Gas absorbing material, gas absorbent and its manufacturing method, and gas separation apparatus

Abstract

This invention provides a gas-absorbing material with excellent gas absorption and release properties using a polymer compound containing an amino group. [Solution] A gas-absorbing material comprising polymer compound particles having amino groups and fine particles with a primary particle diameter of 1000 nm or less containing silica or carbon. The average primary particle diameter of the fine particles is smaller than the median diameter of the polymer compound particles having amino groups in a dry state. The polymer compound particles having amino groups comprise a polymer of a monomer component containing at least one monomer selected from N-(aminoalkyl)acrylamide, N-(aminoalkyl)methacrylamide, aminoalkyl acrylate, and aminoalkyl methacrylate.

Description

[Technical Field]

[0001] The present invention relates to a gas absorption material with excellent reversible absorption performance of gases such as carbon dioxide, a gas absorber, a gas separation material, a filter, and a gas separation device using the gas absorption material. [Background technology]

[0002] In recent years, global warming caused by carbon dioxide emissions from large-scale facilities such as thermal power plants, steel mills, and cement factories, as well as environmental pollution from hydrogen sulfide and other gases, have become serious problems. To mitigate climate change and environmental pollution and realize a low-carbon society, research is underway on Carbon dioxide Capture and Storage (CCS), a method of separating and recovering carbon dioxide and acidic gases such as hydrogen sulfide from exhaust gases containing a large amount of water vapor emitted from these large-scale facilities and sequestering them underground or beneath the seabed. However, current technology results in very high energy costs for CCS, and a significant reduction in energy costs is required. In particular, since the carbon dioxide separation and recovery process accounts for approximately 60% of the energy costs in CCS, improving the efficiency of the carbon dioxide separation and recovery process and significantly reducing energy consumption are essential to reducing energy costs in CCS. Furthermore, in the field of energy supply, processes are being carried out to separate and recover carbon dioxide, acidic gases such as hydrogen sulfide, and water vapor from fuel gases such as natural gas with high carbon dioxide concentrations, coal gas produced in integrated gasification combined cycle (IGCC) power plants, and hydrogen used in fuel cells. Improving the efficiency and energy conservation of these carbon dioxide separation and recovery processes is also important for reducing energy costs in these fields. Here, gas separation and recovery is specifically carried out using a reversible gas absorption process that first absorbs the target gas and then releases it. Therefore, in order to reduce the energy costs mentioned above, there is active development of gas absorption materials that can efficiently absorb and release acidic gases such as carbon dioxide at low cost.

[0003] For example, Patent Documents 1 and 2 propose using gel particles of polymer compounds having amino groups as gas absorbent materials. These gel particles exhibit gas absorption and release properties; they are highly basic at temperatures of around 30°C and absorb carbon dioxide, but when heated to around 75°C, their basicity decreases and they release carbon dioxide. It is claimed that by utilizing these properties, an inexpensive gas absorbent material with excellent reversible gas absorption performance can be provided. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2016 / 024633 [Patent Document 2] International Publication No. 2017 / 146231 [Overview of the project] [Problems that the invention aims to solve]

[0005] As described above, gel particles of polymer compounds containing amino groups are known to have excellent gas absorption and release properties. When the inventors evaluated the practicality of these gel particles, they confirmed that excellent gas absorption and release properties could be obtained by actually forming the gel particles into a film or packing them into a column. On the other hand, it was found that simply forming the gel particles into a film or packing them into a column has limitations in further improving gas absorption and release properties, and that it is necessary to devise new approaches.

[0006] Therefore, in order to solve the problems of the conventional technology, the present inventors proceeded with research with the aim of providing a gas-absorbing material that has an even faster gas absorption and release rate by using polymer compound particles having amino groups. [Means for solving the problem]

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that when fine particles having a primary particle diameter of 1000 nm or less are added to a gas absorption material using polymer compound particles having an amino group, the gas absorption rate and the dissipation rate are remarkably improved. The present invention has been proposed based on such findings, and specifically, has the following configurations.

[0008] [1] A gas absorption material containing polymer compound particles having an amino group and fine particles having a primary particle diameter of 1000 nm or less (excluding the polymer compound particles having an amino group). [2] The gas absorption material according to [1], wherein the fine particles are particles containing silica or carbon. [3] The gas absorption material according to [1] or [2], wherein the water contact angle of the fine particles is 70° or more. [4] The gas absorption material according to any one of [1] to [3], wherein the fine particles are particles containing carbon black or a fluororesin. [5] The gas absorption material according to any one of [1] to [4], wherein the fine particles have a base material particle and a water-repellent film formed on the surface of the base material particle. [6] The gas absorption material according to [5], wherein the water-repellent film contains dialkyl polysiloxane. [7] The gas absorption material according to any one of [1] to [4], wherein the fine particles are those obtained by subjecting base material particles to surface modification for imparting water repellency. [8] The gas absorption material according to [7], wherein the surface modification is a surface modification for introducing an alkyl group into the base material particles. [9] The gas absorption material according to any one of [5] to [8], wherein the base material particles are inorganic fine particles.

[10] The gas absorption material according to any one of [5] to [9], wherein the water contact angle of the base material particles is 70° or more.

[11] The gas absorption material according to any one of [1] to

[10] , wherein the average primary particle diameter of the fine particles is 5 to 200 nm.

[12] The gas absorption material according to any one of [1] to

[11] , wherein the polymer compound particles having an amino group contain a polymer of a monomer component containing a substituted (meth)acrylamide monomer having an amino group.

[13] The gas absorption material according to

[12] , wherein the substituted (meth)acrylamide monomer having an amino group is N-(aminoalkyl)(meth)acrylamide.

[14] The gas absorption material according to any one of [1] to

[13] , wherein the median diameter of the polymer compound particles having an amino group in the dry state is 1 to 50 μm.

[15] The gas absorption material according to any one of [1] to

[14] , wherein the average primary particle diameter of the fine particles is smaller than the median diameter of the polymer compound particles having an amino group in the dry state.

[16] The gas absorption material according to any one of [1] to

[15] , wherein the content of the polymer compound particles having an amino group is larger than the content of the fine particles in terms of solid content.

[17] A gas absorber comprising granulated particles of the gas absorption material according to any one of [1] to

[16] .

[18] A gas absorber comprising a molded body of a mixture containing the gas absorption material according to any one of [1] to

[16] and a thermoplastic resin.

[19] The gas absorber according to

[16] , wherein the mixture contains granulated particles of the gas absorption material as the gas absorption material.

[20] A gas absorber comprising a compacted molded body of the gas absorption material according to any one of [1] to

[16] .

[21] The gas absorber according to any one of

[17] to

[20] , further comprising a filler.

[22] The gas absorber according to

[21] , wherein the filler is activated carbon or zeolite.

[23] A method for producing a gas absorber, comprising the step of putting a composite material obtained by dry-mixing polymer compound particles having an amino group and fine particles having a primary particle diameter of 1000 nm or less into a mold and performing pressure molding.

[24] A gas separation material comprising the gas absorption material according to any one of [1] to

[16] .

[25] The gas separation material according to

[24] , which selectively separates acidic gases from a mixed gas.

[26] The gas separation material according to

[25] , wherein the acidic gas is carbon dioxide. A filter having a gas separation material as described in any one of the items

[27]

[24] to

[26] . A gas separation apparatus having a gas separation material as described in any one of the items

[28]

[24] to

[26] . [Effects of the Invention]

[0009] The gas-absorbing material and gas absorbent of the present invention exhibit fast gas absorption and release rates, and demonstrate excellent reversible gas absorption performance. Therefore, by using the gas-absorbing material and gas absorbent of the present invention as a gas separation material, the time efficiency of the gas separation and recovery process can be improved, and the costs associated with that process can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1] These are scanning electron microscope (SEM) images of the particles used in the examples; (a) is an SEM image of amino group-containing polymer particles 1, and (b) is an SEM image of a composite material of amino group-containing polymer particles 1 and carbon black. [Figure 2] This is an SEM image showing the internal structure of a molded body (gas absorber 1) formed by compacting a composite material into a film. [Figure 3] These are transmission electron microscope images (TEM images) of gas absorber 1, where (a) is a TEM image of a thin section cut from gas absorber 1, and (b) is a TEM image of characteristic X-rays of nitrogen and carbon emitted by energy-dispersive X-ray spectroscopy (EDX). [Figure 4] This graph shows the amount of CO2 absorbed during the absorption process for gas absorber 1 containing amino group-containing polymer particles 1 and carbon black, gas absorber 2 containing amino group-containing polymer particles 1 and water-repellent carbon black, and comparative gas absorber 1 containing only amino group-containing polymer particles 1. [Figure 5]This graph shows the amount of CO2 emitted during the emission process for gas absorber 1 containing amino group-containing polymer particles 1 and carbon black, gas absorber 2 containing amino group-containing polymer particles 1 and water-repellent carbon black, and comparative gas absorber 1 containing only amino group-containing polymer particles 1. [Figure 6] This graph shows the amount of CO2 absorbed during the absorption process of gas absorbers 1, 3-6 containing amino group-containing polymer particles 1 and carbon black, RY200, R805, PTFE particles, or hydrophilic silica 200. [Figure 7] This graph shows the amount of CO2 emitted during the emission process of gas absorbers 1, 3-6 containing amino group-containing polymer particles 1 and carbon black, RY200, R805, PTFE particles, or hydrophilic silica 200. [Figure 8] This graph shows the amount of CO2 absorbed during the absorption process, measured by the temperature swing absorption method, for amino group-containing polymer particles 1, gas absorbers 3 and 6 containing RY200 or RY200, and comparative gas absorber 1 containing only amino group-containing polymer particles 1. [Figure 9] This graph shows the amount of CO2 emitted during the emission process, measured by the temperature swing absorption method, for amino group-containing polymer particles 1, gas absorbers 3 and 6 containing RY200 or RY200, and comparative gas absorber 1 containing only amino group-containing polymer particles 1. [Figure 10] This graph shows the emission-absorption cycle characteristics measured by the temperature swing absorption method for amino group-containing polymer particles 1, gas absorbers 3 and 6 containing RY200 or RY200, and comparative gas absorber 1 containing only amino group-containing polymer particles 1. [Figure 11] These are SEM images of a pellet (gas absorber 7) made of a mixture of amino group-containing polymer particles 1 and carbon black (gas absorbent material) and polyethylene, as well as a pellet (comparative gas absorber 2) made of a mixture of amino group-containing polymer particles 1 and polyethylene. [Figure 12]This graph shows the amount of CO2 absorbed during the absorption process and the amount of CO2 released during the release process for a pellet (gas absorber 7) made of a mixture of amino group-containing polymer particles 1 and carbon black (gas absorbent material) and polyethylene, as well as for a pellet (comparative gas absorber 2) made of a mixture of amino group-containing polymer particles 1 and polyethylene. [Figure 13] This shows the particle size distribution of a mixture of various amino group-containing polymer pulverized materials and RY300. [Figure 14] This graph shows the amount of CO2 absorbed during the absorption process and the amount of CO2 released during the release process for gas absorbent material 8 containing amino group-containing polymer pulverized at 7mm and RY300, and comparative gas absorbent material 3 containing only amino group-containing polymer pulverized at 7mm. [Figure 15] This graph shows the amount of CO2 absorbed during the absorption process of gas absorbent material 8, which contains an amino group-containing polymer pulverized at 7mm and RY300, and gas absorbent material 9, which is a mixture of an amino group-containing polymer pulverized at 1.5mm and RY300 pulverized in a bead mill. [Figure 16] This figure shows the change in particle size during the granulation process of a mixture of amino group-containing polymer pulverized at 7mm and RY300 while spraying a binder. (a) shows the particle size distribution before granulation, and (b) shows the particle size distribution after granulation. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. The following descriptions of constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits. In this specification, "(meth)acrylamide" means "acrylamide" and "methacrylamide". Also, room temperature means 20°C.

[0012] <Gas absorbent material> The gas-absorbing material of the present invention comprises polymer compound particles having amino groups and fine particles with a primary particle diameter of 1000 nm or less (excluding the "polymer compound particles having amino groups"). In this invention, "containing fine particles with a primary particle diameter of 1000 nm or less (excluding "polymer compound particles having amino groups")" means that, in addition to polymer compound particles having amino groups, the invention also contains fine particles with a primary particle diameter of 1000 nm or less. In the following description, "fine particles with a primary particle diameter of 1000 nm or less (excluding "polymer compound particles having amino groups")" may be simply referred to as "fine particles." This gas-absorbing material exhibits excellent reversible gas absorption performance, with rapid gas absorption and release rates, and large gas absorption and release volumes. This is presumed to be due to the following mechanism. In other words, as shown in the examples below, when a gas-absorbing material containing polymer compound particles having amino groups and fine particles with a primary particle diameter of 1000 nm or less is molded, continuous pores are formed inside, which are not seen in gas-absorbing materials without added fine particles. These continuous pores are thought to function effectively as a gas diffusion phase. Therefore, in this gas-absorbing material, the introduced gas easily penetrates to the interior and reacts efficiently with the amino groups of the polymer compound particles, resulting in sufficient gas absorption in a short time. Furthermore, when gas is released from the polymer compound particles in response to changes in conditions such as temperature changes or gas partial pressure changes, the released gas easily dissipates to the outside through the gas diffusion phase described above. Due to this mechanism, the gas-absorbing material of the present invention is presumed to exhibit a large gas absorption rate and gas dissipation rate, and to show excellent reversible gas absorption performance. In particular, when the fine particles are water-repellent, the continuous pores within them become water-repellent, making it difficult for water to exist within the pores. As a result, the pores function more effectively as a gas diffusion phase, exhibiting superior reversible gas absorption performance. For the meaning of "water-repellent fine particles," please refer to the section below on [Fine particles with a primary particle diameter of 1000 or less]. The following describes the polymer compound particles having amino groups, fine particles with a primary particle diameter of 1000 nm or less, and other materials that may be added as needed, which are included in the gas-absorbing material of the present invention.

[0013] [Polymer compound particles containing amino groups] The "polymer compound particles having amino groups" used in the present invention are particles made of polymer compounds having amino groups, and it is preferable that they consist only of polymer compounds having amino groups, but they may also contain materials used in preparing the particles, such as particle size adjusting components such as surfactants, polymers of (meth)acrylamide derivatives, crosslinking agents, unreacted monomers, etc.

[0014] (Polymer compounds containing amino groups) The amino group in the polymer compound having an amino group may be a primary, secondary, or tertiary amino group, but it is preferable that the acid dissociation constant of the conjugate acid is designed. In particular, in order to dissolve carbon dioxide, it is preferable that the acid dissociation constant of the amino group is equal to or greater than that of carbonic acid. Among these, it is preferable that it be a secondary or tertiary amino group, and more preferably a tertiary amino group. It is even more preferable that it be a dialkylamino group such as a dimethylamino group. Furthermore, the amino group in the polymer compound may be attached to the main chain or to the side chain, but it is preferable that it is attached to the side chain.

[0015] Furthermore, polymer compounds having amino groups preferably also have hydrophobic groups. Examples of hydrophobic groups to be introduced into polymer compounds include C X H 2X Or C X H 2X+1Examples of hydrocarbon groups represented by can be listed, and are preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, isopentyl, hexyl, and cyclohexyl groups. Among these, isobutyl and tert-butyl groups are even more preferred. Alternatively, a hydroxyl group may be bonded to the above hydrophobic group, such as a hydroxyethyl, hydroxypropyl, or hydroxybutyl group.

[0016] The polymer compound having an amino group used for the particles is not particularly limited, but examples include (meth)acrylamide polymers and their derivatives, polyethyleneimine and its derivatives, polyvinylamine and its derivatives, polyvinyl alcohol and its derivatives, polyallylamine and its derivatives, and so on. (meth)acrylamide polymers are preferred, and acrylamide polymers are more preferred. Specific constituent monomers for introducing amino groups include N,N-dimethylaminopropyl methacrylamide, N,N-diethylaminopropyl methacrylamide, N,N-dimethylaminoethyl methacrylamide, N,N-diethylaminoethyl methacrylamide, N,N-dimethylaminopropyl methacrylate, N,N-diethylaminopropyl methacrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminopropyl acrylamide, N,N-diethylaminopropyl acrylamide, N,N-diethylaminoethyl acrylamide, N,N-diethylaminoethyl acrylamide, 3-aminopropyl methacrylamide hydrochloride, 3-aminopropyl acrylamide hydrochloride, N,N-dimethylaminopropyl acrylate, N,N-diethylaminopropyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, 3-aminopropyl methacrylate hydrochloride, and 3-aminopropyl acrylate hydrochloride. The polymer compound having an amino group preferably has a polymer density of 0.3 to 90% in the dispersed state after the polymer compound particles are swollen in water, and more preferably 1 to 80%.

[0017] (Gellability of polymer compound particles containing amino groups) The polymer compound particles having amino groups used in the present invention are preferably gelling polymer particles having amino groups. Here, "gelling polymer particles" means polymer particles that have the property of swelling in water or a polar solvent to become gel-like fine particles. Preferred gelling polymer particles are particles in which the water content inside the particles becomes 20 to 99.7% after being dispersed in water at 30°C and swelling sufficiently. Another preferred gelling polymer particle is a particle in which the hydrodynamic diameter becomes 20 nm to 1000 μm (for example, 20 to 2000 nm) after being dispersed in water at 30°C and swelling sufficiently. Furthermore, it is preferable that the gelling polymer particles have reversibility, meaning that after swelling and gelling in water or a polar solvent, they can return to their original gel state by removing the water or polar solvent, drying, and then adding water or a polar solvent.

[0018] (Particle size of polymer compound particles containing amino groups) The polymer compound particles having amino groups used in the present invention preferably have a median diameter of 5 nm to 500 μm (e.g., 5 nm to 50 μm) in a dry state, and more preferably 1 to 200 μm (e.g., 1 to 20 μm). The median diameter of the polymer compound particles having amino groups in a dry state can be measured using a dry laser diffraction particle size distribution analyzer. The denominator is preferably 20 or more, and more preferably 50 or more. The hydrodynamic particle size of polymer compound particles containing amino groups after swelling in water is preferably 10 nm to 1000 μm (e.g., 10 nm to 100 μm), more preferably 50 nm to 500 μm (e.g., 50 nm to 50 μm), even more preferably 100 nm to 200 μm (e.g., 100 nm to 20 μm), and even more preferably 200 nm to 100 μm (e.g., 200 nm to 10 μm), as measured by dynamic light scattering. The "particle size after swelling in water" of polymer compound particles refers to the particle size after immersing dried polymer compound particles in water at 30°C for 24 hours, and is the average particle size measured by dynamic light scattering. It is believed that when the particle size of the polymer compound particles containing amino groups is within the above range, the diffusion distance of molecules (gas molecules and ions derived from gas molecules) in the gel particles becomes within an appropriate range, and the absorption rate and emission rate of gas tend to improve.

[0019] (Preparation of polymer compound particles containing amino groups) Polymeric compound particles having amino groups can be prepared using a solution containing monomer components (hereinafter referred to as "particle preparation solution"). In this specification, "monomer components" refers to all monomers used in the synthesis of the polymer of the polymeric compound particles having amino groups. The method for preparing polymeric compound particles is not particularly limited, and conventionally known methods such as precipitation polymerization, pseudoprecipitation polymerization, emulsion polymerization, dispersion polymerization, suspension polymerization, seed polymerization, bulk polymerization, and bulk polymerization can be used. The monomer components used in preparing the particles preferably contain at least a monomer having an amino group, and more preferably both a monomer having an amino group and a monomer not having an amino group. That is, the polymer compound having an amino group may be a homopolymer or copolymer of monomers having an amino group, or it may be a copolymer of a monomer having an amino group and a monomer not having an amino group. By controlling the proportion of these monomers, the density of amino groups in the polymer compound particles can be adjusted to an appropriate range. The monomer having an amino group and the monomer not having an amino group, which may be used as needed, are preferably substituted (meth)acrylamide monomers, and more preferably substituted methacrylamide monomers. For a description of the amino groups in monomers containing amino groups and their preferred range, please refer to the section on (polymer compounds containing amino groups). The number of amino groups in a monomer is not particularly limited; it may be one or two or more. If a monomer has two or more amino groups, each amino group may be the same or different. The monomer having an amino group is not particularly limited, but examples include N-(aminoalkyl)acrylamide and N-(aminoalkyl)methacrylamide, with N-(aminoalkyl)methacrylamide being preferred. For specific examples of monomers having an amino group, refer to the description of "Specific constituent monomers" in the (polymer compounds having an amino group) section.

[0020] The monomer component preferably includes a monomer having a hydrophobic group along with a monomer having an amino group. For a description of the hydrophobic group and its preferred range, please refer to the section on (polymer compounds having an amino group). The hydrophobic group is preferably located in the side chain. The monomer having a hydrophobic group may or may not have an amino group. By introducing a monomer having a hydrophobic group, it becomes possible to make the environment around the amino group hydrophobic and appropriately adjust the acidity of the conjugate acid of the amino group. The monomer having a hydrophobic group is not particularly limited, but examples include N-alkylacrylamide, N-alkylmethacrylamide, N-alkyl acrylate, N-alkyl methacrylate, N,N-dialkylacrylamide, N-(hydroxyalkyl)methacrylamide, N,N-dialkyl acrylate, N-(hydroxyalkyl)methacrylate, N,N-dialkylmethacrylamide, N-(hydroxyalkyl)acrylamide, N,N-dialkyl methacrylate, and N-(hydroxyalkyl)acrylate, with N-alkylacrylamide being preferred. A preferred combination of monomers having an amino group and monomers having a hydrophobic group is the combination of N-(aminoalkyl)(meth)acrylamide and N-alkyl(meth)acrylamide, with the combination of N-(aminoalkyl)methacrylamide and N-alkylacrylamide being preferable. In particles consisting of a copolymer of N-(aminoalkyl)(meth)acrylamide and N-alkyl(meth)acrylamide, the hydrophobic alkyl group and the hydrogen-bonding amide are evenly and balanced within the molecule.

[0021] The proportion of monomers containing amino groups in the monomer component is preferably 1 to 95 mol%, more preferably 5 to 95 mol%, and even more preferably 30 to 85 mol%, for example, 30 to 60 mol% based on the total number of moles of the monomer component. Furthermore, if the monomer component includes monomers containing hydrophobic groups, the molar ratio of monomers containing amino groups to monomers containing hydrophobic groups is preferably 95:5 to 5:95, and more preferably 2:1 to 1:2. Monomers that contain both amino groups and hydrophobic groups are classified as monomers containing amino groups. Furthermore, the monomer components may have a composition that does not include monomers without amino groups (a composition in which monomers with amino groups make up 100 mol%), or the amount of monomers without amino groups may be trace (for example, less than 5 mol%). In these cases, the acid dissociation constant of the conjugate acid of the amino group can be appropriately adjusted by increasing the crosslinking density or increasing the monomer concentration during polymerization.

[0022] The particle preparation solution may contain only monomer components or may contain other components. Examples of other components include surfactants, crosslinking agents, polymerization initiators, and pKa adjusters. The particle size of the resulting polymer compound particles can be controlled by adjusting the type and concentration of the surfactant added to the particle preparation solution. Furthermore, by using a crosslinking agent, the swelling properties of the particles can be controlled to prevent excessive swelling by forming crosslinked structures within the polymer compound. Additionally, if a relatively large amount of crosslinking agent is used or the monomer concentration during polymerization is set relatively high, crosslinked structures can also be formed between the particles themselves. This allows for the formation of relatively large continuous void structures between the composite particles linked by the crosslinked structures. The pKa adjuster is used to adjust the pKa of the resulting polymer compound particles to a desired value, thereby significantly changing the absorption amount of acidic gas in the target partial pressure range with changes in temperature and partial pressure. As the surfactant, cationic surfactants such as cetyltrimethylammonium bromide can be used. The crosslinking agent can be any agent capable of forming a crosslinked structure between the monomers used, and N,N'-alkylenebisacrylamide is preferably used. The number of carbon atoms in the alkylene group of N,N'-alkylenebisacrylamide is not particularly limited, but is preferably 1 to 12, more preferably 1 to 4, and even more preferably 1 to 2. Instead of the alkylene group, oligoethyleneimine or oligoethylene glycol may function as the crosslinking agent chain. As pKa adjusting agents, those capable of protonating or deprotonating the amino group of the monomer can be used. Acids such as hydrochloric acid and bases such as sodium hydroxide can be used, with their concentrations adjusted as appropriate according to the desired pKa. Furthermore, since the pKa of polymer compound particles can also be controlled by the crosslinking rate of the crosslinking agent, the above-mentioned crosslinking agent may also be used as a pKa adjusting agent. The solvent for the particle preparation solution is not particularly limited, but examples of polar solvents include water, methanol, ethanol, isopropanol, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide. A mixed solvent may also be a combination of two or more of these polar solvents. In particular, it is preferable to use water or a mixed solvent of water and another polar solvent. Polymer compound particles having amino groups may be used in the production of gas absorbent materials as dry particles (solid particles) or as gel particles swollen with liquid, but it is preferable to use them as dry particles. Dry particles can be obtained, for example, by drying a suspension containing polymer compound particles having amino groups using a spray drying method or the like. Furthermore, pulverized material obtained by pulverizing a gel as an aggregate of gel particles can also be preferably used as polymer compound particles having amino groups. Pulverization of the gel can be carried out, for example, using a meat chopper.

[0023] [Fine particles with a primary particle size of 1000 nm or less] In this invention, fine particles with a primary particle diameter of 1000 nm or less (excluding "polymer compound particles having amino groups") are used in combination with polymer compound particles having amino groups. In the present invention, the "primary particle diameter" of the "fine particles with a primary particle diameter of 1000 nm or less" can be measured by transmission electron microscopy. It is preferable that the "fine particles with a primary particle diameter of 1000 nm or less" used in this invention consist solely of fine particles with a primary particle diameter of 1000 nm or less.

[0024] The particle size of the fine particles used in the present invention is preferably 0.1 nm to 1000 nm in average primary particle diameter, more preferably 0.3 nm to 500 nm, even more preferably 0.5 nm to 300 nm, even more preferably 1 nm to 200 nm, particularly preferably 1.5 nm to 100 nm, particularly more preferably 2 nm to 50 nm, and most preferably 2.5 nm to 25 nm. This ensures that the gas diffusion phase is more reliably formed in the molded body of the gas-absorbing material, and tends to improve the gas absorption rate and emission rate. The fine particles may also be aggregates of primary particles. The aggregates are preferably 100 nm to 200 μm, more preferably 500 nm to 100 μm, and most preferably 2.5 μm to 50 μm. The fine particles may be composed of inorganic materials, organic materials, or a combination of organic and inorganic materials. They may also contain silica or carbon, such as carbon black or fumed silica. Furthermore, the fine particles may be water-repellent or hydrophilic. Water-repellent fine particles are particularly preferable when used in environments where water vapor is likely to condense or form condensation. As described above, when the fine particles are water-repellent, the pores formed by the fine particles function more effectively as a gas diffusion phase. Here, "water-repellent microparticles" refers to microparticles with a primary particle diameter of 1000 nm or less and a water contact angle of 70° or more. The "water contact angle" of microparticles refers to the contact angle with water measured on the surface of a microparticle deposition film formed by these microparticles. The water contact angle of the surface of the microparticle deposition film can be measured by measuring the static contact angle with water. The water contact angle of the water-repellent fine particles is preferably 80° or more, more preferably 100° or more, even more preferably 110° or more, even more preferably 120° or more, particularly preferably 130° or more, and most preferably 140° or more. The following describes water-repellent microparticles and other constituent materials of microparticles that can be used as microparticles in gas-absorbing materials.

[0025] (Water-repellent fine particles) The water-repellent fine particles may be fine particles having water repellency by themselves, or may be those obtained by imparting water repellency to the surface of particles serving as a base material (base material particles). Examples of the fine particles obtained by imparting water repellency to the surface of the base material particles include coated fine particles having a water-repellent film formed on the base surface and surface-modified fine particles subjected to surface modification for imparting water repellency to the base material particles. First, carbon black can be cited as fine particles having water repellency by themselves. Examples of carbon black include acetylene black, furnace black, channel black, thermal black, lamp black, ketjen black, etc., and among them, acetylene black is preferable. Other water-repellent fine particles can also include fine particles composed of Knopel (porous carbon, manufactured by Toyo Tanso Co., Ltd.), titanium oxide, mesoporous silica, etc. Further, as fine particles having water repellency by themselves, fine particles formed of a water-repellent organic material can also be used. Examples of the water-repellent organic material that can be used for forming the particles include fluororesins containing a structural unit represented by -(CA 1 A 2 -CA 3 A 4 )- (where A 1 ~A 4 represents a hydrogen atom, a fluorine atom, a chlorine atom or a perfluoroalkyl group, and A 1 ~A 4(At least one of the atoms is a fluorine atom). Specific examples of fluororesins include polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and other monomers, polychlorotrifluoroethylene (PCTFE), copolymers of chlorotrifluoroethylene and other monomers, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and polytetrafluoropropylene (HEP). Examples of copolymers of tetrafluoroethylene and other monomers include perfluoroalkoxyalkanes (PFA: copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether), perfluoroethylenepropene copolymer (FEP: copolymer of tetrafluoroethylene and hexafluoropropylene), ethylene-tetrafluoroethylene copolymer (ETFE), and tetrafluoroethylene-perfluorodioxole copolymer (TFE / PDD). An example of a copolymer of chlorotrifluoroethylene and other monomers is ethylene-chlorotrifluoroethylene copolymer (ECTFE). These water-repellent organic materials may be used individually or in combination of two or more types.

[0026] The base particles of coated fine particles and surface-modified fine particles may be inorganic or organic particles, but inorganic particles are preferred. Furthermore, if fine particles that are themselves water-repellent are used as the base particles, and a water-repellent coating or surface modification that imparts water repellency is applied to these fine particles, the gas absorption rate and emission rate, as well as the amount of gas absorbed and emitted, can be improved. As inorganic particles, known materials can be used, including carbon black such as acetylene black, furnace black, channel black, thermal black, lamp black, and Ketjen black; particles made of inorganic compounds such as oxides, hydroxides, nitrides, halides, carbonates, sulfates, acetates, and phosphates of metallic or metalloid elements; and natural mineral particles. Examples of inorganic compounds of metallic or metalloid elements include lithium fluoride, calcium carbonate, calcium phosphate, calcium sulfate, calcium fluoride, barium sulfate, titanium dioxide (titania), zirconia dioxide (zirconia), aluminum oxide (alumina), aluminasilicate (alumina silicate, kaolin, kaolinite), and silicon dioxide (silica, silica gel). Examples of natural minerals include talc and clay. Among these, particles made of carbon black and silicon dioxide are preferred. Known organic particles can be used, including particles made of styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based polymers. Fillers may also be used in combination; for example, activated carbon and zeolite can be preferably used as fillers.

[0027] For the water-repellent coating formed on the base particles, in addition to the water-repellent organic materials exemplified as water-repellent materials that can be used to form fine particles, coatings of organopolysiloxanes and organohydrogenpolysiloxanes can be used. Examples of organopolysiloxanes include dialkylpolysiloxanes and alkylphenylpolysiloxanes, and examples of organohydrogenpolysiloxanes include alkylhydrogenpolysiloxanes. The alkyl groups in dialkylpolysiloxanes, alkylphenylpolysiloxanes, and alkylhydrogenpolysiloxanes may be linear, branched, or cyclic, but linear is preferred. The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 6. Here, the two alkyl groups bonded to the silicon atom may be the same or different. Specific examples of organopolysiloxanes include dimethylpolysiloxane and methylphenylpolysiloxane, while specific examples of organohydrogenpolysiloxanes include methylhydrogenpolysiloxane.

[0028] Surface modification methods for substrate particles include introducing water-repellent groups such as alkyl groups and alkyl fluoride groups onto the surface of the substrate particles. The alkyl groups and alkyl fluoride groups introduced into the substrate particles may be linear, branched, or cyclic, but linear is preferred. The number of carbon atoms in the alkyl groups and alkyl fluoride groups is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 10. Furthermore, the alkyl fluoride groups may be partially fluorinated alkyl groups in which some of the hydrogen atoms of the alkyl group are replaced with fluorine atoms, or perfluoroalkyl groups in which all of the hydrogen atoms are replaced with fluorine atoms.

[0029] Surface modification to introduce these water-repellent groups into substrate particles can be carried out using silane coupling agents or silane compounds such as silazanes. Examples of silane coupling agents include compounds represented by the following general formula (1). General formula (1) R 1 n SiX (4-n) (In general formula (1), X represents a hydrolyzable group that generates a silanol group by hydrolysis, and R 1 (where n is an integer between 1 and 3.) The silane coupling agent represented by general formula (1) introduces water-repellent groups to the substrate particles by the reaction of silanol groups and silyl groups generated by the hydrolysis of X with functional groups on the surface of the substrate particles. In the general formula, the "hydrolysis group that generates a silanol group" represented by X can include alkoxy groups such as methoxy groups and ethoxy groups, halogen groups, and the like. R 1 Examples of water-repellent groups in this material include alkyl groups, alkyl fluorides, and dimethylsiloxanes. For a description of alkyl groups and alkyl fluorides and their preferred ranges, please refer to the description of water-repellent groups that can be introduced onto the surface of the substrate particles and their preferred ranges. The water-repellent groups may be directly bonded to Si or bonded via linking groups. n is an integer from 1 to 3, preferably 1 or 2. When n is 2 or greater, multiple R 1 The elements may be identical or different from each other. When n is 2 or less, multiple X elements may be identical or different from each other. Examples of silane coupling agents represented by general formula (1) include triethoxyalkylsilane, diethoxydialkylsilane, ethoxytrialkylsilane, trimethoxyalkylsilane, dimethoxydialkylsilane, methoxytrialkylsilane, and trichloroalkylsilane. Specific examples of silane coupling agents include triethoxycaprylylsilane (triethoxy-n-octylsilane) and octadecyltrichlorosilane. The formation of a water-repellent coating and surface modification treatment on the above-mentioned substrate particles can be carried out according to conventional methods.

[0030] Examples of commercially available water-repellent microparticles include Microdispers-200 (manufactured by Techno Chemical Co., Ltd.), AEROSIL RY200, AEROSIL RY300, AEROSIL R805 (all manufactured by Evonik Co., Ltd.), and Ketjenblack (manufactured by Lion Specialty Chemicals Co., Ltd.). The above-mentioned water-repellent fine particles may be used individually or in combination of two or more types.

[0031] (Other fine particles) The fine particles with a primary particle diameter of 1000 nm or less used in this invention are not limited to water-repellent fine particles, but may also be fine particles other than water-repellent fine particles, i.e., fine particles with a water contact angle of less than 70°. Furthermore, water-repellent fine particles and fine particles with a water contact angle of less than 70° may be used in combination. Fine particles with a water contact angle of less than 70° may have a water contact angle of 50° or less, 30° or less, or 10° or less. The lower limit of the water contact angle of fine particles is 0°. Other fine particles besides water-repellent fine particles include particles made of inorganic compounds of metallic and metalloid elements, as well as organic particles, as described in the (water-repellent fine particles) section above as examples of base particles for coated fine particles and surface-modified fine particles, and silicon dioxide particles are preferred. Furthermore, these inorganic and organic particles may have a coating of organic compounds formed on their surface, or organic functional groups may be introduced into them. A commercially available example of fine particles other than water-repellent fine particles is AEROSIL 200 (manufactured by Evonik).

[0032] (Specific surface area of ​​fine particles) The specific surface area of ​​the fine particles used in this invention is 1 to 3000 m². 2 It is preferably / g, and 2.5 to 2750m 2 It is more preferable that the value be / g, and 5 to 2500m 2 It is even more preferable that the concentration is / g. This ensures that the gas diffusion phase is more reliably formed in the molded body of the gas-absorbing material, and tends to improve the gas absorption rate and emission rate. The specific surface area of ​​fine particles can be measured by the BET method.

[0033] [Particle size ratio and quantity ratio of polymer compound particles containing amino groups and fine particles with a primary particle diameter of 1000 nm or less] The average primary particle diameter of fine particles with a primary particle diameter of 1000 nm or less is preferably smaller than the median diameter of the polymer compound particles having amino groups in a dry state. Specifically, the average primary particle diameter of the fine particles is preferably 1 / 3 to 1 / 100000 of the median diameter of the polymer compound particles having amino groups in a dry state, more preferably 1 / 10 to 1 / 100000, even more preferably 1 / 20 to 1 / 50000, even more preferably 1 / 25 to 1 / 1000, particularly preferably 1 / 50 to 1 / 900, and most preferably 1 / 100 to 1 / 800. To effectively form the gas diffusion phase, it is preferable that the amount of fine particles is sufficient to cover the surface of the polymer fine particles having amino groups. Furthermore, to avoid reducing the amount of gas absorbed per unit weight of the gas absorbent material, the proportion of fine particles should be as small as possible. In other words, it is preferable to add the minimum necessary amount of fine particles to cover the surface as thinly as possible. The larger the particle size of the polymer compound particles having amino groups, the smaller the surface area per unit weight. Therefore, the suitable amount of fine particles to be added varies greatly depending on the particle size of the polymer compound particles having amino groups. If the particle size of the polymer compound particles having amino groups is 10 μm or less, the weight ratio of the polymer compound particles having amino groups to the fine particles (polymer compound particles having amino groups: fine particles) is preferably 95:5 to 5:95, more preferably 90:10 to 30:70, and even more preferably 80:20 to 50:50. Furthermore, it is preferable that the content of polymer compound particles having amino groups in the gas absorbent material is greater than the content of water-repellent particles in terms of solid content. Furthermore, when the polymer compound particles having amino groups are gel particles, adding fine particles to the gel as an aggregate of these gel particles, or to the pulverized gel, reduces the bulk (increases the packing volume) compared to when no fine particles are added, thereby improving the reversible gas absorption performance. Since the particle size of the polymer compound particles having amino groups that effectively achieve this effect is relatively large, for example, 10 μm or more, the required blending ratio of fine particles is relatively small, and the volume ratio of gel or pulverized gel to fine particles (gel or pulverized gel: fine particles) is preferably 99.9:0.1 to 95:5, more preferably 99.75:0.25 to 98:2, and even more preferably 99.5:0.5 to 98.5:1.5. By setting the particle size ratio and quantity ratio of polymer compound particles containing amino groups to fine particles within the above range, the gas absorption rate and emission rate tend to increase.

[0034] [Other ingredients] The gas-absorbing material may consist only of polymer compound particles having amino groups and fine particles with a primary particle diameter of 1000 nm, or it may contain other components. Other components may include polymer compounds other than polymer compound particles having amino groups and additives.

[0035] (Polymer compounds other than polymer compound particles containing amino groups) In this specification, "polymer compounds other than polymer compound particles having amino groups" includes polymer compound particles without amino groups, polymer compounds having amino groups that do not form particles, and polymer compounds without amino groups that do not form particles. While polymer compounds other than polymer compound particles having amino groups are not particularly limited, it is preferable that they are polymer compounds that react to stimuli such as temperature changes. Examples of reactions to stimuli include changes in the acid dissociation constant of the functional group, changes in stereostructure, changes in swelling degree, changes in hydrophilicity, changes in water content, changes in water absorption, changes in bicarbonate ion solubility, and changes in hydrogen sulfide ion solubility. Alternatively, it is preferable that the polymer has an amino group whose conjugate acid acid dissociation constant has been designed. In particular, it is preferable that the acid dissociation constant of the amino group is equal to or greater than that of carbonic acid in order to dissolve carbon dioxide. Among these, it is preferable that the amino group be a secondary or tertiary amino group, and more preferably a tertiary amino group. It is even more preferable that the amino group be a dialkylamino group such as a dimethylamino group. Furthermore, the amino group of the polymer compound may be bonded to the main chain or to the side chain, but it is preferable that it is bonded to the side chain.

[0036] (Additives) Examples of additives include film stabilizers, absorption enhancers, release enhancers, hygroscopic agents, and antioxidants.

[0037] Examples of film stabilizers include polymer compounds, polymerizable molecules (polymerizable compounds), crosslinking agents such as titanium crosslinking agents, primary amines, secondary amines, tertiary amines, etc. Among these, polymer compounds that can be preferably used include polymer compounds having primary amino groups such as polyvinylamine, polymer compounds having secondary amino groups, polymer compounds having tertiary amino groups, compounds having quaternary ammonium groups, polymer compounds having multiple types of primary, secondary, tertiary, and quaternary ammonium groups, polyvinyl alcohol, polyethylene, polyvinyl alcohol / polyethylene copolymers, etc. Furthermore, when polymerizable molecules are used as membrane stabilizers, the polymer compounds produced by the polymerization reaction of these molecules within the membrane also function as membrane stabilizers. This makes it easier to maintain a uniform membrane structure without excessive swelling even after water is added after membrane formation or after gas absorption and release. Examples of polymerizable molecules include monomers having polymerizable groups, such as (meth)acrylic monomers. Among these, (meth)acrylamide or (meth)acrylamide derivatives can be preferably used. Examples include alkylacrylamide, substituted or unsubstituted aminoalkyl(meth)acrylamide, and acrylamide derivatives having two polymerizable groups. Among these, substituted aminoalkylacrylamide and acrylamide derivatives having two polymerizable groups can be preferably used. It is preferable to use substituted aminoalkylacrylamide and acrylamide derivatives having two polymerizable groups in combination, with a mole fraction of 60-99:40-1 being preferred, more preferably 80-99:20-1, and even more preferably 90-99:10-1. Specific examples of monomers having polymerizable groups include N-isopropylacrylamide (NIPAM), tert-butylacrylamide (TBAM), N,N-dimethylaminopropyl methacrylamide (DMAPM), N,N'-methylenebisacrylamide (BIS), and acrylamide. These polymerizable compounds may be used individually or in combination of two or more. When using two or more in combination, a preferred example is the combination of N,N-dimethylaminopropyl methacrylamide (DMAPM) and N,N'-methylenebisacrylamide (BIS). The content of the membrane stabilizer in the gas-absorbing material of the present invention is preferably 1 to 89% by mass relative to the total amount of the gas-absorbing material.

[0038] The absorption accelerator is a compound that has the function of promoting the absorption of acidic gas into the gas-absorbing material of the present invention. The release accelerator is a compound that has the function of promoting the release of acidic gas from the gas-absorbing material. In the present invention, an absorption-release accelerator having both the functions of an absorption accelerator and a release accelerator may be used. These absorption accelerators, release accelerators, and absorption-release accelerators may also have the function of a membrane stabilizer. The total content of the absorption accelerator, release accelerator, and absorption-release accelerator in the gas-absorbing material of the present invention is preferably 0.05 mL or more per gram of solid content, and more preferably 0.1 mL or more. Furthermore, the content of the absorption accelerator in the gas-absorbing material of the present invention is preferably 0.1 to 12 N in terms of amine concentration, more preferably 1 to 10 N, and even more preferably 3 to 9 N. Low molecular weight amines can preferably be used as absorption enhancers, release enhancers, and absorption / release enhancers. The molecular weight of the low molecular weight amine is preferably 61 to 10000, more preferably 75 to 1000, and even more preferably 90 to 500. The boiling point of the low molecular weight amine is preferably 80°C or higher, more preferably 120°C or higher, and even more preferably 150°C or higher, for practical use over long periods. To raise the boiling point, an amine-containing compound that has a site that forms a salt with a counterion like an ionic liquid and is liquid may be used. Low molecular weight amines may contain primary amino groups, secondary amino groups, tertiary amino groups, ammonium groups, or imidazolium groups. Multiple amino groups, ammonium groups, or imidazolium groups may be present, with 1 to 3 being preferred. Secondary and tertiary amino groups may also be cyclic amino groups. Furthermore, low molecular weight amines may contain functional groups other than amino groups, ammonium groups, and imidazolium groups, such as hydroxyl groups. It is preferable that low molecular weight amines contain 0 to 2 hydroxyl groups. Examples of preferred low molecular weight amines include amines having an amino group and a hydroxyl group, or amines having three amino groups. Examples of more preferred low molecular weight amines include amines having a secondary amino group and a hydroxyl group. Amines having a secondary amino group and a hydroxyl group with a boiling point of 150°C or higher are particularly preferred because they can dramatically increase the amount of acidic gas released, especially in the high concentration range, and are suitable for repeated use. Examples of low-molecular-weight amines include specific compounds represented by the following formula.

[0039] [ka]

[0040] Of these, DMAE, IPAE, Bis(2DMAE)ER, 1-2HE-PRLD, 1-2HE-PP, TM-1,4-DAB, TMHAD, and PMDETA are particularly preferred because they can release a large amount of acidic gas. Among these, IPAE, Bis(2DMAE)ER, 1-2HE-PP, TM-1,4-DAB, TMHAD, and PMDETA are more preferred because they have relatively high boiling points and do not evaporate easily. IPAE, TM-1,4-DAB, TMHAD, and PMDETA are even more preferred because their concentration can significantly increase the release of acidic gas. IPAE, TMHAD, and PMDETA are particularly preferred because they are readily available.

[0041] The desiccant used as an additive is preferably one whose relative humidity at 25°C is 90% or less when prepared as a saturated aqueous solution. Examples of such desiccant ions include bromide ions, chloride ions, acetate ions, carbonate ions, bicarbonate ions, lithium ions, potassium ions, calcium ions, magnesium ions, and sodium ions. Salts such as lithium bromide, lithium chloride, calcium chloride, potassium acetate, magnesium chloride, potassium carbonate, and sodium carbonate can also be used as desiccant ions. When adding a desiccant, the amount added is preferably 0.01 to 10% by mass of the total amount of gas absorbent material.

[0042] Antioxidants that can be used as additives are those that can suppress or prevent oxidation when added. Examples of such antioxidants include vitamin C (ascorbic acid), vitamin E (tocopherol), BHT (dibutylhydroxytoluene), BHA (butylhydroxyanisole), sodium erythorbate, propyl gallate, sodium sulfite sulfur dioxide, hydroquinone and its derivatives. When adding antioxidants, the amount added is preferably 0.01 to 10% by mass of the total amount of gas absorbent material. The additives described above may be used individually or in combination of two or more types.

[0043] [Usage of gas absorbent materials] The gas-absorbing material of the present invention may be used by filling it into a container such as a column, or it may be used after being molded into a desired shape by compaction, granulation, kneading, etc. For explanations of compaction, granulation, and kneading, please refer to the corresponding descriptions in <Gas Absorber> below. Furthermore, the gas-absorbing material of the present invention can be used after impregnation with a liquid. This causes the polymer compound particles having amino groups to swell and gel, making them more adept at absorbing acidic gases. The method of liquid impregnation is not particularly limited; impregnation may be carried out by injecting a liquid into the gas-absorbing material packed in a column, or by placing the gas-absorbing material or its molded body in an atmosphere in which the substance to be impregnated has been volatilized. For example, if the substance to be impregnated is water, the gas-absorbing material or its molded body can be impregnated with water by placing it in a high-humidity environment. The liquid impregnated into the gas-absorbing material is not particularly limited, but examples include polar solvents such as water, methanol, ethanol, isopropanol, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide. A mixed solvent combining two or more of these polar solvents may also be used. In particular, it is preferable to use water or a mixed solvent of water and another polar solvent. This causes the polymer compound particles containing amino groups to become hydrogel particles. The water content in the hydrogel particles is preferably 0.05 mL or more per gram of solid content, and more preferably 0.1 mL or more. Furthermore, the water content in the hydrogel particles is preferably 20 mL or less per gram of solid content, and more preferably 10 mL or less. The target gas to be absorbed by the gas-absorbing material of the present invention can be any gas in which the target gas or ions derived from the target gas interact with amino groups, such as acidic gases like carbon dioxide and hydrogen sulfide. In the case of carbon dioxide, bicarbonate ions generated by the reaction with hydroxide ions react with amino groups and are absorbed by polymer compound particles. The switching between the gas absorption and release processes in gas absorbent materials can be achieved by changing the temperature or the partial pressure of the target gas. For example, a gas absorbent material swollen with water is highly basic at 30-50°C and readily absorbs carbon dioxide. After absorbing carbon dioxide at this temperature, heating it to 60-90°C reduces its basicity, causing it to release the absorbed carbon dioxide. Alternatively, after absorbing carbon dioxide at 5-50°C, introducing nitrogen gas, which does not contain carbon dioxide, can also cause the carbon dioxide to be released.

[0044] <Method for manufacturing gas absorbent materials> The gas-absorbing material of the present invention can be manufactured by mixing polymer compound particles having amino groups, fine particles with a primary particle diameter of 1000 nm or less, and other components added as needed. It is preferable to mix these materials by dry mixing, where the materials are mixed in a dry state. This allows for the production of a gas-absorbing material capable of sufficiently forming a gas diffusion phase. Dry mixing can be carried out using, for example, an elliptical rotor type agitator, a fluid granulator, a planetary milling machine, a ball mill, or agitated granulator.

[0045] <Gas absorber> Next, the gas absorber of the present invention will be described. The gas absorber of the present invention comprises a compacted molded body of the gas absorbent material of the present invention. Furthermore, the gas absorber of the present invention comprises granulated particles of the gas absorbent material of the present invention. Moreover, the gas absorber of the present invention comprises a molded body of a mixture containing the gas absorbent material of the present invention and a thermoplastic resin. In the following description, these gas absorbers will be referred to as the first gas absorber, the second gas absorber, and the third gas absorber, in the order listed above. For a description of the gas absorbent material of the present invention in the first to third gas absorbers, please refer to the description in the <Gas Absorbent Material> section. The first to third gas absorbers will be described in order below.

[0046] [First gas absorber] The first gas absorber includes a compacted molded body of the gas absorbent material of the present invention. The compacted powder body of this gas-absorbing material contains high-density polymer compound particles with amino groups, and a pore structure is formed between the polymer compound particles by fine particles with a primary particle diameter of 1000 nm or less. This pore structure effectively functions as a gas diffusion phase. As a result, it exhibits fast gas absorption and emission rates, and superior reversible gas absorption performance. It is preferable to manufacture a compacted gas-absorbing material by a process in which a composite material obtained by dry mixing polymer compound particles having amino groups and fine particles is placed in a mold and pressure-molded. The pressure used for compacting the gas absorber is 0.1 to 2000 kg / cm². 2 Preferably, it is 1 to 1500 kg / cm³. 2 It is more preferable that the temperature is 10-1000 kg / cm². 2 It is even more preferable that this be the case.

[0047] Morphology and properties of compacted gas absorbent materials The compacted powder body constituting the gas-absorbing material preferably has the following form and characteristics.

[0048] (Density of compacted powder) The density of the compacted powder is 0.01 to 10.0 g / cm³. 3 Preferably, the concentration is 0.05 to 7.5 g / cm³. 3 It is more preferable that the concentration be 0.1 to 5.0 g / cm³. 3 It is even more preferable that the following conditions are met. A compacted powder body with a density within the above range is presumed to have pores formed with an appropriate occupancy rate, which can further improve the gas absorption and release rates. The density of a compacted powder can be measured using a dry automatic densimeter.

[0049] (Thickness of the compacted powder body) The length (thickness) of the compacted powder body in the compression direction is preferably 1 μm to 10,000 μm, more preferably 5 μm to 5,000 μm, and even more preferably 10 μm to 1,000 μm. The thickness of the compacted powder body can be measured using a microcaliper, laser microscope, or scanning electron microscope.

[0050] (Shape of the compacted powder product) The shape of the compacted body is not particularly limited and can be appropriately selected depending on the application. For example, film-like or cylindrical shapes are suitable for ease of use. Furthermore, if the compacted body is in the form of a film, it may be a single-layer structure or a multilayer structure consisting of multiple films stacked together. In the case of a multilayer structure, it is preferable that at least the films that are in contact with each other have different conditions such as material, mixing ratio, and thickness. It is also preferable that each film constituting the multilayer structure has a thickness within the appropriate range described above.

[0051] (Nitrogen permeation flow rate of compacted powder) The compacted powder body preferably has a nitrogen permeation flux of 100 GPU or less at 40°C, and more preferably 10 GPU or less. Furthermore, the compacted powder body preferably has a carbon dioxide permeation flux of 10 GPU or more at 40°C, and more preferably 100 GPU or more. Since a compacted powder body with nitrogen and carbon dioxide permeation fluxes within the above ranges can selectively permeate carbon dioxide through nitrogen, when used in a gas separation material (described later), it can selectively separate and efficiently recover carbon dioxide from a mixed gas such as air containing nitrogen and carbon dioxide. In this specification, "permeation flux" is the value obtained by the following equation (1). Q = L / A × ΔP ···(1) In equation (1), Q is the permeation flux, L is the permeation flow rate per unit time, A is the membrane area, and ΔP is the partial pressure difference on both sides of the monolayer membrane. The permeation flow rate L can be measured as the amount of gas that permeates through the membrane per unit time by gas chromatography, etc., and the unit of permeation flux L is GPU (1 GPU = 1.0 × 10⁻⁶). -6 (cm 3 (STP) / (s·cm 2The partial pressure difference ΔP can be determined by measuring the gas partial pressure on the gas supply side and the gas partial pressure on the permeate side using a pressure gauge and gas chromatography, and then calculating the difference between them. Furthermore, in this specification, "selectivity" refers to the permeation flux Q of the selectively permeating gas. S Let Q be the molecule, and the permeation flux Q of other gases O The ratio value Q with as the denominator S / Q O That is the case.

[0052] [Second gas absorber] The second gas absorber contains granulated particles of the gas absorbent material of the present invention. Here, "granulated particles of the gas-absorbing material" means that the gas-absorbing material of the present invention is obtained by forming it into particles using a granulator. The granulation of the gas absorbent material may be done by dry granulation or wet granulation, but dry granulation is preferred. Furthermore, the material to be granulated may be only the gas-absorbing material, or it may be a mixture of the gas-absorbing material and other materials. Examples of other materials include fillers. Known fillers can be used. For example, activated carbon, zeolite, silica, fumed silica, hydrophobic silica, hydrophobic fumed silica, hydrophobic silica, alumina, hydrophobic alumina, hydrophobic alumina, boehmite, diatomaceous earth, oxides such as titanium dioxide, iron oxide, zinc oxide, magnesium oxide, and metal ferrite, hydroxides such as aluminum hydroxide and magnesium hydroxide, carbonates such as calcium carbonate (light and heavy), magnesium carbonate, dolomite, and dawsonite, sulfates such as calcium sulfate, barium sulfate, ammonium sulfate, and calcium sulfite, or sulfites. Examples of suitable materials include sulfates, talc, mica, clay, glass fibers, silicates such as calcium silicate, montmorillonite, and bentonite, borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate, carbon black, hydrophobic carbon black, water-repellent carbon black, graphite, carbon fibers, and other materials such as iron powder, copper powder, aluminum powder, zinc oxide, molybdenum sulfide, boron fibers, potassium titanate, lead zirconate titanate, fluorinated resin powder, and Teflon powder. Among these, the use of water-repellent fillers is preferred. Other materials that can be used include water-repellent materials such as carbon black, silica particles, mesoporous silica, PTFE (polytetrafluoroethylene) particles, metal and inorganic oxide particles, zeolites, activated carbon, low molecular weight amine compounds, and amine-containing polymers. The use of low molecular weight amines and amine-containing polymers is particularly preferred as it improves performance. Furthermore, the granulated particles of the gas-absorbing material may contain a binder. Preferably, the binder is sprayed onto the gas-absorbing material during granulation. This reduces the scattering of the gas-absorbing material and improves its handling. In addition to binders commonly used for granulation, a solution of a polymer having amino groups can be used as the binder. As granulators, stirring and mixing granulators, extrusion granulators, pan-type granulators, etc., can be used. The average primary particle size of the granulated particles of the gas-absorbing material is preferably 0.1 μm to 10 mm, more preferably 0.25 μm to 7.5 mm, and even more preferably 0.5 μm to 5.0 mm. The average primary particle size of granulated particles can be measured using a laser diffraction particle size distribution analyzer or an optical microscope.

[0053] [Third gas absorber] The third gas absorber consists of a molded body of a mixture containing the gas absorbent material of the present invention and a thermoplastic resin. The thermoplastic resin contained in the mixture is not particularly limited, but examples include polyethylene, polyolefins such as polypropylene, polyamides, polystyrene, polyimides, acrylic resins, thermoplastic polyurethanes, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, and the like. The content of thermoplastic resin in the mixture is preferably 1 vol% to 99 vol%, more preferably 5 vol% to 95 vol%, and even more preferably 10 vol% to 90 vol%. The mixture is obtained by kneading the gas-absorbing material and the thermoplastic resin in a kneader. At this time, the gas-absorbing material may be kneaded as is, or it may be kneaded as granulated particles. For an explanation of "granulated particles," please refer to the description in the section above under [Second Gas Absorber]. The mixture may contain only the gas-absorbing material and thermoplastic resin of the present invention, or it may contain other materials. Examples of other materials include fillers, and among these, the use of water-repellent fillers is preferred. Examples of other materials include water-repellent materials such as carbon black, silica particles, mesoporous silica, PTFE particles, metal / inorganic oxide particles, zeolites, activated carbon, low molecular weight amine compounds, and amine-containing polymers. In particular, the use of low molecular weight amines or amine-containing polymers is preferred because it improves performance. For mixing the mixture, a twin-screw kneader, a kneader extruder, a single-screw extruder, etc., can be used. For a description of the thickness and shape of the molded body, please refer to the sections above (Thickness of the compacted molded body) and (Shape of the compacted molded body). The molded body may also be in the form of pellets. The average particle size of the pellets is preferably 0.5 to 10 mm, more preferably 1 to 4.5 mm, and even more preferably 1.5 to 3 mm. The average particle size of the pellets is calculated by measuring the maximum diameter of 100 or more individual pellets and dividing by the number of measured pellets.

[0054] [Total pore volume and average pore diameter of the gas absorber] The first and third gas absorbers have a total pore volume of 0.01 to 10 cm³. 3 It is preferable that the value be / g, and 0.01 to 5 cm 3 It is more preferable that the value be / g, and the range is 0.01 to 2.5 cm. 3 It is even more preferable that it be / g. Furthermore, the first gas absorber and the third gas absorber preferably have an average pore diameter of 0.1 to 500 nm, more preferably 0.1 to 300 nm, and even more preferably 0.1 to 150 nm. The total pore volume of the gas absorber can be measured by the BET method, and the average pore diameter can be determined by analysis using the Kelvin equation. By having the total pore volume and average pore diameter of the gas absorber within the above range, gas diffusion occurs efficiently within the gas absorber, enabling efficient gas absorption and release.

[0055] [Other components of the gas absorber] The gas absorber of the present invention may consist solely of a compacted gas absorbent material, or it may have other components. Other components include carriers that support the compacted powder body. Thin plates or porous materials can be used as carriers. As thin plates used as carriers, resin films, metal foils, sheets made of carbon materials, carbon sheets, etc., can be used, and as porous materials, porous materials or fiber aggregates formed from resin, metal, or carbon can be used.

[0056] <Gas separation material> Next, the gas separation material of the present invention will be described. The gas separation material of the present invention is characterized by containing the gas absorbing material of the present invention. The gas absorbing material contained in the gas separation material may constitute the gas absorber of the present invention. For a description of the gas-absorbing material and gas absorber of the present invention, please refer to the descriptions in the sections on <Gas-absorbing material> and <Gas absorber>. Examples of mixed gases to be separated using the gas separation material of the present invention include natural gas, biogas, landfill gas, post-combustion gas, fuel gas, and gas after steam reforming. According to the gas separation material of the present invention, carbon dioxide, for example, can be selectively separated from these mixed gases in a short time, and the concentration of carbon dioxide in the mixed gas can be significantly reduced. Furthermore, the gas separation material of the present invention may not be limited to gas, but may also allow water or water vapor to permeate. This makes it possible to separate water or water vapor from water or water vapor containing gas, or in other words, to remove gas from water or water vapor.

[0057] The conditions for gas separation vary depending on factors such as the gas absorption material used for the gas separation, the composition of the mixed gas being separated, and the gas to be separated from the mixed gas. However, the temperature is preferably 0 to 130°C, more preferably 0 to 95°C, and preferably 10 to 60°C. Furthermore, the moisture content of the gas absorption material during gas separation is preferably 1% to 1000% by mass of the dry film weight.

[0058] <Filters and gas separation equipment> The filter and gas separation device of the present invention are characterized by having the gas separation material of the present invention. For a description of the gas separation material of the present invention, its preferred range, and specific examples, please refer to the contents described in the <Gas Separation Material> section. The filter and gas separation apparatus of the present invention, by using the gas separation material of the present invention, can efficiently separate and recover a specific gas from a mixed gas. [Examples]

[0059] The features of the present invention will be further described below with reference to examples and comparative examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. The water contact angle and average primary particle diameter of each particle were measured by the method described in [Fine particles with a primary particle diameter of 1000 nm or less]. In addition, the specific surface area and total pore volume shown in Table 2 below were measured by the BET method, and the average pore diameter was determined by the Kelvin formula.

[0060] (Synthesis Example 1) Synthesis of amino group-containing polymer particles 1 The amino group-containing polymer particles 1 used in this example were synthesized as follows.

[0061] [ka] One liter of pure water was added to a two-liter three-necked flask and heated to 70°C. Then, 2 mM of a surfactant (cetyltrimethylammonium bromide) and three monomers were dissolved in the mixture to a total monomer concentration of 312 mM. The three monomers were composed of 55 mol% N-(dimethylaminopropyl)methacrylamide, 43 mol% N-tert-butylacrylamide, and 2 mol% N,N'-methylenebisacrylamide. The N-(dimethylaminopropyl)methacrylamide was prepared by removing the polymerization inhibitor using an alumina column. The N-tert-butylacrylamide was pre-dissolved in a small amount of methanol to a 0.68 g / mL solution before being added. This mixture was stirred with a mechanical stirrer while maintaining the temperature at 70°C, and oxygen was removed from the system by bubbling with nitrogen for one hour. To the monomer solution obtained in this way, a solution of 700 mg of 2,2'-azobis(2-methylpropionamidine) dihydrochloride dissolved in 5 mL of pure water was added, and the mixture was reacted at 70°C for 3 hours under a nitrogen atmosphere. After the reaction, the precipitate was filtered off, and unreacted monomers and surfactants were removed by dialysis for 3 days using a dialysis membrane (MWCO12-14.000, width: 75 mm, vol / length: 18 mL / mL) [manufactured by Spectrum Laboratories]. Then, counteranions were removed using a strongly basic ion exchange resin. The suspension of gel particles obtained in the above steps was dried using a spray-drying method to obtain polymer compound particles containing amino groups (amino group-containing polymer particles 1). The particle size of amino group-containing polymer particles 1 in the dry state was 4 μm in median diameter, as measured using a laser diffraction particle size distribution analyzer. The water contact angle of the amino group-containing polymer particles was 66.2°.

[0062] (Synthesis Example 2) Synthesis of Amino Group-Containing Polymer Particles 2 Dimethylaminopropylacrylamide (DMAPAAm: 85 mol%) and BIS (15 mol%) were dissolved in Milli-Q water at 60°C to make a total of 30 mL of aqueous solution. Ethanol was then added to prepare a mixture so that the total monomer concentration of the reaction mixture to be reacted in the next step was 2.3 mol / L. This mixture was heated to 70°C, and then nitrogen bubbling was performed with stirring for 30-60 minutes. To this mixture, a solution of AIBN (AIBN concentration in the reaction mixture: 2.58 mM, solvent: mixed solvent of acetone and water) was added to form a reaction mixture, and bulk polymerization was carried out under a nitrogen atmosphere at 70°C for 3 hours to obtain a single gel. This was pulverized in a meat chopper (1.5 inch capacity), washed with water, and the washing solution was removed by filtration to obtain amino group-containing polymer particles 2. The water content of these amino group-containing polymer particles 2 was 73.7% by weight.

[0063] [ka]

[0064] (Fine particles with a primary particle size of 1000 nm or less used in this example) The fine particles used in this embodiment, their composition, water contact angle, and average primary particle diameter are shown in Table 1. [Table 1]

[0065] [1] Evaluation of CO2 reversible absorption performance The reversible CO2 absorption performance in this embodiment was evaluated using the pressure swing absorption method (PSA method) and the temperature swing absorption method (TSA method).

[0066] (Evaluation of reversible CO2 absorption performance using the pressure swing absorption method) The CO2 reversible absorption performance using the pressure swing absorption method was evaluated using the following procedure. First, the sample to be measured, contained in the reactor, was placed in a constant temperature bath at 40°C and over 98% relative humidity to humidify it sufficiently, and then the temperature was adjusted to 30°C. Next, a mixed gas of humidified CO2 and N2 (CO2 concentration: 10.03 vol%) was introduced into the sample at a flow rate of 200 mL / min, and the CO2 concentration (A) of the gas discharged from the sample was measured using a multi-gas analyzer (Horiba VA-3000) (absorption process). Then, the gas introduced into the sample was switched to humidified N2 gas and introduced into the sample at a flow rate of 200 mL / min, and the CO2 concentration (B) of the gas discharged from the sample was measured (desorption process). The reversible CO2 absorption performance of the sample under test was evaluated by using the cumulative difference between the CO2 concentration of the introduced mixed gas and the CO2 concentration (A) measured during the absorption process as the CO2 absorption amount, and the cumulative difference between the CO2 concentration (B) measured during the emission process as the CO2 emission amount. When the measured CO2 absorption amount is shown on a graph, a "-" sign may be added to value A to distinguish it from the CO2 emission amount, and it may be shown on the negative side of the vertical axis.

[0067] (Example 1) Production of gas absorber 1 using amino group-containing polymer particles 1 and carbon black A composite material (gas-absorbing material 1) of amino group-containing polymer particles 1 and carbon black shown in Table 1 was obtained by mixing them at room temperature in a volume ratio of amino group-containing polymer particles 1:carbon black = 7:3 and mixing them for 10 minutes at 300 rpm in a planetary milling apparatus containing 2 mm zirconia beads. Figure 1(a) shows an SEM image (magnification: 3700x) of amino group-containing polymer particles 1 before the addition of carbon black, and Figure 1(b) shows an SEM image (magnification: 3700x) of the composite material (gas-absorbing material 1) obtained by mixing amino group-containing polymer particles 1 and carbon black. From the SEM image of the composite material in Figure 1(b), it can be seen that the surface of amino group-containing polymer particles 1 is covered with small particles (carbon black). Next, this gas absorbent material 1 is placed in a reactor (width x depth x height: 15cm x 8cm x 0.2cm) and heated at room temperature at 5000kg / 120cm².2 By compacting the powder, a film-like gas absorber 1 with a thickness of 300 μm was obtained. Figure 2 shows an SEM image (magnification: 20,000x) of the internal structure of gas absorber 1. Figure 3(a) shows a TEM image (magnification: 50,000x) of a thin section cut from gas absorber 1, and Figure 3(b) shows a TEM image of the characteristic X-rays of nitrogen and carbon obtained by energy-dispersive X-ray spectroscopy (EDX) of the same thin section. From the microscopic images shown in Figures 2 and 3, it was confirmed that a pore-like structure was formed inside the film of gas absorber 1. Furthermore, the specific surface area, total pore volume, and average pore diameter were measured for carbon black, gas absorbent material 1 (gas absorbent material 1 before compaction), and gas absorber 1. The results are shown in Table 2. It was confirmed that the carbon black maintained pores that allowed gas diffusion even after compaction. The volume ratio of gas absorber 1 (amino group-containing polymer particles 1: carbon black: pores) was 0.433:0.429:0.138.

[0068] [Table 2]

[0069] (Examples 2-6) Production of a gas absorber using amino group-containing polymer particles 1, water-repellent carbon black, water-repellent silica RY200, water-repellent silica R805, PTFE particles, or hydrophilic silica 200. Gas absorbers 2 to 6 were manufactured in the same manner as in Example 1, except that the fine particles shown in Table 3 were used instead of carbon black.

[0070] (Comparative Example 1) Preparation of comparative gas absorber 1 consisting of amino group-containing polymer particles 1 A gas absorber (comparative gas absorber 1) was manufactured in the same manner as in Example 1, except that instead of a composite material of amino group-containing polymer particles 1 and carbon black, only amino group-containing polymer particles 1 were compacted into a film.

[0071] [Table 3]

[0072] Figure 4 shows the amount of CO2 absorbed during the absorption process for gas absorbers 1, 2, and comparative gas absorber 1, and Figure 5 shows the amount of CO2 released during the release process. Figure 6 shows the amount of CO2 absorbed during the absorption process for gas absorbers 1, 3-6, and Figure 7 shows the amount of CO2 released during the release process. In the figures, "GP" represents amino group-containing polymer particles 1, "CB" represents carbon black, "water-repellent CB" represents water-repellent carbon black, "RY200" represents water-repellent silica RY200, "R805" represents water-repellent silica R805, "PTFE" represents PTFE particles, and "200" represents hydrophilic silica 200. This notation is the same in Figures 8-10 and 12. The amount of CO2 absorbed or released shown in units of "mL / g-GPs" and "mL / g" indicates the amount of CO2 absorbed or released per gram of amino group-containing polymer particles. As shown in Figures 4-7, gas absorbers 1-6 containing fine particles with a primary particle diameter of 1000 nm or less saturated with CO2 in a shorter time compared to comparative gas absorber 1 which did not contain fine particles, and absorption ceased. Furthermore, as shown in Figures 6 and 7, the absorption and emission rates were fastest for gas absorbers 3, 4, and 6 using fine particles with an average primary particle diameter of 12 nm (hydrophobic silica RY200, R805, and hydrophilic silica 200), gas absorber 1 using fine particles with an average primary particle diameter of 30 nm (carbon black CB), and gas absorber 5 using fine particles with an average primary particle diameter of 200 nm (PTFE particles). It was found that the absorption and emission rates improved as the average primary particle diameter of the fine particles decreased. In addition, as shown in Figure 4, gas absorber 2 using water-repellent carbon black (water-repellent CB) showed a larger CO2 absorption and emission amount than gas absorber 1, which did not use water-repellent carbon black (CB). These results confirm that using polymer compound particles containing amino groups in combination with fine particles with a primary particle size of 1000 nm or less increases the gas absorption and release rates, and that increasing the water repellency of the fine particles improves the reversible gas absorption performance. Furthermore, when polymer compound particles containing amino groups were prepared with median diameters ranging from 2 to 10 μm, and gas absorbers were similarly fabricated using these particles, reversible gas absorption performance equivalent to that of the gas absorbers in each example was obtained.

[0073] (Evaluation of reversible CO2 absorption performance using the temperature swing absorption method) The reversible CO2 absorption performance using the temperature swing absorption method was evaluated using the following procedure. First, the reactor containing the sample to be measured was placed in a water bath adjusted to 30°C, and a mixed gas of CO2 and N2 (CO2 concentration: 10.0 vol%) humidified at 60°C was introduced into the reactor at a flow rate of 100 mL / min to sufficiently humidify the sample (humidification process). Next, the reactor was quickly moved to a water bath adjusted to 75°C, and after dehumidifying the gas emitted from the sample, the CO2 concentration (B) was measured using a multi-gas analyzer (Horiba VA-3000) (release process). After sufficient CO2 had been released from the sample, the reactor was quickly moved to a water bath adjusted to 30°C, and the above-mentioned humidified mixed gas of CO2 and N2 was introduced into the reactor at a flow rate of 100 mL / min, while the gas emitted from the sample was dehumidified, and the CO2 concentration (A) was measured using a multi-gas analyzer (absorption process). In this experiment, the emission process was performed for 300 seconds, and the absorption process for 500 seconds. The cumulative difference between the CO2 concentration of the introduced mixed gas and the CO2 concentration (A) measured during the absorption process was defined as the CO2 absorption amount, and the cumulative difference between the CO2 concentrations (B) measured during the emission process was defined as the CO2 emission amount. The emission-absorption cycle, in which the emission and absorption processes were repeated alternately, was performed to evaluate the cycle performance. When the measured CO2 absorption amount is shown on a graph, a "-" sign may be added to value A to distinguish it from the CO2 emission amount, and it may be shown on the negative side of the vertical axis.

[0074] Figure 8 shows the amount of CO2 absorbed during the absorption process and the amount of CO2 released during the release process, measured by the temperature swing absorption method for gas absorbers 3, 6, and comparative gas absorber 1 manufactured in each of the above examples. Figure 9 shows the amount of CO2 released during the release process. Figure 10 shows the amount of CO2 released and absorbed when the release-absorption cycle was performed five times. As shown in Figures 8-10, gas absorbers 3 and 6 containing fine particles showed greater CO2 absorption and emission than comparative gas absorber 1, which does not contain fine particles. In particular, gas absorber 3 using hydrophobic silica RY200 showed greater CO2 absorption and emission than gas absorber 6 using hydrophilic silica 200, and exhibited a stable emission-absorption cycle. This is thought to be because, in the temperature swing absorption method, which is measured at high humidity, moisture condensing in the pores of the membrane greatly affects gas diffusion. In gas absorber 3, the water repellency of the hydrophobic silica RY200 covering the amino group-containing polymer particles suppressed the blockage of pores by condensed water, allowing it to function effectively as a gas diffusion phase. From this, it was found that gas absorbers containing water-repellent fine particles can be effectively used as films, etc., for separating CO2 in a short time under high humidity.

[0075] [2] Study on pelletizing gas absorbent materials (Example 7) Production of a gas absorber 7 consisting of pellets of a mixture of gas absorbent material and polyethylene. A composite material (gas absorbent material) of amino group-containing polymer particles 1 and carbon black CB was obtained in the same manner as the preparation procedure for gas absorbent material 1 in Example 1. This composite material and polyethylene (LDPE: Asahi Kasei Suntech LD M6520) were mixed in a twin-screw compounding extruder (Xplore Instruments: Tabletop compounding machine MC6) in a weight ratio of composite material:polyethylene = 2:1 to obtain a gas absorbent 7 consisting of pellets with an average particle size of 3 mm.

[0076] (Comparative Example 2) Preparation of comparative gas absorber 2 consisting of pellets of a mixture of amino group-containing polymer particles 1 and polyethylene. Pellet (comparative gas absorber 2) was manufactured in the same manner as in Example 7, except that a compound was used which was prepared by kneading amino group-containing polymer particles 1 and polyethylene (LDPE: Asahi Kasei Suntech LD M6520) in a weight ratio of amino group-containing polymer particles 1: polyethylene = 4:1.

[0077] Figure 11 shows SEM images of gas absorber 7 and comparative gas absorber 2. In Figure 11, the upper row of images are SEM images of gas absorber 7, and from left to right, they are an SEM image of the external appearance of the pellet, an SEM image of the internal structure of the pellet at a magnification of 35x, and an SEM image of the internal structure of the pellet at a magnification of 5000x. In Figure 11, the lower row of images are SEM images of comparative gas absorber 2, and from left to right, they are an SEM image of the external appearance of the pellet, an SEM image of the internal structure of the pellet at a magnification of 35x, and an SEM image of the internal structure of the pellet at a magnification of 5000x. Furthermore, Figure 12 shows the amount of CO2 absorbed during the absorption process and the amount of CO2 released during the release process for gas absorber 7 and comparative gas absorber 2, as measured by the temperature swing absorption method. It was confirmed that the absorption and release rates for the initial 30 minutes or so in both the absorption and release processes were accelerated by the addition of carbon black CB.

[0078] [3] Examination of the amount of gas absorbent material to be filled The gel (aggregate of gel particles) consisting of amino group-containing polymer particles 2 synthesized in Synthesis Example 2 was sequentially pulverized in a meat chopper at 1.5 bu (hole diameter 4.8 mm), 1.3 bu (hole diameter 4.0 mm), 1 bu (hole diameter 3.2 mm), 7 rin (hole diameter 2.4 mm), and 3 rin (hole diameter 1.1 mm) to obtain various amino group-containing polymer pulverized materials (gel pulverized materials) with different pulverization degrees. Water-repellent silica RY300 was added to each pulverized material in the mixing ratios shown in Table 4 to prepare a mixture. This mixture was placed in a 250 mL plastic container, shaken, and then the surface was leveled and the height was measured. The results are shown in the thick box in Table 4. Furthermore, Figure 13 shows the particle size distribution of a mixture in which the proportion of water-repellent silica RY300 was 0.50% by volume. Figure 14 shows the amount of CO2 absorbed during the absorption process and the amount of CO2 released during the release process, measured by the pressure swing absorption method, for a mixture (gas absorbent material 8) in which water-repellent silica RY300 (0.50% by volume) was added to an amino group-containing polymer pulverized at 7 rin (7 rin), and an amino group-containing polymer pulverized at 7 rin (comparative gas absorbent material 3). Here, 10 L of gas absorbent material was used as the measurement target sample, and measurements were performed with a mixed gas of CO2 and N2 and an N2 gas flow rate of 1000 mL / min. In Figures 13 and 14, "3 rin GP" to "1.5 bu GP" represent the amino group-containing polymer pulverized at 3 rin to 1.5 bu, respectively, and "RY300" represents water-repellent silica RY300.

[0079] [Table 4]

[0080] As shown in Table 4, the volume (filling amount) of the mixture changed by varying the content of water-repellent silica RY300, and the volume was smallest (filling amount largest) when the blending ratio was 0.50% by volume. Furthermore, as shown in Figure 14, this composite material with a large filling amount (gas absorbent material 8) showed a significant improvement in the reversible CO2 absorption amount and CO2 absorption / emission rate per unit mass compared to comparative gas absorbent material 3 which does not contain water-repellent silica RY300. This indicates that by adding fine particles, the amount of gas-absorbing material can be increased, thereby improving the reversible CO2 absorption and CO2 absorption / release rate. Furthermore, the amino group-containing polymer pulverized materials used in Examples 9 and 10 below are also amino group-containing polymer pulverized materials prepared using the same procedure as the amino group-containing polymer pulverized materials prepared in this section.

[0081] [4] Investigation of the effects of crushing gas-absorbing materials (Example 9) Production of gas absorbent material 9 consisting of a mixture of amino group-containing polymer pulverized material and water-repellent silica RY300, which has been further pulverized. A mixture was obtained by mixing an amino group-containing polymer pulverized at 1.5 minutes of the meat chopper with water-repellent silica RY300 in a volume ratio of amino group-containing polymer pulverized material:water-repellent silica RY300 = 99.5:0.5. This mixture was then pulverized using 5 mm diameter zirconia beads at 230 rpm in a planetary ball mill (Fritsch: P-5) to obtain a gas-absorbing material 9 consisting of the pulverized material. Measurement of the particle size distribution of the pulverized material confirmed that the majority of the polymer particles had a particle size of less than 100 μm. Furthermore, the moisture content of the pulverized material was 72.45%, and the moisture content of the amino group-containing polymer pulverized material was 73.17% by weight, which was slightly lower than the moisture content of the amino group-containing polymer particles 2 used as material (73.7%).

[0082] Figure 15 shows the amount of CO2 absorbed during the absorption process, measured by the pressure swing absorption method, for gas absorbent material 9 and the gas absorbent material 8 mentioned above. Here, 10 L of gas absorbent material was used as the sample to be measured, and measurements were performed with a mixed gas of CO2 and N2 and an N2 gas flow rate of 3000 mL / min. Figure 15 shows that the CO2 absorption rate of gas absorbent material 9, which was pulverized using a bead mill, is dramatically improved compared to gas absorbent material 8, which was not pulverized using a bead mill. This indicates that the reversible CO2 absorption performance of gas absorbent material can be further enhanced by increasing the degree of pulverization.

[0083] [5] Investigation of the effects of binder spraying and granulation on gas absorbent materials (Example 10) Production of a gas absorber 10 consisting of granulated particles obtained by granulating a mixture of an amino group-containing polymer pulverized material and water-repellent silica RY300 using a binder. The amino group-containing polymer pulverized using a meat chopper at a 7mm setting, and water-repellent silica RY300 were placed in a pan-type granulator (AS ONE Corporation: DPZ-01R) in a volume ratio of amino group-containing polymer pulverized material:water-repellent silica RY300 = 99.8:0.2 (total amount 1 kg) and mixed. Granulation was carried out by heating and stirring while spraying a nanoparticle aqueous solution (400 mL) prepared by dissolving amino group-containing polymer particles 1 in water at a ratio of 20 g / mL onto the mixture in the granulator, thereby obtaining a gas absorber 10 consisting of granulated particles. Figure 16(a) shows the particle size distribution of the mixture before granulation, and Figure 16(b) shows the particle size distribution of the granulated particles (gas-absorbing material 11). A comparison of Figures 16(a) and (b) shows that granulation increases the particle size, reducing the dispersion of the gas-absorbing material. [Industrial applicability]

[0084] The gas-absorbing material of the present invention can rapidly absorb and release acidic gases such as carbon dioxide, exhibiting excellent reversible gas absorption performance. Therefore, by using the gas-absorbing material of the present invention, the time efficiency of the gas separation and recovery process can be improved and costs can be reduced. For this reason, the present invention has high industrial applicability.

Claims

1. The material comprises polymer compound particles having amino groups, and fine particles other than the polymer compound particles having amino groups, with a primary particle diameter of 1000 nm or less. The average primary particle diameter of the fine particles is smaller than the median diameter of the polymer compound particles having the amino group in a dry state. The aforementioned polymer compound particles having an amino group include a polymer of a monomer component comprising at least one monomer selected from N-(aminoalkyl)acrylamide, N-(aminoalkyl)methacrylamide, aminoalkyl acrylate, and aminoalkyl methacrylate. A gas-absorbing material wherein the fine particles are particles containing silica or carbon.

2. The gas absorbing material according to claim 1, wherein the water contact angle of the fine particles is 70° or more.

3. The gas absorbing material according to claim 1 or 2, wherein the fine particles are fine particles containing carbon black.

4. The gas absorbing material according to any one of claims 1 to 3, wherein the specific surface area of ​​the fine particles is 1 to 3000 m² / g.

5. The gas absorbing material according to any one of claims 1 to 4, wherein the average primary particle diameter of the fine particles is 0.1 nm to 1000 nm.

6. The gas absorbing material according to any one of claims 1 to 5, wherein the polymer compound particles having amino groups comprise a polymer of a monomer component containing N-(aminoalkyl)acrylamide or N-(aminoalkyl)methacrylamide.

7. The gas absorbing material according to any one of claims 1 to 6, wherein the polymer compound particles having amino groups have a structure in which a crosslinked structure is formed on the polymer compound.

8. A gas absorber comprising granulated particles of the gas absorbent material according to any one of claims 1 to 7.

9. A gas absorber comprising a molded body of a mixture containing the gas absorbent material and a thermoplastic resin according to any one of claims 1 to 7.

10. The gas absorber according to claim 9, wherein the gas absorbent material includes granulated particles of the gas absorbent material.

11. A gas absorber comprising a compacted molded body of the gas absorbent material according to any one of claims 1 to 7.

12. The gas absorber according to any one of claims 8 to 11, further comprising a filler.

13. The gas absorber according to claim 12, wherein the filler is activated carbon or zeolite.

14. A gas separation apparatus having a gas absorber according to any one of claims 8 to 13.

15. The process involves dry mixing polymer compound particles having amino groups with fine particles with a primary particle diameter of 1000 nm or less to obtain a composite material, placing the material into a mold, and press-molding it. The average primary particle diameter of the fine particles is smaller than the median diameter of the polymer compound particles having the amino group in a dry state. The aforementioned polymer compound particles having an amino group include a polymer of a monomer component comprising at least one monomer selected from N-(aminoalkyl)acrylamide, N-(aminoalkyl)methacrylamide, aminoalkyl acrylate, and aminoalkyl methacrylate. A method for producing a gas absorber, wherein the fine particles are particles containing silica or carbon.

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