Honeycomb structure

Abstract

Provided is a honeycomb structure comprising a plurality of columnar honeycomb segments 100 that include an adsorbent capable of adsorbing greenhouse gases. The plurality of columnar honeycomb segments 100 are arranged such that the side surfaces 102 thereof face each other, and the facing side surfaces 102 are at least partially in direct or indirect contact with each other. The contact portion 104 occupies 0.6-92.0% of one side surface 102. The lengths of the contact portion 104 in the axial direction of the columnar honeycomb segment 100 and in a direction orthogonal to the axial direction are each at least 2% of the length of a side of the side surface 102.

Description

Honeycomb structure

[0001] The present invention relates to a honeycomb structure.

[0002] To mitigate global warming, there is a growing need for technologies that capture and utilize greenhouse gases (e.g., carbon dioxide) from gases such as the atmosphere and exhaust gases. For example, a technology for adsorbing atmospheric CO2 (DAC: Direct Air Capture) has been developed as a typical conventional carbon dioxide (CO2) capture technology. There are several types of DAC, including liquid absorption, membrane separation, and solid adsorption. Among these, solid adsorption generally involves supporting a CO2 adsorbent (absorbent) material on a substrate. Because substrates used in solid adsorption require a high specific surface area, pellet-type, sheet-type, and fiber-type supports have been mainstream. However, these supports have a high pressure loss during gas flow and require a large amount of energy in the CO2 adsorption process. Therefore, honeycomb structures have been considered as the support (see, for example, Patent Document 1).

[0003] Special table 2018-538137 publication

[0004] Honeycomb structures are mainly manufactured by extrusion molding, but due to factors such as their own weight, there is a limit to the size that can be manufactured according to the designed dimensions. Therefore, in order to obtain a honeycomb structure of dimensions that will ultimately be used in a greenhouse gas capture device such as CO2, a columnar honeycomb structure of the desired dimensions is formed by bonding the side surfaces (peripheral walls) of multiple small columnar honeycomb structures (hereinafter referred to as columnar honeycomb segments) together. However, this columnar honeycomb structure has the problem that greenhouse gases do not flow between the side surfaces, and therefore the side surfaces are not effectively used for adsorbing greenhouse gases.

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a honeycomb structure that can increase the amount of greenhouse gases adsorbed while ensuring strength.

[0006] As a result of extensive research into the structure of columnar honeycomb segments used in greenhouse gas recovery devices, the present inventors have found that the above-mentioned problems can be solved by bringing the side surfaces of the columnar honeycomb segments into contact with each other in a manner that satisfies specific conditions, and have thus completed the present invention. That is, the present invention is exemplified as follows.

[0007] [1] A honeycomb structure comprising a plurality of columnar honeycomb segments containing an adsorbent capable of adsorbing greenhouse gases, wherein the side surfaces of the plurality of columnar honeycomb segments are arranged to face each other, and at least a portion of the facing side surfaces are in direct or indirect contact with each other, the proportion of the contact portion on one side surface is 0.6 to 92.0%, and the lengths of the contact portions in the axial direction of the columnar honeycomb segments and in a direction perpendicular to the axial direction are each 2% or more of the length of the side of the side surface.

[0008] [2] The honeycomb structure according to [1], wherein at least a part of the opposing side surfaces is in contact with each other via a spacer.

[0009] [3] The honeycomb structure according to [2], wherein the spacer has a thickness of 0.2 to 10.0 mm.

[0010] [4] The honeycomb structure according to any one of [1] to [3], wherein the length of the contact portion in the direction perpendicular to the axial direction of the columnar honeycomb segment is less than 90% of the length of the side of the side surface.

[0011] [5] The honeycomb structure according to [4], wherein the contact portion is located at an end and / or a center of the side of the side surface in a direction perpendicular to the axial direction of the columnar honeycomb segment.

[0012] [6] The honeycomb structure according to any one of [1] to [5], wherein the length of the contact portion in the axial direction of the columnar honeycomb segment is 30% or less of the length of the side of the side surface.

[0013] [7] The honeycomb structure according to [6], wherein the contact portion is located at an end and / or a center of the side of the side surface in the axial direction of the columnar honeycomb segment.

[0014] [8] The honeycomb structure according to any one of [1] to [7], wherein slits are provided on the opposing side surfaces.

[0015] [9] The honeycomb structure according to [8], wherein at least a portion of the slit is provided on the side surface that does not overlap with the contact portion, the depth of the slit is less than 50% of the length between the side surface on which the slit is formed and the side surface opposite to the side surface on which the slit is formed, the proportion of the slit on one side surface is 20% or less, and the total proportion of the contact portion and the slit on one side surface is less than 100%.

[0016]

[10] The structure according to [9], wherein the maximum width of the slit is 50 mm or less.

[0017]

[11] The honeycomb structure according to any one of [1] to

[10] , wherein the columnar honeycomb segment has an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells extending from a first end face to a second end face.

[0018]

[12] The total pore volume of the outer wall and the partition wall is 0.2 to 1.5 cm 3 / g. The honeycomb structure according to

[11] .

[0019]

[13] The honeycomb structure according to

[11] or

[12] , wherein the average pore diameter of the outer wall and the partition walls is 0.1 to 15.0 μm.

[0020]

[14] The honeycomb structure according to any one of

[11] to

[13] , wherein the thickness of the outer peripheral wall is 0.1 to 4.0 mm.

[0021]

[15] The honeycomb structure according to any one of

[11] to

[14] , wherein the thickness of the outer peripheral wall and the thickness of the partition wall are the same.

[0022]

[16] The honeycomb structure according to any one of

[11] to

[15] , wherein the outer peripheral wall and the partition walls are made of a material containing the adsorbent.

[0023]

[17] The honeycomb structure according to any one of

[11] to

[15] , wherein the adsorbent is supported on the surfaces of the outer peripheral wall and the partition walls.

[0024]

[18] The honeycomb structure according to any one of [1] to

[17] , wherein the content of the adsorbent in the columnar honeycomb segment is 30 to 96 mass %.

[0025]

[19] The honeycomb structure according to any one of [2] to

[18] , wherein the spacer has adhesive ability.

[0026]

[20] The honeycomb structure according to any one of [2] to

[19] , wherein the spacer is made of a material containing a component capable of adsorbing greenhouse gases.

[0027]

[21] The honeycomb structure according to any one of [2] to

[20] , wherein the spacer is made of a material that requires a load of less than 2000 kPa for 80% compression.

[0028]

[22] The honeycomb structure according to any one of [2] to

[21] , wherein the spacer is arranged in the honeycomb structure so that a / b is 1.0 or more and less than 20.0, where a is the thickness of the spacer in an uncompressed state when not arranged in the honeycomb structure and b is the thickness of the spacer in a compressed state when arranged in the honeycomb structure.

[0029]

[23] The honeycomb structure according to any one of [2] to

[22] , wherein the spacer is made of a material having a compressive residual strain of less than 10% measured after 30 minutes from an uncompressed state where the spacer is not placed in the honeycomb structure, compressed by 80% and held for 24 hours.

[0030]

[24] The honeycomb structure according to any one of [2] to

[23] , wherein the heat resistance temperature of the spacer is 100° C. or higher.

[0031] According to the present invention, it is possible to provide a honeycomb structure that can increase the amount of greenhouse gases adsorbed while ensuring strength.

[0032] 1A . FIG. 1B is a plan view of an end face of a honeycomb structure according to an embodiment of the present invention. FIG. 1C is a cross-sectional view taken along line a-a' of the honeycomb structure shown in FIG. 1A. FIG. 1D is a diagram for explaining the position of a contact portion on one side face of the honeycomb structure shown in FIG. 1A. FIG. 1E is a cross-sectional view taken along line bb' of the honeycomb structure shown in FIG. 2A. FIG. 2F is a cross-sectional view taken along line bb' of the honeycomb structure shown in FIG. 2A. FIG. 2G is a specific example of a honeycomb structure including columnar honeycomb segments having various shapes. FIG. 2H is a cross-sectional view taken along line cc' of the honeycomb structure shown in FIG. 4A. FIG. 4I is a diagram for schematically explaining a method for measuring the hardness of a clay using a hardness tester. FIG. 4J is an enlarged view showing the shape and dimensions of the tip of the hardness tester. FIG. 4J is a graph showing the spring properties of a spring material used in a hardness tester.

[0033] The honeycomb structure of the present invention includes a plurality of columnar honeycomb segments containing an adsorbent capable of adsorbing greenhouse gases. The side surfaces of the plurality of columnar honeycomb segments are arranged to face each other, and at least a portion of the side surfaces of the facing columnar honeycomb segments are in direct or indirect contact with each other. The proportion of the contact area to the side surface of one columnar honeycomb segment is 0.6 to 92.0%. The lengths of the contact areas in the axial direction of the columnar honeycomb segment and in the direction perpendicular to the axial direction are each 2% or more of the length of the side surface of the columnar honeycomb segment. By configuring the honeycomb structure of the present invention in this way, greenhouse gases flow between the side surfaces of the facing columnar honeycomb segments, and these side surfaces can also be effectively used for greenhouse gas adsorption, thereby increasing the amount of greenhouse gas adsorption. Furthermore, the honeycomb structure can ensure sufficient strength.

[0034] 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.

[0035] (1. Honeycomb structure) Fig. 1A is a plan view of an end face of a honeycomb structure according to an embodiment of the present invention. Fig. 1B is a cross-sectional view of the honeycomb structure shown in Fig. 1A taken along line a-a' (a cross-sectional view parallel to the cell extension direction). Fig. 1C is a diagram for explaining the position of a contact portion on one side of the honeycomb structure shown in Fig. 1A. Fig. 2A is a plan view of the end face of another honeycomb structure according to an embodiment of the present invention. Fig. 2B is a cross-sectional view of the honeycomb structure shown in Fig. 2A taken along line bb' (a cross-sectional view parallel to the cell extension direction).

[0036] The honeycomb structure includes a plurality of columnar honeycomb segments 100. Although Figures 1A to 2B show an example in which four columnar honeycomb segments 100 are included, the number of columnar honeycomb segments 100 is not particularly limited. The number of columnar honeycomb segments 100 can be, for example, 2 to 25.

[0037] The plurality of columnar honeycomb segments 100 are arranged so that their side surfaces 102 face each other. Furthermore, at least a portion of the opposing side surfaces 102 of the plurality of columnar honeycomb segments 100 are in direct or indirect contact with each other. Note that FIGS. 1A and 1B show an example in which at least a portion of the opposing side surfaces 102 are in indirect contact with each other, and FIGS. 2A and 2B show an example in which at least a portion of the opposing side surfaces 102 are in direct contact with each other. When at least a portion of the opposing side surfaces 102 are in indirect contact with each other, a spacer 110 can be disposed between the opposing side surfaces 102. By configuring the opposing side surfaces 102 so that at least a portion of the opposing side surfaces 102 are in direct or indirect contact with each other, a space can be formed between the opposing side surfaces 102 through which greenhouse gases can flow.

[0038] The proportion of the contact portion 104 in one side surface 102 is 0.6 to 92.0%, preferably 2.0 to 70.0%, and more preferably 3.0 to 30.0%. By controlling the proportion in this range, a space through which greenhouse gases can flow can be formed between the opposing side surfaces 102. Here, the proportion of the contact portion 104 in one side surface 102 refers to the area proportion of the contact portion 104 (the area of ​​the portion in contact with the opposing side surface 102 when the contact portion 104 is in direct contact with the opposing side surface 102, or the area of ​​the portion in contact with the spacer 110 when the contact portion 104 is in indirect contact with the opposing side surface 102) in the surface area of ​​the one side surface 102. Therefore, for example, the proportion of the contact portion 104 in one side surface 102 of the honeycomb structure shown in FIGS. 1A and 1B is the ratio of the area of ​​the contact portion 104 to the total area of ​​the side surface 102 and the contact portion 104 in FIG. 1C.

[0039] The lengths L1, L2, L3, and L4 of the contact portions 104 in the axial direction X and the direction Y perpendicular to the axial direction X of the columnar honeycomb segment 100 are each 2% or more of the length of the side of the side surface 102. That is, as shown in FIG. 1C , the lengths L1 and L2 of the contact portions 104 in the axial direction X of the columnar honeycomb segment 100 (when a plurality of contact portions 104 are present, the total length of the plurality of contact portions 104) are 2% or more of the length of the side H1 of the side surface 102 in the axial direction X, and the lengths L3 and L4 of the contact portions 104 in the direction Y perpendicular to the axial direction X of the columnar honeycomb segment 100 (when a plurality of contact portions 104 are present, the total length of the plurality of contact portions 104) are 2% or more of the length of the side H2 of the side surface 102 in the direction Y. By controlling the lengths within such ranges, the mechanical strength of a honeycomb structure constituted by a plurality of columnar honeycomb segments 100 can be increased.

[0040] The lengths L3 and L4 of the contact portions 104 in the direction Y perpendicular to the axial direction X of the columnar honeycomb segment 100 are preferably less than 90%, more preferably 50% or less, and even more preferably 30% or less of the length H2 of the side surface 102. By controlling the lengths L3 and L4 within such ranges, it is possible to suppress an increase in pressure loss when greenhouse gases flow between the opposing side surfaces 102.

[0041] The lengths L1, L2 of the contact portions 104 in the axial direction X of the columnar honeycomb segment 100 are preferably 30% or less, more preferably 20% or less, and even more preferably 10% or less of the length of the side H1 of the side surface 102. By controlling the lengths within such ranges, greenhouse gases can easily come into contact with the side surface 102, and therefore the amount of greenhouse gas adsorption can be increased.

[0042] The position of the contact portion 104 in the direction Y perpendicular to the axial direction X of the columnar honeycomb segment 100 is not particularly limited, but can be the end and / or center of the side H2. Similarly, the position of the contact portion 104 in the axial direction X of the columnar honeycomb segment 100 is not particularly limited, but can be the end and / or center of the side H1. By providing the contact portion 104 at such a position, the mechanical strength of the honeycomb structure composed of a plurality of columnar honeycomb segments 100 can be increased. The number of contact portions on each side H1, H2 is not particularly limited, but can be, for example, 1 to 5.

[0043] As described above, the spacers 110 are provided when at least a portion of the opposing side surfaces 102 are in indirect contact with each other. The thickness of the spacers 110 is not particularly limited, but is preferably 0.2 to 10.0 mm, and more preferably 0.4 to 4.0 mm. Within this range, the honeycomb structure composed of a plurality of columnar honeycomb segments 100 can be made compact while increasing its mechanical strength. Here, the thickness of the spacers 110 means the length of the spacers 110 on the opposing side surfaces 102.

[0044] The spacer 110 is not particularly limited as long as it can maintain the space between the opposing side surfaces 102, and various materials can be used. For example, the spacer 110 can be made of an elastic material such as rubber, a resin, a ceramic, a metal, or the like. From the viewpoint of imparting a cushioning capacity suitable for expansion and contraction of the columnar honeycomb segment 100 due to hydration and drying, the spacer 110 preferably has an appropriate hardness depending on its type. For example, in the case of an elastic material such as rubber, the hardness is preferably 5 to 40 in Type A durometer (measured in accordance with JIS K6253-3:2023) or 10 to 50 in Asker C type (measured in accordance with SRIS 0101:1968). Furthermore, in the case of resin, ceramic, metal, or the like, the hardness is preferably 50 to 1000 Hv in Vickers hardness. Specific examples of spacers 110 that satisfy these conditions include silicone bond, silicone rubber sheets, graphite sheets, gel sheets, ethylene propylene rubber, urethane sponges, ceramic fiber mats, metal fiber mats, glass fiber mats, aluminum alloys, copper alloys, stainless steel magnesium alloys, titanium alloys, nickel alloys, steel, and bronze alloys. The spacers 110 may also be made of a material containing a component capable of adsorbing greenhouse gases. By constructing the spacers 110 from such materials, greenhouse gases can be adsorbed in the spacers 110, thereby increasing the amount of greenhouse gases adsorbed. Examples of such materials include, but are not limited to, amino compounds (e.g., solid organic compounds having amino groups), zeolites, and activated carbon.

[0045] The spacer 110 is preferably made of a material that requires a load of less than 2000 kPa for 80% compression. By using a material with such properties to form the spacer 110, the mechanical strength of the honeycomb structure composed of the plurality of columnar honeycomb segments 100 is easily improved, and the position of the plurality of columnar honeycomb segments 100 and the spacers 110 in the honeycomb structure is less likely to shift. Examples of materials that have such properties include foamed silicone, crystalline alumina fiber, and EPDM (ethylene propylene rubber) foam. From the viewpoint of stably ensuring the above-described effects, the load required to compress the spacer 110 by 80% is preferably 1950 kPa or less, more preferably 1900 kPa. The lower limit of the load required to compress the spacer 110 by 80% is not particularly limited, but may be, for example, 100 kPa, 200 kPa, or 300 kPa. The load required to compress the spacer 110 by 80% is calculated as follows. First, a test piece of 2 mm x 2 mm x arbitrary thickness is taken from the spacer 110. Next, under conditions of a temperature of 25°C, a relative humidity of 50%, and atmospheric pressure, a force gauge equipped with a circular attachment of 10 mm in diameter is pressed into the test piece until the thickness becomes 80% of the original thickness, and the repulsive force (N) and the area (mm 2 ) to the repulsive force (N / mm 2 ) is calculated and converted into kPa units.

[0046] The spacers 110 are preferably arranged in the honeycomb structure such that a / b is 1.0 or greater and less than 20.0, where a is the thickness of the spacers 110 in an uncompressed state when not arranged in the honeycomb structure and b is the thickness of the spacers 110 in a compressed state when arranged in the honeycomb structure. Arranging the spacers 110 under such conditions facilitates improving the mechanical strength of the honeycomb structure composed of a plurality of columnar honeycomb segments 100, and also makes it difficult for the columnar honeycomb segments 100 and the spacers 110 to shift position in the honeycomb structure, thereby preventing them from falling off during use. From the viewpoint of stably ensuring this effect, a / b is preferably 1.1 to 19.0. The thickness of the spacers 110 in an uncompressed state is measured by extracting the spacers 110 from the honeycomb structure (the spacers 110 to be used are prepared during the manufacturing process). The thickness is measured at a temperature of 25°C, a relative humidity of 50%, and atmospheric pressure. In addition, the compressed thickness of the spacer 110 arranged in the honeycomb structure is measured at the center in the direction along the outer periphery of the columnar honeycomb segment 100 on both end faces of the honeycomb structure (both end faces including the first end faces 122 and second end faces 124 of the multiple columnar honeycomb segments 100).

[0047] The spacers 110 are preferably made of a material that exhibits a compressive set of less than 10% when compressed 80% from an uncompressed state when not placed in a honeycomb structure, and then maintained for 24 hours, and then measured 30 minutes later. By forming the spacers 110 from a material with such properties, they can follow the contraction of the columnar honeycomb segments 100, thereby easily achieving a cushioning effect. This reduces the likelihood of misalignment of the multiple columnar honeycomb segments 100 and spacers 110 in the honeycomb structure, thereby preventing them from falling off during use. The compressive set of the spacers 110 can be measured in accordance with JIS K6262:2013. Specifically, it can be determined as follows. First, a spacer 110 is extracted from the honeycomb structure (the spacer 110 to be used is prepared during the manufacturing process), and the spacer 110 is compressed 80% (until it is reduced to 20% of its original thickness) and maintained for 24 hours at a temperature of 25°C, a relative humidity of 50%, and atmospheric pressure. Next, the spacer 110 is released from the compressed state and left to stand for 30 minutes, after which the compression set is measured.

[0048] The spacer 110 is preferably made of a material that requires a load of less than 2000 kPa to compress it 80% in an environment at 100°C, and that exhibits a compressive residual strain of less than 10% when measured 30 days after compressing it 80% from an uncompressed state where it is not placed in a honeycomb structure and maintaining the compression set for 24 hours. In the process of capturing (adsorbing) and desorbing greenhouse gases such as CO2, the honeycomb structure may be exposed to an environment heated to 100°C. Therefore, when the spacer 110 has the above-described characteristics in an environment at 100°C, the buffering effect is prevented from decreasing, and the above-described effect can be stably obtained.

[0049] The spacer 110 preferably has a heat resistance temperature of 100°C or higher. As described above, in the process of capturing (adsorbing) and desorbing greenhouse gases such as CO2, the honeycomb structure may be exposed to an environment heated to 100°C. Therefore, by setting the heat resistance temperature of the spacer 110 to 100°C or higher, the above effects can be obtained without deterioration of the spacer 110. The heat resistance temperature of the spacer 110 is determined as follows: First, the spacer 110 is heated at a predetermined temperature in a thermostatic oven for one hour, and then allowed to cool for 30 minutes. Thereafter, the shape, color, and function of the spacer 110 are observed to see if they have changed compared to before they were placed in the thermostatic oven, and the maximum temperature at which no change occurs is defined as the heat resistance temperature.

[0050] It is preferable that the opposing side surfaces 102 of the columnar honeycomb segment 100 are bonded to the spacers 110. By bonding the side surfaces 102 to the spacers 110, it is possible to prevent the spacers 110 from shifting during use. The side surfaces 102 and the spacers 110 may be bonded using an adhesive or the like, or by using spacers 110 having adhesive properties. The spacers 110 having adhesive properties are not particularly limited, but it is sufficient to form the spacers using an adhesive.

[0051] The columnar honeycomb segment 100 has an outer peripheral wall 120 and partition walls 128 disposed inside the outer peripheral wall 120 and defining a plurality of cells 126 extending from a first end face 122 to a second end face 124. The plurality of cells 126 are arranged parallel to one another. The columnar honeycomb segment 100 is a flow-through type in which both end faces (first end face 122 and second end face 124) of each cell 126 are open. When gas (air) containing greenhouse gases flows in from the first end face 122 where the inlets of the plurality of cells 126 are located, the greenhouse gases are adsorbed while passing through the plurality of cells 126, and gas with a reduced greenhouse gas concentration flows out from the second end face 124 where the outlets of the plurality of cells 126 are located.

[0052] The shape of the columnar honeycomb segment 100 is not particularly limited as long as it allows at least a portion of the opposing side surfaces 102 to be in direct or indirect contact with each other. For example, the columnar honeycomb segment 100 can have both end faces (first end face 122 and second end face 124) that are polygonal, such as a square or hexagonal, or round, such as an elliptical, racetrack, or oval, or other irregular shapes. A specific example of a honeycomb structure including columnar honeycomb segments with shapes other than those shown in FIGS. 1A to 2B is shown in FIG. 3. Note that FIG. 3 is a perspective view of the honeycomb structure. It should be noted that this perspective view shows only the outer shape of the columnar honeycomb segment 100, and cells and the like are omitted. The shape of both end faces of the columnar honeycomb segment 100 can be such that the center of the side H2 is located more inward than the end (left view in FIG. 3) or such that the center of the side H2 is located more outward than the end (center view in FIG. 3). As shown in the right diagram of FIG. 3, the columnar honeycomb segment 100 may have a shape in which the shape of both end faces and the size of the cross section at the center between the both end faces are different.

[0053] The length of the columnar honeycomb segment 100 in the direction in which the cells 126 extend (the length from the first end face 122 to the second end face 124) is not particularly limited, and may be set appropriately depending on the required performance, etc. The relationship between the length of the columnar honeycomb segment 100 in the direction in which the cells 126 extend and the maximum diameter of each end face (the maximum length of the diameters passing through the center of gravity of each end face of the columnar honeycomb segment 100) is also not particularly limited. Therefore, the length of the columnar honeycomb segment 100 in the direction in which the cells 126 extend may be longer than the maximum diameter of each end face, or this length may be shorter than the maximum diameter of each end face. However, while a longer length of the columnar honeycomb segment 100 in the direction in which the cells 126 extend can increase the amount of greenhouse gases adsorbed, an excessively long length increases pressure loss. Therefore, the length is preferably 20 to 350 mm, more preferably 30 to 300 mm, and even more preferably 50 to 250 mm.

[0054] There is no particular limitation on the diameter (equivalent circle diameter) of each end face of the columnar honeycomb segment 100. The diameter of each end face of a typical columnar honeycomb segment 100 is 10 to 350 mm, preferably 30 to 300 mm, and more preferably 50 to 250 mm.

[0055] In the columnar honeycomb segment 100, the outer peripheral wall 120 and the partition walls 128 may be made of a material containing an adsorbent capable of adsorbing greenhouse gases, or an adsorbent capable of adsorbing greenhouse gases may be supported on the surfaces of the outer peripheral wall 120 and the partition walls 128. By using such a columnar honeycomb segment 100, greenhouse gases can be adsorbed efficiently. Among these, the columnar honeycomb segment 100 in which the outer peripheral wall 120 and the partition walls 128 are made of a material containing an adsorbent capable of adsorbing greenhouse gases can be manufactured without undergoing a firing process at a high heating temperature, and therefore can reduce CO2 generated during manufacturing and increase the amount of greenhouse gas adsorption.

[0056] When the outer peripheral wall 120 and the partition walls 128 are made of a material containing an adsorbent capable of adsorbing greenhouse gases, the outer peripheral wall 120 and the partition walls 128 can contain an organic binder in addition to the adsorbent capable of adsorbing greenhouse gases. The outer peripheral wall 120 and the partition walls 128 can further contain an inorganic binder as needed. The adsorbent capable of adsorbing greenhouse gases, the organic binder, and the inorganic binder may each be contained singly or in combination of two or more kinds.

[0057] The adsorbent capable of adsorbing greenhouse gases is not particularly limited, but examples thereof include an amino group (-NH, -NHR, -NRR' (R and R' represent organic groups)) and an ammonium group (-NRR'R" +(R, R', and R" represent organic groups.)) can be used. Although the present invention is not intended to be limited by theory, solid organic compounds having one or more selected from amino groups and ammonium groups react with greenhouse gases (e.g., CO2) to form carbamates or bicarbonates, thereby adsorbing the greenhouse gases. Both organic binders and inorganic binders help ensure the strength of the honeycomb structure, but organic binders also contribute to improving formability, and inorganic binders also contribute to improving water resistance and suppressing cracks during drying. While using a water-soluble organic binder is preferable to ensure formability, the inclusion of a water-soluble organic binder in the honeycomb structure reduces water resistance. Therefore, adding a water-insoluble inorganic binder to the honeycomb structure has the effect of suppressing the reduction in water resistance.

[0058] As used herein, "water-insoluble" refers to the property that, when 11 g of a substance to be tested is added to 1 L of water at 20°C and stirred at 500 rpm for 30 minutes, the liquid portion is removed by suction filtration using filter paper type 5C specified in JIS P3801-1995, and the solid portion is dried, the mass is 10 g or more.

[0059] From the viewpoint of achieving a good balance between greenhouse gas adsorption performance, crack suppression during drying, and water resistance, in a preferred embodiment, the content of the solid organic compound having one or more selected from an amino group and an ammonium group in the outer peripheral wall 120 and the partition walls 128 is 30 to 96 mass%, the content of the inorganic binder in the outer peripheral wall 120 and the partition walls 128 is 0 to 30 mass%, and the content of the organic binder in the outer peripheral wall 120 and the partition walls 128 is 3 to 70 mass%. In a more preferred embodiment, the content of the solid organic compound having one or more selected from an amino group and an ammonium group in the outer peripheral wall 120 and the partition walls 128 is 35 to 94 mass%, the content of the inorganic binder in the outer peripheral wall 120 and the partition walls 128 is 0 to 25 mass%, and the content of the organic binder in the outer peripheral wall 120 and the partition walls 128 is 5 to 30 mass%. In an even more preferred embodiment, the content of the solid organic compound having one or more selected from an amino group and an ammonium group in the outer peripheral wall 120 and the partition walls 128 is 40 to 90 mass %, the content of the inorganic binder in the outer peripheral wall 120 and the partition walls 128 is 0 to 20 mass %, and the content of the organic binder in the outer peripheral wall 120 and the partition walls 128 is 5 to 20 mass %.

[0060] The outer peripheral wall 120 and the partition walls 128 may contain components other than the solid organic compound having one or more selected from an amino group and an ammonium group, the inorganic binder, and the organic binder. For example, the outer peripheral wall 120 and the partition walls 128 may contain a surfactant, a pore-forming material, etc. However, in a typical embodiment, the total content of the solid organic compound having one or more selected from an amino group and an ammonium group, the inorganic binder, and the organic binder in the outer peripheral wall 120 and the partition walls 128 is 90% by mass or more. In a more typical embodiment, the total content of the solid organic compound having one or more selected from an amino group and an ammonium group, the inorganic binder, and the organic binder in the outer peripheral wall 120 and the partition walls 128 is 95% by mass or more. Furthermore, the total content of the solid organic compound having one or more selected from an amino group and an ammonium group, the inorganic binder, and the organic binder in the outer peripheral wall 120 and the partition walls 128 may be 99% by mass or more.

[0061] From the viewpoint of water resistance, it is desirable that the solid organic compound having one or more selected from the amino group and the ammonium group is water-insoluble. In addition, the solid organic compound having one or more selected from the amino group and the ammonium group is preferably -NH2, -NHR, -NRR', -NRR'R" + (R, R', and R" represent organic groups), or a combination of two or more of these. Among amino groups and ammonium groups, it is particularly preferable to contain a primary amine (-NH2) as a functional group. The solid organic compound having one or more groups selected from amino groups and ammonium groups also preferably contains an aromatic ring.

[0062] Specific examples of solid organic compounds having one or more 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. Therefore, for example, solid organic compounds having one or more selected from amino groups and ammonium groups can be styrene-based divinylbenzene polymers (e.g., copolymers of styrene and divinylbenzene) having one or more selected from amino groups and ammonium groups, or acrylic copolymers having amino groups (e.g., copolymers of divinylbenzene with one or both of acrylic acid and methacrylic acid). Furthermore, OH-type, Cl-type, and HCO3-type can also be used as the strongly basic anion exchange resin, but for carbon dioxide adsorption applications, OH-type or HCO3-type is preferred.

[0063] From the viewpoint of greenhouse gas 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 greenhouse gas adsorption performance, the exchange capacity of the strongly basic anion exchange resin is preferably 0.6 meq / mL or more, more preferably 0.8 meq / mL or more, and even 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 is passed through.

[0064] Examples of organic binders include methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, hydroxyethyl methyl cellulose, polyvinyl acetal, polyethylene oxide, polyvinyl butyral, polybutadiene, methacrylic acid ester, acrylic, ethyl cellulose, silicone, polyolefin, etc. In particular, the use of water-soluble organic binders such as methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, hydroxyethyl methyl cellulose, polyvinyl acetal, polyethylene oxide, etc. can reduce environmental impact, the risk of organic solvent vapor during drying, and production costs.

[0065] Examples of inorganic binders include one or more inorganic binders selected from fibrous and granular binders, with fibrous inorganic binders being preferred. Inorganic binders are generally water-insoluble, and therefore enhance the water resistance of the columnar honeycomb segment 100. They also suppress cracking during drying. Here, "fibrous" inorganic binders refer to inorganic binders with an average aspect ratio of 3 or greater. "Granular" inorganic binders refer to inorganic binders with an average aspect ratio of less than 3. The average aspect ratio of the inorganic binder is determined by the following procedure: A test piece of the honeycomb structure is cut to an appropriate size, placed in a crucible, and heated to 500°C in an electric furnace to remove organic matter. The remaining inorganic binder is then dispersed on a scanning electron microscope (SEM) sample stage, and the magnification is adjusted to the inorganic binder so that all 20 inorganic binder particles fit within a single field of view. The longest diameter and the shortest diameter of any 20 inorganic binders among them are measured, and the average value of the longest diameter / shortest diameter is taken as the average aspect ratio of the inorganic binder. The longest diameter of one inorganic binder refers to the longest distance between two parallel lines sandwiching the inorganic binder on an SEM image. The shortest diameter of one inorganic binder refers to the shortest distance between two parallel lines sandwiching the inorganic binder on an SEM image.

[0066] Specific examples of inorganic binders include one or more selected from clay, diatomaceous earth, layered clay minerals, montmorillonite, hydrotalcite, activated clay, acid clay, hectorite, halloysite, attapulgite, silica, alumina, talc, chlorite, vermiculite, mica, illite, pyrophyllite, sericite, kaolin, sepiolite, boehmite, palygorskite, and bentonite.

[0067] Among these, the inorganic binder preferably contains one or more selected from sepiolite, boehmite, bentonite, silica, kaolin and talc, and more preferably contains sepiolite.

[0068] Therefore, the total content of one or more selected from sepiolite, boehmite, bentonite, silica, kaolin, and talc in the outer peripheral wall 120 and the partition walls 128 is preferably 0 to 30% by mass, more preferably 0 to 25% by mass, and even more preferably 0 to 20% by mass. Furthermore, the content of sepiolite in the outer peripheral wall 120 and the partition walls 128 is preferably 0 to 30% by mass, more preferably 0 to 25% by mass, and even more preferably 0 to 20% by mass.

[0069] The thickness of the outer peripheral wall 120 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 outer peripheral wall 120 refers to the length in the normal direction of the outer peripheral surface from the boundary between the outer peripheral wall 120 and the outermost cell 126 or partition wall 128 to the outer peripheral surface of the columnar honeycomb segment 100 in a cross section perpendicular to the extension direction of the cells 126.

[0070] The thickness of the partition walls 128 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 128 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 128 is defined as the length of the portion of a line segment connecting the centers of gravity of adjacent cells 126 that passes through the partition wall 128 in a cross section perpendicular to the extension direction of the cells 126. Furthermore, the thickness of the partition walls 128 refers to the average value of the thicknesses of all the partition walls 128 in the columnar honeycomb segment 100.

[0071] It is preferable that the thickness of the outer peripheral wall 120 is the same as that of the partition wall 128. By adopting such a configuration, it is possible to ensure the strength of the columnar honeycomb segment 100, while suppressing an increase in pressure loss and increasing the amount of greenhouse gases adsorbed.

[0072] The total pore volume of the outer wall 120 and the partition wall 128 is, but is not particularly limited to, 0.2 to 1.5 cm 3 / g, and 0.3 to 1.0 cm 3 / g. By controlling the total pore volume within this range, greenhouse gases can be easily diffused into the columnar honeycomb segment 100 through the pores of the outer wall 120 and the partition walls 128, thereby increasing the amount of greenhouse gas adsorption. In this specification, the total pore volume can be measured by mercury intrusion porosimetry using a mercury porosimeter in accordance with JIS R1655:2003.

[0073] The average pore diameter of the outer peripheral wall 120 and the partition walls 128 is not particularly limited, but is preferably 0.1 to 15.0 μm, and more preferably 0.3 to 8.0 μm. By controlling the average pore diameter within this range, greenhouse gases can be easily diffused into the columnar honeycomb segment 100 through the pores of the outer peripheral wall 120 and the partition walls 128, thereby increasing the amount of greenhouse gas adsorption. In this specification, the average pore diameter can be measured by mercury intrusion porosimetry using a mercury porosimeter in accordance with JIS R1655:2003.

[0074] The shape of the cells 126 in a cross section perpendicular to the extension direction of the cells 126 is not particularly limited, but is preferably a rectangle, a hexagon, an octagon, a circle, or a combination thereof. Among these, a square and a hexagon are preferable. By configuring the cells 126 in this shape, an increase in pressure loss when a fluid is flowed through the columnar honeycomb segment 100 can be suppressed.

[0075] The cell density (the number of cells 126 per unit cross-sectional area) of the columnar honeycomb segment 100 is not particularly limited, but from the viewpoint of improving the contact area with gas, it is preferably 30 cells / cm 2 Preferably, the number of cells is 40 or more. 2 From the viewpoint of suppressing an increase in pressure loss, the cell density is more preferably 2000 cells / cm. 2 Preferably, the number of cells per square centimeter is 1200 or less. 2 More preferably, it is 900 cells / cm or less. 2In this specification, the cell density is calculated by dividing the number of cells 126 in the columnar honeycomb segment 100 by the area of ​​one end face of the columnar honeycomb segment 100 excluding the outer peripheral wall 120 .

[0076] The columnar honeycomb segments 100 may have slits on the opposing side surfaces 102. By providing the slits, it is possible to prevent cracks from occurring in the columnar honeycomb segments 100 due to stress caused by adsorption and desorption of greenhouse gases. In addition, the slits allow the greenhouse gases to easily flow between adjacent columnar honeycomb segments 100, which increases the amount of greenhouse gas adsorption.

[0077] FIG. 4A shows a cross-sectional view parallel to the extension direction of the cells 126 of a honeycomb structure including a columnar honeycomb segment 100 with slits. FIG. 4B shows a cross-sectional view of the honeycomb structure shown in FIG. 4A taken along line c-c' (a cross-sectional view perpendicular to the extension direction of the cells 126). In the honeycomb structures shown in FIGS. 4A and 4B, one slit 130 is provided on each of the opposing side surfaces 102. However, the number of slits 130 provided on the opposing side surfaces 102 may be multiple. The positions of the slits 130 on the opposing side surfaces 102 are not particularly limited, but it is preferable that at least some of the slits 130 be provided on the side surfaces 102 that do not overlap with the contact portions 104. This is because the effect of the slits 130 cannot be ensured if they are provided only on the side surfaces 102 that overlap with the contact portions 104.

[0078] As shown in Fig. 4B, the depth L5 of the slits 130 is preferably less than 50% of the length L6 between the side surface 102 on which the slits 130 are formed and the side surface 102 opposite to the side surface 102 on which the slits 130 are formed. By providing slits 130 of such a depth, it is possible to achieve a balance between the strength of the honeycomb structure and the above-described effect of the slits 130. Here, the depth L5 of the slits 130 means the length of the slits 130 in a direction perpendicular to the side surface 102, and refers to the length to the partition wall 128 when the slits 130 and the cells 126 are integrated at their deepest portions.

[0079] 4A and 4B, the shape of the slits 130 can be linear, but may also be curved. The direction in which the slits 130 extend on the opposing side surfaces 102 is not particularly limited, and may be the axial direction X of the columnar honeycomb segment 100 (the direction in which the cells 126 extend) or the direction Y perpendicular to the axial direction X.

[0080] The maximum width of the slits 130 is not particularly limited and may be adjusted appropriately depending on the shape and number of the slits 130, but is preferably 50 mm or less, and more preferably 5 to 15 mm. By controlling the maximum width of the slits 130 within such a range, the strength of the columnar honeycomb segment 100 can be ensured.

[0081] The ratio of the slits 130 to one side surface 102 of the columnar honeycomb segment 100 is preferably 20% or less, and more preferably 5.0 to 15.0%. Furthermore, the total ratio of the contact portions 10 and the slits 130 to one side surface 102 is preferably less than 100%, and more preferably 3.0 to 70.0%. By controlling it to within such a range, it is possible to stably achieve a balance between the strength of the honeycomb structure and the effect of the slits 130 described above.

[0082] (2. Greenhouse Gas Recovery Method and Desorption Method) According to an embodiment of the present invention, there is provided a greenhouse gas recovery method and desorption method using a honeycomb structure. Specifically, a greenhouse gas recovery method according to an embodiment of the present invention includes flowing a gas containing a greenhouse gas through a honeycomb structure, adsorbing the greenhouse gas in the gas by an adsorbent while the gas passes through a plurality of honeycomb structures, and discharging the gas with a reduced greenhouse gas concentration from the honeycomb structure. The gas is not particularly limited as long as it contains a greenhouse gas, particularly CO2, but 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.

[0083] Furthermore, a greenhouse gas desorption method according to an embodiment of the present invention includes flowing a desorbed gas through a honeycomb structure having a greenhouse gas adsorbed therein, and desorbing the greenhouse gas from the adsorbent into the desorbed gas while the desorbed gas passes through the honeycomb structure. The desorbed gas is not particularly limited as long as it is a gas capable of desorbing the greenhouse gas, and may be, for example, water vapor. The water vapor is preferably at a high temperature of 100°C or higher (e.g., 120°C).

[0084] (3. Manufacturing Method of Honeycomb Structure) A preferred example of a manufacturing method of a honeycomb structure according to an embodiment of the present invention will be described below. The manufacturing method of a honeycomb structure according to an embodiment of the present invention includes the steps of manufacturing a plurality of columnar honeycomb segments 100, and arranging the plurality of columnar honeycomb segments 100 so that the side surfaces 102 thereof face each other and at least a portion of the facing side surfaces 102 are in direct or indirect contact with each other. First, the manufacturing step of the columnar honeycomb segment 100 will be described. In the case of a columnar honeycomb segment 100 in which an adsorbent capable of adsorbing greenhouse gases is supported on the surfaces of the outer peripheral wall 120 and the partition walls 128, the columnar honeycomb segment 100 can be manufactured in accordance with a conventional method. Specifically, after manufacturing a columnar honeycomb segment carrier in accordance with a conventional method, a slurry containing an adsorbent capable of adsorbing greenhouse gases can be applied to the carrier and dried, thereby manufacturing the columnar honeycomb segment 100. On the other hand, in the case of a columnar honeycomb segment 100 in which the outer wall 120 and the partition wall 128 are made of a material containing an adsorbent capable of adsorbing greenhouse gases, the manufacturing method includes a process A of kneading a molding raw material containing a solvent, an adsorbent capable of adsorbing greenhouse gases, an organic binder, and an inorganic binder to prepare a puddle, and a process B of molding the puddle into a columnar honeycomb segment 100.

[0085] (Step A) In step A, a forming raw material containing a solvent, an adsorbent capable of adsorbing greenhouse gases, an organic binder, and an inorganic binder is kneaded to prepare a clay. Examples of the solvent (dispersion medium) include water or a mixture of water and an organic solvent such as alcohol, with water being particularly preferred. When using a bead-shaped adsorbent as the adsorbent, pulverizing the bead-shaped adsorbent to a certain size using a ball mill or the like and then kneading the bead-shaped adsorbent makes it easier to control the total pore volume and average pore diameter. The pulverized adsorbent preferably has a median diameter (D50) in the range of 1.0 to 30.0 μm when the cumulative particle size distribution based on the volume is measured using a laser diffraction / scattering method.

[0086] From the viewpoint of achieving a good balance between CO2 adsorption performance, crack suppression during drying, and water resistance, in a preferred embodiment, the content of the adsorbent capable of adsorbing greenhouse gases excluding the solvent in the forming raw material is 30 to 96% by mass, the content of the inorganic binder excluding the solvent in the forming raw material is 0 to 30% by mass, and the content of the organic binder excluding the solvent in the forming raw material is 3 to 70% by mass. In a more preferred embodiment, the content of the adsorbent capable of adsorbing greenhouse gases excluding the solvent in the forming raw material is 35 to 94% by mass, the content of the inorganic binder excluding the solvent in the forming raw material is 0 to 25% by mass, and the content of the organic binder excluding the solvent in the forming raw material is 5 to 30% by mass. In an even more preferred embodiment, the content of the adsorbent capable of adsorbing greenhouse gases excluding the solvent in the forming raw material is 40 to 90% by mass, the content of the inorganic binder excluding the solvent in the forming raw material is 0 to 20% by mass, and the content of the organic binder excluding the solvent in the forming raw material is 5 to 20% by mass.

[0087] The solvent content in the molding material is determined to achieve a clay hardness suitable for extrusion. The clay hardness is preferably in the range of 14 to 26 mm, more preferably 15 to 25 mm, and even more preferably 16 to 24 mm. Herein, clay hardness is measured by the following method. Figure 5 is a diagram illustrating a method for measuring clay hardness using a hardness tester. (a) is an overall view of the hardness tester, (b) is a measurement state when the clay is soft, and (c) is a measurement state when the clay is hard. Figure 6 is an enlarged view showing the shape and dimensions of the tip of the hardness tester. The hardness tester 1 is configured by connecting a conical tip 4 and a support portion 3 via a spring material 2, which are housed in a cylindrical sheath portion 5 (Figure 5(a)). Figure 7 is a graph showing the spring properties of the spring material 2 used in the hardness tester 1. To measure the hardness of the puddle, first, a 20 mm x 20 mm x 20 mm cubic sample is taken from the puddle. The sample is placed on a flat surface, and the tip 4 of the hardness meter 1 is inserted vertically from above into the puddle 6, 7 until the sheath 5 contacts it. The insertion is performed at a sheath speed of 1 mm / s. Next, the length (a1, a2) of the support 3 protruding above the sheath 5 is read 3 seconds after the sheath 5 contacts the puddle 6, 7, and this value (mm) is defined as the hardness of the puddle 6, 7. Therefore, the larger the value, the higher the hardness of the puddle 6, 7. In this specification, the average value of measurements taken at two arbitrary locations is defined as the hardness measurement value of the puddle 6, 7. Note that L0, L1, and L2 indicate the length of the spring material 2. Hardness testers employing such a hardness measurement method are commercially available, and for example, the NGK-type hardness tester (model number: NGK-01) manufactured by NGK Insulators, Ltd. can be used.

[0088] The raw materials for molding 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.

[0089] (Step B) In step B, the clay is formed into a columnar honeycomb segment 100. Typically, in step B, the clay is extrusion-molded into a columnar honeycomb segment 100 having an outer peripheral wall 120 and partition walls 128 disposed inside the outer peripheral wall 120 and defining a plurality of cells 126 extending from a first end face 122 to a second end face 124. In extrusion molding, a die having a desired overall shape, cell shape, partition wall thickness, cell density, etc. can be used.

[0090] Since the columnar honeycomb segment 100 immediately after molding contains a solvent, it is desirable to remove the solvent by a drying process. In the drying process, 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, and dielectric drying, or a combination thereof, are preferred because they can dry the entire molded body quickly and uniformly. From the viewpoint of suppressing decomposition of the adsorbent and organic binder during drying, it is preferable to dry the columnar honeycomb segment 100 in an air atmosphere at 50 to 150°C, more preferably in an air atmosphere at 60 to 140°C, and even more preferably in an air atmosphere at 70 to 130°C. Furthermore, after drying the columnar honeycomb segment 100, the outer periphery may be ground or coated with a ceramic material as needed to finish it into the desired shape.

[0091] When forming the slits 130 on the side surface of the columnar honeycomb segment 100, the method for forming the slits 130 is not particularly limited, and for example, grinding, cutting, laser processing, water jet processing, electric discharge (EDM) processing, etc. can be used. When forming the slits 130 over the entire direction in which the cells 126 extend, a die having a portion corresponding to the slits 130 may be used.

[0092] Next, the side surfaces 102 of the plurality of columnar honeycomb segments 100 obtained above are placed opposite each other so that at least a portion of the opposing side surfaces 102 is in direct or indirect contact with each other. When the opposing side surfaces 102 are placed so that at least a portion of the opposing side surfaces 102 is in indirect contact with each other, spacers 110 may be placed at predetermined positions on the opposing side surfaces 102. As described above, an adhesive may be used as the spacer 110, or the spacer 110 and the side surfaces 102 may be bonded together with an adhesive.

[0093] (4. Greenhouse Gas Recovery Apparatus) A greenhouse gas recovery apparatus according to an embodiment of the present invention includes one or more of the above-described honeycomb structures. Since this greenhouse gas recovery apparatus includes the above-described honeycomb structure, it is possible to increase the amount of greenhouse gas adsorption.

[0094] The greenhouse gas recovery 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 through which a gas containing a greenhouse gas and a desorbed gas can be supplied and discharged. A greenhouse gas recovery device having such a structure can easily achieve the recovery and desorption of greenhouse gases.

[0095] 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.

[0096] Experiment A (Examples 1-29 and Comparative Examples 1-15) Preparation of a prismatic honeycomb segment (hereinafter referred to as an "integrally molded product") whose outer peripheral wall and partition wall are composed of a material containing an adsorbent capable of adsorbing greenhouse gases: Examples 1-26, 28, and 29, Comparative Examples 1-14 A 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 the adsorbent capable of adsorbing greenhouse gases. The adsorbent was pulverized in a ball mill before kneading, and the median diameter (D50) was measured by measuring the cumulative particle size distribution on a volume basis using a laser diffraction / scattering method. The D50 values ​​of the pulverized adsorbents used in each Example and Comparative Example are shown in Tables 1-1 and 1-2. Commercially available methyl cellulose was prepared as organic binder A. Commercially available silicone was prepared as organic binder B. Commercially available sepiolite was prepared as the inorganic binder. Industrial water was used as the solvent, and a commercially available silicone bond (having a durometer type A hardness of 20 after curing) was used as the spacer.

[0097] A molding raw material was obtained by blending an adsorbent capable of adsorbing greenhouse gases (hereinafter abbreviated as "adsorbent"), an organic binder, an inorganic binder, and a solvent. The adsorbent content in the molding raw material, the organic binder content excluding the solvent in the molding raw material, and the inorganic binder content excluding the solvent in the molding raw material were as shown in Tables 1-1 and 1-2. The amount of solvent blended was adjusted so that the clay hardness measured with an NGK hardness tester (model number: NGK-01) manufactured by NGK Insulators, Ltd. was 17 mm. Next, the molding raw material was kneaded for 30 minutes in a vacuum kneader to prepare a clay.

[0098] Next, the obtained clay was molded using an extruder having a predetermined die structure to obtain a quadrangular prism-shaped honeycomb segment in which each cell shape in a cross section perpendicular to the cell extension direction was quadrangular. The obtained quadrangular prism-shaped honeycomb segment was subjected to high-frequency dielectric drying, and then dried for 2 minutes in an air atmosphere at a temperature of 100°C using a microwave dryer, and both end faces were cut to a predetermined length. The obtained quadrangular prism-shaped honeycomb segment had a square end face, with a side length of 120 mm and a length in the cell extension direction of 150 mm. The quadrangular prism-shaped honeycomb segment also had a cell density of 46.5 cells / cm. 2 (300 cells / in 2 ), and the thickness of the partition walls was 203 μm (8 mil). The thickness of the outer wall, the total pore volume and average pore diameter of the outer wall and partition walls are shown in Tables 1-1 and 1-2. The total pore volume and average pore diameter were measured according to the methods described above.

[0099] For the square pillar-shaped honeycomb segments used in Examples 28 and 29, slits were formed on the side surfaces facing other square pillar-shaped honeycomb segments when the honeycomb structures were fabricated. The slits were formed in the square pillar-shaped honeycomb segments using a diamond cutter, extending in the axial direction of the pillar-shaped honeycomb segments. For the square pillar-shaped honeycomb segment used in Example 28, the slit depth was 5% of the length between the side surface on which the slit was formed and the side surface opposite the side surface on which the slit was formed, the proportion of the slits on one side surface was 5%, and the maximum slit width was 5 mm. For the square pillar-shaped honeycomb segment used in Example 29, the slit depth was 49% of the length between the side surface on which the slit was formed and the side surface opposite the side surface on which the slit was formed, the proportion of the slits on one side surface was 19%, and the maximum slit width was 50 mm.

[0100] Next, a plurality of the obtained square pillar-shaped honeycomb segments were prepared, and the side surfaces of the square pillar-shaped honeycomb segments were arranged opposite each other. Spacers were placed at predetermined positions on the opposing side surfaces and assembled to produce a honeycomb structure. By adjusting the position and size of the spacers, the ratio of the contact area to one side surface (hereinafter referred to as the "total contact area ratio"), the length of the contact area in the axial direction X of the square pillar-shaped honeycomb segment (hereinafter referred to as the "axial contact area length"), the ratio of the axial contact area length to the length of the side surface H1 in the axial direction X (hereinafter referred to as the "axial contact area ratio"), the length of the contact area in the direction Y perpendicular to the axial direction X of the square pillar-shaped honeycomb segment (hereinafter referred to as the "orthogonal direction contact area length"), and the ratio of the orthogonal direction contact area length to the length of the side surface H2 in the direction Y (hereinafter referred to as the "orthogonal direction contact area ratio") were controlled to the values ​​shown in Tables 2-1 and 2-2. Here, when determining the thickness of the spacer from the honeycomb structure, measurements are made at one or more locations on the end face of the honeycomb structure using a vernier caliper or the like, and the average of all measurements is used as the result. Furthermore, when determining the length of the contact portion in each direction from the honeycomb structure, the honeycomb structure may be subjected to an X-ray CT inspection and the length of the contact portion in each direction may be determined from the obtained X-ray CT image. Alternatively, the honeycomb structure may be disassembled to determine the thickness of the spacer and the length of the contact portion in each direction.

[0101] In Tables 2-1 and 2-2, the "number of sets" means, for example, in the case of a 3 × 3 arrangement, that a total of nine rectangular pillar-shaped honeycomb segments are provided, with three rectangular pillar-shaped honeycomb segments arranged horizontally and three arranged vertically via spacers. Furthermore, the "axial contact portion position" refers to the position of the contact portion on the side H1 of the side surface in the axial direction X of the rectangular pillar-shaped honeycomb segment, "entire" means a state in which the contact portion is located on the entire side H1, "both ends" means a state in which the contact portion is located on both ends of the side H1, "inlet side" means a state in which the contact portion is located at the gas inflow end of the side H1, "outlet side" means a state in which the contact portion is located at the gas outflow end of the side H1, and "center" means a state in which the contact portion is located at the center of the side H1. Similarly, the "position of the contact portion in the perpendicular direction" is the position of the contact portion on the side H2 of the side surface in the direction Y perpendicular to the axial direction X of the quadrangular pillar-shaped honeycomb segment, "entire" means that the contact portion is located on the entire side H2, "both ends" means that the contact portion is located on both ends of the side H2, and "center" means that the contact portion is located in the center of the side H2.

[0102] <Preparation of a columnar honeycomb segment (hereinafter referred to as "coated product") having an adsorbent capable of adsorbing greenhouse gases supported on the surfaces of the outer wall and partition wall: Example 27 and Comparative Example 15> Alumina, aluminum hydroxide, kaolin, talc, and silica were used as cordierite-forming raw materials. 10 parts by mass of a pore-forming material, 20 parts by mass of a dispersion medium, 1 part by mass of an organic binder, and 0.5 parts by mass of a dispersant were added to 100 parts by mass of this cordierite-forming raw material, and the mixture was mixed and kneaded to prepare a puddle. Water was used as the dispersion medium, coke with an average particle size of 15 μm as the pore-forming material, hydroxypropyl methylcellulose as the organic binder, and ethylene glycol as the dispersant. Next, the obtained puddle was molded using an extruder with a predetermined die structure to obtain a rectangular columnar honeycomb segment molded body in which each cell shape in a cross section perpendicular to the cell extension direction was square. The obtained rectangular pillar-shaped honeycomb segment molded body was dried in a microwave dryer and further dried in a hot air dryer, after which both end faces of the honeycomb molded body were cut and adjusted to the specified dimensions. Next, the obtained rectangular pillar-shaped honeycomb segment molded body was degreased in air at 200 to 1000°C for 3 hours, and then fired in an Ar atmosphere at 1420°C for 2 hours. Next, a slurry containing the same adsorbent as above, ethyl cellulose, was prepared and applied to the partition walls and outer peripheral walls, followed by drying, to obtain a rectangular pillar-shaped honeycomb segment. The obtained rectangular pillar-shaped honeycomb segment had square end faces, with a side length of 120 mm and a length in the cell extension direction of 150 mm. The rectangular pillar-shaped honeycomb segment also had a cell density of 46.5 cells / cm. 2 (300 cells / in 2 The thickness of the outer wall and the content of the adsorbent in the square pillar-shaped honeycomb segment (the proportion of the adsorbent carried in the square pillar-shaped honeycomb segment) are shown in Table 1-2.

[0103] Next, a plurality of the obtained square pillar-shaped honeycomb segments were prepared, and the side surfaces of the square pillar-shaped honeycomb segments were opposed to each other, and spacers were placed at predetermined positions on the opposed side surfaces, and then assembled to produce a honeycomb structure. At this time, the positions and sizes of the spacers were adjusted to control the total contact area ratio, axial contact area length, axial contact area ratio, orthogonal contact area length, and orthogonal contact area ratio to the values ​​shown in Table 2-2.

[0104]

[0105]

[0106]

[0107]

[0108] The honeycomb structures obtained above were evaluated as follows.

[0109] <CO2 Adsorption Amount and CO2 Adsorption Rate> The honeycomb structure was placed in a holder and placed in a sealed container. CO2 sensors were installed on both the inlet and outlet sides of the honeycomb structure. Next, as a pretreatment, nitrogen gas heated to 90-100°C was passed through the honeycomb structure at a flow rate of 500 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 temperature dropped to 25°C (room temperature). After reaching 25°C, air at 25°C was passed at a flow rate of 4900 L / min, and the CO2 adsorption amount was measured until saturation was reached. The saturated CO2 adsorption amount was divided by the mass of the honeycomb structure to determine the CO2 adsorption amount per mass of the honeycomb structure. Note that the above nitrogen gas and air flow rates are for a 3x3 honeycomb structure. In the case of a honeycomb structure with 20 × 20 groups, the flow rate of nitrogen gas was changed to 22,500 L / min and the flow rate of air was changed to 218,000 L / min. In the case of a honeycomb structure with 2 × 2 groups, the flow rate of nitrogen gas was changed to 225 L / min and the flow rate of air was changed to 218 L / min.

[0110] The evaluation of the CO2 adsorption capacity is affected by the number of groups, adsorbent content, total pore volume, average pore diameter, and type of square pillar honeycomb segment, so the comparison criteria were determined as follows. First, structures with the same number of groups and the same adsorbent content, total pore volume, and average pore diameter were compared. For example, the CO2 adsorption capacity of Comparative Example 1 was used as the comparison standard for a honeycomb structure with 3 × 3 groups, the CO2 adsorption capacity of Comparative Example 11 for a honeycomb structure with 20 × 20 groups, and the CO2 adsorption capacity of Comparative Example 12 for a honeycomb structure with 2 × 2 groups. For a structure with an adsorbent content of 96%, the CO2 adsorption capacity of Comparative Example 13 was used as the comparison standard. For a structure with an adsorbent content of 30% and a different total pore volume and average pore diameter, the CO2 adsorption capacity of Comparative Example 14 was used as the comparison standard. For a structure with a coated square pillar honeycomb segment, the CO2 adsorption capacity of Comparative Example 15 was used as the comparison standard. The CO2 adsorption capacity was evaluated using the following evaluation scores for the above comparison criteria. Evaluation score 0: The same as the comparison standard, or the amount of CO2 adsorption is the same as or less than the comparison standard. Evaluation score 1: The increase in the amount of CO2 adsorption is more than 0% and less than 5% compared to the comparison standard. Evaluation score 2: The increase in the amount of CO2 adsorption is 5% or more and less than 10% compared to the comparison standard. Evaluation score 3: The increase in the amount of CO2 adsorption is 10% or more and less than 15% compared to the comparison standard. Evaluation score 4: The increase in the amount of CO2 adsorption is 15% or more and less than 20% compared to the comparison standard. Evaluation score 5: The increase in the amount of CO2 adsorption is 20% or more compared to the comparison standard.

[0111] The CO2 adsorption rate was calculated as the amount of CO2 adsorbed per minute (mol / kg / min) from the amount of CO2 adsorbed from the start of CO2 adsorption until 20 minutes had elapsed. The CO2 adsorption rate was evaluated using the same criteria as for the CO2 adsorption rate evaluation. The CO2 adsorption rate was evaluated using the following scores relative to the above-mentioned criteria. Score 0: The CO2 adsorption rate is the same as the comparison standard, or the CO2 adsorption rate is the same as or slower than the comparison standard. Score 1: The increase in CO2 adsorption rate relative to the comparison standard is greater than 0% and less than 2.5%. Score 2: The increase in CO2 adsorption rate relative to the comparison standard is 2.5% or more and less than 5.0%. Score 3: The increase in CO2 adsorption rate relative to the comparison standard is 5.0% or more and less than 7.5%. Score 4: The increase in CO2 adsorption rate relative to the comparison standard is 7.5% or more and less than 10%. Evaluation score 5: The increase in CO2 adsorption rate is 10% or more compared to the comparison standard.

[0112] <Pressure Loss> After the honeycomb structure was placed in a holder and placed in a sealed container, pressure sensors were installed on the inlet and outlet sides of the honeycomb structure. Next, air at 25°C was flowed at a flow rate of 3,000 kg / hour, and the pressure difference between the inlet and outlet sides was recorded as the pressure loss. The above air flow rates were for a 3x3 honeycomb structure. For a 20x20 honeycomb structure, the air flow rate was changed to 12,440 L / hour. For a 2x2 honeycomb structure, the air flow rate was changed to 124 L / hour. The comparison criteria for pressure loss were determined in the same manner as for the CO2 adsorption amount evaluation. The pressure loss evaluation was performed using the following evaluation scores relative to the comparison criteria: Score 0: The comparison criteria were met, or the pressure difference was the same as or greater than the comparison criteria. Score 1: The pressure difference decreased by more than 0% and less than 1.5% relative to the comparison criteria. Evaluation score 2: The reduction rate of the pressure difference is 1.5% or more and less than 3.0% compared to the comparison standard. Evaluation score 3: The reduction rate of the pressure difference is 3.0% or more and less than 4.5% compared to the comparison standard. Evaluation score 4: The reduction rate of the pressure difference is 4.5% or more and less than 6.0% compared to the comparison standard. Evaluation score 5: The reduction rate of the pressure difference is 6.0% or more and less than 7.5% compared to the comparison standard. Evaluation score 6: The reduction rate of the pressure difference is 7.5% or more and less than 9.0% compared to the comparison standard. Evaluation score 7: The reduction rate of the pressure difference is 9.0% or more and less than 11.5% compared to the comparison standard. Evaluation score 8: The reduction rate of the pressure difference is 11.5% or more and less than 13.5% compared to the comparison standard. Evaluation score 9: The reduction rate of the pressure difference is 13.5% or more and less than 15.0% compared to the comparison standard. Evaluation score 10: The reduction rate of the pressure difference is 15.0% or more compared to the comparison standard.

[0113] <Mechanical Strength> A weight having a predetermined mass (the width of the weight was the same as that of the honeycomb structure) was placed on the honeycomb structure and left for approximately 30 seconds. Similar weights were placed on the other three sides to check for the presence or absence of damage such as cracks. The mechanical strength was measured by repeating the above procedure, increasing the mass of the weight by 2 kg in increments starting from 2 kg. The mass of the weight before damage such as cracks was confirmed was taken as the result of mechanical strength. Mechanical strength was evaluated using the following evaluation scores. Evaluation score 0: Mechanical strength is 4 kg or less. Evaluation score 1: Mechanical strength is 6 to 10 kg. Evaluation score 2: Mechanical strength is 12 to 16 kg. Evaluation score 3: Mechanical strength is 18 to 22 kg. Evaluation score 4: Mechanical strength is 24 to 28 kg. Evaluation score 5: Mechanical strength is 30 kg or more.

[0114] The evaluation results are shown in Tables 3-1 and 3-2.

[0115]

[0116]

[0117] As shown in Tables 3-1 and 3-2, the honeycomb structures of Examples 1 to 29, which had a total contact area ratio of 0.6 to 92.0% and an axial contact area ratio and an orthogonal contact area ratio of 2% or more, all had good results in terms of CO2 adsorption amount, CO2 adsorption rate, pressure loss, and mechanical strength. In contrast, the honeycomb structures of Comparative Examples 1 to 15 had at least one of the total contact area ratio, axial contact area ratio, and orthogonal contact area ratio not satisfying the predetermined range, and therefore at least one of the CO2 adsorption amount, CO2 adsorption rate, and mechanical strength was insufficient.

[0118] [Experiment B (Examples 30 to 44)] A honeycomb structure was produced by preparing a plurality of square pillar-shaped honeycomb segments produced in the same manner as in Example 1, arranging the side surfaces of the square pillar-shaped honeycomb segments opposite each other, and assembling them by arranging spacers at predetermined positions on the opposing side surfaces. At this time, the number of sets, total contact portion ratio, axial contact portion position, axial contact portion length, axial contact portion ratio, orthogonal direction contact portion position, orthogonal direction contact portion length, orthogonal direction contact portion ratio, and spacer thickness were the same as in Example 1, but the type of spacer was changed. Table 4 shows the characteristics of the spacers used, specifically, the load required to compress the spacers by 80% (hereinafter abbreviated as "load required at 80% compression"), a / b (hereinafter abbreviated as "a / b") where a is the thickness in the uncompressed state when not placed on a honeycomb structure and b is the thickness in the compressed state when placed on a honeycomb structure), the compression residual strain (hereinafter abbreviated as "residual compression strain") measured 30 minutes after compressing 80% from the uncompressed state when not placed on a honeycomb structure and holding for 24 hours, and the heat resistance temperature of the spacers (hereinafter abbreviated as "heat resistance temperature"). The load required at 80% compression, a / b, residual compression strain, and heat resistance temperature were determined by the methods described above.

[0119]

[0120] The honeycomb structures obtained above were evaluated as follows.

[0121] <Mechanical Strength> Evaluation was carried out in the same manner as in Experiment A.

[0122] <Retention Performance> After the honeycomb structure was placed on a holder and placed in a sealed container, air at 25°C was flowed at 3,000 kg / hour for 24 hours, and it was evaluated whether the positions of the square pillar-shaped honeycomb segments and spacers constituting the honeycomb structure moved from their initial positions. This evaluation was performed using the following evaluation scores. Evaluation score 0: The square pillar-shaped honeycomb segments, the spacers, or both moved from their initial positions and fell off the holder. Evaluation score 1: The square pillar-shaped honeycomb segments, the spacers, or both moved from their initial positions, but did not fall off the holder. Evaluation score 2: The square pillar-shaped honeycomb segments, the spacers, or both did not move from their initial positions.

[0123] <Cushioning Performance> The honeycomb structure was placed on a holder and placed in a sealed container. A moisture-containing expansion-drying-shrinkage cycle was performed 12 times (for a total of 24 hours) by alternately flowing 3,000 kg / hour of 100°C steam and 3,000 kg / hour of 25°C air for one hour each. The square pillar-shaped honeycomb segments constituting the honeycomb structure were then evaluated for changes from their initial state and cracks. The evaluation was performed using the following evaluation scores. Evaluation score 0: The square pillar-shaped honeycomb segments were deformed from their initial state and cracks were generated, making it impossible for the square pillar-shaped honeycomb segments to maintain their own structure, resulting in the collapse of the honeycomb structure. Evaluation score 1: The square pillar-shaped honeycomb segments were deformed from their initial state and cracks were generated, but the honeycomb structure did not collapse. Evaluation score 2: The square pillar-shaped honeycomb segments were deformed from their initial state, but no cracks were generated. Evaluation score 3: No deformation or cracks occurred in the square pillar-shaped honeycomb segment from the initial state.

[0124] The evaluation results are shown in Table 5.

[0125]

[0126] As shown in Table 5, when a / b was less than 1.0, the retention performance tended to decrease. Furthermore, when a / b was more than 20.0, the compression set was 10% or more, and the heat resistance temperature was less than 100°C, the mechanical strength and cushioning performance tended to decrease.

[0127] REFERENCE SIGNS LIST 1: Hardness tester 2: Spring material 3: Support portion 4: Tip portion 5: Sheath portion 6, 7: Clay a1, a2: Protruding length 100: Columnar honeycomb segment 102: Side surface 104: Contact portion 110: Spacer 120: Outer peripheral wall 122: First end face 124: Second end face 126: Cell 128: Partition wall 130: Slit

Claims

1. A honeycomb structure comprising a plurality of columnar honeycomb segments containing an adsorbent capable of adsorbing greenhouse gases, wherein the side surfaces of the plurality of columnar honeycomb segments are arranged to face each other, and at least a portion of the facing side surfaces are in direct or indirect contact, the proportion of the contact area on one side surface is 0.6 to 92.0%, and the lengths of the contact areas in the axial direction of the columnar honeycomb segments and in a direction perpendicular to the axial direction are each 2% or more of the length of the side of the side surface.

2. The honeycomb structure according to claim 1, wherein at least a portion of the opposing side surfaces are in contact with each other via a spacer.

3. The honeycomb structure according to claim 2, wherein the spacer has a thickness of 0.2 to 10.0 mm.

4. A honeycomb structure according to any one of claims 1 to 3, wherein the length of the contact portion in a direction perpendicular to the axial direction of the columnar honeycomb segment is less than 90% of the length of the side of the side surface.

5. The honeycomb structure according to claim 4, wherein the contact portions are located at the ends and / or centers of the sides of the side surfaces in a direction perpendicular to the axial direction of the columnar honeycomb segments.

6. A honeycomb structure according to any one of claims 1 to 3, wherein the length of the contact portion in the axial direction of the columnar honeycomb segment is 30% or less of the length of the side of the side surface.

7. The honeycomb structure according to claim 6, wherein the contact portions are located at the ends and / or centers of the sides of the side surfaces in the axial direction of the columnar honeycomb segments.

8. A honeycomb structure according to any one of claims 1 to 3, wherein slits are provided on the opposing side surfaces.

9. A honeycomb structure as described in claim 8, wherein at least a portion of the slit is provided on the side surface that does not overlap with the contact portion, the depth of the slit is less than 50% of the length between the side surface on which the slit is formed and the side surface opposite to the side surface on which the slit is formed, the proportion of the slit on one side surface is 20% or less, and the total proportion of the contact portion and the slit on one side surface is less than 100%.

10. The honeycomb structure according to claim 9, wherein the maximum width of the slit is 50 mm or less.

11. A honeycomb structure according to any one of claims 1 to 3, wherein the columnar honeycomb segment has an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells extending from a first end face to a second end face.

12. The total pore volume of the outer wall and the partition wall is 0.2 to 1.5 cm 3 The honeycomb structure according to claim 11, wherein the pore size is 1 / g.

13. A honeycomb structure according to claim 11, wherein the average pore diameter of the outer peripheral wall and the partition walls is 0.1 to 15.0 μm.

14. The honeycomb structure according to claim 11, wherein the thickness of the outer peripheral wall is 0.1 to 4.0 mm.

15. The honeycomb structure according to claim 11, wherein the thickness of the outer peripheral wall and the thickness of the partition wall are the same.

16. The honeycomb structure according to claim 11, wherein the outer peripheral wall and the partition walls are made of a material containing the adsorbent.

17. The honeycomb structure according to claim 11, wherein the adsorbent is supported on the surfaces of the outer peripheral wall and the partition walls.

18. A honeycomb structure according to any one of claims 1 to 3, wherein the content of the adsorbent in the columnar honeycomb segment is 30 to 96 mass %.

19. The honeycomb structure according to claim 2, wherein the spacer has adhesive properties.

20. The honeycomb structure according to claim 2, wherein the spacer is made of a material containing a component capable of adsorbing greenhouse gases.

21. The honeycomb structure according to claim 2, wherein the spacer is made of a material that requires a load of less than 2000 kPa for 80% compression.

22. A honeycomb structure as described in claim 2, wherein the spacers are arranged in the honeycomb structure so that a / b is 1.0 or more and less than 20.0, where a is the thickness of the spacers in an uncompressed state when not arranged in the honeycomb structure and b is the thickness of the spacers in a compressed state when arranged in the honeycomb structure.

23. A honeycomb structure as described in claim 2, wherein the spacer is made of a material that has a compressive residual strain of less than 10% when measured 30 minutes after being compressed 80% from an uncompressed state where it is not placed in the honeycomb structure and held for 24 hours.

24. A honeycomb structure according to claim 2, wherein the heat resistance temperature of the spacer is 100°C or higher.

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