Honeycomb structure, production method for same, and carbon dioxide recovery device

Abstract

The present invention is a honeycomb structure that has a plurality of cell channels that pass through the interior of the honeycomb structure and are partitioned by a partitioning wall 20. The partitioning wall 20 includes a carbon dioxide adsorbent, an organic binder, and an expansion inhibitor. The expansion inhibitor is a water-insoluble material that has a long diameter of A–1 / 2B μm, where A is the average particle diameter of the carbon dioxide adsorbent, and B is the thickness of the partitioning wall.

Description

Honeycomb structure, its manufacturing method, and carbon dioxide recovery device

[0001] The present invention relates to a honeycomb structure, a method for manufacturing the same, 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 describes a honeycomb structure having multiple partition walls (partition walls) extending axially from the inlet end to the outlet end, thereby forming multiple flow channels. The honeycomb structure comprises a mixture of inorganic powder components and an organic binder, and an amine polymer having functional structural unit groups that absorb CO2 is dispersed in the inorganic powder components of the partition walls. The honeycomb structure can adsorb CO2 by flowing a CO2-containing process gas through the cells. Furthermore, the CO2 adsorbed in the honeycomb structure can be desorbed by flowing a purge gas (desorption gas) such as water vapor through the cells.

[0004] Special table 2015-508018 publication

[0005] The CO2 adsorbed in the honeycomb structure is desorbed by passing a purge gas such as water vapor through the cells, but at this time the carbon dioxide adsorbent (amine polymer) absorbs water and expands, so the size of the honeycomb structure becomes larger when desorbing CO2 than when adsorbing CO2. If the size of the honeycomb structure changes between when adsorbing CO2 and when desorbing CO2 in this way, it becomes difficult to install the honeycomb structure in a carbon dioxide recovery device.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a honeycomb structure that can reduce size fluctuations during the carbon dioxide adsorption and desorption cycle, a method for manufacturing the same, and a carbon dioxide recovery device.

[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 by incorporating a water-insoluble material having a predetermined major axis as an expansion inhibitor into the partition walls, it is possible to suppress size fluctuations of the honeycomb structure due to expansion of the carbon dioxide adsorbent, 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, an organic binder, and an expansion inhibitor, the expansion inhibitor being a water-insoluble material having a major axis of A to 1 / 2B μm, where A is the average particle size of the carbon dioxide adsorbent and B is the thickness of the partition walls.

[0009] <2> The honeycomb structure according to <1>, wherein the expansion inhibitor is at least one selected from the group consisting of hollow particles, carbon-based materials, and resin-based materials.

[0010] <3> The honeycomb structure according to <1>, wherein the expansion inhibitor is at least one selected from the group consisting of inorganic hollow particles, expanded resin, graphite, carbon nanotubes, carbon fibers, polyester fibers, hydrophobic cellulose fibers, and polyethylene particles.

[0011] <4> The honeycomb structure according to any one of <1> to <3>, wherein the organic binder is at least one selected from the group consisting of water-soluble cellulose, polyurethane, polyethylene oxide, polybutadiene, acrylic acid ester, and methacrylic acid ester.

[0012] <5> The honeycomb structure according to <4>, wherein the water-soluble cellulose is at least one selected from the group consisting of methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and hydroxyethyl methyl cellulose.

[0013] <6> The honeycomb structure according to any one of <1> to <5>, wherein the expansion coefficient of the honeycomb structure is 20% or less.

[0014] <7> The honeycomb structure according to any one of <1> to <6>, wherein the carbon dioxide adsorbent is a solid organic compound having at least one selected from an amino group and an ammonium group.

[0015] <8> The honeycomb structure according to <7>, 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.

[0016] <9> The honeycomb structure according to <7>, 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.

[0017] <10> A method for manufacturing a honeycomb structure, comprising: a step of kneading a forming raw material including a solvent, a carbon dioxide adsorbent, an organic binder, and an expansion inhibitor to prepare a clay; a step of forming the clay into a honeycomb formed body, the honeycomb formed body having a plurality of cell channels that pass through the interior and are partitioned by partition walls; and a step of drying the honeycomb formed body, wherein the expansion inhibitor is a water-insoluble material having a major axis of A to 1 / 2B μm, where A is the average particle size of the carbon dioxide adsorbent and B is the thickness of the partition walls.

[0018] <11> The method for manufacturing a honeycomb structure according to <10>, wherein the expansion inhibitor is at least one selected from hollow particles, carbon-based materials, and resin-based materials.

[0019] <12> The method for manufacturing a honeycomb structure according to <10>, wherein the expansion inhibitor is at least one selected from the group consisting of inorganic hollow particles, expanded resin, graphite, carbon nanotubes, carbon fibers, polyester fibers, hydrophobic cellulose fibers, and polyethylene particles.

[0020] <13> The method for manufacturing a honeycomb structure according to any one of <10> to <12>, wherein the content of the carbon dioxide adsorbent excluding the solvent in the forming raw material is 45 to 96 mass%, the content of the organic binder excluding the solvent in the forming raw material is 2 to 30 mass%, and the content of the expansion inhibitor excluding the solvent in the forming raw material is 2 to 25 mass%.

[0021] <14> A carbon dioxide recovery device comprising one or more honeycomb structures according to any one of <1> to <9>.

[0022] According to the present invention, it is possible to provide a honeycomb structure capable of reducing size fluctuations in the carbon dioxide adsorption and desorption cycle, a method for manufacturing the same, and a carbon dioxide recovery device.

[0023] 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.

[0024] 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 (hereinafter abbreviated as "adsorbent"), an organic binder, and an expansion inhibitor. The expansion inhibitor is a water-insoluble material having a major axis of A to 1 / 2B μm, where A is the average particle size of the carbon dioxide adsorbent and B is the thickness of the partition walls. The honeycomb structure of the present invention can inhibit and / or absorb the expansion of the adsorbent during carbon dioxide desorption by the expansion inhibitor contained in the partition walls. Therefore, size fluctuations of the honeycomb structure during the carbon dioxide adsorption and desorption cycle (between carbon dioxide adsorption and desorption) can be suppressed.

[0025] 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.

[0026] (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).

[0027] 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.

[0028] 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. 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.

[0029] 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.

[0030] 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.

[0031] The partition walls 20 constituting the honeycomb structure contain an adsorbent, an organic binder, and an expansion inhibitor. Similarly to the partition walls 20, the peripheral wall 10 constituting the honeycomb structure may also contain an adsorbent, an organic binder, and an expansion inhibitor. By incorporating an expansion inhibitor into the partition walls 20 and the peripheral wall 10, the expansion of the adsorbent during carbon dioxide desorption can be inhibited and / or absorbed, thereby suppressing size fluctuations of the honeycomb structure during the carbon dioxide adsorption and desorption cycle. Furthermore, incorporating an adsorbent into the partition walls 20 and the peripheral wall 10 enables carbon dioxide adsorption. Furthermore, compared to conventional honeycomb structures in which the surfaces of the partition walls 20 and the peripheral wall 10 are coated with an adsorbent, this structure is manufactured without a high-temperature firing process, thereby reducing the amount of carbon dioxide generated during manufacturing. Furthermore, the amount of adsorbent supported can be increased, thereby increasing the amount of carbon dioxide adsorption.

[0032] The expansion inhibitor is a water-insoluble material having a major axis of A to 1 / 2B μm, where A is the average particle size of the carbon dioxide adsorbent and B is the thickness of the partition walls 20. Using a water-insoluble material with such a major axis inhibits and / or facilitates absorption of the adsorbent during carbon dioxide desorption, thereby suppressing size fluctuations of the honeycomb structure during the carbon dioxide adsorption and desorption cycle. Here, in this specification, the "major axis of the water-insoluble material" refers to the length of the longest part of the water-insoluble material. Therefore, for example, if the water-insoluble material is fibrous, the major axis refers to the fiber length, and if the water-insoluble material is particulate, the major axis refers to the particle size. The major axis of the water-insoluble material in the partition walls 20 constituting the honeycomb structure can be measured as follows. First, the honeycomb structure is observed using a scanning electron microscope (SEM), and particles for which C and N are not simultaneously detected in elemental analysis using an energy dispersive X-ray fluorescence analyzer (EDX) are considered to be water-insoluble materials. The major axes of 10 particles are then measured, and the average value is taken as the major axis of the water-insoluble material. In this method for determining the major axis of the water-insoluble material, the organic binder is not detected in particulate form, making it possible to distinguish between the particulate water-insoluble material and the organic binder. In this specification, the average particle size of the carbon dioxide adsorbent in the partition walls 20 constituting the honeycomb structure can be measured as follows. First, the honeycomb structure is observed using a scanning electron microscope (SEM), and particles in which C and N are simultaneously detected by elemental analysis using an energy dispersive X-ray fluorescence analyzer (EDX) are considered to be carbon dioxide adsorbents. Then, the particle sizes (average values ​​of the longest and shortest diameters) of 10 such particles are measured, and the average value is taken as the average particle size of the carbon dioxide adsorbent. In this specification, the "thickness of the partition walls 20" is defined as the length of the portion of the line segment connecting the centers of gravity of adjacent cells 30 that passes through the partition walls 20 in a cross section perpendicular to the extension direction of the cells 30. Furthermore, the thickness of the partition walls 20 refers to the average value of the thicknesses of all the partition walls 20 in the honeycomb structure.

[0033] Examples of the expansion inhibitor (water-insoluble material) that can be used include hollow particles, carbon-based materials, and resin-based materials. Here, carbon-based materials and resin-based materials refer to materials other than hollow particles. Specific examples of the expansion inhibitor (water-insoluble material) include inorganic hollow particles, expanded resin, graphite, carbon nanotubes, carbon fibers, polyester fibers, hydrophobic cellulose fibers, and polyethylene particles. These can be used alone or in combination of two or more. Such materials are likely to have the effect of inhibiting and / or absorbing the expansion of the adsorbent during carbon dioxide desorption.

[0034] The content of the expansion inhibitor in the honeycomb structure (partition walls 20 and outer peripheral wall 10) is not particularly limited, but is preferably 2 to 25 mass%, more preferably 3 to 20 mass%, and even more preferably 4 to 15 mass%. By setting the content within such a range, the effect of inhibiting and / or absorbing the expansion of the adsorbent during carbon dioxide desorption can be stably ensured.

[0035] The adsorbent is not particularly limited, and known adsorbents can be used. Among them, the adsorbent is preferably one or more of an amino group (-NH, -NHR, -NRR' (R and R' represent organic groups)) and an ammonium group (-N + Preferably, the adsorbent is a solid organic compound having one or more selected from the group consisting of aryl, ...

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The content of the adsorbent in the honeycomb structure (partition walls 20 and outer peripheral wall 10) is not particularly limited, but is preferably 45 to 96 mass%, more preferably 50 to 94 mass%, and even more preferably 55 to 92 mass%. By setting the content within such a range, the proportion of the adsorbent can be increased, thereby improving the carbon dioxide adsorption performance.

[0040] The organic binder is a component that increases the strength of the honeycomb structure (partition walls 20 and peripheral wall 10). Examples of organic binders include, but are not limited to, water-soluble cellulose, polyurethane, polyethylene oxide, polybutadiene, acrylic acid esters, and methacrylic acid esters. These can be used alone or in combination of two or more. By using these, the strength of the honeycomb structure can be stably improved. Examples of water-soluble cellulose that can be used include methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and hydroxyethyl methyl cellulose.

[0041] The content of the organic binder in the honeycomb structure (partition walls 20 and peripheral wall 10) is not particularly limited, but is preferably 2 to 30 mass%, more preferably 3 to 29 mass%, and even more preferably 4 to 28 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.

[0042] In addition to the above components, the honeycomb structure (partition walls 20 and peripheral wall 10) may further contain known additives such as surfactants and pore formers, 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 formers 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.

[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 in a cross section perpendicular to the extension direction of the cells 30.

[0044] The thickness of the partition wall 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. Moreover, the thickness of the partition wall 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.

[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 8 to 124 cells / cm. 2 , more preferably 16 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 a cross section perpendicular to the extension direction of the cells 30 is not particularly limited, but is preferably a quadrangle (for example, a square), a hexagon, an octagon, a circle, or a combination thereof. Among these, square and hexagonal shapes are preferred for the shape of the cells 30. 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 an expansion coefficient of 20% or less. It can be said that an expansion coefficient within this range results in small size fluctuations in the honeycomb structure during the carbon dioxide adsorption and desorption cycle. The expansion coefficient of the honeycomb structure can be calculated by measuring the cell pitch size of the honeycomb structure using a microscope before and after immersing it in water for one hour, and using the following formula: Expansion coefficient [%] = Cell pitch size after immersion in water / Cell pitch size before immersion in water × 100. Here, in this specification, "cell pitch" refers to the length of the line segment connecting the centers of gravity of two adjacent cells on one end face (first end face 40 or second end face 50) of the honeycomb structure.

[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 cells 30 (cell channels) of the honeycomb structure, adsorbing the carbon dioxide in the gas by an 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 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 molding raw material containing a solvent, an adsorbent, an organic binder, and an expansion inhibitor to prepare a clay. The expansion inhibitor is selected from water-insoluble materials with a major axis of A to 1 / 2B μm, where A is the average particle size of the adsorbent and B is the thickness of the partition walls. The solvent (dispersion medium) is not particularly limited, and examples include water and a mixed solvent of water and an organic solvent such as alcohol, with water being particularly preferred. The average particle size (D50) of the adsorbent can be controlled by pulverization using a ball mill or the like.

[0054] The content of the adsorbent excluding the solvent in the forming raw material is preferably 45 to 96% by mass, more preferably 50 to 94% by mass, and even more preferably 55 to 92% 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 the organic binder excluding the solvent in the forming raw material is preferably 2 to 30% by mass, more preferably 3 to 29% by mass, and even more preferably 4 to 28% by mass. Furthermore, from the viewpoint of ensuring the effect of inhibiting and / or absorbing the expansion of the adsorbent during carbon dioxide desorption, the content of the expansion inhibitor excluding the solvent in the forming raw material is preferably 2 to 25% by mass, more preferably 3 to 20% by mass, and even more preferably 4 to 15% by mass. 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] 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.

[0056] The honeycomb formed body drying step (third step) is a step of drying the honeycomb formed body obtained in the second step. Since the honeycomb formed body immediately after molding contains a solvent, the solvent is removed by drying. For drying, conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying can be used. 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 viewpoint of suppressing decomposition of the adsorbent, organic binder, and expansion inhibitor during drying, it is preferable to dry the honeycomb formed body 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.

[0057] (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. The above-described honeycomb structures have small size fluctuations during the carbon dioxide adsorption and desorption cycle, making it easy to install the honeycomb structures in the carbon dioxide capture apparatus.

[0058] 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.

[0059] 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.

[0060] <Materials Used> The following commercially available water-insoluble weakly basic anion exchange resin (styrene-based divinylbenzene polymer with a primary amine functional group and an exchange capacity of 2.0 meq / mL) was prepared as the adsorbent. The adsorbent was pulverized in a ball mill to an average particle size (D50) of 10 μm. Methylcellulose was prepared as the organic binder. The following expansion inhibitors were prepared: Material A (graphite: major axis 10 μm), Material B (carbon nanotubes: major axis 10 μm), Material C (carbon nanotubes: major axis 2.5 μm), Material D (foamed resin: major axis 50 μm), Material E (inorganic hollow particles: major axis 50 μm), and Material F (polyester: major axis 90 μm). Industrial water was prepared as the solvent. The average particle size of the adsorbent and the major axis of the expansion inhibitor were measured again using the above-described method after the honeycomb structure was fabricated, and were confirmed to be the same as those of the materials used.

[0061] The adsorbent, organic binder, expansion inhibitor, and solvent were blended to obtain a molding raw material at the content shown in Table 1. In Table 1, the content of each component is the content of the molding raw material excluding the solvent. Next, the molding 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.

[0062] 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: rectangular cell extension direction length: 30 mm Diameter of each end face: 60 mm Thickness of outer peripheral wall: 1 mm Thickness of partition wall: 200 μm Cell density: 46.5 cells / cm 2

[0063] 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.

[0064] Next, the expansion coefficient of the honeycomb structure obtained above was evaluated. The expansion coefficient was evaluated by measuring the cell pitch before and after immersing the honeycomb structure in water for 1 hour using a microscope, and calculating the expansion coefficient using the above formula. The results are shown in Table 1.

[0065]

[0066] As shown in Table 1, the honeycomb structures (Examples 1 to 7) containing a carbon dioxide adsorbent, an organic binder, and an expansion inhibitor, and having partition walls in which the major axis of the expansion inhibitor was within the range of A to 1 / 2B μm, had smaller expansion coefficients than the honeycomb structure (Comparative Example 1) having partition walls that did not contain an expansion inhibitor, or the honeycomb structure (Comparative Example 2) having partition walls in which the major axis of the expansion inhibitor was outside the range of A to 1 / 2B μm. As can be seen from the above results, the present invention can provide a honeycomb structure, a manufacturing method thereof, and a carbon dioxide recovery device that can reduce size fluctuations during the carbon dioxide adsorption and desorption cycle.

[0067] 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, an organic binder, and an expansion inhibitor, the expansion inhibitor being a water-insoluble material having a major axis of A to 1 / 2B μm, where A is the average particle size of the carbon dioxide adsorbent and B is the thickness of the partition walls.

2. The honeycomb structure according to claim 1, wherein the expansion inhibitor is at least one material selected from the group consisting of hollow particles, carbon-based materials, and resin-based materials.

3. The honeycomb structure according to claim 1, wherein the expansion inhibitor is one or more selected from inorganic hollow particles, expanded resin, graphite, carbon nanotubes, carbon fibers, polyester fibers, hydrophobic cellulose fibers, and polyethylene particles.

4. A honeycomb structure according to any one of claims 1 to 3, wherein the organic binder is at least one selected from the group consisting of water-soluble cellulose, polyurethane, polyethylene oxide, polybutadiene, acrylic acid ester, and methacrylic acid ester.

5. The honeycomb structure according to claim 4, wherein the water-soluble cellulose is one or more selected from the group consisting of methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol and hydroxyethyl methyl cellulose.

6. The honeycomb structure according to any one of claims 1 to 3, wherein the expansion coefficient of the honeycomb structure is 20% or less.

7. A honeycomb structure according to any one of claims 1 to 3, 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.

8. The honeycomb structure according to claim 7, 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.

9. The honeycomb structure according to claim 7, 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.

10. A method for manufacturing a honeycomb structure, comprising: a step of kneading forming raw materials containing a solvent, a carbon dioxide adsorbent, an organic binder, and an expansion inhibitor to prepare a clay; a step of molding the clay into a honeycomb formed body, the honeycomb formed body having a plurality of cell channels passing through the interior and separated by partition walls; and a step of drying the honeycomb formed body, wherein the expansion inhibitor is a water-insoluble material having a major axis of A to 1 / 2B μm, where A is the average particle size of the carbon dioxide adsorbent and B is the thickness of the partition walls.

11. The method for manufacturing a honeycomb structure according to claim 10, wherein the expansion inhibitor is at least one material selected from the group consisting of hollow particles, carbon-based materials, and resin-based materials.

12. A method for manufacturing a honeycomb structure according to claim 10, wherein the expansion inhibitor is one or more selected from inorganic hollow particles, expanded resin, graphite, carbon nanotubes, carbon fibers, polyester fibers, hydrophobic cellulose fibers, and polyethylene particles.

13. A method for manufacturing a honeycomb structure described in any one of claims 10 to 12, wherein the content of the carbon dioxide adsorbent excluding the solvent in the forming raw material is 45 to 96 mass%, the content of the organic binder excluding the solvent in the forming raw material is 2 to 30 mass%, and the content of the expansion inhibitor excluding the solvent in the forming raw material is 2 to 25 mass%.

14. A carbon dioxide recovery device comprising one or more honeycomb structures according to any one of claims 1 to 3.

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