Process and amine-solvent absorbent for removing acidic gases from gaseous mixtures

• US 4,100,257 A
• Filed: 02/14/1977
• Issued: 07/11/1978
• Est. Priority Date: 02/14/1977
• Status: Expired due to Term

• Current Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Savage, David W., Sartori, Guido
• Primary Examiner(s): Thomas, Earl C.
• Application Number:
  US05/768,420
• Time in Patent Office: 512 Days
• Field of Search: 423/220, 423/226, 423/228, 423/229, 260/584 R, 55/68, 55/73
• US Class Current: 423/226
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents

Abstract

Acidic gases are substantially removed from a normally gaseous mixture by a process comprising contacting the normally gaseous mixture with an amine-solvent liquid absorbent comprising (i) an amine mixture comprised of at least about 50 mol % of a sterically hindered amine and at least about 10 mol % of a tertiary amino alcohol, wherein said sterically hindered amine contains at least one secondary amino group which is part of a ring and is attached to either a secondary or tertiary carbon atom or a primary amino group attached to a tertiary carbon atom, and (ii) a solvent for said amine mixture which is also a physical absorbent for said acidic gases. The liquid absorbent may also include up to about 35 weight percent water. The coaction of the sterically hindered amine and the tertiary amino alcohol in conjunction with the solvent provides an increase in the amount of CO₂ containing acidic gases absorbed compared to the use of the same sterically hindered amines alone and lowers the heat of reaction.

Claims

1. A process for the removal of acidic gases from a normally gaseous mixture, which comprises contacting said normally gaseous mixture with an amine-solvent liquid absorbent being comprised of:

(i) an amine mixture comprised of at least 50 mol % of a sterically hindered amine and at least about 10 mol % of a tertiary amino alcohol, wherein said sterically hindered amine contains at least one secondary amino group which is part of a ring and is attached to either a secondary or tertiary carbon atom or a primary amino group attached to a tertiary carbon atom, and

(ii) a solvent for said amine mixture which is a physical absorbent for said acidic gases.

2. The process of claim 1 wherein said sterically hindered amine is a member selected from the group consisting of 2-piperidine methanol, 2-piperidine ethanol, 2-(1-hydroxyethyl)-piperidine, 5-hydroxy-2-methyl piperidine, 2-methyl-3-hydroxy piperidine, 2,6-dimethyl-3-hydroxy piperidine, 2,5-dimethyl-4-hydroxy piperidine, 3-amino-3-methyl-1-butanol, 2-amino-2-methyl-1-butanol, 2-amino-2-methyl-3-butanol and 3-amino-3-methyl-2-pentanol.

3. The process of claim 1 wherein the tertiary amino alcohol is a member selected from the group consisting of 3-dimethylamino-1-propanol, 1-diethylamino-2-propanol, 2-diethylamino ethanol, 3-diethylamino-1-propanol, N-methyl diethanolamine and 1-methyl-3-hydroxy piperidine.

4. The process of claim 1 wherein said solvent is a member selected from the group consisting of sulfones;

sulfoxides;

glycols, mono- and diethers thereof;

1,3-dioxo compounds characterized by being a 5- to 6-membered heterocyclic ring;

aromatic ethers;

aromatic hydrocarbons;

pyrrolidones;

piperidones; and

mixtures thereof.

5. The process of claim 1 wherein said sterically hindered amine is a 2-piperidine alkanol.

6. The process of claim 1 wherein said sterically hindered amine is a member selected from the group consisting of 2-piperidine methanol and 2-piperidine ethanol.

7. The process of claim 1 wherein said tertiary alkanolamine is a member selected from the group consisting of 3-dimethylamino-1-propanol, 1-diethylamino-2-propanol and 2-diethylamino ethanol.

8. The process of claim 1 wherein said solvent is a cyclotetramethylene sulfone.

9. The process of claim 1 wherein the solvent is sulfolane.

10. The process of claim 1 wherein said liquid absorbent includes up to about 35 weight percent of water.

11. The process of claim 1 wherein said acidic gases are absorbed by said liquid absorbent at a temperature ranging from about 20°

to about 100°

C and at a pressure ranging from 1 to about 2000 psig, and said acidic gases are desorbed from said liquid absorbent at a temperature ranging from about 50°

to about 170°

C and at a pressure ranging from about 1 to about 50 psia.

12. The process of claim 11 wherein the absorption is conducted at a temperature ranging from about 40°

to about 60°

C and at a pressure ranging from about 100 to about 1000 psig, and the desorption is conducted at a temperature ranging from about 80°

to about 150°

C and at a pressure ranging from about 15 to about 30 psia.

16. The process of claim 1 wherein the aminesolvent liquid absorbent additionally includes additives selected from the group consisting of antifoaming agents, antioxidants and corrosion inhibitors.

13. A process for the substantial removal of carbon dioxide containing acidic gases from a normally gaseous mixture, which comprises:

(a) contacting said normally gaseous mixture with an amine-solvent liquid absorbent to absorb said carbon dioxide containing acidic gases, wherein said amine-solvent liquid absorbent comprises;

(i) an amine mixture comprises of at least 50 mol % of a 2-piperidine alkanol and at least 10 mol % of a tertiary amino alcohol which is a member selected from the group consisting of 3-dimethylamino-1-propanol, 1-diethylamino-2-propanol and 2-diethylamino ethanol,

(ii) sulfolane, and

(iii) up to about 35 weight percent of water;

wherein said absorption is conducted at a temperature ranging from about 40°

to about 60°

C and at a pressure ranging from about 100 to about 1000 psig, and

(b) desorbing at least a portion of the absorbed carbon dioxide containing acidic gases from said solution at a temperature ranging from about 80°

to about 150°

C and at a pressure ranging from about 15 to about 30 psia.

14. The process of claim 13 wherein said 2-piperidine alkanol is 2-piperidine ethanol.

15. The process of claim 13 wherein the water content of said amine-solvent liquid absorbent is in the range from about 10 to about 20 weight percent.

17. The process of claim 13 wherein the aminesolvent liquid absorbent additionally includes additives selected from the group consisting of antifoaming agents, antioxidants and corrosion inhibitors.

18. A process for the substantial removal of carbon dioxide containing acidic gases from a normally gaseous mixture, which comprises:

(a) contacting said normally gaseous mixture with an amine-solvent liquid absorbent to absorb said carbon dioxide containing acidic gases, wherein said aminesolvent liquid absorbent comprises;

(i) an amine mixture comprised of at least 65 mol % of 2-piperidine ethanol and from 20 to about 35 mol % of a tertiary amino alcohol selected from the group consisting of 3-dimethylamino-1-propanol, 1-diethylamino-2-propanol and 2-diethylamino ethanol, wherein the total amine concentration in said amine-solvent liquid absorbent is in the range from about 10 weight % to about 65 weight %,

(ii) water, in an amount ranging from about 10 to about 20 weight %, and

(iii) essentially all of the balance of the amine-solvent liquid absorbent being comprised of sulfolane;

wherein said absorption is conducted at a temperature ranging from about 40°

to about 60°

C. and at a pressure ranging from about 100 to about 1000 psig, and;

(b) desorbing at least a portion of the absorbed carbon dioxide containing acidic gases from said solution at a temperature ranging from about 80°

to about 150°

C. and at a pressure ranging from about 15 to about 30 psia.

19. The process of claim 18 wherein the aminesolvent liquid absorbent from step (b) is recycled in the absorption process of step (a).

20. The process of claim 18 wherein the aminesolvent liquid absorbent additionally includes additives selected from the group consisting of antifoaming agents, antioxidants and corrosion inhibitors.