Honeycomb structure

Abstract

This invention provides a honeycomb structure with high isostatic strength and the ability to reduce pressure loss. The honeycomb structure (4) has a columnar honeycomb structure (4) with a porous partition wall (1) arranged to surround a plurality of cells (2) and an outer peripheral wall (3) arranged to surround the partition wall (1). The plurality of cells (2) extend from a first end face (11) to a second end face (12) and become a flow path for fluid. In a cross section of the honeycomb structure (4) orthogonal to the direction of extension of the cells (2), the shape of the cells (2) is a polygon with arc-shaped corners (6). The thickness T1 (mm) of the partition wall (1) is 0.0500 to 0.1400 mm. The radius of curvature R1 (mm) of the arc-shaped corners (6) of the cells (2) and the thickness T1 (mm) of the partition wall (1) satisfy the following relationship (1). The outer diameter of the honeycomb structure (4) is 190.5 to 355.6 mm and the porosity of the partition wall (1) is 20 to 40%. Equation (1): 0.0050≤R1×T1≤0.0150.

Description

Technical Field

[0001] This invention relates to honeycomb structures. More specifically, it relates to honeycomb structures with high isostatic strength and capable of reducing pressure loss. Background Technology

[0002] In recent years, with increased public awareness of environmental issues, various technologies have been developed in the field of fuel combustion to remove harmful components such as nitrogen oxides (hereinafter also referred to as "NOx") from exhaust gases produced during fuel combustion. For example, various technologies have been developed to remove harmful components such as NOx from exhaust gases emitted by diesel vehicle engines. In such removal of harmful components from exhaust gases, catalysts are typically used to chemically react the harmful components into other, less harmful components. Furthermore, honeycomb structures (for example, see Patent Document 1) are used as catalyst carriers for supporting catalysts used in exhaust gas purification.

[0003] For example, various technologies for treating NOx in exhaust gases have been proposed to address the aforementioned NOx limitations. One such technology involves supporting a selective catalytic reduction catalyst (hereinafter also referred to as "SCR catalyst") on a honeycomb structure with porous walls, and using this honeycomb structure to purify NOx in the exhaust gas. The honeycomb structure supporting the SCR catalyst uses ammonia (NH3) generated from the decomposition of urea injected from a urea injector located upstream of it to reduce NOx in the exhaust gas.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-052367 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Previously, in exhaust gas purification devices used to remove NOx from the exhaust gases emitted by diesel vehicle engines, when using honeycomb structures carrying SCR catalysts, two honeycomb structures were sometimes arranged in series relative to the exhaust gas flow direction. While this method achieved high NOx removal performance, it also resulted in increased pressure loss.

[0009] As a method to reduce pressure loss in honeycomb structures, techniques related to "thinning" the walls of the honeycomb structure have been studied. However, with thinning of the walls, problems arise such as deformation of the walls during manufacturing, leading to cell crushing (hereinafter also referred to as "cell distortion"). Furthermore, techniques to improve the isostatic strength of honeycomb structures by shaping the cells into polygons with rounded corners have been investigated. However, when the cell shape is shaped into a polygon with rounded corners, the pressure loss of the honeycomb structure increases. Thus, in the various techniques studied previously, the reduction of pressure loss and the increase of isostatic strength are mutually exclusive, making it extremely difficult to achieve both simultaneously.

[0010] This invention was made in view of the problems inherent in the prior art. The invention provides a honeycomb structure that exhibits high isostatic strength even with a large outer diameter and achieves reduced pressure loss.

[0011] Methods for solving problems

[0012] According to the present invention, a honeycomb structure as shown below is provided.

[0013] [1] A honeycomb structure having a columnar honeycomb structure portion having a porous partition wall arranged to surround a plurality of cells and an outer peripheral wall arranged to surround the partition wall, wherein the plurality of cells extend from a first end face to a second end face and become a flow path for fluid.

[0014] In a cross-section of the aforementioned honeycomb structure orthogonal to the direction in which the aforementioned lattice extends, the shape of the aforementioned lattice is a polygon with arc-shaped corners.

[0015] The thickness T1 (mm) of the aforementioned partition wall is 0.0500~0.1400mm.

[0016] The radius of curvature R1 (mm) of the arc-shaped corner of the aforementioned lattice and the thickness T1 (mm) of the aforementioned partition wall satisfy the following relationship (1).

[0017] In the cross-section of the honeycomb structure portion orthogonal to the direction of the extension of the aforementioned pores, the outer diameter of the honeycomb structure portion is 190.5–355.6 mm.

[0018] The porosity of the aforementioned partition wall is 20-40%.

[0019] Equation (1): 0.0050 ≤ R1 × T1 ≤ 0.0150

[0020] [2] According to the honeycomb structure described in [1] above, in the cross section of the honeycomb structure portion that is orthogonal to the direction of the extension of the pores, the shape of the pores is a quadrilateral shape with the arc-shaped corners.

[0021] [3] The honeycomb structure as described in [1] or [2] above, wherein the pore density of the honeycomb structure is 30 to 140 pores / cm². 2 .

[0022] Invention Effects

[0023] The honeycomb structure of the present invention has the following effects: even with a large outer diameter, it has high isostatic strength and can reduce pressure loss. Attached Figure Description

[0024] Figure 1 This is a perspective view taken from the first end face, schematically illustrating one embodiment of the honeycomb structure of the present invention.

[0025] Figure 2 It is a schematic representation Figure 1 A top view of the first end face of the honeycomb structure shown.

[0026] Figure 3 It is a schematic representation Figure 2 An enlarged schematic top view of a portion of the first end face of the shown honeycomb structure.

[0027] Figure 4 It is a schematic representation Figure 2 A cross-sectional view of section A-A'. Detailed Implementation

[0028] The embodiments of the present invention will now be described. However, the present invention is not limited to the following embodiments. Therefore, it should be understood that appropriate changes and modifications can be made to the following embodiments based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0029] (1) Honeycomb structure:

[0030] Reference Figures 1-4 An embodiment of the honeycomb structure of the present invention will be described. One embodiment of the honeycomb structure of the present invention is a honeycomb structure 100 having columnar honeycomb structure portions 4, wherein the honeycomb structure portion 4 has porous partition walls 1 arranged to surround a plurality of cells 2 and an outer peripheral wall 3 arranged to surround the partition walls 1. Here, Figure 1 This is a perspective view taken from the first end face, schematically illustrating one embodiment of the honeycomb structure of the present invention. Figure 2 It is a schematic representation Figure 1A top view of the first end face of the honeycomb structure shown. Figure 3 It is a schematic representation Figure 2 An enlarged schematic top view of a portion of the first end face of the shown honeycomb structure. Figure 4 It is a schematic representation Figure 2 A cross-sectional view of section A-A'.

[0031] The porous partition wall 1 constituting the honeycomb structure 4 is arranged to surround a plurality of pores 2 extending from the first end face 11 to the second end face 12. In this invention, a pore 2 refers to a space divided by the partition wall 1. The plurality of pores 2 serve as flow paths for fluid. The outer peripheral wall 3 is arranged around the partition wall 1, which is arranged in a lattice shape to surround the plurality of pores 2. The honeycomb structure 100 can be suitable for use as a catalyst support for carrying a catalyst for exhaust gas purification. A catalyst support is a porous structure that supports the particles of the catalyst.

[0032] In this embodiment, in a cross-section of the honeycomb structure 100 orthogonal to the direction in which the lattice 2 extends, the lattice 2 is polygonal in shape with arc-shaped corners 6. Specifically, as... Figure 4 As shown, in the honeycomb structure 100 of this embodiment, the shape of the cell 2 is a quadrilateral shape with arc-shaped corners 6. Hereinafter, "polygonal shape with arc-shaped corners 6" is sometimes referred to as "approximately polygonal shape," and "quadrilateral shape with arc-shaped corners 6" is sometimes referred to as "approximately quadrilateral shape." For example, in a cross section of the honeycomb structure section 4 orthogonal to the direction in which the cell 2 extends, a plurality of cells 2 are arranged in a quadrilateral grid shape along a first direction (e.g., the vertical direction of the paper) and a second direction orthogonal to the first direction (e.g., the horizontal direction of the paper). Moreover, the intersection 5 of the quadrilateral grid is formed by the arc-shaped corners 6 of each of the four cells 2 arranged in the quadrilateral grid shape. It should be noted that, as described above, the cell 2 refers to the space surrounded by the partition wall 1. Therefore, relative to the shape of the cell 2, having arc-shaped corners 6 means that a portion of the space of the cell 2 that forms the corner of the quadrilateral shape is occupied by the partition wall 1 surrounding the cell 2.

[0033] The thickness T1 (mm) of the partition 1 of the honeycomb structure 100 is 0.0500 mm or more. The thickness of the partition 1 is the length of the partition 1 that divides the cross-section of the honeycomb structure portion 4 into two cells 2, in a direction orthogonal to the surface. Here, when measuring the thickness of the partition 1, "the partition 1 that divides the two cells 2" is defined as excluding the thickness of the partition 1 corresponding to the portion corresponding to the arc-shaped corner 6 constituting the cell 2. That is, as described above, unless otherwise specified, the term "thickness of the partition 1" does not include the thickness of the intersection portion 5 of the partition 1, but rather the thickness of the partition 1 that divides the portion that divides the four sides of the main outline of the approximately quadrilateral cell 2. The thickness of the partition 1 can be measured, for example, using a microscope.

[0034] The thickness T1 (mm) of the partition 1 can be 0.0500 to 0.1400 mm, preferably 0.0630 to 0.1400 mm, and more preferably 0.0635 to 0.0889 mm (i.e., 63.5 to 88.9 μm). If the thickness T1 (mm) of the partition 1 is less than 0.0500 mm, the intersection portion 5 in the partition 1 becomes too large when the relationship of the following formula (1) is satisfied. During manufacturing, the blank used for molding is concentrated at the intersection portion 5, and poor molding is easily generated in the partition 1 outside the intersection portion 5. If poor molding occurs in the partition 1 in this way, the isostatic compressive strength will be significantly reduced. In addition, if the thickness T1 (mm) of the partition 1 is less than 0.0500 mm, the partition 1 will deform during manufacturing, and the pore distortion is easily generated. On the other hand, if the thickness T1 (mm) of the partition 1 exceeds 0.1400 mm, the pressure loss of the honeycomb structure 100 will increase.

[0035] Furthermore, in the honeycomb structure 100, the radius of curvature R1 (mm) of the arc-shaped corner 6 of the lattice 2 and the thickness T1 (mm) of the partition 1 satisfy the relationship of the following equation (1). With this configuration, even with a large outer diameter, the isostatic compressive strength is high, and pressure loss can be reduced. For example, the generation of lattice distortion associated with the thinning of the partition 1 of the honeycomb structure 100 can be effectively suppressed, and the increase in pressure loss of the honeycomb structure 100 can also be effectively suppressed. For example, if the value of “R1×T1” in equation (1) is less than 0.0050, the isostatic compressive strength of the honeycomb structure 100 decreases. On the other hand, if the value of “R1×T1” in equation (1) exceeds 0.0150, the pressure loss of the honeycomb structure 100 increases.

[0036] Equation (1): 0.0050 ≤ R1 × T1 ≤ 0.0150

[0037] The radius of curvature R1 (mm) of the arc-shaped corner 6 of the cell 2 can be determined by the following method. First, a cross-section of the honeycomb structure 100 orthogonal to the direction in which the cell 2 extends is photographed. Based on the photographed cross-sectional image of the honeycomb structure 100, the portion constituting the arc-shaped corner 6 with curvature is identified. Specifically, two points corresponding to each endpoint of the arc-shaped corner 6 are found as follows. One end of the arc-shaped corner 6 is defined as a point corresponding to the boundary of the straight side of the main shape of the arc-shaped corner 6 and the main shape of the generally polygonal cell 2. The other end of the arc-shaped corner 6 is defined as a point corresponding to the boundary of the other straight side of the arc-shaped corner 6 and the main shape of the generally polygonal cell 2. Thus, after finding two points corresponding to each endpoint of the arc-shaped corner 6, a midpoint equidistant from the two points at the other end is found on the curved portion of the arc-shaped corner 6. Then, the radius of the circle connecting the three points of the arc-shaped corner 6—one end, the middle point, and the other end—is called the radius of curvature R1 of the arc-shaped corner 6. The radius of curvature R1 of the corner 6 is a value measured by an optical microscope.

[0038] Regarding the specific value of the radius of curvature R1 (mm) of the arc-shaped corner 6 of the grid 2, there are no particular restrictions as long as the thickness T1 (mm) of the partition wall 1 is 0.0500 to 0.1400 mm and satisfies the above formula (1). For example, the radius of curvature R1 (mm) of the arc-shaped corner 6 of the grid 2 is preferably 0.0700 to 0.1500 mm, and more preferably 0.0700 to 0.1200 mm.

[0039] In this embodiment, the outer diameter D1 (mm) of the honeycomb structure 100 in a cross-section orthogonal to the direction of extension of the cellular grid 2 is 190.5 to 355.6 mm, preferably 190.5 to 266.7 mm. In particular, when the outer diameter D1 (mm) of the honeycomb structure 100 is relatively large, as described above, the generation of cellular grid distortion associated with the thinning of the partition walls 1 of the honeycomb structure 100 can be suppressed extremely effectively. Furthermore, if the outer diameter D1 (mm) of the honeycomb structure 4 is less than 190.5 mm, the pressure loss of the honeycomb structure 100 increases. If the outer diameter D1 (mm) of the honeycomb structure 4 exceeds 355.6 mm, breakage and deformation are more likely to occur during processing, resulting in a decrease in isostatic compressive strength, which is undesirable.

[0040] The porosity of the partition walls 1 of the honeycomb structure portion 4 of the honeycomb structure 100 is 20-40%, preferably 30-35%. If the porosity of the partition walls 1 is too low, catalyst peeling is likely to occur when used as an exhaust gas purification device, which is undesirable. If the porosity of the partition walls 1 is too high, the strength of the honeycomb structure portion 4 becomes insufficient, and it is sometimes difficult to hold the honeycomb structure 100 with sufficient holding force when it is housed in the tank of the exhaust gas purification device. The porosity of the partition walls 1 is a value measured by a mercury porosimeter. For example, the Autopore 9500 (trade name) manufactured by Micromeritics can be cited as a mercury porosimeter.

[0041] The cell density of the honeycomb structure portion 4 of the honeycomb structure 100 is preferably 30 to 140 cells / cm². 2 More preferably, 31–93 cells / cm 2 With this configuration, it can be appropriately used as a filter for capturing particulate matter (PM) in exhaust gases emitted from automobile engines, etc. If the pore density is too small, the isostatic pressure may decrease; if the pore density is too large, the pressure loss may increase.

[0042] There are no particular restrictions on the material of partition 1. For example, ceramics can be used as a material for partition 1. Particularly preferred materials include silicon carbide, silicon-bonded silicon carbide, sintered ceramic materials with binders, mullite, cordierite, or aluminum titanate. It should be noted that "silicon-bonded silicon carbide" refers to a substance in which silicon carbide particles, for example, are bonded together with metallic silicon. Furthermore, "sintered ceramic materials with binders" refers to ceramic materials made by sintering substances in which aggregates such as silicon carbide and mullite are bonded together with binders such as cordierite.

[0043] There are no particular limitations on the overall shape of the honeycomb structure 100. Preferably, the first end face 11 and the second end face 12 of the honeycomb structure 100 are circular or elliptical, with a circular shape being particularly preferred. Furthermore, there are no particular limitations on the size of the honeycomb structure 100, such as the length of the honeycomb structure portion 4 from the first end face 11 to the second end face 12. When using the honeycomb structure 100 as a catalyst carrier or other waste gas purification component for carrying a catalyst for waste gas purification, it can be appropriately selected in a manner that yields optimal purification performance.

[0044] Next, a method for manufacturing the honeycomb structure of this embodiment will be described. However, the method for manufacturing the honeycomb structure is not limited to the manufacturing method described below.

[0045] First, a plastic clay for making the honeycomb structure is prepared. The clay for making the honeycomb structure can be prepared by appropriately adding additives such as binders and water to materials selected from the aforementioned preferred group of materials for the partition walls as raw material powder.

[0046] Next, the prepared clay is extruded and molded to obtain a columnar honeycomb molded body with partitions forming multiple pores and an outer peripheral wall disposed on the outermost periphery. In extrusion molding, the die used for extrusion molding can be a die with slits formed on the extrusion surface of the clay that have an inverted shape that becomes the molded honeycomb molded body. For example, a preferred example is a method using a die corresponding to the desired pore shape, partition thickness, etc., for extrusion molding. For example, the pore shape in the die can be exemplified by the previously described method with arc-shaped corners 6 (for example, see reference...). Figure 3 (e.g., in) polygonal shapes (e.g., in) Figure 3 (The middle part is roughly quadrilateral in shape). A durable, ultra-hard alloy is preferred as the material for the die. The resulting honeycomb molded body can also be dried using methods such as microwaves and hot air.

[0047] Next, the obtained honeycomb molded body is fired to obtain a honeycomb structure. The firing temperature and firing atmosphere vary depending on the raw materials, and anyone skilled in the art can select the most suitable firing temperature and firing atmosphere for the selected materials.

[0048] Example

[0049] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

[0050] (Example 1)

[0051] To 100 parts by weight of cordierite petrochemical raw material, 2.2 parts by weight of pore-forming material, 1.1 parts by weight of dispersion medium, and 8.0 parts by weight of organic binder were added, and the mixture was stirred and kneaded to prepare clay. Alumina, aluminum hydroxide, kaolin, talc, and silica were used as the cordierite petrochemical raw material. Water was used as the dispersion medium. Methylcellulose was used as the organic binder. Dextrin was used as the dispersant. In addition to polymers such as polyacrylic acid-based polymers with an average particle size of 30 μm, starch, foaming resin, and polymethyl methacrylate (PMMA), coke (skeletal carbon) was also used as the pore-forming material.

[0052] Next, the clay is extruded and shaped using a die that acts as a honeycomb molding mechanism, resulting in a honeycomb molded body with an overall cylindrical shape. The cell shape of the honeycomb molded body is a quadrilateral shape with arc-shaped corners 6 having a radius of curvature R1.

[0053] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. After that, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0054] Next, the dried honeycomb molded body is degreased and fired to manufacture the honeycomb structure of Example 1.

[0055] The honeycomb structure in Example 1 is a cylindrical honeycomb structure with circular first and second end faces. The outer diameter D1 (mm) of the first and second end faces of the honeycomb structure is 266.7 mm. Furthermore, the total length (mm) of the extended cells in the direction of the honeycomb structure is 152.4 mm. The results are shown in Table 1.

[0056] The thickness T1 of the septum of the honeycomb structure in Example 1 is 0.0635 mm. The results are shown in Table 1. Furthermore, the cell density of the honeycomb structure in Example 1 is 93 cells / cm². 2 The porosity of the septum was 34%. The porosity of the septum was measured using an Autopore 9500 (trade name) manufactured by Micromeritics.

[0057] The cellular structure in Example 1 has a generally quadrilateral shape with arc-shaped corners. The radius of curvature R1 of the arc-shaped corners of the generally quadrilateral cellular structure was measured and found to be 0.1000 mm. The results are shown in Table 1. It should be noted that the method for measuring the radius of curvature R1 is as follows.

[0058] [Determination of radius of curvature R1]

[0059] Using an optical microscope, locate two points: one end and the other end of the arc-shaped corner. Then, on the curved portion of the arc-shaped corner, find the midpoint equidistant from these two points. Next, imaginarily draw an inscribed circle connecting these three points: one end, the midpoint, and the other end of the arc-shaped corner. The radius of this inscribed circle is taken as the radius of curvature R1 of the arc-shaped corner.

[0060] [Table 1]

[0061]

[0062] For the honeycomb structure of Example 1, the "pressure loss" and "isostatic compressive strength" were evaluated using the following methods. The results are shown in Table 1.

[0063] [Pressure Loss]

[0064] Maintain a constant flow rate of 20m at room temperature. 3 An airflow of 1 / min passes through the honeycomb structure, and the differential pressure across the honeycomb structure is measured using a differential pressure gauge. The pressure loss (kPa) of the honeycomb structures in each embodiment and comparative example is then measured. The honeycomb structures in each embodiment and comparative example are then evaluated based on the following evaluation criteria.

[0065] Evaluation "OK": Set the condition of less than 0.7 kPa as "OK (qualified)".

[0066] Evaluation "NG": Set conditions above 0.7 kPa as "NG (Unacceptable)".

[0067] [Isostatic Strength]

[0068] The isostatic compressive strength (MPa) of the honeycomb structures in each embodiment and comparative example was measured according to the method for determining isostatic breaking strength as specified in the JASO standard M505-87 issued by the China Automotive Technology Society. Then, the honeycomb structures of each embodiment and comparative example were evaluated based on the following evaluation criteria.

[0069] Evaluation "OK": Cases with an isostatic compressive breaking strength of 1.0 MPa or above are set as "OK (qualified)".

[0070] Evaluation "NG": Cases with isostatic compressive breaking strength less than 1.0 MPa are set as "NG (unacceptable)".

[0071] (Examples 2-8)

[0072] Except for the changes to the composition of the honeycomb structure as shown in Table 1, the honeycomb structure is made using the same method as the honeycomb structure in Example 1.

[0073] (Comparative Examples 1-11)

[0074] Except for the changes to the composition of the honeycomb structure as shown in Table 1, the honeycomb structure is made using the same method as the honeycomb structure in Example 1.

[0075] (result)

[0076] The honeycomb structures of Examples 1-8 all achieved good results in the evaluation of "pressure loss" and "isostatic compressive strength". In particular, the outer diameter D1 of the honeycomb structure of Examples 1-8 is 266.7 mm, which is a large honeycomb structure, but the partitions are unlikely to deform during manufacturing, and there is no cell distortion that would adversely affect the isostatic compressive strength. Therefore, the honeycomb structures of Examples 1-8 have excellent isostatic compressive strength.

[0077] On the other hand, the "isostatic compressive strength" of the honeycomb structures in Comparative Examples 1 to 4, whose "R1×T1" values ​​are less than 0.0050, failed the evaluation. In addition, the "isostatic compressive strength" of the honeycomb structures in Comparative Examples 7 and 8, whose "R1×T1" values ​​exceed 0.0150, passed the evaluation, but failed the evaluation of "pressure loss".

[0078] Furthermore, the evaluation of "isostatic pressure strength" for Comparative Example 5, with a partition wall thickness T1 of 0.0254 mm, was unsatisfactory. Additionally, the evaluation of "pressure loss" for Comparative Example 6, with a partition wall thickness T1 of 0.1524 mm, was unsatisfactory. The pressure losses of Comparative Examples 9 and 11, with outer diameter D1 less than 190.5 mm, were worse than those of Examples 1-8. The evaluation of isostatic pressure strength for Comparative Examples 9 and 11 both met the acceptance criteria. Here, the value of R1×T1 for Comparative Example 9 was less than 0.0050, and the value of R1×T1 for Comparative Example 11 was within the range of 0.0050 to 0.0150. The R1×T1 values ​​of these two examples were consistent with those of Comparative Examples 2 and Example 2. In the comparison between Comparative Example 2 and Example 2, the isostatic pressure strength of Comparative Example 2, with an R1×T1 value less than 0.0050, was unsatisfactory. Comparative Example 2 has a large outer diameter of 266.7 mm, therefore it is believed that deformation occurred during the molding process due to its own weight, resulting in a significant decrease in isostatic compressive strength. Furthermore, the honeycomb structure of Comparative Example 10 has a porosity of 50% in its partition walls, therefore the evaluation of "isostatic compressive strength" is unsatisfactory. The honeycomb structure of Comparative Example 11 has an outer diameter D1 of 152.4 mm, therefore the evaluation of "pressure loss" is unsatisfactory.

[0079] Industrial availability

[0080] The honeycomb structure of the present invention can be used as a catalyst carrier for carrying catalysts used in waste gas purification.

[0081] Symbol Explanation

[0082] 1: partition wall, 2: lattice, 3: outer peripheral wall, 4: honeycomb structure, 11: first end face, 12: second end face, D1: outer diameter (outer diameter of the honeycomb structure), R1: radius of curvature, T1: thickness (thickness of the partition wall), 100: honeycomb structure.

Claims

1. A honeycomb structure having columnar honeycomb structural portions, The honeycomb structure has a porous partition wall arranged to surround a plurality of cells and an outer peripheral wall arranged to surround the partition wall. The plurality of cells extend from a first end face to a second end face and form a flow path for fluid. In a cross-section of the honeycomb structure orthogonal to the direction in which the lattice extends, the lattice is polygonal with arc-shaped corners. The thickness T1 of the partition wall, in mm, is 0.0762~0.0889 mm. The radius of curvature R1 (in mm) of the arc-shaped corner of the lattice and the thickness T1 (in mm) of the partition wall satisfy the following relationship (1). Equation (1): 0.0053 ≤ R1 × T1 ≤ 0.0076 In the cross-section of the honeycomb structure portion orthogonal to the direction of the extension of the pores, the outer diameter of the honeycomb structure portion is 190.5~355.6mm. The porosity of the partition wall is 35-40%.

2. The honeycomb structure according to claim 1, wherein, In the cross section of the honeycomb structure that is orthogonal to the direction in which the pores extend, the shape of the pores is a quadrilateral shape with the arc-shaped corners.

3. The honeycomb structure of claim 1 or 2, wherein, The pore density of the honeycomb structure is 30~140 pores / cm². 2 .

4. The honeycomb structure of claim 1 or 2, wherein, The honeycomb structure is made of cordierite.

5. The honeycomb structure of claim 1 or 2, wherein, The radius of curvature of the arc-shaped corner of the lattice is 0.0700~0.1000 mm.

6. The honeycomb structure of claim 1 or 2, wherein, The outer diameter of the honeycomb structure is 190.5~266.7mm.

7. The honeycomb structure according to claim 1 or 2, wherein, The pore density of the honeycomb structure is 31~93 pores / cm². 2 .

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