Apparatus for recovering carbon dioxide

Abstract

To provide a method and an apparatus for efficiently recovering carbon dioxide.SOLUTION: Gas to be treated is introduced to a first gas absorption material in order to allow absorption of carbon dioxide. Then, the following is repeated: heat is applied to the first gas absorption material to exhaust carbon dioxide, and the gas to be treated is introduced into a second gas absorption material in order to allow absorption of carbon dioxide; and next, heat is applied to the second gas absorption material to exhaust carbon dioxide, and the gas to be treated is introduced into the first gas absorption material in order to allow absorption of carbon dioxide.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gas absorbing material and a gas absorber capable of reversibly absorbing acidic gases and the like, and to an acidic gas absorption device, an acidic gas recovery device, a water vapor absorption device, a water vapor recovery device, a heat exchanger, and a heat recovery device that use the gas absorber. [Background technology]

[0002] In recent years, global warming caused by carbon dioxide and water vapor emitted from large-scale facilities such as thermal power plants, steel mills, and cement factories, and environmental pollution caused by hydrogen sulfide and other gases, have become major issues. To mitigate climate change and environmental pollution and achieve a low-carbon society, research is underway into carbon dioxide capture and storage (CCS), a method for separating and capturing acidic gases such as carbon dioxide and hydrogen sulfide, as well as water vapor, emitted from these facilities and storing them underground or under the seabed. However, current technology poses significant energy costs for CCS, and significant reductions in energy costs are needed. In particular, because the carbon dioxide capture process accounts for approximately 60% of the energy costs for CCS, improving the efficiency and achieving significant energy savings in the carbon dioxide capture process are essential to reducing energy costs. Additionally, in the energy supply sector, 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 coal gasification combined cycle (IGCC), and hydrogen used in fuel cells. Improving the efficiency and energy conservation of the carbon dioxide separation and recovery process is also important for reducing energy costs in these sectors.

[0003] Chemical absorption, which uses an aqueous amine solution, is a known method for separating carbon dioxide from flue gas. In this method, flue gas is brought into contact with a low-temperature absorbing solution (an aqueous amine solution) in an absorption tower, allowing the carbon dioxide to be selectively absorbed into the absorbing solution. The absorbing solution is then transported to a stripping tower and heated to strip the carbon dioxide. This chemical absorption method is actually used to treat flue gas from large-scale facilities. However, the problem is that the absorbing solution must be heated to over 130°C to strip the carbon dioxide, which requires a large amount of energy. In response to this, Patent Document 1 and Non-Patent Documents 1 and 2 propose the use of a temperature-responsive electrolyte, the basicity of which changes around the phase transition temperature, for separating and recovering carbon dioxide. Patent Document 1 describes an example in which carbon dioxide is absorbed into a temperature-responsive electrolyte at 30°C, and then the temperature-responsive electrolyte is heated to 75°C, thereby releasing the carbon dioxide from the temperature-responsive electrolyte. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 027668 [Non-patent literature]

[0005] [Non-Patent Document 1] J. Am. Chem. Soc., 134, 18177-, (2012). [Non-patent document 2] Angew. Chem, Intl Ed., 53, 2654-, (2014). Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the temperature-responsive electrolytes described in Patent Document 1 and Non-Patent Documents 1 and 2 can absorb carbon dioxide at 30°C and release the absorbed carbon dioxide at 75°C, thereby significantly reducing the heating temperature during carbon dioxide capture compared to conventional chemical absorption methods. However, when the present inventors investigated this temperature-responsive electrolyte, they found that the reversible absorption amount of acid gas per unit volume was small and the rates of acid gas absorption and release were also slow, making it insufficient for use in treating exhaust gases and various fuel gases from large-scale facilities.

[0007] In order to solve the problems of the conventional art, the present inventors have conducted research to provide a gas absorbing material and a gas absorber that can realize a gas absorber that has a large reversible absorption amount of gas per unit volume, can absorb and desorb gas at high speeds, and can reduce the amount of heat required for gas desorption. Furthermore, the present inventors have conducted research to provide an acid gas absorption device and an acid gas recovery device that can efficiently absorb and / or recover acid gases by using the gas absorber, and further to provide a water vapor absorption device, a water vapor recovery device, a heat exchanger, and a heat recovery device. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the present inventors have found that by using polymer compound particles having amino groups as a gas absorption material, it is possible to realize a gas absorber that has a large reversible absorption amount of gas per unit volume, can absorb and release gas at high speeds, and further requires a small amount of heat for gas release. In particular, it has been found that the absorption and desorption performance of the gas absorber can be further improved by having the following configuration. (1) A gel particle film is supported on a support such as a thin plate, film, or fiber made of a metal, carbon material, or polymer compound. (2) Carriers carrying gel particle films are stacked and accumulated. (3) The gel particle membrane is stabilized and fixed by adding a stabilizer. (4) To accelerate the amount and speed of acid gas absorption, an absorption promoter is added to the gel particle membrane.

[0009] Specifically, the present invention has the following configuration. [1] A gas absorbing material comprising polymer compound particles having amino groups. [2] The gas absorbing material according to [1], wherein the polymer compound particles are hydrogel particles. [3] The gas absorbing material according to [2], wherein the polymer compound particles have a water content of 0.1 mL or more per 1 g of solid content. [4] The gas absorbing material according to any one of [1] to [3], for absorbing an acidic gas from a gas containing water vapor and an acidic gas. [5] The gas absorbing material according to any one of [1] to [4], wherein the polymer compound constituting the polymer compound particles is a polymer of a monomer component containing a monomer having an amino group. [6] The gas absorbing material according to [5], wherein the monomer contained in the monomer component is a substituted acrylamide monomer. [7] The gas absorbing material according to [5] or [6], wherein the monomer having an amino group is an N-(aminoalkyl)acrylamide. [8] The gas absorbing material according to any one of [5] to [7], wherein the monomer having an amino group is a monomer having a tertiary amino group. [9] The gas absorbing material according to any one of [5] to [8], wherein the proportion of the monomer having an amino group in the monomer components is 5 to 95 mol %.

[10] The monomer component includes a monomer having an amino group and a monomer having a hydrophobic group, The gas absorbing material according to any one of [5] to [9], wherein the molar ratio of the monomer having an amino group to the monomer having a hydrophobic group is 5:95 to 95:5.

[11] The gas absorbing material according to

[10] , wherein the monomer having an amino group is an N-(aminoalkyl)acrylamide, and the monomer having a hydrophobic group is an N-alkylacrylamide.

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

[11] , wherein the polymer density within the particles in a dispersed state after swelling the polymer compound particles in water is 0.3 to 80%.

[13] The gas absorbing material according to any one of [1] to

[12] , wherein the polymer compound particles have a particle size in a dry state of 5 nm to 10 μm.

[14] The polymer compound particles undergo a phase transition due to a change in temperature, The gas absorbing material according to any one of [1] to

[13] , wherein the polymer compound particles have a phase transition temperature in the range of 10 to 95°C.

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

[14] , wherein a crosslinked structure is formed between at least some of the polymer compound particles.

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

[15] , wherein the polymer compound particles have a hydrodynamic particle size of 10 nm to 50 μm after swelling and dispersing in water.

[17] The gas absorbing material according to any one of [1] to

[16] , for absorbing and releasing gas.

[18] The gas absorbing material according to

[17] , for repeating a cycle of gas absorption and desorption.

[19] The gas absorbing material according to any one of [1] to

[16] , for absorbing carbon dioxide gas.

[0010]

[20] Use of polymer particles containing amino groups for gas absorption.

[21] The use of polymeric compound particles containing amino groups for the absorption of acid gases from gases containing water vapor and acid gases.

[0011]

[22] A gas absorber comprising a gel particle membrane of a polymer compound having an amino group and a carrier supporting the gel particle membrane.

[23] The gas absorber according to

[22] , wherein the gel particle film contains the gas absorbing material according to any one of [1] to

[19] .

[24] The gas absorber according to

[22] or

[23] , wherein the gel particle membrane is a hydrogel particle membrane containing 10 mass % or more of water relative to the total amount of the gel particle membrane.

[25] The carbon dioxide gas emission rate is 0.1 mmol / m 2 The gas absorber according to any one of

[22] to

[24] , wherein the gas absorber has a viscosity of 1 / sec or more.

[26] The carbon dioxide gas absorption rate is 0.05 mmol / m 2 The gas absorbing material according to any one of

[22] to

[25] , wherein the gas absorbing property is not less than 1 / sec.

[27] The gas absorber according to any one of

[22] to

[26] , wherein the support is in the form of a thin plate or a cylinder.

[28] The gas absorber according to any one of

[22] to

[26] , wherein the carrier is a laminate of a plurality of thin plates.

[29] The gas absorber according to

[27] or

[28] , wherein the thin plate is a metal foil.

[30] The gas absorber according to

[27] or

[28] , wherein the thin plate is made of a carbon material.

[31] The gas absorber according to

[27] or

[28] , wherein the thin plate is a resin film.

[32] The gas absorbent according to any one of

[22] to

[26] , wherein the carrier is a fiber assembly.

[33] The gas absorber according to any one of

[22] to

[26] , wherein the carrier is an assembly of a plurality of laminated fiber assemblies.

[34] The gas absorbent according to

[32] or

[33] , wherein the fiber assembly contains inorganic fibers.

[35] The gas absorber according to

[34] , wherein the inorganic fibers are metal fibers.

[36] The gas absorber according to

[35] , wherein the metal fibers include at least one of stainless steel fibers and aluminum fibers.

[37] The gas absorber according to

[35] , wherein the metal fibers include nickel fibers.

[38] The gas absorber according to any one of

[35] to

[37] , wherein the metal fibers are sintered metal fibers.

[39] The gas absorber according to

[34] , wherein the inorganic fibers are carbon fibers.

[40] The gas absorbent according to any one of

[32] to

[39] , wherein the fiber assembly contains organic fibers.

[41] The gas absorbent according to

[40] , wherein the fiber assembly is paper.

[42] The gas absorbent according to any one of

[22] to

[26] , wherein the support is a porous body.

[43] The gas absorber according to

[42] , wherein the porous body is a metal foam.

[44] The carrier has a specific heat capacity at constant pressure of 2500 KJ / (m 3 K) The gas absorber according to any one of

[22] to

[43] , which is made of the following material:

[45] The gas absorber according to any one of

[22] to

[44] , wherein the carrier is made of a material having a thermal conductivity of 10 W / (mK) or more.

[46] The gas absorber according to any one of

[22] to

[45] , wherein the surface of the support functions as a heat transfer surface of a heat exchanger.

[47] The gas absorber according to any one of

[22] to

[46] , wherein the carrier functions as a heat exchanger.

[48] ​​The gas absorber according to any one of

[22] to

[47] , wherein the gel particle film has a packing ratio of 20% or more.

[49] The gas absorber according to any one of

[22] to

[48] , wherein the gel particle membrane further contains a membrane stabilizer.

[50] The gas absorber according to

[49] , wherein the membrane stabilizer comprises a polymer compound.

[51] The gas absorber according to

[49] , wherein the membrane stabilizer comprises a polymer compound having at least one of a primary amino group, a secondary amino group, and a tertiary amino group.

[52] The gas absorber according to

[51] , wherein the membrane stabilizer comprises polyvinylamine or a derivative of polyvinylamine.

[53] The gas absorber according to any one of

[49] to

[52] , wherein the membrane stabilizer contains a polymerizable compound.

[54] The gas absorber according to any one of

[49] to

[53] , wherein the membrane stabilizer contains a polymer compound produced by a polymerization reaction of a polymerizable compound within the gel particle membrane.

[55] The gas absorber according to

[53] or

[54] , wherein the polymerizable compound is acrylamide or an acrylamide derivative.

[56] The gas absorber according to

[55] , wherein the polymerizable compound comprises a substituted aminoalkylacrylamide and an acrylamide derivative having two polymerizable groups.

[57] The gas absorber according to any one of

[49] to

[56] , wherein the membrane stabilizer contains a crosslinking agent.

[58] The gas absorber according to

[57] , wherein the cross-linking agent is a titanium cross-linking agent.

[59] The gas absorber according to any one of

[49] to

[58] , wherein the content of the membrane stabilizer in the gel particle membrane is 1 to 89 mass % based on the total amount of the gel particle membrane.

[60] The gas absorber according to any one of

[22] to

[59] , wherein the gel particle membrane contains an absorption promoter.

[61] The gas absorber according to any one of

[22] to

[60] , wherein the gel particle membrane contains an amine-containing compound having a molecular weight of 61 to 10,000.

[62] The gas absorber according to

[61] , wherein the gel particle membrane contains at least one of an amine having an amino group and a hydroxyl group and an amine having three amino groups.

[63] The gel particle membrane is composed of isopropylaminoethanol, N,N,N',N'-Tetramethyl-1,6-hexanediamine, imino-bis(N,N-dimethylpropylamine), and N,N ’ ,N ” -pentamethyldiethylenetriamine.

[64] The gas absorber according to any one of

[22] to

[63] , wherein the gel particle membrane surface is supported on a heat transfer surface of a heat exchanger.

[65] The gas absorber according to any one of

[22] to

[64] , wherein the gel particle film is capable of reversibly absorbing at least acidic gases.

[66] The gas absorber according to

[65] , wherein the acidic gas is carbon dioxide.

[67] The gas absorber according to

[65] , wherein the acidic gas is hydrogen sulfide.

[68] The gas absorber according to any one of

[22] to

[67] , wherein the gel particle film is capable of reversibly absorbing at least water vapor.

[0012]

[69] A gas absorption method, characterized by absorbing a gas into a gel particle film of a polymer compound having an amino group.

[70] The gas absorption method according to

[69] , wherein after the gas is absorbed, the temperature of the gel particle film is increased to cause the absorbed gas to dissipate from the gel particle film.

[71] The gas absorption method according to

[70] , wherein the temperature is increased until a volume phase transition of the polymer compound occurs.

[72] The gas absorption method according to

[70] or

[71] , wherein after the gas is released, the temperature of the gel particle film is lowered and the gas is absorbed again into the gel particle film.

[73] The gas absorption method according to any one of

[70] to

[72] , wherein a cycle consisting of the absorption and the desorption is repeated multiple times.

[0013]

[74] An acidic gas absorbing device comprising the gas absorber according to any one of

[22] to

[68] .

[75] An acidic gas recovery device comprising the gas absorber according to any one of

[22] to

[68] .

[76] A water vapor absorption device comprising the gas absorber according to any one of

[22] to

[68] .

[77] A water vapor recovery device comprising the gas absorber according to any one of

[22] to

[68] .

[78] A heat exchanger comprising the gas absorber according to any one of

[22] to

[68] .

[79] A heat recovery device comprising the gas absorber according to any one of

[22] to

[68] . [Effects of the Invention]

[0014] The gas absorbing material of the present invention can realize a gas absorber that has a large reversible absorption amount of gas per unit volume, can absorb and dissipate gas at a high speed, and can reduce the amount of heat required for dissipating gas. Furthermore, the gas absorber of the present invention has a large reversible absorption amount of gas per unit volume, and can absorb and desorb gas at a high speed. In addition, the stability of the gel particle membrane is high, and the initial performance can be reliably maintained even when gas absorption and desorption are repeated. The acidic gas absorption device, acidic gas recovery device, water vapor absorption device, water vapor recovery device, heat exchanger, and heat recovery device of the present invention have such gas absorbers, and can efficiently absorb and recover acidic gases and water vapor gases, thereby making a significant contribution to the realization of a low-carbon society. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram illustrating the mechanism of phase transition of the polymer compound particles having amino groups used in the present invention and the mechanism of absorption and release of carbon dioxide. [Figure 2] 1 is a schematic diagram showing a first embodiment of a carbon dioxide gas recovery device to which an acidic gas recovery device of the present invention is applied. [Figure 3] FIG. 2 is a schematic diagram showing a second embodiment of a carbon dioxide gas recovery apparatus to which the acidic gas recovery apparatus of the present invention is applied. [Figure 4] 1 is a graph showing temperature-dependent particle size changes of amine-containing gel particles of Synthesis Example 2. [Figure 5] 1 is a graph showing the temperature dependence of pH of a particle solution containing amine-containing gel particles of Synthesis Example 2. [Figure 6] 1 shows a titration curve of a particle solution containing amine-containing gel particles of Synthesis Example 2 with hydrochloric acid. [Figure 7] 1 is a graph showing the change over time in the amount of carbon dioxide released from the amine-containing gel particles of Synthesis Example 2. [Figure 8]1 is a graph showing the film thickness dependence of the carbon dioxide diffusion rate of a gel particle film and a homogeneous gel film of amine-containing gel particles (particle size 300 nm) in Synthesis Example 2. [Figure 9] 1 is a graph showing the film thickness dependence of the carbon dioxide diffusion rate of a gel particle film of an amine-containing gel particle (particle diameter 300 nm) of Synthesis Example 2 and a gel particle film of an amine-containing gel particle (particle diameter 1 μm) of Synthesis Example 3. [Figure 10] 1 is a graph showing the film thickness dependence of the carbon dioxide absorption rate of the gel particle membrane of the amine-containing gel particles (particle size 300 nm) of Synthesis Example 2, the gel particle membrane of the amine-containing gel particles (particle size 1 μm) of Synthesis Example 3, the gel homogeneous membrane, and the gel particle membrane of the amine-containing gel particles (crosslinked gel particles) of Synthesis Example 4. [Figure 11] FIG. 1 is a schematic diagram showing a reactor for evaluating the gas absorption and desorption performance of a gas absorber. [Figure 12] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per mass of amine-containing dry gel particles for a gas absorber that uses a thin stainless steel plate with a thickness of 0.1 mm or 0.3 mm as a carrier and supports a gel particle film made of amine-containing gel particles. [Figure 13] FIG. 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per mass of amine-containing dry gel particles for a gas absorber that uses a 0.1 mm thick stainless steel thin plate, iron thin plate, or graphite sheet as a carrier and supports a gel particle film made of amine-containing gel particles. [Figure 14] FIG. 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per reactor volume when the thickness of the gel of a gas absorber, which uses a 0.1 mm-thick graphite sheet as a carrier and supports a gel particle film made of amine-containing gel particles, is changed. [Figure 15] 1 is a schematic diagram, a perspective view (photograph), and a top view (photograph) showing another reactor for evaluating the gas absorption and desorption performance of a gas absorber. [Figure 16]This is a graph showing the change over time in the amount of carbon dioxide absorbed and released per volume of fiber assembly for various gas absorbers (water addition amounts of 0.4, 0.8, and 1.6 mL, respectively) that use a fiber assembly as a carrier and have amine-containing dry gel particle loadings of 100, 200, and 400 mg. [Figure 17] This is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per mass of amine-containing dry gel particles for various gas absorbers (water addition amounts of 0.4, 0.8, and 1.6 mL, respectively) in which a fiber aggregate is used as a carrier and the amount of amine-containing dry gel particles carried is changed to 100, 200, and 400 mg. [Figure 18] This is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per volume of fiber assembly for various gas absorbers with different water contents of 0.4 mL or 0.8 mL in a gel particle film (200 mg of amine-containing dry gel particles supported on a fiber assembly) consisting of amine-containing gel particles. [Figure 19] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles in various gas absorbers having different water contents of 0.4 mL and 0.8 mL in a gel particle film (200 mg of amine-containing dry gel particles supported) made of amine-containing gel particles supported on a fiber assembly. [Figure 20] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per volume of fiber assembly of gas absorbents in which the fiber diameters of the fiber assembly used as the carrier are 12 μm and 100 μm. [Figure 21] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles of gas absorbers in which the fiber diameters of the fiber aggregate used as the carrier are 12 μm and 100 μm. [Figure 22] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per volume of fiber assembly of gas absorbents in which the fiber diameters of the fiber assembly used as a carrier are 8 μm and 12 μm. [Figure 23]1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles of gas absorbers in which the fiber diameters of the fiber assemblies used as carriers are 8 μm and 12 μm. [Figure 24] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per mass of amine-containing dry gel particles when a gas absorber having a gel particle membrane made of amine-containing gel particles supported on a carrier made of a fiber aggregate is placed inside a reaction vessel, and when a gel particle membrane made of the same amount of amine-containing gel particles is placed directly inside the same reaction vessel. [Figure 25] 10 is a graph showing the relationship between the gel filling rate and the amount of carbon dioxide emitted and absorbed when metal fiber and sintered metal fiber are used. [Figure 26] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles when sintered metal fiber, foam metal, and sintered nickel fiber are used. [Figure 27] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles for a gas absorber carrying a gel particle film made of amine-containing gel particles of Synthesis Example 1. [Figure 28] 1 is a graph showing the change in vapor pressure with temperature change of a gas absorbent supporting a gel particle film made of amine-containing gel particles of Synthesis Example 1. [Figure 29] 1 is a graph showing the change over time in the amount of carbon dioxide emitted per mass of amine-containing dry gel particles of a gas absorber in which a polyvinyl alcohol / polyethylene copolymer is added to a gel particle film made of amine-containing gel particles. [Figure 30] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed per mass of amine-containing dry gel particles in a gas absorber in which a polyvinyl alcohol / polyethylene copolymer is added to a gel particle film made of amine-containing gel particles. [Figure 31] 1 is a photograph showing the change that occurs when a film formed from a solution in which a titanium-based crosslinking agent solution is added to a solution of a stabilizer and amine-containing dry gel particles is heat-treated. [Figure 32]1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles of a gas absorber in which a polyvinyl alcohol / polyethylene copolymer and a titanium crosslinking agent are added to a gel particle film made of amine-containing gel particles. [Figure 33] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles of a gas absorber obtained by adding a polymerizable compound (DMAPM:BIS=95:5) to a methanol solution of amine-containing gel particles and polymerizing the compound. [Figure 34] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles of a gas absorber obtained by adding and polymerizing a polymerizable compound (DMAPM:BIS:NIPAM=55:5:45) to a methanol solution of amine-containing gel particles. [Figure 35] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and emitted per mass of amine-containing dry gel particles of a gas absorber obtained by adding a polymerizable compound (DMAPM:BIS:NIPAM=30:5:65) to a methanol solution of amine-containing gel particles and polymerizing the compound. [Figure 36] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed and released per mass of amine-containing dry gel particles of a gas absorber obtained by adding a polymerizable compound (DMAPM:BIS=95:5) to an aqueous solution of amine-containing gel particles and polymerizing the compound. [Figure 37] 1 is a graph showing the change over time in the amount of carbon dioxide released from a gas absorber in which various amines are added to a gel particle film made of amine-containing gel particles. [Figure 38] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed by a gas absorber in which various amines are added to a gel particle film made of amine-containing gel particles. [Figure 39] 1 is a graph showing the change over time in the amount of carbon dioxide released from a gas absorber in which various amines are added to a gel particle film made of amine-containing gel particles. [Figure 40] 1 is a graph showing the change over time in the amount of carbon dioxide absorbed by a gas absorber in which various amines are added to a gel particle film made of amine-containing gel particles. [Figure 41] This is a graph showing the change over time in the amount of carbon dioxide released from a gas absorber made of a gel particle membrane to which various concentrations of PMDETA aqueous solutions (0M, 1M, 3M, and 10M in terms of amine concentration) or PMDETA containing almost no water have been added to amine-containing dry gel particles. [Figure 42] This is a graph showing the change over time in the amount of carbon dioxide absorbed by a gel membrane gas absorber in which various concentrations of PMDETA aqueous solutions (0M, 1M, 3M, and 10M in terms of amine concentration) or PMDETA containing almost no water have been added to amine-containing dry gel particles. [Figure 43] 1 is a graph showing the amount of carbon dioxide released from a gas absorber that is a gel film in which a 3N aqueous amine solution is added to amine-containing dry gel particles. [Figure 44] 1 is a graph showing the amount of carbon dioxide released from a gas absorber of a gel film in which 3N, 6N, and 8N aqueous amine solutions are added to amine-containing dry gel particles. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, "(meth)acrylamide" means "acrylamide" and "methacrylamide."

[0017] <Gas absorption material> The gas absorbing material of the present invention contains polymer compound particles having amino groups. When subjected to a small temperature change, polymer compound particles having amino groups undergo changes in the swelling degree and internal structure of the particles, or the acid dissociation constant of the amino groups, and these changes cause a change in their gas absorption capacity. This allows the gas absorption material to switch between a gas absorbing state and a gas emitting state. It is believed that switching between these two states is achieved by the following mechanism. In the following description, when a specific gas contained in the gas to be treated is absorbed and emitted, the specific gas may be referred to as the "target gas." First, when a gas is brought into contact with polymer compound particles having amino groups at a specific temperature, anions derived from the gas and the amino groups of the polymer compound particles form a salt, resulting in the polymer compound particles reversibly absorbing the gas. When the polymer compound particles are heated from this state, a slight increase in temperature changes the particle swelling degree, internal structure, or the acid dissociation constant of the amino groups, and these changes make the polymer compound particles more susceptible to gas emission. As a result, the gas is emitted from the polymer compound particles, and amino groups are regenerated in the polymer compound. If the polymer compound particles with regenerated amino groups are then repeatedly cooled and heated to a specific temperature, a cycle of gas absorption and emission is repeated using the same mechanism as described above. Because the polymer compound particles having amino groups have these functions, the gas absorption material of the present invention can be effectively used as a material for a gas absorber that absorbs and releases gas, and can also reduce the amount of heat required to release gas. Furthermore, in the gas absorbing material of the present invention, since the polymer compound having amino groups is in the form of particles, when a deposited film formed by depositing the particles is exposed to a gas to be treated, the gas to be treated is absorbed on the surface of the deposited film, and the absorbed carbon dioxide molecules and bicarbonate ions rapidly diffuse into the film through the voids between the particles. Furthermore, when the absorbed target gas is released, the carbon dioxide molecules and bicarbonate ions rapidly diffuse through the voids between the particles, and the target gas not only releases from the surface of the deposited film, but also generates a gas phase in the voids between the particles, which releases the target gas from the inside of the deposited film. Therefore, a gas absorber formed using this gas absorbing material has a larger reversible absorption amount of gas per unit volume and can absorb and release gas at a high rate compared to a homogeneous gas absorber without voids.

[0018] In the gas absorbing material of the present invention, the gas to be absorbed and desorbed is not particularly limited, but is preferably an acidic gas such as carbon dioxide or hydrogen sulfide, and more preferably carbon dioxide, because it forms a salt with the amino group of the polymer compound particles and is easily absorbed by the particles.The gas absorbing material of the present invention can efficiently perform reversible absorption and desorption of gases through the mechanism described above, so it can be effectively used for separating and recovering acidic gases such as carbon dioxide and hydrogen sulfide, and can be particularly suitably used for separating and recovering carbon dioxide, which is emitted in large amounts. Furthermore, unlike adsorbents, the gas absorbing material of the present invention can absorb a large amount of acidic gas even when a high concentration of water vapor is present in the gas. Therefore, for example, when treating a gas to be treated that contains water vapor and carbon dioxide, it is possible to directly separate and recover carbon dioxide without removing the water vapor in advance, thereby simplifying the process required for treating the gas to be treated. The amino group-containing polymer compound particles used in the gas absorbing material of the present invention will be described in detail below.

[0019] (Chemical structure and preparation of polymer particles containing amino groups) The polymer compound particles having an amino group are particles made of a polymer compound having an amino group, and are preferably composed only of a polymer compound having an amino group, but may also contain materials used in preparing the particles, such as particle size adjusting components such as surfactants, crosslinking agents, unreacted monomers, etc.

[0020] The polymer compound having an amino group is not particularly limited, but examples thereof include (meth)acrylamide polymers and derivatives thereof, polyethyleneimine and derivatives thereof, polyvinyl alcohol and derivatives thereof, polyallylamine and derivatives thereof, and the like. Specific constituent monomers 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-dimethylaminoethyl 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, and an acrylamide polymer is preferred. The amino group of the polymer compound having an amino group may be a primary amino group, a secondary amino group, or a tertiary amino group, but it is preferable that the acid dissociation constant of the conjugate acid thereof changes in response to a stimulus such as a temperature change. In particular, it is preferable that the acid dissociation constant when absorbing carbon dioxide is equal to or greater than the acid dissociation constant of carbon dioxide, and that the acid dissociation constant when emitting carbon dioxide is equal to or smaller than the acid dissociation constant of carbon dioxide. Among these, a tertiary amino group is preferable, and a dialkylamino group such as a dimethylamino group is more preferable, as this can increase the efficiency of emitting acidic gases. Furthermore, the amino group of the polymer compound may be bonded to either the main chain or the side chain, but is preferably bonded to the side chain.

[0021] Furthermore, it is preferable that the polymer compound having an amino group also has a hydrophobic group. This allows the polymer compound particles to undergo a significant change (phase transition) in swelling degree and internal structure in response to temperature changes, allowing them to efficiently absorb and release gases such as carbon dioxide gas in response to temperature changes. The phase transition of polymer compound particles having amino groups and hydrophobic groups will be explained below using the case where carbon dioxide is absorbed and released as a target gas as an example. Figure 1 is a schematic diagram showing the absorption and release cycle of carbon dioxide gas when polymer compound particles having amino groups and hydrophobic groups are hydrogel particles. As shown in the upper left of Figure 1, at low temperatures, these gel particles lack steric hindrance around the amino groups, making them highly basic and apt to absorb acidic gases. When these gel particles are exposed to a gas to be treated, containing carbon dioxide, bicarbonate anions are generated through nucleophilic attack by hydroxy anions on the carbon dioxide. One bicarbonate anion molecule forms a salt with one amino group. This causes the gel particles to absorb carbon dioxide. At the same time, the pH of the water decreases, causing the gel particles to swell. When the gel particles are heated from this state, intramolecular hydrophobic interactions increase, causing the gel particles to shrink (phase transition). As a result, the amino groups are surrounded by low-polarity polymer chains, increasing steric hindrance and making the amino groups more apt to release acidic gases (low basicity). This causes carbon dioxide to be released, and at the same time, the pH of the water increases. When the gel particles are then cooled, the pH of the water increases further, causing the gel particles to swell and return to their original state. As described above, gel particles of a polymer compound having amino groups and hydrophobic groups can switch from an acid gas absorption state to an acid gas release state with a slight temperature difference that causes a phase transition. Therefore, by using a gas absorption material containing such gel particles, the amount of energy required for the acid gas separation and recovery process can be reduced. The hydrophobic group to be introduced into the polymer compound is C X H 2X Or C X H 2X+1 Examples of the hydrocarbon group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a cyclopentyl group, an isopentyl group, a hexyl group, a cyclohexyl group, and the like. Of these, an isobutyl group and a tert-butyl group are more preferred. Alternatively, the hydrocarbon group may be a group in which a hydroxyl group is bonded to the above hydrophobic group, such as a hydroxyethyl group, a hydroxypropyl group, or a hydroxybutyl group.

[0022] The polymer compound having an amino group preferably has a polymer density within the particles in a dispersed state after the polymer compound particles are swollen in water of 0.3 to 80%, more preferably 1 to 60%.

[0023] Amino group-containing polymer compound particles can be prepared using a solution containing monomer components (hereinafter referred to as a "particle preparation solution"). In this specification, "monomer components" refers to all monomers used in the synthesis of the polymers of the amino group-containing polymer compound particles. The method for producing the polymer compound particles is not particularly limited, and conventionally known methods such as emulsion polymerization, dispersion polymerization, suspension polymerization, and seed polymerization can be used.

[0024] The monomer components used to prepare the particles preferably contain at least a monomer having an amino group, and also contain 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 a monomer having an amino group, or may be a copolymer of a monomer having an amino group and a monomer not having an amino group. By controlling the ratio of these monomers, the density of the 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 are used as needed, are preferably substituted (meth)acrylamide monomers, more preferably substituted acrylamide monomers.

[0025] For the description and preferred range of the amino group of the monomer having an amino group, please refer to the description and preferred range of the amino group of the polymer compound having an amino group. The number of amino groups possessed by the monomer is not particularly limited and may be one or two or more. When the monomer has two or more amino groups, the amino groups may be the same or different. The monomer having an amino group is not particularly limited, but examples thereof include N-(aminoalkyl)acrylamides and N-(aminoalkyl)methacrylamides, with N-(aminoalkyl)acrylamides being preferred.

[0026] The monomer component preferably contains a monomer having a hydrophobic group together with a monomer having an amino group. For the description and preferred range of the hydrophobic group of the monomer having a hydrophobic group, reference can be made to the description and preferred range of the hydrophobic group that can be employed in the polymer compound having an amino group. The hydrophobic group is preferably present at a terminal. The monomer having a hydrophobic group may or may not further have an amino group. The monomer having a hydrophobic group is not particularly limited, but examples thereof include N-alkylacrylamide, N-alkylmethacrylamide, N-alkylacrylate, N-alkylmethacrylate, N,N-dialkylacrylamide, N-(hydroxyalkyl)methacrylamide, N,N-dialkylacrylate, N-(hydroxyalkyl)methacrylate, N,N-dialkylmethacrylamide, N-(hydroxyalkyl)acrylamide, N,N-dialkylmethacrylate, and N-(hydroxyalkyl)acrylate, with N-alkylacrylamide being preferred.

[0027] A preferred combination of a monomer having an amino group and a monomer 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 preferred. Particles composed of a copolymer of N-(aminoalkyl)(meth)acrylamide and N-alkyl(meth)acrylamide have a well-balanced and uniform distribution of hydrophobic alkyl groups and hydrogen-bonding amides within the molecule. Therefore, at low temperatures, they form swollen gel particles that are easily soluble in water and efficiently absorb gas contained in the gas to be treated. Furthermore, upon heating after absorbing gas, the gel particles shrink with a slight temperature increase, significantly reducing their gas absorption capacity and allowing efficient gas diffusion. Therefore, the use of particles composed of this copolymer in a gas absorption material enables high-speed gas absorption and diffusion while minimizing the heat required for gas diffusion. Furthermore, gel particles of this copolymer are resistant to precipitation even when heated above their phase transition temperature, maintaining highly stable solution properties.

[0028] The proportion of the amino group-containing monomer in the monomer components is preferably 5 to 95 mol%, more preferably 30 to 70 mol%, and even more preferably 50 to 65 mol%, based on the total moles of the monomer components. Furthermore, when the monomer components contain a monomer having a hydrophobic group, the molar ratio of the amino group-containing monomer to the hydrophobic group-containing monomer is preferably 95:5 to 5:95, more preferably 2:1 to 1:2. Monomers having both an amino group and a hydrophobic group are classified as monomers having an amino group. The acidic gas absorption capacity of a polymeric compound tends to increase with an increase in the number of amino groups. However, if the number of amino groups is too high, the electrical repulsion between the amino groups makes it difficult for the particles to shrink or for the acidic gas to dissipate at high temperatures. By setting the proportion of the amino group-containing monomer and the molar ratio of the amino group-containing monomer to the hydrophobic group within the above ranges, polymeric compound particles can be obtained that easily undergo a phase transition upon heating and efficiently dissipate acidic gases.

[0029] The particle preparation solution may contain only the monomer component, or may contain other components. Examples of other components include surfactants, crosslinking agents, and polymerization initiators. By using a surfactant, the particle size of the resulting polymer compound particles can be controlled by changing its concentration in the particle preparation solution. Furthermore, by using a crosslinking agent, the swelling property of the particles can be controlled to prevent excessive swelling by forming a crosslinked structure in the polymer compound within the particles. Furthermore, when a relatively large amount of crosslinking agent is used or when the monomer concentration during polymerization is set relatively high, crosslinked structures can also be formed between particles. This results in the formation of a relatively large continuous void structure between the composite particles connected by the crosslinked structure, which can promote gas absorption and emission. As the surfactant, a cationic surfactant such as cetyltrimethylammonium bromide can be used. The crosslinking agent may 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.

[0030] The solvent for the particle preparation solution is not particularly limited, but examples thereof include polar solvents such as water, methanol, ethanol, isopropanol, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide, and may also be a mixed solvent of two or more of these polar solvents. Among these, it is preferable to use water or a mixed solvent of water and another polar solvent.

[0031] (Properties of polymer particles containing amino groups) The polymer compound particles having amino groups may be gel particles swollen with a liquid or dry particles (solid particles), but gel particles are preferred. In gel particles, gas dissolves in the liquid contained in the gel particles, so the amino groups inside the gel particles can also contribute to gas absorption. This allows a large reversible absorption amount of gas to be obtained.

[0032] The polymer compound particles preferably have a particle size of 5 nm to 10 μm in their dry state. The hydrodynamic particle size of the polymer compound particles after swelling in water is preferably 10 nm to several tens of μm, more preferably 10 nm to 50 μm, and even more preferably 20 nm to 10 μm, as measured by dynamic light scattering. The "particle size after swelling in water" of the polymer compound particles refers to the particle size of dried polymer compound particles after immersing them in water for 24 hours, and is the average particle size measured by dynamic light scattering. When the particle size of the polymer compound particles when dried and the particle size after swelling are within the above ranges, the reversible gas absorption amount per unit volume, and the gas absorption rate and diffusion rate can be sufficiently increased.

[0033] The liquid contained in the gel particles is not particularly limited, but examples thereof include polar solvents such as water, methanol, ethanol, isopropanol, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide, and may also be mixed solvents combining two or more of these polar solvents. Among these, water or a mixed solvent of water and another polar solvent is preferably used. In other words, the gel particles are preferably hydrogel particles. When the gel particles are hydrogel particles, gas can be efficiently dissolved within the particles, allowing for reversible absorption of a larger volume of gas. The water content of the gel particles is preferably 0.1 mL or more per gram of solid content, more preferably 0.5 mL or more, and even more preferably 1 mL or more. The water content of the gel particles is preferably 20 mL or less, more preferably 10 mL or less, and even more preferably 8 mL or less. By setting the water content of the gel particles within the above range, excessive swelling of the gel particles can be suppressed, and gas can be sufficiently dissolved within the gel particles, resulting in increased gas absorption and emission.

[0034] The amino group-containing polymeric compound particles used in the present invention preferably have a gas absorption capacity that changes in response to stimuli such as temperature changes. Factors that change gas absorption capacity include changes in the acid dissociation constant of the functional group, changes in steric structure, changes in swelling degree, changes in hydrophilicity, changes in water content, changes in the amount of dissolved bicarbonate ions, and changes in the amount of dissolved hydrogen sulfide ions. While the gas absorption capacity of the amino group-containing polymeric compound particles may change due to any factor, it is preferable that the gas absorption capacity change at least due to a change in the acid dissociation constant of the ammonium ion, the conjugate acid of the amino group, in response to a temperature change. In particular, it is preferable that the change in the acid dissociation constant be caused by swelling / shrinkage of the gel in response to a temperature change (volume phase transition), a coil-globule structural transition of the polymer in response to a temperature change, or a change in the hydrophilicity / hydrophobicity of the molecule. This allows the gas absorption capacity of the polymeric compound particles to change significantly with a small temperature change, thereby reducing the amount of energy required for gas absorption and release, according to the mechanism shown in Figure 1.

[0035] The phase transition temperature of the polymer compound particles is preferably 10 to 95°C, more preferably 20 to 90°C, and even more preferably 30 to 80°C. In this specification, "phase transition temperature" refers to the temperature at which the acid dissociation constant of ammonium ions, the conjugate acid of the amino group, becomes equal to or smaller than the acid dissociation constant of carbonic acid, or the temperature at which the particle size of the polymer compound particles in water becomes 30% or more smaller than the particle size at 5°C. This phase transition temperature can be determined by immersing the polymer compound particles in 5°C water and measuring the pH or particle size of the polymer compound particle aqueous solution at regular temperature intervals or continuously while raising the water temperature from 15°C. The particle size of the polymer compound particles can be measured by dynamic light scattering.

[0036] <Gas absorber> The gas absorber of the present invention comprises a gel particle membrane of a polymer compound having amino groups and a carrier for supporting the gel particle membrane. The gel particle membrane used in the present invention is a membrane containing gel particles formed by swelling solid particles of a polymer compound having amino groups with water. The gel particle membrane can be confirmed by adding fluorescently modified gel particles to visualize the gel particle membrane and observing it with a focusing laser microscope. The fluorescent modification of the gel particles can be achieved by introducing 4-Acrylamidofluorescein, for example. The gel particle film may be a particle deposition film in which gel particles are deposited on a carrier to form a layer, or may be a film in which gel particles are embedded between fibers or in pores constituting the carrier to form a layer. For the description and preferred range of the polymer compound having an amino group and its gel particles, please refer to the description and preferred range of the polymer compound having an amino group and its gel particles in the gas absorption material.

[0037] This gel particle film can be formed, for example, by applying a particle solution in which polymer compound particles having amino groups are dissolved in a polar solvent onto a support and drying the solution to form a solid polymer compound particle film, and then adding water to the polymer compound particle film to swell it. In this case, a polymerizable compound and a polymerization initiator may be added to the particle solution, and after application and drying, the polymerizable compound may be polymerized, and then water may be added to swell it. For the polymerizable compound to be added, see the description of stabilizers below. The polymerization initiator may be any one capable of initiating polymerization of the polymerizable compound, and may be a photopolymerization initiator or a thermal polymerization initiator. A photopolymerization initiator is preferred. When a photopolymerization initiator is used, polymerization is initiated by irradiation with active energy rays such as ultraviolet light. By performing such polymerization, a gel particle film that is highly stable and does not swell excessively can be produced. As the polar solvent for the particle solution, any of the polar solvents exemplified above as the solvents to be contained in the gel particles can be used, and among them, water or a mixed solvent of water and another polar solvent is preferably used. The water content in the gel particle film is preferably 10% by mass or more, more preferably 50 to 2000% by mass, based on the total amount of the gel particle film. The thickness of the gel particle film is not particularly limited, but is preferably 1 to 1,000 μm, more preferably 10 to 600 μm, and even more preferably 20 to 400 μm. By setting the thickness of the gel particle film within the above range, a sufficient amount of gas can be reversibly absorbed per unit volume, allowing gas absorption and desorption to occur at a high speed. When gel particles form a layer by penetrating between fibers or into pores that constitute the carrier, the thickness of the gel particle layer on the fiber surface or pore surface corresponds to the thickness of the gel particle film.

[0038] The gel particle membrane has a carbon dioxide gas diffusion rate of 0.1 mmol / m 2 / sec or more, and 0.15 mmol / m 2 / sec or more is more preferable, and 0.2 mmol / m 2 / sec or more. 2 / sec or more, and 0.1 mmol / m 2 / sec or more is more preferable, and 0.2 mmol / m 2 / sec or more is more preferable. In this specification, the "carbon dioxide gas absorption rate of a gel particle membrane" is determined by measuring the amount of carbon dioxide in the outlet gas using gas chromatography or an infrared carbon dioxide concentration meter when humidified nitrogen gas (mixed gas) containing 10% carbon dioxide is passed over the surface of the gel particle membrane at 60°C. The above-mentioned diffusion rate and absorption rate are the results for a gel particle membrane containing 5 mol% DMAPM, and will be even greater when a larger amount of DMAPM is used or when a promoter is added.

[0039] [Components other than polymer compound particles with amino groups] The gel particle film may contain polymer compounds other than the polymer compound having an amino group, or additives. The polymer compound other than the polymer compound having an amino group is not particularly limited, but is preferably a polymer compound that responds to stimuli such as temperature change, etc. Examples of responses to stimuli include changes in the acid dissociation constant of the functional group, changes in the three-dimensional structure, changes in the degree of swelling, changes in hydrophilicity, changes in water content, changes in the amount of dissolved bicarbonate ions, and changes in the amount of dissolved hydrogen sulfide ions.

[0040] Examples of additives include membrane stabilizers, absorption promoters, diffusion promoters, and the like. Examples of the film stabilizer include polymer compounds, polymerizable molecules (polymerizable compounds), crosslinking agents such as titanium crosslinking agents, primary amines, secondary amines, etc. Among these, preferred polymer compounds include polymer compounds having a primary amino group such as polyvinylamine, polymer compounds having a secondary amino group, polymer compounds having a tertiary amino group, polymer compounds having multiple types of primary, secondary, and tertiary amino groups, polyvinyl alcohol, polyethylene, polyvinyl alcohol / polyethylene copolymers, etc. Furthermore, when a polymerizable molecule is used as the membrane stabilizer, the polymer compound produced by the polymerization reaction of this molecule within the gel particle membrane also functions as a membrane stabilizer. This facilitates maintaining a uniform membrane shape without excessive swelling even after the addition of water or gas absorption and release following membrane formation. Examples of polymerizable molecules include monomers having a polymerizable group, such as acrylic monomers. Among these, acrylamide or an acrylamide derivative is preferably used. Examples include alkylacrylamide, substituted or unsubstituted aminoalkylacrylamide, and acrylamide derivatives having two polymerizable groups. Among these, substituted aminoalkylacrylamide and acrylamide derivatives having two polymerizable groups are preferred. Substituted aminoalkylacrylamide and acrylamide derivatives having two polymerizable groups are preferably used in combination, with the molar fraction preferably being 60-99:40-1, more preferably 80-99:20-1, and even more preferably 90-99:10-1. Specific examples of monomers having a polymerizable group include N-isopropylacrylamide (NIPAM), tert-butylacrylamide (TBAM), N,N-dimethylaminopropylmethacrylamide (DMAPM), N,N'-methylenebisacrylamide (BIS), acrylamide, etc. These polymerizable compounds may be used alone or in combination of two or more. When two or more are used in combination, a preferred example is the combination of N,N-dimethylaminopropylmethacrylamide (DMAPM) and N,N'-methylenebisacrylamide (BIS). The content of the film stabilizer in the gel particle film is preferably 1 to 89% by mass based on the total amount of the gel particle film.

[0041] The absorption promoter is a compound that has the function of promoting the absorption of acidic gases into the gel particle membrane. The diffusion promoter is a compound that has the function of promoting the diffusion of acidic gases from polymer compound particles. In the present invention, it is preferable to use an absorption / diffusion promoter that functions as both an absorption promoter and a diffusion promoter. These absorption promoters, diffusion promoters, and absorption / diffusion promoters may also function as membrane stabilizers. The total content of the absorption promoter, diffusion promoter, and absorption / diffusion promoter in the gel particle membrane is preferably 1 to 20 mass% relative to the total amount of the gel particle membrane. The content of the absorption promoter in the gel particle membrane is preferably 0.1 to 12N, more preferably 1 to 10N, and even more preferably 3 to 9N, in terms of amine concentration. Low molecular weight amines can be preferably used as the absorption enhancer, diffusion enhancer, and absorption / diffusion enhancer. The molecular weight of the low molecular weight amine is preferably 61 to 10,000, more preferably 75 to 1,000, 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, because it can be used repeatedly and is practical.

[0042] The low-molecular-weight amine may contain any of a primary amino group, a secondary amino group, and a tertiary amino group. It may contain multiple amino groups, preferably 1 to 3. The secondary amino group or tertiary amino group may be a cyclic amino group. Furthermore, the low-molecular-weight amine may contain a functional group other than an amino group, such as a hydroxyl group. The low-molecular-weight amine preferably contains 0 to 2 hydroxyl groups. Examples of preferred low-molecular-weight amines include amines having an amino group and a hydroxyl group, and 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 boiling point of 150°C or higher and a hydroxyl group are particularly preferred because they can dramatically increase the amount of acidic gas emitted, particularly in high-concentration regions, and are suitable for repeated use. Examples of low molecular weight amines include specific compounds represented by the following formula: The absorption and diffusion accelerator used in Example (9) can also be preferably used.

[0043] [ka]

[0044] Among these, it is preferable to use DMAE, IPAE, Bis(2DMAE)ER, 1-2HE-PRLD, 1-2HE-PP, TM-1,4-DAB, TMHAD, and PMDETA, as these can increase the amount of acidic gas emitted. Among these, it is more preferable to use IPAE, Bis(2DMAE)ER, 1-2HE-PP, TM-1,4-DAB, TMHAD, and PMDETA, as these have relatively high boiling points and are difficult to evaporate. It is even more preferable to use IPAE, TM-1,4-DAB, TMHAD, and PMDETA, as the amount of acidic gas emitted can be significantly increased by increasing their concentration. It is particularly preferable to use IPAE, TMHAD, and PMDETA, as they are easily available. Furthermore, it is most preferable to use IPAE, as it can dramatically increase the amount of acidic gas emitted, especially in high concentration ranges, and can increase the amount of acidic gas emitted even in situations where the amount of water relative to the amine is small. The additives described above may be used alone or in combination of two or more.

[0045] The gel particle film configured as described above reversibly absorbs gas under certain conditions, releases the gas in response to a stimulus such as a temperature change, and then reversibly absorbs the gas again when the certain conditions are restored or when another stimulus is applied. Examples of gases that can be reversibly absorbed by the gel particle film include acidic gases such as carbon dioxide and hydrogen sulfide, and water vapor.

[0046] [Carrier] The gas absorber of the present invention is also characterized in that the gel particle membrane is held by a carrier. Gel membranes have lower fluidity than liquids, making convection difficult. Therefore, in the process of acid gas absorption in gel membranes, the ion diffusion process is the rate-limiting step. Furthermore, ion diffusion from the membrane surface to a depth of several hundred micrometers or more is restricted, which results in a limit to the amount of acid gas that the gel membrane can absorb. In contrast, when a gel particle membrane is supported on an appropriate carrier, the gas to be treated can diffuse into the membrane through the interparticle voids, and the acidic gas can diffuse from the membrane. Furthermore, heat is efficiently transferred to the gel particle membrane via the carrier, allowing the temperature of the entire gel particle membrane to change responsively to changes in external temperature. Furthermore, by stacking carriers, a large number of gel particle membranes with thicknesses of several hundred micrometers or less can be packed into a reactor of a given volume. As a result, the absorption and release rates of acidic gases and water vapor gases are increased, and the acidic gases can diffuse deep into the membrane, resulting in a large gas absorption capacity. Furthermore, being supported on a carrier makes the gel particle membrane less likely to collapse, allowing the shape of the gel particle membrane to be stably maintained. Furthermore, a large amount of gas can be reversibly absorbed in a reactor of a given volume.

[0047] The carrier may be a thin plate or a fiber assembly. In the present invention, the term "thin plate" refers to a flat plate, sheet, or foil having a thickness of 2 mm or less and 5 μm or more. The material of the thin plate has a specific heat capacity of 2500KJ / (m 3 It is also preferable that the thermal conductivity is 10 W / (mK) or less. A thin plate with such thermal properties changes temperature responsively in response to changes in the external temperature, and can efficiently transmit the temperature change to the entire gel particle film. Herein, the term "constant pressure specific heat" refers to a value measured by a calorimeter such as a water calorimeter or a differential scanning calorimeter, and the term "thermal conductivity" refers to a value measured by a laser flash method or a steady heat flow method.

[0048] Examples of thin plates that can be used include thin metal plates (metal foils), sheets made of carbon materials, carbon sheets, and resin films (polymer compound films). Examples of sheets made of carbon materials include graphite sheets, and examples of resin films include polyethylene, polypropylene, PET, and polyimide. Because of their high thermal conductivity, thin aluminum plates, thin iron plates, and graphite sheets are preferred as thin plates. Alternatively, because of their low specific heat, thin aluminum plates, graphite sheets, and resin films are preferred. Examples of thin metal plates include stainless steel plates, thin iron plates, thin aluminum plates, and thin nickel plates. Of these, thin iron plates, thin aluminum plates, and thin nickel plates are preferred because of their relatively high thermal conductivity, and thin nickel plates are more preferred.

[0049] The thin plate may be a plate having a homogeneous internal structure, or may be a porous body or a honeycomb structure. In the case of a porous body or a honeycomb structure, the pores can be filled with a gel particle film, which allows heat from the thin plate to be easily transferred to the gel particle film, thereby improving the responsiveness of the gas absorber to temperature changes. In particular, porous bodies such as foam metal, foam nickel, and porous carbon have high heat conductivity to the gel particle film, and by using them as a carrier, the responsiveness of the gas absorber to temperature changes can be significantly improved. The pore diameter of the porous body such as foam metal is preferably 0.1 to 10 mm, more preferably 0.4 to 4 mm. In addition, the specific surface area is preferably 100 to 10,000 m. 2 / m 3 Preferably, it is 200 to 6000 m 2 / m 3 It is more preferable that the porosity is 1 to 99%. Furthermore, when a carrier made of porous resin or porous carbon is used as the porous carrier, the heat capacity is small, and therefore the thermal efficiency of the absorber can be improved. The porous body used as the carrier preferably has a porosity of 1 to 99%, more preferably 10 to 99%, and even more preferably 20 to 95%. In this specification, the term "porosity of a thin plate" refers to the porosity measured by the apparent volume and mass of the thin plate and the density of the material. The carrier may also be a laminate of a plurality of these thin plates. In the laminate, all the thin plates may be the same, or a plurality of thin plates of different materials or thicknesses may be combined.

[0050] A fiber assembly is a material obtained by processing a large number of fibers into a thin, wide plate. Examples of fiber assemblies include cloth and paper, with porous materials such as filters being preferred. The cloth may be woven, felt, or nonwoven. Sintered metal fiber felt is also a preferred carrier. This material has a densely packed structure of sintered fiber fibers, and can provide high thermal conductivity. For example, sintered stainless steel fiber felt or sintered nickel fiber felt is preferred, with sintered nickel fiber felt being particularly preferred. The fibers used in the fiber assembly have a specific heat capacity of 2500KJ / (m 3 It is preferable that the fiber aggregate has a thermal conductivity of 10 W / (mK) or less, and a thermal conductivity of 10 W / (mK) or more. A fiber assembly with such thermal properties changes temperature responsively in response to changes in the external temperature, and can efficiently transmit the temperature change to the entire gel membrane.

[0051] The fibers used in the fiber assembly may be inorganic fibers, organic fibers, or composite fibers that combine inorganic and organic fibers. Examples of inorganic fibers include stainless steel fibers, aluminum fibers, and metal fibers such as nickel fibers, and carbon fibers. Nickel fibers are preferred because they provide high heat conductivity. Examples of organic fibers that can be used include natural fibers such as cotton and hemp, and synthetic fibers such as rayon and polyester. The diameter of the fibers is not particularly limited, but is preferably 8 to 100 μm, which makes it possible to obtain a gel particle film with excellent gas absorption and diffusion properties. The carrier may also be an assembly in which a plurality of these fiber assemblies are laminated together. In the assembly, the fiber assemblies may all be the same, or a plurality of fiber assemblies with different fiber types, fiber diameters, fiber densities, etc. may be combined. The carrier may also be a laminate in which a thin plate and a fiber assembly are laminated together.

[0052] When a fiber assembly is used as the carrier, the filling rate of the gel particle membrane is preferably 10 to 100%, more preferably 15 to 80%, and even more preferably 20 to 70%. The filling rate of the gel particle membrane here refers to the occupancy rate of the gel particle membrane relative to the total volume of the gas absorbent. This allows the gel particle membrane to efficiently absorb and desorb gas. In particular, when a sintered body is used, it is possible to maintain high gas absorption and desorption capacity of the gel particle membrane even at a high filling rate. For example, it is possible to maintain high gas absorption and desorption capacity even at a filling rate of 60% or more.

[0053] The shape of the carrier is not particularly limited and can be appropriately selected depending on the application. Specific examples of the shape of the carrier include a plate shape and a cylinder shape, and the planar shape of the plate and the cross-sectional shape of the cylinder may be any of polygonal shapes such as square or rectangular, perfect circle, ellipse, etc.

[0054] <Gas absorption method> The gas absorption method of the present invention is a method of absorbing gas into amino groups in a gel particle membrane. For an explanation of the gel particle membrane of a polymer compound having amino groups, please refer to the explanation of the gel particle membrane in the above <Gas absorber>. When the amino groups inside the gel particle membrane come into contact with gas at a specific temperature, the acid derived from the gas reacts with the base derived from the amino groups of each gel particle to form a salt, thereby enabling the gas to be efficiently absorbed. Furthermore, gas can be released from the gel particle membrane by increasing the temperature of the gel particle membrane. Increasing the temperature of the gel particle membrane decreases the basicity inside the gel particle membrane. Also, the pKa of the conjugate acid of the amine inside the gel particle membrane decreases. Furthermore, the hydrophobic interaction between each gel particle increases, causing each gel particle to shrink; that is, a volume phase transition occurs in the gel particle, and steric hindrance around the amino group increases. As a result, gas is released from the gel particle membrane. Subsequently, decreasing the temperature of the gel particle membrane increases the basicity inside the gel particle membrane. Also, the pKa of the conjugate acid of the amine inside the gel particle membrane increases. Furthermore, the particles swell again, and the gel particle membrane returns to its state before the phase transition. The gel particle membrane, which has returned to a more basic state, can absorb gas again. Then, when the temperature is raised, the absorbed gas is released by the same mechanism as described above. The temperature is then repeatedly lowered and raised, and the cycle of gas absorption and release is repeated in synchronization with this. By repeating this gas absorption and release, it is possible to separate and recover specific gases, for example, from large volumes of exhaust gas. For detailed mechanisms of the phase transition of gel particles and gas absorption and desorption, please refer to Figure 1 and the explanation of Figure 1 in the section "Gas Absorbing Material." To achieve gas absorption and desorption using this mechanism, it is important to raise the temperature of the gel particle membrane that has absorbed the gas until its basicity decreases. It is particularly important to raise the temperature until the basicity becomes equal to or lower than the pKa of carbonic acid. If the temperature is not raised sufficiently, the gas absorbed in the gel particle membrane cannot be sufficiently desorbed, resulting in a decrease in the subsequent gas absorption rate, desorption rate, and reversible absorption amount. For example, when the gel particles are gel particles of a (meth)acrylamide polymer, the temperature of the gel particle membrane during gas absorption is preferably 1 to 60°C, and the temperature of the gel particle membrane during gas desorption is preferably 40 to 200°C.

[0055] <Applications of gas absorbers> As described above, the gas absorber of the present invention can rapidly absorb and desorb gases such as carbon dioxide and has a large gas absorption capacity, and therefore can be suitably used as a gas absorber in acidic gas absorption devices, acidic gas recovery devices, water vapor absorption devices, water vapor recovery devices, etc. Furthermore, the gas absorber of the present invention can also be effectively applied to heat exchangers and heat recovery devices, as the carrier can function as the heat transfer surface of a heat exchanger or as the heat exchanger itself. In this case, for example, a gel-like film is provided on the surface of the carrier that functions as the heat transfer surface (the surface of the heat transfer surface).

[0056] Hereinafter, a first embodiment and a second embodiment of a carbon dioxide gas recovery apparatus will be described as an example of an acidic gas recovery apparatus to which the gas absorber of the present invention is applied. Fig. 2 is a schematic diagram showing the carbon dioxide gas recovery apparatus of the first embodiment, and Fig. 3 is a schematic diagram showing the carbon dioxide gas recovery apparatus of the second embodiment.

[0057] As shown in Fig. 2, the carbon dioxide gas recovery device of the first embodiment includes a heat exchanger 21, a desulfurizer 22, a cylindrical gas absorber 23, and first to third pipes 24, 25, and 26 connected to each of these components. One end of the first pipe 24 serves as a gas inlet for introducing exhaust gas (gas to be treated), and the other end is connected to the desulfurizer 22. One end of the second pipe 25 is connected to the desulfurizer 22, and the other end is connected to one side of the gas absorber 23. The third pipe 26 has a circulation path 26a connected to one side and the other of the gas absorber 23, and a branch path 26b branching from the circulation path 26a on the one side of the gas absorber 23, and one end of the branch path 26b serves as a gas outlet for discharging the recovered carbon dioxide gas. The connecting portions of the second pipe 25 and the third pipe 26 on one side of the gas absorber 23 are provided on approximately the same diameter of the circular side, sandwiching the center. The heat exchanger 21 is connected to the middle of the first pipe 24 and the middle of the circulation path 26a. The gas absorber 23 is made of the gas absorber of the present invention. In this embodiment, the gas absorber 23 has a carrier made of a cylindrical honeycomb rotor formed by processing a fiber aggregate into a honeycomb shape, a gel particle film supported on this carrier, and is configured to be continuously rotated around the center of the disk as the rotation axis. When the carbon dioxide gas device is turned off, the gas absorber 23 is at a temperature similar to the ambient temperature.

[0058] To recover carbon dioxide gas from flue gas using this acid gas recovery system, the operation of each component is turned on, and the high-temperature, dust-collected flue gas is introduced into one end of the first pipe 24. The introduced flue gas passes through the first pipe 24 and is introduced into a desulfurizer 22, which has a cooling capacity of approximately 30°C. Here, the desulfurizer and the cooler may be separate devices. As the flue gas passes through the first pipe 24, some of the heat of the flue gas is transferred via the heat exchanger 21 to the circulation path 26a of the third pipe 26, and the gas in the circulation path 26a is heated to approximately 75°C. The flue gas introduced into the desulfurizer 22 is desulfurized in the desulfurizer 22 and then flows into the second pipe 25. The mixed gas that flows into the second pipe 25 has a temperature of approximately 30°C and is introduced into the gas absorber 23 at around this temperature. In the gas absorber 23, since the temperature of the mixed gas is about 30°C, carbon dioxide is efficiently absorbed by the gel particle film in the region where the mixed gas comes into contact, and gases other than carbon dioxide gas are discharged to the outside of the gas absorber 23. Meanwhile, the region of the gas absorber 23 that has absorbed carbon dioxide moves near the connection part of the third pipe 26 due to the rotation of the gas absorber 23 and comes into contact with gas introduced from the circulation path 26a of the third pipe 26. Because the gas introduced from the circulation path 26a is heated to about 75°C by heat exchange with the exhaust gas, the gel particle film in the region of the gas absorber 23 that comes into contact with the gas undergoes a phase transition, causing carbon dioxide gas to be emitted. A portion of the emitted carbon dioxide gas flows into the branch path 26b of the third pipe 26 and is discharged to the outside through the gas outlet of the branch path 26b and recovered. Another portion of the emitted carbon dioxide gas flows into the circulation path 26a of the third pipe 26. The carbon dioxide that has flowed into the circulation path 26a is heated by the heat exchanger 21 midway through the circulation path 25a, and then reintroduced into the gas absorber 23, where the heat is used to heat the gel particle film.

[0059] As described above, in the carbon dioxide gas recovery device of the first embodiment, the heat of the exhaust gas is reused to heat the gas absorber, and switching is performed from a state in which acid gas is absorbed to a state in which it is released. In this embodiment, the heat of the exhaust gas is effectively utilized, so the amount of energy consumed in the carbon dioxide gas separation and recovery process can be significantly reduced. In the first embodiment, if the temperatures of the exhaust gas and the absorber cannot be controlled to temperatures suitable for carbon dioxide absorption and release, temperature control can be improved by adding an external heat exchange mechanism or an additional heating mechanism to the piping and the absorber.

[0060] Next, a second embodiment of the carbon oxide gas recovery device will be described. As shown in FIG. 3 , the acid gas recovery system of the second embodiment includes a first heat exchanger 31, a second heat exchanger 32, a desulfurizer 33, a first tank 34, a second tank 35, and a first pipe 36 and a second pipe 37 connected to these components. One end of the first pipe 36 serves as a gas inlet for introducing exhaust gas (gas to be treated), and the other end is connected to the desulfurizer 33, which has cooling capacity. The desulfurizer and the cooler may be separate devices. The second pipe 37 includes a main path 37a, one end of which is connected to the desulfurizer 33, and a first path 37b and a second path 37c, which branch off from the other end of the main path 37a. One end of the first path 37b is connected to the main path 37a, and the other end is connected to the first tank 34. The second path 37c is connected to the main path 37a, and the other end is connected to the second tank 35. Valves (not shown) for opening and closing the first and second paths 37b, 37c are provided near the other ends of the first and second paths 37b, 37c. The first heat exchanger 31 is connected to a first intermediate portion of the first pipe 36 and the first tank 34, and the second heat exchanger 32 is connected to a second intermediate portion of the first pipe 36 and the second tank 35. In the carbon dioxide gas recovery device of the second embodiment, gel particle membranes 38, 39 are applied to the heat exchange surface of the first heat exchanger 31 in the first tank 34 and the heat exchange surface of the second heat exchanger 32 in the second tank 35, respectively. In this embodiment, the first heat exchanger 31 in the first tank 34 and the second heat exchanger 32 in the second tank 35, and the gel particle membranes 38, 39 loaded in these tanks, constitute the gas absorber of the present invention and function as an absorption tower and a diffusion tower for carbon dioxide gas, respectively. The gel particle membranes 38, 39 in each tank 34, 35 are kept at a temperature similar to the ambient temperature (approximately 30°C) when the carbon dioxide gas recovery device is turned off.

[0061] To recover carbon dioxide gas from flue gas using this carbon dioxide gas recovery device, first, the valve of the first path 37b of the second pipe 37 is opened, the valve of the second path 37c of the second pipe 37 is closed, the first heat exchanger 31 is turned off, and the second heat exchanger 32 is turned on. In this state, the first tank 34 functions as an absorption tower. That is, in this state, when high-temperature post-dust collection flue gas is introduced into one end of the first pipe 36, the introduced flue gas passes through the first pipe 36 and is introduced into the desulfurizer 33. As the flue gas passes through the first pipe 36, part of the heat of the flue gas is transferred to the second tank 35 via the second heat exchanger 32, and the flue gas is cooled. The flue gas introduced into the desulfurizer 33 is subjected to desulfurization treatment in the desulfurizer 33, which has cooling capacity, and after further cooling, flows into the main path 37a of the second pipe 37. The mixed gas that has flowed into the main path 37a has a temperature of about 30°C, and is introduced into the first tank 34 via the main path 37a and the first path 37b at around this temperature. In the first tank 34, since the temperature of the mixed gas is about 30°C, carbon dioxide is efficiently absorbed into the gel particle membrane 38, and gases other than carbon dioxide are discharged to the outside through a gas outlet provided in the first tank 34.

[0062] After the carbon dioxide has been sufficiently absorbed into the gel particle membrane 38, the valve of the first path 37b of the second pipe 37 is closed, the valve of the second path 37c of the second pipe 37 is opened, the first heat exchanger 31 is turned on, and the second exchanger 32 is turned off. This causes the heat of the exhaust gas passing through the first pipe 36 to be transferred to the first tank 34 and the gel particle membrane 38 via the first heat exchanger 31. The gel particle membrane 38 in the first tank 34 is heated to approximately 75°C by the heat from the first heat exchanger 31, and dissipates carbon dioxide gas. The dissipated carbon dioxide gas is discharged and collected from a gas outlet provided in the first tank 34. Meanwhile, the mixed gas at approximately 30°C that has flowed into the second pipe 37 via the same path as above is introduced into the second tank 35 via the second path 37c, and the carbon dioxide is absorbed by the gel particle membrane 39 installed in the tank 35. That is, in this state, the first tank 34 functions as a diffusion tower, and the second tank 35 functions as an absorption tower, and the absorption and diffusion of carbon dioxide gas are carried out in parallel.

[0063] After sufficient carbon dioxide gas has been released from the gel particle membrane 38 and absorbed into the gel particle membrane 39, as shown in FIG. 3, the valve of the first path 37b of the second pipe 37 is opened, the valve of the second path 37c of the second pipe 37 is closed, the first heat exchanger 31 is turned off, and the second heat exchanger 32 is turned on, switching the first tank to function as an absorption tower and the second tank to function as a stripper tower. This allows carbon dioxide gas absorption and stripping to occur in parallel in the towers opposite to those before the switchover. Furthermore, by repeating the above-described switching operation, carbon dioxide gas can be continuously absorbed and stripped from the exhaust gas, allowing carbon dioxide gas to be efficiently separated and recovered from large amounts of exhaust gas.

[0064] As described above, in the carbon dioxide gas recovery device of the second embodiment, the heat of the exhaust gas is reused to cause a phase transition in the gas absorber, switching it from a state in which it absorbs acidic gases to a state in which it releases them. This significantly improves the energy utilization efficiency compared to conventional carbon dioxide gas separation and recovery processes. In the second embodiment, if the temperatures of the exhaust gas and absorber cannot be controlled to temperatures suitable for carbon dioxide absorption and release, temperature control can be improved by adding an external heat exchange mechanism or an additional heating mechanism to the piping and absorber. [Example]

[0065] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0066] [I] Synthesis of amine-containing gel particles Amino group-containing polymer compound particles were synthesized as follows: In the following description, the gel of amino group-containing polymer compound particles is sometimes referred to as "amine-containing gel particles," and the particles obtained by drying the "amine-containing gel particles" are sometimes referred to as "amine-containing dried gel particles."

[0067] (Synthesis Example 1) One liter of purified water was added to a 2-liter three-neck flask and heated to 70°C. 2 mM of surfactant (cetyltrimethylammonium bromide) and the three monomers were dissolved in the flask to a total monomer concentration of 312 mM. The three monomers were 55 mol% N-(dimethylaminopropyl)methacrylamide, 43 mol% N-tert-butylacrylamide, and 2 mol% N,N'-methylenebisacrylamide. N-(dimethylaminopropyl)methacrylamide was used after removing the polymerization inhibitor using an alumina column. N-tert-butylacrylamide was dissolved in a small amount of methanol to a concentration of 0.68 g / mL and then added. The mixture was maintained at 70°C and stirred with a mechanical stirrer. Nitrogen gas was bubbled through the system for 1 hour to remove oxygen from the system. A solution of 700 mg of 2,2'-azobis(2-methylpropionamidine) dihydrochloride dissolved in 5 mL of purified water was added to the resulting monomer solution, and the mixture was allowed to react for 3 hours at 70°C under a nitrogen atmosphere. After the reaction, the precipitate was filtered and dialyzed for 3 days using a dialysis membrane (MWCO 12-14,000, width: 75 mm, volume / length: 18 mL / mL) [Spectrum Laboratories] to remove unreacted monomer and surfactant. Counteranions were removed from the dialyzed precipitate using a strongly basic ion exchange resin, yielding amine-containing gel particles. Similar experiments were performed on materials without dialysis or ion exchange, confirming that they had nearly equivalent functionality. The particle size of the resulting amine-containing gel particles was 800 nm.

[0068] (Synthesis Example 2) Amine-containing gel particles were obtained in the same manner as in Synthesis Example 1, except that N-isopropylacrylamide was used instead of N-tert-butylacrylamide and the composition of the three monomers was changed to 5 mol% N-(dimethylaminopropyl)methacrylamide, 93 mol% N-isopropylacrylamide, and 2 mol% N,N'-methylenebisacrylamide. The hydrodynamic particle diameter of the obtained amine-containing gel particles dispersed in water at 30°C was approximately 200 nm in a nitrogen atmosphere and approximately 400 nm in the presence of 10% CO2.

[0069] (Synthesis Example 3) Apart from changing the surfactant concentration to 0.16 mM, amine-containing gel particles were obtained in the same manner as in Synthesis Example 2. The hydrodynamic particle size of the obtained amine-containing gel particles in a dispersed state in water at 30°C was 600 nm.

[0070] (Synthesis Example 4) A monomer solution was prepared as in Synthesis Example 2, except that the composition of the three monomers was changed to 5 mol% N-[(3-dimethylamino)propyl]methacrylamide, 93 mol% N-isopropylacrylamide, and 2 mol% N,N'-methylenebisacrylamide, resulting in a total monomer concentration of 1040 mM. After passing nitrogen gas through 2.4 mL of this solution for 10 minutes, an aqueous solution of the initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride was mixed and introduced into the bottom of a stainless steel reactor for carbon dioxide absorption. A silicone rubber spacer (100 μm thick) serving as a mold was placed in the reactor, and a glass plate was placed on top of the spacer, sandwiching the monomer solution between them, so that the monomer solution formed a 100 μm-thick liquid film. The mixture was heated to 70°C and polymerized for 2 hours. After 2 hours, the glass plate and spacer were removed, revealing a hydrogel film with crosslinked amine-containing gel particles adhered to the bottom of the stainless steel reactor. After drying, the primary diameter of the gel particles in the obtained hydrogel film was observed using a scanning electron microscope. It was confirmed that the primary particle diameter of the particles was several tens to several micrometers and that cross-linked structures had formed between the particles.

[0071] [II] Synthesis of stabilizers A polymer compound having an amino group, which serves as a stabilizer, was synthesized as follows.

[0072] (Synthesis Example 5) Synthesis of polyvinylamine 5.0 g of purified N-vinylformamide (NVF) was added to 44 mL of purified water and stirred in a 60 °C oil bath while bubbling nitrogen for 30 minutes. 1.0 mL of an aqueous solution (19 mg / mL) of the initiator 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044) [Wako Pure Chemical Industries, Ltd.] was then added and reacted for 24 hours under a nitrogen atmosphere. Acetone was added to the reaction solution to precipitate the polymer, and the supernatant was removed. The resulting precipitate was dissolved in a 3:1 volume mixture of purified water and ethanol. The polymer precipitation with acetone, removal of the supernatant, and dissolution in an aqueous solvent were repeated several times to remove unreacted monomer. The resulting precipitate solution was concentrated under reduced pressure using an evaporator and then vacuum-dried to obtain solid poly(NVF). The dried solid was dissolved in a 2N aqueous solution of sodium hydroxide to a polymer concentration of 2% by mass, and the solution was stirred in an oil bath at 80°C for 24 hours to obtain a transparent, viscous liquid. Hydrochloric acid was added to this liquid to form the hydrochloride salt, and excess hydrochloric acid was removed using an evaporator. The liquid was dialyzed for three days using a dialysis membrane (MWCO 12-14,000, width: 75 mm, volume / length: 18 mL / mL) [manufactured by Spectrum Laboratories], and the amount of solution in the membrane was measured. The entire solution was then freeze-dried to obtain poly(vinylamine) hydrochloride (PVAm·HCl). The progress of the reaction at each stage was 1 The reaction was confirmed by HNMR (DO). The counter anions were removed from this PVAm·HCl using a strongly basic ion exchange resin to obtain polyvinylamine.

[0073] (Synthesis Example 6) Synthesis of hydrophobic polyvinylamine To impart temperature responsiveness to the PVAm·HCl synthesized in Synthesis Example 5, a carboxylic acid with a bulky hydrophobic moiety was condensed. Two types of carboxylic acids were used: isobutyric acid (Sigma-Aldrich) and pivalic acid (Wako Pure Chemical Industries), each with an isopropyl or tert-butyl group. The product condensed with isobutyric acid is referred to as Isobutyl PVAm, and the product condensed with pivalic acid is referred to as PivalPVAm. Specifically, the hydrophobic polyvinylamine was obtained by the following process. 100 mg of PVAm·HCl (1.25 mmol amine) was dissolved in 20 mL of MilliQ water. Triethylamine (TEA) and isobutyric acid or pivalic acid were added to this solution. Since pivalic acid is solid at room temperature, it was dissolved in 100 L of methanol before addition. After stirring for 10 minutes, the condensation agent 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) [TCI] or 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride n-hydrate (DMT-MM) [Wako Pure Chemical Industries, Ltd.] was added and stirred for 6 hours. After completion of the reaction, the reaction solution was dialyzed for 3 days using a dialysis membrane (MWCO 12-14,000, width: 45 mL, volume / length: 6.42 mL / cm) [Thermo Fisher Scientific]. The condensation rate was measured. 1 The reaction mixture after dialysis was treated with a strong basic ion exchange resin to remove counter anions, yielding hydrophobic polyvinylamine.

[0074] [Evaluation of gas absorption materials] Here, the amine-containing gel particles synthesized in Synthesis Examples 2 to 4 were used as the gel particles. (1) Study on the phase transition of amine-containing gel particles The amine-containing gel particles synthesized in Synthesis Example 2 were dissolved in water to prepare a particle solution (4 mg / mL). Figure 4 shows the temperature-dependent change in particle size of amine-containing gel particles when the particle solution was heated in the presence or absence of carbon dioxide. Figure 5 shows the change in solution pH when the particle solution was cooled to 20°C after absorbing carbon dioxide and heating it to approximately 60°C to release the carbon dioxide. Figure 6 shows the results of a titration test using hydrochloric acid after the particle solution was held at 30°C, 45°C, 60°C, and 75°C. Figure 7 shows the time course of carbon dioxide release when the particle solution was heated to approximately 75°C to release the carbon dioxide. For the measurements in Figures 5 and 7, carbon dioxide gas was absorbed into the particle solution by immersing a stainless steel reactor containing the particle solution in a water bath at 20°C or 30°C and passing a 10:90 mixture of carbon dioxide and nitrogen gas through the vessel for 240 minutes. Carbon dioxide gas emission was performed by immersing the stainless steel reactor in a water bath at 60°C or 75°C. The amount of carbon dioxide emitted was determined by measuring the increase or decrease in carbon dioxide in the gas passing through the reactor during the emission process. Figure 7 also shows the results of an investigation into the amount of carbon dioxide gas emitted under similar conditions for homopolymers of N-[(3-dimethylamino)propyl]methacrylamide (a low-molecular-weight amine) and N-(dimethylaminopropyl)acrylamide.

[0075] As shown in Figures 4 and 5, the particle size and pH of these amine-containing gel particles change depending on the temperature. Furthermore, Figure 6 shows that the apparent pKa of this particle solution was approximately 8 at 30°C and approximately 5.5 at 75°C. These results confirm that these amine-containing gel particles are temperature-responsive particles that undergo a phase transition in response to temperature changes. Furthermore, Figure 7 confirms that these amine-containing gel particles efficiently release absorbed carbon dioxide gas when heated to 75°C. Furthermore, almost no carbon dioxide release was observed in aqueous solutions of low-molecular-weight amines with similar structures or homopolymers of N-(dimethylaminopropyl)acrylamide that did not form particles. This suggests that the phase transition of the particles triggers efficient carbon dioxide release in the amine-containing gel particles.

[0076] (2) Comparison of gas absorption and desorption characteristics between gel particle membranes and homogeneous gel membranes Example 1 The aqueous solutions of amine-containing gel particles obtained in Synthesis Examples 2 to 4 were freeze-dried to prepare methanol solutions (10 mg / mL). This methanol solution was poured into a stainless steel container, dried at 80°C, and then water was added to cause swelling, producing gel particle films of various thicknesses. The thickness of the gel particle film was adjusted by changing the amount of methanol solution poured into the container.

[0077] (Comparative Example 1) An ethanol solution of the monomers with the same composition as that prepared in Synthesis Example 2 was poured into a stainless steel container and degassed for 30 minutes under a nitrogen atmosphere. After that, a DMF solution of benzoyl peroxide was added. A polymer membrane was produced by reacting for at least 6 hours at room temperature under a nitrogen atmosphere. This polymer membrane was washed with water, dried at 80°C, and then swelled by pouring water into it, yielding various gel homogeneous membranes with different thicknesses. The thickness of the gel homogeneous membrane was adjusted by changing the amount of monomer solution poured into the container. Here, "gel homogeneous membrane" refers to a dense film-like membrane that does not contain particles.

[0078] The reactor in which the gel particle film was formed in Example 1 and the reactor in which the uniform gel film was formed in Comparative Example 1 were immersed in a water bath at 30°C, and a carbon dioxide-containing gas prepared by humidifying a mixed gas of carbon dioxide gas and nitrogen gas (10:90) using a humidifier at 60°C was passed through these containers at 300 mL / min for approximately 10 minutes. After confirming with an infrared carbon dioxide concentration meter that the absorption of carbon dioxide into the film had been completed, the containers were transferred to a water bath at 75°C and held there for 3 minutes. During this time, the amount of carbon dioxide in the gas passing through the container was quantified with the infrared carbon dioxide concentration meter, and the carbon dioxide emission rate and absorption rate were calculated from the increase or decrease in the amount of carbon dioxide. The results of measuring the carbon dioxide gas emission rate for the gel particle membrane of Example 1 and the homogeneous gel membrane of Comparative Example 1 are shown in Figures 8 and 9, and the results of measuring the carbon dioxide absorption rate are shown in Figure 10. The numerical values ​​in units of "nm" shown in Figures 8 to 10 are the particle diameter of the gel particles, with "300 nm gel particle membrane" representing the membrane of gel particles synthesized in Synthesis Example 2, "1 μm gel particle membrane" representing the membrane of gel particles synthesized in Synthesis Example 3, and "crosslinked gel particle membrane" representing the membrane of gel particles synthesized in Synthesis Example 4. As shown in Figures 8 to 10, all of the gel particle membranes had larger carbon dioxide absorption and emission amounts than the homogeneous gel membrane, confirming that the carbon dioxide absorption and emission capacity was improved by forming a polymer compound having amino groups into particles. The reason why the carbon dioxide diffusion rate of the gel particle membrane is particularly faster than the absorption rate is presumably because, in the carbon dioxide absorption process, the gel particles swell significantly, leaving small voids between the particles, whereas in the diffusion process, the gel particles shrink, leaving large voids that contribute to gas diffusion.

[0079] [Gas absorber evaluation] In the evaluation of the gas absorber, the amine-containing gel particles synthesized in Synthesis Example 1 were used as the gel particles. (3) The effect of supporting gel particle films on various thin plates The substrates used were 0.1 mm or 0.3 mm thick stainless steel thin plates (thermal conductivity approximately 16 W / (m K)), 0.1 mm thick iron thin plates (thermal conductivity approximately 80 W / (m K)), and 0.1 mm thick graphite sheets (Panasonic Corporation, PGS graphite sheet EYGS182310, thermal conductivity 600-800 W / (m K)). A perforated silicone rubber sheet was attached to each substrate as a mold. Separately, the amine-containing dry gel particles synthesized in Synthesis Example 1 were dissolved in methanol to prepare a particle solution (50 mg / 3 mL). This particle solution was applied to the inside of the mold and placed in an incubator at 40 °C for vacuum drying. The particle solution was similarly applied to the backside of the substrate and dried in an oven at 80 °C for 30 minutes to obtain a laminate consisting of the substrate and dry particle film. However, because the silicone rubber sheet of the mold did not adhere to the graphite sheet, the silicone rubber sheet was fixed with clips and used. While heated on a hot plate at 80 °C, the particle solution was spread using a brush to support the support. Then, as with the other supports, the support coated with the particle solution was dried in a dryer at 80 °C to obtain a laminate. After drying, the weight of the laminate was measured, and the weight of the supported amine-containing dry gel particles was quantified. The amine-containing dry gel particles were then gelled by adding 4 equivalents (4 mL / g) of water. Through these steps, a gas absorber with a gel particle film supported on the support was obtained. The thickness of the gel particle film of each obtained gas absorber was 37 μm.

[0080] Next, a reactor shown in Fig. 11 was prepared. This reactor has a pair of acrylic plates 1, butyl rubber gaskets 2 arranged on each of the opposing surfaces of the pair of acrylic plates 1, and a plurality of screws 4 for fixing the pair of acrylic plates 1 together, and is configured so that a gas absorber 3 is sandwiched between the pair of butyl rubber gaskets 2. In addition, a gas inlet 5 and a gas outlet 6 are provided on the upper acrylic plate 1 of this reactor, and gas from a gas supply means (not shown) is supplied to the gas absorber 3 through the gas inlet 5 and then discharged to the outside through the gas outlet 6. In this experimental example, a gas absorber was fixed to the reactor shown in Figure 11, and a carbon dioxide absorption / desorption experiment was conducted by passing a carbon dioxide-containing gas through it (10 mL / min). The carbon dioxide-containing gas was 60°C, obtained by humidifying nitrogen gas containing 10% carbon dioxide using a humidifier at 60°C. Carbon dioxide absorption was performed by placing the reactor in a water bath at 30°C, and carbon dioxide desorption was performed by placing the reactor in a water bath at 75°C. The carbon dioxide absorption and desorption amounts of the gas absorber were calculated from the increase or decrease in carbon dioxide in the gas passing through the reactor. Figures 12 and 13 show the time-dependent changes in the carbon dioxide absorption and desorption amounts for each gas absorber. In Figures 12 and 13, "sus" indicates a stainless steel thin plate support, "Fe" indicates an iron thin plate support, and "C" indicates a graphite sheet support. In Figure 12, the reactor was placed in a 75°C water bath at 0 and 75 minutes after the start of the experiment to measure the carbon dioxide emission rate, and then placed in a 30°C water bath at 25 and 100 minutes after the start of the experiment to measure the carbon dioxide absorption rate. Figure 12 graphs the emission and absorption rates of the gas absorber at 0, 25, 75, and 100 minutes. Figure 13 graphs the emission and absorption rates of the gas absorber at 0, 30, 75, 100, 140, and 170 minutes after the start of the experiment to measure the emission rate. Figure 13 graphs the emission and absorption rates of the gas absorber at 0, 30, 75, 100, 140, and 170 minutes. The vertical axis of the graphs in Figures 12 and 13 represents the carbon dioxide emission rate per mass of amine-containing dry gel particles from the gas absorber. Negative emission rates indicate carbon dioxide absorption.

[0081] When a 0.1 mm-thick stainless steel plate (thermal conductivity approximately 16 W / (m K)) was used as a support, it took approximately 14 min to desorb 25 mL of carbon dioxide per 1 g of amine-containing dry gel particles, and approximately 26 min to absorb 25 mL of carbon dioxide. The maximum reversible carbon dioxide desorption / absorption volume per 1 g of amine-containing dry gel particles was 31–38 mL (Figures 12 and 13). On the other hand, when the stainless steel plate was 0.3 mm thick, the desorption rate was approximately 1.5 times faster and the absorption rate was approximately 2 times faster than when the stainless steel plate was 0.1 mm thick. It took only approximately 10 min to desorb 25 mL of carbon dioxide per 1 g of amine-containing dry gel particles, and approximately 13 min to absorb 25 mL of carbon dioxide per 1 g of amine-containing dry gel particles (Figure 12). Similarly, the reversible carbon dioxide desorption / absorption volume per 1 g of amine-containing dry gel particles increased to 42–48 mL (Figure 12). On the other hand, when a thin plate of iron, which has a relatively high thermal conductivity (thermal conductivity of approximately 80 W / (m K)), was used as the support, the diffusion rate was accelerated by approximately 1.8 times and the absorption rate by approximately 2.2 times, despite the same 0.1 mm thickness. It took only approximately 8 minutes to diffuse 25 mL of carbon dioxide per 1 g of amine-containing dry gel particles, and only approximately 12 minutes to absorb 25 mL of carbon dioxide. Similarly, the reversible carbon dioxide diffusion and absorption rates per 1 g of amine-containing dry gel particles were 33–42 mL (Figure 13). Furthermore, when a 0.1 mm thick graphite sheet (Panasonic, PGS graphite sheet EYGS182310, thermal conductivity 600-800 W / (mK)) was used, the emission and absorption rates were both accelerated by approximately 2.3 times compared to a 0.1 mm thick stainless steel sheet. It took only approximately 6 minutes to emit 25 mL of carbon dioxide per 1 g of amine-containing dry gel particles, and approximately 10 minutes to absorb 25 mL of carbon dioxide. Similarly, the reversible carbon dioxide emission and absorption capacity per 1 g of amine-containing dry gel particles increased to 60 mL (Figure 13). Similarly, when a 0.1 mm thick aluminum sheet was used, the emission rate was accelerated by approximately 1.8 times, and the absorption rate was accelerated by approximately 1.5 times, compared to a 0.1 mm thick stainless steel sheet.

[0082] (4) Effect of various amounts of amine-containing gel particle membranes Using a 0.1 mm thick graphite sheet (Panasonic, PGS graphite sheet EYGS182310, thermal conductivity 600-800 W / (mK)) as a support, the thickness of the supported amine-containing gel particle film was changed from 37 μm to 230 μm. This resulted in an increase in the reversible carbon dioxide absorption per reactor internal volume from 208 mL / L to 1160 mL / L (Figure 14). In Figure 14, carbon dioxide was sufficiently absorbed at 30 °C to reach equilibrium, and then the temperature was raised to 75 °C to release carbon dioxide. The release of carbon dioxide was initiated at 0 min, and the reactor was then placed in a 30 °C water bath 30 min after the start of the experiment to measure the amount of carbon dioxide absorbed. Figure 14 also shows a graph of the release and absorption amounts of the gas absorber from 0 min and 30 min. The vertical axis of the graph represents the amount of carbon dioxide released per reactor internal volume. A negative absorption amount indicates that carbon dioxide is being absorbed.

[0083] (5) Effect of supporting accelerator-containing amine-containing gel particle membrane A 0.1 mm thick graphite sheet (Panasonic, PGS graphite sheet EYGS182310, thermal conductivity 600-800 W / (mK)) was used as a support, supporting a 230 μm amine-containing gel particle film. Adding 1 M N,N',N"-pentamethyldiethylenetriamines as a promoter improved the reversible carbon dioxide absorption per reactor volume from 1160 mL / L to 4000 mL / L.

[0084] (6) The effect of supporting a thin gel film using various fibers as a carrier Figure 15 shows the stainless steel reactor used in this experiment. 3 The reactor has a space 11 with a volume of (length 80 mm, width 150 mm, depth 5 mm), and thirteen flow straightening plates 12 are arranged at 10 mm intervals within the space 11. The reactor also has a gas inlet 13 for introducing gas from a gas supply means (not shown) into the space 11, and a gas outlet 14 for discharging the gas from the space 11.

[0085] A predetermined amount of amine-containing dry gel particles was dissolved in methanol and stirred overnight. The solution concentration was adjusted to approximately 17 mg / mL. Next, stainless steel fiber felt (Nippon Seisen Co., Ltd., Naslon Felt 12-5-1500 and 8-5-1500, fiber diameter 12 μm and 8 μm, thickness 5 mm, basis weight 1500 g / m) cut into 80 mm × 8 mm × 5 mm was used as a carrier. 2) and aluminum fiber felt (fiber diameter 100 μm) were prepared. These carriers were fixed in the space 11 of the reactor shown in Figure 15 and heated on a hot plate at 80 °C. A methanol solution of amine-containing dry gel particles was evenly applied to the heated carrier using a syringe. Since evaporation of the methanol was slow when heated from below, heat was applied from above using a dryer to evaporate the methanol so that the amine-containing dry gel particles were uniformly supported. A predetermined amount of water was added to the amine-containing dry gel particles supported on the carrier to gel them, creating an amine-containing gel support material (gas absorber). This gas absorber was placed inside the reactor shown in Figure 15, and a carbon dioxide absorption / desorption experiment was conducted by passing a carbon dioxide-containing gas through it (10 mL / min). The carbon dioxide-containing gas used was nitrogen gas containing 10% carbon dioxide humidified with a 60 °C humidifier. Carbon dioxide absorption was performed by placing the reactor in a water bath at 30 °C, and carbon dioxide desorption was performed by placing the reactor in a water bath at 75 °C. The gas passing through the reactor was passed through a 5°C condenser to remove moisture from the gas, and the amount of carbon dioxide in the gas was quantified at regular intervals using a gas chromatograph (Shimadzu Corporation, product name GC-TCD). The amount of carbon dioxide absorbed and released by the gas absorber was calculated from the increase or decrease in carbon dioxide in the gas. Figures 16 to 23 show the time-dependent changes in the amount of carbon dioxide absorbed and released for each gas absorber. Figures 16 to 19 are graphs for gas absorbers using Naslon Felt 12-5-1500 as the carrier. In Figures 20 to 23, "AlΦ100" indicates an aluminum fiber felt carrier, "susΦ12" or "12-5-1500" indicates a Naslon Felt 12-5-1500 carrier, and "8-5-1500" indicates a Naslon Felt 8-5-1500 carrier. 16 to 23, the numerical values ​​in units of "mg / ml" represent the amount of amine-containing dry gel particles applied to the carrier. In Figures 16 to 23, the reactor was placed in a 75°C water bath at 0, 71, and 142 minutes from the start of the experiment to measure the amount of carbon dioxide emitted, and then placed in a 30°C water bath at 25 and 96 minutes from the start of the experiment to measure the amount of carbon dioxide absorbed. Figures 16 to 23 graph the amount of carbon dioxide emitted or absorbed by the gas absorber from 0, 25, 71, 96, and 142 minutes.16 to 23, the vertical axes of the graphs in FIGS. 16, 18, 20, and 22 represent the amount of carbon dioxide emitted per volume of fiber assembly, and the values ​​represented by the vertical axes of the other graphs are the same as the values ​​represented by the vertical axis in FIG.

[0086] When fibers are used as a carrier, it was found that the thickness of the fibers and the amount of gel carried affect the reversible absorption amount and absorption speed. Specifically, stainless steel fiber felt (Nippon Seisen Co., Ltd., Naslon Felt 12-5-1500, fiber diameter 12 μm, thickness 5 mm, basis weight 1500 g / m) 2 When various amounts of amine-containing gel particles (water loading of 4 mL / g) were applied to the cellulose membrane, increasing the amount of applied amine-containing dry gel particles from 100 mg to 200 mg approximately doubled the reversible carbon dioxide absorption capacity. However, increasing the amount from 200 mg to 400 mg dramatically decreased the reversible carbon dioxide absorption capacity (Figures 16 and 17). Furthermore, when the amount of water added was varied while keeping the amount of amine-containing dry gel particles constant, even with a high amount of amine-containing dry gel particles, decreasing the amount of water added from 4 mL / g to 2 mL / g slightly increased the reversible carbon dioxide absorption capacity (Figures 18 and 19). These results indicate that limiting the gel loading rate, including water, to approximately 15-40% is necessary for efficient reversible carbon dioxide absorption. When the fiber diameter was increased from 12 μm to 100 μm (aluminum fiber) at the optimized loading rate, the reversible carbon dioxide absorption performance decreased despite the high thermal conductivity of the material (aluminum) (Figures 20 and 21). This is thought to be because the surface area of ​​the fiber decreases as the fiber diameter increases, resulting in a thicker gel particle film. On the other hand, when the fiber diameter was changed from 12 μm to 8 μm, the diffusion and absorption behavior was found to be almost unchanged (Figures 22 and 23). This indicates that if fibers thinner than 100 μm are used, the absorption and diffusion performance does not depend so strongly on the fiber diameter, and high performance can be achieved.

[0087] (7) Comparison of results with and without gel particle membranes supported on the carrier (Example of preparation and evaluation of gel particle membranes not supported on a carrier) A methanol solution of amine-containing dry gel particles (particle solution) was obtained by dissolving 2.4 g of amine-containing dry gel particles in methanol and stirring overnight. The stainless steel reactor (Figure 15) was placed on a hot plate at 80 °C and heated. The prepared particle solution was applied to the inner surface of the reactor while the methanol evaporated. Specifically, one-third of the total solution volume was applied to the bottom of the stainless steel reactor, one-third of the total solution volume to the upper lid, and one-third of the total solution volume to the comb part of the lid. After drying the particle solution, 4.8 mL of water was added to form a gel film, forming an amine-containing gel particle film on the inner surface of the reactor. Carbon dioxide absorption and desorption experiments were conducted by passing a carbon dioxide-containing gas through the reactor (50 mL / min). The carbon dioxide-containing gas was 60°C, obtained by humidifying nitrogen gas containing 10% carbon dioxide using a humidifier at 60°C. Carbon dioxide absorption was performed by placing the reactor in a water bath at 30°C, and carbon dioxide desorption was performed by placing the reactor in a water bath at 75°C. The gas passing through the reactor was passed through a condenser at 5°C to remove moisture, and the amount of carbon dioxide in the gas was quantified at regular intervals using gas chromatography (Shimadzu Corporation, product name GC-TCD). The amount of carbon dioxide absorbed and released by the gel particle membrane was calculated from the increase or decrease in carbon dioxide in the gas. Figure 24 shows the time course of the amount of carbon dioxide absorbed and released by the gel particle membrane.

[0088] (Example of preparation and evaluation of gel particle membrane supported on a carrier) 2.4 g of amine-containing dried gel particles were dissolved in methanol and stirred overnight to obtain a methanol solution of amine-containing gel particles (particle solution). A stainless steel fiber felt (Naslon felt, 12-5-1500 / m) was placed inside a stainless steel reactor (Figure 15). 2The reactor was loaded with 12 amine-containing dry gel particles and heated on a hot plate at 80°C. The particle solution was evenly applied using a syringe so that 200 mg of amine-containing dry gel particles were supported on each felt in the reactor, and the reactor was left in this state to evaporate the methanol from the particle solution. If the methanol evaporation was slow, heat was applied from above using a dryer to evaporate the methanol so that the amine-containing dry gel particles were uniformly supported. 400 μL (4.8 mL in total) of water was added to each of the 12 supports supporting the amine-containing dry gel particles to gel the particles, yielding a gas absorber with an amine-containing gel particle film supported on the support. Carbon dioxide absorption and desorption experiments were conducted by passing a carbon dioxide-containing gas (50 mL / min) through a container containing a gas absorber. The carbon dioxide-containing gas used was 10% carbon dioxide-containing nitrogen gas humidified with a 60°C humidifier. Carbon dioxide absorption was performed by placing the reactor in a water bath at 30°C, and carbon dioxide desorption was performed by placing the reactor in a water bath at 75°C. The gas passing through the reactor was passed through a condenser at 5°C to remove moisture, and the amount of carbon dioxide in the gas was quantified at regular intervals using gas chromatography (Shimadzu Corporation, product name GC-TCD). The amount of carbon dioxide absorbed and released by the gas absorber was calculated from the increase or decrease in carbon dioxide in the gas. Figure 24 shows the time course of carbon dioxide absorption and desorption for each absorber. In Figure 24, "12-5-1500 felt" refers to a gas absorber using stainless steel fiber felt (Naslon Felt 12-5-1500) as a carrier, and the values ​​in "mg / ml" represent the amount of amine-containing dry gel particles applied to the carrier or container. In Figure 24, the reactor was placed in a 30°C water bath at 25, 96, and 167 minutes after the start of the initial emission to measure the amount of carbon dioxide absorbed. It was also placed in a 75°C water bath at 0, 71, and 142 minutes after the start of the experiment to measure the amount of carbon dioxide emitted. Figure 24 plots the amount of carbon dioxide emitted or absorbed by the gas absorber at 0, 25, 71, 96, 142, and 167 minutes. The values ​​on the vertical axis of the graph in Figure 24 are the same as those in Figure 12.

[0089] The results of the above experiments showed that the gel particle membrane formed directly inside the reactor could reversibly absorb only 50–120 mL of carbon dioxide, whereas the gas absorber in which the gel particle membrane was supported on a 12 μm stainless steel fiber felt was able to reversibly absorb 98–130 mL of carbon dioxide. Furthermore, when the gel particle membrane was formed directly inside the reactor, it took 23 minutes to release 120 mL of carbon dioxide gas in the reversible absorption process described above. However, when the gel particle membrane was supported on the stainless steel fiber felt, the release of carbon dioxide gas was completed within 9 minutes. Similarly, when the gel particle membrane formed directly inside the reactor absorbed approximately 120 mL of carbon dioxide gas in the reversible absorption process described above, it took 45 minutes. However, when the gel particle membrane was supported on the stainless steel fiber felt, the release of carbon dioxide gas was completed within 18 minutes. As described above, it was confirmed that by using metal fibers as a carrier and supporting a gel particle membrane at an appropriate filling rate, the average reversible absorption amount can be improved by 1.3 times, the diffusion rate by 2.6 times, and the absorption rate by 2.5 times.

[0090] Next, experiments were conducted using felt made of stainless steel fibers and sintered metal fibers made by sintering felt made of stainless steel fibers. A felt made of stainless steel fibers (Naslon Felt, 12-5-1500 / m) was placed on an iron plate heated to 80°C. 2 sintered metal fiber (Nippon Seisen, SUS316L, basis weight 1600g / m) 2A sintered metal fiber (fiber diameter: 50 μm, porosity: 89%) was placed on the substrate, and 550 μL of a solution prepared by dissolving the amine-containing gel particles obtained in Synthesis Example 1 in methanol at a concentration of 20 mg / mL was added and dried. The substrate was then placed in a reactor, and 4 equivalents of water per amine-containing gel particle were added. For each experiment, three samples were prepared with different gel particle packing ratios, and the carbon dioxide emission and absorption rates were measured using the same method as above. Figure 25 is a graph showing the relationship between gel packing ratio and carbon dioxide emission and absorption rates. Figure 25 confirms that when sintered metal fiber is used, the gel particles can maintain their high carbon dioxide absorption and desorption capacity even when the gel particle packing ratio is high (e.g., 60% or higher). Next, carbon dioxide absorption / desorption experiments were conducted using the same method as above with sintered metal fibers (fiber diameters 12 μm and 50 μm) made from sintered stainless steel fiber felt, metal foams (Sumitomo Metals, Celmet #4, #5, and #7), and sintered nickel fibers (fiber diameter 40 μm). Figure 26 shows the results of measurements of carbon dioxide absorption by the reactor, which was placed in a 30°C water bath at 25 and 96 minutes after the start of the initial desorption. The reactor was also placed in a 75°C water bath at 0 and 71 minutes after the start of the experiment. Figure 26 plots the desorption and absorption rates of the gas absorber at 0, 25, 71, and 96 minutes. The values ​​on the vertical axis of the graph in Figure 26 are the same as those in Figure 12. Figure 26 demonstrates that metal foams can be used as effectively as sintered metal fibers. It was also confirmed that sintered nickel fiber is excellent in terms of carbon dioxide absorption rate, absorption amount, emission amount, and emission rate, and can be preferably used.

[0091] When 2.4 g of amine-containing dry gel particles were dissolved in methanol and uniformly applied inside the reactor shown in Figure 15, and then dried, 4.8 mL of water was added to create a gel particle film. Only 50 to 120 mL of carbon dioxide could be reversibly absorbed, but a film with a volume of approximately 60,000 mm was able to absorb the same amount of carbon dioxide. 3Four 0.1 mm thick graphite sheets (Panasonic, PGS graphite sheet EYGS182310, thermal conductivity 600-800 W / (mK)) were stacked inside a space (40 mm long, 170 mm wide, approximately 8.8 mm deep). 2 When 2.4 grams of gel particles were uniformly coated on a substrate (40 mm long, 170 mm wide) and 4.8 mL of water was added to form a gel film, 120–140 mL of carbon dioxide could be reversibly absorbed. Furthermore, when a gel particle film was formed directly inside the reactor, it took 23 minutes to dissipate 120 mL of carbon dioxide gas in the reversible absorption process. However, when four graphite sheets carrying gel films were stacked, carbon dioxide dissipation was completed within 15 minutes. Similarly, when a gel particle film was formed directly inside the reactor, it took 45 minutes to dissipate approximately 20 mL of carbon dioxide gas in the reversible absorption process. However, when four graphite sheets carrying gel films were stacked, carbon dioxide dissipation was completed within 25 minutes. As described above, by supporting a gel particle film on the graphite sheet carrier, the average reversible absorption amount was improved by 1.5 times, the diffusion rate by 1.5 times, and the absorption rate by 1.8 times. In addition, when 2.4 grams of amine-containing dry gel particles were dissolved in methanol and uniformly applied inside the reactor shown in Figure 15, dried, and then 4.8 mL of water was added to create a gel particle film, only 50 to 120 mL of carbon dioxide could be reversibly absorbed. However, the gas flow path volume was approximately the same as that of the reactor, approximately 60,000 mm. 3 The heat transfer surface of six stainless steel thin plates (each 18,000mm) of a plate heat exchanger (HISAKA WORKS, LTD., UX-0005A-J-8 plates) with a length of 40mm, width of 170mm, and depth of approximately 8.8mm. 2When 2.4 grams of amine-containing dry gel particles were dissolved in methanol and uniformly coated on a substrate, dried, and then 4.8 mL of water was added to form a gel particle film. This resulted in reversible absorption of 120-140 mL of carbon dioxide. Furthermore, when a gel particle film was directly formed inside the reactor, it took 23 minutes to release 120 mL of carbon dioxide gas in the reversible absorption process. However, when four thin stainless steel plates carrying the gel film were stacked, carbon dioxide release was completed within 14 minutes. Similarly, when a gel particle film was directly formed inside the reactor, it took 45 minutes to release approximately 120 mL of carbon dioxide gas in the reversible absorption process. However, when four thin stainless steel plates carrying the gel film were stacked, carbon dioxide release was completed within 24 minutes. As described above, by supporting a gel particle film on a thin stainless steel plate carrier, the average reversible absorption amount was improved by 1.5 times, the diffusion rate by 1.6 times, and the absorption rate by 1.9 times.

[0092] In addition, the heat transfer surface of six stainless steel thin plates (each 18,000 mm) of a plate heat exchanger (HISAKA WORKS, UX-0005A-J-8 plates) 2 3.9 grams of the amine-containing dry gel particles obtained in Synthesis Example 1 were dissolved in methanol and uniformly coated on a substrate. After drying, 4.8 mL of water was added to form a gel particle film. A 10.9% CO2-containing nitrogen gas was passed through the substrate at 200 mL / min to measure carbon dioxide absorption and desorption. The reactor was placed in a 30°C water bath at 25, 96, and 167 minutes after the start of initial desorption to measure the amount of carbon dioxide absorbed. The reactor was then placed in a 75°C water bath at 0, 71, and 142 minutes after the start of the experiment to measure the amount of carbon dioxide emitted. Figure 27 graphs the amount of carbon dioxide emitted or absorbed by the gas absorber at 0, 25, 71, 96, 142, and 167 minutes. The values ​​on the vertical axis of the graph in Figure 27 are the same as those on the vertical axis in Figure 12. Excellent results were obtained for the carbon dioxide absorption rate, absorption amount, desorption amount, and desorption rate. Figure 28 shows the change in vapor pressure when the temperature of the water bath is changed between 30 and 75°C. The results in Figure 28 indicate that the gel particle film reversibly absorbs water vapor as well as carbon dioxide.

[0093] (8) Study of methods for stabilizing gel films Gel particle membranes consisting only of amine-containing gel particles are highly water-absorbent, and depending on the conditions of repeated use, this may increase the membrane thickness, leading to blockage of the gas flow path and a decrease in the gas absorption / desorption rate and reversible absorption amount. Furthermore, the gel particle membrane may become fluidized and flow away from the carrier surface. To solve these problems, we added a stabilizer to the gel particle membrane and investigated the conditions under which a stable membrane could be obtained even under conditions of high water addition.

[0094] (8-1) Stabilization of amine-containing gel particle membranes using polyvinyl alcohol / polyethylene copolymer as a stabilizer We added polyvinyl alcohol / polyethylene copolymer as a stabilizer to an amine-containing gel particle film composed of amine-containing gel particles at a concentration of 33 mass% or 50 mass% (mass fraction of solids excluding dispersion medium), and observed the behavior of the gel particles when an excess amount of water was added. Specifically, we conducted the following experiment. First, a particle solution consisting of amine-containing dry gel particles labeled with a fluorescent dye (dansyl group), unlabeled amine-containing dry gel particles, and a stabilizer, polyvinyl alcohol / polyethylene copolymer, was dissolved in a solvent, and the coating amount of the dry gel particles was 113 mg / m. 2The gel particle film was formed by applying the solution to the inside of a glass vial and drying it in an oven at 80°C for 1.5 hours. The polyvinyl alcohol / polyethylene copolymer used was EVOH (E29) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., polyethylene copolymer ratio: 29%) or EVOH (E44) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., polyethylene copolymer ratio: 44%). Gel particle films were also formed in glass vials in the same manner, except that no stabilizer was used. An excess amount of water (10 mL / 20 mg polymer) was poured into each glass vial and left for 48 hours. The amount of amine-containing gel particles dissolved from the gel particle film into the aqueous layer was calculated based on the amount of fluorescent dye. The amine-containing gel particle film without the addition of a stabilizer was completely dissolved, and strong fluorescence above the detection limit was observed. When polyvinyl alcohol / polyethylene copolymer (EVOH (E29)) with a polyethylene copolymer ratio of 29% was used as a stabilizer, the addition of 33 mass% reduced the amount of amine-containing gel particle film leaching to less than half of that without the addition of a stabilizer. The gel particle membrane containing 50% stabilizer almost completely prevented leaching, and the amount of fluorescent dye-labeled amine-containing gel particles dissolved in the water was below the detection limit. On the other hand, when using a stabilizer containing 44% polyethylene (EVOH (E44)), the amount of fluorescent dye dissolved in the water layer was also suppressed below the detection limit by adding 33% or 50% by mass. These results demonstrate that adding a polymer with a high polyethylene content and high crystallinity as a stabilizer is effective in preventing leaching of amine-containing gel particles at room temperature. Furthermore, the carbon dioxide absorption and release rates of the gel particle membrane prepared under the same conditions were measured using the reactor shown in Figure 15. The time-dependent change in the carbon dioxide release rate of the gel particle membrane is shown in Figure 29, and the time-dependent change in the carbon dioxide absorption rate of the gel particle membrane is shown in Figure 30. In Figures 29 and 30, the vertical axis represents the amount of carbon dioxide released or absorbed per unit mass of amine-containing dry gel particles. 29 and 30, the amounts of carbon dioxide absorbed and released by the gel particle membrane with stabilizer added were both equivalent to those of the gel particle membrane without stabilizer added. However, the absorption rate tended to be slightly slower as the amount of stabilizer added increased.

[0095] As described above, it was confirmed that the addition of polyvinyl alcohol / polyethylene copolymer dramatically suppressed the dissolution of amine-containing gel particles at room temperature. However, when the temperature was repeatedly changed between 75°C and 30°C in an aqueous environment and carbon dioxide was repeatedly released and absorbed, the stability of the film decreased under some conditions, and the gel particle film sometimes fragmented. Therefore, we investigated a method for creating gel particle films that would maintain their morphology more stably, even in environments where the temperature and carbon dioxide absorption amount changed significantly. A predetermined amount of stabilizer (EVOH (E44)) and amine-containing dry gel particles were dissolved in a mixed solvent of isopropanol and water (volume ratio: 6:4), applied to a glass vial, and stirred at 60°C for 4 hours. A titanium-based crosslinker (TC-310 or TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) diluted with the same solvent was added to the stabilizer-containing particle solution at a mass ratio of approximately 1 / 8 of the stabilizer (EVOH (E44)). After stirring for 1 hour, the mixture was dried in a hot air dryer at 60°C for 12 hours to form a particle film. The particle film was then stabilized by heat treatment at 110°C or 150°C for 1 hour. 200 equivalents of water were added to the particle film to form a gel, which was then allowed to stand at room temperature for 12 hours. As a result, the gel particle film that gelled after heat treatment at 110°C was observed to be somewhat stabilized by adding 9 mass% or more (mass fraction of solids excluding dispersion medium) of stabilizer, but the film fragmented and peeled off from the glass vial (Figure 31(A)). On the other hand, the gel particle film that gelled after heat treatment at 150°C did not break even after being left undisturbed at room temperature for 12 hours, confirming that the film was sufficiently stabilized by adding 3 mass% (mass fraction of solids excluding dispersion medium) of stabilizer. Furthermore, the phenomenon of dissolution of the gel particle film was almost completely suppressed (Figure 31(B)). Furthermore, when the temperature was repeatedly changed between 75°C and 30°C in the presence of 10% carbon dioxide, swelling of the gel particle film crosslinked with the titanium crosslinker (TC-400) was observed with the addition of 6% and 33% stabilizer (mass fraction of solids excluding dispersion medium), and swelling of the gel particle film crosslinked with the titanium crosslinker (TC-310) was observed with the addition of 6% stabilizer (mass fraction of solids excluding dispersion medium), but no fragmentation or rupture of the film was observed (Figure 31(C)). For the gel particle film crosslinked with TC-310 and containing 33% stabilizer (mass fraction of solids excluding dispersion medium), no significant change in swelling was observed even after two temperature cycles.Furthermore, we evaluated the reversible carbon dioxide absorption performance of a gel particle membrane crosslinked with TC-310 and stabilized with 33% by mass (mass fraction of solids excluding the dispersion medium) using the reactor shown in Figure 15. Compared to a gel particle membrane without stabilizer, the carbon dioxide absorption and desorption rates were approximately 10% lower, but there was almost no adverse effect on the desorption and absorption rates (Figure 32). In Figure 32, "EVOH & TC-310" represents a membrane crosslinked with TC-310 and stabilized with EVOH (E44), while "No additive" represents a membrane crosslinked with TC-310 without stabilizer EVOH (E44). In Figure 32, the reactor was placed in a 30°C water bath at 14 and 74 minutes after the start of the experiment to measure the carbon dioxide absorption rate, and at 0 and 60 minutes after the start of the experiment, the reactor was placed in a 75°C water bath to measure the carbon dioxide desorption rate. 32, the amounts of emission and absorption of the gas absorber are graphed from the time points of 0, 14, 60, and 74 minutes. The values ​​represented on the vertical axis of the graph in FIG. 32 are the same as the values ​​represented on the vertical axis in FIG.

[0096] (8-2) Stabilization of gel particle membranes using polyvinylamine as a stabilizer Polyvinyl alcohol / polyethylene copolymer and polyvinylamine were investigated as stabilizers for gel particle membranes. An aqueous solution of amine-containing gel particles and an aqueous polyvinylamine solution were mixed at various mass ratios and stirred for three days. The mixture was then applied to a glass vial and dried under reduced pressure at 40°C, followed by drying at 80°C for one hour at normal pressure. This resulted in the formation of an amine-containing dry gel particle film in the glass vial. Four equivalents of water were added to this amine-containing dry gel particle film to form a gel particle film, and a 10% carbon dioxide-containing gas was passed through the film at room temperature for three hours to dissolve the carbon dioxide. The gel particle film was then heated to 75°C and allowed to stand for 12 hours in the presence of a 10% carbon dioxide-containing gas. This allowed us to investigate whether carbon dioxide crosslinks the primary amines in the polyvinylamine, stabilizing the film. 200 masses of water were poured into the glass vial and allowed to stand for one hour, after which the film stability was observed. The results indicated that gel particle films containing 9 mass% or more (mass fraction of solids excluding the dispersion medium) of polyvinylamine were relatively stable. The stability of the membrane did not improve when the membrane was left standing at room temperature in the presence of 10% carbon dioxide gas for 12 hours, instead of being heated to 75°C and left standing in the presence of 10% carbon dioxide gas for 12 hours. This suggests that the carbon dioxide dissolved in the membrane causes a crosslinking reaction at 75°C, stabilizing the membrane.

[0097] (8-3) Stabilization of thin films of gel particles using polymerizable compounds as stabilizers We investigated the stabilization of gel particle films by using a polymerizable compound as a stabilizer for gel particle films and polymerizing it in the presence of a polymerization initiator. 100 mg of the amine-containing gel particles obtained in Synthesis Example 1 was dissolved in 6 mL of methanol. 95 parts by mass of N,N-dimethylaminopropyl methacrylamide (DMAPM) and 5 parts by mass of N,N'-methylenebisacrylamide (BIS) were dissolved in methanol to prepare a methanol solution with a concentration of 0.05 mg / mL. A methanol solution of a polymerization initiator (IRGACURE 184) was also prepared, and these three methanol solutions were mixed. The mixing ratio was such that the total amount of DMAPM and BIS was 56 parts by mass per 100 parts by mass of the amine-containing gel particles. The polymerization initiator was mixed in an amount of 1 / 60 mole of the monomer. This mixed solution was cast into a stainless steel reactor, slowly dried at room temperature, and then dried in a thermostatic chamber at 35°C. It was then polymerized by ultraviolet irradiation. Water was added to form a gel particle film with a uniform film shape. Even when a large amount of water was added, a gel particle film with a nearly uniform film shape was obtained, with only partial swelling. A carbon dioxide absorption / desorption experiment was conducted using the same method as described above. Figure 33 shows that the reactor was placed in a 30°C water bath at 25, 96, and 167 minutes after the start of the initial desorption to measure the amount of carbon dioxide absorbed. It was also placed in a 75°C water bath at 0, 71, and 142 minutes after the start of the experiment to measure the amount of carbon dioxide emitted. Figure 33 plots the amount of desorption or absorption from the gas absorber at 0, 25, 71, 96, 142, and 167 minutes. The values ​​on the vertical axis of the graph in Figure 33 are the same as those in Figure 12. Figure 33 demonstrates that the resulting gel particle membrane achieved extremely high absorption rate, absorption amount, desorption amount, and desorption rate. The gel particle membrane after the measurements was not excessively swollen and was stable. In the above experiment, a gel membrane was prepared in the same manner using a mixture of DMAPM:BIS:NIPAM=55:5:45 as the polymerizable compound instead of DMAPM:BIS=95:5. Carbon dioxide absorption and desorption tests were conducted to confirm the membrane condition. Here, NIPAM stands for N-isopropylacrylamide. Figure 34 shows the graph of the gas absorber's desorption and absorption rates. As shown in Figure 34, good absorption rates, desorption rates, and desorption rates were achieved. Even when a large amount of water was added during gel membrane formation, the membrane maintained a uniform state. Furthermore, even after the gas absorption and desorption tests, the gel particle membrane was not excessively swollen and remained stable. In addition, a gel membrane was prepared in the same manner using a mixture of DMAPM:BIS:NIPAM = 30:5:65 instead of the DMAPM:BIS = 95:5 polymerizable compound in the above experiment. Carbon dioxide absorption and desorption tests were conducted to confirm the membrane condition. Figure 35 shows the graph of the gas absorber's desorption and absorption amounts. As shown in Figure 35, good absorption rates, absorption amounts, desorption amounts, and desorption rates were achieved. Even when a large amount of water was added during gel membrane formation, the membrane maintained a uniform state. Furthermore, even after the gas absorption and desorption tests, the gel particle membrane was not excessively swollen and remained stable. Furthermore, gel membranes were prepared in the same manner as in the above experiment, except that the polymerizable compound was a DMAPM:BIS ratio of 95:5, but the solvent was changed from methanol to water, and the polymerization initiator was changed to 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone. Carbon dioxide absorption and desorption tests were then conducted to confirm the membrane condition. Figure 36 shows the graphs of the gas absorber's desorption and absorption rates. As shown in Figure 36, good absorption and desorption rates were achieved, but the absorption and desorption rates were somewhat slow. Even when a large amount of water was added during gel membrane formation, the membranes maintained a uniform state. Furthermore, even after the gas absorption and desorption tests, the gel particle membranes were not excessively swollen and remained stable.

[0098] (9) Effect of adding absorption and diffusion promoters Various low molecular weight compounds were added to the gel particle membrane as absorption and desorption promoters, and the effects of adding these compounds on the improvement of the amount of carbon dioxide absorbed, the absorption rate, the amount of carbon dioxide emitted, and the rate of carbon dioxide desorption were examined. A gel particle film was formed in the reactor shown in Figure 15, and a low molecular weight compound represented by the following formula was added to the gel particle film. Alternatively, amine-containing dry gel particles were placed in the reactor, and water, PMDETA containing almost no water, or an aqueous solution of PMDETA was added. Then, under the same conditions as those used in the measurement of Figure 16, one cycle of carbon dioxide absorption and desorption was performed, and the changes in the amount of carbon dioxide absorbed and desorbed over time were examined. The results are shown in Figures 37 to 42. In Figures 37 to 40, "GP+H2O" represents a gel particle film that does not contain the low molecular weight compound represented by the following formula, and the others represent gel particle films to which the low molecular weight compound shown in the table was added at a concentration of 3N or 13 mass% in terms of amine concentration. In Figures 41 and 42, "GP+H2O" represents amine-containing dry gel particles to which water has been added, "GP+PMDEA" represents amine-containing dry gel particles to which PMDETA, which contains almost no water, has been added, and the others represent amine-containing dry gel particles to which PMDETA aqueous solutions with amine-equivalent concentrations of 1N, 3N, and 10N have been added. 37 to 42, it was confirmed that the absorption rate, absorption amount, emission amount, and emission rate were dramatically improved in gel particle membranes to which amine compounds, particularly imino-bis(N,N-dimethylpropylamine) (IBDPA) and N,N',N"-pentamethyldiethylenetriamine (PMDETA), were added. However, if the concentration of the amine compound was too high, the amount of water relative to the amine tended to be too great, and conversely, the absorption amount tended to decrease, suggesting that the presence of an appropriate amount of water is important for improving absorption capacity (Figures 41 and 42). The amount of water present relative to the amine is preferably 5 times or more by mole, more preferably 8 times or more by mole, and even more preferably 10 times or more by mole. In gel particle membranes to which amine compounds were added under optimal conditions, both the absorption amount and emission amount were improved by 3 to 4 times compared to gel particle membranes to which no accelerator was added (Figures 41 and 42).

[0099] [ka]

[0100] Various low molecular weight amines were added to the gel particle membrane as diffusion promoters, and their effect on improving the carbon dioxide diffusion rate from the gel membrane was investigated. A methanol solution (100 mg / 6 mL) of the amine-containing gel particles obtained in Synthesis Example 1 was poured into a stainless steel container and dried at 80°C. The stainless steel container was then cooled with ice from the outside to produce a dry nanogel film. 400 μL of a 3N aqueous amine solution was evenly dropped onto this dry nanogel film. The resulting gel particle film was subjected to one cycle of carbon dioxide absorption and desorption under the same conditions as those used in the measurement of Figure 16, and the amount of carbon dioxide released was measured. The results of measuring the amount of carbon dioxide released using various low-molecular-weight amines are shown in Figure 43. As shown in Figure 43, it was confirmed that the addition of a low-molecular-weight amine can promote desorption. We also fabricated gel particle films in the same manner and investigated the carbon dioxide emissions when 400 μL of a 6N amine aqueous solution was added, and when 800 μL of a 8N amine aqueous solution was added. The results are shown in Figure 44. As shown in Figure 44, TMDAH tended to exhibit reduced carbon dioxide emissions when the amine concentration was too high. However, PMDETA and IPAE demonstrated the ability to achieve high carbon dioxide emissions even at high amine concentrations. IPAE, in particular, achieved significantly higher carbon dioxide emissions even at high amine concentrations, demonstrating exceptionally excellent results. High amine concentrations imply a low ratio of water to amine, and even at these low water concentrations, IPAE achieved significantly higher carbon dioxide emissions. [Industrial Applicability]

[0101] According to the present invention, a gas absorber is realized that can efficiently absorb and release acidic gases such as carbon dioxide and water vapor in response to changes in external temperature. Such a gas absorber can be effectively used in the process of separating and recovering acidic gases in CCS and in the process of separating acidic gases from fuel gas, and has extremely high industrial applicability. [Explanation of symbols]

[0102] 1 acrylic plate 2 Butyl rubber gaskets 3 Gas absorber 4 screws 5 Gas inlet 6 Gas outlet 11 Space section 12 Rectifier plate 13 Gas inlet 14 Gas outlet 21 Heat exchanger 22, 33 Desulfurizer 23 Gas absorber 24 No. 1 Pipe 25 Second Pipe 26 Third Pipe 26a Circulation Route 26b Branching Route 31 1st heat exchanger 32 Second heat exchanger 34 First Tank 35 Second Tank 36 First Pipe 37 Second Pipe 37a Main Route 37b Route 1 37c Route 2 38, 39 Gel particle membrane

Claims

1. a gas inlet for introducing a gas to be treated containing carbon dioxide into the gas absorbing material containing polymer compound particles having amino groups; a heat supply unit for applying heat to the gas absorbing material; a gas exhaust path for exhausting a portion of the gas from the gas absorbing material; and A carbon dioxide recovery method, comprising: recovering carbon dioxide using a circulation path that branches off from the gas discharge path and introduces another portion of the gas into the gas absorbing material; The gas absorbing material satisfies at least one of the following (1) and (2): (1) The water content per 1 g of solids is 0.1 mL or more. (2) The polymer compound particles having amino groups are (meth)acrylamide polymer compound particles. The carbon dioxide recovery method further comprises a heat exchange mechanism with the outside at the gas inlet portion, and the temperature of the gas to be treated is controlled by the heat exchange mechanism.

2. 2. The carbon dioxide recovery method according to claim 1, wherein the gas absorbing material has a heat exchange mechanism with the outside, and the temperature of the gas absorbing material is controlled by the heat exchange mechanism.

3. 2. The carbon dioxide recovery method according to claim 1, wherein a desulfurizer is provided upstream of the gas absorbent material, and the gas to be treated introduced from the gas inlet is introduced into the desulfurizer to be desulfurized, and then introduced into the gas absorbent material.

4. The carbon dioxide recovery method according to claim 3 , wherein the desulfurizer has a cooling function.

5. 5. The carbon dioxide recovery method according to claim 1, wherein a heat exchanger connected to the gas inlet and the circulation path is used as the heat supply unit, and the gas in the circulation path heated by the heat exchanger is introduced into the gas absorbing material, thereby heating the gas absorbing material.

6. a gas inlet for introducing a gas to be treated containing carbon dioxide into the gas absorbing material containing polymer compound particles having amino groups; a heat supply unit for applying heat to the gas absorbing material; a gas exhaust path for exhausting a portion of the gas from the gas absorbing material; and A carbon dioxide recovery apparatus having a circulation path branched from the gas discharge path and introducing another part of the gas into the gas absorbing material, The gas absorbing material satisfies at least one of the following (1) and (2): (1) The water content per 1 g of solids is 0.1 mL or more. (2) The polymer compound particles having amino groups are (meth)acrylamide polymer compound particles. The carbon dioxide recovery device has a heat exchange mechanism with the outside at the gas inlet portion, and controls the temperature of the gas to be treated by the heat exchange mechanism.

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