honeycomb structure

Abstract

honeycomb structure (100) comprising a columnar honeycomb structure body (4) having a first end face (11) and a second end face (12) and having a porous partition (1) arranged to surround several cells (2), wherein the several cells (2) extend from the first end face (11) to the second end face (12) and serve as a fluid passage channel, wherein Assuming that A denotes an amount of open end face (%) in a plane of the honeycomb structure body (4) perpendicular to the extension direction of the cells (2) and P denotes an amount of porosity (%) of the partition (1), the honeycomb structure (100) has a value represented by the following expression (1) which is in the range of 0.05 to 0.12, assuming that D denotes an average pore diameter (µm) of the partition (1) and G a geometric surface area (mm²) 2 / mm 3) of the partition (1) denotes the honeycomb structure (100) has a value represented by the following expression (2), which is in the range of 8 to 50 (µm × mm 2 / mm 3 ) lies, and the honeycomb structure (100) has a hydraulic diameter of the cells that is 1.1 mm or more, wherein ( 1 − A / 100 ) × ( 1 − P / 100 ) and D × G .

Description

[0001] The present application is based on JP 2020-047 719, filed on 18 March 2020 with the Japan Patent Office, which is incorporated herein in its entirety by reference. BACKGROUND OF THE INVENTION Area of ​​the invention

[0002] The present invention relates to honeycomb structures. In particular, the present invention relates to a honeycomb structure that exhibits excellent temperature rise properties and can effectively prevent the flaking of a catalyst used for cleaning exhaust gases. Description of the related area

[0003] Currently, industrialized countries are considering further tightening of regulations on NOx emissions from diesel-powered vehicles and trucks. To comply with such NOx regulations, various techniques have been proposed for treating NOx in exhaust gases. One such technique, for example, involves creating a honeycomb structure with a porous partition loaded with a selective catalytic reduction catalyst (hereinafter referred to as an "SCR catalyst") and the like, and treating NOx in the exhaust gas using the honeycomb structure for purification (see patent document 1). "SCR" stands for selective catalytic reduction.

[0004] Traditionally, the most prevalent exhaust gas cleaning system has been configured to include a first honeycomb catalyst carrier loaded with an oxidation catalyst, a honeycomb filter, and a second honeycomb catalyst carrier loaded with an SCR catalyst, arranged sequentially upstream of the exhaust system. To meet stringent NOx emission regulations described above, another exhaust gas cleaning system is currently under investigation. This system additionally incorporates a third honeycomb catalyst carrier, also loaded with an SCR catalyst, upstream of the first honeycomb catalyst carrier loaded with an oxidation catalyst. The third honeycomb catalyst carrier is intended to improve exhaust gas cleaning performance at low temperatures.

[0005] Further prior art is also known from patent document 2. [Patent Document 1] JP 2013- 052 367 A [Patent document 2] EP 1040 871 A2 SUMMARY OF THE INVENTION

[0006] For the system described above, which includes an additional third honeycomb catalyst carrier loaded with an SCR catalyst upstream in the exhaust system, the amount of SCR catalyst loaded at the third honeycomb catalyst carrier must increase. Specifically, the amount of SCR catalyst loaded at the third honeycomb catalyst carrier can be greater than the amount of SCR catalyst at the second honeycomb catalyst carrier, which is located downstream in the exhaust system. This effectively improves the exhaust gas cleaning performance at low temperatures.

[0007] A conventional honeycomb structure for catalyst supports containing such a large amount of SCR catalyst, as is the case with the third honeycomb support, fails to retain a sufficient surface area of ​​the partition to adhere to the SCR catalyst and therefore causes flaking of the charged catalyst in actual use. This is particularly true when the number of cells in the honeycomb structure is small, and thus the throughput channel per cell is large, resulting in a small surface area of ​​the partition for catalyst adhesion. This significantly contributes to flaking of the charged catalyst. Hereinafter, flaking of the charged catalyst in the honeycomb structure can be referred to as "catalyst flaking."

[0008] In one example, a conventional honeycomb structure used as a catalyst support for an SCR catalyst has a cell density defined by the partition wall, which is approximately 100 cells / cm². 2 The second honeycomb catalyst support in the example described above is located downstream of the honeycomb filter, and the honeycomb structure used as this catalyst support has a relatively high cell density because the honeycomb filter removes suspended particles such as soot from the exhaust gas. If such a honeycomb structure is used as the third honeycomb catalyst support, located upstream in the exhaust system, the cells of the honeycomb structure will become clogged with suspended particles and blocked within a relatively short period of time.

[0009] With regard to problems of conventional techniques, the present invention creates a honeycomb structure which has excellent temperature rise properties and can effectively prevent the flaking of a catalyst loaded for cleaning exhaust gas.

[0010] The present invention creates the following honeycomb structure. [1] A honeycomb structure comprising a columnar honeycomb structure body having a first end face and a second end face and containing a porous partition arranged to surround several cells, the several cells extending from the first end face to the second end face and serving as a fluid passage channel, wherein Assuming that A denotes an amount of open end face (%) in a plane of the honeycomb structure body perpendicular to the direction of cell expansion and P denotes an amount of porosity (%) of the partition, the honeycomb structure has a value represented by the following expression (1) which is in the range of 0.05 to 0.12, assuming that D denotes an average pore diameter (µm) of the partition and G a geometric surface area (mm²) 2 / mm 3 ) of the partition, the honeycomb structure has a value represented by the following expression (2), which is in the range of 8 to 50 (µm × mm 2 / mm 3 ) lies, and the honeycomb structure has a hydraulic diameter of the cells that is 1.1 mm or more, whereby (1−A / 100)×(1−P / 100) and D×G. [2] The honeycomb structure according to [1], wherein the partition contains at least one type selected from the group consisting of cordierite, silicon carbide, silicon nitride and mullite. [3] The honeycomb structure according to [1] or [2], wherein the partition wall has a surface roughness Ra of 1 µm or more. [4] The honeycomb structure according to one of [1] to [3], wherein the honeycomb structure is installed in an exhaust system of an internal combustion engine and is arranged upstream of an oxidation catalyst or an exhaust gas purification filter, which is installed separately in the exhaust system.

[0011] The honeycomb structure of the present invention possesses the remarkable advantages of exhibiting excellent temperature rise properties and effectively preventing the flaking of a charged catalyst for exhaust gas cleaning. The honeycomb structure of the present invention is less likely to become clogged with suspended particles in the exhaust gas, even when arranged relatively upstream in the exhaust system, and therefore effectively prevents cell clogging. The honeycomb structure of the present invention also exhibits excellent mechanical strength. For example, when a honeycomb structure is used as a catalyst support for exhaust gas cleaning, the honeycomb structure can be housed in a casing, such as a metal housing. Housing a honeycomb structure in a casing, such as a metal housing, can be referred to as enclosing. The enclosing of a honeycomb structure exerts a force via a retaining element, such as a clamping element.A mat exerts a uniform pressure on the outer surface of the honeycomb structure to secure the honeycomb structure within the housing. The honeycomb structure of the present invention effectively suppresses breakage due to the compacting uniform pressure applied to the outer surface during dispensing. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view schematically showing a first 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 shows; and Fig. 3 is a schematic cross-sectional view, extending along AA' from Fig. 2 was taken. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0012] The following describes embodiments of the present invention, and the present invention is not limited to the following embodiments. The present invention is to be understood as including the following embodiments, to which modifications and improvements based on the usual knowledge of a person skilled in the art may be added as needed, without departing from the scope of the present invention. (1) Honeycomb structure:

[0013] A first embodiment of the honeycomb structure of the present invention is a honeycomb structure 100 as described in Fig. 1 to Fig. 3 is shown. Fig. Figure 1 is a perspective view that schematically shows the first 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 shows. Fig.3 is a schematic cross-sectional view drawn along line AA' from Fig. 2 was taken.

[0014] As in Fig. 1 to Fig. As shown in Figure 3, the honeycomb structure 100 contains a columnar honeycomb structure body 4, which has a first end face 11 and a second end face 12. The honeycomb structure body 4 has a porous partition 1 that surrounds several cells 2, and these cells 2 extend from the first end face 11 to the second end face 12 and serve as a fluid passage channel. In the honeycomb structure 100, the honeycomb structure body 4 has a round columnar shape and also contains a circumferential wall 3 on its outer circumferential surface. That is, the circumferential wall 3 surrounds the grid-patterned partition 1.

[0015] Assuming that A denotes the amount of the open end face (%) of the honeycomb structure body 4 and P denotes the amount of the porosity (%) of the partition 1, the honeycomb structure has a value represented by the following expression (1) which is in the range of 0.05 to 0.12. (1−A / 100)×(1−P / 100)

[0016] The open end surface area (%) of the honeycomb structure 4 is the open end surface area (%) in a plane of the honeycomb structure 4 perpendicular to the direction of expansion of the cells 2. Specifically, the open end surface area (%) of the honeycomb structure 4 can be obtained as the percentage of the ratio of the area S2 of the cavities of the cells 2 to the total area S1 of the plane of the honeycomb structure 4 perpendicular to the direction of expansion of the cells 2. For example, the open end surface area (%) of the honeycomb structure 4 can be measured using an optical microscope.

[0017] The porosity (%) of partition 1 is a value measured by mercury intrusion porosimetry. The porosity of partition 1 can be measured, for example, using Autopore 9500 (product name), manufactured by Micromeritics Co. To measure the porosity, a portion of partition 1 can be cut out from the honeycomb structure 100 to prepare a test specimen for measurement.

[0018] The value represented by expression (1) above, in the range of 0.05 to 0.12, enables the honeycomb structure to possess excellent temperature rise properties and effectively prevent the flaking of a catalyst used for exhaust gas cleaning. The value represented by expression (1) above is preferably in the range of 0.07 to 0.10 and more preferably in the range of 0.08 to 0.09.

[0019] The open end surface area (%) of the honeycomb structure body 4 is preferably 80 to 90%, more preferably 81 to 89%, and particularly preferably 82 to 88%. An open end surface area (%) of the honeycomb structure body 4 of less than 80% is not advantageous from the standpoint of temperature rise properties and soot clogging. An open end surface area (%) of the honeycomb structure body 4 exceeding 90% is not advantageous because the isostatic strength decreases, and therefore the honeycomb structure simply breaks during dispensing.

[0020] The porosity (%) of the partition 1 is preferably in the range of 25 to 60%, more preferably in the range of 27 to 55%, and particularly preferably in the range of 30 to 45%. A porosity (%) of the partition 1 below 25% is not advantageous from the point of view of catalyst flaking. A porosity (%) of the partition 1 exceeding 60% is not advantageous because the isostatic strength decreases and therefore the honeycomb structure simply breaks down during dosing.

[0021] Assuming that D denotes the average pore diameter (µm) of the partition 1 and G the geometric surface area (mm²) 2 / mm 3 ) of the partition 1, the honeycomb structure 100 has a value represented by the following expression (2), which is in the range of 8 to 50 (µm × mm 2 / mm 3 ) lies. D×G

[0022] The average pore diameter (µm) of partition 1 is a value measured by mercury intrusion porosimetry. Similar to porosity measurement, the average pore diameter of partition 1 can be measured, for example, using Autopore 9500 (product name), manufactured by Micromeritics Co.

[0023] The geometric surface area (mm²) 2 / mm 3 The surface area (mm²) of partition 1 is a value measured with an optical microscope. For example, to measure the geometric surface area of ​​partition 1, the length of the surface of partition 1 defining cells 2 is first measured with an optical microscope. Then, the area per unit volume of partition 1 is measured. Based on these results, the geometric surface area (mm²) can be calculated. 2 / mm 3) of the partition wall 1. The “length of the surface of partition wall 1” means the perimeter of a cell 2 when cell 2 is viewed from the end face of the honeycomb structure 100.

[0024] The value represented by the above expression (2) is in the range of 8 to 50 (µm × mm). 2 / mm 3 ) effectively suppresses catalyst flaking and also effectively suppresses fracture due to a compacting surface pressure applied to the outer circumferential surface of the honeycomb structure 100 during dosing. The value represented by the above expression (2) is preferably 10 to 40 (µm × mm ). 2 / mm 3 ) and more preferably 20 to 30 (µm × mm 2 / mm 3 ).

[0025] The average pore diameter (µm) of the partition 1 is preferably in the range of 1 to 20 µm, more preferably in the range of 3 to 15 µm, and particularly preferably in the range of 4 to 13 µm. An average pore diameter (µm) of the partition 1 smaller than 1 µm is not advantageous from the point of view of catalyst detachment. For example, the amount of catalyst penetrating the interior of the partition 1 is small, such that the contact area between the catalyst layer formed with the partition 1 is small, and therefore the catalyst can easily detach. An average pore diameter (µm) of the partition 1 exceeding 20 µm is not advantageous from the point of view of cleaning performance.For example, a significant amount of the catalyst penetrates the partition 1 and the amount of catalyst on the surface of partition 1, which contributes to cleaning, decreases, such that the cleaning performance may decrease.

[0026] The geometric surface area (mm²) 2 / mm 3 The thickness of the partition wall 1 is preferably in the range of 1 to 4 mm. 2 / mm 3 , more preferably in the range of 1.5 to 3.5 mm 2 / mm 3 and particularly preferably in the range of 2 to 3 mm 2 / mm 3 A geometric surface (mm²) 2 / mm 3 ) of the partition 1, which is smaller than 1 mm 2 / mm 3 This is not advantageous from the standpoint of temperature rise properties. A geometric surface (mm²) 2 / mm 3 ) of partition wall 1, which is 4 mm 2 / mm 3Exceeding this limit is not advantageous from the standpoint of soot clogging. For example, this makes it difficult to increase the diameter of the open ends of cells 2, and therefore cells 2 can easily become clogged with soot.

[0027] The honeycomb structure 100 has a hydraulic diameter of the cells 2, which are surrounded by the partition 1, of 1.1 mm or more. The "hydraulic diameter of the cells 2" is a value calculated based on the cross-sectional area and the perimeter of each cell 2 by 4 × (cross-sectional area) / (perimeter). The hydraulic diameter of the cells 2 is preferably in the range of 1.1 to 1.7 mm, more preferably in the range of 1.2 to 1.6 mm, and particularly preferably in the range of 1.3 to 1.5 mm. A hydraulic diameter of the cells 2 smaller than 1.1 mm causes a tendency for the cells 2 to become clogged with suspended particles such as soot in an exhaust gas.

[0028] The partition 1 preferably has a surface roughness Ra of 1 µm or more, more preferably in the range of 1 to 4 µm, and particularly preferably in the range of 1.5 to 3.5 µm. A surface roughness Ra of the partition 1 of less than 1 µm is not advantageous from the standpoint of maintaining the honeycomb structure during dispensing. That is, due to the manufacturing process, the partition 1 and the circumferential wall 3 of the honeycomb structure 100 have essentially the same surface roughness, and therefore the surface roughness of the circumferential wall 3 will be small. In this case, it can be difficult to maintain the stability of the honeycomb structure 100 during dispensing. The surface roughness Ra of the partition 1 can be a value measured using a three-dimensional measuring instrument according to the method described in JIS B0633:2001.

[0029] The honeycomb structure 100 preferably has a partition wall thickness 1 in the range of 0.06 to 0.21 mm, and more preferably in the range of 0.07 to 0.15 mm. The thickness of the partition wall 1 can be measured, for example, with a scanning electron microscope or a microscope. A partition wall thickness 1 of less than 0.06 mm may result in insufficient strength. A partition wall thickness 1 exceeding 0.21 mm may cause an increase in pressure loss.

[0030] The shape of the cells 2 in the honeycomb structure 4 is not particularly restricted. For example, the cells 2 in a cross-section perpendicular to the direction of expansion of the cells 2 can have a polygonal shape, a circular shape, an elliptical shape, and the like. Examples of polygonal shapes include a triangle, a quadrilateral, a pentagon, a hexagon, and an octagon. Preferably, the shape of the cells 2 is a triangle, a quadrilateral, a pentagon, a hexagon, and an octagon. Regarding the shape of the cells 2, all cells 2 can have the same shape, or the cells 2 can have different shapes. For example, although not shown, quadrilateral and octagonal cells can be combined. With respect to the size of the cells 2, all cells 2 can have the same size, or the cells 2 can have different sizes. For example, although not shown, some of the several 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.

[0031] Preferably, the cells 2, which are defined by the partition 1, have a cell density in the range of 30 to 70 cells / cm². 2 , more strongly preferred in the range of 35 to 65 cells / cm² 2 and especially preferably in the range of 40 to 50 cells / cm² 2 The honeycomb structure 100 of the present embodiment with this configuration can advantageously be used as a cleaning element (e.g. a catalyst carrier) to clean exhaust gas emitted by an automotive engine.

[0032] The perimeter wall 3 of the honeycomb structure body 4 can be monolithic with the partition wall 1 or it can be a perimeter coating layer formed by applying a perimeter coating material such that it surrounds the partition wall 1. Although not shown, the partition wall and the perimeter wall can be formed monolithically during the manufacturing process, and then the formed perimeter wall can be removed by a known method such as grinding. The perimeter coating layer can then be applied to the perimeter of the partition wall.

[0033] The shape of the honeycomb structure body 4 is not particularly restricted. Examples of the shape of the honeycomb structure body 4 include a column shape, where the first end face 11 and the second end face 12 have a shape such as a circle, an ellipse, or a polygon.

[0034] The dimensions of the honeycomb structure body 4, which include the length from the first end face 11 to the second end face 12 and the size of a cross-section perpendicular to the direction of expansion of the cells 2 of the honeycomb structure body 4, are not particularly limited. The dimensions of the honeycomb structure body 4 can be selected such that the honeycomb structure 100 of the present embodiment can exhibit optimal self-cleaning capabilities when used as an element for cleaning exhaust gases. For example, the length from the first end face 11 to the second end face 12 of the honeycomb structure body 4 is preferably in the range of 72 to 254 mm and more preferably in the range of 102 to 203 mm. The area of ​​a cross-section perpendicular to the direction of expansion of the cells 2 of the honeycomb structure body 4 is preferably in the range of 1900 to 130000 mm². 2 and more strongly preferred in the range of 5000 to 100000 mm 2 .

[0035] Preferably, the partition 1 is made of at least one type of material selected from the group consisting of cordierite, silicon carbide, silicon nitride, and mullite. The partition 1 preferably contains materials comprising 20 wt% or more, more preferably 30 wt% or more, and particularly preferably 50 wt% or more.

[0036] In the honeycomb structure 100, the partition 1, which defines the multiple cells 2, can be loaded with a catalyst for exhaust gas purification. The partition 1 being loaded with a catalyst refers to the loading of the catalyst on the surface of the partition 1 or in the pores formed within the partition 1. In particular, the honeycomb structure 100 allows an increased amount of catalyst to be loaded into the pores of the partition 1 and can therefore prevent an increase in pressure loss after loading with the catalyst for exhaust gas purification.

[0037] The amount of catalyst applied to the partition wall 1 of the honeycomb structure 4 per unit volume can be suitably determined depending on the type of catalyst used. One method for loading the catalyst is to apply a catalyst slurry containing a catalyst component to the honeycomb structure 4 by washing, followed, for example, by high-temperature heat treatment for combustion. Examples of catalysts for exhaust gas purification include an SCR catalyst.

[0038] The honeycomb structure 100 can be advantageously used for a catalyst carrier intended to be loaded with a catalyst for exhaust gas purification, such as an SCR catalyst as described above. The honeycomb structure 100, loaded with the catalyst, is installed for use in the exhaust system of an internal combustion engine. In use, the honeycomb structure 100, loaded with the catalyst, can advantageously be positioned upstream of an oxidation catalyst (not shown) or an exhaust gas purification filter (not shown) installed separately in the exhaust system. (2) Method for producing a honeycomb structure:

[0039] There is no specific limitation to the method for producing the honeycomb structure of the present invention, and the honeycomb structure can be produced, for example, by the following method. First, a kneaded material possessing plasticity is prepared to generate a honeycomb structure body. The kneaded material for generating a honeycomb structure body can be prepared by adding additives such as binders, pore-forming agents, and water as required to a material selected as a raw material powder from the aforementioned materials suitable for the honeycomb structure body. Examples of binders include methylcellulose and hydroxypropyl methylcellulose. Examples of additives include a surfactant. The porosity and average pore diameter of the partition can be controlled by adjusting the particle diameter and the amount of pore-forming agent.

[0040] The kneaded material prepared in this way is then extruded, producing a columnar honeycomb shape with a partition wall defining multiple cells and a circumferential wall surrounding this partition. For extrusion of the honeycomb shape, the open end face (%) of the honeycomb shape is preferably adapted to a desired value using an extrusion die.

[0041] The resulting honeycomb-shaped piece is then dried, for example, using microwaves and hot air. Afterward, it is fired to create the honeycomb structure. The firing temperature and atmosphere vary depending on the raw material, and experts can select the temperature and atmosphere best suited to the chosen material. (Examples)

[0042] The present invention will be described below, particularly in the form of examples, and the present invention is by no means limited to these examples. (Example 1)

[0043] Ten parts by mass of pore-forming agent, four parts by mass of dispersion medium, and four parts by mass of organic binder were added to 100 parts by mass of the cordierite-forming raw material, followed by mixing and kneading to produce a kneaded material. The cordierite-forming raw material consisted of 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. A water-absorbing polymer with an average particle diameter of 5 µm was used as the pore-forming agent.

[0044] The kneaded material was then extruded using a die to create a honeycomb-shaped body, resulting in a honeycomb-shaped body with a round column shape as its overall form. The cells of the honeycomb-shaped body were rectangular.

[0045] The honeycomb mold was then dried in a microwave dryer, then completely dried in a hot air dryer, and then both end faces of the honeycomb mold were trimmed to specified dimensions. The dried honeycomb mold was then degreased and baked to obtain a honeycomb structure as shown in Example 1.

[0046] The honeycomb structure of Example 1 had a columnar shape, with the first and second end faces being round. The first and second end faces had a diameter of 190.5 mm. The honeycomb structure had a length of 101.6 mm in the cell expansion direction. The honeycomb structure of Example 1 had a septal thickness of 0.114 mm and a cell density of 62.0 cells / cm³. 2 and a cell spacing of 1.27 mm. The open end face of the honeycomb structure was 82.8%. The hydraulic diameter of the cells was 1.16 mm. Table 1 shows the results. [Table 1] Partition wall thickness Cell density Cell spacing Porosity P Open forehead area A Value of expression (1)(* 1 ) Hydraulic diameter Geometric surface G average pore diameter D Value of expression (2) (*2) Surface roughness Ra mm Cells / cm 2 mm % % - mm mm 2 / mm 3 µm µm ×mm 2 / mm 3 µm Example 1 0,114 62,0 1,27 45 82,8 0,09 1,16 2,87 6 17 2,1 Example 2 0,089 62,0 1,27 30 86,5 0,09 1,18 2,93 4 12 1,8 Example 3 0,132 46,5 1,47 50 82,8 0,09 1,33 2,48 20 50 1,7 Example 4 0,140 31,0 1,80 30 85,0 0,10 1,66 2,05 4 8 2,2 Example 5 0,089 46,5 1,47 30 88,2 0,08 1,38 2,56 4 10 2,0 Example 6 0,114 62,0 1,27 50 82,8 0,09 1,16 2,87 13 37 2,0 Example 7 0,132 46,5 1,47 35 82,8 0,11 1,33 2,48 4 10 2,3 Example 8 0,114 62,0 1,27 35 82,8 0,11 1,16 2,87 4 11 3,0 Example 9 0,114 46,5 1,47 35 85,0 0,10 1,35 2,52 4 10 2,6 Example 10 0,114 62,0 1,27 30 82,8 0,12 1,16 2,87 13 37 2,4 Example 11 0,089 69,8 1,20 30 85,7 0,10 1,11 3,09 13 40 2,2 See example 1. 0,175 62,0 1,27 50 74,3 0,13 1,09 2,71 4 11 2,1 See example 2. 0,064 93,0 1,04 28 88,1 0,09 0,97 3,62 4 14 2,3 See example 3. 0,089 93,0 1,04 50 83,6 0,08 0,95 3,53 11 39 2,5 See example 4. 0,132 46,5 1,47 35 82,8 0,11 1,33 2,48 3 7 2,4 See example 5. 0,089 93,0 1,04 50 83,6 0,08 0,95 3,53 20 71 2,6 See example 6. 0,089 77,5 1,14 51 85,0 0,07 1,05 3,25 18 58 2,0 See example 7. 0,114 62,0 1,27 50 82,8 0,09 1,16 2,87 20 57 1,8 *1 Expression (1): (1 - A / 100) × (1 - P / 100) *2 Expression (2): D × G

[0047] For the honeycomb structure of Example 1, the “porosity P (%)”, the “geometric surface area G (mm²)” were used. 2 / mm 3 The average pore diameter D (µm) and surface roughness Ra (µm) were measured using the following method. Table 1 shows the results. [Porosity P (%)]

[0048] 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 out from the honeycomb structure to create a test specimen, and the porosity of the resulting specimen was measured. The test specimen was a cuboid approximately 10 mm wide, 10 mm high, and 10 mm deep. The test specimen was cut from a section near the center along the axial direction of the honeycomb structure. [Geometric surface area G (mm) 2 / mm 3 )]

[0049] The geometric surface was measured using an optical microscope. [Average pore diameter D (µm)]

[0050] The average pore diameter of the partition was measured using Autopore 9500 (product name), manufactured by Micromeritics Co. The average pore diameter was measured using the same test specimen as in the porosity measurement. [Surface roughness Ra (µm)]

[0051] The surface roughness was measured using a three-dimensional measuring instrument.

[0052] For the honeycomb structure of Example 1, the porosity P was 45%, and the geometric surface area G was 2.87 mm². 2 / mm 3 The average pore diameter D was 6 µm and the surface roughness Ra was 2.1 µm. Based on these values, the values ​​of “expression (1)” were determined. (1- A / 100) × (1 - P / 100)" and "Expression (2): D × G" are calculated. Table 1 shows the result.

[0053] A catalyst was loaded onto the partition wall of the honeycomb structure of Example 1 by the following procedure. First, a catalyst slurry containing zeolite as the catalyst was prepared. This catalyst slurry was loaded onto the honeycomb structure such that the loading quantity per unit volume after drying was 150 g / L. To load the catalyst, the honeycomb structure was immersed in the catalyst slurry for impregnation, followed by blowing with air to remove the excess catalyst slurry. This was dried at a temperature of 120 °C, followed by a heat treatment at 500 °C for 3 hours, resulting in a honeycomb structure loaded with the catalyst. The catalyst loading quantity in the honeycomb structure of Example 1 was 150 g / L.

[0054] For the honeycomb structure of Example 1, which was loaded with the catalyst in this manner, a "temperature increase test", a "soot clogging test", a "catalyst flaking test" and a "dosage test" were carried out using the following procedure. Table 2 shows the result. [Table 2] Temperature rise test Soot blockage test Catalyst peel test Dosage test Result Result Result Result Example 1 OK OK OK OK Example 2 OK OK OK OK Example 3 OK OK OK OK Example 4 OK OK OK OK Example 5 OK OK OK OK Example 6 OK OK OK OK Example 7 OK OK OK OK Example 8 OK OK OK OK Example 9 OK OK OK OK Example 10 OK OK OK OK Example 11 OK OK OK OK See example 1. NG NG OK OK See example 2. OK NG OK OK See example 3. OK NG OK OK See example 4. OK OK NG OK See example 5. OK NG NG OK See example 6. OK NG NG NG See example 7. OK OK OK NG [Temperature rise test]

[0055] A heating test of the honeycomb structure was performed using a propane gas burner test fixture, which includes a metal housing to accommodate the honeycomb structure, and a propane gas burner configured to feed the heated gas into the metal housing. The heating gas was a combustion gas generated by burning propane with the gas burner (propane gas burner). The temperature rise characteristic was evaluated by measuring the time required in the aforementioned heating test for the honeycomb structure to reach 450 °C. Specifically, the obtained honeycomb structure was housed (dosed) in the metal housing of the propane gas burner test fixture. Then, gas (combustion gas) heated by the propane gas burner was introduced into the metal housing to allow the gas to pass through the honeycomb structure. The temperature conditions (inlet gas temperature conditions) of the heating gas flowing into the metal housing were as follows.First, the temperature was raised to 600 °C in 2 minutes and held at 600 °C for 10 minutes. This series of operations to raise and hold the temperature is called a "temperature ramp operation." Afterward, the time it took for the honeycomb structure to reach 450 °C was checked. In Table 2, honeycomb structures that took 23 seconds or less are marked "OK," and those that took longer than 23 seconds are marked "NG." [Soot blockage test]

[0056] A soot clogging test for the honeycomb structure was performed using a metal housing to contain the honeycomb structure and a power unit or soot generator configured to inject heated gas into the metal housing. The gas was heated for 3 hours at a gas temperature of 200 °C and a flow rate of 1.5 Nm³ / h. 3A flow rate of / min was passed through the honeycomb structure (dimensions: diameter 190.5 mm and total length 101.6 mm), and then the surface of the cells of the honeycomb structure was observed with an optical microscope. If less than 1 / 2 of the surface of the cells of the honeycomb structure was blocked with soot, the honeycomb structure was OK, and if more than 1 / 2 of the surface of the cells was blocked with soot, the honeycomb structure was NG. [Catalytic converter flaking test]

[0057] 0.5 MPa factory air was sprayed onto the honeycomb structure using an air gun. If the weight change between before and after spraying was less than 5%, the honeycomb structure was OK. If the weight change was 5% or more, the honeycomb structure was NG. [Dosage test]

[0058] The isostatic strength of the honeycomb structure was measured. Honeycomb structures exhibiting an isostatic strength of 1 MPa or more were rated OK, and those exhibiting an isostatic strength of less than 1 MPa were rated NG. The isostatic strength was measured in accordance with the isostatic fracture strength test specified in M505-87 of the Japan Automotive Standards Organization (JASO), a specification issued by the Society of Japanese Automotive Engineers. The isostatic fracture strength is tested by placing a honeycomb structure in a rubber tubular container sealed with an aluminum plate and subsequently applying isostatic pressure to it in water. The isostatic strength measured by the isostatic fracture strength test is expressed as the pressure (MPa) applied when the honeycomb structure fractures. (Examples 2 to 11)

[0059] The honeycomb structures of these examples were produced by modifying the honeycomb structure as shown in Table 1. The porosity P and the average pore diameter D were adjusted by changing the amount and size of the pore-forming agent. The geometric surface area G was adjusted by changing the die. Examples 2 through 11 were modified during production as follows.

[0060] In example 2, the amount of pore-forming agent added was The pore-forming agent had an average particle diameter of 5 µm and was present in 10 parts by mass. The added quantity of pore-forming agent represents a ratio to 100 parts by mass of the cordierite-forming raw material, and the same applies to the other examples. (Comparative examples 1 to 7)

[0061] The honeycomb structures of these comparative examples were created by modifying the honeycomb structure as shown in Table 1. Comparative examples 1 to 7 were modified as follows during the manufacturing process.

[0062] In comparative example 1, the amount of pore-forming agent added was 5 parts by mass and the pore-forming agent had an average particle diameter of 3 µm.

[0063] For the honeycomb structures of examples 2 to 11 and the comparative examples 1 to 7, a "temperature increase test", a "soot clogging test", a "catalyst peeling test" and a "dosing test" were performed. Table 2 shows the results. (Result)

[0064] The honeycomb structures of Examples 1 to 11 showed good results in all of the "temperature rise test," the "soot clogging test," the "catalyst flaking test," and the "dosing test." In contrast, the honeycomb structure of comparative Example 1 had a value of expression (1) of 0.13, which resulted in poor temperature rise properties in the temperature rise test. The honeycomb structures of comparative Examples 1 to 3, 5, and 6 had a hydraulic cell diameter of less than 1.1 mm, and the cells of these honeycomb structures became clogged with soot in the soot clogging test. The honeycomb structure of comparative Example 4 had a value of expression (2) of 7 and exhibited catalyst flaking during the catalyst flaking test. The honeycomb structures of comparative examples 5 and 6 also showed catalyst flaking during the catalyst flaking test.Presumably, the catalyst flaking of the honeycomb structure in comparative example 5 was caused by the high cell density and the small hydraulic diameter. The honeycomb structure in comparative example 6 had a value of expression (1) of 0.07 and also failed the dosing test. The honeycomb structure in comparative example 7 had a value of expression (2) of 57 and also failed the dosing test.

[0065] The honeycomb structure of the present invention can be used to load a catalyst carrier with a catalyst for cleaning exhaust gas. Reference symbol list 1 partition wall 2 cells 3 Perimeter wall 4 honeycomb structure bodies 11 first front 12 second front 100 honeycomb structure

Claims

[1] Honeycomb structure (100) comprising a columnar honeycomb structure body (4) having a first end face (11) and a second end face (12) and having a porous partition (1) arranged to surround several cells (2), the several cells (2) extending from the first end face (11) to the second end face (12) and serving as a fluid passage channel, wherein Assuming that A denotes an amount of open end face (%) in a plane of the honeycomb structure body (4) perpendicular to the extension direction of the cells (2) and P denotes an amount of porosity (%) of the partition (1), the honeycomb structure (100) has a value represented by the following expression (1) which is in the range of 0.05 to 0.12, assuming that D denotes an average pore diameter (µm) of the partition (1) and G a geometric surface area (mm²) 2 / mm 3) of the partition (1) denotes the honeycomb structure (100) has a value represented by the following expression (2), which is in the range of 8 to 50 (µm × mm 2 / mm 3 ) lies, and the honeycomb structure (100) has a hydraulic diameter of the cells that is 1.1 mm or more, wherein (1−A / 100)×(1−P / 100) and D×G. [2] Honeycomb structure (100) according to claim 1, wherein the partition (1) comprises at least one type selected from the group consisting of cordierite, silicon carbide, silicon nitride and mullite. [3] Honeycomb structure (100) according to claim 1 or 2, wherein the partition (1) has a surface roughness Ra of 1 µm or more. [4] Honeycomb structure (100) according to any one of claims 1 to 3, wherein the honeycomb structure (100) is installed in an exhaust system of an internal combustion engine and is arranged upstream of an oxidation catalyst or an exhaust gas purification filter, which is installed separately in the exhaust system.

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