to a temperature sufficient to solidify the melt and to desorb the acid gas from the solidified salt hydrate. Preferred salt hydrates include tetramethylammonium fluoride tetrahydrate and tetraethylammonium acetate tetrahydrate.

Claims

1. A process for reversibly absorbing an acid gas from a gaseous mixture containing the acid gas, the process consisting essentially of:

contacting the gaseous mixture with the salt hydrate at a temperature above the melt temperature of the salt hydrate melt into which a portion of the acid gas is absorbed; and

cooling the salt hydrate melt to a temperature sufficient to solidify the salt hydrate melt and to desorb the acid gas from the solidifying salt hydrate.

2. The process of claim 1 wherein acid gas is selected from the group consisting of CO₂, H₂ S and COS.

3. The process of claim 2 wherein the gaseous mixture containing the acid gas is contacted with the salt hydrate at a temperature of between about 0°

C. and 200°

C.

4. The process of claim 3 wherein the gaseous mixture containing the acid gas is pressurized prior to contacting the gaseous mixture with the salt hydrate melt.

5. A process for reversibly absorbing an acid gas from a gaseous mixture containing the acid gas, the process consisting essentially of:

contacting the gaseous mixture with a salt hydrate selected from the group consisting of tetramethylammonium fluoride trihydrate, tetramethylammonium fluoride tetrahydrate, tetramethylammonium fluoride hexahydrate, tetraethylammonium acetate tetrahydrate and tetraethylammonium acetate hexahydrate at a temperature above the melt temperature of the salt hydrate to form a salt hydrate melt onto which a portion of the acid gas is reversibly absorbed; and

cooling the salt hydrate melt to a temperature sufficient to solidify the salt hydrate melt and to desorb the acid gas from the solidifying salt hydrate.

6. The process of claim 5 wherein the salt hydrate is tetramethylammonium fluoride tetrahydrate.

7. The process of claim 6 wherein the acid gas is contacted with the salt hydrate at a temperature of between about 40°

C. and about 60°

C.

8. The process of claim 7 wherein the gaseous mixture containing the acid gas is pressurized prior to contacting the gaseous mixture with the salt hydrate melt.

9. The process of claim 8 wherein the acid gas is selected from the group consisting of CO₂, H₂ S and COS.

10. The process of claim 5 wherein the salt hydrate is tetraethylammonium acetate tetrahydrate.

11. The process of claim 10 wherein the acid gas is contacted with the salt hydrate at a temperature of between about 40°

C. and about 60°

C.

12. The process of claim 11 wherein the gaseous mixture containing the acid gas is pressurized prior to contacting the gaseous mixture with the salt hydrate melt.

13. The process of claim 12 wherein the acid gas is selected from the group consisting of CO₂, H₂ S and COS.