JP2018030101A - Method for producing exhaust gas purifying catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an exhaust gas purifying catalyst capable of preventing catalyst slurry from leaching to a skin portion at the time of washcoating for supporting a catalyst on a honeycomb carrier.SOLUTION: A method for producing an exhaust gas purifying catalyst includes: a first step of abutting an elastic gripping jig on the outer periphery of a honeycomb carrier to grip the honeycomb carrier by an elastic body; a second step of immersing the lower end of the honeycomb carrier in a slurry liquid bath containing a catalyst component and then sucking up the slurry liquid; and a fourth step of air blowing the honeycomb carrier from above to coat the catalyst component in a cell. A position for gripping the honeycomb carrier by the elastic gripping jig is set such that the exposed length on the upper end side of a honeycomb in the space is a length equal to or less than one third of the whole length of the honeycomb from the upper end of the elastic body, whereby leaching of the catalyst slurry from the honeycomb skin is suppressed in the next slurry liquid sucking step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an exhaust gas purification catalyst, and more particularly, to a method for manufacturing an exhaust gas purification catalyst that can suppress leaching of catalyst slurry to an outer skin portion during a wash coat in which the catalyst is supported on a honeycomb carrier.

  Exhaust gas from automobiles contains various harmful components such as nitrogen oxides (NOx), unburned hydrocarbons derived from fuel (HC), and carbon monoxide (CO). Has been proposed and implemented.

  In addition to automobiles using gasoline as fuel, there are diesel cars equipped with diesel engines that use light oil as fuel. Regarding exhaust gas discharged from diesel vehicles, in addition to the above NOx, HC, and CO, PM (Particulate Matter) as a particulate component is also known, and DPF (Diesel) is used as a device for purifying such PM. Particulate Filter) has been widely used.

DPF is a general term for an exhaust gas purification filter device also called a wall flow honeycomb filter, but its structure is composed of a plurality of cells partitioned by partition walls from the inlet end portion toward the outlet end portion. The honeycomb structure is alternately plugged at the outlet end. The partition which comprises a cell has air permeability, PM is removed by filtering PM out of waste gas using this air permeability.
If the PM filtered out from the exhaust gas by the DPF is left as it is, it will continue to accumulate in the DPF and cause clogging. Therefore, the PM is generated by the heat of the exhaust gas or the injection of fuel into the combustion chamber or exhaust gas of the engine. To regenerate the DPF on which PM is deposited. For the purpose of promoting such regeneration, a catalyst component may be coated on the partition walls of the DPF cell, and the DPF coated with the catalyst component may be referred to as a CSF (Catalyzed Soot Filter). The present applicant has also proposed a system incorporating these catalysts (see, for example, Patent Document 1).

  Conventionally, most of diesel engines have been required to purify PM in exhaust gas, but it is due to the use of light oil that is difficult to burn compared to gasoline, which is easy to burn like gasoline, Until now, automobiles that use fuel that generates a small amount of PM have not received much attention as an environmental problem.

  However, with increasing interest in environmental problems, regulations on harmful components in exhaust gas have become more stringent, and there is a movement to regulate the amount of PM emitted from gasoline automobiles. In recent years, in particular, the market is also concerned about fuel consumption, and direct-injection engines that supply gasoline directly into the combustion chamber under precise control are becoming mainstream in gasoline engines. However, in such a direct-injection gasoline engine (GDI: Gasoline Direct Injection), the combustion chamber is in a combustion state while a part of the sprayed gasoline is kept in a particulate state, so that the particulate fuel The resulting incomplete combustion can generate more PM than a gasoline vehicle that supplies a mixed gas of fuel and air from a conventional intake manifold, and the need for emission regulations has become more realistic. It was.

  It is conceivable to use a wall flow honeycomb filter to remove PM emitted from such a gasoline vehicle as in the case of a DPF for a diesel vehicle, but the DPF for a diesel vehicle is diverted as it is because of the characteristics of the gasoline vehicle. This was difficult for the following reasons.

  One of the major differences between gasoline vehicles and diesel vehicles is the exhaust gas flow velocity. A diesel engine injects fuel into compressed air at high pressure, and kinetic energy is extracted by igniting and exploding the fuel by the action of the pressure. Although it is an efficient engine due to its high compression, it needs to create a high compression state, so the engine speed is lower than that of a gasoline car, and therefore the exhaust gas temperature is also low, so the conventional filter type In order to improve the strength of the honeycomb structure of the honeycomb, that is, the DPF, the outer skin portion is made of a dense high-strength ceramic material.

  However, the situation of exhaust gas from gasoline engines is different from that of diesel engines. Since the gasoline engine ignites the air-fuel mixture by the spark plug, the compression ratio is smaller than that of a general diesel engine. For this reason, the engine can be operated at a high speed and a high output can be obtained, but the exhaust gas temperature during traveling becomes high. Furthermore, due to demands from the market concerning fuel efficiency improvement in recent years, there is a tendency to reduce the size of high-power engines for the purpose of reducing the weight of vehicles. In order to obtain high output with a small engine, it is necessary to operate the engine at a high speed or supply a large amount of air into the cylinder by a supercharger. However, exhaust from an engine operated at a high speed or in a supercharged state is required. The temperature of the exhaust gas is further increased. When a honeycomb structure like conventional DPF, that is, a wall made of a different material in its outer shell (hereinafter also referred to as an outer peripheral wall) is made against such high-temperature exhaust gas, the running temperature is higher than that of a diesel engine. In a gasoline engine catalyst that has a high temperature, there is a concern that cracks may occur due to a difference in thermal expansion coefficient. For this reason, an integral molding may be preferable.

Therefore, as a filter for removing PM from the exhaust gas of a gasoline engine, a honeycomb filter that does not have a dense outer skin portion for obtaining strength, such as DPF, has been studied. Such a PM filter for a gasoline engine is sometimes referred to as a GPF (Gasoline Particulate Filter) (see, for example, Patent Document 3).
If it is GPF, while it is possible to remove PM in the exhaust gas of the gasoline engine which becomes high temperature, a new problem has arisen in the catalyst manufacturing process.

  In general, the exhaust structure of gasoline engines is a three-way catalyst (TWC: Three way Catalyst) containing noble metals such as platinum, palladium, rhodium, etc. A honeycomb structure catalyzed with components that simultaneously purify NOx, HC, and CO The body is used. The conventional TWC is not a honeycomb structure in which both ends of the cell are plugged together like the DPF, but the catalyst component is coated on the partition walls of the honeycomb cell in which both ends of the cell are called a flow-through honeycomb. Have been used. With such a flow-through honeycomb, there is little increase in back pressure and it is suitable for exhaust gas treatment at a high flow rate like a gasoline engine.

When a honeycomb carrier is catalyzed with a catalyst composition such as TWC, not limited to a flow-through honeycomb or a DPF, a manufacturing method generally referred to as a wash coat method is applied (for example, see Patent Document 2).
Various methods have been proposed and implemented for the washcoat. After holding the intermediate position of the honeycomb carrier with a clamp, a part of the lower part is immersed in a liquid bath to impregnate the catalyst component-containing liquid, There is a method in which the slurry is pulled up and turned over, and then blown over the carrier to separate excess slurry, and the entire carrier is impregnated with a catalyst component-containing liquid (for example, Patent Document 5). The basic principle includes “a step of supplying the slurry catalyst component into the honeycomb cell” and “a step of discharging the supplied catalyst slurry by air pressure”. In the “step of discharging the supplied catalyst slurry by air pressure”, if the flow-through honeycomb is used, it is possible to remove excess slurry without any particular trouble. In addition, since the conventional DPF also has a dense outer skin portion, the excess slurry can be removed without any trouble in this case.

  However, since GPF treats high-temperature exhaust gas, its outer peripheral wall is made of a porous material having air permeability like the cell partition walls, and has a porosity of 30% or more, and further a porosity of 50% or more. It is necessary to use a honeycomb structure.

  A relatively small honeycomb structure used for GPF is usually formed by integrally forming partition walls and an outer skin. Such a honeycomb base material is manufactured by simultaneously forming the partition walls and the outer peripheral wall by extrusion molding, and firing the obtained molded body, and the outer skin and the partition walls have the same porosity. . In addition, since such a small honeycomb is used, the geometric area as a filter is small, and there is a great concern about a decrease in output due to pressure loss.

  In addition, since the end of the honeycomb cell is plugged, the plugged part becomes an obstacle in the “process of discharging the catalyst slurry in the supplied cell by air pressure” at the time of wash coating, and the honeycomb cell is discharged by air pressure. There was a problem that the slurry to be leached out from the outer skin part.

If the slurry leaches out from the outer skin portion in this way, the wash coat apparatus becomes dirty, and expensive noble metals are wasted. In particular, during mass production, the slurry leached into the outer skin portion accumulates on the apparatus, which may cause malfunction. In addition, the leaching of the slurry from the outer skin portion may act like an adhesive, and the honeycomb may be difficult to separate from the apparatus as shown in FIG. 4B.
In addition, since an expensive noble metal is used as an automobile catalyst component, the amount of the component is strictly controlled for the purpose of cost control, and if the slurry is leached from the outer skin portion, it becomes difficult to manage the amount of the component, Such a variation in the amount of components is regarded as a manufacturing defect. In addition, the performance of automobile catalysts can only be industrially implemented by managing the appropriate amount of catalyst, but the amount of catalyst carried by each honeycomb during mass production can be reduced by leaching the slurry into the outer skin. Therefore, it has been extremely difficult to achieve stable purification performance.

In addition, since GPF is used in a higher temperature environment than DPF, if a dense skin part such as DPF is provided, a difference in thermal expansion coefficient occurs between the partition wall and the skin part of the cell. There was also a problem that cracks were likely to occur. The honeycomb having cracks loses its function as a filter. For this reason, in the honeycomb used for GPF, it is necessary to set the cell partition walls and the outer skin portion to the same quality, that is, to set the same thermal expansion coefficient. In this way, as a means for making the cell partition wall and the skin portion the same quality, it is conceivable that the cell partition wall and the skin portion are integrally formed of the same material.
However, if the cell partition and the outer skin portion are made homogeneous, the outer skin portion is also formed in a porous manner, and the slurry leaches out into the outer skin portion when wash-coating the catalyst slurry as described above. It is.

  Thus, a means suitable for GPF that can prevent slurry leaching from the outer skin portion is desired, and it is also desirable that the means can be stably and inexpensively applied and can be mass-produced.

Republished 2013-172128 Special table 2003-506221 gazette JP-T-2015-528868 Japanese Patent Laid-Open No. 7-10650 Special table 2003-506221 gazette

  In view of such circumstances, an object of the present invention is to provide a method for producing an exhaust gas purification catalyst capable of suppressing the seepage of catalyst slurry from the outer peripheral wall when the honeycomb carrier is impregnated and coated on the honeycomb carrier. Is to provide.

  As a result of intensive studies to solve the above problems, the inventors of the present invention grasp the specific position of the end of the honeycomb carrier with the elastic body of the elastic grasping jig when the honeycomb carrier is grasped with the elastic grasping jig. By supporting the catalyst with a wash coat, the catalyst slurry can be prevented from leaching to the outer skin portion even when the catalyst composition is sucked into the honeycomb carrier cell at a strong reduced pressure, and a large amount of GPF can be stably produced. The inventors have found that it can be produced, and have completed the present invention.

In order to achieve the above object, the present invention provides the following method for producing an exhaust gas purification catalyst.
That is, according to the first invention of the present invention, a honeycomb carrier comprising a porous partition wall forming a plurality of cells and a porous outer skin portion having a porosity of 30% or more, and having open ends at the top and bottom. A method for producing an exhaust gas purification catalyst carrying a catalyst component in the cell,
A first step of holding an elastic gripping jig in contact with the outer peripheral portion of the honeycomb carrier and gripping the honeycomb carrier with an elastic body; and immersing the lower end of the honeycomb carrier in a slurry liquid bath containing a catalyst component; A second step of decompressing the inside of the cell by decompressing the space containing the slurry and sucking up the slurry liquid; a third step of lifting the honeycomb carrier impregnated with the catalyst component from the slurry liquid bath and reversing the slurry if necessary; The fourth step of air blowing from above the honeycomb carrier to cover the catalyst component in the cell, the fifth step of separating the elastic gripping jig from the honeycomb carrier, and drying the fired detached honeycomb carrier, followed by firing. And a sixth step of supporting the catalyst component,
In the honeycomb carrier holding step, the honeycomb carrier is held by the elastic holding jig so that the exposed length on the upper end side of the honeycomb in the space is within one third of the total length of the honeycomb from the upper end of the elastic body. Exhaust gas purifying catalyst characterized in that the honeycomb part affected by negative pressure is shortened in the next slurry liquid sucking process, and the exudation of catalyst slurry from the honeycomb outer skin is suppressed in the next slurry liquid sucking process. A manufacturing method is provided.

Further, according to a second invention of the present invention, in the first invention, in the exhaust gas purification catalyst manufacturing method, in the first step of gripping the honeycomb carrier, the elastic gripping tool In the second step, the upper end is held by the elastic body so that the exposed length of the upper end side of the honeycomb with respect to the direction of sucking up the slurry is within 1/3 of the total length of the honeycomb from the upper end of the elastic body in the space. To the fourth step to coat the catalyst component in the cells of the honeycomb carrier,
The gripping position of the honeycomb carrier by the elastic body of the elastic gripping jig is changed so that the lower end becomes the upper end, and the gripping position of the honeycomb by the elastic gripping jig is the exposed length of the new upper end side of the honeycomb in the space. Is held by the elastic body so that the length is within 1/3 of the total length of the honeycomb from the upper end of the elastic body, and the new lower end of the honeycomb carrier is immersed again in the slurry liquid bath containing the catalyst component, and then the upper end of the honeycomb carrier is included. A seventh step in which the inside of the cell is depressurized by depressurizing the space to suck up the slurry liquid; an eighth step in which the honeycomb carrier impregnated with the catalyst component is lifted from the slurry liquid bath and reversed if necessary; The air is blown from above, and the ninth step of coating the catalyst component in the cell is repeated,
Thereafter, an exhaust gas purification catalyst comprising a tenth step of separating the elastic gripping jig from the honeycomb carrier and an eleventh step of drying and firing the separated honeycomb carrier and supporting a catalyst component. A manufacturing method is provided.

  According to a third invention of the present invention, in the first or second invention, the elastic gripping jig is configured such that the upper end of the elastic body is a position within 1/10 of the total length of the honeycomb or a position within 10 mm below the upper end of the honeycomb. Among them, there is provided a method for producing an exhaust gas purifying catalyst, characterized in that the exhaust gas purifying catalyst is characterized in that it is gripped by an elastic body at a position where the exposed length on the honeycomb upper end side becomes shorter.

  According to a fourth aspect of the present invention, there is provided the exhaust gas purification catalyst according to any one of the first to third aspects, wherein the honeycomb carrier has a porosity of an outer skin portion of 50 to 80%. A manufacturing method is provided.

  According to a fifth invention of the present invention, in any one of the first to fourth inventions, the outer skin portion of the honeycomb carrier has an average pore diameter measured by a mercury porosimeter of 10 to 30 μm. An exhaust gas purification catalyst manufacturing method is provided.

  According to a sixth invention of the present invention, in any one of the first to fifth inventions, the cells of the honeycomb carrier have plugging portions at the opening end portion on the inlet end surface side and the opening end portion on the outlet end surface side. And a method for producing an exhaust gas purifying catalyst, wherein the plugged portions are arranged alternately.

  According to a seventh invention of the present invention, in any one of the first to sixth inventions, the catalyst composition contains one or more noble metal elements selected from Pt, Pd, and Rh. A method for producing an exhaust gas purification catalyst is provided.

  According to the method for producing an exhaust gas purification catalyst of the present invention, when the catalyst slurry is coated on the cell partition walls of the honeycomb carrier, the catalyst slurry is not easily leached from the outer skin portion. Productivity increases because it becomes easier to separate the elastic body of the tool from the honeycomb. In addition, the amount of the catalyst component can be easily managed without wasting expensive precious metals, and mass production of the catalyst and stable purification performance of the catalyst can be realized.

It is explanatory drawing which showed typically a series of processes which manufacture an exhaust-gas purification catalyst using a honeycomb support | carrier by this invention. It is explanatory drawing which becomes another aspect which showed typically the process of manufacturing an exhaust-gas purification catalyst by this invention. It is explanatory drawing which showed typically the process of manufacturing an exhaust-gas purification catalyst by a conventional method using a honeycomb support | carrier. It is explanatory drawing which showed typically the process of pulling a holding jig (balloon) away from the honeycomb support | carrier with which the slurry was apply | coated in the cell. (A) is the present invention, and (B) is a conventional example. It is the perspective view which showed typically the external appearance of the honeycomb structure (carrier | carrier).

  Hereinafter, the present invention will be described based on specific embodiments. However, the present invention is not construed as being limited to these embodiments, and within the scope of the present invention, the knowledge of those skilled in the art. Based on this, design changes and improvements can be added as appropriate.

1. Honeycomb structure As shown in Fig. 5, a honeycomb carrier (also referred to as a honeycomb structure) used in the present invention includes a porous partition wall forming a plurality of cells, and a porous outer skin having a porosity of 30% or more. This is a honeycomb-shaped substrate 1 made of a portion and having open ends at the top and bottom.

In the honeycomb-shaped base material, a large number of through holes (cells) extending from one end face to the other end face are formed by partition walls, and these gather together to form a honeycomb.
Honeycomb carriers are roughly classified into a flow-through type (flow-through honeycomb) and a wall-flow type (wall-flow honeycomb) because of their structural features. The flow-through type is widely used for oxidation catalysts, reduction catalysts, and three-way catalysts because a large number of through-hole ends that open from one open end surface to the other open end surface are not sealed. On the other hand, in the wall flow type, one end of the through-hole is alternately sealed, and solid components such as soot and SOF (Soluble Organic Fraction) in exhaust gas can be filtered out. Therefore, it is used as a DPF. The present invention can be used for either of them, but in the case of a honeycomb substrate having a porous outer peripheral wall such as GPF, the catalyst slurry can be prevented from being leached into the outer skin portion during production, and therefore it is used particularly for GPF. It can be suitably used for a wall flow honeycomb.

Moreover, since it is necessary to let exhaust gas escape from the partition which comprises a honeycomb, the partition is formed with a porous body. Consisting of inorganic oxides usually used as porous materials, silicon carbide, silicon-silicon carbide based composite materials, cordierite, mullite, alumina, silica-alumina, spinel, silicon carbide-cordierite based composite materials, lithium Ceramic materials such as aluminum silicate and aluminum titanate are preferred. Among these, cordierite is particularly preferable. This is because when the honeycomb base material is cordierite, a honeycomb structure having a small thermal expansion coefficient and excellent thermal shock resistance can be obtained.
The partition wall and the outer skin portion may be made of the same material or different materials. In GPF, it is preferably formed of the same material. The homogeneous material refers to a material having a range of difference in thermal expansion coefficient and porosity that can prevent cracking due to thermal shock. Further, it is preferably manufactured by integral molding using the same material. This is because efficient production is possible and problems due to differences in materials can be avoided. In addition, there is a concern about problems such as cracks caused by a difference in thermal expansion coefficient in a gasoline engine catalyst that becomes high temperature. For this reason, it is preferable that the partition wall and the outer skin portion have the same thermal expansion coefficient or are integrally molded.
The material of the plugging portion is preferably the same material as that of the honeycomb substrate. The material of the plugging portion and the material of the honeycomb substrate may be the same material or different materials.

  The average pore diameter of the honeycomb base material (partition walls and outer peripheral wall) is preferably 10 to 30 μm, and particularly preferably 15 to 25 μm. When the average pore diameter of the honeycomb base material is less than 10 μm, the pressure loss of the honeycomb structure becomes too high, and when used as a GPF, the engine output may be reduced. Further, when the average pore diameter of the honeycomb substrate exceeds 30 μm, sufficient strength may not be obtained. Here, the “average pore diameter” is a value measured by a mercury porosimeter.

Moreover, 1-18 mil (0.025-0.47 mm) is preferable and, as for the thickness of the partition which is a cell wall, 6-12 mil (0.16-0.32 mm) is more preferable. If the partition wall is too thin, it becomes structurally brittle, and if it is too thick, the geometric surface area of the cell becomes small, which may reduce the effective usage rate of the catalyst. In addition, if the partition wall is too thick, the pressure loss becomes high, and when used as a GPF, there is a risk of causing a decrease in engine output.
The thickness of the outer peripheral wall of the honeycomb base material is preferably 300 to 1000 μm, particularly preferably 500 to 800 μm. If the thickness of the outer peripheral wall is less than 300 μm, sufficient strength may not be obtained. When the thickness of the outer peripheral wall exceeds 1000 μm, the pressure loss of the honeycomb structure becomes too high, and when used as a GPF, the engine output may be reduced.

The cell formed by the partition walls is usually about 0.8 to 2.5 mm in diameter or one side, and its density is expressed by the number of holes per unit cross-sectional area, which is also called cell density. The cell density of the honeycomb structure is not particularly limited, but is preferably 100 to 1200 cells / inch ² (15.5 to 186 cells / cm ² ), and 150 to 600 cells / inch ² (23 to 93 cells / cm ² ). Is more preferable, and 200 to 400 cells / inch ² (31 to 62 cells / cm ² ) is particularly preferable. When the cell density exceeds 1200 cells / inch ² (186 cells / cm ² ), clogging is likely to occur due to catalyst components and solids in the exhaust gas, and pressure loss becomes too high. In addition, engine output may be reduced.
If it is less than 100 cells / inch ² (15.5 cells / cm ² ), the geometric surface area becomes small, so that the effective usage rate of the catalyst is lowered and the usefulness as an exhaust gas purification catalyst may be lost. Further, when used as a GPF, the effective area as a filter is insufficient, the pressure loss after PM deposition becomes high, and the output of the engine may be reduced.

In a TWC for a gasoline vehicle to which a honeycomb structure is applied, the honeycomb base material needs to be formed of a porous body having at least a skin portion that is the same as a partition wall and having a porous body. When the GPF according to the present invention is manufactured, it is possible to prevent the catalyst slurry from leaching to the outer skin portion by the coating.
A large number of pores exist in the cell partition and the outer skin portion. The porosity of the honeycomb partition walls having a plurality of cells and the outer skin is 30% or more, preferably 50 to 80%, and more preferably 60 to 70%. Moreover, 10-30 micrometers is preferable and, as for a pore diameter, it is more preferable that it is 15-25 micrometers. In the present invention, the method for measuring the porosity is not particularly limited, and examples thereof include a measuring method using a mercury porosimeter.

The shape of the honeycomb structure is not particularly limited, and includes a generally known columnar shape, an elliptical columnar shape similar to a columnar shape, and a polygonal column. A cylindrical shape or an elliptical column shape is preferable.
Further, the shape of the cell in the cross section perpendicular to the longitudinal direction of the honeycomb substrate (hereinafter referred to as “cell shape”) is not particularly limited, but is a polygon such as a quadrangle, hexagon, octagon, or a combination thereof. For example, a rectangle, a hexagon, a combination of a rectangle and an octagon, and the like are preferable.
The size of the honeycomb base material is relatively small such as a diameter of about 60 mm and a length of 70 mm, and a large size such as a diameter of about 300 mm and a length of 200 mm. Not limited by size.

The outer skin layer can be formed by contact with the resin composition over the entire outer surface of the outer peripheral wall of the honeycomb base material or in a partial area. In the present invention, it is preferable that a skin layer made of a resin composition is formed on at least both ends of the honeycomb. The outer skin layer preferably contains a resin composition (sealer) that can be impregnated in the pores of the outer peripheral wall with a width of about 10 to 20 mm from both ends.
Thus, it is not essential to perform sealer treatment on both ends, but even if the end of the outer peripheral wall of the honeycomb is exposed to a negative pressure atmosphere during suction of the catalyst slurry due to manufacturing problems, catalyst slurry leaching is not possible. Can be prevented.

  The kind of the resin composition is not particularly limited, and polyvinyl alcohol (PVA), acrylic resin, acrylic silicon resin, acrylic styrene resin, vinyl acetate resin, polyurethane resin, polyethylene glycol (PEG), agar, gelatin, starch, sucrose Wax or wax can be used.

When a honeycomb structure is used for a PM collection filter such as GPF, a plugging portion is formed to plug an opening end portion on the inlet end face side of a predetermined cell and an opening end portion on the outlet end face side of the remaining cells. ing.
Thus, by plugging one open end of each cell of the honeycomb substrate with the plugging portion, the honeycomb structure becomes a wall flow type filter having high PM collection efficiency. In this wall flow type filter, the exhaust gas flowing into the cell from the inlet end face passes through the partition wall and then flows out of the cell from the outlet end face. And when exhaust gas permeate | transmits a partition, a partition functions as a filtration layer and PM contained in exhaust gas is collected.
The plugged portion has an inlet end surface and an outlet end surface, each of which has a plugged open end portion and a plugged portion, and the open end portion is not plugged by the plugged portion. The cells are preferably formed so as to have an alternating checkered pattern. However, the embodiment of the present invention is not limited to such a wall flow filter.

  The problem of leaching of catalyst slurry to the outer surface of the outer peripheral wall and insufficient strength are particularly noticeable in a high-porosity honeycomb structure having a porosity of 50% or more. Therefore, the present invention is highly useful when a honeycomb substrate having a porosity of 50 to 80% is used, and is particularly useful when a honeycomb substrate having a porosity of 60 to 70% is used.

2. Manufacturing method of exhaust gas purifying catalyst The manufacturing method of an exhaust gas purifying catalyst of the present invention comprises a porous partition wall forming a plurality of cells and a porous outer skin portion having a porosity of 30% or more, and is opened vertically. A method for manufacturing an exhaust gas purifying catalyst having a catalyst component supported in a cell of a honeycomb carrier having an end, wherein an elastic gripping jig is brought into contact with the outer periphery of the honeycomb carrier, and the honeycomb carrier is gripped by an elastic body And a second step in which the lower end of the honeycomb carrier is immersed in a slurry liquid bath containing a catalyst component, and then the space including the upper end of the honeycomb carrier is decompressed to decompress the inside of the cell and suck up the slurry. And a third step of lifting the honeycomb carrier impregnated with the catalyst component from the slurry liquid bath and inverting it if necessary, and a fourth step of coating the catalyst component in the cell by blowing air from above the honeycomb carrier. A fifth step of separating the elastic gripping jig from the honeycomb carrier, and a sixth step of supporting the catalyst component by drying and firing the detached honeycomb carrier,
In the honeycomb carrier holding step, the honeycomb carrier is held by the elastic holding jig so that the exposed length on the upper end side of the honeycomb in the space is within one third of the total length of the honeycomb from the upper end of the elastic body. This is characterized in that the honeycomb portion affected by the negative pressure is shortened in the next slurry liquid sucking step, and the exudation of the catalyst slurry from the honeycomb outer skin is suppressed in the next slurry liquid sucking step.

  Conventionally, in the wash coating method using the catalyst composition slurry on the honeycomb carrier, for example, in the case of DPF, as shown in FIG. The honeycomb carrier is held by an elastic body. At this time, close gripping is desirable because a suction operation is required in the step of sucking the slurry liquid into the next cell.

  The DPF carrier is relatively dense and has high mechanical strength, but its weight and size are large. It is thought to prevent the dropout and damage. In addition, it is considered that when gripping is performed at an almost intermediate position, it is easy to achieve a balance during coating, and it is difficult to be affected by misalignment or the like. Further, the outer skin of the GPF carrier has a high porosity, is more fragile than the DPF carrier, and may be broken if gripped at the end. In either case, the honeycomb gripping position is preferably gripped in order to stably carry out the process.

  However, as in the first coat shown in the upper part of FIG. 3, after holding the honeycomb carrier with the elastic body of the elastic holding jig and sucking the slurry (arrows 2 to 3), the honeycomb carrier is inverted and air is blown from above. In the step of spraying and coating the catalyst component in the cell (arrow 5), when the suction pressure in the previous step is strong, the slurry leaches out at the part of the outer skin affected by the suction. Thereafter, the same applies to the second coating shown in the lower part of FIG. 3. After holding the honeycomb carrier with the elastic body of the elastic holding jig and sucking the slurry (arrows 7 to 8), the honeycomb carrier is inverted. Then, when air is blown from above and the suction pressure in the previous step is strong in the step of coating the catalyst component in the cell (arrow 11), the slurry leaches out at the outer skin part affected by the suction.

Such a tendency is conspicuous when the pressure reduction during suction is large, and if the honeycomb is gripped by the intermediate portion in the longitudinal direction, the slurry tends to ooze from the outer skin above the gripping portion. Become.
Further, not only such problems in catalyst production but also accurate catalyst loading cannot be controlled, and the slurry of the catalyst composition that has soaked out is placed on the partition walls of the cell, which is a surface advantageous for exhaust gas purification in the honeycomb structure. In the case of TWC or the like that normally uses a large amount of noble metal, expensive noble metal is wasted, which is disadvantageous in terms of cost.

  Therefore, in the present invention, in the honeycomb carrier holding step, the honeycomb carrier is held by the elastic holding jig so that the exposed length on the upper end side of the honeycomb in the space is within one third of the total length of the honeycomb from the upper end of the elastic body. It is preferable that the position where the length is reached is held by an elastic body so that the portion of the honeycomb that is affected by the reduced pressure is shorter than the conventional portion in the subsequent slurry liquid sucking step. As a result, it is easy to suppress the seepage of the catalyst slurry from the honeycomb outer skin portion exceeding at least 2/3 of the total length of the honeycomb.

  The honeycomb carrier is held by the elastic holding jig by holding the elastic body at a position where the exposed length on the upper end side of the honeycomb in the space is within one third of the entire length of the honeycomb from the upper end of the elastic body. The closer to the honeycomb end, the more effective, and more preferable is that there is no exposed width on the upper end side of the honeycomb. As described above, the slurry leaching site on the outer peripheral portion can be reduced as the elastic body of the elastic gripping jig is gripped at a shallow position of the honeycomb to reduce the site affected by the pressure during suction.

I. One-time coating In the present invention, an elastic gripping jig is brought into contact with the outer peripheral portion of the honeycomb carrier to grip the honeycomb carrier with an elastic body, and the lower end of the honeycomb carrier is placed in a slurry liquid bath containing a catalyst component. After dipping, the space including the upper end of the honeycomb carrier is decompressed to decompress the inside of the cell to suck up the slurry liquid, and the honeycomb carrier impregnated with the catalyst component is pulled up from the slurry liquid bath and reversed if necessary. A third step of separating the elastic carrier from the honeycomb carrier, a fourth step of covering the cell with the catalyst component by blowing air from above the honeycomb carrier, and a fifth step of separating the elastic gripping jig from the honeycomb carrier. Including a sixth step of drying and firing the honeycomb carrier and supporting the catalyst component;
In the honeycomb carrier holding step, the honeycomb carrier is held by the elastic holding jig so that the exposed length on the upper end side of the honeycomb in the space is within one third of the total length of the honeycomb from the upper end of the elastic body. In the next slurry liquid sucking process, the honeycomb portion affected by the negative pressure is shortened, and the seepage of the catalyst slurry from the honeycomb skin is suppressed.

  The catalyst produced in the present invention uses a honeycomb carrier as a filter in order to remove fine particulate matter contained in exhaust gas from automobiles, so there are macropores on the outer wall and there are places where they communicate. To do. That is, the slurry liquid is likely to ooze out from the outer space.

  The present invention purifies NOx, CO, and hydrocarbons by holding a honeycomb filter carrier that captures fine particulate matter (PM) in exhaust gas discharged from a gasoline vehicle at its outer periphery with an elastic gripping jig. This is suitable when the catalyst component of the three-way catalyst (TWC) is carried in the cell or inside the partition wall constituting the cell, but is not limited to this, and is also applicable to the manufacture of a honeycomb catalyst for exhaust gas purification from a diesel vehicle. be able to.

  Next, it explains in full detail for every manufacturing process using FIG.

(1) First Step: Holding the Honeycomb Carrier First, as shown in FIG. 1, an elastic holding jig is brought into contact with the outer peripheral portion of the honeycomb carrier, and the honeycomb carrier is held by an elastic body.

  In the present invention, the elastic body is, for example, a hollow donut-shaped member that allows air to be taken in and out like a balloon, a float, or a tire tube (hereinafter also referred to as “balloon”), or a soft resin member. For example, the surface is slightly stretchable. The balloon may be divided into two in the circumferential direction, or may be attached in a bowl shape to a two-point supported elastic gripping jig (arm). These can control the adhesion to the honeycomb with sufficient confidentiality by adjusting the contact and pressure of air.

  At the time of this gripping operation, the elastic gripping jig moves the honeycomb carrier from the elastic body so that the exposed length on the upper end side of the honeycomb in the space is within one third of the total length of the honeycomb from the upper end of the elastic body. It is preferable to grip with.

  However, such measures are most preferable if the device can be gripped without being exposed on the upper end side of the honeycomb depending on the device. From the honeycomb with the upper end side slightly exposed as described above, there is a concern about slurry leaching in the slurry sucking process described later. However, if the holding position of the present invention is held, the leaching portion of the slurry can be shortened. In addition, the amount of leaching of the slurry can be suppressed by means such as reducing the fluidity by keeping the device environment at a low temperature.

  When the honeycomb base material is relatively small such as a diameter of about 60 mm and a length of 70 mm, it is light, so there is no problem even if the upper end of the honeycomb is not exposed. In addition, although a large one having a diameter of about 300 mm and a length of 200 mm becomes heavy, in the present invention, for example, by selecting the material of the elastic body of the elastic gripping jig and controlling the gripping force, the length of the honeycomb is 3 minutes. It can be handled by gripping with an elastic body at a position where the exposed length is within one.

(2) Second step: suction of slurry liquid by decompression While holding the honeycomb carrier with the elastic body of the elastic holding jig, the honeycomb carrier is placed in the slurry liquid bath containing the catalyst component as indicated by arrows 2 and 3 in FIG. After dipping the lower end of the cell, the space including the upper end of the honeycomb carrier is depressurized to depressurize the inside of the cell, and the slurry liquid is sucked up.

A predetermined amount of slurry is stored in the slurry liquid tank. Each time the honeycomb is immersed, the slurry liquid decreases, but the reduced amount is automatically replenished.
In the case of a three-way catalyst (TWC), a catalyst component mainly composed of a noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh) is used. Since a catalyst such as a noble metal is supported on the cell partition wall in a highly dispersed state, it is preferably supported on a cell partition wall of a honeycomb carrier after being previously supported on a heat-resistant inorganic oxide having a large specific surface area such as alumina. In addition to alumina, as a heat-resistant inorganic oxide for supporting a catalyst, zeolite or the like can be used as a component for improving heat resistance and a component for occluding and releasing oxygen. Further, a catalyst such as a noble metal may be immobilized on a promoter made of Ce, Zr, or a composite oxide thereof, and then supported on the cell partition walls of the honeycomb.
A noble metal component supported on particles such as alumina is dispersed in an aqueous medium and stored in a liquid tank as a slurry containing an additive such as a thickener as necessary. The slurry containing such components is sticky because it is in the form of a slurry, and this also causes sticking of elastic bodies such as balloons.

  The slurry of the catalyst composition used for the production of the honeycomb catalyst of the present invention is not limited by the kind or particle size of the inorganic particles, but it is preferable that at least a part thereof can enter the pores of the partition walls. The slurry of such a catalyst composition is finely divided by a ball mill or the like so that the particle size D90 when the cumulative distribution from the small particle size side in the particle size distribution is 90% is 5 μm or less. More preferably, D90 is 3 μm or less. When such D90 is 5 μm or less, an appropriate amount of the catalyst component can enter into the pores of the partition walls. In particular, when a wall flow honeycomb is used for GPF, the ability to purify particulate components such as soot as well as harmful components in the exhaust gas is sufficiently exhibited, and pressure loss is not unnecessarily caused.

In the conventional method, the amount of slurry that can be coated on the entire cell inside the honeycomb is sucked up in this step. However, when the amount of slurry sucked is large, it is easy to overflow or ooze from the side surface in the decompression space including the upper end of the honeycomb and the upper end of the honeycomb carrier when decompressed.
In contrast, in the present invention, it is not excluded to supply an amount of slurry that can be coated over the entire length of the honeycomb axis. If the exposed length of the honeycomb upper end side in the decompression space including the upper end of the honeycomb carrier with respect to the body is shortened, the portion of the slurry leached out becomes smaller, and even if the slurry is sucked up near the upper end, the slurry from the honeycomb outer skin portion Less seepage.

(3) Third Step: Lifting Honeycomb from Slurry Liquid Bath The honeycomb carrier impregnated with the catalyst component is lifted from the slurry liquid bath as shown by arrow 3 in FIG.

Here, in order to adjust the coating amount by controlling the dripping amount of the slurry, a weak suction may be applied as necessary. If the slurry is sufficiently sucked into the cell, the process can proceed as it is. When the air is blown as it is without reversing after the slurry is sucked, a portion not covered with the slurry remains.
The drive part of the elastic gripping jig can be operated and reversed, and if this reversing operation is performed, the immersion of the slurry can be suppressed more reliably.

(4) Fourth Step: Air Blow Next, as indicated by an arrow 6 in FIG. 1, a hood is placed on the upper part of the elastic holding jig holding the honeycomb, and air is blown from above the honeycomb carrier.

  The problem of slurry leaching that has been pointed out in the conventional method becomes even greater when the pressure (flow rate) of air blow is strong. When the slurry liquid is sucked, the amount of the liquid stays in the cell and enters the pores of the outer wall is small. However, when it is time to invert the honeycomb and blow air, the liquid attached to the inner surface of the cell at that pressure (flow rate) is pushed out from the pores and easily oozes out from the outer wall. For this reason, when the honeycomb is gripped by the intermediate portion in the length direction, the slurry often oozes out from the outer skin above the grip portion.

  On the other hand, in the present invention, in this air blowing step, the elastic holding jig has an exposed length on the upper end side of the honeycomb in the space of 3 minutes of the total length of the honeycomb from the upper end of the elastic body in the holding step of the honeycomb carrier. It is in the state gripped with the elastic body so that it may become the length within 1 of this. Depending on the device, a length of 9/10 or more of the entire honeycomb length may be held by the elastic body at a position where it enters the hood.

  In this way, it is possible to lengthen the portion where the pressure difference between the inside and outside of the honeycomb is small during blow pressurization. That is, the inside of the hood is pressurized by blowing, but balances with the pressure inside the honeycomb, and the slurry is difficult to move in the radial direction (outer wall direction). Because the exposed length from the gripping part is short, there is no leaching part because there is no leaching of the slurry or the amount of slurry that moves in the direction of the outer wall under the influence of the pressure during blowing is small. The length is short and the amount of seepage is small.

As a result, the catalyst component is coated in the cells while suppressing the seepage of the catalyst slurry from the honeycomb outer skin. The amount of noble metal supported is preferably 0.3 to 3.5 g / L per unit volume of the honeycomb carrier.
The surplus slurry coming out from the lower end of the honeycomb by air blowing is preferably not returned to the slurry liquid tank but received in another liquid tank in order to prevent the composition from changing.

(5) Fifth Step: Separation of Elastic Holding Jig After that, as shown in FIG. 4A, the elastic holding jig holding the honeycomb is moved to separate the elastic holding jig from the honeycomb carrier. The honeycomb after slurry coating is separated by contracting if air is removed if the gripping portion is a balloon, and separated by mechanical retraction if it is a soft resin.

In the honeycomb, since the catalyst slurry is prevented from soaking from the outer skin portion, the elastic body of the elastic holding jig is weakly fixed to the honeycomb and easily separated.
The outer shell of the GPF carrier has a high porosity and is more fragile than the DPF carrier, and there is a risk of destruction when gripped at the end, but since it is easily separated, it will not break.

  In the present invention, when a honeycomb having an organic thin film formed at least on the gripping portion on the outer surface is used, it is possible to narrow the fixing region in combination with being less susceptible to pressure fluctuation at the contact portion with the balloon. .

(6) Sixth step: drying and firing In one-time coating, the honeycomb carrier is finally dried and then fired to carry the catalyst component. As a result, the catalyst is supported on the honeycomb carrier in a single layer.
Here, the drying / firing conditions are not particularly limited, but the drying is performed, for example, at 100 to 200 ° C. for 0.1 to 3 hours, and the firing is performed at, for example, 400 to 600 ° C. in an oxidizing atmosphere for 0.5 to 0.5 hours. It is preferable to carry out over 5 hours.

  The above process is automated, and arm expansion / contraction, rotation, traveling, honeycomb movement by a belt conveyor, hood attachment / detachment, decompression device, air blow device, and the like are automatically controlled. During this time, the honeycomb is depressurized, and a predetermined amount of catalyst slurry enters the cell, is inverted, and is expanded in the cell by air (air) blow, and a single layer of uncoated paint is seen at the lower end. A catalyst is obtained.

II. Two-time coating The present invention is a method for producing a honeycomb catalyst by performing the same operation on the catalyst obtained by the first coating.

That is, in the first step of gripping the honeycomb carrier, the exposed length of the upper end side of the elastic body with respect to the direction of sucking up the slurry liquid by the elastic gripping jig To hold within 1/3 of the total length of the honeycomb with an elastic body, and after performing the fourth to fourth steps to coat the catalyst components in the honeycomb carrier cells,
The gripping position of the honeycomb carrier by the elastic body of the elastic gripping jig is changed so that the lower end becomes the upper end, and the gripping position of the honeycomb by the elastic gripping jig is the exposed length of the new upper end side of the honeycomb in the space. Is held by the elastic body so that the length is within 1/3 of the total length of the honeycomb from the upper end of the elastic body, and the new lower end of the honeycomb carrier is immersed again in the slurry liquid bath containing the catalyst component, and then the upper end of the honeycomb carrier is included. A seventh step in which the inside of the cell is depressurized by depressurizing the space to suck up the slurry liquid; an eighth step in which the honeycomb carrier impregnated with the catalyst component is lifted from the slurry liquid bath and reversed if necessary; The air is blown from above, and the ninth step of coating the catalyst component in the cell is repeated,
Thereafter, a tenth step of separating the elastic holding jig from the honeycomb carrier and an eleventh step of drying and firing the separated honeycomb carrier and supporting the catalyst component are performed.

  In the present invention, when the honeycomb carrier is a wall flow type honeycomb for GPF and the catalyst composition slurry is wash coated on the honeycomb, the coating amount is 10 to 200 [g / L] per unit volume of the honeycomb structure. Is preferable, and 30 to 100 [g / L] is more preferable. When the catalyst amount is 10 [g / L], excellent purification performance can be expected for CO, HC and NOx together with the fine particle components in the exhaust gas. When the catalyst amount is 200 [g / L] or less, it can be used as a filter for a wall flow type honeycomb. There is no hindrance to function. However, if it is performed only once, the coating may be uneven and may not be within the above range.

  Applying the catalyst slurry in two steps is because the gradient of the catalyst component amount increases in the axial direction of the honeycomb in one application, so the concentration gradient is reduced by applying from both ends, and at each part of the honeycomb catalyst This is to stabilize the catalyst performance and to reduce the amount of slurry (residual slurry) discharged during air blowing by making the supplied slurry a little insufficient for spreading over the entire length of the cell. .

Further, since the present invention is intended for the wall flow type, there is a case where a sufficient amount of catalyst cannot be formed by coating from one side of the partition walls of the cell by one coating. Even in such a case, it is effective to repeat the process up to the air spraying with the honeycomb soaking position reversed, and the honeycomb can be coated with a necessary amount of catalyst.
According to such twice coating, two kinds of catalyst layers can be provided on the front and back of the partition walls of the cell.

(7) Seventh step: re-grip of honeycomb carrier FIG. 2 shows a method for manufacturing a honeycomb structured catalyst after this step. First, the second step to the fourth step are performed to coat the catalyst component in the cells of the honeycomb carrier, and the honeycomb that remains uncoated at the lower end is placed at an appropriate position by the elastic body of the elastic gripping jig. Re-grip. At this time, the exposed length of the upper end of the elastic body with respect to the direction of sucking up the slurry liquid is within 1/3 of the total length of the honeycomb from the upper end of the elastic body in the space. It is preferable to hold it with an elastic body.

The suction of the slurry liquid in the second catalyst coating is performed on the end face where the slurry liquid was not sucked up in the first time. After completion of the first time, the elastic body (balloon) is in a state of gripping the lower end of the honeycomb. However, since the slurry soak is suppressed and the elastic body (balloon) can be easily moved toward the upper end of the honeycomb, the holding position of the honeycomb carrier is changed to the opposite side from the first, and the elastic holding jig is used to It is preferable that the exposed length of the upper end of the body on the upper end side of the honeycomb with respect to the direction of sucking up the slurry is within 1/3 of the total length of the honeycomb from the upper end of the elastic body in the space.
In addition to this, a method of lowering the honeycomb once on the work table and rotating it and then grasping it with an elastic body can be considered, but this is not preferable because it increases labor.

  At the second time, gripping at a shallow position of the honeycomb reduces the area affected by the pressure during suction, reduces the slurry leaching area on the outer periphery, and the elastic fluid gripping the catalyst component-containing liquid oozes on the outer periphery of the filter carrier. It does not interfere with the detachment of the jig.

(8) Seventh step: sucking up the slurry liquid After that, as indicated by arrows 7 and 8 in FIG. 2, the lower end of the honeycomb carrier is immersed again in the slurry liquid bath containing the catalyst component, and then the space including the upper end of the honeycomb carrier. The slurry is sucked into the cell by reducing the pressure. Since the composition and concentration of the remaining slurry are changed and cannot be reused as they are, a newly prepared slurry liquid tank is used.

(9) Steps 8 to 9: Re-coating with catalyst slurry Next, as shown by the arrow 9 in FIG. 2, the honeycomb carrier impregnated with the catalyst component is pulled up from the slurry liquid bath and reversed as necessary. As indicated by the arrow 11, air is blown from above the honeycomb carrier to coat the catalyst component in the cell.
This step is exactly the same as the procedure for the first coat.

(10) Tenth to eleventh steps: Separation of honeycomb carrier and supporting of catalyst component by drying / firing Next, as shown in FIG. 4A, a tenth step of separating the elastic gripping jig from the honeycomb carrier Then, the separated honeycomb carrier is dried and then fired to carry out an eleventh step for supporting the catalyst component.

This process is also exactly the same as the first coat. As a result, the noble metal supported on the inorganic particles such as alumina is supported on the honeycomb in two layers by the slurry containing it.
As described above, the components of the slurry also include an adhesive substance that facilitates the deposition of the catalyst material in the cell, which is also a cause of sticking of the balloon, which is an elastic body of the elastic gripping jig. However, in the present invention, since it is gripped at a specific portion at the end of the honeycomb, it is difficult to be subject to pressure fluctuation at the contact portion with the balloon, so that the fixing region is not widened.

  Hereinafter, the embodiments of the present invention will be described in more detail, but the present invention is not limited thereto.

<Embodiment 1>
(1) A cordierite wall flow honeycomb structure (diameter: 120 mm, length: 90 mm) is used as a GPF honeycomb carrier, and the upper end of the honeycomb carrier 1 is elastically gripped (see FIG. 1). (Balloon) 2 is held and gripped so that the tip of the honeycomb is exposed by about 5 mm from the upper end of the balloon. In FIG. 1, the elastic body 2 is shown in a bowl shape, but is tightly gripped on the outer peripheral surface of the honeycomb like a tire hose. Above the honeycomb is an airtight space. Although not shown, a pressure reducing device is connected to the elastic gripping jig.
The catalyst slurry liquid tank 6 is filled with the catalyst slurry liquid so that the liquid amount is constant. As the catalyst slurry liquid, a slurry obtained by slurrying a ternary catalyst (TWC) component in which noble metal Rh is supported on alumina is used.

(2) The honeycomb gripped by the elastic gripping jig (balloon) is dipped in the catalyst slurry liquid tank from its lower end. The lower end position of the honeycomb immersed in the slurry liquid tank is not particularly limited, but is about 5 to 30 mm.

(3) Next, the airtight space of the elastic gripping jig is set to a high negative pressure by a decompression device. The catalyst slurry flows into the cell from the lower end of the honeycomb, and the slurry moves toward the upper end of the honeycomb while covering the inner wall of the cell with the slurry. At this time, about 1/3 of the suction level is left unpainted. Since the exposed portion of the tip 4 of the honeycomb is 5 mm above the elastic body and is short, there is no portion where the slurry oozes out. Even if the slurry is sucked up to the upper end of the honeycomb, the leaching is reduced only in this limited portion.
In the conventional method, the holding position of the honeycomb carrier is not particularly limited, and the honeycomb intermediate portion is often held as indicated by the arrow 2 in FIG. 3 because of easy handling in manufacturing. For this reason, in a carrier having a high outer shell porosity such as a honeycomb carrier for GPF, even if the slurry is sucked so as to leave a coating residue of about 10 mm at the upper end of the honeycomb by suction, the elastic body is applied to the upper part during the suction. A large amount of slurry immersion occurred. As described above, when a negative pressure is applied to the honeycomb cell and the suction pressure is high, the slurry is leached out at a portion affected by the suction.
In the present invention, since the end portion of the honeycomb or a slightly lower portion thereof is gripped, even when the suction pressure is strong, there are few parts affected by suction, and the amount of slurry leaching is small.

(4) The honeycomb that has sucked the slurry is pulled up from the slurry liquid tank and inverted. Suction may be continued when pulling up from the slurry liquid tank. Thereafter, by reversing, the portion where the honeycomb cell is left uncoated as shown by the arrow 5 is directed downward, and the portion where the slurry is coated is directed upward.

(5) In this state, the hood 7 is put on the portion of the honeycomb cell where the slurry is applied. The hood covers the upper honeycomb portion from the upper end of the elastic body. And although not shown in figure, air is supplied from the air blowing apparatus connected to the food | hood, and the slurry in a cell flows below. At this time, the cell skin is in a state of being pressurized from the outside, and the slurry does not leach from the skin.

(6) Since only a small amount of slurry oozes out from the honeycomb outer skin, the elastic gripping jig can be easily separated from the honeycomb. The separated honeycomb carrier is dried at 25 to 100 ° C. by standing or heating device, and then calcined at 400 to 600 ° C. for 0.5 to 3 hours to carry the catalyst component. For GPF, The above operation is repeated.

<Embodiment 2>
(7) In a different embodiment of the present invention, the same operation is repeated without drying and firing using the honeycomb in which the catalyst slurry is applied in the cell in the first embodiment. As shown in FIG. 2, the upper end of the honeycomb carrier 1 is brought into contact with the elastic gripping jig (balloon) 2 in the outer peripheral portion of the honeycomb carrier 1, but is gripped so that the tip of the honeycomb is exposed about 5 mm from the upper end of the balloon in the first step. Therefore, the elastic gripping jig can be easily separated from the honeycomb. In this step, the honeycomb re-gripping may be such that the tip of the honeycomb is exposed by about 5 mm from the upper end of the balloon as in the first step, or the exposed width is about 10 to 15 mm and is held slightly toward the center. You may do it.

(8) The honeycomb gripped by the elastic gripping jig (balloon) is dipped in the catalyst slurry liquid tank 6 from the lower end 8 on the side where the slurry is not applied in the aspect 1. The lower end position of the honeycomb immersed in the slurry liquid tank is not particularly limited, but is about 5 to 30 mm.

(9) Next, the airtight space of the elastic gripping jig is set to a high negative pressure by the decompression device. The catalyst slurry flows into the cell from the lower end of the honeycomb, and the slurry moves toward the upper end of the honeycomb while covering the inner wall of the cell with the slurry. At this time, about 1/3 of the suction level is left unpainted. At the tip of the honeycomb, about 5 mm above the elastic body is exposed, but the slurry is immersed only in this limited portion.
In the conventional method, as shown by the arrow 7 in FIG. 3, the honeycomb intermediate portion is gripped. For this reason, even if the slurry is sucked so as to leave a coating residue of about 10 mm on the upper end of the honeycomb by suction, a large amount of slurry soaks again from the elastic body to the upper part during the suction. As described above, when a negative pressure is applied to the honeycomb cell and the suction pressure is high, the slurry is leached out at a portion affected by the suction.
In the present invention, since the end portion of the honeycomb or a slightly lower portion thereof is gripped, even when the suction pressure is strong, there are few parts affected by suction, and the amount of slurry leaching is small.

(10) The honeycomb that has sucked the slurry is pulled up from the slurry liquid tank and inverted. Suction may be continued when pulling up from the slurry liquid tank. Thereafter, by reversing, the portion where the honeycomb cell is left uncoated as shown by the arrow 11 is directed downward, and the portion where the slurry is applied to the cell is directed upward.

(11) In this state, the hood is put on the portion of the honeycomb cell where the slurry is applied. The hood covers the upper honeycomb portion from the upper end of the elastic body. And air is supplied from the air blower connected to the hood, and the slurry in the cell flows downward. At this time, the cell skin is in a state of being pressurized from the outside, and the slurry does not leach out.

(12) Finally, the elastic gripping jig can be easily separated from the honeycomb. The detached honeycomb carrier is dried at 25 to 100 ° C. by standing or heating, and then calcined at 400 to 600 ° C. for 0.5 to 3 hours to carry the catalyst component.

<Embodiment 3>
(1) A cordierite wall flow honeycomb structure (diameter: 300 mm, length: 300 mm) having a large size instead of the cordierite wall flow honeycomb structure (diameter: 120 mm, length: 90 mm) used in Embodiment 1 above 1 is used as a honeycomb carrier for GPF, and as shown in FIG. 1, the upper end of the honeycomb carrier is held in contact with an elastic holding jig (balloon) so that the tip of the honeycomb is exposed from the upper end of the balloon by about 10 mm. To do. Since the honeycomb is large, the gripping position is set at a slightly intermediate position so that the honeycomb can be stably gripped.

(2) Steps 2 to 6 are performed in the same manner as in the first embodiment. In the present invention, the lower part of the end of the honeycomb is gripped, so even when the suction pressure is strong, there are few parts affected by suction, and the amount of slurry leaching is small.

(3) Subsequently, in the same manner as in the above-described second embodiment, in the first embodiment, the end of the honeycomb to which the slurry is not applied is directed downward, and the tip of the honeycomb is exposed by about 10 mm from the upper end of the elastic gripping jig (balloon). Hold it again. Steps 7 to 12 are performed. In the present invention, since the end portion of the honeycomb or a slightly lower portion thereof is gripped, even when the suction pressure is strong, there are few parts affected by suction, and the amount of slurry leaching is small.

  The present invention relates to a filter for collecting particulate matter contained in exhaust gas of a diesel engine or a gasoline engine, such as a catalytic filter (GPF) for capturing particulate matter in exhaust gas of a gasoline engine. It can be preferably used.

1: Honeycomb structure (carrier)
2: Elastic gripping jig (balloon)
4: Exposed end portion 5: Slurry immersion 6: Slurry liquid tank 7: Hood 8: Unpainted portion

Claims (7)

Exhaust gas purification in which a catalyst component is supported in a cell of a honeycomb carrier having a porous partition wall forming a plurality of cells and a porous outer skin part having a porosity of 30% or more and having open ends at the top and bottom A method for producing a catalyst, comprising:
A first step of holding an elastic gripping jig in contact with the outer peripheral portion of the honeycomb carrier and gripping the honeycomb carrier with an elastic body; and immersing the lower end of the honeycomb carrier in a slurry liquid bath containing a catalyst component; A second step of decompressing the inside of the cell by decompressing the space containing the slurry and sucking up the slurry liquid; a third step of lifting the honeycomb carrier impregnated with the catalyst component from the slurry liquid bath and reversing the slurry if necessary; The fourth step of air blowing from above the honeycomb carrier to cover the catalyst component in the cell, the fifth step of separating the elastic gripping jig from the honeycomb carrier, and drying the fired detached honeycomb carrier, followed by firing. And a sixth step of supporting the catalyst component,
In the honeycomb carrier holding step, the honeycomb carrier is held by the elastic holding jig so that the exposed length on the upper end side of the honeycomb in the space is within one third of the total length of the honeycomb from the upper end of the elastic body. Exhaust gas purifying catalyst characterized in that the honeycomb part affected by negative pressure is shortened in the next slurry liquid sucking process, and the exudation of catalyst slurry from the honeycomb outer skin is suppressed in the next slurry liquid sucking process. Manufacturing method. In the manufacturing method of the exhaust gas purification catalyst, in the first step of gripping the honeycomb carrier, the exposed length of the upper end of the elastic body with respect to the suction direction of the slurry liquid by the elastic gripping jig is In the space, the elastic body is held so that the upper end of the elastic body is within 1/3 of the total length of the honeycomb, and the catalyst component is coated in the cells of the honeycomb carrier by performing the second to fourth steps. After
The gripping position of the honeycomb carrier by the elastic body of the elastic gripping jig is changed so that the lower end becomes the upper end, and the gripping position of the honeycomb by the elastic gripping jig is the exposed length of the new upper end side of the honeycomb in the space. Is held by the elastic body so that the length is within 1/3 of the total length of the honeycomb from the upper end of the elastic body, and the new lower end of the honeycomb carrier is immersed again in the slurry liquid bath containing the catalyst component, and then the upper end of the honeycomb carrier is included. A seventh step in which the inside of the cell is depressurized by depressurizing the space to suck up the slurry liquid; an eighth step in which the honeycomb carrier impregnated with the catalyst component is lifted from the slurry liquid bath and reversed if necessary; The air is blown from above, and the ninth step of coating the catalyst component in the cell is repeated,
Thereafter, the method includes: a tenth step of separating the elastic holding jig from the honeycomb carrier; and an eleventh step of drying and firing the separated honeycomb carrier and supporting the catalyst component. The manufacturing method of the exhaust-gas purification catalyst as described.   The elastic gripping jig is gripped by the elastic body at a position where the upper end of the elastic body is within 1/10 of the total length of the honeycomb or within a position within 10 mm below the upper end of the honeycomb where the exposed length of the upper end of the honeycomb is shorter. The method for producing an exhaust gas purifying catalyst according to claim 1 or 2, wherein:   The method for manufacturing an exhaust gas purification catalyst according to any one of claims 1 to 3, wherein the honeycomb carrier has a skin portion with a porosity of 50 to 80%.   The method for producing an exhaust gas purification catalyst according to any one of claims 1 to 4, wherein the outer skin portion of the honeycomb carrier has an average pore diameter measured by a mercury porosimeter of 10 to 30 µm.   The cell of the honeycomb carrier has plugging portions at an opening end portion on an inlet end surface side and an opening end portion on an outlet end surface side, and the plugging portions are alternately arranged. The manufacturing method of the exhaust-gas purification catalyst in any one of 1-5. The said catalyst composition contains 1 or more types of noble metal elements chosen from Pt, Pd, and Rh, The manufacturing method of the exhaust gas purification catalyst in any one of Claims 1-6 characterized by the above-mentioned.