Composition and carbon dioxide absorbent

Abstract

The purpose of the present invention is to provide a composition that has excellent storage stability and excellent durability.　Disclosed is a composition which contains a component (A), a component (B), and a component (C) described below. Component (A): a polyalkyleneimine, Component (B): a polyvalent phosphonic acid, Component (C): a quaternary ammonium salt and / or an amine which is different from the component (A) It is preferable that the quaternary ammonium salt is a quaternary ammonium hydroxide and the total number of carbon atoms per molecule is 20 or less. It is preferable that the amine is an amino alcohol and the total number of carbon atoms per molecule is 20 or less.

Description

Composition and carbon dioxide absorbent

[0001] The present invention relates to a composition. The present invention also relates to a carbon dioxide absorbent using the composition.

[0002] In recent years, a technology called DAC (Direct Air Capture) has been considered as a technology for achieving carbon neutrality. This technology involves capturing dilute carbon dioxide in the atmosphere using a carbon dioxide absorbent, thereby increasing the concentration of carbon dioxide within the absorbent. The highly concentrated carbon dioxide can then be desorbed (desorbed) from the absorbent by heating, depressurizing, or the like, allowing the carbon dioxide captured from the atmosphere to be stored underground or used as a raw material for chemicals, etc.

[0003] Various chemicals have been investigated as such carbon dioxide absorbents, and for example, those using polyethyleneimine are known. Furthermore, because such polyethyleneimine is subject to degradation such as decomposition due to stress such as heating, polyethyleneimine to which a specific phosphorus-based chelating agent has been added is known for the purpose of improving durability such as heat resistance (Patent Documents 1 and 2).

[0004] US Patent No. 10,654,025 Korean Patent Publication No. 10-2022-0120278

[0005] However, when the carbon dioxide adsorbent disclosed in Patent Document 1 is used, a composition in which polyethyleneimine and a specific phosphorus-based chelating agent are mixed at a certain concentration or higher has a storage stability problem in that it gels over time.

[0006] Furthermore, when the carbon dioxide adsorbent disclosed in Patent Document 2 is used, its durability against repeated use is still insufficient, and there is room for further improvement in terms of durability.

[0007] Therefore, an object of the present invention is to provide a composition having excellent storage stability and durability. Another object of the present invention is to provide a carbon dioxide absorbent containing the composition.

[0008] As a result of intensive research to achieve the above object, the present inventors have found that a specific composition containing a polyalkyleneimine has excellent storage stability and durability. The present invention was completed based on these findings.

[0009] That is, the present invention provides a composition comprising a polyalkyleneimine as component (A), a polyvalent phosphonic acid as component (B), and a quaternary ammonium salt and / or an amine as component (C), wherein component (C) is a compound different from component (A).

[0010] The quaternary ammonium salt is preferably a quaternary ammonium hydroxide and has a total carbon number of 20 or less per molecule.

[0011] The amine is preferably an amino alcohol having a total of 20 or less carbon atoms per molecule.

[0012] It is preferred that some or all of the phosphonic acid groups in component (B) form a salt with some or all of component (C).

[0013] The total content of the components (B) and (C) is preferably 0.01 to 10% by mass relative to 100% by mass, which is the total amount of the components (A), (B), and (C) in the composition.

[0014] The present invention also provides a carbon dioxide absorbent containing the above composition.

[0015] The carbon dioxide absorbent preferably includes a carrier and the composition supported on the carrier.

[0016] The present invention also provides a method for separating carbon dioxide, which comprises a step of contacting carbon dioxide in a gaseous state with the carbon dioxide absorbent.

[0017] The present invention also provides a method for recovering carbon dioxide, which includes a step of desorbing carbon dioxide from the carbon dioxide absorbent that has absorbed carbon dioxide.

[0018] The composition of the present invention has excellent storage stability and durability.

[0019] [Composition] The composition of the present invention contains at least a polyalkyleneimine (component (A)), a polyvalent phosphonic acid (component (B)), and a quaternary ammonium salt and / or an amine (component (C)). Here, component (C) is a compound different from component (A). The composition contains these components, and therefore has excellent storage stability and durability, and can be suitably used, for example, as a composition for a carbon dioxide absorbent, which will be described later.

[0020] (Component (A): Polyalkyleneimine) The polyalkyleneimine is a compound having a structural unit derived from alkyleneimine. The structural unit derived from alkyleneimine is not particularly limited, but a structural unit derived from an alkyleneimine having 2 to 6 carbon atoms is preferred. Among the above polyalkyleneimines, a compound having an ethyleneimine structural unit (-CH ２ CH ２ Polyethyleneimine (PEI) having a hydroxyl group of 1,2-dimethylamino- ...

[0021] Examples of the polyalkyleneimine include alkyleneimine polymers and polyamine polymers. Examples of the alkyleneimine include alkyleneimines having 2 to 6 carbon atoms, such as aziridine, 2-methylaziridine, azetidine, 1,2-butyleneimine, 2,3-butyleneimine, and 1,1-dimethylethyleneimine. One type of alkyleneimine may be used alone, or two or more types may be used. That is, the polyalkyleneimine may be a homopolymer or copolymer of alkyleneimine.

[0022] Examples of the polyamine include polyamines having 2 to 6 carbon atoms, such as ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. The polyamines may be used singly or in combination. That is, the polyalkyleneimine may be a homopolymer or copolymer of polyamine.

[0023] The polyalkyleneimine undergoes a chemical reaction with carbon dioxide to reversibly form carbamates or bicarbonates, and is therefore capable of absorbing and desorbing (adsorbing and desorbing) carbon dioxide. In this specification, the term "absorption" is used in a sense that includes adsorption, and can also be referred to as sorption.

[0024] From the viewpoints of superior oxidation stability and superior supportability on a carrier due to low volatility, the number average molecular weight (Mn) of the polyalkyleneimine is preferably 300 or more, more preferably 500 or more, and even more preferably 600 or more. Furthermore, from the viewpoints of superior diffusion rate of absorbed carbon dioxide and superior supportability on a carrier due to lower viscosity, the number average molecular weight is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less.

[0025] The number average molecular weight can be measured by a known method using gel permeation chromatography (GPC) with pullulan as a standard substance. The following conditions are used as GPC measurement conditions in the present invention. Measurement apparatus: GPC apparatus (manufactured by Shimadzu Corporation) Columns used: Shodex OHpak SB-807HQ (two columns) + SB-806M / HQ (two columns) manufactured by Resonac Corporation Column temperature: 40°C Eluent: Aqueous solution prepared from 0.5 mol% sodium nitrate and 0.5 mol% acetic acid Flow rate: 0.4 mL / min Sample concentration: 0.5 mass% Sample injection volume: 50 μL Standard substance: Shodex STANDARD P-82 (manufactured by Resonac Corporation) Detector: Differential refractometer (manufactured by Shimadzu Corporation)

[0026] The amine value of the polyalkyleneimine per nonvolatile content is preferably 5 or more, more preferably 10 or more, and even more preferably 15 or more. The amine value is preferably 30 or less, more preferably 27 or less, and even more preferably 25 or less.

[0027] The non-volatile content (resin content) of the polyalkyleneimine can be measured by the Karl Fischer method or the dry weight method. Specific measurement methods are described below. Karl Fischer method: Measurement equipment: Karl Fischer moisture meter; Solvent: 20-30 ml of methanol; Amine neutralizer: 7 ml of acetic acid. Calculation formula: Resin content (wt%) = 100 - V x F / S x 100, where V = KF titer (ml), F = KF titer (mg / ml), and S = sample amount (mg). Dry weight method: Approximately 1 g of sample is placed on an aluminum dish, dried in a hot air circulation dryer at 150 ± 5°C for 1 hour, and then allowed to cool in a desiccator for 10 minutes. Calculation formula: Resin content (wt%) = W / S x 100, where W = remaining weight after drying (g), and S = sample weight before drying (g).

[0028] The amine value per unit nonvolatile content of the polyalkyleneimine is the number of moles (mmol) of amino groups contained in 1 g of the nonvolatile content of the polyalkyleneimine. The amine value can be calculated by potentiometric titration in a methanol solution using a 0.5 mol / L standard solution of p-toluenesulfonic acid.

[0029] The polyalkyleneimine contains at least one of a primary amine, a secondary amine, and a tertiary amine. The molar ratio of the primary amine, the secondary amine, and the tertiary amine in the polyalkyleneimine is preferably 10-60:10-60:10-50, more preferably 20-50:20-55:10-40, and even more preferably 25-45:30-50:20-35.

[0030] The content of primary amines in the polyalkyleneimine is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, and particularly preferably 27 mol% or more, relative to 100 mol% of the total amount of alkyleneimines constituting the polyalkyleneimine, and is preferably 60 mol% or less, more preferably 50 mol% or less, even more preferably 45 mol% or less, and particularly preferably 37 mol% or less.

[0031] The content of secondary amines in the polyalkyleneimine is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to 100 mol% of the total amount of alkyleneimines constituting the polyalkyleneimine, and is preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less.

[0032] The content of tertiary amine in the polyalkyleneimine is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, relative to 100 mol% of the total amount of alkyleneimines constituting the polyalkyleneimine, and is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less.

[0033] The degree of cationization of the polyalkyleneimine is preferably 5 meq / g or more, more preferably 10 meq / g or more, and even more preferably 15 meq / g or more, and is preferably 30 meq / g or less, more preferably 25 meq / g or less, and even more preferably 22 meq / g or less.

[0034] The degree of cationization can be measured using known techniques, but can also be calculated from the measured value of the N content measured by the Kjeldahl method, Method 2 of the Nitrogen Determination Method in the General Testing Methods of the Standards for Cosmetic Ingredients, based on the following formula: The unit of the degree of cationization, meq / g, is the number of milliequivalents of cationic groups per 1 g of polyalkyleneimine. Degree of cationization (meq / g) = (number of moles of cationic units in 1 g of polyalkyleneimine) x 1000 Number of moles of cationic units in 1 g of polyalkyleneimine = (nitrogen content in polyalkyleneimine) / (atomic weight of N)

[0035] The polyalkyleneimine may be linear or may have a branched structure. The branching degree of the polyalkyleneimine is preferably more than 0%, more preferably 1% or more, even more preferably 5% or more, even more preferably 10% or more, and particularly preferably 15% or more. The branching degree is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less.

[0036] The degree of branching of the polyalkyleneimine is １３ From the chart obtained by measuring C-NMR, the intensity ratio between the carbon atoms bonded to tertiary amines and the carbon atoms bonded to secondary amines is determined to calculate the number of tertiary amines, a, and the number of secondary amines, b, and the branching degree can be calculated by applying a and b to the following formula. That is, a linear polyalkyleneimine has no tertiary amines and therefore has a branching degree of 0%. Furthermore, a polyalkyleneimine in which all nitrogen atoms are tertiary amines, i.e., which is maximally branched, has a branching degree of 100%. Branching degree (%) = [a / (a+b)] x 100

[0037] The polyalkyleneimine may be a modified polyalkyleneimine (modified polyalkyleneimine). The modified polyalkyleneimine is a compound having structural units other than the structural units derived from the alkyleneimine. Examples of the modified polyalkyleneimine include: (i) compounds in which, for example, 1 mole to 300 moles of an alkylene oxide and / or a glycidyl ether compound having 2 to 30 carbon atoms are added to at least a portion of the primary amino groups and / or secondary amino groups contained in the polyalkyleneimine, per mole of active hydrogen in the amino groups; (ii) compounds in which, for example, a compound having a carbon-carbon unsaturated double bond, such as acrylic acid, an acrylic acid ester, styrene, acrylonitrile, N-vinylpyrrolidone, or vinyl acetate, is added to at least a portion of the primary amino groups and / or secondary amino groups contained in the polyalkyleneimine by Michael addition; and (iii) compounds in which, for example, an isocyanate group-containing compound, an ester group-containing compound, a ketone group-containing compound, or an acid anhydride is added to at least a portion of the primary amino groups and / or secondary amino groups contained in the polyalkyleneimine.

[0038] The total content of structural units derived from alkyleneimine in the modified polyalkyleneimine is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, relative to 100% by mass of the total amount of the modified polyalkyleneimine.

[0039] (Component (B): Polyvalent Phosphonic Acid) The polyvalent phosphonic acid has two or more phosphonic acid groups (-P(=O)(OH)) in the molecule. ２ ) The polyvalent phosphonic acid is a compound having excellent resistance to heat and oxidation, and excellent chelating ability with respect to impurities (particularly metals). Therefore, it is presumed that the adverse effects of the impurities in the carbon dioxide absorbent, such as decomposition of the polyalkyleneimine, can be suppressed, and the durability of the carbon dioxide absorbent can be improved. In the present specification, the phosphonic acid group is defined as a phosphate group (-O-P(=O)(OH) ２) is distinguished from the above-mentioned polyvalent phosphonic acid. Therefore, the above-mentioned polyvalent phosphonic acid means a compound in which the phosphorus atom in the above-mentioned phosphonic acid group is directly bonded to an organic group (typically, a carbon atom in an organic group). Note that the above-mentioned polyvalent phosphonic acid is sufficient as long as it has at least two or more phosphonic acid groups in the molecule, and may further have another acid group (a carboxylic acid group, a sulfonic acid group, a phosphate group, etc.).

[0040] As the polyvalent phosphonic acid, from the viewpoint of obtaining a better chelating ability per molecular weight and a better compatibility with the component (A), 1-hydroxyethane-1,1-diphosphonic acid, nitrilotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepentakis(methylphosphonic acid), methylenediphosphonic acid, 1,2-ethylenediphosphonic acid, 1,3-propylenediphosphonic acid, 1,4-phenylenediphosphonic acid, alendronic acid, zoledronic acid, Preferably, the polyvalent phosphonic acid is at least one selected from the group consisting of 1-hydroxyethane-1,1-diphosphonic acid, nitrilotri(methylenephosphonic acid), methylenediphosphonic acid, 1,2-ethylenediphosphonic acid, 1,3-propylenediphosphonic acid, alendronic acid, zoledronic acid, and glycine-N,N-bis(methylenephosphonic acid), and more preferably at least one selected from the group consisting of 1-hydroxyethane-1,1-diphosphonic acid, nitrilotri(methylenephosphonic acid), methylenediphosphonic acid, 1,2-ethylenediphosphonic acid, 1,3-propylenediphosphonic acid, alendronic acid, zoledronic acid, and glycine-N,N-bis(methylenephosphonic acid). Only one type of polyvalent phosphonic acid may be used, or two or more types may be used.

[0041] From the viewpoint of chelating ability per molecular weight and molecular mobility, the molecular weight of the polyvalent phosphonic acid is preferably 1,000 or less, more preferably 600 or less, even more preferably 500 or less, still more preferably 400 or less, and particularly preferably 300 or less. The molecular weight is preferably 150 or more, more preferably 200 or more.

[0042] (Component (C): Quaternary ammonium salt and / or amine) Component (C) is a compound different from component (A) and is a quaternary ammonium salt and / or amine. By using such component (C), it is presumed that some or all of the phosphonic acid groups in component (B) preferably form a salt with some or all of component (C). This suppresses the neutralization reaction between component (A) and component (B), allowing component (A) to react with carbon dioxide more efficiently, thereby further improving the carbon dioxide adsorption / desorption ability. In addition, the salt formed by component (C) neutralizing component (B) has excellent solubility in solvents (particularly water) and compatibility with component (A), and is therefore presumed to suppress gelation of the composition and further improve its storage stability.

[0043] The component (C) may be a quaternary ammonium salt having at least one quaternary ammonium group in the molecule, or an amine having at least one amino group in the molecule. The component (C) may also be a compound having a quaternary ammonium group and an amino group in the molecule, or a compound having two or more quaternary ammonium groups and / or amino groups in the molecule. From the viewpoints of molecular mobility and excellent solubility and storage stability, the component (C) is preferably a quaternary ammonium salt having one quaternary ammonium group in the molecule and / or an amine having one amino group in the molecule.

[0044] The molecular weight of the component (C) is not particularly limited, but from the viewpoint of neutralizing ability per molecular weight and molecular mobility, it is preferably less than 300. The molecular weight may also be 10 or more.

[0045] The component (C) may contain either one or more of the quaternary ammonium salts. The component (C) may contain either one or more of the amines. Furthermore, the component (C) may contain both the quaternary ammonium salt and the amine.

[0046] The quaternary ammonium salt is preferably at least one selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethyl-1-adamantylammonium hydroxide, trimethylphenylammonium hydroxide, and benzyltriethylammonium hydroxide. When the quaternary ammonium salt is one of the above compounds, compatibility with component (A) falls within a suitable range, and it can be expected that the storage stability will be even more satisfactory.

[0047] The total number of carbon atoms per molecule of the quaternary ammonium salt is preferably 20 or less, more preferably 14 or less, even more preferably 12 or less, and particularly preferably 10 or less, from the viewpoint of achieving better compatibility with component (A) and carbon dioxide adsorption / desorption ability. The total number of carbon atoms per molecule of the quaternary ammonium salt is preferably 4 or more, from the same viewpoint and also from the viewpoint of achieving low volatility and better supportability on the carrier. The counter ion of the quaternary ammonium salt is preferably a hydroxide ion, from the viewpoint of suppressing adverse effects on practical specifications, since the by-product during neutralization is water. That is, the quaternary ammonium salt is preferably a quaternary ammonium hydroxide, and the total number of carbon atoms per molecule is preferably within the above range.

[0048] The amine is not particularly limited, and aliphatic amines and aromatic amines can be used. Among these, aliphatic amines are preferred as the amine. Examples of the aliphatic amine include primary amines such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, t-butylamine, sec-butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, and tetradecylamine; secondary amines such as dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, di-t-butylamine, di-sec-butylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, and dinonylamine; and trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, and tri-sec-butylamine. tertiary amines such as pyrrolidine, morpholine, piperazine, 1,4-diazabicyclo[2.2.2]octane, and diazabicycloundecene; cyclic amines such as methanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(ethylamino)ethanol, 2-(propylamino)ethanol, 2-(butylamino)ethanol, 2-(2-aminoethoxy)ethanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, tris(hydroxymethyl)aminomethane, 2-(isopropylamino)ethanol, 2-(methylamino)ethanol, and N-methyldiethanolamine;Ethylenediamine, 1,2-diaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,3-diaminopentane, tris(2-aminoethyl)amine, trimethylenediamine, 1,4-butanediamine (common name: putrescine), 1,5-pentanediamine (common name: cadaverine), hexamethylenediamine, heptamethylenediamine, octamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 1,2-diaminopropane, 2-ethylaminoethylamine Examples of polyamines include N,N'-bis(2-aminoethyl)-1,3-propanediamine, N,N'-bis(3-aminopropyl)-ethylenediamine, N,N'-bis(3-aminopropyl)-1,3-propylenediamine, and N,N'-bis(3-aminopropyl)-1,4-butylenediamine;

[0049] The aliphatic amine is preferably an amino alcohol from the viewpoint of achieving better compatibility with component (A). The amino alcohol is preferably at least one selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(dimethylamino)ethanol, 3-amino-1-propanol, tris(hydroxymethyl)aminomethane, 2-(isopropylamino)ethanol, 2-(methylamino)ethanol, and N-methyldiethanolamine. When the amine is one of the above compounds, compatibility with component (A) falls within a suitable range, and it can be expected that storage stability will be even more satisfactory.

[0050] From the viewpoint of achieving better compatibility with component (A) and better carbon dioxide adsorption / desorption ability, the total number of carbon atoms per molecule of the amine is preferably 20 or less, more preferably 14 or less, even more preferably 12 or less, and particularly preferably 10 or less. From the same viewpoint and from the viewpoint of achieving low volatility and better supportability on a carrier, the total number of carbon atoms per molecule of the amine is preferably 1 or more, more preferably 2 or more. In other words, it is preferable that the amine is an amino alcohol and that the total number of carbon atoms per molecule is within the above range.

[0051] The composition may be liquid or solid. From the viewpoint of superior handling and supportability when using the composition in a carbon dioxide absorbent described below, the composition is preferably liquid. Examples of the liquid composition include a composition containing a solvent such as water, in which the component (A), the component (B), and the component (C) are dissolved or dispersed in the solvent. Other examples of the liquid composition include a composition that does not contain a solvent such as water, in which one or more of the component (A), the component (B), and the component (C) are liquid, and other solid components are dissolved or dispersed in the liquid components. Examples of the solid composition include a solvent-free composition containing the component (A), the component (B), and the component (C).

[0052] (Other Components) The composition may contain other components in addition to the above-mentioned components. Examples of the other components include solvents (e.g., water, organic solvents, etc.), surfactants (anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants), antioxidants, antioxidant assistants, crystallization inhibitors, etc. Further examples of the other components include metals that are impurities that are not intentionally blended. Only one type of the other components may be used, or two or more types may be used. The HLB (hydrophilic-lipophilic balance) of the surfactant is, for example, preferably 10 or more, more preferably 12 or more, and even more preferably 15 or more.

[0053] The antioxidant may be a radical scavenger, a peroxide decomposer, or the like. The radical scavenger may be a phenolic antioxidant, an amine antioxidant, or the like, with an amine antioxidant being preferred. The peroxide decomposer may be any agent capable of effectively decomposing peroxides, but may be a sulfur-based antioxidant, a phosphorus-based antioxidant, a phenolic antioxidant, a hindered amine-based antioxidant, or the like. Examples of the sulfur-based antioxidant include 2-hydroxyethyl disulfide, 1,2-bis[(2-hydroxyethyl)thio]ethane, thiodipropionic acid, dilauryl thiodipropionate, distearyl thiodipropionate, laurylstearyl thiodipropionate, dimyristyl thiodipropionate, distearyl-β,β'-thiodibutyrate, thiobis(β-naphthol), thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, dodecyl mercaptan, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropyl xanthate, and dodecanethiol, with 2-hydroxyethyl disulfide and 1,2-bis[(2-hydroxyethyl)thio]ethane being more preferred.Examples of the phosphorus-based antioxidant include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(octadecyl) phosphite, cyclic neopentane tetrayl bis(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(2,4-di-t-butylphenyl) phosphite, and cyclic neopentane tetrayl bis(2,4-di-t-butylphenyl) phosphite. phosphites (phosphite antioxidants) such as bis[2-t-butyl-4-methylphenyl]phosphite and bis[2-t-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrogenphosphite; and oxaphosphaphenanthrene oxides such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.Examples of the phenolic antioxidant include monophenols such as 4-methoxyphenol, hydroquinone, 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-p-ethylphenol, and stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), and 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy} bisphenols such as 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione, and polymeric phenols such as tocophenol. Examples of the hindered amine antioxidant include bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, methyl-1,2,2,6,6-pentamethyl-4-piperidylsebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and 4-hydroxy-2,2,6,6-tetramethylpiperidine.

[0054] Examples of the crystallization inhibitor include water-soluble polymers such as polyvinylpyrrolidone, polyvinyl alcohol, hydroxyethyl cellulose, etc. By using a water-soluble polymer as a crystallization inhibitor, it is possible to suppress the formation of an insoluble salt due to a secondary interaction between the oligoamine compound and carbamic acid generated by the reaction of the oligoamine compound with carbon dioxide.

[0055] Examples of the metal impurity include a simple metal and a component containing a metal (e.g., a metal oxide). Examples of the metal include a transition metal. The transition metal is any element of Groups 3 to 12 of the periodic table of the elements, specifically at least one selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc, and more specifically at least one selected from the group consisting of chromium, manganese, iron, cobalt, nickel, and copper.

[0056] From the viewpoint of excellent durability, the content of metal-containing components in the composition is preferably 50 ppm or less, more preferably 30 ppm or less, and even more preferably 10 ppm or less, relative to 100% by mass of the total composition. Furthermore, it is particularly preferable that the composition is substantially free of metal-containing components. Furthermore, the content may be 0.5 ppm or more, or even 1 ppm or more, relative to 100% by mass of the total composition. More specifically, the total content of the components containing chromium, manganese, iron, cobalt, nickel, and copper in the composition is preferably within the above range, relative to 100% by mass of the total composition. It is believed that the presence of metals in the composition induces, for example, oxidative degradation of the polyalkyleneimine upon heating, accelerating degradation such as decomposition of the polyalkyleneimine. Therefore, even a very small amount of metal in the composition can result in a significant decrease in durability, but the composition of the present invention is expected to maintain better durability. The content can be measured, for example, by X-ray fluorescence (XRF) analysis.

[0057] From the viewpoint of excellent production efficiency, the content of the solvent (particularly water) in the liquid composition is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to 100% by mass of the total amount of the composition. Furthermore, the content may be 0.01% by mass or more, 0.1% by mass or more, or even 1% by mass or more. Because the composition has a composition in which gelation is further suppressed, even the above content is expected to provide even more sufficient storage stability. Furthermore, the total content of the other components may be included within a range that does not impair the performance of the composition, and is preferably within the above range, relative to 100% by mass of the total amount of the composition.

[0058] The content of component (B) is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, relative to the total amount (100% by mass) of components (A), (B), and (C) in the composition. Furthermore, the content may be 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more. When the content is 10% by mass or less, the amount of component (B) falls within a more suitable range, and the concentration of component (A) in the composition can be maintained at a sufficiently high level, which is expected to result in more sufficient carbon dioxide adsorption and desorption capacity. Furthermore, when the content is 0.01% by mass or more, the effect of suppressing the adverse effects of impurities falls within a suitable range, which is expected to result in more sufficient durability.

[0059] The content of component (C) is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, relative to the total amount (100% by mass) of components (A), (B), and (C) in the composition. Furthermore, the content may be 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more. When the content is 10% by mass or less, the amount of component (C) falls within a more suitable range, and the concentration of component (A) in the composition can be maintained at a sufficiently high level, which is expected to result in more sufficient carbon dioxide adsorption and desorption capacity. Furthermore, when the content is 0.01% by mass or more, the effect of suppressing the adverse effects of impurities falls within a suitable range, which is expected to result in more sufficient durability.

[0060] The total content of components (B) and (C) is preferably 0.01 to 10% by mass, more preferably 0.05 to 10% by mass, and even more preferably 0.05 to 5% by mass, relative to 100% by mass of the total amount of components (A), (B), and (C) in the composition. When the total content is 10% by mass or less, the total amount of components (B) and (C) falls within a more suitable range, allowing the concentration of component (A) in the composition to be maintained at a sufficiently high level, which is expected to result in even more satisfactory carbon dioxide adsorption / desorption capabilities. Furthermore, when the total content is 0.01% by mass or more, the effect of suppressing the adverse effects of impurities falls within a suitable range, which is expected to result in even more satisfactory durability.

[0061] The degree of neutralization of component (B) by component (C) in the composition is not particularly limited and can be changed appropriately depending on the types of components (B) and (C) and the types of impurities in the absorbent. In this embodiment, for example, when one type each of component (B) and component (C) is used, the degree of neutralization can be calculated by applying the total number m of phosphonic acid groups in component (B), the number of moles x of component (B), the total number n of quaternary ammonium groups and / or amino groups in component (C), and the number of moles y of component (C) to the following formula. In this specification, unless otherwise specified, the "degree of neutralization" refers to the theoretical ratio of acidic hydroxy groups (P-OH) in the phosphonic acid groups in component (B) neutralized by component (C). That is, the above-mentioned degree of neutralization means the degree of neutralization when it is assumed that the component (B) is neutralized only by the component (C) and the neutralization reaction proceeds with a reaction efficiency of 100%. Therefore, unless otherwise specified, if the composition does not contain the component (C), the degree of neutralization is 0%. Furthermore, if the acidic hydroxy groups in the component (B) are theoretically completely neutralized by the component (C), the degree of neutralization is 100%. Neutralization degree (%) = [(n x y) / (2m x x)] x 100

[0062] Even when two or more of the above-mentioned components (B) or (C) are used, the degree of neutralization can be calculated by the following generalized formula for multiple components: Degree of neutralization (%) = [Σ(n ｊ xy ｊ ) / Σ (2 m ｉ ×x ｉ )]×100 [where n ｊ represents the total number of quaternary ammonium groups and / or amino groups contained in the jth component (C), and y ｊ represents the number of moles of the jth component (C), and m ｉ represents the total number of phosphonic acid groups contained in the i-th component (B), and x ｉ indicates the number of moles of the i-th component (B).

[0063] The degree of neutralization is not particularly limited, but is preferably 200% or less, more preferably 150% or less, even more preferably 120% or less, even more preferably 99% or less, and particularly preferably 95% or less. The degree of neutralization is preferably 0.1% or more, more preferably 1% or more, even more preferably 5% or more, even more preferably 10% or more, even more preferably 25% or more, and particularly preferably 50% or more. When the degree of neutralization is 200% or less, the amount of component (C) falls within a more suitable range, and the concentration of component (A) in the composition can be maintained at a sufficiently high level, which is expected to result in a more sufficient carbon dioxide adsorption / desorption capacity. When the degree of neutralization is 0.1% or more, the amount of component (C) falls within a more suitable range, which is expected to result in a lower ratio of unneutralized component (B). Therefore, the neutralization reaction between component (A) and unneutralized component (B) is suppressed, and the reaction between component (A) and carbon dioxide proceeds more efficiently, which is expected to result in a more sufficient carbon dioxide adsorption / desorption capacity.

[0064] The composition can be produced by a known or conventional method. For example, it can be produced by mixing and stirring the above-mentioned components (at least the component (A), the component (B), and the component (C)). From the viewpoint of efficiently neutralizing the component (B) with the component (C), a production method for obtaining the composition preferably includes, in this order, a step of mixing the component (B) with the component (C) to prepare a polyvalent phosphonate, and a step of mixing the component (A) with the polyvalent phosphonate. In addition, the component (A), the component (B), and the component (C) may all be solutions dissolved or dispersed in a solvent.

[0065] [Carbon dioxide absorbent] A carbon dioxide absorbent can be prepared using the composition. A carbon dioxide absorbent containing the composition may be referred to as the "carbon dioxide absorbent of the present invention." In other words, the composition is preferably a carbon dioxide absorbent composition. By including the composition, the carbon dioxide absorbent of the present invention exhibits carbon dioxide adsorption / desorption ability while also exhibiting excellent durability against repeated adsorption / desorption.

[0066] The carbon dioxide absorbent of the present invention may contain other components besides the composition. The carbon dioxide absorbent of the present invention may be the composition of the present invention itself, or may be one produced by adding various components to the composition of the present invention, for example. Examples of the various components include a carrier and those exemplified and explained as other components that may be contained in the composition of the present invention described above. From the viewpoint of excellent handleability, the carbon dioxide absorbent preferably contains at least a carrier. That is, it is preferable that the carbon dioxide absorbent contains the composition and the carrier, and the composition is supported on the carrier. Only one of the various components may be used, or two or more of them may be used.

[0067] The carrier is preferably a porous carrier particle from the viewpoint of improving the carbon dioxide adsorption / desorption capacity. Furthermore, examples of materials constituting the carrier include inorganic materials and polymeric materials. That is, the carrier is preferably a porous carrier particle composed of an inorganic material and / or a polymeric material.

[0068] The inorganic material is preferably at least one selected from the group consisting of bentonite, attapulgite, kaolinite, montmorillonite, ball clay, fuller's earth, hectorite, palygorskite, saponite, sepiolite, halloysite, silica, calcium sulfate, zeolite, alumina, activated carbon, and metal-organic frameworks, more preferably silica and / or alumina, and even more preferably silica. The silica is not particularly limited, and known silicas such as fumed silica produced by a dry process, precipitated silica produced by a wet process, silica gel, and silica sol can be used as appropriate. Only one of the inorganic materials may be used, or two or more may be used.

[0069] Examples of the polymeric material include ether sulfone (PES), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), mixed cellulose esters or nitrocellulose (NC), polyolefin, polyethylene, polypropylene, polymethylpentene, polyketone, polyimide, polystyrene, polymethyl methacrylate, polydimethylsiloxane, polyester, nylon, polycaprolactone, polylactic acid, polyvinyl alcohol, polyglycolic acid, etc. Only one of the above polymeric materials may be used, or two or more thereof may be used.

[0070] The specific surface area of ​​the carrier is set to 70 m from the viewpoint of excellent carbon dioxide adsorption / desorption ability. ２ / g or more is preferable, and 80m ２ / g or more, more preferably 100m ２ / g or more. The specific surface area is 800 m ２ / g or less, and ２ / g or less, and ２ / g or less.

[0071] From the viewpoint of excellent carbon dioxide adsorption / desorption ability, the content of component (A) in the carbon dioxide absorbent is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the total amount of the carrier. Moreover, from the viewpoint of excellent carbon dioxide adsorption / desorption ability and supportability, the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 100 parts by mass or less, relative to 100 parts by mass of the total amount of the carrier. Moreover, the total content of components (A), (B), and (C) in the carbon dioxide absorbent is preferably within the above range, relative to 100 parts by mass of the total amount of the carrier.

[0072] The carrier may contain metals as impurities. Examples of such metals include those exemplified and described as other metal components that may be contained in the composition of the present invention. From the viewpoint of excellent durability, the content of the metal-containing components in the carrier is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, even more preferably 3,000 ppm or less, and particularly preferably 2,000 ppm or less, relative to 100% by mass of the total amount of the carrier. Furthermore, from the viewpoint of industrial applicability (productivity), the content may be 10 ppm or more, 30 ppm or more, or even 50 ppm or more, relative to 100% by mass of the total amount of the carrier. More specifically, the total content of the components containing chromium, manganese, iron, cobalt, nickel, and copper in the carrier is preferably within the above range, relative to 100% by mass of the total amount of the carrier. The content can be measured, for example, by X-ray fluorescence (XRF) analysis.

[0073] From the viewpoint of achieving even better durability and carbon dioxide adsorption / desorption capability, the content of the metal-containing component in the support may be 1000 ppm or less, 800 ppm or less, 500 ppm or less, 300 ppm or less, or 250 ppm or less, relative to 100% by mass of the total amount of the support. More specifically, the total content of the components containing chromium, manganese, iron, cobalt, nickel, and copper in the support is preferably within the above range, relative to 100% by mass of the total amount of the support.

[0074] From the viewpoint of excellent durability, the content of the metal-containing component in the carbon dioxide absorbent is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, even more preferably 3,000 ppm or less, and particularly preferably 2,000 ppm or less, relative to 100% by mass of the total amount of the carbon dioxide absorbent. Furthermore, from the viewpoint of industrial applicability (productivity), the content may be 10 ppm or more, 30 ppm or more, or even 50 ppm or more, relative to 100% by mass of the total amount of the carbon dioxide absorbent. More specifically, the total content of the components containing chromium, manganese, iron, cobalt, nickel, and copper in the carbon dioxide absorbent is preferably within the above range, relative to 100% by mass of the total amount of the carbon dioxide absorbent. The content can be measured, for example, by X-ray fluorescence (XRF) analysis.

[0075] Furthermore, from the viewpoint of achieving even better durability and carbon dioxide adsorption / desorption ability, the content ratio of the metal-containing component in the carbon dioxide absorbent may be 1000 ppm or less, 800 ppm or less, 500 ppm or less, 300 ppm or less, or 250 ppm or less, relative to 100% by mass of the total amount of the carbon dioxide absorbent. More specifically, the total content ratio of the components containing chromium, manganese, iron, cobalt, nickel, and copper in the carbon dioxide absorbent is preferably within the above range, relative to 100% by mass of the total amount of the carbon dioxide absorbent.

[0076] From the viewpoint of excellent durability, the total content of component (B) and component (C) in the carbon dioxide absorbent is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, and even more preferably 300 parts by mass or more, relative to 100 parts by mass of the total amount of the metal-containing components in the carbon dioxide absorbent. From the viewpoint of excellent durability and carbon dioxide adsorption / desorption ability, the total content is preferably 5,000 parts by mass or less, more preferably 3,000 parts by mass or less, and even more preferably 2,000 parts by mass or less, relative to 100 parts by mass of the total amount of the metal-containing components in the carbon dioxide absorbent. Furthermore, when the carbon dioxide absorbent contains a carrier, the total amount of the metal-containing components often depends mainly on the carrier, so the total content of component (B) and component (C) in the carbon dioxide absorbent is preferably within the above range, relative to 100 parts by mass of the total amount of the metal-containing components in the carrier.

[0077] The carbon dioxide absorbent can separate carbon dioxide by absorbing not only carbon dioxide in gases containing high concentrations of carbon dioxide, but also dilute carbon dioxide in conditioned air or the atmosphere. Furthermore, by undergoing a step of desorbing (desorbing) the absorbed carbon dioxide, the carbon dioxide can be recovered and further absorbed again. Therefore, by using the carbon dioxide absorbent, it is possible to suppress a decrease in carbon dioxide adsorption / desorption ability even after repeated carbon dioxide absorption / desorption.

[0078] The carbon dioxide absorbent can be produced by a known or conventional method. The method for producing the carbon dioxide absorbent may be referred to as the "production method of the present invention." The carbon dioxide absorbent can be produced, for example, by mixing and stirring the above-mentioned components. Specifically, when the carbon dioxide absorbent includes the composition and the carrier, the production method of the present invention preferably includes a step of mixing and stirring the composition and the carrier to support the composition on the carrier (supporting step). The supporting step may be a step of adding the composition to the carrier and supporting it (step (a)), or a step of separately adding each component contained in the composition to the carrier and supporting it (step (b)). The supporting step is preferably the step (a) from the viewpoint of excellent production efficiency. In the step (b), the order of addition of each component is not particularly limited. For example, the order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (A) to the carrier is not particularly limited. The order of addition of the component (B) to the carrier is not particularly limited. The order of addition of the component (B) to the carrier is not particularly limited. The order of addition of the component (A ... Here, other steps (e.g., a separation step, a drying step, etc.) may be included between the first supporting step, the second supporting step, and the third supporting step. In addition, a solvent (e.g., water) may be added in the supporting step, if necessary.

[0079] For example, the carrier may be impregnated with the composition (and a solvent, if necessary) (impregnation), the composition may be added dropwise to the carrier (dropping), or the carrier may be filled in a container such as a column and then the composition may be passed through (passing). Among these, the impregnation method is preferred from the viewpoint of simplicity of operation and equipment.

[0080] The pressure conditions in the loading step are not particularly limited and can be arbitrarily selected from normal pressure, reduced pressure, increased pressure, etc. When the support has pores, the treatment is preferably carried out under reduced pressure from the viewpoint of removing bubbles in the pores and efficiently loading the support. Specifically, the pressure during the treatment is preferably −0.08 MPaG to −0.004 MPaG, more preferably −0.07 MPaG to −0.01 MPaG, and even more preferably −0.06 MPaG to −0.02 MPaG.

[0081] The temperature conditions in the above-mentioned supporting step are not particularly limited, but from the viewpoint of excellent supporting ability, it is preferably 20°C to 90°C, more preferably 30°C to 80°C, and even more preferably 40°C to 70°C.

[0082] Furthermore, the production method of the present invention may, if necessary, include a step of separating excess solvent from the carrier carrying the composition (separation step), and / or a step of removing the solvent from the carrier (drying step).

[0083] For the separation step, any known or conventional method can be used, for example, any solid-liquid separation technique such as filtration, decantation, centrifugation, etc. Among these, filtration is preferred from the viewpoint of excellent procedural simplicity.

[0084] The temperature conditions in the drying step are not particularly limited, but are preferably 30°C to 100°C, more preferably 40°C to 98°C, even more preferably 50°C to 95°C, and particularly preferably 50°C to 90°C.

[0085] The treatment time in the drying step is not particularly limited, but is preferably 0.1 to 48 hours, more preferably 0.2 to 24 hours, and even more preferably 0.5 to 12 hours.

[0086] The pressure conditions in the drying step are not particularly limited and can be arbitrarily selected from normal pressure, reduced pressure, increased pressure, etc. Among these, normal pressure is preferred from the viewpoint of maintaining the state in which the composition is supported on the carrier.

[0087] The carbon dioxide absorbent can be installed and used in an apparatus (carbon dioxide recovery apparatus) that separates and recovers carbon dioxide from a gas to be treated that contains carbon dioxide. The gas to be treated is a carbon dioxide-containing gas that contains at least carbon dioxide, but may also contain gases other than carbon dioxide. Examples of the gas to be treated include the atmosphere and high-concentration gases that contain carbon dioxide at a higher concentration than the atmosphere. Such high-concentration gases are, for example, those emitted from internal combustion engines or factories.

[0088] Examples of methods for using the carbon dioxide absorbent include a carbon dioxide separation method including a step of contacting carbon dioxide in a gas with the carbon dioxide absorbent (contact step), and a carbon dioxide recovery method including a step of desorbing the carbon dioxide from the carbon dioxide absorbent that has absorbed carbon dioxide (desorption step). In the contact step, the carbon dioxide absorbent absorbs carbon dioxide in the gas, so that the carbon dioxide can be removed (separated) from the gas. In addition, in the desorption step, the carbon dioxide can be recovered by desorbing the carbon dioxide from the carbon dioxide absorbent.

[0089] The pressure condition for the separation step may be, for example, 0.8 to 1.1 atmospheres, and the temperature condition for the separation step may be, for example, −40° C. to 50° C.

[0090] The pressure conditions for the recovery step may be, for example, reduced pressure, 0.02 to 0.5 atmospheres, or 0.1 to 0.3 atmospheres, and the temperature conditions for the recovery step may be, for example, heated, 50°C to 130°C.

[0091] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass." The amounts and mass ratios described in the examples refer to the amounts and mass ratios of each component (i.e., the amounts and mass ratios of the solid content in each raw material) excluding the solvent (water). The abbreviations, manufacturers, etc. of the raw materials used are as follows:

[0092] HEDP: 1-hydroxyethane-1,1-diphosphonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.; 60% by mass aqueous solution) TEAH: tetraethylammonium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.; 10% by mass aqueous solution) TMAH: tetramethylammonium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.; 10% by mass aqueous solution) DMAE: 2-(dimethylamino)ethanol (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) DEA: diethanolamine (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) HEAH: 2-hydroxyethyltrimethylammonium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.; 47-50% by mass aqueous solution) BnAH: benzyltrimethylammonium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.; 10% by mass aqueous solution) TIPA: triisopropanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.) TEA: triethanolamine (manufactured by Nippon Shokubai Co., Ltd.) NaOH: sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) PA: Phosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) PEI: Polyethyleneimine (SP-012; manufactured by Nippon Shokubai Co., Ltd., number average molecular weight 1,200 (catalog value, boiling point elevation method))

[0093] Example 1 (Composition Preparation Step) HEDP as component (B) and water were mixed to prepare a 5 mass% HEDP aqueous solution. Similarly, TEAH as component (C) and water were mixed to prepare a 5 mass% TEAH aqueous solution. Next, the 5 mass% HEDP aqueous solution and the 5 mass% TEAH aqueous solution were mixed so that the mass ratio of HEDP:TEAH = 1.0:0.71 in terms of solid content, and then stirred for 10 minutes to obtain a 5 mass% HEDP neutralized aqueous solution in which a portion of the phosphonic acid groups of HEDP were neutralized with TEAH. Here, the degree of neutralization of HEDP in the neutralized product was 25%. The degree of neutralization can be calculated from the above-mentioned relational expression for the degree of neutralization, specifically, by applying m, the total number of phosphonic acid groups in component (B), x, the number of moles of component (B), n, the total number of quaternary ammonium groups and / or amino groups in component (C), and y, the number of moles of component (C), to the following formula: degree of neutralization (%) = [(n × y) / (2m × x)] × 100

[0094] Next, PEI as component (A) and the 5 mass% aqueous solution of neutralized HEDP were mixed so that the mass ratio, calculated as solid content, of PEI:HEDP neutralized compound was 100:2, and the mixture was stirred for 60 minutes to obtain the composition of Example 1 (73 mass% aqueous solution).

[0095] (Preparation step of carbon dioxide absorbent) The above composition (0.5 parts as solid content) and water (5.0 parts) were mixed to prepare a uniform solution. Next, 1.0 part of HI-SIL-915 (manufactured by PPG Industries) as a carrier was added to the above solution, and the solution was impregnated with stirring for 30 minutes. Next, the solution was treated under reduced pressure at 60°C and 20 Pa, and then heated and dried in an oven at 80°C for 2 hours, thereby obtaining a carbon dioxide absorbent of Example 1 in which the above composition was supported on a carrier.

[0096] The content of metal-containing components in the carrier (HI-SIL-915) was measured by X-ray fluorescence (XRF) analysis and found to be 900 ppm. Here, the content refers to the total content of each of the components containing chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu).

[0097] Example 2 A carbon dioxide absorbent of Example 2 was obtained in the same manner as in Example 1, except that in the composition preparation step, the mass ratio of HEDP:TEAH was changed from HEDP:TEAH = 1.0:0.71 to HEDP:TEAH = 1.0:1.43. At this time, the degree of neutralization of HEDP was 50%.

[0098] Example 3 A carbon dioxide absorbent of Example 3 was obtained in the same manner as in Example 1, except that in the composition preparation step, the mass ratio of HEDP:TEAH was changed from HEDP:TEAH = 1.0:0.71 to HEDP:TEAH = 1.0:2.14. At this time, the degree of neutralization of HEDP was 75%.

[0099] Example 4 A carbon dioxide absorbent of Example 4 was obtained in the same manner as in Example 1, except that in the composition preparation step, the mass ratio of HEDP:TEAH was changed from HEDP:TEAH = 1.0:0.71 to HEDP:TEAH = 1.0:2.86. At this time, the degree of neutralization of HEDP was 100%.

[0100] Example 5 A carbon dioxide absorbent of Example 5 was obtained in the same manner as in Example 1, except that in the composition preparation step, DMAE was used as component (C) instead of TEAH as component (C), and the mass ratio was changed from HEDP:TEAH = 1.0:0.71 to HEDP:DMAE = 1.0:1.30. In this case, the degree of neutralization of HEDP was 75%.

[0101] Example 6 A carbon dioxide absorbent of Example 6 was obtained in the same manner as in Example 1, except that in the composition preparation step, DEA was used as component (C) instead of TEAH, and the mass ratio was changed from HEDP:TEAH = 1.0:0.71 to HEDP:DEA = 1.0:1.53. In this case, the degree of neutralization of HEDP was 75%.

[0102] Example 7 A carbon dioxide absorbent of Example 7 was obtained in the same manner as in Example 1, except that in the composition preparation step, TEAH was replaced with TMAH as component (C) and the mass ratio of HEDP:TEAH was changed from 1.0:0.71 to 1.0:1.33. In this case, the degree of neutralization of HEDP was 75%.

[0103] Example 8 A carbon dioxide absorbent of Example 8 was obtained in the same manner as in Example 1, except that in the composition preparation step, HEAH was used as component (C) instead of TEAH, and the mass ratio of HEDP:TEAH was changed from HEDP:TEAH = 1.0:0.71 to HEDP:HEAH = 1.0:1.76. In this case, the degree of neutralization of HEDP was 75%.

[0104] Example 9 A carbon dioxide absorbent of Example 9 was obtained in the same manner as in Example 1, except that in the composition preparation step, BnAH was used as component (C) instead of TEAH, and the mass ratio of HEDP:TEAH was changed from 1.0:0.71 to 1.0:2.44. At this time, the degree of neutralization of HEDP was 75%.

[0105] Example 10 A carbon dioxide absorbent of Example 10 was obtained in the same manner as in Example 1, except that in the composition preparation step, TIPA was used as component (C) instead of TEAH, and the mass ratio was changed from HEDP:TEAH = 1.0:0.71 to HEDP:TIPA = 1.0:2.79. In this case, the degree of neutralization of HEDP was 75%.

[0106] Example 11 A carbon dioxide absorbent of Example 11 was obtained in the same manner as in Example 1, except that in the composition preparation step, TEA was used as component (C) instead of TEAH, and the mass ratio was changed from HEDP:TEAH = 1.0:0.71 to HEDP:TEA = 1.0:2.17. In this case, the degree of neutralization of HEDP was 75%.

[0107] Comparative Example 1 A carbon dioxide absorbent of Comparative Example 1 was obtained in the same manner as in Example 1, except that PEI (0.5 parts) was used instead of the composition of Example 1 (0.5 parts) in the preparation step of the carbon dioxide absorbent.

[0108] Comparative Example 2 In the composition preparation process, NaOH was used as component (C') instead of TEAH as component (C), and the mass ratio was changed from HEDP:TEAH = 1.0:0.71 to HEDP:NaOH = 1.0:0.58. Except for this, the carbon dioxide absorbent of Comparative Example 2 was prepared in the same manner as in Example 1. However, since gelation occurred when the Na-neutralized HEDP and PEI were mixed, the composition could not be supported on the carrier, and a carbon dioxide absorbent could not be obtained. At this time, the degree of neutralization of HEDP was 75%. Here, the degree of neutralization was calculated by applying the total number m of phosphonic acid groups in component (B), the number of moles x of component (B), and the number of moles y' of component (C') to the relational expression [y' / (2m x x)] x 100.

[0109] Comparative Example 3 A carbon dioxide absorbent of Comparative Example 3 was obtained in the same manner as in Example 1, except that PA (2 parts) was used as component (B') instead of the neutralized HEDP (2 parts) of Example 1 in the composition preparation step. Note that the degree of neutralization of PA at this time was 0%. Here, the degree of neutralization was calculated by applying the total number m' of hydroxyl groups directly bonded to phosphorus atoms in component (B'), the number of moles x' of component (B'), the total number n of quaternary ammonium groups and / or amino groups contained in component (C), and the number of moles y of component (C) to the relational formula [(n x y) / (m' x x')] x 100.

[0110] Comparative Example 4 In the composition preparation step, PA (2 parts) was used as component (B') instead of the neutralized HEDP (2 parts) of Example 1, and the mass ratio was changed from HEDP:TEAH = 1.0:0.71 to PA:TEAH = 1.0:4.51. Except for this, the carbon dioxide absorbent of Comparative Example 4 was obtained in the same manner as in Example 1. The degree of neutralization of PA was 100%. Here, the degree of neutralization was calculated by applying the total number m' of hydroxyl groups directly bonded to phosphorus atoms in component (B'), the number of moles x' of component (B'), the total number n of quaternary ammonium groups and / or amino groups possessed by component (C), and the number of moles y of component (C) to the relational expression [(n x y) / (m' x x')] x 100.

[0111] Comparative Example 5 A carbon dioxide absorbent of Comparative Example 5 was obtained in the same manner as in Example 1, except that in the composition preparation step, HEDP (2 parts) was used instead of the neutralized HEDP (2 parts) of Example 1. In this case, the degree of neutralization of HEDP was 0%.

[0112] <Evaluation> The compositions and carbon dioxide absorbents obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

[0113] (1) Storage Stability The compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 5 were allowed to stand at 25°C, and the fluidity after 7 days was visually confirmed and evaluated according to the following criteria. [Evaluation criteria for storage stability] ○: Fluidity the same as the initial state ×: Significant increase in viscosity or gelation

[0114] (2) Carbon Dioxide Adsorption / Desorption Ability The carbon dioxide adsorption / desorption amounts of the carbon dioxide absorbents obtained in Examples 1 to 11 and Comparative Examples 1 and 3 to 5 were measured by the following test. Then, using the obtained carbon dioxide adsorption / desorption amounts, the blank retention rate was calculated according to the following calculation formula, and evaluation was performed according to the following criteria. The carbon dioxide adsorption / desorption amounts at this time are shown in the item "without degradation treatment" in Table 1.

[0115] [Carbon dioxide adsorption / desorption test] Using a simultaneous differential thermal / thermogravimetric analyzer (TG-DTA) (TG-DTA8120, 8122, manufactured by Rigaku Corporation), the masses of the carbon dioxide absorbent at the absorption temperature (40°C) and the desorption temperature (110°C) were measured, and the carbon dioxide adsorption / desorption amount was calculated using the following formula. In this measurement, a carbon dioxide-containing gas simulating dry air was prepared by adjusting the flow rates of nitrogen and carbon dioxide using a mass flow controller, and supplied to the TG-DTA oven at 200 ml / min. At this time, the carbon dioxide concentration in the gas was set to about 400 ppm, and the humidity of the gas was kept constant at an absolute humidity of 2 g / kg. Carbon dioxide adsorption / desorption amount (mmol / g) = (W Ａ -W Ｄ ) / (M ＣＯ２ ×W １ ) W Ａ W: Mass (g) of carbon dioxide absorbent at absorption temperature Ｄ : Mass (g) of carbon dioxide absorbent at desorption temperature M ＣＯ２ W: molecular weight of carbon dioxide (g / mmol) １ : Mass (g) of carbon dioxide absorbent used in the test

[0116] [Calculation formula for blank retention rate] Blank retention rate (%) = [(amount of carbon dioxide adsorption / desorption in each Example or Comparative Example) / (amount of carbon dioxide adsorption / desorption in Comparative Example 1)] x 100

[0117] [Evaluation criteria for carbon dioxide adsorption / desorption capacity] ∘: Blank retention rate is 60% or more ×: Blank retention rate is less than 60%

[0118] (3) Durability The carbon dioxide absorbents obtained in Examples 1 to 11 and Comparative Examples 1 and 3 to 5 were subjected to the following degradation treatment, and then the above-mentioned carbon dioxide adsorption / desorption test was carried out to measure the carbon dioxide adsorption / desorption amounts. Using the obtained carbon dioxide adsorption / desorption amounts, the retention rate after degradation treatment was calculated according to the following calculation formula, and evaluation was carried out according to the following criteria. The carbon dioxide adsorption / desorption amounts at this time are shown in the "Degraded" section of Table 1.

[0119] [Deterioration Treatment] 0.03 g of each of the carbon dioxide absorbents obtained in Examples 1 to 11 and Comparative Examples 1 and 3 to 5 was weighed into a 10 mL vial. The top of each vial was protected with a piece of wrapping paper with multiple holes punched in it to prevent the inclusion of foreign matter while allowing air to pass through. This was left to stand in an oven at 100°C for 24 hours and then cooled to obtain a carbon dioxide absorbent that had been subjected to a deterioration treatment. This treatment causes the carbon dioxide absorbent to undergo oxidative deterioration, making it possible to simulate an absorbent that has undergone heating and repeated adsorption / desorption treatments.

[0120] [Formula for calculating the retention rate after degradation treatment] Retention rate after degradation treatment (%) = [(amount of carbon dioxide adsorption / desorption with degradation treatment) / (amount of carbon dioxide adsorption / desorption without degradation treatment)] x 100

[0121] [Evaluation criteria for durability] ◯: Retention rate after deterioration treatment is 70% or more ×: Retention rate after deterioration treatment is less than 70%

[0122]

[0123] Carbon dioxide absorbents using compositions containing component (A), component (B), and component (C) all exhibited high carbon dioxide adsorption / desorption amounts and good carbon dioxide adsorption / desorption capabilities (Examples 1 to 11). Furthermore, the retention rates after degradation treatment were 87% to 99%, all of which were very high values, confirming their excellent durability. Furthermore, despite the compositions used in these carbon dioxide absorbents being highly concentrated (73% by mass aqueous solutions), no thickening or gelation over time was observed, confirming their excellent storage stability.

[0124] On the other hand, the carbon dioxide absorbent using a composition containing component (A) but not containing components (B) and (C) had a retention rate of 34% after degradation treatment, showing significant degradation and thus inferior durability (Comparative Example 1). Furthermore, the carbon dioxide absorbent using a composition containing an inorganic alkali instead of component (C) gelled within about 10 minutes of mixing during preparation, resulting in poor storage stability (Comparative Example 2). Furthermore, the carbon dioxide absorbent using a composition containing component (A), monofunctional phosphoric acid instead of component (B), and not containing component (C) had a retention rate of 60% after degradation treatment and showed significant degradation and therefore inferior durability (Comparative Example 3). Furthermore, the carbon dioxide absorbent using a composition containing components (A) and (C) and monofunctional phosphoric acid instead of component (B) had a lower carbon dioxide adsorption / desorption amount than Comparative Example 3, resulting in inferior carbon dioxide adsorption / desorption capacity. Furthermore, the retention rate after degradation treatment was 60%, resulting in poor durability (Comparative Example 4). Furthermore, a carbon dioxide absorbent using a composition containing component (A) and component (B) but not component (C) had an insufficient amount of carbon dioxide adsorption / desorption, and the results were unsatisfactory (Comparative Example 5).

[0125] Example 12 The composition of Example 12 was obtained in the same manner as in Example 1, except that in the composition preparation step, the mass ratio of HEDP:TEAH was changed from 1.0:0.71 to 1.0:2.86, and the mass ratio, calculated as solid content, of PEI:HEDP neutralized compound was changed from 100:2 to 100:5. The degree of neutralization of HEDP at this time was 100%.

[0126] (Preparation step of carbon dioxide absorbent) The above composition (0.5 parts as solid content) and water (5.0 parts) were mixed to prepare a uniform solution. Next, 1.0 part of CARiACT G-10 (manufactured by Fuji Silysia Chemical Ltd.) as a carrier was added to the above solution, and the solution was impregnated with stirring for 30 minutes. Next, the solution was treated under reduced pressure at 60°C and 20 Pa, and then heated and dried in an oven at 80°C for 2 hours, thereby obtaining a carbon dioxide absorbent of Example 12 in which the above composition was supported on a carrier.

[0127] The content of metal-containing components in the carrier (CARiACT G-10) was measured by X-ray fluorescence (XRF) analysis and found to be 200 ppm. Here, the content refers to the total content of each of the components containing chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu).

[0128] Example 13 A carbon dioxide absorbent of Example 13 was obtained in the same manner as in Example 12, except that in the composition preparation step, TMAH was used as component (C) instead of TEAH, and the mass ratio of HEDP:TEAH was changed from 1.0:2.86 to 1.0:1.77. In this case, the degree of neutralization of HEDP was 100%.

[0129] Comparative Example 6 A carbon dioxide absorbent of Comparative Example 6 was obtained in the same manner as in Example 12, except that SP-012 (0.5 parts) was used instead of the composition of Example 12 (0.5 parts) in the preparation step of the carbon dioxide absorbent.

[0130] The carbon dioxide absorbents obtained in Examples 12 and 13 and Comparative Example 6 were evaluated in the same manner as in the above evaluations (1), (2), and (3), except that the desorption temperature in the adsorption / desorption test was changed as follows and the evaluation criteria for durability were changed as follows. The results are shown in Table 2.

[0131] (2) Carbon dioxide adsorption / desorption capacity [Carbon dioxide adsorption / desorption test (part 2)] Using a simultaneous differential thermal / thermogravimetric analyzer (TG-DTA) (manufactured by Rigaku Corporation, TG-DTA8120, 8122), the masses of the carbon dioxide absorbent at the absorption temperature (40°C) and the desorption temperature (75°C) were measured, and the carbon dioxide adsorption / desorption amount was calculated using the following formula. In this measurement, a carbon dioxide-containing gas simulating dry air was prepared by adjusting the flow rates of nitrogen and carbon dioxide using a mass flow controller, and supplied into the TG-DTA oven at 200 ml / min. At this time, the carbon dioxide concentration in the gas was set to about 400 ppm, and the humidity of the gas was kept constant at an absolute humidity of 2 g / kg. Carbon dioxide adsorption / desorption amount (mmol / g) = (W Ａ -WＤ ) / (M ＣＯ２ ×W １ ) W Ａ W: Mass (g) of carbon dioxide absorbent at absorption temperature Ｄ : Mass (g) of carbon dioxide absorbent at desorption temperature M ＣＯ２ W: molecular weight of carbon dioxide (g / mmol) １ : Mass (g) of carbon dioxide absorbent used in the test

[0132] (3) Durability [Evaluation Criteria for Durability (Part 2)] ○: Retention rate after deterioration treatment is 80% or more ×: Retention rate after deterioration treatment is less than 80%

[0133]

[0134] In the case of a carbon dioxide absorbent using a composition containing component (A) but not component (B) or component (C), the retention rate after the aging treatment was 71%, and it was evaluated as having poor durability (Comparative Example 6). On the other hand, in the case of a carbon dioxide absorbent using a composition containing component (A), component (B), and component (C), the retention rate after the aging treatment was 87 to 91%, showing a tendency to be improved compared to Comparative Example 6, and it was evaluated as having excellent durability (Examples 12 to 13). Furthermore, the compositions used in the carbon dioxide absorbents of Examples 12 to 13 did not show any thickening or gelation over time, and were evaluated as having excellent storage stability. Furthermore, the blank retention rate was 105 to 112%, which was equal to or greater than that of Comparative Example 6, and it was evaluated as having excellent carbon dioxide adsorption and desorption ability.

[0135] Variations of the present invention are described below. [Appendix 1] A composition comprising the following components (A), (B), and (C): Component (A): polyalkyleneimine; Component (B): polyvalent phosphonic acid; and Component (C): a quaternary ammonium salt and / or amine, which is a compound different from component (A). [Appendix 2] The composition according to Appendix 1, wherein the quaternary ammonium salt is a quaternary ammonium hydroxide and has a total of 20 or less carbon atoms per molecule. [Appendix 3] The composition according to Appendix 1 or 2, wherein the amine is an amino alcohol and has a total of 20 or less carbon atoms per molecule. [Appendix 4] The composition according to any one of Appendices 1 to 3, wherein some or all of the phosphonic acid groups in component (B) form a salt with some or all of component (C). [Appendix 5] The composition according to any one of Appendices 1 to 4, wherein the total content of the component (B) and the component (C) is 0.01 to 10 mass% relative to 100 mass% of the total amount of the component (A), the component (B), and the component (C) in the composition. [Appendix 6] A carbon dioxide absorbent comprising the composition according to any one of Appendices 1 to 5. [Appendix 7] The carbon dioxide absorbent according to Appendices 6, comprising: a carrier; and the composition supported on the carrier. [Appendix 8] A method for separating carbon dioxide, comprising a step of contacting carbon dioxide in gaseous form with the carbon dioxide absorbent according to Appendices 6 or 7. [Appendix 9] A method for recovering carbon dioxide, comprising a step of desorbing the carbon dioxide from the carbon dioxide absorbent according to Appendices 6 or 7 that has absorbed the carbon dioxide.

Claims

1. A composition comprising the following components (A), (B), and (C): Component (A): polyalkyleneimine; Component (B): polyvalent phosphonic acid; and Component (C): a quaternary ammonium salt and / or amine, which is a compound different from component (A).

2. The composition according to claim 1, wherein the quaternary ammonium salt is a quaternary ammonium hydroxide and has a total carbon number per molecule of 20 or less.

3. The composition according to claim 1 or 2, wherein the amine is an amino alcohol and has a total carbon number per molecule of 20 or less.

4. The composition according to claim 1 or 2, wherein some or all of the phosphonic acid groups of component (B) form salts with some or all of component (C).

5. The composition according to claim 1 or 2, wherein the total content of component (B) and component (C) is 0.01 to 10 mass% relative to 100 mass% of the total amount of component (A), component (B), and component (C) in the composition.

6. A carbon dioxide absorbent comprising the composition of claim 1 or 2.

7. The carbon dioxide absorbent according to claim 6, comprising: a carrier; and the composition supported on the carrier.

8. A method for separating carbon dioxide, comprising a step of contacting carbon dioxide in gaseous form with the carbon dioxide absorbent according to claim 6.

9. A method for recovering carbon dioxide, comprising a step of desorbing carbon dioxide from the carbon dioxide absorbent according to claim 6 which has absorbed carbon dioxide.

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