JP2825420B2 - Diesel engine exhaust gas purification catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for purifying exhaust gas of a diesel engine. To elaborate,
A catalyst for purifying diesel engine exhaust gas that can burn and remove harmful components such as carbon-based particulates, unburned hydrocarbons, and carbon monoxide in diesel engine exhaust gas from low temperatures and suppress the production of sulfate from sulfur dioxide. It is about.

[0002]

2. Description of the Related Art In recent years, in particular, particulate matter in diesel engine exhaust gas (mainly solid carbon fine particles, sulfur-based fine particles such as sulfates, liquid or solid high-molecular hydrocarbon fine particles, etc.) These are collectively referred to as “particulate matter”), which poses a problem in environmental health. The reason is that these fine particles are easily suspended in the air because their particle system is almost 1 μm or less.
This is because they are easily taken into the human body by breathing. Therefore, studies are under way to tighten regulations on the emission of these particulate matter from diesel engines.

[0003] On the other hand, the amount of particulate matter discharged from the diesel engine has been reduced to some extent with the improvement of the pressure of the fuel injection of the diesel engine and the control of the fuel injection timing. However, the reduction has not been sufficient yet, and a component (SOF) soluble in an organic solvent mainly composed of a liquid high molecular weight hydrocarbon, which is contained in the particulate matter, has been improved by the engine improvement as described above. Cannot be removed, and the SOF ratio in the particulate matter increases. Since this SOF contains harmful components such as carcinogenic substances, the SOF together with the particulate matter
Removal is an important issue.

[0004] As a method for removing particulate matter, carbon-based particulates are added to a refractory three-dimensional structure such as ceramic foam, wire mesh, metal foam, plugged ceramic honeycomb, open flow type ceramic honeycomb, metal honeycomb and the like. Using a catalyst carrying a combustible catalytic substance, capturing particulate matter in diesel engine exhaust gas and under exhaust gas emission conditions (gas composition and temperature) obtained under normal diesel engine running conditions, or A catalytic method for removing carbon-based particles using a heating means such as an electric heater has been studied.

[0005] In general, as a catalyst for purifying exhaust gas of a diesel engine, (a) a fuel having a high efficiency in removing harmful components such as unburned hydrocarbons and carbon monoxide from a low temperature in addition to carbon-based fine particles, and (b) a fuel. Sulfur dioxide (SO ₂ ) generated from a large amount of sulfur components in light oil used has low oxidizing ability to sulfur trioxide (SO ₃ ), and sulfate (sulfur dioxide is oxidized to sulfur trioxide or sulfur mist). ) Can be suppressed. Further, (c) a catalyst having a performance that can endure even under continuous tumbling under a high load, that is, has high so-called high-temperature durability is desired.

For example, JP-A-61-129030, JP-A-61-149222 and JP-A-61-146314 disclose palladium and rhodium as main active components.
Further, a catalyst composition to which an alkali metal, an alkaline earth metal, copper, lanthanum, zinc, manganese or the like is added, and JP-A-59-82944 discloses at least one catalyst selected from copper, alkali metal, molybdenum and vanadium. A catalyst composition combining a species with at least one selected from platinum, rhodium and baradium is disclosed.

Further, S in the exhaust gas of a diesel engine
As a catalyst for removing OF, an open honeycomb-shaped noble metal-based oxidation catalyst having a through hole parallel to a gas flow has been reported (SAE Paper, 81026).
3).

[0008]

However, all of the above-mentioned conventional catalysts remove carbon-based fine particles by combustion or remove sulfur.
Although the removal of OF is somewhat effective, the catalyst system containing a platinum group metal has a high oxidizing ability of sulfur dioxide under exhaust gas conditions at high temperatures, so that the amount of sulfate generated increases, and this sulfate is newly used. There is a drawback of causing a serious environmental problem.

That is, the performance required for the catalyst for purifying exhaust gas of a diesel engine described in (a) to (c) above,
Further, a catalyst having sufficient SOF removal performance has not been found yet.

Accordingly, it is an object of the present invention to provide a diesel engine exhaust gas purifying catalyst which can efficiently remove particulate matter in diesel engine exhaust gas.

Another object of the present invention is to have the capability of burning and removing harmful components such as unburned hydrocarbons and carbon monoxide in addition to carbon-based fine particles in diesel engine exhaust gas from a low temperature, and furthermore, have the ability to oxidize sulfur dioxide. An object of the present invention is to provide a catalyst for purifying a diesel engine, which has a low sulfur content and suppresses the production of sulfate.

Another object of the present invention is to provide a diesel engine exhaust gas purifying catalyst which can efficiently remove SOF in diesel engine exhaust gas.

Another object of the present invention is to provide a catalyst for purifying a diesel engine which has good durability at high temperatures and can be mounted on a diesel vehicle without causing practical problems.

[0014]

The above objects are attained from the group consisting of (A) a first catalyst component containing both iron and manganese elements and a refractory inorganic oxide and (B) palladium, platinum and rhodium. A catalyst for purifying exhaust gas of a diesel engine, wherein a second catalyst component containing at least one selected noble metal and a refractory inorganic oxide is supported in a single layer on a refractory three-dimensional structure. Is achieved by

The above objects are achieved by (A) a second catalyst component containing both iron and manganese elements, a refractory inorganic oxide and an alkaline earth element and / or a rare earth element, and (B) palladium, platinum and rhodium. Diesel engine exhaust gas characterized in that at least one noble metal selected from the group consisting of and a third catalyst component containing a refractory inorganic oxide is supported on a refractory three-dimensional structure in a single layer. This is achieved by the purifying catalyst described above.

The above objects are at least one kind selected from the group consisting of (A) a first catalyst component containing both iron and manganese elements and a refractory inorganic oxide, and (B) palladium, platinum and rhodium. A third catalyst component containing a noble metal, a copper element and a refractory inorganic oxide is supported in a single layer on a refractory three-dimensional structure. Is done.

The above objects are attained by (A) a second catalyst component containing both iron and manganese elements, a refractory inorganic oxide and an alkaline earth element and / or a rare earth element, and (B) palladium, platinum and At least one noble metal selected from the group consisting of rhodium, copper and a fourth catalyst component containing a refractory inorganic oxide are supported on a refractory three-dimensional structure in a single layer. This is also achieved by a catalyst for purifying diesel engine exhaust gas.

[0018]

Hereinafter, the present invention will be described in more detail.

The refractory inorganic oxide used in the present invention includes activated alumina, silica, titania, zirconia,
Silica-alumina, alumina-zirconia, alumina-
Titania, silica-titania, silica-zirconia, titania-zirconia, zeolite and the like are used. Its average particle size is from 0.1 to 5 μm, preferably from 0.5 to 5 μm.
2 μm. The refractory inorganic oxide BET (Br
unaer-Emmett-Teller) surface area is 1 to 200 m ² / g,
Preferably it is 10-150 m < ² > / g.

The supported amount of both iron and manganese per liter of the three-dimensional structure is 0.5 to 50 g, preferably 2 to 20 g. That is, the supported amount is 0.5 g
If less than 50 g, the activity is insufficient.
If the amount exceeds the above, the activity cannot be improved in proportion to the added amount. Also, the molar ratio of iron to manganese (Fe: M
n) is 10: 1 to 1:10, preferably 4: 1 to 1:
4, most preferably about 3: 2.

The starting materials for iron and manganese are not particularly limited, but can be generally used in the art, such as metals, oxides, carbonates, nitrates, hydroxides, hydrochlorides, and the like. Acetate or the like is used.

The total amount of iron and manganese with respect to the refractory inorganic oxide is 0.1 to 0.1 with respect to the refractory inorganic oxide.
1 to 98% by weight, preferably 2 to 60% by weight is blended to form the first catalyst component.

The first catalyst component may contain an alkaline earth element or a rare earth element, thereby forming a third catalyst component. Alkaline earth elements are
All elements contained in the alkaline earth family,
Rare earth elements refer to all elements contained in the lanthanoid series. The loading amount of the alkaline earth metal is 0 to 20 g per liter of the refractory three-dimensional structure, preferably,
0.1 to 10 g. That is, if the amount of the alkaline earth element exceeds 20 g, the activity cannot be improved in proportion to the added amount.

The amount of the rare earth element to be carried is from 0 to 30 g, preferably 0.1 g, per liter of the refractory three-dimensional structure.
10 g. That is, when the amount of the rare earth exceeds 30 g, the activity cannot be improved in proportion to the added amount.

The starting materials for the alkaline earth elements and the rare earth elements are not particularly limited, but those usually used in the art can be used. Examples thereof include metals, oxides, carbonates, nitrates, and sulfuric acids. Salts, hydroxides, halides, acetates and the like are used. The supported amount of at least one noble metal selected from the group consisting of palladium, platinum and rhodium per liter of the three-dimensional structure is 0.1.
001 to 6 g, preferably 0.05 to 3 g. That is, if the amount is less than 0.001 g, the activity is insufficient. On the other hand, if the amount exceeds 6 g, the activity cannot be improved in proportion to the added amount.

The starting materials for the noble metals include, for example, metals,
Nitrate, hydrochloride and the like are used. The amount of the noble metal with respect to the refractory inorganic oxide is 0.0003 to 80% by weight, preferably 0.04 to 20% by weight, and the second catalyst component is formed by blending the noble metal.

[0027] Copper can be blended with the second catalyst component, whereby a fourth catalyst component is formed. The supported amount of copper is 0 to 1 per liter of the refractory three-dimensional structure.
0 g, preferably 0.1 to 3 g. That is, when the amount of copper exceeds 10 g, the production of sulfate at 500 ° C. or more increases.

The starting material for copper is not particularly limited, but one generally used in the art can be used. Examples thereof include metals, oxides, carbonates, nitrates, sulfates, hydroxides, and the like. Halides, acetates and the like are used.

The total amount of the refractory inorganic oxide is preferably from 1 to 300 g, preferably from 10 to 100 g, per liter of the catalyst. That is, if it is less than 1 g, the contribution to the activity is small, while if it exceeds 300 g, the improvement of the activity corresponding to the added amount is small and the back pressure increases when used as a refractory three-dimensional structure catalyst. Tend.

The above elements may be supported on the refractory inorganic oxide, or may be mixed with the refractory inorganic oxide.

The catalyst of the present invention is selected from palladium, platinum and rhodium, a catalyst component in which both iron and manganese and, if necessary, an alkaline earth element or a rare earth element are dispersed and supported on a refractory inorganic oxide. A structure in which at least one noble metal and, in some cases, a copper element dispersed and supported on a refractory inorganic oxide are supported in a single layer on a refractory three-dimensional structure can be employed.

The refractory three-dimensional structure used in the present invention includes monolith type such as ceramic foam, open flow ceramic honeycomb, wall flow type honeycomb monolith, open flow metal honeycomb, metal foam, metal mesh and the like. Carrier can be used. In particular, diesel engine exhaust gas is
When 100 mg or less of particulate matter per m ³ is contained and the SOF content of the particulate matter is 20% or more,
An open flow type ceramic honeycomb or metal honeycomb is preferably used.

As the ceramic honeycomb carrier, cordierite, mullite, α-alumina, zirconia,
Materials made of titania, titanium phosphate, aluminum titanate, betalite, sponge, aluminosilicate, magnesium silicate and the like are preferable, and cordierite is particularly preferable. Also,
As the metal honeycomb carrier, stainless steel, Fe-C
An integrated structure made of a heat-resistant metal having low oxidation resistance such as an r-Al alloy is preferably used. Note that in this specification, the term element is used as having a broad definition including metals and oxides.

The method for preparing the catalyst of the present invention is not particularly limited, and can be prepared, for example, by the following method.

The refractory inorganic oxide is introduced and impregnated into an aqueous solution containing a predetermined amount of each compound of iron and manganese and, in some cases, each compound of an alkaline earth element or a rare earth element. 100 ~
The powder is dried at a temperature of 150 ° C. and then calcined at a temperature of 300 to 850 ° C., preferably 400 to 600 ° C., to form a powder in which oxides of the respective metals are dispersed and supported on a refractory inorganic oxide. Further, at least one noble metal selected from the group consisting of palladium, platinum, and rhodium, and in some cases, a refractory inorganic oxide is charged into an aqueous solution containing a predetermined amount of each compound of copper to be impregnated therein. Make powder by the method.

These powders are wet-pulverized into a slurry, a refractory three-dimensional structure is immersed in the slurry, excess slurry is removed, and the slurry is dried at a temperature of 80 to 250 ° C., preferably 100 to 150 ° C. And then 300-85
Calcination at a temperature of 0 ° C, preferably 400 to 600 ° C, gives the desired catalyst.

[0037]

EXAMPLES The present invention will be described below more specifically with reference to examples.

Example 1 1 kg of zirconia powder (average particle size: 2.0 μm) having a specific surface area of 56 m ² / g was poured into an aqueous solution prepared by dissolving 1012 g of iron nitrate and 406 g of manganese acetate in deionized water. After stirring, the mixture was dried at 150 ° C. for 1 hour, and further baked at 500 ° C. for 1 hour to obtain iron oxide (Fe ₂ O ₃ )
And manganese oxide (MnO) dispersedly supported thereon to obtain zirconia powder (average particle size: 15 μm). Also, palladium 8
Another zirconia powder (average particle size: 1.5 μm) was obtained in the same manner as above except that 0 g of palladium nitrate and 155 g of copper nitrate were dissolved in deionized water. These zirconia powders were mixed and wet-pulverized to form a slurry.

The slurry thus obtained is made of a 5.66 inch diameter × 6.00 inch length cylindrical cordierite honeycomb having about 400 open flow gas flow cells per square inch in cross section. After the support was immersed to remove excess slurry, the support was dried at 150 ° C. for 2 hours, and then calcined at 500 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of palladium and copper oxide were 5 g, 3.6 g, 2 g and 1 g per liter of the structure, respectively, and the supported amounts of zirconia were 25 g each per liter of the structure. Example 2 Specific surface area was 118 m. 1.2 kg of ² / g alumina powder (average particle size: 1.0 μm), 120 g of iron oxide and 40 g of manganese oxide were put into deionized water, thoroughly stirred, dried at 200 ° C. for 1 hour, and further dried at 600 ° C. 2
After firing for an hour, an alumina powder was obtained. In addition, specific surface area machine 8
0 m 2 / g zirconia powder (average particle size 1.2 μm) 8
100 kg was poured into an aqueous solution prepared by dissolving palladium nitrate containing 240 g of palladium in deionized water, stirred sufficiently, dried at 150 ° C. for 1 hour, and further dried at 70 ° C.
It was calcined at 0 ° C. for 1 hour to obtain a zirconia powder having palladium dispersedly supported thereon. The alumina powder and the zirconia powder were sufficiently mixed and wet-pulverized to form a slurry.

The same honeycomb carrier made of cordierite as used in Example 1 was immersed in the slurry thus obtained, excess slurry was removed, dried at 150 ° C. for 1 hour, and then dried at 700 ° C. for 1 hour. After calcining for hours, a catalyst was obtained.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of palladium, alumina, and zirconia were 3 g, 1 g, 6 g, 30 g, and 20 g, respectively, per liter of the structure.

Example 3 A silica powder having a specific surface area of 130 m 2 / g (average particle size 1.2
μm) 1 kg, ferrous sulfate 167 g and manganese nitrate 3
25 g was added to an aqueous solution prepared by dissolving in deionized water, and the mixture was thoroughly stirred, dried at 150 ° C. for 1 hour, and further calcined at 550 ° C. for 2 hours to disperse and support iron oxide and manganese oxide. A silica powder was obtained. In addition, specific surface area 10
0 m ² / g titania powder (average particle size 1.2 μm) 1 k
g was added to an aqueous solution prepared by dissolving rhodium nitrate containing 20 g of rhodium in deionized water, and a titania powder was obtained in the same manner as above. The silica and titania powders were sufficiently mixed and wet-pulverized to form a slurry.

The thus obtained slurry was formed into a cylindrical stainless steel honeycomb carrier having a diameter of 5.66 inches and a length of 6.00 inches having about 300 open flow gas flow cells per square inch in cross section. Was immersed to remove excess slurry, dried at 150 ° C. for 1 hour, and then calcined at 400 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of rhodium, silica and titania are as follows:
2 g, 3 g, 1 g, 50 g and 5 g per liter respectively
It was 0 g.

Example 4 1 kg of a titania-zirconia powder (average particle size: 1.0 μm) having a specific surface area of 146 m ² / g (TiO ₂ / ZrO ₂ molar ratio: 3/1) was mixed with 506 g of iron nitrate and 1 g of manganese nitrate.
083 g was added to an aqueous solution prepared by dissolving in deionized water, stirred thoroughly, dried at 150 ° C. for 2 hours, and further calcined at 600 ° C. for 1 hour to obtain a titania in which iron oxide and manganese oxide were dispersed and supported. -A zirconia powder was obtained. Further, silica-alumina (Si) having a specific surface area of 116 m ² / g
O ₂ / Al ₂ O ₃ molar ratio 2/1) 700 g to platinum 20 g
A silica-alumina powder was obtained in the same manner as described above except that the contained chloroplatinic acid was added to an aqueous solution prepared by dissolving in deionized water. The titania-zirconia and silica-alumina powders were sufficiently mixed and wet-pulverized to form a slurry.

The same honeycomb carrier made of cordierite as that used in Example 1 was immersed in the slurry thus obtained, excess slurry was removed, and the slurry was dried at 150 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of platinum, titania-zirconia and silica-alumina were 10 g, 20
g, 2 g, 3 g, 100 g and 70 g.

Example 5 Alumina powder having a specific surface area of 90 m ² / g (average particle size: 1.
2 μm) 1 kg and 50 g of iron oxide and 100 g of manganese oxide are put into deionized water and, after sufficiently stirred,
After drying at 180 ° C. for 1 hour and further firing at 500 ° C. for 2 hours, an alumina powder was obtained. In addition, the specific surface area is 100 m ²
/ G of zirconia powder (average 1.2 μm) was added to an aqueous solution prepared by dissolving rhodium nitrate solution containing 5 g of rhodium and 19 g of copper nitrate in deionized water, and stirred sufficiently, followed by 2 hours at 150 ° C. It was dried and calcined at 650 ° C. for 1 hour to obtain a zirconia powder in which rhodium and copper oxide were dispersed and supported. The alumina and zirconia powders were mixed and wet-pulverized to form a slurry.

The same cordierite honeycomb carrier as used in Example 1 was immersed in the slurry thus obtained, excess slurry was removed, and the slurry was dried at 150 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of rhodium, copper oxide, alumina and zirconia were 5 g, 10 g and 0.5 g per liter of the structure, respectively.
g, 0.5 g, 100 g and 100 g.

Example 6 Alumina-zirconia powder having a specific surface area of 135 m ² / g (average surface area: 1.0 μm) (Al ₂ O ₃ / ZrO ₂₎
1 kg) was added to an aqueous solution prepared by dissolving 747 g of iron chloride and 456 g of manganese chloride in deionized water, stirred sufficiently, dried at 180 ° C. for 2 hours, and dried at 60 ° C.
Calcination was performed at 0 ° C. for 1 hour to obtain an alumina-zirconia powder in which iron oxide and manganese oxide were dispersed and supported. Alumina powder having a specific surface area of 80 m ² / g (average particle size: 1.0 μm)
2. 1 kg of chloroplatinic acid containing 20 g of platinum and copper chloride
An alumina powder was obtained in the same manner as above except that 4 g was dissolved in deionized water. The alumina-zirconia and the alumina powder were mixed and sufficiently wet-pulverized to form a slurry.

The thus obtained slurry was formed into a cylindrical stainless steel honeycomb carrier having a diameter of 5.65 inches and a length of 6.00 inches having a gas flow cell of about 200 oven flows per square inch in cross section. Was immersed to remove excess slurry, dried at 150 ° C. for 1 hour, and then calcined at 400 ° C. for 1 hour to obtain a completed catalyst.

Iron oxide, manganese oxide,
The supported amounts of platinum, copper oxide, alumina-zirconia, and alumina were 30 g, 10
g, 1 g, 0.1 g, 50 g and 50 g.

Example 7 An aqueous solution prepared by dissolving 1 kg of alumina powder (average particle size: 1.0 μm) having a specific surface area of 100 m ² / g in 506 g of iron nitrate, 203 g of manganese acetate and 50 g of cerium nitrate in deionized water was used. After throwing in and stirring thoroughly, 200 ° C
For 2 hours, and calcined at 500 ° C. for 1 hour to obtain an alumina powder in which iron oxide, manganese oxide and cerium oxide are dispersed and supported. An aqueous solution prepared by dissolving palladium nitrate containing 40 g of palladium and 77 g of copper nitrate in deionized water was added to 600 g of zirconia powder (average particle size: 1.0 μm) having a specific surface area of 80 m ² / g. A zirconia powder was obtained by the same operation as described above. The alumina powder and the zirconia powder were mixed and wet-pulverized to form a slurry.

The slurry obtained in this manner has a cylindrical cordierite honeycomb having a diameter of 5.66 inches and a length of 6.00 inches having about 400 open-flow gas flow cells per square inch in cross section. After the support was immersed to remove excess slurry, the support was dried at 150 ° C. for 2 hours, and then calcined at 500 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amount of cerium oxide, palladium, copper oxide, alumina and zirconia was 5
g, 3.6 g, 1 g, 2 g, 1 g, 50 g and 30 g
Met.

Example 8 800 g of titania powder having a specific surface area of 125 m ² / g (average particle size: 1.0 μm), 50 g of iron oxide, 36 g of manganese oxide, and 50 g of lanthanum oxide were charged into deionized water, and thoroughly stirred. After drying at 150 ° C. for 2 hours, and further firing at 600 ° C. for 1 hour, a titania powder was obtained. Also,
Same as above except 700 g of silica powder (average particle size 0.8 μm) having a specific surface area of 150 m ² / g was added to an aqueous solution prepared by dissolving palladium nitrate containing 20 g of palladium and 39 g of copper nitrate in deionized water. , A silica powder was obtained. The titania powder and the silica powder were mixed and wet-pulverized to form a slurry.

The slurry obtained in this manner has a cylindrical cordierite honeycomb carrier having a diameter of 5.66 inches and a length of 6.00 inches having about 300 open-flow gas flow cells per square inch in cross section. After immersion, removing excess slurry, dried at 150 ℃ for 2 hours,
Then, it was calcined at 500 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of lanthanum oxide, palladium, copper oxide, titania and silica were 5 g each per liter of the structure,
3.6 g, 5 g, 2 g, 1 g, 80 g and 70 g.

Example 9 An aqueous solution prepared by dissolving 1 kg of zirconia powder (average particle size: 1.0 μm) having a specific surface area of 80 m ² / g in 1012 g of iron nitrate, 406 g of manganese acetate and 254 g of magnesium nitrate in deionized water. After putting in and stirring enough,
It was dried at 180 ° C. for 2 hours, and further calcined at 500 ° C. for 1 hour to obtain zirconia powder in which iron oxide, manganese oxide and magnesium oxide were dispersed and supported. In addition, the specific surface area is 80
Zirconia powder having an m ² / g (average particle size of 1.0 μm)
A zirconia powder was obtained in the same manner as described above except that palladium nitrate containing 80 g of palladium and 113 g of copper nitrate in 1 kg were added to an aqueous solution prepared by dissolving in deionized water. These zirconia powders were mixed and wet-pulverized to form a slurry.

The thus obtained slurry was formed into a cylindrical stainless steel honeycomb having a diameter of 5.66 inches and a length of 6.00 inches having about 200 open flow gas flow cells per square inch of cross section. The carrier was immersed to remove excess slurry, dried at 150 ° C. for 2 hours, and calcined at 500 ° C. for 1 hour to obtain a catalyst.

In the catalyst, iron oxide, manganese oxide,
The supported amounts of magnesium oxide, palladium and copper oxide were 5 g, 3.6 g, 1 g, 2 g per liter of the structure.
g and 1 g, and the amount of zirconia carried was 25 g per liter of the structure.

Example 10 1 kg of zirconia powder (average particle size: 1.0 μm) having a specific surface area of 110 m ² / g was charged into 50 g of iron oxide, 36 g of manganese oxide, and 211 g of calcium nitrate in deionized water, and thoroughly stirred. , Dried at 200 ° C for 2 hours, and further fired at 600 ° C for 1 hour to obtain zirconia powder. Further, except that 500 g of titania powder (average particle diameter 0.8 μm) having a specific surface area of 150 m ² / g was charged into an aqueous solution prepared by dissolving palladium nitrate and 39 g of copper nitrate containing 20 g of palladium in deionized water. Titania powder was obtained by the same operation. The zirconia powder and the titania powder were mixed and wet-pulverized to form a slurry.

The slurry thus obtained is made of a 5.66 inch diameter × 6.00 inch long cylindrical cordierite honeycomb having about 300 open flow gas flow cells per square inch in cross section. After the support was immersed to remove excess slurry, the support was dried at 150 ° C. for 2 hours, and then calcined at 500 ° C. for 1 hour to obtain a catalyst.

The iron oxide, manganese oxide,
The loading amount of calcium oxide, palladium, copper oxide, zirconia and titania was 5
g, 3.6 g, 5 g, 2 g, 1 g, 100 g and 50 g
g.

Example 11 1 kg of alumina powder (average particle size: 1.0 μm) having a specific surface area of 100 m ² / g was charged with 1012 g of iron nitrate, 406 g of manganese acetate, 254 g of magnesium nitrate, and cerium nitrate 1
After adding 0.1 g to deionized water and stirring thoroughly,
The resultant was dried at 0 ° C. for 2 hours and further calcined at 500 ° C. for 1 hour to obtain an alumina powder in which iron oxide, manganese oxide, magnesium oxide, and cerium oxide were dispersed and supported. In addition, zirconia powder having a specific surface area of 80 m ² / g (average particle size 1.0 μm)
m) A zirconia powder was obtained in the same manner as above, except that 1 kg was charged into an aqueous solution prepared by dissolving 80 g of palladium and 155 g of copper nitrate in deionized water. This alumina powder and zirconia powder were mixed and wet-pulverized to form a slurry.

The thus obtained slurry was formed into a cylindrical stainless steel honeycomb having a diameter of 5.66 inches and a length of 6.00 inches having about 400 open-flow gas flow cells per square inch in cross section. After immersing the carrier and removing excess slurry, the carrier was dried at 150 ° C. for 2 hours,
Then, it was calcined at 500 ° C. for 1 hour to obtain a catalyst.

The iron oxide, manganese oxide,
The supported amounts of magnesium oxide, cerium oxide, palladium, copper oxide, alumina and zirconia were 5 g, 3.6 g, 1 g, 1 g, 2 g, and 1 g of the structure, respectively.
1 g, 25 g and 25 g.

Comparative Example 1 1 kg of titania powder (average particle size: 1.2 μm) having a specific surface area of 100 m ² / g was removed from palladium nitrate containing 30 g of palladium, 31.3 g of copper sulfate, 253 g of iron nitrate and 195 g of manganese nitrate. Pour into an aqueous solution prepared by dissolving in ionic water, mix thoroughly, dry at 150 ° C. for 2 hours, and calcinate at 550 ° C. for 2 hours to disperse and carry palladium, copper oxide, iron oxide and manganese oxide. A titania powder was obtained. This titania powder was sufficiently wet-pulverized to form a slurry.

The slurry thus obtained is made of a 5.66 inch diameter × 6.00 inch long cylindrical cordierite honeycomb having about 300 open flow gas flow cells per square inch in cross section. After the support was immersed to remove excess slurry, the support was dried at 150 ° C. for 1 hour, and then calcined at 500 ° C. for 1 hour to obtain a catalyst.

The supported amounts of palladium, copper oxide, iron oxide, manganese oxide and titania in the catalyst were 3 g, 1 g, 5 g, 3.6 g and 100 g per liter of the structure, respectively.

Comparative Example 2 1 kg of zirconia powder (average particle size: 2.0 μm) having a specific surface area of 45 m ² / g was prepared by dissolving palladium nitrate containing 1 g of palladium and 3.2 g of copper sulfate in deionized water. The solution was poured into an aqueous solution, thoroughly stirred, dried at 180 ° C. for 1 hour, and calcined at 700 ° C. for 1 hour to obtain a zirconia powder in which palladium and copper oxide were dispersed and supported. The zirconia powder was sufficiently wet-pulverized to form a slurry.

The slurry obtained in this manner is a cylindrical cordierite honeycomb having a diameter of 5.66 inches and a length of 6.00 inches having about 200 open flow gas flow cells per square inch of cross section. After the support was immersed to remove excess slurry, the support was dried at 150 ° C. for 2 hours, and then calcined at 500 ° C. for 1 hour to obtain a catalyst.

Further, 1 kg of alumina powder (average particle size: 1.0 μm) having a specific surface area of 95 m ² / g was added to 249 g of iron chloride.
And 228 g of manganese chloride were dissolved in deionized water and poured into an aqueous solution. The mixture was thoroughly stirred, dried at 170 ° C. for 1 hour, and calcined at 650 ° C. for 2 hours to disperse and support iron oxide and manganese oxide. Alumina powder was obtained. This alumina powder was sufficiently wet-pulverized to form a slurry.

The above honeycomb carrier was immersed in the slurry obtained in this manner, and alumina powder was supported on zirconia powder in the same manner to obtain a catalyst.

The supported amounts of palladium, copper oxide, iron oxide, manganese oxide, zirconia and alumina in this catalyst were 0.1 g, 0.1 g, and 0.1 g, respectively, per liter of the structure.
g, 20 g, 10 g, 100 g and 100 g.

Comparative Example 3 1.5 kg of alumina powder (average particle size: 2.0 μm) having a specific surface area of 60 m ² / g was put into an aqueous solution prepared by dissolving 253 g of iron nitrate and 271 g of manganese nitrate in deionized water. After stirring thoroughly, dry at 160 ° C for 1 hour,
Calcination was performed at 500 ° C. for 2 hours to obtain an alumina powder in which iron oxide and manganese oxide were dispersed and supported. This alumina powder was wet-pulverized to form a slurry.

The slurry thus obtained has a cylindrical cordierite honeycomb having a diameter of 5.66 inches and a length of 6.00 inches having about 100 open flow gas flow cells per square inch of cross section. After the support was immersed to remove excess slurry, the support was dried at 150 ° C. for 2 hours to obtain a catalyst.

An aqueous solution prepared by dissolving 500 g of titania powder (average particle size: 1.0 μm) having a specific surface area of 150 m ² / g in 10 g of palladium nitrate and 7.7 g of copper nitrate in deionized water. Then, the mixture was sufficiently stirred, dried at 150 ° C. for 1 hour, and calcined at 600 ° C. for 1 hour to obtain a titania powder in which palladium and copper oxide were dispersed and supported. The titania powder was slurried by wet grinding.

The above honeycomb carrier was immersed in the slurry thus obtained, and titania powder was supported on alumina powder in the same manner to obtain a catalyst.

The iron oxide, manganese oxide,
The supported amounts of palladium, copper oxide, alumina and titania were 5 g, 5 g, 1 g, and 1 g, respectively, per liter of the structure.
0.2 g, 150 g and 50 g.

Comparative Example 4 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that 228 g of copper nitrate was dissolved in deionized water. The supported amounts of alumina and copper oxide in this catalyst were 50 g and 3.0 g per liter of the structure, respectively.

Comparative Example 5 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that 158 g of chromium nitrate was dissolved in deionized water. The supported amounts of alumina and chromium oxide in this catalyst were 50 g and 3.0 g per liter of the structure, respectively.

Comparative Example 6 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that palladium nitrate containing 20 g of palladium was dissolved in deionized water. The supported amounts of alumina and palladium in this catalyst were 50 g and 0.1 g, respectively, per liter of the structure.
g.

Comparative Example 7 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that chloroplatinic acid containing 20 g of platinum was dissolved in deionized water. The amount of alumina and platinum carried in this catalyst was determined by the structure 1
50 g and 1.0 g per liter respectively.

Comparative Example 8 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that rhodium nitrate containing 20 g of rhodium was dissolved in deionized water. The supported amounts of alumina and rhodium in this catalyst were 50 g and 1.0 g, respectively, per liter of the structure.

Comparative Example 9 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that 200 g of nickel acetate and 12.1 g of copper acetate were dissolved in deionized water. The amount of alumina, nickel oxide and copper oxide carried on this catalyst was 50
g and 3.0 g and 1.5 g.

Comparative Example 10 A catalyst was obtained in exactly the same manner as in Comparative Example 1, except that 72.5 g of cobalt nitrate and 60.7 g of copper nitrate were dissolved in deionized water. The amount of alumina, cobalt oxide and copper oxide carried on this catalyst was 5
0 g, 1.0 g and 1.0 g.

Examples 1 to 11 and Comparative Examples 1 to 10
Table 1 shows the amount of each component carried in the catalyst obtained in Table 1.
And Table 2.

[0091]

[Table 1]

[0092]

[Table 2]

(Evaluation of catalysts) The performance of each catalyst for purifying diesel engine exhaust gas was evaluated by the following method.

In this method, a supercharged direct injection diesel engine (4 cylinders, 2800 cc) and light oil having a sulfur content of 0.38% by weight were used as fuel.

Each of the catalysts was attached to an exhaust gas pipe from the above-mentioned engine, and a 300-hour durability test was carried out under the conditions of a full engine load of 250 rpm and a catalyst inlet temperature of 600 ° C.

Next, under stable conditions at a catalyst inlet temperature of 300 ° C. and 500 ° C. at an engine speed of 2000 rpm, fine particles in exhaust gas before entering the catalyst bed (inlet) and after leaving the catalyst bed (outlet). The content of the substance was measured by an ordinary dilution tunnel method, and the purification rate (%) of the particulate substance was determined.

Further, the particulate matter captured using the dilution tunnel was extracted with a dichloromethane solution, and the SOF emission was measured from the change in the weight of the particulate matter before and after the extraction to determine the SOF purification rate.

Further, sulfur dioxide and gaseous hydrocarbons in the exhaust gas before entering the catalyst bed and in the exhaust gas after passing through the catalyst bed were simultaneously analyzed, and their addition rates (%) were determined. Table 3 shows the results.

[0099]

[Table 3]

[0100]

Industrial Applicability The catalyst of the present invention is excellent in the performance of removing harmful components such as unburned hydrocarbons and carbon monoxide from low temperatures in addition to carbon-based fine particles, and has the ability to oxidize sulfur dioxide even at high temperatures. , The production of sulfate can be suppressed. Therefore, the catalyst of the present invention is excellent in reducing particulate matter in diesel engine exhaust gas,
By using the catalyst of the present invention, the exhaust gas of a diesel engine can be efficiently purified.

Further, since the catalyst of the present invention is also excellent in the ability to remove SOF, it is extremely effective in purifying exhaust gas from diesel engines.

Further, since the catalyst of the present invention is excellent in high-temperature durability, it can be mounted on a diesel vehicle without causing practical problems.

Therefore, the catalyst of the present invention is not
It has the ability to purify OF, unburned hydrocarbons, etc., and 500
4% sulfur dioxide oxidation rate even in high temperature range over ℃
It is capable of exhibiting excellent performance of suppressing the following.

As described above, the catalyst of the present invention is very useful as a catalyst for purifying exhaust gas from diesel engines.

Claims (4)

(57) [Claims] 1. A first catalyst component containing (A) both iron and manganese elements and a refractory inorganic oxide, and (B) at least one noble metal selected from the group consisting of palladium, platinum and rhodium. A catalyst for purifying exhaust gas of a diesel engine, wherein a third catalyst component containing a refractory inorganic oxide is supported in a single layer on a refractory three-dimensional structure. 2. A catalyst comprising (A) a second catalyst component containing both iron and manganese elements, a refractory inorganic oxide and an alkaline earth element and / or a rare earth element, and (B) palladium, platinum and rhodium. Purification of exhaust gas from a diesel engine, characterized in that at least one noble metal selected from the group and a third catalyst component containing a refractory inorganic oxide are supported in a single layer on a refractory three-dimensional structure. Catalyst 3. A first catalyst component containing (A) both iron and manganese elements and a refractory inorganic oxide, and (B) at least one noble metal selected from the group consisting of palladium, platinum and rhodium; A catalyst for purifying exhaust gas of a diesel engine, comprising a single layer of a refractory three-dimensional structure and a fourth catalyst component containing copper and a refractory inorganic oxide. 4. A group consisting of (A) a first catalyst component containing both iron and manganese elements and a refractory inorganic oxide and an alkaline earth element and / or a rare earth element, and (B) palladium, platinum and rhodium. A diesel engine exhaust gas characterized in that at least one noble metal selected from the group consisting of copper and a fourth catalyst component containing a refractory inorganic oxide is supported in a single layer on a refractory three-dimensional structure. Purification catalyst.