Honeycomb structure

Abstract

A honeycomb structure (10) comprises: a peripheral wall (11); a partition wall (12) that partitions a space on the inner side of the peripheral wall (11) into a plurality of cells (S) extending in the axial direction of the peripheral wall (11); a carrier supported on the surface of the partition wall (12); and a carbon dioxide adsorbent supported on the carrier. The partition wall (12) has a skeleton portion mainly composed of ceramic, and metal silicon that fills gaps in the skeleton portion and covers the surface of the skeleton portion. In an image obtained by photographing a cross-section of the partition wall (12) and binarizing the skeleton portion and portions other than the skeleton portion, when a division line is drawn so as to divide the skeleton portion, a value obtained by dividing the length of the division line in the image by the area of the skeleton portion in the image is in a range from 1 μm / mm2 to 1000 μm / mm2, inclusive.

Description

Honeycomb structure

[0001] This disclosure relates to a honeycomb structure having partition walls inside a peripheral wall.

[0002] It is widely known that carbon dioxide concentration strongly influences global warming. Therefore, various methods are being explored to effectively reduce carbon dioxide concentration by adsorbing carbon dioxide released into the atmosphere.

[0003] For example, Patent Document 1 discloses a honeycomb substrate for recovering carbon dioxide. The honeycomb substrate contains a binder. As the binder, for example, an organic compound is used.

[0004] Special table 2015-508018 publication

[0005] However, the honeycomb substrate disclosed in Reference 1 contains an organic compound as a binder, which tends to inhibit heat conduction from the heat source to the honeycomb substrate. Therefore, when recovering carbon dioxide using the honeycomb substrate disclosed in Reference 1, the adsorption of carbon dioxide is poor due to the poor thermal conductivity. In addition, the honeycomb substrate is assembled into the reactor of the carbon dioxide recovery device with insulation material and an external heat source wrapped around it, but when tightening during assembly, it is difficult to obtain sufficient strength in the honeycomb substrate containing an organic compound as a binder.

[0006] This invention has been made in view of these circumstances, and its purpose is to provide a honeycomb structure that has sufficient strength and can efficiently recover carbon dioxide.

[0007] A honeycomb structure for solving the above problems comprises a peripheral wall, a partition wall that divides the interior of the peripheral wall into a plurality of cells extending in the axial direction of the peripheral wall, a carrier supported on the surface of the partition wall, and a carbon dioxide adsorbent supported on the carrier, wherein the partition wall has a skeletal portion mainly composed of ceramic and metallic silicon that fills the gaps in the skeletal portion and covers the surface of the skeletal portion, and when a cross-section of the partition wall is photographed and the skeletal portion and other portions are binarized into an image, and a dividing line is drawn to separate the skeletal portion, the value obtained by dividing the length of the dividing line in the image by the area of ​​the skeletal portion in the image is 1 μm / mm ２ 1000μm / mm or more ２ The main points are as follows:

[0008] This configuration allows for excellent thermal conductivity while maintaining sufficient strength. Therefore, when using the above honeycomb structure to recover carbon dioxide, the good thermal conductivity leads to better carbon dioxide adsorption. In other words, carbon dioxide can be recovered efficiently.

[0009] Regarding the above honeycomb structure, it is preferable that the ceramic is at least one selected from silicon carbide, alumina, and cordierite. This configuration allows for a further improvement in the heat resistance of the partition walls. Furthermore, when the ceramic is silicon carbide, the thermal conductivity of the partition walls can be further improved.

[0010] Regarding the above-described honeycomb structure, the thickness of the partition wall is preferably 0.05 mm or more and 0.6 mm or less. This configuration allows for higher thermal conductivity of the partition wall and provides sufficient strength.

[0011] In the above-described honeycomb structure, it is preferable that the skeletal portion is composed of multiple ceramic particles in contact with each other. With this configuration, if stress is applied to the honeycomb structure and a crack occurs in the skeletal portion, the propagation of the crack can be suppressed.

[0012] Figure 1 is a perspective view of a honeycomb structure. Figure 2(a) is a perspective view of the honeycomb structure, and Figure 2(b) shows the components that make up the partition walls of the honeycomb structure. Figure 3(a) is an SEM image of a cross-section of a partition wall, and Figure 3(b) is a binarized image of the SEM image. Figure 4 is a schematic diagram showing the skeletal structure and partition lines.

[0013] An embodiment of the honeycomb structure according to the present invention will be described. As shown in Figure 1, the honeycomb structure 10 is configured in a prismatic shape. The honeycomb structure 10 comprises a peripheral wall 11, a partition wall 12 that divides the interior of the peripheral wall 11 into a plurality of cells S extending in the axial direction of the peripheral wall 11, a carrier supported on the surface of the partition wall 12, and a carbon dioxide adsorbent supported on the carrier. Note that the carrier and carbon dioxide adsorbent are not shown in the figure.

[0014] The cells S partitioned by the partition wall 12 are open at both ends. (Peripheral wall 11) The components constituting the peripheral wall 11 are not particularly limited and known components can be used, for example, it may be composed of the same components as the partition wall 12.

[0015] The thickness of the peripheral wall 11 is not particularly limited and can be set as appropriate, but for example it may be the same as or thicker than the thickness of the partition wall 12. The thickness of the peripheral wall 11 is preferably, for example, 0.05 mm or more and 0.6 mm or less.

[0016] (Partition Wall 12) As shown in Figures 2(a) and 2(b), the partition wall 12 has a skeletal portion 21 (ceramic particles) mainly composed of ceramic, and metallic silicon that fills the gaps in the skeletal portion 21 and covers the surface of the skeletal portion 21.

[0017] The ceramic constituting the skeletal portion 21 of the partition wall 12 is not particularly limited and known materials can be used, such as silicon carbide, alumina, cordierite, zirconia, aluminum nitride, silicon nitride, forsterite, steatite, sialon, machinable ceramics, barium titanate, lead zirconate titanate, ferrite, and mullite. Among these, it is preferable that the ceramic be at least one selected from silicon carbide, alumina, and cordierite.

[0018] The average particle diameter of the ceramic particles is not particularly limited and can be set as appropriate, for example, it can be between 0.8 μm and 10 μm. The average particle diameter of the ceramic particles can be measured by observing the cross-section of the honeycomb structure 10 with an electron microscope (acceleration voltage: 10 kV, magnification: 3000x). Specifically, the particle diameter of all ceramic particles in the field of view is measured from three randomly selected electron microscope images, and the average value is taken as the average particle diameter of the ceramic particles.

[0019] Preferably, the skeletal portion 21 is composed of multiple ceramic particles in contact with each other. This suppresses the propagation of cracks when stress is applied to the honeycomb structure 10 and cracks occur in the skeletal portion 21. The state in which multiple ceramic particles are in contact with each other means a state in which multiple ceramic particles are in contact with each other without being sintered. Furthermore, a crack in the skeletal portion 21 means a gap formed by the separation of ceramic particles. In the case of a sintered body in which ceramic particles are sintered, a crack in the skeletal portion 21 means a gap formed by the fracture of the sintered parts of the ceramic particles, as well as a gap formed by the fracture of the ceramic particles themselves.

[0020] The metallic silicon constituting the partition wall 12 is not particularly limited, and known materials can be used. Metallic silicon is also called metallic-grade silicon. The metallic silicon content in the partition wall 12 is preferably 10% by mass or more and 45% by mass or less. The metallic silicon content in the partition wall 12 is more preferably 20% by mass or more and 45% by mass or less, and even more preferably 30% by mass or more and 40% by mass or less.

[0021] The metallic silicon content in the partition wall 12 refers to the ratio of the mass of the filled metallic silicon to the mass of the partition wall 12 in the filled state. If the peripheral wall 11 is composed of the same components as the partition wall 12, it is preferable that the metallic silicon content in the peripheral wall 11 is also the same as that of the partition wall 12.

[0022] The metallic silicon content in the partition wall 12 can be calculated, for example, by the following method. First, the partition wall 12 is cut out from the honeycomb structure that has undergone the impregnation process described later. The cut-out partition wall 12 is crushed, and the mass A of the crushed partition wall 12 is measured. Next, the crushed partition wall 12 is treated with hydrofluoric acid to remove the filled metallic silicon. Then, the mass B of the crushed partition wall 12 is measured again. Finally, it can be calculated using the following formula.

[0023] The metallic silicon content (mass%) = ((mass A - mass B) / (mass A)) × 100 By having a metallic silicon content within the above numerical range, the gaps in the skeletal portion 21 can be suitably filled with metallic silicon. Since metallic silicon is a material with relatively high thermal conductivity, the thermal conductivity of the partition wall 12 can be improved. That is, the thermal conductivity of the honeycomb structure 10 can be improved. Furthermore, by having a metallic silicon content of 45 mass% or less, the surface of the partition wall 12 is not excessively covered with metallic silicon, so the supportability of the carrier and the carbon dioxide adsorbent supported on the carrier can be improved. In addition, it is possible to suppress the surface of the skeletal portion 21 from being excessively covered with metallic silicon, which would make it difficult for fluid to flow inside the cell S.

[0024] The porosity of the honeycomb structure 10 is preferably 50% or less. More preferably, the porosity of the honeycomb structure 10 is 0% or more and 40% or less, even more preferably 5% or less, even more preferably 1% or less, and most preferably 0%. The porosity of the honeycomb structure 10 can be determined by the mercury intrusion method. The measurement conditions in the mercury intrusion method are a contact angle of 130° and a surface tension of 485 mN / m. The test specimen for the mercury intrusion method was cut out from the honeycomb structure 10 so as to include the peripheral wall 11 and the partition wall 12. By having a porosity of 50% or less of the honeycomb structure 10, the honeycomb structure 10 can exhibit excellent thermal conductivity and have sufficient strength. Note that the porosity of the honeycomb structure 10 refers to the percentage of gaps in the skeletal portion of the peripheral wall 11 and partition wall 12 that are not filled with metallic silicon.

[0025] In the honeycomb structure 10, when a cross-section of the partition wall 12 is photographed and the skeletal portion 21 and other portion 22 are binarized into an image, and dividing lines 23 are drawn to separate the skeletal portion 21, the total length of the dividing lines 23 in the image (μm) is equal to the total area of ​​the skeletal portion 21 in the image (mm²). ２ The value obtained by dividing by (hereinafter also referred to as "unit division line length") is 1 μm / mm ２ 1000μm / mm or more ２ The following applies:

[0026] The method for determining the unit partition line length is described below. First, to obtain a binarized image of the partition wall 12, a cross-section of the partition wall 12 is photographed using an electron microscope. This yields a SEM image of the partition wall 12. As the electron microscope, a known field emission scanning electron microscope (hereinafter also referred to as "FE-SEM") or a scanning electron microscope (hereinafter also referred to as "SEM") can be used. The magnification is preferably between 100x and 400x.

[0027] As shown in the SEM image in Figure 3(a), the dark gray areas represent the skeletal portion 21. The light gray areas represent the metallic silicon (other portion 22) that fills the gaps in the skeletal portion 21.

[0028] As shown in the binarized image of Fig. 3(b), the SEM image of the partition wall 12 is binarized into a skeleton portion 21 and a remaining portion 22. The binarization method is not particularly limited, and for example, the image analysis processing software "image J" can be used. In the binarized image, the skeleton portion 21 is shown in white, and the remaining portion 22 is shown in black. The remaining portion 22 is metallic silicon filled in gaps of the skeleton portion 21.

[0029] Then, on the image after binarization, dividing lines 23 are drawn so as to divide regions derived from each of the ceramic particles before sintering in the skeleton portion 21, thereby dividing the contacted or sintered ceramic particles into a plurality of segments. The dividing lines 23 are thin lines that divide the skeleton portion 21 into a plurality of segments as shown in Fig. 4.

[0030] In addition, the above "dividing regions derived from each of the ceramic particles before sintering" refers to dividing into individual particles from a state where ceramic particles are bonded by sintering or a state where a plurality of ceramic particles are in contact with each other, and this can be performed by the "watershed processing" of the image analysis processing software "image J". Note that the above "dividing" means division by computational boundaries by software.

[0031] For example, when a plurality of ceramic particles are sintered to each other, a state in which the plurality of ceramic particles are integrated is observed in the SEM image. With respect to the binarized image of this SEM image, dividing lines 23 are drawn at boundary portions of the region where the plurality of ceramic particles are integrated using image analysis processing software. Further, when a plurality of ceramic particles are in contact with each other, a state where the plurality of ceramic particles are in contact with each other is observed in the SEM image. With respect to the binarized image of this SEM image, dividing lines 23 are drawn at boundary portions of locations where the respective ceramic particles are in contact using image analysis processing software.

[0032] In a case where locations where a plurality of ceramic particles are sintered to each other and locations where the plurality of ceramic particles are in contact with each other coexist, dividing lines 23 are drawn using image analysis processing software for both the boundary portions of locations where the plurality of ceramic particles are sintered and integrated, and the boundary portions of locations where the plurality of ceramic particles are in contact with each other.

[0033] Next, the length of the dividing lines 23 in an image in which the dividing lines 23 have been drawn is measured. In addition, the area of the skeleton portions 21 in the same image is measured. The total length (μm) of the dividing lines 23 in the image is divided by the total area (mm ２ ) to obtain a unit dividing line length (μm / mm ２ ).

[0034] For the measurement of the above "total area (mm ２ ) of the skeleton portions 21 in the image", the area of the skeleton portions 21 in the binarized image before the dividing lines 23 are drawn is used. The measurement of the unit dividing line length is performed on images of three locations on the partition wall 12, and the average value is taken as the unit dividing line length of the partition wall 12.

[0035] The length of the dividing lines 23 corresponds to the length of portions where ceramic particles are bonded to each other or in contact with each other. When the length of the dividing lines 23 is short, this means that the ceramic particles are not sufficiently bonded or in contact with each other, and therefore means that the thermal conductivity between the ceramic particles is low and the thermal conductivity of the partition wall 12 is low.

[0036] When the length of the dividing lines 23 is long, this means that the ceramic particles are well sintered and integrated with each other. This means that grain growth has occurred among the integrated ceramic particles, and the boundary portions of the ceramic particles are formed to an appropriate size. It means that large ceramic particles in which sintering has progressed are prone to crack propagation when stress is applied and a crack occurs in the skeleton portions 21, resulting in low strength of the partition wall 12.

[0037] The total length (μm) of the dividing lines 23 in the image is divided by the total area (mm ２By normalizing the value obtained by dividing by (i.e., the unit division line length), an index is used to indicate the degree of bonding and contact of ceramic particles in the skeletal portion 21.

[0038] The unit division line length of the honeycomb structure 10 is 1 μm / mm ２ 1000μm / mm or more ２ The following applies: The unit division line length of the honeycomb structure 10 is 1 μm / mm. ２ 500 μm / mm or more ２ Preferably, it is 3 μm / mm ２ 300 μm / mm or more ２ The following configuration is more preferable. With this configuration, the honeycomb structure 10 can exhibit excellent thermal conductivity and have sufficient strength. Therefore, when carbon dioxide is recovered using the honeycomb structure 10, good thermal conductivity leads to better adsorption of carbon dioxide. In other words, carbon dioxide can be recovered efficiently.

[0039] (Carrier) The carrier is not particularly limited and any known material can be used, for example, alumina (Al ２ O ３ ), TiO ２ SiO ２ , ZrO ２ Examples include zeolite and carbon. The method for supporting the support on the surface of the partition wall 12 is not particularly limited, but for example, a suspension in which these materials are dispersed in a dispersion medium is prepared and attached to the surface of the partition wall 12. Furthermore, it can be supported by drying and firing. The support may be a porous material such as polymethyl methacrylate. In addition, the support may be supported not only on the surface of the partition wall 12 but also on the surface of the peripheral wall 11. The firing of the support should be carried out at a temperature lower than the melting point of the metallic silicon.

[0040] (Carbon dioxide adsorbent) The carbon dioxide adsorbent is not particularly limited and any known material can be used, such as zeolite, alkaline and alkaline earth metal compounds, activated carbon, metal-organic structures, monoethanolamine, diethanolamine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, etc.

[0041] Metal-organic frameworks (MOFs) are materials that have a porous coordination network structure with a much larger surface area than activated carbon or zeolites, due to the interaction of metals and organic ligands.

[0042] The method for supporting the carbon dioxide adsorbent on the support is not particularly limited, but for example, an aqueous solution of these materials, an alcohol solution, or a suspension in which these materials are dispersed in a dispersion medium is prepared. Furthermore, the prepared aqueous solution is applied to the compartment wall 12 on which the support is supported. After that, the carbon dioxide adsorbent can be supported on the support by drying as appropriate. When the carbon dioxide adsorbent is supported on the support, the carbon dioxide adsorbent is positioned on the surface of the compartment wall 12 via the support. In addition, the carbon dioxide adsorbent may be supported not only on the surface of the compartment wall 12 but also on the surface of the peripheral wall 11.

[0043] (Method for manufacturing a honeycomb structure) The honeycomb structure 10 can be manufactured by sequentially following the molding process, impregnation process, carrier support process, and carbon dioxide adsorbent support process described below.

[0044] (Molding Process) As raw materials for molding the honeycomb structure 10, a clay-like mixture containing ceramic particles used in known honeycomb structures, an organic binder, and a dispersion medium is prepared. Using this mixture, a molded body is formed having a peripheral wall 11 and a partition wall 12 having a honeycomb cross-section that divides the interior of the peripheral wall 11 into a plurality of cells S extending in the axial direction of the peripheral wall 11. The molding method of the molded body is not particularly limited, but for example, it can be molded by extrusion molding. The obtained molded body may be subjected to a drying treatment to dry the molded body.

[0045] (Impregnation Process) The impregnation process is a process of impregnating the interior of the compartment walls 12 of the molded body with metallic silicon. In the impregnation process, a lump of metallic silicon is placed near the molded body and heated to a temperature above the melting point of metallic silicon (for example, 1450°C or higher). The lump of metallic silicon may be in direct contact with the molded body or in contact with it via a medium. As a result, the molten metallic silicon enters the gaps between the ceramic particles constituting the compartment walls 12 of the molded body by capillary action, and the metallic silicon is impregnated into these gaps.

[0046] (Supporting process for the support body) The supporting process for the support body is the process of supporting the support body on the honeycomb structure that has undergone the impregnation process. In the supporting process for the support body, first, a suspension is prepared in which the material to be used for the support body is dispersed in a dispersion medium. Next, the prepared suspension is attached to the surface of the partition wall 12. Furthermore, the support body can be supported by drying and firing.

[0047] (Carbon Dioxide Adsorbent Supporting Process) The carbon dioxide adsorbent supporting process involves supporting the carbon dioxide adsorbent on a honeycomb structure on which the support is attached. In the carbon dioxide adsorbent supporting process, first, an aqueous solution, an alcohol solution, or a suspension in which these materials are dispersed in a dispersion medium is prepared using the material used for the carbon dioxide adsorbent. Next, the prepared aqueous solution, etc., is applied to the surface of the compartment wall 12 on which the support is attached. Furthermore, the carbon dioxide adsorbent can be supported by drying as appropriate.

[0048] By going through the above steps, a honeycomb structure 10 is obtained, comprising a peripheral wall 11, a partition wall 12 that divides the interior of the peripheral wall 11 into a plurality of cells S extending in the axial direction of the peripheral wall 11, a carrier supported on the surface of the partition wall 12, and a carbon dioxide adsorbent supported on the carrier. The partition wall 12 has a skeletal portion 21 mainly composed of ceramic, and metallic silicon that fills the gaps in the skeletal portion 21 and covers the surface of the skeletal portion 21. The skeletal portion 21 is composed of a plurality of ceramic particles in contact with each other.

[0049] The manufacturing method for the honeycomb structure 10 may include the following degreasing step, firing step, and surface oxidation step between the molding step and the impregnation step. (Degreasing step) The degreasing step is a step in which the organic binder contained in the molded body is burned and incinerated by heating the molded body, thereby obtaining a degreased body from which the organic binder has been removed. By going through the degreasing step, the organic binder and dispersion medium are removed from the molded body, and a degreased body is obtained in which the ceramic particles are in contact with each other and gaps are between the ceramic particles.

[0050] (Firing Process) The firing process involves firing the degreased material obtained in the degreasing process at 1800 to 2200°C for 0.5 to 4 hours under an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere, thereby sintering the ceramic particles together. Through the firing process, the skeletal structure of the honeycomb structure becomes a sintered body made of sintered ceramic particles. Furthermore, by performing the impregnation process described above, metallic silicon fills the gaps in the skeletal structure, and the surface of the skeletal structure becomes covered with metallic silicon.

[0051] (Surface oxidation process) In the surface oxidation process, a thin layer of SiO2 is applied to the surface of the silicon-impregnated honeycomb structure in an oxidizing atmosphere. ２ This is a process for forming an oxide film. The surface oxidation process involves, for example, holding the film at 300 to 1500°C in air for 30 minutes to 10 hours, and then forming a thin SiO2 film. ２ A thin SiO oxide film can be formed. ２ By forming an oxide film, the adhesion force of the support and carbon dioxide adsorbent can be strengthened. ２ The film thickness is not particularly limited, but is preferably, for example, 0.1 to 1000 nm.

[0052] (Applications of the honeycomb structure) The honeycomb structure 10 of this embodiment can be used for carbon dioxide recovery. That is, it can be used in a carbon dioxide recovery device as a carbon dioxide adsorption structure. Specifically, within the peripheral wall 11 of the honeycomb structure 10, the compartment wall 12 on which the carbon dioxide adsorbent is supported can be used as a reaction layer for carbon dioxide adsorption and desorption. Furthermore, the reaction layer can be heated from outside the peripheral wall 11 of the honeycomb structure 10 with a heater.

[0053] <Operation and Effects of the Embodiment> The operation and effects of this embodiment will be described below. (1) The honeycomb structure 10 comprises a peripheral wall 11, a partition wall 12 that divides the interior of the peripheral wall 11 into a plurality of cells S extending in the axial direction of the peripheral wall 11, a carrier supported on the surface of the partition wall 12, and a carbon dioxide adsorbent supported on the carrier. The partition wall 12 has a skeletal portion 21 mainly composed of ceramic, and metallic silicon that fills the gaps in the skeletal portion 21 and covers the surface of the skeletal portion 21. When a cross-section of the partition wall 12 is photographed and the image is binarized to show the skeletal portion 21 and the other portion 22, and a partition line 23 is drawn to separate the skeletal portion 21, the value obtained by dividing the length of the partition line 23 in the image by the area of ​​the skeletal portion 21 in the image is 1 μm / mm ２ 1000μm / mm or more ２ The following applies:

[0054] With this configuration, the honeycomb structure 10 can exhibit excellent thermal conductivity and possess sufficient strength. Therefore, when carbon dioxide is recovered using the honeycomb structure 10, the good thermal conductivity leads to better adsorption of carbon dioxide. In other words, carbon dioxide can be recovered efficiently.

[0055] (2) The ceramic is at least one selected from silicon carbide, alumina, and cordierite. This configuration allows for greater heat resistance of the partition wall 12. (3) The thickness of the partition wall 12 is 0.05 mm or more and 0.6 mm or less. This configuration allows for greater thermal conductivity of the partition wall 12 and provides sufficient strength.

[0056] (4) The skeletal portion 21 is composed of multiple ceramic particles in contact with each other. With this configuration, if stress is applied to the honeycomb structure 10 and a crack occurs in the skeletal portion 21, the propagation of the crack can be suppressed.

[0057] <Examples of Modifications> This embodiment can be implemented with the following modifications. This embodiment and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0058] The cross-sectional shape of the cells S partitioned by the partition walls 12 of the honeycomb structure 10 is not limited to a quadrilateral, but may be a polygon. For example, the cross-sectional shape of the cells S may be a triangle, quadrilateral, hexagon, octagon, or a combination thereof.

[0059] The external shape of the honeycomb structure 10 is not limited to a prismatic shape, but may be cylindrical, elliptical, or fan-shaped. Furthermore, the honeycomb structure 10 may be formed by joining multiple honeycomb structures 10 together, resulting in an overall shape that is prismatic, cylindrical, or the like. The method for joining multiple honeycomb structures 10 is not particularly limited, but they can be joined, for example, by using a known adhesive or the metallic silicon described above. Additionally, the honeycomb structure 10 can be formed by machining an arbitrary shape from a prismatic honeycomb structure, for example. Specifically, an arbitrary external shape such as a cylinder can be created by grinding the outer circumference of a prismatic honeycomb structure.

[0060] In this embodiment, the peripheral wall 11 of the honeycomb structure 10, like the partition wall 12, had a skeletal portion 21 mainly composed of ceramic and metallic silicon that filled the gaps in the skeletal portion 21 and covered the surface of the skeletal portion 21, but is not limited to this embodiment. The peripheral wall 11 may be composed of other materials. Examples of other materials include known cement and the like.

[0061] In this embodiment, the unit section line length was measured using images from three locations on the partition wall 12, but the embodiment is not limited to this. The unit section line length may be measured using images from four or more locations on the partition wall 12, and the average value may be taken as the unit section line length of the partition wall 12.

[0062] In this embodiment, the skeletal portion 21 of the honeycomb structure 10 was composed of multiple ceramic particles in contact with each other, but the embodiment is not limited to this. The skeletal portion 21 of the honeycomb structure 10 may be composed of a sintered body made of sintered ceramic particles. If it is composed of a sintered body made of sintered ceramic particles, the strength of the honeycomb structure 10 can be improved.

[0063] The following describes examples that further elaborate on the above embodiments. (Example 1) First, a mixture with the following composition was prepared.

[0064] A mixture of silicon carbide particles (large particles) with an average particle size of 24 μm, silicon carbide particles (small particles) with an average particle size of 0.5 μm, silicon carbide particles (small particles) with an average particle size of 0.5 μm, silicon cellulose (organic binder), silicon cellulose (organic binder), silicon cellulose compound (plasticizer), silicon cellulose compound (plasticizer), and polyoxyalkylene compound (plasticizer) was used to form a prismatic molded body having a honeycomb structure with dimensions of 35 mm × 35 mm × 300 mm, a peripheral wall thickness of 0.3 mm, a partition wall thickness of 0.25 mm, and a cell width of 1.17 mm. Next, a block of metallic silicon 32.1 g was placed in contact with the molded body, and under vacuum, it was heated at 450°C for 1.0 hour, then at 1350°C for 2.0 hours, and then at 1550°C for 1.0 hour to obtain the honeycomb structure of Example 1, in which metallic silicon was melted and impregnated. The metallic silicon content of the honeycomb structure in Example 1 was 34.0% by mass, and the porosity of the honeycomb structure was 0%.

[0065] Subsequently, SiO is used as a carrier in the honeycomb structure. ２Monoethanolamine was supported as a carbon dioxide adsorbent. (Comparative Example 1) A molded body was obtained in the same manner as in Example 1. Next, a degreased body was obtained by heating the molded body at 370°C for 2.5 hours to remove the organic binder. Then, a calcined body was obtained by heating the degreased body in an argon atmosphere at 2150°C for 2.5 hours. Then, in the same manner as in Example 1, a block of metallic silicon 32.1 g was placed in contact with the calcined body and heated under vacuum at 1550°C for 1.0 hour to obtain the honeycomb structure of Comparative Example 1 in which metallic silicon was melted and impregnated. The metallic silicon content of the honeycomb structure of Comparative Example 1 was 34.0% by mass, and the porosity of the honeycomb structure was 0%.

[0066] Subsequently, the same support and carbon dioxide adsorbent as in Example 1 were supported on the honeycomb structure. (Comparative Example 2) A honeycomb structure of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that metallic silicon impregnation was not performed. The metallic silicon content of the honeycomb structure of Comparative Example 2 was 0% by mass, and the porosity of the honeycomb structure was 38.1%.

[0067] Subsequently, the same carrier and carbon dioxide adsorbent as in Example 1 were supported on the honeycomb structure. (Measurement of thermal conductivity) The thermal conductivity of the honeycomb structures of Example 1 and Comparative Examples 1 and 2 was measured in accordance with JIS R1611:2010. The honeycomb structures used for the measurement of thermal conductivity were those before the carrier and carbon dioxide adsorbent were supported.

[0068] (Measurement of Unit Section Line Length) The honeycomb structures according to Example 1, Comparative Example 1, and Comparative Example 2 were cut perpendicular to the longitudinal direction. Three arbitrary locations were selected in the cross-section of the section wall, and SEM images were obtained by taking images at a magnification of 200x using an electron microscope (FE-SEM: Hitachi High-Technologies Corporation high-resolution field emission scanning electron microscope S-4800). Next, each SEM image was binarized using the image analysis processing software "image J" to obtain binarized images. Furthermore, the "watershed processing" of the image analysis processing software "image J" was performed on the binarized images to draw the section lines. The area of ​​the skeletal parts in the same image was also measured. The total length of the section lines in the image (μm) was measured, and the total area of ​​the skeletal parts in the image (mm²) was measured. ２ By dividing by ), the unit division line length (μm / mm) at the three locations can be calculated. ２ The unit division line length (μm / mm) was calculated. ２ The average value of the unit division line length (μm / mm) was calculated. The results are shown in Table 1. ２ This is shown in the ) section.

[0069] (Compression Test) The following compression tests were performed on the honeycomb structures of Example 1 and Comparative Examples 1 and 2. The honeycomb structures used in the compression tests were those before the support material and carbon dioxide adsorbent were attached.

[0070] For the honeycomb structures of Example 1 and Comparative Examples 1 and 2, prismatic test specimens with dimensions of 34.3 mm × 34.3 mm × 100 mm were prepared. The longitudinal direction of the test specimens was aligned with the direction of cell extension. For each test specimen, the maximum load was measured when a compressive load was applied at a speed of 0.5 mm / min using a strength testing machine (Instron) from a direction perpendicular to the longitudinal direction of the test specimen. Subsequently, the compressive strength was calculated by dividing the obtained maximum load value by the cross-sectional area (34.3 mm × 100 mm) perpendicular to the loading direction of each test specimen before the compression test. The results are shown in the "Compressive Load (MPa)" column of Table 1.

[0071]

[0072] (Evaluation) As shown in Table 1, the thermal conductivity of the honeycomb structures of Example 1 and Comparative Example 1, which have metallic silicon, was higher than that of Comparative Example 2, which does not have metallic silicon.

[0073] Furthermore, the compressive strength of the honeycomb structure in Example 1 was 6.76 MPa. Compared to the honeycomb structures in Comparative Examples 1 and 2, the unit division line length of the honeycomb structure in Example 1 was 1000 μm / mm. ２ Therefore, it has sufficient strength and the unit division line length is 1 μm / mm ２ Therefore, it exhibited high thermal conductivity comparable to that of Comparative Example 1. This suggests that carbon dioxide can be recovered efficiently.

[0074] 10...Honeycomb structure, 11...Surrounding wall, 12...Partition wall, 21...Skeleton part, 22...Other parts, 23...Dividing line.

Claims

1. A honeycomb structure comprising a peripheral wall, a partition wall dividing the interior of the peripheral wall into a plurality of cells extending in the axial direction of the peripheral wall, a carrier supported on the surface of the partition wall, and a carbon dioxide adsorbent supported on the carrier, wherein the partition wall has a skeletal portion mainly composed of ceramic and metallic silicon filling the gaps in the skeletal portion and covering the surface of the skeletal portion, and when a cross-section of the partition wall is photographed and the skeletal portion and other portions are binarized into an image, and a dividing line is drawn to separate the skeletal portion, the value obtained by dividing the length of the dividing line in the image by the area of ​​the skeletal portion in the image is 1 μm / mm ２ 1000μm / mm or more ２ The following is a honeycomb structure.

2. The honeycomb structure according to claim 1, wherein the ceramic is at least one selected from silicon carbide, alumina, and cordierite.

3. The honeycomb structure according to claim 1, wherein the thickness of the partition wall is 0.05 mm or more and 0.6 mm or less.

4. The honeycomb structure according to claim 1, wherein the skeletal portion is composed of a plurality of ceramic particles in contact with each other.

Images