JP5390439B2 - Honeycomb catalyst body - Google Patents

Description

  The present invention relates to a honeycomb structure capable of supporting a large number of catalysts and preventing a decrease in strength and an increase in pressure loss, and a honeycomb catalyst body.

  In order to comply with the next diesel exhaust gas regulations (particularly NOx), it is necessary to support more catalyst on the honeycomb carrier than before. However, an increase in the amount of catalyst supported is accompanied by an increase in the thickness of the catalyst layer formed on the surface of the cell partition wall, thereby reducing the cell opening ratio and the hydraulic diameter, thereby causing an increase in pressure loss. Therefore, by increasing the porosity of the honeycomb carrier (higher porosity) than that of the conventional honeycomb carrier so that the catalyst is supported as much as possible in the open pores of the cell partition walls, the cell opening ratio and hydraulic diameter are increased. , The increase in the thickness of the catalyst layer formed on the cell partition wall surface can be suppressed, and the increase in pressure loss can be avoided. On the other hand, increasing the porosity of the honeycomb carrier causes a decrease in the strength of the honeycomb carrier.

  As a method for avoiding this decrease in strength, as shown in FIG. 4A, a honeycomb structure in which a portion having an R-shaped curvature (hereinafter referred to as “R portion” as appropriate) is added to the intersection portion 109 between the cell 103 and the partition wall 102. (Conventional honeycomb structure). In this conventional honeycomb structure, when a large number of catalysts are supported, as shown in FIG. 4B, the R portion is added to the intersection of the cell partition walls, so that a decrease in strength can be suppressed. However, when the R portion is added to the intersection of the cell partition walls, the conventional honeycomb structure is coated with the catalyst 105 nonuniformly as shown in FIG. 4C, for example. In particular, as shown in FIG. 4C, a large amount of catalyst 105 is deposited at the cell corner, and a non-uniform catalyst layer 105a is formed as seen in the hatched area. As a result, new problems such as a decrease in cell opening ratio and hydraulic diameter and an increase in pressure loss have arisen. In addition, a part of the catalyst deposited at the cell corner portion is not effectively used for exhaust gas purification, and there is a problem that a wasteful catalyst exists.

  Moreover, the following patent documents 1 and 2 are disclosed as a method of avoiding strength reduction.

  In Patent Document 1, for the purpose of providing a ceramic honeycomb structure capable of obtaining sufficient mechanical strength even if the partition walls are made thinner, the first region including the center in the plane perpendicular to the through passage is provided. Reinforcing portions are provided at the respective corners of the through passage existing in the outer second region. Further, it is disclosed that the reinforcing portion has an arc shape or a straight fillet shape.

  In Patent Document 2, a honeycomb having an isotropic strength that does not suffer chipping or cracking damage during handling and canning operations, and a honeycomb that retains thermal shock characteristics and can prevent an increase in pressure drop are disclosed. For the purpose of providing, a honeycomb is disclosed in which a plurality of cells are classified into a first region including some cells in the vicinity of the outer peripheral wall and a second region including the remaining cells. In the honeycomb, the thickness of the cell walls in the first region continuously increases along the axis extending toward the outer peripheral wall, and fillets are formed at least at the intersections between the inner walls of the cells in the first region. Has been. The fillet has a radius, and the fillet radius increases continuously along an axis extending toward the outer peripheral wall.

Japanese Patent Laid-Open No. 10-264125 JP 2006-519953 A

  However, as in Patent Document 1, a reinforcing portion is provided at each corner of the through-passage, and the reinforcing portion is reduced to an arc shape or a straight fillet shape, thereby reducing the cell opening ratio and the hydraulic diameter. It cannot be prevented and pressure loss cannot be reduced. Therefore, a part of the catalyst deposited on the cell corner portion is not effectively used for exhaust gas purification, and a wasteful catalyst exists. In particular, since the size of the reinforcing portion in Patent Document 1 is 0.15 mm at the maximum, the catalyst is not uniformly coated. This is also shown in the size (0.2 mm) of the reinforcing portion of Comparative Examples 1, 5, 9, and 13 shown in the same document. Further, as in Patent Document 2, even if fillets are formed at the intersections between the inner walls of the cell, the catalyst is unevenly coated when the catalyst is supported, and a large amount of catalyst is deposited particularly on the cell corner. End up. Therefore, as in Patent Document 1, it does not solve the new problem that the cell opening ratio / hydraulic diameter decreases and the pressure loss increases.

  An object of the present invention is to provide a honeycomb structure and a honeycomb catalyst body in which the catalyst layer can be made uniform along the cell shape, and the increase in pressure loss can be reduced by making the catalyst layer uniform. In particular, by making the catalyst layer uniform, most of the catalyst can be effectively utilized. When obtaining a NOx purification rate equivalent to that of the prior art, the amount of catalyst can be reduced, and a triangle is formed at a part of the intersection of the cell partition walls. An object of the present invention is to provide a honeycomb structure and a honeycomb catalyst body capable of avoiding a decrease in strength due to a high porosity because the shape is added.

  The inventors of the present invention have an octagonal cross-sectional shape of the cell, and a part of the partition wall intersection part corresponds to the hypotenuse of the octagon in the cross-sectional shape of the cell, and the virtual lines drawn from both ends of the hypotenuse The shape formed when intersecting at the intersection part side is a triangle, and each of the intersection triangle lengths from the hypothetical line to the intersection point from both ends of the hypotenuse is the cell pitch CP, the partition wall thickness The present inventors have found that the above-mentioned problems can be solved by constituting a honeycomb structure having a length of 0.2 (CP-WT) mm to 0.35 (CP-WT) mm, where WT is WT. That is, according to the present invention, the following honeycomb structure and honeycomb catalyst body are provided.

[1] A honeycomb structure having a partition wall made of a porous body, in which a large number of cells serving as fluid flow paths are partitioned by the partition wall, and the partition walls of the partition walls forming the cells A partition intersection portion is formed in a region where the cells intersect, and the cross-sectional shape of the cell is an octagon, and a part of the partition intersection portion corresponds to the hypotenuse of the octagon in the cross-sectional shape of the cell. The shape formed when the virtual line drawn from both ends of the hypotenuse crosses on the partition intersection point side is a triangular shape, and the virtual line to the point crossed from both ends of the hypotenuse intersection triangle the length of each is the cell pitch CP, a partition wall thickness upon a WT, the honeycomb structure having a length of 0.2 (CP-WT) mm~0.35 ( CP-WT) mm , Hani carrying automobile exhaust gas purification catalyst Cam catalyst body.

[2] The honeycomb catalyst body according to [1], wherein the intersection triangular length is 0.2 (CP-WT) mm to 0.3 (CP-WT) mm .

[3] The honeycomb catalyst body according to [1] or [2], comprising at least one selected from the group of cordierite, SiC, mullite, aluminum titanate, and alumina .

  The cell cross-sectional shape is an octagon, and part of the partition wall intersection part corresponds to the hypotenuse of the octagon in the cell cross-section, and the virtual line drawn from both ends of the hypotenuse crosses on the partition wall intersection side. In this case, when the cell pitch is CP and the partition wall thickness is WT, each of the imaginary lines has a triangular shape, and each of the intersection triangle lengths from the opposite sides of the hypotenuse of the hypothetical line is CP. By configuring as a honeycomb structure having a length of 0.2 (CP-WT) mm to 0.35 (CP-WT) mm, the catalyst layer can be made uniform along the cell shape. By making the catalyst layer uniform, an increase in pressure loss can be reduced. Further, since the catalyst layer is made uniform, most of the catalyst can be effectively utilized. Therefore, when obtaining a NOx purification rate equivalent to that of the prior art, the amount of catalyst can be made smaller than that of the prior art. Furthermore, since a triangular shape is added to a part of the intersections of the cell partition walls, it is possible to avoid a decrease in strength due to a high porosity.

It is a perspective view which shows one Embodiment of the honeycomb structure of this invention, and is a schematic diagram. It is the elements on larger scale of the end surface of the honeycomb structure of the present invention, and is a mimetic diagram. FIG. 4 is a partially enlarged view of the end face of the honeycomb structure of the present invention, and is a schematic view showing the structure of cells and partition walls. It is a schematic diagram for demonstrating the state before adhering a catalyst layer in the partition of the honeycomb catalyst body of this invention. It is a schematic diagram for demonstrating the state after attaching the catalyst layer in the partition of the honeycomb catalyst body of this invention. It is the elements on larger scale of the end surface of the conventional honeycomb structure, and is a mimetic diagram. It is a conventional honeycomb catalyst body, and is a schematic diagram for explaining a state before attaching a catalyst layer in a partition provided with an R portion. It is a conventional honeycomb catalyst body, and is a schematic diagram for explaining a state after a catalyst layer is attached in a partition wall having an R portion. It is a schematic diagram for demonstrating the die for extrusion molding used in order to manufacture the honeycomb structure of this invention. It is a schematic diagram for demonstrating the nozzle | cap | die for adding R part to an intersection part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

  FIG. 1 shows a perspective view of the honeycomb structure of the present invention. 2A and 2B are enlarged views of an end face of the honeycomb structure. The honeycomb structure 1 includes partition walls 2 made of a porous body, and the partition walls 2 define and form a large number of cells 3 serving as fluid flow paths. In the honeycomb structure 1, partition intersection points 10 are formed in regions of the partition walls 2 forming the cells 3 where the partition walls intersect with each other. Furthermore, the cross-sectional shape of the cell 3 is an octagon, and a part of the partition wall intersection 10 corresponds to the octagonal hypotenuse 10 a in the cross-sectional shape of the cell 3. The shape formed when the virtual lines drawn from both ends of the hypotenuse 10a intersect on the partition intersection point side is a triangle, and the triangle of the hypothetical lines up to the point intersected from both ends of the hypotenuse 10a Each of the lengths a has a length of 0.2 (CP-WT) mm to 0.35 (CP-WT) mm when the cell pitch is CP and the partition wall thickness is WT. This honeycomb structure is configured.

  Here, the partition wall intersection portion 10 means an intersection region where the partition walls intersect each other. Specifically, it is shown in FIG. 3A. On the other hand, FIGS. 4A to 4C show enlarged views of an end face of a conventional honeycomb structure having an R portion at the intersection 109 of the cell partition wall 102. FIG. 4B is an enlarged view of FIG. 4A. As shown in FIG. 4A and FIG. 4B, the conventional honeycomb structure also has partition wall intersections, but the partition wall intersections are formed in an R shape. Therefore, as shown in FIG. 4C, when the catalyst 105 is attached to the partition wall, the attached catalyst layer 105a is curved and formed in an R shape. Further, the catalyst layer 5 becomes thick in the vicinity of the partition wall intersection.

  On the other hand, when formed as in the present embodiment, as shown in FIGS. 2A, 2B, and 3A, a part of the partition wall intersection portion corresponds to the octagonal hypotenuse 10a in the cross-sectional shape of the cell. The catalyst layer 5a formed by adhering 5 to the partition walls can be made thinner in the vicinity of the partition wall intersection than the conventional honeycomb structure. In other words, a part of the intersection of the partition walls is configured as a hypotenuse that is a straight line except for one having an R-shaped curvature. Moreover, the partition intersection point portion 10 is configured by an intersection region where the partition walls intersect each other. Therefore, the intersection region is an octagonal region.

  3A and 3B is an imaginary line drawn to distinguish the above-described partition wall intersection part and partition walls other than the partition wall intersection part, and is not actually drawn. Therefore, the material, porosity, etc. of the partition intersection portion and the other partition walls are the same. 4B and 4C is also an imaginary line drawn to separate the partition wall intersection part and the partition wall other than the partition wall intersection part, and is not actually drawn. The material of the intersection part and the partition, the porosity, etc. are the same.

  Further, since “the cross-sectional shape of the cell is an octagon”, triangular cells and quadrangular cells are excluded. Further, “both ends of the hypotenuse” mean both ends corresponding to the apex angle of the octagon between the hypotenuse of the octagonal cell and another side adjacent to the hypotenuse. The “virtual line drawn from both ends of the hypotenuse” means an imaginary line (imaginary line) drawn from both ends described above, and is not actually drawn by the partition wall. Specifically, virtual lines b and b drawn from both end portions 10b and 10b of the hypotenuse 10a shown in FIG. 2B can be mentioned. In addition, “the shape formed when intersecting on the partition wall intersection part side is a triangular shape” means that when the above virtual line is intersected on the partition wall intersection part side, the hypotenuse and the virtual line It means that the shape formed by the intersection is triangular. Specifically, as shown in FIG. 2B, a triangle T formed by the intersection of the hypotenuse 10a and the imaginary lines b and b when the imaginary lines b and b are intersected at the partition wall intersection 10 side. be able to.

  In addition, “each of the triangular lengths of the intersection of the imaginary line from the both ends of the hypotenuse to the intersecting point” means that each imaginary line from the two sides of the hypotenuse to the point of intersection with each other is drawn. Means the length of the intersection triangle. Specifically, as shown in FIG. 2B, an intersection triangle length a up to a point where virtual lines b and b drawn from both ends of the hypotenuse 10a intersect each other can be mentioned. However, since each of the sides having the intersection triangle length is equivalent to two sides of an isosceles triangle having the same length in the above-described triangle shape, either one is short (or Long ones) are excluded. Moreover, it is not limited to a right-angled isosceles triangle as shown in FIG. 2B. In addition, “each of the intersection triangle lengths is 0.2 (CP−WT) mm to 0.35 (CP−WT) mm when the cell pitch is CP and the partition wall thickness is WT”. “0.2 to 0.35” indicates a value of the ratio of the intersection triangle length a to the cell width. For example, when the partition wall thickness (WT) is 0.3 mm, the cell pitch (CP) is 1.80 mm, and the ratio of the intersection triangle length a to the cell width is 0.35, the intersection triangle length a Is 0.525 mm.

  Preferably, the intersection triangle length is 0.2 (CP-WT) mm to 0.3 (CP-WT) mm. The catalyst layer can be made more uniform along the cell shape, and the increase in pressure loss can be reliably reduced. The curve of the catalyst layer at the partition intersection is eliminated and the catalyst layer can be thinned. As a result, an increase in pressure loss can be avoided, and the catalyst layer can be made uniform so that most of the catalyst can be effectively utilized.

  Moreover, the porosity of the partition walls 2 is preferably 40 to 80%, and more preferably 45 to 80%. If the porosity is less than 40%, the catalyst does not sufficiently enter the partition walls, and the thickness of the catalyst layer formed on the partition surfaces increases, and the pressure loss tends to increase. On the other hand, when the porosity exceeds 80%, the strength tends to be insufficient.

  As a material used for the honeycomb structure 1, a material made of at least one selected from the group consisting of cordierite, SiC, mullite, aluminum titanate, and alumina can be used.

  In addition, the shape of the cross section of the honeycomb structure 1 of the present embodiment cut in the radial direction on a plane perpendicular to the cell communication direction is preferably a shape suitable for the internal shape of the exhaust system to be installed. Specific examples include a circle, an ellipse, an ellipse, a trapezoid, a triangle, a quadrangle, a hexagon, and a deformed shape that is asymmetrical to the left and right. Of these, a circle, an ellipse, and an ellipse are preferable.

In addition, it is preferable that the cell density is 30 cells / cm ² or more and less than 100 cells / cm ² and the partition wall thickness is 50 μm or more and less than 310 μm. When the cell density is less than 30 cells / cm ² , the contact efficiency with the exhaust gas tends to be insufficient. On the other hand, when the cell density is 100 cells / cm ² or more, the pressure loss tends to increase. If the partition wall thickness is less than 50 μm, the thermal shock resistance may deteriorate due to insufficient strength. On the other hand, when the partition wall thickness is 310 μm or more, the pressure loss tends to increase. Preferably, the partition wall has a thickness of 110 μm or more and less than 300 μm.

  Further, the CP (cell pitch) is preferably 0.85 mm or more and 3.59 mm or less, and more preferably 1.27 mm or more and 1.80 mm or less. When the CP (cell pitch) is less than 0.85 mm, the contact efficiency with the exhaust gas tends to be insufficient. On the other hand, when CP (cell pitch) is more than 3.59 mm, the pressure loss tends to increase.

  The present invention is a honeycomb catalyst body in which an automobile exhaust gas purification catalyst is supported on the above-described honeycomb structure. That is, the honeycomb catalyst body of the present invention is one in which a catalyst layer is formed by supporting a catalyst on both the partition wall surface and the inner surface of the pores of the honeycomb structure 1 described above. Will be described.

  In the present embodiment, the average pore diameter of the partition walls is preferably 5 to 100 μm, more preferably 10 to 80 μm, and particularly preferably more than 15 μm and 60 μm or less. When the average pore diameter is less than 5 μm, for example, carbon fine particles and fine particles such as ash contained in the exhaust gas discharged from the engine are easily captured, and the pores are blocked. On the other hand, if the average pore diameter is more than 100 μm, it tends to be difficult to ensure a sufficient contact area between the exhaust gas and the catalyst layer. The average pore diameter can be measured with a mercury porosimeter.

  Specific examples of the catalyst contained in the catalyst layer 5a constituting the honeycomb catalyst body of the present embodiment include (1) a gasoline engine exhaust gas purification three-way catalyst, (2) an oxidation catalyst for gasoline engine or diesel engine exhaust gas purification, (3) SCR catalyst for selective reduction of NOx, (4) NOx storage catalyst.

  The gasoline engine exhaust gas purification three-way catalyst includes a carrier coat that covers the partition walls of the honeycomb structure (honeycomb carrier) and a noble metal that is dispersed and supported inside the carrier coat. The carrier coat is made of activated alumina, for example. Moreover, as a noble metal disperse-supported in the inside of a carrier coat, Pt, Rh, Pd, or a combination thereof can be cited as a suitable example. Furthermore, the carrier coat contains, for example, a compound such as cerium oxide, zirconia oxide, or silica, or a mixture of these. The total amount of the noble metal is preferably 0.17 to 7.07 g per liter of the honeycomb structure volume.

  An oxidation catalyst for exhaust gas purification of a gasoline engine or a diesel engine contains a noble metal. The noble metal is preferably one or more selected from the group consisting of Pt, Rh, and Pd. The total amount of the noble metal is preferably 0.17 to 7.07 g per liter of the honeycomb structure volume. The SCR catalyst for NOx selective reduction contains at least one selected from the group consisting of metal-substituted zeolite, vanadium, titania, tungsten oxide, silver, and alumina.

  The NOx storage catalyst contains an alkali metal and / or an alkaline earth metal. Examples of the alkali metal include K, Na, and Li. Ca can be mentioned as an alkaline earth metal. The total amount of K, Na, Li, and Ca is preferably 5 g or more per liter of honeycomb structure volume.

  Next, a method for manufacturing the ceramic honeycomb structure of the present invention will be described. In the present invention, the honeycomb structure 1 is obtained by obtaining a honeycomb-shaped formed body by an extrusion method or the like using a clay made of a predetermined raw material, and then drying and firing it. It should be noted that a part of the partition wall intersection 10 as described above corresponds to the octagonal hypotenuse in the cross-sectional shape of the cell 3, the cell pitch is CP, and the partition wall thickness is WT. In order to provide the cell and the partition structure so that the shape formed when intersecting at the partition intersection point side becomes a triangular shape, for example, extrusion may be performed using a die 30 as shown in FIG. . As shown in FIG. 5, the base 30 is formed with a base so as to be able to form a partition intersection 10 that satisfies the hypotenuse of the octagon in the cross-sectional shape of the cell 3 and the two sides having the aforementioned triangular length of intersection. ing. Further, the base is provided with a block portion 51 corresponding to an octagonal cell. The substrate (kneaded material) injected from the substrate inlet slit 50 into the die is discharged from the slit 53 side, so that a honeycomb-shaped formed body can be obtained.

  The honeycomb catalyst body of the present invention can be manufactured by supporting the catalyst on the honeycomb structure 1 according to a manufacturing method according to a conventionally known method. Specifically, first, a catalyst slurry containing a catalyst is prepared. Next, the catalyst slurry is coated on the pore surfaces of the partition walls 2 of the honeycomb structure 1 by a method such as a suction method. Thereafter, the honeycomb catalyst body of the present invention can be manufactured by drying at room temperature or under heating conditions.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

(Experiment 1)
Talc, combined kaolin, calcined kaolin, alumina, aluminum hydroxide, and a plurality from among silica, the chemical _composition, SiO 2 42 to 56 _{wt%, Al} 2 O 3 0 to 45 wt%, and MgO12~ To the cordierite forming raw material prepared at a predetermined ratio so as to be 16% by mass, graphite and synthetic resin were added in an amount necessary to obtain a target porosity. Furthermore, after adding appropriate amounts of methyl celluloses and surfactants, a clay was prepared by adding water and kneading. The prepared clay was vacuum degassed and then extruded to obtain a honeycomb formed body.

  In the extrusion molding, a base 30 in which a block portion 51 corresponding to an octagonal cell and a base inlet slit 50 corresponding to a partition intersection point are formed as shown in FIG. 5 is used. The obtained honeycomb formed body is dried and then fired in a temperature range of a maximum temperature of 1400 to 1430 ° C., thereby having a pore structure of partition walls shown in Tables 1 and 2 and having a diameter of 228.6 mm and a total length of 203.2 mm. Structures (Examples 1 to 12, Comparative Examples 2, 3, 6, 7, 10, 11, 14, and 15) were produced. Further, in order to produce a honeycomb formed body having the intersection R at the partition intersection point, the die 107 shown in FIG. 6 was used in the extrusion. In the base 107, an R-shaped slit 107a is formed in a region corresponding to the partition intersection point as shown in FIG. Then, the injected base (kneaded material) is discharged from the slit 108 side through the R-shaped slit 107. The honeycomb formed body thus obtained was dried and then fired at a maximum temperature of 1400 to 1430 ° C., thereby having the pore structure of the partition walls shown in Tables 1 and 2 and having a diameter of 228.6 mm and a total length. 203.2 mm honeycomb structures (Comparative Examples 1, 4, 5, 8, 9, 12, 13, 16) were produced. In addition, the curvature radius of the intersection R of Comparative Examples 1, 4, 5, 8, 9, 12, 13, and 16 is as shown in Table 2.

  The “intersection triangle length a” in Tables 1 and 2 described above is the intersection triangle length of the cell width (CP−WT) of the intersection triangle length a when the cell pitch is CP and the partition wall thickness is WT. The length (mm) calculated by multiplying the ratio of the length a to the cell width (0.2 to 0.35), and the intersection triangle length a = the ratio of the intersection triangle length a to the cell width × (CP− WT) (Equation 1). Note that a part of the partition wall intersection part corresponds to the hypotenuse of the octagonal cell of the honeycomb structure, and the hypotenuse isosceles is obtained by intersecting the hypotenuse and two sides having the “intersection triangular length a”. A triangle will be formed. The “intersection R” in Tables 1 and 2 described above is as follows. The “intersection point R” is obtained by intentionally adding an R section (arc-shaped curved section) to the intersection section of the partition walls 2 of the honeycomb structure 1. The “intersection R curvature radius” is the length of the radius R of the R portion when the “intersection R” is provided, and is 0.2 mm ≦ radius R ≦ 1.2 mm. The radius R of the R portion at the intersection of the structures was in the range of 0.2 mm to 0.4 mm (see comparative example). In Table 2, “−” in “the value of the ratio of the intersection triangle length a to the cell width” indicates that the intersection R is provided. The same applies to “−” of “intersection triangle length a”. On the other hand, the “intersection R curvature radius” in Tables 1 and 2 is “−” because it does not have the intersection R curvature radius.

(Measurement method of porosity)
The porosity is a value measured with a mercury porosimeter.

(Measurement method of pressure loss)
Exhaust gas was passed through the sample (diameter 228.6 mm × total length 203.2 mm) using an engine (8L / 6 cylinder), the exhaust gas pressure at the front and rear stages of the sample was measured, and the pressure loss was calculated.

(Measurement method of NOx purification rate)
Engine (8L / 6 cylinder) evaluation was performed using the Urea-SCR system. Pass the engine exhaust gas and urea necessary for NOx purification through the sample (diameter 228.6 mm x total length 203.2 mm) on which the SCR catalyst (selective reduction type NOx catalyst) is supported, and measure the amount of NOx before and after the sample. The purification rate was calculated. The main test conditions are as follows. The exhaust gas flow rate was 380 kg / h, the exhaust gas temperature was 250 ° C. (temperature measurement position: 20 mm before the sample gas inlet end surface), and the NOx / NH ₃ equivalent ratio was 1.0.

(Measurement method of isostatic strength)
An isostatic strength test apparatus using a sample (228.6 mm in diameter × 203.2 mm in total length) according to the method for measuring the isostatic fracture strength defined in JASO Standard M505-87, which is an automobile standard issued by the Japan Society for Automotive Engineers. Measured with

  In the evaluation test, Examples 1 to 3 and Comparative Examples 2 to 4 are Comparative Example 1, Examples 4 to 6 and Comparative Examples 6 to 8 are Comparative Example 5, Examples 7 to 9 and Comparative Examples 10 to 12 are In Comparative Example 9, Examples 10 to 12 and Comparative Examples 14 to 16 were based on the results of Comparative Example 13. The amount of catalyst supported on the sample was 200 g / L (indicating the amount of catalyst (200 g) per unit volume (L) of the outer shape of the sample (honeycomb carrier)).

  The criteria for * 2 are as follows. The pressure loss with respect to the standard is −16% or less ◎ (very good), −15 to −6% is ○ (good), −5 to 5% is Δ (equivalent), and 6% or more is × (bad) ). Isostatic strength is 21% or more ◎ (very good), 20% to 11% ◯ (good), -10 to 10% △ (equivalent), -11% or less x (bad) relative to the standard ). The NOx purification rate was evaluated as ◎ (very good) for 16% or more, ◯ (good) for 6-15%, △ (equivalent) for -5-5%, and x (bad) for -6% or less.

  Moreover, the comprehensive criteria are as follows. A case where the pressure loss was ◎, the isostatic strength was △ or ○ or ◎ (equal or better), and the NOx purification rate was Δ, ○ or ◎ (equal or better) was designated as comprehensive judgment （(very good). A case where the pressure loss was ◯, the isostatic strength was △ or ◯ or ◎ (equal or better), and the NOx purification rate was △ or ○ or ◎ (equal or better) was judged as a comprehensive judgment ○ (good). A case where the pressure loss was Δ (equivalent), the isostatic strength was Δ or ○ or ◎ (equivalent or higher), and the NOx purification rate was Δ or ○ or ◎ (equivalent or higher) was defined as a comprehensive judgment Δ (equivalent). The case where the pressure loss was x or the isostatic strength was x was defined as comprehensive judgment x (bad).

(Discussion 1)
As shown in Tables 1 and 2, in Examples 1 to 3, compared with Comparative Example 1, the catalyst layer thickness became uniform, so that comprehensive judgment was improved. Similarly, in Comparative Example 4, since the intersection R was formed, it was confirmed that the catalyst layer thickness was not uniform, and the overall judgment was poor. Moreover, in the comparative examples 2 and 3, it is set as the structure which does not form the intersection R but has an intersection triangle. However, in Comparative Example 2, the intersection triangle length a is 0.37, and in Comparative Example 3, the intersection triangle length a is 0.18. Therefore, the catalyst layer thickness is not uniform and sufficient results are obtained. It was confirmed that it cannot be obtained. Similarly, also about Examples 4-6, Examples 7-9, and Examples 10-12, the result more preferable than the comparative examples 5, 9, and 13 to be compared was able to be obtained.

  Next, Experiment 2 was performed as follows to confirm the effect of reducing the amount of catalyst.

(Experiment 2)
First, a honeycomb formed body similar to the honeycomb formed body of Experiment 1 was prepared. Specifically, the base 30 shown in FIG. 5 in which the slit 50 corresponding to the partition wall intersection is formed. The obtained honeycomb formed body was dried and then fired in a temperature range of a maximum temperature of 1400 to 1430 ° C., thereby having a pore structure of partition walls shown in Table 3 and having a diameter of 228.6 mm and a total length of 203.2 mm. Structures (Reference Examples 1 to 12) were produced. Further, at the time of extrusion molding, a honeycomb formed body having an intersection R at a partition intersection point was obtained using a die 107 shown in FIG. The obtained honeycomb formed body was dried and then fired in a temperature range of a maximum temperature of 1400 to 1430 ° C., thereby having a pore structure of partition walls shown in Table 3 and having a diameter of 228.6 mm and a total length of 203.2 mm. Structures (Reference Comparative Examples 1 to 4) were produced. In addition, the curvature radius of the intersection R of Reference Comparative Examples 1 to 4 is as shown in Table 3.

  Note that “intersection triangle length a” and “intersection R” in Table 3 described above were the same as in Experiment 1. In Table 3, “-” in “the value of the ratio of the intersection triangle length a to the cell width” indicates that the intersection R is provided. The same applies to “−” of “intersection triangle length a”. On the other hand, the case where “intersection R curvature radius” in the table is “−” is because the intersection R curvature radius is not provided.

(Measurement method of porosity)
The porosity is a value measured with a mercury porosimeter.

(Measurement method of pressure loss)
Exhaust gas was passed through the sample (diameter 228.6 mm × total length 203.2 mm) using an engine (8L / 6 cylinder), the exhaust gas pressure at the front and rear stages of the sample was measured, and the pressure loss was calculated.

(Measurement method of NOx purification rate)
Engine (8L / 6 cylinder) evaluation was performed using the Urea-SCR system. Pass the engine exhaust gas and urea necessary for NOx purification through the sample (diameter 228.6 mm x total length 203.2 mm) on which the SCR catalyst (selective reduction type NOx catalyst) is supported, and measure the amount of NOx before and after the sample. The purification rate was calculated. The main test conditions are as follows. The exhaust gas flow rate was 380 kg / h, the exhaust gas temperature was 250 ° C. (temperature measurement position: 20 mm before the sample gas inlet end surface), and the NOx / NH ₃ equivalent ratio was 1.0.

(Measurement method of isostatic strength)
An isostatic strength test apparatus using a sample (228.6 mm in diameter × 203.2 mm in total length) according to the method for measuring the isostatic fracture strength defined in JASO Standard M505-87, which is an automobile standard issued by the Japan Society for Automotive Engineers. Measured with

  In the evaluation test, Reference Examples 1 to 3 are Reference Comparative Example 1, Reference Examples 4 to 6 are Reference Comparative Example 2, Reference Examples 7 to 9 are Reference Comparative Example 3, and Reference Examples 10 to 12 are. Was based on the results of Reference Comparative Example 4. The catalyst amount ratio of * 1 in Table 3 indicates the amount of catalyst per unit volume (L) of the outer shape of the sample (honeycomb carrier), and 200 g / L is 100%.

  The criteria for * 2 are as follows. The pressure loss with respect to the standard is −16% or less ◎ (very good), −15 to −6% is ○ (good), −5 to 5% is Δ (equivalent), and 6% or more is × (bad) ). Isostatic strength is 21% or more ◎ (very good), 20% to 11% ◯ (good), -10 to 10% △ (equivalent), -11% or less x (bad) relative to the standard ). The NOx purification rate was evaluated as ◎ (very good) for 16% or more, ◯ (good) for 6-15%, △ (equivalent) for -5-5%, and x (bad) for -6% or less.

  Moreover, the comprehensive criteria are as follows. A case where the pressure loss was ◎, the isostatic strength was △ or ○ or ◎ (equal or better), and the NOx purification rate was Δ, ○ or ◎ (equal or better) was designated as comprehensive judgment （(very good). A case where the pressure loss was ◯, the isostatic strength was △ or ◯ or ◎ (equal or better), and the NOx purification rate was △ or ○ or ◎ (equal or better) was judged as a comprehensive judgment ○ (good). A case where the pressure loss was Δ (equivalent), the isostatic strength was Δ or ○ or ◎ (equivalent or higher), and the NOx purification rate was Δ or ○ or ◎ (equivalent or higher) was defined as a comprehensive judgment Δ (equivalent). The case where the pressure loss was x or the isostatic strength was x was defined as comprehensive judgment x (bad).

(Discussion 2)
As shown in Table 3, in Reference Examples 1 to 12, the catalyst layer thickness became uniform compared to the reference comparative example, so that the overall judgment was improved. In particular, in an example in which the catalyst amount ratio is equivalent to that of the comparative example, extremely good results were obtained in terms of pressure loss, isostatic strength, and NOx purification rate. Furthermore, even in the example in which the catalyst amount ratio was reduced, extremely good results were obtained as compared with the comparative example serving as a reference. Therefore, it was confirmed that even if the catalyst amount ratio is reduced, an increase in pressure loss can be reduced, most of the catalyst can be effectively utilized, and further, a decrease in strength can be avoided.

  The honeycomb honeycomb structure of the present invention can be used as a honeycomb catalyst body that is excellent in purification efficiency, has a small pressure loss, and can be mounted even in a limited space by supporting a catalyst. Therefore, the honeycomb catalyst body of the present invention is suitably used for purifying components to be purified contained in exhaust gas discharged from, for example, automobile, construction machine, and industrial stationary engines, and combustion equipment.

1: honeycomb structure, 2: partition, 3: cell, 5: catalyst, 5a: catalyst layer, 10: partition intersection, 10a: hypotenuse of octagonal cell (part of partition intersection), 10b: ) Both end portions, 30: base, 50: base inlet slit, 51: block portion, 53: slit, 102: partition walls (of a conventional honeycomb structure), 103: cells (of a conventional honeycomb structure), 105 : Catalyst, 105a: Catalyst layer, 107: Base, 107a: R-shaped slit, 108: Slit, 109: Intersection part (cell and partition wall of conventional honeycomb structure), a: Triangular length of intersection, b: Virtual line , S: virtual line, t: virtual line, T: triangle, CP: cell pitch, WT: partition wall thickness.

Claims (3)

A honeycomb structure having a partition wall made of a porous body, wherein a plurality of cells serving as fluid flow paths are partitioned by the partition wall;
A partition intersection portion is formed in a region where the partition intersects the partition forming the cell,
The cross-sectional shape of the cell is an octagon, and a part of the partition intersection portion corresponds to the hypotenuse of the octagon in the cross-sectional shape of the cell,
The shape formed when the virtual line drawn from both ends of the oblique side intersects on the partition intersection point side is a triangular shape, and the intersection triangle of the virtual line to the point intersected from both ends of the oblique side each of the length, the cell pitch CP, a partition wall thickness upon a WT, the honeycomb structure having a length of 0.2 (CP-WT) mm~0.35 ( CP-WT) mm, automobiles A honeycomb catalyst body carrying an exhaust gas purification catalyst. The honeycomb catalyst body according to claim 1, wherein the intersection triangular length is 0.2 (CP-WT) mm to 0.3 (CP-WT) mm . The honeycomb catalyst body according to claim 1 or 2, comprising at least one selected from the group of cordierite, SiC, mullite, aluminum titanate, and alumina .

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