Development of co2 capture and separation technology using amine-based absorbent having high oxidation resistance

Abstract

[Problem to be Solved] To provide a CO2 absorbent having high oxidation resistance. [Solution] A carbon dioxide absorbent comprising a compound represented by formula (I).

Description

Development of CO₂ Separation and Recovery Technology Using a Highly Oxidation-Resistant Amine-Based Absorbent

[0001] The present invention relates to a novel carbon dioxide absorbent, a method for recovering carbon dioxide using the same, and a novel compound that can be used as the carbon dioxide absorbent.

[0002] Reduction of carbon dioxide, which is regarded as one of the causes of global warming, has become an important issue worldwide. Among them, a large portion of carbon dioxide emissions is considered to come from thermal power generation that uses oil, coal, etc. as energy sources.

[0003] Carbon dioxide capture and storage (CCS) is currently one of the most effective methods for reducing CO₂ in exhaust gases. In addition, technological development is underway to reduce the amount of carbon dioxide in the atmosphere by recovering and storing the carbon dioxide that has been emitted until now by directly capturing carbon dioxide in the atmosphere, known as Direct Air Capture (DAC). The DAC technology is also required for improving air quality to maintain human health and cognitive functions in a closed environment such as a spaceship (Non-Patent Document 1). ２

[0004] The chemical absorption method using an amine absorbent is a powerful technique for separating and recovering CO₂ from low-concentration CO₂-containing gases (Non-Patent Document 2). On the other hand, since most of the desorption of CO₂ from the amine absorbent that has absorbed CO₂ is carried out by heating, the α-position C-H bond of the amino group is easily auto-oxidized and deteriorated, and there is concern that the performance of the absorbent may decrease during multiple CO₂ absorption and desorption cycles. ２ ２ ２ ２ ２ ２

[0005] In recent years, it has been reported by Inagaki that m-xylenediamine (Compound 1 in FIG. 1) is an excellent CO₂ absorbent (Non-Patent Document 3). However, when investigations were carried out to develop a DAC technology using Compound 1, it was found that there were problems with oxidation durability and the sublimability of the CO₂ adduct 2 (FIG. 1). ２ ２

[0006] S. Satyapal, et al. Energy & Fuels 2001, 15, 250.N. Muntaha, et al. ACS Omega 2022, 7, 33680.F. Inagaki, et al. J. Am. Chem. Soc. 2017, 139, 4639.

[0007] The present inventors have developed a CO2 compound with high oxidation resistance. ２ The purpose is to provide an absorbent.

[0008] To solve the above problems, the inventors focused on quaternary alkylamines in which radicals cannot be mechanically generated at the α-carbon of the amino group. The inventors then designed and synthesized compounds such as a diamine (compound a in Figure 1) in which two methyl groups are introduced at both benzyl positions of compound 1 in Figure 1, and a biphenyl derivative (compound b in Figure 1) in which a phenyl group is introduced at the m-position of the benzene ring, thereby creating a highly oxidation-resistant CO2. ２ With the aim of developing a separation and recovery process (see Figure 1b), the present invention was completed.

[0009] That is, the present invention has the following configuration: [1] A carbon dioxide absorbent comprising a compound represented by the following formula (I). (In the formula, R １ ~R ４ Each is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups; R ５ m is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups at each occurrence; m is an integer from 0 to 3; when m is 1 or greater, R ５ NH ２ -CR １ R ２ - is bonded at one or more of the ortho, meta, or para positions on the benzene ring relative to the bonded position (however, NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４(Excluding the ortho position between -) ) [2] The carbon dioxide absorbent described in [1], wherein m is 0. [3] R ５ The carbon dioxide absorbent according to [1], wherein m is a phenyl group which may have substituents. [4] m is 1, R ５ NH ２ -CR １ R ２ A carbon dioxide absorbent according to [3], wherein the - is bonded at the meta position on the benzene ring relative to the bonded position. [5] A carbon dioxide absorbent according to any one of [1] to [4], wherein a compound represented by formula (I) is supported on a carrier. [6] A carbon dioxide absorbent according to [5], wherein the carrier is γ-alumina. [7] A method for recovering carbon dioxide from a gas, comprising the steps of preparing a carbon dioxide absorbent containing a compound represented by the following formula (I); and (In the formula, R １ ~R ４ Each is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups; R ５ m is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups at each occurrence; m is an integer from 0 to 3; when m is 1 or greater, R ５ NH ２ -CR １ R ２ - is bonded at one or more of the ortho, meta, or para positions on the benzene ring relative to the bonded position (however, NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ (Excluding the ortho position between -) A method for recovering carbon dioxide, comprising the step of recovering carbon dioxide by bringing the gas into contact with the carbon dioxide absorbent. [8] The recovery method according to [7], wherein m is 0. [9] R ５The recovery method according to [7], wherein is a phenyl group which may have substituents.

[10] The recovery method according to any one of [7] to [9], wherein the compound represented by formula (I) is supported on a carrier.

[11] The recovery method according to

[10] , wherein the carrier is γ-alumina.

[12] The compound represented by the following formula (II). (In the formula, R １ ~R ４ Each is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups; R ａ Each of these is independently selected from the group consisting of optionally substituted alkyl groups, heteroaromatic rings, cyano groups, ester groups, ether groups, nitro groups, and perfluoroalkyl groups at each instance; n is an integer from 0 to 5; s is an integer from 1 to 3; the phenyl group in formula (II) is NH ２ -CR １ R ２ - is bonded at one or more of the ortho, meta, or para positions on the benzene ring relative to the bonded position (however, NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ (Excluding the ortho position between -s.)

[0010] The present invention provides a CO2 with high oxidation resistance. ２ It is possible to provide an absorbent. The carbon dioxide absorbent of the present invention has high oxidation resistance, so it can be regenerated after carbon dioxide is removed and can be used repeatedly for carbon dioxide absorption and desorption.

[0011] A schematic diagram (a) of direct air recovery using m-xylenediamine and a schematic diagram of a non-limiting example of the carbon dioxide absorbent of the present invention are shown. The results of a carbon dioxide adsorption / desorption test using compound 2b of the present invention are shown. Embodiments for carrying out the invention

[0012] 1. Carbon Dioxide Absorbent One embodiment of the present invention is a carbon dioxide absorbent comprising a compound represented by the following formula (I) (hereinafter also referred to as "the carbon dioxide absorbent of the present invention").

[0013]

[0014] In equation (I), R １ ~R ４ Each is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups. １ ~R ４ By introducing these groups into all of them, it is possible to create structures such as quaternary alkylamines in which radicals cannot be mechanically generated at the α-carbon of the amino group, thereby achieving CO with high oxidation resistance. ２ It is possible to provide an absorbent. Furthermore, R １ ~R ４ By introducing these groups, it is also possible to reduce the temperature required for carbon dioxide desorption.

[0015] Preferably, the alkyl group may have substituents is a C1 to C18 alkyl group, more preferably a C1 to C4 alkyl group, and preferably includes, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, and the like. Substituents on the alkyl group include halogens such as fluorine or chlorine, alkoxy groups, esters, and phenyl groups. Examples of alkyl groups with substituents include a benzyl group and a methoxymethyl group.

[0016] Examples of aryl groups include phenyl, biphenyl, naphthyl, phenantrenyl, and anthracenyl groups, with phenyl being preferred.

[0017] The substituents on the aryl group include alkyl groups which may have substituents (preferably alkyl groups having 1 to 6 carbon atoms which may have substituents, more preferably alkyl groups having 1 to 4 carbon atoms which may have substituents), and aryl groups.

[0018] R ５ Independently, at each instance of appearance, is selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups.

[0019] R ５ The alkyl group which may have substituents is R １ ~R ４ This is similar to alkyl groups that may have substituents, as detailed below.

[0020] R is added to the benzene ring of the compound of formula (I). ５ By introducing this, it is possible to increase the molecular weight, and as a result, CO ２ It is also possible to suppress the weight loss of the absorbent due to unwanted sublimation during desorption. From this point of view, R ５ It is preferable to introduce an aryl group which may have substituents.

[0021] R ５ Examples of aryl groups include phenyl, biphenyl, naphthyl, phenantrenyl, and anthracenyl groups, with phenyl being preferred.

[0022] Substituents on the aryl group include optionally substituted alkyl groups, heteroaromatic rings such as pyridine / pyrrole / furan / thiophene, cyano groups, ester groups, ether groups (alkyl groups substituted with alkoxy groups), nitro groups, and perfluoroalkyl groups. Preferably, optionally substituted alkyl groups are C1-C4 alkyl groups, more preferably C1-C3 alkyl groups, and substituents on the alkyl groups include halogens such as fluorine or chlorine, phenyl groups, vinyl groups, alkynyl groups, amino groups, and hydroxyl groups.

[0023] R ５ Preferably, it is a phenyl group which may have substituents.

[0024] m is an integer from 0 to 3. m is preferably 0 or 1.

[0025] If m is 1 or greater, R ５ NH ２ -CR １ R ２- is bonded at one or more of the ortho, meta, or para positions on the benzene ring relative to the bonded position (however, NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ (Excluding the ortho position between -).

[0026] In one preferred aspect of the carbon dioxide absorbent of the present invention, m is 0.

[0027] Furthermore, in another preferred aspect of the carbon dioxide absorbent of the present invention, R ５ This is a phenyl group which may have substituents.

[0028] Furthermore, in another preferred aspect of the carbon dioxide absorbent of the present invention, m is 1, and R ５ is a phenyl group which may have substituents, and the phenyl group is NH ２ -CR １ R ２ The negative charge bonds at the meta position on the benzene ring relative to the bonded position.

[0029] In the carbon dioxide absorbent of the present invention, the compound represented by formula (I) can also be used as a composition obtained by dissolving or suspending it in a solvent. When water or a mixed solvent of water and an organic solvent is used as the solvent (reaction solvent), high CO ２ It is possible to demonstrate absorption capacity.

[0030] When the compound represented by formula (I) is used as a composition dissolved or suspended in a solvent, the content of the compound represented by formula (I) in the carbon dioxide absorbent of the present invention is not particularly limited.

[0031] Furthermore, in the carbon dioxide absorbent of the present invention, the compound represented by formula (I) can also be used by supporting it on a carrier.

[0032] As the carrier, those known as carriers for carbon dioxide absorbents can be used. For example, porous carriers or the like can be used, but it is preferable to use γ-alumina. When the compound represented by the formula (I) is mixed with γ-alumina and adsorbed on γ-alumina, a powdery solid can be obtained, which is easy to handle.

[0033] To support the compound represented by the formula (I) on γ-alumina, the compound can be dissolved in a solvent such as ethyl acetate, the solution can be added to γ-alumina, and concentrated under reduced pressure to support the compound on γ-alumina.

[0034] In the carbon dioxide absorbent of the present invention, when the compound represented by the formula (I) is supported on a carrier such as γ-alumina and used, the loading amount of the compound is not particularly limited. For example, as the loading amount per 1 g of the carrier, it is 10 to 200 (mg / g), preferably 10 to 100 (mg / g).

[0035] 2. Method for recovering carbon dioxide Another embodiment of the present invention is a method for recovering carbon dioxide from a gas, comprising: a step of preparing a carbon dioxide absorbent containing a compound represented by the following formula (I); and a step of recovering carbon dioxide by bringing the gas into contact with the carbon dioxide absorbent, which is a method for recovering carbon dioxide (hereinafter also referred to as "the recovery method of the present invention").

[0036] In the formula (I), R １ ~ R ４ 、R ５ and the details of m and the compound of the formula (I) are as detailed for the carbon dioxide absorbent of the present invention.

[0037] When performing the recovery method of the present invention, the carbon dioxide absorbent can also be used as a composition in which the compound represented by the formula (I) is dissolved or suspended in a solvent. Further, the carbon dioxide absorbent of the present invention can also be used by supporting the compound represented by the formula (I) on a carrier.

[0038] In one preferred embodiment of the recovery method of the present invention, m is 0 in the formula (I).

[0039] In another preferred embodiment of the recovery method of the present invention, R ５ This is a phenyl group which may have substituents.

[0040] Furthermore, in another preferred aspect of the recovery method of the present invention, m is 1, and R ５ is a phenyl group which may have substituents, and the phenyl group is NH ２ -CR １ R ２ The negative charge bonds at the meta position on the benzene ring relative to the bonded position.

[0041] In another preferred embodiment of the recovery method of the present invention, the compound represented by formula (I) is supported on a carrier.

[0042] In yet another preferred embodiment of the recovery method of the present invention, the compound represented by formula (I) is supported on γ-alumina.

[0043] In the recovery method of the present invention, gases such as air, carbon dioxide-argon, and carbon dioxide-nitrogen can be used as the gas from which carbon dioxide is recovered. To facilitate effective miscibility of the carbon dioxide absorbent solution and the γ-alumina support with the above gases, gas washing bottles, cylindrical columns, etc., can be used.

[0044] The recovery method of the present invention can also be suitably used in DAC (Direct Air Capture) devices that directly adsorb carbon dioxide from the atmosphere. Known devices can be used as DAC devices.

[0045] The recovery method of the present invention may include a step of contacting the carbon dioxide absorbent of the present invention with carbon dioxide, and then heating the carbon dioxide absorbent on which the carbon dioxide has been adsorbed to desorb the carbon dioxide. The carbon dioxide absorbent on which the carbon dioxide has been adsorbed can have the carbon dioxide desorbed by heating it at 60 to 120°C, preferably 80 to 100°C. Since the carbon dioxide absorbent of the present invention has high oxidation resistance, it can be regenerated after the carbon dioxide has been desorbed and can be repeatedly used for carbon dioxide absorption and desorption.

[0046] 3. Compounds of the present invention Another embodiment of the present invention is a compound represented by the following formula (II) (hereinafter also referred to as "the compound of the present invention").

[0047] In formula (II), R １ ~R ４ are each independently selected from the group consisting of an alkyl group which may have a substituent and an aryl group which may have a substituent. By introducing these groups in all of R １ ~R ４ to form a structure such as a quaternary alkylamine in which a radical cannot be mechanistically generated at the α-position carbon of the amino group, a CO ２ absorbent having high oxidation durability can be provided. Further, by introducing these groups into R １ ~R ４ it is also possible to reduce the temperature required for the desorption of carbon dioxide.

[0048] The alkyl group which may have a substituent is preferably an alkyl group having 1 to 18 carbon atoms which may have a substituent, more preferably an alkyl group having 1 to 4 carbon atoms which may have a substituent, and preferably, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group and the like. Examples of the substituent of the alkyl group include halogen such as fluorine or chlorine, an alkoxy group, an ester, a phenyl group and the like. Examples of the alkyl group having a substituent include a benzyl group, a methoxymethyl group and the like.

[0049] s is an integer of 1 to 3.

[0050] The phenyl group in formula (II) is bonded at any one or more of the ortho-position, meta-position, and para-position on the benzene ring with respect to the position to which NH ２ -CR １ R ２ - is bonded (however, the ortho-position between NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ - is excluded).

[0051] The phenyl group in formula (II) is NH ２ -CR １ R ２ The negative charge preferably bonds to the meta position on the benzene ring relative to the bonded position.

[0052] In one preferred aspect of the compound of the present invention, s is 1, and the phenyl group in formula (II) is NH ２ -CR １ R ２ The negative charge preferably bonds to the meta position on the benzene ring relative to the bonded position.

[0053] R ａ Each of these is independently selected, at each instance of appearance, from the group consisting of alkyl groups which may have substituents, heteroaromatic rings, cyano groups, ester groups, ether groups (alkyl groups substituted with alkoxy groups), nitro groups, and perfluoroalkyl groups.

[0054] R ａ The alkyl group which may have substituents is preferably an alkyl group having 1 to 4 carbon atoms which may have substituents, and more preferably an alkyl group having 1 to 3 carbon atoms which may have substituents. Examples of substituents on the alkyl group include halogens such as fluorine or chlorine, a phenyl group, a vinyl group, an alkynyl group, an amino group, a hydroxyl group, and the like.

[0055] Examples of heteroaromatic rings include pyridine, pyrrole, furan, and thiophene.

[0056] n is an integer between 0 and 5.

[0057] One preferred embodiment of the compound of formula (II) is the compound represented by the following formula (IIa).

[0058] In equation (IIa), R １ ~R ４ , R ａ The details of n are as described in detail for the compound of formula (II).

[0059] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0060] 1. Samples and measuring instruments (1) Reagents 1,3-bis(2-isocyanatopropan-2-yl)benzene (purchased from Tokyo Chemical Industry Co., Ltd.), hydrochloric acid, sodium hydroxide, dimethyl 5-bromoisophthalate (purchased from Tokyo Chemical Industry Co., Ltd.), magnesium methylbromide, azidotrimethylsilane (purchased from Tokyo Chemical Industry Co., Ltd.), palladium carbon, hydrogen

[0061] (2) Measuring instruments NMR spectrum: Bruker Avance Neo FT-IR spectrum: JASCO FT / IR4700 ESI mass spectrum: Bruker Compact

[0062] [Synthesis Example 1] Synthesis of α,α,α',α'-tetramethyl-m-xylenediamine (compound a)

[0063] α,α,α',α'-tetramethyl-m-xylenediamine (compound a) was synthesized using the following synthesis scheme.

[0064]

[0065] To 1,3-bis(2-isocyanatopropan-2-yl)benzene (9.27 mL, 41.0 mmol), 12 M hydrochloric acid aqueous solution (20 mL, 0.24 mol) was added under an argon atmosphere, and the mixture was stirred at 80°C for 1 hour, followed by stirring at room temperature for 12 hours. The reaction mixture was carefully neutralized at 0°C with 50% NaOH aqueous solution (to pH ≥ 12) to obtain the neutral product of the desired product. After extracting the mixture three times with 40 mL of dichloromethane, the combined organic phase was washed with saturated saline solution and Na ２ SO ４ The mixture was dried, filtered, and concentrated under vacuum to obtain α,α,α',α'-tetramethyl-m-xylenediamine (7.2 g, 91%) as a pale yellow oil.

[0066] 1 H NMR (500 MHz, CD3OD) δ = 7.65 (t, J = 1.8 Hz, 1H), 7.26-7.35 (m, 3H), 1.49 (s, 12H) ppm.

[0067] [Synthesis Example 2] Synthesis of 3,5-bis[(α,α,α',α'-tetramethyl)aminomethyl]-1,1'-biphenyl (TMMXDA biphenyl derivative)

[0068] The TMMXDA biphenyl compound (compound 2b) was synthesized using the following synthesis scheme.

[0069]

[0070] (1) Synthesis of dimethyl(1,1'-biphenyl)-3,5-dicarboxylate (compound 3): Dimethyl 5-bromoisophthalate (3.00 g, 11.0 mmol), phenylboronic acid (2.68 g, 22.0 mmol), PdCl ２ (dppf)-CH ２ Cl ２ Adductor (449 mg, 0.549 mmol), 2 M Na ２ CO ３ (11.0 mL, 22.0 mmol) and DME (30 mL) were added to a microwave irradiation vial, a stirring bar was added, and the vial was sealed with a septum cap. The vial was then heated in a microwave irradiation device set to 150°C for 10 minutes and then cooled to room temperature. Water (30 mL) was added to stop the reaction, and the mixture was extracted three times with 30 mL of chloroform. The combined organic layers were separated using an ISOLUTE® Phase Separator and concentrated under reduced pressure. The crude product was purified by silica gel flash column chromatography (ethyl acetate:hexane = 1:9) to obtain pure compound 3 (2.20 g, 74%) as a white solid.

[0071] 1 H NMR (500 MHz, CDCl3) δ = 8.66 (t, J = 1.6 Hz, 1H), 8.47 (d, J = 1.6 Hz, 2H), 7.66 (d, J = 7.1 Hz, 2H), 7.49 (dd, J = 7.4, 7.1 Hz, 2H), 7.41 (t, J = 7.4 Hz, 1H), 3.98 (s, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 166.3, 142.0, 139.0, 132.3, 131.2, 129.3, 129.0, 128.2, 127.2, 52.5 ppm.

[0072] (2) Synthesize compound 3 (2.20 g, 8.14 mmol) of 3,5-bis[(α,α,α',α'-tetramethyl)carbonyl]-1,1'-biphenyl (compound 4) in a solution of THF (50 mL) and MeMgBr (3M Et) under nitrogen at 0°C. ２ 22 mL of solution O (65 mmol) was slowly added dropwise. After addition, the reaction mixture was warmed to room temperature and stirred for 2 hours. Saturated NH ４ The reaction was stopped by carefully adding an aqueous solution of Cl (30 mL), and the mixture was extracted with chloroform (3 × 50 mL). The combined organic phases were separated using an ISOLUTE® Phase Separator and concentrated under reduced pressure. The crude product was purified by silica gel flash column chromatography (ethyl acetate:hexane = 1:1) to obtain the target product 4 (1.90 g, 86%) as a white solid.

[0073] 1 H NMR (500 MHz, DMSO-d6) δ = 7.64 (d, J = 7.0 Hz, 2H), 7.59 (t, J = 1.6 Hz, 1H), 7.55 (d, J = 1.6 Hz, 2H), 7.47 (dd, J = 7.2, 7.0 Hz, 2H), 7.36 (t, J = 7.2 Hz, 1H), 5.04 (s, 2H), 1.49 (s, 12H) ppm; 13 C NMR (126 MHz, DMSO-d6) δ 151.1, 141.8, 139.7, 129.3, 127.6, 127.3, 121.3, 120.5, 71.4, 32.6 ppm.

[0074] (3) Add BF to a chloroform (50 mL) suspension of synthetic compound 4 (1.90 g, 7.03 mmol) of 3,5-bis[(α,α,α',α'-tetramethyl)azidomethyl]-1,1'-biphenyl (compound 5) while stirring under nitrogen at room temperature. ３ -Et ２O (3.56 mL, 28.1 mmol) was added dropwise, followed by azidotrimethylsilane (3.73 mL, 28.1 mmol) at room temperature, and the mixture was stirred for 15 hours. Saturated NH ４ The reaction was stopped by adding an aqueous solution of Cl (50 mL), and the organic layer was separated. The aqueous layer was extracted with chloroform (2 × 30 mL), and the combined organic layers were separated using an ISOLUTE® Phase Separator. The chloroform solution was concentrated under reduced pressure to approximately 10 mL, and hexane (10 mL) was added. The crude reaction mixture was purified by silica gel flash chromatography (chloroform:hexane = 1:3), and the fraction containing the product was combined and co-evaporated with EtOH (3 × 50 mL), evaporating to a final volume of approximately 50 mL. The resulting solution was used directly in the next step. To obtain compound data, a small amount (1.5 mL) of this solution was completely evaporated to obtain compound 5 (48 mg) as a white solid.

[0075] 1 H NMR (500 MHz, CDCl3) δ = 7.59 (d, J = 7.0 Hz, 2H), 7.55 (d, J = 1.7 Hz, 2H), 7.51 (t, J = 1.7 Hz, 1H), 7.47 (dd, J = 7.3, 7.0 Hz, 2H), 7.38 (t, J = 7.3 Hz, 1H), 1.70 (s, 12H) ppm; 13 C NMR (126 MHz, CDCl3) δ = 145.7, 142.0, 141.1, 128.9, 127.6, 127.4, 123.2, 120.8, 63.9, 28.5 ppm.

[0076] (4) Synthesis of 3,5-bis[(α,α,α',α'-tetramethyl)aminomethyl]-1,1'-biphenyl hydrochloride (compound 2b・HCl) Compound 5 (1.60 g, 4.99 mmol, weight is estimated) was stirred in ethanol (50 mL), then palladium carbon (5% w / w, 200 mg) was added, and the reaction vessel was filled with hydrogen gas and stirred vigorously at room temperature until the starting materials were consumed (15 hours, １(Tracking by 1H NMR). The reaction mixture was filtered under reduced pressure through a Celite pad, then washed with ethanol, and the hydrochloride salt was prepared by adding an excess amount of 36% aqueous hydrochloric acid to the combined filtrate. After concentrating the mixture under reduced pressure, the crude residue was subjected to ODS column chromatography (MeCN → MeCN:H). ２ The compound was purified using a 6:4 gradient (O = 6), and the desired product 2b·HCl (1.10 g, 65%) was obtained as a white solid. Compound 2b·HCl is stable in air at room temperature and, unlike compound 2b, does not contain CO2. ２ It did not absorb it.

[0077] 1 H NMR (500 MHz, DMSO-d6) δ = 8.94 (s, 6H), 7.85 (s, 4H), 7.83 (m, 1H), 7.51 (m, 2H), 7.42 (t, J = 7.4 Hz, 1H), 1.73 (s, 12H) ppm; 13 C NMR (126 MHz, DMSO-d6) δ = 144.3, 141.0, 140.3, 129.4, 128.4, 127.6, 123.2, 122.0, 56.4, 28.2 ppm.

[0078] (5) Synthetic compound 2b·HCl (938 mg, 2.75 mmol) of 3,5-bis[(α,α,α',α'-tetramethyl)aminomethyl]-1,1'-biphenyl (compound 2b) ２ To a stirred suspension in O (10 mL), a 50% NaOH (0.6 mL) aqueous solution was added at room temperature to neutralize it (until pH ≥ 12), and the mixture was stirred for 2 hours. The reaction mixture was extracted with dichloromethane (4 × 40 mL), and the combined organic phase was washed with saturated saline solution (1 × 30 mL). The extract was then treated with Na ２ SO ４ After drying, the mixture was filtered and concentrated under reduced pressure to obtain compound 2b (726 mg, 98%) as a white solid.

[0079] 1H NMR (500 MHz, DMSO-d6) δ = 7.68 (t, J = 1.7 Hz, 1H), 7.66 (d, J = 7.0 Hz, 2H), 7.60 (d, J = 1.7 Hz, 2H), 7.46 (dd, J = 7.3, 7.0 Hz, 2H), 7.35 (t, J = 7.3 Hz, 1H), 1.95 (br s, 4H), 1.42 (s, 12H) ppm; 13 C NMR (126 MHz, DMSO-d6) δ = 151.9, 142.0, 139.7, 129.2, 127.5, 127.4, 121.5, 121.3, 52.8, 33.5 ppm.

[0080] [Example 1] (1) Carbon dioxide absorption test using amine solution α,α,α',α'-tetramethyl-m-xylenediamine (385 mg, 2.00 mmol) ２ A 10 mL solution of 0 was added to a gas washing bottle. An argon balloon containing 2500 ppm carbon dioxide was connected to the inlet side of the gas washing bottle, and a gas cell with reduced internal pressure was connected to the outlet side. After passing the gas through the aqueous solution until the pressure reached equilibrium, the carbon dioxide concentration inside the gas cell was quantified by FT-IR.

[0081] (2) A carbon dioxide absorption test compound 2b (134 mg, 0.50 mmol) supported on alumina was added to γ-alumina (1.21 g) in ethyl acetate (7 mL) and concentrated under reduced pressure to support compound 2b on the γ-alumina. The γ-alumina support was packed into a cylindrical column (2 cm in diameter), an argon balloon containing 2500 ppm carbon dioxide was connected to the top of the column, and a gas cell with reduced pressure inside was connected to the bottom of the column. After passing gas through the γ-alumina support until the pressure reached equilibrium, the carbon dioxide concentration inside the gas cell was quantified by FT-IR.

[0082] (3) Repeated Absorption and Desorption Test of Carbon Dioxide Compound 2b (134 mg, 0.50 mmol) in ethyl acetate (7 mL) was added to γ-alumina (1.21 g) and concentrated under reduced pressure to support compound 2b on the γ-alumina. The γ-alumina support was stirred at room temperature for 1 hour under a carbon dioxide atmosphere to allow compound 2b to absorb carbon dioxide. This γ-alumina support was spread on a petri dish and heated in an 80°C oven for 2 hours to desorb carbon dioxide from compound 2b. The γ-alumina support, which had been allowed to cool to room temperature, was packed into a cylindrical column (2 cm in diameter), an argon balloon containing 2500 ppm carbon dioxide was connected to the top of the column, and a gas cell with reduced internal pressure was connected to the bottom of the column. After the gas was passed through the γ-alumina support until the pressure reached equilibrium, the carbon dioxide concentration inside the gas cell was quantified by FT-IR. The γ-alumina support, after absorption, was removed from the column and heated in an 80°C oven for 2 hours to desorb carbon dioxide from compound 2b. The above carbon dioxide adsorption / desorption test was repeated 10 times to evaluate whether there was any decrease in performance. The results are shown in Figure 2.

Claims

1. A carbon dioxide absorbent containing a compound represented by the following formula (I). (In the formula, R １ to R ４ are each independently selected from the group consisting of an alkyl group which may have a substituent and an aryl group which may have a substituent; R ５ is independently selected from the group consisting of an alkyl group which may have a substituent and an aryl group which may have a substituent each time it appears; m is an integer of 0 to 3; when m is 1 or more, R ５ is NH ２ -CR １ R ２ - is bonded at one or more of the ortho, meta, and para positions on the benzene ring with respect to the position where it is bonded (however, the ortho position between NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ - is excluded).) 2. The carbon dioxide absorbent according to claim 1, wherein m is 0.

3. R ５ The carbon dioxide absorbent according to claim 1, wherein is a phenyl group which may have substituents.

4. m is 1, R ５ NH ２ -CR １ R ２ The carbon dioxide absorbent according to claim 3, wherein the bond is formed at the meta position on the benzene ring relative to the position where the negative is bonded.

5. The carbon dioxide absorbent according to any one of claims 1 to 4, wherein a compound represented by formula (I) is supported on a carrier.

6. The carbon dioxide absorbent according to claim 5, wherein the carrier is γ-alumina.

7. A method for recovering carbon dioxide from a gas, comprising the steps of preparing a carbon dioxide absorbent containing a compound represented by the following formula (I); and (In the formula, R １ ~R ４ Each is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups; R ５ m is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups at each occurrence; m is an integer from 0 to 3; when m is 1 or greater, R ５ NH ２ -CR １ R ２ - is bonded at one or more of the ortho, meta, or para positions on the benzene ring relative to the bonded position (however, NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ A method for recovering carbon dioxide, comprising the step of recovering carbon dioxide by bringing the gas into contact with the carbon dioxide absorbent (excluding the ortho position between the two).

8. The recovery method according to claim 7, wherein m is 0.

9. R ５ The recovery method according to claim 7, wherein is a phenyl group which may have substituents.

10. The recovery method according to any one of claims 7 to 9, wherein the compound represented by formula (I) is supported on a carrier.

11. The recovery method according to claim 10, wherein the carrier is γ-alumina.

12. Compounds represented by the following formula (II). (In the formula, R １ ~R ４ Each is independently selected from the group consisting of optionally substituted alkyl groups and optionally substituted aryl groups; R ａ Each of these is independently selected from the group consisting of optionally substituted alkyl groups, heteroaromatic rings, cyano groups, ester groups, ether groups, nitro groups, and perfluoroalkyl groups at each instance; n is an integer from 0 to 5; s is an integer from 1 to 3; the phenyl group in formula (II) is NH ２ -CR １ R ２ - is bonded at one or more of the ortho, meta, or para positions on the benzene ring relative to the bonded position (however, NH ２ -CR １ R ２ - and NH ２ -CR ３ R ４ (Excluding the ortho position between -s.)

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