JP2017176939A - Honeycomb catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb catalyst that has catalyst layers formed by using a plurality of catalyst materials together and that shows excellent catalytic performance compared to a honeycomb catalyst having a mixed catalyst layer formed by mixing a conventional plurality of catalyst materials.SOLUTION: Provided is a honeycomb catalyst comprising a honeycomb substrate and two or more kinds of catalyst layers arranged separated in a direction along an inner periphery of each cell of the honeycomb substrate.SELECTED DRAWING: None

Description

  The present invention relates to a honeycomb catalyst in which two or more types of catalyst layers are arranged on the inner wall of each cell of a honeycomb substrate.

  Examples of exhaust gas purification catalysts used in automobiles include, for example, a honeycomb-shaped substrate including a honeycomb-shaped substrate having a plurality of through holes and a catalyst layer made of a catalyst material applied to the inner wall of a cell of the honeycomb-shaped substrate. Catalysts are known. In the catalyst layer of such a honeycomb-shaped catalyst, conventionally, one type of catalyst material has been used, but in recent years, a plurality of catalyst materials have been used in combination for improving the catalyst performance. However, a honeycomb catalyst including a mixed catalyst layer formed by mixing a plurality of catalyst materials has not always had sufficient catalyst performance.

  In addition, as a catalyst layer using a plurality of catalyst materials in combination, a plurality of catalyst layers having different compositions are separated in the exhaust gas flow direction (long axis direction of the cell), A multi-layered catalyst layer is known that is disposed separately in a direction (short axis direction or radial direction of a cell) perpendicular to the flow direction of exhaust gas.

  For example, in Japanese Patent Application Laid-Open No. 2007-268484 (Patent Document 1), a plurality of slurries have different distribution patterns in at least one of the axial direction and the radial direction of the honeycomb substrate on the surface of the cell partition walls of the honeycomb substrate. A plurality of slurries are partitioned and filled into a cylindrical coating jig so as to be substantially the same pattern as the distribution pattern, and the coating jig is brought into contact with one end surface of the honeycomb substrate. And a coating method in which slurry is introduced into the cell passage from the end face of the coating jig.

  In addition, International Publication No. 2010/114132 (Patent Document 2) includes an apparatus for producing an exhaust gas purification catalyst including a nozzle provided with a plurality of discharge ports and a fluid supply device connected to the nozzle. Have been described. Patent Document 2 discloses that a fluid containing a catalyst layer material is discharged from the nozzle onto one end face of a monolith honeycomb substrate to form a catalyst layer, and then a fluid containing a different catalyst layer material is used. By discharging the nozzle from the nozzle to the other end surface of the monolith honeycomb substrate to form different catalyst layers, an exhaust gas purifying catalyst having catalyst layers having different compositions at the upstream and downstream portions of the monolith honeycomb substrate is obtained. It is described that

  Further, in JP 2010-133332 A (Patent Document 3), a light emitting material coating layer and an exhaust gas purifying catalyst layer are separately applied to one honeycomb carrier, whereby light is emitted upstream or downstream of the exhaust. It is described that a catalyst device in which an exhaust gas purifying catalyst is arranged on the heating element, downstream side or upstream side is obtained.

  In addition, JP-A-2014-188466 (Patent Document 4) discloses a surface collection layer having a plurality of pores by applying fine raw material particles to the surface of the partition wall on the inlet cell side of the honeycomb structure portion and firing it. A method for manufacturing an exhaust gas purification filter is described in which a slurry containing an exhaust gas purification catalyst is applied to the partition wall surface on the outlet cell side of the honeycomb structure portion and dried to support the exhaust gas purification catalyst. Yes.

  Further, JP-A-2006-2534 (Patent Document 5) discloses a precursor of a particulate matter oxidation catalyst from the syringe tip to the partition wall surface on the sealing end side of the gas inflow passage of the wall-through filter base. A method for producing an exhaust gas purifying catalyst is described in which a catalyst slurry is press-fitted, and further, a catalyst slurry that is a precursor of a NOx purifying catalyst is press-fitted into the surface of the partition wall on the opening end side of the gas inflow passage, and then dried and fired. ing.

  However, the honeycomb catalyst obtained by the methods described in Patent Documents 1 to 2, and 4 to 5 and the catalyst device described in Patent Document 3 have a plurality of catalyst layers in the major axis direction or radial direction of cells of the honeycomb substrate. A honeycomb catalyst in which a plurality of catalyst layers are arranged in a direction along the inner periphery of the cell has not been known.

JP 2007-268484 A International Publication No. 2010/114132 JP 2010-133332 A JP 2014-188466 A Japanese Patent Laying-Open No. 2006-2534

  The present invention has been made in view of the above-described problems of the prior art, and includes a catalyst layer in which a plurality of catalyst materials are used in combination, and a mixed catalyst layer formed by mixing a plurality of conventional catalyst materials. An object of the present invention is to provide a honeycomb-shaped catalyst exhibiting superior catalyst performance as compared with the provided honeycomb-shaped catalyst.

  As a result of intensive studies to achieve the above object, the present inventors apply a plurality of catalyst materials to the inner wall of each cell of the honeycomb substrate in a state separated in the direction along the inner periphery of the cell. Has found that a honeycomb-shaped catalyst exhibiting superior catalytic performance compared to a honeycomb-shaped catalyst having a mixed catalyst layer formed by mixing a plurality of conventional catalyst materials can be obtained, and the present invention has been completed. .

  That is, the honeycomb-shaped catalyst of the present invention includes a honeycomb-shaped base material, and two or more types of catalyst layers arranged separately on the inner wall of each cell of the honeycomb-shaped base material in the direction along the inner periphery of the cell. It is characterized by having.

  In the honeycomb-shaped catalyst of the present invention, it is preferable that the two or more types of catalyst layers have a uniform composition in the major axis direction of the cell. The two or more types of catalyst layers may be a combination of a rhodium-containing catalyst layer and a palladium-containing catalyst layer, a combination of a rhodium-containing catalyst layer and a platinum-containing catalyst layer, a rhodium-containing catalyst layer, A combination of a catalyst layer containing ceria, a combination of a catalyst layer containing rhodium and a catalyst layer containing iron oxide, a combination of a catalyst layer containing ceria and a catalyst layer containing iron oxide, a catalyst layer containing alumina Combination of catalyst layer containing iron oxide, combination of catalyst layer containing titania and catalyst layer containing alumina, combination of catalyst layer containing noble metal and catalyst layer containing silica, catalyst layer containing noble metal and zeolite A combination of a catalyst layer containing a catalyst and a combination of a catalyst layer containing a basic material and a catalyst layer containing a noble metal It preferably contains one combination even without.

  The reason why the honeycomb catalyst of the present invention exhibits superior catalyst performance as compared with a honeycomb catalyst having a mixed catalyst layer formed by mixing a plurality of conventional catalyst materials is not necessarily clear. They guess as follows. That is, in a mixed catalyst layer formed by mixing a plurality of conventional catalyst materials, a plurality of catalyst materials coexist in close proximity to each other, so that the catalyst materials are diffused and dissolved by high-temperature oxidation / reduction heat treatment.・ Reaction and sintering (grain growth) impedes the performance of each catalyst material, and it is assumed that sufficient catalyst performance is not exhibited. On the other hand, in the honeycomb-shaped catalyst of the present invention, two or more kinds of catalyst layers are separately disposed on the inner wall of each cell of the honeycomb-shaped base material in the direction along the inner periphery of the cell. Even if high temperature heat treatment is applied, the catalyst material is less likely to diffuse, dissolve, react, and sinter (grain growth), and the performance of each catalyst material is fully expressed. As a result, the honeycomb catalyst of the present invention is presumed to exhibit superior catalyst performance as compared with a honeycomb catalyst having a mixed catalyst layer formed by mixing a plurality of conventional catalyst materials.

  According to the present invention, it has a catalyst layer using a plurality of catalyst materials in combination, and exhibits superior catalyst performance compared to a honeycomb catalyst having a mixed catalyst layer formed by mixing a plurality of conventional catalyst materials. A honeycomb catalyst can be obtained.

FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. FIG. 2 is a schematic diagram of a cross section perpendicular to the long axis direction of a cell, showing an example of a preferred embodiment of the honeycomb catalyst of the present invention. It is a graph which shows the relationship between the shear rate and the viscosity of the slurry obtained in Preparation Examples 2, 4, and 5. It is a schematic diagram of the cross section perpendicular | vertical to the major axis direction of a cell which shows the honeycomb catalyst provided with the separation coat catalyst layer produced in Examples 1-2. 2 is a schematic longitudinal sectional view of a honeycomb-shaped catalyst manufacturing apparatus used in Example 1 and Comparative Example 1. FIG. In Example 1, it is a schematic longitudinal cross-sectional view of the manufacturing apparatus of a honeycomb-shaped catalyst which shows the state by which FZ slurry was apply | coated in the cell of the honeycomb-shaped base material. In Example 1, it is a schematic longitudinal cross-sectional view of the manufacturing apparatus of a honeycomb-shaped catalyst which shows the state which inserted the syringe again after forming FZ layer in the cell of a honeycomb-shaped base material. In Example 1, it is a schematic longitudinal cross-sectional view of the manufacturing apparatus of a honeycomb-shaped catalyst which shows the state by which Rh / alumina slurry was apply | coated in the cell of the honeycomb-shaped base material. It is a schematic diagram of a cross section perpendicular | vertical to the major axis direction of a cell which shows the honeycomb catalyst provided with the mixed catalyst layer produced in the comparative examples 1 and 3. FIG. 6 is a graph showing the relationship between the NO and CO purification rates of the honeycomb-shaped catalysts obtained in Example 1 and Comparative Example 1 and the catalyst-containing gas temperature. It is a model perspective view of the test piece used by the X-ray-diffraction measurement of the catalyst layer. It is a graph which shows the X-ray-diffraction pattern of each catalyst layer after a heat test (1). 6 is a schematic diagram of a cross section perpendicular to the major axis direction of a cell, showing a honeycomb catalyst including a laminated catalyst layer produced in Comparative Example 2. FIG.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  The honeycomb-shaped catalyst of the present invention includes a honeycomb-shaped base material, and two or more types of catalyst layers arranged separately in the direction along the inner periphery of the cell on the inner wall of each cell of the honeycomb-shaped base material. It is what.

(Honeycomb substrate)
The honeycomb substrate used in the present invention is not particularly limited as long as it has a large number of cells (gas passages) partitioned by partition walls. Moreover, there is no restriction | limiting in particular as a cross-sectional shape of the cell of the direction perpendicular | vertical to the major axis direction (gas flow direction) of a cell, For example, square shape (preferably regular square shape), hexagon shape (preferably regular hexagon shape) And the like (preferably regular polygonal shape), circular shape, elliptical shape and the like.

  The material of such a honeycomb substrate is not particularly limited, and examples thereof include cordierite, silicon carbide, mullite, alumina, aluminum titanate, silicon nitride, stainless steel, 20% Cr-5% Al alloy stainless steel, and the like. Can be mentioned. In particular, when the honeycomb catalyst of the present invention is used as an exhaust gas purification catalyst for automobiles, a cordierite honeycomb substrate and a stainless steel foil substrate are preferable.

(Catalyst layer)
The catalyst material constituting the catalyst layer used in the present invention is not particularly limited. For example, noble metals (rhodium (Rh), palladium (Pd), platinum (Pt), etc.), basic materials (barium (Ba), etc.) , Oxide carriers (alumina, zirconia, silica, titania, rare earth oxides (for example, ceria, lanthanum oxide), transition metal oxides (for example, iron oxide), and complex oxides (for example, ceria- Zirconia composite oxide, zeolite) and the like.

  In the honeycomb-shaped catalyst of the present invention, two or more types of catalyst layers formed by using two or more types of such catalyst materials independently are provided on the inner wall of each cell of the honeycomb-shaped substrate. It is arrange | positioned in the state isolate | separated in the inner peripheral direction. The combination of two or more kinds of catalyst materials (catalyst layers) according to the present invention is not particularly limited. However, when the catalyst materials are mixed, diffusion, solid solution, reaction, and sintering of the catalyst material by high-temperature oxidation / reduction heat treatment. A combination of a catalyst material (catalyst layer made of the catalyst material) in which the catalyst performance is not sufficiently exhibited due to the occurrence of (granular growth) or the like, due to a decrease in active site, specific surface area, or melting point, is preferable, and contains rhodium (Rh) Combination of catalyst material (catalyst layer) and catalyst material (catalyst layer) containing palladium (Pd), catalyst material (catalyst layer) containing rhodium (Rh) and catalyst material (catalyst layer) containing platinum (Pt) A combination of a catalyst material (catalyst layer) containing rhodium (Rh) and a catalyst material (catalyst layer) containing ceria, a catalyst material (catalyst layer) containing rhodium (Rh) And catalyst material (catalyst layer) containing iron oxide, catalyst material containing ceria (catalyst layer) and catalyst material containing iron oxide (catalyst layer), catalyst material containing alumina (catalyst layer) And a combination of a catalyst material (catalyst layer) containing iron oxide and a combination of a catalyst material (catalyst layer) containing titania and a catalyst material (catalyst layer) containing alumina. The combination of these catalyst materials is used independently, and when two or more types of catalyst layers separated in the inner circumferential direction of the cell are formed, the catalyst material can be diffused even when subjected to high temperature heat treatment for oxidation / reduction.・ Solid solution / reaction / sintering (grain growth) is less likely to occur, and the reduction of active sites, specific surface area, and melting point is suppressed, and excellent catalytic performance is achieved compared to the case of mixing.

  In addition, as a combination of two or more kinds of catalyst materials (catalyst layers) according to the present invention, a combination of catalyst materials that easily cause coking when mixed with the catalyst materials is preferable, and a catalyst material containing a noble metal (catalyst layer) and A combination of a catalyst material containing silica (catalyst layer) and a combination of a catalyst material containing noble metal (catalyst layer) and a catalyst material containing zeolite (catalyst layer) are more preferred. The combination of these catalyst materials is used independently, and when two or more catalyst layers separated in the inner circumferential direction of the cell are formed, coking is less likely to occur and is superior to the case of mixing. Catalytic performance (for example, hydrocarbon (HC) adsorption ability) is developed.

  Further, as a combination of two or more kinds of catalyst materials (catalyst layers) according to the present invention, a combination of catalyst materials that are likely to cause diffusion, movement and reaction when the catalyst materials are mixed is also preferable. A combination of the catalyst material containing (catalyst layer) and the catalyst material containing noble metal (catalyst layer) is more preferred. The combination of these catalyst materials is used independently, and when two or more types of catalyst layers separated in the inner circumferential direction of the cell are formed, the diffusion, movement and reaction of the catalyst materials are less likely to occur. The catalyst performance (for example, NOx adsorption ability and NOx purification performance) superior to that of the case is exhibited.

(Structure of honeycomb catalyst)
The honeycomb-shaped catalyst of the present invention includes the honeycomb-shaped base material, and two or more types of catalyst layers arranged separately on the inner wall of each cell of the honeycomb-shaped base material in the inner circumferential direction of the cell. Is. 1A to 1L are schematic views of a cross section perpendicular to the major axis direction (gas flow direction) of a cell, showing an example of a preferred embodiment of such a honeycomb catalyst of the present invention. By disposing two or more types of catalyst layers separately on the inner wall of each cell of the honeycomb substrate in the inner circumferential direction of the cell, the catalyst material can be diffused, dissolved, and reacted even when subjected to high temperature oxidation / reduction heat treatment. -Sintering (grain growth) is less likely to occur, the performance of each catalyst layer is fully expressed, and shows superior catalyst performance compared to the case where two or more catalyst materials are mixed. In addition, each catalyst layer may be in contact with the next catalyst layer as a whole and / or a part thereof, or may be separated from each other.

  The honeycomb-shaped catalyst of the present invention shown in FIGS. 1A and 1G has a square-shaped cross section of the cell 1a of the honeycomb substrate, and the inner wall 1b of the cell 1a is divided into two in the inner circumferential direction of the cell. The catalyst A layer 101A is arranged in one of the regions, and the catalyst B layer 101B is arranged in the other, that is, one catalyst A layer 101A and one catalyst B layer 101B are formed on the inner wall 1b of the cell 1a. The cells are arranged in a state separated in the inner peripheral direction of the cell.

  The honeycomb-shaped catalyst of the present invention shown in FIGS. 1B and 1H has a square-shaped cross section of the cell 1a of the honeycomb-shaped substrate, and the inner wall 1b of the cell 1a is divided into four in the inner peripheral direction of the cell. The catalyst A layer 101A is disposed in one of the regions, the catalyst B layer 101B is disposed in two regions adjacent to the catalyst A layer 101A, and the catalyst A layer 101A is disposed in a region facing the catalyst A layer 101A. In other words, the two catalyst A layers 101A and the two catalyst B layers 101B are alternately arranged on the inner wall 1b of the cell 1a while being separated in the inner circumferential direction of the cell.

  The honeycomb-shaped catalyst of the present invention shown in FIGS. 1C and 1I has a honeycomb substrate base cell 1a having a square cross section, and the inner wall 1b of the cell 1a is divided into four in the inner circumferential direction of the cell. The catalyst A layer 101A is in one of the regions, the catalyst B layer 101B is in one region adjacent to the catalyst A layer 101A, and the catalyst D layer 101D (or the catalyst is in the other region adjacent to the catalyst A layer 101A). C layer 101C) has a catalyst C layer 101C (or catalyst D layer 101D) disposed in a region facing the catalyst A layer 101A, that is, the catalyst A layer 101A and the catalyst on the inner wall 1b of the cell 1a. In a state where the B layer 101B, the catalyst C layer 101C, and the catalyst D layer 101D (or the catalyst A layer 101A, the catalyst B layer 101B, the catalyst D layer 101D, and the catalyst C layer 101C) are separated in the inner circumferential direction of the cell. In which is disposed.

  The honeycomb catalyst of the present invention shown in FIGS. 1D and 1J has a regular hexagonal cross-sectional shape of the cell 1a of the honeycomb substrate, and the inner wall 1b of the cell 1a is divided into two in the inner circumferential direction of the cell. The catalyst A layer 101A is arranged in one of the regions, and the catalyst B layer 101B is arranged in the other, that is, one catalyst A layer 101A and one catalyst B layer 101B are formed on the inner wall 1b of the cell 1a. The cells are arranged in a state separated in the inner peripheral direction of the cell.

  The honeycomb catalyst of the present invention shown in FIGS. 1E and 1K has a regular hexagonal cross-sectional shape of the cell 1a of the honeycomb substrate, and the inner wall 1b of the cell 1a is divided into six in the inner circumferential direction of the cell. The catalyst A layer 101A is in one of the regions, the catalyst B layer 101B is in two regions adjacent to the catalyst A layer 101A, and the catalyst B layer 101B is in the region facing the catalyst A layer 101A. The catalyst A layer 101A is disposed in two regions adjacent to the layer 101B, that is, three catalyst A layers 101A and three catalyst B layers 101B are arranged in the inner circumferential direction of the cell on the inner wall 1b of the cell 1a. They are alternately arranged in a separated state.

  In the honeycomb-shaped catalyst of the present invention shown in FIG. 1F, the cell 1a of the honeycomb-shaped base material has a regular hexagonal cross section, and the inner wall 1b of the cell 1a is divided into three in the inner circumferential direction of the cell. One of them is a catalyst A layer 101A, a catalyst B layer 101B in one region adjacent to the catalyst A layer 101A, and a catalyst C layer 101C in the other region adjacent to the catalyst A layer 101A. That is, the catalyst A layer 101A, the catalyst B layer 101B, and the catalyst C layer 101C are sequentially arranged on the inner wall 1b of the cell 1a while being separated in the inner circumferential direction of the cell.

  The honeycomb-shaped catalyst of the present invention shown in FIG. 1L has a regular hexagonal cross-sectional shape of the cell 1a of the honeycomb-shaped substrate, and the inner wall 1b of the cell 1a is divided into four in the inner circumferential direction of the cell. One of the catalyst A layer 101A, the catalyst C layer 101C is disposed in two regions adjacent to the catalyst A layer 101A, and the catalyst B layer 101B is disposed in a region facing the catalyst A layer 101A, That is, the catalyst A layer 101A, the catalyst C layer 101C, the catalyst B layer 101B, and the catalyst C layer 101C are sequentially arranged on the inner wall 1b of the cell 1a while being separated in the inner circumferential direction of the cell.

  Moreover, when the cross-sectional shape of the cells of the honeycomb-shaped substrate is a polygon such as a regular square or a regular hexagon, when the viscosity of the catalyst material or catalyst material slurry to be applied increases, as shown in FIG. 1G to FIG. The inner circumference of the layer becomes a circle. For this reason, the thickness of the catalyst layer at the center of the side (polygonal side) in the cell cross-sectional shape is thinner than the corner (polygonal apex part). Therefore, as shown in FIGS. 1G to 1L, the boundary part of the adjacent catalyst layer is set to a side (polygonal side) (preferably the central part of the side (central part of the polygonal side)) in the cross-sectional shape of the cell. By disposing, compared with the honeycomb-shaped catalyst shown in FIGS. 1A to 1F, diffusion, solid solution, reaction, sintering (grain growth), etc. of the catalyst material can be further prevented. 1L, the catalyst A layer 101A and the catalyst B layer 101B are separated from each other by disposing the catalyst C layer 101C as a buffer layer between the catalyst A layer 101A and the catalyst B layer 101B. Can be further increased.

  In the honeycomb catalyst of the present invention shown in FIGS. 1A to 1L, the composition of the catalyst A layer 101A, the catalyst B layer 101B, the catalyst C layer 101C, and the catalyst D layer 101D is uniform in the long axis direction of the cell. It is preferable. Thereby, the pressure loss with respect to the gas which distribute | circulates the inside of a cell can be reduced.

  In the honeycomb catalyst of the present invention, the width of the catalyst layer (the length in the minor axis direction on the surface of the catalyst layer) is preferably 0.05 to 5 mm, more preferably 0.3 to 2 mm. When the width of the catalyst layer is less than the lower limit, separation of the catalyst layer is not sufficient, and the catalyst performance tends to be insufficient. On the other hand, when the upper limit is exceeded, the coexistence effect of two or more types of catalyst layers is sufficient. Tend to be difficult to obtain.

  Moreover, as thickness of a catalyst layer, 5-200 micrometers is preferable and 10-50 micrometers is more preferable. When the thickness of the catalyst layer is less than the lower limit, a sufficient amount of the catalyst material cannot be supported, and thus the catalyst performance tends to be insufficient. On the other hand, when the upper limit is exceeded, a gas flow path is sufficiently secured. Since this is not possible, the pressure loss with respect to the gas flowing in the cell increases. For example, in the case of an exhaust gas purifying catalyst, the fuel consumption of an automobile tends to deteriorate.

  Such a method for manufacturing a honeycomb-shaped catalyst of the present invention will be described below by taking as an example the case where the catalyst material A and the catalyst material B are applied to form the catalyst layer A and the catalyst layer B.

  First, a discharge tube such as a syringe is inserted into the cell from one end face of the honeycomb-shaped substrate, and the tip of the discharge tube is moved until it reaches the other end surface of the honeycomb-shaped substrate. Next, the catalyst material A is supplied to the discharge pipe while moving the discharge pipe from the other end face toward the one end face along the long axis direction of the cells of the honeycomb substrate, and the tip end of the discharge pipe It discharges from the material discharge port provided in this. At this time, the catalyst material A can be applied to a partial region in the inner peripheral direction of the inner wall of the cell by providing a material discharge port on a part of the outer peripheral surface of the distal end portion of the discharge pipe. A series of these operations is performed for each cell, and the catalyst material A is applied to a partial region of the inner wall direction of the inner wall of each cell. Thereafter, the applied catalyst material A is baked to form the catalyst layer A in a partial region in the inner peripheral direction of the inner wall of each cell.

  Next, the direction of the material discharge port is set by rotating the discharge pipe with the major axis direction as the rotation axis so that the catalyst material B is applied to a predetermined region where the catalyst layer A on the inner wall of the cell is not formed. . Thereafter, the discharge pipe is inserted into the cell from one end face of the honeycomb substrate, and the tip of the discharge pipe is moved until it reaches the other end face of the honeycomb substrate. Next, the catalyst material B is supplied to the discharge pipe while moving the discharge pipe from the other end face toward the one end face along the long axis direction of the cells of the honeycomb-shaped base material, and the tip of the discharge pipe is supplied. It discharges from the provided material discharge port. Thereby, the catalyst material B is apply | coated to the area | region of the inner peripheral direction of the area | region where the catalyst layer A of the inner wall of a cell is not formed. A series of these operations is performed for each cell, and the catalyst material A is applied to a partial region of the inner wall direction of the inner wall of each cell. Thereafter, the applied catalyst material B is baked, so that the catalyst layer B is formed in at least a part of the inner peripheral direction of the inner wall of each cell in the region where the catalyst layer A is not formed.

  In this way, by sequentially applying and firing the catalyst material A and the catalyst material B, for example, two types can be formed on the inner wall of the cell of the honeycomb substrate as shown in FIGS. 1A, 1D, 1G, and 1J. Thus, the honeycomb catalyst of the present invention can be obtained in which the catalyst layers are separated in the inner circumferential direction of the cell. Further, by sequentially repeating the application and firing of the catalyst material A and the catalyst material B as described above, for example, on the inner wall of the cell of the honeycomb substrate as shown in FIGS. 1B, 1E, 1H and 1K. The honeycomb-shaped catalyst of the present invention in which two types of catalyst layers are alternately arranged in a state where they are separated in the inner peripheral direction of the cell can be obtained. Furthermore, after the catalyst layer A and the catalyst layer B are formed as described above, the catalyst material C and the like are further applied and baked, for example, as shown in FIGS. 1C, 1F, 1I, and 1L. In addition, the honeycomb catalyst of the present invention can be obtained in which three or more kinds of catalyst layers are alternately arranged on the inner wall of the cell of the honeycomb substrate in the state of being separated in the inner circumferential direction of the cell.

  In such a honeycomb catalyst manufacturing method, when a catalyst material slurry is used as a catalyst material, the viscosity is not particularly limited as long as the catalyst material is discharged from the material discharge port, and the type of discharge device is selected. Thus, a slurry of about 1000 mPa · s can be used, but from the viewpoint that the catalyst material can be easily applied to the inner wall of the cell by the above method, 300 mPa · s or less is preferable, and 200 mPa · s or less is preferable. More preferred is 100 mPa · s or less.

  In the method for manufacturing the honeycomb-shaped catalyst, the method for supplying the catalyst material to the discharge pipe is not particularly limited. For example, various liquid feed pumps such as an air type, a valve type, a screw type, and a uniaxial eccentric screw type are used. A method is mentioned.

  Furthermore, in the method for manufacturing the honeycomb-shaped catalyst, a gas such as air is supplied from the gas supply device to the gas flow path, and the catalyst material is applied while being blown from the gas discharge port provided at the tip of the discharge pipe. It is preferable. As a result, the catalyst material can be reliably adhered to the inner wall of the cell, and the excess catalyst material is removed, the inner wall of the cell becomes smooth, the pressure loss is small, and the flow path (cell) with a smooth inner wall is formed. It becomes possible to obtain a honeycomb-shaped catalyst.

  In the method for manufacturing the honeycomb-shaped catalyst, it is preferable to apply the catalyst material while sucking the inside of the cell from the end surface opposite to the end surface where the discharge pipe of the honeycomb-shaped base material is inserted using a suction device. As a result, excess catalyst material is removed, the inner wall of the cell becomes smooth, pressure loss is small, and a honeycomb catalyst having a flow path (cell) with a smooth inner wall can be manufactured.

  Furthermore, in the method for manufacturing the honeycomb-shaped catalyst, a liquid such as water is supplied from the liquid supply device to the liquid flow path, and the catalyst material is applied while spraying from the liquid discharge port provided at the tip of the discharge pipe. It is also possible. Thereby, drying and solidification of the catalyst material in the vicinity of the material discharge port can be prevented.

  Although the honeycomb catalyst manufacturing method of the present invention has been described above, the honeycomb catalyst of the present invention is not limited to the one manufactured by the above method. For example, in the above method, a catalyst layer is formed in a plurality of cells by inserting one discharge pipe into one cell, applying and baking the catalyst material, and repeating this operation for each cell. However, a plurality of discharge pipes may be simultaneously inserted into a plurality of cells to apply and burn the catalyst material, and a catalyst layer may be simultaneously formed in the plurality of cells. Thereby, the total application time can be shortened.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. The catalyst material slurry used in Examples and Comparative Examples was prepared by the following method.

(Preparation Example 1)
<Preparation of iron oxide-zirconia composite oxide powder>
333.8 g of iron (III) ammonium citrate (manufactured by Wako Pure Chemical Industries, reagent, brown, iron content: 16-19%), water-dispersed yttria-containing alkaline zirconia sol (manufactured by Nissan Chemical Industries, Ltd.) “Nanouse ZR30-BS”, sol particle diameter: 30 to 80 nm, ZrO ₂ solid content concentration: 30.8%, Zr: Y (atomic ratio) = 1: 0.109, containing tetramethylammonium hydroxide (TMAH) .) 223.5 g and 179.1 g of distilled water were charged into a 1 L polyethylene beaker. The atomic ratio of the composite oxide calculated from these charges is Fe: Zr: Y = 2.00: 1.00: 0.109, and the contents of Fe ₂ O ₃ , ZrO ₂ and Y ₂ O ₃ are _{Fe 2 O 3: ZrO 2:} Y 2 O 3 ( wt%) = 54.09: 41.74: was 4.17.

  This mixture is sufficiently stirred with a propeller stirrer, and further stirred with a homogenizer (IKA "T25", shaft generator using IKA "S25N-25F") at a rotation speed of 20000 rpm for 1 minute. Performed 3 times. Then, suction filtration is performed using filter paper (5 types C, particle retention capacity: 2.5 μm, diameter: 70 mmφ) to remove impurities, and yttria-containing zirconia sol water suspension in which iron (III) ammonium citrate is dissolved. The liquid was collected in a glass beaker.

  The aqueous suspension was concentrated by heating with a hot stirrer set to 250 ° C. while stirring with a propeller stirrer coated with Teflon (registered trademark). Stirring was stopped before the viscosity of the aqueous suspension became high and stirring became difficult, and the concentrate was placed in a dryer at 120 ° C. together with a propeller blade and dried for 12 hours or more. The obtained powder was put into a crucible, and in order to oxidize the powder completely, it was put in a sheath pot with the lid of the crucible opened about 1/10 to 1/5. The sheath pot was placed in a degreasing furnace capable of circulating air, and the powder was calcined in the air at 150 ° C. for 3 hours → 250 ° C. for 2 hours → 400 ° C. for 2 hours → 500 ° C. for 5 hours.

  Thereafter, when the temperature of the degreasing furnace became 150 ° C. or lower, the sheath mortar was taken out from the degreasing furnace, and the powder was pulverized using an agate mortar until the size became 75 μm or smaller. The obtained pulverized product is put in a crucible, put in a box-type electric furnace with the lid of the crucible opened about 1/10 to 1/5, and baked in the atmosphere at 900 ° C. for 5 hours to obtain an iron oxide-zirconia composite. An oxide powder (hereinafter referred to as “FZ powder”) was obtained. The volume-based particle size distribution of the FZ powder was measured by a dynamic light scattering method, and the average particle size D50 (particle size at a cumulative frequency of 50%) was determined to be 34 μm.

(Preparation Example 2)
<Preparation of iron oxide-zirconia composite oxide slurry>
100 parts by mass of the FZ powder obtained in Preparation Example 1, 10 parts by mass of acetic acid-stabilized alumina sol (“AS200” manufactured by Nissan Chemical Industries, Ltd., solid content concentration: 10.8%) and water with a solid content concentration of 40 masses %, And then stirred for 2 minutes using a homogenizer to obtain an iron oxide-zirconia composite oxide slurry (hereinafter referred to as “FZ slurry”). The volume-based particle size distribution of this FZ slurry was measured by a dynamic light scattering method, and the average particle size D50 (particle size at a cumulative frequency of 50%) was determined to be 11 μm. Further, when the viscosity at 25 ° C. was measured using an E-type viscometer (“TVE-35H type” manufactured by Toki Sangyo Co., Ltd.), as shown in FIG. It was 100 mPa · s or less.

(Preparation Example 3)
<Preparation of rhodium-supported alumina powder>
Lanthanum-stabilized Θ-alumina powder (Cataler Co., Ltd., lanthanum content: 1% by mass, specific surface area: about 100 m ² / g) is sieved using a pulverizer (A Wonder Co., Ltd. “Wonder Blender”). It grind | pulverized so that a particle size might be 25 micrometers or less. 100 ml of distilled water was added to 40 g of the pulverized product, and 2.114 ml of a rhodium nitrate solution containing 0.060009 g of rhodium (Rh) in terms of metal was added to the La stabilized Θ-alumina powder. After impregnating the solution, it was evaporated to dryness on a hot stirrer set while gradually raising the temperature to 110 to 150 ° C., and further dried in the atmosphere at 110 ° C. for 16 hours to obtain a coagulated product (evaporation drying). Hard). Subsequently, La stabilized Θ-alumina powder (hereinafter referred to as “Rh / Θ-alumina powder”) carrying Rh was obtained by firing at 500 ° C. for 1 hour. The obtained Rh / Θ-alumina powder was pulverized using an agate mortar until the size became 75 μm or less. The volume-based particle size distribution of the obtained pulverized product was measured by a dynamic light scattering method, and the average particle size D50 (particle size at a cumulative frequency of 50%) was determined to be 13 μm. In addition, the rhodium carrying amount in the obtained Rh / Θ-alumina powder was 0.15% by mass.

(Preparation Example 4)
<Preparation of rhodium-supported alumina slurry>
100 parts by mass of Rh / Θ-alumina powder obtained in Preparation Example 3, 10 parts by mass of acetic acid stabilized alumina sol (“AS200” manufactured by Nissan Chemical Industries, Ltd., solid content concentration: 10.8%) and water as solid content After mixing to a concentration of 30% by mass, the mixture was stirred for 2 minutes using a homogenizer to obtain a rhodium-supported alumina slurry (hereinafter referred to as “Rh / alumina slurry”). The volume-based particle size distribution of the Rh / alumina slurry was measured by a dynamic light scattering method, and the average particle size D50 (particle size at a cumulative frequency of 50%) was determined to be 12 μm. Further, when the viscosity at 25 ° C. was measured in the same manner as in Preparation Example 2, as shown in FIG. 2, it was 100 mPa · s or less in a shear rate range of 10 to 300 / sec.

(Preparation Example 5)
<Preparation of palladium-supported ceria-zirconia composite oxide powder>
Complex oxide powder containing ceria-zirconia pulverized to 12.195 g (1 g as Pd) in a nitric acid acidic palladium-supporting aqueous solution (Pat content: 8.2 mass%, manufactured by Cataler, Inc.) to a size of 25 μm or less (Average particle diameter (D50): 7.5 μm, CeO ₂ : ZrO ₂ : other rare earth oxide = 60% by mass: 30% by mass: 10% by mass, hereinafter referred to as “CZ powder”) After impregnating CZ powder with an aqueous solution carrying palladium nitrate that is acidic, evaporate to dryness on a hot stirrer set while gradually raising the temperature to 120 to 220 ° C., and further calcinate at 500 ° C. for 1 hour in the air. Thus, a ceria-zirconia composite oxide powder (hereinafter referred to as “Pd / CZ powder”) carrying Pd was obtained. The average particle size (D50) of the CZ powder is a particle size at a cumulative frequency of 50% of the volume-based particle size distribution of the CZ powder measured by a dynamic light scattering method.

(Preparation Example 6)
<Preparation of mixed slurry of palladium-supported ceria-zirconia composite oxide powder and alumina powder>
100 parts by mass of Pd / CZ powder obtained in Preparation Example 5, lanthanum stabilized Θ-alumina powder pulverized to a size of 25 μm or less (manufactured by Cataler, Inc., average particle size (D50): about 17 μm, lanthanum content : 4% by mass, specific surface area: about 100 m ² / g) 100 parts by mass, acetic acid stabilized alumina sol (Nissan Chemical Industries, Ltd. “AS200”, solid content concentration: 10.8%) 20 parts by mass and water After mixing so that the partial concentration becomes 30% by mass, the mixture is stirred for 2 minutes using a homogenizer and mixed slurry containing Pd / CZ powder and Θ-alumina powder (hereinafter referred to as “Pd / CZ + alumina mixed slurry”). .) The average particle size (D50) of the lanthanum-stabilized Θ-alumina powder is the particle size at a cumulative frequency of 50% of the volume-based particle size distribution of the CZ powder measured by the dynamic light scattering method.

(Preparation Example 7)
<Preparation of mixed slurry of iron oxide-zirconia composite oxide powder and rhodium-supported alumina powder>
125 parts by mass of FZ powder obtained in Preparation Example 1, 100 parts by mass of Rh / Θ-alumina powder obtained in Preparation Example 3, acetic acid stabilized alumina sol (“AS200” manufactured by Nissan Chemical Industries, Ltd.), solid content concentration: 10.8%) After mixing 22.5 parts by mass and water so that the solid content concentration becomes 36% by mass, the mixture is stirred for 2 minutes using a homogenizer and contains FZ powder and Rh / Θ-alumina powder. A mixed slurry (hereinafter referred to as “FZ + Rh / alumina mixed slurry”) was obtained. The volume-based particle size distribution of this FZ + Rh / alumina mixed slurry was measured by a dynamic light scattering method, and the average particle size D50 (particle size at a cumulative frequency of 50%) was determined to be 15.5 μm. Further, when the viscosity at 25 ° C. was measured in the same manner as in Preparation Example 2, as shown in FIG. 2, it was 100 mPa · s or less in a shear rate range of 10 to 300 / sec.

(Preparation Example 8)
<Preparation of mixed slurry of palladium-supported ceria-zirconia composite oxide powder and rhodium-supported alumina powder>
After mixing 60 parts by mass of the Rh / alumina slurry obtained in Preparation Example 4 and 80 parts by mass of the Pd / CZ + alumina mixed slurry obtained in Preparation Example 6, the mixture was stirred and Pd / CZ powder and Rh / Θ-alumina were mixed. A mixed slurry containing the powder (hereinafter referred to as “Pd / CZ + Rh / alumina mixed slurry”) was obtained.

Example 1
As shown in FIG. 3, a honeycomb substrate (made by cordierite, substrate size: length 10 mm × width 10 mm × length 49 mm, capacity: about 5 ml, cell shape: square cell, number of cells: 200 cells / inch, An FZ layer (catalyst A layer 101A) is formed in an approximately half region in the inner circumferential direction of the inner wall 1b of 25 cells having a cell thickness of 12 mils and a cell pitch of 1.9 mm × 1.9 mm. An Rh / alumina layer (catalyst B layer 101B) was formed in the remaining regions facing each other. These separation coat catalyst layers had a total coating amount of about 0.6 g (about 120 g / L-cat with respect to 1 L of the honeycomb substrate). The mass ratio between the FZ layer and the Rh / alumina layer was FZ: Rh / alumina = 5: 4.

  First, the honeycomb-shaped substrate was washed with water, dried, and then fired in air at 1000 ° C. for 3 hours. As shown in FIG. 4A, a discharge pipe 3 (outer diameter: 1.07 mm, inner diameter: 0.69 mm) in which a material discharge port 2 is provided in a part of the outer peripheral surface of the tip is connected to the honeycomb substrate 1 Was inserted into the cell 1a from one end face 4 and moved until the tip portion reached the other end face 5. Next, as shown in FIG. 4B, the discharge pipe 3 is moved from the end surface 5 to the end surface 4 at a speed of 5.0 mm / second along the long axis direction of the cell 1a, and the inside of the cell 1a is sucked. While, the FZ slurry obtained in Preparation Example 2 was supplied from the slurry supply device 6 to the discharge pipe 3 at a speed of 0.03 mm / second, and discharged from the material discharge port 2 at the tip of the discharge pipe 3. At this time, since the material discharge port 2 is provided in a part of the outer peripheral surface of the distal end portion of the discharge pipe 3, the FZ slurry is applied to an approximately half region in the inner peripheral direction of the inner wall 1b of the cell, and the FZ slurry layer (Catalyst material A layer 102A) was formed. This operation was performed for 25 cells, and the FZ slurry was applied to about a half region in the inner peripheral direction of the inner wall 1b of each cell to form an FZ slurry layer (catalyst material A layer 102A). Thereafter, by firing at 500 ° C. for 1 hour in the air, an FZ layer (catalyst A layer 101A) having a width of about 1.5 mm is formed in about a half region in the inner peripheral direction of the inner wall 1b of the cell of the honeycomb substrate 1. ) Was formed.

  Next, after rotating the direction of the material discharge port 2 of the discharge pipe 3 by 180 °, as shown in FIG. 4C, the discharge pipe 3 is inserted into the cell from one end face 4 of the honeycomb-shaped substrate 1, The tip was moved until it reached the other end face 5. Next, as shown in FIG. 4D, the discharge pipe 3 is moved from the end surface 5 to the end surface 4 at a speed of 5.0 mm / second along the long axis direction of the cell 1a, and the inside of the cell 1a is sucked. However, the Rh / alumina slurry obtained in Preparation Example 4 was supplied from the slurry supply device 6 to the discharge pipe 3 at a speed of 0.06 mm / second and discharged from the material discharge port 2 at the tip of the discharge pipe 3. At this time, since the material discharge port 2 is provided in a part of the outer peripheral surface of the distal end portion of the discharge pipe 3, the Rh / alumina slurry is formed in the remaining region facing the FZ layer in the inner peripheral direction of the inner wall 1b of the cell. Was applied to form an Rh / alumina slurry layer (catalyst material B layer 102B). This operation is performed for 25 cells, and Rh / alumina slurry is applied to the remaining region facing the FZ layer in the inner circumferential direction of the inner wall 1b of each cell, and the Rh / alumina slurry layer (catalyst material B layer 102B) Formed. Thereafter, the remaining area facing the FZ layer (catalyst A layer 101A) in the inner peripheral direction of the inner wall 1b of the cell of the honeycomb-shaped substrate 1 is reduced in width by firing at 500 ° C. for 1 hour in the atmosphere. A 1.5 mm Rh / alumina layer (catalyst B layer 101B) was formed.

(Comparative Example 1)
As shown in FIG. 5, a honeycomb substrate (made of cordierite, substrate size: length 10 mm × width 10 mm × length 49 mm, capacity: about 5 ml, cell shape: square cell, number of cells: 200 cells / inch, Using the same method as in Example 1, two FZ + Rh / alumina mixed layers (mixed catalyst layer 104A) were formed on the inner walls 1b of 25 cells having a cell thickness of 12 mil and a cell pitch of 1.9 mm × 1.9 mm. And 104B) were formed with these layers facing each other. These mixed catalyst layers had a total coating amount of about 0.55 g (about 110 g / L-cat with respect to 1 L of the honeycomb substrate). Moreover, it formed so that mass ratio of FZ and Rh / alumina in a mixed layer might become FZ: Rh / alumina = 5: 4.

  First, the honeycomb-shaped substrate was washed with water, dried, and then fired in air at 1000 ° C. for 3 hours. As shown in FIG. 4A, a discharge pipe 3 (outer diameter: 1.07 mm, inner diameter: 0.69 mm) provided with a material discharge port 2 in a part of the outer peripheral surface of the tip is connected to the honeycomb substrate 1. It was inserted into the cell 1 a from one end face 4 and moved until the tip end reached the other end face 5. Next, in Preparation Example 7, while moving the discharge pipe 3 in the direction from the end face 5 to the end face 4 at a speed of 5.0 mm / sec along the long axis direction of the cell 1a, and suctioning the inside of the cell 1a, The obtained FZ + Rh / alumina mixed slurry was supplied from the slurry supply device 6 to the discharge pipe 3 at a speed of 0.04 mm / second, and was discharged from the material discharge port 2 at the tip of the discharge pipe 3. At this time, since the material discharge port 2 is provided in a part of the outer peripheral surface of the distal end portion of the discharge pipe 3, the FZ + Rh / alumina mixed slurry is applied to about a half region in the inner peripheral direction of the inner wall 1b of the cell, An FZ + Rh / alumina mixed slurry layer (mixed catalyst material layer) was formed. This operation was performed for 25 cells, and the FZ + Rh / alumina mixed slurry was applied to about half of the inner circumferential direction of the inner wall 1b of each cell to form an FZ + Rh / alumina mixed slurry layer (mixed catalyst material layer). Thereafter, by firing in the atmosphere at 500 ° C. for 1 hour, an FZ + Rh / alumina mixed layer (mixed catalyst) having a width of about 1.5 mm is formed in about a half region in the inner circumferential direction of the inner wall 1b of the cell of the honeycomb substrate. Layer 104A) was formed.

  Next, after the direction of the material discharge port 2 of the discharge pipe 3 is rotated by 180 °, the discharge pipe 3 is inserted into the cell from one end face 4 of the honeycomb substrate 1, and the tip is the other end face 5. Moved until it reached. Next, the discharge pipe 3 is moved in the direction from the end face 5 to the end face 4 at a speed of 5.0 mm / sec along the major axis direction of the cell 1a, and the inside of the cell 1a is sucked and obtained in Preparation Example 7. The obtained FZ + Rh / alumina mixed slurry was supplied from the slurry supply device 6 to the discharge pipe 3 at a speed of 0.04 mm / second, and was discharged from the material discharge port 2 at the tip of the discharge pipe 3. At this time, since the material discharge port 2 is provided in a part of the outer peripheral surface of the distal end portion of the discharge pipe 3, it faces the FZ + Rh / alumina mixed layer (mixed catalyst layer 104A) in the inner peripheral direction of the inner wall 1b of the cell. The FZ + Rh / alumina mixed slurry was applied to the remaining region to form an FZ + Rh / alumina mixed slurry layer (mixed catalyst material layer). This operation is performed for 25 cells, FZ + Rh / alumina mixed slurry is applied to the remaining area facing the FZ + Rh / alumina mixed layer (mixed catalyst layer 104A) in the inner circumferential direction of the inner wall 1b of each cell, and FZ + Rh / An alumina mixed slurry layer (mixed catalyst material layer) was formed. Thereafter, by firing in the atmosphere at 500 ° C. for 1 hour, the width of the remaining region facing the FZ + Rh / alumina mixed layer (mixed catalyst layer 104A) in the inner peripheral direction of the inner wall 1b of the cell of the honeycomb-shaped substrate is widened. A FZ + Rh / alumina mixed layer (mixed catalyst layer 104B) having a thickness of about 1.5 mm was formed. As a result, two FZ + Rh / alumina mixed layers (mixed catalyst layers 104A and 104B) having a width of about 1.5 mm were formed on the inner wall 1b of the cell of the honeycomb substrate so as to face each other.

<Heat resistance test (1)>
Four honeycomb-shaped catalysts obtained in Example 1 and Comparative Example 1 were simultaneously mounted on a reaction tube having an inner diameter of about 30 mm. At this time, the gap between the reaction tube and the honeycomb catalyst was filled with quartz wool so that the gas introduced into the reaction tube could sufficiently flow through the honeycomb catalyst. The reaction tube was heated at 1000 ° C. for 5 hours while reducing gas [CO (1 vol%) + H ₂ O (3 vol%) + N ₂ (remainder)] was circulated at 10 L / min. The catalyst was subjected to a heat resistance test.

<CO and NO 50% purification temperature>
An evaluation gas [NO (about 0.1 vol%) + CO (about 0.45 vol%) + H ₂ O (3 vol%) + O ₂ ( (Predetermined flow rate) + N ₂ (remainder)] is circulated at 15 L / min while heating from 150 ° C. to 600 ° C. at a rate of temperature increase of 24 ° C./min. The concentration of CO and NO in the catalyst was measured to calculate the purification rate thereof, and the catalyst temperature (50% purification temperature of CO and NO) when CO and NO were purified by 50% was determined. The results are shown in FIG. The flow rate of O ₂ gas was appropriately adjusted so that the air-fuel ratio of the catalyst-containing gas was about 0.999.

<Average CO and NO purification rate>
In the reaction tube equipped with the honeycomb catalyst after the heat resistance test (1), the temperature of the gas containing the catalyst was 280 ° C., and the steady gas [NO (about 0.045 vol%) + H ₂ O (3 vol%) + N ₂ (remainder) )] Is circulated at 15 L / min, rich gas (CO (about 0.2 vol%) + N ₂ (remainder)) is circulated at 15 L / min for 1 minute, and then lean gas (O ₂ (about 0.05 vol. %) + N ₂ (remainder)) was allowed to flow at 15 L / min for 1 minute. This operation was repeated twice, and the average concentration of CO and NO in the catalyst-containing gas and the catalyst output gas for a total of 4 minutes (2 cycles) was measured to calculate the average purification rate of CO and NO. The results are shown in Table 1.

  As apparent from the results shown in FIG. 6 and Table 1, the honeycomb catalyst of the present invention formed by separating the FZ layer and the Rh / alumina layer on the inner wall of the cell in the inner circumferential direction (Example 1: Separation coat) ) Purifies CO and NO at a lower catalyst-containing gas temperature than a honeycomb catalyst (Comparative Example 1: Mixed slurry coating) formed on the inner wall of a cell so that two FZ + Rh / alumina mixed layers face each other. It was found that the catalyst activity was excellent.

  Further, as apparent from the results shown in Table 1, the honeycomb catalyst of the present invention formed by separating the FZ layer and the Rh / alumina layer on the inner wall of the cell in the inner circumferential direction (Example 1: Separation coat) Compared with the honeycomb catalyst (Comparative Example 1: Mixed slurry coating) formed on the inner wall of the cell so that two FZ + Rh / alumina mixed layers face each other, the average purification rate of CO and NO is high, and the exhaust gas purification performance It was found to be excellent.

<X-ray diffraction measurement of catalyst layer>
As shown in FIG. 7, an FZ layer 105A and an alumina layer are formed on a honeycomb-shaped flat plate (20 mm × 50 mm) cut out from a honeycomb substrate (made of cordierite, cell shape: hexagonal cell, cell interval: 1.3 mm). 105B were alternately formed. That is, on the honeycomb-shaped flat plate, the FZ slurry obtained in Preparation Example 2 and the lanthanum stabilized Θ-alumina powder in which Rh is not supported (manufactured by Cataler, Inc., lanthanum content: 1 mass%, specific surface area: The slurry containing about 100 m ² / g) was alternately applied by one cell at a time and fired at 500 ° C. for 1 hour in the air. As a result, on the honeycomb-shaped flat plate, a test piece in which FZ layers and alumina layers are alternately separated by one cell in a direction perpendicular to the long axis direction of the cells (hereinafter referred to as “separation coat test piece”). ").

Moreover, the FZ powder obtained in Preparation Example 1 and Rh-stabilized Θ-alumina powder in which Rh was not supported (made by Cataler, Inc., lanthanum content: 1% by mass, ratio) A mixed slurry containing a surface area of about 100 m ² / g) at a mass ratio of 2: 1 was applied and fired at 500 ° C. for 1 hour in the air. Thereby, a test piece (hereinafter referred to as “mixed slurry coat test piece”) in which an FZ + alumina mixed layer was disposed on the entire surface of the honeycomb-shaped flat plate was obtained.

Further, the entire surface of the honeycomb-shaped flat plate contains lanthanum-stabilized Θ-alumina powder (made by Cataler, Inc., lanthanum content: 1 mass%, specific surface area: about 100 m ² / g) on which Rh is not supported. The slurry to be applied was applied and baked at 500 ° C. for 1 hour in the air. As a result, a test piece (hereinafter referred to as “alumina slurry coat test piece”) having an alumina layer disposed on the entire surface of the honeycomb-shaped flat plate was obtained.

  Further, the FZ slurry obtained in Preparation Example 2 was applied to the entire surface of the honeycomb-shaped flat plate and fired at 500 ° C. for 1 hour in the air. As a result, a test piece (hereinafter referred to as “FZ slurry coat test piece”) in which the FZ layer is disposed on the entire surface of the honeycomb-shaped flat plate was obtained.

After subjecting each test piece to the heat resistance test (1), the catalyst layer was scraped and collected, and the obtained catalyst powder was subjected to powder X-ray diffraction measurement. The result is shown in FIG. As shown in FIG. 8, in the mixed slurry-coated specimen, an X-ray diffraction peak derived from FeAl ₂ O ₄ is observed, and Fe and Al react to form a spinel phase (FeAl ₂ O ₄ ). It was confirmed that On the other hand, in the separation coat test piece, an X-ray diffraction peak derived from Fe ₃ O ₄ was observed as in the FZ slurry coat test piece, but no X-ray diffraction peak derived from FeAl ₂ O ₄ was observed. It was. From these results, in the honeycomb catalyst having the FZ + Rh / alumina mixed layer (Comparative Example 1: Mixed slurry coating), the spinel phase (FeAl ₂ O ₄ ) is generated and Rh is deactivated, and the catalytic activity and exhaust gas purification are reduced. The performance is thought to have declined. On the other hand, since no X-ray diffraction peak derived from FeAl ₂ O ₄ was observed in the separation coat test piece, Rh was not deactivated, and it was considered that excellent catalytic activity and exhaust gas purification performance were expressed.

(Example 2)
In the same manner as in Example 1 except that the Pd / CZ + alumina mixed slurry obtained in Preparation Example 6 was used instead of the FZ slurry, as shown in FIG. A Pd / CZ + alumina mixed layer (catalyst A layer 101A) having a width of about 1.5 mm is formed in an approximately half region in the inner circumferential direction, and the remaining region facing the Pd / CZ + alumina mixed layer has a width of about A 1.5 mm Rh / alumina layer (catalyst B layer 101B) was formed. These separation coat catalyst layers had a total coat amount of about 0.7 g (about 140 g / L-cat with respect to 1 L of the honeycomb substrate 1). Further, the mass ratio of the Pd / CZ + alumina mixed layer and the Rh / alumina layer was formed to be Pd / CZ + alumina: Rh / alumina = 4: 3.

(Comparative Example 2)
As shown in FIG. 9, a honeycomb substrate (made of cordierite, substrate size: length 10 mm × width 10 mm × length 49 mm, capacity: about 5 ml, cell shape: square cell, number of cells: 200 cells / inch, A Pd / CZ + alumina mixed layer (catalyst A layer 101A) is formed in an approximately half region in the inner circumferential direction of the inner wall 1b of 25 cells having a cell thickness of 12 mils and a cell pitch of 1.9 mm × 1.9 mm. An Rh / alumina layer was laminated on the Pd / CZ + alumina mixed layer. These laminated catalyst layers had a total coating amount of about 0.7 g (about 140 g / L-cat for 1 L of honeycomb-shaped substrate). Further, the mass ratio of the Pd / CZ + alumina mixed layer and the Rh / alumina layer was formed to be Pd / CZ + alumina: Rh / alumina = 4: 3.

  First, the honeycomb-shaped substrate was washed with water, dried, and then fired in air at 1000 ° C. for 3 hours. As shown in FIG. 4A, a discharge pipe 3 (outer diameter: 1.07 mm, inner diameter: 0.69 mm) in which a material discharge port 2 is provided in a part of the outer peripheral surface of the tip is connected to the honeycomb substrate 1 Was inserted into the cell 1a from one end face 4 and moved until the tip portion reached the other end face 5. Next, in Preparation Example 6, while moving the discharge pipe 3 from the end face 5 to the end face 4 at a speed of 5.0 mm / sec along the major axis direction of the cell 1a, and sucking the inside of the cell 1a, The obtained Pd / CZ + alumina mixed slurry was supplied from the slurry supply device 6 to the discharge pipe 3 at a speed of 0.03 mm / second and discharged from the material discharge port 2 at the tip of the discharge pipe 3. At this time, since the material discharge port 2 is provided in a part of the outer peripheral surface of the distal end portion of the discharge pipe 3, the Pd / CZ + alumina mixed slurry is applied to about a half region in the inner peripheral direction of the inner wall 1b of the cell. A Pd / CZ + alumina mixed slurry layer (catalyst material A layer) was formed. This operation is performed for 25 cells, and Pd / CZ + alumina mixed slurry is applied to about half of the inner circumferential direction of the inner wall 1b of each cell to form a Pd / CZ + alumina mixed slurry layer (catalyst material A layer). did. Thereafter, the Pd / CZ + alumina mixed layer having a width of about 1.5 mm is formed in about half of the inner circumferential direction of the inner wall 1b of the cell of the honeycomb-shaped substrate 1 by firing at 500 ° C. for 1 hour in the atmosphere. Catalyst A layer 101A) was formed.

  Next, the discharge pipe 3 is inserted into the cell from one end face 4 of the honeycomb-shaped substrate 1 without changing the direction of the material discharge port 2 and moved until the tip reaches the other end face 5. It was. Next, the discharge pipe 3 is moved in the direction from the end face 5 to the end face 4 at a speed of 5.0 mm / second along the major axis direction of the cell 1a, and the inside of the cell 1a is sucked and obtained in Preparation Example 4. The obtained Rh / alumina slurry was supplied from the slurry supply device 6 to the discharge pipe 3 at a speed of 0.06 mm / second and discharged from the material discharge port 2 at the tip of the discharge pipe 3. At this time, since the material discharge port 2 is provided in a part of the outer peripheral surface of the distal end portion of the discharge pipe 3, the Rh / alumina slurry is formed on the Pd / CZ + alumina mixed layer in the inner peripheral direction of the inner wall 1b of the cell. Was applied to form an Rh / alumina slurry layer (catalyst material B layer). This operation is performed for 25 cells, and Rh / alumina slurry is applied onto the Pd / CZ + alumina mixed layer in the inner circumferential direction of the inner wall 1b of each cell to form an Rh / alumina slurry layer (catalyst material B layer). did. Thereafter, by firing at 500 ° C. for 1 hour in the atmosphere, the width is about 1 on the Pd / CZ + alumina mixed layer (catalyst A layer 101A) in the inner peripheral direction of the inner wall 1b of the cell of the honeycomb substrate 1. A 5 mm Rh / alumina layer (catalyst B layer 101B) was formed. As a result, a Pd / CZ + alumina mixed layer (catalyst A layer 101A) having a width of about 1.5 mm and an Rh / alumina layer (catalyst B layer 101B) having a width of about 1.5 mm are formed on the inner wall 1b of the cell of the honeycomb substrate. ) And a catalyst layer laminated.

(Comparative Example 3)
In the same manner as in Comparative Example 1 except that the Pd / CZ + Rh / alumina mixed slurry obtained in Preparation Example 8 was used instead of the FZ + Rh / alumina mixed slurry, as shown in FIG. Two Pd / CZ + Rh / alumina mixed layers (mixed catalyst layers 104A and 104B) were formed on the inner wall 1b of the cell so that these layers face each other. These mixed catalyst layers had a total coating amount of about 0.7 g (about 140 g / L-cat with respect to 1 L of honeycomb substrate). Further, the mass ratio of Pd / CZ and Rh / alumina in the mixed layer was formed to be Pd / CZ: Rh / alumina = 4: 3.

<Heat resistance test (2)>
Four honeycomb-shaped catalysts obtained in Example 2 and Comparative Examples 2 to 3 were simultaneously mounted on a reaction tube having an inner diameter of about 30 mm. At this time, the gap between the reaction tube and the honeycomb catalyst was filled with quartz wool so that the gas introduced into the reaction tube could sufficiently flow through the honeycomb catalyst. Rich gas [CO (1 vol%) + H ₂ O (3 vol%) + N ₂ (remainder)] and lean gas [O ₂ (1 vol%) + H ₂ O (3 vol%) + N ₂ (remainder)] are 20 L / min. Then, the reaction tube was heated at 1050 ° C. for 10 hours while being alternately circulated every 1 minute to conduct a heat resistance test on the honeycomb catalyst.

<Oxygen storage amount (OSC)>
In a reaction tube with an inner diameter of 15 mm in which one type of each honeycomb-shaped catalyst after the heat resistance test (2) is mounted, the catalyst-containing gas temperature is 600 ° C., and rich gas [CO (2 vol%) + N ₂ (remainder)] is 15 L / min. After flowing for 1 minute, lean gas [O ₂ (1% by volume) + N ₂ (remainder)] was allowed to flow at 15 L / min for 1 minute. This operation is repeated four times, and the amount of CO ₂ in the catalyst outgas for a total of 4 minutes in the latter half (two cycles) is determined with the amount of CO in the catalyst-containing gas as 100, and this is calculated as the relative oxygen storage amount (OSC). Evaluated as a value. The results are shown in Table 2.

<Average purification rate of NO>
In a reaction tube with an inner diameter of 15 mm, each having a honeycomb-shaped catalyst after the heat resistance test (2) mounted, a gas with a catalyst temperature of 500 ° C., a flow rate of 15 L / min, and a space velocity of 180,000 / hr. 0.65% by volume) + NO (0.15% by volume) + H ₂ O (5% by volume) + CO ₂ (10% by volume) + N ₂ (remainder)] while circulating rich gas [O ₂ (0% by volume)] Was circulated for 3 minutes, and then lean gas [O ₂ (0.65 vol%)] was circulated for 3 minutes. This operation was repeated, and the average purification rate of NO was calculated by measuring the average concentration of NO in the catalyst-containing gas and the catalyst-out gas for 100 seconds from the start of the flow of the rich gas in the next cycle after the stable cycle. The results are shown in Table 2.

  As is apparent from the results shown in Table 2, the honeycomb catalyst of the present invention formed by separating the Pd / CZ + alumina mixed layer and the Rh / alumina layer on the inner wall of the cell in the inner circumferential direction (Example 2: Separation) The coating) was found to be superior in oxygen storage capacity compared to the honeycomb catalyst (Comparative Example 2: Multilayer coating) in which the Pd / CZ + alumina mixed layer and the Rh / alumina layer were laminated.

  Further, as is apparent from the results shown in Table 2, the honeycomb catalyst of the present invention (Example 2) in which the Pd / CZ + alumina mixed layer and the Rh / alumina layer were formed on the inner wall of the cell separately in the inner circumferential direction. : Separation coat) has a higher average purification rate of NO than a honeycomb catalyst (Comparative Example 3: Mixed slurry coat) formed on the inner wall of the cell so that two Pd / CZ + Rh / alumina mixed layers face each other. The exhaust gas purification performance was found to be excellent.

  From the above results, the FZ layer and the Rh / alumina layer, or the Pd / CZ + alumina mixed layer and the Rh / alumina layer are separately disposed on the inner wall of the cell of the honeycomb-shaped substrate, so that the It has been found that even when heat treatment is performed, the reaction between Fe and Al and the solid solution and reaction between Rh, Pd, and CZ can be suppressed, and the deactivation of Rh can be suppressed.

  As described above, according to the present invention, it is provided with a catalyst layer in which a plurality of catalyst materials are used in combination, compared to a conventional honeycomb catalyst having a mixed catalyst layer formed by mixing a plurality of catalyst materials. It becomes possible to obtain a honeycomb-shaped catalyst exhibiting excellent catalyst performance. In particular, when the present invention is applied to a combination of catalyst materials in which a part of the catalyst performance decreases when mixed, it is possible to suppress the decrease in the catalyst performance. For example, the catalyst activity is improved when mixed, but by applying the present invention to a combination of catalyst materials that lowers the heat resistance, not only the catalyst activity is improved but also the heat resistance is suppressed. (Or improved heat resistance).

  Therefore, the honeycomb catalyst of the present invention includes a three-way catalyst for gasoline vehicles, an NOx purification catalyst for storage reduction type, a particulate matter (particulate) purification catalyst for gasoline vehicles having flow-through through holes, one end at a time. Filter-type diesel vehicle particulate matter (particulate) purification catalyst, HC and CO purification catalyst, fuel reforming catalyst, fuel cell catalyst, city gas and hydrogen fuel catalyst with alternately end faces clogged It is useful in a catalyst using two or more kinds of catalyst materials in combination.

  1: honeycomb-shaped substrate, 1a: cell of honeycomb-shaped substrate 1, 1b: inner wall of honeycomb-shaped substrate 1, 2: material discharge port, 3: discharge tube, 4: discharge tube 3 of honeycomb-shaped substrate 5. End face to be inserted, 5: End face opposite to the end face 4 of the honeycomb substrate, 101A: Catalyst A layer, 101B: Catalyst B layer, 101C: Catalyst C layer, 101D: Catalyst D layer, 102A: Catalyst material A layer, 102B: Catalyst material B layer, 103A: Excess catalyst removed Material A, 103B: Excess catalyst material B removed, 104A and 104B: Mixed catalyst layer, 105A: FZ layer, 105B: Alumina layer.

Claims (3)

  A honeycomb comprising: a honeycomb-shaped base material; and two or more types of catalyst layers disposed separately on the inner wall of each cell of the honeycomb-shaped base material in a direction along the inner periphery of the cell Catalyst.   The honeycomb catalyst according to claim 1, wherein the two or more types of catalyst layers have a uniform composition in the major axis direction of the cell.   The two or more catalyst layers include a combination of a rhodium-containing catalyst layer and a palladium-containing catalyst layer, a combination of a rhodium-containing catalyst layer and a platinum-containing catalyst layer, a rhodium-containing catalyst layer and ceria. Combination of catalyst layer containing, combination of catalyst layer containing rhodium and catalyst layer containing iron oxide, combination of catalyst layer containing ceria and catalyst layer containing iron oxide, catalyst layer containing alumina and iron oxide A combination of a catalyst layer containing a catalyst, a combination of a catalyst layer containing titania and a catalyst layer containing alumina, a combination of a catalyst layer containing a noble metal and a catalyst layer containing silica, a catalyst layer containing a noble metal and a zeolite Less than the combination of the catalyst layers to be used and the combination of the catalyst layer containing the basic material and the catalyst layer containing the noble metal. Honeycomb catalyst according to claim 1 or 2, characterized in that also those which contain one combination.