JP2012200612A - Method for manufacturing honeycomb filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a honeycomb filter capable of enhancing the continuous regeneration performance.SOLUTION: The honeycomb filter 20, with its one end opened and the other end sealed, is formed with a collection layer 24 for collecting/removing solid components included in fluid on a porous partition wall part 22 forming a plurality of cells 23 which becomes flow passages of the fluid. In the partition wall part 22 and the collection layer 24, at least the collection layer 24 has a catalyst. The invention forms a collection layer raw material and a catalyst material at the same time on the partition wall part 22 by contacting with a slurry including a collection layer raw material forming the collection layer and a catalyst material having a catalyst component.

Description

  The present invention relates to a method for manufacturing a honeycomb filter.

  Conventionally, as a honeycomb filter, a cell in which one end is opened and the other end is plugged and a cell in which one end is plugged and the other end is opened alternately A porous partition wall formed so as to be disposed, and a collection layer that is a layer that is formed on the partition wall and collects particulate matter (hereinafter also referred to as PM) contained in the exhaust gas. Things are known. Moreover, in such a thing, what supported the catalyst and improved the exhaust gas purification performance is known.

  As a manufacturing method of such a honeycomb filter, there is a manufacturing method in which a collecting layer is formed and bonded on the partition walls of the honeycomb structure, and then a catalyst component is coated by a method such as dipping or suction, followed by drying and heat treatment. It has been proposed (see, for example, Patent Document 1).

JP 2010-214335 A

  By the way, in such a honeycomb filter, for example, a “regeneration process” for recovering the function of the filter by burning the collected PM may be performed. However, when the honeycomb filter obtained by the manufacturing method described above is used, the performance of restoring the filter function in the regeneration process may not be sufficient yet, and it has been desired to further improve the continuous reproducibility.

  This invention is made | formed in view of such a subject, and it aims at providing the manufacturing method of the honey-comb filter which can improve continuous reproducibility more.

  The present invention adopts the following means in order to achieve the main object described above.

The method for manufacturing the honeycomb filter of the present invention includes:
A method for manufacturing a honeycomb filter for collecting a solid component contained in a fluid,
A solid component contained in a fluid in a honeycomb structure having a plurality of porous partition walls that are open at one end and plugged at the other end to form a plurality of cells serving as fluid flow paths. The collection layer raw material for forming the collection layer, which is a layer for collecting the catalyst, and the slurry containing the catalyst material having the catalyst component are brought into contact with each other, and the collection layer raw material and the catalyst material are simultaneously formed on the partition wall portion. Collecting layer raw material-catalyst material simultaneous forming step,
Is included.

  In this honeycomb filter manufacturing method, the collection layer material and the catalyst material are simultaneously formed in the partition wall. In this manufacturing method, the continuous reproducibility in the honeycomb filter can be further improved. The reason for this is not clear, but is considered as follows. When the slurry containing the catalyst material is brought into contact with the partition wall portion on which the collection layer raw material has been formed in advance, the catalyst material is placed in the pores of the collection layer or at the boundary portion between the collection layer and the partition wall when contacting the catalyst material. The gas flow path may be blocked by agglomeration or agglomerated catalyst material. On the other hand, in the manufacturing method of the present invention, since the collection layer raw material and the catalyst material are simultaneously formed in the partition wall, aggregation of the catalyst material and blockage of the gas flow path can be suppressed. And since aggregation of a catalyst material can be suppressed, the surface area of a catalyst material becomes large, and it is thought that a catalyst function can be exhibited more efficiently. Further, since the blockage of the gas flow path can be further suppressed, it is considered that the PM can be burned more efficiently by circulating a high-temperature gas more efficiently during the regeneration process. Here, the continuous reproducibility refers to the ability to regenerate the honeycomb filter by continuously reducing the soot accumulated on the honeycomb filter in the regeneration process.

  In the method for manufacturing a honeycomb filter of the present invention, the collection layer material may have an average particle size of 2 μm or more and 7 μm or less. By so doing, it is possible to further suppress an increase in pressure loss in the honeycomb filter. Here, the average particle diameter means a median diameter (D50) obtained by measuring raw material particles using water as a dispersion medium using a laser diffraction / scattering particle size distribution measuring apparatus.

  In the method for manufacturing a honeycomb filter of the present invention, the partition wall material is one or more of silicon carbide, silicon nitride, cordierite, mullite, and aluminum titanate, and the collection layer material is silicon carbide. In addition, any one or more of silicon nitride, cordierite, mullite, and aluminum titanate may be included.

  In the method for manufacturing a honeycomb filter of the present invention, the collection layer material may be the same type as the material of the partition wall. By doing so, it is considered that the thermal expansion coefficients of the collection layer and the partition wall can be made equal, and the separation between the partition wall and the collection layer due to thermal expansion and contraction can be further suppressed. Here, the same type may be classified into the same component system, for example. Such component systems can be classified into, for example, silicon carbide, silicon nitride, cordierite, mullite, aluminum titanate, and the like.

  In the honeycomb filter manufacturing method of the present invention, in the collection layer raw material-catalyst material simultaneous forming step, one end of the honeycomb structure is brought into contact with the slurry containing the collection layer raw material and the catalyst material, The trapping layer raw material and the catalyst material may be simultaneously formed in the partition wall by suction from the other end of the honeycomb structure. If it carries out like this, manufacturing cost can be suppressed by performing formation of a collection layer raw material and formation of a catalyst material simultaneously. In addition, the catalyst material can be efficiently supported on the collection layer raw material serving as the aggregate of the collection layer. Furthermore, the formation amount of the slurry containing the collected raw material and the catalyst material can be adjusted more easily. Furthermore, the catalyst material can be efficiently formed inside the partition wall. Note that when one end of the honeycomb structure is brought into contact with the slurry containing the collection raw material and the catalyst material, the end of the honeycomb structure may be immersed in the slurry, or the slurry may start from the end of the honeycomb structure. May be poured, or slurry may be sprayed onto the end of the honeycomb structure.

  In the honeycomb filter manufacturing method of the present invention, in the trapping layer raw material-catalyst material simultaneous forming step, the honeycomb structure is immersed in a slurry containing the trapping layer raw material and the catalyst material and trapped in the partition wall. It is good also as what forms a layer collection raw material and a catalyst material simultaneously. In this way, the collection layer material and the catalyst material can be more easily formed on the partition walls of the honeycomb structure.

  The method for manufacturing a honeycomb filter according to the present invention is the above-described method for manufacturing a honeycomb filter, and includes a heat treatment step of performing a heat treatment for fixing the formed collection layer material and the catalyst material on the partition wall. preferable. By so doing, the formed collection layer material and catalyst material can be more firmly fixed to the partition walls of the honeycomb structure. Here, fixing means that the trapping layer raw material and the catalyst material are held in the partition walls of the honeycomb structure to such an extent that they are not separated from the honeycomb filter. The collection layer material and the catalyst material may be directly or indirectly fixed to the partition walls of the honeycomb structure. Even in this case, the formed trapping layer material and the catalyst material can be more firmly fixed to the partition walls of the honeycomb structure.

  In such a method for manufacturing a honeycomb filter of the present invention, in the heat treatment step, the heat treatment may be performed at a heat treatment temperature of 500 ° C. or higher and 750 ° C. or lower. If it is 500 degreeC or more, a collection layer raw material and a catalyst material can be more stably fixed to the partition part of a honeycomb structure. Moreover, if it is 750 degrees C or less, the density of a collection layer can be made more suitable, and aggregation of a catalyst can be suppressed more.

An explanatory view showing an example of an outline of composition of honeycomb filter 20. FIG. An explanatory view showing an example of an outline of composition of honeycomb filter. Explanatory drawing which shows the outline of a structure of the collection layer raw material-catalyst material simultaneous formation apparatus 50. FIG. The graph which shows the relationship between the particle diameter of a collection layer raw material, pressure loss, and regeneration efficiency.

  Next, modes for carrying out the present invention will be described with reference to the drawings. A honeycomb filter obtained by the production method of the present invention (hereinafter also referred to as a honeycomb filter of the present invention) is disposed in an exhaust pipe of an engine for purifying an exhaust of an automobile engine, for example. The solid component (particulate matter, hereinafter also referred to as PM) contained is collected and removed. In this honeycomb filter, when the amount of collected PM reaches a predetermined value, a process (regeneration process) for burning the collected PM by increasing the fuel concentration is executed.

  An embodiment of the honeycomb filter of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a honeycomb filter 20 according to an embodiment of the present invention. As shown in FIG. 1, the honeycomb filter 20 of the present embodiment has a shape in which the outer peripheral surfaces of two or more honeycomb segments 21 having partition walls 22 are bonded to each other by a bonding layer 27, and the outer peripheral protection portion is formed on the outer periphery thereof. 28 is formed. The honeycomb filter 20 has a porous partition wall in which one end portion is opened and the other end portion is plugged by a plugging portion 26 to form a plurality of cells 23 serving as exhaust gas flow paths as fluid. And a collection layer 24 that is a layer that is formed on the partition wall 22 and collects a solid component (PM) contained in the fluid (exhaust gas). Further, at least the collection layer 24 of the partition wall 22 and the collection layer 24 has a catalyst. In the honeycomb segment 21, the partition wall 22 includes a cell 23 having one end opened and the other end plugged, and a cell 23 having one end plugged and the other end opened. Are alternately arranged. Further, in the honeycomb filter 20, the exhaust gas that has entered the cell 23 (also referred to as an inlet side cell) having an opening on the inlet side passes through the collection layer 24 and the partition wall 22, and the cell 23 (the outlet side cell) having an opening on the outlet side. The PM contained in the exhaust gas is collected on the collection layer 24 at this time.

  The outer shape of the honeycomb filter 20 is not particularly limited, but may be a columnar shape, a quadrangular columnar shape, an elliptical columnar shape, a hexagonal columnar shape, or the like. The outer shape of the honeycomb segment 21 is not particularly limited, but preferably has a flat surface that can be easily joined, and can have a polygonal prismatic shape (such as a quadrangular prism shape or a hexagonal prism shape). The cell may have a cross-sectional shape of a polygon such as a triangle, a quadrangle, a hexagon, and an octagon, a streamline shape such as a circle and an ellipse, and a combination thereof. For example, the cell 23 may have a quadrangular cross section perpendicular to the flow direction of the exhaust gas. Here, the case where the outer shape of the honeycomb filter 20 is formed in a cylindrical shape, the outer shape of the honeycomb segment 21 is formed in a rectangular column shape, and the cells 23 are formed in a rectangular shape will be mainly described.

  The partition wall 22 is porous, for example, cordierite, Si-bonded SiC, recrystallized SiC, aluminum titanate, mullite, silicon nitride, sialon, zirconium phosphate, zirconia, titania, alumina, and silica. It may be formed including one or more inorganic materials. Among these, at least one of silicon carbide, silicon nitride, cordierite, mullite, and aluminum titanate is preferable, and cordierite, Si-bonded SiC, recrystallized SiC, and the like are more preferable. The partition wall 22 preferably has a porosity of 30% by volume to 85% by volume, and more preferably 35% by volume to 65% by volume. The partition wall 22 preferably has an average pore diameter in the range of 10 μm to 60 μm. This porosity and average pore diameter shall mean the result measured by the mercury intrusion method. The partition wall 22 has a thickness of preferably 150 μm or more and 600 μm or less, and more preferably 200 μm or more and 400 μm or less. If the thickness is 150 μm or more, the mechanical strength can be increased, and if it is 600 μm or less, the pressure loss can be further reduced. When the partition wall portion 22 is formed with such a porosity, average pore diameter, and thickness, the exhaust gas easily passes and PM is easily collected.

  The collection layer 24 is a layer for collecting PM contained in the exhaust gas, and is formed on the partition wall portion 22 by a group of particles having an average particle size smaller than the average pore diameter of the partition wall portion 22. Also good. The collection layer 24 preferably has an average pore diameter of 0.2 μm or more and 10 μm or less, and preferably has a porosity of 40 volume% or more and 95 volume% or less, and the average particle size of the particles constituting the collection layer The diameter is preferably 0.5 μm or more and 15 μm or less. If the average pore diameter is 0.2 μm or more, it is possible to suppress an excessive initial pressure loss in which no PM is deposited. If the average pore diameter is 10 μm or less, the PM collection efficiency is improved. It is possible to suppress PM from passing through the layer 24 and into the pores, and it is possible to suppress deterioration in pressure loss during PM deposition. Further, when the porosity is 40% by volume or more, it is possible to suppress an excessive initial pressure loss in which PM is not deposited, and when the porosity is 95% by volume or less, the durable collection layer 24 is used. A surface layer can be produced. Moreover, if the average particle size of the particles constituting the collection layer is 0.5 μm or more, the size of the space between the particles of the particles constituting the collection layer can be sufficiently secured, so that the permeability of the collection layer can be increased. It is possible to maintain a rapid pressure loss increase, and if it is 15 μm or less, there is a sufficient contact point between the particles, so that sufficient bond strength between the particles can be secured and the separation layer peel strength can be secured. Can be secured. As described above, it is possible to maintain good PM collection efficiency, prevent a sudden pressure loss increase immediately after the start of PM collection, reduce pressure loss during PM deposition, and durability of the collection layer.

  The collection layer 24 may be formed on the partition wall 22 of the inlet side cell and the outlet side cell of the exhaust gas, but is formed on the partition wall 22 of the inlet side cell as shown in FIG. It is preferable that the outlet side cell is not formed. In this way, the pressure loss can be further reduced and PM contained in the fluid can be removed more efficiently. In addition, the honeycomb filter 20 can be easily manufactured.

  The collection layer 24 is formed by including one or more inorganic materials of cordierite, silicon carbide, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica. It is good as it is. Among these, at least one of silicon carbide, silicon nitride, cordierite, mullite, and aluminum titanate is preferable. At this time, the collection layer 24 is preferably formed of the same material as the material of the partition wall 22. The collection layer 24 more preferably contains 10% by weight or more of ceramic or metal inorganic fibers. In this way, the strength of the collection layer can be increased. Moreover, it is easy to collect PM by fiber. The collection layer 24 may be formed by including one or more materials in which the inorganic fibers are selected from aluminosilicate, alumina, silica, zirconia, ceria, and mullite. In addition, the average particle diameter of the particle group of the collection layer 24 was obtained by observing the collection layer 24 with a scanning electron microscope (SEM) and measuring each particle of the collection layer 24 included in the photographed image. It shall mean the average value.

In the honeycomb filter 20, at least the collection layer 24 of the partition walls 22 and the collection layer 24 has a catalyst. This catalyst is at least one of a catalyst that oxidizes unburned gas (HC, CO, etc.) contained in exhaust gas, a catalyst that promotes combustion of collected PM, and a catalyst that occludes, adsorbs or decomposes NO _x. It is good. By so doing, it is possible to efficiently oxidize unburned gas, to efficiently remove PM, to efficiently decompose NO _x, and the like.

  The bonding layer 27 is a layer for bonding the honeycomb segments 21 and may include inorganic particles, inorganic fibers, a binder, and the like. The inorganic particles can be the particles of the inorganic material described above, and the average particle diameter is preferably 0.1 μm or more and 30 μm or less. The inorganic fiber may be as described above. For example, the average diameter is preferably 0.5 μm to 8 μm, and the average length is preferably 100 μm to 500 μm. As the binder, colloidal silica or clay can be used. The bonding layer 27 is preferably formed in a range of 0.5 mm to 2 mm. In addition, an average particle diameter shall mean the median diameter (D50) measured using the laser diffraction / scattering type particle size distribution measuring apparatus and water as a dispersion medium. The outer periphery protection part 28 is a layer that protects the outer periphery of the honeycomb filter 20 and may include the above-described inorganic particles, inorganic fibers, a binder, and the like.

  Next, a method for manufacturing the honeycomb filter 20 will be described. The method for manufacturing the honeycomb filter 20 includes, for example, a partition wall that forms a porous partition wall portion 22 in which one end portion is opened and the other end portion is plugged to form a plurality of cells serving as fluid flow paths. A trapping layer raw material for forming a trapping layer 24, which is a layer for trapping a solid component contained in a fluid, in a honeycomb structure 29 including a partition wall portion 22, and a catalyst material having a catalyst component; , And simultaneously forming the collection layer material and the catalyst material on the partition wall 22, and the formed collection layer material and the catalyst material together with the partition wall. And a heat treatment step for performing heat treatment for fixing to the portion.

[Partition wall forming step]
In this step, the raw material for the partition wall 22 is mixed, and the partition wall 22 is molded by a predetermined molding method. Here, the partition wall 22 is formed along with the formation of a honeycomb formed body that is a formed body before the collection layer 24 is formed and before firing. As a raw material for the partition wall 22, for example, a base material, a pore former, and a dispersion medium may be mixed to prepare clay or slurry. As a base material, the inorganic material mentioned above can be used. For example, in the case of using silicon carbide as a base material, silicon carbide powder and metal silicon powder are mixed at a mass ratio of 80:20, a dispersion medium such as water and a pore former are added, and an organic binder or the like is further added thereto. Can be added and kneaded to form a plastic clay. The means for preparing the kneaded material by kneading the silicon carbide powder and the metal silicon powder raw material (molding raw material) is not particularly limited, and examples thereof include a method using a kneader or a vacuum kneader. As the pore former, those that burn after firing are preferable. For example, starch, coke, foamed resin, and the like can be used. You may add a binder, a dispersing agent, etc. to this clay suitably. As the binder, for example, an organic binder such as cellulose is preferably used. As the dispersant, a surfactant such as ethylene glycol can be used. For example, the partition wall 22 may be formed as a honeycomb formed body by extruding into an arbitrary shape described above using a mold having a shape in which the cells 23 are arranged side by side. Then, the process which forms the plugging part 26 in a honeycomb molded object is performed. The plugged portion 26 includes a cell 23 in which one end is opened and the other end is plugged, and a cell 23 in which one end is plugged and the other end is opened. Are preferably alternately arranged. As a raw material used for plugging, a raw material for forming the partition wall 22 described above may be used. The obtained honeycomb formed body is preferably subjected to a drying treatment, a calcination treatment, and a firing treatment. The calcination process is a process of burning and removing organic components contained in the honeycomb formed body at a temperature lower than the firing temperature. The firing temperature can be 1400 ° C. to 1450 ° C. for cordierite raw material, and 1450 ° C. for Si-bonded SiC. Through such a process, the honeycomb structure before forming the collection layer 24 can be obtained. The honeycomb structure here may be one that forms the honeycomb segment 21 or may form the honeycomb filter 20 in which a plurality of honeycomb segments 21 are joined.

[Collecting layer raw material-catalyst material simultaneous formation process]
In this step, a honeycomb structure having a plurality of porous partition walls forming a plurality of cells that are open at one end and plugged at the other end to form a fluid flow path, A slurry containing a collection layer raw material for forming a collection layer, which is a layer for collecting the contained solid component, and a catalyst material having a catalyst component is brought into contact, and the collection layer material and the catalyst material are brought into contact with the partition wall 22. And at the same time. This collection layer raw material and catalyst material constitute the honeycomb filter 20 as the collection layer 24 and the catalyst by drying or heat treatment described later.

  In the method for manufacturing a honeycomb filter of the present invention, the slurry having the collection layer material and the catalyst material may be obtained by dispersing the collection layer material and the catalyst material in a dispersion medium. Also, the catalyst material may be dispersed in the collection layer slurry in which the collection layer material is dispersed in the dispersion medium, or the collection layer is dispersed in the catalyst slurry in which the catalyst material is dispersed in the dispersion medium. It is good. As the dispersion medium, water, alcohol or the like can be suitably used.

  The collection layer material is preferably one containing one or more inorganic materials of cordierite, silicon carbide, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica, It is preferably one or more of silicon carbide, silicon nitride, cordierite, mullite, and aluminum titanate. Moreover, it is preferable that the collection layer raw material is the same type as the material of the partition wall. This is because it is considered that the thermal expansion coefficient of the collection layer and the partition wall can be made equal, and the separation between the partition wall and the collection layer due to thermal expansion and contraction can be further suppressed. . The inorganic material may be fibrous or particulate. More preferably, the inorganic material contains 10% by weight or more of ceramic or metal inorganic fibers. In this way, the strength of the collection layer can be increased. Moreover, it is easy to collect PM by fiber. Moreover, it is good also as a thing containing a binder, a binder, a dispersing agent, etc. besides the collection layer raw material. As the binder, colloidal silica, clay, or the like can be used. As the binder, for example, a cellulose organic binder is preferably used. As the dispersant, a surfactant such as ethylene glycol can be used.

  The average particle diameter of the collection layer material is not particularly limited, but is preferably 30 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. This is because if the thickness is 30 μm or less, a collection layer 24 sufficient to collect PM can be obtained. Moreover, it is because continuous reproducibility can be improved. Moreover, the average particle diameter of the collection layer material is preferably 0.5 μm or more, more preferably 1 μm or more, and further preferably 2 μm or more. In particular, the average particle size of the collection layer material is preferably 2 μm or more and 7 μm or less. By so doing, continuous reproducibility can be further improved, and an increase in pressure loss in the honeycomb filter can be further suppressed.

The catalyst material has a catalyst component. As the catalyst component, for example, it is more preferable to include one or more kinds of noble metal elements and transition metal elements. Moreover, another catalyst component and a purification | cleaning material component may be included. For example, alkali metal (Li, Na, K, Cs) or alkaline earth metal (Ca, Ba, Sr, etc.) NO _X storage catalyst, including at least one rare earth metal, transition metal, the three-way catalyst, cerium Examples thereof include a promoter represented by at least one oxide of (Ce), zirconium (Zr), and titanium (Ti), and an HC (Hydro Carbon) adsorbent. Specifically, examples of the noble metal include platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), gold (Au), and silver (Ag). Examples of the transition metal contained in the catalyst include Mn, Fe, Co, Ni, Cu, Zn, Sc, Ti, V, and Cr. Examples of rare earth metals include Sm, Gd, Nd, Y, La, Pr, and the like. Examples of the alkaline earth metal include Mg, Ca, Sr, Ba and the like. Of these, platinum and palladium are more preferred. If it has a catalyst component that promotes combustion of PM, the PM collected on the collection layer 24 can be removed more easily, and a catalyst that oxidizes unburned gas (hereinafter referred to as DOC; Diesel). Assuming having Oxidation also referred to as catalyst) and NO _X decomposing catalyst component, it is possible to further purify the exhaust gas.

Among these, the catalyst component preferably contains DOC. This is because continuous reproducibility can be further improved. The reason is presumed as follows. As described above, in the production method of the present invention, since the collection layer raw material and the catalyst material are simultaneously formed on the partition wall, aggregation of the catalyst material and blockage of the gas flow path can be suppressed. For this reason, it is possible to efficiently coat the catalyst around the ceramic raw material that forms the collection layer by suppressing the aggregation of the catalyst material, and efficiently in the region near the surface of the collection layer where PM is deposited. Can be oxidized. For this reason, it is considered that NO ₂ back diffusion is promoted as shown below, and continuous reproducibility is improved. Here, a mechanism for improving the continuous reproducibility by NO ₂ back diffusion will be described. In the regeneration process, NO contained in the exhaust gas is oxidized to NO ₂ by the DOC, but this NO ₂ reacts with the PM deposited on the surface of the partition wall 22 to burn the PM. Although NO ₂ is converted to NO by the reaction with PM, it is oxidized by the catalyst carried on the partition wall and becomes NO ₂ again. Accordingly, a concentration distribution of NO-NO ₂ is formed in the thickness direction of the partition wall portion 22, and in order to balance the NO-NO ₂ concentration in the vicinity of the PM layer where the NO ₂ concentration is reduced, the inlet side cell to the outlet side The NO ₂ flowing through the partition wall 23 toward the cell moves toward the inlet side cell where PM having a low NO ₂ concentration is deposited (reverse diffusion), and the NO ₂ reacts with the PM again to reduce the PM. Let Thus, it is thought that continuous reproducibility can be improved more by reducing PM efficiently. The noble metal, transition metal, co-catalyst, etc., which are catalyst components, may be supported on a carrier having a large specific surface area. The carrier is preferably, for example, at least one of Al oxide, Ti oxide, Ce oxide, Zr oxide, and Si oxide, among alumina, silica alumina, titania, ceria, and zirconia. More preferably, it contains at least one of the above.

  In this step, one end of the honeycomb structure 29 is brought into contact with the slurry containing the collection layer raw material and the catalyst material, and is sucked from the other end of the honeycomb structure 29 to be collected in the partition wall 22. It is good also as what forms a raw material and a catalyst material simultaneously. If it carries out like this, manufacturing cost can be suppressed by performing formation of a collection layer raw material and formation of a catalyst material simultaneously. In addition, the catalyst material can be efficiently supported on the collection layer raw material serving as the aggregate of the collection layer. Furthermore, the formation amount of the slurry containing the collected raw material and the catalyst material can be adjusted more easily. Furthermore, the catalyst material can be efficiently formed inside the partition wall. At this time, it is preferable to suck from the outlet side of the cell 23. In this way, the communicating pores can be more efficiently secured in the partition wall portion 22 and the collection layer 24, and the formation of aggregates between the collection layer raw material and the catalyst material can be suppressed. Can be further suppressed. Moreover, since a collection layer can be formed in the partition part of the cell on the inlet side and PM can be collected in the cell on the inlet side, pressure loss can be further suppressed. When one end of the honeycomb structure 29 is brought into contact with the slurry containing the collection layer raw material and the catalyst material, the end of the honeycomb structure may be immersed in the slurry, or the end of the honeycomb structure may be immersed in the slurry. Alternatively, the slurry may be poured or the slurry may be sprayed onto the end of the honeycomb structure. Moreover, after forming a slurry, it is preferable to remove and dry an excess slurry. By doing so, a desired amount of the collecting layer can be formed. The drying method is not particularly limited, and conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying and the like can be used. Especially, the drying method which combined hot air drying, microwave drying, or dielectric drying is preferable at the point which can dry the whole molded object rapidly and uniformly.

[Heat treatment process]
In this step, heat treatment is performed to fix the collection layer material and the catalyst material formed as described above to the partition wall 22. By so doing, the formed collection layer material and catalyst material can be more firmly fixed to the partition walls of the honeycomb structure. Here, fixing means that the trapping layer raw material and the catalyst material are held in the partition walls of the honeycomb structure to such an extent that they are not separated from the honeycomb filter. The collection layer material and the catalyst material may be directly or indirectly fixed to the partition walls of the honeycomb structure. Even in this case, the formed collection layer raw material and the catalyst material can be more firmly fixed to the partition walls of the honeycomb structure.

  In this step, it is preferable to perform the heat treatment at a heat treatment temperature of 200 ° C. or higher and 900 ° C. or lower. When the heat treatment temperature is 200 ° C. or higher, the contained organic substances can be sufficiently removed, and when the heat treatment temperature is 900 ° C. or lower, pore reduction can be suppressed. Among these, it is more preferable to perform the heat treatment at a heat treatment temperature of 500 ° C. or higher and 750 ° C. or lower. If it is 500 degreeC or more, a collection layer raw material and a catalyst material can be more stably fixed to the partition part of a honeycomb structure. Moreover, if it is 750 degrees C or less, the density of a collection layer can be made more suitable, and aggregation of a catalyst can be suppressed more.

  According to the honeycomb filter manufactured by the manufacturing method of the embodiment described above, since the collection layer raw material and the catalyst material are simultaneously formed in the partition wall 22, the continuous reproducibility can be further improved.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the honeycomb filter 20 is formed by bonding the honeycomb segments 21 with the bonding layer 27. However, as shown in FIG. In the honeycomb filter 40, the partition wall portion 42, the cell 43, the collection layer 44, the plugging portion 46, the outer periphery protection portion 48, and the like are the partition wall portion 22, the cell 23, the collection layer 24, and the plugging portion of the honeycomb filter 20. 26 and the outer periphery protection part 28 can be set as the same structure. Even if it does in this way, continuous reproducibility can be improved more.

  In the above-described embodiment, the honeycomb filter 20 for automobiles has been described. However, the honeycomb filter 20 is not particularly limited as long as it collects a solid component contained in a fluid, and may be a honeycomb filter for a power generation engine. A honeycomb filter for equipment may be used.

  In the embodiment described above, in the collection layer raw material-catalyst material simultaneous forming step, one end of the honeycomb structure 29 is brought into contact with the slurry containing the collection layer raw material and the catalyst material, and the other of the honeycomb structure 29 is contacted. The trapping layer raw material and the catalyst material are simultaneously formed in the partition wall 22 by sucking from the end portion. However, the honeycomb structure 29 is immersed in the slurry containing the trapping layer raw material and the catalyst material, and the partition wall The collection layer material and the catalyst material may be simultaneously formed in the portion 22. In this way, the collection layer material and the catalyst material can be more easily formed on the partition walls of the honeycomb structure. Moreover, it is good also as what forms the collection layer raw material and catalyst material on the partition part 22 simultaneously by pumping a slurry from the inlet side of the cell 23. Even in this case, the collection layer raw material and the catalyst material can be formed on the partition walls of the honeycomb structure.

  In the embodiment described above, the partition wall forming step is included, but the partition wall forming step may not be included. For example, a honeycomb structure prepared in advance may be used. In the above-described embodiment, the heat treatment step is included, but the heat treatment step may be omitted.

  Below, the example which manufactured the honey-comb filter concretely is demonstrated as an Example. Here, a honeycomb filter having a structure in which a plurality of honeycomb segments were joined was produced.

[Examples 1 to 6]
(1) Production of honeycomb segment Silicon carbide powder and metal silicon powder are mixed at a mass ratio of 80:20, and methyl cellulose and hydroxypropoxyl methyl cellulose, a surfactant and water are added and kneaded to form a plastic clay. And extruding the kneaded material using a predetermined mold to form a honeycomb segment molded body having a desired shape. Here, the partition wall was formed into a shape having a thickness of 305 μm, a cell pitch of 1.47 mm, a cross section of 35 mm × 35 mm, and a length of 152 mm. Next, the obtained honeycomb segment formed body was dried by microwave, further dried with hot air, plugged, calcined in an oxidizing atmosphere at 550 ° C. for 3 hours, and then inert atmosphere The main baking was performed under the conditions of 1400 ° C. and 2 hours below. The plugging portion is formed by alternately masking the cell opening on one end face of the segment molded body, immersing the masked end face in a plugging slurry containing a silicon carbide raw material, and plugging the opening and the plugging. The parts were arranged alternately. Similarly, the other end face is also masked so that one open and the other plugged cell and the one plugged and the other open cell are alternately arranged. Part was formed.

(2) Bonding, outer periphery processing, outer periphery coating After applying a slurry for bonding formed by kneading alumina silicate fiber, colloidal silica, polyvinyl alcohol, silicon carbide, and water to the side surfaces of the honeycomb segment, and assembling and crimping each other, Drying with hot air yielded a bonded honeycomb segment assembly having a square overall shape. Further, after the honeycomb segment bonded body was ground into a cylindrical shape, the periphery thereof was coated with a slurry for outer periphery coating made of the same material as the bonding slurry, and dried. Furthermore, a cylindrical honeycomb structure having a desired shape, segment shape, and cell structure was obtained by curing by heat treatment at 700 ° C. for 30 minutes. Here, the honeycomb structure has a cross-sectional diameter of 144 mm and a length of 152 mm.

(3) Collection layer raw material-catalyst material simultaneous formation A catalyst slurry obtained by mixing alumina as a catalyst base material carrying Pt as a catalyst component, and Ce oxide and nitric acid as catalyst aids (promoter) in water. The average particle size is 1 μm (Example 1), 2 μm (Example 2), 4 μm (Example 3), 6 μm (Example 4), and 7 μm (Example 5). , 8 μm (Example 6) of silicon carbide was added to obtain a slurry (hereinafter also referred to as a mixed slurry) containing the collection layer raw material and the catalyst material. Next, a honeycomb structure 29 in which the collection layer raw material and the catalyst material were formed on the partition walls was formed using the forming apparatus 50 shown in FIG. First, one end of the manufactured honeycomb structure 29 was fixed to the jig 51, and the supply fixing cylinder 54 was fixed to the other end of the honeycomb structure 29. A through hole 52 is formed in the center of the jig 51. A supply port 53 for supplying slurry is formed at the tip of the supply fixing cylinder 54. Between the supply fixing cylinder 54 and the honeycomb structure 29, a supply amount adjusting plate 56 for adjusting the supply amount of the slurry is disposed. Next, the supply amount adjustment plate 56 is fixed at a position obtained empirically in advance so that a predetermined film thickness is formed, and the mixed slurry is pumped from the supply port 53 to form the plugging portion 26 on the supply port 53 side. The mixed slurry was supplied to the inside of the cells of the honeycomb structure that had not been formed (the left diagram in FIG. 3). Next, the through hole 52 of the jig 51 was sucked, and water as a solvent of the mixed slurry was discharged through the partition wall 22 (center view in FIG. 3). At this time, the solid content of the mixed slurry remained in the cell 23 having an opening on the supply fixing cylinder 54 side, and the collection layer material and the catalyst material were formed on the partition wall. At this time, the Pt component was adjusted to 1.06 g / L with respect to the honeycomb filter.

(4) Drying / heat treatment The excess slurry is removed by air blow, drying is performed at 150 ° C. for 1 hour, and then heat treatment is performed at 650 ° C. for 2 hours to fix the collection layer material and the catalyst material to the honeycomb structure. (Right figure in FIG. 13). In this way, honeycomb filters of Examples 1 to 6 were obtained.

[Comparative Example 1]
(1) Manufacture of honeycomb segment Since it is the same as that of the manufacture of the honeycomb segment about Example 1-6 mentioned above, description is abbreviate | omitted.

(2) Bonding and outer periphery processing A slurry for kneading kneaded alumina silicate fiber, colloidal silica, polyvinyl alcohol, silicon carbide, and water is applied to the side surface of the honeycomb segment, and after assembling and pressure-bonding, hot air drying is performed. Thus, a bonded honeycomb segment assembly having an overall shape of a quadrangle was obtained. Further, the joined honeycomb segment assembly was ground into a cylindrical shape.

(3) Collection layer raw material single formation 2.5% by mass of silicon carbide (average particle size 2 μm) as inorganic particles, 0.5% by mass of carboxymethyl cellulose as an organic binder, and 2% of colloidal silica as a binder % And water as a dispersion medium were mixed so as to be 95% by mass to obtain a slurry for forming a collection layer (hereinafter also referred to as a collection layer slurry). Next, the honeycomb structure 29 in which the collection layer raw material was formed in the partition walls was manufactured using the forming apparatus 50 shown in FIG. A honeycomb segment is used in place of the honeycomb structure, and the trapping layer slurry is used instead of the mixed slurry. A collection layer material was formed.

(4) Outer peripheral coat The excess slurry was removed by air blow and dried with hot air. Further, after the honeycomb segment bonded body was ground into a cylindrical shape, the periphery thereof was coated with a slurry for outer periphery coating made of the same material as the bonding slurry, and dried. Furthermore, a cylindrical honeycomb structure having a desired shape, segment shape, and cell structure was obtained by curing by heat treatment at 700 ° C. for 30 minutes. Here, the honeycomb structure has a cross-sectional diameter of 144 mm and a length of 152 mm.

(5) Single formation of catalyst material A catalyst obtained by mixing alumina (Al ₂ O ₃ ) as a catalyst base material carrying Pt as a catalyst component, and Ce oxide and nitric acid as catalyst aids (promoter) in water. A slurry was prepared. Next, the Pt component was supported on the honeycomb filter so as to be 1.06 g / L. The catalyst was supported by allowing the catalyst slurry to flow into the cell (outlet side cell) from the end of the honeycomb filter on the exhaust gas outflow side so that a large amount of catalyst was present on the partition walls.

(6) Drying / heat treatment The excess slurry is removed by air blow, drying is performed at 150 ° C. for 1 hour, and then heat treatment is performed at 650 ° C. for 2 hours to fix the collection layer material and the catalyst material to the honeycomb structure. It was. In this way, a honeycomb filter of Comparative Example 1 was obtained.

[Pressure loss evaluation test]
The honeycomb filter manufactured as described above is attached to the exhaust system of a 2.2 L diesel engine using an engine bench, and the torque is changed from 500 rpm to 1000 rpm in increments of 500 rpm for 3 minutes at full load. Retained. And the pressure loss performance (pressure loss performance) at the time of the full load with respect to each rotation speed was evaluated. And the pressure loss value (pressure loss value, kPa) after hold | maintaining for 3 minutes at the rotation speed of 4000 rpm was calculated | required.

[Continuous regeneration evaluation test]
The honeycomb filter manufactured as described above is attached to the exhaust system of a 2.2 L diesel engine using an engine bench, 8 g / L soot is deposited, and the DPF inlet is kept at a constant speed of 2000 rpm. The gas temperature was kept at 400 ° C. for 20 minutes. Then, the weight of the honeycomb filter before and after the test is measured to determine the weight difference, and the ratio of the combustion amount (weight reduction) to the soot deposition amount 8 g / L is calculated. This is the regeneration efficiency (%) in the continuous regeneration test. did.

[Experimental result]
FIG. 4 is a graph showing the relationship between the particle diameter of the collection layer material, the pressure loss, and the regeneration efficiency. The results are shown in Table 1. As shown in Table 1 and FIG. 4, in Examples 1 to 6 in which the collection layer raw material and the catalyst material were simultaneously formed, the regeneration efficiency was higher than that of Comparative Example 1 in which the collection layer raw material and the catalyst material were separately formed. It was good. From this, it was found that the continuous reproducibility can be further improved by simultaneous formation of the collection layer raw material and the catalyst material. Moreover, it turned out that pressure loss can be reduced more if the average particle diameter of a collection layer raw material is 2 micrometers or more and 7 micrometers or less at this time.

  20, 40 Honeycomb filter, 21 Honeycomb segment, 22, 42 Partition part, 23, 43 cell, 24, 44 Collection layer, 26, 46 Plugged part, 27 Bonding layer, 28, 48 Peripheral protection part, 29 Honeycomb structure Body, 50 collection layer raw material-catalyst material simultaneous forming device, 51 jig, 52 through hole, 53 supply hole, 54 supply fixed cylinder, 56 supply amount adjusting plate.

Claims (8)

A method for manufacturing a honeycomb filter for collecting a solid component contained in a fluid,
A solid component contained in a fluid in a honeycomb structure having a plurality of porous partition walls that are open at one end and plugged at the other end to form a plurality of cells serving as fluid flow paths. The collection layer raw material for forming the collection layer, which is a layer for collecting the catalyst, and the slurry containing the catalyst material having the catalyst component are brought into contact with each other, and the collection layer raw material and the catalyst material are simultaneously formed on the partition wall portion. Collecting layer raw material-catalyst material simultaneous forming step,
A method for manufacturing a honeycomb filter.   The method for manufacturing a honeycomb filter according to claim 1, wherein the collection layer material has an average particle size of 2 µm or more and 7 µm or less. The material of the partition wall is at least one of silicon carbide, silicon nitride, cordierite, mullite, aluminum titanate,
The collection layer material includes one or more of silicon carbide, silicon nitride, cordierite, mullite, and aluminum titanate.
The manufacturing method of the honey-comb filter of Claim 1 or 2. The collection layer raw material is the same kind as the material of the partition wall,
The manufacturing method of the honey-comb filter of any one of Claims 1-3. In the collection layer raw material-catalyst material simultaneous forming step, one end of the honeycomb structure is brought into contact with the slurry containing the collection layer raw material and the catalyst material, and suction is performed from the other end of the honeycomb structure. And simultaneously forming the collection layer raw material and the catalyst material in the partition wall,
The manufacturing method of the honey-comb filter of any one of Claims 1-4. In the trapping layer raw material-catalyst material simultaneous forming step, the honeycomb structure is immersed in a slurry containing the trapping layer raw material and the catalyst material to simultaneously form the trapping layer raw material and the catalyst material in the partition wall. To
The manufacturing method of the honey-comb filter of any one of Claims 1-4. A method for manufacturing a honeycomb filter according to any one of claims 1 to 6,
A heat treatment step for performing a heat treatment for fixing the formed trapping layer material and the catalyst material to the partition wall;
A method for manufacturing a honeycomb filter.   The method for manufacturing a honeycomb filter according to claim 7, wherein in the heat treatment step, heat treatment is performed at a heat treatment temperature of 500 ° C or higher and 750 ° C or lower.

Images