Carbon dioxide absorber and carbon dioxide separation/recovery method using the absorber

Patent metadata

Field	Value
Publication number	US-9399192-B2
Application number	US-201214125048-A
Country	US
Kind code	B2
Filing date	Jun 8, 2012
Priority date	Jun 9, 2011
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

The present invention provides a carbon dioxide absorber capable of efficiently and stably removing carbon dioxide in a gas or solution. This carbon dioxide absorber contains an amine compound, a weakly acidic compound and water, the pKb value of the amine compound in an aqueous solution at 30° C. is 4.0 to 7.0, the pKa value of the weakly acidic compound in an aqueous solution at 30° C. is 7.0 to 10.0, and the weakly acidic compound is present in an amount within the range of 0.01 equivalents to 1.50 equivalents with respect to amino groups of the amine compound.

First claim

The invention claimed is:

1. A carbon dioxide absorber containing an amine compound, a weakly acidic compound and water;
wherein, the amine compound at least includes an amine compound represented by the following general formula (I):

wherein, R 1 and R 2 represent hydrogen atoms or alkyl groups having 1 to 4 carbon atoms,
the weakly acidic compound is a boric acid or a borate ester having a pKa value of 7.0 to 10.0 in an aqueous solution at 30° C., and
the weakly acidic compound is present in an amount within the range of 0.01equivalents to 1.50 equivalents with respect to amino groups of the amine compound.

2. The carbon dioxide absorber according to claim 1 , wherein the pH of the carbon dioxide absorber at 30° C. is 8.5 to 11.0.

3. The carbon dioxide absorber according to claim 1 , wherein the content of the boric acid or the borate ester is within the range of 0.05 equivalents to 0.30 equivalents with respect to amino groups of the amine compound.

4. The carbon dioxide absorber according to claim 3 , wherein 25% to 99% of the boric acid neutralizes amino groups of the amine compound.

5. The carbon dioxide absorber according to claim 1 , wherein a compound having a pKb value in an aqueous solution at 30° C. of less than 4.0 is not contained.

6. The carbon dioxide absorber according to claim 1 , wherein the amine compound has a primary and/or secondary amino group.

7. The carbon dioxide absorber according to claim 1 , wherein the content of the amine compound is 30% by mass to 55% by mass, and the amount of the water is 40% by mass or more.

8. The carbon dioxide absorber according to claim 1 , further containing 1.0% by mass to 6.0% by mass of piperazine and/or 2-methylpiperazine, and containing the weakly acidic compound within the range of 0.5 moles to 2.0 moles with respect to 1 mole of the piperazine and/or 2-methylpiperazine.

9. The carbon dioxide absorber according to claim 1 , further containing diethanolamine.

10. The carbon dioxide absorber according to claim 1 , wherein both R 1 and R 2 in the formula are hydrogen atoms.

11. A carbon dioxide absorber containing water and an amine that at least includes an amine compound represented by the following general formula (I):

(wherein, R 1 and R 2 represent hydrogen atoms or alkyl groups having 1 to 4 carbon atoms).

12. The carbon dioxide absorber according to claim 11 , wherein both R 1 and R 2 in the formula are hydrogen atoms.

13. The carbon dioxide absorber according to claim 11 , containing the amine at 5.0% by mass to 80.0% by mass and containing water at 20.0% by mass to 95.0% by mass.

14. The carbon dioxide absorber according to claim 13 , wherein the amine contains diethanolamine at 20.0% by mass to 70.0% by mass in the amine.

15. The carbon dioxide absorber according to claim 13 , wherein the amine contains piperazine and/or 2-methylpiperazine at 1.0% by mass to 15.0% by mass in the amine.

16. The carbon dioxide absorber according to claim 13 , wherein the amine contains diethanolamine at 20.0% by mass to 65.0% by mass and contains piperazine and/or 2-methylpiperazine at 1.0% by mass to 15.0% by mass in the amine.

17. The carbon dioxide absorber according to claim 1 or 11 , further containing an antioxidant.

18. The carbon dioxide absorber according to claim 17 , wherein the antioxidant is a secondary antioxidant having one or more thiol groups.

19. A method for regenerating a carbon dioxide absorber, comprising following steps:
absorbing carbon dioxide into the carbon dioxide absorber described in claim 1 or 11 , and
releasing the carbon dioxide by heating the carbon dioxide absorber.

20. A method for separating and recovering carbon dioxide, comprising following steps:
absorbing carbon dioxide by contacting a gas containing carbon dioxide with the carbon dioxide absorber according to claim 1 or 11 , and
regenerating the carbon dioxide absorber by releasing the carbon dioxide by subsequently heating the carbon dioxide absorber.

21. A carbon dioxide absorber containing an amine compound, a weakly acidic compound and water;
wherein,
the amine compound at least includes an amine compound represented by the following general formula (I):

wherein, R 1 and R 2 represent hydrogen atoms or alkyl groups having 1 to 4carbon atoms,
the weakly acidic compound is a boric acid or a borate ester,
the weakly acidic compound is present in an amount within the range of 0.05equivalents to 0.30 equivalents with respect to amino groups of the amine compound, and
wherein a compound having a pKb value in an aqueous solution at 30° C. of less than 4.0 is not contained.

Assignees

• Fujimoto Norikazu
• Hattori Kyouhei
• Yamaguchi Fumihiko
• Asahi Chemical Ind

Inventors

• Fujimoto Norikazu
• Hattori Kyouhei
• Yamaguchi Fumihiko

Classifications

• B01D53/1425 Primary

  Regeneration of liquid absorbents · CPC title

• B01D2252/504

  Mixtures of two or more absorbents · CPC title

• B01D2252/204

  Amines · CPC title

• B01D53/1475

  Removing carbon dioxide · CPC title

• B01D53/1493

  Selection of liquid materials for use as absorbents · CPC title