Acid-gas adsorbent, structure provided with acid-gas adsorbent, and acid-gas adsorption device

Abstract

The present invention provides an acid-gas adsorbent suitable for curbing, in a low-humidity environment, a decrease in adsorption performance with respect to an acid gas. This acid-gas adsorbent comprises a polymer P having an amino group, and a liquid L having a boiling point of 130°C or higher. When the acid-gas adsorbent is run through an adsorption test A for 15 hours, the amount of carbon dioxide adsorbed is 0.35 mmol / g or higher. 　Adsorption test A: a mixed gas G1 composed of carbon dioxide, nitrogen, and water vapor is continuously fed into a container in which the acid-gas adsorbent is accommodated. The concentration of carbon dioxide in the mixed gas G1 is 400 volppm, and the mixed gas G1 has a temperature of 20°C and a humidity of 50%RH.

Description

Acid gas adsorbent, structure equipped with acid gas adsorbent, and acid gas adsorption device

[0001] The present invention relates to an acid gas adsorbent, a structure including the acid gas adsorbent, and an acid gas adsorption device.

[0002] In recent years, carbon capture and storage (CCS) and carbon capture and utilization (CCU) have been considered as a way to reduce the amount of carbon dioxide in the atmosphere. In CCS and CCU, carbon dioxide is sometimes captured by separating it from the atmosphere.

[0003] As a method for separating acidic gases such as carbon dioxide from the atmosphere, an adsorption method has been developed in which the acidic gas is adsorbed onto an adsorbent. The adsorbent used in the adsorption method can adsorb the acidic gas by, for example, contacting the atmosphere.

[0004] Examples of adsorbent materials include amine compounds that have the function of adsorbing acidic gases. For example, Patent Document 1 discloses fibrillated cellulose with amino groups introduced therein as an adsorbent. Patent Document 2 discloses an adsorbent with amino groups introduced inside the pores of a mesoporous material.

[0005] International Publication No. 2017 / 009241 U.S. Patent No. 7,767,004

[0006] According to the studies of the present inventors, adsorbents containing amine compounds tend to have a reduced ability to adsorb acidic gases in a low-humidity environment (for example, an environment of 20°C and 30% RH or less). This tendency is particularly pronounced when the amine compound is a solid.

[0007] Therefore, an object of the present invention is to provide an acidic gas adsorbent that is suitable for suppressing a decrease in the adsorption performance for acidic gases in a low-humidity environment.

[0008] The present invention provides an acidic gas adsorbent comprising: a polymer having an amino group; and a liquid having a boiling point of 130°C or higher, wherein when the following adsorption test A is performed for 15 hours, the adsorption amount a of carbon dioxide is 0.35 mmol / g or higher. Adsorption test A: A mixed gas G1 composed of carbon dioxide, nitrogen, and water vapor is continuously fed into a container containing the acidic gas adsorbent. Here, the concentration of carbon dioxide in the mixed gas G1 is 400 vol ppm, and the mixed gas G1 is at a temperature of 20°C and a humidity of 50% RH.

[0009] The present invention further provides a structure comprising the above-described acid gas adsorbent and a ventilation path.

[0010] The present invention further provides an acidic gas adsorption device comprising an adsorption section having a gas inlet and a gas outlet, the adsorption section containing the above-mentioned acidic gas adsorbent.

[0011] According to the present invention, it is possible to provide an acidic gas adsorbent that is suitable for suppressing a decrease in the adsorption performance for acidic gases in a low-humidity environment.

[0012] 1 is a diagram for explaining a method for measuring the amount of carbon dioxide adsorbed by an acidic gas adsorbent. FIG. 2 is a perspective view schematically showing an example of a structure provided with an acidic gas adsorbent. FIG. 3 is a perspective view schematically showing a modified example of a structure provided with an acidic gas adsorbent. FIG. 4 is a graph showing the results of adsorption test B performed on the acidic gas adsorbents of Examples and Comparative Examples.

[0013] An acidic gas adsorbent according to a first aspect of the present invention comprises: a polymer having an amino group; and a liquid having a boiling point of 130°C or higher, and when the following adsorption test A is performed for 15 hours, the carbon dioxide adsorption amount a is 0.35 mmol / g or higher. Adsorption test A: A mixed gas G1 composed of carbon dioxide, nitrogen, and water vapor is continuously fed into a container containing the acidic gas adsorbent. Here, the concentration of carbon dioxide in the mixed gas G1 is 400 vol ppm, and the mixed gas G1 is at a temperature of 20°C and a humidity of 50% RH.

[0014] In a second aspect of the present invention, for example, in the acidic gas adsorbent according to the first aspect, the polymer is a solid.

[0015] In a third aspect of the present invention, for example, in the acidic gas adsorbent according to the first or second aspect, the polymer includes an amine polymer having a constitutional unit derived from an epoxy monomer.

[0016] In a fourth aspect of the present invention, for example, in the acidic gas adsorbent according to the third aspect, the amine polymer comprises a reaction product of a compound group including an amine monomer and an epoxy monomer.

[0017] In a fifth aspect of the present invention, for example, in the acidic gas adsorbent according to the fourth aspect, the amine monomer includes polyethyleneimine.

[0018] In a sixth aspect of the present invention, for example, in the acidic gas adsorbent according to any one of the first to fifth aspects, the glass transition temperature of the polymer is 40° C. or lower.

[0019] In a seventh aspect of the present invention, for example, in the acidic gas adsorbent according to any one of the first to sixth aspects, the liquid contains an ionic liquid.

[0020] In an eighth aspect of the present invention, for example, in the acidic gas adsorbent according to the seventh aspect, the ionic liquid has temperature responsiveness.

[0021] In a ninth aspect of the present invention, for example, in the acidic gas adsorbent according to any one of the first to eighth aspects, the content of the liquid is 1 wt % to 15 wt %.

[0022] In a tenth aspect of the present invention, for example, the acidic gas adsorbent according to any one of the first to ninth aspects has a porous structure.

[0023] In an eleventh aspect of the present invention, for example, the acidic gas adsorbent according to any one of the first to tenth aspects has an adsorption amount b1 of carbon dioxide of 0.1 mmol / g or more when the following adsorption test B is performed for 15 hours. Adsorption test B: A mixed gas G2 composed of carbon dioxide, nitrogen, and water vapor is continuously fed into a container containing the acidic gas adsorbent. Here, the concentration of carbon dioxide in the mixed gas G2 is 400 vol ppm, and the mixed gas G2 is at a temperature of 20°C and a humidity of 20% RH.

[0024] In a twelfth aspect of the present invention, for example, the acidic gas adsorbent according to the eleventh aspect has an adsorption amount b2 of carbon dioxide of 0.01 mmol / g or more when the adsorption test B is carried out for one hour.

[0025] A structure according to a thirteenth aspect of the present invention comprises: an acidic gas adsorbent according to any one of the first to twelfth aspects; and a ventilation path.

[0026] An acidic gas adsorption device according to a fourteenth aspect of the present invention comprises an adsorption section having a gas inlet and a gas outlet, and the adsorption section accommodates the acidic gas adsorbent according to any one of the first to twelfth aspects.

[0027] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0028] <Embodiment of Acidic Gas Adsorbent> The acidic gas adsorbent of this embodiment includes a polymer P having an amino group and a liquid L having a boiling point of 130°C or higher. The combination of polymer P and liquid L tends to suppress the deterioration of the adsorption performance of the acidic gas adsorbent in a low-humidity environment (for example, an environment of 20°C and 30% RH or less). In this specification, "boiling point" means the boiling point under atmospheric pressure (101.325 kPa). "Liquid" means a substance in a liquid state at atmospheric pressure and 20°C.

[0029] The acidic gas adsorbent of this embodiment exhibits practically sufficient adsorption performance in a high-humidity environment (for example, an environment exceeding 30% RH at 20°C), and when the following adsorption test A is performed for 15 hours, the carbon dioxide adsorption amount a is 0.35 mmol / g or more. In adsorption test A, a mixed gas G1 is used as the high-humidity gas. Adsorption test A: A mixed gas G1 composed of carbon dioxide, nitrogen, and water vapor is continuously fed into a container containing the acidic gas adsorbent. Here, the carbon dioxide concentration in the mixed gas G1 is 400 vol ppm, and the mixed gas G1 is at a temperature of 20°C and a humidity of 50% RH.

[0030] (Adsorption Test A) The following describes the details of Adsorption Test A. Adsorption Test A can be performed using a measurement device 20 shown in FIG. 1 . The measurement device 20 includes a first tank 30 and a second tank 31. As an example, the first tank 30 stores dry nitrogen, and the second tank 31 stores a mixed gas of dry nitrogen and dry carbon dioxide. The concentration of carbon dioxide in the mixed gas in the second tank 31 is, for example, 5 vol %.

[0031] The measuring device 20 further includes a first container 40 containing water 70, and a first path 60 for sending nitrogen from the first tank 30 to the first container 40. The first path 60 has one end connected to the gas outlet of the first tank 30 and the other end located in the water 70 of the first container 40. The nitrogen sent from the first tank 30 to the first container 40 is humidified by contact with the water 70. A mass flow controller 35 is arranged in the first path 60 to adjust the flow rate of nitrogen sent from the first tank 30 to the first container 40.

[0032] The measuring device 20 further includes a second container 41, a second path 62, and a bypass path 61. The second path 62 connects the first container 40 and the second container 41. The humidified nitrogen sent to the first container 40 is sent to the second container 41 through the second path 62. The bypass path 61 branches off from the first path 60 at a position between the first tank 30 and the mass flow controller 35 and connects to the second path 62. A portion of the nitrogen sent from the first tank 30 flows into the bypass path 61 and is sent to the second container 41 through the second path 62. A mass flow controller 36 is disposed in the bypass path 61 to adjust the flow rate of nitrogen sent from the first tank 30 to the bypass path 61.

[0033] The measuring device 20 further includes a third path 63 for sending the mixed gas from the second tank 31 to the second path 62. The third path 63 has one end connected to the gas outlet of the second tank 31 and the other end connected to the second path 62. A mass flow controller 37 is disposed in the third path 63 for adjusting the flow rate of the mixed gas sent from the second tank 31 to the second path 62. The mixed gas sent to the second path 62 is sent to the second container 41 through the second path 62.

[0034] The measurement device 20 further includes a third container 42 and a fourth path 64. The third container 42 contains water 71 and an adsorption unit 21 disposed in the water 71. In the third container 42, the temperature of the water 71 is maintained at 20°C. The adsorption unit 21 has a gas inlet 22 and a gas outlet 23. The adsorption unit 21 functions as a container that contains an acidic gas adsorbent therein. The adsorption unit 21 is configured to prevent the water 71 from penetrating into the interior. The adsorption unit 21 is typically a tube made of a hydrophobic resin, for example, a fluororesin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA). As an example, the tube serving as the adsorption unit 21 has an inner diameter of 4 mm and an outer diameter of 6 mm. The adsorption unit 21 is configured to be detachable from the measurement device 20.

[0035] The measuring device 20 can also be used as an acidic gas adsorption device equipped with an adsorption unit 21. In another aspect, the present invention provides an acidic gas adsorption device 20 equipped with an adsorption unit 21 having a gas inlet 22 and a gas outlet 23, the adsorption unit 21 accommodating an acidic gas adsorbent.

[0036] The fourth path 64 connects the second container 41 and the third container 42. Specifically, the fourth path 64 is connected to the gas inlet 22 of the adsorption unit 21 in the third container 42. A first concentration meter 50 is disposed in the fourth path 64 to measure the concentration of carbon dioxide in the gas supplied to the adsorption unit 21. A CO2 / H2O gas analyzer LI-850-3 manufactured by LI-COR Corporation can be used as the first concentration meter 50.

[0037] The measurement device 20 further includes a fifth path 65 connected to the gas outlet 23 of the adsorption unit 21 for discharging gas from the adsorption unit 21 to the outside of the measurement device 20. A back pressure valve 55 and a second concentration meter 51 are disposed in the fifth path 65. The back pressure valve 55 allows the pressure inside the adsorption unit 21 to be adjusted to a constant value. The second concentration meter 51 can measure the concentration of carbon dioxide in the gas discharged from the adsorption unit 21. A CO2 / H2O gas analyzer LI-850-3 manufactured by LI-COR Corporation can be used as the second concentration meter 51.

[0038] Each path of the measuring device 20 is preferably made of metal or resin piping.

[0039] [Pretreatment] First, an acidic gas adsorbent is prepared and dried. The drying is preferably performed by treating the acidic gas adsorbent for at least two hours under conditions of 60°C in a vacuum atmosphere. Next, the dried acidic gas adsorbent is packed into the adsorption unit 21 in a dry room with a dew point of approximately -60°C. The weight of the acidic gas adsorbent packed into the adsorption unit 21 is, for example, 50 mg. Next, the fourth path 64 and the fifth path 65 are connected to both ends of the adsorption unit 21, and the adsorption unit 21 is immersed in water 71 in the third container 42.

[0040] Next, nitrogen from the first tank 30 and the mixed gas from the second tank 31 are supplied to the second container 41 via the first path 60, the second path 62, the bypass path 61, and the third path 63 of the measurement device 20. These gases are mixed in the second container 41 to obtain a mixed gas G1 composed of carbon dioxide, nitrogen, and water vapor. In the second container 41, the carbon dioxide concentration in the mixed gas G1 is adjusted to 400 vol ppm. The mixed gas G1 has a temperature of 20°C and a humidity of 50% RH. The mixed gas G1 is supplied to the adsorption unit 21 via the fourth path 64 at a flow rate sufficient for the weight of the acidic gas adsorbent, for example, a flow rate of 300 mL / min for 50 mg of acidic gas adsorbent. In the adsorption unit 21, the pressure of the mixed gas G1 is adjusted to, for example, 107 kPa by the back pressure valve 55.

[0041] Next, while the mixed gas G1 is being supplied to the adsorption unit 21, the adsorption unit 21 is removed from the third container 42 and immersed in a water bath (not shown) at 80°C for two hours or more. The adsorption unit 21 is immersed in the water bath until the carbon dioxide concentration measured by the first concentration meter 50 and the carbon dioxide concentration measured by the second concentration meter 51 become substantially the same value. This completes the pretreatment of the acidic gas adsorbent in the adsorption unit 21.

[0042] [Adsorption Test] Next, while the mixed gas G1 is being supplied to the adsorption unit 21, the adsorption unit 21 is removed from the hot water bath and immersed in the water 71 in the third container 42. This starts a carbon dioxide adsorption test (adsorption test A) for the acidic gas adsorbent in the adsorption unit 21. The adsorption test is carried out for 15 hours after the start. Specifically, the mixed gas G1 is continuously supplied to the adsorption unit 21 for 15 hours. When the adsorption test is carried out for 15 hours, it can usually be considered that the adsorption of carbon dioxide by the acidic gas adsorbent has reached equilibrium.

[0043] In adsorption test A, the amount of carbon dioxide adsorbed by the acid gas adsorbent from the start to 15 hours is measured as M1. The amount of carbon dioxide adsorbed by the acid gas adsorbent can be calculated from the results of measuring the difference over time between the carbon dioxide concentration measured by the first concentration meter 50 and the carbon dioxide concentration measured by the second concentration meter 51. Based on the amount of substance M1, the amount of carbon dioxide adsorbed by 1 g of the acid gas adsorbent in 15 hours is calculated, and the calculated value is specified as the adsorption amount a.

[0044] In the acidic gas adsorbent of this embodiment, the carbon dioxide adsorption amount a when adsorption test A is performed for 15 hours is preferably 0.4 mmol / g or more, and may be 0.5 mmol / g or more, 0.8 mmol / g or more, 1.0 mmol / g or more, 1.3 mmol / g or more, 1.5 mmol / g or more, 1.6 mmol / g or more, 1.7 mmol / g or more, 1.8 mmol / g or more, 1.9 mmol / g or more, 2.0 mmol / g or more, 2.1 mmol / g or more, 2.2 mmol / g or more, or even 2.3 mmol / g or more. The upper limit of the carbon dioxide adsorption amount a is not particularly limited, and may be, for example, 10 mmol / g or less.

[0045] (Polymer) In the acidic gas adsorbent, the polymer P has the function of adsorbing acidic gases due to amino groups. The polymer P preferably contains at least one amino group selected from the group consisting of primary amino groups, secondary amino groups, and tertiary amino groups. From the viewpoint of adsorption performance for acidic gases, the polymer P preferably contains at least one amino group selected from the group consisting of primary amino groups and secondary amino groups, and preferably contains both primary and secondary amino groups. In the polymer P, the larger the amount of primary amino groups and secondary amino groups (particularly primary amino groups), the higher the density of nitrogen elements in the acidic gas adsorbent and the higher the amount of acidic gas adsorption (e.g., the above-mentioned adsorption amount a) tends to be. When the amount of primary amino groups and secondary amino groups (particularly secondary amino groups) in the polymer P is large, the acidic gas adsorbent tends to be able to easily desorb the adsorbed acidic gases. Polymer P having primary amino groups or secondary amino groups allows the acidic gas adsorbent to be regenerated under relatively mild conditions. The polymer P may contain a tertiary amino group, but may not contain a tertiary amino group.

[0046] In this embodiment, in the near-infrared absorption spectrum (spectral data) obtained by performing near-infrared spectroscopy (NIR) on the polymer P, -1 The peak intensity I of the absorption peak present in the vicinity B The wave number is 4930 cm -1 The peak intensity I of the absorption peak present in the vicinity A Ratio I A / I B Generally, when the polymer P contains a primary amino group and a secondary amino group, the wavelength of the polymer P is preferably 6500 cm -1 Absorption peaks due to primary and secondary amino groups were observed around the wavenumber of 4930 cm -1 An absorption peak due to the primary amino group is observed around the A / I Bcan be used as an index relating to the ratio of the amount of primary amino groups to the amount of secondary amino groups in polymer P. NIR can be performed using a transparent test piece obtained by press-molding polymer P. This test piece is less prone to light scattering, which can affect the NIR results.

[0047] Ratio I A / I B is more preferably 0.90 or more, and may be 0.95 or more, 1.00 or more, 1.05 or more, 1.10 or more, 1.15 or more, or even 1.20 or more. A / I B The higher the ratio I, the greater the amount of acid gas adsorbed (for example, the above-mentioned adsorption amount a). A / I B The upper limit of is not particularly limited, and is, for example, 1.50 or less.

[0048] The weight ratio of nitrogen elements in polymer P is, for example, 5 wt% or more, preferably 10 wt% or more. The higher this weight ratio, the more the acidic gas adsorption performance of the acidic gas adsorbent tends to improve. The upper limit of the weight ratio of nitrogen elements in polymer P is not particularly limited, and is, for example, 30 wt% or less. Note that when all of the nitrogen elements contained in polymer P are derived from amino groups, the weight ratio of nitrogen elements described above can be regarded as the weight ratio of amino groups in polymer P.

[0049] The density of nitrogen elements in polymer P is, for example, greater than 12.0 mmol / g, preferably 12.2 mmol / g or greater, and may be 12.5 mmol / g or greater, 13.0 mmol / g or greater, 13.5 mmol / g or greater, 14.0 mmol / g or greater, 14.5 mmol / g or greater, 15.0 mmol / g or greater, 15.5 mmol / g or greater, 16.0 mmol / g or greater, 16.5 mmol / g or greater, 17.0 mmol / g or greater, or even 17.5 mmol / g or greater. The upper limit of the nitrogen element density is not particularly limited and may be, for example, 30 mmol / g or less, or 20 mmol / g or less. In this specification, the density of nitrogen elements in polymer P refers to the amount of nitrogen elements contained in 1 g of polymer P. Note that when all of the nitrogen elements contained in polymer P are derived from amino groups, the density of nitrogen elements can be considered to be the density of amino groups in polymer P.

[0050] The density of nitrogen elements in polymer P can be measured by the following method. First, the weight ratio w (wt%) of nitrogen elements contained in polymer P is measured using a commercially available CHN elemental analyzer. Based on the obtained results, the density d of nitrogen elements can be calculated using the following formula: Density d (mmol / g) = (weight ratio w (wt%) × 1000) / (atomic weight of nitrogen × 100)

[0051] The polymer P may contain a functional group other than an amino group. Examples of the functional group include a hydroxyl group, an ether group, an ester group, and an amide group. The polymer P preferably contains an ether group as the functional group.

[0052] The polymer P preferably comprises an amine polymer, particularly an amine polymer comprising a building block U1 derived from an epoxy monomer. The amine polymer may comprise a reactant P1 of a compound group comprising an amine monomer, particularly a compound group comprising an amine monomer and an epoxy monomer.

[0053] As described above, the group of compounds for forming the reactant P1 includes an amine monomer and an epoxy monomer. The reactant P1 may be a polymer of a group of monomers including an amine monomer and an epoxy monomer (particularly a polymer of an amine monomer and an epoxy monomer). The reactant P1 may also be a crosslinked product of an amine monomer with an epoxy monomer. A crosslinked product of an amine monomer with an epoxy monomer not only tends to have a high nitrogen element density, but also tends to have high heat resistance and moist heat resistance. When preparing the reactant P1 having a crosslinked structure, it is preferable that at least one selected from the group consisting of the amine monomer and the epoxy monomer is a multifunctional monomer having two or more functionalities, particularly three or more functionalities.

[0054] The amine monomer is a monomer containing at least one amino group, preferably at least one primary amino group. The number of primary amino groups contained in the amine monomer is preferably two or more, may be three or more, or may be four or more. The upper limit of the number of primary amino groups is not particularly limited, and may be, for example, 100 or less, or may be 10 or less. The amine monomer may contain secondary amino groups or tertiary amino groups in addition to primary amino groups, but may not contain tertiary amino groups. In the amine monomer, the ratio of the number of primary amino groups to the total number of amino groups is not particularly limited, and may be, for example, 10% or more, preferably 20% or more, more preferably 30% or more, or even 40% or more. The higher this ratio, the more crosslinking points in the amine monomer and the denser the crosslinked structure in the reactant P1, which tends to improve heat resistance and moist heat resistance. The upper limit of this ratio is not particularly limited, and may be, for example, 80% or less, or may be 60% or less.

[0055] The molecular weight (weight average molecular weight in some cases) of the amine monomer is, for example, 50 or more, and may be 100 or more, 150 or more, 200 or more, 300 or more, 500 or more, 1000 or more, or even 1500 or more. The larger the molecular weight of the amine monomer, the easier it is to adjust the density of the nitrogen element in the reactant P1. Furthermore, amine monomers with larger molecular weights tend to be safer to handle. The upper limit of the molecular weight of the amine monomer is, for example, 5000 or less, or may be 2000 or less. The molecular weight of the amine monomer may, in some cases, be less than 1000, 500 or less, or even 300 or less. The amine equivalent of the amine monomer is, for example, 10 g / eq. or more, preferably 20 g / eq. or more, and more preferably 30 g / eq. or more. The larger the amine equivalent of the amine monomer, the easier it is to adjust the density of the nitrogen element in the reactant P1. The upper limit of the amine equivalent of the amine monomer is not particularly limited, and may be, for example, 200 g / eq. It may be 150 g / eq. or less, 100 g / eq. or less, or even 50 g / eq. or less. In this specification, the amine equivalent means the mass of the amine monomer relative to 1 equivalent of the active hydrogen of the primary amino group contained in the amine monomer. When the amine monomer contains repeating units (structural units), the number of structural units contained in the amine monomer (degree of polymerization) is not particularly limited and is, for example, 5 to 100.

[0056] Examples of the amine monomers include ethylamine, ethylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, iminobispropylamine, bis(hexamethylene)triamine, 1,3,6-trisaminomethylhexane, tris(2-aminoethyl)amine, N,N'-bis(3-aminopropyl)ethylenediamine, polymethylenediamine, trimethylhexamethylenediamine, polyether Examples of suitable amine monomers include aliphatic amines such as butyldiamine; alicyclic amines such as isophoronediamine, menthanediamine, piperazine, N-aminoethylpiperazine, 3,9-bis(3-aminopropyl)2,4,8,10-tetraoxaspiro(5,5)undecane adduct, bis(4-amino-3-methylcyclohexyl)methane, bis(4-aminocyclohexyl)methane, and modified products thereof; aliphatic polyamines such as polyethyleneimine and polyalkylenepolyamines; (meth)acrylic polymers having amino groups such as aminoethylated acrylic polymers; and aliphatic polyamidoamines formed by the reaction of polyamines with dimer acids. The amine monomer preferably contains an aliphatic amine (particularly triethylenetetramine (TETA)) or an aliphatic polyamine (particularly polyethyleneimine (PEI)), and particularly preferably contains PEI. The amine monomers can be used alone or in combination of two or more.

[0057] In addition, aliphatic polyamines, particularly PEI, tend to be highly safe to handle. For example, amine monomers such as aliphatic polyamines are preferably not classified as hazardous materials under the Fire Service Act and are preferably not subject to the Poisonous and Deleterious Substances Control Act. The amine monomers preferably have negative results in mutagenicity tests (Ames tests). The amine monomers preferably have mild or moderate irritation results in skin irritation tests (primary skin irritation tests using rabbits).

[0058] The epoxy monomer is a monomer containing at least one epoxy group. The number of epoxy groups contained in the epoxy monomer is preferably 2 or more, and may be 3 or more, or 4 or more. The greater the number of epoxy groups, the more crosslinking points in the epoxy monomer and the denser the crosslinked structure in the reaction product P1, which tends to improve heat resistance and moist heat resistance. The upper limit of the number of epoxy groups contained in the epoxy monomer is not particularly limited and is, for example, 10 or less.

[0059] The molecular weight of the epoxy monomer is not particularly limited and is, for example, less than 1,000, preferably 500 or less. The epoxy equivalent of the epoxy monomer is not particularly limited and is, for example, 150 g / eq. or less, preferably 100 g / eq. or less. The smaller the epoxy equivalent of the epoxy monomer, the higher the density of the nitrogen element in the reactant P1 tends to be. The lower limit of the epoxy equivalent of the epoxy monomer is not particularly limited and is, for example, 50 g / eq. or more. The epoxy equivalent means the mass of the epoxy monomer per equivalent of the epoxy group contained in the epoxy monomer.

[0060] Examples of epoxy monomers include monofunctional epoxy compounds such as n-butyl glycidyl ether, higher alcohol glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, p-sec-butylphenyl glycidyl ether, and t-butylphenyl glycidyl ether; diepoxy alkanes such as 1,5-hexadiene diepoxide, 1,7-octadiene diepoxide, and 1,9-decadiene diepoxide; (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, and (poly)propylene glycol diglycidyl ether. Examples of such epoxy compounds include polyfunctional epoxy compounds having an ether group, such as ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, and sorbitol polyglycidyl ether; and polyfunctional epoxy compounds having an amino group, such as N,N,N',N'-tetraglycidylmetaxylenediamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0061] The epoxy monomer may be an aromatic epoxy resin, a non-aromatic epoxy resin, or the like, depending on the circumstances. Examples of aromatic epoxy resins include polyphenyl-based epoxy resins, epoxy resins containing a fluorene ring, epoxy resins containing triglycidyl isocyanurate, and epoxy resins containing a heteroaromatic ring (e.g., a triazine ring). Examples of polyphenyl-based epoxy resins include bisphenol A-type epoxy resins, brominated bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, stilbene-type epoxy resins, biphenyl-type epoxy resins, bisphenol A novolac-type epoxy resins, cresol novolac-type epoxy resins, diaminodiphenylmethane-type epoxy resins, and tetrakis(hydroxyphenyl)ethane-based epoxy resins. Examples of non-aromatic epoxy resins include aliphatic glycidyl ether-type epoxy resins, aliphatic glycidyl ester-type epoxy resins, alicyclic glycidyl ether-type epoxy resins, alicyclic glycidyl amine-type epoxy resins, and alicyclic glycidyl ester-type epoxy resins.

[0062] The epoxy monomers can be used alone or in combination of two or more. When a monofunctional epoxy compound is used, it is preferable to use it in combination with another epoxy monomer containing two or more epoxy groups. The monofunctional epoxy compound can also be used as a reactive diluent to adjust the viscosity of the compounds used to form the reactant P1.

[0063] The epoxy monomer preferably includes a multifunctional epoxy compound having an ether group, such as ethylene glycol diglycidyl ether (EDE) or pentaerythritol tetraglycidyl ether (PETG). EDE and PETG have a small epoxy equivalent and can easily lower the glass transition temperature Tg of the polymer P. These epoxy compounds also tend to be low in cost. The epoxy monomer may include a multifunctional epoxy compound having an amino group, such as N,N,N',N'-tetraglycidylmetaxylenediamine or 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, in addition to or instead of the multifunctional epoxy compound having an ether group.

[0064] As described above, the polymer P as an amine polymer may contain a structural unit U1 derived from an epoxy monomer. When the polymer P is a reactant P1, the polymer P further contains a structural unit U2 derived from an amine monomer. The content of the structural unit U1 in the polymer P, particularly the reactant P1, is, for example, 20 wt % to 70 wt %. The content of the structural unit U2 in the polymer P, particularly the reactant P1, is, for example, 30 wt % or more, preferably 50 wt % or more. The upper limit of the content of the structural unit U2 is not particularly limited, and is, for example, 80 wt % or less.

[0065] The polymer P is preferably a solid. In this specification, "solid" means a substance that is in a solid state at atmospheric pressure and 20°C. The polymer P is preferably in a solid state at atmospheric pressure in the range of 20°C to 80°C.

[0066] The glass transition temperature Tg of the polymer P is not particularly limited, and may be, for example, 40 ° C. or lower, 30 ° C. or lower, 20 ° C. or lower, 15 ° C. or lower, 10 ° C. or lower, 5 ° C. or lower, 0 ° C. or lower, -1 ° C. or lower, less than -1 ° C., -2 ° C. or lower, -3 ° C. or lower, -4 ° C. or lower, -5 ° C. or lower, -6 ° C. or lower, -7 ° C. or lower, -8 ° C. or lower, -9 ° C. or lower, -10 ° C. or lower, -11 ° C. or lower, -12 ° C. or lower, -13 ° C. or lower, -14 ° C. or lower, or even -15 ° C. or lower. The lower the glass transition temperature Tg of the polymer P, the higher the rate at which the acidic gas adsorbent adsorbs the acidic gas. The lower limit of the glass transition temperature Tg of the polymer P may be, for example, -100 ° C. or higher, -50 ° C. or higher, -30 ° C. or higher, or even -20 ° C. or higher, from the viewpoint of sufficiently ensuring the adsorption performance of the acidic gas adsorbent, heat resistance, and ease of preparation of the acidic gas adsorbent. In this specification, the glass transition temperature Tg is the midpoint glass transition temperature (T mg ) The polymer P generally corresponds to a thermosetting resin.

[0067] The weight average molecular weight of the polymer P is not particularly limited and is, for example, 500 or more, preferably 1000 or more, more preferably 10000 or more, and even more preferably 100000 or more. The upper limit of the weight average molecular weight of the polymer P is, for example, 10,000,000 or less.

[0068] The content of polymer P in the acidic gas adsorbent is, for example, 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 85 wt% or more, or even 90 wt% or more. The higher the content of polymer P, the more the acidic gas adsorbent tends to improve its acid gas adsorption performance. The upper limit of the content of polymer P in the acidic gas adsorbent is not particularly limited, and may be, for example, 99.9 wt% or less, 99.5 wt% or less, 99 wt% or less, 97 wt% or less, 95 wt% or less, or even 93 wt% or less.

[0069] (Liquid) As described above, the acidic gas adsorbent contains a liquid L having a boiling point of 130°C or higher. In the acidic gas adsorbent, it is preferable that the liquid L is present in the vicinity of the polymer P. In particular, it is preferable that molecules of the liquid L are present between molecular chains of multiple polymers P. As an example, in the acidic gas adsorbent, the polymer P may be compatible with the liquid L or may be swollen by the liquid L.

[0070] The boiling point of Liquid L is preferably 150° C. or higher, and may be 180° C. or higher, 200° C. or higher, 230° C. or higher, 250° C. or higher, 280° C. or higher, or even 300° C. or higher. The upper limit of the boiling point of Liquid L is not particularly limited, and may be, for example, 1000° C. or lower, or 500° C. or lower.

[0071] The liquid L preferably has high polarity and a high dielectric constant. A highly polar liquid L is suitable for stabilizing ions (e.g., carbamate ions) formed by the reaction of amino groups contained in the polymer P with acidic gases (e.g., carbon dioxide). Stabilizing these ions tends to improve the acidic gas adsorption performance of the acidic gas adsorbent.

[0072] The liquid L preferably contains an ionic liquid. In particular, the acidic gas adsorbent may contain only an ionic liquid as the liquid L. In this specification, "ionic liquid" refers to a salt (ionic compound) that is liquid at 20°C.

[0073] In another aspect, the present invention provides an acidic gas adsorbent comprising: a polymer P having an amino group; and an ionic liquid, wherein when the above-mentioned adsorption test A is carried out for 15 hours, the amount of carbon dioxide adsorption a of the acidic gas adsorbent is 0.35 mmol / g or more.

[0074] The ionic liquid preferably contains at least one ion selected from the group consisting of imidazolium ions, pyridinium ions, pyrrolidinium ions, phosphonium ions, ammonium ions, and sulfonium ions, more preferably at least one ion selected from the group consisting of imidazolium ions and phosphonium ions, and particularly preferably a phosphonium ion. These ions preferably contain a substituent having one or more carbon atoms.

[0075] Examples of the substituent having one or more carbon atoms include an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 3 to 14 carbon atoms, and an aryl group having from 6 to 20 carbon atoms. These substituents may be further substituted with a hydroxyl group, a cyano group, an amino group, a monovalent ether group, etc. Examples of the ether group include polyalkylene glycol groups such as polyethylene glycol.

[0076] Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, an n-eicosadecyl group, an i-propyl group, a sec-butyl group, an i-butyl group, a 1-methylbutyl group, a 1-ethylpropyl group, a 2-methylbutyl group, an i-pentyl group, a neopentyl group, a 1,2-dimethylpropyl group, a 1,1-dimethylpropyl group, a t-pentyl group, a 2-ethylhexyl group, and a 1,5-dimethylhexyl group.

[0077] The alkyl group may be substituted with a cycloalkyl group. The number of carbon atoms in the alkyl group substituted with a cycloalkyl group is, for example, 1 to 20. Examples of the alkyl group substituted with a cycloalkyl group include a cyclopropylmethyl group, a cyclobutylmethyl group, a cyclohexylmethyl group, and a cyclohexylpropyl group.

[0078] Examples of the cycloalkyl group having 3 to 14 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a norbornyl group, a bornyl group, and an adamantyl group.

[0079] Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, a toluyl group, a xylyl group, a mesityl group, an anisyl group, a naphthyl group, and a benzyl group.

[0080] The phosphonium ion may be represented by the following formula (1):

[0081] In formula (1), R 1 ~R 4 are each independently the above-mentioned substituents having 1 or more carbon atoms, and are preferably alkyl groups having 1 to 20 carbon atoms. 1 ~R 4 Preferred examples of the phosphonium ion include an n-butyl group, an n-hexyl group, and an n-tetradecyl group. Specific examples of the phosphonium ion include a tetrabutylphosphonium ion (P 4,4,4,4 ), trihexyltetradecylphosphonium ion (P 6,6,6,14 ) etc.

[0082] The imidazolium ion may be represented by the following formula (2):

[0083] In formula (2), R 5 ~R 9 are each independently a hydrogen atom or the above-mentioned substituent having one or more carbon atoms. 5 is preferably a substituent having 1 or more carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, and particularly preferably an ethyl group. 7 is preferably a substituent having 1 or more carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, and particularly preferably a methyl group. 6 , R 8 and R 9are preferably hydrogen atoms. Specific examples of imidazolium ions include 1-ethyl-3-methylimidazolium ion (EMIm).

[0084] In the ionic liquid, the above-mentioned ions may form salts with counter anions such as alkylsulfonate, tosylate, dimethylbenzenesulfonate, trifluoromethanesulfonate, acetate, bis(fluorosulfonyl)imide, bis(trifluoromethanesulfonyl)imide, thiocyanate, dicyanamide, tricyanomethanide, tetracyanoborate, hexafluorophosphate, tetrafluoroborate, halide, and amino acid ions (e.g., valinate).

[0085] A specific example of an ionic liquid is tetrabutylphosphonium 2,4-dimethylbenzenesulfonate ([P 4,4,4,4 ] [2,4MeSO3]), trihexyltetradecylphosphonium valinate ([P 6,6,6,14] [Val]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm][BF4]), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIm][TFSI]), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([EMIm][FSI]), 1-ethyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium bromine imide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium tetrachloroferrate, 1-butyl-3-methylimidazolium iodide, 1-butyl-2,3-dimethylimidazolium chloride chloride, 1-butyl-2,3-dimethylimidazolium hexafluorophosphate, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium trifluoro(trifluoromethyl)borate, 1-butyl-3-methylimidazolium tribromide, 1,3-dimesitylimidazolium chloride, 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride, 1,3-diisopropylimidazolium tetrafluoroborate, 1,3-di-tert-butylimidazolium tetrafluoroborate, 1,3-dicyclohexylimidazolium tetrafluoroborate, 1,3-dicyclohexylimidazolium chloride, 1,2-dimethyl-3-propylimidazolium iodide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium bromide, 1-methyl-3-propylimidazolium iodide, 1-methyl-3-n-octylimidazolium bromide, 1-methyl-3-n-octylimidazolium Examples of suitable imidazolium compounds include 1-methyl-3-n-octylimidazolium hexafluorophosphate, 1-methyl-3-[6-(methylsulfinyl)hexyl]imidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium tricyanomethanide, 1-ethyl-3-methylimidazolium tetracyanoborate, and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0086] The ionic liquid preferably has temperature responsiveness. In this specification, "temperature responsiveness" means that the properties (particularly, solubility in water) change in response to a change in temperature. In particular, the ionic liquid preferably exhibits lower critical solution temperature (LCST) phase separation behavior in water. Examples of ionic liquids that exhibit LCST-type phase separation behavior include [P 4,4,4,4 ] [2,4MeSO3], [P 6,6,6,14 ][Val] and the like.

[0087] Whether an ionic liquid exhibits LCST-type phase separation behavior in water can be confirmed, for example, by the following tests 1 and 2. Specifically, if the ionic liquid dissolves in water in test 1 and if the ionic liquid does not dissolve in water and phase separation is confirmed in test 2, it can be determined that the ionic liquid exhibits LCST-type phase separation behavior in water. Test 1: 0.5 g of ionic liquid is added to a container such as a microtube, and 0.5 g of water (ion-exchanged water) at 20°C is then added to the container. The container is then sealed and shaken by hand approximately 10 times. The container is allowed to stand for 1 minute, and the ionic liquid is visually confirmed to have dissolved in water. Test 2: The same procedure as test 1 is performed, except that the water temperature is changed to 50°C. The ionic liquid is visually confirmed to have dissolved in water.

[0088] The ionic liquid does not have to be temperature responsive. As an example, the ionic liquid may be one that dissolves in water in both Tests 1 and 2. In this specification, an ionic liquid that dissolves in water in both Tests 1 and 2 may be referred to as a "hydrophilic ionic liquid." Examples of hydrophilic ionic liquids include [EMIm][BF4].

[0089] The ionic liquid may be one that is insoluble in water and undergoes phase separation in both the above tests 1 and 2. In this specification, an ionic liquid that is insoluble in water in both tests 1 and 2 may be referred to as a "hydrophobic ionic liquid." Examples of hydrophobic ionic liquids include [EMIm][TFSI], [EMIm][FSI], and the like.

[0090] Liquid L may contain an aprotic polar solvent instead of or in addition to the ionic liquid. Specific examples of the aprotic polar solvent include dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0091] The content of liquid L in the acidic gas adsorbent is, for example, 0.1 wt% or more, and may be 0.5 wt% or more, 1 wt% or more, 3 wt% or more, 5 wt% or more, 7 wt% or more, or even 10 wt% or more. The higher the content of liquid L, the more likely the acidic gas adsorbent is to suppress the deterioration of its adsorption performance for acidic gases in a low-humidity environment. Furthermore, from the viewpoint of adjusting the content of polymer P having the function of adsorbing acidic gases to a high level, the content of liquid L is preferably 70 wt% or less, and may be 60 wt% or less, 50 wt% or less, 40 wt% or less, 30 wt% or less, 20 wt% or less, or even 15 wt% or less. The content of liquid L in the acidic gas adsorbent is preferably 1 wt% to 15 wt%.

[0092] (Other Components) The acidic gas adsorbent may be composed substantially only of the polymer P and the liquid L, but may also contain other components. Examples of other components include a reaction accelerator, a plasticizer, a pigment, a dye, an antioxidant, a conductive material, an antistatic agent, an ultraviolet absorber, a flame retardant, and an antioxidant. A reaction accelerator can be used when synthesizing the polymer P. Examples of reaction accelerators include tertiary amines such as triethylamine and tributylamine; and imidazoles such as 2-phenol-4-methylimidazole, 2-ethyl-4-methylimidazole, and 2-phenol-4,5-dihydroxyimidazole. These reaction accelerators can accelerate the reaction for synthesizing the reactant P1.

[0093] (Acidic Gas Adsorbent) The weight ratio of nitrogen elements in the acidic gas adsorbent is, for example, 1 wt% or more, and may be 5 wt% or more, or even 10 wt% or more. The higher this weight ratio, the more the acidic gas adsorbent tends to improve its ability to adsorb acidic gases. The upper limit of the weight ratio of nitrogen elements in the acidic gas adsorbent is not particularly limited, and is, for example, 30 wt% or less. Note that when all of the nitrogen elements contained in the acidic gas adsorbent are derived from amino groups, the weight ratio of the nitrogen elements can be considered to be the weight ratio of amino groups in the acidic gas adsorbent.

[0094] The density of the nitrogen element in the acidic gas adsorbent is, for example, 10.0 mmol / g or more, 11.0 mmol / g or more, 12.0 mmol / g or more, 12.2 mmol / g or more, 12.5 mmol / g or more, 13.0 mmol / g or more, 13.5 mmol / g or more, 14.0 mmol / g or more, 14.5 mmol / g or more, 15.0 mmol / g or more, 15.5 mmol / g or more, 16.0 mmol / g or more, 16.5 mmol / g or more, 17.0 mmol / g or more, or even 17.5 mmol / g or more. The upper limit of the density of the nitrogen element in the acidic gas adsorbent is not particularly limited, and may be, for example, 30 mmol / g or less, or 20 mmol / g or less. In this specification, the density of the nitrogen element in the acidic gas adsorbent means the amount of nitrogen element contained in 1 g of the acidic gas adsorbent, and can be measured, for example, by the same method as the density of the nitrogen element in the above-mentioned polymer P. When all of the nitrogen elements contained in the acidic gas adsorbent are derived from amino groups, the density of the nitrogen elements can be considered to be the density of the amino groups in the acidic gas adsorbent.

[0095] The shape of the acidic gas adsorbent is not particularly limited and may be, for example, a block, a sheet, a particle, etc. In this specification, the particle shape includes a spherical shape, an ellipsoidal shape, a scale shape, a fiber shape, etc.

[0096] The acidic gas adsorbent may have a porous structure. As an example, the acidic gas adsorbent may include a porous body S containing a polymer P and a liquid L. The shape of the porous body S may be, for example, a block, a sheet, or a particle. The acidic gas adsorbent may or may not include a porous resin sheet as the porous body S. The acidic gas adsorbent may or may not include a member other than the porous body S, such as a carrier for supporting the polymer P. When the acidic gas adsorbent does not include a carrier, the shape of the acidic gas adsorbent tends to be easily adjustable by cutting or machining.

[0097] The porous body S preferably has a three-dimensional network skeleton containing the polymer P and the liquid L. The three-dimensional network skeleton may further contain components other than the polymer P and the liquid L. As an example, in the porous body S, the above-mentioned three-dimensional network skeleton extends continuously. The pores contained in the porous body S are preferably continuous pores formed continuously in a three-dimensional manner. The porous body S may have closed pores or may have through pores that penetrate the porous body S.

[0098] The specific surface area of ​​the acidic gas adsorbent (porous body S) is not particularly limited, and may be, for example, 0.5 m 2 / g or more, and 1.0m 2 / g or more, 2.0m 2 / g or more, 3.0m 2 / g or more, 4.0m 2 / g or more, 5.0m 2 / g or more, 6.0m 2 / g or more, 7.0m 2 / g or more, 8.0m 2 / g or more, and even 9.0m 2 / g or more. The larger the specific surface area of ​​the acidic gas adsorbent, the faster the rate at which the acidic gas adsorbent adsorbs the acidic gas tends to increase. The upper limit of the specific surface area of ​​the acidic gas adsorbent is not particularly limited, and may be, for example, 100 m 2 / g or less. The specific surface area of ​​the acidic gas adsorbent means the Brunauer-Emmett-Teller (BET) specific surface area determined by nitrogen gas adsorption. The specific surface area of ​​the acidic gas adsorbent can be measured by a method conforming to the provisions of JIS Z8830:2013.

[0099] The pore volume of the acidic gas adsorbent (porous body S) is not particularly limited, and may be, for example, 0.1 cm 3 / g or more, and 3 / g or more, 0.3cm 3 / g or more, 0.5cm 3 / g or more, 1.0cm 3 / g or more, and even 2.0 cm 3 The upper limit of the pore volume of the acidic gas adsorbent is not particularly limited, and may be, for example, 5.0 cm 3 / g or less, and 3 / g or less, and 3 The pore volume of the acidic gas adsorbent can be measured by mercury intrusion porosimetry. Mercury intrusion porosimetry is performed using a commercially available pore size distribution analyzer (e.g., Autopore V9620 manufactured by Micromeritics) under an initial pressure of 21 kPa.

[0100] The average pore diameter of the acidic gas adsorbent (porous body S) is not particularly limited and may be, for example, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, or even 0.5 μm or more. The upper limit of the average pore diameter of the acidic gas adsorbent is not particularly limited and may be, for example, 50 μm or less. In this specification, the average pore diameter of the acidic gas adsorbent means the median diameter measured by mercury intrusion porosimetry. Mercury intrusion porosimetry is performed using a commercially available pore size distribution analyzer (e.g., Autopore V9620 manufactured by Micromeritics) under an initial pressure of 21 kPa.

[0101] When the acidic gas adsorbent is particulate, the average particle size of the acidic gas adsorbent is not particularly limited and is, for example, 0.5 μm or more, preferably 1 μm or more, and may be 10 μm or more, 20 μm or more, or 30 μm or more. The average particle size of the acidic gas adsorbent may be 200 μm or less, 100 μm or less, or less than 75 μm. In this specification, the average particle size of the acidic gas adsorbent means the particle size (d50) corresponding to 50% cumulative volume in the particle size distribution measured by a laser diffraction particle sizer or the like.

[0102] (Method for Producing Acidic Gas Adsorbent) The method for producing an acidic gas adsorbent of this embodiment includes, for example, bringing the polymer P into contact with the liquid L.

[0103] As an example, the polymer P can be synthesized by reacting a group of compounds containing an amine monomer (particularly an amine monomer containing a primary amino group), which preferably further contains an epoxy monomer containing an epoxy group.

[0104] The compound group may contain only an epoxy monomer E1 containing two epoxy groups, or may contain an epoxy monomer E2 containing three or more, for example, four, epoxy groups instead of or together with the epoxy monomer E1. When the compound group contains the epoxy monomers E1 and E2, the weight ratio E1 / E2 of the epoxy monomer E1 to the epoxy monomer E2 is not particularly limited and may be, for example, 3 / 7 to 8 / 2, 3 / 7 to 5 / 5, or even 3 / 7 to 4 / 6.

[0105] In this embodiment, the ratio E / A of the equivalent E of the epoxy group in the compound group to the equivalent A of the active hydrogen of the primary amino group in the compound group is preferably 1.00 or less. In particular, it is preferable that the blending ratio of the amine monomer and the epoxy monomer is adjusted so that the ratio E / A is 1.00 or less. In the compound group, the ratio E / A is preferably 0.90 or less, and may be 0.50 or less, less than 0.50, 0.45 or less, 0.40 or less, 0.35 or less, or even 0.30 or less. The smaller the ratio E / A, the higher the ratio of primary amino groups in the polymer P and the higher the density of nitrogen elements in the acidic gas adsorbent. From the viewpoint of ease of preparation of the acidic gas adsorbent, the lower limit of the ratio E / A may be, for example, 0.10 or more, 0.15 or more, or even 0.20 or more.

[0106] In this embodiment, it is preferable that the primary amino group of the amine monomer reacts with the epoxy group of the epoxy monomer in the compound group, causing a polymerization reaction or a crosslinking reaction to proceed. The reaction of the compound group can be carried out by applying energy to the compound group. The energy applied to the compound group is preferably thermal energy. As an example, the reaction of the compound group can be promoted by heating the compound group at a temperature of 40°C to 100°C. However, the energy applied to the compound group may also be light energy.

[0107] In this embodiment, a porous body containing polymer P may be produced. This porous body can be produced, for example, by the following method. First, the above-mentioned compounds are mixed with a porogen to produce a mixed solution. The porogen is a solvent that can dissolve the monomers contained in the compounds and, further, can cause reaction-induced phase separation after the compounds have reacted. Specific examples of porogens include cellosolves such as methyl cellosolve and ethyl cellosolve, esters such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, glycols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polyoxyalkylene glycol, and ethers such as polyoxyethylene monomethyl ether and polyoxyethylene dimethyl ether. Specific examples of polyoxyalkylene glycols include poly(1,2-butanediol)-6 propylene glycol and polyoxypropylene diglyceryl ether. The porogen may be a polar solvent such as ethyl acetate, N,N-dimethylformamide (DMF), acetonitrile, ethanol, or isopropanol, a non-polar solvent such as toluene, or a mixture thereof. The porogens may be used alone or in combination of two or more.

[0108] The mixture may further contain components other than the compounds, such as the above-mentioned reaction accelerators.

[0109] Next, the compounds are reacted in the mixture. For example, the mixture is filled into a mold and then heated to react the compounds. This results in a cured product containing the polymer P and the porogen. In this cured product, the polymer P and the porogen undergo phase separation to form a co-continuous structure.

[0110] Next, the porogen is extracted and removed from the cured product. This allows for the production of a porous body containing polymer P. The porogen can be extracted by immersing the cured product in a solvent. Examples of the solvent that can be used include water, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, aliphatic alcohol solvents, ester solvents, ether solvents, and halogen-containing organic solvents. Examples of aliphatic hydrocarbon solvents include n-hexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, isooctane, petroleum ether, and benzine. Examples of aromatic hydrocarbon solvents include toluene, xylene, mesitylene, and benzene. Examples of aliphatic alcohol solvents include methanol, ethanol, isopropanol, butanol, cyclohexanol, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, and diethylene glycol. Examples of ester solvents include ethyl acetate. Examples of ether solvents include diethyl ether, diisopropyl ether, dibutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, and anisole. Examples of halogen-containing organic solvents include dichloromethane, chloroform, carbon tetrachloride, dichloroethane, and chlorobenzene. These solvents can be used alone or in combination of two or more.

[0111] When preparing a cured body, the faster the reaction rate of the compounds, the more finely the porogen tends to be dispersed in the cured body. By removing the porogen from a cured body in which the porogen is finely dispersed, a porous body with a large specific surface area can be prepared. The reaction rate of the compounds varies depending on the type and blending ratio of the monomers contained in the compounds. For example, the reaction rate of the compounds tends to be high when an epoxy monomer E2 containing three or more, for example, four, epoxy groups is used, or when polyethyleneimine with a large weight-average molecular weight is used as the amine monomer.

[0112] In this embodiment, by contacting the polymer P (particularly a porous body containing the polymer P) with the liquid L, for example, the polymer P and the liquid L become compatible with each other, thereby obtaining an acidic gas adsorbent. The method for contacting the polymer P with the liquid L is not particularly limited, and can be performed, for example, by the following method. First, a mixed solution of the liquid L and an alcohol is prepared. As the alcohol, a lower alcohol having 5 or less carbon atoms can be used. The content of the liquid L in the mixed solution is not particularly limited, and is, for example, 0.1 wt % to 20 wt %. Next, the polymer P can be brought into contact with the liquid L by immersing the polymer P in the mixed solution. At this time, the temperature of the mixed solution is, for example, room temperature (20°C). The time for which the polymer P is immersed in the mixed solution is not particularly limited, and is, for example, 0.5 hours to 24 hours.

[0113] After contacting the polymer P with the liquid L, the acidic gas adsorbent may be further subjected to a drying treatment, if necessary. By the drying treatment, for example, alcohol originating from the above-mentioned mixed liquid can be removed from the acidic gas adsorbent. The temperature for the drying treatment is not particularly limited as long as it is a temperature lower than the boiling point of the liquid L, and is, for example, 20°C to 60°C. The time for the drying treatment is, for example, 0.5 hours to 24 hours. The drying treatment may be performed under a reduced pressure atmosphere or a vacuum atmosphere.

[0114] (Characteristics of Acidic Gas Adsorbent) As described above, adsorbents containing amine compounds tend to have reduced adsorption performance for acidic gases in low-humidity environments (for example, environments of 20°C and 30% RH or less). This tendency is presumably due to the fact that, in low-humidity environments, there is almost no water present near the amine compound, which reduces the mobility of the molecular chains of the amine compound and makes it difficult for acidic gases to diffuse in the adsorbent.

[0115] In contrast, in this embodiment, the acidic gas adsorbent contains polymer P and liquid L. The presence of liquid L makes it difficult for the mobility of the molecular chains of polymer P to decrease even in a low-humidity environment, and therefore the diffusibility of acidic gases in the acidic gas adsorbent to decrease. As a result, the acidic gas adsorbent of this embodiment tends to suppress a decrease in its adsorption performance for acidic gases in a low-humidity environment.

[0116] As an example, when the acidic gas adsorbent of this embodiment is subjected to the following adsorption test B for 15 hours, it is preferable that the carbon dioxide adsorption amount b1 is 0.1 mmol / g or more. In the adsorption test B, a mixed gas G2 is used as the low-humidity gas. Adsorption test B: A mixed gas G2 composed of carbon dioxide, nitrogen, and water vapor is continuously fed into a container containing the acidic gas adsorbent. Here, the carbon dioxide concentration in the mixed gas G2 is 400 vol ppm, and the mixed gas G2 has a temperature of 20°C and a humidity of 20% RH.

[0117] Adsorption test B can be performed in the same manner as adsorption test A, except that mixed gas G2 is used instead of mixed gas G1. Mixed gas G2 can be prepared by changing the flow rate of nitrogen passing through first path 60 and bypass path 61 of measurement device 20 from the conditions of adsorption test A.

[0118] The carbon dioxide adsorption amount b1 when Adsorption Test B is performed for 15 hours is preferably 0.3 mmol / g or more, and may be 0.5 mmol / g or more, 0.6 mmol / g or more, 0.7 mmol / g or more, 0.8 mmol / g or more, 0.9 mmol / g or more, 1.0 mmol / g or more, 1.1 mmol / g or more, 1.2 mmol / g or more, 1.3 mmol / g or more, 1.4 mmol / g or more, or even 1.5 mmol / g or more. The upper limit of the carbon dioxide adsorption amount b1 is not particularly limited, and may be, for example, 10 mmol / g or less.

[0119] When the above-described adsorption test B is performed for one hour on the acidic gas adsorbent of this embodiment, the carbon dioxide adsorption amount b2 is preferably 0.01 mmol / g or more. The adsorption amount b2 can be used as an indicator of the rate at which the acidic gas adsorbent adsorbs acidic gases in a low-humidity environment. In other words, the larger the adsorption amount b2, the faster the acidic gas adsorbent adsorbs acidic gases in a low-humidity environment.

[0120] The carbon dioxide adsorption amount b2 when Adsorption Test B is performed for 1 hour is preferably 0.03 mmol / g or more, and may be 0.05 mmol / g or more, 0.08 mmol / g or more, 0.1 mmol / g or more, 0.2 mmol / g or more, 0.3 mmol / g or more, 0.4 mmol / g or more, or even 0.5 mmol / g or more. The upper limit of the carbon dioxide adsorption amount b2 is not particularly limited, and is, for example, 5 mmol / g or less.

[0121] When the above-described adsorption test B is performed for 4 hours on the acidic gas adsorbent of this embodiment, the carbon dioxide adsorption amount b3 is preferably 0.05 mmol / g or more. The adsorption amount b3 can also be used as an indicator of the rate at which the acidic gas adsorbent adsorbs acidic gases in a low-humidity environment. In other words, the larger the adsorption amount b3, the faster the acidic gas adsorbent adsorbs acidic gases in a low-humidity environment.

[0122] The carbon dioxide adsorption amount b3 when Adsorption Test B is performed for 4 hours is preferably 0.1 mmol / g or more, and may be 0.3 mmol / g or more, 0.4 mmol / g or more, 0.5 mmol / g or more, 0.6 mmol / g or more, 0.7 mmol / g or more, 0.8 mmol / g or more, 0.9 mmol / g or more, 1.0 mmol / g or more, or even 1.05 mmol / g or more. The upper limit of the carbon dioxide adsorption amount b3 is not particularly limited, and is, for example, 5 mmol / g or less.

[0123] Furthermore, when the acidic gas adsorbent of this embodiment is subjected to the following desorption test C, it is preferable that the carbon dioxide desorption amount c is 0.05 mmol / g or more. Desorption test C: While continuing to feed the mixed gas G2 into the above-mentioned container, the acidic gas adsorbent after the adsorption test B for 15 hours is heated at 65°C for 1.5 hours.

[0124] Desorption test C can be performed by the following method. First, the above-mentioned adsorption test B is performed for 15 hours using the measuring device 20. More specifically, while the mixed gas G2 is being supplied to the adsorption unit 21, the adsorption unit 21 is immersed in water 71 in the third container 42, and the mixed gas G2 is continuously supplied to the adsorption unit 21 for 15 hours. Next, while the mixed gas G2 is being continuously supplied to the adsorption unit 21, the adsorption unit 21 is removed from the third container 42 and immersed in a water bath (not shown) at 65°C. This starts a carbon dioxide desorption test (desorption test C) for the acidic gas adsorbent in the adsorption unit 21. The desorption test is performed for 1.5 hours after the start of the test.

[0125] In desorption test C, the amount of carbon dioxide desorbed from the acid gas adsorbent within 1.5 hours from the start is measured, M2. The amount of carbon dioxide desorbed from the acid gas adsorbent can be calculated from the results of measuring the difference over time between the carbon dioxide concentration measured by first concentration meter 50 and the carbon dioxide concentration measured by second concentration meter 51. The amount of carbon dioxide desorbed from 1 g of the acid gas adsorbent in 1.5 hours is calculated based on the amount of substance M2, and the calculated value is specified as the desorption amount c.

[0126] In the acidic gas adsorbent of this embodiment, the carbon dioxide desorption amount c when desorption test C is performed is preferably 0.1 mmol / g or more, and may be 0.3 mmol / g or more, 0.5 mmol / g or more, 0.6 mmol / g or more, 0.7 mmol / g or more, 0.8 mmol / g or more, 0.9 mmol / g or more, 1.0 mmol / g or more, 1.1 mmol / g or more, 1.2 mmol / g or more, 1.3 mmol / g or more, 1.4 mmol / g or more, or even 1.5 mmol / g or more. The upper limit of the carbon dioxide desorption amount c is not particularly limited, and may be, for example, 10 mmol / g or less.

[0127] The ratio of the desorption amount c (mmol / g) to the adsorption amount b1 (mmol / g) (65°C desorption rate) is, for example, 40% or more, and may be 45% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 96% or more, or even 97% or more, or may be 100%.

[0128] (Uses of Acidic Gas Adsorbent) The acidic gas adsorbent of the present embodiment can adsorb acidic gases. Examples of acidic gases include carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur oxides (SOx), hydrogen cyanide, and nitrogen oxides (NOx), and carbon dioxide is preferred.

[0129] The acidic gas adsorbent can be used by the following method. First, a mixed gas containing an acidic gas is contacted with the acidic gas adsorbent. The mixed gas preferably contains other gases in addition to the acidic gas. Examples of other gases include non-polar gases such as hydrogen and nitrogen, and inert gases such as helium, with nitrogen being preferred. The mixed gas is typically atmospheric air. The mixed gas may also be off-gas from a chemical plant or thermal power plant.

[0130] The temperature of the mixed gas is, for example, room temperature (20°C). The concentration of the acidic gas in the mixed gas is not particularly limited and, under standard conditions (0°C, 101 kPa), is, for example, 0.01 vol% (100 volppm) or more, preferably 0.04 vol% (400 volppm) or more, and may be 1.0 vol% or more. The upper limit of the carbon dioxide concentration in the mixed gas is not particularly limited and, under standard conditions, is, for example, 10 vol% or less. The pressure of the mixed gas is typically equal to atmospheric pressure in the environment in which the acidic gas adsorbent is used. However, the mixed gas to be contacted with the acidic gas adsorbent may be pressurized.

[0131] The acidic gas adsorbent that has come into contact with the mixed gas adsorbs the acidic gas contained in the mixed gas. The operation of bringing the mixed gas into contact with the acidic gas adsorbent is preferably carried out until the adsorption of the acidic gas by the acidic gas adsorbent reaches equilibrium.

[0132] Next, the acidic gas adsorbent that has adsorbed the acidic gas is regenerated. The regeneration can be performed by heating the acidic gas adsorbent. The heating temperature of the acidic gas adsorbent is, for example, 50 to 80°C. The acidic gas adsorbent may be heated under a reduced pressure or a vacuum. By heating the acidic gas adsorbent, the acidic gas is desorbed from the acidic gas adsorbent. This regenerates the acidic gas adsorbent, allowing it to be reused. The acidic gases, particularly carbon dioxide, desorbed from the acidic gas adsorbent can be used as raw materials for chemical synthesis or as dry ice. The adsorption of acidic gases by the acidic gas adsorbent and the regeneration of the acidic gas adsorbent can be performed using the measuring device 20 (acidic gas adsorption device) described above.

[0133] 2A , the structure 15 of this embodiment includes the acidic gas adsorbent 10 and ventilation paths 14. The structure 15 is typically a honeycomb structure having a plurality of ventilation paths 14 extending in the same direction.

[0134] The acidic gas adsorbent 10 included in the structure 15 typically has a sheet shape. The structure 15 may or may not include a support for supporting the acidic gas adsorbent 10 together with the acidic gas adsorbent 10.

[0135] The structure 15 preferably includes an adsorbent unit U in which a corrugated acidic gas adsorbent 10A and a flat-plate acidic gas adsorbent 10B are stacked. In the acidic gas adsorbent 10A, a plurality of peaks 12 and a plurality of valleys 13 are alternately arranged. A ventilation path 14 is formed between the peaks 12 or valleys 13 of the acidic gas adsorbent 10A and the acidic gas adsorbent 10B. In this embodiment, the direction x is the direction (wave direction) in which the plurality of peaks 12 and the plurality of valleys 13 of the acidic gas adsorbent 10A are alternately arranged. The direction y is the stacking direction of the acidic gas adsorbents 10A and 10B in the adsorbent unit U. The direction z is perpendicular to the directions x and y, and is the direction in which the ventilation path 14 extends.

[0136] The structure 15 preferably includes a plurality of adsorbent units U. The number of adsorbent units U in the structure 15 is not particularly limited and may be, for example, 2 to 100. In the structure 15, the plurality of adsorbent units U are stacked in the direction y so that a plurality of acidic gas adsorbents 10A and a plurality of acidic gas adsorbents 10B are arranged alternately. By stacking the plurality of adsorbent units U, the structure 15 has a block shape.

[0137] The ventilation path 14 is a through-hole that penetrates the structure 15 in the direction z. The ventilation path 14 is surrounded by the acidic gas adsorbents 10A and 10B. In the structure 15, the acidic gas moves in the direction z through the ventilation path 14 and is efficiently adsorbed by the acidic gas adsorbents 10A and 10B.

[0138] In the structure 15, the smaller the thickness of the acidic gas adsorbents 10A and 10B, the larger the cross-sectional area of ​​the ventilation path 14 can be adjusted. A structure 15 with a large cross-sectional area of ​​the ventilation path 14 is suitable for reducing pressure loss that occurs when the structure 15 comes into contact with acidic gas. A structure 15 with reduced pressure loss can reduce the power of the fan used to move the acidic gas. Note that if the amount of amino group substance per unit volume of the acidic gas adsorbent 10 is large, the acidic gas adsorbent 10 tends to be able to sufficiently adsorb acidic gases even when the thickness of the acidic gas adsorbent 10 is small.

[0139] <Modifications of the Structure> The shape of the structure 15 including the acidic gas adsorbent 10 is not limited to that shown in Fig. 2A. The structure 16 shown in Fig. 2B has a shape in which one adsorbent unit U is wound around a central tube 80. Except for this, the configuration of the structure 16 is the same as the configuration of the structure 15.

[0140] The structure 16 has a cylindrical shape. In the structure 16, the multiple peaks 12 and the multiple valleys 13 of the acidic gas adsorbent 10A are alternately arranged in the circumferential direction of the structure 16. The ventilation paths 14 formed between the peaks 12 or valleys 13 of the acidic gas adsorbent 10A and the acidic gas adsorbent 10B penetrate the structure 16 in the extension direction of the central tube 80. In the structure 16, the acidic gas moves through the ventilation paths 14 in the extension direction of the central tube 80 and is efficiently adsorbed by the acidic gas adsorbents 10A and 10B.

[0141] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0142] Comparative Example 1 First, 1.50 g of poly(1,2-butanediol)-6 propylene glycol (NOF Corporation, Uniol (registered trademark) PB-500) and 0.64 g of a butylene glycol and propylene glycol copolymer (NOF Corporation, Uniol (registered trademark) PB-700) were added to a 6 mL screw tube bottle (manufactured by AS ONE Corporation). 1.28 g of ethylene glycol diglycidyl ether (Nagase ChemteX Corporation, EX-810) was dissolved in the resulting mixture to prepare a mixture of epoxy monomer and porogen.

[0143] Next, 1.70 g of polyethyleneimine (Epomin SP-012, manufactured by Nippon Shokubai Co., Ltd.) was added to this mixture to prepare a mixture of epoxy monomer, amine monomer, and porogen. In this mixture, the ratio E / A of the equivalent weight E of the epoxy group contained in the epoxy monomer to the equivalent weight A of the active hydrogen of the primary amino group contained in the amine monomer was 0.5.

[0144] Next, the mixture was shaken for 2 minutes using a tabletop shaker (Angel Vibrator Digital 60 Hz) set to intensity 5. Next, the mixture was allowed to stand in a thermostatic chamber at 80°C for 2 hours to harden. This resulted in a block-shaped cured product containing polymer P having amino groups. The cured product was removed from the screw cap bottle and cut into approximately 3 mm square pieces. The cured product was then immersed in ethyl acetate at 60°C for 1 hour, and this operation was repeated twice with liquid changes. This removed the porogen from the cured product, forming a porous body containing polymer P. This porous body was dried at 60°C for 1 hour and then vacuum-dried for another 2 hours. This resulted in the acidic gas adsorbent of Comparative Example 1.

[0145] Example 1 First, a porous body containing polymer P was prepared by the same method as in Comparative Example 1. Next, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIm][TFSI]) as liquid L was mixed with methanol to prepare a mixed liquid. The content of liquid L in the mixed liquid was 1 wt %. Next, the porous body containing polymer P was immersed in the mixed liquid for 18 hours at room temperature (20°C). This caused polymer P and liquid L to come into contact and become compatible with each other. Next, the mixed liquid was transferred to a recovery flask, and the solvent was distilled off using an evaporator. The porous body was removed from the recovery flask and subjected to a drying treatment at 60°C for 2 hours to obtain an acidic gas adsorbent of Example 1 containing polymer P and liquid L.

[0146] Examples 2 to 4 Acidic gas adsorbents of Examples 2 to 4 were obtained in the same manner as in Example 1, except that the type of liquid L used was changed as shown in Table 1.

[0147] The boiling points of all of the liquids L used in Examples 1 to 4 were significantly higher than 130°C.

[0148] [Amount of carbon dioxide adsorption] The above-mentioned adsorption test A was carried out on the acidic gas adsorbents prepared in the examples and comparative examples. In the adsorption test A, the amount of carbon dioxide adsorbed by the acidic gas adsorbent was measured over time. Table 1 shows the amount of carbon dioxide adsorbed 30 minutes, 60 minutes, 90 minutes, 240 minutes, and 900 minutes (15 hours) after the start of the adsorption test A.

[0149] Furthermore, the above-mentioned Adsorption Test B was performed on the acidic gas adsorbents prepared in the Examples and Comparative Examples. In Adsorption Test B, the amount of carbon dioxide adsorbed by the acidic gas adsorbent was measured over time. In Adsorption Test B, after 900 minutes (15 hours) had elapsed from the start, the acidic gas adsorbent was heated to 50 to 80°C, and carbon dioxide was desorbed from the acidic gas adsorbent. Table 1 shows the amounts of carbon dioxide adsorbed 30 minutes, 60 minutes, 90 minutes, 240 minutes, and 900 minutes (15 hours) after the start of Adsorption Test B. Furthermore, Figure 3 shows the relationship between the time from the start of Adsorption Test B and the amount of carbon dioxide adsorbed.

[0150]

[0151] The abbreviations in Table 1 are as follows: [EMIm][TFSI]: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [EMIm][BF4]: 1-ethyl-3-methylimidazolium tetrafluoroborate [P 4,4,4,4 ][2,4MeSO3]: tetrabutylphosphonium 2,4-dimethylbenzenesulfonate [P 6,6,6,14 ][Val]: trihexyltetradecylphosphonium valinate

[0152] As can be seen from Table 1 and Figure 3, the acidic gas adsorbents of the examples containing liquid L had a larger carbon dioxide adsorption amount when adsorption test B was performed (particularly, the adsorption amount b1 when adsorption test B was performed for 15 hours) than the comparative examples, and tended to suppress the decline in adsorption performance for acidic gases in low-humidity environments.

[0153] The acidic gas adsorbent of this embodiment can adsorb carbon dioxide in the atmosphere.

Claims

1. An acidic gas adsorbent comprising a polymer having an amino group and a liquid having a boiling point of 130° C. or higher, wherein when the following adsorption test A is performed for 15 hours, the carbon dioxide adsorption amount a is 0.35 mmol / g or more. Adsorption test A: A mixed gas G1 composed of carbon dioxide, nitrogen, and water vapor is continuously sent into a container containing the acidic gas adsorbent. Here, the concentration of carbon dioxide in the mixed gas G1 is 400 volppm, the mixed gas G1 has a temperature of 20° C., and a humidity of 50% RH.

2. The acidic gas adsorbent according to claim 1, wherein the polymer is a solid.

3. The acidic gas adsorbent according to claim 1, wherein the polymer contains an amine polymer having a structural unit derived from an epoxy monomer.

4. The acidic gas adsorbent according to claim 3, wherein the amine polymer contains a reaction product of a group of compounds including an amine monomer and an epoxy monomer.

5. The acidic gas adsorbent according to claim 4, wherein the amine monomer contains polyethyleneimine.

6. The acidic gas adsorbent according to claim 1, wherein the glass transition temperature of the polymer is 40° C. or lower.

7. The acidic gas adsorbent according to claim 1, wherein the liquid contains an ionic liquid.

8. The acidic gas adsorbent according to claim 7, wherein the ionic liquid has temperature responsiveness.

9. The acidic gas adsorbent according to claim 1, wherein the content of the liquid is 1 wt% to 15 wt%.

10. The acidic gas adsorbent according to claim 1, which has a porous structure.

11. The acidic gas adsorbent according to claim 1, wherein when the following adsorption test B is performed for 15 hours, the carbon dioxide adsorption amount b1 is 0.1 mmol / g or more. Adsorption test B: A mixed gas G2 composed of carbon dioxide, nitrogen, and water vapor is continuously sent into a container containing the acidic gas adsorbent. Here, the concentration of carbon dioxide in the mixed gas G2 is 400 volppm, the mixed gas G2 has a temperature of 20° C., and a humidity of 20% RH.

12. The acidic gas adsorbent according to claim 11, wherein when the adsorption test B is performed for 1 hour, the carbon dioxide adsorption amount b2 is 0.01 mmol / g or more.

13. A structure comprising the acidic gas adsorbent according to any one of claims 1 to 12 and a ventilation path.

14. An acidic gas adsorption device comprising an adsorption section having a gas inlet and a gas outlet, wherein the adsorption section contains the acidic gas adsorbent according to any one of claims 1 to 12.

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