Carbon dioxide gas adsorbent composition and aqueous solution composition

Abstract

Provided is a carbon dioxide gas adsorbent composition comprising: (A) an organic silicon compound having, for example, an average structure represented by formula (1) and having, per molecule, an amino group, and an alkoxysilyl group or a silanol group or both thereof; and (B) a solvent. (In the formula, A1 and A2 each represent a divalent hydrocarbon group having 1-20 carbon atoms, m represents a number of 0-4, R1 represents a monovalent hydrocarbon group having 1-10 carbon atoms, R2 represents a hydrogen atom or an alkyl group having 1-10 carbon atoms, and a-h represent numbers satisfying a≥0, b≥0, c≥0, d≥0, e≥0, f≥0, g≥0, h>0, and a+b+c>0.)

Description

Compositions and aqueous solutions for carbon dioxide adsorbents

[0001] The present invention relates to a composition for carbon dioxide adsorbent and an aqueous solution composition, and more specifically, to a composition for carbon dioxide adsorbent and an aqueous solution composition containing an amino group-containing organosilicon compound and a solvent.

[0002] In recent years, the impact of greenhouse gases, including carbon dioxide (CO2), has become a major concern as one of the causes of global warming, and countermeasures have become an urgent international issue from the perspective of protecting the global environment. As the main source of CO2 is the combustion of fossil fuels, the demand for reducing CO2 emissions from fossil fuel use is becoming increasingly strong. Accordingly, research is being actively conducted on methods (CCUS technology) that selectively adsorb and remove CO2 from combustion exhaust gases, recover it, and store and reuse the recovered CO2 without releasing it into the atmosphere, targeting facilities such as coal-fired power plants that burn large amounts of fossil fuels.

[0003] Methods for separating and recovering CO2 from combustion exhaust gases include chemical absorption methods that utilize the chemical reaction between basic compounds and CO2. In chemical absorption methods, aqueous solutions of alkanolamines, mainly monoethanolamine (MEA), are used as the basic compound as the absorbent, and the CO2 is separated and recovered by contacting this with the combustion exhaust gas (see, for example, Patent Document 1).

[0004] However, when using an aqueous MEA solution as an absorbent, repeated use involving CO2 adsorption and desorption by heating (regeneration of the absorbent solution due to CO2 release) presents a problem: MEA itself is a low-molecular-weight compound and is highly volatile, leading to its release into the environment. MEA is designated as a Class I designated chemical substance subject to the PRTR system and is considered highly harmful to humans and ecosystems, so its release into the environment was a major concern. Furthermore, absorbent solutions using aqueous MEA solutions generate a large amount of heat during CO2 adsorption, meaning that a lot of thermal energy is required for regeneration of the absorbent solution, resulting in performance that is not always satisfactory in practical use.

[0005] Therefore, in order to improve the regenerability (reduce the thermal energy during regeneration) while maintaining the CO2 absorption amount of the MEA aqueous solution, examination examples using 2-amino-2-methyl-1-propanol (AMP), which is a hindered amine with a large steric hindrance, and piperazines such as 2-methylpiperazine (2MPZ) and piperazine (PZ), which are amines with high nucleophilicity, have been reported (see, for example, Patent Document 2). However, although various absorption characteristics have been improved by the above amines, since they are all low-molecular compounds, they have high volatility, and the problems regarding the risk of environmental release have not been solved. In addition, all of the above amines are solids near room temperature, and there are problems such as solids precipitating in the absorption liquid after CO2 adsorption, and problems that solids precipitate when the concentration is increased to improve the CO2 adsorption amount.

[0006] Therefore, in the absorption liquid using an amine aqueous solution, improvement of the CO2 absorption amount and regenerability, reduction of the volatility of the amine compound, and suppression of solid precipitation are desired.

[0007] Japanese Patent Application Laid-Open No. 2009-214089 Japanese Patent Application Laid-Open No. 2008-13400

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a composition for a carbon dioxide adsorbent and an aqueous solution composition that can achieve both a CO2 absorption amount and regenerability, are excellent in the low volatility of an amino group-containing compound, and suppress solid precipitation.

[0009] As a result of intensive studies to solve the above problems, the inventors of the present invention have found that a composition for a carbon dioxide adsorbent containing an organosilicon compound having an amino group and an alkoxysilyl group and / or a silanol group in one molecule and a solvent can achieve both a CO2 absorption amount and regenerability, is excellent in the low volatility of an amine compound, and can suppress solid precipitation, and thus completed the present invention.

[0010] That is, the present invention provides: 1. A composition for a carbon dioxide adsorbent containing (A) an organosilicon compound having an amino group and an alkoxysilyl group, a silanol group or both in one molecule, and (B) a solvent; 2. The composition for a carbon dioxide adsorbent according to 1, wherein the component (A) is an organosilicon compound having an average structure represented by the following formula (1). (wherein, A 1 and A 2 are each independently an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, m is a number from 0 to 4, R 1 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, R 2 is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, and a, b, c, d, e, f, g, and h are numbers satisfying a≥0, b≥0, c≥0, d≥0, e≥0, f≥0, g≥0, h>0, and a + b + c>0.) 3. In the formula (1), A 1 is an alkylene group having 3 or 4 carbon atoms, A 2 is an alkylene group having 2 or 3 carbon atoms, R 1 is a methyl group, R 2 is a hydrogen atom, a is a number from 0 to 100, b is a number from 0 to 100, and a + b>0 is satisfied, c, d, e, f, and g are 0, and h is a number greater than 0 and 100 or less, The composition for a carbon dioxide adsorbent according to 2. 4. In the formula (1), A 1 is an alkylene group having 3 or 4 carbon atoms, A 2 is an alkylene group having 2 or 3 carbon atoms, R 1 is a methyl group, R 2 is a hydrogen atom, a, c, d, e, f, and g are 0, b is a number from 1 to 100, and h is a number greater than 0 and 100 or less, The composition for a carbon dioxide adsorbent according to 2. 5. In the formula (1), A 1 is an alkylene group having 3 or 4 carbon atoms, m is 0, R 2is a hydrogen atom, a, c, d, e, f, and g are 0, b is a number from 1 to 100, and h is a number greater than 0 and less than or equal to 100. The composition for a carbon dioxide adsorbent according to 2 above. 6. The composition for a carbon dioxide adsorbent according to any one of 1 to 5, wherein the mass reduction rate of the component (A) after heating and drying at 150°C for 3 hours is 10% by mass or less. 7. The composition for a carbon dioxide adsorbent according to any one of 1 to 6, wherein the component (B) contains water. 8. (A) An organosilicon compound having an average structure represented by the following formula (2), and (B) an aqueous solution composition containing water (In the formula, A 10 and A 20 are each independently an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, and one or more of A 10 and A 20 is a branched alkylene group having 3 to 20 carbon atoms, m is a number from 0 to 4, R 1 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, a0 is a number from 0 to 100, b0 is a number from 0 to 100, and a0 + b0 > 0 is satisfied, and h0 is a number greater than 0 and less than or equal to 100.) is provided.

[0011] The composition for a carbon dioxide adsorbent and the aqueous solution composition of the present invention contain a specific organosilicon compound and a solvent. Since the organosilicon compound has an amino group in one molecule and an alkoxysilyl group and / or a silanol group, it can achieve both a CO2 absorption amount and a regenerability, compared to an aqueous solution of a low molecular weight amine compound that has been conventionally used as a composition for a carbon dioxide adsorbent. Also, it has excellent low volatility of the amino group-containing compound and can suppress solid precipitation. The composition for a carbon dioxide adsorbent and the aqueous solution composition of the present invention having such characteristics can be suitably used as a composition for a carbon dioxide adsorbent in the treatment of exhaust gas containing acidic gases such as CO2 discharged from various facilities such as thermal power plants, steel mills, and factory boilers, or in DAC (Direct Air Capture, direct air recovery technology), etc.

[0012] The present invention will be described in detail below. The carbon dioxide adsorbent composition according to the present invention comprises (A) an organosilicon compound having an amino group and an alkoxysilyl group, a silanol group, or both in one molecule, and (B) a solvent.

[0013] [Component (A)] The organosilicon compound of component (A) is not particularly limited as long as it is an amino group-containing organosilicon compound having an amino group in one molecule and having an alkoxysilyl group and / or a silanol group, and may have a linear structure, a branched structure, or a crosslinked structure consisting of a polysiloxane skeleton. More specifically, an organosilicon compound having an average structure represented by the following formula (1) is preferred, and by using such a compound, even better CO2 absorption, regeneration, low volatility, and suppression of solid deposition can be achieved.

[0014]

[0015] In equation (1), A 1 and A 2 Each of these independently represents an unsubstituted or substituted divalent hydrocarbon group with 1 to 20 carbon atoms. 1 and A 2 The divalent hydrocarbon group having 1 to 20 carbon atoms may be linear, branched, or cyclic, and examples include alkylene groups having 1 to 20 carbon atoms, preferably 1 to 10, more preferably 1 to 6; cycloalkylene groups having 3 to 20 carbon atoms, preferably 3 to 10, more preferably 3 to 6; and arylene groups having 6 to 20 carbon atoms, preferably 6 to 10, more preferably 6 to 8. 1 and A 2Specific examples of divalent hydrocarbon groups include alkylene groups such as methylene, ethylene, trimethylene, propylene, isopropylene, tetramethylene, isobutylene, pentamethylene, isopentylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, undecamethylene, dodecamethylene, tridecamethylene, tetradecamethylene, pentademethylene, hexadecamethylene, heptadecamethylene, octademethylene, nonadecamethylene, and eicosadecylene; cycloalkylene groups such as cyclopentylene and cyclohexylene; and arylene groups such as phenylene and α-,β-naphthylene.

[0016] Furthermore, these groups may contain bonds that include heteroatoms such as O and S in their molecular chains. Specific examples of heteroatom-containing bonds include ether bonds (-O-), sulfide bonds (-S-), sulfonyl bonds (-S(=O)2-), phosphinyl bonds (-P(=O)OH-), oxo bonds (-C(=O)-), thiooxo bonds (-C(=S)-), ester bonds (-C(=O)O-), thioester bonds (-C(=O)S-), thionoester bonds (-C(=S)O-), dithioester bonds (-C(=S)S-), carbonate ester bonds (-OC(=O)O-), and thiocarbonate ester bonds (-OC(=S)O-).

[0017] Among these, A 1 As for the group, trimethylene, isobutylene, and tetramethylene groups are preferred. Also, A 2 As such, ethylene, trimethylene, and isopropylene groups are preferred. 1 and A 2 Preferably, one or more of these are branched alkylene groups having 3 to 20 carbon atoms, and more preferably are isobutylene or isopropylene groups. 1 and A 2 A preferred combination is A 1 is a trimethylene group and A 2 This is a combination of trimethylene groups, A 1 is a trimethylene group and A 2 is a combination of isopropylene groups, A 1isobutylene group and A 2 This is a combination of ethylene groups, and A 1 isobutylene group and A 2 This is a combination of isopropylene groups.

[0018] R 1 Each of these independently represents an unsubstituted or substituted monovalent hydrocarbon group with 1 to 10 carbon atoms. 1 Specific examples of the monovalent hydrocarbon group are not particularly limited, but include unsubstituted or substituted alkyl groups having 1 to 10 carbon atoms, preferably 1 to 6, more preferably 1 to 3, or unsubstituted or substituted aryl groups having 6 to 10 carbon atoms, preferably 6 to 8. The alkyl groups having 1 to 10 carbon atoms may be linear, cyclic, or branched, but linear alkyl groups are more preferred. 1 Specific examples of alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups, but methyl, ethyl, n-propyl, n-hexyl, and n-octyl groups are preferred, methyl and ethyl groups are more preferred, and methyl groups are even more preferred. Specific examples of aryl groups having 6 to 10 carbon atoms include phenyl, α-naphthyl, and β-naphthyl groups, but phenyl groups are preferred. Some or all of the hydrogen atoms in these groups may be substituted with alkyl groups having 1 to 3 carbon atoms, for example. Among these, R is preferred from the viewpoint of CO2 absorption, regeneration, low volatility, and suppression of solid deposition. 1 A methyl group is particularly preferred.

[0019] R 2 R represents a hydrogen atom and an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. 2 The alkyl group having 1 to 10 carbon atoms may be linear, cyclic, or branched, but linear alkyl groups are preferred. Preferably, it has 1 to 6 carbon atoms, more preferably 1 to 3. 2Specific examples of alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups, but methyl, ethyl, n-propyl, n-hexyl, and n-octyl groups are preferred, methyl and ethyl groups are more preferred, and methyl groups are even more preferred. Some or all of the hydrogen atoms of these groups may be substituted with alkyl groups having 1 to 3 carbon atoms, for example. Among these, R is particularly preferred from the viewpoint of CO2 absorption, regeneration, low volatility, and suppression of solid deposition. 2 A hydrogen atom is preferred.

[0020] m represents a number from 0 to 4, but from the viewpoint of CO2 absorption, regeneration, low volatility, and suppression of solid deposition, a number from 0 to 2 is preferred, a number from 0 to 1 is more preferred, and 0 is even more preferred.

[0021] Furthermore, in the present invention, a, b, c, d, e, f, g, and h represent the average number (average degree of polymerization) of each constituent unit, and are numbers that satisfy a≧0, b≧0, c≧0, d≧0, e≧0, f≧0, g≧0, h>0, and a+b+c>0. From the viewpoint of CO2 absorption, regeneration, low volatility, and suppression of solid deposition, a is preferably a number from 0 to 1,000, more preferably a number from 0 to 500, even more preferably a number from 0 to 100, and still more preferably a number from 0 to 50; b is preferably a number from 0 to 1,000, more preferably a number from 0 to 500, even more preferably a number from 0 to 100, and still more preferably a number from 0 to 50; c is preferably a number from 0 to 100, more preferably a number from 0 to 50, even more preferably a number from 0 to 10, and still more preferably 0; d is preferably a number from 0 to 1,000, more preferably a number from 0 to 500, even more preferably a number from 0 to 10, and still more preferably 0; e is preferably a number from 0 to 1,000, more preferably a number from 0 to 500, even more preferably a number from 0 to 10, and still more preferably 0. f is preferably a number between 0 and 500, more preferably a number between 0 and 100, even more preferably a number between 0 and 10, and still preferably 0. g is preferably a number between 0 and 100, more preferably a number between 0 and 50, even more preferably a number between 0 and 10, and still preferably 0. h is preferably a number greater than 0 and 1,000 or less, more preferably a number greater than 0 and 500 or less, even more preferably a number greater than 0 and 100 or less, and still preferably a number greater than 0 and 50 or less. a+b+c is preferably a number satisfying 0 < a+b+c ≤ 1,000, more preferably a number satisfying 1 ≤ a+b+c ≤ 500, and even more preferably a number satisfying 1 ≤ a+b+c ≤ 100. In this invention, the values ​​of a, b, c, d, e, f, g, and h can be determined by the methods described in the examples below.

[0022] Component (A) is more preferably an organosilicon compound having the average structure represented by the following formulas (2-1) and (2-2), even more preferably an organosilicon compound having the average structure represented by the following formula (3), and even more preferably an organosilicon compound having the average structure represented by the following formula (4). Using such a compound will result in even better CO2 absorption, regeneration, low volatility, and suppression of solid deposition. Component (A) may be used alone or in combination of two or more.

[0023] (In the formula, A 1 A 2 , m and R 1 This expresses the same meaning as above, but preferably A 1 A is an alkylene group having 3 or 4 carbon atoms. 2 R is an alkylene group having 2 or 3 carbon atoms. 1 (where a is a methyl group, a is a number between 0 and 100, b is a number between 0 and 100, and a + b > 0, and h is a number greater than 0 and less than or equal to 100.)

[0024] (In the formula, A 1 A 2 , m and R 1 This expresses the same meaning as above, but preferably A 1 and A 2 One or more of these are branched alkylene groups having 3 to 20 carbon atoms, where a is a number between 0 and 100, b is a number between 0 and 100, and a + b > 0, and h is a number greater than 0 and less than or equal to 100.

[0025] (In the formula, A 1 A 2 , m and R 1 This expresses the same meaning as above, but preferably A 1 A is an alkylene group having 3 or 4 carbon atoms. 2 R is an alkylene group having 2 or 3 carbon atoms. 1 (where is a methyl group, b is a number from 1 to 100, and h is a number greater than 0 and less than or equal to 100.)

[0026] (In the formula, A 1 and R 1 This expresses the same meaning as above, but preferably A 1 (where b is an alkylene group with 3 or 4 carbon atoms, b is a number from 1 to 100, and h is a number greater than 0 and less than or equal to 100.)

[0027] (A) Specific examples of components include, but are not limited to, those represented by the following formulas. (In the formula, a to h are the same as above.)

[0028] Component (A) can be easily obtained by known synthesis methods. For example, it can be obtained by hydrolyzing and condensing an amino group-containing alkoxysilane corresponding to the constituent unit of component (A) with other organoalkoxysilanes as needed, and removing the alcohol generated as needed. In this case, the resulting organosilicon compound may be in the form of an aqueous solution. Alternatively, it can be obtained by an equilibration reaction in the presence of a catalyst such as an alkali metal hydroxide or tetramethylammonium hydroxide, in which an amino group-containing alkoxysilane or its hydrolysis condensate corresponding to the constituent unit of component (A) is reacted with a cyclic siloxane such as octamethylcyclotetrasiloxane and / or hexamethyldisiloxane as needed. Another method is to de-alcoholize a hydroxyl-blocked dimethylpolysiloxane at both ends and an amino group-containing alkoxysilane corresponding to the constituent unit of component (A) in the presence of a catalyst such as an alkali metal hydroxide.

[0029] Among these, a method of hydrolysis and condensation of an amino group-containing alkoxysilane corresponding to the constituent unit of component (A) and, if necessary, other organoalkoxysilanes is preferred. Examples of amino group-containing alkoxysilanes used in the hydrolysis and condensation reaction include: aminomethyltrimethoxysilane, aminomethyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 8-aminooctyltrimethoxysilane, 8-aminooctyltriethoxysilane; N-2-(aminoethyl)-aminomethyltrimethoxysilane, N-2-(aminoethyl)-aminomethyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane; N-(3-trimethoxysilylpropyl)diethylenetriamine, N-(3 N-(triethoxysilylpropyl)diethylenetriamine; N-(3-trimethoxysilylpropyl)propane-1,2-diamine; N-(3-triethoxysilylpropyl)propane-1,2-diamine; N-2-(aminoethyl)-3-amino-2-methylpropyltrimethoxysilane; N-2-(aminoethyl)-3-amino-2-methylpropyltriethoxysilane; N-(2-methyl-3-trimethoxysilylpropyl)propane-1,2-diamine; N-(2-methyl-3-triethoxysilylpropyl)propane-1,2-diamine, and other amino group-containing trialkoxysilanes; Examples include aminomethylmethyldimethoxysilane, aminomethylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 8-aminooctylmethyldimethoxysilane, 8-aminooctylmethyldiethoxysilane; amino group-containing dialkoxysilanes such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane and N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane; and amino group-containing monoalkoxysilanes such as 3-aminopropyldimethylmethoxysilane and 3-aminopropyldimethylethoxysilane. These may be used individually or in combination of two or more.

[0030] Examples of organoalkoxysilanes that may be used as needed include: trialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, and propyltriethoxysilane; dialkoxysilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, dipropyldimethoxysilane, and dipropyldiethoxysilane; tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane; and monoalkoxysilanes such as trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, and triethylethoxysilane. These may be used individually or in combination of two or more.

[0031] The above-mentioned amino group-containing alkoxysilane and, if necessary, organoalkoxysilane are preferably used in molar ratios corresponding to the ratio of each constituent unit contained in the organosilicon compound of component (A). The ratio of these alkoxysilanes to water is not particularly limited, but a ratio of 1 to 20 moles of water per mole of alkoxysilane is preferred. The reaction temperature during hydrolysis condensation is not particularly limited, but -10 to 150°C is preferred to improve the reaction rate and prevent the decomposition of the organic functional groups of the silane compound. During the reaction, it is preferable to carry out the hydrolysis condensation reaction while distilling off the by-product alcohol and, if necessary, water under atmospheric pressure or reduced pressure, thereby obtaining the organosilicon compound of component (A).

[0032] [Component (B)] The solvent (B) is not particularly limited as long as it can uniformly dissolve component (A), but a protic solvent is preferred from the viewpoint of solubility, CO2 absorption amount, regeneration ability, low volatility, and effect of suppressing solid deposition. Specific examples of protic solvents include water, methanol, ethanol, isopropyl alcohol, butanol, propylene glycol, propylene glycol monomethyl ether, 2-methoxyethoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, etc., but water and ethylene glycol are preferred, and water is more preferred, from the viewpoint of solubility, CO2 absorption amount, regeneration ability, low volatility, and effect of suppressing solid deposition. Component (B) may be used alone or in combination of two or more.

[0033] The composition of the present invention may optionally contain additives such as storage stability improvers and surfactants, as long as they do not impair the effects of the present invention.

[0034] The content of component (A) in the carbon dioxide adsorbent composition of the present invention is preferably 10 to 80 parts by mass, and more preferably 20 to 70 parts by mass, per 100 parts by mass of the carbon dioxide adsorbent composition. Within this range, excellent CO2 absorption and solid deposition suppression effects are obtained.

[0035] In this case, it is preferable that the remainder after removing component (A) is component (B), more preferably 90 to 20 parts by mass of component (B) per 100 parts by mass of the carbon dioxide adsorbent composition, and even more preferably 80 to 30 parts by mass.

[0036] In the present invention, when component (B) is water (hereinafter, a composition in which component (B) is water is also referred to as an "aqueous solution composition"), it is preferable that component (A) contains an organosilicon compound having the average structure represented by the above formula (2-1), (2-2), (3), or (4). More preferably, an aqueous solution composition containing (A) an organosilicon compound having the average structure represented by the above formula (2-2) and (B) water is preferred.

[0037] The method for producing the composition of the present invention is not particularly limited, but for example, a preferred method is to synthesize component (A) by the hydrolysis condensation reaction described above, and then add component (B) to the solution after the reaction is completed at 10 to 30°C to adjust the content ratio of components (A) and (B) to a predetermined range.

[0038] In the carbon dioxide adsorbent composition of the present invention, from the viewpoint of low volatility, the mass loss (volatile content) of component (A) excluding component (B) after heating and drying at 150°C for 3 hours is preferably 10% by mass or less, more preferably less than 5% by mass, even more preferably less than 3% by mass, and still more preferably less than 1% by mass.

[0039] The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, the average structure of organosilicon compounds was determined using a 300 MHz NMR measuring device manufactured by JEOL Ltd. 1 H-NMR and 29 The molecular weight was calculated from the integrated value of the detection spectrum in Si-NMR and from the weight-average molecular weight in polystyrene equivalent obtained by GPC measurement under the following conditions. [GPC conditions] Apparatus: HLC-8220 (manufactured by Tosoh Corporation) Columns: TSKgel GMHXL-L, TSKgel G4000HXL, TSKgel G2000HXL ×2 Developing solvent: Tetrahydrofuran (THF) Flow rate: 1 mL / min Detector: RI Column oven temperature: 40°C Standard substance: Polystyrene

[0040] [1] Preparation of composition for carbon dioxide adsorbent [Example 1] 1075 g of pure water was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and 720 g of 3-aminopropylmethyldiethoxysilane was added dropwise at 25°C while stirring. After heating to 120°C to remove the by-product alcohol under atmospheric pressure, pure water was added at 25°C to adjust the composition so that the content of component (A) was 30% by mass and the content of water, the solvent (B), was 70% by mass of the remainder, thereby obtaining composition 1 for carbon dioxide adsorbent. The organosilicon compound A1 contained in the obtained composition 1 for carbon dioxide adsorbent had an average structure represented by the following formula.

[0041]

[0042] [Example 2] Except that the amounts of 3-aminopropylmethyldiethoxysilane and pure water used were changed in Example 1, the content of component (A) was set to 45% by mass, and the content of water, which is the solvent (B), was set to 55% by mass of the remainder, a carbon dioxide adsorbent composition 2 was obtained in the same manner as in Example 1. The organosilicon compound A2 contained in the obtained carbon dioxide adsorbent composition 2 had an average structure represented by the following formula.

[0043]

[0044] [Example 3] In the same manner as in Example 1, except that the amounts of 3-aminopropylmethyldiethoxysilane and pure water used were changed, and the content of component (A) was set to 60% by mass and the content of water, which is the solvent (B), was set to 40% by mass of the remainder, a carbon dioxide adsorbent composition 3 was obtained. The organosilicon compound A3 contained in the obtained carbon dioxide adsorbent composition 3 had an average structure represented by the following formula.

[0045]

[0046] [Example 4] A carbon dioxide adsorbent composition 4 was obtained in the same manner as in Example 1, except that 3-aminopropylmethyldiethoxysilane was replaced with N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, the content of component (A) was changed to 60% by mass, and the content of water, the solvent (B), was changed to 40% by mass of the remainder. The organosilicon compound A4 contained in the obtained carbon dioxide adsorbent composition 4 had an average structure represented by the following formula.

[0047]

[0048] [Example 5] A carbon dioxide adsorbent composition 5 was obtained in the same manner as in Example 1, except that 3-aminopropylmethyldiethoxysilane was replaced with 3-aminopropyltriethoxysilane. The organosilicon compound A5 contained in the obtained carbon dioxide adsorbent composition 5 had an average structure represented by the following formula.

[0049]

[0050] [Example 6] A carbon dioxide adsorbent composition 6 was obtained in the same manner as in Example 1, except that 3-aminopropylmethyldiethoxysilane was replaced with N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. The organosilicon compound A6 contained in the obtained carbon dioxide adsorbent composition 6 had an average structure represented by the following formula.

[0051]

[0052] [Example 7] In Example 1, 3-aminopropylmethyldiethoxysilane was used with N 1 A carbon dioxide adsorbent composition 7 was obtained in the same manner as in Example 1, except that it was changed to (3-trimethoxysilylpropyl)diethylenetriamine. The organosilicon compound A7 contained in the obtained carbon dioxide adsorbent composition 7 had an average structure represented by the following formula.

[0053]

[0054] [Example 8] In Example 7, N 1 A carbon dioxide adsorbent composition 8 was obtained in the same manner as in Example 7, except that the amounts of (3-trimethoxysilylpropyl)diethylenetriamine and pure water used were changed, and the content of component (A) was set to 45% by mass and the content of water, the solvent (B), was set to 55% by mass of the remainder. The organosilicon compound A8 contained in the obtained carbon dioxide adsorbent composition 8 had an average structure represented by the following formula.

[0055]

[0056] [Example 9] In Example 1, 3-aminopropylmethyldiethoxysilane was used with N 1 A carbon dioxide adsorbent composition 9 was obtained in the same manner as in Example 1, except that it was changed to -(3-trimethoxysilylpropyl)propane-1,2-diamine. The organosilicon compound A9 contained in the obtained carbon dioxide adsorbent composition 9 had an average structure represented by the following formula.

[0057]

[0058] [Example 10] A carbon dioxide adsorbent composition 10 was obtained in the same manner as in Example 1, except that 3-aminopropylmethyldiethoxysilane was replaced with N-2-(aminoethyl)-3-amino-2-methylpropyltrimethoxysilane. The organosilicon compound A10 contained in the obtained carbon dioxide adsorbent composition 10 had an average structure represented by the following formula.

[0059]

[0060] [Example 11] In Example 1, 3-aminopropylmethyldiethoxysilane was N 1 A carbon dioxide adsorbent composition 11 was obtained in the same manner as in Example 1, except that it was changed to -(2-methyl-3-trimethoxysilylpropyl)propane-1,2-diamine. The organosilicon compound A11 contained in the obtained carbon dioxide adsorbent composition 11 had an average structure represented by the following formula.

[0061]

[0062] [Example 12] A carbon dioxide adsorbent composition 12 was obtained in the same manner as in Example 1, except that 3-aminopropylmethyldiethoxysilane was replaced with 3-aminopropyldimethylethoxysilane. The organosilicon compound A12 contained in the obtained carbon dioxide adsorbent composition 12 had an average structure represented by the following formula.

[0063]

[0064] [Example 13] 1075 g of pure water was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer. 540 g of 3-aminopropylmethyldiethoxysilane and 128 g of methyltrimethoxysilane were added dropwise at 25°C while stirring. The mixture was then heated to 120°C to remove the by-product alcohol under atmospheric pressure. Pure water was then added at 25°C to adjust the composition so that the content of component (A) was 20% by mass and the content of the solvent (B), water, was 80% by mass of the remainder, thereby obtaining carbon dioxide adsorbent composition 13. The organosilicon compound A13 contained in the obtained carbon dioxide adsorbent composition 13 had an average structure represented by the following formula.

[0065]

[0066] [Example 14] 1075 g of pure water was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer. 573 g of 3-aminopropylmethyldiethoxysilane and 90 g of dimethyldimethoxysilane were added dropwise at 25°C while stirring. The mixture was then heated to 120°C to remove the by-product alcohol under atmospheric pressure. Pure water was then added at 25°C to adjust the composition so that the content of component (A) was 20% by mass and the content of the solvent (B), water, was 80% by mass of the remainder, thereby obtaining carbon dioxide adsorbent composition 14. The organosilicon compound A14 contained in the obtained carbon dioxide adsorbent composition 14 had an average structure represented by the following formula.

[0067]

[0068] [Example 15] 1075 g of pure water was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer. 504 g of 3-aminopropylmethyldiethoxysilane and 235 g of tetraethoxysilane were added dropwise at 25°C while stirring. The mixture was then heated to 120°C to remove the by-product alcohol under atmospheric pressure. Pure water was then added at 25°C to adjust the composition so that the content of component (A) was 30% by mass and the content of water (B), the solvent, was 70% by mass of the remainder, thereby obtaining carbon dioxide adsorbent composition 15. The organosilicon compound A15 contained in the obtained carbon dioxide adsorbent composition 15 had an average structure represented by the following formula.

[0069]

[0070] [Example 16] 1075 g of pure water was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer. 661 g of 3-aminopropylmethyldiethoxysilane and 40 g of trimethylmethoxysilane were added dropwise at 25°C while stirring. The mixture was then heated to 120°C to remove the by-product alcohol under atmospheric pressure. Pure water was then added at 25°C to adjust the composition so that the content of component (A) was 30% by mass and the content of the solvent (B), water, was 70% by mass of the remainder, thereby obtaining carbon dioxide adsorbent composition 16. The organosilicon compound A16 contained in the obtained carbon dioxide adsorbent composition 16 had an average structure represented by the following formula.

[0071]

[0072] [Example 17] 1075 g of pure water was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and 720 g of 3-aminopropylmethyldiethoxysilane was added dropwise at 25°C while stirring. The mixture was then heated to 120°C to remove the by-product alcohol and water under atmospheric pressure, and then ethylene glycol was added at 25°C to adjust the composition so that (A) the content of the amino group-containing organosilicon compound component was 30% by mass and (B) the content of the solvent, ethylene glycol, was 70% by mass of the remainder, thereby obtaining carbon dioxide adsorbent composition 17. The organosilicon compound A17 contained in the obtained carbon dioxide adsorbent composition 17 had an average structure represented by the following formula.

[0073]

[0074] [Comparative Example 1] A composition 18 for carbon dioxide adsorbent was obtained by adjusting the composition so that monoethanolamine (MEA), which is a comparative amine compound, accounts for 30% by mass, and the content of water, which is the solvent (B), accounts for 70% by mass of the remainder.

[0075] [Comparative Example 2] A carbon dioxide adsorbent composition 19 was obtained in the same manner as in Comparative Example 1, except that monoethanolamine (MEA) was replaced with 2-amino-2-methyl-1-propanol (AMP).

[0076] [Comparative Example 3] A carbon dioxide adsorbent composition 20 was obtained in the same manner as in Comparative Example 1, except that monoethanolamine (MEA) was replaced with tetraethylenepentamine (TEPA).

[0077] [Comparative Example 4] A carbon dioxide adsorbent composition 21 was obtained in the same manner as in Comparative Example 1, except that monoethanolamine (MEA) was replaced with piperazine (PZ). However, although the amine compound was dissolved in this carbon dioxide adsorbent composition 21 immediately after preparation due to the heat of dissolution, when cooled to 25°C, a solid derived from the amine compound (PZ) precipitated, and it was not possible to obtain a solution in which the amine compound was uniformly dissolved.

[0078] The carbon dioxide adsorbent compositions prepared in Examples 1 to 17 and Comparative Examples 1 to 3 were evaluated as follows. The results are shown in Tables 1 and 2. [Volatile content of component (A)] The mass loss rate (volatile content) of component (A) was calculated by subtracting the theoretical content of solvent (B) from the measured values ​​by the residual heat method after heating and drying the carbon dioxide adsorbent compositions on an aluminum petri dish at 105°C and 150°C for 3 hours. A smaller value indicates lower volatility. [CO2 absorption amount] The amount of CO2 absorbed per gram of the carbon dioxide adsorbent composition was measured. The CO2 absorption amount was measured under CO2 partial pressure of 1 MPa, temperature of 40°C, and 5 hours, and calculated from the mass increase of the carbon dioxide adsorbent composition at that time. A larger value indicates better CO2 absorption. [Regenerative properties] The regenerative properties were evaluated by measuring the amount of heat generated when CO2 was absorbed by the carbon dioxide adsorbent composition. The measurement conditions were a CO2 partial pressure of 1 MPa, a temperature of 40°C, and 5 hours during which CO2 was absorbed into the carbon dioxide adsorbent composition. The amount of heat generated per mole of absorbed CO2 was then calculated. A SETARAM C80 calorimeter was used to measure the amount of heat generated. A smaller value indicates better regeneration. [Suppression effect of solid precipitation] After the above CO2 absorption measurement, the degree of solid precipitation in the carbon dioxide adsorbent composition was visually checked. If no solid precipitation was observed, it was evaluated as having excellent suppression effect of solid precipitation, and was rated "○". If significant solid precipitation was observed, it was evaluated as "×".

[0079]

[0080]

[0081] As shown in Tables 1 and 2, the carbon dioxide adsorbent compositions 1 to 17 of the present invention obtained in Examples 1 to 17 showed low or almost no volatile content of component (A) at 105°C and 150°C, demonstrating excellent low volatility, CO2 absorption capacity, regeneration properties, and suppression of solid precipitation. On the other hand, the carbon dioxide adsorbent compositions 18 to 20 prepared in Comparative Examples 1 to 3, which contained low molecular weight amine compounds, all showed that most of the amine compound volatilized under heating conditions of 105°C or 150°C, and also exhibited insufficient CO2 absorption capacity, regeneration properties, and suppression of solid precipitation. Furthermore, in Comparative Example 4, composition 21 containing an amine compound (PZ) precipitated solids derived from the amine compound, and it was not possible to obtain a solution in which the amine compound was uniformly dissolved.

[0082] As described above, the carbon dioxide adsorbent compositions and aqueous solutions of Examples 1 to 17 can achieve both CO2 absorption capacity and regeneration properties, which was difficult with conventional technology, and also exhibit excellent low volatility of amino group-containing compounds, thereby suppressing solid deposition.

Claims

1. A composition for carbon dioxide adsorbent comprising (A) an organosilicon compound having an amino group and an alkoxysilyl group, a silanol group, or both in one molecule, and (B) a solvent.

2. The carbon dioxide adsorbent composition according to claim 1, wherein component (A) is an organosilicon compound having an average structure represented by the following formula (1). (In the formula, A 1 and A 2 Each is independently an unsubstituted or substituted divalent hydrocarbon group with 1 to 20 carbon atoms, m is a number from 0 to 4, and R 1 Each of these is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R 2 (where a is a hydrogen atom, or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, and a, b, c, d, e, f, g, and h are numbers satisfying a≧0, b≧0, c≧0, d≧0, e≧0, f≧0, g≧0, h>0, and a+b+c>0.) 3. In the above formula (1), A 1 However, it is an alkylene group with 3 or 4 carbon atoms, A 2 However, it is an alkylene group with 2 or 3 carbon atoms, R 1 However, it is a methyl group, R 2 The carbon dioxide adsorbent composition according to claim 2, wherein a is a hydrogen atom, a is a number from 0 to 100, b is a number from 0 to 100 and satisfies a + b > 0, c, d, e, f, and g are 0, and h is a number greater than 0 and less than or equal to 100.

4. In the formula (1), A 1 is an alkylene group having 3 or 4 carbon atoms, and A 2 is an alkylene group having 2 or 3 carbon atoms, R 1 is a methyl group, R 2 is a hydrogen atom, a, c, d, e, f and g are 0, b is a number from 1 to 100, and h is a number greater than 0 and not exceeding 100. The composition for a carbon dioxide adsorbent according to claim 2.

5. In formula (1) above, A 1 However, it is an alkylene group with 3 or 4 carbon atoms, m is 0, and R 2 The carbon dioxide adsorbent composition according to claim 2, wherein a is a hydrogen atom, a, c, d, e, f, and g are 0, b is a number from 1 to 100, and h is a number greater than 0 and less than or equal to 100.

6. The carbon dioxide adsorbent composition according to any one of claims 1 to 5, wherein the mass reduction rate of component (A) after heating and drying at 150°C for 3 hours is 10% by mass or less.

7. The carbon dioxide adsorbent composition according to any one of claims 1 to 6, wherein the component (B) comprises water.

8. An aqueous composition comprising (A) an organosilicon compound having an average structure represented by the following formula (2), and (B) water. (In the formula, A 10 and A 20 Each of these is independently an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, and A 10 and A 20 One or more of these are branched alkylene groups with 3 to 20 carbon atoms, m is a number from 0 to 4, and R 1 Each of these is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, where a0 is a number between 0 and 100, b0 is a number between 0 and 100, and a0 + b0 > 0, and h0 is a number greater than 0 and less than or equal to 100.

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