JP2001187344A - Waste gas cleaning material and waste gas cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste gas cleaning material and a waste gas cleaning device improved in the reaction efficiency of a waste gas with a catalyst and the collecting efficiency to enable to efficiently combusting particulates. SOLUTION: The waste gas cleaning material 1 is constituted so as to alternately seal one of a gas inlet side and a gas outlet side of each adjacent air permeable cell of a wall through type filter 2 composed of a combined body of the air permeable cells, which are partitioned by a gas permeable partition, and is formed by applying a waste gas cleaning catalyst 4 having a main crystal structure of CuV2O6 (c), in which the molar ratio (a:b) of copper element (a) to vanadium element (b) is 1:1.5 to 1:3.5 and the molar ratio (c:d) of a copper vanadium compound (c) to cesium sulfate (d) is 1:3 to 1:3.5, on the inside surface of the air permeable cells.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying material for purifying by burning particulates (solid carbon fine particles, liquid or solid high molecular weight hydrocarbon fine particles) contained in exhaust gas discharged from a diesel engine. And an exhaust gas purifying apparatus.

[0002]

2. Description of the Related Art Particulates contained in exhaust gas from a diesel engine have a particle diameter of about 1 μm or less, easily float in the atmosphere, and contain carcinogenic substances. It is becoming a problem, and regulations on particulate emissions from diesel engines are being tightened.

As one method of removing particulates from exhaust gas, after collecting the particulates with an exhaust gas purifier composed of a heat-resistant structure, the exhaust gas purifier is heated by heating means such as a burner or a heater. There is a method of burning particulates and converting them into carbon dioxide gas.
Further, as the exhaust gas purifying material, the exhaust gas purifying body described above carries an exhaust gas purifying catalyst made of a metal oxide or the like. In this case, the collected particulates are catalyzed by the catalytic action of the exhaust gas purifying catalyst. It can be burned at a lower temperature than when it is not.

[0004] If the particulates can be burned at the temperature of the exhaust gas using the exhaust gas purifying material carrying such an exhaust gas purifying catalyst, there is no need to arrange a heating means in the exhaust gas purifying apparatus. Can be simplified.

However, at present, it is difficult for the exhaust gas purifying material carrying the exhaust gas purifying catalyst to sufficiently burn the particulates at the exhaust gas temperature, and it is indispensable to use it together with a heating means. Therefore, development of an exhaust gas purifying catalyst having a high catalytic activity capable of burning particulates at a lower temperature is desired.

As exhaust gas purifying catalysts, C-
It is known that those using metal oxides such as u and V have relatively high activity. For example, JP-A-58-14
No. 3840 (hereinafter abbreviated as “A”) discloses:
An exhaust gas purifying catalyst comprising a composite metal oxide containing Cu and V is disclosed. Also, Japanese Patent Application Laid-Open No. 58-174236
Publication (hereinafter abbreviated as Publication B) includes Cu,
An exhaust gas purifying catalyst in which an alkali metal is added to a metal oxide such as V or Mo is disclosed. In addition, 4-42
No. 063 (hereinafter abbreviated as C), C
There is disclosed an exhaust gas purifying catalyst in which an alkali metal oxide and a noble metal are added to a metal oxide such as u, Mn, and Mo.

[0007]

However, the exhaust gas purifying material carrying the exhaust gas purifying catalyst described in Japanese Patent Application Laid-Open Publication Nos. A, B, and C discloses that the supplied exhaust gas and the exhaust gas purifying catalyst are efficiently used. The catalytic activity of the exhaust gas purifying catalyst cannot be fully utilized because it does not have a structure for contacting and collecting the exhaust gas, and the particulates in the exhaust gas pass without being trapped, resulting in an exhaust gas purification rate. Was low.

Further, since the exhaust gas purifying catalyst and the exhaust gas purifying material carried by the exhaust gas purifying catalyst do not have a structural state for maintaining a good contact state with the exhaust gas and efficiently causing a catalytic reaction, the exhaust gas purifying catalyst is trapped by the exhaust gas purifying material. There is a problem that the collected particulates cannot be sufficiently burned at the exhaust gas temperature.

The present invention solves the above-mentioned conventional problems, and provides an exhaust gas purifying material and an exhaust gas purifying apparatus capable of increasing the reaction efficiency and trapping efficiency between an exhaust gas and a catalyst and efficiently burning particulates. The purpose is to provide.

[0010]

The exhaust gas purifying material of the present invention comprises a gas inlet side or a gas outlet side of each adjacent ventilation cell of a wall-through filter comprising an aggregate of ventilation cells separated by gas-permeable partitions. Are alternately plugged, and a copper element (a) whose main crystal structure is CuV ₂ O ₆
And the molar ratio (a: b) of the vanadium element (b) is 1: 1.
The molar ratio (c: d) of the copper vanadium compound (c) of 5 to 1: 3.5 and the cesium sulfate (d) is 1: 3 to 1: 3.
5 is formed by coating the exhaust gas purification catalyst on the inner wall surface of the ventilation cell.

As a result, it is possible to provide an exhaust gas purifying material and an exhaust gas purifying apparatus which can increase the reaction efficiency and the trapping efficiency between the exhaust gas and the catalyst and efficiently burn the particulates.

[0012]

The exhaust gas purifying material according to the first aspect of the present invention is a gas inlet side or a gas outlet of each adjacent ventilation cell of a wall-through filter comprising an aggregate of ventilation cells separated by gas-permeable partitions. A copper element (a) having a main crystal structure of CuV ₂ O ₆ with one of the sides alternately plugged
And the molar ratio (a: b) of the vanadium element (b) is 1: 1.
The molar ratio (c: d) of the copper vanadium compound (c) of 5 to 1: 3.5 and the cesium sulfate (d) is 1: 3 to 1: 3.
5 is formed by coating the exhaust gas purification catalyst on the inner wall surface of the ventilation cell.

As a result, the following effects can be obtained.

(A) Since the gas inlet side or the gas outlet side of each adjacent ventilation cell of the wall-through type filter is alternately plugged, the exhaust gas supplied to the exhaust gas purifying material is covered with the exhaust gas purifying catalyst. The exhaust gas and the exhaust gas purifying catalyst can be reliably brought into contact with each other through the gas permeable partition wall, so that the trapped particulates in the exhaust gas can be efficiently burned.

(B) Since the main crystal structure of the exhaust gas purifying catalyst is CuV ₂ O ₆ and contains a copper vanadium compound and a cesium sulfate at a specific ratio in a specific ratio, a plurality of different oxidation states can be taken. It is possible to improve the exhaust gas purification efficiency by effectively utilizing the excellent catalytic activity by mixing copper and vanadium.

(C) Since cesium sulfate is added to the exhaust gas purifying catalyst, the strength of the sintered body of the exhaust gas purifying catalyst formed by firing a mixture containing a copper vanadium compound is improved to improve the durability. Can be.

(D) Cesium sulfate can function as a catalyst for oxidizing or reducing the sulfide component in the exhaust gas, and in this case, the action of purifying the exhaust gas can be further improved.

(E) Since the molar ratio between the copper vanadium compound and the cesium sulfate is limited to a specific range in which the catalytic activities of both can be exhibited most synergistically, the solid carbon fine particles in the particulate can be effectively used. Can be burned.

(F) Since the main crystal structure is CuV ₂ O ₆ , the copper element and the vanadium element can be stably maintained in a specific range in which they function most efficiently as a combustion catalyst.

Here, the wall-through type filter is
For example, the length in the exhaust gas supply direction is about 120 to 250 m
m, a columnar shape having a diameter of 100 to 250 mm, or a rectangular parallelepiped, and a large number of ventilation cells are assembled in the axial direction of the cylinder or the lengthwise direction of the rectangular parallelepiped. The ventilation cell has, for example, a square flow path cross section. The number of ventilation cells is 100 to 250 per 2.54 cm 2, and the exhaust gas is passed through the ventilation cell. From the side to the exit side.

In the wall-through type filter, a plastic raw material to which a binder is added is supplied to a mold and extruded into a shape having a large number of ventilation cells, or a slurry in which the raw material is dispersed is poured into a mold and cured. Can be molded. Ceramic materials such as alumina, alumina-silica, zirconia, titania, magnesia, aluminum titanate, cordierite, mullite, silicon carbide, boron carbide, silicon nitride, aluminum nitride and sialon are used for the material of this wall-through filter. it can. The partition part of this ventilation cell, that is, the body part of the wall-through type filter has a gas permeability that allows the supplied exhaust gas to pass therethrough, and the tissue state such as pore diameter and distribution state is adjusted. is there.

One of the exhaust gas inlet side and the outlet side of each of the ventilation cells adjacent to each other of the wall-through type filter is made of alumina, silica, magnesia, or a crystalline or vitreous material composed of a composite oxide component thereof. It is filled and sealed with a mixture of an inorganic powder and an organic binder or an inorganic binder. This allows the supplied exhaust gas to pass through the gas-permeable partition walls of each of the ventilation cells constituting the wall-through filter, thereby forming an exhaust gas flow path, and allowing the exhaust gas flow path to efficiently contact the catalyst on the ventilation cell, Catalytic reactions can take place.

As the copper vanadium compound, for example, C
u_FiveV_TwoO_Ten, CuV_TwoO₆, Cu_ThreeV_TwoO ₈Can be used
Or the form of a composite oxide in which two or more of these are mixed
It can also be used in a state.

The exhaust gas purifying catalyst is formed, for example, by forming a layer of a mixture containing a copper vanadium compound and cesium sulfate on the wall surface in a ventilation cell of a wall-through type filter and firing it at a predetermined temperature if necessary. ~ Several tens of μ
m of the catalyst layer.

If the molar ratio of the copper vanadium compound to the cesium sulfate is less than 1: 3, the amount of cesium sulfate increases, and the cesium sulfate covers the copper vanadium compound. The amount that can be contacted with the soot is insufficient, and a substantial catalytic function cannot be exhibited. On the other hand, if the weight ratio is more than 1: 3.5, the amount of cesium sulfate is insufficient, and the catalytic activity due to the synergistic effect cannot be sufficiently exhibited.

[0026] In the exhaust gas purifying material according to claim 2, the gas permeable partition wall of the wall-through type filter is cordierite and the total pore volume is 0.2.
cc / g or more, the volume of pores having a pore diameter of 10 μm or more is 40 to 60% of the total pore volume, and the average pore diameter is 8 to 20 μm.
m, the porosity is 40-60%.

Thus, the following operation can be obtained in addition to the operation of the first aspect.

(A) Since the gas permeable material is cordierite having a small change in thermal expansion and the conditions of the permeable structure are set, the pressure loss at the time of supplying the exhaust gas to the exhaust gas purifying material is suppressed, and the gas is efficiently used. The particulates in the exhaust gas are captured, and the catalyst supported on the gas flow path is acted on, so that the particulates can be efficiently burned.

(B) Since the coefficient of thermal expansion can be reduced by using cordierite, the difference in thermal expansion caused by severe temperature fluctuation at the time of mounting and using in a manifold of an automobile can be reduced. It is possible to make the exhaust gas purifying material excellent in long-term durability by suppressing the occurrence of cracks, spalling and the like by making it small.

(C) The contact between the solid carbon fine particles in the particulates and the catalyst during purification is optimized, and the particulates can be purified without accumulating in the exhaust gas purifying material.

Here, when the total pore volume of cordierite is less than 0.2 cc / g, gas permeability is insufficient, and particulates are easily deposited in the filter, which is a factor of deteriorating the catalytic function. Also, the hole diameter is 10 μm
When the volume of the above pores is smaller than 40% of the total pore volume, the average pore diameter is smaller than 8 μm, and the porosity is smaller than 40%, it is difficult to secure gas permeability necessary for a gas filter. Become. Conversely, the volume of pores having a pore diameter of 10 μm or more is 60% of the total pore volume, and the average pore diameter is 20 μm.
When the m and the porosity are each greater than 60%, adverse effects such as a decrease in the strength of a structure required as a gas filter are undesirably increased.

According to a third aspect of the present invention, in the exhaust gas purifying material according to the first aspect, the gas permeable partition wall of the wall-through type filter is aluminum titanate obtained by extrusion molding, and has an average pore diameter of 8 to 42 μm. The porosity is 29 to 63 μm, and the coefficient of thermal expansion α _{a in the} extrusion direction is −
2.3 × 10 ⁻⁶ ° C. ^{−1 to} 0 × 10 ⁻⁶ ° C. ⁻¹ , and a thermal expansion coefficient α _{b in} a direction perpendicular to the extrusion direction is 0 × 10 ⁻⁶ ° C. ^{−1 to} 2.4.
It is configured to be × 10 ⁻⁶ ° C. ⁻¹ .

Thus, the following operation can be obtained in addition to the operation of the first aspect.

(A) Since the body of the wall-through type filter is made of aluminum titanate having a small coefficient of thermal expansion, and the coefficient of thermal expansion in a specific direction, the average pore diameter, and the porosity are set in predetermined ranges, An exhaust gas purifying material having excellent thermal shock resistance and gas permeability can be provided.

(B) The contact between the solid carbon fine particles in the particulates and the catalyst at the time of purification is optimized, and the particulates are purified without accumulating in the exhaust gas purifying material. Heat resistance is improved, and it has the effect of preventing cracking and melting during particulate purification.

Here, the average pore diameter is 8 μm and the porosity is 2
If each is less than 9%, it will be difficult to ensure sufficient gas permeability. Conversely, if the average pore diameter is greater than 42 μm and the porosity is greater than 63%, however, the mechanical strength is insufficient and the durability is deteriorated, which is not preferable.

The coefficient of thermal expansion α _{a in the} extrusion direction is -2.3.
If the coefficient of thermal expansion α _{b in the} direction perpendicular to the extrusion direction is smaller than 0 and smaller than × 10 ^-6 ° C. ^-1 , the thermal expansion in both directions acts in a state where cracks and the like are likely to occur when the temperature changes. It is not preferable because it may be performed. A similar tendency appears when the thermal expansion coefficient α _{a in} the extrusion direction is larger than 0 and the thermal expansion coefficient α _{b in the} direction perpendicular to the extrusion direction is larger than 2.4 × 10 ⁻⁶ ° C. ⁻¹ . Not preferred.

According to a fourth aspect of the present invention, in the exhaust gas purifying material according to the first aspect, the gas permeable partition wall of the wall-through type filter is made of silicon carbide and has an average pore diameter of 6 to 15 μm.
m, the porosity is 42 to 53%.

Thus, the following operation can be obtained in addition to the operation of the first aspect.

(A) Since silicon carbide does not undergo creep deformation even when subjected to high temperatures for a long time, has high thermal conductivity and is resistant to temperature fluctuations, it prevents cracking and melting damage during particulate purification. To improve heat resistance.

(B) SiO formed by oxidizing silicon carbide
_The reaction of the exhaust gas purifying catalyst composed of the copper vanadium compound and cesium sulfate with the wall-through type silicon carbide filter body can be prevented by interposing the coating of ( ₂ ).

Here, the average pore diameter of silicon carbide is 6 μm.
When m and the porosity are smaller than 42%, it is difficult to secure sufficient gas permeability. Conversely, if the average pore diameter is greater than 15 μm and the porosity is greater than 53%, however, the mechanical strength is insufficient and the durability is deteriorated, which is not preferable.

According to a fifth aspect of the present invention, there is provided an exhaust gas purifying honeycomb body having the exhaust gas purifying material according to any one of the first to fourth aspects arranged upstream of an exhaust gas flow and carrying a noble metal. It is arranged downstream of the exhaust gas flow.

As a result, the following effects can be obtained.

(A) By providing an exhaust gas purifying material and an exhaust gas purifying honeycomb body having different catalytic characteristics and exhaust gas flow path characteristics from each other independently and continuously, the exhaust gas purifying on the upstream side is performed. The soot in the particulates in the exhaust gas is reliably captured and burned by the material, and the exhaust gas purification honeycomb body on the downstream side efficiently removes harmful components such as SOF, carbon monoxide, and hydrocarbons, which are the remaining particulates. be able to.

(B) Since the exhaust gas honeycomb body containing the noble metal is provided on the downstream side, the exhaust gas from which the noble metal and the particulates have been removed in advance is brought into contact with the noble metal, so that the activity of the noble metal catalyst can be effectively used and the noble metal can be used in the particulate form. The catalyst characteristics can be prevented from deteriorating due to contact with. Thereby, the required amount of the noble metal can be reduced, and the exhaust gas purifying apparatus can be manufactured at low cost.

(C) Since the exhaust gas purifying body containing the oxide of the transition metal and the honeycomb body for purifying the exhaust gas containing the noble metal are provided separately, the catalyst composition by the combination of the oxide of the transition metal and the noble metal is formed. Changes can be prevented, and the durability of each can be increased.

Here, as the exhaust gas purifying honeycomb body,
Examples include a flow-through type ceramic honeycomb, a wall-through type ceramic honeycomb, and a flow-through type metal honeycomb. A ceramic honeycomb is preferably used. Examples of the material of the ceramic honeycomb include cordierite, aluminum titanate, mullite, α-alumina, zirconia, titania, silicon carbide, and the like.

These materials are used at least in the exhaust gas temperature (approximately 350 to 45) when applied to a diesel engine.
(0 ° C.).

As the noble metal, a metal such as platinum, rhodium or palladium, which has a high heat resistance and high catalytic activity and is hardly corroded, is preferably used.

The catalyst layer supporting the noble metal of the exhaust gas purifying honeycomb body is formed by dispersing the noble metal on the particle surface of a powder of an inorganic oxide having high heat resistance such as silica, alumina, zirconia, titania or a composite thereof. This is a catalyst carrier formed by sintering these powders or compacts at a predetermined temperature or fixing them in a layer using an inorganic adhesive or the like.

The noble metals used in the exhaust gas purifying honeycomb body are as follows:
It has the function of purifying carbon monoxide and hydrocarbons, which are coexisting components in the exhaust gas that could not be captured in the upstream exhaust gas purifying material, and SOF, which is the remainder of particulates.

According to a sixth aspect of the present invention, in the exhaust gas purifying apparatus according to the fifth aspect, the exhaust gas purifying honeycomb body comprises Pt, Pt,
A catalyst for purifying a noble metal exhaust gas in which at least one of d and Rh is supported on alumina coated with silica / alumina is coated on a cordierite or aluminum titanate honeycomb body.

Thus, in addition to the function of claim 5, the following function can be obtained.

(A) Since the exhaust gas purifying honeycomb body is made of cordierite or aluminum titanate having a low coefficient of thermal expansion, it has excellent fracture resistance to thermal shock and improves its durability. Can be.

(B) Since the noble metal catalyst is supported on alumina coated with silica / alumina, the affinity between the noble metal catalyst and the alumina particles can be improved, and the noble metal catalyst is prevented from peeling from the alumina particles. Thus, the durability can be further improved.

(C) SO by the action of silica / alumina
Reaction with ₂ can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of an exhaust gas purifying material according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 1 denotes an exhaust gas purifying material according to the first embodiment, 2 denotes a wall-through filter having a large number of ventilation cells, and 3 denotes an inlet side of each ventilation cell of the wall-through filter 2 or A plugging portion in which the outlet side is plugged alternately, 4 is an exhaust gas purifying catalyst formed in layers on the inner wall surface of the ventilation cell, and 5 is an intermediary between a container 6 of the exhaust gas purifying device to which the exhaust gas purifying material 1 is mounted. It is a bulk heat insulator made of an inorganic fiber material or the like to be inserted.

The exhaust gas purifying material 1 comprises a wall-through type filter 2 made of a cordierite material in which the ends of the ventilation cells are alternately hermetically sealed with plugging portions 3, and an exhaust gas purification catalyst 4 coated on the surface of the ventilation cell. Consists of The wall-through type filter 2 having an exhaust gas ventilation passage formed by alternately plugging one end forms a skeleton of the exhaust gas purifying material 1, and has a total pore volume of 0.2 cc / g or more and 10 μm or more.
m has a pore volume of 40 to 60% and an average pore diameter of 8 to 2
When the porosity is 0 μm and the porosity is 40 to 60%, it has an action of purifying the exhaust gas by effectively burning the particulates in the exhaust gas without accumulating in the filter.

Here, when the total pore volume is 0.2 cc / g or less, the pore volume of 10 μm or more is less than 40%, the average pore diameter is less than 8 μm, and the porosity is less than 40%, the particulates are contained in the filter. And a total pore volume of 0.2 cc / g or more and a pore volume of 10 μm or more
More than 0%, the average pore size is greater than 20 μm,
Even if the porosity is larger than 40%, the amount of particulates passing through the filter is increased, and the particulates cannot be sufficiently burned and purified.

(Embodiment 2) FIG. 2 is a sectional view of an exhaust gas purifying apparatus according to Embodiment 2 of the present invention.

In FIG. 2, reference numeral 20 denotes an exhaust gas purifying apparatus according to the second embodiment, 21 denotes an exhaust gas purifying honeycomb body provided downstream of the exhaust gas purifying material 1 in the container 6 of the exhaust gas purifying apparatus 20, and 22 denotes an exhaust gas purifying honeycomb body. Noble metal catalyst coated on the inner surface of the exhaust gas channel No. 21. Components having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the exhaust gas purifying apparatus 20 of the second embodiment, one end of the ventilation cell is alternately sealed with the plugging portion 3 to form a gas flow path passing through the gas permeable partition wall, and the partition wall surface is formed by the exhaust gas purifying catalyst. A cordierite-type wall-through type filter 2 coated with 4 is disposed on the upstream side of the exhaust gas flow, and an exhaust gas purification honeycomb body 21 having a noble metal catalyst 22 coated on the exhaust gas flow path surface is disposed on the downstream side of the exhaust gas flow. It is configured. Wall-through type filter 2 arranged on the upstream side
Is a skeleton of a catalyst filter, the total pore volume of which is 0.2 cc / g or more, the pore volume of 10 μm or more is 40 to 60%, the average pore diameter is 8 to 20 μm, and the porosity is 4
When it is 0 to 60%, particulates in exhaust gas,
Among them, it mainly has a function of purifying SOOT (soot) without accumulating in the filter. The total pore volume is 0.
When the pore volume is 2 cc / g or less, the pore volume of 10 μm or more is less than 40%, the average pore diameter is less than 8 μm, and the porosity is less than 40%, the particulates are easily deposited in the filter, and the total pore volume is 0.1 μm. At 2 cc / g or more, the pore volume of 10 μm or more is more than 60%, and the average pore diameter is 20 μm.
Even if the porosity is larger than m and the porosity is larger than 40%, the amount of particulates passing through the filter increases, and the particulates cannot be sufficiently purified. The exhaust gas purifying honeycomb body 21 of the catalyst filter disposed on the downstream side forms a skeleton of the catalyst filter, and has an action of oxidizing and purifying particulates, especially SOF, and carbon monoxide and hydrocarbons in the exhaust gas. .

(Embodiment 3) The exhaust gas purifying material of Embodiment 3 is the same as the wall-through filter 2 of Embodiment 1.
Is changed from a cordierite-based material to an aluminum titanate-based material, and its arrangement is the same as that of FIG.

The exhaust gas purifying material 1 of the third embodiment comprises a wall-through type aluminum titanate filter whose one end is alternately plugged, and an exhaust gas purifying catalyst 4 coated on the surface of the aluminum titanate filter. The wall-through type aluminum titanate filter in which one end is alternately plugged forms the skeleton of the catalyst. When the average pore diameter is 8 to 42 μm and the porosity is 29 to 63%, the particle size of the filter during purification is reduced. The contact between the curate and the catalyst is optimized, and the particulates are purified without accumulating in the exhaust gas purifying material.The heat resistance of the exhaust gas purifying material is improved, and cracks and erosion during particulate purification are reduced. Has the effect of preventing. When the average pore size is less than 8 μm and the porosity is less than 29%, the particulates tend to accumulate in the filter. Conversely, even if the average pore size is greater than 42 μm and the porosity is greater than 63%, The amount of particulates passing through is increased, and the particulates cannot be sufficiently purified.

(Embodiment 4) An exhaust gas purifying apparatus according to Embodiment 4 is obtained by changing the material of the wall-through type filter 2 of Embodiment 2 from a cordierite-based material to an aluminum titanate-based material. Are the same as those shown in FIG.

The exhaust gas purifying apparatus 20 of the fourth embodiment comprises a wall-through type aluminum titanate filter having one end plugged alternately upstream of the exhaust gas flow, and a catalyst layer coated on the surface of the aluminum titanate filter. And an exhaust gas purification filter comprising a honeycomb body on the downstream side of the exhaust gas flow and a catalyst layer coated on the surface of the honeycomb body. The wall-through type aluminum titanate filter in which one end of the catalyst filter arranged alternately is plugged constitutes the skeleton of the catalyst filter, and has an average pore diameter of 8 to 42 μm and a porosity of 29 to 63. %, The contact between the particulates and the catalyst at the time of exhaust gas purification is optimized, the particulates are purified without accumulating in the exhaust gas purification material, and the heat resistance of the exhaust gas purification material is improved. It has the function of preventing cracking and melting during particulate purification. Average pore diameter of less than 8 μm, porosity of 2
When it is less than 9%, the particulates tend to accumulate in the filter, and conversely, even if the average pore diameter is greater than 42 μm and the porosity is greater than 63%, the particulates passing through the filter will increase, Particulates cannot be sufficiently purified. The honeycomb body of the catalyst filter disposed on the downstream side forms a skeleton of the catalyst filter, and has an action of purifying particulates in exhaust gas, especially SOF, carbon monoxide and hydrocarbons.

(Embodiment 5) The exhaust gas purifying material of Embodiment 5 is the same as the wall-through filter 2 of Embodiment 1.
Is changed from cordierite material to silicon carbide material.

The exhaust gas purifying material 1 of the fifth embodiment comprises a wall-through type silicon carbide filter whose one end is alternately plugged, and a layer of the exhaust gas purifying catalyst 4 coated on the surface of the silicon carbide filter. The wall-through type silicon carbide filter has an average pore diameter of 6 to 15 μm,
When the porosity is 42 to 53%, the contact between the particulates and the catalyst during purification is optimized, the particulates are purified without accumulating in the exhaust gas purification material, and the heat resistance of the exhaust gas purification material is reduced. To prevent cracking and erosion during particulate purification, and to prevent the presence of SiO present on the surface of the wall-through type silicon carbide filter.
₂ has the effect of preventing the reaction between the exhaust gas purification catalyst comprising a copper vanadium compound and cesium sulfate and the wall-through type silicon carbide filter. Average pore size is 6μ
When the porosity is less than 42% and the porosity is less than 42%, particulates tend to accumulate in the filter.
Even if it is larger than 0 μm and the porosity is larger than 53%, the amount of particulates passing through the filter increases, and the particulates cannot be sufficiently purified.

(Embodiment 6) In an exhaust gas purifying apparatus according to Embodiment 6, the material of the wall-through type filter 2 of Embodiment 2 is changed from cordierite to silicon carbide.

The exhaust gas purifying apparatus 20 of the sixth embodiment comprises a wall-through type silicon carbide filter whose one end is alternately plugged on the upstream side of the exhaust gas flow, and a catalyst layer coated on the surface of the silicon carbide filter. The exhaust gas purification filter includes an exhaust gas purification filter including a honeycomb body downstream of the exhaust gas flow and a catalyst layer coated on the surface of the honeycomb body. The wall-through type silicon carbide filter in which one end of the catalyst filter arranged alternately is plugged constitutes a skeleton of the catalyst filter, and has an average pore diameter of 6 to 15 μm and a porosity of 42 to 5 μm.
At 3%, the contact between the particulates and the catalyst during purification is optimized, and the particulates are purified without accumulating in the exhaust gas purifying material, and the heat resistance of the exhaust gas purifying material is improved. the wall-through type exhaust emission control catalyst and wall-through type silicon carbide filter made by carbonization SiO ₂ existing on the surface of silicon made filter copper vanadium compound and a cesium sulfate as to prevent cracking or melting during purifying the particulates Has the effect of preventing reactions. Average pore diameter less than 6 μm, porosity of 4
When it is less than 2%, the particulates easily accumulate in the filter, and conversely, even if the average pore diameter is greater than 10 μm and the porosity is greater than 53%, the particulates passing through the filter increase, Particulates cannot be sufficiently purified. The honeycomb body of the catalyst filter disposed on the downstream side forms a skeleton of the catalyst filter, and has an action of purifying particulates in exhaust gas, especially SOF, carbon monoxide and hydrocarbons.

[0074]

EXAMPLES Next, examples which further embody the embodiments of the present invention will be described.

Example 1 239.4 g, 48 respectively
9 g and 705.6 g of copper sulfate pentahydrate (manufactured by Nacalai Tesque), vanadium oxide sulfate (manufactured by Wako Pure Chemical Industries) and cesium sulfate (manufactured by Soegawa Rikagaku) were dissolved in 2000 g of purified water. Volume is 0.2cc / g, 10μm
Impregnated with a filter made of a wall-through type cordierite having a pore volume of 45%, an average pore diameter of 13 μm, a porosity of 48%, and a cell number of 100 cells per inch alternately plugged at one end, After removing excess solution by air blow, drying and firing are performed to obtain an exhaust gas purification filter. An exhaust gas purifying material is obtained by winding a heat insulating material around the exhaust gas purifying filter and fixing it to a predetermined container.

(Example 2) First, a method of manufacturing an exhaust gas purifying filter installed upstream of an exhaust gas flow will be described. 239.4 g, 489 g and 705.6 g respectively
Of copper pentahydrate (manufactured by Nacalai Tesque), vanadium oxide (manufactured by Wako Pure Chemical Industries) and cesium sulfate (manufactured by Soegawa Rikagaku) in 2,000 g of purified water had a total pore volume of 0.2 cc. / G, pore volume of 10 μm or more is 45
%, An average pore diameter of 13 μm, a porosity of 48%, and a filter made of a wall-through type cordierite alternately plugged at one end with 100 cells per inch. After removal, drying and firing are performed to obtain an exhaust gas purification filter. Next, a method of manufacturing an exhaust gas purifying filter installed on the downstream side of the exhaust gas flow will be described. 375 g of aluminum nitrate (manufactured by Wako Pure Chemical Industries) is added to 5 L of purified water, stirred, and activated alumina (Sumitomo Chemical) is added to the solution. (Manufactured by Kogyo Co., Ltd.) and stirred for 24 hours. Next, 90 g of sodium silicate and 99.5 g of sodium hydroxide are added to precipitate a silica-alumina precursor on the surface of the activated alumina. The solution is thoroughly washed, dried and fired in air. Next, activated alumina 14 coated with the silica-alumina was added to a mixed solution obtained by adding 720 g of a dispersant (manufactured by Kao) to 2.5 L of pure water.
Add 00g and mix for 20hrs to make a slurry. This slurry was diluted with the same solution as the above-mentioned mixed solution so that the powder concentration became 1/3, and a cordier having a diameter of 5.66 inches, a length of 6 inches and a cell number of 400 cells / square inch was added to the diluted slurry. After dipping and lifting the honeycomb structure made of light, excess slurry is removed by air blow, and then dried at 300 ° C. This operation is repeated several times to coat a predetermined amount, and then fired in the air. Next, the honeycomb structure was immersed in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water, and after being pulled up, an excess solution was removed by air blow, followed by drying by a freeze-drying method, followed by drying in air. Baking. Finally, 5L of pure water
A predetermined amount of dinitrodiaminoplatinum nitric acid solution, the honeycomb structure carrying palladium is immersed in a solution of citric acid, and after pulling up, an excess solution is removed by air blow and then dried by a freeze-drying method. By firing in a reducing atmosphere, an exhaust gas purification filter is obtained.

An exhaust gas purifying material is obtained by wrapping a heat insulating material around each of the exhaust gas purifying filters and fixing it at a predetermined position in a predetermined container.

Example 3 A filter supporting an exhaust gas purifying catalyst has an average pore diameter of 15 μm, a porosity of 50%,
The coefficient of thermal expansion α _{a in the} extrusion direction is −2.3 × 10 ^{−6 to} 0
℃ ^-1 , thermal expansion coefficient α _{a in the} direction perpendicular to the extrusion direction is 0
It is the same as Example 1 except that it is a wall-through type aluminum titanate filter in which one end is alternately plugged at a temperature of up to 2.4 × 10 ⁻⁶ ° C. ⁻¹ .

(Example 4) A filter carrying an exhaust gas purifying catalyst disposed on the upstream side of an exhaust gas flow has an average pore diameter of 15 µm, a porosity of 50%, and a thermal expansion coefficient α _{a in the} extrusion direction of -2.3. × 10 ^-6 ~0 ℃ ^-1, extrusion direction and wall-through type aluminum titanate thermal expansion coefficient alpha _a perpendicular direction is plugged alternately at one end is 0~2.4 × 10 ^-6 ℃ ^-1 It is the same as Example 2 except that it is a filter made.

Example 5 A filter carrying an exhaust gas purifying catalyst was a wall-through type silicon carbide filter having an average pore diameter of 9 μm and a porosity of 47%, and alternately plugged at one end. This is similar to the first embodiment.

(Example 6) A wall-through type silicon carbide filter having an average pore diameter of 9 µm and a porosity of 47% was alternately plugged, with a filter carrying an exhaust gas purifying catalyst disposed upstream of the exhaust gas flow. It is the same as Example 2 except that it is a filter made.

(Example A1) 239.4 g each, 4
89 g and 705.6 g of copper sulfate pentahydrate (manufactured by Nacalai Tesque), vanadium oxide (manufactured by Wako Pure Chemical Industries) and cesium sulfate (manufactured by Soegawa Rikagaku) were dissolved in 2000 g of purified water. The volume is smaller than 0.2 cc / g and the pore volume of 10 μm or more is out of the range of 40 to 60%,
The average pore diameter is out of the range of 8 to 20 μm, and the porosity is 40 to 6.
Out of the range of 0%, the filter is impregnated with a wall-through type cordierite filter alternately plugged at one end with 100 cells per inch, excess solution is removed by air blow, and then dried and fired. To obtain an exhaust gas purification filter. An exhaust gas purifying material was obtained by winding a heat insulating material around the exhaust gas purifying filter and fixing it to a predetermined container.

(Example A2) First, a method of manufacturing an exhaust gas purifying filter installed on the upstream side of an exhaust gas flow will be described. 239.4 g, 489 g and 705.
A solution prepared by dissolving 6 g of copper sulfate pentahydrate (manufactured by Nacalai Tesque), vanadium oxide (manufactured by Wako Pure Chemical Industries) and cesium sulfate (manufactured by Soegawa Rikagaku) in 2000 g of purified water has a total pore volume of 0. Smaller than 2 cc / g, pore volume of 10 μm or more is out of the range of 40 to 60%, and average pore size is 8 to 2
0 μm, porosity outside the range of 40-60%, 1
Impregnated with a filter made of a wall-through type cordierite alternately plugged at one end with 100 cells per inch, removing excess solution by air blow, drying and firing to obtain an exhaust gas purification filter. .

Next, a method for manufacturing an exhaust gas purifying honeycomb body installed on the downstream side of the exhaust gas flow will be described. 375 g of aluminum nitrate (manufactured by Wako Pure Chemical Industries) is added to 5 L of purified water, and the mixture is stirred. Then, 1400 g of activated alumina (manufactured by Sumitomo Chemical) is added to the solution, and the mixture is stirred for 24 hours. Next, 90 g of sodium silicate and 99.5 g of sodium hydroxide are added to precipitate a silica-alumina precursor on the surface of the activated alumina. The solution is thoroughly washed, dried and fired in air. Next, a dispersant (manufactured by Kao) 72 was added to 2.5 L of pure water.
To a mixed solution containing 0 g, 1400 g of activated alumina coated with the silica / alumina was added and mixed for 20 hours to prepare a slurry.

This slurry was diluted with the same solution as the above-mentioned mixed solution so that the powder concentration was reduced to 1/3. The diluted slurry was 5.66 inches in diameter, 6 inches in length, and 4 cells in number.
A honeycomb structure made of cordierite of 00 cells / square inch is immersed and pulled up, and after removing excess slurry by air blow, drying is performed at 300 ° C.

This operation is repeated several times to coat a predetermined amount, followed by firing in air. Next, the honeycomb structure was immersed in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water, and after being pulled up, an excess solution was removed by air blow, followed by drying by a freeze-drying method and drying in air. Baking.

Lastly, the honeycomb structure carrying palladium was immersed in a predetermined amount of dinitrodiaminoplatinic nitric acid solution and a solution of citric acid dissolved in 5 liters of pure water, pulled up, and the excess solution was removed by air blowing. Then, after drying by a freeze-drying method, it is fired in a reducing atmosphere to obtain an exhaust gas purifying honeycomb body.

A heat insulating material was wound around each of the exhaust gas purifying material and the exhaust gas purifying honeycomb body, and was fixed at a predetermined position in a predetermined container to constitute an exhaust gas purifying apparatus.

(Example A3) A filter carrying an exhaust gas purifying catalyst has an average pore diameter outside the range of 8 to 42 μm, a porosity outside the range of 29 to 63%, and a thermal expansion coefficient α _{a in the} extrusion direction of −2. Outside the range of 3 × 10 ^{−6 to} 0 ° C. ^−1, the coefficient of thermal expansion α _{a in the} direction perpendicular to the extrusion direction is 0 to 2.4 × 10
It is the same as Example 1 except that it is a wall-through type aluminum titanate filter alternately plugged at one end outside the range of ^-6 ° C- ¹ .

(Example A4) A filter carrying an exhaust gas purifying catalyst disposed on the upstream side of an exhaust gas flow has an average pore diameter outside the range of 8 to 42 μm, a porosity outside the range of 29 to 63%, and Thermal expansion coefficient α _a is -2.3 × 10 ^-6
A wall-through type titanium having one end alternately plugged out of the range of 0 ° C. ^-1 and _a coefficient of thermal expansion α _{a in the} direction perpendicular to the extrusion direction of 0 to 2.4 × 10 ^-6 ° C. ^-1 It is the same as Example 2 except that it is a filter made of aluminum acid.

(Example A5) A filter carrying an exhaust gas purifying catalyst was a wall-through type filter having an average pore diameter outside the range of 6 to 15 μm and a porosity outside the range of 42 to 53%, and alternately plugged at one end. It is the same as Example 1 except that the filter is made of silicon carbide.

(Example A6) Filters carrying an exhaust gas purifying catalyst arranged upstream of an exhaust gas flow alternately have an average pore diameter outside the range of 6 to 15 μm and a porosity outside the range of 42 to 53%. It is the same as Example 2 except that the filter is a wall-through type silicon carbide filter with one end plugged.

(Evaluation Experiment 1): Test for Evaluating Catalyst Activity The above (Example 1) to (Example 6) and (Example A1) to
After the activated carbon was uniformly placed on the filter prepared in (Example A6), the filter was set in a fixed bed flow reactor. While flowing oxygen and sulfur dioxide containing predetermined concentrations (balance gas = nitrogen) as the reaction gas, the temperature of the activated carbon was increased from room temperature to 500 ° C. while the combustion state of the activated carbon was changed to CO /
Tracking was performed using a CO ₂ sensor, and the catalyst performance (activity: unit ° C) was compared at the temperature at which activated carbon burned 5%. Further, as a durability test, after performing a heat treatment at 500 ° C. for a predetermined time, the catalyst performance was evaluated by the same test method as described above.

Tables 1 to 3 show the results of evaluation experiment 1 when cordierite, aluminum titanate and silicon carbide were used as materials, respectively, and evaluation experiment 2 in which the leak rate was determined. The results are shown together with the results.

[0095]

[Table 1]

[0096]

[Table 2]

[0097]

[Table 3]

(Evaluation Experiment 2): Test for Determining the Leakage Rate A test piece having a diameter of 70 mm and a thickness of 1 mm was obtained from the filters prepared in Examples 1 to 6 and A1 to A6. Was cut out and fixed to a holder. The holder was installed on the downstream side of the micro-dilution tunnel, which was separated from the pipe of a diesel engine with a displacement of 3400 cc and four cylinders, and the leak rate was calculated from the pressure difference between before and after the holder. )
It was shown to.

As is clear from the results shown in Table 1 above, the exhaust gas purifying materials having the exhaust gas purifying catalysts shown in Examples 1 and 2 were the same as those shown in Examples A1 and A2. In comparison, it can be seen that the combustion purification action of the particulates is good and the leak rate of the particulates is low.

That is, the exhaust gas purifying materials of Example 1 and Example 2 had a molar ratio of copper element and vanadium element of 1: 1.5 to 1.5.
1: 3.5, and its main crystal structure is CuV ₂ O
₆ , and the ratio of the copper vanadium compound and the cesium sulfate whose abundance is 25 mol% or more is 1: 3 to 1: 3.5.
Having an exhaust gas purifying catalyst,
A wall through having one end sealed alternately having a total pore volume of 0.2 cc / g or more, a pore volume of 10 μm or more of 40 to 60%, an average pore diameter of 8 to 20 μm, and a porosity of 40 to 60%. It was carried on a cordierite filter.

On the other hand, in the exhaust gas purifying materials of Examples A1 and A2, the molar ratio of copper element to vanadium element was 1: 1.
5-1: 3.5, and its main crystal structure is CuV ₂
O ₆ , and the ratio of the copper vanadium compound having an abundance of 25 mol% or more to cesium sulfate is 1: 3 to 1: 3.
Exhaust gas purifying catalyst having the characteristic of No. 5, the total pore volume is smaller than 0.2 cc / g, the pore volume of 10 μm or more is outside the range of 40 to 60%, and the average pore diameter is outside the range of 8 to 20 μm. The filter is supported on a wall-through type cordierite filter having a porosity outside the range of 40 to 60% and having one end plugged alternately.

As is clear from the results shown in Table 2, the exhaust gas purifying materials having the exhaust gas purifying catalysts shown in Examples 3 and 4 were different from those shown in Examples A3 and A4. As a result, it has been found that the particulates have a good purifying action and a low leak rate, and the heat resistance of the exhaust gas purifying material is improved, so that cracking and melting damage during particulate purification can be prevented.

The exhaust gas purifying materials shown in Examples 3 and 4 had a molar ratio of copper element to vanadium element of 1: 1.5 to 1.5.
1: 3.5, and its main crystal structure is CuV ₂ O
₆ , and the ratio of the copper vanadium compound and the cesium sulfate whose abundance is 25 mol% or more is 1: 3 to 1: 3.5.
Exhaust gas purification catalyst having an average pore diameter of 8 to 42 μm
m, the porosity is 29 to 63%, the coefficient of thermal expansion α _{a in the} extrusion direction is −2.3 × 10 ^{−6 to} 0 ° C. ⁻¹ , and the coefficient of thermal expansion α _{a in the} direction perpendicular to the extrusion direction is 0 to 2. 4 is carried to one end alternately is × 10 ^-6 ° C. ^-1 to plugging the wall-through type aluminum titanate filter is formed.

On the other hand, in Examples A3 and A4,
Exhaust gas purifying materials have a molar ratio of copper to vanadium
1: 1.5 to 1: 3.5, whose main crystal structure is
CuV _TwoO₆And the abundance ratio is 25 mol% or more.
The ratio of copper vanadium compound to cesium sulfate is 1: 3 to
1: 3.5 Exhaust gas purification catalyst
The catalyst is converted to an average pore size outside the range of 8 to 42 μm, the porosity.
Is outside the range of 29 to 63%, and the thermal expansion coefficient α in the extrusion direction is α.
_aIs -2.3 × 10^-6~ 0 ° C^-1Out of range, extrusion direction
Coefficient of thermal expansion α perpendicular to_aIs 0 to 2.4 × 10^-6° C
^-1Alternately plugged at one end outside the range
-Formed supported on aluminum titanate filter
It was done.

As is clear from the results shown in Table 3, the exhaust gas purifying materials having the exhaust gas purifying catalysts shown in Examples 5 and 6 were different from those shown in Examples A5 and A6. Therefore, the purification action of particulates is good and the leak rate is low, and the heat resistance of the exhaust gas purification material is improved,
It can prevent cracking and erosion during particulate purification, and furthermore, an exhaust gas purification catalyst comprising a copper vanadium compound and cesium sulfate by SiO ₂ present on the surface of the wall-through type silicon carbide filter and a wall-through type silicon carbide filter. It was found that the action of preventing the reaction was good.

The exhaust gas purifying materials shown in Examples 5 and 6 had a molar ratio of copper element to vanadium element of 1: 1.5 to 1.5.
1: 3.5, and its main crystal structure is CuV ₂ O
₆ , and the ratio of the copper vanadium compound and the cesium sulfate whose abundance is 25 mol% or more is 1: 3 to 1: 3.5.
Having an exhaust gas purifying catalyst,
The filter is supported on a wall-through type silicon carbide filter having an average pore diameter of 6 to 15 μm and a porosity of 42 to 53% alternately plugged at one end.

Further, it was shown in Examples A5 and A6.
Exhaust gas purifying materials have a molar ratio of copper to vanadium
1: 1.5 to 1: 3.5, whose main crystal structure is
CuV _TwoO₆And the abundance ratio is 25 mol% or more.
The ratio of copper vanadium compound to cesium sulfate is 1: 3 to
1: 3.5 Exhaust gas purification catalyst
The average pore diameter of the activated catalyst is out of the range of 6 to 15 μm, and the porosity is
Is outside the range of 42-53%, and one end is plugged alternately
Supported on wall-through type silicon carbide filter
It was formed.

[0108]

According to the first aspect of the present invention, the following effects can be obtained.

(A) Since the gas inlet side or the gas outlet side of each adjacent ventilation cell of the wall-through type filter is alternately plugged, the exhaust gas supplied to the exhaust gas purifying material is covered with the exhaust gas purifying catalyst. The exhaust gas and the exhaust gas purifying catalyst can be reliably brought into contact with each other through the gas permeable partition wall, so that the trapped particulates in the exhaust gas can be efficiently burned.

(B) Since the main crystal structure of the exhaust gas purifying catalyst is CuV ₂ O ₆ and contains a copper vanadium compound and a cesium sulfate at a specific ratio in a specific ratio, a plurality of different oxidation states can be taken. It is possible to improve the exhaust gas purification efficiency by effectively utilizing the excellent catalytic activity by mixing copper and vanadium.

(C) Since cesium sulfate is added to the exhaust gas purifying catalyst, the strength of the sintered body of the exhaust gas purifying catalyst formed by firing the mixture containing the copper vanadium compound is improved to improve the durability. Can be.

(D) Cesium sulfate can function as a catalyst for oxidizing or reducing sulfide components in exhaust gas, and in this case, the action of purifying exhaust gas can be further improved.

(E) Since the molar ratio of the copper vanadium compound and the cesium sulfate is limited to a specific range capable of synergistically exhibiting the catalytic activities of both, the solid carbon fine particles in the particulates are effectively removed. Can be burned.

(F) Since the main crystal structure is CuV ₂ O ₆ , the copper element and the vanadium element can be stably maintained in a specific range in which they function most efficiently as a combustion catalyst.

According to the second aspect of the present invention, the following effects can be obtained in addition to the effects of the first aspect.

(A) Since the gas permeable material is cordierite with a small change in thermal expansion and the conditions of the permeable structure are set, the pressure loss when the exhaust gas is supplied to the exhaust gas purifying material is suppressed, and the gas is efficiently used. The particulates in the exhaust gas are captured, and the catalyst supported on the gas flow path is acted on, so that the particulates can be efficiently burned.

(B) Since the coefficient of thermal expansion can be reduced by using cordierite, the difference in thermal expansion that occurs even when subjected to severe temperature fluctuations when used in a manifold of an automobile is used. It is possible to make the exhaust gas purifying material excellent in long-term durability by suppressing the occurrence of cracks, spalling and the like by making it small.

(C) The contact between the solid carbon fine particles in the particulates and the catalyst during purification is optimized, and the particulates can be purified without accumulating in the exhaust gas purifying material.

According to the third aspect of the present invention, the following effects can be obtained in addition to the effects of the first aspect.

(A) Since the main body of the wall-through type filter is made of aluminum titanate having a small coefficient of thermal expansion, and the coefficient of thermal expansion in a specific direction, the average pore diameter, and the porosity are set within predetermined ranges, An exhaust gas purifying material having excellent thermal shock resistance and gas permeability can be provided.

(B) The contact between the solid carbon fine particles in the particulates and the catalyst during purification is optimized, and the particulates are purified without accumulating in the exhaust gas purifying material. Heat resistance is improved, and it has the effect of preventing cracking and melting during particulate purification.

According to the fourth aspect of the present invention, the following effects can be obtained in addition to the effects of the first aspect.

(A) Since silicon carbide does not undergo creep deformation even when subjected to a high temperature for a long time, has high thermal conductivity and is resistant to temperature fluctuation, it prevents cracking and melting damage during particulate purification. To improve heat resistance.

(B) SiO formed by oxidizing silicon carbide
_The reaction of the exhaust gas purifying catalyst composed of the copper vanadium compound and cesium sulfate with the wall-through type silicon carbide filter body can be prevented by interposing the coating of ( ₂ ).

According to the fifth aspect of the present invention, the following effects can be obtained.

(A) By providing an exhaust gas purifying material and an exhaust gas purifying honeycomb body which are different from each other in the catalytic characteristics of the supported catalyst and the characteristics of the exhaust gas flow path independently and continuously, the exhaust gas purifying material on the upstream side is provided. The soot in the particulates in the exhaust gas is reliably captured and burned by the material, and the exhaust gas purification honeycomb body on the downstream side efficiently removes harmful components such as SOF, carbon monoxide, and hydrocarbons, which are the remaining particulates. be able to.

(B) Since the exhaust gas honeycomb body containing the noble metal is provided on the downstream side, the exhaust gas from which the noble metal and the particulates have been removed in advance is brought into contact with the noble metal, so that the activity of the noble metal catalyst can be effectively used and the noble metal can be used in the particulate form. The catalyst characteristics can be prevented from deteriorating due to contact with. Thereby, the required amount of the noble metal can be reduced, and the exhaust gas purifying apparatus can be manufactured at low cost.

(C) Since the exhaust gas purifying body containing the oxide of the transition metal and the honeycomb body for purifying the exhaust gas containing the noble metal are provided separately, the catalyst composition by the combination of the oxide of the transition metal and the noble metal is formed. Changes can be prevented, and the durability of each can be increased.

According to the sixth aspect of the present invention, the following effects can be obtained in addition to the effects of the fifth aspect.

(A) Since the exhaust gas purifying honeycomb body is made of cordierite or aluminum titanate having a small coefficient of thermal expansion, it has excellent fracture resistance to thermal shock and improves its durability. Can be.

(B) Since the noble metal catalyst is supported on alumina coated with silica / alumina, the affinity between the noble metal catalyst and the alumina particles can be improved, and the noble metal catalyst is prevented from peeling from the alumina particles. Thus, the durability can be further improved.

(C) By the action of silica / alumina, SO
Reaction with ₂ can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of an exhaust gas purifying material according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an exhaust gas purifying apparatus according to Embodiment 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas purifying material 2 Wall-through type filter 3 Sealing part 4 Exhaust gas purifying catalyst 5 Insulating material 6 Container 20 Exhaust gas purifying device 21 Exhaust gas purifying honeycomb body 22 Precious metal catalyst

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 27/224 B01J 35/04 301E 35/04 301 301P 35/10 301F 35/10 301 F01N 3/02 301B F01N 3/02 301 301E 3/10 A 3/10 3/24 N 3/24 E 3/28 301P 3/28 301 B01D 53/36 104B (72) Inventor Nobuyuki Tokubuchi 1006 Kadoma Odama, Kadoma City, Osaka Matsushita Inside Electric Industrial Co., Ltd. (72) Inventor Masahiro Inoue 1006 Odakadoma, Kadoma City, Osaka Pref. Matsushita Electric Industrial Co., Ltd. F-term (reference) BA05 BB06 BC07 CA01 CB04 4D048 AA14 AB01 BA03X BA06X BA07X BA10X BA14X BA23X BA30X BA31X BA33Y BA35X BA42X BA45X BA46X BB02 BB 12 BB14 CA01 CC04 CC34 CC46 CC63 CD05 EA07 4G069 AA03 AA08 BA01A BA01B BA03A BA03B BA13A BA13B BB02A BB02B BB06A BB06B BB10A BB10B BB15A BB15B BC06A BC06B BC16A BC16B BC31A BC31B BC50A BC50B BC54A BC54B BC71A BC72A BC72B BC75A BC75B BD05A BD05B CA07 CA18 EA19 EA25 EA27 EB10 EB12Y EB14Y EB15Y EC06X EC07X EC08X EC17X EC18X EC27 ED06 EE09 FA03 FA06 FB23 FC08

Claims (6)

[Claims] 1. A wall-through filter comprising a collection of ventilation cells separated by gas-permeable partitions, wherein one of the gas inlet side and the gas outlet side of each adjacent ventilation cell is alternately plugged, and is mainly used. Copper vanadium compound (c) having a crystal structure of CuV ₂ O ₆ and a molar ratio (a: b) of copper element (a) to vanadium element (b) of 1: 1.5 to 1: 3.5.
And the molar ratio (c: d) of cesium sulfate (d) is 1: 3
An exhaust gas purifying material formed by coating an inner wall surface of the ventilation cell with an exhaust gas purifying catalyst of 〜1: 3.5. 2. The gas permeable partition wall of the wall-through type filter is cordierite, and the total pore volume is 0.2.
cc / g or more, the volume of pores having a pore diameter of 10 μm or more is 40 to 60% of the total pore volume, and the average pore diameter is 8 to 20 μm.
The exhaust gas purifying material according to claim 1, wherein m and the porosity are 40 to 60%. 3. The gas permeable partition wall of the wall-through type filter is aluminum titanate obtained by extrusion molding, the average pore diameter is 8 to 42 μm, the porosity is 29 to 63 μm, and the coefficient of thermal expansion α in the extrusion direction is α. _{a is-}
^{2.3 × 10 -6 ℃ -1 ~0 ×} 10 -6 ℃ -1, extrusion direction perpendicular to the direction of the thermal expansion coefficient alpha _b is 0 × 10 ^{- 6} ℃ ^-1 ~2.4
The exhaust gas purifying material according to claim ¹ , wherein the temperature is × 10 ^-6 ° C ^-1 . 4. A gas permeable partition wall of the wall-through type filter is made of silicon carbide, and has an average pore diameter of 6 to 15 μm.
The exhaust gas purifying material according to claim 1, wherein m and the porosity are 42 to 53%. 5. The exhaust gas purifying material according to any one of claims 1 to 4, wherein the exhaust gas purifying material is disposed upstream of the exhaust gas flow, and the exhaust gas purifying honeycomb body supporting the noble metal is disposed downstream of the exhaust gas flow. An exhaust gas purifying device characterized by the above-mentioned. 6. An exhaust gas purifying honeycomb body comprising Pt, Pt,
Noble metal exhaust gas purifying catalyst comprising at least one of d and Rh supported on alumina coated with silica / alumina is coated on a cordierite or aluminum titanate honeycomb body. The exhaust gas purifying apparatus according to claim 5, wherein