JP2591703B2 - Catalyst structure for catalytic reduction of nitrogen oxides - 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 structure for catalytic reduction of nitrogen oxides using a hydrocarbon as a reducing agent, and more particularly, to harmful nitrogen contained in exhaust gas discharged from factories, automobiles and the like. The present invention relates to a catalyst structure for catalytic reduction of nitrogen oxides having high selectivity and high activity suitable for reducing and removing 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, there is a problem that the reduction activity of the catalyst is reduced. In addition, even when hydrogen, carbon monoxide, hydrocarbons, and the like are used as a reducing agent, since they react with oxygen present at a higher concentration than nitrogen oxide present at a lower concentration, it is necessary to reduce nitrogen oxides. Has the problem that a large amount of reducing agent is required.

[0003] Recently, a method of directly decomposing nitrogen oxides with a catalyst in the absence of a reducing agent has also been proposed. However, such a known catalyst has been known to use nitrogen oxides. There is a problem that it is difficult to be put to practical use because of its low decomposition activity. Further, as a new catalyst for catalytic reduction of nitrogen oxide using a hydrocarbon or an oxygen-containing compound as a reducing agent, H-type zeolite, copper ion exchange ZSM-5, and the like have been proposed. In particular, H-type ZSM-5 (SiO ₂ / Al ₂
It is said that an O ₃ molar ratio of 30 to 40) is optimal.
However, it is still difficult to say that such H-type ZSM-5 still has sufficient reducing activity and selectivity. In particular, when moisture is contained in the gas, aluminum in the zeolite structure is dealuminated. Therefore, there is a demand for a catalyst for catalytically reducing nitrogen oxides having a higher reduction activity and an excellent durability even when the gas contains moisture, because the performance is rapidly lowered.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to use a hydrocarbon as a reducing agent in the coexistence of oxygen. In particular, even in the coexistence of oxygen and moisture, since nitrogen oxides selectively react with hydrocarbons, the nitrogen oxides in the exhaust gas can be highly and highly active without using a large amount of a reducing agent. An object of the present invention is to provide a catalyst structure for catalytic reduction of nitrogen oxides which can be reduced with selectivity and has excellent durability even in the presence of moisture.

[0005]

According to the present invention, there is provided a catalyst structure for catalytic reduction of nitrogen oxides using a hydrocarbon as a reducing agent, comprising an inner layer having a catalyst component on a base material constituting the catalyst structure; A catalyst structure for catalytic reduction of nitrogen oxides having a two-layer structure comprising a surface layer carrying a catalyst component on an inner layer, wherein the inner layer is formed of aluminum oxide,
From titanium oxide, zirconium oxide and H-type zeolite
Platinum, iridium, at least one selected carrier
Rhodium, palladium and ruthenium, at least one platinum group element selected from the group consisting of a catalyst component supported thereon , the surface layer is selected from aluminum oxide, titanium dioxide, zirconium oxide and H-type zeolite. The periodic table IIa, IIIa, III
b, IVa, IVb, Va, VIIa and VIII (cobalt and
Excluding nickel and nickel. ) Of is supported at least one metal or its ion or its oxide and said <br/> be composed of catalyst component comprising.

In the present invention, the term "active component" means a component which effectively acts as a catalyst for the catalytic reduction of nitrogen oxides, and the term "carrier" means a component carrying such an active component. Consists of such an active ingredient and a carrier when the active ingredient is supported on a carrier. However, when the catalyst component does not include a carrier, the active component means the catalyst component.

A catalyst structure for catalytically reducing nitrogen oxides using a hydrocarbon as a reducing agent according to the present invention comprises: an inner layer having a first catalyst component on a substrate constituting the catalyst structure; It has a two-layer structure including a surface layer in which the second catalyst component is supported on the inner layer. That is, the surface layer is an exhaust gas to be treated containing nitrogen oxides, that is, a layer in which the reaction gas first comes into direct contact with the catalyst in the catalytic reduction treatment of the reaction gas with the catalyst, and is a layer of the catalyst structure. The inner layer means a catalyst layer located on the outermost surface side, and the inner layer means a catalyst layer which can be reached only when the reaction gas diffuses and moves inside the surface layer.

In the catalyst structure according to the present invention, the above-mentioned substrate means a three-dimensional structure such as a honeycomb, a sphere, a pellet, and the like. A substrate on which a multilayer structure of layers is formed. Such a base material may be an inert structure that does not participate in any catalytic reaction, but may also serve as a carrier for the inner layer. When it also serves as the carrier of the inner layer, for example, as described later, preferably, a conventionally known inorganic oxide such as γ-alumina or a silica mainly containing sodium and aluminum such as zeolite is preferably used. Form three-dimensional structures such as honeycombs, spheres, and pellets made of acid salts. However, in the present invention, the base material may have any other shape as long as it has a three-dimensional shape capable of supporting a two-layer catalyst layer thereon.

[0009] Generally, the inner layer is formed by impregnating, depositing or ion-exchanging the first active ingredient with the carrier,
Yotsute to the combination or the like of these methods, the active ingredient may be by connexion formed to be supported on a carrier. Follow
Thus, according to the present invention, the first active ingredient is supported on a carrier.
This may be supported on an inert substrate as described above to form an inner layer.Also, the substrate itself may be formed from a carrier, and the first active ingredient may be supported on the carrier. Thus, an internal layer may be formed.

After forming the inner layer in this manner, the surface layer is coated with, for example, a slurry containing the second catalyst component by a wash coat method or the like to form the second catalyst component. Can be formed on the inner layer. The catalyst structure for catalytic reduction of nitrogen oxides according to the present invention is basically as described above.
It has a two-layer structure. First, the surface layer will be described.

In the catalyst structure according to the present invention, the support for the active component constituting the surface layer is at least one selected from aluminum oxide (alumina), titanium dioxide (titania), zirconium oxide (zirconia) and H-type zeolite. One type is used. The surface layer is formed on such a carrier by using the periodic table IIa, IIIa, IIIb, IVa, IVb,
Va, VIIa and VIII (excluding cobalt and nickel)
Good. ) It is made of at least one metal or its ion or catalyst component composed by supporting an active ingredient consisting of the oxides selected from.

As an example of the above-mentioned metals, for example, metals of Group IIa of the periodic table include Mg, Ca, Sr and B
a and the like , as a metal of Group IIIa, Y, a lanthanide group metal,
Group IIIb metal is Ga, group IVa metal is Ti and Zr, group IVb metal is Ge and Sn,
Group V metal includes V and Nb, Group VIIa metal includes Mn, and Group VIII metal includes Fe . In the present invention, these active ingredients may be supported on the carrier in the form of metal ions or metal oxides.

In order to support the above-mentioned metal, metal ion or metal oxide on a support such as aluminum oxide, titanium dioxide, zirconium oxide or H-type zeolite, for example, the ion-exchange group of the support is replaced with these metal ions. Precursors (eg, nitrates, sulfates, carbonates, hydroxides, chlorides, etc.) that form metal oxides by calcination are supported on a carrier by an impregnation method, a deposition method, or the like. After firing, a method of converting the precursor into a metal oxide and supporting it, preparing a metallosilicate in which the metal as the active ingredient is incorporated into the zeolite structure during the production of zeolite, and then preparing the metallosilicate By exchanging, for example, an alkali metal ion in a silicate for a hydrogen ion or an ammonium ion, the metal or its ion Can be adopted a method in which a H-type zeolite containing as an active ingredient.

In the catalyst structure according to the present invention, commercially available γ-alumina can be used as the aluminum oxide (alumina) used as a carrier for the active component constituting the surface layer. It is preferable to use high purity γ-alumina having a very low rate. Titanium dioxide (titania) preferably contains sulfate ions obtained by calcining metatitanic acid obtained from a process for producing titanium dioxide by a sulfuric acid method. Zirconium oxide (zirconia) is preferably zirconium oxide containing sulfate ions obtained by adding sulfuric acid to commercially available zirconium hydroxide and baking this.

The H-type zeolite is an alkali metal or alkaline earth metal-ZSM-5, mordenite, US
Those obtained by ion-exchanging a zeolite such as Y with ammonia and calcining, or those obtained by subjecting these zeolites to hydrogen ion exchange under acidic conditions are preferably used. In the surface layer, the loading of the active ingredient is usually 0.1 to 50% by weight. here,
The loading rate is (weight of active ingredient / weight of carrier) × 100.
(% By weight). When the loading rate of the active ingredient in the surface layer is less than 0.1% by weight, sufficient catalytic activity cannot be obtained. On the other hand, even when the loading rate exceeds 50% by weight, the catalyst activity corresponding to the loading rate exceeds 50% by weight. No increase can be obtained. However, if necessary, the carrier may be loaded with the active ingredient in an amount exceeding 50% by weight.

Next, the inner layer in the catalyst structure according to the present invention will be described. In the first catalyst for reducing nitrogen oxides according to the present invention, the inner layer comprises aluminum oxide,
From titanium oxide, zirconium oxide and H-type zeolite
Platinum, iridium, at least one selected carrier
It comprises a catalyst component supporting at least one platinum group element selected from the group consisting of rhodium, palladium and ruthenium .

The carrier for the inner layer is a surface as described above.
Same as the carrier for the layer. In general, various methods for supporting an active component of a catalyst on a carrier have been conventionally known, and in the present invention, a method for supporting a platinum group element, which is an active component, on a carrier is not limited at all. For example, Conventionally known appropriate methods, for example, the above-mentioned impregnation method, deposition method, ion exchange method, or a combination thereof can be used, among others, the carrier such as the γ-alumina, ion exchange method Therefore, it is preferable that the platinum group element is highly dispersed and supported.

In the inner layer of the catalytic structure for catalytic reduction of nitrogen oxides according to the present invention, the loading of the platinum group element, which is the active ingredient, on the carrier is usually 0.1 to 10% by weight. When the loading of the active ingredient in the inner layer of the first catalyst structure according to the present invention is less than 0.1% by weight, sufficient catalytic activity cannot be obtained, while the loading is 10% by weight. However, the increase in the catalytic activity cannot be obtained. However, if necessary, the carrier may be loaded with the active ingredient at a loading of more than 10% by weight.

According to the second catalyst structure for catalytic reduction of nitrogen oxides of the present invention, the inner layer is made of aluminum oxide,
From titanium oxide, zirconium oxide and H-type zeolite
At least one selected carrier includes: (a) the at least one platinum group element ; (b) cerium oxide (CeO ₂ ), lanthanum oxide (La ₂
O _3), neodymium oxide (Nd ₂ O _3), carrying at least one metal oxide selected from the group consisting of germanium oxide (GeO ₂₎ and gallium oxide (Ga ₂ O ₃₎
It is not composed of a catalyst component comprising.

The above-mentioned active ingredient can be supported on a carrier by any of the methods known in the art, as described above.
After the metal oxide such as cerium oxide is supported on the carrier by an impregnation method or a deposition method, it is preferable that the platinum group element is further highly dispersed by an ion exchange method and supported on the carrier. .

In the inner layer of such a second catalyst structure according to the invention, the ratio of said metal oxide such as cerium oxide, lanthanum oxide, neodymium oxide, germanium oxide or gallium oxide to the platinum group element is For 100 parts by weight of metal oxide, platinum group element 0.1 to 100
It is in the range of parts by weight, preferably in the range of 5 to 50 parts by weight. In the internal layer having the metal oxide together with the platinum group element at such a ratio, any active component functions as a site for activating adsorption of hydrocarbons or as an activation site for nitrogen oxides, Since the reaction proceeds selectively, it is considered that the catalyst has high activity and selectivity in the catalytic reduction reaction of nitrogen oxides using a hydrocarbon as a reducing agent.

Furthermore, according to the second catalyst structure of the present invention, when the above-mentioned active component is supported on the above-mentioned carrier in the inner layer, the loading ratio is usually 5%.
５０50% by weight. When the loading of the active ingredient is less than 5% by weight, sufficient catalytic activity cannot be obtained,
On the other hand, if the loading exceeds 50% by weight, a corresponding increase in catalytic activity cannot be obtained.

In a third catalyst structure according to the present invention, the inner layer is made of aluminum oxide, titanium dioxide, zirconium oxide.
And at least one carrier selected from H and zeolite H
In a (a) at least one platinum group element, consisting of a catalyst component comprising by supporting and (b) gold. The inner layer of the third catalyst structure is preferably formed such that the platinum group element is highly dispersed and supported on the above-described carrier by an ion exchange method, and then gold is further added thereto. It can be obtained by supporting by an ion exchange method, or by supporting colloidal gold hydroxide or the like with high dispersion. According to the invention, it is preferred that the inner layer thus formed is subsequently further reduced with hydrogen or the like.

In the inner layer of the third catalyst structure according to the present invention, the ratio of gold to the platinum group element is in the range of 0.0001 to 0.1 part by weight of gold with respect to 100 parts by weight of the platinum group element. And preferably in the range of 0.001 to 0.01 parts by weight. According to the inner layer having the platinum group element and gold in such a ratio, the platinum group element regulates the adsorption and activation of hydrocarbons and nitrogen oxides, and the gold regulates the adsorption and activation of hydrocarbons. Since each site functions as a regulating site and the reaction proceeds selectively, the catalytic reduction reaction of nitrogen oxides using hydrocarbons as a reducing agent is considered to have high activity and selectivity over a wide temperature range. Can be

In the third catalyst structure, when such an active component is supported on the above-described carrier to form an inner layer, the loading is usually 0.1 to 10% by weight. When the loading of the active ingredient is less than 0.1% by weight, sufficient catalytic activity cannot be obtained. On the other hand, even when the loading exceeds 10% by weight, a corresponding increase in catalyst activity is obtained. Can not.

In the inner layer of such a third catalyst structure according to the present invention, the platinum complex ions and the ions of the other platinum group elements are ion-exchange groups (for example, alumina If it is a hydrogen ion, if it is a zeolite, it is ion-exchanged with an alkali metal ion in many cases), and thus the platinum group element such as platinum is highly dispersed and supported, and furthermore, By highly dispersing and supporting gold on the carrier, the oxidizing action of the platinum group element in the catalyst layer can be appropriately adjusted, and thus the internal layer is considered to have high activity and selectivity. .

Further, the fourth catalyst structure according to the present invention comprises:
The inner layers are aluminum oxide, titanium dioxide,
At least one selected from ruconium and H-type zeolite
One type of carrier includes (a) the platinum group element , (b) gold , and (c) at least one type of metal oxide selected from the group consisting of cerium oxide, lanthanum oxide, neodymium oxide, germanium oxide, and gallium oxide. It consists catalyst component comprising by supporting the object.

The inner layer of the fourth catalyst structure is preferably formed by supporting the metal oxide on a carrier as described above by an impregnation method or a deposition method, and then by an ion exchange method. The platinum group element is highly dispersed and supported,
Further, thereafter, gold can be supported by ion exchange, or colloidal gold hydroxide or the like can be highly dispersed and supported. According to the present invention, it is preferable that the inner layer thus obtained is thereafter subjected to a reduction treatment with hydrogen or the like.

In such an inner layer of the fourth catalyst structure, the ratio of gold to the platinum group element is the same as described above. In the inner layer of the fourth catalyst structure, the ratio of the metal oxide such as cerium oxide, lanthanum oxide, neodymium oxide, germanium oxide or gallium oxide to the platinum group element is 100 parts by weight of the platinum group element. Thus, the content of the metal oxide is in the range of 100 to 100,000 parts by weight, preferably in the range of 1,000 to 10,000 parts by weight. According to the inner layer having a platinum group element and a metal oxide together with gold at such a ratio, the platinum group element and the metal oxide serve as sites for activating adsorption of hydrocarbons and / or nitrogen oxides, and Since gold functions as sites for controlling the adsorption activation of hydrocarbons, and the reaction proceeds selectively, in a catalytic reduction reaction of nitrogen oxides using hydrocarbons as a reducing agent, in a wide temperature range,
It appears to have high activity and selectivity.

Further, according to the present invention, when such an active ingredient is supported on a carrier as described above, the supporting rate is as follows:
Usually, it is 0.1 to 10% by weight. In the present invention, when the loading of the active ingredient is less than 0.1% by weight, sufficient catalytic activity cannot be obtained. On the other hand, even when the loading exceeds 10% by weight, the catalytic activity corresponding to the loading exceeds 10% by weight. No increase can be obtained. However, if necessary, the loading rate is 10% by weight.
In addition, the catalytically active component may be supported on a carrier.

In the inner layer of the fourth catalyst structure according to the present invention, the ion exchange groups (often hydroxyl groups) of the metal oxide prepared in advance and the platinum complex ions, iridium ions, rhodium ions, palladium ions and ruthenium Ion exchange with at least one ion selected from the group consisting of ions, whereby the platinum group elements are highly dispersed on these oxides, and the metal oxides and the platinum group elements are synergized with the metal oxides. By further dispersing and supporting gold on the oxide, the oxidizing action of the platinum group element in the inner layer can be appropriately adjusted, thus having high activity and selectivity. It seems to be something.

In the nitrogen oxide catalytic reduction catalyst structure having a multilayer structure according to the present invention, in order to obtain effective nitrogen oxide catalytic reduction activity, the thickness of the surface layer is preferably 5 μm or more. The activity increases with the increase.
In particular, according to the invention, the thickness of the surface layer is between 20 and 100
It is in the range of μm. On the other hand, the thickness of the inner layer is 5 μm or more, and preferably in the range of 10 to 50 μm. Even if the thickness of the inner layer exceeds 50 μm, there is no particular problem,
The layer having a thickness of more than 50 μm is too deep inside the carrier and hardly comes into contact with the reaction gas, and does not function effectively as a catalyst.

The catalyst structure for catalytic reduction of nitrogen oxides according to the present invention has a two-layer structure as described above, and has high activity and selectivity. The reason is not clear in detail yet, but the surface layer where the reaction gas first comes into contact with the catalyst mainly activates adsorption without completely oxidizing hydrocarbons as a reducing agent, while the surface layer of this surface layer Since the inner layer on the inner side mainly activates the adsorption of nitrogen oxides, the reactivity between the surface layer and the inner layer is significantly increased, and as a result, the activated hydrocarbons or Oxygenated compounds produced from such hydrocarbons,
Since the activated nitrogen oxide reacts, it is considered that the nitrogen oxide is reduced with high activity and high selectivity.

As described above, the catalyst structure according to the present invention can have various shapes such as a honeycomb shape, a pellet shape, and a spherical shape. When molding or manufacturing such a structure, a molding aid, a molded body reinforcing body, an inorganic fiber, an organic binder, or the like may be appropriately used. In the catalytic reduction of nitrogen oxides using the catalyst structure according to the present invention, as the reducing agent comprising a hydrocarbon, for example, as a gaseous one,
Hydrocarbon gas such as methane, ethane, propane, propylene, butylene, etc., as liquids, single component hydrocarbons such as pentane, hexane, octane, heptane, benzene, toluene, xylene, gasoline, kerosene, light oil,
Mineral oil-based hydrocarbons such as heavy oil can be used. In particular, according to the present invention, among the above, acetylene,
Methylacetylene, lower alkynes such as 1-butyne, ethylene, propylene, isobutylene, 1-butene, lower alkenes such as 2-butene, butadiene, lower dienes such as isoprene, propane, lower alkanes such as butane and the like are preferable as the reducing agent. Used. These hydrocarbons may be used alone or in combination of two or more as needed.

The hydrocarbon as the reducing agent varies depending on the specific hydrocarbon to be used, but is usually used in a molar ratio to nitrogen oxide within a range of about 0.1 to 2. If the amount of hydrocarbon used is less than 0.1 in terms of molar ratio to nitrogen oxides, sufficient reducing activity cannot be obtained for nitrogen oxides. On the other hand, if the molar ratio exceeds 2, Since a large amount of unreacted hydrocarbons is emitted, a post-treatment for recovering the nitrogen oxides after the catalytic reduction treatment of the nitrogen oxides 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, it can be said that the catalyst structure according to the present invention is also useful as a catalyst for reducing or removing hydrocarbons and particulates 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 alkyne <alkene <aromatic hydrocarbon <alkane. In addition, in hydrocarbons of the same system, the temperature decreases as the number of carbon atoms increases. The optimum temperature at which the catalyst structure according to the present invention exhibits a reducing activity on nitrogen oxides varies depending on the reducing agent and the catalyst component used, but is usually 100 to 800 ° C. In this temperature range, the space velocity (SV) 500
It is preferable to distribute exhaust gas at about 100,000. A particularly preferable temperature range in the present invention is 200 to 50.
0 ° C.

[0038]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. (1) Preparation of catalyst structure Example 1 Tetraammineplatinum (II) chloride (Pt (NH ₃ ) ₄ Cl ₂ )
· A H ₂ O) 1.08 g was dissolved in deionized water 50 ml, to prepare an aqueous solution of [Pt (NH _{3) 4]} ²⁺ ions.
This was previously dried at 120 ° C. for 24 hours.
-Pellet of alumina (NK-324 manufactured by Sumitomo Chemical) 10
The mixture was added to 200 ml of water containing 0 ml (60 g) with sufficient stirring to exchange the [Pt (NH ₃ ) ₄ ] ²⁺ ion with the hydrogen ion in alumina. During this period, as the pH dropped, 0.2% by weight of aqueous ammonia was added to maintain the pH at 5.5. In this manner, a predetermined amount of the aqueous solution of tetraammineplatinum (II) chloride was added to the water containing the γ-alumina pellet, and the mixture was stirred at 70 ° C. for 2 hours.

[Pt (NH)
₃ ) ₄ ] The pellet of γ-alumina ion-exchanged with ²⁺ ions was filtered, washed with a nitric acid aqueous solution of pH 5.5, and washed with water.
After drying at 18 ° C. for 18 hours, baking was performed at 500 ° C. for 4 hours to obtain γ-alumina supporting 1% by weight of platinum. The thickness of the platinum layer thus supported on the γ-alumina was determined by line analysis of silica using an electron probe microanalyzer, and as a result, it was about 20 μm.

Separately, lanthanum nitrate (La (NO ₃ ) _3.
7.8 g of 6H ₂ O) was dissolved in 5 liters of ion-exchanged water to prepare an aqueous solution having a pH of 6.0. At a temperature of 70 ° C., 500 g of sodium-type ZSM-5 (manufactured by Nippon Mobil Co., SiO ₂ / Al ₂ O ₃ molar ratio: 34) was charged into the aqueous solution of lanthanum nitrate, and lanthanum was added to ZSM-5 at a loading of 0.5% by weight. Ions (La ³⁺ ) were carried by ion exchange. The ZSM-5 supporting the lanthanum ion was pulverized by a sample mill to obtain a powder whose particle size was adjusted to 100 mesh and 150 mesh.

The pellet of γ-alumina loaded with platinum was charged into a tumbling granulator, and further, the above powder and 10 times dilution water of silica gel (Snowtex N manufactured by Nissan Chemical Industries Ltd.) used as a binder were charged. The surface of the γ-alumina pellet was coated with ZSM-5 carrying the lanthanum ion. At this time, the thickness of the coating layer was examined by a line analysis of silica using an electron probe microanalyzer, and adjusted so as to have an average of 5 μm. Thus, a platinum support having lanthanum ion-exchanged H-type ZSM-5 as a coating on the surface was used. γ-alumina was obtained as catalyst structure A-1.

Example 2 In the same manner as in Example 1, the thickness of the coating layer was about 20 μm.
Thus, platinum-supported γ-alumina having m of lanthanum ion-exchanged H-type ZSM-5 as a coating on the surface was obtained as catalyst structure A-2.

Example 3 In the same manner as in Example 1, the thickness of the coating layer was about 50 μm.
Thus, platinum-supported γ-alumina having m of lanthanum ion-exchanged H-type ZSM-5 as a coating on the surface was obtained as catalyst structure A-3.

Example 4 In the same manner as in Example 1, the thickness of the coating layer was about 100
Platinum-supported γ-alumina having μm lanthanum ion exchange H-type ZSM-5 as a coating on the surface was obtained as a catalyst structure A-4.

Example 5 In the same manner as in Example 1, the thickness of the coating layer was about 200
A platinum-supported γ-alumina having μm lanthanum ion-exchanged H-type ZSM-5 as a coating on the surface was obtained as a catalyst structure A-5.

Example 6 In the same manner as in Example 1, γ-alumina loaded with platinum at a loading of 1% by weight was prepared. Cerium nitrate (Ce
(NO ₃₎ the ₃ · 6H ₂ O) _1425g was dissolved in deionized water for 5 liters. 500 g of γ-alumina (GB manufactured by Mizusawa Chemical Industry Co., Ltd.) was added thereto, and after sufficiently stirring, the γ-alumina was filtered, dried, calcined at 500 ° C. for 3 hours, and the cerium oxide carrying ratio was measured. Γ-alumina supported at 10% by weight was obtained. This γ-alumina was pulverized with a sample mill to obtain a powder whose particle size was adjusted below 100 mesh and above 150 mesh. Thereafter, in the same manner as in Example 1, a catalyst structure A-6 made of platinum-supported γ-alumina coated on the surface with cerium oxide-supported γ-alumina having an average coating layer thickness of about 50 μm was obtained.

Example 7 In the same manner as in Example 1, γ-alumina loaded with platinum at a loading of 1% by weight was prepared. On the other hand, 500 g of sodium mordenite (NM-100P manufactured by Nippon Chemical Co., Ltd.) was immersed in an aqueous solution of zirconyl nitrate (concentration of 100 g / l as ZrO ₂ ), and kept at 70 ° C. for 1 hour with stirring.
Sodium ions were exchanged with zirconium ions (Zr ⁴⁺ ). The zeolite cake obtained by filtration and washing was dried, and then calcined at 650 ° C. for 4 hours.

The zeolite (zirconium mordenite) had a zirconium content of 3.3% by weight and a specific surface area of 39 m ² / g. This zirconium mordenite was pulverized by a sample mill to obtain a powder whose particle size was adjusted to 100 meshes and 150 meshes. Less than,
In the same manner as in Example 1, a catalyst structure A-7 made of platinum-supported γ-alumina coated on the surface with zirconium ion-exchange mordenite having a coating layer thickness of about 50 μm on average was obtained.

Example 8 28.5 g of cerium nitrate (Ce (NO ₃ ) ₃ .6H ₂ O) was dissolved in 100 ml of ion-exchanged water. 120
100 ml (60 g) of a 3 mm diameter γ-alumina pellet (Sumitomo Chemical's N4-324) dried at 24 ° C. for 24 hours and left for 30 minutes to remove the cerium nitrate solution from γ
-Fully impregnated into the pores of the alumina. Then, γ-
After removing the alumina pellet from the aqueous solution and removing the excess aqueous solution attached to the surface of the pellet, γ-
Alumina pellets in 300 ml of 6% by weight ammonia water
And left for 1 hour to neutralize and hydrolyze cerium nitrate in the pores of γ-alumina.

Next, the thus obtained γ-alumina supporting cerium ion (Ce ³⁺ ) was sufficiently washed with ion-exchanged water, and calcined at 500 ° C. for 3 hours.
A pellet of γ-alumina carrying cerium oxide at a loading of 10% by weight was obtained. The pellet of γ-alumina supporting cerium oxide was put into 250 ml of ion-exchanged water. At this time, the pH was 7.1. This is 1/1
The pH was adjusted to 5.5 by adding 0 N nitric acid.

Separately, tetraammineplatinum (II) chloride (P
1.08 g of t (NH ₃ ) ₄ Cl ₂ .H ₂ O) was dissolved in 50 ml of ion-exchanged water to prepare an aqueous solution of [Pt (NH ₃ ) ₄ ] ²⁺ ion-exchange, which was loaded with the cerium oxide. [Pt (NH ₃ ) ₄ ] ²⁺ was exchanged with hydrogen ions in alumina or cerium oxide by adding to the aqueous solution containing the pellet of γ-alumina under sufficient stirring. During this period, 2% by weight of aqueous ammonia was added to the mixture to adjust the pH to 5.
Maintained at 5. After adding a predetermined amount of aqueous solution of tetraammineplatinum (II) chloride in this way, the mixture was stirred at 70 ° C. for 2 hours.

Next, the cerium oxide-supported γ-alumina pellet thus ion-exchanged was filtered to obtain a pH 5.
5 was dried at 120 ° C. for 18 hours, calcined at 500 ° C. for 4 hours, and further reduced at 400 ° C. for 1 hour in a mixed gas stream of nitrogen / hydrogen (volume ratio: 4/1). did. The catalyst thus obtained was obtained by supporting 10% by weight of cerium oxide and 1% by weight of platinum on γ-alumina. On the other hand, Na _x [(AlO ₂ ) _x
(SiO ₂ ) _y ] · Sodium type ZSM-5 represented by ZH ₂ O (manufactured by Nippon Mobile Co., Ltd., Y / X = 35) 500
g was immersed in 5 liters of a 0.025 mol / l aqueous solution of titanium sulfate and thoroughly stirred.

While stirring this in an autoclave, the temperature was raised at a rate of 100 ° C./hour, kept at 125 ° C. for 1 hour, and the titanium sulfate aqueous solution was hydrolyzed to convert sodium ions into titanium ions (Ti). After ion exchange with ⁴⁺ ), the ^mixture was filtered and washed with water to obtain a zeolite cake. After drying this cake, it was calcined at 650 ° C. for 4 hours to obtain zeolite. The titanium content in this zeolite is T
It was 2.4% by weight as iO ₂ . This was pulverized with a sample mill to obtain a powder whose particle size was adjusted to 100 mesh and 150 mesh. Thereafter, in the same manner as in Example 1, a catalyst structure A-8 comprising platinum and cerium oxide-supported γ-alumina coated with titanium ions ZSM-5 on the surface and having a coating layer thickness of about 50 μm on average was obtained.

Example 9 Neodymium nitrate (Nd (NO ₃ ) ₃ .6H ₂ O) 234.5 g
Was dissolved in 5 liters of ion-exchanged water. Thereafter, in the same manner as in Example 8, a pellet of γ-alumina carrying neodymium oxide at a carrying ratio of 30% by weight was obtained. This was put into 250 ml of ion-exchanged water. The pH at this time was 7.5. 1 / 10N nitric acid was added thereto to adjust the pH to 5.5. Hereinafter, in the same manner as in Example 4, a catalyst in which 30% by weight of neodymium oxide and 2% by weight of platinum were supported on γ-alumina was obtained.

Separately, germanium tetrachloride (GeCl ₄ )
500 g was dissolved in 1050 ml of ethanol. 600 g of titanium oxide having a specific surface area of 115 m ² / g and a sulfuric acid content of 2.7%, obtained by calcining metatitanic acid (TiO ₂ · H ₂ O) at 500 ° C., were added thereto, and then gradually ion-exchanged water was added. Was added to hydrolyze germanium tetrachloride. After this,
The solid content was filtered, dried and calcined at 300 ° C. for 3 hours to obtain titanium oxide supporting germanium oxide at a supporting ratio of 20% by weight. Hereinafter, in the same manner as in Example 8, a catalyst structure A-9 composed of platinum and neodymium oxide-supported γ-alumina coated with germanium oxide-supported titanium oxide having an average coating layer thickness of about 50 μm on the surface was used.
I got

Example 10 59.6 g of gallium nitrate (Ga (NO ₃ ) ₃ .nH ₂ O, 18.9% by weight as Ga) was dissolved in 100 ml of ion-exchanged water. A pellet of γ-alumina having a diameter of 3 mm previously dried at 120 ° C. for 24 hours (NK-32 manufactured by Sumitomo Chemical Co., Ltd.)
4) Add 100ml (60g), leave for 30 minutes,
The gallium nitrate aqueous solution was sufficiently impregnated in the pores of γ-alumina. Next, the pellet of γ-alumina is taken out from the aqueous solution, and the excess aqueous solution attached to the surface of the pellet is removed. Then, the pellet of γ-alumina is poured into 200 ml of 6% by weight ammonia water, and left for 1 hour. Gallium nitrate was neutralized and hydrolyzed in the pores of γ-alumina.

Next, the gamma-alumina thus loaded with gallium ions (Ga ⁴⁺ ) was sufficiently washed with ion-exchanged water, and calcined at 500 ° C. for 3 hours.
A pellet of γ-alumina supporting gallium oxide at a supporting rate of 10% by weight was obtained. The pellet of gamma-alumina supporting gallium oxide was put into 250 ml of ion-exchanged water. At this time, the pH was 7.1. This is 1/1
The pH was adjusted to 5.5 by adding 0 N nitric acid.

Separately, tetraammineplatinum chloride (II)
1.08 g of [[Pt (NH ₃ ) ₄ ] Cl ₂ .H ₂ O) was dissolved in 50 ml of ion-exchanged water to prepare an aqueous solution of [Pt (NH ₃ ) ₄ ] ²⁺ ion-exchange, which was then oxidized. [Pt (NH ₃ ) ₄ ] ²⁺ was exchanged with an aqueous solution containing a pellet of γ-alumina supporting gallium under sufficient stirring to exchange hydrogen ions in alumina or gallium oxide. During this period, 2% by weight of aqueous ammonia was added to keep the pH at 5.5 as the pH dropped. In this way, a predetermined amount of the aqueous solution of tetraammineplatinum (II) chloride was added to the aqueous solution containing the gallium oxide-supported γ-alumina pellet, followed by stirring at 70 ° C. for 2 hours.

Next, the gallium oxide-supported γ-alumina pellet thus ion-exchanged was filtered to obtain a pH 5.
5 was dried at 120 ° C. for 18 hours, calcined at 500 ° C. for 4 hours, and further reduced at 400 ° C. for 1 hour in a mixed gas stream of nitrogen / hydrogen (volume ratio: 4/1). did. The catalyst obtained in this manner was one in which 10% by weight of gallium oxide and 1% by weight of platinum were supported on γ-alumina.

Separately, gallium nitrate (Ga (NO ₃ ) ₃ .n
118 g of H ₂ O and Ga (18.9% by weight) was dissolved in 1 liter of ion-exchanged water. 70 ° C., pH 2.5 containing 700 g of H-type mordenite (HM-23 manufactured by Nippon Chemical)
The aqueous solution of gallium nitrate was added to the slurry adjusted to the above under sufficient stirring to effect ion exchange. During this period, 2% by weight of aqueous ammonia was added to the mixture to adjust the pH to 2.
Maintained at 5. After adding a predetermined amount of gallium nitrate aqueous solution in this way, the mixture was stirred for 2 hours.

Next, the gallium ion-exchanged mordenite thus ion-exchanged is filtered, washed with ion-exchanged water, dried at 120 ° C. for 18 hours, and then dried.
It was baked at 0 ° C. for 5 hours. In this way, mordenite supporting 5% by weight of gallium ions was obtained. Less than,
In the same manner as in Example 8, a catalyst structure A-10 comprising platinum and gallium oxide-supported γ-alumina coated with gallium ion-exchanged H-type mordenite having a coating layer thickness of about 50 μm on average was obtained.

Example 11 In the same manner as in Example 1, γ-
Alumina was prepared. Separately, chloroauric acid aqueous solution (as gold
0.126 g / l) 47.6 ml was added to ion-exchanged water 100 ml, and the above-mentioned platinum-supported γ-alumina was added thereto with sufficient stirring, and γ-alumina was impregnated with a chloroauric acid aqueous solution. Gold chloride ions were supported on γ-alumina by ion exchange. Next, the γ-alumina was filtered, washed with ion-exchanged water, dried at 120 ° C. for 18 hours, calcined at 500 ° C. for 4 hours, and then nitrogen / hydrogen (volume ratio 4/1). ) Reduction treatment was performed at 400 ° C for 1 hour in a mixed gas stream.

In this way, a catalyst in which 1% by weight of platinum and 0.01% by weight of gold were supported on γ-alumina was obtained. 200 ml of an ethanol solution of niobium pentachloride (NbCl ₅ ) (15 g / l as Nb) was gradually added to 500 g of commercially available zirconium hydroxide (manufactured by Daiichi Rare Element Co., Ltd.), and the mixture was sufficiently kneaded. The obtained kneaded material was air-dried, dried at 100 ° C. for 18 hours, and calcined at 500 ° C. for 3 hours.
Zirconium oxide carrying 10% by weight of niobium oxide (Nb ₂ O ₅ ) as Nb was obtained. Thereafter, in the same manner as in Example 8, a catalyst structure A-11 composed of platinum and gold-supported γ-alumina having a coating layer thickness of about 50 μm on average coated with niobium oxide-supported zirconia on the surface was obtained.

Example 12 A solution of ruthenium ion (Ru ³⁺ ) was prepared by dissolving 2.46 g of ruthenium chloride (RuCl ₃ ) in 0.1 N hydrochloric acid, and the same γ-alumina pellet as in Example 1 was prepared. The ruthenium ions were exchanged with the hydrogen ions in the alumina by adding to the contained water with sufficient stirring. During this period, 2% by weight of aqueous ammonia was added as the pH decreased, and the pH was adjusted to 3.
It was kept at zero. After adding a predetermined amount of an aqueous solution of ruthenium chloride in hydrochloric acid, the mixture was stirred at 70 ° C. for 2 hours.

Thereafter, in the same manner as in Example 1, a catalyst in which 2% by weight of ruthenium was supported on γ-alumina was obtained. Separately, 50 g of γ-alumina powder (A-11 manufactured by Sumitomo Chemical Co., Ltd.)
Was poured into 100 ml of ion-exchanged water, and 50 ml of an aqueous solution of niobium pentachloride in hydrochloric acid (4.1 g as NbCl ₅ ) was further added thereto.
Was added and heated to boiling for hydrolysis. The solid content was washed with ion-exchanged water and calcined at 500 ° C. for 4 hours to obtain a metal oxide mixture powder having a Nb ₂ O ₅ / 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% by weight aqueous ammonia was added thereto to adjust the pH to 6.0. Under sufficient stirring, nickel ion (N) obtained by dissolving 1.24 g of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) in 50 ml of ion-exchanged water.
i ²⁺ ) aqueous solution was added and nickel ion exchange was performed.
During this time, 2% by weight of aqueous ammonia was added to maintain the pH at a predetermined value. After adding a predetermined amount of the nickel ion aqueous solution in this way, stirring was further continued for 2 hours.

[0067] Thereafter, in the same manner as in Example 1, Nb ₂ O ₅ -A obtained by supporting nickel ions by loading of 5 wt%
1 ₂ O ₃ catalyst powder was obtained. Hereinafter, in the same manner as in Example 8, a catalyst structure A-12 made of ruthenium-supported γ-alumina coated on the surface with nickel ion-supported Nb ₂ O ₅ —Al ₂ O ₃ having a coating layer thickness of about 50 μm on average was prepared. Obtained.

Example 13 In the same manner as in Example 8, γ-
98 g of an alumina pellet was obtained. Rhodium chloride (Rh
Cl ₃ .nH ₂ O, 37.24% by weight as Rh) 5.37
g was dissolved in 50 ml of ion-exchanged water to prepare an ion-exchanged aqueous solution of rhodium ion (Rh ³⁺ ), and this was added to an aqueous solution containing a γ-alumina pellet carrying lanthanum oxide under sufficient stirring. In addition, rhodium ions were exchanged with hydrogen ions in alumina or lanthanum oxide. During this period, 2% by weight of aqueous ammonia was added to keep the pH at 5.5 as the pH dropped. After adding the predetermined aqueous solution of rhodium chloride in this way, the mixture was stirred at 70 ° C. for 2 hours.

Thereafter, as in Example 8, γ-alumina supported 30% by weight of lanthanum oxide and 2% by weight of rhodium. Thereafter, in the same manner as in Example 8, γ-alumina contained 30% by weight of lanthanum oxide, 2% by weight of rhodium and gold.
A catalyst supported by 0.005% by weight was obtained. Thereafter, in the same manner as in Example 1, the coating layer thickness was about 50 μm on average.
Thus, a catalyst structure A-13 composed of rhodium and gold-supported γ-alumina coated on the surface with lanthanum ion-exchanged H-type ZSM-5 of m was obtained.

Example 14 1.81 g of gallium nitrate (Ga (NO ₃ ) ₃ .nH ₂ O, 18.9% by weight as Ga) was dissolved in 100 ml of ion-exchanged water. H-type mordenite (HM-23 manufactured by Nippon Chemical)
Containing 100 ml (70 g) of a 3 mm diameter pellet
The aqueous solution of gallium nitrate was added to the slurry adjusted to pH 2.5 and pH 2.5 under sufficient stirring to effect ion exchange. During this period, 2% by weight of aqueous ammonia was added to keep the pH at 2.5 as the pH dropped. After adding a predetermined gallium nitrate aqueous solution in this way, the mixture was stirred for 2 hours.

Next, the gallium ion-exchanged mordenite thus ion-exchanged is filtered, washed with ion-exchanged water and dried at 120 ° C. for 18 hours.
It was baked at 0 ° C. for 5 hours. Thus, a mordenite pellet supporting 5% by weight of gallium ions was obtained. Separately, 5.32 g of iridium chloride (IrCl ₄ , 98.9% by weight as iridium chloride) was put into 100 ml of ion-exchanged water at 80 ° C. and dissolved. The mordenite pellets were put into this, and left for 30 minutes to sufficiently impregnate the pores of the mordenites. Then, the pellets were taken out of the solution, and the excess aqueous solution attached to the surface of the pellets was removed. The mixture was reduced with a 10% by weight aqueous solution of hydrazine, and dried at 120 ° C. for 18 hours. This was calcined at 500 ° C. for 3 hours to obtain gallium ion-exchanged mordenite supporting 2% by weight of iridium.

In the same manner as in Example 1, a catalyst structure A- made of iridium-supported gallium ion-exchanged mordenite coated on the surface with a lanthanum ion-exchanged H-type ZSM-5 having a coating layer thickness of about 50 μm on average.
14 was obtained.

Example 15 In the same manner as in Example 1, γ-
A pellet of alumina was prepared. Separately, commercially available calcium mordenite (Ca-M-100P, manufactured by Nippon Chemical Co., Ltd.) was pulverized with a sample mill to obtain a powder whose particle size was adjusted below 100 mesh and above 150 mesh. Hereinafter, Example 1
In the same manner as described above, C
The a-mordenite was coated to obtain a catalyst structure A-15 made of platinum-supported γ-alumina coated on the surface with Ca-mordenite having a coating layer thickness of about 50 μm on average.

Comparative Example 1 A sodium type ZSM-5 (SiO ₂ manufactured by Nippon Mobile Co., Ltd.)
/ Al ₂ O ₃ molar ratio = 34) by hydrogen substitution to form H-type ZS
M-5 was formed into a spherical body having a diameter of 2.4 mm using silica sol (Snowtex N manufactured by Nissan Chemical Industries, Ltd.) as a binder. This was dried at 120 ° C. for 18 hours, and then calcined at 500 ° C. for 4 hours to obtain a catalyst structure B-1.

[0075] Comparative Example 2 chloroplatinic acid _{(H 2 PtCl 6 · 6H 2} O) 1.59g was dissolved in deionized water 100 ml. 100 ml of the same γ-alumina as in Example 1 was added thereto, and left for 1 hour.
Excess solution was removed from γ-alumina. Then, γ-
After drying the alumina at 120 ° C. for 18 hours, 500 ° C.
For 4 hours, and further reduced at 400 ° C. for 1 hour in a mixed gas stream of nitrogen / hydrogen (4/1). Thus, the catalyst structure B- in which 1% by weight of platinum is supported on γ-alumina
2 was obtained.

Comparative Example 3 28.5 g of cerium nitrate (Ce (NO ₃ ) ₃ .6H ₂ O) was dissolved in 100 ml of ion-exchanged water. 120
100 ml (60 g) of 3 mm diameter γ-alumina pellets (NK-324, manufactured by Sumitomo Chemical Co., Ltd.) dried at 24 ° C. for 24 hours and left for 30 minutes to remove the cerium nitrate solution from γ
-Fully impregnated into the pores of the alumina. Then, γ-
After removing the alumina pellet from the above solution and removing the excess solution adhering to the surface of the pellet, the pellet of γ-alumina was poured into 200 ml of 6% by weight aqueous ammonia, and left for 1 hour. Cerium nitrate was neutralized and hydrolyzed in the pores.

Then, the thus obtained γ-alumina carrying cerium ions is sufficiently washed with ion-exchanged water and calcined at 500 ° C. for 3 hours to reduce the cerium oxide loading to 10% by weight. Thus, a pellet of γ-alumina supported was obtained. The pellet of γ-alumina supporting cerium oxide was put into 250 ml of ion-exchanged water.
At this time, the pH was 7.1. 1 / 10N nitric acid was added thereto to adjust the pH to 5.5.

Separately, tetraammineplatinum (II) chloride (P
1.08 g of t (NH ₃ ) ₄ Cl ₂ .H ₂ O) was dissolved in 50 ml of ion-exchanged water to prepare an aqueous solution of [Pt (NH ₃ ) ₄ ] ²⁺ ion-exchange, which was loaded with the cerium oxide. [Pt (NH ₃ ) ₄ ] ²⁺ was exchanged with hydrogen ions in alumina or cerium oxide by adding to the aqueous solution containing the pellet of γ-alumina under sufficient stirring. During this period, 2% by weight of aqueous ammonia was added to the mixture to adjust the pH to 5.
Maintained at 5. After adding a predetermined amount of aqueous solution of tetraammineplatinum (II) chloride in this way, the mixture was stirred at 70 ° C. for 2 hours.

Next, the cerium oxide-supported γ-alumina pellet thus ion-exchanged was filtered to obtain a pH 5.
5 was dried at 120 ° C. for 18 hours, calcined at 500 ° C. for 4 hours, and further reduced in a stream of nitrogen / hydrogen (volume ratio: 4/1) at 400 ° C. for 1 hour. Thus, a catalyst structure B-3 in which 10% by weight of cerium oxide and 1% by weight of platinum were supported on γ-alumina was obtained.

(2) Evaluation Test Using the above-described catalyst structures (A-1 to 18) of the present invention and the catalyst structures (B-1 to 3) of Comparative Examples under the following test conditions, nitrogen oxidation was carried out. Nitrogen oxide catalytic reduction of the substance-containing gas was performed, and the removal rate of nitrogen oxide was determined by a chemical luminescence method. (Test conditions) (1) Gas composition NO 500 ppm O ₂ 10% by volume Reducing agent 500 ppm Water 6% by volume Nitrogen balance (2) Space velocity 10,000 or 20000 Hr ^-1 (3) Reaction temperature 200 ° C., 250 ° C., 300 ° C. ,
350 ° C., 400 ° C. or 450 ° C. The results are shown in Tables 1 and 2.

[0081]

[Table 1]

[0082]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the catalyst structures according to the present invention all have high removal rates of nitrogen of nitrogen oxides, whereas the catalyst structures according to Comparative Examples have a high removal rate. Overall, the removal rate is low. The catalyst structure according to Comparative Example 1 is a conventionally known representative catalyst structure for catalytic reduction of nitrogen oxide composed of H-type ZSM-5, and generally has a low nitrogen oxide removal rate. .

Comparative Example 2 is a catalyst structure having a single layer structure in which platinum is supported on γ-alumina. On the contrary,
In Example 1, Z was prepared by supporting platinum on γ-alumina, using this as an internal layer, and supporting lanthanum ions thereon.
This is a catalyst structure having a two-layer structure in which an SM-5 coating layer is formed as a surface layer, and has an improved nitrogen oxide removal rate.

Comparative Example 3 is a catalyst structure having a single layer structure in which cerium oxide and platinum are supported on γ-alumina. On the other hand, in Example 8, γ-alumina supported cerium oxide and platinum, and this was used as an inner layer, on which a two-layer having a coating layer made of titanium ion-substituted ZSM-5 as a surface layer was used. The catalyst structure has a structure in which the nitrogen oxide removal rate of nitrogen oxides is improved.

[0086]

As described above, the catalyst structure for catalytic reduction of nitrogen oxides according to the present invention has a surface layer having a predetermined catalyst component, and has a predetermined catalyst component and is located inside the surface layer. It has a multi-layer structure with an inner layer, and has higher activity and higher selectivity than conventional catalyst structures in the catalytic reduction of nitrogen oxides using hydrocarbons as a reducing agent. Even under the above conditions, the nitrogen oxides in the exhaust gas can be efficiently catalytically reduced in a wide temperature range, and the durability is excellent.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B01J 23/56 ZABA (72) Inventor Tadao Nakatsuji 5-1-1 Ebishima-cho, Sakai-shi, Osaka Sakai Chemical (72) Inventor Hiromasa Shimizu 5-1-1 Ebisushimacho, Sakai City, Osaka Sakai Chemical Industry Co., Ltd. (72) Inventor Ritsu Yasukawa 5-1, Ebisshimacho, Sakai City, Osaka Address Sakai Chemical Industry Co., Ltd. Central Research Laboratory (72) Inventor Tomohiro Yoshinari 3-32-25-201, Motomachi, Urawa City, Saitama Prefecture (72) Inventor Fujio Suganuma 228-16 Shinjuku Shinjuku, Showa-cho, Kita-Katsushika-gun, Saitama Prefecture 72) Inventor Katsumi Miyamoto 1-11-17 Washinomiya, Washinomiya-cho, Kita-Katsushika-gun, Saitama (72) Inventor Tetsuhiko Ito Ichiban-Chome Ichiban-Chome, Tsukuba, Ibaraki Pref. Hideaki 1st place, Higashi 1-chome, Tsukuba City, Ibaraki Pref. Examiner, Institute of Chemical Technology, Tomoo Niida (56) References JP-A-5-168939 (JP, A) JP-A-5-228370 (JP, A) JP Hei 5-68888 (JP, A)

Claims (12)

(57) [Claims] 1. A nitrogen oxide having a two-layer structure comprising an inner layer having a catalyst component on a base material constituting a catalyst structure, and a surface layer carrying a catalyst component on the inner layer. Catalyst structure for catalytic reduction of oxides , the inner layer of which is aluminum oxide, titanium dioxide, zirconium oxide
At least one selected from the group consisting of lithium and H-type zeolite
, A catalyst component comprising at least one platinum group element selected from the group consisting of platinum, iridium, rhodium, palladium and ruthenium , wherein the surface layer is aluminum oxide, titanium dioxide, zirconium oxide and H type. At least one carrier selected from zeolites is provided with periodic table IIa, IIIa, IIIb, IVa, IVb, V
a, VIIa and VIII (excluding cobalt and nickel)
Good. At least one metal or its ion or nitrogen oxide catalytic reduction catalyst structure for the use of hydrocarbons, comprising the catalytic component composed by supporting as a reducing agent and the oxides of). 2. The nitrogen oxide according to claim 1, wherein the inner layer comprises a catalyst component in which a platinum group element is supported on a carrier, and the supporting rate is in the range of 0.1 to 10% by weight. Catalyst structure for catalytic reduction. 3. A nitrogen oxide having a two-layer structure comprising an inner layer having a catalyst component on a base material constituting a catalyst structure, and a surface layer carrying a catalyst component on the inner layer. Catalyst structure for catalytic reduction of oxides , the inner layer of which is aluminum oxide, titanium dioxide, zirconium oxide
At least one selected from the group consisting of lithium and H-type zeolite
The carrier consists of (a) platinum, iridium, rhodium, and at least one platinum group element selected from the group consisting of palladium and ruthenium, (b) cerium oxide, lanthanum oxide, neodymium oxide, germanium oxide and gallium oxide consists of at least one metal oxide and a catalyst component comprising by supporting a member selected from the group, the surface layer is aluminum oxide, titanium dioxide, at least one carrier selected from zirconium oxide and H-type zeolites, the periodic table IIa, IIIa, IIIb, IVa, IVb, V
a, VIIa and VIII (excluding cobalt and nickel)
Good. At least one metal or its ion or nitrogen oxide catalytic reduction catalyst structure for the use of hydrocarbons, comprising the catalytic component composed by supporting as a reducing agent and the oxides of). 4. The catalyst structure for catalytic reduction of nitrogen oxides according to claim 3, wherein the inner layer contains 0.1 to 100 parts by weight of a platinum group element with respect to 100 parts by weight of the metal oxide. 5. The internal layer consists of a catalyst component comprising by supporting a platinum group element and a metal oxide on a carrier, supporting ratio is 5 to 50
The catalyst structure for catalytic reduction of nitrogen oxides according to claim 4, wherein the amount is in the range of% by weight. 6. A nitrogen oxide having a two-layer structure comprising an inner layer having a catalyst component on a base material constituting a catalyst structure, and a surface layer carrying a catalyst component on the inner layer. Catalyst structure for catalytic reduction of oxides , the inner layer of which is aluminum oxide, titanium dioxide, zirconium oxide
At least one selected from the group consisting of lithium and H-type zeolite
A carrier, (a) platinum, iridium, rhodium, and at least one platinum group element selected from the group consisting of palladium and ruthenium, consists catalyst component composed by supporting and (b) a gold surface layer is oxidized At least one carrier selected from aluminum, titanium dioxide, zirconium oxide and H-type zeolite is provided with a periodic table IIa, IIIa, IIIb, IVa, IVb, V
a, VIIa and VIII (excluding cobalt and nickel)
Good. At least one metal or its ion or nitrogen oxide catalytic reduction catalyst structure for the use of hydrocarbons, comprising the catalytic component composed by supporting as a reducing agent and the oxides of). 7. The catalyst structure for catalytic reduction of nitrogen oxides according to claim 6, wherein the inner layer contains 0.0001 to 0.1 parts by weight of gold with respect to 100 parts by weight of the platinum group element. 8. inner layer and a platinum group element and gold supported on a carrier made from the catalyst component comprising, supported rate is 0.1 to 10 wt%
The catalyst structure for catalytic reduction of nitrogen oxide according to claim 7, wherein 9. A nitrogen oxide having a two-layer structure comprising an inner layer having a catalyst component on a base material constituting a catalyst structure, and a surface layer carrying a catalyst component on the inner layer. Catalyst structure for catalytic reduction of oxides , the inner layer of which is aluminum oxide, titanium dioxide, zirconium oxide
At least one selected from the group consisting of lithium and H-type zeolite
A carrier, (a) platinum, iridium, rhodium, and at least one platinum group element selected from the group consisting of palladium and ruthenium, and (b) gold, (c) cerium oxide, lanthanum oxide, neodymium oxide by supporting at least one metal oxide selected from germanium and the group consisting of gallium oxide consists catalyst component comprising, a surface layer is aluminum oxide, titanium dioxide, at least one selected from zirconium oxide and H-type zeolite On the carrier, the periodic table IIa, IIIa, IIIb, IVa, IVb, V
a, VIIa and VIII (excluding cobalt and nickel)
Good. At least one metal or its ion or nitrogen oxide catalytic reduction catalyst structure for the use of hydrocarbons, comprising the catalytic component composed by supporting as a reducing agent and the oxides of). 10. The internal layer contains 0.0001 to 0.1 parts by weight of gold based on 100 parts by weight of a platinum group element, and 100 to 100 parts by weight of a platinum group element.
The catalyst structure for catalytic reduction of nitrogen oxides according to claim 9, which has 000 parts by weight. 11. An inner layer comprising a catalyst component in which a platinum group element, gold and a metal oxide are supported on a carrier, and the loading rate is 0.1%.
2. The composition according to claim 1, wherein the content is in the range of 1 to 10% by weight.
0. The catalyst structure for catalytic reduction of nitrogen oxides according to 0. 12. The metal of Group IIa of the periodic table is Mg, Ca,
At least one element selected from Sr and Ba, at least one element selected from the group IIIa metal selected from Y and lanthanide group metals, at least one selected from the group IIIb metal selected from Ga and the group IVa metal selected from Ti and Zr. The group IVb metal is at least one selected from Ge and Sn; the group Va metal is at least one selected from V and Nb;
The catalyst structure for catalytic reduction of nitrogen oxides according to claim 1, wherein the metal of group a is Mn and the metal of group VIII is Fe .