Acidic gas adsorption device

Abstract

This invention provides an acidic gas adsorption device capable of stably maintaining excellent acidic gas adsorption performance. An acidic gas adsorption device according to an embodiment of the present invention is provided with an acidic gas adsorption unit that is in contact with an acidic gas flow path. The acidic gas adsorption unit includes an acidic gas adsorbent capable of adsorbing acidic gas, and a deterioration inhibitor. The solubility of the target acidic gas with respect to the deterioration inhibitor at 25°C is 0.1 mol / kg or more. The vapor pressure of the deterioration inhibitor at 25°C is 30 Pa or less.

Description

Acid Gas Adsorption Equipment

[0001] The present invention relates to an acid gas adsorption device.

[0002] In recent years, efforts have been made to separate and capture acidic gases contained in the atmosphere to reduce environmental impact. Acidic gases include carbon dioxide, 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, a carbon dioxide capture absorbent structure has been proposed (see, for example, Patent Document 1). The structure includes a honeycomb substrate having multiple partition walls, thereby forming multiple flow channels, and functional structural unit groups disposed in and on the partition walls. The carbon dioxide capture absorbent structure can capture carbon dioxide from a gas flowing through the absorbent structure and desorb the captured carbon dioxide under predetermined heating conditions. However, when the carbon dioxide capture absorbent structure described in Patent Document 1 is used to repeatedly adsorb and desorb carbon dioxide contained in the atmosphere, the carbon dioxide adsorption performance may gradually decrease due to the repeated heating treatments.

[0003] International Publication No. 2013 / 119929

[0004] A primary object of the present invention is to provide an acid gas adsorption device that can sufficiently maintain excellent acid gas adsorption performance.

[0005] [1] An acidic gas adsorption device according to an embodiment of the present invention includes an acidic gas adsorption unit. The acidic gas adsorption unit includes an acidic gas adsorbent and a degradation inhibitor. The acidic gas adsorbent is capable of adsorbing acidic gases. The solubility of the target acidic gas in the degradation inhibitor at 25°C is 0.1 mol / kg or more. The vapor pressure of the degradation inhibitor at 25°C is 30 Pa or less. [2] In the acidic gas adsorption device described in [1] above, the acidic gas adsorption unit may be an acidic gas adsorption layer disposed on the surface of a substrate. That is, the acidic gas adsorption device may further include a substrate supporting the acidic gas adsorption layer. [3] In the acidic gas adsorption device described in [2] above, the acidic gas adsorption layer may include a first layer disposed on the surface of the substrate and a second layer disposed on at least a portion of the surface of the first layer. The first layer includes the acidic gas adsorbent and has acidic gas adsorption ability. The second layer faces the acidic gas flow path and includes the degradation inhibitor. [4] In the acidic gas adsorption device described in [2] above, the acidic gas adsorption layer may have a single-layer structure. The acidic gas adsorption layer having a single-layer structure faces the acidic gas flow path and has acidic gas adsorption ability. [5] In the acidic gas adsorption device described in any of [1] to [4] above, the acidic gas adsorption section may further include a porous carrier. The porous carrier supports the acidic gas adsorbent. [6] In the acidic gas adsorption device described in any of [1] to [5] above, the acidic gas may be carbon dioxide.

[0006] According to an embodiment of the present invention, an acidic gas adsorption device that can sufficiently maintain excellent acidic gas adsorption performance can be realized.

[0007] Fig. 1 is a schematic perspective view of an acidic gas adsorption apparatus according to one embodiment of the present invention. Fig. 2 is a schematic cross-sectional view of the acidic gas adsorption apparatus of Fig. 1. Fig. 3 is a schematic cross-sectional view of one embodiment of an acidic gas adsorption section included in the acidic gas adsorption apparatus of Fig. 2. Fig. 4 is a schematic cross-sectional view of another embodiment of an acidic gas adsorption section included in the acidic gas adsorption apparatus of Fig. 2.

[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 Acidic Gas Adsorption Apparatus FIG. 1 is a schematic perspective view of an acidic gas adsorption apparatus according to one embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of the acidic gas adsorption apparatus of FIG. 1. The illustrated acidic gas adsorption apparatus 100 includes an acidic gas adsorption unit 2. The acidic gas adsorption unit 2 faces an acidic gas flow path 14. In other words, the acidic gas adsorption unit 2 is in contact with the acidic gas flow path 14. The acidic gas adsorption unit 2 includes an acidic gas adsorbent and a degradation inhibitor. The acidic gas adsorption unit 2 is typically an acidic gas adsorption layer disposed on the surface of a substrate 1. The acidic gas adsorption layer 2 may have a multilayer structure including multiple layers (see FIG. 3) or a single-layer structure (see FIG. 4). The acidic gas adsorbent is capable of adsorbing acidic gases. The solubility of the target acidic gas in the degradation inhibitor at 25°C is 0.1 mol / kg or more. The vapor pressure (saturated vapor pressure) of the degradation inhibitor at 25°C is 30 Pa or less. According to this configuration, since the deterioration inhibitor having the above-mentioned vapor pressure is contained in the acidic gas adsorption section, volatilization of the acidic gas adsorbent in the desorption process described below and / or detachment of the acidic gas adsorbent due to contact with a fluid (hereinafter sometimes referred to as "wear") can be suppressed. Furthermore, since the deterioration inhibitor has the above-mentioned solubility of acidic gases, even if the acidic gas adsorption section contains the deterioration inhibitor, the acidic gas can be sufficiently dissolved in the deterioration inhibitor and can stably contact the acidic gas adsorbent. Therefore, deterioration of the acidic gas adsorption performance of the acidic gas adsorption device can be suppressed, and excellent acidic gas adsorption performance can be sufficiently maintained. This allows for a longer life of the acidic gas adsorption device.

[0010] The solubility of acidic gases in the deterioration inhibitor at 25°C is 0.1 mol / kg or more, preferably 0.2 mol / kg or more, more preferably 0.4 mol / kg or more, and even more preferably 1.5 mol / kg or more. When the deterioration inhibitor has such an acidic gas solubility, an excellent adsorption rate can be achieved without interfering with contact between the acidic gas and the acidic gas adsorbent. This can improve the acidic gas adsorption performance of the acidic gas adsorption device. Meanwhile, the higher the solubility of acidic gases in the deterioration inhibitor at 25°C, the more preferable. The solubility of acidic gases in the deterioration inhibitor at 25°C is, for example, 20.0 mol / kg or less, or, for example, 15.0 mol / kg or less, or, for example, 8.0 mol / kg or less. The solubility of acidic gases in the deterioration inhibitor is measured, for example, by a volumetric method or a gravimetric method that measures the amount of dissolved gas.

[0011] The vapor pressure (saturated vapor pressure) of the deterioration inhibitor is typically lower than the vapor pressure (saturated vapor pressure) of the acidic gas adsorbent. In other words, the deterioration inhibitor is less likely to volatilize than the acidic gas adsorbent. The vapor pressure of the deterioration inhibitor at 25°C is 30 Pa or less, preferably 10 Pa or less, and more preferably 5 Pa or less. When the deterioration inhibitor has such a vapor pressure, the volatilization and / or wear of the acidic gas adsorbent can be sufficiently suppressed. Therefore, the life of the acidic gas adsorption device can be stably extended. On the other hand, the lower the vapor pressure of the deterioration inhibitor at 25°C, the more preferable. The vapor pressure of the deterioration inhibitor at 25°C is typically 0 Pa or more. The vapor pressure of the deterioration inhibitor at 25°C is measured, for example, using any appropriate manometer (vapor pressure meter), more specifically, by a gas flow method.

[0012] The vapor pressure of the acidic gas adsorbent at 25°C is, for example, 30 Pa to 10,000 Pa, and preferably 35 Pa to 5,000 Pa. The difference between the vapor pressure of the acidic gas adsorbent and the vapor pressure of the deterioration-inhibiting material at 25°C (= vapor pressure of acidic gas adsorbent - vapor pressure of deterioration-inhibiting material) is, for example, 0.1 Pa to 9,000 Pa, and preferably 1.0 Pa to 4,000 Pa. If the vapor pressure difference between the acidic gas adsorbent and the deterioration-inhibiting material is within this range, volatilization and / or wear of the acidic gas adsorbent can be sufficiently suppressed.

[0013] The acidic gas adsorbent can be arbitrarily and appropriately selected depending on the acidic gas to be adsorbed by the acidic gas adsorption device. ２ ), hydrogen sulfide, sulfur dioxide, nitrogen dioxide, dimethyl sulfide (DMS), and hydrogen chloride. In one embodiment, the acid gas is carbon dioxide (CO ２ ) and the gas to be treated as a fluid is a carbon dioxide-containing gas. The carbon dioxide-containing gas may contain nitrogen in addition to carbon dioxide. The carbon dioxide-containing gas is typically air (atmosphere). Below, a detailed description will be given of the case where the acidic gas is carbon dioxide.

[0014] When the acid gas is carbon dioxide, the acid gas adsorbent is a carbon dioxide adsorbent. Any suitable compound capable of adsorbing and desorbing carbon dioxide can be used as the carbon dioxide adsorbent. Examples of the carbon dioxide adsorbent include nitrogen-containing compounds.

[0015] The nitrogen-containing compound may be in a liquid state or a solid state at room temperature and normal pressure (23°C, 0.1 MPaA (absolute pressure)). More specific examples of the nitrogen-containing compound 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-aminopropyl-trimethoxysilane, 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 to which an amino group is attached as a substituent. The carbon dioxide adsorbents may be used alone or in combination. Among such carbon dioxide adsorbents, a carbon dioxide adsorbent that is in a liquid state at room temperature and normal pressure (23°C, 0.1 MPaA (absolute pressure)) is preferred, an organic polymer having a primary amino group to a tertiary amino group is more preferred, and polyethyleneimine is even more preferred.

[0016] The content of the acidic gas adsorbent in the acidic gas adsorption layer 2 is, for example, 5% by mass to 70% by mass, and preferably 10% by mass to 30% by mass.

[0017] Any appropriate compound having the above-described solubility and vapor pressure can be used as the deterioration inhibitor. The deterioration inhibitor is typically in a liquid state at room temperature and normal pressure (23°C, 0.1 MPaA (absolute pressure)). The deterioration inhibitor may have acid gas adsorption ability, or may not have substantially acid gas adsorption ability. Examples of deterioration inhibitors include ionic liquids and deep eutectic solvents. These deterioration inhibitors can be used alone or in combination.

[0018] Ionic liquids are liquid "salts" composed only of ions (anions and cations). Examples of cations in ionic liquids include ammonium-based ions, phosphonium-based ions, sulfonium salts, and inorganic ions. In one embodiment, the cation in the ionic liquid is an ammonium-based cation. Examples of ammonium-based cations include imidazolium salts, pyridinium salts, pyrrolidinium, piperidinium, aliphatic ammonium, and guanidinium. Of these ammonium-based cations, aliphatic ammonium and guanidinium are preferred. Examples of aliphatic ammonium include amino-group-containing aliphatic ammonium such as 2,2'-diaminodiethylammonium (DETAH). Examples of guanidinium include tetraalkylguanidinium such as 1,1,3,3-tetramethylguanidinium (TMGH). Examples of anions of ionic liquids include halogen-based anions such as bromide and triflate, boron-based anions such as tetraphenylborate, phosphorus-based anions such as hexafluorophosphate, sulfur-based anions such as alkylsulfonates, phenoxide (PhO), and imidazolate (Im). Ionic liquids can be used alone or in combination.

[0019] Deep eutectic solvents typically contain a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA). Examples of hydrogen bond donors (HBDs) include carboxylic acid-containing organic compounds such as decanoic acid; ester-containing organic compounds such as phenyl salicylate; alcohols such as decanol, ethylene glycol (EG), aminopropanol (AP), and menthol; phenols such as thymol; ketone-containing organic compounds such as camphor; and vanilloids such as vanillin. HBDs can be used alone or in combination. Examples of hydrogen bond acceptors (HBAs) include ammonium salts having a halogen or hydroxy anion, such as tetra-n-octylammonium bromide, 1-methylimidazolium chloride (HMIM-Cl), and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU); amine compound salts having a halogen or hydroxy anion, such as triethylenetetramine chloride; monocyclic monoterpenoids, such as carvone; and carboxylic acid-containing organic compounds, such as lauric acid. HBAs can be used alone or in combination. HBD and HBA can be mixed in any appropriate ratio to form a deep eutectic solvent. These deep eutectic solvents can be used alone or in combination.

[0020] Among such degradation inhibitors, preferred examples of the ionic liquid include imidazolium salts as the cation and halogen-based compounds such as triflate as the anion, or deep eutectic solvents include carboxylic acid-containing organic compounds such as decanoic acid as the hydrogen bond donor (HBD) and ammonium salts having a halogen or hydroxy anion such as tetra-n-octylammonium bromide as the hydrogen bond acceptor (HBA). Preferred examples of the combination of cation and anion in the ionic liquid include a combination of guanidinium and phenoxide, and a combination of aliphatic ammonium and imidazolate, more preferably a combination of amino group-containing aliphatic ammonium and imidazolate, and even more preferably a combination of DETAH and imidazolate. Furthermore, preferred combinations of HBA and HBD in deep eutectic solvents include combinations of an ammonium salt having a halogen or hydroxy anion with an alcohol, and combinations of a vanilloid with a monocyclic monoterpenoid, more preferred combinations include combinations of an ammonium salt having a halogen or hydroxy anion with an alcohol, and even more preferred combinations include combinations of HMIM-Cl with AP and combinations of DBU with EG.

[0021] The content of the deterioration inhibitor in the acidic gas adsorption layer is, for example, 0.1 to 70 parts by mass, and preferably 5 to 30 parts by mass, relative to 1 part by mass of the acidic gas adsorbent. When the content of the deterioration inhibitor is within this range, the acidic gas adsorption performance of the acidic gas adsorption device can be sufficiently maintained over a long period of time.

[0022] In one embodiment, the acidic gas adsorption layer 2 further includes a porous carrier in addition to the above-described acidic gas adsorbent and deterioration-suppressing material. The porous carrier supports at least the acidic gas adsorbent. When the acidic gas adsorbent layer includes a porous carrier, it is possible to prevent the acidic gas adsorbent from falling off from the acidic gas adsorbent layer during the adsorption step and / or desorption step.

[0023] The porous support can form mesopores in the acidic gas adsorbent layer. Examples of the porous support include metal-organic frameworks (MOFs) such as MOF-74, MOF-200, and MOF-210; activated carbon; nitrogen-doped carbon; mesoporous silica; mesoporous alumina; zeolites; carbon nanotubes; and fluoride resins such as polyvinylidene fluoride (PVDF). Of these, metal-organic frameworks (MOFs), activated carbon, PVDF, zeolites, mesoporous silica, and mesoporous alumina are preferred. The porous supports may be used alone or in combination.

[0024] The BET specific surface area of ​​the porous carrier is, for example, 50 m ２ / g or more, preferably 500m ２ If the porous carrier has such a surface area, it can stably support the acidic gas adsorbent, and the adsorption efficiency of the acidic gas can be improved. The upper limit of the BET specific surface area of ​​the porous carrier is typically 2000 m ２ / g or less.

[0025] When the acidic gas adsorbent layer contains a porous carrier, the content of the porous carrier in the acidic gas adsorbent layer is, for example, 0.1 to 10 parts by mass, and preferably 0.5 to 2.0 parts by mass, per 1 part by mass of the acidic gas adsorbent. When the content of the porous carrier is in this range, the acidic gas adsorbent can be supported more stably.

[0026] The acidic gas adsorption layer 2 may further contain any appropriate additive. Examples of the additive include an organic binder, an inorganic binder, a surfactant, and a plasticizer. The content of the additive may be adjusted arbitrarily and appropriately.

[0027] The following describes a specific configuration of the acidic gas adsorption device 100. In one embodiment, the acidic gas adsorption device 100 further includes a substrate 1 that supports the acidic gas adsorption layer 2.

[0028] B. Substrate The structure of the substrate 1 is not particularly limited, and examples thereof include a honeycomb structure, a filter structure such as a filter cloth, a pellet structure, etc. The acidic gas adsorption layer 2 is not particularly limited as long as it is disposed on the surface of the substrate 1.

[0029] In one embodiment, the substrate 1 is a honeycomb substrate 1a. The honeycomb substrate 1a has partition walls 12 that define a plurality of cells 13. The cells 13 extend in the longitudinal direction (axial direction) of the honeycomb substrate 1a from a first end face E1 (inlet end face) to a second end face E2 (outlet end face) of the honeycomb substrate 1a (see FIG. 2). The cells 13 have any appropriate shape in a cross section perpendicular to the longitudinal direction of the honeycomb substrate 1a. Examples of the cross-sectional shape of the cells include a triangle, a square, a pentagon, a polygon having 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 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.

[0030] The cell density (i.e., the number of cells 13 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.

[0031] The honeycomb substrate 1a 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 cylinder with an elliptical bottom, a rectangular pillar with a polygonal bottom, and a pillar with an irregular bottom. The honeycomb substrate 1a shown in the figure has a rectangular pillar 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. Furthermore, the honeycomb substrate 1a may be divided into multiple sections in the longitudinal direction and / or the direction perpendicular to the longitudinal direction.

[0032] The honeycomb substrate 1a typically includes outer walls 11 and partition walls 12 located inside the outer walls 11. In the illustrated example, the outer walls 11 and the partition walls 12 are integrally formed. However, the outer walls 11 and the partition walls 12 may be separate bodies.

[0033] In the illustrated example, the outer wall 11 has a rectangular cylindrical shape. The thickness of the outer wall 11 can be set arbitrarily and appropriately. The thickness of the outer wall 11 is, for example, 0.1 mm to 10 mm.

[0034] The partition walls 12 define a plurality of cells 13. More specifically, the partition walls 12 include first partition walls 12a and second partition walls 12b that are perpendicular to each other, and the first partition walls 12a and the second partition walls 12b define the plurality of cells 13. The cross-sectional shape of the cells 13 is substantially rectangular. Note that the configuration of the partition walls is not limited to the above-described partition walls 12. The partition walls may include first partition walls extending in the radial direction and second partition walls extending in the circumferential direction, which define the plurality of cells.

[0035] The thickness of the partition walls 12 can be appropriately set depending on the application of the acidic gas adsorption device. The thickness of the partition walls 12 is typically thinner than the thickness of the outer walls 11. The thickness of the partition walls 12 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, a scanning electron microscope (SEM). When the thickness of the partition walls is in this range, the mechanical strength of the honeycomb substrate can be sufficiently ensured, and the opening area (the total area of ​​the cells in the cross section) can be sufficiently ensured.

[0036] The porosity of the partition walls 12 can be set appropriately depending on the purpose. The porosity of the partition walls 12 is, for example, 15% to 70%, and preferably 20% to 45%. The porosity is measured by, for example, mercury intrusion porosimetry. The bulk density of the partition walls 12 can be set appropriately depending on the purpose. The bulk density is, for example, 0.10 g / cm ３ ~0.60 g / cm ３ and preferably 0.20 g / cm ３ ~0.50 g / cm ３ The bulk density is measured by, for example, mercury intrusion porosimetry.

[0037] A representative example of a material for forming the partition walls 12 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 silicon carbide and silicon-silicon carbide composite materials.

[0038] Such a honeycomb-shaped substrate 1a is typically produced 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 honeycomb-shaped substrate 1a. When firing, the firing is performed at, for example, 1200°C to 1500°C. The firing time is, for example, 1 hour to 20 hours.

[0039] If necessary, any appropriate surface treatment layer (for example, a dense layer) may be provided on the surface of the substrate 1 on which the acidic gas adsorption layer 2 is disposed (for example, the surface of the partition wall 12).

[0040] C. Acidic Gas Adsorption Layer In the illustrated example, the acidic gas adsorption layer 2 is formed on the surface of the partition wall 12. The thickness of the acidic gas adsorption layer 2 is not particularly limited. The thickness of the acidic gas adsorption layer 2 is, for example, 10 μm to 1000 μm, and preferably 50 μm to 500 μm.

[0041] In the acidic gas adsorption device 100, the acidic gas flow path 14 is formed in a portion (typically the center) of the cross section of the cell 13 where the acidic gas adsorption layer 2 is not formed. The acidic gas adsorption layer 2 may be formed on the entire inner surface of the partition wall 12 (i.e., so as to surround the acidic gas flow path 14) 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 2 is formed on the entire inner surface of the partition wall 12, the adsorption efficiency of the acidic gas (typically carbon dioxide) can be improved.

[0042] Like the cells 13, the acidic gas flow paths 14 extend from a first end face E1 (inlet end face) to a second end face E2 (outlet end face). The extension direction of the acidic gas flow paths 14 and the fluid passage direction are typically parallel to each other. The cross-sectional shape of the acidic gas flow paths 14 may be the same as that of the cells 13 described above, preferably a hexagon or a quadrangle, and more preferably a square, a rectangle, or a hexagon. The cross-sectional shapes and sizes of the acidic gas flow paths 14 may all be the same, or at least some may be different. Typically, the cells 13 (more specifically, the acidic gas flow paths 14) are supplied with a gas to be treated containing an acidic gas in an adsorption step described below, and with a desorbed gas in a desorption step described below.

[0043] C-1. Acidic Gas Adsorption Layer Having a Multilayer Structure As shown in FIG. 3, the acidic gas adsorption layer 2 may have a multilayer structure including multiple layers. In the illustrated example, the acidic gas adsorption layer 2 includes a first layer 2a and a second layer 2b. The first layer 2a is disposed on the surface of the substrate 1 (typically, the partition walls 12 of the honeycomb substrate 1a). The first layer 2a contains the above-described acidic gas adsorbent 21. The first layer 2a has acidic gas adsorption ability. The second layer 2b is disposed on at least a portion of the surface of the first layer 2a and faces the acidic gas flow path 14. The second layer 2b contains the above-described deterioration suppression material 22. If the acidic gas adsorption layer has such a multilayer structure, the second layer can sufficiently suppress volatilization and / or wear of the acidic gas adsorbent contained in the first layer. Furthermore, because the solubility of the acid gas in the deterioration-suppressing material contained in the second layer is suitably adjusted, the acid gas can pass through the second layer to reach the first layer and can stably contact the acid gas adsorbent contained in the first layer, thereby suppressing deterioration of the acid gas adsorption performance of the acid gas adsorption device and allowing excellent acid gas adsorption performance to be sufficiently maintained.

[0044] The content of the acidic gas adsorbent 21 in the first layer 2a is, for example, 5% by mass to 70% by mass, and preferably 10% by mass to 30% by mass.

[0045] In one embodiment, the first layer 2 a contains the porous carrier 23 at the above-mentioned content ratio in addition to the acidic gas adsorbent 21. In this case, the acidic gas adsorbent 21 is supported on the porous carrier 23 in the first layer 2 a.

[0046] The thickness of the first layer 2a is, for example, 10 μm to 1000 μm, and preferably 50 μm to 500 μm. If the thickness of the first layer is in this range, excellent acid gas adsorption performance can be stably imparted to the acid gas adsorption device.

[0047] The second layer 2b is typically laminated on the first layer 2a. The second layer 2b is located on the opposite side of the first layer 2a from the substrate 1. The second layer 2b may be formed on the entire surface of the first layer 2a, or may be formed on only a portion of the surface of the first layer 2a. The second layer 2b preferably covers the entire first layer 2a.

[0048] The content of the deterioration suppressing material 22 in the second layer 2b is, for example, 0.001% by mass to 100% by mass, and preferably 0.5% by mass to 5.0% by mass. The thickness of the second layer 2b is typically thinner than the thickness of the first layer 2a. The thickness of the second layer 2b is, for example, 0.01 μm to 500 μm, and preferably 1.0 μm to 100 μm. When the thickness of the second layer is within this range, volatilization and / or wear of the acid gas adsorbent can be stably suppressed.

[0049] The acidic gas adsorption layer 2 including the first layer 2a and the second layer 2b is typically produced by the following method. First, if necessary, the porous carrier is dispersed in any appropriate dispersion medium to prepare a carrier dispersion. Next, the carrier dispersion is applied to the surface of the substrate by any appropriate application method. Then, if necessary, the coating is dried to form a carrier-containing membrane. Next, the acidic gas adsorbent is dissolved in any appropriate solvent to prepare an adsorbent solution. Then, the adsorbent solution is applied to the surface of the substrate or the carrier-containing membrane by any appropriate application method. When the adsorbent solution is applied to the surface of the carrier-containing membrane, the adsorbent solution is impregnated into the carrier-containing membrane. Then, if necessary, it is dried to form a first layer containing the acidic gas adsorbent and the porous carrier. When the adsorbent solution is applied to the surface of the substrate, the coating is dried as necessary to form a first layer containing the acidic gas adsorbent. Next, the deterioration inhibitor is applied to the surface of the first layer by any appropriate application method. Thereafter, if necessary, the coating film on the first layer is dried to form a second layer containing the deterioration suppressing material. In this manner, the acidic gas adsorption layer 2 including the first layer 2 a and the second layer 2 b is produced.

[0050] C-2. Acidic Gas Adsorption Layer Having a Single-Layer Structure In another embodiment, as shown in FIG. 4, the acidic gas adsorption layer 2 has a single-layer structure. The acidic gas adsorption layer 2 having a single-layer structure faces the acidic gas flow path 14 and has the ability to adsorb acidic gas. The acidic gas adsorption layer 2 contains the acidic gas adsorbent 21 and the deterioration-suppressing material 22 in the above-described content ratios. In the acidic gas adsorption layer 2 having a single-layer structure, the acidic gas adsorbent 21 and the deterioration-suppressing material 22 are dispersed. Even when the acidic gas adsorption layer has such a single-layer structure, it is possible to suppress deterioration of the acidic gas adsorption performance of the acidic gas adsorption device and to stably maintain excellent acidic gas adsorption performance.

[0051] In one embodiment, the acidic gas adsorption layer 2 contains the porous carrier 23 in the above-described content ratio in addition to the acidic gas adsorbent 21 and the deterioration suppression material 22. In this case, each of the acidic gas adsorbent 21 and the deterioration suppression material 22 is supported on the porous carrier 23 in the acidic gas adsorption layer 2.

[0052] The acidic gas adsorption layer 2 having a single-layer structure is typically prepared by the following method. First, if necessary, the porous carrier is dispersed in any appropriate dispersion medium to prepare a carrier dispersion. Next, the carrier dispersion is applied to the surface of the substrate by any appropriate coating method. Thereafter, if necessary, the coating is dried to form a carrier-containing membrane. Next, the acidic gas adsorbent and the deterioration inhibitor are dissolved in any appropriate solvent to prepare an adsorbent-inhibitor solution. The order of addition of the acidic gas adsorbent and the deterioration inhibitor is not particularly limited. Thereafter, the adsorbent-inhibitor solution is applied to the surface of the substrate or the carrier-containing membrane by any appropriate coating method. When the adsorbent-inhibitor solution is applied to the surface of the carrier-containing membrane, the adsorbent-inhibitor solution is impregnated into the carrier-containing membrane. Thereafter, by drying as necessary, an acidic gas adsorption layer containing the acidic gas adsorbent, the deterioration inhibitor, and the porous carrier is formed. When the adsorbent-inhibitor solution is applied to the surface of the substrate, the coating is dried as necessary to form an acidic gas adsorption layer containing the acidic gas adsorbent and the deterioration inhibitor. In this way, the acidic gas adsorption layer 2 having a single layer structure is produced.

[0053] D. Acidic Gas Recovery Method Next, a method for recovering acidic gas using an acidic gas adsorption device according to one embodiment of the present invention will be described. The acidic gas recovery method typically includes an adsorption step and a desorption step.

[0054] In the adsorption process, a gas to be treated containing an acidic gas is supplied to the acidic gas adsorption layer 2, which has been adjusted to a predetermined adsorption temperature. When the gas to be treated is a carbon dioxide-containing gas, the carbon dioxide concentration in the carbon dioxide-containing gas before being supplied to the acidic gas adsorption device is, for example, 100 ppm (volume basis) to 2% by volume. As shown in FIG. 2 , in one embodiment, the gas to be treated containing an acidic gas passes through an acidic gas flow path 14 provided in the acidic gas adsorption device 100 and comes into contact with the acidic gas adsorption layer 2 facing the acidic gas flow path 14. Since the acidic gas adsorption layer 2 contains a degradation inhibitor, the acidic gas adsorbent can be prevented from falling off due to the gas to be treated passing through the acidic gas flow path 14. Furthermore, since the degradation inhibitor can dissolve acidic gases, the acidic gas adsorbent contained in the acidic gas adsorption layer 2 can be sufficiently contacted with the acidic gas. This allows the acidic gas adsorbent to adsorb the acidic gas (typically carbon dioxide) from the gas to be treated. The gas to be treated, with its acidic gas content reduced, is then discharged from the acidic gas adsorption device 100 as a treated gas.

[0055] The temperature of the acidic gas adsorption layer in the adsorption step (adsorption temperature) is, for example, 0°C to 50°C, and preferably 10°C to 40°C. 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 to 3 hours, and preferably 30 minutes to 2 hours. When the adsorption temperature and / or adsorption time are within the above ranges, the acidic gas adsorbent can efficiently adsorb acidic gases.

[0056] The acidic gas adsorption rate in the adsorption step (=100-(acidic gas concentration in treated gas / acidic gas concentration in gas to be treated before supply to the acidic gas adsorption section×100)) is, for example, 60% or more, preferably 75% or more, and more preferably 80% or more. On the other hand, the upper limit of the acidic gas adsorption rate in the adsorption step is typically 90%.

[0057] In the desorption step, the acidic gas adsorption device 100 is typically heated to a desorption temperature that exceeds the adsorption temperature. More specifically, in the desorption step, the temperature of the acidic gas adsorption layer 2 is raised to the desorption temperature and then maintained at the desorption temperature for a predetermined desorption time. This causes the acidic gas adsorbed by the acidic gas adsorbent in the adsorption step to be desorbed from the acidic gas adsorbent. Therefore, the desorbed acidic gas can be recovered.

[0058] In one embodiment, in the desorption step, the desorbed gas heated to the above-mentioned desorption temperature is passed through the acidic gas flow path 14 of the acidic gas adsorption device 100, and the desorbed acidic gas is recovered together with the desorbed gas. The gas recovered in the desorption step may be referred to as recovered gas. Examples of the desorbed gas include water vapor, CO ２ Examples of the acid gas recovery method include the acid gas recovered previously by an acid gas adsorption apparatus. In the desorption step, the acid gas can also be recovered without using the desorbed gas. For example, the desorbed acid gas can be recovered by sucking it with a vacuum pump. Alternatively, the desorbed gas and the vacuum pump can be used in combination.

[0059] The temperature of the acidic gas adsorption layer in the desorption step (desorption temperature) is, for example, 70°C to 200°C, and preferably 80°C to 110°C. Even if the acidic gas adsorption layer is heated to such a desorption temperature in the desorption step, the acidic gas adsorption layer contains a deterioration-inhibiting material, so that volatilization of the acidic gas adsorbent can be stably suppressed. The duration of the desorption step (the desorption time during which the acidic gas adsorption section is maintained at the desorption temperature) is, for example, 1 minute to 1 hour, and preferably 5 minutes to 30 minutes. When the desorption temperature and / or desorption time are within the above ranges, acidic gases can be sufficiently desorbed from the acidic gas adsorbent.

[0060] As a result, the acid gas can be efficiently recovered while the acid gas adsorption performance of the acid gas adsorption device is sufficiently maintained. With such an acid gas adsorption device, the adsorption step and the desorption step can be repeatedly performed. In one embodiment, the cycle of the adsorption step and the desorption step is performed, 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.

[0061] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The methods for measuring the properties of the degradation inhibitors used in the examples and comparative examples are as follows.

[0062] Example 1 A clay containing alumina, silica, and magnesia (i.e., cordierite) was extruded and then dried to prepare a honeycomb substrate as shown in FIG. 1 . The honeycomb substrate had a rectangular columnar shape. The length of one side of the bottom surface of the honeycomb substrate was 120 mm. The length of the honeycomb substrate was 100 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 of 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%.

[0063] Next, the porous carrier was dispersed in a dispersion medium to prepare a carrier dispersion. Next, the carrier dispersion was applied to the partition walls of a honeycomb substrate at room temperature and normal pressure (23°C, 0.1 MPaA (absolute pressure)). Thereafter, the coated film of the carrier dispersion was dried to form a carrier-containing film containing the porous carrier.

[0064] An adsorbent solution was prepared by dissolving an acidic gas adsorbent in a solvent. The adsorbent solution was then applied to the surface of the carrier-containing membrane at room temperature and atmospheric pressure (23°C, 0.1 MPaA (absolute pressure)). The adsorbent solution was then impregnated into the carrier-containing membrane. The carrier-containing membrane containing the adsorbent solution was then dried to form a first layer containing the acidic gas adsorbent and the porous carrier. The thickness of the first layer was 100 μm.

[0065] Next, [TMGH][PhO] (ionic liquid, cation: 1,1,3,3-tetramethylguanidinium, anion: phenoxide) as a degradation inhibitor was passed through the cells of the honeycomb substrate on which the first layer was formed at room temperature and normal pressure (23°C, 0.1 MPaA (absolute pressure)). As a result, the ionic liquid was applied to the surface of the first layer, and a second layer composed of the ionic liquid was formed. The thickness of the second layer was 1 μm. The solubility (acidic gas solubility) of acidic gas (carbon dioxide gas) in the degradation inhibitor and the vapor pressure of the degradation inhibitor are shown in Table 1.

[0066] As a result, an acidic gas adsorption layer including the first and second layers was formed on the partition walls of the honeycomb substrate, and an acidic gas adsorption device (carbon dioxide adsorption device) was prepared. The content of the ionic liquid in the acidic gas adsorption layer was 0.5 parts by mass relative to 1 part by mass of the acidic gas adsorbent.

[0067] Example 2 An acidic gas adsorption device was prepared in the same manner as in Example 1, except that the deterioration inhibitor [TMGH][PhO] was changed to [DETAH][Im] (ionic liquid, cation: 2,2′-diaminodiethylammonium, anion: imidazolate).

[0068] Example 3 An acidic gas adsorption device was prepared in the same manner as in Example 1, except that the degradation inhibitor [TMGH][PhO] was changed to [HMIM]Cl-AP (a deep eutectic solvent, a mixed solution of aminopropanol as a hydrogen bond donor and 1-methylimidazolium chloride as a hydrogen bond acceptor).

[0069] Example 4 An acidic gas adsorption apparatus was prepared in the same manner as in Example 1, except that the deterioration inhibitor [TMGH][PhO] was changed to DBU-EG (a deep eutectic solvent, a mixed solvent of ethylene glycol as a hydrogen bond donor and 1,8-diazabicyclo[5.4.0]undec-7-ene as a hydrogen bond acceptor).

[0070] Example 5 An acidic gas adsorption apparatus was prepared in the same manner as in Example 1, except that the deterioration-suppressing material [TMGH][PhO] was changed to vanillin-carvone (a deep eutectic solvent, a mixed solvent of vanillin and carvone, vanillin:carvone=1:3).

[0071] Comparative Example 1 An acidic gas adsorption device was prepared in the same manner as in Example 1, except that the deterioration-suppressing material [TMGH][PhO] was changed to monoethanolamine (MEA).

[0072] Comparative Example 2 An acidic gas adsorption device was prepared in the same manner as in Example 1, except that the deterioration-suppressing material [TMGH][PhO] was changed to polyethylene glycol.

[0073] <Reference Example 1> An acidic gas adsorption device was prepared in the same manner as in Example 1, except that the second layer composed of the deterioration-inhibiting material was not formed, and only the first layer containing the acidic gas adsorbent and the porous carrier was used as the acidic gas adsorption layer.

[0074] <Acid gas (CO ２ ) Evaluation of Adsorption Performance> The acidic gas adsorption devices obtained in each Example, Comparative Example, and Reference Example were housed in a quartz tubular reactor so that the extension direction of the cell was parallel to the vertical direction. Next, the gas flow path was vented at 100°C in nitrogen, and then the acidic gas adsorption device was cooled to room temperature (23°C). A mixed gas (0.04 vol% CO in nitrogen) was introduced into the gas flow path of this acidic gas adsorption device at 25°C and a flow rate of 2 m / sec for 15 minutes. ２ ) was flowed. ２ The concentrations were measured, and the above-mentioned acidic gas adsorption rates (%) were calculated. Next, the acidic gas adsorption performance of the acidic gas adsorption devices of each Example and Comparative Example was evaluated using the acidic gas adsorption rate of the acidic gas adsorption device of the Reference Example as the standard. More specifically, when the acidic gas adsorption rate of the acidic gas adsorption device of the Reference Example was taken as 100%, an acidic gas adsorption rate of less than 40% was evaluated as "C," an acidic gas adsorption rate of 40% or more and 90% or less was evaluated as "B," and an acidic gas adsorption rate of more than 90% was evaluated as "A." The results are shown in Table 1.

[0075] <Evaluation of High-Temperature Durability> The mass (initial mass) of the acidic gas adsorption layer provided in the acidic gas adsorption device obtained in each Example and Comparative Example was measured. Next, the acidic gas adsorption device was maintained at 120°C for 100 hours, and then the mass (post-heating mass) of the acidic gas adsorption layer in the acidic gas adsorption device after heating was measured. Next, the high-temperature durability of the acidic gas adsorption layer was evaluated based on the initial mass of the acidic gas adsorption layer. More specifically, when the initial mass of the acidic gas adsorption layer was taken as 100%, a post-heating mass of the acidic gas adsorption layer was evaluated as "C." A post-heating mass of the acidic gas adsorption layer of 90% to 98% was evaluated as "B." A post-heating mass of the acidic gas adsorption layer of more than 98% was evaluated as "A." The results are shown in Table 1.

[0076]

[0077] As is clear from Table 1, when the acidic gas adsorption layer contains a degradation inhibitor whose vapor pressure at 25°C is 30 Pa or less, mass change of the acidic gas adsorption layer is suppressed in a high-temperature environment. Therefore, when the acidic gas adsorption device is subjected to the above-mentioned desorption process, volatilization and / or wear of the acidic gas adsorbent can be suppressed. Furthermore, when the acidic gas solubility in the degradation inhibitor is 0.1 mol / kg or more, the acidic gas adsorption device has excellent acidic gas adsorption performance. Therefore, when the vapor pressure of the degradation inhibitor is 30 Pa or less and the acidic gas solubility is 0.1 mol / kg or more, the acidic gas adsorption device can stably maintain excellent acidic gas adsorption performance.

[0078] The acid gas adsorption device according to the embodiment of the present invention is used for separating and recovering acid gases, and can be particularly suitably used in a carbon dioxide capture, utilization, and storage (CCUS) cycle.

[0079] REFERENCE SIGNS LIST 1 Substrate 2 Acidic gas adsorption layer (part) 21 Acidic gas adsorbent 22 Deterioration suppression material 23 Porous carrier 100 Acidic gas adsorption device

Claims

1. An acidic gas adsorption device comprising an acidic gas adsorption section in contact with an acidic gas flow path, the acidic gas adsorption section including: an acidic gas adsorbent capable of adsorbing acidic gas; and a deterioration inhibitor having a solubility of the target acidic gas of 0.1 mol / kg or more at 25°C and a vapor pressure of 30 Pa or less at 25°C.

2. The acidic gas adsorption device according to claim 1, wherein the acidic gas adsorption portion is an acidic gas adsorption layer disposed on the surface of a substrate.

3. The acidic gas adsorption device according to claim 2, wherein the acidic gas adsorption layer comprises: a first layer having an acidic gas adsorption ability containing the acidic gas adsorbent, the first layer being arranged on the surface of the substrate; and a second layer facing the acidic gas flow path, the second layer being arranged on at least a portion of the surface of the first layer, the second layer containing the deterioration inhibitor.

4. The acid gas adsorption device according to claim 2, wherein the acid gas adsorption layer faces the acid gas flow path and has a single layer structure having an acid gas adsorption ability.

5. The acid gas adsorption device according to claim 1, wherein the acid gas adsorption section further includes a porous carrier that supports the acid gas adsorbent.

6. The acid gas adsorption device of claim 1, wherein the acid gas is carbon dioxide.

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