honeycomb structure

Abstract

Honeycomb structure (100) with a columnar honeycomb structure body (10) with a porous partition (1) arranged to surround several cells that serve as a fluid passage channel extending from a first end face (11) to a second end face (12), wherein a major component of the partition (1) is cordierite, a porosity of the partition (1) measured by the mercury injection method is 45 to 55%, a mean pore diameter of the partition (1) measured by the mercury injection method is 8 to 19 µm, among pores formed in the partition (1) pores with a pore diameter greater than the thickness T1 of the partition (1) are referred to as first pores, and pores with a pore diameter of 10 µm or less are referred to as second pores, a cumulative pore volume of the partition (1) measured by the The mercury injection method is measured in such a way that it isthat a pore volume ratio of the first pores relative to a total pore volume of the partition (1) is 3.0% or less, and a pore volume ratio of the second pores relative to the total pore volume of the partition (1) is 30% or more, and a pore diameter distribution of the partition (1) is a unimodal distribution or a multimodal distribution in which a difference between a value of a pore diameter of a maximum peak of the pore volume and a value of a pore diameter of a quasi-maximal peak as the second to the maximum peak is 30 µm or less.

Description

The present application is based on JP 2019-187529, filed on 11.10.2019 with the Japanese Patent Office. BACKGROUND OF THE INVENTION Field of invention The present invention relates to honeycomb structures. In particular, the present invention relates to a honeycomb structure that is particularly suitable for use as a catalyst support onto which a catalyst is to be loaded in order to clean exhaust gases. Description of the state of the art Currently, developed countries are considering further tightening the standards for NOx emissions from diesel cars and trucks. To meet these NOx emission standards, various techniques have been proposed for treating NOx in exhaust gases. One such technique involves a honeycomb structure with a porous partition, loaded, for example, with a selective catalytic reduction (SCR) catalyst, to treat NOx in the exhaust gas. In other words, such a honeycomb structure is used as a catalyst carrier loaded with a catalyst to clean the exhaust gas. Traditionally, when a catalyst is loaded into a honeycomb structure, it is primarily deposited on the surface of the partition. Recently, stricter regulations for vehicle emissions have necessitated improvements in the exhaust cleaning performance of honeycomb structures loaded with catalyst. One method for improving this performance involves increasing the amount of catalyst deposited on the honeycomb structure. For example, a technique has been proposed that increases the porosity of the partition, ensuring that the pores formed within the partition are also loaded with catalyst.This is shown, for example, in patent document 1, which discloses a honeycomb structure suitable as a support for a catalyst for cleaning exhaust gas and which includes partitions for forming multiple cells, wherein the partitions are porous partitions with pores whose pore diameter lies within a predefined range. Another method for improving the cleaning performance can be to increase the cell density of a honeycomb structure to increase the efficiency of contact with exhaust gas. "Increasing cell density" means increasing the density of cells defined by the partition to increase the cell density of the honeycomb structure. [Patent document 1] JP 2013 - 52 367 A SUMMARY OF THE INVENTION However, a honeycomb structure with a more porous partition wall presents the problem of reduced isostatic strength. A honeycomb structure with a higher cell density presents the problem of increased pressure loss within the honeycomb structure. Such an increase in pressure loss due to the higher cell density can be mitigated to some extent, for example, by reducing the thickness of the partition wall. A partition wall with reduced thickness and higher porosity, as described above, makes it more difficult to maintain isostatic strength and similar properties. Therefore, "reducing the thickness of a partition wall," as described above, can be referred to as "thinning a partition wall." As described above, the honeycomb structure, which accommodates both higher porosity and a thinner partition wall, can increase the amount of catalyst loaded onto the partition surface and into the pores. However, this honeycomb structure presents a particular challenge in achieving sufficient properties regarding both isostatic strength and pressure drop. Furthermore, if the partition porosity increases and the amount and rate of catalyst loading into the pores of the partition wall increase, the cleaning performance may not improve sufficiently in line with the increased amount of catalyst. That is, if the catalyst is loaded into the pores of the partition wall in a state where the catalyst reaction is minimal, the catalyst's contribution to improving cleaning performance can be significantly reduced.Therefore, there is a need for a honeycomb structure that effectively suppresses a reduction in isostatic strength and an increase in pressure loss, while increasing the permissible amount of catalyst that can be loaded onto the partition and effectively utilizing the catalyst loaded into the pores. In view of these problems of conventional techniques, it is an object of the present invention to create a honeycomb structure that effectively suppresses a reduction in isostatic strength and an increase in pressure loss, while increasing the permissible amount of catalyst that can be loaded onto the partition and effectively utilizing the catalyst loaded into the pores. The present invention creates the following honeycomb structure. [1] A honeycomb structure with a columnar honeycomb body having a porous partition arranged to surround several cells which serve as a fluid passage channel extending from a first end face to a second end face, wherein a major component of the partition is cordierite, a partition porosity measured by the mercury injection method is 45 to 55%, a mean pore diameter of the partition measured by the mercury injection method is 8 to 19 µm, among pores formed in the partition, pores with a pore diameter greater than a thickness T1 of the partition are called first pores and pores with a pore diameter of 10 µm or less are called second pores, and a cumulative pore volume of the partition measured by the mercury injection method is such thatthat a pore volume ratio of the first pores relative to a total pore volume of the partition is 3.0% or less, and a pore volume ratio of the second pores relative to the total pore volume of the partition is 30% or more, and a pore diameter distribution of the partition is a unimodal distribution or a multimodal distribution in which the difference between a value of the pore diameter of a maximum peak of the pore volume and a value of a pore diameter of a quasi-maximal peak as the second to the maximum peak is 30 µm or less. [2] The honeycomb structure according to [1], wherein the porosity of the partition, as measured by the mercury injection method, is 47 to 53%, the mean pore diameter of the partition, as measured by the mercury injection method, is 9 to 18 µm, the cumulative pore volume of the partition, as measured by the mercury injection method, is such that a pore volume ratio of the first pores relative to a total pore volume of the partition is 2.5% or less and a pore volume ratio of the second pores relative to a total pore volume of the partition is 35% or more, and the pore diameter distribution of the partition is a unimodal distribution or a multimodal distribution in which a difference between a value of a pore diameter of a maximum peak of the pore volume and a value of a pore diameter of a quasi-maximal peak as the second to the maximum peak is 28 µm or less. [3] The honeycomb structure according to [1] or [2], wherein a thickness T1 of the partition wall is 64 to 104 µm. [4] The honeycomb structure according to any one of [1] to [3], wherein the cell density of the honeycomb structure body is 85 to 101 cells / cm2. [5] The honeycomb structure according to any one of [1] to [4], wherein the pore diameter distribution of the partition is a unimodal distribution or a bimodal distribution. [6] The honeycomb structure according to any one of [1] to [5], wherein the partition wall comprises 90 wt% or more cordierite in the constituent components. The honeycomb structure of the present invention exhibits the significant effect of effectively suppressing a reduction in isostatic strength and an increase in pressure drop, while increasing the permissible amount of catalyst that can be loaded onto the partition and effectively utilizing the catalyst loaded into the pores. Furthermore, the honeycomb structure of the present invention can be suitablely used as a catalyst support to be loaded with a catalyst for exhaust gas purification, thereby improving exhaust gas purification performance while effectively suppressing a reduction in isostatic strength and an increase in pressure drop. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view schematically showing an embodiment of the honeycomb structure of the present invention; Fig. 2 is a top view showing the first end face of the honeycomb structure of Fig. 1; and Fig. 3 is a sectional view schematically showing the cross-section along AA' of Fig. 2. DESCRIPTION OF PREFERRED EXECUTION FORMS The following describes embodiments of the present invention, although the present invention is not limited to the following embodiments. The present invention should be understood to encompass the following embodiments, to which modifications and improvements may be added as necessary based on the common knowledge of a person skilled in the art, without departing from the scope of protection of the present invention. (1) Honeycomb structure One embodiment of the honeycomb structure according to the present invention is a honeycomb structure 100, as shown in Figs. 1, 2 to 3. Fig. 1 is a perspective view schematically showing one embodiment of the honeycomb structure of the present invention. Fig. 2 is a top view showing a first end face of the honeycomb structure of Fig. 1. Fig. 3 is a sectional view schematically showing the cross-section along AA' of Fig. 2. As shown in Figs. 1, 2 to 3, the honeycomb structure 100 of the present embodiment comprises a column-shaped honeycomb structure body 10 with a first end face 11 and a second end face 12. The honeycomb structure body 10 has a porous partition 1 arranged to surround several cells 2, which serve as a fluid passage channel extending from the first end face 11 to the second end face 12. In the honeycomb structure 100 of the present embodiment, the honeycomb structure body 10 is configured to have a round column shape and further comprises a circumferential wall 20 on its circumferential side surface. That is, the circumferential wall 20 is arranged to surround the lattice-structured partition 1. The honeycomb structure 100 of the present embodiment exhibits the following technical features in terms of the material and thickness of the partition 1 and the pore diameter and pore volume of the pores formed in the partition 1. Hereinafter, the thickness (µm) of the partition 1 is referred to as "T1". "T1" may also be referred to as "thickness T1". Among the pores formed in the partition 1, two types of pores with the following pore diameter values, measured by the mercury injection method, are referred to as "first pores" and "second pores". The "first pores" are pores with a diameter greater than the thickness T1 of the partition 1. The "second pores" are pores with a pore diameter of 10 µm or less. The main component of the partition 1 in the honeycomb structure 100 is cordierite. The "main component" here refers to a component that is present in the materials forming the partition 1 at a ratio of 50% by mass or more. Preferably, the partition comprises 190% by mass or more cordierite in its constituent components, and more preferably 95% by mass or more. The honeycomb structure 100 exhibits a partition wall porosity of 45 to 55%, as measured by the mercury injection method, and a mean pore diameter of 8 to 19 µm, as measured by the mercury injection method. The cumulative pore volume of partition wall 1, as measured by the mercury injection method, is such that the pore volume ratio of the first pores relative to the total pore volume of the partition wall is 13.0% or less, and the pore volume ratio of the second pores relative to the total pore volume of the partition wall is 130% or more. The pore diameter distribution of partition wall 1 is either unimodal or multimodal, with a difference of 30 µm or less between the pore diameter of the maximum peak and the pore diameter of the quasi-maximal peak (second to maximum peak).Hereinafter, “the porosity of partition 1 measured by the mercury injection method” and “the mean pore diameter of partition 1 measured by the mercury injection method” can simply be referred to as “porosity of partition 1” and “mean pore diameter of partition 1”, respectively. The honeycomb structure 100 of the present embodiment exhibits the significant effect of effectively suppressing a reduction in isostatic strength and an increase in pressure drop, while increasing the permissible amount of catalyst that can be loaded onto the partition 1 and effectively utilizing the catalyst loaded into the pores for the catalytic reaction. The honeycomb structure 100 of the present embodiment is therefore suitable for use as a catalyst support for exhaust gas purification, improving the purification performance while effectively suppressing a reduction in isostatic strength and an increase in pressure drop. If the porosity of partition 1 is less than 45%, the resulting honeycomb structure, which fulfills the other configurations as described above, may fail, for example, to maintain a sufficient pore volume to be filled with the catalyst. As the catalyst loading increases, the honeycomb structure has significant difficulty suppressing an increase in pressure drop. If the porosity of the partition exceeds 155%, the resulting honeycomb structure, which fulfills the other configurations as described above, has significant difficulty suppressing, for example, a decrease in isostatic strength. Preferably, the porosity of the partition is 47% to 53%, and more preferably 49% to 52%. If the mean pore diameter of partition 1 is less than 8 µm, the resulting honeycomb structure, which fulfills the other configurations as described above, exhibits a significant difficulty, for example, in suppressing an increase in pressure loss. If the mean pore diameter of partition 1 exceeds 19 µm, the resulting honeycomb structure, which fulfills the other configurations as described above, exhibits a significant difficulty, for example, in suppressing a decrease in isostatic strength. Preferably, the mean pore diameter of the partition is 9 to 18 µm and more preferably 10 to 17 µm. If the pore volume ratio of the first pores relative to the total pore volume of partition 1 exceeds 3.0% and / or the pore volume ratio of the second pores relative to the total pore volume of partition 1 is less than 30%, the resulting honeycomb structure exhibits significant difficulty in suppressing both a reduction in isostatic strength and an increase in pressure drop. Hereinafter, the pore volume ratio of the first pores relative to the total pore volume of partition 1 can be simply referred to as the "pore volume ratio of the first pores." The pore volume ratio of the second pores relative to the total pore volume of partition 1 can be simply referred to as the "pore volume ratio of the second pores."Preferably, the pore volume ratio of the first pores is 2.5% or less and the pore volume ratio of the second pores is 35% or more, and more preferably, the pore volume ratio of the first pores is 2.3% or less and the pore volume ratio of the second pores is 40% or more. As described above, the honeycomb structure 100 of the present embodiment has a pore diameter distribution of the partition 1 that is either a unimodal distribution or a multimodal distribution in which the difference between the value of the pore diameter at the maximum peak of the pore volume and the value of the pore diameter at the quasi-maximal peak is 30 µm or less. Up to now, honeycomb structures containing cordierite as the main component can be produced by adding a desired amount of a pore-forming agent to a cordierite-forming raw material, for example, to adjust the porosity of the partition. Such a porous partition with the cordierite-forming raw material to which a pore-forming agent is added exhibits large pores with a relatively large pore diameter due to the pore-forming agent and micropores with a relatively small pore diameter due to the powder of the cordierite-forming raw material.Therefore, the pore diameter distribution of such a partition can exhibit a multimodal (bimodal) distribution, consisting of a distribution of large pores primarily due to the pore-forming agent and a distribution of micropores primarily due to the cordierite-forming raw material powder. The honeycomb structure 100 of the present embodiment is produced, for example, by adjusting the particle diameter and the amount of the pore-forming agent additive to bring the distribution of large pores closer to the distribution of micropores. The resulting honeycomb structure thus exhibits a pore diameter distribution that is either unimodal or multimodal, in which the difference between the value of the pore diameter at the maximum peak of the pore volume and the value of the pore diameter at the quasi-maximal peak is 30 µm or less.The honeycomb structure effectively suppresses a reduction in isostatic strength and an increase in pressure drop, while increasing the permissible amount of catalyst that can be loaded onto partition 1 and ensuring effective utilization of the catalyst loaded into the pores. If the difference between the pore diameter at the maximum peak of the pore volume and the pore diameter at the quasi-maximal peak exceeds 30 µm, the pores with a larger diameter are preferentially filled with catalyst. In this case, an increased catalyst loading does not result in a correspondingly high purification performance. Furthermore, such a pore diameter distribution reduces the isostatic strength as the porosity of partition 1 increases.If, in the honeycomb structure 100 of the present embodiment, the partition 1 has a pore diameter distribution which is a multimodal distribution in which a difference between the value of the pore diameter of the maximum peak of the pore volume and the value of the pore diameter of the quasimaximal peak is 30 µm or less, it is preferred that the multimodal distribution is essentially a bimodal distribution consisting of the distribution of large pores and the distribution of micropores. The porosity and mean pore diameter of partition 1 can be measured, for example, using Autopore 9500 (product name), manufactured by Micromeritics Co. To measure the porosity and mean pore diameter, a portion of partition 1 can be cut out of the honeycomb structure 100 to prepare a test piece for measurement, and the porosity and mean pore diameter can then be measured using this prepared test piece. The total pore volume, as well as the pore volumes of the first and second pores of partition 1, can be obtained from the cumulative pore volume of partition 1, which is measured by the mercury injection method. The cumulative pore volume of partition 1 can be measured, for example, using Autopore 9500 (product name), manufactured by Micromeritics Co. Specifically, the cumulative pore volume of partition 1 can be measured by the following procedure. First, a portion of partition 1 is cut out of the honeycomb structure 100 to prepare a test piece for measuring the cumulative pore volume. The size of the test piece is not particularly limited; it is preferably a cube with, for example, approximately 10 mm x 10 mm x 10 mm in length, width, and height, respectively. The portion of partition 1 to be cut out as a test piece is not particularly limited.Preferably, the test piece is cut from a section near the center in the axial direction of the honeycomb structure body 10. The prepared test piece is placed in a measuring cell of a measuring device, and the pressure in this measuring cell is reduced. Next, mercury is introduced into the measuring cell. The mercury is then pressurized, and the volume of mercury forced into the pores present in the test piece during the pressurization is measured. As the pressure applied to the mercury increases, the mercury is first forced into pores with a larger pore diameter and then into pores with a smaller pore diameter.Consequently, the relationship between the "pore diameter of the pores formed in the test piece" and the "cumulative pore volume" can be derived from the relationship between the "pressure applied to the mercury" and the "volume of mercury forced into the pores." The "cumulative pore volume" is a value obtained by accumulating the pore volume values ​​from a smallest pore diameter to a specific pore diameter. For example, the pore volume of the second set of pores can be obtained as a value calculated by accumulating the pore volume values ​​of the pores from a smallest pore diameter to a pore diameter of 10 µm (i.e., the pores with a pore diameter of 10 µm or less).The pore volume ratio (%) of the second pores can then be obtained as a percentage (pv1 / PVall x 100%) of the ratio of the pore volume pv1 of the pores with pore diameters of 10 µm or less relative to the total pore volume PVall, represented by the cumulative pore volume. Similarly, the pore volume of the first pores can also be obtained as a value calculated by accumulating the pore volume values ​​of the pores with a pore diameter greater than the thickness T1 of partition 1. The pore volume ratio (%) of the first pores can also be obtained by a procedure similar to that used for the pore volume ratio (%) of the second pores. The thickness T1 of the partition 1 can be measured, for example, with a scanning electron microscope or a microscope. The partition 1 preferably has a thickness T1 of 64 to 104 µm, more preferably 76 to 102 µm, and most preferably 81 to 97 µm. The honeycomb structure 100 of the present embodiment can effectively suppress a reduction in isostatic strength and thus allows the partition 1 to be thinned as described above. The honeycomb structure 100 of the present embodiment therefore results in a low pressure drop. If the thickness T1 of the partition 1 is less than 64 µm, the thickness T1 of the partition 1 is too small, so that the honeycomb structure cannot have sufficient strength. If the thickness T1 of the partition 1 exceeds 104 µm, the pressure drop of the honeycomb structure 100 can increase.Since the thickness T1 of partition wall 1 is a value that serves as a reference for the first pores, the thickness T1 of partition wall 1, which exceeds the numerical range described above, may adversely affect the parameters relating to the pore volume ratio of the first pores. The honeycomb structure 100 of the present embodiment can increase the filling rate of the pores of the partition 1 with catalyst due to the high porosity of the partition 1. The honeycomb structure 100 can therefore suppress an increase in pressure drop after loading with the catalyst to clean exhaust gas. In this way, the honeycomb structure 100 can suppress an increase in pressure drop when, for example, the amount of catalyst used for loading is increased, and can achieve both an "improvement in cleaning performance" and a "suppression of an increase in pressure drop". Preferably, in the honeycomb structure 100 of the present embodiment, the partition 1 has a porosity of 47 to 53% and a mean pore diameter of 9 to 18 µm, the pore volume ratio of the first pores is 2.5% or less, and the pore volume ratio of the second pores is 35% or more. If the pore diameter distribution of the partition 1 is a multimodal distribution, a difference of 28 µm or less between the value of the pore diameter at the maximum peak of the pore volume and the value of the pore diameter at the quasi-maximal peak is preferred. The shape of the cells 2 formed in the honeycomb structure 10 is not particularly limited. In a cross-section orthogonal to the orientation of the cells 2, the cells 2 can, for example, have a polygonal shape such as a triangle, a quadrilateral, a pentagon, a hexagon, or an octagon. Preferably, the shape of the cells 2 is a triangle, a quadrilateral, a pentagon, a hexagon, or an octagon. Regarding the shape of the cells 2, all of the cells 2 can have the same shape, or the cells 2 can have different shapes. Although not shown, for example, quadrilateral and octagonal cells can be combined. Regarding the size of the cells 2, all of the cells 2 can have the same size, or the cells 2 can have different sizes. Although not shown, for example, some of the cells can be larger, and other cells can be relatively smaller.In the present invention, the cells 2 refer to a space surrounded by the partition 1. Preferably, the cells 2 defined by the partition 1 can have a cell density of 85 to 101 cells / cm² and more preferably 90 to 97 cells / cm². The honeycomb structure 100 with such a configuration of the present embodiment can be suitablely used as a cleaning element (e.g., catalyst support or filter) to clean exhaust gas emitted from a motor vehicle engine. The circumferential wall 20 of the honeycomb structure body 10 can be configured as a single unit with the partition wall 1 or can consist of a circumferential coating layer formed by applying a circumferential coating material to surround the partition wall 1. Although not shown, the circumferential coating layer can be provided on the circumferential side of the partition walls after the partition walls and the circumferential walls have been formed as a single unit, and then the formed circumferential wall is removed by a known method such as grinding in a manufacturing process. The shape of the honeycomb structure body 10 is not particularly limited. Examples of the shape of the honeycomb structure body 10 include a column shape in which the first end face 11 and the second end face 12 have a shape such as a circle, an ellipse, or a polygon. The size of the honeycomb structure body 10, including the length from the first end face 11 to the second end face 12, and the size of a cross-section orthogonal to the orientation of the cells 2 of the honeycomb structure body 10 are not particularly limited. The dimensions of the honeycomb structure 10 of the present embodiment can be suitably selected so that the honeycomb structure can exhibit optimal cleaning performance when used as an element for cleaning exhaust gas. The length from the first end face 11 to the second end face 12 of the honeycomb structure body 10 is, for example, preferably 76.2 to 228.6 mm and more preferably 101.6 to 203.2 mm. The area of ​​a cross-section orthogonal to the orientation of the cells 2 of the honeycomb structure body 10 is preferably 24,829 to 99,315 mm² and more preferably 28,502 to 85,634 mm². In the honeycomb structure 100 of the present embodiment, the partition 1, which defines the multiple cells 2, can be loaded with catalyst to purify exhaust gas. The loading of the partition 1 with catalyst refers to the loading of the catalyst onto the surface of the partition 1 or into the pores formed in the partition 1. The honeycomb structure 100 of the present embodiment can suppress a reduction in isostatic strength and an increase in pressure drop, thus enabling an increase in the catalyst loading quantity through high porosity and thinning of the partition 1 to improve purification performance. (2) Method for producing a honeycomb structure A method for producing the honeycomb structure of the present invention is not particularly limited, and the honeycomb structure can be produced, for example, by the following method. First, a kneadable material with plasticity is prepared to create a honeycomb structure body. The kneaded material for creating a honeycomb structure body can be prepared by adding additives such as binders, pore-forming agents, and water as required to a material selected from raw material powders of the aforementioned materials suitable for the honeycomb structure body. Examples of the raw material powder include a cordierite-forming raw material. The cordierite-forming raw material is a raw material that forms cordierite after firing.In particular, the cordierite formation raw material is a raw material formulated to have a chemical composition in the range of 42 to 56 wt% silicon dioxide, 30 to 45 wt% aluminum oxide and 12 to 16 wt% magnesium oxide. To prepare the kneaded material, the particle diameter of the pore-forming agent can be adjusted to control the pore diameter distribution of the partition. For example, the mean particle diameter of the pore-forming agent is preferably smaller than the thickness T1 of the partition. Using such a pore-forming agent allows for a pore volume ratio of the first pores of 3.0% or less and a pore volume ratio of the second pores of 30% or more. Next, the prepared kneaded material is extruded, producing a columnar, honeycomb-shaped body with a partition wall defining multiple cells and a circumferential wall arranged to surround this partition wall. Preferably, the thickness of the partition wall of the honeycomb-shaped body is determined such that, after firing, the partition wall of the honeycomb structure has a desired thickness T1 according to the mean particle diameter of the pore-forming agent added to the raw material powder. Next, the resulting honeycomb-shaped body is dried, for example, using microwaves and hot air. Following this, the honeycomb-shaped body is fired to create a honeycomb structure. The firing temperatures and atmosphere vary depending on the raw material, and a specialist in the field can select the temperature and atmosphere best suited to the chosen material. (Examples) The following describes the present invention in more detail by means of examples, and the present invention is by no means limited to these examples. (Example 1) 2.5 parts by mass of pore-forming agent, 0.5 parts by mass of dispersion medium, and 6.5 parts by mass of organic binder were added to 100 parts by mass of cordierite-forming raw material, followed by mixing and kneading to prepare a kneaded material. The cordierite-forming raw material used was aluminum oxide, aluminum hydroxide, kaolin, talc, and silicon dioxide. Water was used as the dispersion medium. Methylcellulose was used as the organic binder. Dextrin was used as the dispersion agent. Hollow resin particles with a mean particle diameter of 28 µm were used as the pore-forming agent. Next, the kneaded material was extruded using a nozzle to create a honeycomb-shaped body, resulting in a honeycomb-shaped body with a round columnar form as the overall shape. The cells of the honeycomb body were rectangular. Next, the honeycomb-shaped body was dried using a microwave dryer, then completely dried using a hot air dryer, and then both end faces of the honeycomb-shaped body were cut to achieve predetermined dimensions. The dried honeycomb-shaped body was then degassed and fired to obtain a honeycomb structure as shown in Example 1. The honeycomb structure of Example 1 had a round column shape, with the first and second end faces being round. The first and second end faces had a diameter of 266.7 mm. The honeycomb structure had a total length in the cell direction of 152.4 mm. The honeycomb structure of Example 1 had a partition thickness T1 of 89 µm and a cell density of 93 cells / cm². Table 1 shows the diameter (mm), total length (mm), cell density (cells / cm²), and partition thickness T1 (µm) of the honeycomb structure. [Table 1] [Table 1] Ex. 1266,7152,4938949111,845.00 Ex. 2266,7152,4939152132,043.00 Ex. 3266,7152,4939153152,340.00 E.g. 4266,7152,4949153112,145.00 E.g. 5266,7152,4938950182,535,020 E.g. 6266,7152,4938950172,335,028 Ex. 7266,7152,493914791,450.00 Ex. 8266,7152,4939147111,646.00 Ex. 9266,7152,494865191,550.00 E.g. 10266,7152,49410250101,346.00 Ex. 11266,7152,4949751111,445.00 E.g. 12266,7152,4947650112,045.00 Ex. 13266,7152,4948149101,743.00 E.g. 14266,7152,4949155192,633,025 E.g. 15266,7152,4938955102,246.00 E.g. 16266,7152,4939152193,030,030 E.g. 17266,7152,493864581,349.00 E.g. 18266,7152,4949145101,852.00 E.g. 19266,7152,493894981,648.00 E.g. 20266,7152,49310450121,044.00 Ex. 21266,7152,4936449102,543.00 For comparison: 1266.7152.492944060.254.00 Comparison example: 2266,7152,4948957203,228,030 Comparison example: 3266,7152,4939150204,334,035 For the partition wall of the honeycomb structure in Example 1, the following values ​​were obtained: porosity (%), mean pore diameter (µm), first pore volume ratio (%), second pore volume ratio (%), and the pore diameter between peaks of the pore diameter distribution (µm). Table 1 shows the results. The pore diameter between peaks of the pore diameter distribution (µm) represents the difference between the pore diameter of the maximum pore volume peak and the pore diameter of the quasi-maximal peak (second to the maximum peak) in the partition wall's pore diameter distribution. A pore diameter between peaks of the pore diameter distribution of 0 µm indicates that the partition wall's pore diameter distribution is unimodal. The porosity of the partition wall was measured using Autopore 9500 (product name), manufactured by Micromeritics Co. To measure the porosity, a portion of the partition wall was cut from the honeycomb structure to prepare a test piece, and the porosity of the resulting test piece was measured. The test piece was a cube approximately 10 mm long, 10 mm wide, and 10 mm high. The test piece was cut from a section near the center along the axial direction of the honeycomb structure. The total pore volume of the partition was measured using Autopore 9500 (product name), manufactured by Micromeritics Co. The total pore volume was also measured using the same test piece as for the porosity measurement. During the total pore volume measurement, the cumulative pore volume of the partition was measured, and the "pore volume ratio of the first pores (%)" and the "pore volume ratio of the second pores (%)", as described above, were also measured simultaneously. The "value of the pore diameter between peaks of the pore diameter distribution (µm)" was also calculated based on the obtained measurement results. For the honeycomb structure of Example 1, the porosity of the partition wall was 49% and the mean pore diameter was 11.0 µm. The pore volume ratio of the first pores was 1.8% and the pore volume ratio of the second pores was 45.0%. The pore diameter distribution of the partition wall was a unimodal distribution, meaning that the value of the pore diameter between the peaks in the pore diameter distribution was 0 µm. Catalyst was loaded onto the partition of the honeycomb structure of Example 1 by the following procedure. First, a catalyst slurry containing zeolite with a mean particle diameter of 5 µm was prepared. This catalyst slurry was loaded onto the honeycomb structure so that the loading rate per unit volume after drying was 230 g / l. To load the catalyst, the honeycomb structure was immersed in the catalyst slurry, followed by blowing off the excess catalyst slurry for impregnation. This was dried at 120 °C, followed by heat treatment at 500 °C for 3 hours, resulting in a catalyst-loaded honeycomb structure. The catalyst loading rate on the honeycomb structure of Example 1 was 231 g / l. [Table 2] Example 163.02.0-1658.5 Example 265.01.8-1858.6 Example 372.01.1-2059.5 Example 463.01.7-1758.8 Example 576.01.4-2058.4 Example 674.01.5-1958.4 Example 745.02.9-1158.4 Example: 860.02.8-1558.5 Example: 945.02.5-1258.6 Example 1062.03.2-658.5 Example 1163.03.0-958.7 Example 1260,01,2-1958,4 Example 1362.01.4-1758.1 Example: 1480.00.7-2359.7 Example: 1560.00.8-1759.0 Example 1678.00.9-2158.4 Example 1740.03.2-1058.5 Example: 1858.03.0-1458.6 Example 1942,02,4-1158,7 Example 2064.03.6-558.4 Example: 2163.00.7-2558.8 Comparison example: 120.04.0-558.0 Comparison example: 280.00.6 - 2460.0 Comparison example: 370.00.6-1857.0 For the honeycomb structure of Example 1, the "catalyst filling rate (%)" was obtained using the following procedure. For the honeycomb structure of Example 1, the "isostatic strength (MPa)" was measured using the following procedure. For the honeycomb structure of Example 1, the "pressure loss assessment (%)" and the "cleaning performance assessment (%)" were performed using the following procedure. Table 2 shows the results. (Catalytic converter filling rate (%)) A test piece measuring 20 mm in length, 20 mm in width, and 20 mm in height was cut from the honeycomb structure of Example 1. The partition of this test piece was polished, and then SEM images of three randomly selected fields were acquired using a scanning electron microscope (SEM). The dimensions of one field of view were the thickness (µm) of the partition in the X direction and 600 µm in the Y direction. When the honeycomb structure was then loaded with catalyst, the ratio (percentage) of the volume (V1) of the pores actually filled with catalyst, relative to the volume (V0) of all pores formed in the partition, was obtained.Specifically, the images were analyzed to extract a portion of the pores (i.e., pores impregnated with the catalyst and pores not impregnated with the catalyst) by binarization, and then the volume (V0) of all pores formed in the partition was calculated. Next, the honeycomb structure was loaded with the catalyst, and the images were analyzed to extract a portion of the catalyst-impregnated pores by binarization, and then the volume V1 was obtained. Based on these values, the catalyst filling rate (%) in each SEM image was then calculated. Table 2 shows the catalyst filling rate (%) value, which was the arithmetic mean of the catalyst filling rates of the SEM images in three fields of view. If the catalyst filling rate (%) in Table 2 was 40% or higher, the honeycomb structure was accepted. (Isostatic strength (MPa)) The isostatic strength was measured according to the isostatic fracture strength test specified in M505-87 of the automotive standard (JASO standard) issued by the Society of Automotive Engineers of Japan, Inc. The isostatic fracture strength is tested by arranging the honeycomb structure in a rubber tubular container sealed with an aluminum plate and then applying isostatic pressure to it in water. The isostatic strength measured by this isostatic fracture strength test is expressed as the pressure (MPa) applied when the honeycomb structure fractures. If the isostatic strength was 0.7 MPa or greater, the honeycomb structure was "accepted," and if the isostatic strength was less than 0.7 MPa, the honeycomb structure was "rejected." (Pressure loss rating (%)) The pressure difference between the first and second end faces of the reference honeycomb structure at 25 °C was determined. The pressure drop value of the reference honeycomb structure obtained in this way was defined as “PO (%)”. The reference honeycomb structure had the same partition structure as the honeycomb structure to be evaluated (see Table 1), and the reference honeycomb structure had the partition that was not loaded with catalyst. Separately, a pressure difference between the first and second end faces of the catalyst-loaded honeycomb structures with the values ​​shown in Table 2 was determined at 25 °C. The pressure drop value of each of the catalyst-loaded honeycomb structures obtained in this way was defined as “P1 (%)”. As an evaluation value to assess the pressure drop, the value was then calculated using the following expression (1).The honeycomb structure with the evaluation value of the following expression (1), which was -5% or less, was accepted. (Cleaning performance rating (%)) First, test gas containing NOx was introduced into the honeycomb structure. The amount of NOx in the gas released from this honeycomb structure was then analyzed using a gas analyzer. The temperature of the test gas flowing through the honeycomb structure was 200 °C. The temperatures of the honeycomb structure and the test gas were controlled by a heating device. An infrared imaging oven was used for this purpose. The test gas consisted of 5% by volume carbon dioxide, 14% by volume oxygen, 350 ppm nitric oxide (by volume), 350 ppm ammonia (by volume), and 10% by volume water with nitrogen. To prepare this test gas, the water and the mixed gas were separated from other gases and then blended in the tube for use in the test. A MEXA9100EGR gas analyzer, manufactured by HORIBA, Ltd., was used. The space velocity of the test gas flowing into the honeycomb structure was 100000 (hour-1).The "Cleaning Performance Rating (%)" column in Table 2 shows the NOx cleaning rate, which is obtained by subtracting the amount of NOx in the test gas separated from the honeycomb structure from the total amount of NOx in the test gas, dividing the result by the total amount of NOx in the test gas, and multiplying the result by 100. Since the NOx cleaning rate of the reference standard honeycomb structure was 58.0%, any honeycomb structure with a NOx cleaning rate of 58.0% or higher was accepted. The reference honeycomb structure was the same as the one used for the "Pressure Loss Rating (%)". (Examples 2 to 21) Honeycomb structures of examples 2 to 21 were produced by modifying the partition structure as shown in Table 1. The "mean pore diameter (µm)," the "pore volume ratio of the first pores (%)," the "pore volume ratio of the second pores (%)," and the "value of the pore diameter between peaks in the pore diameter distribution (µm)" were adjusted by modifying the particle diameter of the pore-forming agent added to the forming raw material. In example 2, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 3, the pore-forming agent with a mean particle diameter of 38 µm was used. In example 4, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 5, the pore-forming agent with a mean particle diameter of 70 µm was used. In example 6, the pore-forming agent with a mean particle diameter of 70 µm was used. In example 7, the pore-forming agent with a mean particle diameter of 10 µm was used. In example 8, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 9, the pore-forming agent with a mean particle diameter of 22 µm was used. In example 10, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 11, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 12, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 13, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 14, the pore-forming agent with a mean particle diameter of 70 µm was used. In example 15, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 16, the pore-forming agent with a mean particle diameter of 70 µm was used. In example 17, the pore-forming agent with a mean particle diameter of 10 µm was used. In example 18, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 19, the pore-forming agent with a mean particle diameter of 22 µm was used. In example 20, the pore-forming agent with a mean particle diameter of 28 µm was used. In example 21, the pore-forming agent with a mean particle diameter of 28 µm was used. (Comparative examples 1 to 3) Honeycomb structures in comparison examples 1 to 3 were produced by changing the partition configuration as shown in Table 1. The "mean pore diameter (µm)", the "pore volume ratio of the first pores (%)", the "pore volume ratio of the second pores (%)" and the "value of the pore diameter between peaks of the pore diameter distribution (µm)" were adjusted by changing the particle diameter of the pore-forming agent added to the raw material. In comparative example 1, the pore-forming agent with a mean particle diameter of 10 µm was used. In comparative example 2, the pore-forming agent with a mean particle diameter of 70 µm was used. In comparative example 3, the pore-forming agent with a mean particle diameter of 100 µm was used. For the honeycomb structures of Examples 2 to 21 and Comparative Examples 1 to 3, the "catalyst filling rate (%)" and the "isostatic strength (MPa)" were measured using a method similar to Example 1. The "pressure loss assessment (%)" and the "cleaning performance assessment (%)" were also performed using a method similar to Example 1. Table 2 shows the results. (Results) The honeycomb structures of Examples 1 to 21 suppressed a decrease in isostatic strength and an increase in pressure drop and exhibited excellent cleaning performance. The honeycomb structures of Comparative Example 1 had a low catalyst loading rate, resulting in a high catalyst loading rate on the partition surface. Consequently, this honeycomb structure experienced a high pressure drop. The honeycomb structures of Comparative Examples 2 and 3 had a high pore volume ratio of the first pores and a high catalyst loading rate. However, these honeycomb structures of Comparative Examples 2 and 3 exhibited a significant decrease in isostatic strength relative to the reference honeycomb structure. Regarding the pore diameter distribution of the pores formed in the partition, the honeycomb structure of Comparative Example 3 showed a multimodal distribution with a pore diameter between the peaks of 35 µm, as shown in Table 2.Such a honeycomb structure, as in comparison example 3, also showed a low value in the cleaning performance evaluation. The honeycomb structure of the present invention can be used for a catalyst carrier that is to be loaded with catalyst in order to clean exhaust gas. Description of reference symbols 1 Partition wall 2 Cell 10 Honeycomb structure body 11 First end face 12 Second end face 20 Perimeter wall 100 Honeycomb structure

Claims

honeycomb structure (100) with a columnar honeycomb structure body (10) with a porous partition (1) arranged to surround several cells that serve as a fluid passage channel extending from a first end face (11) to a second end face (12), wherein a major component of the partition (1) is cordierite, a porosity of the partition (1) as measured by the mercury injection method is 45 to 55%, a mean pore diameter of the partition (1) as measured by the mercury injection method is 8 to 19 µm, among pores formed in the partition (1) pores with a pore diameter greater than the thickness T1 of the partition (1) are referred to as first pores, and pores with a pore diameter of 10 µm or less are referred to as second pores, a cumulative pore volume of the partition (1) as measured by the The mercury injection method is measured in such a way that it isthat a pore volume ratio of the first pores relative to a total pore volume of the partition (1) is 3.0% or less, and a pore volume ratio of the second pores relative to the total pore volume of the partition (1) is 30% or more, and a pore diameter distribution of the partition (1) is a unimodal distribution or a multimodal distribution in which a difference between a value of a pore diameter of a maximum peak of the pore volume and a value of a pore diameter of a quasi-maximal peak as the second to the maximum peak is 30 µm or less. Honeycomb structure (100) according to claim 1, wherein the porosity of the partition (1), measured by the mercury injection method, is 47 to 53%, the mean pore diameter of the partition (1), measured by the mercury injection method, is 9 to 18 µm, the cumulative pore volume of the partition (1), measured by the mercury injection method, is such that a pore volume ratio of the first pores relative to a total pore volume of the partition (1) is 2.5% or less, and a pore volume ratio of the second pores relative to a total pore volume of the partition (1) is 35% or more, and the pore diameter distribution of the partition (1) is a unimodal distribution or a multimodal distribution in which a difference between a value of a pore diameter at a maximum peak of the pore volume and a value of a pore diameter at a quasi-maximal peak as the second to the maximum peak is 28 µm or less. Honeycomb structure (100) according to claim 1 or 2, wherein a thickness T1 of the partition (1) is 64 to 104 µm. Honeycomb structure (100) according to one of claims 1 to 3, wherein the cell density of the honeycomb structure body (10) is 85 to 101 cells / cm2. Honeycomb structure (100) according to one of claims 1 to 4, wherein the pore diameter distribution of the partition (1) is a unimodal distribution or a bimodal distribution. Honeycomb structure (100) according to one of claims 1 to 5, wherein the partition (1) comprises 90 wt% or more of cordierite in the constituent components.

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