Honeycomb structure and carbon dioxide recovery device

Abstract

Provided is a honeycomb structure having a plurality of cell channels which pass through the interior of the structure and are partitioned by a partition wall 20. The partition wall 20 contains a carbon dioxide adsorbent and an organic binder, and the carbon dioxide adsorbent and the organic binder are at least partially bonded to each other.

Description

Honeycomb structure and carbon dioxide recovery device

[0001] The present invention relates to a honeycomb structure and a carbon dioxide recovery device.

[0002] To realize a decarbonized society, there is a growing need for technologies that capture and utilize greenhouse gases (e.g., carbon dioxide) from the atmosphere and exhaust gases. A typical conventional carbon dioxide (CO2) capture technology is Direct Air Capture (DAC), which adsorbs CO2 from the atmosphere. There are several types of DAC, including liquid absorption, membrane separation, and solid adsorption. Among these, the use of a honeycomb structure containing a CO2 adsorbent (absorbent) has been considered for the solid adsorption method.

[0003] For example, Patent Document 1 (Patent Document 1) describes a honeycomb structure having a plurality of partition walls extending axially from the inlet end to the outlet end, thereby forming a plurality of flow channels. The honeycomb structure comprises a mixture of an inorganic powder component and an organic binder, and an amine polymer having a functional structural unit group capable of absorbing CO2 is dispersed in the inorganic powder component of the partition walls. The honeycomb structure can adsorb CO2 by passing a CO2-containing process gas through the cells. Furthermore, the CO2 adsorbed in the honeycomb structure can be desorbed by passing a purge gas (desorption gas) such as water vapor through the cells.

[0004] Special table 2015-508018 publication

[0005] As described above, CO2 adsorbed in a honeycomb structure is desorbed by passing a purge gas such as water vapor through the cells, so the honeycomb structure is required to be water-resistant. However, the honeycomb structure described in Patent Document 1 is manufactured by extrusion molding a mixture of inorganic powder components, an organic binder, and an amine polymer, but is not fired, so it cannot be said to have sufficient water resistance. In particular, if the organic binder is water-soluble, the organic binder will dissolve when CO2 is desorbed, which may reduce the strength of the honeycomb structure and lead to breakage. In addition, swelling of the amine polymer also makes the honeycomb structure more susceptible to collapse.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a honeycomb structure and a carbon dioxide recovery device that are excellent in water resistance and capable of adsorbing and desorbing carbon dioxide.

[0007] The present inventors have conducted extensive research into honeycomb structures having partition walls containing a carbon dioxide adsorbent and an organic binder, and as a result have found that water resistance can be improved by bonding at least a portion of the carbon dioxide adsorbent and the organic binder, thereby completing the present invention. That is, the present invention is exemplified as follows.

[0008] <1> A honeycomb structure having a plurality of cell channels that pass through the interior of the honeycomb structure and are separated by partition walls, the partition walls containing a carbon dioxide adsorbent and an organic binder, and at least a portion of the carbon dioxide adsorbent and the organic binder are bonded to each other.

[0009] <2> The honeycomb structure according to <1>, wherein the bond is an amide bond and / or a urea bond.

[0010] <3> The honeycomb structure according to <1> or <2>, wherein the organic binder has one or more functional groups selected from a sulfo group, a phosphate group, a carboxy group, an ester group, an epoxy group, and an isocyanate group.

[0011] <4> The honeycomb structure according to <3>, wherein the organic binder is at least one selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid esters, phthalic acid esters, polyvinyl acetate, cyanoacrylic acid esters, bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, aliphatic type epoxy resins, glycidylamine type epoxy resins, methyl isocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and blocked isocyanates.

[0012] <5> The honeycomb structure according to any one of <1> to <4>, wherein the carbon dioxide adsorbent is a solid organic compound having at least one selected from an amino group and an ammonium group.

[0013] <6> The honeycomb structure according to <5>, wherein the solid organic compound is a weakly basic anion exchange resin having an amino group and / or a strongly basic anion exchange resin having an ammonium group.

[0014] <7> The honeycomb structure according to <5>, wherein the solid organic compound is a styrene-divinylbenzene copolymer having one or more selected from an amino group and an ammonium group, and / or an acrylic copolymer having one or more selected from an amino group and an ammonium group.

[0015] <8> The honeycomb structure according to any one of <1> to <7>, which does not contain an inorganic binder.

[0016] <9> A carbon dioxide recovery device comprising one or more honeycomb structures according to any one of <1> to <8>.

[0017] According to the present invention, it is possible to provide a honeycomb structure and a carbon dioxide recovery device that are excellent in water resistance and capable of adsorbing and desorbing carbon dioxide.

[0018] 1A is a schematic diagram of an end face perpendicular to the cell extension direction of a honeycomb structure according to an embodiment of the present invention, and FIG. 1B is a schematic diagram of a cross section taken along line aa' in FIG.

[0019] The honeycomb structure of the present invention has a plurality of cell channels that pass through the interior and are separated by partition walls, and the partition walls contain a carbon dioxide adsorbent and an organic binder, with at least a portion of the carbon dioxide adsorbent and the organic binder being bonded together. Since the honeycomb structure of the present invention has at least a portion of the carbon dioxide adsorbent and the organic binder bonded together, the organic binder is less likely to be eluted, thereby preventing breakage due to a decrease in the strength of the honeycomb structure. Furthermore, the carbon dioxide adsorbent is less likely to swell, preventing collapse of the honeycomb structure. As a result, the water resistance of the honeycomb structure is improved.

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also within the scope of the present invention.

[0021] (1. Honeycomb structure) Fig. 1A is a schematic diagram of an end face perpendicular to the cell extension direction of a honeycomb structure according to an embodiment of the present invention. Fig. 1B is a schematic diagram of a cross section taken along line aa' in Fig. 1A (a cross section parallel to the cell extension direction).

[0022] As shown in FIGS. 1A and 1B , the honeycomb structure has a plurality of cells 30 (cell channels) that pass through the interior and are separated by partition walls 20. Specifically, the honeycomb structure includes an outer peripheral wall 10 and partition walls 20 disposed on the inner periphery of the outer peripheral wall 10, extending from a first end face 40 to a second end face 50, and separating the plurality of cells 30 that form fluid flow paths. The plurality of cells 30 are arranged parallel to one another. The honeycomb structure is a flow-through type in which both end faces (first end face 40 and second end face 50) of each cell 30 are open. When a gas containing carbon dioxide (e.g., air) flows in through the first end face 40 where the inlets of the plurality of cells 30 are located, the carbon dioxide is adsorbed as it passes through the plurality of cells 30, and the gas with a reduced carbon dioxide concentration flows out from the second end face 50 where the outlets of the plurality of cells 30 are located.

[0023] The end face shape of the honeycomb structure is not particularly limited, and may be, for example, a round shape such as a circle, an ellipse, a racetrack shape, or an oval shape, a polygonal shape such as a triangle or a rectangle, or other irregular shapes. The outer shape of the honeycomb structure may typically be a columnar shape. Note that the honeycomb structure shown in Figures 1A and 1B has a square end face shape and is an example of a square columnar shape as a whole.

[0024] The length of the honeycomb structure in the direction in which the cells 30 extend (the length from the first end face 40 to the second end face 50) is not particularly limited and may be set appropriately depending on the application and required performance. However, while a longer length of the honeycomb structure in the direction in which the cells 30 extend can increase the amount of carbon dioxide adsorption, if the length is too long, pressure loss increases. For this reason, the length is preferably 20 to 350 mm, more preferably 20 to 300 mm, and even more preferably 20 to 250 mm.

[0025] The diameter of each end face of the honeycomb structure is not particularly limited and may be set appropriately depending on the application and required performance. However, while a larger diameter of each end face of the honeycomb structure can increase the amount of carbon dioxide adsorption, if the diameter is too large, manufacturing becomes more difficult. Therefore, the diameter is preferably 20 to 450 mm, more preferably 20 to 400 mm, and even more preferably 20 to 350 mm. Here, the diameter of each end face of the honeycomb structure in this specification means the diameter if the shape is circular, and means the circle-equivalent diameter if the shape is other than circular.

[0026] The partition walls 20 constituting the honeycomb structure contain a carbon dioxide adsorbent. Furthermore, the outer peripheral wall 10 constituting the honeycomb structure can also contain a carbon dioxide adsorbent, similar to the partition walls 20. By incorporating a carbon dioxide adsorbent into the partition walls 20 and the outer peripheral wall 10, carbon dioxide adsorption becomes possible. Furthermore, compared to conventional honeycomb structures in which the surfaces of the partition walls 20 and the outer peripheral wall 10 are coated with a carbon dioxide adsorbent, the honeycomb structure is manufactured without undergoing a firing process at a high heating temperature, thereby reducing the amount of carbon dioxide generated during manufacturing. Furthermore, the amount of carbon dioxide adsorbent supported can be increased, thereby increasing the amount of carbon dioxide adsorption.

[0027] The partition walls 20 constituting the honeycomb structure contain an organic binder. The peripheral wall 10 constituting the honeycomb structure may also contain an organic binder, similar to the partition walls 20. By including an organic binder in the partition walls 20 and the peripheral wall 10, the strength of the honeycomb structure can be increased.

[0028] The carbon dioxide adsorbent and organic binder contained in the partition walls 20 (and the peripheral wall 10, if necessary) that constitute the honeycomb structure are at least partially bonded. By bonding at least partially the carbon dioxide adsorbent and the organic binder in this manner, when carbon dioxide is desorbed using a purge gas (desorption gas) such as water vapor, collapse of the honeycomb structure due to swelling of the carbon dioxide adsorbent and elution of the organic binder are less likely to occur, thereby improving the water resistance of the honeycomb structure. The bonding ratio between the carbon dioxide adsorbent and the organic binder is not particularly limited and may be adjusted appropriately depending on the types of carbon dioxide adsorbent and organic binder used.

[0029] The type of bond between the carbon dioxide adsorbent and the organic binder is not particularly limited, as it depends on the types of functional groups possessed by the carbon dioxide adsorbent and the organic binder. Typical bonds include amide bonds, urea bonds, and combinations thereof. Such bonds can stably improve the water resistance of the honeycomb structure.

[0030] The carbon dioxide adsorbent is not particularly limited as long as it can adsorb and desorb carbon dioxide and react with the organic binder. That is, the carbon dioxide adsorbent only needs to have a functional group capable of adsorbing and desorbing carbon dioxide and a functional group capable of reacting with the organic binder. The types of the functional group capable of adsorbing and desorbing carbon dioxide and the functional group capable of reacting with the organic binder may be the same or different. Examples of functional groups capable of adsorbing and desorbing carbon dioxide and reacting with the organic binder include amino groups. The number of functional groups contained in the carbon dioxide adsorbent may be one or two or more.

[0031] The carbon dioxide adsorbent has an amino group (one or more selected from -NH2, -NHR, -NRR' (R and R' represent organic groups)) and an ammonium group (-N +Preferably, the solid organic compound has one or more groups selected from the group consisting of RR'R" (R, R', and R" represent organic groups). Although the present invention is not intended to be limited by theory, a solid organic compound having an amino group can adsorb carbon dioxide by reacting with carbon dioxide to form a carbamate or bicarbonate. Furthermore, a solid organic compound having an ammonium group can adsorb carbon dioxide by reacting with carbon dioxide to form a bicarbonate. Furthermore, a solid organic compound having one or more groups selected from an amino group and an ammonium group can be reacted with an organic binder by using an organic binder having a specific functional group described below.

[0032] The solid organic compound having one or more selected from the amino group and the ammonium group is preferably water-insoluble from the viewpoint of water resistance. The solid organic compound having one or more selected from the amino group and the ammonium group is preferably —NH2, —NHR, —NRR′, —N + The solid organic compound may have any of RR'R" (R, R', and R" represent organic groups), or may have two or more of these in combination. Among amino groups, it is particularly preferable to have a primary amine (-NH2) as a functional group. It is also preferable that the solid organic compound having one or more selected from amino groups and ammonium groups contains an aromatic ring.

[0033] Specific examples of solid organic compounds having one or more groups selected from amino groups and ammonium groups include weakly basic anion exchange resins having amino groups and strongly basic anion exchange resins having ammonium groups. Furthermore, solid organic compounds having one or more groups selected from amino groups and ammonium groups include styrene-divinylbenzene copolymers having one or more groups selected from amino groups and ammonium groups, and acrylic copolymers having one or more groups selected from amino groups and ammonium groups. These can be used alone or in combination of two or more. Examples of styrene-divinylbenzene copolymers having one or more groups selected from amino groups and ammonium groups include copolymers of styrene and divinylbenzene. Examples of acrylic copolymers having one or more groups selected from amino groups and ammonium groups include (meth)acrylic acid-divinylbenzene copolymers. While OH-type, Cl-type, HCO3-type, etc. can be used as strongly basic anion exchange resins having ammonium groups, OH-type or HCO3-type are preferred from the viewpoint of carbon dioxide adsorption performance. That is, the counter anion of the ammonium group is OH. ― or HCO3 ― is preferred.

[0034] From the viewpoint of carbon dioxide adsorption performance, the exchange capacity of the weakly basic anion exchange resin is preferably 0.6 meq / mL or more, more preferably 1.0 meq / mL or more, and even more preferably 1.4 meq / mL or more. From the viewpoint of carbon dioxide adsorption performance, the exchange capacity of the strongly basic anion exchange resin is preferably 0.6 meq / mL or more, more preferably 1.0 meq / mL or more. Here, the exchange capacity of the weakly basic anion exchange resin is measured by the tapping method, where 10 mL of the ion exchange resin is treated with hydrochloric acid, the excess hydrochloric acid is washed away with ethanol, and the amount of chloride ions that flow out when aqueous ammonia is passed through. The exchange capacity of the strongly basic anion exchange resin is measured by the tapping method, where 10 mL of the ion exchange resin is treated with hydrochloric acid, the excess hydrochloric acid is washed away with ethanol, and the amount of chloride ions that flow out when aqueous sodium hydroxide solution is passed through.

[0035] The carbon dioxide adsorbent is preferably dispersed in the partition walls. Similarly, the carbon dioxide adsorbent is preferably dispersed in the outer peripheral wall. By dispersing the carbon dioxide adsorbent in the partition walls or the outer peripheral wall in this manner, the amount of carbon dioxide adsorbed can be increased.

[0036] The content of the carbon dioxide adsorbent in the partition walls 20 (and the outer peripheral wall 10 as necessary) is not particularly limited, but is preferably 40 to 94 mass%, more preferably 50 to 92 mass%, and even more preferably 60 to 90 mass%. By setting the content within such a range, the proportion of the carbon dioxide adsorbent can be increased, and therefore the carbon dioxide adsorption performance is improved.

[0037] The organic binder contains at least an organic binder capable of reacting with a carbon dioxide adsorbent (hereinafter referred to as a "reactive organic binder"). This reactive organic binder has a functional group capable of reacting with a functional group of the carbon dioxide adsorbent. When a carbon dioxide adsorbent having an amino group as a functional group is used, the reactive organic binder preferably has one or more functional groups selected from a sulfo group, a phosphate group, a carboxy group, an ester group, an epoxy group, and an isocyanate group. By using a reactive organic binder having such a functional group, it is possible to react with the carbon dioxide adsorbent to form an amide bond or a urea bond.

[0038] Examples of reactive organic binders include acrylic acid, acrylic acid esters, methacrylic acid esters, phthalic acid esters, polyvinyl acetate, cyanoacrylic acid esters, bisphenol A epoxy resins, bisphenol F epoxy resins, novolac epoxy resins, aliphatic epoxy resins, glycidylamine epoxy resins, methyl isocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and blocked isocyanates. These can be used alone or in combination of two or more. The use of such reactive organic binders makes them more likely to react with a carbon dioxide adsorbent having an amino group as a functional group.

[0039] The partition walls 20 (and the outer peripheral wall 10, if necessary) may further contain, in addition to the reactive organic binder, an organic binder that does not react with the carbon dioxide adsorbent (hereinafter referred to as a "non-reactive organic binder"). Examples of such non-reactive organic binders include methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, hydroxyethyl methyl cellulose, polyvinyl acetal, polyethylene oxide, polyethylene glycol, polyvinyl butyral, polybutadiene, ethyl cellulose, silicone, and polyolefin. These may be used alone or in combination of two or more. In particular, the use of a water-soluble organic binder such as methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, hydroxyethyl methyl cellulose, polyvinyl acetal, polyethylene oxide, or polyethylene glycol can reduce the environmental impact, the hazards associated with organic solvent vapor during drying, and the production costs.

[0040] The content of the organic binder (reactive organic binder and non-reactive organic binder) in the partition walls 20 (and the peripheral wall 10, if necessary) is not particularly limited, but is preferably 5 to 50 mass%, more preferably 8 to 40 mass%, and even more preferably 10 to 30 mass%. By setting the content within such a range, it is possible to improve the carbon dioxide adsorption performance while ensuring the strength of the honeycomb structure. Furthermore, the mass ratio of the reactive organic binder to the non-reactive organic binder is not particularly limited, but is preferably 1:9 to 9:1, more preferably 1:9 to 8:2, and even more preferably 2:8 to 8:2. By setting the mass ratio in such a range, it is possible to obtain sufficient CO2 adsorption performance while improving the water resistance of the honeycomb structure.

[0041] In addition to the above components, the partition wall 20 (and the outer peripheral wall 10, if necessary) may further contain known additives such as surfactants and pore-forming materials, as long as the effects of the present invention are not impaired. Specific examples of surfactants include ethylene glycol, dextrin, fatty acid soap, and polyalcohol. These may be used alone or in combination of two or more. Specific examples of pore-forming materials include wood flour, activated carbon, hollow resins, porous resins, hollow inorganic materials, and porous inorganic materials. These may be used alone or in combination of two or more.

[0042] The partition walls 20 (and the outer peripheral wall 10, if necessary) preferably do not contain an inorganic binder as a binder. That is, the binder contained in the partition walls 20 (and the outer peripheral wall 10, if necessary) is preferably made of the above-mentioned organic binder. Although the inorganic binder has the effect of improving water resistance, as described above, the water resistance is improved by the bond between the carbon dioxide adsorbent and the organic binder, and therefore, the inorganic binder does not need to be used.

[0043] The thickness of the peripheral wall 10 is not particularly limited, but is preferably 0.1 to 4.0 mm, more preferably 0.2 to 3.0 mm, and even more preferably 0.3 to 2.5 mm, from the viewpoint of ensuring strength. In this specification, the thickness of the peripheral wall 10 refers to the length in the normal direction to the peripheral surface of the honeycomb structure from the boundary between the peripheral wall 10 and the outermost cell 30 or partition wall 20 to the peripheral surface of the honeycomb structure, in a cross section perpendicular to the extension direction of the cells 30 of the honeycomb structure.

[0044] The thickness of the partition walls 20 is not particularly limited, but is preferably 50 μm or more, more preferably 80 μm or more, and even more preferably 100 μm or more, from the viewpoint of ensuring strength. Furthermore, the thickness of the partition walls 20 is preferably 50 to 600 μm, more preferably 80 to 550 μm, and even more preferably 100 to 500 μm, from the viewpoint of suppressing pressure loss. In this specification, the thickness of the partition walls 20 is defined as the length of the portion of a line segment connecting the centers of gravity of adjacent cells 30 that passes through the partition wall 20 in a cross section of the honeycomb structure perpendicular to the extension direction of the cells 30. Furthermore, the thickness of the partition walls 20 refers to the average thickness of all the partition walls 20 in the honeycomb structure.

[0045] It is preferable that the thickness of the outer peripheral wall 10 is the same as that of the partition walls 20. With such a configuration, it is possible to suppress an increase in pressure loss and increase the amount of carbon dioxide adsorption while ensuring the strength of the honeycomb structure.

[0046] The cell density of the honeycomb structure (the number of cells 30 per unit cross-sectional area) is not particularly limited, but is preferably 6 to 124 cells / cm. 2 , more preferably 6 to 62 cells / cm 2 By controlling the cell density within this range, it becomes easier to obtain the effect of suppressing an increase in pressure loss and the effect of improving the mechanical strength and the amount of carbon dioxide adsorption. 2 If the cell density is less than 124 cells / cm, the mechanical strength and the amount of carbon dioxide adsorption tend to decrease. 2 When the cell density exceeds this value, the pressure loss is likely to increase. Here, in this specification, the cell density is calculated by dividing the number of cells 30 in the honeycomb structure by the area of ​​one end face excluding the outer wall 10 of the honeycomb structure.

[0047] The shape of the cells 30 in the cross section perpendicular to the extension direction of the cells 30 of the honeycomb structure is not particularly limited, but is preferably a rectangle, a hexagon, an octagon, a circle, or a combination thereof. Among these, the shape of the cells 30 is preferably a square or a hexagon. By configuring the cells 30 in this way, it is possible to suppress an increase in pressure loss when gas is flowed through the honeycomb structure.

[0048] The honeycomb structure according to the embodiment of the present invention preferably has a saturated carbon dioxide adsorption capacity of 1 mmol / g or more. Such a saturated carbon dioxide adsorption capacity can be said to have excellent carbon dioxide adsorption performance. The saturated carbon dioxide adsorption capacity is measured by the method described in the examples below.

[0049] (2. Carbon Dioxide Capture Method and Desorption Method) The carbon dioxide capture method and desorption method according to an embodiment of the present invention are carried out using the above-described honeycomb structure. Specifically, the carbon dioxide capture method according to an embodiment of the present invention includes flowing a gas containing carbon dioxide through a plurality of cell channels of the honeycomb structure, adsorbing the carbon dioxide in the gas by a carbon dioxide adsorbent while the gas passes through the plurality of cells 30 (cell channels), and discharging the gas with a reduced carbon dioxide concentration from the honeycomb structure. The gas is not particularly limited as long as it contains carbon dioxide, and examples thereof include environmental air (outdoor air, as well as indoor or indoor air), factory exhaust gas, ship exhaust gas, and power plant exhaust gas.

[0050] Furthermore, a carbon dioxide desorption method according to an embodiment of the present invention includes flowing a desorbed gas or a heated desorbed gas through a plurality of cells 30 (cell channels) of a honeycomb structure in which carbon dioxide has been adsorbed, and desorbing carbon dioxide from the carbon dioxide adsorbent into the desorbed gas as the desorbed gas passes through the plurality of cells 30. The desorbed gas is not particularly limited as long as it is a gas capable of desorbing carbon dioxide, and may be, for example, water vapor. The water vapor is preferably at a high temperature of 80°C or higher. The desorbed gas may be heated by a heater or by mixing with a high-temperature gas.

[0051] (3. Manufacturing Method of Honeycomb Structure) The manufacturing method of the honeycomb structure according to the embodiment of the present invention is not particularly limited as long as it is a method that can manufacture the above-mentioned honeycomb structure. Hereinafter, a method suitable for manufacturing the honeycomb structure according to the embodiment of the present invention will be described.

[0052] The method for manufacturing a honeycomb structure according to an embodiment of the present invention includes a clay preparation step (first step), a forming step into a honeycomb formed body (second step), and a drying step of the honeycomb formed body (third step).

[0053] The clay preparation step (first step) is a step of kneading a forming raw material containing a carbon dioxide adsorbent and an organic binder to prepare a clay. The forming raw material may further contain a solvent. The solvent (dispersion medium) is not particularly limited, and examples thereof include water and a mixed solvent of water and an organic solvent such as alcohol, but water is particularly preferred.

[0054] The content of carbon dioxide adsorbent excluding the solvent in the forming raw material is preferably 40 to 94% by mass, more preferably 50 to 92% by mass, and even more preferably 60 to 90% by mass, from the viewpoint of achieving a good balance between carbon dioxide adsorption performance, crack suppression during drying, and water resistance. From the same viewpoint, the content of organic binder (reactive organic binder and non-reactive organic binder) excluding the solvent in the forming raw material is preferably 5 to 50% by mass, more preferably 8 to 40% by mass, and even more preferably 10 to 30% by mass. The mass ratio of reactive organic binder to non-reactive organic binder in the organic binder is preferably 2:8 to 10:0, more preferably 3:7 to 10:0, and even more preferably 4:6 to 10:0. The solvent content in the forming raw material is adjusted so as to obtain a clay of suitable hardness for forming (particularly, extrusion forming).

[0055] To prevent clogging during molding, the carbon dioxide adsorbent preferably has a median diameter (D50) based on a volume-based cumulative particle size distribution obtained by a laser diffraction / scattering method of 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 15 μm or less. For reasons of availability and suppression of secondary aggregation, the median diameter (D50) of the carbon dioxide adsorbent is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. Therefore, the median diameter (D50) of the carbon dioxide adsorbent is, for example, preferably 0.1 to 100 μm, more preferably 0.5 to 50 μm, even more preferably 1 to 50 μm, even more preferably 1 to 40 μm, and particularly preferably 1 to 30 μm.

[0056] When a water-soluble organic binder is used as the organic binder, the organic binder dissolves during kneading. Therefore, there are no particular limitations on the shape and size, and it is sufficient to use an organic binder in a generally available form. When a water-insoluble organic binder is used, it dissolves during kneading if an organic solvent is used. Therefore, there are no particular limitations on the shape and size.

[0057] The molding raw materials containing the above-mentioned components can be kneaded using a known kneader, and it is desirable to carry out the kneading for a time required for each component to be uniformly distributed in the clay.

[0058] The forming step (second step) into a honeycomb formed body is a step of forming the clay obtained in the first step into a honeycomb formed body. The honeycomb formed body has a plurality of cells 30 (cell channels) that pass through the interior and are partitioned by partition walls 20. Specifically, in the second step, extrusion is performed to form a honeycomb formed body that includes an outer peripheral wall 10 and partition walls 20 that are disposed on the inner peripheral side of the outer peripheral wall 10, extend from a first end face 40 to a second end face 50, and partition the plurality of cells 30 that form fluid flow paths. During extrusion, a die having a desired overall shape, cell shape, partition wall thickness, cell density, etc. can be used.

[0059] The honeycomb formed body drying step (third step) is a step of drying the honeycomb formed body obtained in the second step. Because the honeycomb formed body immediately after molding contains a solvent, the solvent is removed by drying. This drying step also allows at least a portion of the carbon dioxide adsorbent and the reactive organic binder to react with each other. Conventional drying methods, such as hot air drying, microwave drying, dielectric drying, reduced-pressure drying, vacuum drying, and freeze drying, can be used for drying. Among these, hot air drying, microwave drying, dielectric drying, or a combination thereof is preferred because it allows the entire honeycomb formed body to be dried quickly and uniformly. From the viewpoints of promoting the reaction between the carbon dioxide adsorbent and the reactive organic binder during drying and suppressing decomposition of the carbon dioxide adsorbent and the organic binder, the honeycomb formed body is preferably dried in an air atmosphere at 20 to 150°C, more preferably in an air atmosphere at 30 to 140°C, and even more preferably in an air atmosphere at 40 to 130°C.

[0060] (4. Carbon Dioxide Capture Apparatus) A carbon dioxide capture apparatus according to an embodiment of the present invention includes one or more of the above-described honeycomb structures. Because the carbon dioxide capture apparatus includes the above-described honeycomb structure, it has excellent water resistance and can suppress a decrease in strength and a decrease in CO2 adsorption performance that are caused by elution of the organic binder and the carbon dioxide adsorbent during use.

[0061] The carbon dioxide capture device according to the embodiment of the present invention may further include a housing that accommodates the honeycomb structure. The housing is preferably connected to a pipe that can supply and discharge a gas containing carbon dioxide and a desorbed gas. A carbon dioxide capture device having such a structure can easily achieve the capture and desorption of carbon dioxide.

[0062] The present invention will be described in detail below with reference to examples, but the present invention should not be construed as being limited to these examples.

[0063] <Materials Used> The following commercially available water-insoluble weakly basic anion exchange resin (a styrene-based divinylbenzene polymer having a primary amine functional group with an exchange capacity of 2.0 meq / mL) was prepared as a carbon dioxide adsorbent. The acidic adsorbent was pulverized in a ball mill before kneading, and the median diameter (D50) was adjusted to 10 μm when the volume-based cumulative particle size distribution was measured by a laser diffraction / scattering method. Acrylic acid ester and blocked isocyanate (both in emulsion form) were prepared as reactive organic binders. Methylcellulose was prepared as a non-reactive organic binder. Industrial water was prepared as a solvent.

[0064] A forming raw material was obtained by blending the carbon dioxide adsorbent, each organic binder, and solvent to the content shown in Table 1. In Table 1, the content of the organic binder is the content of the organic binder, not the content of the emulsion. Next, the forming raw material was kneaded for 30 minutes in a vacuum kneader to prepare a puddle. The amount of solvent blended was adjusted so that the puddle would have a hardness suitable for molding.

[0065] Next, the clay was molded using an extrusion molding machine having a predetermined die structure to obtain a honeycomb molded body. The die structure was selected so that the honeycomb molded body (honeycomb structure) after drying would have the following conditions: Outer shape: rectangular columnar cell cross-sectional shape: length in the direction of extension of the rectangular cell: 120 mm, diameter of each end face: 60 mm, outer peripheral wall thickness: 1 mm, partition wall thickness: 200 μm, cell density: 46.5 cells / cm 2

[0066] Next, the obtained honeycomb molded body was subjected to high frequency dielectric drying, and then dried for 1 minute in an air atmosphere at a temperature of 120° C. using a microwave dryer, and both end faces were cut off by a predetermined length to prepare a honeycomb structure.

[0067] Next, the honeycomb structure obtained above was evaluated as follows.

[0068] <Presence or absence of bonding between carbon dioxide adsorbent and organic binder> The honeycomb structure was crushed in an agate mortar, and the crushed material was measured using a Fourier transform infrared spectrophotometer to obtain an FT-IR spectrum. In this evaluation, a peak derived from an amide bond or a urea bond was confirmed in the FT-IR spectrum, which was represented by "Good."

[0069] <Carbon Dioxide Adsorption Performance> The sample (honeycomb structure) was placed in a holder and placed in a sealed container. CO2 concentration sensors were then installed on the inlet and outlet sides of the sample's cell. Next, as a pretreatment, nitrogen gas heated to 90-100°C was passed through the sample at a flow rate of 1.5 L / min until the CO2 concentration at the outlet reached 0 ppm. The heating was then stopped while the nitrogen gas flow continued until the sample reached 25°C (room temperature). After reaching 25°C, air at 25°C was passed through the sample at a flow rate of 15 L / min, and the CO2 adsorption amount (mol) until saturation was reached was measured. The measured CO2 adsorption amount (mol) was divided by the sample's mass (kg) to calculate the CO2 adsorption amount per mass of the sample (mol / kg), which was defined as the saturated carbon dioxide adsorption amount. In this evaluation, a saturated carbon dioxide adsorption amount of 1 mmol / g or greater was represented by a ◯, and a saturated carbon dioxide adsorption amount less than 1 mmol / g was represented by an ×.

[0070] <Water Resistance> To evaluate water resistance, a cubic sample with a side length of 20 mm was cut out from a bone-dry honeycomb structure, and the sample was immersed in water for 24 hours. The B-axis compressive strength (compressive strength in a direction perpendicular to the cell extension direction of the honeycomb structure) was then measured. The B-axis compressive strength was measured by placing a weight on the side of the sample, applying a compressive load of 0.05 MPa to the sample, and visually evaluating the presence or absence of cracks due to deformation of the sample. In this evaluation, samples that did not develop cracks were represented as ◯ (able to withstand a load of 0.05 MPa), and samples that developed cracks were represented as × (not able to withstand a load of 0.05 MPa).

[0071] The results of the above evaluations are shown in Table 1.

[0072]

[0073] As shown in Table 1, the honeycomb structure (Example) having partition walls to which at least a portion of the carbon dioxide adsorbent and organic binder were bonded had good water resistance, whereas the honeycomb structure (Comparative Example) having partition walls to which at least a portion of the carbon dioxide adsorbent and organic binder were not bonded had insufficient water resistance.

[0074] As can be seen from the above results, the present invention can provide a honeycomb structure and a carbon dioxide recovery device that are excellent in water resistance and capable of adsorbing and desorbing carbon dioxide.

[0075] 10 outer peripheral wall 20 partition wall 30 cell 40 first end surface 50 second end surface

Claims

1. A honeycomb structure having a plurality of cell channels that pass through the interior of the honeycomb structure and are separated by partition walls, the partition walls containing a carbon dioxide adsorbent and an organic binder, and at least a portion of the carbon dioxide adsorbent and the organic binder are bonded together.

2. The honeycomb structure according to claim 1, wherein the bond is an amide bond and / or a urea bond.

3. The honeycomb structure according to claim 1 or 2, wherein the organic binder has one or more functional groups selected from the group consisting of a sulfo group, a phosphate group, a carboxy group, an ester group, an epoxy group and an isocyanate group.

4. The honeycomb structure according to claim 3, wherein the organic binder is one or more selected from acrylic acid, acrylic acid esters, methacrylic acid esters, phthalic acid esters, polyvinyl acetate, cyanoacrylic acid esters, bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, aliphatic type epoxy resins, glycidylamine type epoxy resins, methyl isocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and blocked isocyanates.

5. The honeycomb structure according to claim 1 or 2, wherein the carbon dioxide adsorbent is a solid organic compound having at least one group selected from the group consisting of an amino group and an ammonium group.

6. The honeycomb structure according to claim 5, wherein the solid organic compound is a weakly basic anion exchange resin having an amino group and / or a strongly basic anion exchange resin having an ammonium group.

7. A honeycomb structure according to claim 5, wherein the solid organic compound is a styrene-divinylbenzene copolymer having one or more groups selected from an amino group and an ammonium group, and / or an acrylic copolymer having one or more groups selected from an amino group and an ammonium group.

8. The honeycomb structure according to claim 1 or 2, which does not contain an inorganic binder.

9. A carbon dioxide recovery device comprising one or more honeycomb structures according to claim 1 or 2.

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