Carbon dioxide absorption method, carbon dioxide emission method, carbon dioxide absorption device, and carbon dioxide emission device

Abstract

This carbon dioxide absorption method includes a step (A) for causing a carbon dioxide absorbent (a) to absorb carbon dioxide in the absence of a liquid solvent, said carbon dioxide absorbent (a) having at least one amino group and containing an amine compound in liquid form at room temperature.

Description

Carbon dioxide absorption method, carbon dioxide release method, carbon dioxide absorption device, and carbon dioxide release device

[0001] The present invention relates to a method for absorbing carbon dioxide, a method for releasing carbon dioxide, a carbon dioxide absorption device, and a carbon dioxide releasing device. This application claims priority based on Japanese Patent Application No. 2024-040313, filed on March 14, 2024, the contents of which are incorporated herein by reference.

[0002] Carbon dioxide is a greenhouse gas, and its increasing concentration in the atmosphere causes global warming. The advancement of civilization has led to the mass consumption of fossil fuels, resulting in ever-increasing carbon dioxide emissions. In response, plants absorb carbon dioxide through photosynthesis and release oxygen. However, as deforestation progresses on a global scale, large numbers of plants have been lost, and carbon dioxide consumption has continued to decline. As a result, the concentration of carbon dioxide in the atmosphere has been rising, and various adverse effects thought to be caused by global warming have been observed on a global scale. Furthermore, carbon dioxide is not only used by plants for photosynthesis, but is also a raw material for the production of high-performance materials. Therefore, in recent years, efforts have been made to develop carbon dioxide capture technologies that absorb and release carbon dioxide.

[0003] For example, a carbon dioxide absorbent containing 1,3-diaminocyclohexane or a derivative thereof has been disclosed (see, for example, Patent Document 1). This carbon dioxide absorbent utilizes the amino group (—NH ２ ) reacts with carbon dioxide, converting the amino group into a carboxyamino group (—NH—C(═O)—OH) to form a carbamic acid compound, thereby absorbing carbon dioxide.

[0004] Special table 2019-520201 publication

[0005] However, in the method of Patent Document 1, when absorbing carbon dioxide into 1,3-diaminocyclohexane and its derivatives, it was necessary to bubble carbon dioxide in the presence of a liquid solvent. Also, when releasing carbon dioxide from a carbamic acid compound, it was necessary to bubble an inert gas in the presence of a liquid solvent under heated conditions. In other words, the method of Patent Document 1 required the use and bubbling of a liquid solvent for both absorbing and releasing carbon dioxide, resulting in a problem of poor energy efficiency.

[0006] An object of the present invention is to provide a carbon dioxide absorption method, a carbon dioxide release method, a carbon dioxide absorption device, and a carbon dioxide release device that do not require the use of a liquid solvent or bubbling.

[0007] The present invention employs the following configurations. [1] A method for absorbing carbon dioxide, comprising step (A) of allowing a carbon dioxide absorbent (a) containing an amine compound having at least one amino group and being liquid at room temperature to absorb carbon dioxide in the absence of a liquid solvent. [2] The method for absorbing carbon dioxide according to [1], wherein step (A) comprises spraying vapor of at least one solvent selected from the group consisting of water and alcohols having 1 to 6 carbon atoms onto the carbon dioxide absorbent (a). [3] The method for absorbing carbon dioxide according to [1] or [2], wherein the amine compound contains a compound represented by the following formula (1): (In formula (1), m is 0 or 1; R １ and R ２ are each independently an alkyl group, an alkoxy group, a carboxy group, an alkyloxycarbonyl group, a formyl group, an alkylcarbonyl group, an alkylthio group, a sulfo group, an alkyloxysulfonyl group, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have a substituent; L are each independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; １ and p ２ are each independently 1 or 2; when m is 0, q １ is an integer from 0 to 11, provided that p １ +q １is 12 or less, and when m is 1, q １ is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11, and q ２ is an integer from 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have a substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have a substituent, the two or more R ２may be bonded to each other to form a ring.) [4] A method for producing a carbon dioxide releasing agent (b) comprising a monocarbamic acid compound having at least one carboxyamino group, by causing the carbon dioxide absorbent (a) to absorb carbon dioxide by the method for absorbing carbon dioxide according to any one of [1] to [3]. [5] Use of a composition comprising an amine compound having at least one amino group and being a liquid at room temperature as the carbon dioxide absorbent (a) in the method for absorbing carbon dioxide according to any one of [1] to [3]. [6] Use of a composition comprising an amine compound having at least one amino group and being a liquid at room temperature for producing the carbon dioxide absorbent (a) used in the method for absorbing carbon dioxide according to any one of [1] to [3]. [7] A method for releasing carbon dioxide, comprising a step (B) of releasing carbon dioxide from a carbon dioxide releasing agent (b) comprising a monocarbamic acid compound having at least one carboxyamino group, in the absence of a liquid solvent. [8] The method for releasing carbon dioxide according to [7], wherein the step (B) comprises exposing the carbon dioxide releasing agent (b) to a reduced pressure condition, heating the carbon dioxide releasing agent (b), or blowing a desorption gas containing an inert gas onto the carbon dioxide releasing agent (b). [9] The method for releasing carbon dioxide according to [7] or [8], wherein the monocarbamic acid compound comprises a compound represented by the following formula (2): (In formula (2), m is 0 or 1; R １ and R ２ are each independently an alkyl group, an alkoxy group, a carboxy group, an alkyloxycarbonyl group, a formyl group, an alkylcarbonyl group, an alkylthio group, a sulfo group, an alkyloxysulfonyl group, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have a substituent; each L is independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; m is 1; p １ and p ２ is 1; when m is 0, q １ is an integer from 0 to 11, provided that p １ +q １ is 12 or less, and when m is 1, q １is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11, and q ２ is an integer from 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have a substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have a substituent, the two or more R ２may be bonded to each other to form a ring.)

[10] A method for producing a carbon dioxide absorbent (a) comprising an amine compound having at least one amino group and being liquid at room temperature, by releasing carbon dioxide from the carbon dioxide releasing agent (b) by the method for releasing carbon dioxide according to any one of [7] to [9].

[11] Use of a composition comprising a monocarbamic acid compound having at least one carboxyamino group as the carbon dioxide releasing agent (b) in the method for releasing carbon dioxide according to any one of [7] to [9].

[12] Use of a composition comprising a monocarbamic acid compound having at least one carboxyamino group for producing the carbon dioxide releasing agent (b) used in the method for releasing carbon dioxide according to any one of [7] to [9].

[13] A carbon dioxide absorption device used in the carbon dioxide absorption method according to any one of [1] to [3], comprising: a first reaction vessel accommodating a carbon dioxide absorbent (a) containing an amine compound having at least one amino group and being liquid at room temperature, and a first gas flow path connected to the first reaction vessel and through which a gas containing carbon dioxide flows into the first reaction vessel.

[14] A carbon dioxide release device used in the carbon dioxide release method according to any one of [7] to [9], comprising: a second reaction vessel accommodating a carbon dioxide release agent (b) containing a monocarbamic acid compound having at least one carboxyamino group, a heating unit that heats the carbon dioxide release agent (b) accommodated in the second reaction vessel, and a second gas flow path connected to the second reaction vessel and through which a gas containing carbon dioxide is released from the second reaction vessel.

[0008] According to the present invention, there are provided a method for absorbing carbon dioxide, a method for releasing carbon dioxide, a carbon dioxide absorption device, and a carbon dioxide releasing device, which do not require the use of a liquid solvent or bubbling.

[0009] 1A is a schematic diagram showing a carbon dioxide absorption device according to one embodiment of the present invention. FIG. 1B is a schematic diagram showing a carbon dioxide release device according to one embodiment of the present invention. FIG. 1C is a schematic diagram showing a carbon dioxide release device according to one embodiment of the present invention. FIG. 1D is a graph showing the measurement results of the carbon dioxide absorption efficiency and the absorption amount of carbon dioxide during absorption of carbon dioxide in Example 1A. FIG. 1E is a graph showing the measurement results of the carbon dioxide absorption efficiency and the absorption amount of carbon dioxide during absorption of carbon dioxide in Example 2A. FIG. 1F is a photograph of the state of the carbon dioxide absorbent before carbon dioxide absorption and the carbon dioxide absorbent after carbon dioxide absorption in Example 3A. FIG. 1G is a graph showing the measurement results of the carbon dioxide absorption efficiency and the absorption amount of carbon dioxide during absorption of carbon dioxide when the flow rate of a gas containing carbon dioxide is changed during absorption of carbon dioxide in Example 4A. FIG. 1G is a graph showing the measurement results of the carbon dioxide absorption efficiency when a monocarbamic acid compound of isophoronediamine is used as the carbon dioxide release agent in Example 1B. 1 is a graph showing the results of TG-DTA measurement and DSC measurement during the release of carbon dioxide when a monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane is used as a carbon dioxide releasing agent in Example 2B. ２ When heated to 100°C, CO ２ When CO is desorbed, ２ 1 is a graph showing the concentration of CO 3 in Example 3B at 80° C. ２ (b) CO at 100°C ２ In Example 4B, the CO 2 was released at each temperature when 1 mmol of a monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane was heated in a closed system. ２ 1 is a graph showing the amount of CO desorption in Example 4B when heated at (a) 90° C. and (b) 100° C.２ In Example 5B, the monocarbamic acid compound of isophoronediamine was heated to 90° C. under a nitrogen gas flow and CO ２ When CO is desorbed ２ 1 is a graph showing the concentration. FIG. 1 is a graph showing the measurement results of carbon dioxide absorption efficiency when a gas containing carbon dioxide is bubbled during carbon dioxide absorption in Comparative Example 1A. FIG. 2 is a graph showing the measurement results of carbon dioxide absorption efficiency when a gas containing carbon dioxide is supplied without bubbling during carbon dioxide absorption in Example 5A. FIG. 3 is a graph showing the measurement results of the amount of carbon dioxide released when the heating temperature and heating time are changed during carbon dioxide release in Example 6A. FIG. 4 is a diagram showing the measurement device used in Example 7. FIG. 5 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 7. FIG. 6 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 8. FIG. 7 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 9. FIG. 8 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 10. FIG. 9 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 11. FIG. 10 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 12. (a) and (b) are graphs showing the measurement results of carbon dioxide release efficiency in Example 13. 14 is a graph showing the measurement results of carbon dioxide absorption efficiency and absorption amount in Example 14. FIG. 15 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 15. FIG. 16 is a graph showing the measurement results of carbon dioxide release efficiency in Example 16. (a) is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 17. (b) is a graph showing the measurement results of carbon dioxide release efficiency in Example 17. FIG. 17 is a graph showing the carbon dioxide absorption amount and carbon dioxide release amount measured in Example 17. FIG. 18 is a graph showing the measurement results of carbon dioxide absorption efficiency in Example 17. １３10 is a graph showing the results of C-NMR measurement. 11 is a graph showing the results of X-ray crystal structure analysis measurement in Example 19. 12(a) is a graph showing the results of measurement of weight change when a transparent solid is heated in Example 20. 13(b) is a graph showing the results of measurement of weight change when a white solid is heated in Example 20. 14 is a graph showing the amounts of carbon dioxide absorbed and released measured in Example 21.

[0010] <<Method for Absorbing Carbon Dioxide>> The method for absorbing carbon dioxide of the present invention includes a step (A) of absorbing carbon dioxide in the absence of a liquid solvent using a carbon dioxide absorbent (a) containing an amine compound that has at least one amino group and is liquid at room temperature. Examples of the amine compound include monoamine compounds having one amino group and polyamine compounds having multiple amino groups, with diamine compounds having two amino groups being preferred. The amino groups of these amine compounds are preferably primary or secondary amino groups, with primary amino groups being more preferred because they enhance carbon dioxide absorption capacity. It is preferred that the amine compound does not have a tertiary amino group.

[0011] <Carbon dioxide absorbent (a)> In the present invention, the carbon dioxide absorbent (a) contains an amine compound that has at least one amino group and is liquid at room temperature. Examples of the amine compound include monoamine compounds that have one amino group and are liquid at room temperature, and polyamine compounds that have multiple amino groups and are liquid at room temperature. Of these, diamine compounds that have two amino groups and are liquid at room temperature are preferred. In this specification, "liquid at room temperature" means a liquid state at 10 to 30°C. Examples of the diamine compound include a compound represented by the following formula (1) (hereinafter also referred to as compound (1)):

[0012]

[0013] (In formula (1), m is 0 or 1; R １ and R ２are each independently an alkyl group, an alkoxy group, a carboxy group, an alkyloxycarbonyl group, a formyl group, an alkylcarbonyl group, an alkylthio group, a sulfo group, an alkyloxysulfonyl group, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have a substituent; L are each independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; １ and p ２ are each independently 1 or 2; when m is 0, q １ is an integer from 0 to 11, provided that p １ +q １ is 12 or less, and when m is 1, q １ is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11, and q ２ is an integer from 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have a substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have a substituent, the two or more R ２ may be bonded to each other to form a ring.

[0014] In this specification, when a specific compound is assumed to have a structure in which one or more hydrogen atoms are substituted with a group other than a hydrogen atom, the compound having such a substituted structure is referred to as a "derivative" of the specific compound. In this specification, unless otherwise specified, the term "group" includes not only an atomic group formed by bonding multiple atoms but also a single atom.

[0015] In general formula (1), R１ and R ２ each independently represents an alkyl group, an alkoxy group, a carboxy group (-C(=O)-OH), an alkyloxycarbonyl group, a formyl group (-C(=O)-H), an alkylcarbonyl group (acyl group), an alkylthio group, a sulfo group (-SO ３ H), alkyloxysulfonyl group, nitro group (-NO ２ ), a hydroxyl group (—OH), a thiol group (mercapto group, —SH), a cyano (—CN) group, or a halogen atom, and the alkyl group may have a substituent. １ and R ２ These groups in may be the same or different.

[0016] R １ and R ２ The alkyl group in the formula (I) may be linear, branched, or cyclic.

[0017] R １ and R ２The number of carbon atoms in the linear or branched alkyl group in the formula (I) is not particularly limited, but is preferably 1 to 20. Examples of such linear or branched alkyl groups include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylbutyl group, an n-hexyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, an n-heptyl group, a 2-methylhexyl group, a 2,3-dimethylbutyl group, a 2-methylhexyl group, a 2,4-dimethylbutyl group, a 2,5-dimethylbutyl group, a 2,6-dimethylbutyl group, a 2,7-dimethylbutyl group, a 2,8-dimethylbutyl group, a 2,9-dimethylbutyl group, a 2,10-dimethylbutyl group, a 2,11-dimethylbutyl group, a 2,12-dimethylbutyl group, a 2,13-dimethylbutyl group, a 2,14-dimethylbutyl group, a 2,15-dimethylbutyl group, a 2,16-dimethylbutyl group, a 2,17-dimethylbutyl group, a 2,18-dimethylbutyl group, a 2,19-dimethylbutyl group, a 2,20-dimethylbutyl group, a 2,21-dimethylbutyl group, a 2,22-dimethylbutyl group, a 2,23-dimethylbutyl group, a 2,24-dimethylbutyl group, a 2,25-dimethylbutyl group, a 2,26-dimethylbutyl group, a 2,27-dimethylbutyl group, a 2,28-dimethylbutyl group, a 2,29-dimethylbutyl group, a 2,30-dimethylbutyl group, a 2,31-dimethylbutyl Examples of such alkyl groups include methyl silyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, n-octyl, isooctyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl. The linear or branched alkyl group more preferably has 1 to 10 carbon atoms, and may have, for example, 1 to 7, 1 to 5, or 1 to 3 carbon atoms.

[0018] R １ and R ２ In the formula (I), the cyclic alkyl group may be either monocyclic or polycyclic. The number of carbon atoms in the cyclic alkyl group is not particularly limited as long as it is 3 or more, but is preferably 3 to 20. Examples of the cyclic alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a norbornyl group, an isobornyl group, a 1-adamantyl group, a 2-adamantyl group, and a tricyclodecyl group. The number of carbon atoms in the cyclic alkyl group is more preferably 3 to 15, and may be, for example, any one of 3 to 10, 3 to 7, and 3 to 5, or any one of 5 to 15, 5 to 10, and 5 to 7.

[0019] R １ and R ２The alkyl group in the formula (I) may be a mixture of a linear or branched chain structure and a cyclic structure. Examples of the alkyl group having a mixture of a linear structure and a cyclic structure include monovalent groups having a structure in which one or more hydrogen atoms in the linear or branched alkyl group described above are substituted with the cyclic alkyl group described above, such as a cyclopentylmethyl group, a 1-cyclopentylethyl group, a cyclohexylmethyl group, and a 1-cyclohexylethyl group; and monovalent groups having a structure in which one or more hydrogen atoms in the cyclic alkyl group described above are substituted with the linear or branched alkyl group described above, such as a methylcyclopentyl group, an ethylcyclopentyl group, a methylcyclohexyl group, an ethylcyclohexyl group, and a dimethylcyclohexyl group. The number of carbon atoms in the alkyl group having a mixture of a linear structure and a cyclic structure is not particularly limited as long as it is 4 or more, but is preferably 4 to 25, and may be, for example, 6 to 15 or 6 to 10.

[0020] In this specification, an alkyl group that has only a chain structure and does not have a cyclic structure is a chain alkyl group, and an alkyl group that has a cyclic structure, regardless of whether it has a chain structure or not, is a cyclic alkyl group.

[0021] R １ and R ２ The alkyl groups in the formula (I) are each independently preferably an alkyl group having 1 to 10 carbon atoms (a linear alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms), and more preferably an alkyl group having 1 to 5 carbon atoms (a linear alkyl group having 1 to 5 carbon atoms, a cyclic alkyl group having 3 to 5 carbon atoms).

[0022] R １ and R ２ The alkyl group in the formula (I) may have a substituent. The alkyl group having a substituent means that one or more hydrogen atoms in the alkyl group are substituted with a group other than a hydrogen atom.

[0023] When the alkyl group has two or more substituted hydrogen atoms, the substituents may all be the same, all be different, or only some may be the same.

[0024] In the alkyl group, the substitution position of the hydrogen atom is not particularly limited.For example, when two or more hydrogen atoms that can be substituted with a substituent are bonded to one carbon atom in the alkyl group, only one of them may be substituted with a substituent, or two or more of them may be substituted with a substituent.For example, when the alkyl group has a chain structure, the substitution position may be a terminal carbon atom or a non-terminal carbon atom of the chain structure.

[0025] R １ and R ２ When the alkyl group in the formula (I) has a substituent, the number of the substituents depends on the number of hydrogen atoms that can be substituted, but in general, it is preferably 1 to 3, and more preferably 1 or 2.

[0026] Examples of the substituent include an amino group, a cyano group, a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), and a hydroxyl group.

[0027] A preferred example of the alkyl group having a substituent is an aminoalkyl group having an amino group as a substituent, and a more preferred example is an aminoalkyl group in which an amino group is bonded to the terminal carbon atom of a chain (straight-chain or branched-chain) alkyl group.

[0028] R １ and R ２ The alkoxy group in R may be linear, branched, or cyclic. １ and R ２ Examples of the alkoxy group in ３ —O—), cyclopropyloxy group (C ３ H ５ —O—), cyclopentylmethyloxy group (C ５ H ９ -CH ２—O—), methylcyclopentyloxy group (CH ３ -C ５ H ８ -O-) and the like. １ and R ２ and monovalent groups having a structure in which the linear, branched, or cyclic alkyl group shown in the formula (I) is bonded to an oxygen atom.

[0029] The number of carbon atoms in the linear or branched alkoxy group is preferably 1 to 20, more preferably 1 to 10, and may be, for example, any one of 1 to 7, 1 to 5, and 1 to 3. The number of carbon atoms in the cyclic alkoxy group is preferably 3 to 20, more preferably 3 to 15, and may be, for example, any one of 3 to 10, 3 to 7, and 3 to 5, or any one of 5 to 15, 5 to 10, and 5 to 7. The number of carbon atoms in the alkoxy group having a mixed chain structure and a cyclic structure is not particularly limited as long as it is 4 or more, but is preferably 4 to 25, and may be, for example, any one of 6 to 15 and 6 to 10.

[0030] In this specification, an alkoxy group that has only a chain structure and does not have a cyclic structure is a chain alkoxy group, and an alkoxy group that has a cyclic structure, regardless of whether it has a chain structure or not, is a cyclic alkoxy group.

[0031] R １ and R ２ The alkoxy groups in the formula (I) are each independently preferably an alkoxy group having 1 to 10 carbon atoms (a chain alkoxy group having 1 to 10 carbon atoms, or a cyclic alkoxy group having 3 to 10 carbon atoms), and more preferably an alkoxy group having 1 to 5 carbon atoms (a chain alkoxy group having 1 to 5 carbon atoms, or a cyclic alkoxy group having 3 to 5 carbon atoms).

[0032] R １ and R ２ Examples of the alkyloxycarbonyl group in ３ —O—C(═O)—), cyclopropyloxycarbonyl group (C ３ H ５—O—C(═O)—), cyclopentylmethyloxycarbonyl group (C ５ H ９ -CH ２ —O—C(═O)—), methylcyclopentyloxycarbonyl group (CH ３ -C ５ H ８ -O-C(=O)-) and the like. １ and R ２ and monovalent groups having a structure in which the linear, branched, or cyclic alkyl group in the formula (I) is bonded to an oxygen atom that is not constituting a carbonyl group (—C(═O)—) in an oxycarbonyl group (—O—C(═O)—).

[0033] When the alkyl group is linear or branched, the number of carbon atoms in the alkyloxycarbonyl group is preferably 2 to 21, more preferably 2 to 11, and may be, for example, any one of 2 to 8, 2 to 6, and 2 to 4. When the alkyl group is cyclic, the number of carbon atoms in the alkyloxycarbonyl group is preferably 4 to 21, more preferably 4 to 16, and may be, for example, any one of 4 to 11, 4 to 8, and 4 to 6, or any one of 6 to 16, 6 to 11, and 6 to 8. When the alkyl group is a mixture of a linear structure and a cyclic structure, the number of carbon atoms in the alkyloxycarbonyl group is not particularly limited as long as it is 5 or more, but is preferably 5 to 26, and may be, for example, any one of 7 to 16 and 7 to 11.

[0034] R １ and R ２ The alkyloxycarbonyl groups in the formula (I) are each preferably an alkyloxycarbonyl group having 2 to 11 carbon atoms, and more preferably an alkyloxycarbonyl group having 2 to 6 carbon atoms.

[0035] R １ and R ２ Examples of the alkylcarbonyl group in ３ -C(=O)-), cyclopropylcarbonyl group (C ３ H ５-C(=O)-), cyclopentylmethylcarbonyl group (C ５ H ９ -CH ２ —C(═O)—), methylcyclopentylcarbonyl group (CH ３ -C ５ H ８ -C(=O)-) and the like. １ and R ２ and monovalent groups having a structure in which the linear, branched, or cyclic alkyl group in the formula (I) is bonded to a carbon atom in a carbonyl group (—C(═O)—).

[0036] When the alkyl group is linear or branched, the number of carbon atoms in the alkylcarbonyl group is preferably 2 to 21, more preferably 2 to 11, and may be, for example, any one of 2 to 8, 2 to 6, and 2 to 4. When the alkyl group is cyclic, the number of carbon atoms in the alkylcarbonyl group is preferably 4 to 21, more preferably 4 to 16, and may be, for example, any one of 4 to 11, 4 to 8, and 4 to 6, or any one of 6 to 16, 6 to 11, and 6 to 8. When the alkyl group is a mixture of a linear structure and a cyclic structure, the number of carbon atoms in the alkylcarbonyl group is not particularly limited as long as it is 5 or more, but is preferably 5 to 26, and may be, for example, any one of 7 to 16 and 7 to 11.

[0037] R １ and R ２ The alkylcarbonyl groups in the formula (I) are each independently preferably an alkylcarbonyl group having 2 to 11 carbon atoms, and more preferably an alkylcarbonyl group having 2 to 6 carbon atoms.

[0038] R １ and R ２ The alkylthio group in R may be linear, branched, or cyclic. １ and R ２ Examples of the alkylthio group in ３ -S-), cyclopropylthio group (C ３ H ５-S-), cyclopentylmethylthio group (C ５ H ９ -CH ２ -S-), methylcyclopentylthio group (CH ３ -C ５ H ８ -S-) and the like, １ and R ２ Examples of such alkylthio groups include monovalent groups having a structure in which the linear, branched, or cyclic alkyl group in the formula (I) is bonded to a sulfur atom. The linear or branched alkylthio group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and may be, for example, any of 1 to 7, 1 to 5, and 1 to 3 carbon atoms. The cyclic alkylthio group preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and may be, for example, any of 3 to 10, 3 to 7, and 3 to 5 carbon atoms, or any of 5 to 15, 5 to 10, and 5 to 7 carbon atoms. The alkylthio group having a mixed linear structure and a cyclic structure may have any number of carbon atoms, as long as it is 4 or more, but is preferably 4 to 25 carbon atoms, and may be, for example, any of 6 to 15 and 6 to 10 carbon atoms.

[0039] In this specification, an alkylthio group having only a chain structure and not a cyclic structure is a chain alkylthio group, and an alkylthio group having a cyclic structure, regardless of whether it has a chain structure or not, is a cyclic alkylthio group.

[0040] R １ and R ２ The alkylthio groups in the formula (I) are each independently preferably an alkylthio group having 1 to 10 carbon atoms (a chain alkylthio group having 1 to 10 carbon atoms, or a cyclic alkylthio group having 3 to 10 carbon atoms), and more preferably an alkylthio group having 1 to 5 carbon atoms (a chain alkylthio group having 1 to 5 carbon atoms, or a cyclic alkylthio group having 3 to 5 carbon atoms).

[0041] R １ and R ２ Examples of the alkyloxysulfonyl group in ３ -O-SO ２-), cyclopropyloxysulfonyl group (C ３ H ５ -O-SO ２ -), cyclopentylmethyloxysulfonyl group (C ５ H ９ -CH ２ -O-SO ２ -), methylcyclopentyloxysulfonyl group (CH ３ -C ５ H ８ -O-SO ２ -), etc., １ and R ２ wherein the linear, branched or cyclic alkyl group is an oxysulfonyl group (—O—SO ２ A sulfonyl group (-SO ２ Examples of such groups include monovalent groups having a structure in which the oxygen atom bonded to an oxygen atom that does not constitute a group (-).

[0042] When the alkyl group is linear or branched, the number of carbon atoms in the alkyloxysulfonyl group is preferably 1 to 20, more preferably 1 to 10, and may be, for example, any one of 1 to 7, 1 to 5, and 1 to 3. When the alkyl group is cyclic, the number of carbon atoms in the alkyloxysulfonyl group is preferably 3 to 20, more preferably 3 to 15, and may be, for example, any one of 3 to 10, 3 to 7, and 3 to 5, or any one of 5 to 15, 5 to 10, and 5 to 7. When the alkyl group is a mixture of a linear structure and a cyclic structure, the number of carbon atoms in the alkyloxysulfonyl group is not particularly limited as long as it is 4 or more, but is preferably 4 to 25, and may be, for example, any one of 6 to 15 and 6 to 10.

[0043] R １ and R ２ The alkyloxysulfonyl groups in the formula (I) are each independently preferably an alkyloxysulfonyl group having 1 to 10 carbon atoms, and more preferably an alkyloxysulfonyl group having 1 to 5 carbon atoms.

[0044] R １ and R ２Examples of the halogen atom in the above formula include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0045] R １ and R ２ each independently represents an alkyl group having 1 to 10 carbon atoms (a linear alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms), an alkoxy group having 1 to 10 carbon atoms (a linear alkoxy group having 1 to 10 carbon atoms, a cyclic alkoxy group having 3 to 10 carbon atoms), a carboxy group, an alkyloxycarbonyl group having 2 to 11 carbon atoms (an alkyloxycarbonyl group having 2 to 11 carbon atoms when the alkyl group is linear or branched, an alkyloxycarbonyl group having 4 to 11 carbon atoms when the alkyl group is cyclic), a formyl group, and an alkylcarbonyl group having 2 to 11 carbon atoms, each of which may have an amino group as the substituent. It is preferable that the alkyl group is one or more selected from the group consisting of (an alkylcarbonyl group having 2 to 11 carbon atoms when the alkyl group is linear or branched, and an alkylcarbonyl group having 4 to 11 carbon atoms when the alkyl group is cyclic), an alkylthio group having 1 to 10 carbon atoms (a linear alkylthio group having 1 to 10 carbon atoms, a cyclic alkylthio group having 3 to 10 carbon atoms), a sulfo group, and an alkyloxysulfonyl group having 1 to 10 carbon atoms (an alkyloxysulfonyl group having 1 to 10 carbon atoms when the alkyl group is linear or branched, and an alkyloxysulfonyl group having 3 to 11 carbon atoms when the alkyl group is cyclic). １ and R ２are each independently one or more selected from the group consisting of an alkyl group having 1 to 5 carbon atoms (a linear alkyl group having 1 to 5 carbon atoms, a cyclic alkyl group having 3 to 5 carbon atoms), an alkoxy group having 1 to 5 carbon atoms (a linear alkoxy group having 1 to 5 carbon atoms, a cyclic alkoxy group having 3 to 5 carbon atoms), an alkyloxycarbonyl group having 2 to 6 carbon atoms (an alkyloxycarbonyl group having 2 to 6 carbon atoms when the alkyl group is linear or branched, an alkyloxycarbonyl group having 4 to 6 carbon atoms when the alkyl group is cyclic), a formyl group, an alkylcarbonyl group having 2 to 6 carbon atoms (an alkylcarbonyl group having 2 to 6 carbon atoms when the alkyl group is linear or branched, an alkylcarbonyl group having 4 to 6 carbon atoms when the alkyl group is cyclic), and an alkylthio group having 1 to 5 carbon atoms (a linear alkylthio group having 1 to 5 carbon atoms, a cyclic alkylthio group having 3 to 3 carbon atoms).

[0046] In general formula (1), each L is independently a divalent or higher organic group, a carbonyl group, -O-, or -S-. Examples of the divalent or higher organic group include an alkylene group having 1 to 10 carbon atoms and an alkenylene group having 2 to 10 carbon atoms. A carbon atom in the alkylene group having 1 to 10 carbon atoms and the alkenylene group having 2 to 10 carbon atoms may be substituted with an oxygen atom or a sulfur atom. Examples of the alkylene group having 1 to 10 carbon atoms include a linear alkylene group having 1 to 10 carbon atoms, a branched alkylene group having 3 to 10 carbon atoms, and a cycloalkylene group having 3 to 10 carbon atoms. Examples of the linear alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, an n-propylene group, and an n-butylene group. Examples of the branched alkylene group having 3 to 10 carbon atoms include a 1-methylethylene group, a 2-methylethylene group, a 1,1-dimethylethylene group, a 1,2-dimethylethylene group, a 2,2-dimethylethylene group, a 1-ethylethylene group, etc. Examples of the cycloalkylene group having 3 to 10 carbon atoms include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, etc.

[0047] In general formula (1), p １ and p ２are each independently 1 or 2. That is, p １ and p ２ may be the same as or different from each other. １ defines the number of amino groups directly bonded to a carbon atom constituting one of the cyclohexane ring skeletons in compound (1). ２ defines the number of amino groups directly bonded to the carbon atom constituting the other cyclohexane ring skeleton in compound (1).

[0048] In the general formula (1), when m is 0, q １ is an integer from 0 to 11, provided that p １ +q １ is equal to or less than 12. On the other hand, when m is 1, q １ is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11. １ is an R bonded directly to a carbon atom constituting one of the cyclohexane ring skeletons in compound (1). １ The number of

[0049] m is 0, and q １ is an integer of 2 or more (2 to 11), and m is 1 and q １ is an integer of 2 or more (2 to 10), and in either case, two or more R １ may be the same or different from each other. That is, two or more R １ may all be the same, may all be different, or may only be partially the same.

[0050] In general formula (1), q ２ is an integer from 0 to 10. ２ is an R bonded directly to the carbon atom constituting the other cyclohexane ring skeleton in compound (1). ２ The number of

[0051] q ２ is an integer of 2 or more (2 to 10), two or more R ２ may be the same or different from each other. That is, two or more R ２may all be the same, may all be different, or may only be partially the same.

[0052] m is 0 and q １ is an integer of 2 or more (2 to 11), and two or more R １ is an alkyl group which may have a substituent, and m is 1 and q １ is an integer of 2 or more (2 to 10), and two or more R １ is an alkyl group which may have a substituent, and in either case, the two or more R １ (an alkyl group which may have a substituent) are bonded to each other, and these R １ may form a ring together with the group in the cyclohexane ring skeleton to which two or more R １ The ring formed by mutual bonding is an aliphatic ring containing only carbon atoms as atoms forming the ring skeleton. １ The bonding positions between R １ When R has a chain structure, the bonding position may be a terminal carbon atom of the chain structure or a non-terminal carbon atom. １ The number of bonding sites between the rings may be 1 or 2 or more. That is, the ring may be either monocyclic or polycyclic.

[0053] q ２ is an integer of 2 or more (2 to 10), and two or more R ２ is an alkyl group which may have a substituent, the two or more R ２ (an alkyl group which may have a substituent) are bonded to each other, and these R ２ may form a ring together with the group in the cyclohexane ring skeleton to which two or more R ２ The embodiment in which two or more R １ are bonded to each other to form a ring. ２The ring formed by mutual bonding of two or more R １ The rings may be the same as those formed by bonding together, and these rings may be the same as or different from each other.

[0054] q １ and q ２ For example, when m is 0, q is preferably 0 to 6, and more preferably 0 to 4. １ and q ２ For example, when m is 1, it is preferably 0 to 4, and more preferably 0 to 2.

[0055] The diamine compound is preferably, for example, a compound represented by the following formula (1A) or (1B).

[0056]

[0057] (In formula (1A), R １２ are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a carboxy group, an alkyloxycarbonyl group having 2 to 11 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 11 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, a sulfo group, an alkyloxysulfonyl group having 1 to 10 carbon atoms, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; R １２ at least one of the groups is an alkyl group having 1 to 10 carbon atoms and having an amino group as a substituent; and q １２ is an integer from 1 to 11, and q １２ is an integer of 2 or more, two or more R １２ may be the same or different, and q １２ is an integer of 2 or more, and two or more R １２ is the alkyl group, the two or more R １２ may be bonded to each other to form a ring.

[0058] (In formula (1B), R １３ and R ２１are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a carboxy group, an alkyloxycarbonyl group having 2 to 11 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 11 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, a sulfo group, an alkyloxysulfonyl group having 1 to 10 carbon atoms, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; L are each independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; q １３ and q ２１ are each independently an integer of 0 to 10, and q １３ is an integer of 2 or more, two or more R １３ may be the same or different, and q ２１ is an integer of 2 or more, two or more R ２１ may be the same or different, and q １３ is an integer of 2 or more, and two or more R １３ is the alkyl group, the two or more R １３ may be bonded to each other to form a ring, and q ２１ is an integer of 2 or more, and two or more R ２１ is the alkyl group, the two or more R ２１ may be bonded to each other to form a ring.

[0059] These groups include the same groups as those explained in formula (1).

[0060] As the diamine compound, for example, a compound represented by the following formula (11A) or (11B) is more preferable.

[0061]

[0062] (In formula (11A), R １２１are each independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkyloxycarbonyl group having 2 to 6 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; q １２１ are each independently an integer of 0 to 10, and q １２１ is an integer of 2 or more, two or more R １２１ may be the same or different, and q １２１ is an integer of 2 or more, and two or more R １２１ is the alkyl group, the two or more R １２１ may be bonded to each other to form a ring; R １２２ is an alkylene group having 1 to 5 carbon atoms.

[0063] (In formula (11B), R １３１ and R ２１１ are each independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkyloxycarbonyl group having 2 to 6 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; q １３１ and q ２１１ are each independently an integer of 0 to 10, and q １３１ is an integer of 2 or more, two or more R １３１ may be the same or different, and q ２１１ is an integer of 2 or more, two or more R ２１１ may be the same or different, and q １３１ is an integer of 2 or more, and two or more R １３１ is the alkyl group, the two or more R １３１ may be bonded to each other to form a ring, and q ２１１ is an integer of 2 or more, and two or more R ２１１ is the alkyl group, the two or more R ２１１may be bonded to each other to form a ring.

[0064] These groups include the same groups as those explained in formula (1).

[0065] As the diamine compound, for example, a compound represented by the following formula (111A) or (111B) is more preferable.

[0066]

[0067] The compound represented by the formula (111A) above is isophoronediamine, which has excellent carbon dioxide absorption capacity. The compound represented by the formula (111B) above is 4,4'-methylenebis(2-methylcyclohexylamine), and the monocarbamic acid compound produced by reacting this compound with carbon dioxide has excellent carbon dioxide release capacity. This is thought to be because this monocarbamic acid compound is thermodynamically unstable and therefore easily releases carbon dioxide. High carbon dioxide absorption capacity typically increases the amount of energy required to release carbon dioxide, so there is a trade-off between carbon dioxide absorption capacity and release capacity. However, 4,4'-methylenebis(2-methylcyclohexylamine) has both high carbon dioxide absorption capacity and high release capacity, so this trade-off problem can be overcome and energy consumption can be reduced. Among these, 4,4'-methylenebis(2-methylcyclohexylamine) is more preferred in terms of both carbon dioxide absorption capacity and release capacity.

[0068] In the carbon dioxide absorbent (a) of this embodiment, the active ingredient that absorbs carbon dioxide is preferably compound (1). That is, compound (1) has reactivity with carbon dioxide (in other words, absorbing ability), and the reaction product of compound (1) and carbon dioxide has the ability to release carbon dioxide.

[0069] More specifically, when the compound (1) is isophoronediamine represented by formula (111A), the amino group (—NH ２) reacts with carbon dioxide, and a monocarbamic acid compound is obtained in which the amino group is converted into a carboxyamino group (—NH—C(═O)—OH). Compound (1) is converted into the monocarbamic acid compound, and is thereby made capable of releasing carbon dioxide. In some cases, the carboxyamino group may be converted into a group of the formula “—NH—C(═O)—OH.” － " or a group represented by the formula "-NH ２ ＋ -C(=O)-O － ", but even if the carboxyamino group is ionized, this does not have any effect on the release of carbon dioxide. From the viewpoint of energy efficiency in the release of carbon dioxide, which will be described later, the monocarbamic acid compound further has the remaining amino group (-CH ２ -NH ２ ) does not react with carbon dioxide. In other words, it is preferable that compound (1) is not converted into a compound having two carboxyamino groups (—NH—C(═O)—OH). The monocarbamic acid compound releases carbon dioxide from the carboxyamino group and reforms an amino group. As a result, the monocarbamic acid compound returns to compound (1), and compound (1) can be reused as carbon dioxide absorbent (a). In other words, compound (1) can repeatedly absorb and release carbon dioxide.

[0070] In the present invention, the vapor pressure of the amine compound at 25°C is preferably 0.01 to 10 Pa, more preferably 0.01 to 4 Pa, and even more preferably 0.01 to 0.1 Pa. In the present invention, the boiling point of the amine compound is preferably 180 to 350°C, more preferably 230 to 350°C, and even more preferably 300 to 350°C.

[0071] In the present invention, the amount of carbon dioxide absorbed per 1 mol of the amine compound is preferably 0.5 to 1.5 mol, more preferably 0.6 to 1.5 mol, and even more preferably 0.7 to 1.5 mol.

[0072] In the present invention, diamine compounds represented by the following formulas (3) and (4) (hereinafter also referred to as compounds (3) and (4)) and monoamine compounds represented by the following formulas (5) and (6) (hereinafter also referred to as compounds (5) and (6)) can also be used as the carbon dioxide absorbent (a).

[0073]

[0074] In formula (3), L １ and L ２ are each independently an alkylene group having 1 to 6 carbon atoms, and n １ and n ２ are each independently a number from 0 to 6. In formula (4), L ３ and L ４ are each independently an alkylene group having 1 to 6 carbon atoms, and n ３ and n ４ are each independently a number from 0 to 6. In formula (5), p １ is a number from 2 to 6. In formula (6), q １ and q ２ are each independently a number from 2 to 6.

[0075] As the amine compound, for example, compounds represented by the following formulas (3A) to (6A) are more preferable.

[0076]

[0077] <Liquid Solvent> The carbon dioxide absorbent (a) of the present invention may or may not contain a trace amount of liquid solvent, but it is preferable to include it because it makes it easier to adjust the viscosity of the carbon dioxide absorbent (a). The amount of liquid solvent added to the carbon dioxide absorbent (a) is preferably 0.5 to 5 mL, more preferably 0.7 to 3 mL, and even more preferably 0.8 to 1.5 mL, per 100 mmol of carbon dioxide absorbent (a). When the amount of liquid solvent is within the above range, it becomes easier to adjust the viscosity of the carbon dioxide absorbent (a), and the surface area of ​​the carbon dioxide absorbent (a) tends to increase when absorbing carbon dioxide, making it easier to improve the carbon dioxide absorption efficiency. Furthermore, by adjusting the viscosity, monocarbamic acid produced after carbon dioxide absorption precipitates, making it easier for unreacted carbon dioxide absorbent (a) to appear on the surface, making it easier to improve the carbon dioxide absorption efficiency. The viscosity of the carbon dioxide absorbent (a) when a liquid solvent is added is preferably 10 to 80 mPa·s, more preferably 20 to 70 mPa·s, and even more preferably 35 to 50 mPa·s. If the viscosity of the carbon dioxide absorbent (a) is within the above range, the surface area of ​​the carbon dioxide absorbent (a) is likely to increase when absorbing carbon dioxide, making it easier to improve the carbon dioxide absorption efficiency. Furthermore, if the viscosity is within the above range, monocarbamic acid produced after carbon dioxide absorption precipitates, making it easier for unreacted carbon dioxide absorbent (a) to appear on the surface, making it easier to improve the carbon dioxide absorption efficiency.

[0078] In this specification, "room temperature" means a temperature that is neither particularly cold nor hot, that is, an ordinary temperature, and examples thereof include temperatures of 15°C to 30°C.

[0079] Examples of the liquid solvent include water and alcohols such as methanol and ethanol, and among these, water is preferred from the viewpoint of carbon dioxide absorption efficiency.

[0080] The content of compound (1) in the carbon dioxide absorbent (a) is not particularly limited, but is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, particularly preferably 99% by mass or more, and may be 100% by mass, relative to the total mass of the carbon dioxide absorbent (a). When the proportion is within the above range, the amount of carbon dioxide absorbed by the carbon dioxide absorbent (a) is further increased.

[0081] The carbon dioxide absorbent (a) may contain other components that do not fall under either the compound (1) or the liquid solvent, as long as the effects of the present invention are not impaired. The other components can be selected arbitrarily depending on the purpose and are not particularly limited. The other components may be, for example, any components other than liquid solvents such as amine compounds, water, and organic solvents, and a base such as an inorganic base or an organic base may be added from the viewpoint of enhancing carbon dioxide absorption capacity.

[0082] The carbon dioxide absorbent (a) may contain only one kind of other component, or two or more kinds of other components. When the carbon dioxide absorbent (a) contains two or more kinds of other components, the combination and ratio thereof can be arbitrarily selected depending on the purpose.

[0083] When the carbon dioxide absorbent (a) contains the other component, the content (parts by mass) of the other component is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less, relative to the total mass of the carbon dioxide absorbent (a). When the content is equal to or less than the upper limit, the amount of carbon dioxide absorbed by the carbon dioxide absorbent (a) is further increased.

[0084] The carbon dioxide absorbent (a) of the present invention exhibits excellent effects in that it can easily absorb carbon dioxide and also easily release the absorbed carbon dioxide. Conventional carbon dioxide absorbents, for example, consume a large amount of energy when easily absorbing and releasing carbon dioxide. In contrast, the carbon dioxide absorbent (a) of the present embodiment solves the conventional problems by containing a compound (1) having a structure within a specific range as an active ingredient that absorbs carbon dioxide and releases the absorbed carbon dioxide.

[0085] <Step (A)> In the step (A), carbon dioxide is absorbed into the carbon dioxide absorbent (a) in the absence of a liquid solvent. In the step (A), when the carbon dioxide absorbent (a) containing, for example, compound (1) is used, the amino group of compound (1) in the carbon dioxide absorbent (a) reacts with carbon dioxide and is converted into a monocarbamic acid compound (a compound represented by the following formula (2), hereinafter also referred to as compound (2)), thereby absorbing carbon dioxide.

[0086]

[0087] When compounds (3) to (6) are used instead of compound (1) as the compounds contained in the carbon dioxide absorbent (a), carbon dioxide is absorbed by converting them into the following monocarbamic acid compounds (7) to (10) (hereinafter also referred to as compounds (7) to (10)):

[0088]

[0089] Examples of the monocarbamic acid compound include the same compounds as those described in the carbon dioxide releasing method described below.

[0090] In the step (A), for example, a gas containing carbon dioxide may be brought into contact with the carbon dioxide absorbent (a). In particular, the step (A) can be more easily carried out by using a liquid carbon dioxide absorbent (a) containing the compound (1).

[0091] Carbon dioxide (gas) may be absorbed by the carbon dioxide absorbent (a) alone, or may be absorbed by the carbon dioxide absorbent (a) in the form of a mixed gas with another gas. As the mixed gas, for example, a gaseous target material containing carbon dioxide and from which carbon dioxide is to be recovered may be used as is, or the target material may be further mixed with another gas and diluted before use. As the mixed gas, for example, air may be used. As another mixed gas, for example, a mixed gas containing carbon dioxide and an inert gas may be mentioned. However, the mixed gases listed here are only examples.

[0092] Examples of the inert gas include nitrogen gas, helium gas, argon gas, etc. Among these, nitrogen gas is particularly suitable because it is inexpensive.

[0093] In the gas containing carbon dioxide, the concentration of carbon dioxide relative to the total volume of the gas containing carbon dioxide may be, for example, any one of 100% by volume or less, 90% by volume or less, 80% by volume or less, 60% by volume or less, and 40% by volume or less. In the gas containing carbon dioxide, the concentration of carbon dioxide relative to the total volume of the gas containing carbon dioxide may be, for example, any one of 0.01% by volume or more, 0.02% by volume or more, 0.03% by volume or more, and 0.04% by volume or more.

[0094] In the carbon dioxide absorption method of the present invention, the use of the carbon dioxide absorbent (a) not only makes it possible to easily absorb carbon dioxide but also makes it possible to use the mixed gas having a wide range of carbon dioxide concentrations as described above, and is therefore highly useful.

[0095] When carbon dioxide is absorbed into the carbon dioxide absorbent (a), the flow rate of the carbon dioxide-containing gas can be selected arbitrarily depending on the purpose. Regardless of whether carbon dioxide is used alone or as a mixed gas, the flow rate is preferably 0.01 to 20 mol / h per 1 mol of compound (1) in the carbon dioxide absorbent (a). For example, the flow rate may be any of 0.01 to 10 mol / h, 0.01 to 5 mol / h, and 0.01 to 1 mol / h, or may be any of 0.1 to 20 mol / h, 1 to 20 mol / h, and 10 to 20 mol / h. When the flow rate is within the above range, the amount of carbon dioxide absorbed is greater. In the absorption method of this embodiment, the use of the carbon dioxide absorbent (a) not only makes it possible to easily absorb carbon dioxide, but also allows the flow rate of the carbon dioxide-containing gas to be set over a wide range as described above, making it highly useful.

[0096] The reaction temperature when carbon dioxide is absorbed into the carbon dioxide absorbent (a) can be appropriately selected depending on the type of carbon dioxide absorbent (a), and is not particularly limited. The temperature is preferably 0°C or higher and lower than 40°C, more preferably 10 to 35°C, even more preferably 20 to 35°C, and particularly preferably room temperature. When the temperature is within the above range, the carbon dioxide absorption efficiency is more likely to be increased. In addition, since there is no need for heating, the amount of energy consumed for carbon dioxide absorption can be reduced.

[0097] The reaction pressure when carbon dioxide is absorbed into the carbon dioxide absorbent (a) can be appropriately selected depending on the type of carbon dioxide absorbent (a), and is not particularly limited. The pressure is preferably 10 to 200 kPa, more preferably 50 to 150 kPa, even more preferably 0.8 to 120 kPa, and particularly preferably atmospheric pressure. When the temperature is within the above range, the carbon dioxide absorption efficiency is more likely to be increased. In addition, since pressurization is not required, the energy consumption for carbon dioxide absorption can be reduced.

[0098] When carbon dioxide is absorbed into the carbon dioxide absorbent (a), vapor of at least one solvent selected from the group consisting of water or alcohols having 1 to 6 carbon atoms may be sprayed onto the absorbent. This facilitates increasing the carbon dioxide absorption efficiency. Examples of the alcohols having 1 to 6 carbon atoms include monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, i-butanol, t-butanol, n-pentanol, t-amyl alcohol, and n-hexanol. The vapor pressure of the at least one solvent selected from the group consisting of water or alcohols having 1 to 6 carbon atoms is preferably 0.01 to 20 kPa, more preferably 0.1 to 15 kPa, and even more preferably 1 to 13 kPa. When the flow rate is within the above range, the carbon dioxide absorption efficiency is more likely to be increased. Although the effect of spraying vapor of the solvent on increasing the carbon dioxide absorption efficiency is not clear, it is believed that the vapor reduces the viscosity of the carbon dioxide absorbent (a), increasing the surface area of ​​the carbon dioxide absorbent (a), thereby increasing the contact efficiency with carbon dioxide, thereby making it easier to increase the carbon dioxide absorption efficiency. Unlike the case where the carbon dioxide absorbent (a) is diluted with a liquid solvent, the carbon dioxide absorbent (a) is not diluted by the steam to such an extent that the carbon dioxide absorption efficiency is reduced, and therefore it is considered that the carbon dioxide absorption efficiency can be more easily increased.

[0099] In step (A), from the viewpoint of energy efficiency, it is preferable not to bubble carbon dioxide in the liquid carbon dioxide absorbent (a). Furthermore, the carbon dioxide absorbent (a) may be stirred by a known method, but from the viewpoint of energy efficiency, it is preferable not to stir it. In step (A), the carbon dioxide absorbent (a) may be placed in an eggplant flask, and carbon dioxide may be introduced into the eggplant flask while rotating the eggplant flask with a rotary evaporator, or the carbon dioxide absorbent (a) may be spread widely on a tray or the like so as to be exposed to carbon dioxide, or the carbon dioxide absorbent may be applied to the inner surface of an exhaust duct or the like so as to be exposed to carbon dioxide.

[0100] In this embodiment, step (A) may be terminated when a portion of compound (1) remains unreacted with carbon dioxide, or step (A) may be terminated after the entire amount of compound (1) has reacted with carbon dioxide. The ratio of the amount (molar number) of compound (1) in the carbon dioxide absorbent (a) at the end of step (A) to the amount (molar number) of compound (1) in the carbon dioxide absorbent (a) at the start of step (A) is preferably 20 mol% or less, and may be, for example, 10 mol% or less, 5 mol% or less, or 1 mol% or less, or may be 0 mol%. When this ratio is equal to or less than the upper limit, the amount of carbon dioxide released in step (B) is further increased.

[0101] In step (A), a solid carbon dioxide release agent (b) is produced from the liquid carbon dioxide absorbent (a), which allows visual confirmation of the progress of the carbon dioxide absorption reaction.

[0102] <<Method for Releasing Carbon Dioxide>> The method for releasing carbon dioxide of the present invention includes a step (B) of releasing carbon dioxide from a carbon oxide releasing agent (b) containing a monocarbamic acid compound having at least one carboxyamino group in the absence of a liquid solvent.

[0103] <Monocarbamic Acid Compound> Examples of the monocarbamic acid compound include compounds represented by the following formula (2).

[0104]

[0105] (In formula (2), m is 0 or 1; R １ and R ２ are each independently an alkyl group, an alkoxy group, a carboxy group, an alkyloxycarbonyl group, a formyl group, an alkylcarbonyl group, an alkylthio group, a sulfo group, an alkyloxysulfonyl group, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have a substituent; each L is independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; m is 1; p １ and p ２ is 1; when m is 0, q １is an integer from 0 to 11, provided that p １ +q １ is 12 or less, and when m is 1, q １ is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11, and q ２ is an integer from 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have a substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have a substituent, the two or more R ２ may be bonded to each other to form a ring.

[0106] The monocarbamic acid compound is preferably, for example, a compound represented by the following formula (2A) or (2B).

[0107]

[0108] (In formula (2A), R １２ are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a carboxy group, an alkyloxycarbonyl group having 2 to 11 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 11 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, a sulfo group, an alkyloxysulfonyl group having 1 to 10 carbon atoms, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; R １２ at least one of the groups is an alkyl group having 1 to 10 carbon atoms and having an amino group as a substituent; and q １２ is an integer from 1 to 11, and q １２is an integer of 2 or more, two or more R １２ may be the same or different, and q １２ is an integer of 2 or more, and two or more R １２ is the alkyl group which may have an amino group as the substituent, the two or more R １２ may be bonded to each other to form a ring.

[0109] (In formula (2B), R １ and R ２ are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a carboxy group, an alkyloxycarbonyl group having 2 to 11 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 11 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, a sulfo group, an alkyloxysulfonyl group having 1 to 10 carbon atoms, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; １ and q ２ are each independently an integer of 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have an amino group as the substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have an amino group as the substituent, the two or more R ２ may be bonded to each other to form a ring.

[0110] These groups include the same groups as those explained in formula (1).

[0111] As the monocarbamic acid compound, for example, a compound represented by the following formula (12A) or (12B) is more preferable.

[0112]

[0113] (In formula (12A), R １２１ are each independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkyloxycarbonyl group having 2 to 6 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; q １２１ are each independently an integer of 0 to 10, and q １２１ is an integer of 2 or more, two or more R １２１ may be the same or different, and q １２１ is an integer of 2 or more, and two or more R １２１ is the alkyl group which may have an amino group as the substituent, the two or more R １２１ may be bonded to each other to form a ring; R １２２ is an alkylene group having 1 to 5 carbon atoms.

[0114] (In formula (12B), R １３１ and R ２１１ are each independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkyloxycarbonyl group having 2 to 6 carbon atoms, a formyl group, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have an amino group as the substituent; q １３１ and q ２１１ are each independently an integer of 0 to 10, and q １３１ is an integer of 2 or more, two or more R １３１ may be the same or different, and q ２１１ is an integer of 2 or more, two or more R ２１１ may be the same or different, and q １３１ is an integer of 2 or more, and two or more R１３１ is the alkyl group which may have an amino group as the substituent, the two or more R １３１ may be bonded to each other to form a ring, and q ２１１ is an integer of 2 or more, and two or more R ２１１ is the alkyl group which may have an amino group as the substituent, the two or more R ２１１ may be bonded to each other to form a ring.

[0115] These groups include the same groups as those explained in formula (1).

[0116] As the monocarbamic acid compound, for example, a compound represented by the following formula (112A) or (112B) is more preferable.

[0117]

[0118] As the monocarbamic acid compound, for example, compounds represented by the following formulae (7A) to (10A) are also preferred.

[0119]

[0120] In the present invention, from 1 mol of the monocarbamic acid compound, preferably 0.5 to 1 mol, more preferably 0.6 to 1 mol, and even more preferably 0.7 to 1 mol of carbon dioxide is released.

[0121] <Step (B)> In the step (B), carbon dioxide is released from the carbon dioxide releasing agent (b) in the absence of a liquid solvent. In the step (B), for example, when the carbon dioxide releasing agent (b) containing the compound (2) is used, carbon dioxide is released from the carboxyamino group of the compound (2) in the carbon dioxide releasing agent (b) and converted into the amine compound (1), thereby releasing carbon dioxide.

[0122] The reaction temperature when carbon dioxide is released from the carbon dioxide release agent (b) can be appropriately selected depending on the type of carbon dioxide release agent (b) and is not particularly limited. The temperature is preferably 40 to 100°C, more preferably 50 to 90°C, and even more preferably 60 to 80°C. When the temperature is within the above range, the carbon dioxide release efficiency is more likely to be increased. In addition, since the heating temperature is not too high, the amount of energy consumed for carbon dioxide release can be reduced.

[0123] The reaction pressure when releasing carbon dioxide from the carbon dioxide release agent (b) can be appropriately selected depending on the type of carbon dioxide release agent (b) and is not particularly limited. The pressure is preferably 1 to 120 kPa, more preferably 5 to 102 kPa, even more preferably 10 to 102 kPa, and particularly preferably atmospheric pressure (101.33 kPa). When the temperature is within the above range, the carbon dioxide release efficiency is more likely to be improved. In addition, since pressurization or depressurization is not necessarily required, the amount of energy consumed for carbon dioxide release can be reduced.

[0124] In step (B), the carbon dioxide release agent (b) may be exposed to reduced pressure conditions, the carbon dioxide release agent (b) may be heated, or a desorption gas containing an inert gas may be sprayed onto the carbon dioxide release agent (b). This facilitates further improvement of the carbon dioxide release efficiency. The reduced pressure conditions may be atmospheric pressure or less, and are, for example, preferably 1 to 101.33 kPa, more preferably 5 to 101.33 kPa, and even more preferably 7 to 101.33 kPa. The reaction time under reduced pressure conditions is preferably 20 to 60 minutes, more preferably 10 to 30 minutes, and even more preferably 5 to 15 minutes. The heating temperature is preferably 40 to 100°C, more preferably 50 to 90°C, and even more preferably 60 to 80°C. When the temperature is within the above range, the carbon dioxide release efficiency is more easily improved. The heating conditions are not particularly limited, and may be reduced pressure conditions, pressurized conditions, or an inert gas stream. The reduced pressure conditions can be the same as those described above. The pressurization conditions may be any pressure above atmospheric pressure, and for example, preferably above 101.33 kPa, more preferably from 101.33 to 200 kPa, and even more preferably from 101.33 to 150 kPa. Examples of the inert gas include those mentioned above as inert gases. Examples of the desorption gas containing an inert gas include nitrogen gas and air. The flow rate of the desorption gas containing an inert gas is preferably from 1 to 270 mol / h, more preferably from 20 to 200 mol / h, and even more preferably from 80 to 160 mol / h, per mol of compound (2) in the carbon dioxide release agent (b). When the flow rate is within the above range, the carbon dioxide release efficiency is more likely to be increased.

[0125] In the step (B), a liquid carbon dioxide absorbent (a) is produced from the solid carbon dioxide releasing agent (b), which allows visual confirmation that the carbon dioxide releasing reaction has progressed.

[0126] As explained above, by carrying out step (B), compound (2) as the monocarbamic acid compound releases carbon dioxide and returns to compound (1) as the diamine compound. This regenerated compound (1) can be used again to absorb and release carbon dioxide. Therefore, in the carbon dioxide absorption and release method of the present invention, the diamine compound and the monocarbamic acid compound used in steps (A) and (B) can be reused two or more times. The same applies to amine compounds other than compound (1).

[0127] <<Method for Producing Carbon Dioxide Absorbent (a)>> The carbon dioxide absorbent (a) of the present invention can be produced, for example, by mixing the diamine compound and, if necessary, other components.

[0128] The diamine compound may be a commercially available product or may be synthesized from a commercially available product. For example, the diamine compound represented by formula (1) may be synthesized by hydrogenating an aromatic diamine compound represented by the following formula (1-1):

[0129]

[0130] The carbon dioxide absorbent (a) of the present invention can also be produced by releasing carbon dioxide from the carbon dioxide release agent (b) by the carbon dioxide releasing method of the present invention.

[0131] <<Method for producing carbon dioxide releasing agent (b)>> The carbon dioxide releasing agent (b) of the present invention can be produced by mixing the monocarbamic acid compound with other components as necessary. In addition, the carbon dioxide releasing agent (b) of the present invention can also be produced by absorbing carbon dioxide into the carbon dioxide absorbent (a) by a carbon dioxide absorption method.

[0132] <<Method of Using Carbon Dioxide Absorbent (a)>> In the present invention, a composition containing an amine compound having at least one amino group and being a liquid at room temperature can be used as the carbon dioxide absorbent (a) in the carbon dioxide absorption method of the present invention. In the present invention, a composition containing an amine compound having at least one amino group and being a liquid at room temperature can be used to produce the carbon dioxide absorbent (a) used in the carbon dioxide absorption method of the present invention. From the viewpoint of enhancing carbon dioxide absorption capacity, a composition containing an amine compound having at least one amino group and being a liquid at room temperature is preferably a liquid. For example, a composition containing an amine compound having at least one amino group and being a liquid at room temperature can be spread on a tray or the like, and allowed to stand with a large area exposed to air, thereby reacting with carbon dioxide, thereby absorbing carbon dioxide. Instead of spreading on a tray or the like, the composition may be sprayed onto the surface of an object that comes into contact with air, for example, by spraying. When removing high concentrations of carbon dioxide contained in factory exhaust gases, for example, the composition can be applied to the inside of an exhaust duct, and allowed to stand with a large area exposed to exhaust gases, thereby reacting with carbon dioxide, thereby absorbing carbon dioxide.

[0133] <<Method of Using Carbon Dioxide Releasing Agent (b)>> In the present invention, a composition containing a monocarbamic acid compound having at least one carboxyamino group can be used as the carbon dioxide releasing agent (b) in the method for releasing carbon dioxide of the present invention. In the present invention, a composition containing a monocarbamic acid compound having at least one carboxyamino group can be used for producing the carbon dioxide releasing agent (b) used in the method for releasing carbon dioxide of the present invention.

[0134] From the viewpoint of improving handleability and carbon dioxide release capacity, a composition containing a monocarbamic acid compound having at least one carboxyamino group is preferably solid. The composition may or may not contain a trace amount of liquid solvent, but may contain it from the viewpoint of increasing the surface area of ​​the carbon dioxide release agent (b). The amount of liquid solvent added to the carbon dioxide release agent (b) is preferably 0.5 to 10 mL, more preferably 0.7 to 8 mL, and even more preferably 0.8 to 6 mL per 100 mmol of carbon dioxide release agent (b). When the amount of liquid solvent is within the above range, aggregation of particles of the carbon dioxide release agent (b) is easily prevented, and the surface area of ​​the carbon dioxide release agent (b) is likely to increase when carbon dioxide is released, thereby improving carbon dioxide release efficiency. The composition may or may not contain other substances such as a solvent. However, from the viewpoint of reducing energy consumption for heating, it is preferable that the composition is composed only of a monocarbamic acid compound and does not contain other substances such as a solvent. If other substances such as a solvent are contained, it is preferably in a trace amount, like the liquid solvent described above.

[0135] <<Carbon Dioxide Absorbing Apparatus>> Fig. 1 is a schematic diagram showing a carbon dioxide absorbing apparatus according to one embodiment of the present invention. As shown in Fig. 1, the carbon dioxide absorbing apparatus 1 of this embodiment includes a reaction vessel 10, a heating unit 20, a first gas flow path 30, and a first on-off valve 40.

[0136] The reaction vessel 10 is a vessel that contains a carbon dioxide absorbent (a) 100 .

[0137] The reaction vessel 10 is not particularly limited as long as it is not deteriorated by the carbon dioxide absorbent (a) 100, and examples thereof include a glass test tube, a glass flask, and the like.

[0138] The heating unit 20 is disposed on the bottom side of the reaction vessel 10 so as to surround the outer peripheral surface (outer surface) and bottom surface of the reaction vessel 10. The heating unit 20 heats the reaction vessel 10 from the outside, thereby heating the carbon dioxide absorbent (a) 100 accommodated in the reaction vessel 10 and the gas flowing into the reaction vessel 10 to a temperature suitable for the reaction. The heating unit 20 is not particularly limited as long as it can heat the carbon dioxide absorbent (a) 100 and the gas in the reaction vessel 10 to a predetermined temperature, and examples thereof include an electric heater, a hot water bath, and the like. The heating unit 20 does not necessarily have to be provided.

[0139] The first gas flow path 30 is connected to the reaction vessel 10 and is used to introduce gas into the reaction vessel 10. An end 30A of the first gas flow path 30 that is not disposed inside the reaction vessel 10 is connected to a gas tank filled with gas, an air pump for introducing air, or the like. An end 30B of the first gas flow path 30 that is disposed inside the reaction vessel 10 is disposed near the surface of the carbon dioxide absorbent (a) 100 contained in the reaction vessel 10. Here, the end 30B does not require bubbling and is therefore not disposed inside the carbon dioxide absorbent (a) 100.

[0140] The first on-off valve 40 is provided in the first gas flow path 30 and serves to adjust the flow rate of the gas flowing into the reaction vessel 10 through the first gas flow path 30. The first on-off valve 40 is not particularly limited, and examples thereof include an electromagnetic valve.

[0141] The carbon dioxide absorbing apparatus 1 of the present embodiment may include a flow meter 70. The flow meter 70 is provided in the first gas flow path 30 and is used to measure the flow rate of the gas passing through the first gas flow path 30 and flowing into the reaction vessel 10.

[0142] The carbon dioxide absorbing device 1 of this embodiment may be provided with an exhaust gas flow path (not shown) that allows excess gas to flow out of the reaction vessel 10 .

[0143] A method of using the carbon dioxide absorbing device 1 of this embodiment will be described.

[0144] (Absorption of Carbon Dioxide: Step (A)) The first on-off valve 40 is opened to allow carbon dioxide to flow into the reaction vessel 10, and the carbon dioxide is absorbed by the carbon dioxide absorbent (a) 100 in the reaction vessel 10. After the absorption of carbon dioxide by the carbon dioxide absorbent (a) 100 is completed, the first on-off valve 40 is closed.

[0145] In the step (A), the carbon dioxide absorbent (a) 100 and the gas containing carbon dioxide may or may not be heated by the heating unit 20 .

[0146] <<Carbon Dioxide Release Apparatus>> Fig. 2 is a schematic diagram showing a carbon dioxide release apparatus according to one embodiment of the present invention. As shown in Fig. 2, the carbon dioxide release apparatus 2 of this embodiment includes a reaction vessel 12, a heating unit 22, a second gas flow path 52, and a second on-off valve 62.

[0147] The reaction vessel 12 is a vessel that contains the carbon dioxide releasing agent (b) 200 .

[0148] The reaction vessel 12 is not particularly limited as long as it is not deteriorated by the carbon dioxide releasing agent (b) 200, and examples thereof include a glass test tube, a glass flask, and the like.

[0149] The heating unit 22 is disposed on the bottom side of the reaction vessel 12 so as to surround the outer peripheral surface (outer surface) and bottom surface of the reaction vessel 12. The heating unit 22 heats the reaction vessel 12 from the outside, thereby heating the carbon dioxide release agent (b) 200 contained in the reaction vessel 12 and the gas flowing into the reaction vessel 12 to a temperature suitable for the reaction. The heating unit 22 is not particularly limited as long as it can heat the carbon dioxide release agent (b) 200 and the gas in the reaction vessel 12 to a predetermined temperature, and examples thereof include an electric heater, a hot water bath, etc.

[0150] The second gas flow path 52 is connected to the reaction vessel 12 and is used to release gas from inside the reaction vessel 12. An end 52A of the second gas flow path 52 that is not disposed inside the reaction vessel 12 is connected to a gas tank that collects carbon dioxide. An end 52B of the second gas flow path 52 that is disposed inside the reaction vessel 12 is disposed at a position separated from the carbon dioxide release agent (b) 200 contained in the reaction vessel 12.

[0151] The second gas flow path 52 may be connected to a pump (not shown) for creating a reduced pressure condition inside the reaction vessel 12. Examples of the pump include an aspirator, a diaphragm pump, and a vacuum pump.

[0152] The second on-off valve 62 is provided in the second gas flow path 52 and serves to adjust the flow rate of the gas that passes through the second gas flow path 52 and is released from the reaction vessel 12. The second on-off valve 62 is not particularly limited, and examples thereof include an electromagnetic valve.

[0153] The carbon dioxide release device 2 of this embodiment may include a flow meter 72. The flow meter 72 is provided in the second gas flow path 52 and is used to measure the flow rate of the gas that passes through the second gas flow path 52 and flows out of the reaction vessel 12.

[0154] As shown in FIG. 3, the carbon dioxide release device 3 of the present invention may include a first on-off valve 42 for allowing a gas containing an inert gas to flow into the reaction vessel 12 .

[0155] The first gas flow path 32 is connected to the reaction vessel 12 and is used to introduce gas into the reaction vessel 12. An end 32A of the first gas flow path 32 that is not disposed inside the reaction vessel 12 is connected to a gas tank filled with gas, an air pump for introducing air, or the like. An end 32B of the first gas flow path 32 that is disposed inside the reaction vessel 12 is disposed near the surface of the carbon dioxide release agent (b) 200 contained in the reaction vessel 12. Here, the end 32B does not require bubbling and is therefore not disposed inside the carbon dioxide release agent (b) 200.

[0156] The first on-off valve 42 is provided in the first gas flow path 32 and serves to adjust the flow rate of the gas flowing into the reaction vessel 12 through the first gas flow path 32. The first on-off valve 42 is not particularly limited, and examples thereof include an electromagnetic valve.

[0157] The carbon dioxide release device 3 of this embodiment may include a flow meter 72. The flow meter 72 is provided in the first gas flow path 32 and is used to measure the flow rate of the gas flowing into the reaction vessel 12 through the first gas flow path 32.

[0158] In the carbon dioxide release device 3 of this embodiment, excess gas may be released from the reaction vessel 12 together with the released carbon dioxide through the second gas flow path 52. The other components in Figure 3 can be the same as those in Figure 2 with the same reference numerals.

[0159] The carbon dioxide release device 3 of this embodiment can also be used as a carbon dioxide absorption device by changing the carbon dioxide release agent (b) to a carbon dioxide absorbent (a) and changing the gas containing an inert gas flowing into the reaction vessel to a gas containing carbon dioxide.

[0160] A method of using the carbon dioxide release device 3 of this embodiment will be described with reference to FIG.

[0161] (Release of Carbon Dioxide: Step (B)) In step (B), the first on-off valve 42 and the second on-off valve 62 are opened to allow nitrogen to flow into the reaction vessel 12. After the release of carbon dioxide by the carbon dioxide release agent (b) 200 is completed, the first on-off valve 42 is closed.

[0162] It is not necessary to use the first on-off valve 42 and the flow meter 72 to control the flow rate of nitrogen flowing into the reaction vessel 12, but by controlling the flow rate of nitrogen, the concentration of carbon dioxide released from the compound (2) can be controlled.

[0163] In the step (B), it is preferable to heat the gas containing the carbon dioxide releasing agent (b) 200 and the inert gas by the heating unit 22 .

[0164] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the examples shown below.

[0165] Example 1A: Absorption of Carbon Dioxide. Isophoronediamine (0.183 mL) was placed in a 100 mL recovery flask, and the recovery flask was attached to a rotary evaporator. A first gas flow path consisting of a Teflon tube was connected to a capillary at the top end of the rotary evaporator's condenser. A gas containing 400 ppm of carbon dioxide was introduced into the recovery flask from the outside, and the receiver flask of the rotary evaporator was removed. A carbon dioxide absorption device was assembled so that the lower end of the Teflon tube reached near the surface of the isophoronediamine in the recovery flask. Next, using the device at room temperature, 0.04% carbon dioxide (diluted with nitrogen) was introduced into the recovery flask at a flow rate of 50 mL / min while rotating the recovery flask, spraying the gas onto the isophoronediamine (step (A)). The excess gas was then discharged to the outside through the open connection port of the receiver flask. The exhaust gas was then analyzed by infrared absorption spectroscopy to quantify the carbon dioxide in the exhaust gas. The amount of carbon dioxide absorbed by the carbon dioxide absorbent (a) made of isophoronediamine was calculated from the inflow and outflow amounts of carbon dioxide, and the carbon dioxide absorption efficiency was calculated using the following formula. The results are shown in Figure 4. [Carbon dioxide absorption efficiency (%)] = [Amount of carbon dioxide absorbed] / [Amount of carbon dioxide inflow] x 100

[0166] 200-500 minutes after the start of carbon dioxide inflow, carbon dioxide absorbent (a) composed of isophoronediamine became cloudy due to the absorption of carbon dioxide. As is clear from Figure 4, immediately after the start of carbon dioxide inflow, the carbon dioxide absorption efficiency was close to 100%, and the carbon dioxide absorbent (a) absorbed carbon dioxide with high efficiency. Then, over time, the amount of isophoronediamine capable of reacting with carbon dioxide decreased, and the carbon dioxide removal efficiency decreased, until approximately 2,000 minutes after the start of carbon dioxide inflow, carbon dioxide was no longer removed. It was confirmed that isophoronediamine absorbed 0.55 mmol of carbon dioxide. Because electrical energy was only used to rotate the rotary evaporator, an improvement over the prior art was observed in terms of energy efficiency.

[0167] Example 2A Carbon Dioxide Absorption A carbon dioxide absorption reaction was carried out in the same manner as in Example 1A, except that in addition to the gas, water vapor was flowed into the recovery flask and sprayed onto the isophoronediamine, and the carbon dioxide absorption efficiency was calculated. However, in Figure 5, before introducing 0.04% carbon dioxide gas (diluted with nitrogen) into the carbon dioxide absorbent, carbon dioxide gas was bubbled in water to introduce carbon dioxide gas with a humidity of 90% or more into the recovery flask. Figure 5 shows the results of carbon dioxide absorption using 0.04% carbon dioxide gas containing water vapor. Figure 6 shows photographs showing the state inside the flask before and after the carbon dioxide absorption reaction.

[0168] 100-300 minutes after the start of the inflow of 0.04% carbon dioxide containing water vapor, the carbon dioxide absorbent (a) composed of isophoronediamine became cloudy due to the absorption of carbon dioxide. As shown in Figure 6, the liquid in the flask before the carbon dioxide absorption reaction was transparent, but a white solid precipitated in the flask after the carbon dioxide absorption reaction, indicating that the progress of the carbon dioxide absorption reaction could be visually confirmed. As is clear from Figure 5, immediately after the start of the carbon dioxide inflow, the carbon dioxide absorption efficiency maintained 80-100%, and the carbon dioxide absorbent (a) absorbed carbon dioxide with high efficiency. Then, approximately 1000 minutes after the start, the amount of isophoronediamine capable of reacting with carbon dioxide suddenly decreased, the carbon dioxide removal efficiency decreased, and approximately 1400 minutes after the start of the carbon dioxide inflow, carbon dioxide was no longer removed. It was confirmed that isophoronediamine absorbed 1.00 mmol of carbon dioxide. In other words, it was found that when water vapor was contained in the gas, isophoronediamine and carbon dioxide reacted at a molar ratio of 1:1. Since electrical energy was only used to rotate the rotary evaporator, this was an improvement over the prior art in terms of energy efficiency. Furthermore, since a higher carbon dioxide absorption amount was achieved in a shorter time than in Example 1A, it was found that spraying water vapor improves both the carbon dioxide absorption efficiency and the absorption amount.

[0169] Example 3A Carbon Dioxide Absorption The 0.04% carbon dioxide gas (diluted with nitrogen) of Example 1A was bubbled into a methanol solution, methanol vapor was added to the 0.04% carbon dioxide gas, and the mixture was sprayed onto the isophoronediamine in the recovery flask to carry out a carbon dioxide absorption reaction in the same manner as in Example 1A, and the carbon dioxide absorption efficiency was calculated. The results of the carbon dioxide absorption efficiency are shown in Figure 7.

[0170] 1,300 minutes after the start of the carbon dioxide inflow, the carbon dioxide absorbent (a) composed of isophoronediamine became cloudy due to the absorption of carbon dioxide. As is clear from Figure 7, immediately after the start of the inflow of 0.04% carbon dioxide containing methanol vapor, the carbon dioxide absorption efficiency remained at approximately 100%, and the carbon dioxide absorbent (a) absorbed carbon dioxide with high efficiency. Then, 800 minutes after the start, the amount of isophoronediamine capable of reacting with carbon dioxide suddenly decreased, and the carbon dioxide removal efficiency decreased. Approximately 1,300 minutes after the start of the carbon dioxide inflow, carbon dioxide removal ceased. It was confirmed that isophoronediamine absorbed 1.09 mmol of carbon dioxide. In other words, it was determined that isophoronediamine and carbon dioxide reacted at a molar ratio of 1:1.09. This is presumably due to the reaction of two amino groups with carbon dioxide in some of the isophoronediamine. Since electrical energy was only used to rotate the rotary evaporator, this represents an improvement over the prior art in terms of energy efficiency. Furthermore, because a higher carbon dioxide absorption capacity was achieved in a shorter time than in Examples 1A and 2A, it was found that spraying methanol vapor improved both the carbon dioxide absorption efficiency and the absorption capacity. However, while the obtained reaction product may be used as a carbon dioxide release agent (b), it is presumed that the by-product in which two amino groups react with carbon dioxide requires a large amount of energy to release two molecules of carbon dioxide. Therefore, from the viewpoint of energy efficiency, it is preferable to use the by-product in the carbon dioxide release method of the present invention with an energy consumption that does not release two molecules of carbon dioxide. Even when the reaction product is used, the energy efficiency is improved compared to conventional technology, and it was found to be within a fully practical range.

[0171] [Example 4A] <<Absorption of Carbon Dioxide>> The carbon dioxide absorption reaction was carried out in the same manner as in Example 3A, except that the flow rate of the 0.04% carbon dioxide gas (diluted with nitrogen) containing methanol vapor was changed from 50 mL / min to 75 mL / min, 100 mL / min, 200 mL / min, and 250 mL / min, respectively, and the carbon dioxide absorption efficiency was calculated. The results are shown in Figure 8 together with the results of Example 3A (flow rate: 50 mL / min).

[0172] After a specific time had elapsed since the start of carbon dioxide inflow, the carbon dioxide absorbent (a) composed of isophorone diamine became cloudy due to the absorption of carbon dioxide. As is clear from Figure 8, it was found that the carbon dioxide absorption efficiency decreased with increasing flow rate during the period from immediately after the start of carbon dioxide inflow to 500 minutes. Furthermore, at all flow rates, carbon dioxide was no longer removed approximately 1,300 minutes after the start of carbon dioxide inflow. This is thought to be due to the fact that increasing the flow rate reduces the contact efficiency between carbon dioxide and isophorone diamine, thereby reducing the carbon dioxide removal efficiency. It was confirmed that isophorone diamine absorbed 1.2 mmol, 1.1 mmol, 1.1 mmol, and 1.5 mmol of carbon dioxide at gas flow rates of 75 mL / min, 100 mL / min, 200 mL / min, and 250 mL / min, respectively. At 50 mL / min, 1.09 mmol was absorbed, similar to Example 3A. Since electrical energy was used only to rotate the rotary evaporator, this was an improvement over the prior art in terms of energy efficiency. Furthermore, at a gas flow rate of 75 mL / min, a higher carbon dioxide absorption amount was achieved in a shorter time than in Example 3A (flow rate: 50 mL / min), demonstrating that optimizing the flow rates of the gas and methanol vapor can further improve both the carbon dioxide absorption efficiency and the absorption amount.

[0173] Example 1B Release of Carbon Dioxide The monocarbamic acid compound of isophoronediamine was subjected to TG-DTA measurement and DSC measurement. The results are shown in FIG. 9. The TG-DTA measurement was performed using a thermogravimetric analyzer (product name: TG-DTA2000SA, manufacturer: Bruker) under a nitrogen atmosphere at a heating rate of 10°C / min. The DSC measurement was performed using a differential scanning calorimeter (product name: DSC3200SA, manufacturer: Bruker) under a nitrogen atmosphere at a heating rate of 10°C / min. As shown in FIG. 9, the monocarbamic acid compound of isophoronediamine required 155 kJ / mol of thermal energy to release carbon dioxide from 80 mol% of the carboxyamino groups relative to the total number of moles of carboxyamino groups in the compound, and the energy required for isophoronediamine to absorb carbon dioxide was 4.0 GJ / tCO ２ It was also found that the vapor pressure of isophoronediamine produced after the release of carbon dioxide is 2 Pa, the boiling point is 247°C, and the melting point is 10°C, so even if the mixture is overheated, the isophoronediamine produced is unlikely to volatilize and can be recovered as a liquid.

[0174] Example 2B Release of Carbon Dioxide TG-DTA and DSC measurements were carried out in the same manner as in Example 1B, except that the monocarbamic acid compound of isophoronediamine was changed to the monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane. The results are shown in Figure 10. As shown in Figure 10, the thermal energy required for the release of carbon dioxide from 80 mol% of the carboxyamino groups in the monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, relative to the total number of moles of carboxyamino groups in the compound, was 108 J / mol, and the energy required for 4,4'-diamino-3,3'-dimethyldicyclohexylmethane to absorb carbon dioxide was 2.5 GJ / tCO ２Furthermore, the vapor pressure of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane produced after the release of carbon dioxide was 0.08 Pa, the boiling point was 342°C, the melting point was -7°C, and the viscosity was high, so it remained in the flask without volatilizing even when heated, and the recovery rate of the diamine compound was also high.

[0175] [Example 3B] 0.28 g (1 mmol) of a monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane was heated to 80°C under reduced pressure of 7 kPa to obtain a CO ２ After desorption, N ２ CO gas (50 mL / min) was diluted to ２ The amount of carbon dioxide released was analyzed by infrared absorption spectroscopy (VAISALA, GMP251 and GMP252) to quantify the amount of carbon dioxide released. ２ The concentration was 90 mol% or more. The results are shown in Table 1 and Figure 11. In addition, desorption at 100°C finally returned to an almost transparent liquid. ２ When CO is desorbed, and when CO is desorbed at 100°C, ２ The appearance of the film after desorption is shown in FIG.

[0176]

[0177] As shown in Table 1 and Figures 11 and 12, by heating the monocarbamic acid compound under reduced pressure, CO ２ was found to be detached.

[0178] [Example 4B] 0.28 g (1 mmol) of a monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane was placed in a glass container and heated at various temperatures in a closed system. ２ The amount of CO released was evaluated. The results are shown in Figure 13. ２ When CO was desorbed, and when heated at 100°C, ２ The appearances of the product when the monocarbamic acid compound is desorbed and the product when the monocarbamic acid compound is desorbed are shown in Fig. 14. In Fig. 13, the blank indicates the increase in volume when heated in the absence of the monocarbamic acid compound.

[0179] As shown in FIG. 13, by heating a monocarbamic acid compound under pressure in a sealed tube, CO ２ As shown in Figure 14, the appearance was white powder and it did not return to a transparent liquid, but it was found that carbon dioxide was sufficiently released.

[0180] [Example 5B] 1 mmol of a monocarbamic acid compound of isophoronediamine was placed in a glass container and heated with N ２ Carbon dioxide was desorbed by heating at 90° C. under an air stream. The results are shown in Table 2 and FIG.

[0181]

[0182] As shown in Table 2 and Figure 15, by heating the monocarbamic acid compound under an inert gas flow, CO ２ It was found that a maximum of 1.35 mol% of CO was released. ２ It can be concentrated to a concentration of 0.6 mmol CO ２ has detached.

[0183] Comparative Example 1A: Absorption of Carbon Dioxide. An aqueous diamine solution was prepared by adding 2 mL of water to 1 mmol of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane. Nitrogen gas containing 400 ppm of carbon dioxide and water vapor were supplied at a flow rate of 50 mL / min, and the diamine solution was bubbled while the rotary evaporator was rotated at a rotation speed of 150 rpm at room temperature. Carbon dioxide absorption was performed in the same manner as in Example 1A. The results are shown in Figure 16. As shown in Figure 16, when bubbling was performed using a liquid solvent, the carbon dioxide absorption efficiency decreased over reaction time. The total amount of carbon dioxide absorbed was 1.1 mmol, and there was almost no unreacted diamine compound, indicating that a carbamic acid compound had been produced in which one amino group had reacted with carbon dioxide. Using too much liquid solvent required heating a large amount of solvent during carbon dioxide desorption, which was undesirable from the perspective of energy efficiency.

[0184] [Example 5A] <<Absorption of Carbon Dioxide>> Carbon dioxide was absorbed in the same manner as in Comparative Example 1A, except that 1 mmol of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane was used as is, 2 mL of water was not added, and bubbling was not performed. The results are shown in Figure 17. As shown in Figure 17, the carbon dioxide absorption efficiency leveled off before the reaction time reached 1,000 minutes, indicating that the carbon dioxide absorption efficiency was high. The total amount of carbon dioxide absorbed was 0.6 mmol.

[0185] Example 6A <<Release of Carbon Dioxide>> 6 mmol of a monocarbamic acid compound of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane was weighed into a test tube and heated in the absence of a liquid solvent at 60°C for 20 minutes, at 80°C for 30 minutes, and at 100°C for 30 minutes, and the amount of carbon dioxide released was measured. The results are shown in Figure 18. As shown in Figure 18, the amount of carbon dioxide released when heated at 60°C for 20 minutes was 0.21 mmol. The amount of carbon dioxide released when heated at 80°C for 30 minutes was 2.30 mmol. Since the compound in the flask after heating at 80°C for 30 minutes was a white powder, it was visually confirmed that not all of the carbon dioxide had been released from the compound. The amount of carbon dioxide released when heated at 100°C for 30 minutes was 1.57 mmol. After heating at 100°C for 30 minutes, the compound in the flask was a transparent liquid, and it was therefore possible to visually confirm that almost all of the carbon dioxide had been released from the compound and that 4,4'-diamino-3,3'-dimethyldicyclohexylmethane had been produced.

[0186] Example 7 Figure 19 shows a carbon dioxide absorption apparatus for measuring the carbon dioxide absorption capacity of a carbon dioxide absorbent (a). In Figure 19, the carbon dioxide absorption apparatus 1 is configured to include a carbon dioxide concentration detection device A, a rotation device B utilizing part of an evaporator, a carbon dioxide absorbent (a) 100 contained in a flask serving as a reaction vessel 10, a gas flow controller C, and a solvent S converted into saturated solvent vapor G so that the saturated solvent vapor G can be supplied to the reaction vessel 10 together with carbon dioxide. Figure 20 is a graph showing the carbon dioxide absorption efficiency when the rotation speed of the rotation device is changed. Except for changing the rotation speed of the rotation device to 100 rpm, 200 rpm, and 300 rpm, the carbon dioxide absorption capacity was measured under the following conditions: 1.0 mmol of isophoronediamine, a carbon dioxide concentration of 400 ppm, a carbon dioxide flow rate of 50 mL / min, room temperature, no solvent, and a flask volume of 30 mL. As shown in FIG. 20, it was found that a higher rotation speed increases the surface area of ​​the carbon dioxide absorbent (a), resulting in a higher carbon dioxide absorption capacity.

[0187] [Example 8] Figure 21 is a graph showing the carbon dioxide absorption efficiency when the volume of the flask installed in the rotating device was changed. Except for changing the volume of the flask to 30 mL, 50 mL, and 100 mL, the carbon dioxide absorption capacity was measured under solvent-free conditions with 1.0 mmol of isophoronediamine, a carbon dioxide concentration of 400 ppm, a carbon dioxide flow rate of 75 mL / min, a rotation speed of the rotating device of 150 rpm, and room temperature. As shown in Figure 21, it was found that a larger volume of the flask could increase the surface area of ​​the carbon dioxide absorbent (a), and therefore, higher carbon dioxide absorption capacity.

[0188] [Example 9] Figure 22 is a graph showing the carbon dioxide absorption efficiency when the combination of water vapor and a trace amount of solvent supplied together with carbon dioxide is changed. The combination of water vapor and solvent supplied was changed to water vapor only, water vapor and 1 mL of solvent (water) added to the flask, and no water vapor, respectively. The carbon dioxide absorption capacity was measured under the following conditions: 1.0 mmol of isophoronediamine, a carbon dioxide concentration of 400 ppm, a carbon dioxide flow rate of 50 mL / min, a rotation speed of the rotating device of 150 rpm, room temperature, and a flask volume of 100 mL. As shown in Figure 22, it was found that the carbon dioxide absorption capacity was higher when water vapor was supplied. It was also found that the carbon dioxide absorption capacity was higher when water vapor was combined with a trace amount of solvent.

[0189] [Example 10] Figure 23 is a graph showing the carbon dioxide absorption efficiency when the type of vapor supplied together with carbon dioxide is changed. Except for changing the vapor supplied to water vapor, a mixed vapor of water vapor and solvent (methanol) vapor, methanol vapor, ethanol vapor, no vapor, and DMF vapor, the carbon dioxide absorption capacity was measured under the following conditions: isophoronediamine 1.0 mmol, carbon dioxide concentration 400 ppm, carbon dioxide flow rate 50 mL / min, rotation speed of the rotating device 150 rpm, temperature room temperature, and flask volume 100 mL. As shown in Figure 23, it was found that the carbon dioxide absorption capacity was higher when water vapor or alcohol vapor was supplied.

[0190] [Example 11] Figure 24 is a graph showing the carbon dioxide absorption efficiency when the carbon dioxide flow rate is changed. Except for changing the flow rate of carbon dioxide supplied to 50 mL / min, 75 mL / min, 100 mL / min, 200 mL / min, and 250 mL / min, the carbon dioxide absorption capacity was measured under the following conditions: isophoronediamine 1.0 mmol, carbon dioxide concentration 400 ppm, rotation speed of the rotating device 150 rpm, temperature room temperature, flask volume 100 mL, and methanol vapor supply. As shown in Figure 24, it was found that increasing the carbon dioxide flow rate resulted in higher carbon dioxide absorption capacity. It was also found that the absorption efficiency decreased when methanol vapor was allowed to flow too much.

[0191] Example 12 Figure 25 is a graph showing the carbon dioxide absorption efficiency when the amine compound contained in the carbon dioxide absorbent (a) was changed. The amine compounds used are shown below. The carbon dioxide absorption capacity was measured under the following conditions: 1 mmol of each amine compound (except for Entry 5, which contains 2 mmol of amine compound 4), a carbon dioxide flow rate of 50 mL / min, a carbon dioxide concentration of 400 ppm, a rotation speed of the rotating device of 150 rpm, room temperature, a flask volume of 100 mL, and methanol vapor. The results are shown in Table 3 and Figure 25. As shown in Table 3 and Figure 25, it was found that the carbon dioxide absorption capacity was higher when a diamine compound was used or when the equivalent amount of a monoamine compound was increased.

[0192]

[0193]

[0194] [Example 13] Figures 26(a) and 26(b) are diagrams showing the carbon dioxide release efficiency of each monocarbamic acid compound obtained after carbon dioxide was absorbed into the carbon dioxide absorbent (a) in Example 12. Each monocarbamic acid compound was used in an amount of 1 mmol (except for Entry 5, which was 2 mmol), and the nitrogen flow rate was 25 mL / min. 6 mL of methanol was added, and the carbon dioxide release capacity was measured under conditions of 60°C. The results are shown in Table 4 and Figure 26. As shown in Table 4 and Figure 26, it was found that all of the amine compounds were able to release almost all of the absorbed carbon dioxide.

[0195]

[0196] Example 14 Figure 27 shows the carbon dioxide absorption efficiency and absorption amount when 4,4'-methylenebis(2-methylcyclohexylamine) is used as the diamine compound and the type of steam is changed. The carbon dioxide absorption capacity was measured under the following conditions: 1.0 mmol of 4,4'-methylenebis(2-methylcyclohexylamine), a carbon dioxide concentration of 400 ppm, a carbon dioxide flow rate of 50 mL / min, a rotation speed of the rotating device of 150 rpm, room temperature, and a flask volume of 100 mL. As shown in Figure 27, adding a small amount of water to the flask in addition to water vapor resulted in higher carbon dioxide absorption capacity.

[0197] Example 15: Figure 28 shows the carbon dioxide absorption efficiency when 4,4'-methylenebis(2-methylcyclohexylamine) was used as the diamine compound and the amount of water added to the flask was varied. The carbon dioxide absorption capacity was measured under the following conditions: 1.0 mmol of 4,4'-methylenebis(2-methylcyclohexylamine), a carbon dioxide concentration of 400 ppm, a carbon dioxide flow rate of 50 mL / min, a rotation speed of the rotating device of 175 rpm, room temperature, a flask volume of 100 mL, and 1 mL of water and steam added to the flask. As shown in Figure 28, adding a small amount of water to the flask in an appropriate amount in addition to the water vapor resulted in higher carbon dioxide absorption capacity. It was found that the carbon dioxide absorption efficiency was most improved in the case of adding 0.4 mL of water. This is thought to be because the viscosity of the reaction solution could be adjusted to an appropriate range.

[0198] Example 16 Figure 29 is a graph showing the carbon dioxide release efficiency when a small amount of solvent is added to a flask using a monocarbamic acid compound obtained by absorbing carbon dioxide with 4,4'-methylenebis(2-methylcyclohexylamine). The carbon dioxide release capacity was measured under conditions of 1.0 mmol of monocarbamic acid compound, a nitrogen flow rate of 25 mL / min, and 80°C, for both cases where no solvent was added and where 6 mL of solvent (methanol) was added to the flask. As shown in Figure 29, it was found that the carbon dioxide release capacity was higher when a small amount of solvent was added to the flask in an appropriate amount.

[0199] Example 17 Figure 30(a) shows the carbon dioxide absorption efficiency when one cycle consists of absorbing carbon dioxide into 4,4'-methylenebis(2-methylcyclohexylamine) to form a monocarbamic acid compound, then releasing the carbon dioxide and returning it to 4,4'-methylenebis(2-methylcyclohexylamine). Except for changing the number of cycles to 1, 2, 3, 4, and 5, the carbon dioxide absorption capacity was measured under the following conditions: 1.0 mmol of 4,4'-methylenebis(2-methylcyclohexylamine), a carbon dioxide concentration of 400 ppm, a carbon dioxide flow rate of 50 mL / min, a rotation speed of the rotating device of 175 rpm, room temperature, a flask volume of 100 mL, and the supply of water vapor and 1 mL of water. As shown in Figure 30(a), it was found that the diamine compound could be repeatedly used while maintaining its high carbon dioxide absorption capacity.

[0200] Fig. 30(b) is a diagram showing the carbon dioxide release efficiency in Example 17. As shown in Fig. 30(b), it was found that even when the diamine compound was used repeatedly, it could be used repeatedly while maintaining a high carbon dioxide release capacity.

[0201] Fig. 31 is a diagram showing the carbon dioxide absorption amount and carbon dioxide release amount in Example 17. As shown in Fig. 31, even when the diamine compound was used repeatedly, the carbon dioxide absorption amount and carbon dioxide release capacity hardly changed, and it was found that the diamine compound could be used repeatedly without deterioration as a carbon dioxide absorbent (a). Note that although both the absorption amount and release amount appear to decrease slightly in the fourth and fifth cycles, this is thought to be due to the volatilization of the amine compound, not to a decrease in the function of the amine compound.

[0202] [Example 18] Figure 32 shows the state of isophoronediamine before absorbing carbon dioxide. １３ C-NMR and after carbon dioxide absorption into isophoronediamine １３ 32 shows a C-NMR spectrum and a C-NMR spectrum. As shown in Fig. 32, it was found that a monocarbamic acid compound was obtained by reacting an amine with carbon dioxide.

[0203] Example 19 Figure 33 shows the results of measuring the X-ray diffraction pattern at room temperature of a monocarbamic acid compound obtained by absorbing carbon dioxide into 4,4'-methylenebis(2-methylcyclohexylamine). After carbon dioxide absorption, a white solid and a transparent solid were visually observed in the flask. As shown in Figure 33, the white solid was more crystalline than the transparent solid, but both were found to be amorphous. The peaks of the transparent solid were at 7°, 15°, and 19°, indicating that the white solid and the transparent solid were of different crystal types.

[0204] [Example 20] Figure 34(a) is a graph showing the weight change when the transparent solid was heated. 6.9 mg of the transparent solid was heated to a temperature of 250°C. As shown in Figure 34(a), it was found that the release of carbon dioxide was completed when the solid was heated to 240°C. Figure 34(b) is a graph showing the weight change when the white solid was heated. 8.1 mg of the white solid was heated to a temperature of 300°C. As shown in Figure 34(b), it was found that the release of carbon dioxide was completed when the solid was heated to 270°C.

[0205] [Example 21] Fig. 35 is a diagram showing the results of repeated absorption and release of carbon dioxide in the same manner as in Example 17, except that the release of carbon dioxide was carried out at 90° C. As shown in Fig. 35, it was found that, as in Example 17, even when the diamine compound was repeatedly used at an elevated temperature, it could be repeatedly used while maintaining a high carbon dioxide release capacity.

[0206] The present invention can be used in the general fields of carbon dioxide fixation and carbon dioxide recovery.

[0207] REFERENCE SIGNS LIST 1 Carbon dioxide absorption device 2, 3 Carbon dioxide release device 10, 12 Reaction vessel 20, 22 Heating section 30, 32 First gas flow path 40, 42 First on-off valve 52 Second gas flow path 62 Second on-off valve 70, 72 Flow meter 100 Carbon dioxide absorbent (a) 200 Carbon dioxide release agent (b)

Claims

1. A method for absorbing carbon dioxide, comprising a step (A) of allowing a carbon dioxide absorbent (a) containing an amine compound that has at least one amino group and is liquid at room temperature to absorb carbon dioxide in the absence of a liquid solvent.

2. The method for absorbing carbon dioxide according to claim 1, wherein the step (A) comprises spraying vapor of at least one solvent selected from the group consisting of water and alcohols having 1 to 6 carbon atoms onto the carbon dioxide absorbent (a).

3. The method for absorbing carbon dioxide according to claim 1, wherein the amine compound comprises a compound represented by the following formula (1): (In formula (1), m is 0 or 1; R １ and R ２ are each independently an alkyl group, an alkoxy group, a carboxy group, an alkyloxycarbonyl group, a formyl group, an alkylcarbonyl group, an alkylthio group, a sulfo group, an alkyloxysulfonyl group, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have a substituent; L are each independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; １ and p ２ are each independently 1 or 2; when m is 0, q １ is an integer from 0 to 11, provided that p １ +q １ is 12 or less, and when m is 1, q １ is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11, and q ２ is an integer from 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have a substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have a substituent, the two or more R ２ may be bonded to each other to form a ring.

4. A method for producing a carbon dioxide releasing agent (b) comprising a monocarbamic acid compound having at least one carboxyamino group, by absorbing carbon dioxide into the carbon dioxide absorbent (a) using the carbon dioxide absorption method described in claim 1.

5. Use of a composition containing an amine compound that has at least one amino group and is liquid at room temperature as the carbon dioxide absorbent (a) in the carbon dioxide absorption method according to claim 1.

6. Use of a composition containing an amine compound that has at least one amino group and is liquid at room temperature for producing the carbon dioxide absorbent (a) used in the carbon dioxide absorption method according to claim 1.

7. A method for releasing carbon dioxide, comprising step (B) of releasing carbon dioxide from a carbon dioxide releasing agent (b) comprising a monocarbamic acid compound having at least one carboxyamino group in the absence of a liquid solvent.

8. A method for releasing carbon dioxide as described in claim 7, wherein step (B) includes exposing the carbon dioxide release agent (b) to reduced pressure conditions, heating the carbon dioxide release agent (b), or blowing a desorption gas containing an inert gas onto the carbon dioxide release agent (b).

9. The method for releasing carbon dioxide according to claim 7, wherein the monocarbamic acid compound includes a compound represented by the following formula (2): (In formula (2), m is 0 or 1; R １ and R ２ are each independently an alkyl group, an alkoxy group, a carboxy group, an alkyloxycarbonyl group, a formyl group, an alkylcarbonyl group, an alkylthio group, a sulfo group, an alkyloxysulfonyl group, a nitro group, a hydroxyl group, a thiol group, a cyano group, or a halogen atom, and the alkyl group may have a substituent; each L is independently a divalent or higher organic group, a carbonyl group, -O-, or -S-; m is 1; p １ and p ２ is 1; when m is 0, q １ is an integer from 0 to 11, provided that p １ +q １ is 12 or less, and when m is 1, q １ is an integer from 0 to 10, provided that p １ +q １ is less than or equal to 11, and q ２ is an integer from 0 to 10, and q １ is an integer of 2 or more, two or more R １ may be the same or different, and q ２ is an integer of 2 or more, two or more R ２ may be the same or different, and q １ is an integer of 2 or more, and two or more R １ is the alkyl group which may have a substituent, the two or more R １ may be bonded to each other to form a ring, and q ２ is an integer of 2 or more, and two or more R ２ is the alkyl group which may have a substituent, the two or more R ２ may be bonded to each other to form a ring.

10. A method for producing a carbon dioxide absorbent (a) comprising releasing carbon dioxide from the carbon dioxide releasing agent (b) by the carbon dioxide releasing method described in claim 7, and comprising an amine compound having at least one amino group and being liquid at room temperature.

11. Use of a composition containing a monocarbamic acid compound having at least one carboxyamino group as the carbon dioxide releasing agent (b) in the method for releasing carbon dioxide according to claim 7.

12. Use of a composition containing a monocarbamic acid compound having at least one carboxyamino group for producing the carbon dioxide releasing agent (b) used in the method for releasing carbon dioxide according to claim 7.

13. A carbon dioxide absorption device used in the carbon dioxide absorption method described in claim 1, comprising: a first reaction vessel containing a carbon dioxide absorbent (a) that has at least one amino group and contains an amine compound that is liquid at room temperature; and a first gas flow path connected to the first reaction vessel and through which a gas containing carbon dioxide flows into the first reaction vessel.

14. A carbon dioxide releasing device used in the carbon dioxide releasing method described in claim 7, comprising: a second reaction vessel containing a carbon dioxide releasing agent (b) including a monocarbamic acid compound having at least one carboxyamino group; a heating unit that heats the carbon dioxide releasing agent (b) contained in the second reaction vessel; and a second gas flow path that is connected to the second reaction vessel and releases a gas containing carbon dioxide from within the second reaction vessel.

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