JP2018103106A - Method for producing exhaust gas purification catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an exhaust gas purification catalyst, upon wash coat to a honeycomb carrier, even if catalyst slurry is leached to an outer skin part and is firmly stuck with a grasping fixture, capable of performing the separation of the grasping fixture.SOLUTION: Provided is a method for producing an exhaust gas purification catalyst where a balloon-shaped supporting body in an elastic grasping fixture is expanded under pressure to grasp and fix the outer circumferential part of a honeycomb carrier, thereafter a slurry liquid including a catalyst component is fed from the edge face of the honeycomb carrier, in a state where the honeycomb carrier fed with the catalyst slurry is grasped with the balloon-shaped supporting body, an air flow is applied from the edge face of the honeycomb carrier fed with the catalyst slurry to coat the catalyst component at the inside of a cell, and, in a separation step in which the elastic grasping fixture is separated from the outer skin part of the honeycomb carrier stuck by the exuding of the catalyst slurry, the upper and lower edge faces or the circumferential part of the honeycomb carrier are fixed by sandwiching means, and subsequently, pressurization by the balloon-shaped supporting body is stopped and the grasping of the outer circumferential part of the honeycomb carrier is released to promote the separation between the honeycomb outer skin and the supporting body.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing an exhaust gas purification catalyst, and more particularly, when a catalyst slurry is leached into a skin portion and is firmly fixed to a gripping jig during wash coating on a honeycomb carrier, the gripping jig is separated. The present invention relates to a method for producing an exhaust gas purification catalyst that can be made.

  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 using diesel 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. And a honeycomb structure 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 flow rate of exhaust gas. 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 structure, that is, the DPF, the outer skin portion is made of a dense high-strength ceramic material.

  However, 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, a three-way catalyst (TWC: Three Way Catalyst) containing noble metals such as platinum, palladium, rhodium, etc., is used to purify exhaust gas from gasoline engines. 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 the honeycomb carrier is catalyzed with a catalyst composition such as TWC, a manufacturing method generally called a wash coat method is applied (see, for example, Patent Document 2).
Various methods have been proposed and implemented for the washcoat. After holding the intermediate position of the honeycomb carrier with the sandwiching means, a part of the lower part is immersed in a liquid bath and impregnated with the catalyst component-containing liquid. There is a method in which the support is pulled up from the slurry and inverted, and then the excess slurry is separated by air blowing to the support, and the entire support 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 structure 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. Catalyst slurry oozes out from the outer skin.

  The catalyst slurry leached from the outer skin part worked like an adhesive, and the honeycomb carrier gripped by the balloon support of the elastic gripping jig was fixed to the balloon, and it was difficult to separate. Even if sticking to the balloon is partially eliminated, as shown in Fig. 6 (upper right), the honeycomb is tilted, and with an automated device, impact is not achieved during tilting or in subsequent processes without proper positioning. In addition, the honeycomb may be damaged. In addition, if sticking to the balloon is not resolved, the sticking continues as shown in FIG. 6 (lower right), and it is necessary to apply a strong external force to separate them, and there is a risk of honeycomb damage such as cracks in the honeycomb outer skin. high.

  In Patent Document 6, the entire circumference of a cylindrical honeycomb carrier is covered with a balloon and pressurized with air, and then the catalyst is attached to the outside of the honeycomb carrier when the catalyst slurry is poured from above the inside of the honeycomb carrier to carry the catalyst. Means for suppressing this are described. However, the position where the catalyst adheres is particularly intense in the vicinity of both ends of the carrier, and there is no specific means for dealing with the state where the catalyst oozes out from the inside of the honeycomb carrier and adheres to the outer shell, thereby releasing the adhesion.

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 cell partition and the skin part and cracks occur. There is also a problem that is likely to occur. The honeycomb having cracks loses its function as a filter. Therefore, 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 partition walls and the outer skin portion of the cell are made of the same quality as described above, the outer skin portion will also be formed in a porous manner, and the catalyst slurry will leach into the outer skin portion when washing the catalyst slurry. It is as follows.

  Thus, a means suitable for GPF, which enables separation from the holding jig even if the catalyst slurry from the honeycomb skin portion leaches out, is desired, and can be stably and inexpensively applied to mass production. It is also desired that this is possible.

Republished 2013-172128 Special table 2003-506221 gazette JP-T-2015-528868 Japanese Patent Laid-Open No. 7-10650 Special table 2003-506221 gazette Japanese Utility Model Publication No. 2-45139

  In view of such circumstances, an object of the present invention is to provide an exhaust that enables the gripping jig to be separated even when the catalyst slurry is leached into the outer skin portion and firmly fixed to the gripping jig during the wash coating on the honeycomb carrier. The object is to provide a method for producing a gas purification catalyst.

  As a result of intensive research to solve the above problems, the inventors of the present invention supplied air to a balloon-like support of an elastic gripping jig to expand it to grip the honeycomb carrier, and wash the catalyst slurry to the honeycomb with a wash coat. After coating the cells of the carrier, in the honeycomb separation step, with the sandwiching means sandwiching and fixing the upper and lower end surfaces or the circumferential portion of the honeycomb, the balloon-like support is no longer pressurized and shrunk, whereby the catalyst slurry It has been found that the separation of the fixed honeycomb outer shell and the support is promoted by the leaching of the substrate, and the present invention has been completed.

That is, according to the first invention of the present invention, the porous partition wall forming a plurality of cells, and the end face in which at least a part of the cells constituted by the partition walls are opened, and the porosity is 30% or more. A method for producing an exhaust gas purification catalyst in which a catalyst component is supported by a washcoat method in a honeycomb carrier cell composed of a porous outer skin part,
After pressing and expanding the balloon-shaped support of the elastic gripping jig to grip and fix the outer periphery of the honeycomb carrier, a slurry liquid containing a catalyst component is supplied from the end surface of the honeycomb carrier, and the honeycomb carrier to which the catalyst slurry is supplied While gripping with a balloon-shaped support, air flow is applied from the end face of the honeycomb carrier to which the catalyst slurry is supplied to cover the catalyst components in the cells, and elastic gripping is performed from the outer skin portion of the honeycomb carrier that is fixed by the catalyst slurry leaching. The honeycomb carrier separated through the separation step of separating the jig is dried and then fired to carry the catalyst component.
In the separation step, after fixing the upper and lower end surfaces or the circumferential portion of the honeycomb carrier with clamping means, the pressure applied by the balloon-like support is released to release the gripping of the outer circumferential portion of the honeycomb carrier, thereby supporting the honeycomb outer skin and the support. Provided is a method for producing an exhaust gas purifying catalyst characterized by promoting separation from a body.

  According to a second aspect of the present invention, in the first aspect, in the separation step, at least one of the clamping means and the elastic gripping jig is rotated in the circumferential direction of the honeycomb carrier. A method for producing an exhaust gas purification catalyst is provided.

  Further, according to the third invention of the present invention, in the first or second invention, in the separation step, the clamping means is located on at least one of the upper end side or the lower end surface side in the axial direction of the honeycomb carrier, There is provided a method for producing an exhaust gas purifying catalyst, characterized in that the exhaust gas purifying catalyst is fixed toward an end face facing the clamping means.

  According to a fourth aspect of the present invention, in the first or second aspect, the sandwiching means is a balloon sandwiching body arranged at equal intervals on the outer circumferential surface of the honeycomb carrier, and the elastic There is provided a method for producing an exhaust gas purification catalyst characterized in that it is made of a material harder than a grasping balloon, has a narrow contact area with a honeycomb carrier, and has high peelability from the outer peripheral surface of the honeycomb.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the honeycomb carrier has an outer shell portion with a porosity of 50 to 80%. A method for producing a catalyst is provided.

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

  According to the seventh invention of the present invention, in any one of the first to sixth inventions, the cells of the honeycomb carrier are plugged at the opening end on the inlet end face side and the opening end on the outlet end face side. There is provided a method for producing an exhaust gas purifying catalyst, characterized in that the plugging portions are alternately arranged.

  Furthermore, according to an eighth invention of the present invention, in any one of the first to seventh inventions, the catalyst composition contains one or more precious 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 leached from the outer skin portion, and the balloon of the elastic gripping jig is fixed to the honeycomb outer skin. However, it becomes easy to separate by a simple operation of fixing the honeycomb by the sandwiching means, and the honeycomb carrier is not easily inclined at the time of separation, so that the process can be smoothly shifted to the subsequent processing step, and the productivity is improved.

It is explanatory drawing which showed typically the essential process of the washcoat method to which this invention is applied. It is the perspective view which showed the external appearance of the honeycomb carrier typically. FIG. 4 is an explanatory view of an embodiment schematically showing a step of separating a honeycomb carrier fixed to a support using a clamping means when manufacturing an exhaust gas purification catalyst according to the present invention. FIG. 5 is an explanatory view of another embodiment schematically showing a step of separating a honeycomb carrier fixed to a support using a clamping means when manufacturing an exhaust gas purification catalyst according to the present invention. FIG. 4 is an explanatory view of an embodiment schematically showing a step of separating a honeycomb carrier fixed to a support using a balloon as a sandwiching means when manufacturing an exhaust gas purification catalyst according to the present invention. FIG. 2 is an explanatory view schematically showing a state in which part of the sticking is eliminated in the separation step after the catalyst slurry is stuck to the honeycomb carrier, and a state in which the support is not separated from the honeycomb carrier and is continuously stuck.

  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 A honeycomb structure (also referred to as a honeycomb carrier) used in the present invention includes a porous partition wall forming a plurality of cells and a porous skin having a porosity of 30% or more as shown in FIG. 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 leaching into the outer skin part during production. 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. The “average pore diameter” referred to here 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.

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 includes a porous partition wall forming a plurality of cells, and an end face in which at least a part of the cells constituted by the partition walls is open, A method for producing an exhaust gas purification catalyst in which a catalyst component is supported by a wash coat method in a cell of a honeycomb carrier composed of a porous outer skin portion having a rate of 30% or more,
After pressing and expanding the balloon-shaped support of the elastic gripping jig to grip and fix the outer periphery of the honeycomb carrier, a slurry liquid containing a catalyst component is supplied from the end surface of the honeycomb carrier, and the honeycomb carrier to which the catalyst slurry is supplied While gripping with a balloon-shaped support, air flow is applied from the end face of the honeycomb carrier to which the catalyst slurry is supplied to cover the catalyst components in the cells, and elastic gripping is performed from the outer skin portion of the honeycomb carrier that is fixed by the catalyst slurry leaching. The honeycomb carrier separated through the separation step of separating the jig is dried and then fired to carry the catalyst component.
In the separation step, after fixing the upper and lower end surfaces or the circumferential portion of the honeycomb carrier with clamping means, the pressure applied by the balloon-like support is released to release the gripping of the outer circumferential portion of the honeycomb carrier, thereby supporting the honeycomb outer skin and the support. It is characterized by promoting separation from the body.

  In the washcoat method of the present invention, the outer peripheral portion of the honeycomb carrier is gripped by the balloon-shaped support of the elastic gripping jig, and then a slurry liquid containing a catalyst component is supplied from the end surface of the honeycomb carrier. The present invention provides a method of separating the honeycomb carrier fixed by the catalyst slurry leached into the outer shell and the elastic gripping jig by a specific means by a series of steps of coating the catalyst component in the cell by applying an air flow.

  Next, the method of the present invention will be described in detail for each representative manufacturing process.

(1) Holding of the honeycomb carrier First, as shown in FIG. 1A, air is supplied to the inside of the balloon-shaped support 2 of the elastic holding jig 3, and the outer periphery of the honeycomb carrier 1 is held by the balloon. .

  The elastic gripping jig uses, for example, a hollow donut-shaped member as a support, which is an elastic balloon that allows air to be taken in and out like a balloon, a float, or a tire tube. 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 (robot arm). These can control the gripping force to the honeycomb with sufficient adhesion by adjusting the contact and pressure of air.

  By gripping with such a balloon, it is possible to prevent the honeycomb carrier from being damaged by the gripping force even if it is a brittle carrier such as a GPF honeycomb carrier. A balloon similar to this may also be used in the clamping means in the separation step described later.

(2) Supply of Catalyst Slurry Solution by Depressurization Next, as shown in the center of FIG. 1, slurry containing a catalyst component is supplied to the honeycomb carrier while holding the honeycomb carrier with the balloon of the elastic holding jig. The method of supplying such a catalyst slurry is not particularly limited, and it may be supplied from either the upper end or the lower end of the honeycomb as shown in two directions by arrows (1) in FIG.

A predetermined amount of catalyst slurry is stored in the catalyst slurry liquid tank. Each time the honeycomb is immersed, the catalyst slurry liquid decreases, but the decrease 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 catalyst slurry containing an additive such as a thickener as necessary. The slurry containing such a component is sticky because it is in the form of a slurry, which causes sticking to the balloon.

  The catalyst slurry is not limited by the type and particle size of the inorganic particles, but it is preferable that at least a part of the catalyst slurry can penetrate into the pores of the partition walls. It is preferable that the particle diameter D90 when the cumulative distribution from the diameter side becomes 90% is 5 μm or less, such that it is finely divided by a ball mill or the like, and 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.

Here, the slurry liquid may be supplied from the lower end opening of the honeycomb carrier to the upper end side or from the upper end opening of the honeycomb carrier to the lower end side.
Also, the slurry liquid supply means may be suction from the lower end or supply by gravity descending from the upper end, and if necessary, a pressure intended for filling the slurry liquid into the cell may be applied. good.

  In addition, when the porosity of the honeycomb carrier shell is remarkably high, the viscosity of the catalyst slurry is low, or the particle size of the inorganic fine particles in the catalyst slurry is remarkably low, and depending on the combination of these conditions, At the stage of supply, the catalyst slurry may ooze out from the outer skin portion.

(3) Application of airflow: air blow Next, as shown on the right side of FIG. 1, that is, as indicated by an arrow (2), the honeycomb carrier 1 supplied with the catalyst slurry was covered with a hood on the elastic body (balloon) 2 as necessary. Thereafter, air blow is applied from one end face of the carrier 1 to remove the excess catalyst slurry, spread the catalyst slurry on the cell wall surface, and fill the catalyst slurry into the cell wall.
The honeycomb carrier impregnated with the catalyst component is pulled up from the catalyst slurry liquid tank and reversed as necessary.

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 catalyst slurry is sufficiently sucked into the cell, it can proceed to the next step as it is.
When the air is blown as it is without reversing after the catalyst slurry is sucked, a portion not covered with the catalyst slurry may remain. If the reversing operation is performed to operate and reverse the drive part of the elastic gripping jig, the unpainted portion of the catalyst slurry can be reduced.

  In GPF honeycombs in which resin is not impregnated into the outer skin, the catalyst slurry oozes out of the honeycomb outer shell when air blow is performed. When the catalyst slurry liquid is sucked, the amount of the liquid stays in the cell and does not reach the pores of the outer wall, but when air is blown into the honeycomb carrier, the pressure (air flow rate) of the cell This is because the liquid adhering to the inner surface is pushed out from the pores and easily oozes out from the outer wall. The soaking of the catalyst slurry from the honeycomb outer skin becomes larger when the air blow pressure (air flow rate) is strong. Then, the balloon of the elastic gripping jig is fixed to the honeycomb outer skin by the soaking of the catalyst slurry.

(4) Separation of elastic gripping jig and honeycomb Conventionally, when the balloon of the elastic gripping jig is fixed to the honeycomb outer shell, it is difficult to separate the balloon as shown in FIG. Even if the sticking to the balloon is partially eliminated, the honeycomb is tilted, and with an automated device, the honeycomb cannot be placed at an appropriate position on the device, and the honeycomb may be damaged during or after the tilt. There is.

  Therefore, in the present invention, in the separation step, after fixing the upper and lower end surfaces or the circumferential portion of the honeycomb carrier with clamping means, the pressure applied by the balloon-shaped support is released to release the gripping of the outer circumferential portion of the honeycomb carrier. , To promote separation of the honeycomb skin and the support.

  One clamping method at this time is to fix the axial direction or the circumferential direction with respect to the honeycomb by the clamping means. In other words, sandwiching means are placed on the top and bottom of the honeycomb, and the upper and lower end surfaces are fixed at the same time. The upper end surface is fixed and moved from the lower end surface. Clamping or placing a clamping means on the side surface of the honeycomb and clamping toward the center. The pinching means needs to have a certain hardness in order to exert a pinching force, but in order to prevent damage to the honeycomb outer skin, the fixing portion is preferably made of a balloon, silicon rubber, or the like.

  Among these, in the separation step, it is preferable that the sandwiching means is located on at least one of the upper end side or the lower end face side in the axial direction of the honeycomb carrier and is fixed toward the end face facing the sandwiching means. When the honeycomb is large and heavy, the gripping tends to become unstable, so that the inclination and deviation are likely to increase after the coating operation. In the present invention, even in such a case, the inclination and deviation can be easily corrected by sandwiching the upper and lower ends of the honeycomb.

  As another clamping method, there can be mentioned a method of fixing the honeycomb side surface by a robot arm. In this case, the holding means is a balloon holding body arranged at equal intervals on the outer circumferential surface of the honeycomb carrier, and is made of a material harder than the elastic gripping balloon or is in contact with the honeycomb carrier. It is preferable that the area is small and the peelability from the outer peripheral surface of the honeycomb is high. For example, the contact area with the honeycomb carrier is preferably 0.05 to 0.9 times, more preferably 0.1 to 0.5 times that of the balloon for elastic gripping. Further, the sandwiched body may be sandwiched so as to make one round of the circumferential shape of the honeycomb carrier, but may be in the form of two or more arms.

  After fixing the honeycomb as described above, the pressure applied by the balloon-shaped support is released to release the gripping of the outer peripheral portion of the honeycomb carrier, thereby promoting separation of the honeycomb skin and the support.

  If the sticking to the balloon is still not resolved, it is necessary to apply a stronger external force to separate them. In the separation step, at least one of the clamping means and the elastic gripping jig is rotated in the circumferential direction of the honeycomb carrier. . When the sandwiching means is positioned on at least one of the upper end side or the lower end surface side in the axial direction of the honeycomb carrier and is fixed toward the end face facing the sandwiching means, the elastic gripping jig that is fixed is more Rotate.

  On the other hand, when the sandwiching means is a balloon sandwiching body arranged at equal intervals on the outer circumferential surface of the honeycomb carrier, either the sandwiching means or the elastic gripping jig can be rotated in a relatively opposite direction. That's fine. However, since the elastic gripping jig is fixed, it is more effective to rotate the clamping means. For this purpose, the balloon holding body is preferably made of a material harder than the elastic gripping balloon, or has a narrow contact area with the honeycomb carrier, so that the peelability from the outer peripheral surface of the honeycomb is improved.

In the present invention, how to rotate the gripping portion or the fixing portion, the rotating means and the rotating condition are not particularly limited as long as the honeycomb outer shell is thin and GPF is not broken by external force.
The direction of rotation in the separation step is arbitrary and may be either left or right. However, sudden rotation with high torque may damage the outer skin, so it is desirable to work while confirming the degree of fixation, such as gradually increasing it.

  Thereafter, after confirming that the honeycomb sticking has been eliminated, the holding means is removed from the fixing portion, and the elastic gripping jig is separated from the honeycomb carrier.

(5) Drying and firing Finally, the honeycomb carrier is dried and then fired to carry the catalyst component. Here, the conditions for drying and firing are not particularly limited. Drying can be performed, for example, at 100 to 200 ° C. for 0.1 to 3 hours, and firing can be performed, for example, at 400 to 600 ° C. for 0.5 to 5 hours in an oxidizing atmosphere.

  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 and is reversed if necessary. Then, the honeycomb slurry is spread in the cell by air blow, and a honeycomb catalyst is obtained after drying and firing.

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

<Embodiment 1>
As a cordierite wall flow honeycomb structure, a honeycomb carrier for GPF (for example, a diameter of 100 to 200 mm, a length of 150 to 250 mm) is used, and the honeycomb carrier is supported by a balloon-like support of an elastic gripping jig on the outer periphery of the honeycomb carrier. Grip.
The catalyst slurry liquid tank is filled with the catalyst slurry liquid so that the liquid volume is constant. As the catalyst slurry liquid, a slurry obtained by slurrying a three-way catalyst (TWC) component in which noble metals such as Pt, Pd, and Rh are supported on alumina is used.

The honeycomb gripped by the support of the jig is dipped in the catalyst slurry liquid tank from its lower end. The lower end position of the honeycomb immersed in the catalyst slurry liquid tank is not particularly limited, but is about 5 to 30 mm.
Next, the airtight space of the jig is reduced to a high pressure by a pressure reducing device. The catalyst slurry flows into the cell from the lower end of the honeycomb, and the catalyst slurry moves toward the upper end of the honeycomb while coating the inner wall of the cell with the catalyst slurry. At this time, about 1/3 of the total length of the honeycomb is left uncoated.
In this way, when decompression is applied to the honeycomb cells and the suction pressure is high, the catalyst slurry is leached above the portion affected by the suction, that is, above the support of the jig.

Next, the honeycomb that has sucked the catalyst slurry is pulled up from the catalyst slurry liquid tank and inverted. Suction may be continued when the catalyst slurry liquid tank is pulled up. Thereafter, by reversing, the portion where the honeycomb cell is left uncoated is directed downward, and the portion where the cell is coated with the catalyst slurry is directed upward.
In this state, a hood is placed on the portion of the honeycomb cell where the catalyst 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 blow apparatus connected to the hood, and the catalyst slurry in the cell flows downward. At this time, even if the cell skin is in a state of being pressurized from the outside, the catalyst slurry oozes out of the skin.

As shown in FIG. 3, the honeycomb after the slurry coating is fixed to the elastic support by the slurry leaching.
Therefore, in the present embodiment, as shown in FIG. 3 (left), the sandwiching means is brought close to the top and bottom of the honeycomb, and the end portions of the honeycomb are fixed by the sandwiching means. A balloon or silicon rubber or the like is mounted on the contact surface of the sandwiching means with the honeycomb. Thereafter, as shown in FIG. 3 (right), air is extracted from the balloon that has been gripped, and the pressure applied to the honeycomb is released. When the air escapes, the balance of the balloon is lost on the left and right with the honeycomb, and the honeycomb is inclined in the past. However, in this embodiment, since the balloon is fixed from above and below, the inclination can be suppressed.
Thereafter, the separated 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 2>
In the present embodiment, the catalyst slurry is applied in the cell by the same operation as in the first embodiment, but a case where a strong air blow is performed will be described.
When a strong air blow is performed, a large amount of the catalyst slurry oozes into the honeycomb outer skin, and adhesion to the balloon becomes stronger.

Therefore, also in this embodiment, as shown in FIG. 4 (left), the sandwiching means is approached from above and below the honeycomb, and the end portion of the honeycomb is brought into contact with the sandwiching means and fixed with sufficient force. A balloon or silicon rubber or the like is mounted on the contact surface of the sandwiching means with the honeycomb. Thereafter, as shown in FIG. 4 (middle), the balloon is rotated. At the beginning of rotation, reduce the rotational force and operate carefully while checking the degree of sticking. At this time, if the sandwiching force at the end of the honeycomb is small, it is difficult to transmit a sufficient rotational force to the honeycomb. When the rotational force exceeds the adhering force, the balloon is pulled away from the honeycomb as shown in FIG. 4 (right).
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>
In the present embodiment, a case where the catalyst slurry is applied in the cell by performing a strong air blow by the same operation as in the second embodiment will be described.
When a strong air blow is performed, a large amount of the catalyst slurry oozes into the honeycomb outer skin, and adhesion to the balloon becomes stronger.

Therefore, in this embodiment, as shown in FIG. 5 (left), the sandwiching means with the balloon as the sandwiching means is brought close to the side surface 2 direction at the lower end of the honeycomb, and the honeycomb end is fixed with the balloon as the sandwiching means. The balloon mounted on the contact surface of the sandwiching means with the honeycomb has a contact area smaller than that of the grasping balloon (for example, two arm-shaped sandwiching bodies having a contact area of 0. 1 times). Thereafter, the balloon is rotated as shown in FIG. 5 (right). At the beginning of rotation, reduce the rotational force and operate carefully while checking the degree of sticking. When the rotational force exceeds the fixing force, the balloon is pulled away 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.

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

1: Honeycomb carrier 2: Grasping balloon 3: Elastic gripping jig 5: Permeation of catalyst slurry 6: Catalyst slurry liquid tanks 7, 7 ': Clamping means

Claims (8)

In a cell of a honeycomb carrier comprising a porous partition wall forming a plurality of cells, and a porous skin portion having an end face where at least a part of the cells constituted by the partition wall is open and having a porosity of 30% or more In addition, a method for producing an exhaust gas purification catalyst carrying a catalyst component by a wash coat method,
After pressing and expanding the balloon-like support of the elastic gripping jig to grip and fix the outer periphery of the honeycomb carrier,
A slurry liquid containing a catalyst component is supplied from the end face of the honeycomb carrier, and the honeycomb carrier to which the catalyst slurry is supplied is held by a balloon-like support, and an air stream is applied to the cell from the end face of the honeycomb carrier to which the catalyst slurry is supplied. The catalyst component is coated inside,
The honeycomb carrier separated through the separation step of separating the elastic gripping jig from the outer skin portion of the honeycomb carrier fixed by the leaching of the catalyst slurry is dried and then fired to carry the catalyst component.
In the separation step, after fixing the upper and lower end surfaces or the circumferential portion of the honeycomb carrier with clamping means, the pressure applied by the balloon-like support is released to release the gripping of the outer circumferential portion of the honeycomb carrier, thereby supporting the honeycomb outer skin and the support. A method for producing an exhaust gas purification catalyst, characterized by promoting separation from a body.   The method for manufacturing an exhaust gas purification catalyst according to claim 1, wherein in the separation step, at least one of the sandwiching means and the elastic gripping jig is rotated in the circumferential direction of the honeycomb carrier.   The exhaust gas purification according to claim 1 or 2, wherein the sandwiching means is located at least one of an upper end side or a lower end face side in the axial direction of the honeycomb carrier and is fixed toward an end face facing the sandwiching means. A method for producing a catalyst.   The sandwiching means is a balloon sandwiching body arranged at equal intervals on the outer circumferential surface of the honeycomb carrier and is made of a material harder than the elastic gripping balloon or has a narrow contact area with the honeycomb carrier. The method for producing an exhaust gas purification catalyst according to claim 1 or 2, wherein the peelability from the outer peripheral surface of the honeycomb is high.   The method for manufacturing an exhaust gas purification catalyst according to claim 1, 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 5, 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 1-6. 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 1-7 characterized by the above-mentioned.

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