Honeycomb structure and reactor

Abstract

A honeycomb structure according to an embodiment of the present invention includes a honeycomb structural part having an outer wall and a partition wall that is disposed inside the outer wall and that partitions and forms a plurality of cells that extend from a first end surface to a second end surface and serve as fluid flow paths. The cell density of the plurality of cells is more than 233 / cm2 and 3100 / cm2 or less.

Description

Honeycomb structure and reactor

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

[0002] Conventionally, a reactor has been known in which a fluid is introduced into a space in which a catalyst is disposed, and a reaction is promoted by the catalyst. For example, a honeycomb structure having a plurality of cells defined by partition walls, in which the partition walls support a catalyst, can increase the contact area between the catalyst and the fluid and favorably promote the reaction, and is therefore widely used as a reactor for promoting a reaction for purifying automobile exhaust gas (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-170972

[0004] In reactors using conventional honeycomb structures, mass transfer from the fluid to the partition wall surface (and consequently, the catalyst) is insufficient, which can result in insufficient reaction time and yield. One factor affecting mass transfer is the contact area between the fluid and the catalyst, which can be increased by increasing the cell density. However, increasing the cell density tends to increase pressure loss inversely proportional to the square of the hydraulic diameter of the cell. For this reason, honeycomb structures with high cell densities of 1200 cpsi or more have not been thoroughly studied.

[0005] A main object of the present invention is to provide a honeycomb structure that can be suitably used as a reactor by improving mass transfer from a fluid to the partition wall surface.

[0006] [1] According to one aspect of the present invention, there is provided a honeycomb structure part including an outer wall and partition walls disposed inside the outer wall, the partition walls extending from a first end face to a second end face and defining a plurality of cells that serve as fluid flow paths, wherein the cell density of the plurality of cells is 233 cells / cm ２ Over 3100 particles / cm ２ [2] In the honeycomb structure according to the above [1], the cell density of the plurality of cells is 775 cells / cm ２ Over 3100 particles / cm ２[3] The honeycomb structure according to [1] or [2] above may further include a functional material supported on the partition walls. [4] In the honeycomb structure according to [3] above, the partition walls may have a functional layer containing the functional material. [5] In the honeycomb structure according to [3] above, the partition walls may be porous walls having pores, and the functional material may be supported inside the pores of the porous partition walls. [6] In the honeycomb structure according to [3] above, the partition walls may be formed of a material containing the functional material. [7] According to another aspect of the present invention, there is provided a reactor including the honeycomb structure according to any one of [1] to [6] above.

[0007] According to an embodiment of the present invention, by increasing the cell density of the honeycomb structure to a range exceeding 1500 cpsi, mass transfer from the fluid to the partition wall surface (and consequently the catalyst) can be suitably improved.

[0008] 4B is a schematic perspective view showing the configuration of a honeycomb structure according to one embodiment of the present invention. FIG. 4C is a graph showing the relationship between cell density and mass transfer parameter. FIG. 4D is a graph showing the relationship between cell density and contraction dominance parameter. FIG. 4E is a schematic perspective view showing the configuration of a honeycomb structure according to one embodiment of the present invention. FIG. 4F is a schematic cross-sectional view parallel to the extension direction of the fluid inlet channels of the honeycomb structure shown in FIG. 4A. FIG. 4G is a schematic cross-sectional view perpendicular to the extension direction of the fluid inlet channels of the honeycomb structure shown in FIG. 4A. FIG. 4H is a schematic cross-sectional view parallel to the extension direction of the fluid inlet channels of the honeycomb structure according to one embodiment of the present invention. FIG. 4I is a graph showing the relationship between mass transfer parameter and catalytic reaction efficiency based on simulation results.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Furthermore, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Identical elements may be assigned the same reference numerals, and redundant descriptions may be omitted.

[0010] A. Honeycomb Structure A-1. Overall Configuration of Honeycomb Structure Fig. 1 is a schematic perspective view showing the configuration of a honeycomb structure according to one embodiment of the present invention. The honeycomb structure 100A includes a honeycomb structure portion 10 having an outer wall 16 and partition walls 14 disposed inside the outer wall 16 and extending from a first end face 10a to a second end face 10b to define a plurality of cells 12 that serve as fluid flow paths. Depending on the purpose, a functional material can be supported on the honeycomb structure portion 10.

[0011] The number of cells 12 per unit area (hereinafter referred to as "cell density") in a cross section perpendicular to the direction in which the cells 12 of the honeycomb structure part 10 extend (hereinafter also referred to as "length direction") is typically 233 cells / cm. ２ or more than 1500 cpsi. Such a cell density can suitably improve mass transfer from the fluid to the partition wall surface, which can consequently contribute to improving reaction efficiency. Specifically, mass transfer can be improved by increasing the contact area between the fluid and the partition wall. Mass transfer can also be improved by reducing the cell diameter to shorten the distance between the fluid and the partition wall, and in the case of a simple flow path, mass transfer can be improved in inverse proportion to the square of the hydraulic diameter of the cell. Therefore, mass transfer is affected by the geometric area (GSA, unit: cm) of the honeycomb structure. ２ / cm ３ ) and the mass transfer parameter (= GSA / (Hd) using the hydraulic diameter of the cell (Hd, unit: μm) ２ ), and the larger the mass transfer parameter, the better the mass transfer. Here, FIG. 2A shows a graph in which the horizontal axis and the vertical axis represent the cell density and the mass transfer parameter, respectively. As shown in FIG. 2A, there is a generally positive correlation between the cell density and the mass transfer parameter, but the slope of the correlation increases significantly at cell densities of around 1500 cpsi. This indicates that mass transfer can be significantly improved when the cell density exceeds 1500 cpsi compared to when the cell density is 1500 cpsi or less.

[0012] The cell density is preferably 310 cells / cm ２ or greater than 2000 cpsi, preferably 387 particles / cm ２ or greater than 2500 cpsi, preferably 465 particles / cm２ or greater than 3000 cpsi.

[0013] In one embodiment, the cell density is 775 cells / cm ２ Alternatively, it is preferable that the density exceeds 5000 cpsi, for example, 930 particles / cm ２ or greater than 6000 cpsi or 1085 particles / cm ２ or more than 7000 cpsi. Such a cell density can reduce the degree of dominance of contraction pressure loss in the pressure loss of the honeycomb structure, thereby contributing to improved product design flexibility and / or reaction efficiency. Specifically, the pressure loss of the honeycomb structure is expressed as the sum of contraction pressure loss, pipe pressure loss, and divergence pressure loss. The degree of dominance of contraction pressure loss can be evaluated using a "contraction dominance parameter," which is calculated by normalizing the difference between contraction pressure loss (unit: Pa) and divergence pressure loss (unit: Pa). A larger value of the contraction dominance parameter indicates a greater degree of dominance of contraction pressure loss. Figure 2B shows a graph plotting the cell density and the contraction dominance parameter on the horizontal and vertical axes, respectively. As shown in Figure 2B, the contraction dominance parameter increases with increasing cell density up to approximately 5000 cpsi. However, as the cell density increases further, the contraction dominance parameter decreases, i.e., the influence of contraction pressure loss decreases. This is thought to have the following advantages as a reactor. In other words, if the influence of contraction pressure loss is reduced, the increase in the water-stopping area that occurs at the cell inlet can be suppressed. This prevents a decrease in the contact area between the fluid and the reactor, and avoids a decrease in reaction efficiency. In addition, the reduced influence of contraction pressure loss can be used to increase the design freedom of the inlet part to the reactor, allowing for flexibility in the design of the piping shape, layout, etc., making it possible to optimize the efficiency of the entire reactor system.

[0014] The upper limit of the cell density is, for example, 3100 cells / cm ２ When the cell density is in the range of the upper limit or less, the mass transfer effect can be improved while preventing an excessive increase in pressure loss. On the other hand, when the cell density exceeds the upper limit, the manufacturing process may become difficult.

[0015] The GSA of the honeycomb structure 10 is preferably 3000 cm ２ / cm ３ More preferably, 4000 cm ２ / cm ３ or more, and ２ / cm ３ or more than 12,000 cm ２ / cm ３ The GSA may have a viscosity of 22,000 cm or more. ２ / cm ３ or less, more preferably 20,000 cm ２ / cm ３ The GSA is the total internal surface area (S cm ２ ) is the total volume (V cm ３ ) (S / V).

[0016] The hydraulic diameter (Hd) of the cells 12 is preferably 100 μm or more, more preferably 120 μm or more. The hydraulic diameter is preferably 720 μm or less, more preferably 600 μm or less, and may be 300 μm or less or 250 μm or less. The hydraulic diameter is calculated by dividing the cross-sectional area of ​​the cell in a cross section perpendicular to the longitudinal direction of the honeycomb structure by A μm ２ When the perimeter of the cell is B μm, Hd is calculated as Hd=4A / B.

[0017] The open area ratio (OFA) of the multiple cells 12 in a cross section perpendicular to the longitudinal direction of the honeycomb structure section 10 is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. When the open area ratio is in the range equal to or greater than the above lower limit, an increase in pressure loss can be suppressed. Furthermore, as a result of a reduced heat capacity, the energy required to heat the honeycomb structure section 10 can be reduced. From the viewpoint of strength, the open area ratio is preferably 95% or less. The OFA refers to the ratio of the "sum of the cross-sectional areas of all the cells 12" to the sum of the "sum of the cross-sectional areas of the partition walls 14 forming the honeycomb structure section 10" and the "sum of the cross-sectional areas of all the cells 12" in a cross section perpendicular to the longitudinal direction of the honeycomb structure section 10.

[0018] The outer wall 16 typically has a cylindrical shape. The cross-sectional shape of the outer wall 16 perpendicular to the longitudinal direction of the honeycomb structure section 10 is preferably substantially rectangular, but may be other shapes such as other polygons (e.g., triangles, pentagons, hexagons), circles, or ellipses. In the illustrated example, the outer wall 16 is formed integrally with the partition walls 14. The outer wall 16 and the partition walls 14 may also be formed separately. The thickness of the outer wall 16 may be, for example, 0.1 mm to 10 mm.

[0019] The partition walls 14 are typically porous walls having a large number of pores. The porosity and pore size of the partition walls 14 can be set appropriately depending on the purpose. From the viewpoint of strength, the porosity of the partition walls can be, for example, 70% or less, and preferably 10% to 60%. The average pore size is preferably 90% or less, and more preferably 50% or less, of the thickness of the partition walls 14. The average pore size can be, for example, 280 μm or less, preferably 2.5 μm to 225 μm, and more preferably 5.0 μm to 180 μm. The porosity can be measured by, for example, mercury intrusion porosimetry. The average pore size is a value calculated by mercury intrusion porosimetry as the pore size that provides half the total pore volume.

[0020] The thickness of the partition walls 14 is preferably 5 μm or more, more preferably 25 μm or more, and even more preferably 50 μm or more. The thickness of the partition walls 14 is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less, and may be 160 μm or less, 150 μm or less, or 140 μm or less. When the thickness of the partition walls 14 is within the above range, the above cell density can be achieved while ensuring the strength desired for the honeycomb structure. For example, by forming the partition walls to a thickness of about 5 μm, a cell density of about 20,000 cpsi can be achieved.

[0021] Each of the plurality of cells 12 is a space extending from a first end face to a second end face. In the illustrated example, the cross-sectional shape of each cell 12 perpendicular to the length direction is substantially rectangular, but it may be other shapes such as polygonal, circular, elliptical, etc.

[0022] In one embodiment, the honeycomb structure 10 satisfies all of the above-mentioned preferable cell density, opening ratio, and thickness of the partition walls 14. Such a honeycomb structure 10 can significantly improve the mass transfer from the fluid to the partition wall surface, thereby obtaining the effect of improving the reaction efficiency.

[0023] In the honeycomb structure 10, the distance L between the first end face 10a and the second end face 10b (the length of the honeycomb structure 10 or the cell 12) is X cm, and the total opening area of ​​the plurality of cells 12 in a cross section perpendicular to the length direction is Y cm. ２ When Y / X is set as above, Y / X is preferably 30 or more, more preferably 40 or more, and even more preferably 50 or more. When Y / X is equal to or more than the above lower limit, the effect of suppressing an increase in pressure loss can be suitably obtained while ensuring the surface area of ​​the cells 12. The upper limit of Y / X is not particularly limited, but may be, for example, 850,000 or less, or 50,000 or less. The distance L is preferably 0.3 cm to 5 cm, more preferably 0.3 cm to 4 cm, and even more preferably 0.3 cm to 3 cm. The sum Y of the opening areas of the plurality of cells 12 is preferably 5 cm ２ ~250,000 cm ２ , more preferably 10 cm ２ ~250,000 cm ２ , more preferably 100 cm ２ ~160,000 cm ２ is.

[0024] Ceramics are representative examples of materials constituting the honeycomb structure member 10. From the viewpoints of heat resistance and corrosion resistance, preferred examples of ceramics include cordierite, mullite, alumina, zirconia, silicon nitride, silicon carbide, silicon-silicon carbide composite materials, silicon carbide-cordierite composite materials, spinel, lithium aluminum silicate, and aluminum titanate. For example, cordierite, which has a low thermal expansion coefficient, is preferably used from the viewpoint of reducing thermal stress. Furthermore, from the viewpoint of removing or utilizing the heat of reaction from an exothermic reaction, silicon-silicon carbide composite materials, which have high thermal conductivity, are preferably used. Materials constituting the honeycomb structure member 10 include materials other than ceramics, such as paper, paper coated with a protective layer, synthetic paper, and nonwoven fabric, from the viewpoint of facilitating the production of the honeycomb structure member 10. The materials constituting the honeycomb structure member 10 can be used alone or in combination.

[0025] When a functional material is supported on the honeycomb structure section 10, the functional material is typically supported on the partition walls 14 so as to be able to come into contact with a fluid passing through the cells 12. For example, the functional material can be supported on the partition walls 14 by forming a functional layer containing the functional material on the partition wall surface, by supporting the functional material inside the pores of the partition walls, or by forming the partition walls 14 using a material containing the functional material. Note that when a functional layer is formed on the partition wall surface, the OFA is calculated by regarding the functional layer as part of the partition wall.

[0026] The functional material may be any material having an appropriate function depending on the purpose, and examples of the functional material include, but are not limited to, catalysts and adsorbents.

[0027] Specific examples of the catalyst include, but are not limited to, ammonia production catalysts (Fe, Co, Ni, Mo, Ru, etc.), ammonia decomposition catalysts (Ni, Ru, etc.), fuel reforming catalysts (Ge, Mo, Sn, Re, Ir, Pt, etc.), methanation catalysts (Fe, Co, Ni, Mo, Ru, Rh, etc.), methanol synthesis catalysts (Co, Cu, Mo, Rh, Pd, W, Re, Ir, Pt, alkali metal alkoxides, etc.), turquoise hydrogen production catalysts (Fe, Co, Ni, molybdenum carbide, etc.), volatile organic compound (VOC) combustion removal catalysts (Pd, Pt, manganese oxide, Co—Ce composite oxide, perovskite oxide, etc.), and methylcyclohexane synthesis catalysts by toluene hydrogenation (Ni, Ru, Rh, Ir, Pt, etc.).

[0028] Specific examples of adsorbents include, but are not limited to, carbon dioxide adsorbents (porous carbon materials, zeolites, metal organic frameworks, amine compounds, alkali metal carbonates, etc.), moisture absorbents (zeolites, silica gel, activated carbon, alumina, silica, low-crystalline clay, amorphous aluminum silicate complexes, etc.), and adsorbents for allergens, odor components, etc. (zeolites, alumina zinc silicate, silica gel, activated carbon, silica, amorphous aluminum silicate complexes, magnesia, zinc oxide, titanium oxide, metal organic frameworks, etc.).

[0029] A-2. Modification 1 The honeycomb structure may be a joined body including a plurality of honeycomb structure sections arranged adjacent to each other in a direction perpendicular to the longitudinal direction and a joining layer joining the plurality of honeycomb structure sections. When joining a plurality of honeycomb structure sections satisfying the above cell density, the occurrence of cracks can be more effectively prevented than when similar honeycomb structure sections are manufactured with a wider diameter.

[0030] FIG. 3 is a schematic perspective view showing the configuration of a honeycomb structure including four honeycomb structure parts and a bonding layer bonding these parts together.

[0031] The honeycomb structure 100B has four honeycomb structure members 10 and bonding layers 20 that bond the honeycomb structure members 10 together. Each honeycomb structure member 10 has an outer wall 16 and partition walls 14 that are disposed inside the outer wall 16 and extend from a first end face 10a to a second end face 10b to define a plurality of cells 12 that serve as fluid flow paths. The honeycomb structure members 10 preferably have the same length, and are bonded together so that the first end faces 10a are flush with each other and so that the second end faces 10b are flush with each other.

[0032] The honeycomb structure section 10 is as described above. The honeycomb structure sections 10 may have the same structure as each other or different structures. Specifically, in each honeycomb structure section 10, the arrangement, thickness, forming material, etc. of the partition walls 14 may be the same as each other or different from each other, and as a result, the cross-sectional shape, cell density, opening ratio, etc. of the cells 12 may be the same as each other or different from each other.

[0033] The bonding layer 20 can be formed of any appropriate bonding material. For example, a ceramic material with a solvent such as water added to form a paste can be used as the bonding material. The bonding layer 20 may contain the same ceramic as the outer wall 16 and / or the partition wall 14. The outer wall can also be formed by applying the bonding material to the periphery of multiple bonded honeycomb structure parts. The thickness of the bonding layer 20 can be, for example, 0.1 mm to 5 mm.

[0034] A-3. Variation 2 The honeycomb structure may have a configuration including two or more honeycomb structure sections arranged with at least a portion spaced apart so that the inflow end faces or the outflow end faces face each other, with either one of the first end face or the second end face being an inflow end face and the other being an outflow end face, a fluid inflow channel forming the inflow end face-side space of the honeycomb structure section, one end being open and the other being closed, and a fluid outflow channel forming the outflow end face-side space of the honeycomb structure section, one end being open and the other being closed. In the above configuration, the fluid inflow channel and the fluid outflow channel communicate with the plurality of cells at the inflow end face and the outflow end face of the honeycomb structure section, respectively.

[0035] In one embodiment, the two or more honeycomb structure parts are all formed of a forming material with the same composition and have partition walls with the same structure (resulting in the same cell density and opening ratio). In another embodiment, the two or more honeycomb structure parts may be formed of forming materials with different compositions and / or may have partition walls with different structures.

[0036] Figure 4A is a schematic perspective view showing the configuration of an example of a honeycomb structure having the above configuration, Figure 4B is a schematic cross-sectional view parallel to the direction in which the fluid inlet channel of the honeycomb structure shown in Figure 4A extends (cross-sectional view along line A1-A1 in Figure 4A), and Figure 4C is a schematic cross-sectional view perpendicular to the direction in which the fluid inlet channel of the honeycomb structure shown in Figure 4A extends (cross-sectional view along line A2-A2 in Figure 4B).

[0037] The honeycomb structure 100C has opposing fluid inlet end faces 100a and fluid outlet end faces 100b, and includes five honeycomb structure sections 10. Each honeycomb structure section 10 has an inlet end face 10c and an outlet end face 10d, and is arranged spaced apart from one another with the inlet end faces 10c facing each other or with the outlet end faces 10d facing each other. The number of honeycomb structure sections included in the honeycomb structure is not limited to the illustrated example and can be appropriately set depending on the purpose. For example, the number of honeycomb structure sections included in the honeycomb structure can be set so that the total number of fluid inlet channels and fluid outlet channels is preferably 3 to 1,000, more preferably 5 to 500.

[0038] The five honeycomb structure sections 10 are housed in a cylindrical can 110. Specifically, a buffer member 120 is arranged along the inner periphery of the can 110. Positioning members 130, each having recesses corresponding to the length of the honeycomb structure section 10, are arranged at predetermined intervals on both sides of the internal space of the buffer member 120. Plate-shaped holding members 140 are arranged on the top and bottom surfaces of the buffer member 120. Each of the five honeycomb structure sections 10 is fixed by fitting into the recesses of the positioning members 130. The can 110 and the holding members 140 may be made of, for example, a metal material such as stainless steel or a ceramic material such as ferrite. The buffer member 120 may be made of, for example, a ceramic fiber such as alumina fiber or mullite fiber. This configuration allows the honeycomb structure sections 10 to be maintained in a suitable state even when subjected to external impact. However, the configuration of the honeycomb structure is not limited to the illustrated example. For example, the buffer member, the positioning member, and / or the holding member may be omitted depending on the purpose.

[0039] The space between the opposing inlet end faces 10c constitutes the fluid inlet channel 30. Specifically, the fluid inlet channel 30 is defined by two inlet end faces 10c facing each other at a predetermined distance, or by the inlet end face 10c and the holding member 140, and a connecting member connecting them. One end of the fluid inlet channel 30 is open, and the other end is closed by providing a sealing portion 52. In the illustrated example, the positioning members 130 arranged on both side surfaces function as connecting members, but this configuration is not limited thereto. For example, sealing portions may be provided at both ends of the fluid inlet channel in a direction perpendicular to the extension direction, thereby serving as connecting members.

[0040] The space between the opposing outflow end faces 10d constitutes the fluid outflow channel 40. Specifically, the fluid outflow channel 40 is defined by two outflow end faces 10d facing each other at a predetermined distance, or by the outflow end face 10d and a holding member 140, and connecting members (in the illustrated example, positioning members 130 arranged on both side faces) that connect them. One end of the fluid outflow channel 40 is open, and the other end is closed by the provision of a sealing portion 54.

[0041] The fluid inlet channel 30 communicates with a plurality of cells 12 at the inlet end face 10 c, and the fluid outlet channel 40 communicates with a plurality of cells 12 at the outlet end face 10 d. With this configuration, fluid that flows into the fluid inlet channel 30 from an open end flows into the cells 12 from the inlet end face 10 c, flows out from the outlet end face 10 d, moves to the fluid outlet channel 40, and can flow out from the open end. Furthermore, two adjacent honeycomb structure sections 10 can share the fluid inlet channel 30 and / or the fluid outlet channel 40.

[0042] From the viewpoint of efficiently allowing a fluid to flow in and out of the honeycomb structure 100C, it is preferable that the fluid inlet channel 30 and the fluid outlet channel 40 extend in opposite directions. The angle formed between the extension direction of the fluid inlet channel 30 (in other words, the direction from the open-side end toward the closed-side end) and the extension direction of the fluid outlet channel 40 (in other words, the direction from the open-side end toward the closed-side end) is, for example, in the range of 180°±30°, and preferably in the range of 180°±25°.

[0043] 4A to 4C, the honeycomb structure members 10 are arranged in parallel so that the distance between the opposing inlet end faces 10c or outlet end faces 10d is constant, thereby forming fluid inflow channels or fluid outflow channels. Unlike the illustrated example, each honeycomb structure member 10 may be arranged obliquely relative to an adjacent honeycomb structure member 10 so that the distance between the opposing inlet end faces 10c or outlet end faces 10d gradually increases or decreases. For example, two opposing honeycomb structure members 10 may be arranged so that the inlet end faces 10c or the outlet end faces 10d are spaced apart at one end and in contact at the other end, thereby forming one end open and the other end closed.

[0044] The angle formed by the extending direction of the inlet end face 10c or the extending direction of the outlet end face 10d facing each other may be, for example, in the range of 0°±30°, and preferably in the range of 0°±25°. When the angle is within the above range, a space-saving effect can be suitably obtained.

[0045] A-4. Modification 3 The honeycomb structure may be configured so that the honeycomb structure portion can be heated. For example, the honeycomb structure may have a magnetic material supported on the honeycomb structure and a coil wiring arranged to surround the outer periphery of the outer wall. With this configuration, the honeycomb structure portion can be induction heated by passing an AC current through the coil wiring.

[0046] The magnetic body is preferably a magnetic material having a maximum magnetic permeability of 10,000 or more. Specific examples of the magnetic body include balance Fe-10% Si-5% Al, 49% Co-49% Fe-2% V, balance Fe-36% Ni, and balance Fe-45% Ni.

[0047] The magnetic material can be supported on the honeycomb structure by, for example, being disposed in some of the cells, or by forming partition walls or bonding layers containing magnetic material particles.

[0048] A-5. Manufacturing method of honeycomb structure The above honeycomb structure can be typically manufactured by a method including a molding step of extruding a molding material containing a ceramic raw material to obtain a honeycomb formed body, and a firing step of drying the honeycomb formed body and firing the resulting dried honeycomb body to obtain a honeycomb structure part.

[0049] In the molding process, typically, the molding material is extruded through a die having slits corresponding to the partition walls of the honeycomb structure to obtain a cylindrical honeycomb molded body having partition walls and outer walls that define cells that serve as fluid flow paths. By selecting an appropriate die and tool, the shape and density of each cell, as well as the shapes and thicknesses of the partition walls and outer walls, can be controlled. Furthermore, by employing a bracing structure, triangular cells, or other configurations, it is possible to achieve both favorable cell density and strength.

[0050] The molding material typically includes a ceramic raw material. As the ceramic raw material, powder of the above-mentioned ceramics, raw material powder that becomes the above-mentioned ceramics upon firing (for example, cordierite raw material), etc. can be used. The cordierite raw material is a raw material that becomes cordierite upon firing. The cordierite raw material is alumina (Al ２ O３ ) (including aluminum hydroxide converted to alumina): 30% to 45% by mass, magnesia (MgO): 11% to 17% by mass, and silica (SiO ２ Preferably, the molding material has a chemical composition of 42% by mass to 57% by mass of ceramic raw materials. The molding material may further contain a binder, a pore-forming agent, a dispersant, water, an organic solvent, etc. In addition, by blending a functional material with the molding material, a honeycomb structure (specifically, partition walls and outer walls) formed from a material containing the functional material can be obtained. The porosity and pore size of the honeycomb structure can be controlled by appropriately selecting the type and amount of the ceramic raw material, binder, pore-forming agent, and dispersant.

[0051] The honeycomb formed body is dried to obtain a dried honeycomb body. Before drying, the honeycomb formed body may be cut to a predetermined length.

[0052] Examples of drying methods for the honeycomb formed body include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying. These may be used alone or in combination of two or more. Among these, a drying method that combines hot air drying with microwave drying or dielectric drying is preferred because it can dry the entire honeycomb formed body quickly and uniformly.

[0053] The dried honeycomb body is fired to obtain a honeycomb structure part. Any appropriate firing conditions can be adopted. The firing temperature is, for example, 1400°C to 1500°C. The firing time is, for example, 20 hours to 80 hours. The firing may be carried out continuously or in multiple stages at different temperatures. When firing is carried out in multiple stages, the firing time is the sum of the firing times of each stage.

[0054] Before the dried honeycomb body is subjected to the firing treatment, the dried honeycomb body may be calcined. The calcination temperature may be determined, for example, depending on the combustion temperature of the organic matter contained in the dried honeycomb body. The calcination temperature is, for example, 200°C to 1000°C. The calcination time is, for example, 10 hours to 100 hours. Note that the calcination and firing may be carried out consecutively. Specifically, the calcination may be carried out during the temperature rise process of firing.

[0055] The above-mentioned manufacturing method may further include a functional material supporting step of supporting a functional material on the honeycomb structure portion, if necessary. The functional material supporting step is preferably carried out after the firing step.

[0056] Any appropriate method can be used to support a functional material on a honeycomb structure. For example, a functional layer containing a functional material can be formed on the partition wall surfaces and / or pore inner surfaces by a method including: immersing a honeycomb structure in a functional material dispersion containing a functional material, a binder, and a dispersion medium to form a coating layer on the partition wall surfaces and / or pore inner surfaces; or flowing a functional material dispersion through the cells of the honeycomb structure to form a coating layer on the partition wall surfaces and / or pore inner surfaces; and drying the coating layer. When immersing a honeycomb structure in a functional material dispersion, the functional material dispersion adhering to the end faces and outer wall surfaces of the honeycomb structure after immersion can be removed by blowing, wiping, or the like. The drying temperature can be, for example, 120°C to 600°C. The formation of the functional layer (i.e., the formation and drying of the coating layer) can be performed only once or can be repeated multiple times. By repeating the process multiple times, a desired amount of functional material can be preferably supported on the honeycomb structure. In this manner, partition walls carrying a functional material on the surface and / or inside the pores can be obtained.

[0057] Examples of the dispersion medium include water, organic solvents (e.g., toluene, xylene, ethanol, n-butanol, ethyl acetate, butyl acetate, terpineol, dihydroterpineol, Texanol, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether acetate, and diethylene glycol monobutyl ether), and mixtures thereof.

[0058] A honeycomb structure having a plurality of honeycomb structure parts bonded via a bonding layer can be produced by a method including the steps of: producing a plurality of honeycomb structure parts as described above; applying a bonding material to the outer walls of the honeycomb structure parts to form a coating layer; assembling the plurality of honeycomb structure parts via the coating layer to produce an assembly; and drying the assembly to form the coating layer as a bonding layer. There are no particular limitations on the bonding material, and any material for forming a bonding layer in a conventionally known honeycomb structure can be used.

[0059] A honeycomb structure including two or more honeycomb structure sections arranged with at least a portion spaced apart so that their inflow end faces or outflow end faces face each other, a fluid inflow channel, and a fluid outflow channel can be manufactured by a method further including arranging the two or more honeycomb structure sections at predetermined positions in a can body, if necessary, using a buffer member, a holding member, a positioning member, a pressing member, etc. The manufacturing method can further include providing a plug at one end of the fluid inflow channel or the fluid outflow channel.

[0060] The method for accommodating the plurality of honeycomb structure portions in predetermined positions in the can body is not particularly limited, and any known method can be used. For example, in addition to fixing methods using fitting such as clearance fitting, interference fitting, and shrink fitting, brazing, welding, diffusion bonding, etc. can be used.

[0061] Alternatively, the honeycomb structure may be manufactured by a method including: preparing a honeycomb structure member having a long cell length and a rectangular prism shape; and then slitting the resulting honeycomb structure member from opposing outer wall surfaces alternately in a direction intersecting the cell extension direction to form slit portions. The slitting is performed so that a predetermined distance of honeycomb structure members remains. This method can produce a honeycomb structure 100D, as shown in FIG. 5 , having two or more honeycomb structure members 10 (six in the illustrated example) integrally formed with slit remaining portions 62 connecting adjacent honeycomb structure members 10. Since one end of the slit portion 60 is open and the other end is closed, the slit portion 60 can function as a fluid inlet channel 30 or a fluid outlet channel 40. The slit remaining portions 62 can also function as plugs.

[0062] B. Reactor The honeycomb structure described in Section A can be used as a reactor for carrying out various reactions. When the honeycomb structure itself does not have a configuration capable of heating the honeycomb structure portion, the reactor may include, in addition to the honeycomb structure, a heating device (e.g., an electric heater) arranged in contact with or in close proximity to the honeycomb structure. Heating the honeycomb structure can promote chemical reactions, adsorption / desorption reactions, etc.

[0063] [Trends in Mass Transfer Parameters in Simulation] For a honeycomb structure including a honeycomb structure part in which a catalyst is supported on the partition walls, the total hydrocarbon (THC) conversion efficiency was simulated by varying the GSA of the honeycomb structure part and the hydraulic diameter of the cells, assuming vehicle driving under specified conditions. Figure 6 shows a graph in which the mass transfer parameters and the conversion efficiency obtained by the simulation are normalized and plotted on the X axis and the Y axis, respectively.

[0064] As shown in FIG. 6, the THC conversion rate (in other words, catalytic reaction efficiency) increased as the mass transfer parameter increased.

[0065] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations shown in the above-described embodiment can be replaced with configurations that are substantially the same as those shown in the above-described embodiment, that have the same effects, or that can achieve the same purpose.

[0066] The honeycomb structure according to the embodiment of the present invention can be suitably used as various reactors.

[0067] 10 honeycomb structure portion, 10a first end face, 10b second end face, 10c inlet end face, 10d outlet end face, 12 cell, 14 partition wall, 16 outer wall, 30 fluid inlet channel, 40 fluid outlet channel, 100A-D honeycomb structure.

Claims

1. A honeycomb structure part having an outer wall and partition walls arranged inside the outer wall and extending from a first end face to a second end face to define a plurality of cells that serve as fluid flow paths, wherein the cell density of the plurality of cells is 233 cells / cm ２ Over 3100 particles / cm ２ Below is a honeycomb structure.

2. The cell density of the plurality of cells is 775 cells / cm ２ Over 3100 particles / cm ２ The honeycomb structure according to claim 1, wherein:

3. The honeycomb structure according to claim 1, further comprising a functional material carried on the partition walls.

4. The honeycomb structure according to claim 3, wherein the partition walls have a functional layer containing the functional material.

5. The honeycomb structure according to claim 3, wherein the partition walls are porous partition walls having pores, and the functional material is supported inside the pores of the porous partition walls.

6. The honeycomb structure according to claim 3, wherein the partition walls are formed of a material containing the functional material.

7. A reactor comprising the honeycomb structure according to any one of claims 1 to 6.

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