Separation of acidic gas constituents from gaseous mixtures containing the same

• US 4,044,100 A
• Filed: 03/29/1972
• Issued: 08/23/1977
• Est. Priority Date: 12/08/1969
• Status: Expired due to Term

• Current Assignee: Norton Company (Compagnie De Saint-Gobain)
• Original Assignee: Allied Chemical Corporation (Honeywell International Inc.)
• Inventors: McElroy, Paul L. Jr.
• Primary Examiner(s): Thomas, Earl C.
• Application Number:
  US05/239,366
• Time in Patent Office: 1,973 Days
• Field of Search: 423/226-229
• US Class Current: 423/226
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents

Abstract

Acidic gas constituents are removed from a gaseous mixture by contacting the gaseous mixture with a single-phase liquid solution of a normally liquid dialkyl ether of a polyalkylene glycol and diisopropanolamine. Absorption conditions are selected to effect substantial absorption of the acidic gases while maintaining the solvent as a single-phase. The single-phase liquid solution containing absorbed acidic gases is separated from the resulting sweet gas and conducted to a stripping zone wherein the solution is subjected to conditions to effect removal of absorbed gas therefrom. The resulting stripped single-phase solution can be recycled for further contacting with gaseous mixtures containing acidic gases.

Claims

1. A method of separating carbon dioxide from a gaseous mixture containing same which comprises contacting the gaseous mixture in an absorption zone with a liquid solvent comprising a solution of from 10 to 65% by weight of di-isopropanolamine and of from 35 to 90% by weight of a normally liquid dialkalyl ether of a polyalkalylene glycol under conditions which effect absorption of the carbon dioxide in the solvent while controlling temperature at above about 15°

to 90°

C. and total pressure between about 50 and 1500 pounds per square inch gauge such as to maintain said solvent as a single phase.

2. A method as claimed in claim 1 wherein the gaseous mixture contains at least one additional acidic gas constituent selected from the group consisting of hydrogen sulfide and carbonyl sulfide.

3. A method as claimed in claim 2 wherein the liquid solvent comprises a solution by weight of 10 to 65% of diisopropanolamine and 35 to 90% of a normally liquid dimethyl ether of a polyethylene glycol, and the gaseous mixture is contacted with the liquid solvent at a pressure of at least 150 pounds per square inch gauge.

4. A method as claimed in claim 3, wherein the polyethylene glycol dimethyl ether comprises at least one member selected from the group consisting of the dimethyl ether of diethylene glycol, the dimethyl ether of triethylene glycol, the dimethyl ether of tetraethylene glycol, the dimethyl ether of pentaethylene glycol, the dimethyl ether of hexaethylene glycol, and the dimethyl ether of heptaethylene glycol.

5. A method as claimed in claim 4, wherein the polyethylene glycol dimethyl ether comprises the dimethyl ether of tetraethylene glycol.

6. A method as claimed in claim 3, wherein the polyethylene glycol dimethyl ether comprises a mixture of the dimethyl ether of diethylene glycol, the dimethyl ether of triethylene glycol, the dimethyl ether of tetraethylene glycol, the dimethyl ether of pentaethylene glycol, the dimethyl ether of hexaethylene glycol, and the dimethyl ether of heptaethylene glycol.

7. A method as claimed in claim 6, wherein the solvent from the absorption zone containing absorbed gas is passed to a stripping zone maintained at a pressure substantially lower than in the absorption zone, said solvent containing absorbed gas subjected to conditions in said stripping zone to effect removal of absorbed gas therefrom, and the resulting desorbed solvent recycled to said absorption zone for further contact with said gaseous mixture.

8. a method as claimed in claim 7, wherein the liquid solvent comprises a solution by weight of 25 to 50% of diisopropanolamine and 50 to 75% of the polyethylene glycol dimethyl ether.

9. A method as claimed in claim 8, wherein the absorption zone is maintained at a temperature of from about 15°

C. to about 90°

C. and the solvent additionally contains water maintained in an amount between about 0.5% and about 15% by weight.

10. A method as claimed in claim 9, wherein the pressure in the absorption zone is maintained between about 50 to 1,500 pounds per square inch gauge, the temperature in the lower part of the absorption zone is maintained at about 70°

C.

11. A method as claimed in claim 10, wherein the gaseous mixture is an ammonia synthesis gas.

12. A method as claimed in claim 10, wherein the gaseous mixture is a sour natural gas.