Compositions and aqueous solutions for carbon dioxide adsorbents

Abstract

To provide a carbon dioxide adsorbent composition that achieves both high CO2 absorption capacity and regenerative properties, exhibits excellent low volatility of amino group-containing compounds, and suppresses solid precipitation. [Solution] (A) an organosilicon compound having an average structure represented by the following formula (1), in which one molecule contains an amino group, an alkoxysilyl group, a silanol group, or both, and (B) a solvent, comprising a composition for carbon dioxide adsorbent. TIFF2026088569000030.tif17166 (in the formula, A 1 and A 2 m is a divalent hydrocarbon group with 1 to 20 carbon atoms, m is a number from 0 to 4, and R 1 R is a monovalent hydrocarbon group having 1 to 10 carbon atoms. 2 (where a is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and a to 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.)

Description

[Technical Field]

[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. [Background technology]

[0002] In recent years, the impact of greenhouse gases, including carbon dioxide (CO2), has been recognized 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 burning 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 an MEA aqueous solution is used as an absorbent, during repeated use by repeatedly adsorbing CO2 and desorbing CO2 by heating (regenerating the absorbent accompanied by the release of CO2), since MEA itself is a low-molecular compound, it has a high volatility and there is a problem that it is released into the environment. MEA is designated as a Class I Specified Chemical Substance that is a highly toxic substance and subject to the PRTR system, and is considered to be highly harmful to humans and the ecosystem. Therefore, its release into the environment has been a major concern. In addition, the absorbent using an MEA aqueous solution has a problem that the amount of heat generated during CO2 adsorption is large, that is, a large amount of thermal energy is required for regeneration of the absorbent. Therefore, it did not necessarily have satisfactory performance 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 2-methylpiperazine (2MPZ), piperazine (PZ), etc. as piperazines with high nucleophilicity have been reported (for example, see Patent Document 2). However, although various absorption characteristics were improved by the above amines, since they are all low-molecular compounds, they still have high volatility, and the problem regarding the risk of environmental release has 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 absorbent after CO2 adsorption, and problems that solids precipitate when the concentration is increased to improve the CO2 adsorption amount.

[0006] Therefore, in the absorbent 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.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

[0008] This invention has been made in view of the above circumstances, and aims to provide a carbon dioxide adsorbent composition and an aqueous solution composition that can achieve both CO2 absorption capacity and regeneration, and that exhibits excellent low volatility of amino group-containing compounds and suppresses solid precipitation. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the present inventors have found that a composition for carbon dioxide adsorbent containing an organosilicon compound having an amino group in one molecule and an alkoxysilyl group and / or silanol group, and a solvent, can achieve both high CO2 absorption capacity and regeneration properties, and also exhibits excellent low volatility of the amine compound, thereby suppressing solid deposition, and have completed the present invention.

[0010] In other words, the present invention is 1. (A) an organosilicon compound having an amino group, an alkoxysilyl group, a silanol group, or both in one molecule, and (B) a solvent, a composition for carbon dioxide adsorbent, 2. The carbon dioxide adsorbent composition according to claim 1, wherein the component (A) is an organosilicon compound having an average structure represented by the following formula (1). [ka] (In the formula, A 1 and A 2 Each of these is independently a divalent hydrocarbon group with 1 to 20 carbon atoms, either unsubstituted or substituted, where 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 2is 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 not exceeding 100. 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 not exceeding 100. 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 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 2 6. The mass reduction rate of the component (A) after heating and drying at 150 ° C for 3 hours is ¹Ÿ 10 mass%. The composition for a carbon dioxide adsorbent according to any one of 1 to 5 7. The component (B) contains water. The composition for a carbon dioxide adsorbent according to any one of 1 to 6 8. (A) An organosilicon compound having an average structure represented by the following formula (2), and (B) an aqueous solution composition containing water

Chemical formula

[0011] The carbon dioxide adsorbent composition and aqueous solution composition of the present invention contain a specific organosilicon compound and a solvent, and since the organosilicon compound has an amino group in one molecule and also has an alkoxysilyl group and / or a silanol group, it is possible to achieve both CO2 absorption capacity and regeneration properties compared to aqueous solutions of low molecular weight amine compounds that have been conventionally used as carbon dioxide adsorbent compositions, and it also has the characteristic of having low volatility of the amino group-containing compound and being able to suppress solid deposition. The carbon dioxide adsorbent composition and aqueous solution composition of the present invention, having such properties, can be suitably used as a carbon dioxide adsorbent composition for treating exhaust gases containing acidic gases such as CO2 emitted from various facilities such as thermal power plants, steel mills, and factory boilers, or in DAC (Direct Air Capture) technology. [Modes for carrying out the invention]

[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] [(A) component] 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 the average structure represented by the following formula (1) is preferred, and using such a compound will further improve CO2 absorption, regeneration, low volatility, and suppression of solid deposition.

[0014] [ka]

[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. A 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. A 1 and A 2 Specific 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 in their molecular chains that include heteroatoms such as O and S. Specific examples of bonds containing heteroatoms 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 bonds (-OC(=O)O-), and thiocarbonate bonds (-OC(=S)O-).

[0017] Among these, A 1 Preferably, trimethylene, isobutylene, and tetramethylene groups are used. Also, A 2 As such, ethylene, trimethylene, and isopropylene groups are preferred. A 1 and A 2 Preferably, one or more of these are branched alkylene groups having 3 to 20 carbon atoms, and more preferably isobutylene or isopropylene groups. A 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 1 isobutylene 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. R 1Specific examples of monovalent hydrocarbon groups include, but are not limited to, 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. Alkyl alkyl groups having 1 to 10 carbon atoms may be linear, cyclic, or branched, but linear alkyl groups are more preferred. R 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. Furthermore, specific examples of aryl groups having 6 to 10 carbon atoms include phenyl, α-naphthyl, and β-naphthyl groups, but the phenyl group is preferred. Furthermore, some or all of the hydrogen atoms in these groups may be substituted with, for example, alkyl groups having 1 to 3 carbon atoms. Among these, R 1 A methyl group is particularly preferred.

[0019] R 2 This represents a hydrogen atom and an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. R 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. R 2 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. Furthermore, some or all of the hydrogen atoms in these groups may be substituted with, for example, alkyl groups having 1 to 3 carbon atoms. Among these, in particular, from the viewpoint of CO2 absorption, regeneration, low volatility, and suppression of solid deposition, R 2 A hydrogen atom is preferred.

[0020] m represents a number from 0 to 4, but from the viewpoint of CO2 absorption amount, regenerativeness, low volatility, and effect of suppressing 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 between 0 and 1,000, more preferably a number between 0 and 500, even more preferably a number between 0 and 100, and still more preferably a number between 0 and 50. b is preferably a number between 0 and 1,000, more preferably a number between 0 and 500, even more preferably a number between 0 and 100, and still more preferably a number between 0 and 50. c 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 even more preferably 0. d is preferably a number between 0 and 1,000, more preferably a number between 0 and 500, even more preferably a number between 0 and 10, and still most preferably 0. e is preferably a number between 0 and 1,000, more preferably a number between 0 and 500, even more preferably a number between 0 and 10, and still most 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 even more 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 most preferably 0. h is preferably a number greater than 0 and less than or equal to 1,000, more preferably a number greater than 0 and less than or equal to 500, even more preferably a number greater than 0 and less than or equal to 100, and still more preferably a number greater than 0 and less than or equal to 50. For a + b + c, a number satisfying 0 < a + b + c ≤ 1,000 is preferred, a number satisfying 1 ≤ a + b + c ≤ 500 is more preferred, and a number satisfying 1 ≤ a + b + c ≤ 100 is even more preferred. In the present invention, the values of a, b, c, d, e, f, g, and h can be determined by the method described in the examples below.

[0022] As the component (A), an organosilicon compound having an average structure represented by the following formulas (2-1) and (2-2) is more preferred, an organosilicon compound having an average structure represented by the following formula (3) is even more preferred, and an organosilicon compound having an average structure represented by the following formula (4) is even more preferably used. By using such a compound, a better CO2 absorption amount, regeneration property, low volatility, and suppression effect of solid precipitation can be exhibited. The component (A) may be used alone or in combination of two or more.

[0023]

Chemical formula

[0024]

Chemical formula

[0025] [ka] (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 between 1 and 100, and h is a number greater than 0 and less than or equal to 100.)

[0026] [ka] (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. [ka] (In the formula, a to h are the same as above.)

[0028] Component (A) can be readily 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 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, if necessary. Alternatively, it can be obtained by de-alcoholizing a dimethylpolysiloxane with hydroxyl groups blocked 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 preferred method involves hydrolysis and condensation of an amino group-containing alkoxysilane corresponding to the constituent unit of component (A) and, if necessary, other organoalkoxysilanes. Examples of amino group-containing alkoxysilanes used in hydrolysis condensation reactions 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 -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; 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; Amino group-containing monoalkoxysilanes such as 3-aminopropyldimethylmethoxysilane and 3-aminopropyldimethylethoxysilane These can be used individually or in combination of two or more.

[0030] Examples of organoalkoxysilanes 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; Monoalkoxysilanes such as trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, and triethylethoxysilane These can be used individually or in combination of two or more.

[0031] The above-mentioned amino group-containing alkoxysilane, and organoalkoxysilane used as needed, are preferably used in molar ratios corresponding to the ratio of each constituent unit contained in the organosilicon compound of component (A). Furthermore, while the ratio of these alkoxysilanes to water is not particularly limited, 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] [(B) Component] (B) The solvent 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, and glycerin. However, from the viewpoint of solubility, CO2 absorption, regeneration, low volatility, and suppression of solid precipitation, water and ethylene glycol are preferred, and water is more preferred. Note that 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 an 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 an 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. [Examples]

[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 300MHz NMR spectrometer 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 terms obtained by GPC measurement under the following conditions. [GPC conditions] Equipment: HLC-8220 (manufactured by Tosoh Corporation) Columns: TSKgel GMHXL-L, TSKgel G4000HXL, TSKgel G2000HXL ×2 Developing solvent: Tetrahydrofuran (THF) Flow rate: 1mL / min Detector: RI Column constant temperature bath temperature: 40℃ Standard material: Polystyrene

[0040] [1] Production of compositions for carbon dioxide adsorbents [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. The mixture was then heated to 120°C to remove the by-product alcohol under atmospheric pressure, and then 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 the solvent (B), water, was 70% by mass of the remainder, thereby obtaining carbon dioxide adsorbent composition 1. The organosilicon compound A1 contained in the obtained carbon dioxide adsorbent composition 1 had an average structure represented by the following formula.

[0041] [ka]

[0042] [Example 2] Composition 2 for carbon dioxide adsorbent was obtained 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 45% by mass and the content of water, the solvent (B), was set to 55% by mass of the remainder. The organosilicon compound A2 contained in the obtained carbon dioxide adsorbent composition 2 had an average structure represented by the following formula.

[0043] [ka]

[0044] [Example 3] In Example 1, composition 3 for carbon dioxide adsorbent was obtained 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, the solvent (B), was set to 40% by mass of the remainder. The organosilicon compound A3 contained in the obtained carbon dioxide adsorbent composition 3 had an average structure represented by the following formula.

[0045] [ka]

[0046] [Example 4] In Example 1, 3-aminopropylmethyldiethoxysilane was replaced with N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and 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. Otherwise, composition 4 for carbon dioxide adsorbent was obtained in the same manner as in Example 1. The organosilicon compound A4 contained in the obtained carbon dioxide adsorbent composition 4 had an average structure represented by the following formula.

[0047] [ka]

[0048] [Example 5] In Example 1, composition 5 for carbon dioxide adsorbent 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] [ka]

[0050] [Example 6] In Example 1, composition 6 for carbon dioxide adsorbent 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] [ka]

[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] [ka]

[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, so that the content of component (A) was 45% by mass and the content of water, the solvent (B), was 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] [ka]

[0056] [Example 9] In Example 1, 3-aminopropylmethyldiethoxysilane was used with N1 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] [ka]

[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] [ka]

[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] [ka]

[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] [ka]

[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] [ka]

[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] [ka]

[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 the solvent (B), water, 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] [ka]

[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] [ka]

[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] [ka]

[0074] [Comparative Example 1] Composition 18 for carbon dioxide adsorbent was obtained by adjusting the composition so that monoethanolamine (MEA), a comparative amine compound, was present at 30% by mass, and the content of water, the solvent (B), was 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] In Comparative Example 1, composition 21 for carbon dioxide adsorbent 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 1-17 and Comparative Examples 1-3 were evaluated as follows. The results are shown in Tables 1 and 2. [Volatile components of (A)] The above carbon dioxide adsorbent composition was heated and dried on an aluminum petri dish at 105°C and 150°C for 3 hours. The theoretical content of solvent (B) was removed from the measured values ​​using the residual weight method, and the mass loss rate (volatile content) of component (A) was calculated. A smaller value indicates lower volatility. [CO2 absorption amount] The amount of CO2 absorbed per gram of the above-mentioned carbon dioxide adsorbent composition was measured. The CO2 absorption was measured under the following conditions: CO2 partial pressure of 1 MPa, temperature of 40°C, and 5 hours. CO2 was absorbed into the carbon dioxide adsorbent composition, and the amount was calculated from the increase in mass of the carbon dioxide adsorbent composition during this time. A larger value indicates better CO2 absorption. [Reproducibility] The regeneration potential was evaluated by measuring the amount of heat generated when CO2 was absorbed by the above-mentioned carbon dioxide adsorbent composition. The measurement conditions were a CO2 partial pressure of 1 MPa, a temperature of 40°C, and 5 hours under which CO2 was absorbed by the carbon dioxide adsorbent composition. The amount of heat generated per mole of absorbed CO2 was calculated. A SETARAM C80 calorimeter was used to measure the heat generation. A smaller value indicates better regeneration potential. [Effect of suppressing solid precipitation] After measuring the CO2 absorption amount as described above, the degree of solid precipitation in the carbon dioxide adsorbent composition was visually inspected. If no solid precipitation was observed, it was evaluated as having excellent solid precipitation suppression effect, and was evaluated as "○". If significant solid precipitation was observed, it was evaluated as "×".

[0079] [Table 1]

[0080] [Table 2]

[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 have little to no volatile content of component (A) at 105°C and 150°C, and exhibit excellent low volatility, CO2 absorption capacity, regeneration properties, and suppression of solid deposition. On the other hand, in Comparative Examples 1 to 3, the carbon dioxide adsorbent compositions 18 to 20, which contained low molecular weight amine compounds, all showed that most of the amine compounds volatilized under heating conditions of 105°C or 150°C, and that their CO2 absorption capacity, regeneration properties, and inhibitory effect on solid deposition were insufficient. In addition, in Comparative Example 4, composition 21 containing the amine compound (PZ) precipitated a solid 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 techniques, 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 the component (A) is an organosilicon compound having an average structure represented by the following formula (1). 【Chemistry 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 less than or equal to 100. The composition for a carbon dioxide adsorbent according to claim 2.

5. In the above formula (1), 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 claim 1, 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 claim 1, wherein the (B) component comprises water.

8. (A) an organosilicon compound having an average structure represented by the following formula (2), and (B) an aqueous solution composition containing water. 【Chemistry 2】 (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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