JPH0623270A - Catalyst for catalystic reduction of nitrogen oxides - Google Patents

Abstract

PURPOSE:To provide a catalystic reduction catalyst for nitrogen oxides which can efficiently reduce nitrogen oxides in exhaust gas discharged from plants, automobiles, etc., without using large quantities of reducing agents and also is supeior in durability, even in the presence of moisture. CONSTITUTION:The catalystic reduction catalyst for nitrogen oxides is formed by ion-exchanging a transition metal ion to at least one kind metallic oxide selected from the group consisting of aluminum oxide, silicone dioxide, titanium oxide zirconium oxide, niobium pentaoxide and stannic oxide and depositing it, and hydrocarbon and/or an oxygen-containing compound are used as the reducing agent.

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. More specifically, it is suitable for use in reducing and removing harmful nitrogen oxides 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 uses various hydrocarbons and / or oxygen-containing compounds as a reducing agent.

[0002]

2. Description of the Related Art Conventionally, nitrogen oxides contained in exhaust gas have been produced by oxidizing nitrogen oxides and then absorbing it in an alkali, or by using a reducing agent such as ammonia, hydrogen, carbon monoxide, or hydrocarbon. It is removed by a method such as conversion to nitrogen. However, according to the former method, it is necessary to treat the generated alkaline waste liquid to prevent 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 reducing activity of the catalyst is lowered. Even when hydrogen, carbon monoxide, hydrocarbon, etc. are used as a reducing agent, they react with oxygen present in a higher concentration than nitrogen oxide present in a low concentration, and therefore, in order to reduce nitrogen oxides. Has a problem that it requires a large amount of reducing agent.

For this reason, recently, a method of directly decomposing a nitrogen oxide with a catalyst in the absence of a reducing agent has been proposed. However, such a conventionally known catalyst has been proposed as a nitrogen oxide. There is a problem that it cannot be put to practical use because of its low decomposition activity. In addition, as a new catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon or an oxygen-containing compound as a reducing agent, H 2
Type zeolite and Cu ion exchange ZSM-5 have been proposed. In particular, H type _{ZSM-5 (SiO 2 / Al} 2 O 3
The molar ratio = 30-40) is said to be optimal. However, it is difficult to say that even such H-type ZSM-5 has sufficient reducing activity, and in particular, when water is contained in the gas, aluminum in the zeolite structure is dealuminated, resulting in poor performance. A catalyst for catalytic reduction of nitrogen oxides, which has a much higher reducing activity and has excellent durability even when the gas contains water, is desired because of its rapid decrease.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to use oxygen when a hydrocarbon or an oxygen-containing compound is used as a reducing agent. In the coexistence of
Even in the presence of oxygen and water, nitrogen oxides selectively react with hydrocarbons and oxygen-containing compounds, so nitrogen oxides in exhaust gas can be efficiently reduced without using a large amount of reducing agent. Moreover, it is to provide a catalyst for catalytic reduction of nitrogen oxides, which has excellent durability even in the presence of water.

[0005]

A catalyst for catalytic reduction of nitrogen oxides using the first hydrocarbon and / or oxygen-containing compound according to the present invention as a reducing agent is aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, pentaoxide. At least one selected from the group consisting of niobium oxide and stannic oxide
It is characterized in that a transition metal is ion-exchanged and supported on one kind of metal oxide.

The above-mentioned metal oxides used as a carrier or substrate in the present invention, namely, aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, niobium pentoxide and stannic oxide have a hydroxyl group on the surface thereof. The hydrogen ion contained therein can be ion-exchanged with a transition metal cation or a complex cation having a transition metal as a constituent component. The ion exchange capacity is usually 0.5 mmol equivalent / g, though it depends on the kind of metal oxide and the preparation conditions.

In the present invention, various commercially available products can be used as the above-mentioned metal oxide. If necessary, a neutralizing agent is added to an aqueous solution of a water-soluble salt of the metal to cause hydrolysis, or It can be obtained by hydrolyzing under heating conditions to form a precipitate, separating the precipitate, washing thoroughly with water, and then calcining. The transition metal used in the present invention, IIIA in the periodic table of the long periodic type, IVA,
An element belonging to the VA, VIIA, VIII and IB group, specifically, for example, Sc, Ti, V, Cr, M of the 4th period.
n, Fe, Co, Ni and Cu, the fifth period Y, Zr,
Nb, Mo, Tc, Ru, Rh, Pd and Ag, La group of the sixth period, Hf, Ta, W, Re, Os, Ir, Pt
And Au can be removed. Among these, for the metal that cannot obtain a water-soluble cation, for example, platinum is used for complex ionization such as a tetravalent ammine complex or a divalent ammine complex and then subjected to ion exchange. do it.

In the present invention, the ion exchange method is not particularly limited and can be carried out by a conventionally known ordinary method. For example, the metal oxide is dispersed in water, and the cation or complex cation of the transition metal to be ion-exchanged does not cause precipitation under sufficient stirring,
In addition, cations or complex cations may be added while keeping the pH as high as possible. Thus, in the ion exchange, the cation or complex cation of the transition metal to be ion-exchanged does not cause precipitation, and the ion exchange with the hydrogen ion of the hydroxyl group is carried out by keeping the pH as high as possible. The capacity can be increased.

As the ion exchange proceeds, the pH of the liquid is lowered by the exchanged hydrogen ions. Therefore, a neutralizing agent such as ammonia is added to maintain the pH high as described above, and the ion exchange is performed. Good to do. When the metal ion to be exchanged is not hydrolyzed by heating as in the case of copper, nickel, etc., the ion exchange may be performed under the condition of increasing the temperature in order to increase the ion exchange rate. Good. The ion species to be ion-exchanged may be a single species or a mixture of two or more species.

After the ion exchange, the substrate metal oxide is filtered, washed with water and dried, and if necessary, 200 to 8
When calcined at 00 ° C., a catalyst for catalytic reduction of nitrogen oxides, which is obtained by carrying out ion exchange of a transition metal on a metal oxide and supporting it, can be obtained according to the present invention. In addition, precious metals are
Further reduction with hydrogen or the like is preferable. In the present invention, the amount of the transition metal ion to be carried on the metal oxide by ion exchange varies depending on the kind of the metal ion, but usually the base metal is 0.1 to 2.0% by weight, and the noble metal is The range of 0.01 to 5% by weight is preferable. Even if the transition metal ions are excessively supported on the substrate in excess of the supported amount,
In the obtained catalyst, not only the effect corresponding to the increase of the supported amount cannot be obtained, but also in the reaction system in which oxygen coexists, the consumption of hydrocarbons and oxygen-containing compounds by oxygen increases, which is not preferable. . On the other hand, when the supported amount is less than the above, the reducing activity of the catalyst cannot be sufficiently improved.

It is not always clear why the ion-exchange-supported catalyst has a higher activity than that prepared by a conventional impregnation method, but it has a very high dispersity and an oxidizing ability higher than that of an oxide. Is low, and it is considered that the selectivity can be increased in this reaction. Further, regarding the noble metal system, the noble metal particle size is smaller than that of the impregnation method, which is considered to enhance the selectivity.

The catalyst according to the present invention can be formed into various shapes such as a honeycomb shape and a spherical shape by a conventionally known forming method. At the time of this molding, a molding aid, a molded body reinforcing material, an inorganic fiber, an organic binder and the like may be appropriately mixed. It is also possible to carry the coating on a preformed substrate by a washcoat method or the like. Furthermore,
It is also possible to use other conventionally known catalyst preparation methods.

In the practice of the present invention, specific examples of the hydrocarbon used as the reducing agent include those in a gaseous state,
Hydrocarbon gas such as methane, ethane, butylene, etc. in liquid form, such as pentane, hexane, octane, heptane, benzene, toluene, xylene, etc., single component hydrocarbons, gasoline, kerosene, light oil, heavy oil, etc. Mineral oil-based hydrocarbons and the like. Particularly preferred hydrocarbons include lower alkynes such as acetylene, methylacetylene and 1-butyne, lower alkenes such as ethylene, propylene, isobutylene, 1-butene and 2-butene, lower dienes such as butadiene and isoprene, propane and butane. And lower alkanes and the like.

The suitable amount of hydrocarbon added varies depending on the kind, but is 0.1 to 2 in terms of molar ratio with respect to nitrogen oxides.
It is a degree. When it is less than 0.1, sufficient reducing activity cannot be obtained, while when the molar ratio exceeds 2,
Since the amount of unreacted hydrocarbons emitted is large, a post-treatment for recovering the unreacted hydrocarbons is required. The oxygen-containing compound used as a reducing agent in the practice of the present invention is an organic compound having an oxygen element in its molecule. Specific examples thereof include methyl alcohol, ethyl alcohol,
Alcohols such as propyl alcohol and octyl alcohol, ethers such as dimethyl ether, diethyl ether and dipropyl ether, methyl acetate, ethyl acetate,
Examples thereof include esters such as oils and fats and ketones such as acetone and methyl ethyl ketone. Suitable oxygen-containing compounds include lower alcohols such as methyl alcohol and ethyl alcohol.

The above hydrocarbons and oxygen-containing compounds may be used alone or in combination of two or more if necessary. Further, the hydrocarbon and the oxygen-containing compound may be used alone or in combination of two or more. It should be noted that unburned substances such as fuel and incomplete combustion products existing in the exhaust gas, that is, hydrocarbons and patty chelates are also effective as reducing agents, and these are also included in the hydrocarbon of the present invention. From this point of view, it can be said that the catalyst according to the present invention is also useful as a catalyst for reducing or removing hydrocarbons, patty chelates and the like in exhaust gas.

The temperature at which the reducing agent shows a selective reduction reaction with respect to nitrogen oxides increases in the order of oxygen-containing compound <alkyne <alkene <aromatic hydrocarbon <alkane. Further, in the hydrocarbons of the same system, the temperature becomes lower as the carbon number becomes larger. The optimum temperature at which the catalyst according to the present invention exhibits reduction activity for nitrogen oxides varies depending on the reducing agent and the catalyst species used, but is usually 100 to 800.
℃. In this temperature range, space velocity (SV)
It is preferable to circulate the exhaust gas at about 500 to 100,000. In the present invention, a particularly suitable temperature range is 200
~ 600 ° C.

[0017]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

(1) Preparation of catalyst Example 1 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.) was put into 250 ml of ion-exchanged water, and (1 + 5) hydrochloric acid was added thereto to adjust the pH to 5. It was set to 0. Under sufficient agitation to, copper nitrate _{(Cu (NO 3) 2 ·} 3H 2 O) 0.95g was dissolved in ion-exchanged water 50 ml Cu ion aqueous solution was added comprising,
Cu ion exchange was performed. During this period, the pH was maintained at 5.0 by adding 2% by weight aqueous ammonia as the pH decreased. In this way, a predetermined Cu ion aqueous solution was added and then stirred for 2 hours.

Then, the γ-alumina powder thus ion-exchanged is filtered, washed with an aqueous nitric acid solution having a pH of 5.0, dried at 120 ° C. for 18 hours, and then at 500 ° C. for 4 hours.
After being calcined for a time, Cu ion-supported alumina catalyst powder (Cu
The amount of supported ions was 0.5% by weight). To 50 g of this powder, 25 g of silica sol (Snowtex N made by Nissan Chemical Co., Ltd.) was added, and the viscosity was adjusted with water to obtain a slurry for wash coat. This slurry was applied on a 1.25 mm pitch honeycomb manufactured by Kojilulite Co., Ltd. (hereinafter, this honeycomb is simply referred to as a honeycomb) to support a catalyst to obtain a trial sample (A-1). The amount of catalyst loaded on the honeycomb is
It was 0.103 g per 1 cc of honeycomb.

Example 2 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.) was put into 100 ml of ion-exchanged water, and stannic chloride (SnCl ₄ .xH ₂ O, SnCl ₄ ) was further added thereto. 6%)
4.55 g was added and heated to boiling for hydrolysis. The solid content was washed with ion-exchanged water and then calcined at 500 ° C. for 4 hours to obtain a metal oxide mixture powder having a SnO ₂ / Al ₂ O ₃ weight ratio of 2/98.

50 g of this metal oxide powder was put into 250 ml of ion-exchanged water, and 10 wt% ammonia water was added thereto to adjust the pH to 6.0. Under sufficient stirring, a Co ion aqueous solution prepared by dissolving 1.24 g of cobalt nitrate (Co (NO ₃ ) ₂ .6H ₂ O) in 50 ml of deionized water was added to carry out Co ion exchange. During this period, 2% by weight aqueous ammonia was added to maintain the pH at a predetermined value. In this way, after the predetermined Co ion aqueous solution was added, stirring was continued for 2 hours. Thereafter, in the same manner as in Example 1, Co ion-supported SnO ₂ —Al ₂ O ₃ catalyst powder (C
The amount of o-ion supported was 0.5% by weight), and a trial sample (A-2) was obtained using this. The amount of catalyst loaded on the honeycomb was 0.133 g per 1 cc of the honeycomb.

Example 3 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.) was put into 100 ml of ion-exchanged water, and 50 ml of a hydrochloric acid aqueous solution of niobium pentachloride (4.1 g as NbCl ₅ ) was further added thereto. , Heated to boiling and hydrolyzed. After washing the solid content with ion-exchanged water, the solid content is baked at 500 ° C. for 4 hours to obtain N
A metal oxide mixture powder having a b ₂ O ₅ / Al ₂ O ₃ weight ratio of 2/98 was obtained.

50 g of this metal oxide powder was added to ion-exchanged water.
Pour into 250 ml and add 10 wt% ammonia water to it.
In addition, the pH was 6.0. With sufficient stirring for this, nitric acid
Nickel (Ni (NO₃)₂・ 6H₂O) 1.24 g
Solution of Ni ion dissolved in 50 ml of water
Well, Ni ion exchange was performed. During this period, 2% by weight
Monia water was added to maintain the pH at the specified value. in this way
Then, after adding a predetermined Ni ion aqueous solution, at 2:00
The stirring was continued for a while. Hereafter, in the same manner as in Example 1,
Ni Ni-supported Nb₂O_Five-Al₂O ₃Catalyst powder
(Amount of Ni ion supported: 0.5% by weight) was obtained, and using this,
A prototype sample (A-3) was obtained. Supporting catalyst to honeycomb
The holding amount was 0.126 g per 1 cc of honeycomb.

Example 4 Silica powder (Cyroid 800 manufactured by Fuji Devison Co., Ltd.) 50
Into 250 ml of ion-exchanged water, the tetravalent platinum ammine complex aqueous solution (5 × as Pt) was added under sufficient stirring.
10 ⁻⁴ g / l) 50 g was added for platinum ammine complex ion exchange. During this period, 2 wt% aqueous ammonia was added to maintain the pH at 7.0. Thereafter, in the same manner as in Example 1, Pt-supported SiO ₂ catalyst powder (Pt supported amount:
05% by weight), and using this, a prototype sample (A-
4) was obtained. The loading amount of the catalyst on the honeycomb is 1
It was 0.097 g per cc.

Example 5 150 g of metatitanic acid (TiO ₂ .H ₂ O) (60 g of titanium oxide) was calcined at 500 ° C. for 3 hours to obtain anatase type titanium oxide having a specific surface area of 117 m ² / g. This was added to 300 ml of water, 2% by weight aqueous ammonia was added to this with stirring to adjust the pH to 2.0, and after filtration, it was thoroughly washed with ion-exchanged water and dried at 120 ° C. for 18 hours.

50 g of the obtained powder was added to ion-exchanged water 250
It is poured into ml, and with sufficient stirring, ferric nitrate (F
_{e (NO 3) 2 · 6H} 2 O) 1.57g of deionized water 50
Fe ion aqueous solution dissolved in ml was added to carry out Fe ion exchange. During this time, the pH was maintained at a predetermined value. In this way, after the predetermined Fe ion aqueous solution was added, the mixture was further stirred for 2 hours.

Thereafter, the solid content was filtered, washed with an aqueous nitric acid solution having a pH of 2.0, and dried at 120 ° C. for 12 hours, and then 5
Fe (III) ion-exchanged TiO by firing at 00 ° C for 4 hours
_Two catalyst powders (Fe ion supported amount: 0.5% by weight) were obtained. This is used in the same manner as in Example 1 to make a prototype sample (A
-5) was obtained. The amount of catalyst loaded on the honeycomb was 0.115 g per 1 cc of the honeycomb.

Example 6 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.) was placed in 250 ml of ion-exchanged water, and (1 + 5) hydrochloric acid was added to adjust the pH to 6.0. With sufficient stirring, 0.78 g of lanthanum nitrate (La (NO ₃ ) ₃ .6H ₂ O) was dissolved in 50 ml of deionized water to add a La ion aqueous solution to carry out La ion exchange. During this period, the pH was maintained at 6.0 by adding 2% by weight aqueous ammonia as the pH decreased. In this way, after adding a predetermined La ion aqueous solution, the mixture was further stirred for 2 hours.

Then, the solid content was filtered and washed with a nitric acid aqueous solution having a pH of 6.0, and then La was washed in the same manner as in Example 1.
(III) Ion-exchange alumina catalyst powder (La ion support amount
0.5% by weight), and using this, a prototype sample (A-
6) was obtained. The loading amount of the catalyst on the honeycomb is 1
It was 0.137 g per cc.

Example 7 50 g of γ-alumina powder (AF-115 manufactured by Sumitomo Chemical Co., Ltd.)
Was poured into 250 ml of ion-exchanged water to prepare a slurry. The pH of this slurry was 4.2. 2% by weight aqueous ammonia was added to this slurry to adjust the pH to 5.5. Separately, 0.09 g of tetraammineplatinum (II) chloride was dissolved in 50 ml of ion-exchanged water to prepare a [Pt (NH ₃ ) ₄ ] ²⁺ ion-exchange aqueous solution, which was sufficiently added to the slurry of γ-alumina powder. In addition to vigorous stirring, [Pt (NH ₃ ) ₄ ] ²⁺ was exchanged for hydrogen ions in alumina. During this period, as the pH decreased, 2% by weight of ammonia water was added to adjust the pH to 5.5.
Maintained at. In this way, after adding a predetermined tetraammineplatinum (II) chloride aqueous solution, the mixture was stirred at 70 ° C. for 2 hours.

Then, the γ-alumina powder thus ion-exchanged is filtered, washed with an aqueous nitric acid solution having a pH of 5.5 and dried at 120 ° C. for 18 hours, and then at 500 ° C. for 4 hours.
Firing for an hour, and further in a nitrogen / hydrogen (4/1) mixed gas flow,
Reduction treatment was performed at 600 ° C. for 4 hours. Hereinafter, in the same manner as in Example 1, a trial sample (A-7) was obtained. The amount of catalyst loaded on the honeycomb was 0.122 g per 1 cc of the honeycomb.

Example 8 In Example 7, tetraammineplatinum chloride (II) 0.4
Prototype sample (A-
8) was obtained. The loading amount of the catalyst on the honeycomb is 1
It was 0.127 g per cc.

Example 9 In Example 7, tetraammineplatinum chloride (II) 0.9
Prototype sample (A-
9) was obtained. The loading amount of the catalyst on the honeycomb is 1
It was 0.130 g per cc.

Example 10 In Example 7, tetraammineplatinum (II) chloride 1.8
Prototype sample (A-
10) was obtained. The amount of catalyst loaded on the honeycomb was 0.134 g per 1 cc of the honeycomb.

Example 11 In Example 7, tetraammineplatinum (II) chloride 4.5
Prototype sample (A-1
1) was obtained. The loading amount of the catalyst on the honeycomb is 1
It was 0.139 g per cc.

Example 12 50 g of γ-alumina powder (AF-115 manufactured by Sumitomo Chemical Co., Ltd.)
Was poured into 250 ml of ion-exchanged water to prepare a slurry. The pH of this slurry was 4.2. (1 + 10) hydrochloric acid was added to this slurry to adjust the pH to 3.0. Separately, 1.22 g of ruthenium chloride hydrate (41% by weight as Ru)
Was dissolved in 50 ml of ion-exchanged water to prepare a Ru ³⁺ ion-exchanged aqueous solution, which was added to the slurry of γ-alumina powder under sufficient stirring to exchange Ru ³⁺ with hydrogen ions in alumina. Let During this time, 2% by weight aqueous ammonia was added to maintain the pH at 3.0. Thus, the ruthenium chloride aqueous solution was added, and then the mixture was stirred at 70 ° C. for 2 hours.

Then, the γ-alumina powder thus ion-exchanged is filtered, washed with a nitric acid aqueous solution having a pH of 3.0, dried at 120 ° C. for 18 hours and then at 500 ° C. for 4 hours.
Firing for an hour, and further in a nitrogen / hydrogen (4/1) mixed gas flow,
Reduction treatment was performed at 600 ° C. for 4 hours. Thereafter, a trial sample (A-12) was obtained in the same manner as in Example 1. The amount of catalyst loaded on the honeycomb was 0.113 g per 1 cc of the honeycomb.

Comparative Example 1 Sodium type ZSM-5 (SiO ₂ manufactured by Japan Mobile Co., Ltd.
/ Al ₂ O ₃ molar ratio = 34) by hydrogen substitution to give H-type ZS
M-5 was treated in the same manner as in Example 2 to obtain a comparative sample (B-1). The amount of the slurry carried at this time was 0.128 g per 1 cc of the honeycomb.

[0039] Comparative Example 2 cobalt nitrate _{(Co (NO 3) 2 ·} 6H 2 O) 1.24g
Was dissolved in 75 ml of ion-exchanged water, 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.) was added, and the mixture was sufficiently stirred to form a slurry. This slurry was spray-dried (manufactured by Yamato Scientific, drying temperature 150 ° C, outlet temperature 5
0 ° C.) and spray dried. The dried product obtained is 5
The mixture was calcined in air at 00 ° C. for 4 hours to obtain a CuO-supported alumina catalyst (support amount as Cu: 0.5% by weight). Less than,
Using this, a trial sample (B-2) was obtained in the same manner as in Example 1. The amount of catalyst loaded on the honeycomb was 0.109 g per 1 cc of the honeycomb.

[0040] Comparative Example 3 Nickel nitrate _{(Ni (NO 3) 2 ·} 6H 2 O) 1.24g
Was dissolved in 75 ml of ion-exchanged water, 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.) was added, and the mixture was sufficiently stirred to form a slurry. Hereinafter, in the same manner as in Comparative Example 2, NiO-supported alumina catalyst (supported amount as Ni)
0.5% by weight). Hereinafter, using this, a trial sample (B-3) was obtained in the same manner as in Example 1. The amount of catalyst loaded on the honeycomb was 0.112 g per 1 cc of the honeycomb.

(2) Evaluation test The trial production samples (A-1) to (A-6) and the comparative sample (B-1) were subjected to nitrogen oxide catalytic reduction of nitrogen oxide-containing gas under the following test conditions. The conversion rate of nitrogen oxides to nitrogen was calculated by quantifying nitrogen by gas chromatography.

(Test conditions) (1) Gas composition NO 1% by volume O ₂ 10% by volume Reducing agent 1% by volume Water 6% by volume He balance (SO ₂ 100% by volume, A-1, A-2 and A-4) (2) Space velocity 30,000 or 60,000 (1 /
Hr) (3) Reaction temperature 300 ° C, 400 ° C, 500 ° C or 600 ° C Table 1 shows the results.

[0043]

[Table 1]

As is clear from the results shown in Table 1, all the catalysts according to the examples of the present invention had a high conversion rate of nitrogen oxides to nitrogen, whereas the catalysts according to the comparative examples generally had the same conversion rate. Low conversion to nitrogen.

[0045]

As described in detail above, the catalyst for catalytic reduction of nitrogen oxides using the hydrocarbons and oxygen-containing compounds according to the present invention as a reducing agent is a catalyst for reducing nitrogen in exhaust gas in the presence of oxygen and water. Oxides can be efficiently catalytically reduced, and also have excellent durability.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location B01J 23/74 301 A 8017-4G 23/82 A 8017-4G 23/84 301 A 8017-4G 37 / 30 7821-4G (71) Applicant 000174541 Sakai Chemical Industry Co., Ltd. 1-2-1, Nishi, Hinocho-cho, Sakai City, Osaka Prefecture (74) The above three agents Attorney Mitsuno Makino (72) Inventor Tadao Nakatsuji Osaka Prefecture Sakai Chemical Industry Co., Ltd., 5-1, Ebisu-machi, Central Research Laboratory (72) Inventor Hiromasu Shimizu Osaka Prefecture, Sakai-shi, 5-1, Ebisu-machi, Central Research Laboratory (72) Inventor, Yaskawa Ritsu Osaka 5-1, Ebishima-cho, Sakai-shi, Sakai Chemical Industry Co., Ltd. Central Research Institute (72) Inventor Akihiro Kitazume 2-15-36 Sugito, Sugito-cho, Kitakatsushika-gun, Saitama (72) Inventor Hiroshi Tsuchida Kawasaki-shi, Kanagawa 2-24-6 Kyomachi, Saki-ku (72) Masaaki Kawatsuki, Masaaki Kawatsuki 2856-1, Osawa, Koshigaya, Saitama Century Condominium No. 103 Saga (72) Inventor, Takehiko Ito 1-1, East Japan Industrial Technology Institute, Tsukuba City, Ibaraki Prefecture (72) Inventor Hideaki Hamada 1-1 East, Tsukuba, Ibaraki Prefecture

Claims (3)

[Claims] 1. A transition metal is ion-exchanged and supported on at least one metal oxide selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, niobium pentoxide and stannic oxide. A catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon and / or an oxygen-containing compound as a reducing agent. 2. A base metal as a transition metal is added to a metal oxide in an amount of 0.
The catalyst for catalytic reduction of nitrogen oxides according to claim 1, wherein the catalyst is supported in an amount of 1 to 2.0% by weight. 3. A noble metal as a transition metal is added to a metal oxide in an amount of 0.
The catalyst for catalytic reduction of nitrogen oxides according to claim 1, wherein the catalyst is supported in an amount of 01 to 5% by weight.