Method for absorbing CO2 from a gas mixture

• US 9,630,140 B2
• Filed: 04/22/2013
• Issued: 04/25/2017
• Est. Priority Date: 05/07/2012
• Status: Active Grant

• Current Assignee: Evonik Operations GmbH (Rag-Stiftung)
• Original Assignee: Evonik Degussa GmbH
• Inventors: Willy, Benjamin, Rinker, Stefanie, Niemeyer, Jochen, Witthaut, Daniel, Seiler, Matthias, Neumann, Manfred, Keup, Michael, Rolker, Jrn, Schneider, Rolf, Dembkowski, Daniel, Brehme, Volker
• Primary Examiner(s): BERNS, DANIEL J
• Application Number:
  US14/399,139
• Publication Number:
  US 20150125373A1
• Time in Patent Office: 1,464 Days
• Field of Search: None
• CPC Class Codes: B01D 2252/20442 containing a piperidine-ring
• CPC Class Codes: B01D 2252/20447 containing a piperazine-ring
• CPC Class Codes: B01D 2252/20452 containing a morpholine-ring
• CPC Class Codes: B01D 2252/20478 Alkanolamines
• CPC Class Codes: B01D 2252/502 having two or more functionalities in the same molecule other than alkanolamine
• CPC Class Codes: B01D 2256/24 Hydrocarbons
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2258/0233 from cement factories
• CPC Class Codes: B01D 2258/025 from metallurgy plants
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 2258/05 Biogas
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: C10L 2290/541 Absorption of impurities during preparation or upgrading of a fuel
• CPC Class Codes: C10L 3/104 Carbon dioxide
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

In a method of absorbing CO₂ from a gas mixture the use of an absorption medium comprising water and at least one amine of formula (I)

• where
• R¹ is a —(CH₂)_n—(XCH₂CH₂)_m—Y—R³ radical where
• R³=hydrogen or an alkyl radical having from 1 to 6 carbon atoms,
• X and Y are each, independently of one another, NR³, oxygen, SO or SO₂, where in the case of Y═SO and in the case of Y═SO₂, R³ is not hydrogen, and Y—R³ can be an N-morpholinyl radical or an N-piperazyl radical,
• n=2 to 4,
• m=0 to 4 and
• R² is hydrogen, an alkyl radical having from 1 to 6 carbon atoms or a radical R¹,
• where m is not 0 when R² is not a radical R¹, Y═NR³ and Y—R³ is not an N-morpholinyl radical and not an N-piperazyl radical,
• makes it possible to avoid precipitation of a solid during the absorption of CO₂ and a separation into two liquid phases during the regeneration of the absorption medium.

Claims

1. A method of absorbing CO₂ from a gas mixture by contacting the gas mixture with an absorption medium wherein the absorption medium comprises water and at least one amine of formula (I):

2. The method of claim 1, wherein X and Y in formula (I) are each, independently of one another, NR³ or oxygen.

3. The method of claim 2, wherein Y in formula (I) is oxygen.

4. The method of claim 3, wherein R³ in formula (I) is methyl or hydrogen.

5. The method of claim 3, wherein m in formula (I) is 0.

6. The method of claim 1, wherein Y—

R³ in formula (I) is an N-morpholinyl radical or an N-piperazyl radical.

7. The method of claim 6, wherein m in formula (I) is 0.

8. The method of claim 1, wherein n in formula (I) is 2 or 3.

9. The method of claim 8, wherein n in formula (I) is 2.

10. The method of claim 1, wherein the absorption medium has a content of amines of formula (I) of from 10 to 60% by weight.

11. The method of claim 10, wherein the absorption medium has a content of amines of formula (I) of from 20 to 50% by weight.

12. The method of claim 1, wherein the gas mixture is a combustion off-gas, a natural gas or a biogas.

13. The method of claim 1, wherein CO₂ absorbed in the absorption medium is desorbed again by an increase in temperature, a reduction of pressure or both and after this desorption of CO₂ the absorption medium is used again for absorbing CO₂.

14. The method of claim 13, wherein the absorption is carried out at a temperature in the range from 0 to 80°

C. and the desorption is carried out at a higher temperature in the range from 50 to 200°

C.

15. The method of claim 13, wherein the absorption is carried out at a pressure in the range from 0.8 to 90 bar and the desorption is carried out at a lower pressure in the range from 0.01 to 10 bar.

16. The method of claim 1, wherein said amine of formula (I) is selected from the group consisting of 4-(2-hydroxyethylamino)-2,2,6,6-tetramethylpiperidine, 4-[bis(2-hydroxyethy)amino]-2,2,6,6-tetramethylpiperidine, 4-(2-methoxyethylamino)-2,2,6,6-tetramethylpiperidine, 4-(2-hydroxyethylaminoethylamino)-2,2,6,6-tetramethylpiperidine, 4-(2-piperazinoethylamino)-2,2,6,6-tetramethylpiperidine and 4-(2-morpholinopropylamino)-2,2,6,6-tetramethylpiperidine.