JP5242341B2 - Honeycomb structure and honeycomb catalyst body - Google Patents

Description

The present invention relates to a honeycomb structure and a catalyst body. More specifically, by supporting the catalyst, carbon monoxide (CO), hydrocarbon (HC) contained in exhaust gas discharged from automobiles, construction machinery, industrial stationary engines, and combustion equipment, etc. A honeycomb structure capable of efficiently purifying harmful substances of nitrogen oxide (NO _x ) and effectively suppressing an increase in pressure loss, and a catalyst supported on the honeycomb structure The present invention relates to a honeycomb catalyst body.

Currently, a honeycomb catalyst body in which a catalyst is supported on a honeycomb structure is used to purify exhaust gas discharged from various engines or the like (see, for example, Patent Document 1). In such a honeycomb catalyst body, fluid (exhaust gas) flows into each cell from the end face on the inflow side, and carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO _X ) contained in the exhaust gas. And other harmful substances are purified with a catalyst.

  Conventionally, a honeycomb structure used for such a honeycomb catalyst body increases the cell density, increases the geometric area on which the catalyst is supported, and improves the exhaust gas purification performance. It was made to increase the contact efficiency.

Japanese Patent Laid-Open No. 07-00766

  However, in the conventional honeycomb structure and honeycomb catalyst body, if the cell density of the honeycomb structure is increased in order to improve the purification performance, the pressure loss when the exhaust gas passes through the cell increases. On the other hand, if it is intended to suppress the increase in pressure loss by thinning the partition walls of the honeycomb structure, the contact efficiency between the exhaust gas and the catalyst is lowered, and the exhaust gas purification performance is lowered.

  Thus, in the conventional honeycomb structure and honeycomb catalyst body, there is a tradeoff between improving the purification performance and reducing the pressure loss, and it is extremely difficult to achieve both. There was a problem.

  The present invention has been made in view of such problems of the prior art, and by carrying a catalyst, it is possible to efficiently purify harmful substances contained in exhaust gas, and pressure loss Is provided, and a honeycomb catalyst body in which a catalyst is supported on the honeycomb structure is provided.

  In order to solve the above-described problems, the present invention provides the following honeycomb structure and honeycomb catalyst body.

[1] A columnar honeycomb structure part having a porous partition wall, in which a plurality of square cells serving as a fluid flow path penetrating from the end surface on the inflow side to the end surface on the outflow side are formed by the partition wall, The partition wall has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm, and the plurality of cells extend from the inflow side end surface to the outflow side end surface in the flow path direction of the cells. A plugging member is provided so as to block a part of the first cell in which the area of the vertical cross section is formed to be a constant size and the opening at the end on the outflow side end face side. Comprising at least a part of the position corresponding to the position where the intersecting portion, which is the portion where the partition walls intersect, of the outflow side end portion of the honeycomb structure portion. Notches formed so that intersections are cut away and removed The length of the cutout portion in the cell flow path direction is L1, the cutout length of one cut-out partition wall in the cross section perpendicular to the cell flow path direction is t1, and the other Formula 1: (L1−L2) × (t1 + t2) / 2 where the notch length of the notched partition wall is t2, and the length of the plugged portion in the cell flow path direction is L2. When the notch size shown is W1 and the total cell area on the outflow side end face of the honeycomb structure portion is P2, the total notch portion W2 having the notch size W1 is the total cell area P2. 25 was 50%, the long honeycomb structure from L1 is L2 of.

[2] The honeycomb according to [1], wherein the notch size W1 is 2 to 50% of the cell area P1 when the area of one cell on the outflow side end face of the honeycomb structure portion is P1. Structure.

[3] The lower limit value of the value obtained by subtracting the length L2 of the plugging portion in the cell flow direction from the length L1 of the cell in the flow channel direction is 1 mm, and the upper limit value is The honeycomb structure according to [1] or [2], which is 30 mm or 1/2 of the total length in the cell extending direction of the honeycomb structure portion, whichever is shorter.

[4] The honeycomb structure according to any one of [1] to [3], wherein the cutout lengths t1 and t2 of the partition walls are 100 to 200% of the partition wall thickness T.

[5] The honeycomb structure according to any one of [1] to [4], and a catalyst supported on the inner surface of the pores of the partition walls of the honeycomb structure and the catalyst supported on the surface of the partition walls. A honeycomb catalyst body having a catalyst loading of 100 to 250 g / L.

  The honeycomb structure and the honeycomb catalyst body of the present invention are a honeycomb structure including a honeycomb structure portion having porous partition walls having a specific porosity and average pore diameter, and a checkered pattern is formed at an end portion on the outflow side of the honeycomb structure portion. The plugged portion is formed in the shape and the notched portion is formed at a position corresponding to the position where the intersection of the partition walls is arranged, so the plugged portion is formed due to the presence of the plugged portion. A part of the fluid that has flowed into the cell is permeated through the partition wall and actively discharged into the cell without the adjacent plugging portion, so that the purification efficiency can be improved. By forming the portion, the cell in which the plugged portion is formed is not completely sealed at the end portion on the outflow side, and the fluid can flow out to the outside through the notch portion. Because the pressure is It is possible to effectively suppress an increase in loss, or to reduce the pressure loss. As described above, according to the honeycomb structure and the honeycomb catalyst body of the present invention, since the plug structure and the cutout portion are provided, it is possible to efficiently purify harmful substances contained in the exhaust gas, and to reduce pressure loss. Can be effectively suppressed, or pressure loss can be reduced.

  That is, the honeycomb structure and the honeycomb catalyst body of the present invention can simultaneously solve the problems that are difficult to achieve with the conventional techniques, such as improving the purification efficiency of exhaust gas and suppressing the increase in pressure loss.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be specifically described. However, the present invention is not limited to the following embodiment, and is within the scope of the gist of the present invention. Based on this knowledge, it should be understood that design changes, improvements, etc. can be made as appropriate.

[1] Honeycomb structure:
As shown in FIGS. 1 to 4, the honeycomb structure 100 of the present embodiment has a porous partition wall 1, and a fluid flow that penetrates from the inflow side end surface 2 to the outflow side end surface 3 by the partition wall 1. A columnar honeycomb structure 5 having a plurality of quadrangular cells 4 to form a path is provided. The partition wall 1 has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm. 4, the plugging portions 6 are alternately formed so as to form a checkered pattern on the outflow side end surface 3 of the honeycomb structure portion 5, and the inflow side end portions of the cells 4 are all opened. The crossing portion 7 is cut out and removed at at least a part of the position corresponding to the position where the crossing portion 7, which is the portion where the partition wall 1 crosses, at the end portion on the outflow side of the structure portion 5. The cutout portion 9 is formed. The plurality of cells include a first cell having a cross-sectional area perpendicular to the flow direction of the cell from the end surface on the inflow side to the end surface on the outflow side, and an end on the end surface side on the outflow side. What is necessary is just to consist of the 2nd cell by which the plugging member was arrange | positioned so that a part of opening part might be plugged in the opening part of a part. In the honeycomb structure 100 of the present embodiment, the length of the notch 9 in the flow direction of the cell 4 is L1, and one notched partition wall 1 in a cross section orthogonal to the flow direction of the cell 4 is provided. Where the notch length of t1 is the notch length of the other notched partition wall 1 and t2 is the notch length of the partition wall 1 and the length of the plugged portion 6 in the flow direction of the cell 4 is L2. When the notch size indicated by (L1−L2) × (t1 + t2) / 2 is W1, and the total cell area on the end surface 3 on the outflow side of the honeycomb structure portion 5 is P2, the notch size W1 The total W2 of the entire cutout portion 9 is 2 to 50% of the total cell area P2, and L1 is longer than L2. The total cell area P2 is the sum of the cross-sectional areas of the cells. The cross-sectional area of the cell is the cross-sectional area of the flow path portion of the cell, and the partition wall portion is excluded. The plurality of cells include a first cell having a cross-sectional area perpendicular to the cell flow path direction from the inflow side end surface to the outflow side end surface, and the outflow side end surface. And a second cell in which a plugging material is disposed so as to close a part of the opening in the opening at the end on the side. Here, FIG. 1 is a perspective view schematically showing one embodiment of the honeycomb structure of the present invention, and FIG. 2 is one of the outflow side end faces of the one embodiment of the honeycomb structure of the present invention. It is a top view which shows a part typically. FIG. 3 is a schematic diagram showing the AA ′ cross section of FIG. 2, and FIG. 4 is a schematic diagram showing the BB ′ cross section of FIG. 2.

The honeycomb structure 100 of the present embodiment can be suitably used as a catalyst carrier of a honeycomb catalyst body for purifying exhaust gas discharged from various engines or the like. More specifically, for example, a honeycomb catalyst body is produced by supporting a catalyst on the inner surface of the pores of the partition walls and the partition surface, and the obtained honeycomb catalyst body is disposed inside the exhaust gas exhaust system, A fluid (exhaust gas) flows into each cell from the end surface on the inflow side, and the inflowed exhaust gas permeates through the partition wall, thereby allowing carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO _X). ) And other harmful substances are purified with a catalyst.

  In the honeycomb structure 100 of the present embodiment, the partition walls 1 have a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm, and the porosity is higher than that of the honeycomb structure used in the conventional honeycomb catalyst body. The partition wall 1 is formed of a porous body that is high and has a large average pore diameter. For this reason, when a catalyst is supported on a honeycomb structure and used as a honeycomb catalyst body, an increase in pressure loss can be effectively suppressed.

  In this specification, “porosity” refers to a value measured by a mercury porosimeter (mercury intrusion method). The “average pore diameter” is measured by a mercury porosimeter (mercury intrusion method), and the cumulative volume of mercury injected into the porous substrate (ie, the partition wall) is the total fineness of the porous substrate. The pore diameter calculated from the pressure when the pore volume is 50%.

  Furthermore, in the honeycomb structure 100 of the present embodiment, the plugging portions 6 are alternately formed so as to form a checkered pattern on the outflow side end surface 3 of the honeycomb structure portion 5 at the outflow side end portions of the plurality of cells 4. And at least a part of the position 8 corresponding to the position where the intersecting portion 7, which is the portion where the partition walls 1 intersect, is disposed at the outflow side end of the honeycomb structure portion 5. In addition, the two partition walls 1 and 1 that intersect are notched and the notch 9 is formed so that the intersecting part 7 is removed, and the notch has the predetermined size. Due to the presence of the sealing portion, a part of the fluid that has flowed into the cell in which the plugging portion is formed is allowed to permeate through the partition wall and actively flow out into the cell without the adjacent plugging portion. The purification efficiency can be improved, and the notch is formed. Therefore, the cell in which the plugged portion is formed is not completely sealed at the end portion on the outflow side, but can flow the fluid to the outside through the notch portion. The increase in loss can be effectively suppressed, or the pressure loss can be reduced.

  The honeycomb structure 100 of the present embodiment has a porous partition wall 1, and a plurality of cells 4 serving as fluid flow paths that penetrate from the end surface 2 on the inflow side to the end surface 3 on the outflow side are partitioned by the partition wall 1. The formed columnar honeycomb structure 5 is provided. Note that the honeycomb structure portion 5 constituting the honeycomb structure 100 of the present embodiment includes an outer peripheral wall 10 disposed so as to surround the outer periphery of the partition wall 1 that defines the cells 4.

  As described above, this partition wall has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm, and the lower limit of the partition wall porosity is preferably 60% or more, and more than 65%. In addition, the upper limit is preferably 80% or less, and more preferably 75% or less. With this configuration, the exhaust gas purification efficiency can be improved satisfactorily, the increase in pressure loss can be effectively suppressed, and further the pressure loss can be reduced.

  In addition, when the porosity of the partition is less than 50%, the porosity of the partition is too low, the pore surface area of the partition is reduced, the effect of improving the purification efficiency, and the effect of suppressing the increase in pressure loss It becomes impossible to achieve both. In particular, the exhaust gas purification efficiency is significantly reduced. On the other hand, when the porosity of the partition walls exceeds 80%, the amount (flow rate) of the exhaust gas that permeates the partition walls increases and the exhaust gas purification efficiency is improved, but the mechanical strength of the honeycomb structure is significantly reduced. , Damage and the like are likely to occur, making it difficult to use as a catalyst carrier.

  Conventionally, in a honeycomb structure used as a catalyst carrier, when the mechanical strength is significantly reduced, a large amount (excess) of a catalyst containing a noble metal is supported to increase the mechanical strength of the honeycomb catalyst body. In some cases, the precious metals contained in the catalyst described above are relatively expensive, and there is a problem that the manufacturing cost of the honeycomb catalyst body increases with an increase in the amount of the catalyst used. The honeycomb structure of the present embodiment has a mechanical strength that can withstand use as a catalyst carrier in a necessary and sufficient amount of catalyst supported.

  Moreover, the average pore diameter of the partition walls of the honeycomb structure part constituting the honeycomb structure is 13 to 60 μm, preferably 15 to 50 μm, and more preferably 18 to 40 μm. With this configuration, the exhaust gas purification efficiency can be improved satisfactorily, the increase in pressure loss can be effectively suppressed, and further the pressure loss can be reduced.

  When the average pore diameter of the partition walls is less than 13 μm, when the catalyst is supported on the inner surface of the partition wall pores and used as a honeycomb catalyst body, the pores are blocked, and the exhaust gas from the inner surface of the pores is blocked. Purification is not performed, and purification efficiency is significantly reduced. On the other hand, if the average pore diameter of the partition walls exceeds 70 μm, the total inner surface area of the partition wall pores decreases, and the exhaust gas purification efficiency decreases.

Cell density of the honeycomb structure of the present embodiment is preferably from 16 to 93 cells ^/ cm 2 ^{(100~600cpsi),} more preferably from 42-62 cells ^/ cm 2 ^{(300~400psi).} When the cell density is less than 16 cells / cm ² , the contact efficiency with the exhaust gas is lowered, and the purification efficiency may be lowered. When the cell density is more than 93 cells / cm ² , the pressure loss is increased. Sometimes. “Cpsi” is an abbreviation for “cells per square inch”, and is a unit representing the number of cells per square inch.

  Moreover, it is preferable that the thickness of a partition is 80-450 micrometers, and it is still more preferable that it is 230-330 micrometers. If the partition wall thickness is less than 80 μm, the strength may be insufficient and thermal shock resistance may decrease, and if it exceeds 450 μm, pressure loss may increase. The cell shape is not particularly limited as long as the present invention can be realized, and may be arbitrarily selected from a triangle, a quadrangle, a hexagon, an octagon-rectangle combination, and the like, but a quadrangle is preferable.

  The shape of the cross section perpendicular to the central axis of the honeycomb structure of the present embodiment, that is, the shape of the outer peripheral wall arranged so as to surround the partition wall is not particularly limited, but for example, a circle, an ellipse, an ellipse, a trapezoid , Triangles, squares, hexagons, other polygons, or left-right asymmetrical shapes. Of these, a circle, an ellipse, and an ellipse are preferable.

  As a material constituting the partition walls of the honeycomb structure of the present embodiment, a material mainly composed of ceramics can be given as a suitable example. Preferred examples of ceramics include silicon carbide, cordierite, aluminum titanate, sialon, mullite, silicon nitride, zirconium phosphate, zirconia, titania, alumina, silica, or a combination thereof. In particular, ceramics such as silicon carbide, cordierite, mullite, silicon nitride, and alumina are preferable from the viewpoint of alkali resistance. Among these, oxide-based ceramics are preferable because of their low cost.

  Note that the outer peripheral wall disposed so as to surround the partition walls may be a molded integrated wall that is formed integrally with the honeycomb structure portion at the time of forming the honeycomb structure portion, or a honeycomb structure portion having a wall on the outer periphery thereof. Alternatively, the outer peripheral wall of the honeycomb structure portion may be ground into a predetermined shape and the outer peripheral wall may be formed of cement or the like. Such an outer peripheral wall can be formed using the material similar to the material which comprises the partition mentioned above, for example.

  Further, the honeycomb structure of the present embodiment may be used alone or, for example, a plurality of square pillar-shaped honeycomb structures may be bonded to each other by pasting the side surfaces thereof to form a bonded type honeycomb structure. May be used as

  In the honeycomb structure of the present embodiment, a plurality of cells penetrating from the end surface on the inflow side to the end surface on the outflow side are partitioned by the porous partition walls. This cell serves as a flow path for fluid, that is, exhaust gas, and a part of the exhaust gas flowing in from the end surface on the inflow side passes through the partition wall that partitions the cell and flows out into the adjacent cell. In addition, harmful substances are purified by the inner surface of the pores of the partition walls and the catalyst supported on the partition surface, and the resulting purified gas can be discharged from the end face on the outflow side.

  As shown in FIGS. 1 to 4, the honeycomb structure of the present embodiment is alternately formed so as to form a checkered pattern on the outflow side end surface 3 of the honeycomb structure unit 5 at the outflow side end portions of the plurality of cells 4. The plugging portion 6 is formed, and all the inflow side end portions of the cells 4 are opened.

  The plugged portion is preferably made of a porous body having a porosity of 20 to 80%. By comprising in this way, since waste gas can permeate | transmit a plugging part, waste gas can be purified also by a plugging part. If the porosity is less than 20%, the exhaust gas does not flow to the first cell, and only about half of the cells are used for purification, and the harmful component emission amount may be greatly increased. If the amount exceeds 80%, the amount (flow rate) of the exhaust gas that permeates the partition wall increases, and the purification performance of the exhaust gas is improved. However, the mechanical strength of the honeycomb structure is reduced, so that damage or the like may easily occur. , It may be difficult to use as a catalyst support.

  The plugging portion has a length from an end surface (outflow side end surface) in the outflow side opening to an opposite end surface in the cell flow path direction, that is, the disposition depth of the plugging portion is 0.3. It is preferable that it is 10-10 mm, and it is still more preferable that it is 0.5-5 mm. For example, when the arrangement depth is less than 0.3 mm, the mechanical strength of the plugged portion is reduced, and the bonding force between the plugged portion and the partition wall cannot be sufficiently obtained, and the exhaust gas The plugging portion may be easily damaged by pressure or vibration from the outside. On the other hand, if it exceeds 10 mm, the effective area of the partition wall through which the exhaust gas permeates decreases, and sufficient purification efficiency may not be obtained.

  As the material constituting the plugged portion, those mentioned as the material for the partition walls constituting the honeycomb structure portion can be preferably used, and the material is preferably the same as the material for the partition walls.

As shown in FIGS. 1 to 4, the honeycomb structure 100 of the present embodiment corresponds to the position where the intersecting portion 7, which is the portion where the partition walls 1 intersect, at the outflow side end of the honeycomb structure 5. At least a part of the position 8 is provided with a notch 9 formed so that the two intersecting partition walls 1 and 1 are notched and the intersection is removed. In the honeycomb structure 100 of the present embodiment, the length of the notch 9 in the flow direction of the cell 4 is L1, and one notched partition wall 1 in a cross section orthogonal to the flow direction of the cell 4 is provided. Where the notch length of t1 is the notch length of the other notched partition wall 1 and t2 is the notch length of the partition wall 1 and the length of the plugged portion 6 in the flow direction of the cell 4 is L2. When the notch size indicated by (L1−L2) × (t1 + t2) / 2 is W1, and the total cell area on the end surface 3 on the outflow side of the honeycomb structure portion 5 is P2, the notch size W1 The total W2 of the entire cutout portion 9 is 2 to 50% of the total cell area P2, and L1 is longer than L2. Here, the total cell area P2 is the total area of all cells on the outflow side end face of the honeycomb structure. Therefore, the sum of the areas of the cells having the plugged portions on the outflow side end face of the honeycomb structure portion and the sum of the areas of the cells having no plugged portions on the outflow side end surface of the honeycomb structure portion. Is the sum of the values. The total cell area P2 varies depending on the size of the honeycomb structure, but is preferably about 10 to 50000 mm ² .

  In the honeycomb structure 100 of the present embodiment, the fluid such as exhaust gas that has flowed from the opening on the inflow side of the cell in which the plugging portion is formed at the outflow side end is plugged near the outflow side end. Since the portion is in a slightly pressurized state, it passes through the partition wall and flows into the adjacent cell, and flows out from the opening on the outflow side of the adjacent cell. At this time, since the notch portion is formed at the outflow side end portion of the honeycomb structure portion, as shown in FIGS. 3 and 4, a part of the fluid flowing into the cell in which the plugging portion is formed is Thus, it is possible to prevent the pressure in the cell in which the plugged portion is formed from flowing out through the notch and the plugged portion is excessively increased. Thus, according to the honeycomb structure of the present embodiment, the fluid flowing through the cells having the plugged portions permeates the partition walls and effectively contacts the catalyst in the partition walls due to the presence of the plugged portions. In addition, since a part of the fluid flowing through the cell having the plugging portion through the notch flows out to the outside, it is possible to suppress an increase in pressure loss, and therefore, harmful substances contained in the fluid such as exhaust gas. Can be efficiently purified, and an increase in pressure loss can be effectively suppressed, or pressure loss can be reduced. Here, in FIG. 3 and FIG. 4, an arrow F indicates the flow of fluid in which the fluid that has flowed into the cell in which the plugging portion is formed flows out to the outside through the cutout portion.

  In the honeycomb structure of the present embodiment, the total W2 of the entire cutout portion 9 having the cutout size W1 is 2 to 50% of the total cell area P2, and preferably 25 to 100%. More preferably, it is 30 to 90%. If it is less than 2%, the size of the notch is small and pressure loss increases, which is not preferable. If it is greater than 50%, the amount of exhaust gas that flows out through the notch increases and purification efficiency decreases. Therefore, it is not preferable.

  The notch is in a state where two intersecting partition walls are scraped (notched) at a position including the intersecting portion at the end of the honeycomb structure on the outflow side. The notch 9 has an effect even if it is provided at some of the intersections, but as shown in FIGS. 2 and 3, all the parts corresponding to the intersections are not cut out. Is preferred. And in the cross section orthogonal to the cell flow path direction, the length of the notched portion of one of the two cut out partition walls (the partition extends in the cross section perpendicular to the cell flow direction) (Length in the direction) is t1, and the length of the notched portion of the other partition wall of the two notched partition walls is t2. In the case where the partition walls are cut diagonally (in the cross section perpendicular to the cell flow path direction, they are oblique to the extending direction of the partition walls), the average length is t2. The cutout length t1 and the cutout length t2 may be the same length or different lengths. The notch length t1 and the notch length t2 are preferably 130 to 170% of the partition wall thickness T. If it is less than 130%, the pressure loss may be difficult to reduce, and if it is more than 200%, the purification efficiency of exhaust gas may be reduced. Further, the notch is connected to (communication with) at least one of the two “cells having a plugging portion” adjacent to the notch, and the exhaust gas is connected to the notch. It is formed so that it can flow out from the “cell having a stopper” to the notch. And as shown in FIG. 2, it is preferable that the notch part is connected with both of two "cells which have a plugging part" adjacent to the notch part.

  Moreover, the lower limit of the value (L1-L2) obtained by subtracting the flow path direction length L2 of the plugging portion from the length L1 of the cutout portion in the cell flow direction is 1 mm, and the upper limit value. Is preferably 30 mm or 1/2 of the total length in the cell extending direction of the honeycomb structure portion, whichever is shorter, the lower limit value is 2.0 mm, and the upper limit value is 15 mm or the cells of the honeycomb structure portion It is more preferable that the length is 1/4 of the total length in the extending direction. If L1-L2 is shorter than 1.0 mm, the pressure loss may be difficult to reduce. If L1-L2 is longer than 30 mm or ½ of the total length in the cell extending direction of the honeycomb structure portion, whichever is shorter, exhaust gas purification efficiency may be reduced.

  In the honeycomb structure of the present embodiment, the notch size W1 is 2 to 50% of the cell area P1 when the area of one cell on the outflow side end face of the honeycomb structure portion is P1. Is preferable, and it is still more preferable that it is 10 to 30%. If it is less than 2%, the size of the notch may be small and the pressure loss may increase. If it is greater than 50%, more exhaust gas will flow out through the notch and the purification efficiency will decrease. There are things to do.

  The number of notches is preferably 30% or more, more preferably 80% or more of the total number of intersections when no notches are formed on the end face on the outflow side of the honeycomb structure. Further preferred is 100%. If it is less than 50%, there are few notches and pressure loss may increase.

[2] Manufacturing method of honeycomb structure:
Next, a method for manufacturing the honeycomb structure of the present embodiment will be specifically described.

  The method for manufacturing a honeycomb structured body of the present embodiment includes a step (1) of obtaining a columnar honeycomb formed body having partition walls that form a plurality of cells serving as fluid flow paths by forming a ceramic forming raw material. Plugged slurry is formed by filling plugging slurry into an opening of a predetermined cell on one end face (end face on the outflow side) of the formed honeycomb molded body, and plugging the opening of the predetermined cell. A step (2) for obtaining a body, and the periphery of the crossing portion including the crossing portion at the outflow side end portion of the plugged honeycomb formed body is cut out (cut off) with a predetermined size to form a cutout portion. A method for manufacturing a honeycomb structure, comprising: a step (3) of obtaining a notched portion formed honeycomb formed body; and a step (4) of obtaining the honeycomb structure by firing the notched portion formed honeycomb formed body. is there.

  Hereinafter, the manufacturing method of the honeycomb structure of the present embodiment will be described in more detail for each step.

[2-1] Step (1):
Step (1) is a step of forming a columnar honeycomb formed body having partition walls that form a plurality of cells that serve as fluid flow paths by forming a ceramic forming raw material containing a ceramic raw material. This step (1) can be performed according to a conventionally known method for manufacturing a honeycomb structure.

[2-2] Step (2):
In the step (2), the plugging slurry is filled in the opening portion of the predetermined cell on the one end surface (end surface on the outflow side) side of the obtained honeycomb formed body, as shown in FIG. This is a step of obtaining a plugged honeycomb formed body in which plugged portions are formed in the portions.

  In the method for manufacturing a honeycomb structured body of the present embodiment, the end portion on the outflow side of the remaining cells that do not form plugged portions is covered with a mask, and only predetermined cells are filled with the plugging slurry.

  The method of disposing the mask in the remaining cells is not particularly limited. For example, an adhesive film is attached to the entire one end face (outflow end face) of the honeycomb formed body, and the adhesive film And a method of making a hole at a position corresponding to the opening of the “predetermined cell without mask”. More specifically, after sticking the adhesive film to the entire one end face of the honeycomb molded body, only the portion of the adhesive film corresponding to the cell (predetermined cell) where the plugging portion is to be formed. A method of drilling holes with a laser can be suitably used. As an adhesive film, what applied the adhesive to one surface of the film which consists of resin, such as polyester, polyethylene, a thermosetting resin, etc. can be used conveniently.

  Further, in the step (1), the partition walls in the cross section perpendicular to the central axis direction (cell flow path direction) are formed in a lattice shape, and the cross section perpendicular to the cell flow path direction is square. A molded body is formed. Then, the adhesive film is perforated so that the predetermined cells and the remaining cells are alternately arranged across the partition walls, that is, the predetermined cells and the remaining cells are arranged in a staggered manner.

  Examples of the plugging slurry for forming the plugging portion include a slurry in which the above ceramic raw material and additive are blended. It is preferable to adjust the viscosity to 200 to 400 dPa · s by mixing water, a binder, a pore former, a surfactant or the like as an additive.

  In addition, after forming the plugged portions with the plugging slurry in this way, the obtained plugged honeycomb formed body may be further dried.

[2-3] Step (3):
In step (3), the periphery of the crossing portion including the crossing portion at the outflow side end of the plugged honeycomb formed body is cut out (cut off) with a predetermined size to form a cutout portion. This is a step of obtaining a formed honeycomb formed body. Regarding the structure of the notch (the length L1 of the cell in the flow direction of the cell, the notch length t1, t2, etc.), the number of formations, etc., the structure and the formation of the notch described in the honeycomb structure of the present embodiment. It is preferable that the number be equal.

  The notch may be formed by using a router so that the partition wall is notched from the end face on the outflow side of the plugged honeycomb molded body, or a sword mountain shape in which a plurality of needle-like members are held on the substrate. A jig may be used to pierce the intersection of the partition walls, or the intersection of the partition walls may be removed (notched) by applying high-pressure water to the intersection of the partition walls. It may be formed.

  In addition, you may perform the formation of the notch part of a process (3) after performing the baking of a process (4).

[2-4] Step (4):
Step (4) is a step of firing the notched portion formed honeycomb formed body to obtain a honeycomb structure. In this way, the honeycomb structure of the present embodiment can be manufactured easily and at low cost. This step (4) can be performed according to a conventionally known method for manufacturing a honeycomb structure.

[3] Honeycomb catalyst body:
Next, an embodiment of the honeycomb catalyst body of the present invention will be specifically described. The honeycomb catalyst body of the present embodiment is supported on the inner surface of the pores of the honeycomb structure of the present invention described above (the honeycomb structure 100 shown in FIGS. 1 to 4) and the partition walls of the honeycomb structure. And a catalyst supported on the partition wall surface.

Such a honeycomb catalyst body allows exhaust gas discharged from automobile, construction machine, and industrial stationary engines, combustion equipment, and the like to flow into each cell from the end face on the inflow side, The partition wall is used to purify harmful substances such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO _x ), etc. with a catalyst. The permeated fluid (purified gas) that has permeated through the partition wall in this manner flows out from the opening on the end surface on the outflow side of the adjacent cell.

  Since the honeycomb catalyst body of the present embodiment has the catalyst supported on the honeycomb structure of the present invention, the honeycomb catalyst body has a plugging portion and a notch portion, so that harmful substances contained in the exhaust gas are efficiently removed. In addition, the pressure loss can be effectively suppressed, or the pressure loss can be reduced.

  In addition, since the honeycomb catalyst body of the present embodiment has a partition wall porosity and average pore diameter in a specific range, even if the purification efficiency of exhaust gas is improved, the increase in pressure loss is effectively suppressed, or the pressure Loss can be reduced.

  That is, the honeycomb catalyst body of the present embodiment can simultaneously solve the problems that are difficult to achieve with the conventional techniques, such as improving the purification efficiency of exhaust gas and suppressing the increase in pressure loss.

The catalyst used in the honeycomb catalyst body of the present embodiment is not particularly limited as long as it can purify harmful substances contained in the exhaust gas. For example, platinum (Pt) and rhodium (Rh) are used as noble metals. And further containing activated alumina and ceria as an oxygen storage agent are preferred. Such a catalyst is particularly effective for purification of harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO _x ).

  The amount of catalyst supported varies depending on the type of catalyst, the size and cell structure of the honeycomb structure used as the catalyst carrier, and the type and amount of exhaust gas to be purified. For example, per 1 L of the honeycomb structure volume Further, it is preferable that 100 to 250 g of catalyst is supported. By comprising in this way, the purification | cleaning efficiency of exhaust gas can be improved and the increase in pressure loss can be suppressed effectively. The catalyst loading is more preferably 150 to 200 g, and particularly preferably 160 to 180 g, per liter of the honeycomb structure volume.

  The amount of the catalyst supported on the inner surface of the pores of the partition walls is preferably equal to or greater than the amount of the catalyst supported on the partition surface. If the catalyst supported on the inner surface of the pores of the partition walls is not equal to or greater than the amount of the catalyst supported on the partition surface, the surface area in the pores cannot be used effectively and the purification rate may deteriorate.

[3-1] Manufacturing method of honeycomb catalyst body:
Next, an example of a method for manufacturing the honeycomb catalyst body of the present embodiment will be described. Note that the method for manufacturing the honeycomb catalyst body of the present embodiment is not limited to the following method.

  First, a honeycomb structure constituting the catalyst carrier of the honeycomb catalyst body of the present embodiment is manufactured. In the honeycomb catalyst body of the present embodiment, since the honeycomb structure of the present invention described so far is used, the honeycomb structure according to one embodiment of the manufacturing method of the honeycomb structure of the present embodiment described above. Can be manufactured.

  Next, the catalyst is supported on the partition wall surfaces of the obtained honeycomb structure and the inner surfaces of the pores of the partition walls. The catalyst loading method is not particularly limited, and the catalyst can be loaded according to a method used in a conventionally known honeycomb catalyst body manufacturing method. For example, after the honeycomb structure is wash-coated with a catalyst solution containing a catalyst component, it can be heat treated at a high temperature and baked.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. Each physical property was measured by the following method.

[Average pore diameter (μm)]: The pore diameter was measured by a mercury porosimeter (mercury intrusion method), and the cumulative volume of mercury injected into the porous substrate was the total pore volume of the porous substrate. It means the pore diameter calculated from the pressure when it becomes 50%. As the mercury porosimeter, the product name: Auto Pore III Model 9405 manufactured by Micromeritics was used.

[Porosity (%)]: Similar to the pore diameter, a mercury porosimeter was used.

[Catalyst loading (g / L)]: The catalyst loading (g / L) per liter of the volume of the honeycomb structure as the catalyst carrier was calculated.

[Platinum group metal loading (g / L)]: The platinum group metal loading (g / L) contained in the catalyst per 1 L volume of the honeycomb structure as the catalyst carrier was calculated. The platinum group metal is configured such that the ratio of platinum (Pt) to rhodium (Rh) (Pt: Rh) is 5: 1.

[Opening ratio of cutout portion]: The length L1 of the cutout portion in the cell flow path direction is measured using a caliper, and the cutout lengths t1 and t2 in the cross section perpendicular to the cell flow passage direction are optically measured. Measure with a microscope. Further, the length L2 of the plugged portion in the cell flow path direction is measured using a caliper. Further, the total cell area P2 on the outflow side end face of the honeycomb structure part is measured by an image processing method. Then, the notch size W1 ((L1-L2) × (t1 + t2) / 2) is calculated. The notch size W1 is summed up for all the notch portions to calculate the total notch portion W2 of the notch size W1. Then, the aperture ratio (100 × W2 / P2) of the notch is calculated.

[Pressure loss (kPa)]: A gas for measurement (air) at 25 ° C. and 1 atm was passed through the honeycomb catalyst body at a constant flow rate, and the pressures at the end face on the inflow side and the end face on the outflow side were measured. The pressure difference was defined as pressure loss (kPa). Measurements of the pressure, the flow rate of the measurement gas, up to 0.92 nm ³ / min 9.91Nm ³ / min, to increase the flow rate by about 1 Nm ³ / min, was measured a total of 10 times.

[Hazardous component emission (g / mile)]: The measurement of the harmful component emission was performed by disposing the honeycomb catalyst body of each example or comparative example in the exhaust system of a gasoline engine vehicle having a displacement of 2 liters. The engine vehicle was operated in the FTP (US federal regulation, LA-4) operation mode, and the emission amount (g) of harmful components contained in the exhaust gas discharged per mile of the mileage was measured. As harmful components, the amount (g) of hydrocarbon (HC) and nitrogen oxide (NO _x ) in the exhaust gas was measured (HC emissions, NO _x emissions). In addition, the amount of harmful component discharge was measured when the platinum group metal loading was 1 g / L and when the platinum group metal loading was 2 g / L.

( Reference Example 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~ 10-20 parts by mass of graphite was added as a pore former to 100 parts by mass of the cordierite forming raw material prepared at a predetermined ratio so as to be 16% by mass. Further, after adding appropriate amounts of methylcellulose and surfactant, the prepared clay was vacuum degassed and then extrusion molded to obtain a cylindrical honeycomb formed body. The honeycomb molded body has a partition wall thickness of 200 μm (8 mil) and a cell density of 62 cells / cm ² (400 cpsi). Note that “1 (mil)” is 1/1000 inch, and “cpsi” is “cell / square inch”.

  Next, the end face on the outflow side has a checkered pattern (that is, a staggered pattern) at the opening of a predetermined cell on one end face side corresponding to the end face on the outflow side of the obtained honeycomb formed body. A plugged portion was formed to obtain a plugged honeycomb formed body. As the plugging slurry for forming the plugging portion, a slurry in which the cordierite forming raw material and an additive were blended was used. The length L2 of the plugged portion in the cell flow path direction was set to 2 mm. As the plugging slurry for forming the plugged portion, a cordierite forming raw material and a binder prepared at the same ratio as the cordierite forming raw material used for the above-mentioned honeycomb molded body kneaded material are blended, What adjusted the viscosity to 180-350 dPa * s with the thickener was used.

Next, the intersection of the partition walls at the end portion (end portion on the outflow side) where the plugged portion of the obtained plugged honeycomb formed body was formed was provided with projections 11 as shown in FIG. Using the jig 12, notches having the following sizes were formed to form notch portions, and a notched portion-formed honeycomb formed body was obtained. The jig 12 has a plurality of needle-like members 11 disposed on a substrate 13 and cuts out the partition walls 1 (intersections) of the honeycomb structure 100 at the tips of the needle-like members 11. FIG. 5 is a schematic view showing a step of forming a notch in the step of manufacturing the honeycomb structure of the present invention. The notches were formed in the portions corresponding to all the intersecting portions of the end portion on the outflow side of the honeycomb formed body. As the size of the notch, the length L1 in the cell flow path direction is 10 mm, the notch lengths t1 and t2 in the cross section perpendicular to the cell flow path direction are both 1 mm, and the outflow of the honeycomb molded body The total cell area P2 on the side end face was set to 50000 mm ² .

Next, the obtained notch-formed honeycomb formed body was fired to manufacture a honeycomb structure. Table 1 shows the partition wall thickness (μm), cell density (cell / cm ² ), average pore diameter (μm), and porosity (%) of the honeycomb structure.

Next, a catalyst containing a platinum group metal prepared so that the ratio (Pt: Rh) of platinum (Pt) and rhodium (Rh) is 5: 1 is added to the obtained honeycomb structure. A honeycomb catalyst body was manufactured by supporting the catalyst so that the amount was 160 g / L ( Reference Example 1). As the promoter of the supported catalyst, cerium (Ce) oxide (CeO ₂ ) and zirconium (Zr) oxide (ZrO ₂ ) were used. The platinum group metal loading is 2 g / L. Table 1 shows the catalyst loading (WC amount) and the platinum group metal loading.

With respect to the honeycomb catalyst body of Reference Example 1, the opening ratio of the notch portion was measured, and the pressure loss and the harmful component discharge amount were measured. The measurement result of the opening ratio of the notch is shown in Table 1, the measurement result of the pressure loss is shown in Table 2, and the measurement result of the harmful component discharge amount is shown in Table 3.

(Examples 2 to 5 )
A honeycomb structure having the same configuration as in Reference Example 1 was manufactured except that the average pore diameter, the porosity, and the opening ratio of the notch portions were changed as shown in Table 1, and the resulting honeycomb structure was obtained. A catalyst was supported by the same method as in Reference Example 1 to produce honeycomb catalyst bodies (Examples 2 to 5 ). About each honeycomb catalyst body of Examples 2-5, the measurement of the pressure loss and the measurement of the harmful component discharge | emission amount were performed. The results are shown in Tables 2 and 3.

(Comparative Example 1)
The honeycomb structure has partition wall thickness (μm), cell density (cell / cm ² ), average pore diameter (μm), and porosity (%) as shown in Table 1, and has a notch. As shown in Table 1, a catalyst was supported on the obtained honeycomb structure so that the amount of catalyst supported was 200 g / L, and a honeycomb catalyst body was manufactured (Comparative Example 1). . The platinum group metal loading was 2.5 g / L. The honeycomb catalyst body of Comparative Example 1 was measured for harmful component discharge. The results are shown in Table 3 .

From Tables 1 and 3, the honeycomb catalyst bodies of Reference Example 1 and Examples 2 to 5 in which the cutout portions were formed had a HC emission amount of NO as compared with the honeycomb catalyst body of Comparative Example 1 in which the cutout portions were not formed. It turns out that the amount of _X emission is also small. Further, from Tables 1 to 3, it can be seen that a good pressure loss, HC discharge amount and NO _X discharge amount are shown when the opening ratio of the notch is 5 to 50%. Also, from Tables 1 and 2, it can be seen that the pressure loss is reduced as the opening ratio of the notch is increased ( Reference Example 1, Examples 2 to 3). Further, Tables 1 to 3 show that an excellent pressure loss, HC discharge amount and NO _X discharge amount are shown at an average pore diameter of 15 to 70 μm.

The honeycomb structure according to the present invention supports carbon monoxide (CO) and hydrocarbons contained in exhaust gas discharged from automobiles, construction machines, industrial stationary engines, combustion equipment, and the like by supporting a catalyst. (HC) and nitrogen oxides (NO _x ) can be efficiently purified, and an increase in pressure loss can be effectively suppressed, which can be suitably used as a catalyst carrier of a honeycomb catalyst body. it can.

Moreover, the honeycomb catalyst body of the present example is a carbon monoxide (CO), hydrocarbon (HC) contained in exhaust gas discharged from automobiles, construction machinery, industrial stationary engines, combustion equipment, and the like. It can be suitably used to purify harmful components such as nitrogen oxides (NO _x ).

1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. [Fig. 3] Fig. 3 is a plan view schematically showing a part of the outflow side end surface of one embodiment of the honeycomb structure of the present invention. It is a schematic diagram which shows the A-A 'cross section of FIG. It is a schematic diagram which shows the B-B 'cross section of FIG. It is a schematic diagram which shows the process of forming a notch part in the process of manufacturing the honeycomb structure of this invention.

Explanation of symbols

1: partition wall, 2: end face on the inflow side, 3: end face on the outflow side, 4: cell, 5: honeycomb structure part, 6: plugging part, 7: intersection part, 8: position where the intersection part is arranged Corresponding position, 9: notch, 10: outer peripheral wall, 11: acicular member, 12: jig, 100: honeycomb structure, F: arrow.

Claims (5)

A columnar honeycomb structure part having a porous partition wall and penetrating from the end surface on the inflow side to the end surface on the outflow side by the partition wall, in which a plurality of rectangular cells serving as fluid flow paths are partitioned;
The partition wall has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm,
The plurality of cells include a first cell having a cross-sectional area perpendicular to the cell flow path direction from the inflow side end surface to the outflow side end surface, and the outflow side end surface. A second cell in which a plugging member is disposed so as to close a part of the opening in the opening at the end on the side;
Formed so that the crossing portion is cut out and removed at at least a part of the position corresponding to the position where the crossing portion, which is the portion where the partition walls cross, of the outflow side end portion of the honeycomb structure portion. Having a cut-out portion,
The length of the cutout portion in the cell flow path direction is L1, the cutout length of one cutout partition in the cross section orthogonal to the cell flowpath direction is t1, and the other cutout partition wall. The notch length represented by Formula 1: (L1−L2) × (t1 + t2) / 2, where t2 is the length of the notch and L2 is the length of the plugging portion in the flow path direction of the cell. Let W1 be
When the total cell area on the outflow side end face of the honeycomb structure portion is P2,
A honeycomb structure in which the total notch portion W2 of the notch size W1 is 25 to 50% of the total cell area P2 and L1 is longer than L2.   The honeycomb structure according to claim 1, wherein the notch size W1 is 2 to 50% of the cell area P1 when the area of one cell on the outflow side end face of the honeycomb structure portion is P1.   The lower limit of the value obtained by subtracting the length L2 of the plugging portion in the cell flow direction from the length L1 of the cell in the flow path of the cell is 1 mm, and the upper limit is 30 mm. The honeycomb structure according to claim 1 or 2, which has a shorter length which is one half of the total length in the cell extending direction of the structure portion.   The honeycomb structure according to any one of claims 1 to 3, wherein the partition wall cutout lengths t1 and t2 are 100 to 200% of the partition wall thickness T. A honeycomb structure according to any one of claims 1 to 4, and a catalyst supported on the inner surface of the pores of the partition walls of the honeycomb structure and supported on the partition wall surfaces,
A honeycomb catalyst body having a catalyst loading of 100 to 250 g / L.

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