JPH11123306A - Filter for cleaning gaseous emission and apparatus for cleaning gaseous emission in which the filter is used - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter and an apparatus for cleaning gaseous emission capable of cleaning an unburned hydrocarbon generated from fuel and engine oil contained in gaseous emission from an internal combustion engine, particularly a diesel engine, even in a low-temperature range and removing soot at the same time. SOLUTION: A decomposition catalyst 1 for decomposing an unburned hydrocarbon generated from fuel and engine oil in diesel particulates into a hydrocarbon having a smaller carbon number is provided on an inflow side of gaseous emission, and an oxidation catalyst 6 for oxidizing carbon monoxide, a hydrocarbon, and the hydrocarbon having smaller carbon number produced by the decomposition of the unburned hydrocarbon generated from the fuel and engine oil is provided on an outlet side of the gaseous emission.

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 filter for purifying exhaust gas of an internal combustion engine and an exhaust gas purifying apparatus using the same, and more particularly to oxidizing and burning particulates contained in exhaust gas of a diesel engine. The present invention relates to an exhaust gas purifying filter for purifying exhaust gas and an exhaust gas purifying apparatus using the same.

[0002]

2. Description of the Related Art It is desirable from the viewpoint of environmental protection to purify exhaust gas from an internal combustion engine so that the exhaust gas is safely released into the atmosphere. Exhaust gas purifying filters are generally made of a ceramic or metal heat-resistant honeycomb body, and an inorganic porous material for supporting a required amount of a catalytically active component, such as precious metal, base metal, or an oxide thereof, on the heat-resistant honeycomb body. A carrier (also referred to as a carrier layer) made of a porous material, and a catalytically active component such as a noble metal, a base metal, or an oxide thereof supported on the carrier. With respect to gasoline engines, toxic substances in exhaust gas have been steadily reduced due to strict regulations on exhaust gas and technological advances therefor, specifically, the emergence and further improvement of so-called three-way catalysts. However, due to the unique principle of diesel engines and the presence of harmful components called particulates, regulations are strictly set compared to gasoline engines. Because of the large delay, there is a demand for the development of an exhaust gas purifying filter that can surely purify particulates and an exhaust gas purifying device using the same.

[0003] Catalysts for purifying exhaust gas from diesel engines that have been developed to date have basically the same structure as three-way catalysts, and are intended for unburned hydrocarbons derived from fuel and engine oil. Open SOF (Soluble Organic Fract)
(ion; soluble organic component, hydrocarbon) cracking catalyst is known. An open-type SOF decomposition catalyst prepared by a known technique of impregnation is disclosed in, for example,
As disclosed in Japanese Patent Publication No. 26, metal fine particles such as platinum group metals, which are catalytically active components, are dispersed and supported on a carrier having a high specific surface area, similarly to a gasoline engine, and together with carbon monoxide and hydrocarbons. Unburned hydrocarbons derived from fuel and engine oil in the diesel particulates are oxidatively decomposed and purified. As a carrier having a high specific surface area, activated alumina or activated alumina to which an alkali metal or a rare earth is added is used in consideration of heat resistance and the like. This open-type SOF cracking catalyst has a drawback that the dry-suit removal rate is low, but the amount of dry-suit can be reduced by mechanical improvement of the diesel engine itself or improvement of the fuel itself, and the regeneration treatment Because there is a great merit that no device is required,
Further improvement of technology is expected in the future.

However, this open type SOF cracking catalyst also has insufficient activity in a low temperature range, and unburned hydrocarbons derived from fuel and engine oil are released to the atmosphere without purification. Therefore, Japanese Patent Application Laid-Open No. 4-26792
As disclosed in No. 8, a first catalyst that adsorbs unburned hydrocarbons derived from fuel and engine oil is disposed upstream of the exhaust gas, and a second catalyst that carries an oxidation catalyst is disposed downstream of the exhaust gas. In the low temperature range, unburned hydrocarbons derived from the fuel and the engine oil are adsorbed and trapped by the first catalyst, and when the exhaust gas temperature rises, the hydrocarbons are derived from the fuel and the engine oil trapped by the first catalyst. A method has been proposed in which unburned hydrocarbons are desorbed and oxidized with a second catalyst. However, also in this case, the first
There is a limit to the ability of the catalyst to trap unburned hydrocarbons derived from fuel and engine oil. For example, if the catalyst is left for a long time in an idling state, the adsorption power of the first catalyst is saturated, and the fuel and engine oil are saturated. Unburned hydrocarbons derived from the methane are discharged without being trapped.

[0005]

As described above, conventional exhaust gas purifying catalysts for unburned hydrocarbons derived from fuel and engine oil have insufficient catalytic activity in a low temperature range. However, there has been a problem that unburned hydrocarbons derived from fuel and engine oil cannot be sufficiently purified. Further, the catalysts disclosed in the above-mentioned publications and the like are intended only for unburned hydrocarbons derived from fuel and engine oil, and soot can hardly be purified.

The present invention provides an exhaust gas purifying filter which can purify unburned hydrocarbons derived from fuel and engine oil contained in exhaust gas from an internal combustion engine, particularly a diesel engine even in a low temperature range and can simultaneously remove soot. The purpose is to provide.

[0007]

An exhaust gas purifying filter according to the present invention is an exhaust gas purifying filter for purifying diesel particulates, which converts unburned hydrocarbons derived from fuel and engine oil in diesel particulates into carbon. A cracking catalyst that breaks down into small numbers of hydrocarbons is placed on the exhaust gas inflow side, and low carbon number hydrocarbons are generated by the decomposition of carbon monoxide, hydrocarbons and unburned hydrocarbons derived from fuel and engine oil. An oxidation catalyst for oxidizing the exhaust gas is disposed on the outflow side of the exhaust gas.

[0008] Using one honeycomb body carrying a catalyst,
A decomposition catalyst may be supported on the exhaust inflow side of the honeycomb body and an oxidation catalyst may be supported on the exhaust outflow side of the exhaust gas flow, or two or more filters may be used to support the exhaust gas flow. A honeycomb body carrying the decomposition catalyst may be arranged on the exhaust gas inflow side, and a honeycomb body carrying the oxidation catalyst may be arranged on the exhaust gas outflow side.

In this configuration, even in a low temperature range, unburned hydrocarbons derived from fuel and engine oil are decomposed into hydrocarbons having a small number of carbon atoms in the cracking catalyst on the exhaust inflow side, and carbon monoxide is decomposed in the oxidation catalyst on the exhaust outflow side. It is possible to provide an exhaust gas purification filter capable of oxidizing hydrocarbons having a small number of carbon atoms generated by decomposition of hydrocarbons and unburned hydrocarbons derived from fuel and engine oil.

Further, in the exhaust gas purifying filter having the above structure, an upstream side with respect to an exhaust gas flow of a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small carbon number, A configuration in which a soot-purifying catalyst is provided may be employed.

With this configuration, it is possible to provide an exhaust gas purifying filter capable of simultaneously purifying soot together with carbon monoxide, hydrocarbons and unburned hydrocarbons derived from fuel and engine oil in diesel exhaust gas. .

Among the catalysts used in the exhaust gas purifying filter of the present invention, the soot catalyst is a metal oxide and / or metal sulfate containing at least one member selected from the group consisting of Group 1a, 5a and 1b. Preferably, the composition formula of the metal oxide and / or the metal sulfate is Cs ₂ SO ₄ , CuVO ₃ ,
It is desirable to have at least one kind selected from Cu ₃ V ₂ O ₈ and Cu ₅ V ₂ O ₁₀ .

According to this structure, the metal oxide and / or metal sulfate of Group 1a directly acts on soot to perform oxidation,
A metal oxide and / or metal sulfate containing at least one member selected from the group consisting of group 5a and / or group 1b;
A soot catalyst capable of purifying soot contained in diesel particulates can be provided by playing a cocatalytic role of a group a metal oxide and / or metal sulfate.

In the exhaust gas purifying filter having the above structure, the cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small carbon number has a high specific surface area for supporting a catalyst component. The material is composed of alumina generated from pseudo-boehmite sol or a composite oxide composed of alumina generated from pseudo-boehmite sol and at least one selected from silica, zirconia, and titania.

[0015] With this configuration, the catalyst component can be supported on the carrier with a high specific surface area and high dispersion, and unburned hydrocarbons derived from fuel and engine oil can be appropriately applied to the solid acid sites existing on the carrier surface. Adsorption with a high adsorption force promotes the reaction between unburned hydrocarbons derived from fuel and engine oil and the catalyst component, thereby improving the decomposition reaction activity, and the fuel contained in diesel particulates. Further, it is possible to provide a cracking catalyst for cracking unburned hydrocarbons derived from engine oil into hydrocarbons having a small number of carbon atoms at a low temperature.

An oxidation catalyst for oxidizing hydrocarbons having a small number of carbons generated by decomposition of carbon monoxide, hydrocarbons, and unburned hydrocarbons derived from fuels and engine oils includes ceria and the like having oxygen storage capacity. And a carrier supported on the carrier, and at least one selected from the group of noble metals such as Pt and Pd as catalyst components.

According to this structure, the oxygen in the exhaust gas acts on the structural oxygen of the material by the material such as ceria having an oxygen storage capacity, thereby serving as an active oxygen supply source to promote the oxidation reaction. At least one selected from the group of noble metals such as Pd and Pd oxidizes carbon monoxide, hydrocarbons and hydrocarbons having a small number of carbons generated by decomposition of unburned hydrocarbons derived from fuel and engine oil. By doing so, it has the effect of promoting the oxidation reaction, carbon monoxide,
It is possible to provide a catalyst that oxidizes, at a low temperature, hydrocarbons having a small number of carbons generated by decomposition of hydrocarbons and unburned hydrocarbons derived from fuel and engine oil.

The exhaust gas purifying filter of the present invention has a structure having a honeycomb body and the exhaust gas purifying catalyst of the present invention carried on the honeycomb body. Among these, honeycomb bodies are ceramic carriers such as cordierite,
A known carrier having a large number of honeycomb-shaped passages, such as a metal carrier, can be used. The number of passages is 100
Desirably, it is about 400 cells / square inch.

[0019]

DETAILED DESCRIPTION OF THE INVENTION The present invention according to claim 1 is an exhaust gas purifying filter for purifying diesel particulates, wherein unburned hydrocarbons derived from fuel and engine oil in the diesel particulates are converted to a carbon number. A cracking catalyst that decomposes into small hydrocarbons is placed on the exhaust gas inflow side to oxidize hydrocarbons with low carbon numbers generated by the decomposition of carbon monoxide, hydrocarbons and unburned hydrocarbons derived from fuel and engine oil. The oxidation catalyst is disposed on the outflow side of the exhaust gas, without trapping unburned hydrocarbons derived from fuel and engine oil even in a low temperature range, to convert the hydrocarbons with a small number of carbon It has a function of completely oxidizing hydrocarbons having a small number of carbons which have been decomposed and easily oxidized to CO ₂ .

The invention according to claim 2 is an exhaust gas purifying filter for purifying diesel particulates, which purifies soot in diesel particulates.
A soot catalyst comprising a metal oxide and / or a metal sulfate containing at least one selected from the group a and the group 5a and / or the group 1b is disposed on the exhaust gas inflow side, and is derived from fuel and engine oil. A cracking catalyst that decomposes unburned hydrocarbons into small hydrocarbons, which is located downstream of the soot catalyst, and further decomposes unburned hydrocarbons derived from carbon monoxide, hydrocarbons and fuel and engine oil. Oxidation catalyst for oxidizing small hydrocarbons produced by the decomposition of small hydrocarbons generated by carbon is characterized by being disposed downstream of the decomposition catalyst, carbon monoxide in a low temperature range, In addition to purifying hydrocarbons with low carbon numbers produced by decomposing hydrocarbons and unburned hydrocarbons derived from fuel and engine oil, soot can be purified at the same time. It has the effect that.

The invention according to claim 3 is characterized in that the group 1a and the group 5a
At least one member selected from the group consisting of
A metal oxide and / or metal sulfate containing
The composition formula of the catalyst is Cs_TwoSO_FourAnd CuVO_Three, Cu_ThreeV
_TwoO₈And Cu_FiveV_TwoO_TenAt least one selected from the group of
Cs_TwoSO_FourBut
Acts as a main component to purify soot, CuVO_Three, Cu_Three
V_TwoO₈And Cu_FiveV_TwoO _TenAt least one kind selected from
The top is Cs_TwoSO_FourIs to act as a co-catalyst for soot
It has the function of purifying.

According to a fourth aspect of the present invention, the carrier of the cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small carbon number is alumina formed from pseudo-boehmite gel. It is characterized by having a large area for supporting the catalyst component and having heat resistance, and also when decomposing unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms. In addition, unburned hydrocarbons derived from fuel and engine oil have an action of adsorbing, with an appropriate adsorption force, on solid acid sites present on alumina generated from pseudo-boehmite sol.

According to a fifth aspect of the present invention, the alumina produced from the pseudo-boehmite gel is pseudo-γ-alumina, and the diffraction pattern of the (440) plane obtained by the X-ray diffraction method is 2θ.
It is characterized by a pattern forming a double line at around = 60 °, and has an effect of having a crystal structure different from that of known γ-alumina, and having a high specific surface area and high heat resistance.

According to a sixth aspect of the present invention, a carrier for a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms comprises alumina produced from pseudo-boehmite sol, silica, A complex oxide comprising at least one selected from the group consisting of zirconia and titania, capable of controlling the solid acid on the carrier, and thus being derived from fuel and engine oil. This has the effect that the state of adsorption of unburned hydrocarbons on the carrier can be arbitrarily controlled.

[0025] The invention according to claim 7, the solid acid strength of unburned hydrocarbons carriers of small hydrocarbons decompose decomposition catalyst carbon number derived from the fuel and engine oil, in acidity function H ₀ -5 0.6 ≧ H ₀ > −12, whereby unburned hydrocarbons derived from fuel and engine oil can be adsorbed on solid acid sites with an appropriate adsorption force. Having.

Here, the definition of the acidity function H ₀ indicates the tendency of a solution to transfer a proton to a neutral base. For example, when the electrically neutral base is B, the following equilibrium relationship is established.

B + H ⁺ ⇔BH ⁺ At this time, the acidity function H ₀ is expressed by the following equation.

[0028] ^{_{H 0 = (pKa) BH +}} + log 10 (CB / CBH +) = -log 10 (αH + · fB / fBH +) p, Ka, α, f the invention according to the constant claim 8, Alumina generated from pseudo-boehmite sol, which is a carrier for a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms, and at least one selected from the group consisting of silica, zirconia, and titania Wherein the ratio of at least one of Si, Zr, and Ti to Al of the composite oxide comprising at least one species is 20 to 33 mol%, and alumina produced from pseudo-boehmite sol; , Zirconia, and titania have an action of controlling a solid acid that is expressed when forming a composite oxide. .

According to a ninth aspect of the present invention, the active components carried on a carrier of a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small carbon number are Pd and Rh, The total carrying amount of Pd and Rh is 5 wt%, and the ratio of Rh to Pd is 6 to
Pd decomposes unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms, and Rh plays the role of a promoter to decompose Pd. Has the effect of improving If the supported amount is less than 5 wt%, the activity will be lower than 5 wt%, and if it exceeds 5 wt%, there will be no change in activity, and more than 5 wt% will be useless. On the other hand, when the ratio of Rh to Pd is out of the range of 6 to 15 wt%, the decomposition activity is reduced.

[0030] The tenth aspect of the present invention relates to Pd and Rh.
The pH of the aqueous solution of Pd salt and Rh salt when carrying
２．０2.0.
The solubility of d salt and Rh salt is improved, and it has an effect of being able to be supported on a carrier in a state closer to atoms.

The invention according to claim 11 is characterized in that carbon monoxide,
An oxidation catalyst for oxidizing hydrocarbons and low-carbon hydrocarbons generated by decomposing unburned hydrocarbons derived from fuels and engine oils is used as a carrier coated with a material such as ceria having an oxygen storage capacity, and a carrier. And at least one selected from the group of noble metals such as Pt and Pd, which are catalyst components supported on the substrate, and a material such as ceria having oxygen storage capacity. By the action of oxygen in the exhaust gas and lattice oxygen of a material such as ceria having oxygen storage capacity, it becomes a source of active oxygen, and at least one or more selected from the group of noble metals such as Pt and Pd Combined with the oxidizing power of carbon monoxide, hydrocarbons, and unburned hydrocarbons derived from fuels and engine oil Cormorant having an effect.

According to a twelfth aspect of the present invention, there is provided an exhaust gas purifying apparatus, wherein the exhaust gas purifying filter is held in a heat insulating container.
Since the catalyst filter is held in the heat insulating container, it is possible to prevent external cooling when the catalyst filter is heated by the exhaust gas, and thus has an effect of preventing heat shock.

According to a thirteenth aspect of the present invention, the heat-insulating container is disposed immediately below the engine manifold. Since the heat-insulating container is mounted immediately below the engine manifold, the temperature of the catalyst can be reduced even if it is small. Considering that the higher the situation, the higher the activity, it has the effect of being catalytically advantageous.

Hereinafter, a specific example of the embodiment of the present invention will be described. (Embodiment 1) FIG. 1 is a cross-sectional view of an exhaust gas purifying filter according to a first embodiment of the present invention, and arrows in the drawing indicate the directions of inflow and outflow of exhaust gas. The exhaust gas first passes through a cracking catalyst 1 arranged on the exhaust inflow side in FIG. Here, in the cracking catalyst 1, the composite oxide 3 formed by compounding alumina supported on the surface of the honeycomb body 2 and at least one selected from silica, zirconia, and titania is formed on the honeycomb body 2. Providing a high specific surface area, the catalytically active components Pd4 and Rh5 supported on the upper surface of the composite oxide 3 convert unburned hydrocarbons derived from fuel and engine oil in exhaust gas into hydrocarbons having a small number of carbon atoms. Decompose. Next, the exhaust gas passes through the oxidation catalyst 6 arranged on the exhaust outlet side in FIG. The inorganic oxide 8 having a high specific surface area and coated with a material having an oxygen storage ability supported on the surface of the honeycomb
To provide a high specific surface area, at least one or more of the noble metals such as Pd, Pt, Rh, and Ir, which are the catalytically active components supported on the upper surface of the support, include carbon monoxide, hydrocarbons and Unburned hydrocarbons derived from fuel and engine oil decompose and oxidize hydrocarbons with low carbon numbers. In FIG. 1, reference numeral 9 denotes Pt, and it may be replaced by at least one of noble metals such as Pd, Rh, and Ir.

(Embodiment 2) FIG. 2 is a sectional view of an exhaust gas purifying filter according to a second embodiment of the present invention. The exhaust gas first passes through a soot catalyst 10 arranged on the exhaust inflow side in FIG. Here, the soot catalyst 10 includes Cs ₂ SO ₄ supported on the surface of the honeycomb body 11 and CuV
_{O 3, Cu 3 V 2 O} 8, soot in the diesel particulate by configured Cu ₅ V ₂ O ₁₀ 12 at least one selected from Cu ₅ V ₂ O ₁₀ is purified. Next, the exhaust gas passes through a decomposition catalyst 13 disposed downstream of the soot catalyst 10 disposed on the exhaust inflow side. Here, in the cracking catalyst 13, a composite oxide 15 formed by complexing alumina supported on the surface of the honeycomb body 14 and at least one or more selected from silica, zirconia, and titania,
The honeycomb body 14 has a high specific surface area, and the composite oxide 15
Of the catalytically active components Pd16 and Rh supported on the upper surface of
Reference numeral 17 decomposes unburned hydrocarbons derived from fuel and engine oil in the exhaust gas into hydrocarbons having a small number of carbon atoms. Next, the exhaust gas passes through an oxidation catalyst 18 arranged downstream of the decomposition catalyst 13 arranged on the exhaust outlet side in FIG. The high specific surface area inorganic oxide 20 coated on the surface of the honeycomb body 19 and coated with a material having an oxygen storage capacity provides the honeycomb body 19 with a high specific surface area and the material having an oxygen storage capacity is coated. Pt 21 (alternatively, at least one of noble metals such as Pd, Rh, and Ir) supported on the upper surface of the high specific surface area inorganic oxide 20 may be contained in the exhaust gas. The unburned hydrocarbons derived from carbon monoxide, hydrocarbons and fuels and engine oils oxidize the low carbon number hydrocarbons produced by decomposition.

(Embodiment 3) FIG. 3 is a sectional view of an exhaust gas purifying apparatus according to a third embodiment of the present invention. In FIG. 3, the composite oxide 24 supported on the surface of the honeycomb body 23 provides the honeycomb body 23 with a high specific surface area, and the catalytically active component supported on the upper surface of the composite oxide 24 reduces the monoxide in the exhaust gas. Unburned hydrocarbons derived from carbon, hydrocarbons and fuels and engine oils oxidize the hydrocarbons produced by decomposition. The heat insulating material 31 around the exhaust gas purification filter is made of hollow stainless steel or the like, and thermally shields the filter from the outside. Other configurations are the same as those described in the first embodiment, and the decomposition catalyst 22, Pd2
5, Rh 26, an oxidation catalyst 27, a honeycomb body 28, an inorganic oxide 29, and Pt30.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0038]

【Example】

(Decomposition Catalyst A1) First, alumina powder and silica sol produced from pseudo-boehmite sol were mixed and stirred for 24 hours, dried at 120 ° C. for 12 hours, and calcined at 800 ° C. for 5 hours to prepare a composite oxide. I do. After crushing this composite oxide, it is mixed with pure water to prepare a slurry.

Next, a cordierite honeycomb body having a diameter of 5.66 inches, a length of 6 inches, and a cell number of 300 cells / square inch was prepared, immersed in the slurry, pulled up, and then the excess slurry was removed by air blowing. After the removal, the coating was dried at 120 ° C. for 5 hours, and further baked at 800 ° C. for 5 hours to coat the composite oxide on the honeycomb body. The attached amount of the composite oxide was about 350 g per honeycomb body.

Next, an aqueous Pd nitrate solution adjusted to pH = 1.7 was prepared, and the honeycomb body coated with the composite oxide was immersed in the aqueous solution, followed by drying at 120 ° C. for 30 minutes. This operation was repeated several times. A predetermined amount of Pd is loaded, and under a reducing atmosphere
It was baked at 00 ° C. for 5 hours. Further, an aqueous solution of Rh nitrate adjusted to pH = 1.7 was prepared, and a honeycomb body coated with the composite oxide supporting Pd was immersed in the aqueous solution.
The operation of drying at 30 ° C. for 30 minutes is repeated several times to obtain a predetermined amount of R.
h was carried and fired at 600 ° C. for 5 hours in a reducing atmosphere, and then fired at 800 ° C. in air for 5 hours.

(Decomposition Catalyst A2) A composite oxide was prepared using alumina powder produced from pseudo-boehmite sol, titania sol and pure water. Next, it is the same as the first catalyst A1 except that a slurry was prepared using this composite oxide, and the honeycomb body was immersed in the slurry.

(Decomposition Catalyst A3) A composite oxide was prepared using alumina powder generated from pseudo boehmite sol, zirconia sol and pure water. Next, it is the same as the first catalyst A1 except that a slurry was prepared using this composite oxide, and the honeycomb body was immersed in the slurry.

(Oxidation catalyst B1) First, alumina powder produced from pseudo-boehmite sol, Ce nitrate and pure water were stirred and mixed for 24 hours, dried at 120 ° C. for 12 hours, and further dried at 80 ° C.
The composite oxide is prepared by firing at 0 ° C. for 5 hours. After crushing this composite oxide, it is mixed with pure water to prepare a slurry.
At this time, the powder concentration in the slurry was about 10% by weight.

Next, a cordierite honeycomb body having a diameter of 5.66 inches, a length of 6 inches, and a cell number of 300 cells / square inch was prepared, immersed in the slurry, pulled up, and then the excess slurry was removed by air blowing. After the removal, drying was performed at 120 ° C. for 5 hours, and further calcination was performed at 800 ° C. for 5 hours, so that the honeycomb body was coated with alumina generated from pseudo-boehmite sol. The attached amount of alumina generated from the pseudo boehmite sol was about 350 g per honeycomb body.

Next, an aqueous solution of Pd nitrate adjusted to pH = 1.7 was prepared, and a honeycomb body coated with alumina generated from pseudo-boehmite sol was immersed in the aqueous solution, followed by drying at 120 ° C. for 30 minutes. This was repeated several times to carry a predetermined amount of Pd, and baked at 600 ° C. for 5 hours in a reducing atmosphere. Further, an aqueous solution of dinitrodiamino Pt crystals adjusted to pH = 1.7 is prepared, and a honeycomb body coated with alumina generated from the pseudo-boehmite sol supporting Pd is immersed in the aqueous solution, and dried at 120 ° C. for 30 minutes. Is carried out several times to carry a predetermined amount of Pt,
For 5 hours. Finally, it was further fired in air at 800 ° C. for 5 hours.

(Oxidation Catalyst B2) First, a slurry is prepared by wet mixing zirconia powder and pure water all day and night.
At this time, the powder concentration in the slurry was about 10% by weight. Next, it is the same as the second catalyst B1 except that the honeycomb body was immersed in this slurry.

(Oxidation catalyst B3) First, titania powder and pure water are wet-mixed for 24 hours to prepare a slurry. At this time, the powder concentration in the slurry was about 10% by weight. Next, it is the same as the second catalyst B1 except that the honeycomb body was immersed in this slurry.

(Soot Catalyst C1) First, copper nitrate and ammonium vanadate are weighed to a molar ratio of 1: 1 and dissolved in pure water and stirred to prepare a solution for impregnation.

Next, a cordierite honeycomb body having a diameter of 5.66 inches, a length of 6 inches and a cell number of 300 cells / square inch was prepared, immersed in the aqueous solution, and an excess aqueous solution was removed by air blowing. Thereafter, it was dried and calcined at 900 ° C. for 5 hours in the air to support the composite oxide of copper and vanadium on the honeycomb body.

Next, cesium sulfate is weighed to a molar ratio of 2: 1 with respect to the composite oxide of copper and vanadium, dissolved in pure water, and stirred.

A honeycomb body supporting a composite oxide of copper and vanadium is immersed in this solution, excess aqueous solution is removed by air blow, dried, and dried in air at 900 ° C. for 5 hours.
After firing for an hour, an exhaust gas purification filter was obtained.

(Soot catalyst C2) First, except that copper nitrate and ammonium vanadate were weighed at a molar ratio of 3: 2, dissolved in pure water and stirred to prepare a solution for impregnation. Is the same as that of the third catalyst C1.

(Soot Catalyst C3) First, except that copper nitrate and ammonium vanadate were weighed at a molar ratio of 5: 2, dissolved in pure water and stirred to prepare a solution for impregnation. Is the same as that of the third catalyst C1.

(Comparative Example D1) First, alumina powder, silica sol and pure water were stirred and mixed for 24 hours, dried at 120 ° C. for 12 hours, and calcined at 800 ° C. for 5 hours to prepare a composite oxide. After crushing this composite oxide, it is mixed with pure water to prepare a slurry.

Next, a cordierite honeycomb body having a diameter of 5.66 inches, a length of 6 inches, and a cell number of 300 cells / square inch was prepared, immersed in the slurry, pulled up, and then the excess slurry was removed by air blowing. After the removal, the coating was dried at 120 ° C. for 5 hours, and further baked at 800 ° C. for 5 hours to coat the composite oxide on the honeycomb body. The attached amount of the composite oxide was about 350 g per honeycomb body.

Next, an operation of preparing an aqueous solution of Pd nitrate adjusted to pH = 1.7, immersing the honeycomb body coated with the composite oxide in the aqueous solution, and drying at 120 ° C. for 30 minutes was repeated several times. A predetermined amount of Pd is loaded, and under a reducing atmosphere
It was baked at 00 ° C. for 5 hours. Further, an aqueous solution of Rh nitrate adjusted to pH = 1.7 was prepared, and a honeycomb body coated with the composite oxide supporting Pd was immersed in the aqueous solution.
The operation of drying at 30 ° C. for 30 minutes is repeated several times to obtain a predetermined amount of R.
h was carried and fired at 600 ° C. for 5 hours in a reducing atmosphere, and then fired at 800 ° C. in air for 5 hours.

(Comparative Example D1) First, a slurry is prepared by mixing alumina powder generated from pseudo-boehmite sol with pure water. The powder concentration in the slurry at this time was about 1
It was 0 wt%.

Next, a cordierite honeycomb body having a diameter of 5.66 inches, a length of 6 inches and a cell number of 300 cells / square inch was prepared, immersed in the slurry, pulled up, and then the excess slurry was removed by air blowing. After the removal, drying was performed at 120 ° C. for 5 hours, and further calcination was performed at 800 ° C. for 5 hours, so that the honeycomb body was coated with alumina generated from pseudo-boehmite sol. The attached amount of alumina generated from the pseudo boehmite sol was about 350 g per honeycomb body.

Next, an aqueous solution of Pd nitrate adjusted to pH = 1.7 was prepared, and a honeycomb body coated with alumina generated from pseudo-boehmite sol was immersed in the aqueous solution, followed by drying at 120 ° C. for 30 minutes. This was repeated several times to carry a predetermined amount of Pd, and baked at 600 ° C. for 5 hours in a reducing atmosphere. Further, an aqueous solution of dinitrodiamino Pt crystals adjusted to pH = 1.7 is prepared, and a honeycomb body coated with alumina generated from the pseudo-boehmite sol supporting Pd is immersed in the aqueous solution, and dried at 120 ° C. for 30 minutes. Is carried out several times to carry a predetermined amount of Pt,
For 5 hours. Finally, it was further fired in air at 800 ° C. for 5 hours.

Next, a description will be given of a catalyst activity evaluation test performed on the exhaust gas purifying catalyst in the above embodiment.
The catalyst filter was cut into a predetermined size so that the catalyst filter prepared in the above example could be evaluated in the reaction system.
FIG. 4 is a schematic diagram of a fixed bed flow system reaction apparatus used for a catalyst activity evaluation test.

In FIG. 4, nitrogen gas 32 and dry air 3
3, the unburned hydrocarbon 34 derived from the fuel and the engine oil is adjusted to a predetermined flow rate by each of the liquid flow rate regulators 37 by the gas flow rate regulators 35 and 36, and then the fuel and the engine in the carburetor 38. Unburned hydrocarbons 34 derived from oil are vaporized at a predetermined concentration and mixed with nitrogen gas 32 and air. This mixed gas is introduced into the quartz glass tube 39 and is purified by an exhaust gas purifying filter 40 placed in the quartz glass tube 39. In addition, quartz wool 41 is disposed before and after the exhaust gas purification filter 40, and the quartz glass tube 39 is installed in an electric furnace 42. A part of the purified mixed gas is introduced into an NDIR-type carbon monoxide / carbon dioxide gas analyzer 43 to detect the concentration of carbon monoxide and carbon dioxide, and then introduced into an oxygen sensor 44 to detect the concentration of oxygen. Is measured. The catalyst activity evaluation test was carried out as follows: the oxygen partial pressure of the mixed gas was 12%, the space velocity was 30000 / h, the concentration of unburned hydrocarbons derived from fuel and engine oil was 300
The change over time in the catalytic activity was measured under the conditions of ppm and an electric furnace temperature of 200 ° C. From the carbon monoxide concentration and carbon dioxide concentration measured by the above method, the combustion rate was calculated by the following equation.

Unburned hydrocarbon purification rate = (PCO + PCO ₂ ) / PC In the above equation, PCO is a value of a carbon monoxide concentration measured by an NDIR-type carbon monoxide / carbon dioxide gas analyzer 43, and PCO ₂ is The value of the carbon dioxide concentration measured by the analyzer 43, and PC is the theoretical concentration of CO or CO ₂ when 100% of unburned hydrocarbons derived from fuel and engine oil have burned.

Further, a different part of the purified mixed gas is introduced into a gas chromatograph through a gas sampling device, and each component of unreacted fuel and unburned hydrocarbon derived from engine oil is quantified. The reaction rate is determined in advance in a state where no exhaust gas purification filter is provided, and beforehand, each component of unburned hydrocarbons derived from fuel and engine oil is determined, and the value at this time is defined as 100% and is included in the purified mixed gas. The residual ratio of unburned hydrocarbons derived from unreacted fuel and engine oil was calculated.

Regarding the evaluation of the soot catalyst, soot cannot be supplied simultaneously with the gas into the circulation system. Therefore, the cut out catalyst filter is impregnated with a solution in which soot is suspended, and soot is attached to the catalyst filter. The purification rate was calculated from the weight before and after the reaction.

Table 1 shows the results of the purification rates of the catalyst activity evaluation tests on the exhaust gas purification filters in the examples and comparative examples. The evaluation test was performed for 24 hours regardless of whether the soot catalyst was placed in the reaction system.

[0066]

[Table 1]

First, when looking at a system in which a soot catalyst is not provided in the reaction system, the purification rate in the low temperature range immediately after the start of the reaction and after 24 hours has passed is clearly higher than that of the comparative example. It is clear that the catalyst is superior. Looking at the low purification rate of the comparative example, in the low temperature range, unburned hydrocarbons derived from fuel and engine oil are adsorbed to the adsorbent upstream of the exhaust gas flow of the purification catalyst,
It is clear that the catalyst cannot be purified unless it is purified when the reaction temperature rises and desorbs, and it is clear how excellent the present catalyst is.

In the system in which the soot catalyst was arranged in the reaction system, the system without the soot catalyst shown in the comparative example hardly purified soot. About half of soot
The purification was performed at 0 ° C., which clearly indicates that the purification was excellent.

As described above, it is clear how the catalyst purification filter of the present invention and the purification device using the same are superior to the conventional catalyst purification filter and the purification device using the same.

[0070]

As described above, according to the exhaust gas purifying filter of the present invention and the exhaust gas purifying apparatus using the same,
Conventionally, carbon which is not easily oxidized even in a low temperature range where unburned hydrocarbons derived from fuel and engine oil must be adsorbed is decomposed into unburned hydrocarbons derived from fuel and engine oil, thereby making carbon more easily oxidized. It can be converted to lower number hydrocarbons, which can be further oxidized with an oxidation catalyst. Therefore, even if a low load state such as idling continues for a long time, the exhaust gas is always exhausted as purified exhaust gas. In addition, soot can be purified at the same time by combining it with a soot catalyst.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an exhaust gas purification filter according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of an exhaust gas purification filter according to a second embodiment of the present invention.

FIG. 3 is a sectional view of an exhaust gas purifying apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram of a fixed-bed flow reactor used in a catalyst activity evaluation test.

[Explanation of symbols]

Reference Signs List 1 decomposition catalyst 2 honeycomb body 3 composite oxide 4 Pd 5 Rh 6 oxidation catalyst 7 honeycomb body 8 inorganic oxide 9 Pt 10 soot catalyst 11 honeycomb body 12 Cu ₅ V ₂ O ₁₀ 13 decomposition catalyst 14 honeycomb body 15 composite oxide 16 Pd 17 Rh 18 Oxidation catalyst 19 Honeycomb body 20 Inorganic oxide 21 Pt 22 Decomposition catalyst 23 Honeycomb body 24 Composite oxide 25 Pd 26 Rh 27 Oxidation catalyst 28 Honeycomb body 29 Inorganic oxide 30 Pt 31 Thermal insulator 32 Nitrogen gas 33 Air 34 Unburned hydrocarbons 35 Gas flow regulator 36 Gas flow regulator 37 Liquid flow regulator 38 Vaporizer 39 Quartz glass tube 40 Exhaust gas purification filter 41 Quartz wool 42 Electric furnace 43 Carbon monoxide / carbon dioxide gas analyzer 44 Oxygen sensor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyuki Tokubuchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (13)

[Claims] An exhaust gas purifying filter for purifying diesel particulates, comprising: a decomposition catalyst for decomposing unburned hydrocarbons derived from fuel and engine oil in the diesel particulates into hydrocarbons having a small carbon number. An oxidation catalyst, which is located on the inflow side of the exhaust gas and oxidizes hydrocarbons with low carbon number generated by the decomposition of carbon monoxide, hydrocarbons and unburned hydrocarbons derived from fuel and engine oil, is located on the exhaust gas outflow side An exhaust gas purification filter characterized by the following. 2. An exhaust gas purifying filter for purifying diesel particulates, wherein the metal contains at least one member selected from the group consisting of Group 1a, 5a and / or 1b for purifying soot in diesel particulates. A soot catalyst made of an oxide and / or a metal sulfate is disposed on the inflow side of the exhaust gas, and is located downstream of the soot catalyst that decomposes unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms. And an oxidation catalyst, which oxidizes hydrocarbons with low carbon numbers generated by decomposing carbon monoxide, hydrocarbons and unburned hydrocarbons derived from fuel and engine oil, is disposed downstream of the decomposition catalyst. An exhaust gas purification filter characterized by the above-mentioned. 3. A metal oxide containing at least one member selected from the group consisting of Group 1a, Group 5a and / or Group 1b, and / or
Alternatively, the composition formula of the soot catalyst comprising a metal sulfate is Cs ₂
And SO _4, the exhaust gas purifying filter according to claim 2, characterized in that CuVO _3, is Cu ₃ V ₂ O ₈ and Cu ₅ V ₂ O ₁₀ of at least one or more selected from the group consisting of. 4. The carrier of a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms is alumina produced from pseudo-boehmite gel. 3. The exhaust gas purification filter according to 2. 5. The alumina produced from the pseudo-boehmite gel is pseudo-γ-alumina, and its alumina is determined by X-ray diffraction.
The exhaust gas purification filter according to claim 4, wherein the diffraction pattern of the (40) plane is a pattern forming a double line at around 2θ = 60 °. 6. A carrier for a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms is selected from the group consisting of alumina produced from pseudo-boehmite sol and silica, zirconia and titania. 3. The exhaust gas purifying filter according to claim 1, wherein the exhaust gas purifying filter is a composite oxide comprising at least one selected from the group consisting of: 7. The fuel and solid acid strength of carriers of unburned hydrocarbons decomposing decomposition catalyst into smaller hydrocarbon carbon number derived from the engine oil, with acidity function H ₀ -5.6 ≧ H ₀
3. The exhaust gas purifying filter according to claim 1, wherein the ratio is> -12. 4. 8. A catalyst comprising a carrier of a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms, alumina produced from pseudo-boehmite sol, and silica, zirconia and titania. The ratio of at least one or more of Si, Zr, and Ti to Al of the selected composite oxide of at least one or more is 2
The exhaust gas purification filter according to claim 1, wherein the content is 0 to 33 mol%. 9. An active component supported on a carrier of a cracking catalyst for cracking unburned hydrocarbons derived from fuel and engine oil into hydrocarbons having a small number of carbon atoms is Pd and Rh;
The total carrying amount of Pd and Rh is 5 wt%, and P
3. The exhaust gas purification filter according to claim 1, wherein the ratio of Rh to d is 6 to 15 wt%. 10. The exhaust gas purifying filter according to claim 9, wherein the pH of the aqueous solution of the Pd salt and the Rh salt when carrying Pd and Rh is in the range of 1.0 to 2.0. 11. An oxidation catalyst for decomposing carbon monoxide, hydrocarbons, and unburned hydrocarbons derived from fuel and engine oil and oxidizing hydrocarbons having a small number of carbons, such as ceria or the like having oxygen storage capacity. A support coated with the material, and a catalyst component Pt further supported on the support,
3. The semiconductor device according to claim 1, wherein the material is at least one selected from the group of noble metals such as Pd.
An exhaust gas purification filter as described in the above. 12. An exhaust gas purifying apparatus characterized in that the exhaust gas purifying filter according to claim 1 or 2 is held in a heat insulating container. 13. The exhaust gas purifying apparatus according to claim 12, wherein the heat insulating container is disposed immediately below the engine manifold.