Process for removing carbon dioxide from gases

• US 5,618,506 A
• Filed: 08/04/1995
• Issued: 04/08/1997
• Est. Priority Date: 10/06/1994
• Status: Expired due to Term

• Current Assignee: Kansai Electric Power Company Incorporated, Mitsubishi Jukogyo Kabushiki Kaisha
• Original Assignee: Kansai Electric Power Company Incorporated, Mitsubishi Jukogyo Kabushiki Kaisha
• Inventors: Suzuki, Hitomi, Hayakawa, Atsushi, Iijima, Masaki, Mimura, Tomio, Iwaki, Toru, Mitsuoka, Shigeaki, Shimojo, Shigeru, Shimayoshi, Hidenobu
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): HARDING, AMY MARIE
• Application Number:
  US08/511,290
• Time in Patent Office: 613 Days
• Field of Search: 423/226, 423/228, 423/229
• US Class Current: 423/228
• 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: 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

This invention relates to the process for removing CO₂ from CO₂ -containing gas such as combustion gas. For example, it is the process for removing CO₂ from combustion gas through the contact of the gas at the atmospheric pressure with an aqueous solution of an amine represented by the general formula R¹ NHC(CH₃)₂ CH₂ OH in which R¹ is a lower alkyl group having 1-4 carbon atoms, or an aqueous solution containing both an amine represented by the general formula R₂ CHR₃ NHCH₂ CH₂ OH in which R² is a hydrogen atom or a lower alkyl group having 1-4 carbon atoms and R³ is a hydrogen atom or methyl group and a piperazine compound selected from the group consisting of piperazine, 2-methylpiperazine, 2,3-dimethylpiperazine, and 2,5-dimethylpiperazine, or an mixed aqueous amine solution containing a secondary amine and a tertiary amine at concentrations of 10-45% by weight each, or an aqueous solution of a piperazine derivative.

Claims

1. A process for removing CO₂ from a CO₂ -containing gas said process comprising contacting the CO₂ -containing untreated gas with an aqueous solution of an amine compound represented by the general formula (1)

View Dependent Claims (2, 3)

2. The process as claimed in claim 1 wherein the aqueous solution of the amine compound of the general formula (1) is in a concentration in the range of 15-65% by weight.

3. The process as claimed in claim 1 wherein the CO₂ -containing gas is a combustion gas at atmospheric pressure.

4. A process for removing CO₂ from combustion gases said process comprising contacting a combustion gas at atmospheric pressure with an aqueous solution containing both an amine compound (2) represented by the general formula

View Dependent Claims (5, 6)

5. The process as claimed in claim 4 wherein the piperazine compound (3) is 2-methylpiperazine and the amine compound (2) is 2-(n-butylamino)ethanol.

6. The process as claimed in claim 4 wherein the concentration of the amine compound (2) in the aqueous solution is in the range of 15-65% by weight and the concentration of the piperazine compound (3) is in the range of 1.5-65% by weight where that piperazine compound is soluble in the aqueous solution of the amine compound (2) at 30°

C., the combined concentration of (2) and (3) being not more than 70% by weight.

7. A process for removing CO₂ from combustion gases comprising contacting a combustion gas at atmospheric pressure with an aqueous solution, having a concentration of 30-50% by weight of a piperazine derivative represented by a general formula (4) ##STR2## in which R⁴ is a methyl, ethyl or group and R⁵ is hydrogen, methyl, ethyl or propyl group.

8. The process as claimed in claim 7 wherein the piperazine derivative is 2-methylpiperazine.

9. A process for removing CO₂ from combustion gases comprising:

contacting a combustion gas with an aqueous solution, at atmospheric pressure, said aqueous solution comprising an amine compound represented by formula (2)

space="preserve" listing-type="equation">R.sup.2 CHR.sup.3 NCH.sub.2 CH.sub.2 OH (2)

and a piperazine compound (3);

wherein said amine compound is 2-(n-butylamino) ethanol and said piperazine compound is 2-methylpiperazine.

10. A process for removing CO₂ from a combustion gas through contact of a combustion gas at atmospheric pressure with an aqueous amine solution wherein said mixed aqueous amine solution consists essentially of a secondary amine selected from a group consisting of 2-methylaminoethanol, 2-ethylaminoethanol, 2-isopropylaminoethanol, 2-n-butylaminoethanol, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, and 2-piperidinoethanol and a tertiary amine selected from a group consisting of 2-dimethylaminoethanol, 2-diethylaminoethanol, 3-dimethylamino-1-propanol, 4-dimethylamino-1-butanol, 2-dimethylamino-2-methyl-1-propanol, N-ethyl-N-methylethanolamino;

wherein the secondary amine and the tertiary amine are at concentrations of 10-45% by weight each;

the combined concentration of the amines in the mixed aqueous solution is not more than 70% by weight; and

the concentration of the tertiary amine in the mixed aqueous amine solution is within the range of plus and minus 10% by weight of the concentration of the tertiary amine which, when used singularly in an aqueous solution, achieves the maximum CO₂ absorption per unit volume of the singular aqueous solution, the absorption conditions being the same.

11. A process for removing CO₂ from a combustion gas through contact of a combustion gas at atmospheric pressure with an aqueous amine solution wherein said mixed aqueous amine solution consists essentially of a secondary amine selected from a group consisting of 2-methylaminoethanol, 2-ethylaminoethanol, 2-isopropylaminoethanol, 2-n-butylaminoethanol, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, and 2-piperidinoethanol and a tertiary amine selected from a group consisting of N-methyldiethanolamine, N-ethyldiethanolamine, N-t-butyldiethanolamine, and N-methyldiisopropanolamine;

wherein the secondary amine and the tertiary amine are at concentrations of 10-45% by weight each;

the combined concentration of the amines in the mixed aqueous solution is not more than 70% by weight; and

the concentration of the tertiary amine in the mixed aqueous amine solution is within the range of plus and minus 10% by weight of the concentration of the tertiary amine which, when used singularly in an aqueous solution, achieves the maximum CO₂ absorption per unit volume of the singular aqueous solution, the absorption conditions being the same.