Amine composition for carbon dioxide separation and method for producing same

Abstract

[Solution] A piperazine-containing aqueous solution described in the prior art has a problem that the entire solution solidifies at low temperatures such as a freezing point or less outdoors in winter. A composition for carbon dioxide separation, which contains an amine compound (A) represented by general formula (1) or (2), an amine compound (B) represented by general formula (3), and carbon dioxide (the amine compound (A) and the amine compound (B) may each independently form a carbonate or a carbamate), is used. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a carbon dioxide separation composition for separating carbon dioxide from a mixed gas containing carbon dioxide and a method for producing the same. Background Art

[0002] In recent years, due to the issue of global warming, the separation and recovery of carbon dioxide has attracted attention, and the development of carbon dioxide absorbing liquids has been actively carried out.

[0003] The most common carbon dioxide absorbing liquid is a monoethanolamine aqueous solution. Although monoethanolamine is inexpensive and readily available industrially, it has the characteristic that carbon dioxide absorbed at low temperatures will not diffuse unless the temperature reaches 120°C or above.

[0004] Therefore, the development of carbon dioxide absorbing liquids that have a lower diffusion temperature of carbon dioxide than monoethanolamine and consume less energy to recover carbon dioxide is underway. For example, an N-methyldiethanolamine-based absorbing liquid has been proposed (e.g., Patent Document 1). Furthermore, the development of carbon dioxide absorbing liquids that are prepared by mixing piperazine as an activator into N-methyldiethanolamine and dissolving the mixture in water is underway (e.g., Patent Document 2).

[0005] The piperazine-containing cleaning agent described in Patent Document 2 has the problem that piperazine precipitates at temperatures around 5 to 10°C, making pumping the cleaning solution difficult. As a solution to this problem, a method has been reported for producing a high-concentration piperazine-containing aqueous solution that stably dissolves piperazine without precipitation even at room temperature (Patent Document 3).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application No. 2006-528062

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 52-63171

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2008-56642 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] The piperazine-containing aqueous solutions described in the prior art have a problem in that the entire solution solidifies at temperatures below freezing, such as outdoors in winter, and a solution to this problem has been desired.

[0013] Solutions to the problem

[0014] The present inventors have conducted intensive studies to solve the above-mentioned problems and have completed the present invention described below.

[0015] That is, the present invention includes the following [1] to [9]. [1]

[0017] A composition for separating carbon dioxide, comprising:

[0018] An amine compound (A) represented by the following general formula (1) or (2), an amine compound (B) represented by the following general formula (3), and carbon dioxide (the amine compound (A) and the amine compound (B) may each independently form a carbonate or a carbamate),

[0019]

[0020] [In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. a and b each independently represent 0 or 1.]

[0021]

[0022] [In the above formula, R 1 Each independently represents an alkyl group having 1 to 3 carbon atoms.]

[0023]

[0024] [In the above formula, R 1 and R 2 Each independently represents an alkylene group having 2 to 3 carbon atoms.] [2]

[0026] The composition for separating carbon dioxide according to the above-mentioned [1], wherein

[0027] The amine compound (A) is at least one amine compound (A) selected from 1-(2-dimethylaminoethyl)-4-methylpiperazine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, and 1,4-diazabicyclo[2.2.2]octane. [3]

[0029] The composition for separating carbon dioxide according to [1] or [2] above, wherein

[0030] The above-mentioned amine compound (B) is piperazine or homopiperazine. [4]

[0032] The composition for separating carbon dioxide according to any one of [1] to [3] above, wherein

[0033] The amount of carbon dioxide is 10 to 150 parts by mole relative to 100 parts by mole of the total amount of the amine compound (A) and the amine compound (B). [5]

[0035] The composition for separating carbon dioxide according to any one of [1] to [4] above, wherein

[0036] The composition ratio of the amine compound (A) to the amine compound (B) is 5 to 1000 parts by mass of the amine compound (B) relative to 100 parts by mass of the amine compound (A). [6]

[0038] The carbon dioxide separation composition according to any one of the above-mentioned [1] to [5], further comprising an amine compound (C) represented by the following general formula (4) or (5).

[0039]

[0040] [In the above formula, R 1 and R 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2,3-dialkoxypropyl group having a total of 5 to 11 carbon atoms, an aminoalkyl group having 2 to 7 carbon atoms, or a hydroxyalkyl group having 4 to 10 carbon atoms. The alkyl group may or may not be a cycloalkyl group forming a ring.

[0041]

[0042] [In the above formula, R 1 represents an alkyl group having 1 to 6 carbon atoms, a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2,3-dialkoxypropyl group having a total carbon number of 5 to 11, an aminoalkyl group having 2 to 7 carbon atoms, or a hydroxyalkyl group having 4 to 10 carbon atoms. The alkyl group may or may not be a cycloalkyl group forming a ring. 2 and R 3 Each independently represents an alkylene group having 2 to 3 carbon atoms.] [7]

[0044] The composition for separating carbon dioxide according to the above-mentioned [6], wherein

[0045] The above-mentioned amine compound (C) is at least one amine compound (C) selected from 1-(2,3-dihydroxypropyl)-piperazine, N-(2-aminoethyl)piperazine, N-(2-hydroxyethyl)piperazine, N-(2-aminoethyl)-2-aminoethanol, N-methyl-1,3-diaminopropane, N-methylethylenediamine, N-isopropylethylenediamine, monoethanolamine, diethanolamine, 1-(aminoethylamino)-2,3-dihydroxypropane and ethylenediamine. [8]

[0047] The carbon dioxide separation composition according to any one of [1] to [7] above, further comprising water, wherein the concentration of the water is 30 to 75% by mass of the entire carbon dioxide separation composition in a state containing water. [9]

[0049] A method for producing a composition for separating carbon dioxide, which is a method for producing the composition for separating carbon dioxide described in [1] above, comprising:

[0050] At least an amine compound (A) represented by the following general formula (1) or (2), an amine compound (B) represented by the following general formula (3), and gaseous, liquid, or solid carbon dioxide are mixed.

[0051]

[0052] [In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. a and b each independently represent 0 or 1.]

[0053]

[0054] [In the above formula, R 1 Each independently represents an alkyl group having 1 to 3 carbon atoms.]

[0055]

[0056] [In the above formula, R 1 and R 2 Each independently represents an alkylene group having 2 to 3 carbon atoms.]

[0057] Effects of the Invention

[0058] Compared to conventionally known materials, the carbon dioxide separation composition of the present invention has a low freezing point, maintains a liquid state below freezing point, and exhibits excellent storage stability, thereby preventing the produced carbon dioxide separation composition from freezing during transportation or storage.

[0059] If the freezing can be avoided, the damage such as deformation or breakage of the transport container or storage container caused by the freezing can be reduced. Therefore, the present invention is very useful industrially. DETAILED DESCRIPTION

[0060] Hereinafter, the present invention will be described in detail.

[0061] As described above, cyclic secondary amines such as piperazine have low solubility in water, and conventionally known carbon dioxide absorbing liquids containing them have the problem of the entire liquid solidifying at low temperatures, particularly below freezing, outdoors in winter.

[0062] When the carbon dioxide absorbent solidifies, the container used to transport or store it is at high risk of deformation or damage. Furthermore, if the carbon dioxide absorbent solidifies during transport or storage, the entire transport or storage container must be heated to redissolve it before it is placed in carbon dioxide separation / recovery equipment. However, such equipment is not widely available. Therefore, conventional carbon dioxide absorbents require strict temperature management to prevent solidification, particularly in winter.

[0063] The carbon dioxide separation composition of the present invention has significant effects in that it has a lower freezing point than conventionally known carbon dioxide absorbing liquids, maintains a liquid state below freezing point, and exhibits excellent storage stability, and does not require strict temperature management.

[0064] First, the carbon dioxide separation composition of the present invention will be described.

[0065] The carbon dioxide separation composition of the present invention comprises an amine compound (A) represented by the following general formula (1) or (2), an amine compound (B) represented by the following general formula (3), and carbon dioxide (the above-mentioned amine compound (A) and amine compound (B) can each independently form a carbonate or a carbamate).

[0066] The carbon dioxide separation composition of the present invention may or may not further contain an amine compound (C) represented by the above-mentioned general formula (4) or (5) (the above-mentioned amine compound (C) may form a carbonate or a carbamate).

[0067] In the present invention, the amine compounds represented by the general formulas (1), (2), (3), (4), and (5) can absorb and diffuse carbon dioxide (see, for example, International Patent Publication No. WO2021 / 153650 A1, Japanese Patent Application Laid-Open No. 2022-101908, or Japanese Patent Application Laid-Open No. 2022-168949). Therefore, the carbon dioxide separation composition of the present invention has the ability to serve as a carbon dioxide separation / recovery agent.

[0068] In the above general formula (1), R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. a and b each independently represent 0 or 1.

[0069] a and b each independently represent 0 or 1. That is, the relationship a+b=0, 1, or 2 is satisfied.

[0070] When a=1 and b=1, the above general formula (1) is represented by the following general formula (1a).

[0071]

[0072] [In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.]

[0073] When a=0 and b=1, the above general formula (1) is expressed as the following general formula (1b).

[0074]

[0075] [In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.]

[0076] When a=0 and b=0, the above general formula (1) is expressed as the following general formula (1c).

[0077]

[0078] [In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.]

[0079] The amine compound represented by the general formula (1) is preferably when a = 0 and b = 1 or a = 0 and b = 0 from the viewpoint of excellent coagulation inhibition. That is, the amine compound represented by the general formula (1b) or (1c) is preferred.

[0080] In the above general formulas (1), (1a), (1b) and (1c), R 1 ~R 6 As long as it meets the above definition, there is no particular limitation, and examples thereof include: for example, each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. Among these, R 1 ~R 6 Preferably, each independently is a hydrogen atom, a methyl group or an ethyl group, and more preferably all are hydrogen atoms.

[0081] Specific examples of the amine compound represented by the general formula (1) include the following compounds (Exemplary Compounds 1 to 23), but are not limited thereto.

[0082]

[0083] The amine compound represented by the general formula (1) is preferably 1,4-diazabicyclo[2.2.2]octane-2-methanol (R 1 =R 2 =R 3 =R 4 =R 5 =R 6 = hydrogen atom, a=0, b=1) or 1,4-diazabicyclo[2.2.2]octane (R 1 =R 2 =R 3 =R 4 =R 5 =R 6 = hydrogen atom, a=0, b=0). That is, the amine compound represented by the following example compound 1 or 13 is preferred.

[0084]

[0085] In the above general formula (2), R 1 Each independently represents an alkyl group having 1 to 3 carbon atoms.

[0086] In the above general formula (2), R 1 As long as it meets the above definition, there is no particular limitation, and examples thereof include: for example, each independently methyl, ethyl, n-propyl or isopropyl. Among these, R 1 Preferably, all are methyl groups.

[0087] Specific examples of the amine compound represented by the general formula (2) include, for example, 1-(2-dimethylaminoethyl)-4-methylpiperazine.

[0088] The amine compound (A) is preferably at least one amine compound (A) selected from the group consisting of 1-(2-dimethylaminoethyl)-4-methylpiperazine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, and 1,4-diazabicyclo[2.2.2]octane, from the viewpoint of excellent coagulation inhibition.

[0089] In the above general formula (3), R 1 and R 2 Each independently represents an alkylene group having 2 to 3 carbon atoms.

[0090] In the above general formula (3), R 1 and R 2 As long as it meets the above definition, there is no particular limitation, and examples thereof include: for example, each independently can be ethylene or propylene. 1 and R 2 , from the viewpoint of excellent coagulation inhibition, preferably each independently is 1,2-ethylene, 1,2-propylene or 1,3-propylene, and more preferably R 1 and R 2 They are the same group and are 1,2-ethylene, 1,2-propylene or 1,3-propylene, and more preferably they are the same group and are 1,2-ethylene.

[0091] Specific examples of the amine compound (B) represented by the general formula (3) include piperazine and homopiperazine.

[0092]

[0093] In addition, the amine compound (B) is preferably piperazine or homopiperazine from the viewpoint of excellent coagulation suppression.

[0094] In the above general formula (4), R 1 and R 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2,3-dialkoxypropyl group having a total of 5 to 11 carbon atoms, an aminoalkyl group having 2 to 7 carbon atoms, or a hydroxyalkyl group having 4 to 10 carbon atoms. The alkyl group may or may not be a cycloalkyl group forming a ring.

[0095] In the above general formula (5), R 1 represents an alkyl group having 1 to 6 carbon atoms, a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2,3-dialkoxypropyl group having a total carbon number of 5 to 11, an aminoalkyl group having 2 to 7 carbon atoms, or a hydroxyalkyl group having 4 to 10 carbon atoms. The alkyl group may or may not be a cycloalkyl group forming a ring. 2 and R 3 Each independently represents an alkylene group having 2 to 3 carbon atoms.

[0096] The alkyl group having 1 to 6 carbon atoms (which may also be a cycloalkyl group) is not particularly limited, and examples thereof include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, cyclobutyl, n-pentyl, sec-pentyl, isopentyl, tert-pentyl, cyclopentyl, n-hexyl, sec-hexyl, isohexyl, tert-hexyl, and cyclohexyl.

[0097] The 2,3-dialkoxypropyl group having a total number of carbon atoms of 5 to 11 is not particularly limited, and examples thereof include a 2,3-dimethoxypropyl group (total number of carbon atoms: 5), a 2,3-diethoxypropyl group (total number of carbon atoms: 7), a 2,3-dipropoxypropyl group (total number of carbon atoms: 9), and a 2,3-dibutoxypropyl group (total number of carbon atoms: 11).

[0098] The aminoalkyl group having 2 to 7 carbon atoms (the alkyl group may be a cycloalkyl group) is not particularly limited, and examples thereof include 2-aminoethyl, 3-aminopropyl, and 4-aminobutyl.

[0099] The hydroxyalkyl group having 4 to 10 carbon atoms (the alkyl group may also be a cycloalkyl group) is not particularly limited, and examples thereof include 2-hydroxybutyl, 2-hydroxypentyl, 2-hydroxyhexyl, 2-hydroxyheptyl, 2-hydroxycyclopentyl, 2-hydroxycyclohexyl, 2-hydroxycycloheptyl, 2-hydroxycyclooctyl, 2-hydroxycyclononyl, and 2-hydroxycyclodecyl.

[0100] The alkylene group having 2 to 3 carbon atoms is not particularly limited, and examples thereof include ethylene and propylene. More specifically, examples thereof include 1,2-ethylene, 1,2-propylene, and 1,3-propylene.

[0101] Regarding R in the general formula (4) of the present invention 1 and R 2 , from the viewpoint of excellent carbon dioxide adsorption and desorption efficiency, they are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2-aminoethyl group or a 3-aminopropyl group.

[0102] Regarding R in the general formula (5) of the present invention 1 , from the viewpoint of excellent carbon dioxide adsorption and desorption efficiency, they are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2-aminoethyl group or a 3-aminopropyl group.

[0103] Regarding R in the general formula (5) of the present invention 2 and R 3 From the viewpoint of excellent carbon dioxide diffusion efficiency, they are preferably each independently 1,2-ethylene, 1,2-propylene or 1,3-propylene, more preferably they are the same group and are 1,2-ethylene, 1,2-propylene or 1,3-propylene, and more preferably they are the same group and are 1,2-ethylene.

[0104] The amine compound represented by the general formula (5) of the present invention is preferably an amine compound represented by the following general formula (5a).

[0105]

[0106] [In the above formula, R 4 and R in general formula (5) 1 have the same meaning.]

[0107] Specific examples of the amine compound (C) represented by the general formula (4) or (5) include, for example, cyclohexylamine, dicyclohexylamine, N-methylethylenediamine, N-isopropylethylenediamine, monoethanolamine, N-methylethanolamine, N-isopropylethanolamine, N,N-dimethylethanolamine, diethanolamine, N-methyldiethanolamine, N,N-dimethyl-1,4-diaminobutane, N-methyl-1,3-diaminopropane, N,N-dimethyl-1,3-diaminopropane, N,N-dimethyl-1,2-diaminopropane, N,N-dimethyl N,N-diethyl-1,3-diaminopropane, N,N-diethyl-1,2-diaminopropane, N,N-diethyl-1,2-diaminoethane, N-(2-aminoethyl)-2-aminoethanol, N-(3-aminopropyl)-2-aminoethanol, N-(2-aminopropyl)-2-aminoethanol, N-(4-aminobutyl)-2-aminoethanol, N-(2-aminoethyl)-3-aminopropanol, N-(3-aminopropyl)-3-aminopropanol, N-(2-aminopropyl)- 3-Aminopropanol, N-(4-aminobutyl)-3-aminopropanol, N-(2-aminoethyl)-4-aminobutanol, N-(3-aminopropyl)-4-aminobutanol, N-(2-aminopropyl)-4-aminobutanol, N-(4-aminobutyl)-4-aminobutanol, N-(2-aminocyclopentyl)-2-aminoethanol, N-(3-aminocyclopentyl)-2-aminoethanol, N-(2-aminocyclohexyl)-2-aminoethanol, N-(3-aminocyclohexyl)-2-aminoethanol, N-(4-aminocyclohexyl)- 2-aminoethanol, N-(2-aminocyclopentyl)-3-aminopropanol, N-(3-aminocyclopentyl)-3-aminopropanol, N-(2-aminocyclohexyl)-3-aminopropanol, N-(3-aminocyclohexyl)-3-aminopropanol, N-(4-aminocyclohexyl)-3-aminopropanol, N-methylpiperazine, N-ethylpiperazine, N-(2-hydroxyethyl)piperazine, N-(2-hydroxypropyl)piperazine, N-(2-aminoethyl)piperazine, N-(3-aminopropyl)piperazine or N-(2,3-dihydroxypropyl)piperazine, etc.

[0108] The amine compound (C) is preferably at least one amine compound (C) selected from the group consisting of 1-(2,3-dihydroxypropyl)-piperazine, N-(2-aminoethyl)piperazine, N-(2-hydroxyethyl)piperazine, N-(2-aminoethyl)-2-aminoethanol, N-methyl-1,3-diaminopropane, N-methylethylenediamine, N-isopropylethylenediamine, monoethanolamine, diethanolamine, 1-(aminoethylamino)-2,3-dihydroxypropane, and ethylenediamine, from the viewpoint of excellent carbon dioxide diffusion efficiency. More preferably, it is at least one amine compound (C) selected from the group consisting of 1-(2,3-dihydroxypropyl)-piperazine, N-(2-aminoethyl)piperazine, N-(2-hydroxyethyl)piperazine, N-(2-aminoethyl)-2-aminoethanol, monoethanolamine, diethanolamine, and 1-(aminoethylamino)-2,3-dihydroxypropane.

[0109] As described above, the carbon dioxide separation composition of the present invention comprises the amine compound (A), the amine compound (B), and carbon dioxide (the amine compound (A) and the amine compound (B) can each independently form a carbonate or a carbamate).

[0110] Generally, it is known that amine compounds interact with carbon dioxide to form amine carbonates and carbamates. These amine carbonates and carbamates are in a chemical equilibrium state within the mixture of the amine compound and carbon dioxide. Applying physical forces such as heating and reduced pressure can shift this chemical equilibrium toward a simple combination of the amine compound and carbon dioxide.

[0111] Therefore, when the carbon dioxide separation composition of the present invention contains a carbonate and / or carbamate of an amine compound (A) and / or an amine compound (B), the content and composition ratio (mass ratio or molar ratio, etc.) of the amine compound (A), amine compound (B) and carbon dioxide in the carbon dioxide separation composition of the present invention are specified as follows: the carbonate and / or carbamate of the amine compound (A) is regarded as a simple composition of the amine compound (A) and carbon dioxide, and the carbonate and / or carbamate of the amine compound (B) is regarded as a simple composition of the amine compound (B) and carbon dioxide.

[0112] The content of the amine compound (A) in the carbon dioxide separation composition of the present invention is not particularly limited, but is preferably 2 to 60% by mass, more preferably 3 to 50% by mass, more preferably 3 to 35% by mass, more preferably 3 to 25% by mass, more preferably 3 to 20% by mass, and more preferably 3 to 15% by mass, based on 100% by mass of the entire carbon dioxide separation composition.

[0113] The content of the amine compound (B) in the carbon dioxide separation composition of the present invention is not particularly limited, but is preferably 3 to 60 mass %, more preferably 5 to 50 mass %, and even more preferably 8 to 35 mass %, based on 100 mass % of the entire carbon dioxide separation composition.

[0114] The carbon dioxide content in the carbon dioxide separation composition of the present invention is not particularly limited, but is preferably 1-30 mass %, more preferably 1-20 mass %, and even more preferably 1-15 mass %, based on 100 mass % of the entire carbon dioxide separation composition.

[0115] In the carbon dioxide separation composition of the present invention, the composition ratio of the amine compound (A) to the amine compound (B) is not particularly limited. However, from the viewpoint of excellent carbon dioxide diffusion efficiency, the amine compound (B) is preferably 1 to 1000 parts by mass, more preferably 5 to 1000 parts by mass, more preferably 5 to 900 parts by mass, more preferably 10 to 700 parts by mass, more preferably 20 to 500 parts by mass, and more preferably 50 to 250 parts by mass, relative to 100 parts by mass of the amine compound (A).

[0116] The content of carbon dioxide in the carbon dioxide separation composition of the present invention is not particularly limited. For example, the carbon dioxide is preferably 1 to 200 parts by mass (parts by mole) of carbon dioxide relative to 100 parts by mass (parts by mole) of the total amount of the amine compounds (A) and (B), more preferably 5 to 175 parts by mass (parts by mole), more preferably 10 to 150 parts by mass (parts by mole), more preferably 20 to 120 parts by mass (parts by mole), and more preferably 30 to 110 parts by mass (parts by mole).

[0117] It should be noted that, regardless of whether the carbon dioxide separation composition of the present invention contains or does not contain amine compounds other than amine compounds (A) and (B) (for example, amine compound (C) or other amine compounds described later), the ratio of the content of all amine compounds (hereinafter referred to as "total amine compounds") contained in the carbon dioxide separation composition of the present invention to the content of carbon dioxide contained in the carbon dioxide separation composition of the present invention is not particularly limited. However, the amount of carbon dioxide is preferably 1 to 200 parts by mass (parts by mole) relative to 100 parts by mass (parts by mole) of the total amount of the total amine compounds, more preferably 5 to 175 parts by mass (parts by mole), more preferably 10 to 150 parts by mass (parts by mole), more preferably 20 to 120 parts by mass (parts by mole), and more preferably 30 to 110 parts by mass (parts by mole).

[0118] In addition, the carbon dioxide separation composition of the present invention may further contain an amine compound (C).

[0119] When the carbon dioxide utilization composition of the present invention contains an amine compound (C), the amine compound (C) may be in the form of a carbonate or a carbamate.

[0120] When the carbon dioxide separation composition of the present invention contains a carbonate or carbamate of an amine compound (C), the content and composition ratio (mass ratio or molar ratio, etc.) of the amine compound (C) and carbon dioxide in the carbon dioxide separation composition of the present invention are defined as follows: the carbonate or carbamate of the above-mentioned amine compound (C) is regarded as a simple composition of the amine compound (C) and carbon dioxide.

[0121] When the carbon dioxide separation composition of the present invention contains an amine compound (C), the content of the amine compound (C) is not particularly limited. When the entire carbon dioxide separation composition containing the amine compound (C) is taken as 100 mass %, the content of the amine compound (C) is preferably 2 to 30 mass %, more preferably 5 to 25 mass %, and even more preferably 10 to 20 mass %.

[0122] When the carbon dioxide separation composition of the present invention contains an amine compound (C), the content of carbon dioxide in the above-mentioned carbon dioxide separation composition is not particularly limited. For example, with respect to 100 parts by mass (parts by mole) of the total amount of the amine compound (A), the amine compound (B) and the amine compound (C), the carbon dioxide is preferably 1 to 200 parts by mass (parts by mole), more preferably 5 to 175 parts by mass (parts by mole), more preferably 10 to 150 parts by mass (parts by mole), more preferably 20 to 120 parts by mass (parts by mole), and more preferably 30 to 110 parts by mass (parts by mole).

[0123] Furthermore, the carbon dioxide separation composition of the present invention may or may not contain an amine compound different from the amine compound (A), the amine compound (B), or the amine compound (C) (hereinafter referred to as "other amine compound").

[0124] When the carbon dioxide separation composition of the present invention contains the above-mentioned other amine compound, the other amine compound may form a carbonate or a carbamate.

[0125] In the case where the carbon dioxide separation composition of the present invention contains carbonates or carbamates of other amine compounds, the content and composition ratio (mass ratio or molar ratio, etc.) of other amine compounds and carbon dioxide in the carbon dioxide separation composition of the present invention are stipulated as follows: the carbonates or carbamates of the above-mentioned other amine compounds are regarded as simple compositions of the other amine compounds and carbon dioxide.

[0126] When the carbon dioxide separation composition of the present invention contains other amine compounds, the content of the other amine compounds is not particularly limited. The content is preferably 2 to 30 mass %, more preferably 5 to 25 mass %, and even more preferably 10 to 20 mass %, based on 100 mass % of the entire carbon dioxide separation composition containing the other amine compounds.

[0127] When the carbon dioxide separation composition of the present invention contains other amine compounds, the content of carbon dioxide in the above-mentioned carbon dioxide separation composition is not particularly limited. For example, with respect to 100 parts by mass (parts by mole) of the total amount of the amine compound (A), the amine compound (B) and the other amine compounds, the carbon dioxide is preferably 1 to 200 parts by mass (parts by mole), more preferably 5 to 175 parts by mass (parts by mole), more preferably 10 to 150 parts by mass (parts by mole), more preferably 20 to 120 parts by mass (parts by mole), and more preferably 30 to 110 parts by mass (parts by mole).

[0128] The carbon dioxide separation composition of the present invention may further contain water. The water content is preferably 30-75% by mass, more preferably 35-70% by mass, and even more preferably 40-65% by mass, based on 100% by mass of the entire carbon dioxide separation composition containing water.

[0129] The carbon dioxide separation composition of the present invention may further contain a solvent other than water (hereinafter referred to as an "organic solvent"). The organic solvent is not particularly limited, and examples thereof include methanol, ethanol, propanol, isopropanol, ethylene glycol, propylene glycol, glycerol, and ethylene glycol monomethyl ether.

[0130] The content of the organic solvent is preferably 1 to 30 mass %, more preferably 2 to 25 mass %, and even more preferably 5 to 20 mass %, based on 100 mass % of the entire carbon dioxide separation composition including the organic solvent.

[0131] The carbon dioxide separation composition of the present invention may further contain components not described above, such as surfactants, defoaming agents, and antioxidants.

[0132] The content of all amine compounds (the total amount of amine compound (A), amine compound (B), amine compound (C), and other amine compounds) in the carbon dioxide separation composition of the present invention is preferably 10 to 70 mass %, more preferably 20 to 60 mass %, and even more preferably 25 to 50 mass %, based on the total amount of the carbon dioxide separation composition containing all the above amine compounds being 100 mass %, from the viewpoint of increasing the carbon dioxide diffusion amount per unit mass.

[0133] The carbon dioxide contained in the carbon dioxide separation composition of the present invention may be contained in any form as long as it is mixed with the various amine compounds and the like described above.

[0134] Note that, since the carbon dioxide in the carbon dioxide separation composition of the present invention is released from the composition system by heating, the carbon dioxide content can be confirmed by measuring the amount of release.

[0135] The carbon dioxide content in the carbon dioxide separation composition of the present invention can be confirmed using a total organic carbon meter or a nuclear magnetic resonance apparatus.

[0136] The carbon dioxide separation composition of the present invention can be produced by mixing at least the above-mentioned amine compound (A), the above-mentioned amine compound (B), and gaseous, liquid or solid carbon dioxide, and is preferably produced by mixing at least the amine compound (A), the above-mentioned amine compound (B) and a gas containing carbon dioxide or dry ice.

[0137] In the above production method, the above amine compound (C), the above other amine compound, water, and / or the above organic solvent may be mixed simultaneously or separately.

[0138] When the amine compound (A), the amine compound (B), gaseous, liquid or solid carbon dioxide, the amine compound (C), other amine compounds, water, and / or the above-mentioned organic solvent are mixed in this order, the order is not particularly limited.

[0139] In the carbon dioxide separation composition of the present invention or the method for producing the same, the amine compound represented by the general formula (1), (2), (3), (4), or (5) or other amine compounds may be commercially available products or products synthesized by known methods. The purity of these amine compounds is not particularly limited, but is preferably 90% or higher, more preferably 95% or higher.

[0140] When at least the amine compound (A), the amine compound (B), and gaseous, liquid, or solid carbon dioxide are mixed, the carbon dioxide separation composition of the present invention obtained by mixing them is preferably liquid at 0° C. or lower and at atmospheric pressure.

[0141] The gaseous, liquid, or solid carbon dioxide is preferably a gas containing carbon dioxide from the viewpoint of excellent handleability.

[0142] As the gaseous, liquid, or solid carbon dioxide, when a gas containing carbon dioxide is used, the method for mixing at least the amine compound (A), the amine compound (B), and the gas containing carbon dioxide is not particularly limited, and a known method can be used. Examples of the known method include a bubbling method, and a facing contact method using a packed tower or a plate tower ( )wait.

[0143] The gas containing carbon dioxide may be pure carbon dioxide gas or a mixed gas containing carbon dioxide and other gases. The other gases are not particularly limited and include, for example, atmospheric air, nitrogen, oxygen, hydrogen, argon, neon, helium, carbon monoxide, water vapor, methane, ethane, propane, butane, ethylene, propylene, butylene, isobutylene, butadiene, or nitrogen oxides.

[0144] The method for mixing at least the above-mentioned amine compound (A), the above-mentioned amine compound (B), and gaseous, liquid or solid carbon dioxide is not particularly limited, and an example thereof includes a method in which at least the above-mentioned amine compound (A), the above-mentioned amine compound (B), and gaseous, liquid or solid carbon dioxide are mixed and stirred while controlling the temperature within the range of -30°C to 80°C.

[0145] The carbon dioxide separation composition of the present invention exhibits the following functions: by contacting with a gas containing carbon dioxide, it can absorb carbon dioxide with high selectivity, and then diffuse the absorbed carbon dioxide by high temperature and / or reduced pressure treatment. Therefore, the carbon dioxide separation composition of the present invention can be used as a carbon dioxide separation agent. In addition, such carbon dioxide separation operation is hereinafter also referred to as a carbon dioxide separation process.

[0146] In the carbon dioxide separation step, there is no particular limitation on the method for contacting the gas containing carbon dioxide with the carbon dioxide separation composition of the present invention, and a known method can be used. Examples of the known method include a bubbling method, a facing contact method using a packed tower or a plate tower ( )wait.

[0147] In the carbon dioxide separation step, the temperature at which the carbon dioxide-containing gas is absorbed by the carbon dioxide separation composition of the present invention is not particularly limited, but is generally in the range of 0°C to 50°C.

[0148] In the carbon dioxide separation step, the temperature for diffusing carbon dioxide from the carbon dioxide separation composition of the present invention is not particularly limited, but is generally in the range of 60 to 150° C. However, from the viewpoint of energy reduction, it is preferably 100° C. or lower.

[0149] Furthermore, the carbon dioxide separation composition of the present invention can be used as a carbon dioxide absorbing and diffusing agent in which the composition is supported or attached to any carrier.

[0150] The support is not particularly limited, and examples thereof include silica, alumina, magnesia, porous glass, activated carbon, and polymethyl methacrylate-based porous resins or fibers.

[0151] As the above-mentioned silica, various silicas are known, including crystalline and non-crystalline (amorphous), zeolite-like silica having fine pores, mesoporous silica, etc. The silica that can be used in the carbon dioxide absorbing and diffusing agent of the present invention is not particularly limited, and industrially available silica can be used, preferably silica with a large surface area.

[0152] From the viewpoint of excellent carbon dioxide absorption, the amount of the carbon dioxide separation composition supported in the carbon dioxide absorbing and diffusing agent using a carrier is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, relative to the weight of the carrier supporting the carbon dioxide separation composition.

[0153] The amount of water contained in the carbon dioxide absorbing and diffusing agent using a carrier is preferably equimolar or greater relative to the absorbed carbon dioxide. An equimolar or greater amount of water relative to carbon dioxide is preferred because the diffusion energy of carbon dioxide does not become excessive.

[0154] The carbon dioxide-containing gas used in the carbon dioxide separation step may be pure carbon dioxide gas or a mixed gas containing carbon dioxide and other gases. The other gases are not particularly limited and include, for example, atmospheric air, nitrogen, oxygen, hydrogen, argon, neon, helium, carbon monoxide, water vapor, methane, or nitrogen oxides.

[0155] It should be noted that the gas containing carbon dioxide used in the carbon dioxide separation step is more preferably combustion exhaust gas. The carbon dioxide-containing mixed gas preferably has a carbon dioxide concentration of 5% by volume or more, more preferably 10% by volume or more.

[0156] The carbon dioxide separation composition of the present invention is not particularly limited and can be used, for example, to separate carbon dioxide from combustion exhaust gases generated in thermal power plants, steel mills, and cement plants, and to separate carbon dioxide from steam-reformed gas obtained in a steam reforming step.

[0157] Example

[0158] Hereinafter, the present invention will be described using examples, but the present invention is not to be construed as being limited thereto.

[0159] In the following examples, the molar ratio of carbon dioxide to total amine compounds was calculated from the integrated ratio of the peak derived from the amine compound and the peak derived from carbon dioxide measured by the inverse gated decoupling method using a nuclear magnetic resonance analyzer.

[0160] [Example 1]

[0161] 5g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (manufactured by Tosoh), 35g of piperazine (anhydrous product manufactured by Tokyo Chemical Industry Co., Ltd.), and 60g of pure water were placed in a 200mL gas absorption bottle, the temperature of which was adjusted to 40°C in a water bath, and the mixture was stirred to obtain a homogeneous solution. A mixture of carbon dioxide gas and nitrogen gas was bubbled through the solution, which was maintained at 40°C in a water bath, at a rate of 140mL / minute to absorb the carbon dioxide. The gas absorption bottle was then cooled to 60°C and nitrogen gas was bubbled through at a rate of 200mL / minute to partially expel the temporarily absorbed carbon dioxide. Expulsion was stopped when the amount of carbon dioxide dissolved in the solution reached 12.8g. The amount of carbon dioxide absorbed and expelled was monitored using a gas flowmeter and a carbon dioxide concentration meter. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.66.

[0162] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0163] [Example 2]

[0164] 10g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (manufactured by Tosoh), 30g of piperazine (anhydrous product manufactured by Tokyo Chemical Industry), and 60g of pure water were placed in a 200mL gas absorption bottle, the temperature of which was adjusted to 40°C in a water bath, and the mixture was stirred to obtain a homogeneous solution. A mixture of carbon dioxide gas and nitrogen gas was bubbled through the solution, which was maintained at 40°C in a water bath, at a rate of 140mL / minute to absorb the carbon dioxide. The gas absorption bottle was then cooled to 60°C and nitrogen gas was bubbled through at a rate of 200mL / minute to partially expel the temporarily absorbed carbon dioxide. Expulsion was stopped when the amount of carbon dioxide dissolved in the solution reached 8.7g. The amount of carbon dioxide absorbed and expelled was monitored using a gas flowmeter and a carbon dioxide concentration meter. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.47.

[0165] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0166] [Example 3]

[0167] 20g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (manufactured by Tosoh), 20g of piperazine (anhydrous product manufactured by Tokyo Chemical Industry), and 60g of pure water were placed in a 200mL gas absorption bottle, the temperature of which was adjusted to 40°C in a water bath, and the mixture was stirred to obtain a homogeneous solution. A mixture of carbon dioxide gas and nitrogen gas was bubbled through the solution, which was maintained at 40°C in a water bath, at a rate of 140mL / minute to absorb the carbon dioxide. The gas absorption bottle was then cooled to 60°C and nitrogen gas was bubbled through at a rate of 200mL / minute to partially expel the temporarily absorbed carbon dioxide. Expulsion was stopped when the amount of carbon dioxide dissolved in the solution reached 7.4g. The amount of carbon dioxide absorbed and expelled was monitored using a gas flowmeter and a carbon dioxide concentration meter. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.45.

[0168] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0169] [Example 4]

[0170] 15g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (manufactured by Tosoh), 10g of piperazine (anhydrous product manufactured by Tokyo Chemical Industry), 15g of N-(2-aminoethyl)piperazine (manufactured by Tokyo Chemical Industry), and 60g of pure water were placed in a 200mL gas absorption bottle. The temperature was adjusted to 40°C in a water bath, and the mixture was mixed and stirred to obtain a uniform solution. A mixture of carbon dioxide gas and nitrogen gas was bubbled into the solution, which was heated to 40°C in a water bath, at a rate of 140mL / min to absorb the carbon dioxide. The gas absorption bottle was then heated to 60°C and nitrogen gas was bubbled in at a rate of 200mL / min to partially expel the temporarily absorbed carbon dioxide. The expulsion was stopped when the amount of carbon dioxide dissolved in the solution reached 5.9g. It should be noted that the amount of carbon dioxide absorbed and expelled was monitored using a gas flow meter and a carbon dioxide concentration meter. At this time, the molar ratio of carbon dioxide to the total amine compounds in the solution (the number of moles of carbon dioxide ÷ the number of moles of the total amine compounds) was 0.40.

[0171] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0172] [Example 5]

[0173] 5 g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 27 g of 1-(2-dimethylaminoethyl)-4-methylpiperazine (Tokyo Chemical Industry), 15 g of piperazine (Tokyo Chemical Industry, anhydrous), and 53 g of pure water were placed in a 200 mL gas absorption bottle. The mixture was stirred and maintained at 40°C in a water bath to obtain a homogeneous solution. A mixture of carbon dioxide gas and nitrogen gas was bubbled through the solution, which was maintained at 60°C in a water bath, at a rate of 10 mL / min. The carbon dioxide absorption was monitored using a gas flowmeter and a carbon dioxide concentration meter. Bubbling was stopped when the amount of carbon dioxide dissolved in the solution reached 4.8 g. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.30.

[0174] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0175] [Example 6]

[0176] 5 g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 22 g of 1-(2-dimethylaminoethyl)-4-methylpiperazine (Tokyo Chemical Industry), 20 g of piperazine (Tokyo Chemical Industry, anhydrous), and 53 g of pure water were placed in a 200 mL gas absorption bottle. The mixture was stirred and maintained at 40°C in a water bath to obtain a homogeneous solution. A mixture of carbon dioxide and nitrogen was bubbled through the solution, maintained at 60°C in a water bath, at a rate of 10 mL / min. The carbon dioxide absorption was monitored using a gas flowmeter and a carbon dioxide concentration meter. Bubbling was stopped when the amount of dissolved carbon dioxide in the solution reached 6.0 g. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.35.

[0177] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0178] [Example 7]

[0179] 5g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 32g of 1-(2-dimethylaminoethyl)-4-methylpiperazine (Tokyo Chemical Industry), 10g of piperazine (Tokyo Chemical Industry, anhydrous), and 53g of pure water were placed in a 200mL gas absorption bottle. The mixture was stirred and maintained at 40°C in a water bath to obtain a homogeneous solution. A mixture of carbon dioxide and nitrogen was bubbled through the solution, which was maintained at 80°C in a water bath, at a rate of 10mL / min. The carbon dioxide absorption was monitored using a gas flowmeter and a carbon dioxide concentration meter. Bubbling was stopped when the amount of carbon dioxide dissolved in the solution reached 1.7g. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.11.

[0180] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0181] [Example 8]

[0182] 10g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 22g of 1-(2-dimethylaminoethyl)-4-methylpiperazine (Tokyo Chemical Industry), 15g of piperazine (Tokyo Chemical Industry, anhydrous), and 53g of pure water were placed in a 200mL gas absorption bottle. The mixture was stirred and heated to 40°C in a water bath to obtain a homogeneous solution. A mixture of carbon dioxide gas and nitrogen gas was bubbled through the solution, which was heated to 60°C in a water bath, at a rate of 10mL / min. The carbon dioxide absorption was monitored using a gas flowmeter and a carbon dioxide concentration meter. Bubbling was stopped when the amount of carbon dioxide dissolved in the solution reached 5.1g. At this point, the molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.31.

[0183] A portion of the resulting solution (corresponding to the carbon dioxide separation composition of the present invention) was filled into 20 mL sample bottles to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other was left at -5°C (a low-temperature constant temperature room) for one week. Both samples showed no precipitation of piperazine, and the solution remained liquid without solidification.

[0184] [Comparative Example 1]

[0185] 40g of piperazine (anhydrous product, manufactured by Tokyo Chemical Industry) and 40g of N-methyldiethanolamine (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were dissolved in 120g of 50°C warm water to produce an aqueous solution containing 20% ​​piperazine and 20% N-methyldiethanolamine by weight. After the solution temperature was adjusted to 40°C, a gas containing 20% ​​CO₂ was continuously bubbled through a glass spherical filter at 300ml / min for one hour. The amount of inorganic carbon absorbed by the CO₂ in the resulting liquid was measured using a gas chromatography-based total organic carbon meter and found to be 5.9g, representing a ratio of 0.289 mol / mol to the amount of piperazine in the solution. The molar ratio of carbon dioxide to total amine compounds in the solution (moles of carbon dioxide divided by moles of total amine compounds) was 0.17.

[0186] A portion of the resulting solution was filled into a 20 mL sample bottle to prepare two samples for storage testing. One was left at 20°C (a constant temperature room) for one week, and the other at -5°C (a low-temperature constant temperature room) for one week. No piperazine precipitated in either sample. The sample left at 20°C remained liquid, but the sample left at -5°C solidified entirely.

[0187] [Comparative Example 2]

[0188] 20g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 20g of piperazine (Tokyo Chemical Industry, anhydrous), and 60g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and the mixture was stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0189] [Comparative Example 3]

[0190] 30g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 10g of piperazine (Tokyo Chemical Industry, anhydrous), and 60g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and the mixture was stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0191] [Comparative Example 4]

[0192] 15g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 10g of piperazine (Tokyo Chemical Industry, anhydrous), 15g of N-(2-aminoethyl)piperazine (Tokyo Chemical Industry), and 60g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and the mixture was stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0193] [Comparative Example 5]

[0194] 20g of N,N,N',N'',N''-pentamethyldiethylenetriamine (Tokyo Chemical Industry), 20g of piperazine (Tokyo Chemical Industry, anhydrous), and 60g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and mixed and stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0195] [Comparative Example 6]

[0196] 27g of N,N,N',N'',N''-pentamethyldiethylenetriamine (Tokyo Chemical Industry), 10g of piperazine (Tokyo Chemical Industry, anhydrous), and 63g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and mixed and stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0197] [Comparative Example 7]

[0198] 5g of N-methyldiethanolamine (Fuji Film Wako Pure Chemical Industries, Ltd.), 35g of piperazine (Tokyo Chemical Industry, anhydrous), and 60g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and mixed and stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0199] [Comparative Example 8]

[0200] 30g of N-methyldiethanolamine (Fuji Film Wako Pure Chemical Industries, Ltd.), 10g of piperazine (Tokyo Chemical Industry, anhydrous), and 60g of pure water were placed in a 200mL sample bottle. The temperature was adjusted to 40°C in a water bath and mixed and stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0201] [Comparative Example 9]

[0202] 5g of 1,4-diazabicyclo[2,2,2]octane-2-methanol (Tosoh), 32g of 1-(2-dimethylaminoethyl)-4-methylpiperazine (Tokyo Chemical Industry), 10g of piperazine (Tokyo Chemical Industry, anhydrous), and 53g of pure water were placed in a 200mL gas absorption bottle. The temperature was adjusted to 40°C in a water bath and the mixture was stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0203] [Comparative Example 10]

[0204] 20g of bis(2-dimethylaminoethyl)ether (manufactured by Tokyo Chemical Industry), 20g of piperazine (anhydrous product, manufactured by Tokyo Chemical Industry), and 60g of pure water were placed in a 200mL gas absorption bottle. The temperature was adjusted to 40°C in a water bath, and the mixture was stirred to obtain a uniform solution. A portion of the solution was filled into a 20mL sample bottle and allowed to stand at -5°C (low-temperature thermostat) for one week. The entire solution solidified.

[0205]

[0206]

[0207]

[0208]

[0209]

[0210] While the present invention has been described in detail and with reference to specific embodiments, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the present invention.

[0211] It should be noted that the contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2023-18851 filed on February 10, 2023 and Japanese Patent Application No. 2023-204267 filed on December 1, 2023 are cited herein and adopted as the disclosed contents of the specification of the present invention.

[0212] Industrial Applicability

[0213] As is clear from Examples 1-8 and Comparative Examples 1-10, the carbon dioxide separation composition of the present invention resolves the prior art issue of solidification below freezing. Therefore, the carbon dioxide separation composition of the present invention can be handled as a stable liquid even below freezing, which is very useful industrially.

Claims

1. A composition for separating carbon dioxide, comprising: An amine compound (A) represented by the following general formula (1) or (2), an amine compound (B) represented by the following general formula (3), and carbon dioxide, in, The amine compound (A) and the amine compound (B) can each independently form a carbonate or a carbamate. ， In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, a and b each independently represent 0 or 1, ， In the above formula, R 1 Each independently represents an alkyl group having 1 to 3 carbon atoms, ， In the above formula, R 1 and R 2 Each independently represents an alkylene group having 2 to 3 carbon atoms.

2. The carbon dioxide separation composition according to claim 1, wherein The amine compound (A) is at least one amine compound (A) selected from 1-(2-dimethylaminoethyl)-4-methylpiperazine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, and 1,4-diazabicyclo[2.2.2]octane.

3. The composition for separating carbon dioxide according to claim 1, wherein The amine compound (B) is piperazine or homopiperazine.

4. The composition for separating carbon dioxide according to claim 1, wherein The amount of carbon dioxide is 10 to 150 parts by mole relative to 100 parts by mole of the total amount of the amine compound (A) and the amine compound (B).

5. The composition for separating carbon dioxide according to claim 1, wherein The composition ratio of the amine compound (A) to the amine compound (B) is 5 to 1000 parts by mass of the amine compound (B) relative to 100 parts by mass of the amine compound (A).

6. The carbon dioxide separation composition according to claim 1, further comprising an amine compound (C) represented by the following general formula (4) or (5): ， In the above formula, R 1 and R 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2,3-dialkoxypropyl group having a total carbon number of 5 to 11, an aminoalkyl group having 2 to 7 carbon atoms, or a hydroxyalkyl group having 4 to 10 carbon atoms, and the alkyl group may or may not be a cycloalkyl group forming a ring, ， In the above formula, R 1 represents an alkyl group having 1 to 6 carbon atoms, a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2,3-dialkoxypropyl group having a total carbon number of 5 to 11, an aminoalkyl group having 2 to 7 carbon atoms, or a hydroxyalkyl group having 4 to 10 carbon atoms, wherein the alkyl group may or may not be a cycloalkyl group forming a ring, and R 2 and R 3 Each independently represents an alkylene group having 2 to 3 carbon atoms.

7. The composition for separating carbon dioxide according to claim 6, wherein The amine compound (C) is at least one amine compound (C) selected from 1-(2,3-dihydroxypropyl)-piperazine, N-(2-aminoethyl)piperazine, N-(2-hydroxyethyl)piperazine, N-(2-aminoethyl)-2-aminoethanol, N-methyl-1,3-diaminopropane, N-methylethylenediamine, N-isopropylethylenediamine, monoethanolamine, diethanolamine, 1-(aminoethylamino)-2,3-dihydroxypropane and ethylenediamine. The carbon dioxide separation composition according to claim 1 , further comprising water, wherein the concentration of the water is 30 to 75% by mass of the entire carbon dioxide separation composition in a state containing water.

9. A method for producing a composition for separating carbon dioxide, which is a method for producing the composition for separating carbon dioxide according to claim 1, the method comprising: At least an amine compound (A) represented by the following general formula (1) or (2), an amine compound (B) represented by the following general formula (3), and gaseous, liquid, or solid carbon dioxide are mixed. ， In the above formula, R 1 ~R 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, a and b each independently represent 0 or 1, ， In the above formula, R 1 Each independently represents an alkyl group having 1 to 3 carbon atoms, ， In the above formula, R 1 and R 2 Each independently represents an alkylene group having 2 to 3 carbon atoms.

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