Acid gas adsorption device and method for manufacturing the acid gas adsorption device

Abstract

An acid gas adsorption device capable of maintaining excellent acid gas adsorption capacity regardless of the usage environment is provided. The acid gas adsorption device according to an embodiment of the present invention includes acid gas adsorption particles and an organic binder. The acid gas adsorption particles are capable of adsorbing acid gas. The organic binder is capable of binding the acid gas adsorption particles. The organic binder is soluble in aprotic polar solvents and substantially insoluble in protic polar solvents.

Description

[Technical Field]

[0001] The present invention relates to an acid gas adsorption device and a method for manufacturing an acid gas adsorption device. [Background technology]

[0002] In recent years, efforts have been made to separate and capture acidic gases contained in the atmosphere in order to reduce environmental impact. Such acidic gases include carbon dioxide (hereinafter sometimes referred to as CO2), which is a major cause of global warming. A representative example of such efforts is the carbon dioxide capture, utilization, and storage (CCUS) cycle. As a carbon dioxide adsorption device used for such carbon dioxide separation and capture, an adsorption structure for capturing CO2 has been proposed, which includes an amine compound having a functional mer group capable of adsorbing carbon dioxide and an organic binder soluble in a protic polar solvent, in which the organic binder binds and holds the amine compound (see, for example, Patent Document 1). Because such an adsorption structure uses an organic binder soluble in a protic polar solvent, the structure in which the organic binder holds the amine compound may change due to, for example, water vapor in the atmosphere, resulting in a problem of being unable to stably maintain carbon dioxide adsorption performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 119929 Summary of the Invention [Problem to be solved by the invention]

[0004] A primary object of the present invention is to provide an acid gas adsorption device that can maintain excellent acid gas adsorption capacity regardless of the operating environment. [Means for solving the problem]

[0005] [1] An acid gas adsorption device according to an embodiment of the present invention includes particles capable of adsorbing acid gases and an organic binder capable of binding the particles. The organic binder is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent. [2] The acidic gas adsorption device described in [1] above may have a surface that can come into contact with acidic gas. The particles and the organic binder are present on the surface. The surface has a three-dimensional network structure or a porous lamellar structure. [3] In the acidic gas adsorption device according to the above [1] or [2], the organic binder may contain at least water as a poor solvent. [4] The acidic gas adsorption device according to any one of [1] to [3] above may include a substrate and an acidic gas adsorption layer. The acidic gas adsorption layer is disposed on the surface of the substrate. The acidic gas adsorption layer contains the particles and the organic binder. [5] The acidic gas adsorption device according to any one of [1] to [3] above may include a molded body containing the particles and the organic binder. [6] The acidic gas adsorption device according to any one of [1] to [3] above may include an acidic gas adsorption layer, a dense layer, and a substrate, in this order. The acidic gas adsorption layer contains the particles and the organic binder. The dense layer is denser than the acidic gas adsorption layer. [7] In the acidic gas adsorption device according to any one of [1] to [6] above, the acidic gas may be carbon dioxide. [8] A method for manufacturing an acidic gas adsorption device according to another aspect of the present invention includes the steps of: dispersing particles capable of adsorbing acidic gases in a binder solution in which an organic binder that is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent is dissolved in an aprotic polar solvent; applying the binder solution in which the particles are dispersed to the surface of a substrate to form a precursor film; and replacing the aprotic polar solvent contained in the precursor film with a poor solvent for the organic binder to form an acidic gas adsorption layer containing the particles capable of adsorbing acidic gases and the organic binder. [9] A method for manufacturing an acidic gas adsorption device according to yet another aspect of the present invention includes the steps of: preparing a puddle by mixing particles capable of adsorbing acidic gases, an organic binder that is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent, and an aprotic polar solvent that can dissolve the organic binder and in which the particles are substantially insoluble; molding the puddle to prepare a precursor containing the particles capable of adsorbing acidic gases and the organic binder; and replacing the aprotic polar solvent contained in the precursor with a poor solvent for the organic binder to prepare a molded body containing the particles capable of adsorbing acidic gases and the organic binder.

[10] A method for manufacturing an acidic gas adsorption device according to yet another aspect of the present invention includes the steps of: dispersing a carrier in a binder solution in which an organic binder that is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent is dissolved in an aprotic polar solvent; applying the binder solution in which the carrier is dispersed to the surface of a substrate to form a precursor film; replacing the aprotic polar solvent contained in the precursor film with a poor solvent for the organic binder to form a carrier-containing film containing the carrier and the organic binder; and supporting an acidic gas adsorption compound on the carrier contained in the carrier-containing film to form an acidic gas adsorption layer containing particles composed of the acidic gas adsorption compound and the carrier and the organic binder. [Effects of the Invention]

[0006] According to an embodiment of the present invention, an acidic gas adsorption device that can maintain excellent acidic gas adsorption capacity regardless of the usage environment can be realized. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view of an acid gas adsorption device according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the acid gas adsorption apparatus of FIG. [Figure 3] FIG. 3 is a schematic perspective view of an acid gas adsorption device according to another embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram of an acid gas adsorption device according to yet another embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view of an acid gas adsorption device according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0009] A. Overview of the acid gas adsorption device FIG. 1 is a schematic perspective view of an acid gas adsorption apparatus according to one embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of the acid gas adsorption apparatus of FIG. 1; FIG. 3 is a schematic perspective view of an acid gas adsorption apparatus according to another embodiment of the present invention; and FIG. 4 is a schematic configuration diagram of an acid gas adsorption apparatus according to yet another embodiment of the present invention.

[0010] An acidic gas adsorption device according to one embodiment of the present invention is capable of separating (removing) acidic gas contained in a gas to be treated from the gas to be treated. The acidic gas adsorption device 100 includes particles capable of adsorbing acidic gas (hereinafter referred to as acidic gas adsorbent particles) and an organic binder. The acidic gas adsorbent particles are capable of adsorbing acidic gas. The organic binder is capable of binding the acidic gas adsorbent particles. The organic binder is soluble in aprotic polar solvents and substantially insoluble in protic polar solvents. That is, the organic binder is resistant (water-resistant) to water, which is a protic polar solvent. With this configuration, the organic binder is substantially insoluble in protic polar solvents and is water-resistant, so that swelling of the organic binder due to, for example, water vapor in the atmosphere can be suppressed. Therefore, volume expansion and / or a decrease in strength of the organic binder can be suppressed, and ultimately, changes in the structure in which the organic binder binds and holds the acidic gas adsorbent particles can be suppressed. As a result, excellent acidic gas adsorption ability can be maintained regardless of the usage environment. Such an acidic gas adsorption device can be manufactured by precipitating an organic binder by replacing an aprotic polar solvent in which the organic binder dissolves with a poor solvent such as water. Because the precipitated organic binder is insoluble in protic polar solvents (e.g., water or alcohols), an acidic gas adsorption device with acidic gas adsorption capacity that is not affected by protic polar solvents (i.e., an acidic gas adsorption device with excellent water resistance) can be realized with low energy and no heat treatment.

[0011] In one embodiment, the acidic gas adsorption device 100 has a surface that can come into contact with acidic gas. Acidic gas adsorbent particles and an organic binder are present on the surface that can come into contact with acidic gas. The surface has a three-dimensional network structure or a porous lamellar structure. Therefore, the acidic gas can be efficiently diffused from the surface that can come into contact with acidic gas toward the interior. In particular, since the organic binder is water-resistant, such a fine structure can be stably maintained on the surface that can come into contact with acidic gas regardless of the usage environment. The surface that can come into contact with acidic gas preferably has a three-dimensional network structure.

[0012] The three-dimensional network structure typically has a plurality of pores. Each of the plurality of pores typically has a substantially circular or elliptical cross section. The average pore size in the three-dimensional network structure is, for example, 0.1 μm to 10 μm, and preferably 0.5 μm to 5.0 μm. The average pore size is calculated, for example, by binarizing an SEM photograph taken at a magnification of 300 times of a cross section obtained by cutting the surface having the three-dimensional network structure in the thickness direction. The porosity of the three-dimensional network structure is, for example, 15% to 90%, preferably 40% to 80%, and more preferably 45% to 75%. The porosity can be measured by, for example, mercury intrusion porosimetry. The bulk density of the three-dimensional network structure is, for example, 0.05 g / cm 3 ~1.600g / cm 3 and preferably 0.2 g / cm 3 ~1.5g / cm 3 and more preferably 0.25 g / cm 3 ~1.3g / cm 3 is.

[0013] The porous lamellar structure typically includes a plurality of relatively large primary pores and a plurality of relatively small secondary pores. Each of the plurality of first pores typically has a substantially teardrop shape in the cross section. The length of the first pore is, for example, 1 to 30 times, and preferably 2 to 10 times, the width of the first pore (the dimension in the direction perpendicular to the length direction). The pore size (diameter) is calculated, for example, by binarizing an SEM photograph taken at 300x magnification of a cross section cut in the thickness direction of a surface having a porous lamellar structure. The average length of the plurality of primary pores is, for example, 10 μm to 1000 μm, and preferably 50 μm to 500 μm.The average width of the plurality of primary pores is, for example, 1 μm to 100 μm, and preferably 10 μm to 50 μm. Each of the second pores typically has a substantially circular or elliptical cross section. When the second pores have a substantially elliptical shape, the ratio of the major axis to the minor axis of the second pore is less than the lower limit of the ratio of the length to the width of the first pore. The average diameter of the plurality of second pores is, for example, 0.1 μm to 10 μm, and preferably 0.5 μm to 5 μm. The average length of the multiple first pores is, for example, 10 times or more, preferably 50 times or more, and for example, 1000 times or less, preferably 500 times or less, relative to the average diameter of the multiple second pores (average length of first pores / average diameter of second pores).

[0014] Examples of acidic gases to be adsorbed by the acidic gas adsorption device 100 include carbon dioxide (CO2), hydrogen sulfide, sulfur dioxide, nitrogen dioxide, dimethyl sulfide (DMS), and hydrogen chloride. In one embodiment, the acidic gas is carbon dioxide (CO2), and the gas fluid is a CO2-containing gas. The CO2-containing gas may contain nitrogen in addition to CO2. The CO2-containing gas is typically air (atmosphere). The CO2 concentration in the CO2-containing gas before being supplied to the acidic gas adsorption device is, for example, 100 ppm (volume basis) or more and 2% by volume or less.

[0015] A-1. Acid gas adsorption particles The acidic gas adsorbent particles are in a solid state at room temperature and normal pressure (23°C, 0.1 MPaA (absolute pressure)). The acidic gas adsorption device 100 typically contains a plurality of acidic gas adsorbent particles. The acidic gas adsorbent particles contained in the acidic gas adsorption device 100 may be primary particles or secondary particles formed by agglomeration of a plurality of primary particles.

[0016] In one embodiment, the acidic gas adsorbent particles include an acidic gas adsorbent compound and a carrier that supports the acidic gas adsorbent compound. However, the acidic gas adsorbent particles may be composed only of the acidic gas adsorbent compound without including a carrier. In other words, the acidic gas adsorbent particles may be composed only of an acidic gas adsorbent compound that is solid at room temperature and normal pressure.

[0017] When the acid gas is CO2, the acid gas adsorbing compound is a CO2 adsorbing compound. The CO2 adsorption compound may be any suitable compound capable of adsorbing and desorbing CO2. Examples of CO2 adsorption compounds include nitrogen-containing compounds; alkali compounds such as sodium hydroxide and potassium hydroxide; carbonates such as calcium carbonate and potassium carbonate; bicarbonates such as calcium bicarbonate and potassium bicarbonate; metal-organic frameworks (MOFs) such as MOF-74, MOF-200, and MOF-210; zeolites; activated carbon; and nitrogen-doped carbon. The CO2 adsorption compounds may be used alone or in combination.

[0018] Among CO2 adsorption compounds, nitrogen-containing compounds are preferred. More specifically, nitrogen-containing compounds include primary amines such as monoethanolamine and polyvinylamine; secondary amines such as diethanolamine, cyclic amines, and N-(3-aminopropyl)diethanolamine; tertiary amines such as methyldiethylamine and triethanolamine; ethyleneamine compounds such as tetraethylenepentamine; aminosilane coupling agents such as aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and polyethyleneimine-trimethoxysilane; organic polymers having primary and tertiary amino groups; organic monomers having primary and tertiary amino groups; piperazine compounds such as 1-(2-hydroxyethyl)piperazine; and organic / inorganic compounds having amino groups as substituents. The nitrogen-containing compounds can be used alone or in combination. Among nitrogen-containing compounds, organic monomers having primary and tertiary amino groups and organic polymers having primary and tertiary amino groups are preferred. Specific examples of organic monomers having a primary amino group to a tertiary amino group include ethyleneimine and styrene to which an amino group has been added. Specific examples of organic polymers having primary to tertiary amino groups include linear polyethyleneimine, branched polyethyleneimine, polyamidoamine, and polystyrene to which amino groups have been added. The weight-average molecular weight Mw (polystyrene equivalent) of the organic polymer is, for example, 1,000 or more, preferably 50,000 or more, and for example, 1,000,000 or less, preferably 300,000 or less.

[0019] In one embodiment, the acid gas adsorbing compound is substantially insoluble in protic polar solvents (typically water) and aprotic polar solvents. The water solubility of the acidic gas adsorption compound at 25°C is, for example, 0.1 g / 100 g-H2O or less, preferably 0.05 g / 100 g-H2O or less. If the water solubility of the acidic gas adsorption compound is equal to or less than the above upper limit, excellent water resistance can be stably imparted to the acidic gas adsorption device. The lower limit of the water solubility of the acidic gas adsorption compound at 25°C is typically 0.01 g / 100 g-H2O or more. The solubility of the acidic gas-adsorbing compound in an aprotic polar solvent at 25°C is, for example, 1 g / 100 g of aprotic polar solvent or less, preferably 0.5 g / 100 g of aprotic polar solvent or less. If the solubility of the acidic gas-adsorbing compound in an aprotic polar solvent is equal to or less than the above upper limit, dissolution of the acidic gas-adsorbing compound in an aprotic polar solvent can be suppressed during the manufacture of an acidic gas adsorption device. The lower limit of the solubility of the acidic gas-adsorbing compound in an aprotic polar solvent at 25°C is typically 0.01 g / 100 g of aprotic polar solvent or more.

[0020] The solubility parameter of the acidic gas-adsorbing compound at 25° C. is, for example, 7 or more, preferably 8 or more, and for example, 20 or less, preferably 15 or less. The solubility parameter can be calculated, for example, by the Hildebrand method (the same applies hereinafter).

[0021] Any suitable carrier capable of supporting the acidic gas adsorption compound can be used. The carrier is preferably a porous carrier. When the carrier is a porous carrier, mesopores can be formed on the surface that can come into contact with the acidic gas. Examples of porous carriers include metal-organic frameworks (MOFs) such as MOF-74, MOF-200, and MOF-210; activated carbon; nitrogen-doped carbon; porous silica; porous alumina; zeolite; carbon nanotubes; and polymers. The porous carriers can be used alone or in combination. Preferably, the porous carrier is made of a material different from that of the acidic gas adsorption compound. Among porous carriers, porous silica is more preferred.

[0022] The BET specific surface area of ​​the porous support is, for example, 50 m 2 / g or more, preferably 500m 2 / g or more. If the surface area of ​​the porous support is equal to or greater than the lower limit, the acidic gas adsorption compound can be stably supported, and the CO2 recovery rate can be improved. The upper limit of the BET specific surface area of ​​the porous support is typically 2000 m 2 / g or less.

[0023] Metallic materials may also be used from the viewpoint of thermal conductivity. Examples include steel materials such as carbon steel and alloy steel; and non-ferrous metals and their alloys such as copper, aluminum, and nickel. Metallic materials are not limited to porous shapes.

[0024] The acidic gas adsorbent particles are formed by any suitable combination of the above-mentioned acidic gas adsorbent compound and the above-mentioned carrier. Specific examples of the acidic gas adsorbent particles include amine-supported polymers, amine-supported MOFs, and amine-supported nitrogen-doped carbons.

[0025] The mass ratio of the acidic gas-adsorbing compound to the support (acidic gas-adsorbing compound / support) is, for example, 0.1 or more, preferably 1 or more, and for example, 5 or less, preferably 3 or less.

[0026] A-2. Organic binder The organic binder may be any suitable organic compound capable of binding acidic gas adsorbent particles. The organic binder is soluble in aprotic polar solvents and substantially insoluble in protic polar solvents. Examples of organic binders include fluoropolymers such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), ethylene tetrafluoroethylene copolymer (ETFE), and polyvinyl fluoride (PVF); and amorphous plastics such as polyethersulfone (PES), polysulfone, polyvinylidene chloride, polyimide, and polyvinyl chloride. The organic binders may be used alone or in combination. Among organic binders, preferred are organic binders for which at least water is a poor solvent (organic binders that are substantially insoluble in water), more preferred are fluoropolymers, and even more preferred are polyvinylidene fluoride. When the organic binder contains a fluoropolymer (polyvinylidene fluoride), it can impart excellent heat resistance and water resistance to the acidic gas adsorption device.

[0027] The weight average molecular weight Mw (polystyrene equivalent) of the organic binder is, for example, 10,000 or more, preferably 200,000 or more, and for example, 10,000,000 or less, preferably 1,000,000 or less.

[0028] The solubility of the organic binder in a protic polar solvent (typically water) at 25°C is, for example, 0.1 g / 100 g of protic polar solvent or less, preferably 0.05 g / 100 g of protic polar solvent or less. If the solubility of the organic binder in a protic polar solvent (typically water) is not more than the above upper limit, excellent water resistance can be stably imparted to the acid gas adsorption device. Note that the lower limit of the solubility of the organic binder in a protic polar solvent (typically water) at 25°C is typically 0.01 g / 100 g of protic polar solvent or more.

[0029] The solubility parameter of the organic binder at 25° C. is, for example, 9 or more, preferably 10 or more, and for example, 15 or less, preferably 13 or less.

[0030] B. Acid gas adsorption device comprising a substrate and an acid gas adsorption layer 1 and 2, in one embodiment, an acidic gas adsorption device 100 includes a substrate 11 and an acidic gas adsorption layer 12 containing the above-described acidic gas adsorbent particles and an organic binder. In the illustrated example, the acidic gas adsorption layer 12 is disposed on the surface of the substrate 11.

[0031] B-1. Base material The structure of the substrate 11 is not particularly limited, and examples thereof include a honeycomb structure, a filter structure such as a filter cloth, and a pellet structure. In the illustrated example, the substrate 11 is a honeycomb substrate 11a. The honeycomb substrate 11a and the acidic gas adsorption layer 12 form a honeycomb structure. The honeycomb substrate 11a has partition walls 13 that define a plurality of cells 14.

[0032] The cells 14 extend in the longitudinal direction (axial direction) of the honeycomb substrate 11a from the first end face E1 (inlet end face) to the second end face E2 (outlet end face) of the honeycomb substrate 11a (see FIG. 2). The cells 14 have any appropriate shape in a cross section perpendicular to the longitudinal direction of the honeycomb substrate 11a. Examples of the cross-sectional shape of the cells include a triangle, a square, a pentagon, a polygon with hexagons or more, a circle, and an ellipse. The cross-sectional shapes and sizes of the cells may all be the same, or at least some of them may be different. Among such cross-sectional shapes of the cells, a hexagon or a quadrangle is preferred, and a square, a rectangle, or a hexagon is more preferred.

[0033] The cell density (i.e., the number of cells 14 per unit area) in the cross section perpendicular to the longitudinal direction of the honeycomb substrate can be appropriately set depending on the purpose. For example, the cell density is 4 cells / cm 2 ~320 cells / cm 2 If the cell density is in this range, the strength and effective GSA (geometric surface area) of the honeycomb substrate can be sufficiently ensured.

[0034] The honeycomb substrate 11a may have any appropriate shape (overall shape). Examples of the shape of the honeycomb substrate include a cylindrical shape with a circular bottom, an elliptical cylindrical shape with an elliptical bottom, a rectangular prism with a polygonal bottom, and a cylindrical shape with an irregular bottom. The honeycomb substrate 11a in the illustrated example has a cylindrical shape. The outer diameter and length of the honeycomb substrate can be appropriately set depending on the purpose. Although not shown, the honeycomb substrate may have a hollow region at the center in a cross section perpendicular to the longitudinal direction.

[0035] The honeycomb substrate 11a typically includes outer walls 16 and partition walls 13 located inside the outer walls 16. In the illustrated example, the outer walls 16 and the partition walls 13 are integrally formed. However, the outer walls 16 and the partition walls 13 may be separate bodies.

[0036] In the illustrated example, the outer wall 16 has a cylindrical shape. The thickness of the outer wall 16 can be set arbitrarily and appropriately. The thickness of the outer wall 16 is, for example, 0.1 mm to 10 mm.

[0037] The partition walls 13 define a plurality of cells 14. More specifically, the partition walls 13 have first partition walls 13a and second partition walls 13b that are perpendicular to each other, and the first partition walls 13a and the second partition walls 13b define a plurality of cells 14. The cross-sectional shape of the cells 14 is substantially rectangular except for the portions where the first partition walls 13a and the second partition walls 13b contact the outer wall 16. The configuration of the partition walls is not limited to the above-described partition walls 13. The partition walls may have first partition walls extending in the radial direction and second partition walls extending in the circumferential direction, which define a plurality of cells.

[0038] The thickness of the partition walls 13 can be appropriately set depending on the application of the acidic gas adsorption device. The thickness of the partition walls 13 is typically thinner than the thickness of the outer walls 16. The thickness of the partition walls 13 is, for example, 0.03 mm to 0.6 mm. The thickness of the partition walls is measured by cross-sectional observation using, for example, an SEM (scanning electron microscope). When the thickness of the partition walls is in this range, the mechanical strength of the honeycomb substrate can be made sufficient, and the opening area (the total area of ​​the cells in the cross section) can be made sufficient.

[0039] The porosity of the partition walls 13 can be appropriately set depending on the purpose. The porosity of the partition walls 13 is, for example, 15% or more, preferably 20% or more, and for example, 70% or less, preferably 45% or less. The porosity can be measured by, for example, mercury intrusion porosimetry. The bulk density of the partition walls 13 can be appropriately set depending on the purpose. For example, the bulk density is 0.10 g / cm 3 or more, preferably 0.20 g / cm 3or more, for example, 0.60 g / cm 3 or less, preferably 0.50 g / cm 3 The bulk density can be measured by, for example, mercury intrusion porosimetry.

[0040] A representative example of a material for forming the partition walls 13 is ceramics. Examples of ceramics include silicon carbide, silicon-silicon carbide composite materials, cordierite, mullite, alumina, silicon nitride, spinel, silicon carbide-cordierite composite materials, lithium aluminum silicate, and aluminum titanate. The materials for forming the partition walls can be used alone or in combination. Among the materials for forming the partition walls, preferred examples include cordierite, alumina, mullite, silicon carbide, silicon-silicon carbide composite materials, and silicon nitride, and more preferred examples include cordierite.

[0041] B-2. Acid gas adsorption layer In one embodiment, the acidic gas adsorption layer 12 is formed on the surface of the partition wall 13. In the honeycomb substrate 11a, a gas flow path 15 is formed in a portion (typically the center portion) of the cross section of the cell 14 where the acidic gas adsorption layer 12 is not formed. The acidic gas adsorption layer 12 may be formed on the entire inner surface of the partition wall 13 (i.e., so as to surround the gas flow path 15) as in the illustrated example, or may be formed on a portion of the surface of the partition wall. When the acidic gas adsorption layer 12 is formed on the entire inner surface of the partition wall 13, the adsorption efficiency of the acidic gas (typically CO2) can be improved.

[0042] The gas flow channels 15 extend from a first end face E1 (inlet end face) to a second end face E2 (outlet end face) in the same manner as the cells 14. The cross-sectional shape of the gas flow channels 15 may be the same as that of the cells 14, preferably a hexagon or a quadrangle, and more preferably a square, rectangle, or hexagon. The cross-sectional shapes and sizes of the gas flow channels 15 may all be the same, or at least some may be different. Typically, the cell 14 (more specifically, the gas flow path 15) is supplied with a gas to be treated containing an acidic gas in an adsorption step described later, and is supplied with a desorbed gas in a desorption step described later.

[0043] The acidic gas adsorption layer 12 contains the above-described acidic gas adsorbent particles and the above-described organic binder. Therefore, by dissolving the organic binder contained in the acidic gas adsorption layer that has reached the end of its life with an aprotic polar solvent, the acidic gas adsorption layer can be easily removed and regenerated with low energy. The surface 12s of the acidic gas adsorption layer 12 opposite the partition wall 13 faces the gas flow path 15 and can come into contact with the acidic gas supplied in the adsorption process. Acidic gas adsorbent particles and an organic binder are present on the surface 12s. In other words, the surface 12s of the acidic gas adsorption layer 12 is the "surface that can come into contact with the acidic gas" described in Section A above, and preferably has the three-dimensional network structure or porous lamellar structure described above.

[0044] The acidic gas adsorption layer 12 may contain any suitable additive in addition to the acidic gas adsorbent particles and the organic binder. The total content of the acidic gas adsorbent particles and organic binder in the acidic gas adsorption layer 12 is, when the total of the acidic gas adsorbent particles, the organic binder, and the additive is taken as 100% by volume, for example, 30% by volume or more, preferably 50% by volume or more, and for example, 100% by volume or less, preferably 99% by volume or less. The volume percentage can be measured, for example, by microstructural observation or elemental analysis. When the entire acidic gas adsorption layer 12 including pores is taken as 100% by volume, the total content of the acidic gas adsorption particles and organic binder is, for example, 10% by volume or more, preferably 30% by volume or more, more preferably 40% by volume or more, even more preferably 50% by volume or more, and particularly preferably 60% by volume or more, and is, for example, 90% by volume or less, preferably 85% by volume or less.

[0045] The content of the acidic gas adsorbent particles in the acidic gas adsorption layer 12 is, for example, 5% by volume or more, preferably 30% by volume or more, when the total of the acidic gas adsorbent particles, organic binder, and additive is 100% by volume. If the content of the acidic gas adsorbent particles is equal to or more than the above-mentioned lower limit, the acidic gas adsorption performance of the acidic gas adsorption device can be sufficiently ensured. The upper limit of the content of the acidic gas adsorbent particles is typically 85% by volume or less. If the entire acidic gas adsorption layer 12 including pores is taken as 100% by volume, the content of the acidic gas adsorption particles is, for example, 9% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and for example, 30% by volume or less, preferably 25% by volume or less.

[0046] The content of the organic binder in the acidic gas adsorption layer 12 is, for example, 5% by volume or more, preferably 15% by volume or more, when the total of the acidic gas adsorption particles, the organic binder, and the additive is taken as 100% by volume. If the content of the organic binder is equal to or more than the lower limit, the acidic gas adsorption particles can be prevented from falling off from the acidic gas adsorption layer in the adsorption step and / or desorption step described below. The upper limit of the content of the organic binder is typically 70% by volume or less. If the entire acidic gas adsorption layer 12 including pores is taken as 100% by volume, the content of the organic binder is, for example, 1% by volume or more, preferably 5% by volume or more, and for example, 30% by volume or less, preferably 10% by volume or less.

[0047] The acidic gas adsorption layer 12 typically has interconnected pores. The porosity of the acidic gas adsorption layer 12 is, for example, 10% to 90%, preferably 10% to 60%, and more preferably 15% to 40%.

[0048] The thickness of the acidic gas adsorption layer 12 is not particularly limited, but is, for example, 10 μm or more, preferably 50 μm or more, and is, for example, 1000 μm or less, preferably 500 μm or less.

[0049] As shown in FIG. 5 , in another embodiment, the acidic gas adsorption device 100 further includes a dense layer 17 in addition to the substrate 11 and the acidic gas adsorption layer 12. The dense layer 17 is disposed between the substrate 11 and the acidic gas adsorption layer 12. In other words, the acidic gas adsorption device 100 includes the acidic gas adsorption layer 12, the dense layer 17, and the substrate 11 (typically, the partition wall 13), in this order. The dense layer 17 is configured to be denser than the acidic gas adsorption layer 12. The porosity of the dense layer 17 is smaller than the porosity of the acidic gas adsorption layer 12. When the dense layer is disposed between the substrate and the acidic gas adsorption layer, the adhesive strength of the acidic gas adsorption layer can be improved, allowing the acidic gas adsorption layer to be thicker. This can improve the adsorption capacity of the acidic gas adsorption device.

[0050] In the illustrated example, the dense layer 17 is disposed on the surface of the partition wall 13. The dense layer 17 may be formed on the entire inner surface of the partition wall 13 as in the illustrated example, or may be formed on a portion of the surface of the partition wall 13. The acidic gas adsorption layer 12 is disposed on the surface of the dense layer 17. The acidic gas adsorption layer 12 may be formed on the entire surface of the dense layer 17 as in the illustrated example, or may be formed on a portion of the surface of the dense layer 17.

[0051] The material of the dense layer 17 is not particularly limited as long as it is soluble in an aprotic solvent. Examples of the material of the dense layer 17 include the organic binders described above. The materials of the dense layer 17 can be used alone or in combination. Among the materials of the dense layer 17, the organic binders described above are preferred. The organic binder contained in the dense layer 17 and the organic binder contained in the acidic gas adsorption layer 12 may be the same or different from each other.

[0052] The thickness of the dense layer 17 is, for example, 10 to 1000 times, and preferably 100 to 500 times, the thickness of the acidic gas adsorption layer 12. The thickness of the dense layer 17 is not particularly limited, but is, for example, 0.1 μm or more, preferably 1 μm or more, and for example, 10 μm or less, preferably 5 μm or less. The thickness is calculated, for example, as the average value of layer thicknesses measured at three or more points on a cross-sectional SEM photograph.

[0053] B-3. ​​Acid gas adsorption device with pellet-shaped substrate 1 and 2 includes a honeycomb substrate 11a as the substrate 11, as described above, but the shape of the substrate 11 is not limited thereto. In one embodiment, the substrate 11 is a pellet-shaped substrate.

[0054] As shown in FIG. 4, a typical example of an acidic gas adsorption device including a pellet-shaped substrate is an acidic gas adsorption device including a plurality of adsorbent layers 31. The plurality of adsorbent layers 31 are stacked at intervals in the thickness direction. In the illustrated example, five adsorbent layers 31 are arranged in parallel, but the number of adsorbent layers 31 is not limited to this. The number of adsorbent layers 31 is, for example, 5 or more, preferably 10 or more, and more preferably 20 or more. The interval between adjacent adsorbent layers 31 among the plurality of adsorbent layers 31 is, for example, 0.5 cm or more and 1.5 cm or less.

[0055] Each of the plurality of adsorbent layers 31 includes a plurality of pellet structures 32 and a flexible fiber member 33. The plurality of pellet structures 32 are filled inside the flexible fiber member 33 having a hollow shape (bag shape). Each of the plurality of pellet structures 32 includes a pellet-shaped substrate and an acidic gas adsorption layer.

[0056] Although not shown, the average primary particle diameter of the pellet-shaped substrate is, for example, 60 μm or more and 1200 μm or less. The porosity range of the pellet-shaped substrate is the same as the porosity range of the partition walls described above, and the bulk density range of the pellet-shaped substrate is the same as the bulk density range of the partition walls described above. Examples of materials constituting the pellet-shaped substrate include ceramics similar to those constituting the partition walls. The acidic gas adsorption layer provided in the pellet structure 32 is formed on the outer peripheral surface of the pellet-shaped substrate. The acidic gas adsorption layer is explained in the same manner as the acidic gas adsorption layer 12 in Section B-2 above. The packing ratio of the pellet structures 32 in the adsorbent layer 31 may be any appropriate value.

[0057] The flexible fibrous member 33 allows gas to pass through and restricts the passage of the pellet structures. The flexible fibrous member 33 is typically formed in a hollow shape (bag shape) capable of accommodating a plurality of pellet structures 32. The flexible fibrous member 33 may be a woven fabric or a nonwoven fabric. Examples of materials for the flexible fibrous member 33 include organic fibers and natural fibers, and preferred examples include polyethylene terephthalate fibers, polyethylene fibers, and cellulose-based fibers. The thickness of the flexible fibrous member 33 is, for example, 25 μm or more and 500 μm or less.

[0058] The illustrated acidic gas adsorption apparatus 100 further includes a plurality of spacers 34. The spacers 34 are sandwiched between adjacent ones of the plurality of adsorbent layers 31. This ensures a stable spacing between adjacent adsorbent layers. In one embodiment, the plurality of adsorbent layers 31 and the plurality of spacers 34 are arranged in a generally zigzag shape when viewed from a direction perpendicular to the thickness direction of the adsorbent layer 31 (the depth direction of the paper in FIG. 4).

[0059] An example of an acid gas adsorption device 100 including such a pellet structure 32 is the gas separation unit described in International Publication No. 2014 / 170184, the entire disclosure of which is incorporated herein by reference.

[0060] B-4. Method for manufacturing an acidic gas adsorption device including a substrate and an acidic gas adsorption layer Next, a method for manufacturing the acidic gas adsorption device 100 including the substrate 11 and the acidic gas adsorption layer 12 will be described. A manufacturing method of an acidic gas adsorption device 100 having a substrate 11 and an acidic gas adsorption layer 12 includes the steps of: dispersing acidic gas adsorption particles in a binder solution; applying the binder solution in which the acidic gas adsorption particles are dispersed to the surface of the substrate 11; and replacing the aprotic polar solvent in the precursor film formed on the surface of the substrate 11 to form the acidic gas adsorption layer 12.

[0061] In the method for manufacturing such an acidic gas adsorption device 100, first, the organic binder described above is dissolved in an aprotic polar solvent to prepare a binder solution.

[0062] The aprotic polar solvent is capable of dissolving the organic binder, but is insoluble in the acidic gas adsorbent particles (more specifically, the acidic gas adsorbing compound). The solubility parameter distance between the organic binder and the aprotic polar solvent at 25°C is, for example, 3 or less, preferably 2 or less. If the solubility parameter distance between the organic binder and the aprotic polar solvent is equal to or less than the upper limit, the organic binder can be smoothly dissolved in the aprotic polar solvent. The lower limit of the solubility parameter distance between the organic binder and the aprotic polar solvent at 25°C is typically 0 or more. The solubility parameter distance can be calculated by the Hildebrand method. The solubility parameter distance between the acidic gas-adsorbent compound and the aprotic polar solvent at 25°C is, for example, 2 or more, preferably 3 or more, and more preferably 4 or more. If the solubility parameter distance between the acidic gas-adsorbent compound and the aprotic polar solvent is equal to or greater than the above-mentioned lower limit, the acidic gas-adsorbent compound can be prevented from dissolving in the aprotic polar solvent. The upper limit of the solubility parameter distance between the acidic gas-adsorbent compound and the aprotic polar solvent at 25°C is typically 10 or less.

[0063] Any suitable organic solvent can be used as the aprotic polar solvent. Examples of the aprotic polar solvent include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). The aprotic polar solvent can be used alone or in combination. Among the aprotic polar solvents, N-methyl-2-pyrrolidone (NMP) is preferred. When the aprotic polar solvent contains NMP, the organic binder (particularly PVDF) can be dissolved more smoothly, and the dissolution of the acidic gas adsorption compound can be stably suppressed.

[0064] Next, the above-mentioned acid gas adsorbent particles are added to and dispersed in the binder solution.

[0065] A solution of an organic binder in an aprotic polar solvent, in which acidic gas adsorbent particles are dispersed (particle-dispersed binder solution), is applied to the surface of the substrate 11 by any appropriate method.

[0066] The substrate 11 is typically produced separately by the following method. First, a binder and water or an organic solvent are added as needed to a material powder containing the above-mentioned ceramic powder, and the resulting mixture is kneaded to form a clay. The clay is then molded into a desired shape (typically by extrusion molding), dried, and fired as needed to produce the substrate 11 (typically a honeycomb-shaped substrate 11a or a pellet-shaped substrate). When firing, the firing is carried out at 1200°C to 1500°C, for example. The firing time is, for example, 1 hour or more and 20 hours or less.

[0067] The method for applying the particle-dispersed binder solution can be arbitrarily and appropriately selected depending on the shape of the substrate 11. In one embodiment, the substrate 11 (typically, a honeycomb-shaped substrate 11a or a pellet-shaped substrate) is immersed in the particle-dispersed binder solution.

[0068] The application method is not limited to the above-described immersion method. For example, when the substrate 11 is a honeycomb substrate 11a, the particle-dispersed binder solution may be circulated through the cells 14 of the honeycomb substrate 11a. This allows the particle-dispersed binder solution to be smoothly applied to the surfaces of the partition walls. The number of times the particle-dispersed binder solution is applied can be changed appropriately depending on the desired thickness of the acidic gas adsorption layer 12 .

[0069] As a result, the particle-dispersed binder solution is applied to the surface of the substrate 11 (typically, the surface of the partition walls 13 of the honeycomb substrate 11a or the outer peripheral surface of the pellet-shaped substrate), forming a precursor film. The precursor film contains the acidic gas adsorbent particles, the organic binder, and the aprotic polar solvent.

[0070] Next, the aprotic polar solvent contained in the precursor film is replaced with a poor solvent for the organic binder.

[0071] The poor solvent dissolves the organic binder less easily than the aprotic polar solvent (good solvent), and the organic binder is substantially insoluble in the poor solvent. The solubility parameter distance between the organic binder and the poor solvent at 25°C is typically greater than the solubility parameter distance between the organic binder and the aprotic polar solvent (good solvent). The solubility parameter distance between the organic binder and the poor solvent at 25°C is, for example, 2 or more, preferably 3 or more, and more preferably 4 or more.

[0072] Examples of poor solvents include protic polar solvents such as water, alcohols such as ethanol, butanol, and isopropyl alcohol (IPA); and fluorocarbons such as hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and hydrofluoroolefins (HFOs). The poor solvents can be used alone or in combination. Of the poor solvents, water is preferred.

[0073] Substitution of aprotic polar solvents results in membranes that are stable to protic solvents.

[0074] As a result, the above-mentioned acidic gas adsorption layer 12 is formed on the surface of the substrate 11 (typically, on the surface of the partition walls 13 of the honeycomb substrate 11a or on the outer peripheral surface of the pellet-shaped substrate). Thereafter, the acidic gas adsorption layer 12 is dried as necessary.

[0075] In this manner, a structure including the substrate 11 and the acidic gas adsorption layer 12 disposed on the surface of the substrate 11 is manufactured. More specifically, when the substrate 11 is a honeycomb substrate 11a, a honeycomb structure is manufactured that includes the honeycomb substrate 11a and the acidic gas adsorption layer 12 disposed on the surface of the partition wall 13. In other words, an acidic gas adsorption device 100 composed of a honeycomb structure is manufactured. When the substrate 11 is a pellet-shaped substrate, a pellet structure is produced that includes the pellet-shaped substrate and an acidic gas adsorption layer disposed on the peripheral surface of the pellet-shaped substrate. Such a pellet structure is suitably used for producing the acidic gas adsorption device shown in FIG.

[0076] Furthermore, the manufacturing method of an acidic gas adsorption device including the substrate 11 and the acidic gas adsorption layer 12 is not limited to the above-described embodiment. A manufacturing method of an acidic gas adsorption device according to another embodiment includes the steps of dispersing a carrier in a binder solution, applying the binder solution in which the carrier is dispersed to the surface of the substrate 11, replacing the aprotic polar solvent in the precursor film formed on the surface of the substrate 11 to form a carrier-containing film, and supporting an acidic gas adsorption compound on the carrier contained in the carrier-containing film to form the acidic gas adsorption layer 12.

[0077] In the method for manufacturing such an acidic gas adsorption device, first, a binder solution is prepared in the same manner as described above, and then the carrier is added to the binder solution and stirred. As a result, the carrier is dispersed in the binder solution, and a binder solution in which the carrier is dispersed (carrier-dispersed binder solution) is prepared.

[0078] Next, the carrier-dispersed binder solution is applied to the surface of the substrate 11 by the application method described above. As a result, the carrier-dispersed binder solution is applied to the surface of the substrate 11 (typically, the surface of the partition walls 13 of the honeycomb substrate 11a or the outer peripheral surface of the pellet-shaped substrate), forming a precursor film. The precursor film contains the carrier, the organic binder, and the aprotic polar solvent.

[0079] Next, the aprotic polar solvent contained in the precursor film is replaced with the poor solvent described above. As a result, a carrier-containing film is formed on the surface of the substrate 11 (typically, on the surface of the partition walls 13 of the honeycomb substrate 11a or on the outer surface of the pellet-shaped substrate). Thereafter, the carrier-containing film is dried as necessary. The carrier-containing film contains the carrier and the organic binder. The surface of the carrier-containing film preferably has the three-dimensional network structure or porous lamellar structure described above.

[0080] Next, the acidic gas adsorption compound is supported on the carrier contained in the carrier-containing membrane. The acidic gas adsorption compound used in this embodiment is preferably an acidic gas adsorption compound that is liquid at room temperature and normal pressure. More specifically, the acidic gas adsorption compound that is liquid at room temperature and normal pressure is applied to the carrier-containing membrane by the above-mentioned application method. As a result, the acidic gas adsorption compound is impregnated into the carrier of the carrier-containing membrane and supported thereon, forming acidic gas adsorption particles composed of the acidic gas adsorption compound and the carrier. That is, the acidic gas adsorption layer 12 is composed of acidic gas adsorption particles and an organic binder. In this manner, a structure including the substrate 11 and the acidic gas adsorption layer 12 disposed on the surface of the substrate 11 can be manufactured.

[0081] Furthermore, the acidic gas adsorption device 100 including the substrate 11, the dense layer 17, and the acidic gas adsorption layer 12 can be manufactured, for example, by the following method. The manufacturing method includes, for example, a step of applying a material solution for the dense layer 17 to the surface of the substrate 11 to form the dense layer 17; and a step of forming the acidic gas adsorption layer 12 on the surface of the dense layer 17.

[0082] In the manufacturing method of such an acidic gas adsorption device 100, first, the material of the dense layer 17 (typically, an organic binder) is dissolved in the aprotic polar solvent to prepare a material solution for the dense layer.

[0083] Next, the material solution for the dense layer is applied to the surface of the substrate 11 by the above-mentioned application method. The number of applications is appropriately changed depending on the desired thickness of the dense layer 17. Thereafter, the coating film is dried as necessary. As a result, a dense layer 17 is formed on the surface of the substrate 11 (typically, on the surface of the partition walls 13 of the honeycomb substrate 11a or on the outer circumferential surface of the pellet-shaped substrate).

[0084] Next, the acidic gas adsorption layer 12 is formed on the surface of the dense layer 17 in the same manner as in the above-mentioned manufacturing method. In this manner, a structure including the substrate 11, the dense layer 17 disposed on the surface of the substrate 11, and the acidic gas adsorption layer 12 disposed on the surface of the dense layer 17 can be manufactured.

[0085] C. Acid gas adsorption device equipped with molded body In another embodiment, as shown in Fig. 3, an acidic gas adsorption apparatus 100 includes a molded body 21 containing the above-described acidic gas adsorbent particles and an organic binder. The molded body 21 is integrally molded into a desired shape by any appropriate molding method (typically, extrusion molding).

[0086] In the illustrated example, the formed body 21 is a honeycomb formed body 21a. The honeycomb formed body 21a has a configuration similar to that of the above-described honeycomb substrate 11a, and can be described in the same manner as the above-described honeycomb substrate 11a. Specifically, the honeycomb formed body 21a has partition walls 13 that define a plurality of cells 14. The honeycomb formed body 21a may further have outer walls 16 in addition to the partition walls 13. In the honeycomb formed body 21a, the acidic gas adsorption layer 12 is not formed on the partition walls 13. Therefore, the entire internal space of the cells 14 functions as a gas flow path 15.

[0087] The partition walls 13 of the honeycomb molded body 21a contain the above-mentioned acidic gas adsorbent particles and the above-mentioned organic binder. The surfaces 13s of the partition walls 13 face the gas flow paths 15 and can come into contact with the acidic gas supplied in the adsorption process. The acidic gas adsorbent particles and the organic binder are present on the surfaces 13s. In other words, the surfaces 13s of the partition walls 13 are the "surfaces that can come into contact with the acidic gas" described in Section A above, and preferably have the above-mentioned three-dimensional network structure or porous lamellar structure.

[0088] The porosity of the partition walls 13 can be set appropriately depending on the purpose. The porosity of the partition walls 13 is, for example, 15% or more, preferably 20% or more, and for example, 70% or less, preferably 45% or less. The bulk density of the partition walls 13 can be appropriately set depending on the purpose. For example, the bulk density is 0.1 g / cm 3 or more, preferably 0.2 g / cm 3 or more, for example, 0.6 g / cm 3 or less, preferably 0.5 g / cm 3 The following is the result.

[0089] The formed body 21 (typically, the honeycomb formed body 21a) may contain any appropriate additive in addition to the acidic gas adsorbent particles and the organic binder. Examples of the additive include a pore-forming material and a surfactant, and a pore-forming material is preferred.

[0090] The total content of the acidic gas adsorbent particles and the organic binder in the compact 21 is, for example, 30% by volume or more, preferably 50% by volume or more, and for example, 100% by volume or less, preferably 99% by volume or less.

[0091] The content of the acidic gas adsorbent particles in the compact 21 is, for example, 5% by volume or more, preferably 30% by volume or more. When the content of the acidic gas adsorbent particles is equal to or more than the above-mentioned lower limit, the acidic gas adsorption performance of the acidic gas adsorption device can be sufficiently ensured. The upper limit of the content of the acidic gas adsorbent particles is typically 85% by volume or less.

[0092] The content of the organic binder in the compact 21 is, for example, 5% by volume or more, preferably 15% by volume or more. If the content of the organic binder is equal to or more than the lower limit, the acidic gas adsorbent particles can be prevented from falling off from the compact in the adsorption step and / or desorption step described below. The upper limit of the content of the organic binder is typically 70% by volume or less.

[0093] C-1. Acid gas adsorption device equipped with pellet compacts 3 includes a honeycomb molded body 21a as the molded body 21, as described above, but the shape of the molded body 21 is not limited thereto. In one embodiment, the molded body 21 is a pellet molded body.

[0094] As shown in FIG. 4, the acid gas adsorption device including the pellet compact can be described in the same manner as the acid gas adsorption device including the pellet structure, except that the pellet structure 32 is changed to the pellet compact 35.

[0095] The plurality of pellet compacts 35 are filled inside a hollow (bag-shaped) flexible fiber member 33. The average primary particle diameter of the pellet compacts is, for example, 60 μm or more and 1200 μm or less. The range of the porosity of the pellet compacts is the same as the range of the porosity of the partition walls described above, and the range of the bulk density of the pellet compacts is the same as the range of the bulk density of the partition walls described above.

[0096] The peripheral surface of the pellet-shaped compact 35 can come into contact with the acidic gas supplied in the adsorption step. Acidic gas adsorbent particles and an organic binder are present on the peripheral surface of the pellet-shaped compact 35. In other words, the peripheral surface of the pellet-shaped compact 35 is the "surface that can come into contact with the acidic gas" described in Section A above, and preferably has the three-dimensional network structure or porous lamellar structure described above.

[0097] C-2. Method for manufacturing an acid gas adsorption device equipped with a molded body Next, a method for manufacturing the acidic gas adsorption device 100 including the molded body 21 will be described. The manufacturing method of the acidic gas adsorption device 100 having the molded body 21 includes the steps of: mixing acidic gas adsorption particles, an organic binder, and an aprotic polar solvent to prepare a clay; molding the clay to prepare a precursor; and replacing the aprotic polar solvent in the precursor to form the molded body 21.

[0098] In the manufacturing method of the acidic gas adsorption device 100, first, the acidic gas adsorbent particles, the organic binder, and the aprotic polar solvent (good solvent) are mixed by any appropriate method to prepare a clay. At this time, an additive (typically a pore-forming material) is further added as necessary.

[0099] The respective addition ratios of the acidic gas adsorbent particles and the organic binder can be arbitrarily and appropriately adjusted, for example, so that the mass ratio of the organic binder to the acidic gas adsorbent particles falls within the above range.

[0100] The addition ratio of the acidic gas adsorbent particles is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, and for example, 99 parts by mass or less, preferably 85 parts by mass or less, per 100 parts by mass of the aprotic polar solvent. The addition ratio of the organic binder is, for example, 1 part by mass or more, preferably 15 parts by mass or more, and for example, 70 parts by mass or less, preferably 50 parts by mass or less, relative to 100 parts by mass of the aprotic polar solvent.

[0101] The temperature at which they are mixed is, for example, -10°C or higher, preferably 0°C or higher, and for example, 60°C or lower, preferably 30°C or lower.

[0102] In this way, a clay (molding raw material) is prepared. The clay is then molded into a desired shape by any suitable molding method (typically extrusion molding). This results in a precursor having a desired shape (typically a honeycomb or pellet shape). The precursor contains the acid gas adsorbent particles, the organic binder, and the aprotic polar solvent.

[0103] Next, the aprotic polar solvent contained in the precursor is replaced with the poor solvent. This results in the formation of the above-described molded body 21. Thereafter, the molded body 21 is dried as needed. The drying temperature is, for example, 25°C or higher and 200°C or lower. The drying time is, for example, 1 minute or higher and 10 hours or lower.

[0104] In this way, a molded body 21 having a desired shape is manufactured. More specifically, as shown in FIG. 3, when the formed body 21 is a honeycomb formed body 21a, an acidic gas adsorption device 100 constituted by the honeycomb formed body 21a is manufactured. When the compact 21 is a pellet compact, the acidic gas adsorption device shown in FIG. 4 can be manufactured using the pellet compact.

[0105] D. Operation of the Acid Gas Adsorption System 100 An acidic gas adsorption device 100 according to one embodiment can repeatedly perform an adsorption process in which acidic gas contained in the gas to be treated is adsorbed onto acidic gas adsorption particles; and a desorption process in which the acidic gas is desorbed from the acidic gas adsorption particles.

[0106] In the adsorption step, typically, a gas to be treated containing an acidic gas is supplied to an acidic gas adsorption device at a predetermined adsorption temperature, and the acidic gas comes into contact with the acidic gas adsorbent particles, whereby the acidic gas is adsorbed by the acidic gas adsorbent particles.

[0107] The temperature (adsorption temperature) of the acidic gas adsorption apparatus in the adsorption step is, for example, 0°C or higher, preferably 10°C or higher, and for example, 50°C or lower, preferably 40°C or lower. In one embodiment, the adsorption temperature is the same as the ambient temperature. The duration of the adsorption step (adsorption time) is, for example, 15 minutes or higher, preferably 30 minutes or higher, and for example, 3 hours or lower, preferably 2 hours or lower. When the adsorption temperature and / or adsorption time is within the above range, the acidic gas adsorbent particles can efficiently adsorb acidic gases.

[0108] The acidic gas recovery rate in the adsorption process (=100-(acidic gas concentration in the gas to be treated that has passed through the acidic gas adsorption device / acidic gas concentration in the gas to be treated before being supplied to the acidic gas adsorption device × 100)) is, for example, 60% or more, preferably 75% or more, more preferably 80% or more, and particularly preferably 90% or more, and is, for example, 100% or less.

[0109] In the desorption step, the acid gas adsorber is typically heated to a desorption temperature that exceeds the adsorption temperature. More specifically, in the desorption step, the acid gas adsorber is heated to the desorption temperature and then maintained at the desorption temperature for a predetermined desorption time.

[0110] In one embodiment, water vapor is supplied to the acidic gas adsorption device to raise the temperature of the acidic gas adsorption device to the desorption temperature. The temperature of the water vapor is, for example, 50°C or higher and 200°C or lower. Since the acidic gas adsorption device according to one embodiment includes an organic binder with excellent water resistance, water vapor can be used to raise the temperature.

[0111] The desorbed gas is then supplied to an acidic gas adsorption apparatus at the desorption temperature, and the desorbed acidic gas is recovered together with the desorbed gas. The gas recovered in the desorption process may be referred to as recovered gas. Examples of the desorbed gas include water vapor and the recovered gas previously recovered by the acidic gas adsorption apparatus. By using the recovered gas as the desorbed gas, the acidic gas concentration in the recovered gas can be improved. The temperature of the desorbed gas supplied to the acidic gas adsorption apparatus is, for example, 60°C or higher, preferably 90°C or higher, and, for example, 200°C or lower, preferably 160°C or lower. In the desorption step, the acidic gas can also be recovered without using the desorbed gas. For example, the desorbed acidic gas can be recovered by sucking it with a vacuum pump. Alternatively, the desorbed gas and the vacuum pump can be used in combination.

[0112] The temperature of the acidic gas adsorption apparatus in the desorption step (desorption temperature) is, for example, 70°C or higher, preferably 80°C or higher, and for example, 200°C or lower, preferably 110°C or lower. The desorption step is carried out for a time period (desorption time during which the acidic gas adsorption apparatus is maintained at the desorption temperature) of, for example, 1 minute or higher, preferably 5 minutes or higher, and for example, 1 hour or lower, preferably 30 minutes or lower. When the desorption temperature and / or desorption time are within the above ranges, oxidation degradation and volatilization of the acidic gas adsorbent particles can be suppressed.

[0113] As a result, the acidic gas adsorbed by the acidic gas adsorbent particles in the adsorption step can be desorbed from the acidic gas adsorbent particles, and the desorbed acidic gas can be recovered.

[0114] An acidic gas adsorption device according to one embodiment can perform a cycle of the adsorption step and the desorption step, for example, 10 or more times, preferably 30 or more times, more preferably 50 or more times, and even more preferably 100 or more times.

[0115] E. Recycling of organic binders After the adsorption step and the desorption step are performed (preferably after the cycle of the adsorption step and the desorption step is performed within the above range), the organic binder contained in the acidic gas adsorption device may be recovered and reused (recycled). Furthermore, the organic binder may be recovered after the acidic gas recovery rate in the adsorption step falls below the above lower limit. This allows for effective use of the organic binder in the acidic gas adsorption layer that has reached the end of its life.

[0116] When the acidic gas adsorption device 100 includes the substrate 11 and the acidic gas adsorption layer 12, the organic binder is recovered by bringing the above-described aprotic polar solvent into contact with the acidic gas adsorption layer 12. For example, when the substrate 11 is a honeycomb substrate 11a, the above-described aprotic polar solvent is circulated through the gas flow path 15 to bring the aprotic polar solvent into contact with the acidic gas adsorption layer 12. As a result, the organic binder contained in the acidic gas adsorption layer is dissolved in the aprotic polar solvent, and the acidic gas adsorbent particles are released from the substrate. The aprotic polar solvent from which the acidic gas adsorption layer has been removed contains acidic gas adsorbent particles and an organic binder. Therefore, after removing the acidic gas adsorbent particles from the aprotic polar solvent containing the acidic gas adsorbent particles and the organic binder by filtration or the like, a protic polar solvent (typically water) is added to the aprotic polar solvent containing the organic binder. This allows only the organic binder to be precipitated, allowing the organic binder to be reused.

[0117] Furthermore, when the acidic gas adsorption apparatus 100 includes the compact 21, the compact 21 is pulverized to recover the organic binder. Any appropriate method can be adopted as the pulverization method for the compact depending on the material of the compact. Examples of the pulverization method include a hammer mill, a roller mill, a jet mill, and a ball mill. As a result, a material powder is obtained. The material powder contains acidic gas adsorbent particles and an organic binder. Next, the material powder is added to the above-mentioned aprotic polar solvent and stirred. This dissolves the organic binder in the aprotic polar solvent. Thereafter, as described above, the acidic gas adsorbent particles are removed from the aprotic polar solvent containing the acidic gas adsorbent particles and the organic binder, and then a protic polar solvent is added to the filtrate to precipitate only the organic binder. This also allows the organic binder to be reused. [Example]

[0118] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0119] Example 1 A clay containing alumina, silica, and magnesia (i.e., cordierite) was extruded and then dried to prepare the honeycomb substrate shown in Figure 1. The honeycomb substrate had a cylindrical shape with a diameter of 28 mm and a length of 60 mm. The honeycomb substrate had partition walls that defined a plurality of cells and an outer peripheral wall that surrounded the partition walls. The cross-sectional shape of the cells was rectangular. The cell density in the honeycomb substrate was 62 cells / cm. 2 The thickness of the partition walls was 0.1 mm, and the porosity of the partition walls was 40%.

[0120] A binder solution with a concentration of 10% by volume was prepared by dissolving 10 parts by mass of polyvinylidene fluoride (PVDF, organic binder, weight-average molecular weight Mw 50,000, solubility in water at 25°C 0.03 g / 100 g-H2O, melting point 173°C, decomposition temperature 280°C) in 90 parts by mass of N-methyl-2-pyrrolidone (NMP, aprotic polar solvent).

[0121] Next, 10 parts by mass of an amine-supported polymer (average primary particle diameter 5 μm) whose main component is polyethyleneimine was added to the binder solution, and the amine-supported polymer was dispersed in the binder solution by rotation and revolution stirring. The sol particle diameter measured by dynamic light scattering was 20 μm.

[0122] Next, the binder solution in which the amine-supported polymer was dispersed was passed through the cells of the honeycomb substrate at room temperature and atmospheric pressure (23°C, 0.1 MPaA (absolute pressure)). As a result, the binder solution in which the amine-supported polymer was dispersed was applied to the surface of the partition walls of the honeycomb substrate, forming a precursor film containing the amine-supported polymer and PVDF. The thickness (wet thickness) of the precursor film was 200 μm.

[0123] Next, the honeycomb substrate with the precursor film formed thereon was immersed in water (a poor solvent for PVDF) for 10 minutes at room temperature and atmospheric pressure. This substituted the NMP contained in the precursor film with water, forming an acidic gas adsorption layer containing the amine-supported polymer and PVDF. The honeycomb substrate was then removed from the water, and the acidic gas adsorption layer was dried at 50°C for 120 minutes.

[0124] In this manner, an acidic gas adsorption device (carbon dioxide adsorption device) including a honeycomb substrate and an acidic gas adsorption layer (carbon dioxide adsorption layer) was manufactured. In the acidic gas adsorption layer, the content of the amine-supported polymer was 50% by volume, and the content of PVDF was 50% by volume. The surface shape of the acidic gas adsorption layer observed with a scanning electron microscope was a porous lamellar structure. The thickness of the acidic gas adsorption layer was 180 μm. The average pore diameter in the acidic gas adsorption layer was 5 μm.

[0125] <Example 2> 40 parts by mass of the amine-supported polymer (acidic gas adsorbent particles), 40 parts by mass of the PVDF, and 20 parts by mass of NMP were mixed to obtain a clay (molding raw material). The clay was then extruded into a honeycomb shape as shown in FIG. 3 to prepare a precursor.

[0126] Next, under normal temperature and pressure, the honeycomb-shaped precursor was immersed in water (a poor solvent for PVDF) for 10 minutes. As a result, the NMP contained in the precursor was replaced with water, and a honeycomb-shaped molded body containing an amine-supported polymer and PVDF was formed. Then, the honeycomb-shaped molded body was lifted out of the water, and the honeycomb-shaped molded body was dried at 50 °C for 120 minutes.

[0127] As described above, an acidic gas adsorption device (carbon dioxide adsorption device) composed of a honeycomb-shaped molded body was manufactured. The shape and size of the honeycomb-shaped molded body were the same as those of the honeycomb-shaped base material in Example 1. The cell density in the honeycomb-shaped molded body was 62 cells / cm 2 and the porosity of the partition wall was 30%. In the honeycomb-shaped molded body, the content ratio of the amine-supported polymer was 50% by volume, and the content ratio of PVDF was 50% by volume. The surface shape of the partition wall observed by a scanning electron microscope was a porous lamellar structure. The average pore diameter in the honeycomb-shaped molded body was 5 μm.

[0128] <CO2 adsorption and desorption evaluation> The acidic gas adsorption device (carbon dioxide adsorption device) obtained in each example was housed in a quartz tube reactor such that the extending direction of the cells was parallel to the vertical direction. Next, after purging the gas flow path at 100 °C in nitrogen, the acidic gas adsorption device was cooled to room temperature (23 °C). A mixed gas (0.04% by volume of CO2 in nitrogen) was flowed through the gas flow path of this acidic gas adsorption device at 25 °C and a flow rate of 2 m / s for 15 minutes. The CO2 concentration in the mixed gas passing through the gas flow path was measured, and the above-described CO2 recovery rate (%) was calculated. Thereafter, steam at 120 °C was flowed through the gas flow path of the acidic gas adsorption device at a flow rate of 2 m / s for 15 minutes, and the acidic gas adsorption device was heated to 100 °C (desorption temperature). Next, steam at 120 °C was flowed through the gas flow path of the acidic gas adsorption device at a flow rate of 2 m / s for 15 minutes to desorb (regenerate) CO2 from the CO2 adsorbent. One cycle was defined as the repetition of the adsorption and desorption of these CO2. This cycle was repeated 10 times. In the acidic gas adsorption apparatus of Example 1, the CO2 recovery rate in all cycles was 90% or more, and in the acidic gas adsorption apparatus of Example 2, the CO2 recovery rate in all cycles was 90% or more. [Industrial Applicability]

[0129] The method for regenerating an acid gas adsorption device according to an embodiment of the present invention is used to regenerate an acid gas adsorption device used for separating and recovering acid gases, and is particularly suitable for regenerating a carbon dioxide adsorption device used in a carbon dioxide capture, utilization, and storage (CCUS) cycle. [Explanation of symbols]

[0130] 11 Base material 11a Honeycomb substrate 12 Acid gas adsorption layer 17 Layer compacta 21 Molded body 21a Honeycomb molded body 100 Acid gas adsorption device

Claims

1. Particles having an acid gas adsorption ability; an organic binder capable of binding the particles together; The acid gas adsorption device, wherein the organic binder is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent.

2. a surface that can contact an acid gas, on which the particles and the organic binder are present; 2. The acid gas adsorption device according to claim 1, wherein the surface has a three-dimensional network structure or a porous lamellar structure.

3. The acidic gas adsorption device according to claim 1 , wherein the organic binder contains at least water as a poor solvent.

4. A substrate; an acidic gas adsorption layer disposed on a surface of the substrate and containing the particles and the organic binder;

5. The acid gas adsorption device according to claim 1 , comprising a molded body containing the particles and the organic binder.

6. an acidic gas adsorption layer containing the particles and the organic binder; a dense layer that is denser than the acidic gas adsorption layer; The acid gas adsorption device according to claim 2 , comprising:

7. 7. The acidic gas adsorption device according to claim 1, wherein the acidic gas is carbon dioxide.

8. a step of dispersing particles capable of adsorbing acidic gases in a binder solution in which an organic binder that is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent is dissolved in an aprotic polar solvent; a step of applying the binder solution in which the particles are dispersed onto a surface of a substrate to form a precursor film; and replacing the aprotic polar solvent contained in the precursor film with a poor solvent for the organic binder to form an acidic gas adsorption layer containing the particles and the organic binder.

9. a step of preparing a clay by mixing particles having an acid gas adsorption ability, an organic binder that is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent, and an aprotic polar solvent that can dissolve the organic binder and is substantially insoluble in the particles; forming the clay to prepare a precursor containing the particles and the organic binder; and a step of replacing the aprotic polar solvent contained in the precursor with a poor solvent for the organic binder to prepare a compact containing the particles and the organic binder.

10. a step of dispersing a carrier in a binder solution in which an organic binder that is soluble in an aprotic polar solvent and substantially insoluble in a protic polar solvent is dissolved in an aprotic polar solvent; a step of applying the binder solution in which the carrier is dispersed onto a surface of a substrate to form a precursor film; a step of substituting the aprotic polar solvent contained in the precursor film with a poor solvent for the organic binder to form a carrier-containing film containing the carrier and the organic binder; and supporting an acidic gas adsorption compound on the carrier contained in the carrier-containing film to form an acidic gas adsorption layer containing particles composed of the acidic gas adsorption compound and the carrier, and the organic binder.

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