Carbon dioxide absorbent and apparatus of separating and recovering carbon dioxide
A carbon dioxide absorbent of an embodiment includes a chain amine, a cyclic amine, and an acid. The chain amine is a compound expressed by Formula (1) of FIG. 1 . R 1 in Formula (1) is hydrogen or an alkyl chain having at least one hydroxyl group and 1 to 7 carbon atoms. R 2 in Formula (1) is an alkyl chain having at least one hydroxyl group and 1 to 7 carbon atoms. R 3 in Formula (1) is hydrogen, a straight alkyl chain having 1 to 7 carbon atoms, a branched alkyl chain having 1 to 7 carbon atoms, or a cyclic alkyl chain having 5 to 7 carbon atoms.
1. A carbon dioxide absorbent, comprising a chain amine, a cyclic amine, and an acid,
wherein a pH of the carbon dioxide absorbent before absorbing carbon dioxide is 9.5-10.8;
the chain amine is a compound of Formula (1):
wherein R 1 in Formula 1 is hydrogen or an alkyl chain having at least one hydroxyl group and 1 to 7 carbon atoms,
R 2 in Formula (1) is an alkyl chain having at least one hydroxyl group and 1 to 7 carbon atoms, and
R 3 in Formula (1) is hydrogen, a straight alkyl chain having 1 to 7 carbon atoms, a branched alkyl chain having 1 to 7 carbon atoms, or a cyclic alkyl chain having 5 to 7 carbon atoms; and
the acid is at least one selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, hydroiodic acid, acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid.
2. The absorbent according to claim 1 , wherein a pH of the carbon dioxide absorbent before absorbing carbon dioxide is 9.6-10.7.
3. The absorbent according to claim 1 , wherein a molar ratio of the cyclic amine to the acid is 1.0:0.1-1.9.
4. The absorbent according to claim 1 , wherein the cyclic amine is at least one compound selected from the group consisting of a compound of Formula (2), a compound of Formula (3), and a compound in which structures of Formulas (2) and (3) are linked with each other by a carbon chain,
R 4 in Formula (2) is an alkyl chain having 1 to 3 carbon atoms, optionally has an organic group including nitrogen as a side chain, and optionally has a hydroxyl group as a side chain,
R 5 in Formula (2) is an alkyl chain having 2 to 3 carbon atoms, optionally has an organic group including nitrogen as a side chain, and optionally has a hydroxyl group as a side chain,
R 6 in Formula (2) is hydrogen or a straight or branched alkyl chain having 1 to 4 carbon atoms, and optionally has a hydroxyl group,
R 7 in Formula (2) is hydrogen or a straight or branched alkyl chain having 1 to 4 carbon atoms, and optionally has a hydroxyl group,
R 8 in Formula (3) is a straight alkyl chain having 4 to 7 carbon atoms, optionally has an organic group including nitrogen as a side chain, and optionally has a hydroxyl group, and
R 9 in Formula (3) is hydrogen or a straight or branched alkyl chain having 1 to 4 carbon atoms, and optionally has a hydroxyl group.
5. The absorbent according to claim 1 , wherein the acid has pKa of 6.0 or less.
6. The absorbent according to claim 1 , wherein the acid is at least one selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, and hydroiodic acid.
7. The absorbent according to claim 1 , wherein the acid is at least one selected from the group consisting of acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid.
8. The absorbent according to claim 7 , wherein the acid is at least one selected from the group consisting of acetic acid, citric acid, gluconic add, lactic acid, oxalic acid, and tartaric acid.
9. An apparatus of separating and recovering carbon dioxide, the apparatus comprising the carbon dioxide absorbent according to claim 1 , the carbon dioxide absorbent being a carbon dioxide unabsorbed carbon dioxide absorbent, the apparatus comprising:
an absorption tower configured to separate and recover carbon dioxide from gas containing carbon dioxide by contacting the gas containing carbon dioxide with the carbon dioxide unabsorbed carbon dioxide absorbent to allow carbon dioxide to be absorbed in the carbon dioxide unabsorbed carbon dioxide absorbent and a carbon dioxide absorbed carbon dioxide absorbent is obtained; and
a regeneration tower configured to regenerate the carbon dioxide absorbed carbon dioxide absorbent by desorbing carbon dioxide from the carbon dioxide absorbed carbon dioxide absorbent which has absorbed carbon dioxide.