WO2007055033A1

WO2007055033A1 - Filter, exhaust gas purifying apparatus for internal combustion engine and exhaust gas purifying method

Info

Publication number: WO2007055033A1
Application number: PCT/JP2005/021189
Authority: WO
Inventors: Atsushi Kudo; Yukio Oshimi
Original assignee: Ibiden Co., Ltd.
Priority date: 2005-11-14
Filing date: 2005-11-14
Publication date: 2007-05-18

Abstract

Disclosed is a filter for purifying an exhaust gas discharged from an internal combustion engine, wherein an ash trap layer is provided in a cell on the exhaust gas inflow side. Consequently, the filter can have a longer life without sacrificing the filtration area or pressure loss by effectively accumulating ashes which are produced during regeneration of the filter.

Description

Specification

TECHNICAL FIELD The present invention relates to a filter, an exhaust gas purification device for an internal combustion engine, and an exhaust gas purification method.

The present invention relates to a filter for removing particulate matter in exhaust gas discharged from an internal combustion engine such as a diesel engine, an exhaust gas purification device using the filter, and an exhaust gas purification method performed using the device. In particular, the present invention proposes a technique characterized by a filter that can effectively remove the ash contained in the particulate matter at a specific location in the filter without causing a pressure loss.

Background art

In recent years, internal combustion engines mounted on automobiles, construction machines, etc. have been purifying exhaust gas by purifying harmful gas components such as nitrogen oxides (NOx) and hydrocarbons (HC) contained in the exhaust gas. It is normal. In particular, in the case of diesel engines, in addition to nitrogen oxides (NOx) and hydrocarbons (HG), so-called particulate matter (PM) such as soot and S0F (Solu- ble Organic Fraction) is used. It is also necessary to reduce i cu I ate Matter).

With such a technical background, various exhaust gas purification apparatuses for internal combustion engines have been proposed. For example, as an example of such an exhaust gas purification device, there is one in which a particulate filter for collecting particulate matter contained in the exhaust gas is provided in the exhaust passage. When a predetermined amount of particulate matter is collected, the filter raises the temperature of the filter by increasing the exhaust temperature of the engine or heating it using a beater, and the collected particulate matter is collected. It is intended to burn and remove.

However, in such a filter, after the particulate matter is burned and removed, the pore size of the exhaust passage in the filter is blocked by aggregation of an inorganic compound called ash that is generated as unburned matter. Exhaust pressure loss There was a problem of increased loss.

As used herein, ash refers to various additives and impurity components contained in the fuel and lubricating oil of an internal combustion engine that combine in the combustion chamber of the internal combustion engine or the filter to form various compounds, These compounds are produced by agglomeration of these compounds in the filter. For example, fuels and lubricating oils for internal combustion engines contain components such as sulfur, phosphorus, calcium, and magnesium, and the components contained in the lubricating oil and the components contained in the mixture are combined in the combustion chamber. and calcium sulfate (CAS0 _4), phosphoric acid Cal Shiu厶_{_{_{(Ca 3 (P0 4) 2}}} ), or compounds such as magnesium sulfate (MgSO ₄₎ generates, these compounds are aggregated with soot (C), Particulate matter will be formed. That is, sulfur and this has a characteristic that it is easy to be absorbed in the soot, on the filter, the sulfur absorbed with soot combines with cull Shiumu and magnesium in the exhaust gas, calcium sulfate (CAS0 ₄₎ or sulfuric acid Ma It generates Guneshiumu (MgSO ₄₎ compounds such as these compounds is to agglomerate in the ash.

As these ash components, other additives containing cerium, iron, etc. in fossil fuels are mixed, and the oxidation reaction is promoted by these additives (inorganic compounds), thereby achieving a regeneration temperature. (E.g., Japanese Patent Laid-Open No. 8-2 1 8 8 49, Japanese Patent Laid-Open No. 2 00 0-1 6 7 3 2 9, Japanese Patent Laid-Open No. 2 0 0 1-9 8 9 2 5) The compound resulting from the additive used in (see) is also ash.

In general, these ashes become less reactive when separated from the particulate matter during regeneration, and other ashes accumulate on the ash one after another when they accumulate in the exhaust gas passage (bottomed hole). There are characteristics. As a result, there was a problem that the pores in the partition walls of the filter were clogged, hindering the filter characteristics and increasing the pressure loss.

In order to solve such problems, it has been conventional to vibrate the filter. (See, for example, Japanese Utility Model Laid-Open No. 4 1 1 2 9 8 2 4 and Japanese Patent Laid-Open No. 8-2 8 2 4 7) and organic particles or metallic binder on the filter surface. There has been proposed a technique (see, for example, Japanese Patent Laid-Open No. 10-33932) in which ash is screened together with ceramic particles by adhering ash.

However, in these conventional technologies, the screened-off ash is accumulated in the longitudinal direction of the through-holes from the vicinity of the sealing portion of the honeycomb structure, so that the filtration area decreases as it is used. As a result, there is a problem that the life of the filter is shortened.

In addition, in order to prevent the accumulation of ash in the two-cam structure, a technique for flowing a cleaning gas from the opposite direction and collecting the cleaned ash outside the honeycomb structure has been proposed. However, there was a problem that it would become extremely complicated when trying to form such a system.

Further, as another conventional technique, a technique using a trapping material carrying a metal having an electronegativity equal to or lower than a predetermined component contained in a fuel and / or lubricating oil of an internal combustion engine is used. Has also been proposed (see, for example, Japanese Patent Application Laid-Open No. 2 00 1-1 2 2 2 9).

According to this prior art, a metal having a negative electronegativity equal to or lower than that of a predetermined component contained in the lubricating oil is preferably used as the trapping material, preferably a metal having a lower electronegativity than the predetermined component and a high ionization tendency. Since it is supported, it is used that the component to be bonded is not the predetermined component but is bonded to the metal having a low electronegativity.

Next, a technique for preventing the formation of ash by a filter in the downstream region by supporting a basic metal in the upstream region and converting it into a phosphate or a sulfate has been proposed (for example, Japanese Patent Laid-Open Publication No. 2000-208). 2—see 3 7 1 8 2 4).

With this technology, for example, potassium sulfate is more expensive than calcium sulfate. However, since the degree of aggregation is low, it can be easily decomposed and removed by using a high-temperature treatment or reducing atmosphere.

Further, as another conventional technique, a technique for bonding ceramic particles (silicon carbide or the like) with a glass is known (for example, Japanese Patent Laid-Open Nos. 61-265050, 8-1 6 5 1 7 1 and Japanese Patent Laid-Open No. 2 0 1-1 9 9 7 7). However, these technologies are intended to fabricate filters and are used to bond ceramic particles with glass, not to incorporate ash, and in such cases, glass melting of the joints is not possible. The problem is that the filter itself is destroyed instead.

However, as described above, the conventional technology disclosed in the above-mentioned patent document still has various problems that need to be solved.

Accordingly, an object of the present invention is to reduce the filter volume resulting from the accumulation of ash produced by the combustion of particulate matter in the exhaust gas in the filter, or the exhaust gas flow path (cell). The purpose is to propose a filter that does not cause clogging and does not cause the accompanying increase in pressure loss.

Another object of the present invention is not only the need for maintenance after replacement for a new product after a certain period of use, and removal for removal of an ash, but also a longer service life with a simple configuration. It is to propose a filter.

Still another object of the present invention is to propose an exhaust gas purification device and an exhaust gas purification method using the filter. Disclosure of the invention

Inventors have found that Ash is Obtaining the knowledge that the ruta is deposited sequentially from the rear (discharge side) of the cell, the removal of the ash accompanied by such a deposition phenomenon is not a method of physically peeling and removing as in the prior art. Developed the present invention based on the knowledge that it is effective to remove ash in a compact location in a filter while suppressing filter volume reduction and exhaust flow blockage. did.

That is, the present invention

(1) A filter for purifying exhaust gas discharged from an internal combustion engine, wherein an ash trap layer is provided in an exhaust gas inflow side cell of the filter,

(2) In an exhaust gas purification apparatus for an internal combustion engine, in which an exhaust gas flow path of the internal combustion engine is provided with a filter that collects particulate matter contained in the exhaust gas, an exhaust gas inflow side cell of the filter An exhaust gas purifying device for an internal combustion engine, characterized in that an ash trap layer is provided therein.

(3) In a method of collecting and purifying particulate matter in exhaust gas discharged from an internal combustion engine by a filter mounted in an exhaust gas passage of an exhaust gas purification device, the exhaust gas inflow side cell of the filter An exhaust gas purification of an internal combustion engine, characterized in that an ash trap layer is provided in the ash trap, the ash contained in the particulate matter is trapped and accumulated in the ash trap layer, and is trapped and removed at a specific position in the filter. Is the method.

The ash trap layer is preferably made of a glassy material, and is made of a low melting point glass, and the ash trap layer can be made of a low melting point inorganic compound flux material. .

The ash trap layer is preferably provided in the vicinity of the in-cell sealing portion of the integral-type, aggregate-type honeycomb structure, or laminated honeycomb structure.

Further, the filter has an ash trap layer formed of the honeycomb structure. It is preferable to be provided on the partition wall surface.

According to the present invention, an ash trap layer is provided at a specific location in the filter, that is, in each cell on the exhaust gas inflow side, particularly in the vicinity of the sealing portion of the cell end (downstream end portion). In ash, the particulate matter in the exhaust gas is burned and removed (for example, about 550 ° C), softened or further melted to produce ash, that is, the particulate matter burns to become unburned. The ash generated in this way is adsorbed sequentially in this ash trap layer, and is accumulated so as to be confined there and accumulated and solidified at a high density, thereby reducing the filter volume (filtering area) or blocking the exhaust passage. It can be used for a long time with no pressure loss in the exhaust system, and the filter life can be extended.

In addition, according to the exhaust gas purifying apparatus of the present invention, there is no need for maintenance such as replacement with a new product after a certain period of use or removal for ash removal, and the structure is simple, so that the cost is low. Can be realized.

Furthermore, according to the method of the present invention, exhaust gas can be highly purified through complete removal of ash. Brief Description of Drawings

FIG. 1 is a perspective view schematically showing an example of a honeycomb filter according to the present invention.

Fig. 2 (a) is a perspective view schematically showing an example of the porous ceramic member constituting the honeycomb filter shown in Fig. 1, and Fig. 2 (b) is shown in Fig. 2 (a). FIG. 3 is a cross-sectional view taken along line AA of the porous ceramic member.

Fig. 3 (a) is a perspective view schematically showing another example of the honeycomb filter according to the present invention, and Fig. 3 (b) shows the honeycomb shown in Fig. 3 (a). FIG. 6 is a cross-sectional view of the mu filter taken along line B-B.

Fig. 4 (a) is a perspective view schematically showing still another example of the honeycomb filter according to the present invention, and Fig. 4 (b) is a diagram of C and C of the honeycomb filter shown in Fig. 4 (a). FIG.

FIG. 5 is a diagram for explaining a part of the manufacturing process of the honeycomb filter shown in FIG.

FIG. 5 (a) is a schematic view showing the paper sheets to be laminated, and FIG. 5 (b) is a schematic perspective view of the honeycomb filter formed by stacking the paper sheets.

FIG. 6 is a cross-sectional view schematically showing an example of an exhaust gas purification device using the honeycomb filter according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a filter that collects particulate matter contained in exhaust gas exhausted from an internal combustion engine and an exhaust gas purification device for an internal combustion engine equipped with the filter. In this way, the generated ash is captured, and the ash is captured (captured) at a specific position in the filter, that is, in the vicinity of the sealing portion provided in the cell end portion of each cell on the exhaust gas inflow side. An ash trap layer is provided.

The above ash trap layer means that at least a part of the liquid phase at the filter regeneration temperature (2500 ° C to 800 ° C) at which the ash described above is removed (regenerated) by burning the particulates. It is preferably made of a material that generates or softens.

Specifically, such a trap layer constituent material is a vitreous material that changes from a solid phase to a liquid phase at the regeneration temperature of the filter or softens at least, preferably a phosphate glass or a calcium sulfate glass. Low melting point glass, etc. Alternatively, it is preferable to use a low melting point inorganic compound flux material.

The phosphoric acid glasses include P ₂ 0 ₃ — BaO (glass transition temperature: 3 7 7), Ρ ₂ 0 ₃ -Ζπ0 (glass transition temperature: 3 6 6 ° C), P ₂ 0 ₃ — BaO—BaF ₂ (glass transition temperature: 3 66 ° C.) or the like can be used.

Further, as a calcium-based glass sulfate, CaS0 ₄ -NaC I (lowest liquid phase temperature: 7 2 6 ° C), CaS0 4 - KCI ( minimum liquidus temperature: 6 8 7 ° C), CaS0 4 - NaC 卜 KC I (minimum liquidus temperature: 60 5 ° C) or the like can be used.

As the low-melting-point inorganic compound-based flux material, it is preferable to use a sulfate-based flux-reactive chloride-containing sulfate-based flux (hereinafter referred to as “chloride-containing flux”).

The sulfate fluxes include Li ₂ S0 ₄ -0.5Na ₂ S0 ₄ + 0.5K ₂ S0 ₄ (minimum melting temperature: 5 2 1 ° C), Na ₂ S0 ₄ -ZnS0 ₄ (minimum melting temperature: 4 5 6 ° C) can be used.

Furthermore, for chloride-containing fluxes, Li ₂ S0 ₄ -K ₂ S0 ₄ -NaCI (minimum melting temperature: 4 3 2 ° C) and i ₂ S0 ₄ -NaCI (minimum melting temperature: 4 9 9 ° C), Li ₂ S0 ₄ -NaC 卜 KCI (minimum melting temperature: 4 26 ° C), etc. can be used. Hereinafter, a filter according to the present invention and an exhaust gas purification apparatus for an internal combustion engine using the filter will be specifically described with reference to the drawings.

Here, an embodiment in which the filter according to the present invention is a honeycomb structure and the exhaust gas purification device according to the present invention is applied to a vehicle diesel engine will be described.

The filter according to the present invention uses a honeycomb structure in which a large number of cells (through holes) are arranged in parallel in the longitudinal direction with partition walls (filtration walls) therebetween. With such a structure, the filtration area per volume of the filter can be increased. << Ticulate can be collected thinly.

In such a honeycomb structure, a large number of cells are separated by partition walls. An assembly in which a plurality of columnar porous ceramic members arranged in parallel in the hand direction are bundled through a sealing material layer (hereinafter referred to as an “aggregate type honeycomb structure”), and the whole is a single unit. One made of porous ceramic members (hereinafter referred to as “integrated honeycomb structure”) and a number of plate-like (sheet-like) porous ceramic members A columnar honeycomb structure in which the cell holes are arranged in parallel in the longitudinal direction with the partition walls therebetween (hereinafter referred to as “stacked honeycomb structure”) may be used.

Fig. 1 is a perspective view schematically showing an example of an aggregate type honeycomb structure which is an example of a honeycomb structure, and Fig. 2 (a) is a porous diagram of the aggregate type honeycomb structure shown in Fig. 1. 1 is a perspective view of a ceramic member (unit), and FIG. 2B is a cross-sectional view taken along line AA of the porous ceramic member shown in FIG.

The honeycomb structure 10 shown in FIG. 1 is composed of a prismatic porous ceramic member (unit) 20 shown in FIG. 2 and a cylindrical ceramic block 1 that is bundled together via a sealing material layer 1 4. 5 and a sealing material layer 13 is provided on the outer periphery of the ceramic block 15.

In this example, the prismatic porous ceramic member 20 is provided with a large number of cells (through holes) 21 along the longitudinal direction thereof. When the above-mentioned double cam structure 10 is used as a honeycomb filter for collecting particulates in exhaust gas, the porous ceramic member 20 is formed of these cells as shown in FIG. 2 (b). Either one of the openings at both ends of 2 1 is sealed with a sealing material (plug) 2 2.

That is, the honeycomb structure 1 0 is hand of (exhaust gas inflow side) cells 2 1 of the ceramic block ¹ 5 its downstream end (Seruen de) is locked Li sealed by the sealing material 2 2, In the other (exhaust gas outflow side) cell 2 1, the upstream end is sealed with the sealing material 2 2. In this case, the exhaust gas flowing into the exhaust gas inflow side cell 21a passes through the partition wall 23 that separates the cells 21a, and moves to the cell 21b on the exhaust gas outflow side. The partition wall 2 3 separating these cells 21a and 21b is made to function as a particle collecting filter.

The sealing material layer 13 formed around the ceramic block 15 is used to prevent exhaust gas from leaking from the outer periphery of the ceramic block 15 when the honeycomb structure 10 is used as a honeycomb filter. Or, it is formed to adjust the shape.

Fig. 3 (a) is a perspective view schematically showing another embodiment of the honeycomb structure, that is, a specific example of the integral honeycomb structure, and Fig. 3 (b) is a view taken along the line B-B. It is sectional drawing.

As shown in FIG. 3 (a), the monolithic honeycomb structure 30 has a single columnar structure in which a large number of cells 31a and 31b are provided along the longitudinal direction with a partition wall 33 therebetween. It is composed of a cylindrical ceramic block 35 made of a porous ceramic sintered body.

When this honeycomb structure 30 is used as a filter for collecting particulates in the exhaust gas, the ceramic block 35 is composed of cells 31a, as shown in Fig. 3 (b). Either one of the ends of 3 1 b is sealed with sealing material 3 2 on one side.

That is, in the ceramic block 35 of the honeycomb structure 30, the downstream end of the exhaust gas inflow side cell 3 1 a is sealed by the sealing material 3 2, and the exhaust gas outflow side cell 3 1 b At the end, the upstream end is preferably sealed with the sealing material 32.

In this case, the exhaust gas flowing into one cell 3 1 a passes through the partition wall 3 3 separating these cells 3 1 a and then flows out from the other cell 3 1 b (so-called wall). Flow type), these cells 3 1 a, 3 1 b The partition wall 3 3 separating the two can function as a particle collecting filter.

Although not shown in Fig. 3, around the ceramic block 35, in order to prevent the exhaust gas from leaking from the outer periphery of the ceramic block 15 as in the honeycomb structure 10 shown in Fig. 1, Alternatively, a sealing material layer may be formed to adjust the shape.

The honeycomb structure constituting the filter according to the present invention described above may be used as a ceramic member material, for example, oxide ceramics such as cordierite, alumina, silicon force, mullite, zirconia, and yttria, silicon carbide, Carbide ceramics such as zirconium carbide, titanium carbide, tantalum carbide, tungsten carbide, etc., nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, titanium nitride, etc., aluminum titanate, composite of ceramic and silicon, etc. Can be used.

When the honeycomb structure forming the filter according to the present invention is an aggregate-type honeycomb structure as shown in FIG. 1, among the above ceramic particles, heat resistance is high, and mechanical characteristics and chemical stability are improved. Silicon carbide is desirable because it has excellent thermal conductivity.

In addition, when the honeycomb structure forming the filter according to the present invention is an integral honeycomb structure as shown in FIG. 3, an oxide ceramic such as cordierite is used. It can be manufactured at low cost and has a relatively small coefficient of thermal expansion. For example, it is not broken during use as a honeycomb filter, and it is not oxidized. It is.

The thermal conductivity of the substrate of the honeycomb structure forming the filter according to the present invention is determined by the type of ceramic particles used, etc., but when ceramic ceramics or nitride ceramics are used as ceramic particles Is preferably 3 WZ m · K to 60 WZ m W / m 2 K ~ 40 W / m 2 K is more desirable.

The reason is that if the thermal conductivity is less than 3 WZm ■ K, the temperature of the filter will be too high and the filter will be damaged, and the performance of the catalyst supported on the filter will be reduced. ■ If the temperature exceeds K, the temperature of the filter will not rise easily, so it will be difficult for the particulate soot to burn, and it will be difficult to purify the exhaust gas.

In addition, when using oxide ceramics (eg cordierite 卜) as the ceramic particles, the thermal conductivity is preferably 0.1 WZm ■ K to 10W Wm ■ 、, and 0.3 WZm ■ Κ ~ 3 W / m ■ More preferably Κ.

The reason is that if the thermal conductivity is less than 0.1 WZm ■ K, the temperature of the filter is too high and the filter is damaged, or the performance of the catalyst supported on the filter decreases. This is because if the temperature exceeds 1 OWZm ■ K, the temperature of the filter becomes difficult to rise, so it becomes difficult for the particulate soot to burn and purification of the exhaust gas becomes difficult.

In the honeycomb structure shown in FIG. 1 and FIG. 3, the shape of the ceramic block is a columnar shape. However, in the present invention, the ceramic block is not limited to a columnar shape as long as it is a columnar shape. It may be of a shape such as a prismatic shape.

The porosity of the ceramic block is preferably about 20 to 80%. The reason is that when the porosity is less than 20%, when the above honeycomb structure is used as a honeycomb filter, clogging occurs immediately, and when the porosity exceeds 80%, ceramic This is because the strength of the block decreases and it is easily broken.

The porosity can be measured by a conventionally known method such as a mercury intrusion method, an Archimedes method, or a measurement using a scanning electron microscope (SEM). The average pore size of the ceramic block is preferably about 5 to 100 m. The reason is that if the average pore diameter is less than 5 jum, when the above honeycomb structure is used as a filter, the particulates are easily clogged, while the average pore diameter is 1 OO jUm. This is because the particulates pass through the pores, and the particulates cannot be collected and cannot function as a filter. In the honeycomb structure forming the filter according to the present invention, when any one end of the ceramic block cells is sealed, the sealing material is preferably made of a porous ceramic. . The reason is that the sealed ceramic block is made of porous ceramic, so that the sealing material is the same porous ceramic as the ceramic block, so that the adhesive strength between them can be increased. In addition, by adjusting the porosity of the sealing material in the same manner as the ceramic block described above, the thermal expansion coefficient of the ceramic block can be matched with the thermal expansion coefficient of the sealing material. It is possible to prevent cracks from occurring in the wall part where the sealing material is in contact with the sealing material due to thermal stress during use. This is because it can be done.

When the sealing material is made of porous ceramic, it is desirable to use, for example, the same material as the ceramic particles constituting the ceramic block described above.

When the honeycomb structure forming the filter according to the present invention is the aggregate type honeycomb structure shown in FIG. 1, the sealing material layers 1 3 and 14 are provided between the porous ceramic members 20 or ceramics. These are arranged on the outer periphery of the block 15 so as to surround them. The sealing material layer 14 interposed between the porous ceramic members 20 functions as an adhesive that binds the plurality of porous ceramic members 20 together. When the honeycomb structure is used as a filter, the sealing material layer 13 formed on the outer periphery of the block 15 is a ceramic block 1 when the honeycomb structure 10 is installed in the exhaust passage of the internal combustion engine. It functions to prevent the exhaust gas from leaking from the outer periphery of 5.

As described above, in the honeycomb structure forming the filter according to the present invention, the sealing material layer is formed between the porous ceramic members and on the outer periphery of the ceramic block. These sealing material layers are the same. It may be made of a material or a different material. For example, an inorganic binder, an organic binder, and inorganic fibers and / or inorganic particles are used. Furthermore, when the sealing material layers are made of the same material, the blending ratio of the materials may be the same and may be different.

As the inorganic binder constituting the sealing material layer, for example, silica sol, alumina sol or the like is used. These may be used alone or in combination of two or more. Of the above inorganic binders, silica is preferred.

Examples of the organic binder constituting the sealing material layer include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. These may be used alone or in combination of two or more. Among the organic binders, carboxymethyl cellulose is desirable.

As the inorganic fibers constituting the sealing material layer, for example, silica alumina, mullite, alumina, a ceramic fiber such as siri force, or the like is used. These may be used alone or in combination of two or more. Among the inorganic fibers, silica monoalumina fiber is desirable. Examples of the inorganic particles constituting the sealing material layer include carbides, nitrides, and the like. Specifically, silicon carbide, silicon nitride, nitriding An inorganic powder made of boron or the like or a whisker is used. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide having excellent thermal conductivity is desirable.

The sealing material layer 14 interposed between the members may be made of a dense material, but when used as the honeycomb filter, the exhaust gas can flow into the inside thereof. A porous body is used. On the other hand, it is desirable that the sealing material layer 13 disposed on the outer periphery of the filter is made of a dense body. This is because the sealing material layer 13 is used for the purpose of preventing the exhaust gas from leaking from the outer periphery of the ceramic block 15 when the honeycomb structure 10 is installed in the exhaust passage of the internal combustion engine. is there.

As described above, the honeycomb structure according to the present invention has a structure in which a sealing material is filled and sealed at one end of each cell of the ceramic block, as shown in FIGS. It is suitable for collecting particulates in exhaust gas discharged from internal combustion engines such as diesel engines.

Note that the partition walls of the ceramic block of the honeycomb structure may carry a catalyst such as Pt for promoting combustion of the particulate when the honeycomb filter is regenerated. For example, exhaust gas discharged from a heat engine such as an internal combustion engine or a combustion device such as a boiler by supporting a catalyst such as a noble metal such as Pt, Rh, or Pd or an alloy thereof on a ceramic block of a honeycomb structure It can be used to purify HC, CO, NOx, etc.

Next, a laminated honeycomb structure which is another embodiment of the honeycomb structure forming the filter according to the present invention will be described. FIG. 4 is a perspective view schematically showing a specific example of the laminated honeycomb structure, and FIG. 4 (a) is a perspective view of the porous ceramic sintered body shown in FIG. Figure (b) FIG. 3 is a cross-sectional view taken along line C-C of the porous ceramic member shown in (a). This filter is a laminate in which plate-like sheets (thickness of about 0.1 to 20 mm) are laminated in the thickness direction, that is, in the longitudinal direction of the filter, and the cell through holes overlap in the longitudinal direction. The cells 4 1 are shaped to form a honeycomb structure.

Here, the term “stacked so that the cell through holes overlap each other” means that the through holes formed in the adjacent sheet-shaped objects communicate with each other to form the cell 41.

The sheet-like material is preferably made of ceramic, metal or the like, but in the present invention, it is preferably made mainly of inorganic fibers. This is because when the sheet-like material is made of inorganic fibers, it can be easily produced by a papermaking method or the like, and a honeycomb structure made of a laminated body can be produced by laminating them. . The laminate may be formed by bonding with an inorganic adhesive material or the like, or may be merely physically laminated.

In addition, when producing a laminated body, it is directly inserted into a casing (metal cylindrical body) to be attached to the exhaust pipe, and the layer is stacked by applying pressure to form the panicam structure. can do.

The honeycomb structure 40 has a large number of cells 41a, in which either one end of the cells, that is, the downstream end on the exhaust gas inflow side is plugged, arranged in parallel in the longitudinal direction with the partition wall 43 therebetween. It has a cylindrical shape that functions as a filter.

That is, as shown in Fig. 4 (b), the cell is sealed at either the end corresponding to the exhaust gas inlet side or the outlet side, and the exhaust gas flowing into one cell 41a is After passing through the partition wall 43 that separates these cells, it flows out from the other cell 4 1 b and functions as a filter. The wall thickness is preferably in the range of 0.2 to 10 mm, and more preferably in the range of 0.3 to 6.0 mm.

The reason is that if the thickness is less than 0.2 mm, the strength is weak and may be damaged during use. If the thickness exceeds 10 O mm, the exhaust gas hardly permeates and the pressure loss is large. Because it becomes.

The density of cells in the cross section perpendicular to the longitudinal direction of the honeycomb structure is 0.16 cells / cm ² (1.0 cells η ² ) to 62 cells cm ² (400 cells / in ² ). Preferably, 0.6 2 pieces cm ² (4.0 pieces Z in ² ) to 3 1 pieces Zcm ² (200 pieces Z in ² ) is a more desirable range. The reason for this is that if the area is less than 0.1 6 cm ² , the filtration area is small and the pressure loss tends to be large, and if it exceeds 62 ² cm ² , the cross-sectional area per through hole is small. This is because the particulates and ash are easily clogged. Also, the size of the through hole is 1.4mm x 1.4mm ~ 16mmx16mm force, desired.

Examples of the material of the inorganic fiber include oxide ceramics such as silica-alumina, clay, alumina, and silica, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, silicon carbide, Carbide ceramics such as zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide can be used. These may be used alone or in combination of two or more.

The fiber length of the inorganic fiber is preferably 0.1 mm to 100 mm, and more preferably 0.5 mm to 5 O mm.

The reason is that if the thickness is less than 0.1 mm, the elasticity due to the use of the fiber is lowered and it becomes difficult to maintain the shape, and if it exceeds 100 mm, the additivity is lowered.

The fiber diameter of the inorganic fiber is preferably 1 m to 30 m, and more preferably 2 / m to 10 m. The reason is that if it is less than 1 fi m, the strength is insufficient, and if it exceeds 30 ju m, the workability deteriorates.

In addition to the inorganic fibers, the honeycomb structure may include a binder that bonds these inorganic fibers to maintain a certain shape. Examples of the binder include inorganic glass such as silicate glass, alkali silicate glass, and borosilicate glass, alumina sol, silica sol, and titasol.

When the binder is included, the content is preferably 5 w t% to 50 w t%, and more preferably 10 w t% to 40 w t% o

The reason for this is that the bonding strength is insufficient if it is less than 5 wt%, and conversely, if it exceeds 50 wt%, there are too many indas and the bonding between the fibers becomes insufficient.

The honeycomb structure may contain a small amount of inorganic particles and metal particles. As the inorganic particles, for example, carbides, nitrides, oxides and the like can be used. Specifically, inorganic powders made of silicon carbide, silicon nitride, boron nitride, alumina, silica, zirconia, titania, etc. Can be used.

Examples of the metal particles include metal silicon, aluminum, iron, and titanium. These may be used alone or in combination of two or more.

The apparent density of the honeycomb structure is preferably 0.05 gZ cm ³ to 1.0 O gZ cm ³ , and is preferably 0.1 g / cm ³ to 0.5 0 g Z cm ³ . It is more desirable.

The reason is that 0.0 is less than 5 g Zc m ^3, second cam structure capacity is too small temperature becomes too high during Patikyure bets combustion is because cracks, more than 1 .00 g / cm ³ And the heat of the honeycomb structure This is because the capacity is so large that the temperature does not rise easily during the burning of the patty liquor and the regeneration is insufficient.

The porosity of the honeycomb structure is preferably a 6 0% by volume to 9 8 volume%, 8 0 volume% to 9 5 volume ^_0/0 is a more desirable arbitrariness.

The reason is that if it is less than 60% by volume, the passage of exhaust gas decreases, while if it exceeds 98% by volume, the strength is insufficient. The apparent density and porosity can be measured by a conventionally known method such as a gravimetric method, an Archimedes method, or a measurement using a scanning electron microscope (S E M).

In the honeycomb structure forming the filter of the present invention, a catalyst made of a noble metal such as platinum, palladium, or rhodium may be supported on the inorganic fiber constituting the honeycomb structure. In addition to precious metals, alkali metals (Group 1 of the Periodic Table of Elements), alkaline earth metals (Group 2 of the Periodic Table of Elements), rare earth elements (Group 3 of the Periodic Table of Elements), and transition metal elements may be added. .

By supporting such a catalyst, the filter using the honeycomb structure functions as a filter that can collect particulates in the exhaust gas and perform regeneration treatment with the catalyst. It can function as a catalytic converter for purifying C0, HC, NOx, etc. contained in exhaust gas.

The shape of the honeycomb structure 10 shown in FIG. 4 is a columnar shape, but is not limited to the circular columnar shape. For example, it has an arbitrary columnar shape or size such as an elliptical columnar shape or a prismatic shape. Also good.

An important structure in the filter according to the present invention is to use any one of the aggregate type honeycomb structure 10, the integral type honeycomb structure 30, and the laminated honeycomb structure 40 as described above. The exhaust gas inflow side cells 2 1 a, 3 1 a, 4 formed in this structure are preferable. Made of vitreous material such as low-melting glass or low-melting-point inorganic compound-based flux material in the vicinity of the sealing part in the cell of 1a or on the partition wall surface, and further on the downstream part of the partition wall surface. This is in that an ash trap layer 1 0 0 is provided.

The low melting point glass is vitrified by softening or melting at a temperature at which particulates collected during regeneration can be burned and removed, that is, at a filter regeneration temperature (2500 to 800 ° C). Inorganic compounds such as phosphate glass and calcium sulfate glass are preferred, and the low melting inorganic compound flux material is softened or melted within the above temperature range. Sulfate flux or chloride containing flux is preferred. In addition, two or more of these materials can be used in combination.

In the present invention, the reason why the above-described ash trap layer is provided in the cell is as follows. In general, when the filter is regenerated, particulate matter (particulate soot) is combusted. At this time, the ash component left as unburned material is blown away by the exhaust gas. The ash thus blown is vitrified and fluidized in a softened and melted state. The ash in such a flow state attracts and binds with each other in order to trap the ash, so that all the softened ash that has detached (from the particulates) accumulates in this portion (ash trap, etc.). That is, the softened glass or flux generated in this way is accumulated at a high density in that portion, and is fixed there, so that even if the filter is used for a long time, the filtration area is small. There is no longer a loss of pressure.

In the present invention, when the honeycomb structure forming the filter is a so-called wall flow type in which any one of the cell end portions is sealed with a sealing material, the ash trap layer is formed on the partition wall of the ceramic block. Rather than forming, it is preferable to form it at a position adjacent to the sealing part of the exhaust gas outflow side.

This is because if an ash trap layer is formed on the partition wall, ash accumulates on the trap and fills the pores, increasing the resistance when injecting exhaust gas and increasing pressure loss. Because it becomes.

On the other hand, when an ash trap layer is formed adjacent to the sealing portion at the outflow side end of the exhaust gas inflow side cell, the ash is accumulated in the vicinity of the sealing portion. This is because the decrease can be minimized. However, it can also be formed on the partition walls by adjusting the porosity of the filter and the thickness of the ash wrap layer.

Next, an aggregated honeycomb structure forming the filter according to the present invention

As an example of a method for manufacturing 10 and the integral honeycomb structure 30, a case will be described in which a honeycomb structure in which one end of a predetermined cell of a ceramic block is sealed and sealed is manufactured.

As shown in FIG. 3, when the honeycomb structure is an integrated honeycomb structure 30 formed as one ceramic block as a whole, first, the ceramic structure as described above is used. Extrusion molding is performed using a raw material paste 粒子 containing particles as a main component, and a ceramic molded body having substantially the same shape as the honeycomb structure 30 shown in Fig. 3 is produced.

The raw material paste preferably has a porosity of 20 to 80% of ceramic block after production. For example, ceramic particle powder having a large average particle size and ceramic particle having a small average particle size A mixed powder consisting of and added with a binder and a dispersion medium is used. As the binder, for example, methyl cellulose, carboxymethyl cellulose, hydroxychetyl cellulose, polyethylene glycol, phenol resin, epoxy resin and the like are used. In general, the amount of the binder is desirably about 1 to 10 parts by weight with respect to 100 parts by weight of the ceramic particle powder.

As the dispersion medium liquid, for example, an organic solvent such as benzene, alcohol such as methanol, water or the like is used, and this dispersion medium liquid is blended so that the viscosity of the raw material paste ペース falls within a certain range. The

The mixed powder consisting of the ceramic powder and the silicon powder, the binder and the dispersion medium liquid are mixed with an attritor or the like, and sufficiently mixed with a kneader to obtain a raw material paste, and then the raw material paste is extruded. Molding to produce the above ceramic molded body.

In addition, a molding aid may be added to the raw material paste as necessary, and examples of the molding aid include ethylene glycol, dextrins phosphorus, fatty acid sarcophagus, polyvinyl alcohol, and the like. Is used.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide-based ceramics, spherical acrylic particles, and graphite may be added to the raw material paste as necessary.

As the balloon, for example, an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a murato balloon are used. Of these, alumina balloons are preferred.

Then, the ceramic molded body is dried using a microphone mouth wave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like to obtain a ceramic dried body, and then a predetermined cell. One end of the cell is filled with a paste serving as a sealing material, and the cell is sealed.

Next, the ceramic dry body filled with the sealing material paste 卜 is heated to about 150 to 700 ° C. to remove the binder contained in the ceramic dry body, and the ceramic degreased body and Apply degreasing treatment.

Furthermore, the above ceramic degreased body is heated to about 1400-200 ° C. And manufacturing a ceramic porous body.

The honeycomb structure manufactured in this way has a structure in which a sealing material is filled and sealed at the outflow side end of the exhaust gas inflow side cell of the ceramic block. The honeycomb filter for exhaust gas purification described above As such, it can be suitably used.

In this case, the cell wall of the ceramic block, that is, the surface of each partition wall, may be supported with a catalyst such as Pt for promoting the combustion of the particulates when the honeycomb filter is regenerated.

When the honeycomb structure is an aggregated honeycomb structure 10 in which a plurality of porous ceramic members are bundled through a sealing material layer as shown in FIG. First, extrusion molding is performed using the above-mentioned raw material paste containing ceramic particles and silicon as main components, and a shaped product having a shape like the porous ceramic member 20 shown in FIG. 2 is produced.

The raw material paste may be the same as the raw material paste described in the above-described integrated honeycomb structure 30.

Next, the generated shaped body is dried using a microwave dryer or the like to obtain a dried body, and then a sealing material and a sealing material are provided at the end on the outflow side of the through hole on the gas inflow side serving as a cell of the dried body. A sealing process is performed to fill the sealing material paste and seal the cells. Further, the upstream end of the exhaust gas outflow side cell adjacent to the exhaust gas inflow side is similarly sealed with a sealing material.

Next, a dry body, in which each cell is alternately sealed as described above, is subjected to a degreasing process under the same conditions as those of the above-described integrated honeycomb structure 30, and then fired to obtain a plurality of It is possible to manufacture a porous ceramic member in which the cells are arranged in parallel in the longitudinal direction across the partition walls. Then, on the side surface of the porous ceramic member 20, a seal layer is formed. The process of applying and laminating a paste paste with a uniform thickness is repeated to produce a laminated body of prismatic porous ceramic members 20 having a predetermined size. Since the material constituting the sealing material paste has been described when the honeycomb structure is described, the description thereof is omitted here. Next, the laminated body of the porous ceramic member 20 is heated to dry and solidify the sealing material paste layer 51 to form the sealing material layer 14. Then, for example, using a diamond cutter or the like, A ceramic block 15 is manufactured by cutting the outer peripheral portion into a shape as shown in FIG. Furthermore, a honeycomb structure in which a plurality of porous ceramic members are bundled through a seal material layer by forming the seal material layer 13 on the outer periphery of the ceramic block 15 using the above seal material paste. Structures can be manufactured.

The aggregated honeycomb structure 10 manufactured in this way is obtained by filling the end portion of a predetermined cell of a ceramic block (porous ceramic member) with a sealing material and sealing it. It can be suitably used as a honeycomb filter for gas purification. In this case, the wall of the ceramic block (the partition wall of the porous ceramic member) may carry a catalyst such as Pt for promoting the combustion of the particulates when the honeycomb filter is regenerated. Good.

In the present invention, among the cells of the ceramic block, the downstream end portions of the exhaust gas inflow side cells 21a and 31a are adjacent to the portion (sealing portion) sealed with the sealing material. Thus, it is desirable that the ash trap layer 100 be formed, but in some cases, the ash trap layer may be formed on the partition wall surface (cell wall). This ash trap layer 100 is formed by cooling after melting, coating, filling, or spraying molten glassy material into the exhaust gas inflow side cells 2 1a, 3 1a. can do. If a trap layer is formed at the time of sealing, it is then fired at Ι Α Ο Ζ Ι Ο Ο Ο ^, so the trap layer softens at 25 ° to 80 ° C., which is not preferred.

Further, after forming the trap layer in the exhaust gas inflow side cells 21a and 31a, the sealing material may be pushed in and sealed.

Next, a manufacturing method of the laminated honeycomb structure forming the filter of the present invention will be described with reference to FIG.

(1) Ash trap application process to inorganic fibers

Inorganic fibers such as alumina fibers are impregnated in a slurry prepared by melting phosphate glass, for example, and then pulled up and cooled to prepare inorganic fibers on which a glassy ash trap layer is adhered and supported. . The supported amount of ash trap is preferably 0.01 to 90 g per 10 g of inorganic fiber.

As described above, in the honeycomb structure according to the present invention, the ash trap layer 100 can be more evenly dispersed because the ash trap layer 100 can be directly applied to the inorganic fiber that is a constituent material before molding. In this state, it can be supported and adhered.

Usually, the ash trap layer 100 is controlled so as not to melt and flow out of the filter, and utilizes the property of softening and melting during regeneration. Therefore, when the surface of the ash trap layer is softened and melted (that is, at the time of regeneration), it is desirable that the ash be immediately taken into the ash trap layer when the particulate reaction occurs. . In other words, ash can be reliably taken into the trap layer by providing ash traps uniformly within the filter.

Therefore, in the obtained honeycomb structure, the combustion function of particulates and the purification function of harmful gases can be increased. Atsushi The provision of the strap layer may be performed after the papermaking sheet is produced.

(2) Process for preparing papermaking slurry

Next, the inorganic fiber carrying the catalyst obtained in step (1) is dispersed at a rate of 5 to 100 g per 1 liter of water, and an inorganic binder such as sili-force sol is added to the inorganic fiber 1. Add 100 to 40 parts by weight of organic binder such as acrylic latex to 1 to 10 parts by weight with respect to 00 parts by weight, and if necessary, coagulant such as aluminum sulfate, polyacrylamide, etc. Add a small amount of flocculant and thoroughly stir to prepare a slurry for papermaking.

Examples of the organic binder include methyl cellulose, carboxymethyl cellulose, hydroxy shetil cellulose, polyethylene glycol, phenol resin, epoxy resin, polyvinyl alcohol, and styrene butadiene rubber.

(3) Papermaking process

The slurry obtained in the above (2) is made by a punching mesh in which holes having a predetermined shape are formed at predetermined intervals, and the obtained slurry is heated to a temperature of about 100 to 200 ° C. By drying with, a paper sheet 40 a having a predetermined thickness as shown in FIG. 5 (a) is obtained. The thickness of the papermaking sheet 40 a is preferably 0.1 to 20 mm.

In the present invention, for example, by using a mesh in which holes having a predetermined shape are formed in a checkered pattern, a papermaking sheet 40b for both ends can be obtained.

That is, if several sheets of this papermaking sheet are used at both ends, a honeycomb structure that functions as a filter can be obtained without forming a cell and then closing a predetermined cell at both ends. Can do.

(4) Lamination process

As shown in Fig. 5 (b), a cylindrical case with a holding bracket on one side. First, a plurality of sheet-forming sheets 40 b for both ends are stacked in the casing 43, and then a predetermined number of sheet-forming sheets 40 a for internal use are stacked. Finally, several sheets of paper 40b for both ends were stacked, further pressed, and then the other side was installed and fixed with holding metal fittings to complete the canning. A honeycomb structure can be produced. Of course, in this process, the papermaking sheets 40 a and 40 b are laminated so that the cells overlap.

When the honeycomb structure forming the filter of the present invention is simply simply formed by stacking paper sheets, the honeycomb structure is disposed in the exhaust passage when the honeycomb structure is disposed in the exhaust passage. Even if a certain temperature distribution occurs in the structure, the temperature distribution of a single sheet is small and cracks are not likely to occur.

In addition, as a result of the papermaking, the inorganic fibers are oriented almost parallel to the main surface of the papermaking sheet, and when the laminate is produced, the inorganic fibers are compared with the surfaces parallel to the cell formation direction. The orientation is more along the plane perpendicular to the cell formation direction.

As a result, the exhaust gas can easily permeate the walls of the honeycomb structure, so that the initial pressure loss can be reduced and the particulates can be easily filtered through the inside of the partition walls. Can be suppressed, and an increase in pressure loss during particulate collection can be suppressed.

In addition, since the ratio of exhaust gas flowing parallel to the orientation direction of the inorganic fibers increases, the chance that the particulates come into contact with the catalyst adhering to the inorganic fibers increases, and the particulates easily burn.

Furthermore, by making paper sheets with different hole dimensions and laminating them, the cells form irregularities and cells with a large surface area can be formed. Therefore, it is necessary to collect particulates with a large filtration area. It is possible to reduce the pressure loss at the time. The shape of the hole is not particularly limited to a quadrangle, and may be any shape such as a triangle, hexagon, octagon, dodecagon, circle, or ellipse.

FIG. 6 is a cross-sectional view schematically showing an example of an exhaust gas purifying device for a vehicle in which the filter of the present invention is installed.

In FIG. 6, an exhaust gas purification device 600 mainly includes a honeycomb filter 60 according to the present invention, a casing 630 which covers the outside of the honeycomb filter 60, and A holding sealing material 6 20 disposed between the cam filter 60 and the casing 6 30 and heating means 6 10 provided on the exhaust gas inflow side of the honeycomb filter 60 are configured. An exhaust introduction pipe 6 40 connected to an internal combustion engine such as an engine is connected to an end of the casing 6 30 on the side where the exhaust gas is introduced. A discharge pipe 65 0 connected to the outside is connected to the end. In Fig. 6, the arrows indicate the flow of exhaust gas.

Although not shown, it is preferable to install an exhaust pipe in front of the honeycomb filter or a catalyst carrier carrying platinum in the casing. This is because, among exhaust gases, the heat generated by gases that react at low temperatures, such as HC, is transmitted to the honeycomb filter, which makes the filter cool to high temperatures.

The particulate filter described above is not particularly limited in shape and structure as long as it has a structure capable of collecting particulate matter, but preferably has a surface area as large as possible.

For example, the first flow path has a two-cam structure, a porous material is used as a base material, the upstream end is open, and the downstream end is closed, and the upstream end is closed. In addition, a so-called wall flow type in which the second flow path having the open end on the downstream side is alternately arranged in a honeycomb shape can be provided. These first flow paths become exhaust gas inflow side cells whose downstream ends are closed by a sealing material, and the second flow paths are exhaust gases whose upstream ends are closed by a sealing material. These are gas gas outflow side cells, which are alternately arranged through thin walls.

Further, in FIG. 6, the structure of the honeycomb filter 60 may be the same as the aggregated honeycomb structure 10 shown in FIG. 1 or the integrated honeycomb structure 30 shown in FIG.

In the exhaust gas purification device 600 having such a configuration, exhaust gas discharged from an internal combustion engine such as an engine is introduced into the casing 6 30 through the introduction pipe 6 40, and the honeycomb filter. After passing through the wall (partition wall) from the 60 cell, the particulates are collected and purified by this partition wall, and then discharged to the outside through the discharge pipe 6 50.

When a large amount of particulates accumulates on the partition walls of the honeycomb filter 60 and the pressure loss increases, the regeneration process of the honeycomb filter 60 is performed. In the regeneration treatment, the gas heated by the heating means 61 is flowed into the cells of the honeycomb filter 60 to heat the honeycomb filter 60, and the particulates deposited on the partition walls are burned by the heating. Removed.

Further, when a catalyst such as Pt for promoting the combustion of particulates is supported on the partition walls of the honeycomb filter 60, the combustion temperature of the particulates is lowered, so the honeycomb filter 60 by the heating means 6 10 is used. In some cases, heating by the heating means 6 10 can be eliminated.

The regeneration of the filter means that the collected particulates are burned, but the regeneration method is a method in which the honeycomb structure is heated by a heating means provided on the exhaust gas inflow side. Alternatively, an oxidation catalyst is supported on the two-cam structure, and the heat generated by the oxidation of hydrocarbons in the exhaust gas by the oxidation catalyst is used to regenerate in parallel with the purification of the exhaust gas. A method of performing Further, the catalyst for direct oxidation of solid Patikyure bets by oxidizing by re NOX oxidation catalyst provided upstream of the system and filters provided in the filter to generate a N0 _2, oxidizing the Patikyure bets using the N0 ₂ It is also possible to use this method.

In the exhaust gas purifying apparatus 600 according to the present invention, the particulates are burned and removed in the temperature range of 2500 ° C. to 800 ° C., which is the melting temperature of the ash trap layer 100. (Regeneration treatment) is preferably configured, and more preferably, the regeneration treatment is performed in a temperature range of 500 ° C to 700 ° C.

Generally, in a diesel engine, the exhaust gas has a relatively high oxygen concentration. Therefore, the regeneration process of the exhaust gas purification device for the diesel engine has a relatively high oxygen concentration or an oxygen storage effect of rare earth elements or the like. Usually, it is carried out in an excess oxygen atmosphere by the action of a catalyst having

Therefore, when the regeneration temperature exceeds 800 ° C., the vitreous material or flux material constituting the ash trap layer 100 is melted and easily flows from the porous filter. Below 2500 ° C, the glass or flux will not melt, so it will not function to take in and fix the ash.

When producing a filter according to the present invention, a glassy material or an inorganic compound-based flux material is melted and reduced in viscosity within a temperature range of 250 ° C. to 800 ° C. In order to investigate the applicability of the material as a material to form a glass, 11 types of testable glassy materials (Test Examples 1 to 1 1) and inorganic compound flux materials were used. 5 types (Test Examples 1 2 to 16) were selected. The results are shown in Table 1.

(Note * 1) Flux Α 'Sulfide flux

(* 2) Flux Β

The above test was performed using a thermogravimetric / differential thermal analyzer (TGZD TA) (manufactured by Seiko Denshi Co., Ltd., product name: TGZDTA220U). The lowest liquidus temperature, the lowest melting temperature, and the glass transition temperature were obtained and the applicability was judged.

Examples in which 16 types of ash trap materials selected based on such test results are applied to an integrated / aggregate type non-stacked honeycomb structure will be described in detail below. It is not limited only to these examples.

Examples 1 to 16 below are examples of an integral honeycomb structure, Examples 1 7 to 3 2 are examples of an aggregated honeycomb structure, and Examples 3 3 to 4 8 are It is an example of a laminated honeycomb structure.

(Example 1)

(1) Using a commercially available cordierite, a cylindrical porous ceramic with a porosity of 45%, an average pore diameter of 20 / m, a large force diameter of 144 mm, and a length of 25 4 mm And a honeycomb structure that functions as a honeycomb filter for purifying exhaust gas.

(2) in the honeycomb structure, the P ₂ 0 ₃ based glass such as that shown in Test Example 1 was slurried dissolved in 400 ° C, sealing the slurry Seruen de of exhaust gas inflow-side cells of the honeycomb structure Spraying to a thickness of 5 mm adjacent to the stop, an ash trap layer is formed and used as a filter.

(Example 2)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the slurry by dissolving P ₂ 0 ₃ based glass, as shown in Test Example 2 5 0 0 ° C, the downstream end of the exhaust inlet-side in the cell the slurry Sink at a thickness of 5 mm adjacent to the sealing part As a result, an ash trap layer was formed and used as a filter.

(Example 3)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) above (1) to the honeycomb structure, in the slurry by dissolving P ₂ 0 ₃ based glass such as that shown in Test Example 3 in 3 00 ° C, the downstream end in the slurry exhaust gas inflow cells The ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion of the honeycomb structure provided in Fig. 1 to obtain a filter.

(Example 4)

(1) The same hanica ridge structure as (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), and the slurry dissolved in 7 5 0 ° C in CAS0 ₄ glass as shown in Test Example 4, sealing of the downstream end of the exhaust inlet-side in the cell the slurry A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the stopper, and a filter was obtained.

(Example 5)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the slurry by dissolving CAS0 ₄ glass as shown in Test Example 5 7 00 ° C, is adjacent to the slurry in the sealing portion of Hani cam structure Then, it was coated and filled at a thickness of 5 mm to form an ash trap layer and used as a filter.

(Example 6)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the slurry by dissolving CAS0 ₄ glass as shown in Test Example 6 in 5 8 0 ° G, sealing of the downstream end of the exhaust inlet-side in the cell the slurry A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the stopper, and a filter was obtained.

(Example 7) (1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the slurry by dissolving CAS0 ₄ glass as shown in Test Example 7 by 7 7 0 ° C, sealing of the downstream end of the exhaust inlet-side in the cell the slurry A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the stopper, and a filter was obtained.

(Example 8)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the slurry by dissolving CAS0 ₄ glass as shown in Test Example 8 7 3 0 ° C, sealing of the downstream end of the exhaust inlet-side in the cell the slurry A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the stopper, and a filter was obtained.

(Example 9)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the slurry by dissolving CAS0 ₄ glass as shown in Test Example 9 6 5 0 ° C, sealing of the downstream end of the exhaust inlet-side in the cell the slurry A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the stopper, and a filter was obtained.

(Example 10)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) the honeycomb structure of the above (1), in the CaS0 slurry dissolved ₄ glass at 7 00 ° C shown in Experimental Example 1 0, sealing the slurry in the downstream end of the drainage inlet side cells A flush trap layer was formed by pouring in a thickness of 5 mm adjacent to the stopper and used as a filter.

(Example 1 1)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) In the honeycomb structure of (1) above, the CaS0 ₄ glass shown in Test Example 1 1 was melted at 500 ° C to make a slurry. The ash trap layer was formed by coating and filling with a thickness of 5 mm adjacent to the sealing portion of the system structure to obtain a filter.

(Example 1 2)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) In the honeycomb structure of (1) above, the sulfide flux shown in Test Example 12 was dissolved at 570 ° C to form a slurry, and the slurry was sealed at the downstream end in the exhaust inflow side cell. Poured at a thickness of 5 mm adjacent to the stopper, an ash trap layer was formed to provide a filter.

(Example 1 3)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) In the honeycomb structure of (1) above, the sulfide-based flux shown in Test Example 13 is melted at 5300C to make a slurry, and the slurry is used as a sealing part of the honeycomb structure. Adjacent to each other at a thickness of 5 mm, an ash wrap layer was formed to form a filter.

(Example 1 4)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) In the honeycomb structure of (1) above, the chloride-containing flux shown in Test Example 14 was dissolved at 550 ° C to form a slurry, and the slurry was placed at the downstream end of the exhaust inflow side cell. An ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Example 15)

(1) A honeycomb structure similar to (1) of Example 1 was used.

(2) In the honeycomb structure of (1) above, the chloride-containing flux shown in Test Example 15 was dissolved at 480 ° C to form a slurry, and the slurry was placed at the downstream end in the exhaust inflow side cell. Poured at a thickness of 5 mm adjacent to the sealing part, an ash trap layer was formed and used as a filter.

(Example 16) (1) A honeycomb structure similar to (1) of Example 1 was used.

(2) In the honeycomb structure of (1) above, the chloride-containing flux shown in Test Example 16 was dissolved at 4800 ° C to form a slurry, and the slurry was downstream end in the exhaust inflow side cell. A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion of the filter.

(Comparative Example 1)

(1) A honeycomb structure was only produced in the same manner as (1) of Example 1, but no ash trap layer was formed.

(Example 1 7)

(1) 80% by weight of silicon carbide powder with an average particle size of 30_im and an average particle size of 0.

5 μm silicon carbide powder 20% by weight is wet-mixed, and 6 parts by weight of organic binder (methylcellulose) and 2.5 parts by weight of surfactant are added to 100 parts by weight of the obtained mixed powder. A raw material paste was prepared by adding 24 parts by weight of water and kneading.

Next, the raw material paste was filled into an extrusion molding machine, and a green body having substantially the same shape as the porous ceramic member 30 shown in FIG. 23 was produced at an extrusion speed of 10 cm / min.

After the formed form is dried using a microphone mouth wave dryer to form a ceramic dry body, a sealing material paste having the same composition as that of the formed form is filled into one end of a predetermined through hole, and then again. It was dried using a drier and further degreased at 55 ° C. for 3 hours in an oxidizing atmosphere to obtain a ceramic degreased body. By firing the above ceramic degreased body under a normal pressure argon atmosphere at 2 15 ° C. for 2 hours, the porosity is 45%, the average pore diameter is 10 m, and the size is 34.3. A porous ceramic member of mm X 3 4.3 mm x 25 4 mm was produced.

(2) Alumina fiber with a fiber length of 20 m 30% by weight, average particle size 0.

6 m silicon carbide particles 2 1% by weight, silica sol 15% by weight, Karpoki A number of the above porous ceramic members are bound by the method described with reference to FIG. 5 using a heat-resistant sealing material pace 含む containing 5.6% by weight of dimethyl cellulose and 28.4% by weight of water, and subsequently. A cylindrical ceramic block with a diameter of 144 mm was manufactured by cutting with a diamond force utter.

At this time, the thickness of the sealing material layer for binding the porous ceramic member was adjusted to 1.0 mm.

Next, ceramic fiber made of alumina silicate as inorganic fiber (Shock content: 3%, fiber length: 5 to 100 jum) 2 3.3% by weight, average as inorganic particles Silicon carbide powder with a particle size of 0.3 m 30.2% by weight, silica sol as inorganic binder (content of Sio _{2 in} sol: 30% by weight) 7% by weight, carboxymethyl cereal as organic binder 0.5% by weight of roulose and 39% by weight of water were mixed and kneaded to prepare a sealing material case 卜.

A seal material paste layer having a thickness of 1.0 mm was formed on the outer periphery of the ceramic block using the seal material paste. The seal material paste layer was dried at 120 ° C. to produce a honeycomb structure having a cylindrical shape and functioning as a honeycomb filter for exhaust gas purification.

(3) in the filter, and the P ₂ 0 ₃ based glass, such as shown in Test Example 1 slurried dissolved in 40 0 ° G, adjacent the slurry to the sealing portion of the downstream end of the exhaust inlet-side in the cell Then, it was sprayed to a thickness of 5 mm to form an ash trap layer to obtain a filter.

(Example 1 8)

(1) A honeycomb structure was manufactured in the same manner as in (1) to (2) of Example 17.

(3) the honeycomb structure manufactured in the above (1), and the slurry dissolved by UNA P ₂ 0 ₃ based glass shown in Test Example 2 5 00 ° C, the slurry One was sprayed to a thickness of 5 mm adjacent to the sealing part at the downstream end in the exhaust gas inflow side cell to form an ash trap layer, which was used as a filter. (Example 1 9)

(2) the honeycomb structure manufactured in (1), and the slurry dissolved by UNA P ₂ 0 ₃ based glass shown in Test Example 3 in 3 00 ° C, in the slurry one exhaust inlet cells An ash trap layer was formed by spraying to a thickness of 5 mm adjacent to the sealing portion at the downstream end to obtain a filter. (Example 2 0)

(2) In the honeycomb structure manufactured in (1) above, the CaSO ₄ glass shown in Test Example 4 was melted at 75 ° C. to make a slurry, and the slurry was placed at the downstream end in the exhaust inflow side cell. The ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Example 2 1)

(2) In the honeycomb structure manufactured in (1) above, the GaSO ₄ glass shown in Test Example 5 is melted at 700 ° C. to form a slurry, and the slurry is sealed at the downstream end in the exhaust inflow side cell. The filter was applied and filled with a thickness of 5 mm adjacent to the stopper to form an ash trap layer, which was used as a filter.

(Example 2 2)

(2) The CaSO shown in Test Example 6 was added to the honeycomb structure manufactured in (1) above. _{The quaternary} glass is melted at 58 ° C. to make a slurry, and the slurry is poured into a 5 mm thickness adjacent to the downstream end sealing portion in the exhaust inflow side cell to form an ash trap layer, Filter.

(Example 2 3)

(2) In the honeycomb structure manufactured in (1) above, the CaSO ₄ glass shown in Test Example 7 is melted at 7700C to make a slurry, and the slurry is placed at the downstream end in the exhaust inflow side cell. The ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Example 24)

(2) In the honeycomb structure manufactured in (1) above, the CaSO ₄ glass shown in Test Example 8 was melted at 730 ° C. to make a slurry, and the slurry was placed at the downstream end in the exhaust inflow side cell. The ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Example 2 5)

(2) In the honeycomb structure manufactured in (1) above, the CaSO ₄ glass shown in Test Example 9 was melted at 65 ° C. to make a slurry, and the slurry was placed at the downstream end in the exhaust inflow side cell. A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Example 26)

(1) A honeycomb structure was manufactured in the same manner as in (1) to (2) of Example 17. (2) the honeycomb structure manufactured in the above (1), in the slurry by dissolving CAS0 ₄ glass shown in Test Example 1 0 7 00 ° C, the downstream end of the exhaust inlet-side in the cell the slurry A ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Example 2 7)

(2) the honeycomb structure manufactured in the above (1), in the slurry by dissolving CAS0 ₄ glass shown in Test Example 1 1 5 00 ° C, the downstream end of the exhaust inlet-side in the cell the slurry The filter was applied and filled with a thickness of 5 mm adjacent to the sealing portion to form an ash trap layer to obtain a filter.

(Example 2 8)

(2) In the honeycomb structure manufactured in (1) above, a sulfate flux as shown in Test Example 12 was dissolved at 5700 ° C. to form a slurry, and the slurry was placed in the exhaust inflow side cell. Next, the ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion at the downstream end of the filter. (Example 29)

(2) In the honeycomb structure manufactured in (1) above, a sulfate flux as shown in Test Example 13 is dissolved at 5300 ° C to form a slurry, and the slurry is placed in the exhaust inflow side cell. Then, the ash trap layer was formed by coating and filling with a thickness of 5 mm adjacent to the sealing portion at the downstream end of the filter to obtain a filter. (Example 30)

(1) A honeycomb structure was manufactured in the same manner as (1) to (2) in Example 17 Made.

(2) To the honeycomb structure manufactured in (1) above, a chloride-containing flux as shown in Test Example 14 was dissolved at 55 ° C to make a slurry, and the slurry was placed in the exhaust inflow side cell. Next, the ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion at the downstream end of the filter.

(Example 3 1)

(2) In the honeycomb structure manufactured in (1) above, a chloride-containing flux as shown in Test Example 15 was melted at 4800C to make a slurry, and the slurry was placed in the exhaust inflow side cell. Next, the ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion at the downstream end of the filter. (Example 3 2)

(2) In the honeycomb structure manufactured in (1) above, Test Example 16 6 Chloride-containing flux was melted at 4800C to make a slurry, and the slurry was placed at the downstream end in the exhaust inflow side cell. An ash trap layer was formed by pouring in a thickness of 5 mm adjacent to the sealing portion to obtain a filter.

(Comparative Example 2)

(1) A honeycomb structure was only manufactured in the same manner as (1) to (2) in Example 17 and no ash trap layer was formed.

(Example 3 3)

(1) Ash trap and catalyst application process to inorganic fibers

Alumina fibers (average fiber diameter: 5 m, average fiber length: 0. 3 mm), and was impregnated 2 minutes to the slurry one was melted to P ₂ 0 ₃ system glass 400 ° C, as shown in Test Example 1 Alumina slurry carrying Pt (Pt concentration: 5 Wt%) was impregnated for 2 minutes, and then heated to the slurry preparation temperature of each ash trap to prepare an alumina fiber with a catalyst attached. As a result, the supported amount of Pt is 0.

2 4 g.

(2) Process for preparing papermaking slurry

Next, the alumina fiber obtained in step (1) is dispersed at a rate of 10 g per 1 liter of water, and in addition, silica sol is added to the fiber as an inorganic binder. Acrylate latex was added at a rate of 3 wt% as an organic binder. Furthermore, a slurry for papermaking was prepared by adding a small amount of aluminum sulfate as a coagulant and a small amount of polyacrylamide as a coagulant and stirring sufficiently.

(3) Papermaking process

From the slurry obtained in (2) above, a 4.5 mm 4.5 mm hole was formed on the entire surface with a distance of 2 mm between each other, and a 13.4.8 mm diameter hole opening mesh was used. The resulting product was dried at 150 ° C to form a 1 mm thick sheet with 4.5 mm x 4.5 mm holes formed at 2 mm intervals on the entire surface. I got Shi Ai.

In addition, in order to obtain a sheet for both ends, a 4.5 mm X 4.5 mm hole with a checkered pattern is used, and paper making and drying are performed in the same manner. Papermaking sheet B in which holes of mm X 4.5 mm were formed in a checkered pattern was obtained.

(4) Lamination process

A casing (cylindrical metal container) with a holding bracket attached on one side was erected so that the side on which the bracket was attached was down. Then, after three sheets of paper sheet B were laminated, 150 sheets of paper sheet A 1 were laminated, and finally three paper sheets were laminated, and further pressed, and then the other sheet was also used for restraining. By installing and fixing the bracket, the length is 1 A honeycomb structure composed of a 50 mm laminate was manufactured and used as a filter. The amount of Pt supported on this honeycomb structure was 5 gZl. In this step, the sheets were laminated so that the through holes overlapped.

(Example 3 4)

Except that the slurry scratch dissolved P ₂ 0 ₃ based glass, as shown in Test Example 2 5 00 ° C is to manufacture the laminated honeycomb structured body in the same manner as in Example 3 3, and a filter.

(Example 3 5)

Except that the slurry scratch P ₂ 0 ₃ based glass such as that shown in Test Example 3 was dissolved in 3 00 ° C is to manufacture the laminated honeycomb structured body in the same manner as in Example 3 3, and a filter.

(Example 36)

Except that the slide Li one by dissolving CAS0 ₄ glass as shown in Test Example 4 7 50 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 3 7)

Except that the slurries by dissolving CAS0 ₄ glass as shown in Test Example 5 7 00 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 3 8)

Except that the slurries by dissolving GaS0 ₄ glass as shown in Test Example 6 in 5 8 0 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 3 9)

Except that the slurries by dissolving CAS0 ₄ glass as shown in Test Example 7 by 7 7 0 ° C, the laminated honeycomb structured body in the same manner as in Example 3 3 Manufactured and used as a filter.

(Example 40)

Except that the slurries by dissolving CAS0 ₄ glass as shown in Test Example 8 7 3 0 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 4 1)

Except that the slurries by dissolving CAS0 ₄ glass as shown in Test Example 9 6 5 0 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 4 2)

Except that the slurries by dissolving CAS0 ₄ glass as shown in Test Example 1 0 One at 0 0 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 4 3)

Except that the slurries by dissolving CAS0 ₄ glass as shown in Test Example 1 1 5 0 0 ° C, the same procedure as in Example 3 3 to manufacture a laminated honeycomb structured body, and a filter.

(Example 4 4)

A laminated honeycomb structure was produced as a filter in the same manner as in Example 33 except that a sulfide-based flux as shown in Test Example 12 was melted at 5700C to make a slurry.

(Example 4 5)

A laminated honeycomb structure was manufactured and used as a filter in the same manner as in Example 33, except that a sulfide-based flux as shown in Test Example 13 was melted at 530 ° C to form a slurry.

(Example 4 6)

Test Example 14 Dissolve a chloride-containing flux as shown in 4 at 55 ° C. A laminated honeycomb structure was produced in the same manner as in Example 33 except that the slurry was made into a slurry.

(Example 4 7)

Test Example 15 A laminated honeycomb structure was produced in the same manner as in Example 33, except that a chloride-containing flux as shown in 5 was dissolved at 4800 ° C. into a slurry. It was.

(Example 4 8)

A laminated honeycomb structure was produced in the same manner as in Example 33 except that a chloride-containing flux as shown in Test Example 16 was dissolved at 4800 ° C to form a slurry. Filter.

(Comparative Example 3)

A honeycomb structure was manufactured in the same manner as in Example 33, except that the ash trap was not formed in (1) of Example 33.

The honeycomb structure manufactured according to each of the above-described Examples 1 to 48 and Comparative Examples 1 to 3 was disposed in the exhaust passage of the engine as a particulate filter to form an exhaust gas purification device. Then, the above engine is operated at a rotational speed of 300 min-1 and torque of 50 Nm until a particulate of 8 g I is collected in the filter, and then a regeneration process for burning the particulates. Was applied 1 5 0 times.

After that, the filter was cut and the presence or absence of ash was visually confirmed.

Tables 2 to 4 show the manufacturing conditions and the presence or absence of ash absorption by the ash trap layer for each example. (Table 2)

(Table 3)

(Table 4)

As shown in Tables 2 to 4, it was confirmed that ash absorption occurred in the honeycomb structures of the examples. Industrial applicability

As described above, the filter according to the present invention not only removes particulates in exhaust gas discharged from an internal combustion engine such as a diesel engine, but also by combustion during regeneration to remove the particulates. The produced ash is useful for being taken in and fixed by an ash-wrapped layer made of a glassy material or an inorganic compound-based flux material.

Claims

The scope of the claims

1. A filter for purifying exhaust gas discharged from an internal combustion engine, wherein an ash trap layer is provided in an exhaust gas inflow side cell of the filter.

2. The filter according to claim 1, wherein the ash trap layer is made of a glassy material.

3. The filter according to claim 1 or 2, wherein the ash trap layer is made of low melting point glass.

4. The filter according to claim 1, wherein the ash trap layer force is composed of a low-melting-point inorganic compound-based flux material.

5. The ash wrapping layer is provided in the vicinity of an in-cell sealing portion of an integral-type, aggregate-type honeycomb structure, or laminated honeycomb structure. The filter described in the section.

6. The filter according to any one of claims 1 to 4, wherein the ash trap layer is provided on a partition wall surface of the honeycomb structure.

7. In an exhaust gas purification apparatus for an internal combustion engine in which a filter for collecting particulate matter contained in the exhaust gas is installed in the exhaust gas passage of the internal combustion engine, in the exhaust gas inflow side cell of this filter, An exhaust gas purifying device for an internal combustion engine, characterized in that an ash-wrap layer is provided.

8. The exhaust gas purifying device for an internal combustion engine according to claim 7, wherein the filter is formed of an integral type, a collective type honeycomb structure, or a laminated type honeycomb structure.

9. The ash trap layer is made of a glassy material. The exhaust gas purifying device for an internal combustion engine according to claim 7, wherein the exhaust gas purifying device is an internal combustion engine.

10. The exhaust gas purifying device for an internal combustion engine according to claim 7 or 9, wherein the ash soot wrap layer is made of low melting point glass.

11. The exhaust gas purifying device for an internal combustion engine according to claim 7, wherein the ash trap laminar force is composed of a low-melting-point inorganic compound-based flux.

12. The ash trap layer is provided in the vicinity of an in-cell sealing portion of an integral type, an aggregate type honeycomb structure or a laminated honeycomb structure. The exhaust gas purification device for an internal combustion engine according to any one of claims 1 to 3.

13. The exhaust gas purifying device for an internal combustion engine according to any one of claims 7 to 11, wherein the ash trap layer is provided on a partition wall surface of the honeycomb structure.

14. In a method for collecting and purifying particulate matter in exhaust gas exhausted from an internal combustion engine by a filter mounted in an exhaust gas passage of an exhaust gas purification device, in the exhaust gas inflow side cell of the filter An exhaust gas for an internal combustion engine characterized in that an ash trap layer is provided in the ash trap layer, and the ash contained in the particulate matter is trapped and accumulated in the ash trap layer, and is trapped and removed at a specific position in the filter. Purification method.