JPH11207182A - Catalyst for catalytic reduction of nitrogen oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst for catalytic reduction of nitrogen oxides with which nitrogen oxides in an exhaust gas can be efficiently reduced without using a large amt. of a reducing agent by selectively reacting, nitrogen oxides with the reducing agent even in the presence of oxygen, especially in the presence of oxygen, sulfur oxides and water in catalytic reduction of nitrogen oxides by using hydrocarbons and oxygen-contg. org. compds. as a reducing agent. SOLUTION: This catalyst for catalytic reduction of nitrogen oxides is prepared by depositing (a) iridium and (b) at least one kind selected from indium and gallium on an oxide carrier and uses hydrocarbons and/or oxygen-contg. org. compds. as a reducing agent. The component (a) is deposited by 0.1 to 10 wt.% calculated as metal, and the component (b) is deposited by 0.1 to 20 wt.% calculated as metals. The oxide carrier consists of titanium oxide, silica, alumina, zirconia or silica alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon or an oxygen-containing organic compound as a reducing agent, and more particularly, to a catalyst contained in exhaust gas discharged from factories, automobiles and the like. The present invention relates to a catalyst for catalytic reduction of nitrogen oxides, which is suitable for reducing and removing harmful nitrogen oxides.

[0002]

2. Description of the Related Art Conventionally, nitrogen oxides contained in exhaust gas are obtained by oxidizing the nitrogen oxides and then absorbing them into an alkali, or by using a reducing agent such as ammonia, hydrogen, carbon monoxide, or a hydrocarbon. It has been removed by a method of converting to nitrogen.

However, according to the former method, it is necessary to take measures for treating the generated alkaline waste liquid to prevent the occurrence of pollution. On the other hand, according to the latter method, when ammonia is used as the reducing agent, it reacts with the sulfur oxide in the exhaust gas to form salts, and as a result, the reduction activity of the catalyst is reduced. Also, hydrogen, carbon monoxide,
Even when hydrocarbons and the like are used as reducing agents, they react with oxygen present at a higher concentration than nitrogen oxides present at a lower concentration, so a large amount of reducing agent is required to reduce nitrogen oxides. There is a problem that.

Therefore, recently, a method of directly decomposing nitrogen oxides with a catalyst in the absence of a reducing agent has been proposed. However, such a known catalyst has been known as a nitrogen oxide. Since the decomposition activity is low, there is a problem that it is difficult to put to practical use.

On the other hand, various zeolites and the like have been proposed as a new catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon or an oxygen-containing compound as a reducing agent.
M-5 and H-type _{ZSM-5 (SiO 2 / Al} 2 O 3 molar ratio = 30 to 40) are to be optimal. However, even with such Cu-ZSM-5 and H-type ZSM-5, it is still difficult to say that they have sufficient reducing activity. In particular, when the exhaust gas contains moisture, aluminum in the zeolite structure is dealuminated. And the performance drops sharply. Therefore, there is a demand for a catalyst for catalytic reduction of nitrogen oxides having higher reduction activity and excellent durability even in the presence of moisture.

[0006] A catalyst comprising silver or silver oxide supported on an inorganic oxide has also been proposed. However, such a catalyst has a high oxidation activity and a low selectivity to nitrogen oxide. The removal rate is low. Further, there is another problem that the catalyst activity is significantly deteriorated in the coexistence of a sulfur oxide (Japanese Patent Laid-Open No. 5-317647).

[0007] In addition, a catalyst comprising iridium supported on barium oxide has been proposed, but this catalyst also does not have a sufficient reducing activity, and it is strongly desired to further improve the selective reactivity. Requested.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a nitrogen oxide using a hydrocarbon or an oxygen-containing organic compound as a reducing agent. In the catalytic reduction of, a large amount of a reducing agent is used by selectively reacting a nitrogen oxide with a reducing agent even in the coexistence of oxygen and, particularly, in the coexistence of oxygen, sulfur oxides and moisture. An object of the present invention is to provide a catalyst for catalytic reduction of nitrogen oxides that can efficiently reduce nitrogen oxides in exhaust gas without using the catalyst.

[0009]

According to the present invention, there is provided a hydrocarbon comprising (a) iridium and (b) at least one selected from indium and gallium supported on an oxide carrier. A catalyst for catalytic reduction of nitrogen oxides using an oxygen-containing organic compound as a reducing agent is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The catalyst according to the present invention is a catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon and / or an oxygen-containing organic compound as a reducing agent, and is selected from indium and gallium as component (b). At least one of them is supported on an oxide carrier described later together with iridium as the component (a).

According to the present invention, iridium, which is the component (a), is supported on an oxide carrier in the form of metal, ion or oxide depending on the method of preparing the catalyst and the treatment conditions of the exhaust gas. On the other hand, indium or gallium as the component (b) is supported on an oxide carrier in the form of ions or oxides, depending on the method for preparing the catalyst.

For example, when the above component (a) or (b) is supported on a carrier by an ion exchange method, each of the above components is supported as an ion. On the other hand, when the component is supported by an impregnation method, it is supported as an oxide. You. (A) or
(b) After the component is supported on the carrier by the impregnation method, it is heated (for example, 300 ° C. or higher) in a hydrogen atmosphere and subjected to a reduction treatment, whereby the iridium metal can be supported.

However, in the present invention, the component (a) is supported on an oxide carrier as a metal (partially including an oxide), as is the case with each component in the examples, and (b) The component is preferably supported on the oxide carrier as an oxide.

In the present invention, as the oxide carrier, conventionally known ones, for example, titanium oxide, silica, alumina, zirconia, silica-alumina and the like are appropriately used. Silica alumina is particularly preferably used because it has a synergistic effect on the catalytic performance and has a high reducing activity on nitrogen oxides by supporting the above components (a) and (b).

In the catalyst according to the present invention, the amount of iridium, which is the component (a), of the component (a) or (b) is 0.1 to 10% by weight in terms of metal. On the other hand, the loading amount of at least one selected from indium and gallium as the component (b) is a total of 0.
Preferably it is in the range of 1 to 20% by weight.

The amount of the component (a) supported exceeds 10% by weight in terms of metal, and the amount of the component (b) supported is 20% in terms of metal.
If the amount is more than 10% by weight, the oxidizing power of the obtained catalyst is too high, resulting in poor selectivity. However, when the supported amount of the component (a) or the component (b) is less than 0.1% by weight in terms of metal, the resulting catalyst is not sufficient in the activity of reducing nitrogen oxides. In particular, according to the present invention, the supported amount of the component (a) is in the range of 0.5 to 5% by weight in terms of metal, and the supported amount of the component (b) is 1 to 10% by weight in terms of metal. %.

According to the present invention, a catalyst comprising the components (a) and (b) supported on an oxide carrier in such a range has a moderate oxidizing power as compared with a conventionally known catalyst. ,
Although the reason is not completely clear, since partial oxidation or cracking of hydrocarbons or oxygen-containing organic compounds is promoted, the catalytic reduction reaction of nitrogen oxides using hydrocarbons or oxygen-containing organic compounds as a reducing agent is promoted. It seems to have extremely high activity and selectivity. Moreover, since the catalyst according to the present invention has excellent resistance to sulfur oxides, it can be suitably used as, for example, a denitration catalyst for exhaust gas from a diesel engine or a catalyst for diesel vehicles and lean burn gasoline vehicles. . Further, the catalyst according to the present invention is a catalyst for the catalytic reduction reaction of nitrogen oxides in exhaust gas.
It also has an excellent characteristic that the (space velocity) dependence is extremely small.

Since the catalyst according to the present invention can be usually obtained as a powder or a granular material, it can be formed into various shapes such as a honeycomb shape and a spherical shape by a conventionally known forming method. Can be. During this molding,
A molding aid, a molded body reinforcement, an inorganic fiber, an organic binder, and the like may be appropriately compounded. Further, the catalyst according to the present invention may be supported on a carrier formed in a honeycomb shape in advance.

In particular, according to the present invention, the catalyst is prepared in the form of a powder, and an inert base material is separately formed into a required shape in advance, and the catalyst is added thereto by an appropriate method such as a wash coat method. It can be advantageously used as a catalyst structure coated and supported. Here, as the inert substrate, for example, using a mineral substance such as cordierite,
This is made into a structure such as a honeycomb, a sphere, a ring, or the like, and a catalyst is supported on these to form a catalyst structure.

According to the present invention, as described above, a catalyst layer is formed on the surface of a structure such as a honeycomb, a sphere, or a ring made of an inert substrate by a wash coat method or the like. When the catalyst is supported, it is preferable that the catalyst layer is supported on the surface of the structure such that the catalyst layer has a thickness of 10 μm or more from the surface (hereinafter, referred to as a catalyst layer thickness for simplicity). By making the catalyst layer supported on the structure over a thickness of 10 μm or more from the surface in this way, reactivity to nitrogen oxides,
That is, it is possible to obtain a catalyst structure having high selectivity for reducing nitrogen oxides. However, according to the present invention, the thickness of the catalyst layer may be usually 200 μm or less. Even if the thickness of the catalyst layer exceeds 200 μm, it is not possible to obtain a selective reduction property corresponding to the thickness, which is not preferable from the viewpoint of the cost of producing the catalyst.

In the catalytic reduction of nitrogen oxides using the catalyst according to the present invention, the reducing agent comprising a hydrocarbon may be, for example, a gaseous one such as a hydrocarbon gas such as methane, ethane, propane, propylene and butylene; Examples of the shape include single-component hydrocarbons such as pentane, hexane, octane, heptane, benzene, toluene, and xylene, and mineral oil-based hydrocarbons such as gasoline, kerosene, light oil, and heavy oil. In particular, according to the present invention, among the above, ethylene, propylene, isobutylene, 1-butene, lower alkenes such as 2-butene, propane, lower alkanes such as butane, light oil, kerosene and the like are preferably used as the reducing agent. . These hydrocarbons may be used alone or, if necessary, in combination of two or more.

Examples of the reducing agent comprising an oxygen-containing organic compound include aldehydes such as acetaldehyde, formaldehyde and acrolein; alcohols such as methanol, ethanol, propanol and octanol; and dimethyl ether, diethyl ether and dipropyl ether. Ethers, methyl acetate, ethyl acetate,
Esters such as oils and fats, for example, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone can be mentioned. Among these, the most preferred oxygen-containing organic compounds are aldehydes. These oxygen-containing organic compounds may also be used alone, and if necessary,
Two or more kinds may be used in combination.

Further, in the present invention, a mixture of the hydrocarbon and the oxygen-containing organic compound may be used as a reducing agent.

In the present invention, the reducing agent varies depending on the specific hydrocarbon or oxygen-containing organic compound used, but is usually in the range of about 0.1 to 3 in terms of molar ratio to nitrogen oxide. Used. When the amount of the reducing agent used is less than 0.1 in terms of the molar ratio to the nitrogen oxide, sufficient reducing activity for the nitrogen oxide cannot be obtained.
When the molar ratio exceeds 3, the discharge amount of the unreacted reducing agent increases, so that after the catalytic reduction treatment of the nitrogen oxide, a post-treatment for recovering the nitrogen oxide is required.

Unburned or incomplete combustion products such as fuel present in the exhaust gas, that is, hydrocarbons and particulates are also effective as reducing agents, and these are also included in the hydrocarbons of the present invention. It is. From this point of view, from a different viewpoint, the catalyst according to the present invention is also used as a catalyst for reducing or removing hydrocarbons and particulates in exhaust gas,
Can be useful.

The optimum temperature at which the catalyst of the present invention exhibits a reducing activity on nitrogen oxides varies depending on the reducing agent and the type of catalyst used, but is usually in the range of 100 to 600 ° C., preferably 200 to 400 ° C. It is in the range of ° C. According to the present invention, in such a temperature range, 500 to 1000
By flowing the exhaust gas through a reactor filled with a catalyst at a space velocity (SV) of about 00 hr ^-1 , nitrogen oxides in the exhaust gas can be efficiently reduced and removed.

[0027]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. Hereinafter, the supported amount is in terms of metal.

(1) Preparation of catalyst Example 1 7.75 g of iridium chloride aqueous solution (5.00% by weight as iridium) and 1.49 g of indium chloride (InCl ₃ )
And 38.74 g of activated titanium oxide (specific surface area 109 m ² / g, SSP-M manufactured by Sakai Chemical Industry Co., Ltd.) in deionized water 10
Added to 0 mL. The obtained slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder comprising 1% by weight of Ir and 2% by weight of In on titanium oxide.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
It was applied to a honeycomb substrate made of cordierite having a square inch to carry Ir-In / titanium oxide at a ratio of about 140 g / L (layer thickness: 61 μm). This catalyst is referred to as A-1
That.

Example 2 15.00 g of an aqueous solution of iridium chloride (5.00% by weight as iridium) and 1.49 of indium chloride (InCl ₃ )
g and activated titanium oxide (specific surface area 109 m ² / g, SSP-M manufactured by Sakai Chemical Industry Co., Ltd.)
Added to 00 mL. The obtained slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder comprising 2% by weight of Ir and 2% by weight of In on titanium oxide.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
It was applied to a honeycomb substrate made of cordierite having a square inch to carry Ir-In / titanium oxide at a ratio of about 140 g / L (layer thickness: 61 μm). This catalyst is referred to as A-2
That.

Example 3 24.25 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and 1.49 of indium chloride (InCl ₃ ).
g and activated titanium oxide (specific surface area 109 m ² / g, SSP-M manufactured by Sakai Chemical Industry Co., Ltd.)
Added to 00 mL. The obtained slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder comprising 3% by weight of Ir and 2% by weight of In on titanium oxide.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
It was applied to a honeycomb substrate made of cordierite having a square inch to carry Ir-In / titanium oxide at a ratio of about 140 g / L (layer thickness: 61 μm). This catalyst is designated A-3
That.

Example 4 7.75 g of iridium chloride aqueous solution (5.00% by weight as iridium) and 3.73 g of indium chloride (InCl ₃ )
And 38.74 g of activated titanium oxide (specific surface area 109 m ² / g, SSP-M manufactured by Sakai Chemical Industry Co., Ltd.) in deionized water 10
Dispersed in 0 mL. This slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder comprising 1% by weight of Ir and 5% by weight of In on titanium oxide.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
It was applied to a honeycomb substrate made of cordierite having a square inch to carry Ir-In / titanium oxide at a ratio of about 140 g / L (layer thickness: 61 μm). This catalyst is referred to as A-4
That.

Example 5 7.75 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and 3.73 g of indium chloride (InCl ₃ )
And 38.74 g of silica alumina (specific surface area 320 m ² / g, M-15 manufactured by Devison Chemical Co., Ltd.) were added to 100 mL of ion-exchanged water. The obtained slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder comprising 1% by weight of Ir and 5% by weight of In on titanium oxide.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
About 140 g / L of Ir-In / silica alumina is applied to a honeycomb substrate made of square inch cordierite.
(Layer thickness of 88 μm). This catalyst is called A
It is called -5.

Example 6 7.75 g of an aqueous solution of iridium chloride (5.00% by weight as iridium) and 3.73 g of indium chloride (InCl ₃ )
And γ-alumina powder (AC11 manufactured by Sumitomo Chemical Co., Ltd.)
K) 38.74 g was added to 100 mL of ion-exchanged water. The obtained slurry is dried with a spray drier and
The powder was fired at 0 ° C. for 3 hours to obtain a powder in which 1% by weight of Ir and 5% by weight of In were supported on alumina.

60 g of this powder and 6 g of silica sol (Snowtex N, manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
The coating was applied to a honeycomb substrate made of cordierite having a square inch to carry Ir-In / alumina at a ratio of about 140 g / L (layer thickness 74 μm). This catalyst is called A-6.

Example 7 7.75 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and gallium nitrate (Ga (NO ₃ ) ₃ .nH)
7.12 g of ₂ O) and silica alumina (specific surface area 320 m ²
/ G, Devison Chemical Co., Ltd. M-15) 38.74 g
Was added to 100 mL of ion-exchanged water. The obtained slurry was dried by a spray drier and calcined at 500 ° C. for 3 hours to obtain 1% by weight of Ir and 2% of Ga in silica alumina.
In this way, a powder which was supported by weight% was obtained.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
About 140 g / L of Ir-Ga / silica-alumina is applied to a honeycomb substrate made of square inch cordierite.
(Layer thickness of 88 μm). This catalyst is called A
It is called -7.

Example 8 24.25 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and gallium nitrate (Ga (NO ₃ ) ₃ .n)
7.12 g of H ₂ O and silica alumina (specific surface area 320 m)
² / g, M-15 manufactured by Devison Chemical Co., Ltd.) 38.74
g was added to 100 mL of ion-exchanged water. This slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder comprising silica alumina carrying 3% by weight of Ir and 2% by weight of Ga.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
About 140 g / L of Ir-Ga / silica-alumina is applied to a honeycomb substrate made of square inch cordierite.
(Layer thickness of 88 μm). This catalyst is called A
It is called -8.

Example 9 24.25 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and gallium nitrate (Ga (NO ₃ ) ₃ .n)
17.80 g of H ₂ O) and silica alumina (specific surface area 320)
m ² / g, M-15) manufactured by Devison Chemical Co., Ltd.) 38.7
4 g was added to 100 mL of ion-exchanged water. The obtained slurry was dried with a spray drier,
After firing for 3 hours, 3% by weight of Ir
Was carried to obtain 5% by weight of a powder.

60 g of this powder and 6 g of silica sol (Snowtex N, manufactured by Nissan Chemical Industries, Ltd.) were mixed with an appropriate amount of water, and the mixture was wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
About 140 g / L of Ir-Ga / silica-alumina is applied to a honeycomb substrate made of square inch cordierite.
(Layer thickness of 88 μm). This catalyst is called A
It is called -9.

Comparative Example 1 24.25 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and silica alumina (specific surface area: 320 m ²⁾
/ G, Devison Chemical Co., Ltd. M-15) 38.74 g
Was added to 100 mL of ion-exchanged water. The obtained slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours to obtain a powder in which 3% by weight of Ir was supported on silica alumina.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) are mixed with an appropriate amount of water, and the mixture is wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
The coating was applied to a honeycomb substrate made of cordierite having a square inch to carry Ir / silica alumina at a ratio of about 140 g / L (layer thickness: 88 μm). This catalyst is called B-1.

Comparative Example 2 24.25 g of an iridium chloride aqueous solution (5.00% by weight as iridium) and 38.74 g of barium sulfate (1.9 m ² / g, barium sulfate BA manufactured by Sakai Chemical Industry Co., Ltd.) were ion-exchanged with water. Added to 100 mL. The obtained slurry was dried with a spray drier and calcined at 500 ° C. for 3 hours.
A powder comprising 3% by weight of Ir supported on barium sulfate was obtained.

60 g of this powder and 6 g of silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) were mixed with an appropriate amount of water, and the mixture was wet-ground with a planetary mill for 5 minutes using 100 g of zirconia balls as a grinding medium. A wash coat slurry was prepared. This slurry was prepared using 200 /
It was applied to a honeycomb substrate made of cordierite having a square inch, and was loaded with Ir / barium sulfate at a ratio of about 140 g / L (layer thickness 53 μm). This catalyst is called B-2.

(2) Evaluation Test Using the catalysts (A-1 to 9) according to the present invention and the catalysts (B-1 to 2) of the comparative examples under the following test conditions, Nitrogen oxide catalytic reduction was performed, and the removal rate of nitrogen oxide was determined by a chemical luminescence method.

[0051] (However, when light oil was used as the reducing agent, the light oil was C12 in terms of C.) (2) Space velocity 50000 (hr ^-1 ) (3) Reaction temperature 200 ° C, 250 ° C, 300 ° C,
350 ° C., 400 ° C. or 450 ° C. The results are shown in Table 1.

[0052]

[Table 1]

[0053]

As described above, the catalyst for catalytic reduction of nitrogen oxides according to the present invention uses hydrocarbons and / or oxygen-containing organic compounds as a reducing agent even in the presence of oxygen, sulfur oxides and moisture. In addition, it is possible to efficiently reduce the nitrogen oxides in the exhaust gas, and is excellent in durability and sulfur oxide resistance.

Continuing from the front page (72) Keiichi Tabata 5-11 Ebisushima-cho, Sakai City, Osaka Prefecture Sakai Chemical Industry Co., Ltd. (72) Inventor Kazuyuki Ueda 5-1-1 Ebisushimacho Sakai City, Osaka Prefecture Central Research Laboratory Co., Ltd.

Claims (3)

[Claims] 1. A hydrocarbon and / or oxygen-containing organic compound characterized in that (a) iridium and (b) at least one selected from indium and gallium are supported on an oxide carrier. The catalyst for catalytic reduction of nitrogen oxides used. 2. Component (a) is 0.1 to 10% by weight in terms of metal.
(B) component is 0.1 to 20 in metal conversion.
The catalyst according to claim 1, which is supported in a range of weight%. 3. The catalyst according to claim 1, wherein the oxide carrier is titanium oxide, silica, alumina, zirconia or silica-alumina.