Absorbent compositions for the removal of acid gases from gas streams

• US 6,337,059 B1
• Filed: 05/03/1999
• Issued: 01/08/2002
• Est. Priority Date: 05/03/1999
• Status: Active Grant

• Current Assignee: Union Carbide Chemicals & Plastics Technology Corporation (Dow, Inc.)
• Original Assignee: Union Carbide Chemicals & Plastics Technology Corporation (Dow, Inc.)
• Inventors: Schubert, Craig Norman, Dean, John Wayne, Forte, Paulino
• Primary Examiner(s): Griffin, Steven P.
• Assistant Examiner(s): Vanoy, Timothy C
• Application Number:
  US09/304,283
• Time in Patent Office: 981 Days
• Field of Search: 423/228, 423/229, 423/210, 423/242.7, 252/182.12, 252/190, 252/189
• US Class Current: 423/210
• CPC Class Codes: B01D 53/1456 Removing acid components
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

An absorbent composition for the removal of acid gases, such as CO₂, H₂S and COS, from gas streams is provided. The absorbent composition comprises an aqueous solution comprising: 1) greater than 1 mole piperazine per liter of aqueous solution; and 2) about 1.5 to about 6 moles methyldiethanolamine per liter of aqueous solution.

Claims

1. An absorbent composition for the removal of acid gases from gas streams, comprising an aqueous solution comprising:

1) greater than 1.1 mole piperazine per liter of aqueous solution; and

     2) about 1.5 to about 6 moles methyldiethanolamine per liter of aqueous solution.

2. The absorbent composition of claim 1, comprising greater than about 1.2 mole piperazine per liter of aqueous solution.

3. The absorbent composition of claim 1, comprising about 2.5 to about 5.5 mole methyldiethanolamine per liter of aqueous solution.

4. The absorbent composition of claim 1, comprising about 2.9 to about 4.2 mole methyldiethanolamine per liter of aqueous solution.

5. The absorbent composition of claim 1, further comprising an additional chemical solvent or a physical solvent.

6. The absorbent composition of claim 5, comprising a physical solvent selected from the group consisting of sulfolane or methoxytriglycol.

7. A process for the removal of acid gases from a gas stream, comprising contacting a gas stream containing an acid gas with an absorbent composition comprising an aqueous solution comprising:

1) greater than 1.1 mole piperazine per liter of aqueous solution; and

     2) about 1.5 to about 6 moles methyldiethanolamine per liter of aqueous solution to produce an acid gas-lean gas stream and an acid gas-rich absorbent composition stream.

8. The process of claim 7, further comprising the subsequent steps of separating the acid gas-lean gas stream from the acid gas-rich absorbent composition stream;

recovering the acid gas-lean gas stream as product;

regenerating the acid gas-rich absorbent composition stream by removing acid gas therefrom to produce a regenerated absorbent composition; and

recycling the regenerated absorbent composition to the contacting step of claim 7.

9. The process of claim 7, wherein the absorbent composition comprises about 2.5 to about 5.5 mole methyldiethanolamine per liter of aqueous solution.

10. The process of claim 7, wherein the absorbent composition further comprises an additional chemical solvent or a physical solvent.

11. The process of claim 7, wherein the regenerating step is conducted at a temperature in the range of about 100°

to about 130°

C.