JP3320431B2 - Nitrogen oxide removal 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 removing nitrogen oxides, and more particularly to nitrogen oxides in exhaust gas discharged from internal combustion engines such as automobiles, for example, gasoline engines, diesel engines, boilers and industrial plants. The present invention relates to a catalyst for efficiently removing substances.

[0002]

2. Description of the Related Art In recent years, harmful components of nitrogen oxides (hereinafter, also referred to as NOx) are contained in exhaust gas discharged from internal combustion engines such as automobiles, boilers, and industrial plants. Has become. Therefore, removal of NOx in the exhaust gas has been studied from various aspects.

Conventionally, for example, in the case of automobile exhaust gas, a method has been used in which exhaust gas is treated using a three-way catalyst to remove NOx simultaneously with hydrocarbons (HC) and carbon monoxide (CO). This method is performed under the condition that air is introduced in an amount that can completely burn the fuel. However, when the ratio of air to fuel (air-fuel ratio = air / fuel) increases, oxygen is present in excess of the amount of oxygen necessary to completely burn unfueled components such as hydrocarbons and carbon monoxide in exhaust gas. That is, in such an oxidizing atmosphere, NOx cannot be reduced and removed by a normal three-way catalyst.

In the case of removing nitrogen oxides from a diesel engine or a boiler among internal combustion engines, a method using a reducing agent such as ammonia, hydrogen, or carbon monoxide is generally used. However, this method has a problem that a special device is required for collecting and treating the unreacted reducing agent.

Recently, as a method for removing NOx, a method using a NOx decomposition catalyst comprising a crystalline aluminosilicate containing copper ions has been proposed (JP-A-60-12).
No. 5,250, U.S. Pat. No. 4,297,328), which merely states that nitric oxide (NO) can be decomposed into nitrogen (N ₂ ) and oxygen (O ₂ ). However, it does not describe the effectiveness under actual exhaust gas conditions and that unsaturated hydrocarbons are effective in decomposing NOx.

Japanese Patent Application Laid-Open No. 63-100919 discloses that when an exhaust gas is treated with a copper-containing catalyst in an oxidizing atmosphere in the presence of a hydrocarbon, the reaction between NOx and the hydrocarbon is preferentially promoted. It is described that NOx can be efficiently removed. The hydrocarbon used in this method is
It is stated that hydrocarbons contained in the exhaust gas or hydrocarbons added as needed from outside may be used.
Further, as a specific embodiment, a method is disclosed in which exhaust gas is first contacted with a copper-containing catalyst to remove NOx, and then contacted with an oxidation catalyst to remove hydrocarbons, carbon monoxide, and the like.

However, Japanese Patent Application Laid-Open No. 1-171625 discloses that the above catalyst has poor heat resistance and, when exposed to high-temperature exhaust gas, deteriorates NOx decomposition performance. A method is described in which, when the exhaust gas becomes high in temperature, the exhaust gas is bypassed to the oxidation catalyst or the three-way catalyst.

As described above, at present, a catalyst for decomposing nitrogen oxides that efficiently decomposes and removes NOx in exhaust gas and has excellent high-temperature heat resistance has not been developed.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to
An object of the present invention is to provide a nitrogen oxide removing catalyst that has excellent x decomposition performance, has excellent high-temperature heat resistance, and can efficiently decompose and remove NOx even under a high space velocity (SV).

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and have found that (A) a composite oxide comprising copper and / or cobalt and aluminum;
(B) a catalyst composition comprising at least one zeolite selected from the group consisting of H-type ferrierite, H-type mordenite and proton-substituted pentasil-type zeolite, is supported on a honeycomb-shaped carrier having an integral structure, The present invention has been completed.

That is, the present invention relates to (A) a composite oxide comprising copper and / or cobalt and aluminum, and (B) at least one selected from H-type ferrierite, H-type mordenite and pentasil-type zeolite substituted with protons. The present invention relates to a catalyst for removing nitrogen oxides, characterized in that a catalyst component containing at least one kind of zeolite is supported on a honeycomb-shaped carrier having an integral structure.

Hereinafter, the present invention will be described in detail.

The composite oxide (A) according to the present invention is a composite oxide composed of copper and / or cobalt and aluminum. The content of copper and / or cobalt is (A) copper and / or cobalt and It is 1 to 20% by weight, preferably 2 to 10% by weight, in terms of metal, based on the composite oxide composed of aluminum. If the content of copper and / or cobalt is less than 1% by weight, the catalytic activity decreases, Further, even if the content exceeds 20% by weight, the activity decreases. It is considered that when the content exceeds 20% by weight, the reaction between hydrocarbon and oxygen proceeds preferentially over the reaction between hydrocarbon and nitrogen oxides, so that the catalytic activity is reduced.

Within the above range, the NOx decomposition performance is excellent,
In addition, improvement in high-temperature heat resistance is recognized. This is considered to be due to the fact that the sintering of copper and / or cobalt is suppressed and the high-temperature heat resistance is improved by complexing with copper and / or cobalt and aluminum.

The amount of the composite oxide (A) composed of copper and / or cobalt and aluminum is 10 g to 240 g, preferably 1 g per liter of the integrated structure.
6 g to 200 g. When the amount is less than 10 g, the catalytic activity decreases, and when the amount exceeds 240 g,
The catalyst activity cannot be obtained in proportion to the supported amount.

(A) A method for preparing a composite oxide composed of copper and / or cobalt and aluminum includes a conventional preparation method, for example, (1) mixing a solution of a water-soluble or organic solvent-soluble salt, drying and calcining. (2) a method of mixing a solution of a salt soluble in water or an organic solvent and co-precipitating with ammonia or tartaric acid, for example, (i) adding aqueous ammonia to a mixed aqueous solution of a water-soluble salt of copper and aluminum; , Sodium hydroxide, sodium carbonate, urea, etc., or (ii) using a salt of copper and aluminum soluble in an organic solvent, gelling a mixture of organic solvents with citric acid, tartaric acid, glucose acid, etc. (3) solid-phase reaction method, in which oxides are pulverized, mixed and fired, (4) water-soluble salts of each oxide are added to gel of alumina, dried and fired Method, the element (5), respectively,
A method of performing a gas phase reaction using a compound having a low vapor pressure can be used.

A conventional impregnation method in which alumina is impregnated with a water-soluble salt, dried and calcined is one in which a peak of copper and / or cobalt oxide is sufficiently observed in general X-ray diffraction. However, the above preparation methods (1) to
In the composite oxide composed of copper and / or cobalt and aluminum in (5), fine particles of copper and / or cobalt oxide which could not be observed by X-ray diffraction were present.

Of the above methods, a method of mixing a water-soluble salt and co-precipitating with ammonia or the like to co-precipitate through a hydroxide serving as a precursor of the composite oxide is preferable. Specifically, a mixed aqueous solution containing copper nitrate, cobalt nitrate, and aluminum nitrate is converted into a hydroxide precipitate with ammonia or the like, which is separated by filtration or the like, and the precipitate is dried at about 120 ° C., 800 ° C. By sintering to a degree, a composite oxide can be obtained. The pH during this coprecipitation is preferably about 4 to 10. Further, the drying temperature after performing filtration and washing of the precipitate obtained by various coprecipitation methods is preferably a temperature of about 50 ° C. to 200 ° C., and the calcination temperature is slightly depending on the method of preparing the composite oxide. Although different, a temperature of about 300 ° C. to 800 ° C. is preferred.

The starting sources of copper, cobalt and aluminum used in the composite oxide comprising copper and / or cobalt and aluminum include nitrates, sulfates, acetates, chlorides and alkoxides, and use an organic solvent. In the case of ethylene glycol, hexylene glycol,
Ethanol, 2-propanol and the like can be used.

The zeolite (B) according to the present invention is at least one zeolite selected from the group consisting of H-type ferrierite, H-type mordenite and pentasil-type zeolite substituted with protons.

As the zeolite, those having a silica / alumina (molar ratio) of 4/1 or more are particularly preferably used. The H-type zeolite is usually a Na-type or K-type zeolite in which Na or K is replaced with H (proton). The pentasil-type zeolite is usually a zeolite having a high silica component ratio, and for example, refers to a zeolite having a 10-membered ring such as ZSM-5 and ZSM-11.

(B) A catalyst composition containing H-type ferrierite, H-type mordenite and at least one zeolite selected from the group consisting of pentasil-type zeolites is 10 to 240 g per liter of the volume of the integrated structure,
Preferably, it is 16 to 200 g. When it is less than 10 g, the content of zeolite decreases, and the amount of hydrocarbon adsorbed decreases, so that the NOx decomposition activity decreases,
If the amount exceeds 240 g, hydrocarbons reacting with NOx are sufficiently present on the catalyst surface, so that the NOx decomposing activity corresponding to the supported amount cannot be obtained. Further, the mixing ratio (composite oxide (A) / zeolite (B) weight ratio) of composite oxide (A) and zeolite (B) is usually
0.25 / 1 to 4/1, especially 0.5 / 1 to 2/1
Is preferable. If this mixing ratio exceeds 4/1,
Although the ratio of zeolite (B) decreases and the amount of adsorbed hydrocarbons decreases, the NOx resolution decreases, but even if a large amount of zeolite (B) is used so that the mixing ratio becomes smaller than 0.25 / 1, There is no corresponding improvement in NOx resolution.

The catalyst of the present invention comprises the above composite oxide (A)
And a catalyst composition containing zeolite (B) is coated and supported on a honeycomb-shaped carrier having an integral structure. The method for supporting the coating of the catalyst composition is not particularly limited, but the catalyst according to the present invention is obtained by forming an integrated structure into a slurry obtained by separately wet-milling the composite oxide (A) and the zeolite (B). After impregnating, mixing the composite oxide (A) and zeolite (B), and wet-milling the slurry to impregnate the integrated structure, and removing excess slurry by means such as blowing compressed air, A drying method is particularly preferably used.

In the above method, the average particle diameter of the slurry is preferably in the range of 0.1 to 5 μm, particularly preferably 0.5 to 5 μm.
It is preferably in the range of ３3 μm. When the average particle diameter exceeds 5 μm, the NOx decomposability of the obtained catalyst is reduced. This is considered to be due to the fact that the reaction between hydrocarbon and NOx hardly occurs. On the other hand, even if the average particle diameter is smaller than 0.1 μm, no improvement in NOx resolution corresponding to the average particle diameter is observed. It is considered that this is because the distance between the adsorbed hydrocarbon and NOx is already sufficient to react.

Therefore, by bringing the exhaust gas into contact with the catalyst for removing nitrogen oxides of the present invention, the nitrogen oxides in the exhaust gas can be efficiently decomposed and removed. When the exhaust gas has a low hydrocarbon content, such as diesel engine exhaust gas, the amount of hydrocarbons can be compensated for by adding and introducing hydrocarbons as appropriate to carry out the decomposition and removal.

As the honeycomb-shaped carrier having an integral structure used in the present invention, a monolith honeycomb carrier may be a metal honeycomb carrier, a plug honeycomb carrier, a corrugated carrier, or the like. The number of cells, the shape of the cells, and the like of these integrated structures can be appropriately selected depending on the target internal combustion engine, its exhaust gas amount, linear velocity, and the like.

[0027]

The catalyst for removing nitrogen oxides according to the present invention comprises (1) NOx
Excellent decomposition performance. (2) It has excellent high temperature heat resistance. (3) There is an advantage that NOx can be efficiently decomposed and removed even under a high space velocity.

Further, by using the zeolite (B) according to the present invention in combination with the composite oxide (A), NOx can be efficiently decomposed and removed even at a high space velocity. This is achieved by utilizing the hydrocarbons in the exhaust gas or the hydrocarbons separately introduced in the exhaust gas to reduce the NO in the exhaust gas.
It is considered that when decomposing x, the zeolite (B) functions as a hydrocarbon adsorbent and adsorbs as much hydrocarbon as possible on the catalyst surface.

[0029]

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

(Example 1) As a honeycomb-shaped carrier having an integral structure, a diameter of 33 mm, a length of 76 mm, and a volume of 65 mL (L:
Liter) of a cordierite-type honeycomb carrier (manufactured by Nippon Insulators, Ltd.). Aluminum nitrate [A
l (NO ₃ ) ₃ .9H ₂ O] and 736 g of copper nitrate [Cu (N
Aqueous ammonia was added to a mixed aqueous solution containing 29.7 g of [O ₃ ) ₂ .3H ₂ O] (purity: 78.5%) until the pH became 7 while stirring to prepare a coprecipitate of copper and aluminum.
The obtained coprecipitate was filtered and washed, dried at 120 ° C. for 2 hours, and then calcined at 800 ° C. for 2 hours. The obtained copper-aluminum composite oxide contained 6% by weight of copper in terms of metal.

Separately, animinium sulfate [Al ₂ (SO ₄ )
₃ · 16H ₂ O] 24.3 g and sodium silicate (SiO
₂ content, 58.5% by weight).
idCrystalization Metho
d ", Proceedings8th International
tionic Congress on Catalogy
sis, Berlin, 1984, Vol. 3, p59
According to the method described in No. 6, a Na-type ZSM-5 (silica / alumina (molar ratio), 40/1) zeolite was prepared.
The obtained zeolite was analyzed by X-ray diffraction to obtain Na-type ZSM-5.
Was confirmed. Next, this Na-type ZSM-5 powder was put into a 1 mol aqueous solution of ammonium nitrate,
Stirring at room temperature for 3 hours, washing with water at room temperature,
After drying at 0 ° C. for 24 hours, it was calcined in air at 550 ° C. for 3 hours to obtain H-type ZSM-5 powder.

The above copper-aluminum composite oxide powder 5
0 g and 50 g of H-type ZSM-5 powder were wet-pulverized with a ball mill to prepare an aqueous slurry having an average particle diameter of 1 μm. After the honeycomb-shaped carrier is immersed in the aqueous slurry and taken out, excess slurry is compressed with compressed air.
I blew it away. Next, it was dried at 120 ° C. for 2 hours to obtain a completed catalyst (A).

In the copper-aluminum composite oxide, the copper content was 6% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type ZSM-5 was 1/1.

(Example 2) In Example 1, copper nitrate 2
A completed catalyst (B) was obtained in the same manner as in Example 1, except that 9.9 g of copper nitrate was used instead of 9.7 g.

In the copper-aluminum composite oxide, the copper content was 2% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type ZSM-5 was 1/1. (Example 3) A completed catalyst (C) was obtained in the same manner as in Example 1, except that 49.5 g of copper nitrate was used instead of 29.7 g of copper nitrate.

The copper content of the copper-aluminum composite oxide was 10% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type ZSM-5 was 1/1.

Example 4 In Example 1, cobalt acetate [Co (CH ₃ COO) ₂ .4H] was used instead of copper nitrate.
Except for using ₂ O] 16.9 g, performed in the same manner as in Example 1 to obtain a complete catalyst (D).

In the cobalt-aluminum composite oxide, the cobalt content was 4% by weight, and the mixing ratio (weight ratio) of the cobalt-aluminum composite oxide and the H-type ZSM-5 was 1/1.

(Example 5) In Example 1, the H-type ZS
A completed catalyst (E) was obtained in the same manner as in Example 1 except that 50 g of H-type ferrierite (silica / alumina (molar ratio, 16/1)) was used instead of 50 g of the M-5 powder. Copper-
Copper content of aluminum composite oxide is 6% by weight
And the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type ferrierite was 1/1.

(Embodiment 6) In Embodiment 1, H-type ZS
H-type mordenite (silica /
A completed catalyst (F) was obtained in the same manner as in Example 1 except that 50 g of alumina (molar ratio, 16/1) was used. The copper content of the copper-aluminum composite oxide was 6% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type mordenite was 1/1.

Example 7 A completed catalyst (G) was obtained in the same manner as in Example 1 except that the aqueous slurry having an average particle diameter of 0.5 μm was prepared by adjusting the wet grinding time. The copper content in the copper-aluminum composite oxide was 6% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type ZSM-5 was 1/1.

Example 8 The procedure of Example 1 was repeated, except that the wet milling time was adjusted to prepare an aqueous slurry having an average particle diameter of 3 μm.
I got The copper content in the copper-aluminum composite oxide was 6% by weight, and the copper-aluminum composite oxide and H
The mixing ratio (weight ratio) of the type ZSM-5 was 1/1.

Example 9 In Example 1, the amount of the copper-aluminum composite oxide powder was changed from 50 g to 65 g.
And the amount of the H-type ZSM-5 powder is reduced from 50 g to 35
Except having changed to g, it carried out similarly to Example 1 and obtained the completed catalyst (I).

The copper content of the copper-aluminum composite oxide was 6% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and the H-type ZSM-5 was 1.9 / 1.

Example 10 The amount of the copper-aluminum composite oxide powder used in Example 1 was changed from 50 g to 35 g.
The amount of the H-type ZSM-5 powder is
Except having changed to g, it carried out similarly to Example 1 and obtained the completed catalyst (J).

The copper content of the copper-aluminum composite oxide was 6% by weight, and the mixing ratio (weight ratio) of the copper-aluminum composite oxide and H-type ZSM-5 was 0.53 / 1.
Met.

(Example 11) In place of the copper-aluminum composite oxide and the H-type ZSM-5 in Example 1, 50 g of a copper-aluminum composite oxide powder obtained by the following procedure was used. 50g of ZSM-5 powder used in
A water-based slurry was prepared using a ball mill in the same procedure as in Example 1 except that the above was used to obtain a completed catalyst (K). This copper-aluminum composite oxide and H-type ZSM-5
Was 1/1 in weight ratio.

Method for Preparing Copper-Aluminum Composite Oxide While stirring a mixed solution of 736 g of aluminum nitrate and 29.7 g of copper nitrate, a 1N aqueous sodium hydroxide solution was added until the pH reached 7, and co-precipitation of copper and aluminum was performed. The product was prepared, washed by filtration, dried at 120 ° C. for 2 hours,
Calcination was performed at 800 ° C. for 2 hours to obtain a copper-aluminum composite oxide (copper contained 6% by weight in terms of metal).

(Example 12) In place of the copper-aluminum composite oxide and H-type ZSM-5 in Example 1, 50 g of a copper-aluminum composite oxide powder obtained by the following procedure was used. 50g of ZSM-5 powder used in
A completed catalyst (L) was obtained in the same manner as in Example 1 except that The mixing ratio between the copper-aluminum composite oxide and the H-type ZSM-5 was 1/1 by weight.

Method for Preparing Copper-Aluminum Composite Oxide 93.9 g of urea was added to a mixed aqueous solution containing 736 g of aluminum nitrate and 29.7 g of copper nitrate, and heated and stirred at 80 ° C. for 10 hours to obtain a precipitate. The obtained coprecipitate was filtered and washed, dried at 120 ° C, and calcined at 800 ° C for 2 hours.
An aluminum composite oxide was obtained (copper contained 6% by weight in terms of metal).

Example 13 The procedure of Example 1 was repeated, except that the copper-aluminum composite oxide and the H-type ZSM-5 were replaced with 50 g of a copper-aluminum composite oxide powder obtained by the following procedure. 50g of ZSM-5 powder used in
A finished catalyst (M) was obtained in the same manner as in Example 1 except that The mixing ratio between the copper-aluminum composite oxide and the H-type ZSM-5 was 1/1 by weight.

Method for Preparing Copper-Aluminum Composite Oxide Aluminum isopropoxide [Al (OCH (C
H_Three)_Two)_Three229.8 g, hexylene glycol 50
0 g and 3 liters of isopropanol were added.
Heat and stir for hours to dissolve the isopropoxide.
With copper chloride [CuCl _TwoEtano with 4.87 g dissolved
And then stirred at 85 ° C for 30 minutes.
180 ml of pure water and 450 ml of isopropanol solution
And mixed at 85 ° C. for 10 hours,
A precipitate was obtained by dissolution.

The precipitate was washed with methanol, filtered and washed with pure water, and dried at 120 ° C. for 2 hours.
C. for 2 hours to obtain a copper-aluminum composite oxide (copper contained 4% by weight in terms of metal).

(Example 14) In Example 1, the copper-aluminum composite oxide powder 5 obtained by the following procedure was used instead of the copper-aluminum composite oxide and H-type ZSM-5.
A completed catalyst (N) was obtained in the same manner as in Example 1 except that 0 g and 50 g of the ZSM-5 powder used in Example 1 were used.

Method for Preparing Copper-Aluminum Composite Oxide A mixed solution containing 736 g of aluminum nitrate and 29.7 g of copper nitrate was prepared, evaporated to dryness at 120 ° C. for 12 hours, and then thoroughly mixed in an agate mortar. It was baked at 500 ° C. for 2 hours.

Comparative Example 1 The procedure of Example 1 was repeated except that a copper-zeolite powder prepared according to the following procedure was used instead of the copper-aluminum composite oxide and H-type ZSM-5. The same operation was performed to obtain a completed catalyst (I).

Preparation Method of Copper-Zeolite Powder To 100 g of the same H-type ZSM-5 powder as used in Example 1, 400 g of pure water was added, and the mixture was stirred at 98 ° C. for 2 hours.
At 0.2 ° C., a 0.2 mol / liter aqueous solution of a copper ammine complex was slowly dropped. After completion of the dropwise addition, the mixture was heated and stirred at 80 ° C. for 12 hours to perform ion exchange. The ion-exchanged zeolite was filtered and sufficiently washed with water. The ion-exchanged zeolite was dried at 120 ° C. for 24 hours to obtain a copper-zeolite powder.

The loading ratio of copper is as follows with respect to H type ZSM-5.
It was 5.8% by weight.

Comparative Example 2 The procedure of Example 1 was repeated except that the copper-alumina powder prepared according to the following procedure was used instead of the copper-aluminum composite oxide and H-type ZSM-5. In the same manner, a completed catalyst (II) was obtained.

Preparation method of copper-alumina powder An aqueous solution containing 29.1 g of copper nitrate and a specific surface area of 100 m ² /
g of activated alumina and dried at 120 ° C. for 2 hours, and then calcined at 500 ° C. for 2 hours to obtain a copper-activated alumina powder. Copper loading was 6 per activated alumina.
% By weight. (Comparative Example 3) A completed catalyst (III) was obtained in the same manner as in Comparative Example 2, except that 16.9 g of cobalt acetate was used instead of copper nitrate.

The cobalt loading was 4% by weight with respect to the activated alumina.

(Test Example 1) Catalysts (A) to (N) and (I) prepared in Examples 1 to 13 and Comparative Examples 1 to 5
(III) was subjected to the following initial performance test and temporal performance test.

[Initial Performance Test] Diameter 34.5 mmφ,
After filling the catalyst into a stainless steel reaction tube having a length of 300 mm, a reaction gas having the following composition was introduced under the conditions of a space velocity of 20,000 hr- ¹ . The catalyst performance was evaluated by measuring the NOx purification rate at a catalyst layer inlet temperature of 400 ° C. (initial performance). Table 1 shows the results.

[Reaction gas composition] Carbon monoxide (NO) 75
0 ppm, propylene (C ₃ H ₆ ) 1000 ppm (converted to methane), carbon monoxide (CO) 0.2% by volume, oxygen 2.
0% by volume, 10% by volume of water, 13.5% by volume of carbon dioxide,
Remaining nitrogen.

[Aging Performance Test] Each catalyst was charged into a multi-converter. Exhaust gas from the cruising of a commercially available gasoline electronically controlled engine was mixed with air to fill the packed catalyst bed with an air-fuel ratio (A / F) of 20. / 1, the space velocity (SV) 160,000 / Hr, the catalyst bed temperature 7
It passed for 20 hours under the condition of 00 ° C. Thereafter, the same operation as in the above-mentioned initial performance test was performed, and the NOx purification rate was measured to evaluate the catalytic performance (performance over time). Table 1 shows the results.

(Test Example 2) The oxygen concentration in the reaction gas was set at 2.
Except that the volume was changed from 0% by volume to 10% by volume, the same procedure as in Test Example 1 was performed to evaluate the initial performance and the aging performance of each catalyst. Table 2 shows the results.

[0067]

[Table 1]

[0068]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomohisa Ohata 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo Nippon Shokubai Catalysis Research Laboratories Co., Ltd. JP-A-3-181321 (JP, A) JP-A-1-266854 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 B01D 53 / 86,53 / 94

Claims (4)

(57) [Claims] At least one selected from the group consisting of (A) a composite oxide composed of copper and / or cobalt and aluminum, and (B) an H-type ferrierite, an H-type mordenite, and a pentasil-type zeolite substituted with a proton. A catalyst for removing nitrogen oxides, wherein a catalyst composition containing one kind of zeolite is coated and supported on a honeycomb-shaped carrier having an integral structure. 2. The catalyst for removing nitrogen oxides according to claim 1, wherein the average particle size in the slurry when the catalyst composition is coated and supported on a honeycomb-shaped carrier as a slurry is in the range of 0.1 to 5 μm. 3. The content of copper and / or cobalt is:
(A) 1 to 20% by weight in terms of metal, based on a composite oxide comprising copper and / or cobalt and aluminum
The catalyst for removing nitrogen oxides according to claim 1, wherein 4. The weight ratio of the composite oxide (A) to the zeolite (B) ((A) / (B)) is from 0.25 / 1 to 0.25 / 1.
The catalyst for removing nitrogen oxides according to claim 1, which is 4/1.