Carbon dioxide adsorbent and method for separating and recovering carbon dioxide

Abstract

The present disclosure aims to provide an adsorbent for separating and recovering carbon dioxide and a method for separating and recovering carbon dioxide, which have a high carbon dioxide absorption capacity, a high carbon dioxide release and absorption capacity at low temperatures, and both resistance to heat and oxygen, and little deterioration. 【Solution】 A carbon dioxide adsorbent comprising an amine (A) represented by formula (11) and a support. JPEG2026101636000040.jpg2370 In the formula, R 1 is a hydrogen atom, an alkyl group which may have a substituent, a heterocyclic group which may have a substituent, or a cycloalkyl group which may have a substituent, R 2 is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, A 1 is an n1-valent organic residue whose terminal is an oxygen atom or a nitrogen atom, n1 represents an integer of 2 to 12.

Description

[Technical Field]

[0001] This disclosure relates to a carbon dioxide adsorbent and a method for separating and recovering carbon dioxide. [Background technology]

[0002] In recent years, the rapid increase in greenhouse gas emissions such as carbon dioxide and methane associated with social activities has been cited as one of the causes of global warming. In particular, carbon dioxide is the most important greenhouse gas, and in accordance with the Paris Agreement which came into effect in 2016, measures to reduce carbon dioxide emissions are urgently needed.

[0003] As part of efforts to reduce carbon dioxide emissions, the separation and capture of carbon dioxide is attracting attention, and the development of carbon dioxide absorbent solutions is being actively pursued. Therefore, in recent years, the development of carbon dioxide separation and capture technologies using chemical absorption methods, primarily composed of aqueous solutions of amine compounds, has been vigorously promoted, targeting carbon dioxide-containing gases emitted from power plants and steel mills.

[0004] On the other hand, as a method for separating acidic gases such as carbon dioxide, adsorption methods have also been developed, in which the acidic gas is adsorbed onto an adsorbent. In adsorption methods, porous materials filled with amine compounds are sometimes used.

[0005] For example, Patent Document 1 discloses a polyethylene polyamine derivative with excellent carbon dioxide absorption and release properties, in which some or all of the primary amino groups of polyethylene polyamine having 4 or more nitrogen atoms are replaced with hydroxyalkyl groups having 1 to 4 carbon atoms, and an adsorbent comprising a porous support.

[0006] Patent Document 2 discloses an adsorbent characterized by a reaction product of an amine and an epoxide that is excellent at adsorbing carbon dioxide at mild temperatures or room temperature.

[0007] Patent documents 3 and 4 disclose adsorbents characterized by amines substituted with glycidyl ether groups.

[0008] Patent Document 5 discloses an acidic gas adsorbent comprising a porous body and a solid amine compound supported on the surface of the pores of the porous body. In this invention, an amine polymer containing constituent units derived from epoxy monomers is used as the amine compound.

[0009] Patent documents 1 to 5 mentioned above all disclose the use of compounds as adsorbents in which part or all of the amine structure is modified by reacting polyethyleneimine or polyamine structures containing two or more nitrogen atoms in the molecule with an epoxide compound. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2022-7403 [Patent Document 2] International Publication No. 2016 / 114991 [Patent Document 3] International Publication No. 2023 / 215873 [Patent Document 4] International Publication No. 2024 / 124198 [Patent Document 5] International Publication No. 2022 / 202848 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Carbon dioxide adsorbents absorb carbon dioxide from a gas containing carbon dioxide, for example, by coming into contact with the gas. After absorbing carbon dioxide, the adsorbent releases the carbon dioxide, for example, by pressurizing or heating, and it is desirable to reduce the energy used in these processes. Furthermore, it is desirable to reuse the adsorbent after releasing the carbon dioxide, but the amines in the adsorbent that have absorbed carbon dioxide sometimes degrade the adsorbent's performance when repeatedly subjected to heating under an oxygen stream.

[0012] The present disclosure aims to provide a carbon dioxide adsorbent and a method for separating and recovering carbon dioxide, which have a high carbon dioxide absorption capacity, a high carbon dioxide release capacity at low temperatures, high resistance to heat and oxygen, and little deterioration in the absorption and desorption process.

Means for Solving the Problems

[0013] The present disclosure provides a solid adsorbent for separating and recovering carbon dioxide and a method for separating and recovering carbon dioxide as described below. [1] A carbon dioxide adsorbent comprising an amine (A) represented by the formula (11) and a support.

[0014]

Chemical formula

[0015] , is a hydrogen atom, an alkyl group which may have a substituent, a heterocyclic group which may have a substituent, or a cycloalkyl group which may have a substituent, R 2 is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, A 1 is an n1-valent organic residue whose terminal is an oxygen atom or a nitrogen atom, n1 represents an integer of 2 to 12. [2] The carbon dioxide adsorbent according to [1], wherein the A 1 is represented by the following formula (12) or formula (13). [(* -) n2 X 1 -] n A (12)

[0015]

Chemical formula

[0016] [ka] In the formula, X is an oxygen atom, or -NR 11 -and, R 11 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or R 1 R 2 It is N-CH2CH(OH)CH2- A is an n-valent organic residue, n represents an integer between 2 and 6. [4] The carbon dioxide adsorbent according to [3], wherein X is an oxygen atom. [5] The R 1 The optionally substituted alkyl group, optionally substituted heterocyclic group, and optionally substituted cycloalkyl group comprises two or more nitrogen atoms, as described in any of [1] to [4]. [6] The R 1 A carbon dioxide adsorbent according to any of [1] to [5], wherein the carbon dioxide adsorbent is represented by the following formula (2) or (3).

[0017] [ka] During the ceremony, R 3 is a hydrogen atom or a methyl group, p is an integer between 0 and 4. R 4 and R 6 Each of these is independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a hydroxyalkyl group. R 5This is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group, or -(CH2)sR 7 And, R 7 is a hydroxyl group, or -N(R 8 )R 9 And, R 8 and R 9 Each of these is independently a hydrogen atom, a methyl group, or a hydroxyalkyl group. q is either 2 or 3. r is between 2 and 4. s is 2 or 3, m is between 0 and 3. [7] The carbon dioxide adsorbent according to any one of [1] to [6], wherein the support is at least one selected from the group consisting of silica, silica alumina, alumina, zeolite, zeolite-related compounds, magnesia, titanium dioxide, calcium silicate, carbon nanotubes, activated carbon, polymethyl methacrylate, zirconia, natural minerals, waste solids, and carbon molecular sieves. [8] The carbon dioxide adsorbent according to any one of [1] to [7], wherein the organic residue in A is one of a substituted linear or branched aliphatic hydrocarbon residue, a substituted linear or branched alkoxy residue, a substituted linear or branched polyoxyalkyl residue, a substituted (meth)acryloyl residue, a substituted alkyl ester residue, a substituted aromatic ester residue, a substituted alicyclic hydrocarbon residue, a substituted aromatic hydrocarbon residue, a substituted aromatic heterocyclic residue, and a substituted amino residue. [9] The aforementioned R 2 A carbon dioxide adsorbent described in any of [1] to [8], wherein is a hydrogen atom.

[10] The carbon dioxide adsorbent according to any one of [1] to [9], wherein the content of the amine (A) is 5 to 70% by mass.

[11] A method for separating or recovering carbon dioxide, The method includes a first step of bringing the gas to be treated into contact with a carbon dioxide adsorbent described in any one of claims 1 to 10 to absorb carbon dioxide, and a second step of decarbonizing the carbon dioxide from the carbon dioxide adsorbent that absorbed carbon dioxide in the first step, A method for separating or recovering carbon dioxide, wherein the second step includes one or more of the following steps: (a) placing the carbon dioxide adsorbent under reduced pressure conditions to remove carbon dioxide; (b) contacting the carbon dioxide adsorbent with at least one of water vapor and an inert gas to remove carbon dioxide; and (c) heating the carbon dioxide adsorbent to remove carbon dioxide. [Effects of the Invention]

[0018] According to this disclosure, it is possible to provide a carbon dioxide adsorbent and a carbon dioxide separation and recovery method that have high carbon dioxide absorption capacity and high carbon dioxide release capacity at low temperatures, high resistance to heat and oxygen and less degradation during the absorption and release process, enabling carbon dioxide separation and recovery with low energy consumption as a whole system. [Modes for carrying out the invention]

[0019] The following describes carbon dioxide adsorbents and methods for separating and recovering carbon dioxide. In this disclosure, unless otherwise specified, the "~" indicating a numerical range includes the numbers written before and after it as the lower and upper limits. When there are multiple identical symbols in a chemical formula, unless otherwise specified, such identical symbols are not limited to representing the same substituent, but may represent substituents that are different from each other within the range defined by the symbol. In this specification, "carbon dioxide adsorbent" may be referred to as "adsorbent."

[0020] [Carbon dioxide adsorbent] The carbon dioxide adsorbent according to this embodiment includes an amine (A) represented by formula (11), which will be described later, and a support. This adsorbent has amine (A) supported on the surface of the support. The (-CHOHCH2) of amine (A)n1 A 1 The portion (more specifically, the -OH group) is more likely to be positioned on the surface side of the support, and as a result, the carbon dioxide adsorption portion NR 1 R 2 It is presumed that this adsorbent is more likely to be placed on the gas side to be treated. n1 A 1 The adsorption of this portion onto the support surface makes it possible to suppress the desorption of amine (A) during heating. Furthermore, the (-CHOHCH2) n1 A 1 A portion of the molecule exhibits intramolecular or intermolecular interactions with amino groups, which can suppress side reactions such as oxidation, and improves the resistance of the carbon dioxide adsorbent to heat and oxygen. 1 R 2 By placing it on the side of the gas to be treated, carbon dioxide and NR 1 R 2 The contact efficiency with the material is increased, improving the amount of carbon dioxide adsorbed, and carbon dioxide is efficiently desorbed by heating at a relatively low temperature of around 70°C. Based on these findings, the carbon dioxide adsorbent of this embodiment exhibits minimal degradation and excellent reusability. Furthermore, using the carbon dioxide adsorbent of this embodiment enables carbon dioxide separation and recovery with low energy consumption across the entire system. The following describes the components of the carbon dioxide absorbent.

[0021] <Amine (A)> Amine (A) is a compound represented by formula (11) above.

[0022] [ka] In the formula, R 1 This is a hydrogen atom, an optionally substituted alkyl group, an optionally substituted heterocyclic group, or an optionally substituted cycloalkyl group. R 2 This is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. A 1This is an n1-valent organic residue whose terminal is an oxygen or nitrogen atom. n1 represents an integer between 2 and 12.

[0023] R 2 The C1-C8 alkyl groups in this context can be linear or branched alkyl groups. Specific examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, neopentyl, n-hexyl, n-octyl, and 2-ethylhexyl groups. 2 Among these, hydrogen atoms or alkyl groups having 1 to 4 carbon atoms are preferred, hydrogen atoms, methyl groups, or ethyl groups are more preferred, and hydrogen atoms or methyl groups are even more preferred.

[0024] R 1 Examples of substituents in "alkyl groups that may have substituents," "heterocyclic groups that may have substituents," and "cycloalkyl groups that may have substituents" include halogen atoms, linear or branched alkyl groups, alkylene groups, cycloalkyl groups, alkoxy groups, cyano groups, trifluoromethyl groups, nitro groups, hydroxyl groups, carbamoyl groups, N-substituted carbamoyl groups, sulfamoyl groups, N-substituted sulfamoyl groups, carboxyl groups, sulfo groups, amino groups, imino groups, nitrogen atoms, oxygen atoms, phenyl groups, sulfanyl groups, etc., and the substituents may have further substituents, and examples of substituents include the substituents listed above.

[0025] Examples of alkyl groups that may have substituents include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, neopentyl, n-hexyl, n-octyl, stearyl, and 2-ethylhexyl groups.

[0026] "Substitutable alkyl groups" include, for example, trichloromethyl group, trifluoromethyl group, 2,2,2-trifluoroethyl group, 2,2-dibromoethyl group, 2,2,3,3-tetrafluoropropyl group; 2-ethoxyethyl group, 2-butoxyethyl group; 2-nitropropyl group; benzyl group, 4-methylbenzyl group, 4-tert-butylbenzyl group, 4-methoxybenzyl group, 4-nitrobenzyl group, 2,4-dichlorobenzyl group; methylsulfanyl group, ethylsulfanyl group, propyl Sulfanyl group, butylsulfanyl group, pentylsulfanyl group, hexylsulfanyl group, octylsulfanyl group, decylsulfanyl group, dodecylsulfanyl group, octadecylsulfanyl group, methoxyethylsulfanyl group, aminoethylsulfanyl group, benzylaminoethylsulfanyl group, methylcarbonylaminoethylsulfanyl group, phenylcarbonylaminoethylsulfanyl group; sulfanylmethyl group, 2-sulfanylethyl group, 1-sulfanylethyl group;Aminomethyl group, aminoethyl group, N-methylaminoethyl group, N-ethylaminoethyl group, N-(aminoethyl)aminoethyl group, N-(hydroxyethyl)aminoethyl group, N-propylaminoethyl group, N-isopropylaminoethyl group, N-butylaminoethyl group, aminopropyl group, N-methylaminopropyl group, N-ethylaminopropyl group, N-propylaminopropyl group, N-(aminopropyl)aminopropyl group, N-isopropylaminopropyl group, N-butylaminopropyl group, aminobutyl group, aminopentyl group, aminohexyl group, aminooctyl group, aminodecyl group, aminododecyl group, aminooctadecyl group, aminoethoxymethyl group, aminoethylaminoethyl group, aminoethyl(methyl)aminoethyl group, aminopropylaminopropyl group, aminopropyl(methyl)aminopropyl group, dibutylaminopropyl group, di(aminoethyl)aminoethyl group, di(A Examples include the aminoethyl(aminoethylpropyl) group, aminopropylaminobutylaminopropyl group, aminopropylaminoethylaminopropyl group, aminoethylaminopropylaminoethyl group, aminoethylaminoethylaminoethyl group, aminopropylaminoethylaminoethyl group, aminoethylaminoethylaminoethylaminoethyl group, aminoethylaminoethylaminoethylaminoethylaminoethyl group, aminoethylaminomethylphenyl group, aminoethylaminocarbonylmethyl group, aminoethylaminocarbonylphenyl group; hydroxymethyl group, 2-hydroxyethyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 4-hydroxybutyl group; cyclopropylmethyl group, cyclobutylmethyl group, cyclopentylmethyl group, cyclohexylmethyl group, cyclopentylethyl group, cyclopentylpropyl group, cyclohexylpropyl group, etc.

[0027] The "alkyl group having a substituent" is preferably aminoethyl group, N-methylaminoethyl group, N-ethylaminoethyl group, N-(aminoethyl)aminoethyl group, N-propylaminoethyl group, N-isopropylaminoethyl group, N-butylaminoethyl group, aminopropyl group, N-methylaminopropyl group, N-ethylaminopropyl group, N-propylaminopropyl group, N-(aminopropyl)aminopropyl group, N-isopropylaminopropyl group, N-butylaminopropyl group, or aminobutyl group. More preferably, the group is aminoethyl(methyl)aminoethyl group, aminopropylaminopropyl group, aminopropyl(methyl)aminopropyl group, dibutylaminopropyl group, di(aminoethyl)aminoethyl group, di(aminoethyl)aminoethylpropyl group, aminopropylaminobutylaminopropyl group, aminopropylaminoethylaminopropyl group, aminoethylaminopropylaminoethyl group, aminoethylaminoethylaminoethyl group, aminoethylaminoethylaminoethyl group, aminopropylaminoethylaminoethylaminoethyl group, aminoethylaminoethylaminoethylaminoethylaminoethyl group.

[0028] Examples of heterocyclic groups that may have substituents include 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrolyl group, 3-pyrolyl group, 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 2-imidazolyl group, 2-oxazolyl group, 2-thiazolyl group, piperidino group, 4-piperidyl group, morpholino group, 2-morpholinyl group, N-indolyl group, 2-indolyl group, 2-benzofuryl group, 2-benzothienyl group, 2-quinolino group, and N-carbazolyl group.

[0029] Examples of cyclic alkyl groups that may have substituents include cyclopropyl group, methylcyclopropyl group, cyclobutyl group, cyclopentyl group, methylcyclopentyl group, ethylcyclopentyl group, cyclohexyl group, methylcyclohexyl group, ethylcyclohexyl group, and propylcyclohexyl group.

[0030] In terms of achieving both carbon dioxide adsorption and carbon dioxide release ability at low temperatures, R 1 It is preferable that it contains nitrogen atoms, more preferably two or more nitrogen atoms, and even more preferably three or more nitrogen atoms.

[0031] Also, R 1 It is preferable that the group is represented by the following general formulas (2) and (3). The asterisk (*) in the formulas indicates the bond position with N in formula (1).

[0032] [ka]

[0033] In formula (2), R 3 is a hydrogen atom or a methyl group, and p is an integer from 0 to 4. From the viewpoint of carbon dioxide adsorption and low-temperature release, R 3 Hydrogen atoms are preferred. Furthermore, from the viewpoint of carbon dioxide adsorption, low-temperature release, and ease of synthesis, p is preferably 1 to 4, and more preferably 2 to 3.

[0034] In formula (3), R 4 and R 6 Each of these is independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a hydroxyalkyl group, and R 5 This is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group, or -(CH2)sR 7 And R 7 is a hydroxyl group, or -N(R 8 )R 9 And R 8 and R 9 Each is independently a hydrogen atom, a methyl group, or a hydroxyalkyl group, q is 2 or 3, r is 2 to 4, s is 2 or 3, and m is 0 to 2. From the viewpoint of carbon dioxide adsorption and low-temperature release, R 4 and R 5 A hydrogen atom is preferred for q, and q is preferably 3.

[0035] R 4 ~R 6 Examples of C1-C8 alkyl groups in include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, hexyl, and octyl groups. From the viewpoint of carbon dioxide adsorption and low-temperature release, R 4 ~R 6 The alkyl group is preferably a C1-C4 alkyl group, and among these, a methyl group or an ethyl group is preferred.

[0036] R 4 ~R 6 , R 8 and R 9 In the hydroxyalkyl group, the number of carbon atoms in the alkyl group is preferably 1 to 8, and more preferably 1 to 4, from the viewpoint of carbon dioxide adsorption and low-temperature release. Specific examples of hydroxyalkyl groups include hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, and hydroxybutyl group.

[0037] From the standpoint of carbon dioxide adsorption and low-temperature release, R 1 The group is preferably represented by general formula (3). R 1 Specific examples will be shown later in the section on amine (A).

[0038] A in equation (11) above 1 This is an n1-valent organic residue whose terminal (i.e., the element at the bonding site) is either an oxygen atom or a nitrogen atom.

[0039] A 1 As such, a group represented by formula (12) or formula (13) below is preferred from the viewpoint of the ease of synthesis of amine (A). [(*-) n2 X 1 -] n A (12)

[0040] [ka] In the formula, X 1is an oxygen atom or a nitrogen atom, n2 is X 1 If it is an oxygen atom, it is 1, and X 1 If it is a nitrogen atom, it is 2. A is an n-valent organic residue, n represents an integer between 2 and 6. * indicates the connection position.

[0041] X in equation (12) 1 is A 1 It represents the terminal end and is either an oxygen atom or a nitrogen atom. n2 is X 1 The number of bonds of X is shown, 1 If it is an oxygen atom, it is 1, and X 1 If it's a nitrogen atom, the answer is 2. In equation (12), the sum of multiple n² is A 1 The valence of becomes n1.

[0042] A represents an n-valent organic residue. Preferably, the n-valent organic residue has one or more carbon atoms. Preferred specific examples of n-valent organic residues include: a linear or branched hydrocarbon residue that may have n-valent substituents, a linear or branched alkoxy residue that may have n-valent substituents, a (meth)acryloyl residue that may have n-valent substituents, a linear or branched polyoxyalkyl residue that may have n-valent substituents, an alkyl ester residue that may have n-valent substituents, an aromatic ester residue that may have n-valent substituents, an alicyclic hydrocarbon residue that may have n-valent substituents, an aromatic heterocyclic residue that may have n-valent substituents, or an amino residue that may have n-valent substituents, where an oxygen atom may be present between adjacent carbon atoms. Furthermore, n represents an integer from 2 to 6.

[0043] Examples of "linear or branched hydrocarbons" in linear or branched hydrocarbon residues that may have n-valent substituents include alkyl groups, alkenyl groups, and alkynyl groups.

[0044] Specific alkyl groups include alkyl groups with 1 to 18 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tetradecyl, pentadecyl, and octadecyl groups.

[0045] Furthermore, examples of alkenyl groups include alkenyls having 2 to 18 carbon atoms, such as vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-octenyl group, 1-decenyl group, and 1-octadecenyl group.

[0046] Examples of alkynyl groups include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-octynyl, 1-decinyl, and 1-octadecinyl groups, which have 2 to 18 carbon atoms.

[0047] Examples of alkoxy groups in linear or branched alkoxy residues that may have n-valent substituents include methoxy groups and ethoxy groups.

[0048] Examples of the (meth)acryloyl group of the (meth)acryloyl residue, which may have an n-valent substituent, include the methacrylic group and the acryloyl group.

[0049] Examples of polyoxyalkyl groups of linear or branched polyoxyalkyl residues that may have n-valent substituents include polyethylene oxide groups with 4 to 16 repeats and linear or branched polypropylene oxide groups with 4 to 16 repeats. Preferred substituents include alkyl groups, phenyl groups, and hydroxyl groups.

[0050] Examples of alkyl ester groups of alkyl ester residues that may have n-valent substituents include methyl ester group, ethyl ester group, propyl ester group, butyl ester group, pentyl ester group, heptyl ester group, hexyl ester group, octyl ester group, hexadecyl ester group, cyclohexyl ester group, 1,2-cyclohexanediester group, and 1,2-cyclohexenediester group.

[0051] Examples of aromatic ester groups in aromatic ester residues that may have n-valent substituents include phenyl ester groups and 4-tert-butylphenyl ester groups.

[0052] Examples of alicyclic hydrocarbon groups in alicyclic hydrocarbon residues that may have n-valent substituents include cycloalkyl groups, specifically cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclooctadecyl, and 2-indeno groups, which are cycloalkyl groups having 3 to 18 carbon atoms. In addition, alicyclic hydrocarbon groups also include groups in which multiple cycloalkyl groups are linked by alkylene groups or the like.

[0053] Aromatic hydrocarbons of the aromatic hydrocarbon residue, which may have n-valent substituents, include aromatic hydrocarbons with condensation numbers 1 to 4. Specifically, examples include benzene, biphenyl, naphthalene, anthracene, phenanthrene, tetracene, pyrene, 9,9-diphenylfluorene, bis(3-methylphenyl)fluorene, and binaphthyl. Preferably, substituents are alkyl groups, alkylene groups, and halogen atoms, and particularly preferably methyl groups, methylene groups, tert-butylene groups, and bromine atoms.

[0054] The aromatic heterocycle of the aromatic heterocycle residue, which may have an n-valent substituent, is an aromatic heterocycle with condensation numbers 1 to 4, and examples include pyrrole, imidazole, pyridine, triazine, indole, quinoline, carbazole, and phthalimide.

[0055] An example of an amino group in an amino residue that may have an n-valent substituent is the aniline group.

[0056] In an n-valent organic residue, examples of substituents include linear or branched alkyl groups, alkoxy groups, polyoxyalkyl groups, phenyl groups, 4-nitrophenyl groups, 2-methoxyphenyl groups, hydroxyl groups, halogen atoms, epoxy groups, etc., and these substituents may have further substituents.

[0057] The specific alkyl group used as a substituent is synonymous with the alkyl group of a linear or branched hydrocarbon residue that may have an n-valent substituent, as mentioned above.

[0058] Specific examples of alkoxy groups used as substituents include methoxy groups and ethoxy groups.

[0059] Specific examples of polyoxyalkyl groups used as substituents include polyethylene oxide groups with 4 to 16 repeats, and linear or branched polypropylene oxide groups with 4 to 16 repeats.

[0060] Specific halogen atoms that can be used as substituents include chlorine, bromine, and iodine atoms.

[0061] A is preferably a linear or branched hydrocarbon residue which may have an n-valent substituent, or an aromatic hydrocarbon residue which may have an n-valent substituent. More preferably, A is a linear or branched hydrocarbon residue which may have an n-valent substituent, and particularly preferably, A is an n-valent linear hydrocarbon residue. From the viewpoint of CO2 recovery, it is preferable that the partial molecular weight of group A is small, and that it may have -O- between carbon atoms and may have a hydroxyl group as a substituent. A linear or branched aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferred, and a linear or branched aliphatic hydrocarbon group having 1 to 6 carbon atoms is preferred. From the perspective of heat resistance and the like, it is preferable that the group A has a ring structure selected from an alicyclic ring and an aromatic ring. There may be one or more rings in the group A, and 1 to 3 rings are more preferable. A 1 Specific examples of 1 include groups represented by the following formula. Note that * indicates the bonding position.

[0062]

Chemical formula

[0063] The amine (A) has a high ability to release carbon dioxide at low temperatures and high resistance to heat and oxygen. Among them, the compound represented by the following formula (1) is preferable.

[0064]

Chemical formula

[0065] R 1 and R 2 , A and n are as described above. In addition, the alkyl group having 1 to 8 carbon atoms in R 11 is the same as the above-mentioned R 2 .

[0066] Table 1 shows amines (A-1) to (A-208) which are representative examples of the amine (A) in this embodiment, but this embodiment is not limited to this representative example.

[0067]

Table 1-1

[0068] Table 1-2

[0069] Table 1-3

[0070] Table 1-4

[0071] Table 1-5

[0072] Table 1-6

[0073] Table 1-7

[0074] Table 1-8

[0075] Table 1-9

[0076] Table 1-10

[0077] Table 1-11

[0078] [Table 1-12]

[0079] [Table 1-13]

[0080] [Table 1-14]

[0081] [Table 1-15]

[0082] [Table 1-16]

[0083] [Table 1-17]

[0084] Amine (A) can be obtained, for example, by reacting the following amine (B) with the following polyfunctional epoxy compound (C) in a suitable solvent.

[0085] Examples of the aforementioned solvents include water, alkanols (e.g., methanol, ethanol, propanol, butanol, etc.), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0086] It is preferable to carry out the reaction when the total equivalent weight of the primary and secondary amino groups of amine (B) is in the range of 0.95 to 1.1 relative to the epoxy equivalent weight of polyfunctional epoxy compound (C). Furthermore, amine (B) and polyfunctional epoxy compound (C) may be used individually or in combination of several different types.

[0087] The polyfunctional epoxy compound (C) used in this embodiment will now be described. A polyfunctional epoxy compound is a compound having two or more epoxy groups in one molecule.

[0088] The polyfunctional epoxy compound can be any compound commonly used in epoxy resin compositions, and its type is not particularly limited as long as it has two or more epoxy groups in one molecule.

[0089] Polyfunctional epoxy compounds include polyfunctional aliphatic epoxy compounds and polyfunctional aromatic epoxy compounds.

[0090] As the polyfunctional aliphatic epoxy compound, a cyclic structure may be used, and either synthesized or commercially available compounds may be used.

[0091] Examples of polyfunctional aliphatic epoxy compounds include difunctional aliphatic epoxy compounds having two epoxy groups in their molecule, such as alkylene glycol diglycidyl ether, alkenylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane diglycidyl ether, and 1,4-cyclohexanedimethanol diglycidyl ether; Examples include polyglycidyl ethers of trifunctional or more alcohols such as trimethylolpropane, pentaerythritol, and dipentaerythritol [trimethylolpropane polyglycidyl ether such as trimethylolpropane triglycidyl ether, trimethylolpropane triglycidyl ether, or a mixture of trimethylolpropane diglycidyl ether and trimethylolpropane triglycidyl ether (e.g., Denacol EX-321L: manufactured by Nagase Chemitex), pentaerythritol triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol heptaglycidyl ether, sorbitol hexaglycidyl ether, resorcinol diglycidyl ether, pentaerythritol (tri, or tetra)glycidyl ether, dipentaerythritol (tri, tetra, penta, or hexa)glycidyl ether, etc.], which have three or more epoxy groups in their molecule.

[0092] Commercially available polyfunctional aliphatic epoxy compounds can be used, such as "EP-4088S" (manufactured by ADEKA Corporation), "EHPE3150" (manufactured by Daicel Corporation), "EX-211L" and "EX-212L" (both manufactured by Nagase ChemteX Corporation), and "Showfree CDMDG" (manufactured by Resonac Corporation).

[0093] Examples of polyfunctional aromatic epoxy compounds include polyhydric phenols having at least one aromatic ring, such as bisphenol A and bisphenol F, or polyglycidyl ethers of their alkylene oxide adducts; Epoxy novolac resin; Polyglycidyl ethers of aromatic compounds having two or more phenolic hydroxyl groups, such as resorcinol, hydroquinone, and catechol; Polyglycidyl ethers of aromatic compounds having two or more alcoholic hydroxyl groups, such as phenyldimethanol, phenyldiethanol, and phenyldibutanol; Polyglycidyl esters of polybasic acid aromatic compounds having two or more carboxylic acids, such as phthalic acid, terephthalic acid, and trimellitic acid; Examples include divinylbenzene diepoxy compounds.

[0094] The polyfunctional aromatic epoxy compound may be synthesized or commercially available.

[0095] Polyfunctional aromatic epoxy compounds can be commercially available, such as "Denacol EX-201," "Denacol EX-711," and "Denacol EX-721" (all manufactured by Nagase ChemteX Corporation); "Ogusol EG-280" and "Ogusol CG-400" (both manufactured by Osaka Gas Chemical Co., Ltd.); "EXA-80CRP" and "HP4032D" (both manufactured by DIC Corporation); “jER828” and “jER828EL” (both manufactured by Mitsubishi Chemical Corporation); Examples include "Adeka Resin EP-4100", "Adeka Resin EP-4100G", "Adeka Resin EP-4100E", "Adeka Resin EP-4100L", "Adeka Resin EP-4100TX", "Adeka Resin EP-4000", "Adeka Resin EP-4005", "Adeka Resin EP-4901", and "Adeka Resin EP-4901E" (all manufactured by ADEKA Corporation).

[0096] As specific examples of amines (B), the structures of amines (B-1) to (B-46) are shown in Tables 2-1 to 2-2.

[0097] [Table 2-1]

[0098] [Table 2-2]

[0099] The structures of specific polyfunctional epoxy compounds (C-1) to (C-34) are shown in Tables 3-1 to 3-3.

[0100] [Table 3-1]

[0101] [Table 3-2]

[0102] [Table 3-3]

[0103] <Support> The support is a solid material that supports compound (A) represented by general formula (1), and can be any material that can withstand the conditions for carbon dioxide separation and recovery. For example, ceramics, porous materials, carbon materials, and resin materials can be used. Specifically, examples include silica, silica-alumina, alumina, zeolite, zeolite-related compounds, magnesia, titanium dioxide, calcium silicate, carbon nanotubes, activated carbon, polymethyl methacrylate, zirconia, natural minerals, waste solids, and carbon molecular sieves. The support may be used alone or in combination of two or more types. Examples of the above-mentioned waste solids include waste containing ceramics, porous materials, carbon materials, and resin materials. The shape of the support can be appropriately selected depending on the application of the carbon dioxide adsorbent, and may be in the form of particles, or it may be a structure with multiple through-holes such as a lattice or honeycomb shape.

[0104] The support may be a commercially available product as it is, or a support synthesized by a known method may be used. Examples of commercially available products include mesostructured silica MSU-F manufactured by Sigma-Aldrich, SIPERNAT® 50S manufactured by Evonik, CARiACT® Q10, Q30, Q50 manufactured by Fuji Silysia Chemical, and Celcor® cordierite support manufactured by Corning.

[0105] In order to carry a large amount of polyamine, a porous material with a large specific surface area and pore volume is preferred for the support. The specific surface area (BET) is preferably 50 m 2 / g or more and 2000 m 2 / g or less, more preferably 100 m 2 / g or more and 1000 m 2 / g or less. The pore volume is preferably 0.1 cm 2 / g or more and 2.3 cm 2 / g or less, more preferably 0.7 cm 2 / g or more and 2.3 cm 2 / g or less.

[0106] The specific surface area and pore volume can be measured, for example, by using a specific surface area and pore size distribution measuring device (BELSORP: manufactured by MicrotracBEL Corporation) using the constant volume method. As a gas adsorption measurement method using a more specific specific surface area and pore size distribution measuring device, for example, the sample is pretreated by heating and vacuum evacuation, and approximately 0.1 g of the measurement sample is weighed into the sample tube. Then, it is heated to 100 °C, vacuum evacuation is performed for 4 hours, then cooled to room temperature, and the sample mass is weighed. In the measurement, the liquid nitrogen temperature is set and the pressure range is specified. The specific surface area, pore volume, and pore diameter can be calculated by analyzing the obtained nitrogen adsorption isotherm.

[0107] <Carbon dioxide adsorbent> The carbon dioxide adsorbent is obtained by supporting the compound (A) represented by the formula (1) on a support. The carbon dioxide adsorbent contains an amine (A) and a support on which it is supported.

[0108] A carbon dioxide adsorbent can be manufactured by a manufacturing method comprising the steps of preparing compound (A) and obtaining the carbon dioxide adsorbent. In the step of obtaining the carbon dioxide adsorbent, compound (A) can be brought into contact with a support to produce a carbon dioxide adsorbent that supports amine (A).

[0109] Amine (A) can be produced, for example, by mixing a support with a solution of amine (A), stirring at room temperature, and then distilling off the solvent (e.g., alcohol). Methods for distilling off the solvent include, for example, heating under reduced pressure using an evaporator.

[0110] The amine (B) and the polyfunctional epoxy compound (C) can be reacted separately to obtain amine (A) after the solvent has been removed. For example, the polyfunctional epoxy compound (C) and amine (B) can be added sequentially to a dispersion of the support while stirring to disperse the amino compound (A) on the support and form an adsorbent. Alternatively, the reaction product of amine (B) and polyfunctional epoxy compound (C) can be added directly to the support suspension while still in the reaction solution.

[0111] Furthermore, if the polyfunctional epoxy compound is in liquid form, it can be used without dissolving it in a solvent.

[0112] The present invention can be applied to pressure swing and temperature swing methods, which are not applicable to liquid carbon dioxide adsorbents, by supporting compound (A) on a support. The pressure swing method includes the step of placing the carbon dioxide adsorbent under reduced pressure conditions to desorb carbon dioxide. The temperature swing method includes the step of heating the carbon dioxide adsorbent to desorb carbon dioxide.

[0113] The carbon dioxide adsorbent may further include a binder for granulating amine(A). That is, the carbon dioxide adsorbent may include amine(A) as a granule with a binder and a support. By granulating amine(A) with a binder, vibration resistance and abrasion resistance can be imparted, and stability in water can be further improved.

[0114] As a binder, at least one selected from the group consisting of silica, alumina, silica-alumina, clay minerals, fluororesins, cellulose derivatives, and epoxy resins may be used. Examples of fluororesins include polytetrafluoroethylene. Examples of cellulose derivatives include hydroxypropyl methylcellulose, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxyethylated starch. Examples of epoxy resins include diglycerol polyglycidyl ether and sorbitol polyglycidyl ether, which may be used as a mixture with an epoxy resin curing agent (modified polyamide resin, etc.). Other polymers (polyvinyl alcohol, polyethylene oxide, sodium polyacrylate, polyacrylamide, etc.) may also be used. These compounds may be used. They are commercially available or can be readily manufactured by known methods. The binder may be used alone or in combination of two or more types.

[0115] As binders, commercially available options include Snowtec 30 and AS-200 from Nissan Chemical Corporation, Polyflon PTFE D-210C from Daikin Industries, Ltd., NEOVISCO MC RM4000 from Sansho Co., Ltd., AQ Nylon P-70 from Toray Industries, Inc., and Denacol EX-421 from Nagase ChemteX Corporation.

[0116] The content of the carbon dioxide adsorbent in the binder is not particularly limited as long as it is in an amount that allows for granulation, but it is preferable that it be in a small amount in order to prevent a decrease in the content of amine compound (A).

[0117] When granulation is performed using a binder, the average particle size of the granules is preferably 0.1 mm to 2.0 mm, from the viewpoint of reducing pressure loss when gas is supplied to the adsorbent-packed bed.

[0118] The content of amine (A) in the carbon dioxide adsorbent is not particularly limited, but from the viewpoint of efficiently separating and recovering carbon dioxide, the content of amine (A) is preferably, for example, 5% by mass or more and 70% by weight or less, based on the total mass of the carbon dioxide adsorbent, and is particularly preferably 20% by mass or more and 70% by weight or less.

[0119] <Methods for separating or recovering carbon dioxide> The carbon dioxide separation (recovery) method processes gases containing carbon dioxide. These gases may include, for example, exhaust gases emitted from thermal power plants that use coal, heavy oil, natural gas, etc. as fuel; blast furnaces in steel mills that reduce iron oxide with coke; converters in steel mills that burn carbon in pig iron to produce steel; boilers in various manufacturing plants; kilns in cement plants; and even exhaust gases emitted from transportation equipment such as automobiles, ships, and aircraft that use gasoline, heavy oil, light oil, etc. These gases may also include carbon dioxide emitted in enclosed spaces such as submersible research vessels, space stations, buildings, and offices, due to human respiration or energy conversion by equipment. They may also be carbon dioxide from the atmosphere.

[0120] The method for separating or recovering carbon dioxide according to this disclosure is characterized by the use of a carbon dioxide adsorbent.

[0121] The carbon dioxide separation (recovery) method includes a first step of bringing the gas to be treated into contact with a carbon dioxide adsorbent to absorb carbon dioxide, and a second step of decarbonizing the carbon dioxide from the carbon dioxide adsorbent that absorbed carbon dioxide in the first step.

[0122] The carbon dioxide content and temperature of the gas to be treated in the first step are not particularly limited, as long as the carbon dioxide adsorbent can withstand the conditions. For example, the partial pressure of carbon dioxide may be 100 kPa or less, and the temperature may be 10°C to 60°C. Specifically, examples include operating conditions expected in thermal power plants (partial pressure of carbon dioxide: 7 to 100 kPa, temperature: 40 to 60°C) and operating conditions expected in space stations (partial pressure of carbon dioxide: 0 to 1 kPa, temperature: 20 to 25°C). The gas to be treated may be at atmospheric pressure or pressurized.

[0123] The gas to be treated in the first step may contain water vapor. Since the carbon dioxide adsorbent has excellent carbon dioxide adsorption properties even when the gas to be treated contains water vapor, the dehumidification operation can be omitted.

[0124] Methods for removing carbon dioxide in the second step include (a) a step of removing carbon dioxide by placing the carbon dioxide adsorbent under reduced pressure conditions (pressure swing method), (b) a step of removing carbon dioxide by contacting the carbon dioxide adsorbent with at least one of water vapor and an inert gas (preferably a gas that does not contain carbon dioxide (or a gas with a low carbon dioxide content)), and (c) a step of removing carbon dioxide by heating the carbon dioxide adsorbent (temperature swing method).

[0125] In the method including step (a), it is preferable to reduce the pressure to about 0.2 Pa in terms of the amount of carbon dioxide desorbed and the stability of the carbon dioxide adsorbent. The carbon dioxide adsorbent or the container containing it may be heated during the depressurization. If heating is performed, the temperature should preferably be up to about 60°C, in which case it is preferable to reduce the pressure to about 0.5 Pa. The method including step (A) is suitable when the gas to be treated has a temperature of 20 to 60°C and a carbon dioxide partial pressure of 100 kPa or less.

[0126] In the method including step (B), for example, carbon dioxide partial pressure can be reduced and carbon dioxide can be desorbed by bringing an inert gas, water vapor, or a gas that does not contain carbon dioxide into contact with the carbon dioxide adsorbent. The gas to be brought into contact with the carbon dioxide adsorbent can be any gas in which the carbon dioxide adsorbent is stable, and inert gases such as argon, nitrogen, and water vapor are preferred, with depressurized water vapor being more preferred.

[0127] In the method including step (C), carbon dioxide can be desorbed by raising the temperature above the temperature at which it was absorbed. In this case, the temperature at which carbon dioxide was absorbed may be, for example, 10 to 40°C, and the temperature at which carbon dioxide was desorbed may be, for example, around 60°C.

[0128] The carbon dioxide adsorbent of this embodiment, amine (A) represented by formula (1), and the support are also excellent at absorbing hydrogen sulfide in addition to carbon dioxide. [Examples]

[0129] The carbon dioxide adsorbent according to this embodiment will be described in more detail below with reference to examples. However, this disclosure is not limited to these examples. The carbon dioxide adsorbent according to the present invention can be easily prepared in two steps.

[0130] Step 1: Preparation of amine (A) [Synthesis Example 1: Amine (A-1)]

[0131] [ka]

[0132] Under a nitrogen atmosphere, 5.0 g (111.0 mmol) of ethylamine (B-1) mixed with 50 ml of methanol and 9.67 g (55.5 mmol) of ethylene glycol diglycidyl ether (C-1) were added and the mixture was stirred. After addition, the mixture was stirred at room temperature for 24 hours, and the reaction was confirmed to have progressed by gas chromatography (GC) when ethylamine (B-1) was not detected. The solvent methanol was removed by reducing the pressure at a temperature below 40°C to obtain the target product, amine (A-1).

[0133] [Synthesis Examples 2-102] In the above Synthesis Example 1, the amine (A) described in Tables 4-1 to 4-3 was synthesized in the same manner as in Synthesis Example 1, except that the starting materials amine (B) and polyfunctional epoxy compound (C) were appropriately replaced with the amines listed in Tables 2-1 to 2-2 and the polyfunctional epoxy compounds listed in Tables 3-1 to 3-3. The symbols of the amine compounds in Tables 4-1 to 4-3 correspond to those listed in Tables 1-1 to 1-17.

[0134] [Synthesis Example 103: Compound of Comparative Example 5] (Modified form of pentaethylenehexamine and monofunctional epoxy compound) 10 g of pentaethylenehexamine (0.043 mol) was dissolved in 40 ml of water. 5 g of propylene oxide (0.086 mol) was taken out and added dropwise to the pentaethylenehexamine solution. The mixture was stirred at room temperature for 20 hours. Then, the temperature was raised to 60°C and maintained at that temperature for 2 hours. The water was removed using a rotary evaporator, and the mixture was then subjected to vacuum (<1 mmHg) overnight to obtain the target product.

[0135] [Synthesis Example 104: Compound of Comparative Example 6] (Modified polyethyleneimine and monofunctional epoxy compound) 10 g of polyethyleneimine (PEI:MW800, Aldrich) (0.013 mol) was dissolved in 40 ml of water. 1.03 g (0.0065 mol) of hexaethyl glycidyl ether was taken out and added dropwise to the polyethyleneimine solution. The mixture was stirred at room temperature for 20 hours. Then the temperature was raised to 60°C and maintained at that temperature for 2 hours. The water was removed using a rotary evaporator, and the mixture was then subjected to vacuum (<1 mmHg) overnight to obtain the target product.

[0136] [Synthesis Example 105: Compound of Comparative Example 7] (Modified form of triethylenetetramine and a difunctional epoxy compound) 7.6 g (0.052 mol) of triethylenetetramine (TETA, manufactured by Sigma-Aldrich) was dissolved in 60 ml of methanol. Next, 0.60 g (0.0042 mol) of 1,7-octadiene diepoxide (ODE, manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.15 g (0.0004 mol) of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) were prepared as epoxy monomers and added dropwise to the triethylenetetramine solution. These mixtures were stirred at room temperature for 20 hours. Then, the temperature was raised to 50°C and maintained at that temperature for 2 hours. Methanol was removed using a rotary evaporator, and the mixture was then subjected to vacuum (<1 mmHg) overnight to obtain the target product.

[0137] Step 2: Preparation of carbon dioxide adsorbent [Example 1: Adsorbent (1)] Adsorbent (1), consisting of 30% by mass of amine (A-1) and 70% by mass of silica gel as a support, was prepared as follows. 3.0 g of (A-1) obtained in Synthesis Example 1 was weighed and dissolved in 20.0 g of methanol solution weighed into a 200 ml flask. Then, 7.0 g of silica gel Q50 (CARiACT Q50 manufactured by Fuji Silysia Chemical Co., Ltd.: specific surface area 80 m²), which was the support material, was weighed out and dissolved in it. 2(A-1) was placed in a round-bottom flask and stirred at room temperature for 2 hours. Then, the methanol solvent was removed by heating it to 40°C in a rotary evaporator while reducing the pressure in the system to 0.03 MPa. Subsequently, it was vacuum-dried overnight at a vacuum degree of <1 mmHg and a temperature of 60°C to obtain adsorbent (1) containing 30% by mass of (A-1).

[0138] [Examples 2-113, Comparative Examples 1-7] Carbon dioxide adsorbents (2) to (120) were prepared in the same manner as in Example 1, except that the amine compound and support were changed to the combinations listed in Tables 4-1 to 4-3.

[0139] [Table 4-1]

[0140] [Table 4-2]

[0141] [Table 4-3]

[0142] [Materials used for evaluation] To simplify notation, the following abbreviations were used. PEI: Polyethyleneimine (Mw=600) Q10: Silica gel (CARiACT Q10 manufactured by Fuji Silicia Chemical Co., Ltd., specific surface area 300 m²) 2 ( / g, pore volume 1.0 ml / g) Q30: Silica gel (CARiACT Q30 manufactured by Fuji Silicia Chemical Co., Ltd., specific surface area 100 m²) 2 ( / g, pore volume 1.0 ml / g) Q50: Silica gel (CARiACT Q50 manufactured by Fuji Silicia Chemical Co., Ltd., specific surface area 80 m²) 2 ( / g, pore volume 1.0 ml / g) Celcor: Cordillerine carrier (Celcor manufactured by Corning, total volume: 0.0303L (diameter 24mm, length 67mm, cylindrical), number of cells: 400 cells per square inch of cross-sectional area)

[0143] [Method for measuring carbon dioxide gas absorption and release] 1.5 g of the adsorbent (1) prepared in Example 1 was filled into a temperature-controllable, gas-permeable glass cell, and the cell was evacuated at 100°C for 30 minutes with a vacuum pump at approximately 0.8 kPa to desorb carbon dioxide and water present in the adsorbent. After this pretreatment, the glass cell was placed in a water bath maintained at a constant temperature of 25°C, and adsorption measurements were performed. For absorption measurements, a carbon dioxide concentration meter equipped with an IR detector (consisting of a carbon dioxide concentration sensor (VAISALA, (GMP252)) and an indicator (VAISALA, (M-170))) was placed at the inlet and outlet of the glass cell, respectively. Compressed air (CO2: 400 ppm) was flow-controlled using a mass flow controller and the gas flow rate (6 L / min) was passed through the glass cell as a simulated gas. Immediately, the carbon dioxide concentration at the gas outlet decreased to less than 10 ppm, suggesting that carbon dioxide was essentially completely adsorbed from the air. Subsequently, the carbon dioxide concentration was recorded as a function of time using the carbon dioxide concentration meter. Initially, the carbon dioxide concentration was close to 0 ppm, and then the carbon dioxide concentration at the outlet began to increase. Measurements were taken until the carbon dioxide concentration at the outlet reached a value close to the concentration reading on the carbon dioxide concentration meter at the inlet (until adsorption saturated). The total adsorption amount was calculated as the amount of carbon dioxide adsorbed per gram of carbon dioxide adsorbent (mmol·g) over the time until adsorption saturated.

[0144] Next, while operating a vacuum pump (100 kPa) installed outside the carbon dioxide concentration meter on the outlet side, the water bath containing the adsorbent was heated until the temperature of the glass cell reached 70°C, and carbon dioxide was desorbed from the adsorbent while flowing nitrogen gas at 10 ml / min. The carbon dioxide concentration was recorded as a function of time using the carbon dioxide concentration meter. The carbon dioxide concentration increased to a value exceeding 10,000 ppm due to heating, and then measurements were taken until the carbon dioxide concentrations at the cell outlet and inlet asymptotically approached each other. From the obtained results, the total release amount was calculated as the amount of carbon dioxide adsorbed per gram of carbon dioxide adsorbent (mmol·g) during the time until asymptotic approaches were reached.

[0145] [Measurement of carbon dioxide gas absorption and release] The carbon dioxide absorption and release amounts were measured using the method described above. For adsorbent (1) in Example 1, the amount of carbon dioxide absorbed per unit weight of the adsorbent per hour was 1.23 mmol·g. On the other hand, the amount of carbon dioxide released per unit weight of the adsorbent per hour was 1.22 mmol·g. The results of similar measurements for adsorbents (2) to (120) are shown in Tables 4-1 to 4-4.

[0146] Based on the calculated carbon dioxide gas adsorption amount, the following criteria were established for evaluation, and S, A, and B were designated as usable ranges. S: Adsorption amount is 1.3 mmol / g or more A: Adsorption amount is 1.0 mmol / g or more and less than 1.3 mmol / g B: Adsorption amount is 0.7 mmol / g or more and less than 1.0 mmol / g C: Adsorption amount is less than 0.7 mmol / g

[0147] Based on the calculated desorption rate of carbon dioxide gas, the following criteria were established and evaluated, with S, A, and B being designated as the usable range. S: Desorption amount is 1.3 mmol / g or more A: Desorption amount is 1.0 mmol / g or more and less than 1.3 mmol / g B: Desorption amount is 0.7 mmol / g or more and less than 1.0 mmol / g C: Desorption amount is less than 0.7 mmol / g

[0148] [Method for evaluating the adsorption rate of carbon dioxide gas] The adsorption rate was evaluated using the adsorbents listed in Tables 4-1 to 4-3. Similar to the method for measuring the amount of carbon dioxide gas adsorbed described above, the adsorbents were filled into temperature-controllable, gas-permeable glass cells, and the cells were evacuated at 100°C for 30 minutes using a vacuum pump at approximately 0.8 kPa to desorb the carbon dioxide and water present in the adsorbent. After this pretreatment, the glass cells were placed in a water bath maintained at a constant temperature of 25°C, and compressed air (CO2: 400 ppm) was flowed into the glass cells at a flow rate of 6 L / min using a mass flow controller, with the flow rate controlled by the mass flow controller. The amount of carbon dioxide gas adsorbed at this time (amount of carbon dioxide adsorbed in 10 minutes (mmol / g)) was measured using a gas flow meter and a carbon dioxide concentration meter. The absorption rate (g / L / min) was defined as the value obtained by dividing this adsorption amount by 10.

[0149] The evaluation criteria were as follows, with S, A, and B being considered as the usable range. S: Adsorption rate of 0.10 mmol / g / min or higher A: Adsorption rate of 0.07 mmol / g / min or more and less than 0.10 mmol / g / min B: Adsorption rate of 0.03 mmol / g / min or more and less than 0.07 mmol / g / min C: Adsorption rate less than 0.03 mmol / g / min

[0150] [Thermal oxidation resistance] For the samples in Examples 1-113 and Comparative Examples 1-7, where the absorption and release of carbon dioxide gas was measured, the adsorbent was left in a hot air oven at 70°C for 24 hours in an air environment. Then, the same sample was used again, and an absorption and release test was performed in the same manner as described above, measuring the amount of CO2 absorbed after exposure to an air-heated environment. The thermal oxidation resistance of the adsorbent was evaluated from the results using the following formula. (formula) Thermal oxidation resistance = Amount of CO2 absorbed by the adsorbent after exposure to air / heated environment ÷ Amount of CO2 absorbed by the adsorbent before exposure to air / heated environment The evaluation results are shown in Tables 4-1 to 4-3.

[0151] Based on the above resistance results, the following criteria were established and evaluated, with S, AA, A, and B being designated as the usable range. The evaluation results are shown in Tables 4-1 to 4-3.

[0152] S: Thermal oxidation resistance of 0.90 or higher AA: Thermal oxidation resistance between 0.80 and 0.90 A: Thermal oxidation resistance is between 0.70 and 0.80. B: Thermal oxidation resistance is between 0.50 and 0.70. C: Thermal oxidation resistance is less than 0.50

[0153] As described in the above examples, the carbon dioxide adsorbent of the present invention exhibits superior carbon dioxide absorption and release rates, as well as excellent thermal oxidation resistance, compared to conventionally known carbon dioxide adsorbents. Furthermore, it was found to possess thermal oxidation resistance to the generally known PEI (polyethyleneimine). One possibility is that the amine compound (A) of the present invention, consisting of a polyfunctional epoxy and an amine, reacts to form a structure with multiple ether bonds and hydroxyl groups within the molecule, exhibiting high affinity for support materials such as silica, resulting in excellent supported adsorption, and also exhibiting excellent thermal oxidation resistance due to intramolecular / intermolecular interactions through hydrogen bonding with the amino group. As a result, it is presumed that the amine portion can react with carbon dioxide easily and rapidly, leading to high adsorption and desorption rates.

Claims

1. A carbon dioxide adsorbent comprising an amine (A) represented by formula (11) and a support. 【Chemistry 1】 In the formula, R １ This is a hydrogen atom, an optionally substituted alkyl group, an optionally substituted heterocyclic group, or an optionally substituted cycloalkyl group. R ２ This is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. A １ This is an n1-valent organic residue whose terminal is an oxygen or nitrogen atom. n1 represents an integer between 2 and 12.

2. A １ The carbon dioxide adsorbent according to claim 1, which is represented by the following formula (12) or formula (13). [(*-) ｎ２ X １ -] ｎ A (12) 【Chemistry 2】 In the formula, X １ is an oxygen atom or a nitrogen atom, n2 is X １ is 1 when X １ is a nitrogen atom, and is 2 when X A is an n-valent organic residue, n represents an integer between 2 and 6. * indicates the bonding position.

3. The carbon dioxide adsorbent according to claim 1, wherein the amine (A) is represented by the following formula (1). 【Transformation 3】 In the formula, X is an oxygen atom or -NR １１ - and R １１ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or R １ R ２ N-CH ２ CH(OH)CH ２ - and A is an n-valent organic residue, n represents an integer between 2 and 6.

4. The carbon dioxide adsorbent according to claim 3, wherein X is an oxygen atom.

5. The aforementioned R １ The carbon dioxide adsorbent according to claim 1, wherein the alkyl group which may have substituents, the heterocyclic group which may have substituents, and the cycloalkyl group which may have substituents contain two or more nitrogen atoms.

6. The aforementioned R １ The carbon dioxide adsorbent according to claim 1, wherein is represented by the following formula (2) or (3). 【Chemistry 4】 During the ceremony, R ３ is a hydrogen atom or a methyl group, p is an integer between 0 and 4. R ４ and R ６ Each of these is independently a hydrogen atom, a C1-C8 alkyl group, or a hydroxyalkyl group. R ５ This is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group, or -(CH ２ ) s-R ７ And, R ７ is a hydroxyl group, or -N(R ８ ) R ９ And, R ８ and R ９ Each of these is independently a hydrogen atom, a methyl group, or a hydroxyalkyl group. q is either 2 or 3. r is between 2 and 4. s is 2 or 3, m is between 0 and 3.

7. The carbon dioxide adsorbent according to claim 1, wherein the support is at least one selected from the group consisting of silica, silica alumina, alumina, zeolite, zeolite-related compounds, magnesia, titanium dioxide, calcium silicate, carbon nanotubes, activated carbon, polymethyl methacrylate, zirconia, natural minerals, waste solids, and carbon molecular sieves.

8. The carbon dioxide adsorbent according to claim 1, wherein the organic residue in A is one of the following: a linear or branched aliphatic hydrocarbon residue which may have a substituent; a linear or branched alkoxy residue which may have a substituent; a linear or branched polyoxyalkyl residue which may have a substituent; a (meth)acryloyl residue which may have a substituent; an alkyl ester residue which may have a substituent; an aromatic ester residue which may have a substituent; an alicyclic hydrocarbon residue which may have a substituent; an aromatic heterocyclic residue which may have a substituent; and an amino residue which may have a substituent.

9. The aforementioned R ２ The carbon dioxide adsorbent according to claim 1, wherein is a hydrogen atom.

10. The carbon dioxide adsorbent according to claim 1, wherein the content of the amine (A) is 5 to 70% by mass.

11. A method for separating or recovering carbon dioxide, The method includes a first step of bringing the gas to be treated into contact with a carbon dioxide adsorbent according to any one of claims 1 to 10 to absorb carbon dioxide, and a second step of decarbonizing the carbon dioxide from the carbon dioxide adsorbent that absorbed carbon dioxide in the first step, A method for separating or recovering carbon dioxide, wherein the second step includes one or more of the following steps: (a) placing the carbon dioxide adsorbent under reduced pressure conditions to remove carbon dioxide; (b) contacting the carbon dioxide adsorbent with at least one of water vapor and an inert gas to remove carbon dioxide; and (c) heating the carbon dioxide adsorbent to remove carbon dioxide.

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