JP3129348B2 - Exhaust gas treatment catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to nitrogen oxides (hereinafter referred to as NO
x), carbon monoxide (CO), hydrocarbons (hereinafter H
C) (hereinafter abbreviated as C).

[0002]

2. Description of the Related Art In the treatment of exhaust gas from automobiles and the like, purification is carried out by using a catalyst (composition: Pt, Rh / Al ₂ O ₃ ) commonly called a three-way catalyst utilizing CO and HC in the exhaust gas. However, NOx is purified only in a very narrow range near the stoichiometric air-fuel ratio. 2. Description of the Related Art In recent years, as global environmental problems have increased, there has been a strong demand for lower fuel consumption of automobiles, and a lean burn engine that burns at a stoichiometric air-fuel ratio or more has attracted attention as a key technology. However, taking into account the running performance and acceleration of the vehicle, the engine only in the lean region has many disadvantages, and it is actually necessary to perform combustion in both the vicinity of the stoichiometric air-fuel ratio (stoichio) and the lean region. Recently, regarding the purification of NOx in the lean region, a crystalline silicate catalyst containing cobalt or copper has been spotlighted as a catalyst having high performance.

[0003] These catalysts have sufficient performance in the early stage of the reaction, but have problems in durability.
Up to now, various types of crystalline silicates have been studied for improvement in durability. For example, in order to prevent desorption of aluminum which is a main constituent element of the crystalline silicate and to stabilize cobalt or copper, a group VIII element or a rare earth element is contained in the crystal lattice (Japanese Patent Laid-Open No. 3-165816). And alkaline earth metals (Japanese Patent Application No. 3-3191).
A method using a novel silicate to which 95) is added has been proposed. In addition, in order to prevent the penetration of steam that promotes the desorption of aluminum, the application of crystalline silicate with improved steam resistance by growing hydrophobic silicalite on the surface layer of crystalline silicate is being studied. (Japanese Patent Application No. 3-192829).

However, by using these catalysts, the durability in a lean atmosphere has been dramatically improved, but when accelerating at a high speed of 100 km / h, the gas temperature instantaneously rises to around 700 ° C. At this time, the gas composition at this time is a rich atmosphere in which a reducing agent such as hydrogen is excessively present. Under these conditions, the deterioration of the catalyst cannot be prevented even when the above-mentioned improved crystalline silicate is applied. Therefore, improvement of the durability of the catalyst in a high-temperature rich atmosphere is a major problem in practical use of these catalysts.

[0005] In view of the above technical level, the present invention prevents catalyst deterioration even in a rich atmosphere in which a reducing agent is excessively present,
Another object of the present invention is to provide a catalyst capable of efficiently treating exhaust gas even in a lean atmosphere or a rich atmosphere.

[0006]

In order to overcome the above-mentioned disadvantages of the conventional catalyst, the present inventors have proposed a method of reducing Co or Cu ion, which is an active metal of a Co / crystalline silicate catalyst or Cu / crystalline silicate catalyst. The present invention has been completed as a result of intensive studies on a catalyst for preventing the reduction of Co ions or oxides, Cu ions or oxides in a reducing atmosphere, based on the knowledge that it is necessary to suppress the reduction of Co.

That is, the present invention has the following (1 ) an X-ray diffraction pattern shown in Table 1, which is expressed as a molar ratio of oxide (1 ± 0.
8) R ₂ O · _{[aM 2 O 3 · bM'O · cAl} 2 O 3 ]
YSiO ₂ (wherein, R is an alkali metal ion and / or hydrogen ion, M is at least one or more selected from the group consisting of group VIII elements, rare earth elements, titanium, vanadium, chromium, niobium, antimony, and gallium) M ′ is an alkaline earth metal ion of magnesium, calcium, strontium, barium, a ≧ 0, 2
0>b> 0 , a + c = 1, 3000>y> 11) crystalline silicate having a chemical formula of cobalt and further titanium, zirconium, chromium, manganese, iron, lanthanum,
Zinc, aluminum, tin, nickel, magnesium,
An exhaust gas treatment catalyst comprising at least one metal selected from the group consisting of calcium, strontium and barium.

(2) The crystalline silicate according to (1) above, wherein the crystalline silicate synthesized in advance is used as a mother crystal, and Si having the same crystal structure as the mother crystal is formed on the outer surface of the mother crystal.
The exhaust gas treatment catalyst according to the above (1), wherein the catalyst is a layered composite crystalline silicate obtained by growing a crystalline silicate consisting of O and O.

(3) A group consisting of the crystalline silicate according to (1) above, further comprising copper, titanium, zirconium, chromium, manganese, iron, cobalt, zinc, aluminum, tin, nickel, magnesium, calcium, strontium and barium. An exhaust gas treatment catalyst comprising at least one metal selected from the group consisting of:

(4) The crystalline silicate according to (1) above, wherein the crystalline silicate synthesized in advance is used as a mother crystal, and the outer surface of the mother crystal has the same crystal structure as the mother crystal.
(3) The exhaust gas treatment catalyst according to the above (3), wherein the catalyst is a layered composite crystalline silicate obtained by growing a crystalline silicate consisting of O and O. It is.

[0011]

Normally, Co / crystalline silicate is used for NO
The purification reaction formula for purifying the exhaust gas containing x, CO, and HC is as follows.

[0012]

Embedded image

In the above reaction formula, (1) means activation of HC, (2) means combustion of HC, (3) means denitration reaction, and (4) means combustion of CO. Co / crystalline silicate By adding and coexisting at least one metal selected from the group consisting of titanium, zirconium, chromium, manganese, iron, lanthanum, zinc, aluminum, tin, nickel, magnesium, calcium, strontium and barium, / Titanium, zirconium, chromium, manganese, iron, cobalt, crystalline silicate
Zinc, aluminum, tin, nickel, magnesium,
By adding and coexisting at least one metal selected from the group consisting of calcium, strontium and barium, the denitration performance can be improved without changing the reaction rate constants of k ₁ , k ₂ , k ₃ and k _4. The effect of maintaining and suppressing the reduction of Co or Cu is exerted.

The crystalline silicate used in the present invention has an X-ray diffraction pattern shown in Table 1 below, and is expressed as a molar ratio of oxide (1 ± 1) in a dehydrated state.
0.8) R ₂ O · _{[aM 2 O 3 · bM'O · cAl} 2 O
₃ ] · ySiO ₂ (where R is an alkali metal ion and / or hydrogen ion, M is a group VIII element, a rare earth element,
At least one element ion selected from the group consisting of titanium, vanadium, chromium, niobium, antimony and gallium, M 'is an alkaline earth metal ion of magnesium, calcium, strontium, barium, a ≧
0, 20>b> 0 , a + c = 1, 3000>y> 11)
Having the following chemical formula:

[0015]

[Table 2]

A layered composite in which a crystalline silicate previously synthesized from the above crystalline silicate is used as a mother crystal, and a crystalline silicate made of Si and O having the same crystal structure as the mother crystal is grown on the outer surface of the mother crystal. Crystalline silicate may be used. Due to the hydrophobic action of the crystalline silicate composed of Si and O (referred to as silicalite) grown on the outer surface of the layered composite crystalline silicate, only H ₂ O hardly penetrates into the interior of the crystalline silicate, and the It has the effect of lowering the concentration of H ₂ O around the reaction active site, and has the effect of suppressing the demetallation effect. for that reason,
Even in a high-temperature steam atmosphere, deterioration of the catalyst is suppressed.

The catalyst of the present invention is obtained by adding Co to the above crystalline silicate.
Alternatively, a method of immersing in an aqueous solution of Cu and each metal salt and supporting metal ions by an ion exchange method, or supporting the metal ions by an impregnation method with an aqueous solution of a metal salt such as chloride, nitrate, sulfate, or the like may be used. Furthermore, a method is also possible in which after supporting Co or Cu, oxides and chlorides of each of the above metals are supplied in a gaseous state and supported.

[0018]

【Example】

(Example 1) 〇 (Synthesis of mother crystal 1) 5616 g of water glass No. 1 (SiO ₂ : 30%) was added to water 54
This solution was dissolved in 29 g, and this solution was designated as solution A. On the other hand, water 4
To 175 g, 718.9 g of aluminum sulfate,
Dissolve 110 g of iron, 47.2 g of calcium acetate, 262 g of sodium chloride, and 2020 g of concentrated hydrochloric acid. The solution A and the solution B are supplied at a constant rate to form a precipitate, and the mixture is sufficiently stirred to obtain a slurry having a pH of 8.0. This slurry was charged into a 20-liter autoclave, and 500 g of tetrapropylammonium bromide was further added. Hydrothermal synthesis was performed at 160 ° C. for 72 hours. After the synthesis, the resultant was washed with water and dried. Obtain silicate 1. The crystalline silicate 1 is represented by the following composition formula in terms of the molar ratio of the oxide (omitting the water of crystallization), and the crystal structure is shown in Table 1 by X-ray diffraction. 0.5Na ₂ O ・ 0.5H ₂ O ・
[0.8Al ₂ O ₃ .0.2Fe ₂ O ₃ .0.25Ca
O] · 25SiO ₂

〇 (Synthesis of Layered Composite Crystalline Silicate 1) Finely pulverized mother crystal 1 (crystalline silicate 1) 100
0 g was added to 2160 g of water, and 4590 g of colloidal silica (SiO ₂ : 20%) was further added, followed by sufficient stirring to obtain a solution a. On the other hand, 105.8 g of sodium hydroxide is dissolved in 2008 g of water to obtain a solution b. While the solution a is being stirred, the solution b is gradually added dropwise to form a precipitate to obtain a slurry. The slurry is placed in an autoclave, and a solution of 568 g of tetrapropylammonium bromide dissolved in 2106 g of water is added to the autoclave. 160 ° C in this autoclave,
Hydrothermal synthesis is performed for 72 hours (stirring at 200 rpm), and after stirring, washing and drying, baking is performed at 500 ° C. for 3 hours to obtain a layered composite crystalline silicate 1.

The layered composite crystalline silicate 1 was stirred at 40 ° C. in a 4N aqueous solution of NH ₄ Cl for 3 hours to carry out NH ₄ ion exchange. Washing after ion exchange, 100 ° C, 24
After drying for an hour, baking was performed at 400 ° C. for 3 hours to obtain an H-type layered composite crystalline silicate 1.

(Catalysis) Next, 3 parts of alumina sol, 55 parts of silica sol (SiO ₂ : 20%) and 200 parts of water were added to the above 100 parts of the H-type layered composite crystalline silicate 1 as a binder, The mixture was sufficiently stirred to obtain a wash coat slurry. Next, a cordierite monolith substrate (400 cell grids) was immersed in the slurry, taken out, and then sprayed with excess slurry and dried at 200 ° C. The coating amount is 200 g per 1 liter of the base material.

Next, a solution of cobalt chloride and zinc chloride in hydrochloric acid (CoCl ₂ .6H ₂ O: 26.8 g, ZnCl ₂ : 2)
After the honeycomb coated article 1 was immersed in 1.5 g / 200 cc HCl and impregnated for 1 hour, the liquid adhering to the substrate wall was wiped off and dried at 200 ° C. Next, a purge treatment was performed at 500 ° C. in a nitrogen atmosphere for 12 hours to obtain a honeycomb catalyst 1.

(Example 2) In the method of synthesizing the mother crystal 1 of Example 1, instead of ferric chloride, cobalt chloride, ruthenium chloride, rhodium chloride, lanthanum chloride, cerium chloride,
The same operation as that of the mother crystal 1 was repeated except that titanium chloride, vanadium chloride, chromium chloride, antimony chloride, gallium chloride and niobium chloride were each added in the same mole number as Fe ₂ O _{3 in} terms of oxide. 12 were prepared. The crystal structures of these mother crystals are shown in Table 1 by X-ray diffraction, and the composition is represented by a molar ratio of oxide (dehydrated form) of 0.5Na ₂ O · 0.5H _2. O ・
(0.2M ₂ O ₃ · 0.8Al ₂ O ₃ · 0.25Ca
O) · 25SiO ₂ . Where M is Co, Ru, R
h, La, Ce, Ti, V, Cr, Sb, Ga, and Nb.

Further, a mother crystal 13 was obtained in the same manner as that of the mother crystal 1 except that nothing was added instead of ferric chloride and calcium acetate.

These mother crystals 2 to 13 are finely pulverized, and the mother crystals 2 to 13 are used in place of the mother crystal 1 in the same manner as in the synthesis of the layered composite crystalline silicate 1 of Example 1, and the autoclave is used. As a result, the layered composite crystalline silicates 2 to 13 were obtained.

Using the layered composite crystalline silicates 2 to 13 described above, H-type layered composite crystalline silicates 2 to 13 were obtained in the same manner as in Example 1, and this silicate was further used in the same manner as in the preparation of the catalyst of Example 1. Was coated on the cordierite monolith substrate in the step of to obtain honeycomb coated articles 2 to 13.
Next, it was immersed in a solution of cobalt chloride or zinc chloride and treated with the same treatment as in Example 1 for honeycomb catalysts 2 to 13 (honeycomb catalysts).
Medium 13 was obtained as Reference Example) .

Further, only the mother crystal 1 is made of H
The resultant was molded into a mold, and further coated on a honeycomb substrate to obtain a honeycomb coated article 14. The coated product 14 was immersed in a solution of cobalt chloride and zinc chloride / hydrochloric acid in the same manner as in Example 1 to obtain a honeycomb catalyst 14.

(Example 3) In the method for synthesizing the mother crystal 1 of Example 1, magnesium acetate was used instead of calcium acetate.
Mother crystals 15 to 17 were prepared by repeating the same operation as for mother crystal 1 except that strontium acetate and barium acetate were each added in the same mole number as CaO in terms of oxide. The crystal structures of these mother crystals are shown in Table 1 by X-ray diffraction, and the composition is represented by a molar ratio of oxide (dehydrated form) of 0.5Na ₂ O · 0.5H _2. O ・
(0.2Fe ₂ O ₃ · 0.8Al ₂ O ₃ · 0.25Me
O) · 25SiO ₂ . Where Me is Mg, Sr,
Ba. These mother crystals 15 to 17 are finely pulverized,
Hydrothermal synthesis was performed using an autoclave in the same manner as in the synthesis of the layered composite crystalline silicate 1 of Example 1 to obtain layered composite crystalline silicates 15 to 17. Further, the silicates 15 to 17 were converted to H-type by the same method as in Example 1, and the honeycomb catalysts 15 to 1 were formed by the same method as in Example 1.
7 was obtained.

(Example 4) Honeycomb coated article 1 coated with H-type layered composite crystalline silicate 1 obtained in Example 1
Using cobalt chloride and aluminum chloride (CoCl
_{2 · 6H 2 O: 33g,} Al 2 O 3 · 6H 2 O: 18.
0g / H ₂ O200cc), titanium chloride and cobalt chloride _{(CoCl 2 · 6H 2 O:} 26.8g, TiCl 4: 2
2.5 g / HCl 200 cc), cobalt chloride and tin chloride (CoCl ₂ .6H ₂ O: 26.8 g, SnCl ₄ :
22g / HCl200cc), cobalt and chromium nitrate chloride _{(CoCl 2 · 6H 2 O:} 26.8g, Cr (N
O ₃ ) ₂ : 17.8 g / HCl 200 cc), cobalt chloride and zirconium tetrachloride (CoCl ₂ .6H ₂ O: 2)
6.8 g, ZrCl ₄ : 18 g / HCl 200 cc),
Cobalt chloride and lanthanum chloride (CoCl ₂ .6H ₂ O:
_{26.8g, LaCl 3 · 6H 2 O} : 34g / HCl2
00cc), cobalt chloride and manganese chloride (CoCl ₂
6H ₂ O: 26.8 g, MnCl ₂ : 20 g / HCl
200cc), cobalt and iron chloride (CoCl ₂ · 6
_{H 2 O: 26.8g, FeCl 3} · 6H 2 O: 22g /
HCl 200cc), cobalt chloride and nickel chloride (C
oCl ₂ .6H ₂ O: 33 g, NiCl ₂ .6H ₂ O:
24 g / ₂₀₀ cc of H ₂ O), cobalt chloride and calcium chloride (CoCl ₂ .6H ₂ O: 33 g, CaCl _2.
2H ₂ O: 20 g / H ₂ O ₂₀₀ cc), cobalt chloride and magnesium chloride (CoCl ₂ .6H ₂ O: 33 g,
MgCl ₂ .6H ₂ O: 35 g / H ₂ O ₂₀₀ cc),
Cobalt barium chloride (CoCl ₂ · 6H ₂ O:
33 g, BaCl ₂ · 2H ₂ O: 43 g / H ₂ O 200
cc) and cobalt chloride and strontium chloride (CoC
_{l 2 · 6H 2 O: 33g} , SrCl 2 · 6H 2 O: 40
g / H ₂ O ₂₀₀ cc).
Honeycomb catalysts 18 to 30 were obtained in the same manner as in the case of catalysis.

(Example 5) Using the layered composite crystalline silicate 1 of Example 1, 0.04M cobalt chloride and 0.04M
Ion exchange was performed by immersing in 4M calcium chloride aqueous solution at 30 ° C. and stirring. After washing and drying, a powder catalyst a was obtained.

Next, a honeycomb catalyst 31 was obtained by coating the above-mentioned powder catalyst a on a monolith substrate in the same manner as in the catalysis of Example 1.

(Comparative Example 1) An aqueous solution of cobalt chloride (CoCl ₂ .6H ₂ O) was added to the honeycomb coat 1 obtained in Example 1.
26.8 g / H ₂ O ₂₀₀ cc), and thereafter, a honeycomb catalyst 32 was obtained in the same manner as in Example 1.

The constitutions of the above-mentioned catalysts of the present invention, the catalysts of the reference example and the catalysts of the comparative examples are shown in Tables 2 and 3 below.

[0034]

[Table 3]

[0035]

[Table 4]

(Experimental Example 1) An activity evaluation test of the honeycomb catalysts 1-32 prepared in Examples 1, 2, 3, 4, 5 and Comparative Example 1 was performed. The activity evaluation conditions are as follows. 〇 (gas composition) NO: 400 ppm, CO: 1000 ppm, C
₂ H ₄ : 1000 ppm, C ₃ H ₆ : 340 ppm, O
_{2: 8%, CO 2:} 10%, H 2 O: 10%, remaining:
N ₂ , GHSV 30000h ⁻¹ , catalyst shape: 15 mm
× 15 mm × 60 mm (144 cells) Tables 4 and 5 show the denitration ratio of the catalyst in the initial state at a reaction temperature of 350 and 450 ° C.

(Experimental Example 2) A forced deterioration test was performed on the honeycomb catalysts 1 to 32 in a rich atmosphere (reducing atmosphere). The forced deterioration test is as follows. 〇 (gas composition) H ₂ : 3%, H ₂ O: 10%, balance: N ₂ GHSV: 5000 h ⁻¹ , temperature: 700 ° C., gas supply time: 6 hours Catalyst shape: 15 mm × 15 mm × 60 mm (144 cells) )

Catalysts 1 to 3 treated under the above forced deterioration conditions
2 was subjected to an activity evaluation test under the activity evaluation conditions of Experimental Example 1. Tables 4 and 5 show the denitration rates of the catalysts after the forced degradation test at reaction temperatures of 350 and 450 ° C. Table 4,
As shown in Table 5, it was confirmed that the catalysts of the present invention 1 to 12 and 14 to 31 maintained the activity of the catalyst high even in a reducing atmosphere.

[0039]

[Table 5]

[0040]

[Table 6]

Example 6 (Synthesis of mother crystal 1) 5616 g of water glass No. 1 (SiO ₂ : 30%) was added to water 54
This solution was dissolved in 29 g, and this solution was designated as solution A. On the other hand, water 4
In 175 g, 718.9 g of aluminum sulfate, 110 g of ferric chloride, 47.2 g of calcium acetate, 262 g of sodium chloride and 2020 g of concentrated hydrochloric acid are dissolved. The solution A and the solution B are supplied at a constant rate to form a precipitate, and the mixture is sufficiently stirred to obtain a slurry having a pH of 8.0. This slurry was charged into a 20-liter autoclave, and 500 g of tetrapropylammonium bromide was further added. Hydrothermal synthesis was performed at 160 ° C. for 72 hours. After the synthesis, the resultant was washed with water and dried. Obtain silicate 1. This crystalline silicate is represented by the following composition formula in terms of the molar ratio of the oxide (omitting the water of crystallization), and the crystal structure is shown in Table 1 by X-ray diffraction. 0.5NaO ₂ .0.5H ₂ O. [0.
8Al ₂ O ₃ .0.2Fe ₂ O ₃ .0.25CaO]
25SiO ₂

(Synthesis of Layered Composite Crystalline Silicate 1) Finely pulverized mother crystal 1 (crystalline silicate 1) 100
0 g was added to 2160 g of water, and 4590 g of colloidal silica (SiO ₂ : 20%) was further added, followed by sufficient stirring to obtain a solution a. On the other hand, 105.8 g of sodium hydroxide is dissolved in 2008 g of water to obtain a solution b. While the solution a is being stirred, the solution b is gradually added dropwise to form a precipitate to obtain a slurry. The slurry is placed in an autoclave, and a solution of 568 g of tetrapropylammonium bromide dissolved in 2106 g of water is added to the autoclave. 160 ° C in this autoclave,
Hydrothermal synthesis is performed for 72 hours (stirring at 200 rpm), and after stirring, washing and drying, baking is performed at 500 ° C. for 3 hours to obtain a layered composite crystalline silicate 1.

The layered composite crystalline silicate 1 was stirred at 40 ° C. in a 4N aqueous NH ₄ Cl solution for 3 hours to carry out NH ₄ ion exchange. Washing after ion exchange, 100 ° C, 24
After drying for an hour, baking was performed at 400 ° C. for 3 hours to obtain an H-type layered composite crystalline silicate 1.

(Catalysis) Next, 3 parts of alumina sol, 55 parts of silica sol (SiO ₂ : 20%) and 200 parts of water were added to the above 100 parts of the H-type layered composite crystalline silicate 1 as a binder. The mixture was sufficiently stirred to obtain a wash coat slurry. Next, a cordierite monolith substrate (400 cell grids) was immersed in the slurry, taken out, and then sprayed with excess slurry and dried at 200 ° C. The coating amount is 200 g per 1 liter of the base material.

Next, cuprous chloride and zinc chloride hydrochloric acid solution (C
uCl: 26.8 g, ZnCl ₂ : 21.5 g / 200
ccHCl), the honeycomb coated article 1 was immersed for 1 hour, and the liquid adhering to the substrate wall was wiped off at 200 ° C.
And dried. Next, purging was performed at 500 ° C. in a nitrogen atmosphere for 12 hours to obtain a honeycomb catalyst 1 ′.

(Example 7) In the method of synthesizing the mother crystal 1 of Example 6, instead of ferric chloride, cobalt chloride, ruthenium chloride, rhodium chloride, lanthanum chloride, cerium chloride, titanium chloride, vanadium chloride, chromium chloride, Mother crystals 2 to 12 were prepared by repeating the same operation as for mother crystal 1 except that antimony chloride, gallium chloride and niobium chloride were each added in the same mole number as Fe ₂ O _{3 in} terms of oxide. The crystal structure of these mother crystals is as shown in Table 1 by X-ray diffraction, and their composition is expressed as a molar ratio of oxide (dehydrated form) of 0.5N.
_{a 2 O · 0.5H 2 O ·} (0.2M 2 O 3 · 0.8Al
₂ O ₃ · 0.25CaO) · 25SiO ₂ . Where M is Co, Ru, Rh, La, Ce, Ti, V, C
r, Sb, Ga, is a N b.

Further, a mother crystal 13 was obtained in the same manner as that of the mother crystal 1 except that nothing was added instead of ferric chloride and calcium acetate.

The mother crystals 2 to 13 are finely pulverized, and the mother crystals 2 to 13 are used in place of the mother crystal 1 in the same manner as in the synthesis of the layered composite crystalline silicate 1 of Example 6, and the autoclave is used. As a result, the layered composite crystalline silicates 2 to 13 were obtained.

Using the above layered composite crystalline silicates 2 to 13, H-type layered composite crystalline silicates 2 to 13 were obtained in the same manner as in the catalysis of Example 6. This silicate was further coated on a cordierite monolith substrate in the same steps as in the preparation of the catalyst of Example 6 to form a honeycomb coated product 2 to 1
3 and then immersed in a cuprous chloride / phosphoric acid / hydrochloric acid solution,
Honeycomb catalysts 2 'to 13' were treated in the same manner as in Example 6.
(Honeycomb catalyst 13 'is a reference example) .

Further, only the mother crystal 1 was made H
The resultant was molded into a mold, and further coated on a honeycomb substrate to obtain a honeycomb coated article 14. The coated product 14 was immersed in a cuprous chloride / zinc chloride / hydrochloric acid solution in the same manner as in Example 6 to obtain a honeycomb catalyst 14 '.

(Example 8) In the method for synthesizing the mother crystal 1 of Example 6, magnesium acetate was used instead of calcium acetate.
Mother crystals 15 to 17 were prepared by repeating the same operation as for mother crystal 1 except that strontium acetate and barium acetate were each added in the same mole number as CaO in terms of oxide. The crystal structures of these mother crystals are shown in Table 1 by X-ray diffraction, and the composition is represented by a molar ratio of oxide (dehydrated form) of 0.5Na ₂ O · 0.5H _2. O ・
(0.2Fe ₂ O ₃ · 0.8Al ₂ O ₃ · 0.25Me
O) · 25SiO ₂ . Where Me is Mg, Sr,
Ba. These mother crystals 15 to 17 are finely pulverized,
Hydrothermal synthesis was performed using an autoclave in the same manner as in the synthesis of the layered composite crystalline silicate 1 of Example 6 to obtain layered composite crystalline silicates 15 to 17. Further, the silicates 15 to 17 were converted to H-type by the same method as in Example 6, and the honeycomb catalysts 15 'to 17 were formed by the same method as in Example 6.
17 'was obtained.

(Example 9) Honeycomb coated article 1 coated with H-type layered composite crystalline silicate 1 obtained in Example 6
Using cupric chloride and aluminum chloride (CuCl ₂
2H ₂ O: 33 g, AlCl ₃ .6H ₂ O: 18.0
g / H ₂ O ₂₀₀ cc), cuprous chloride and titanium chloride (C
uCl: 26.8 g, TiCl ₄ : 22.5 g / HCl
200cc), cuprous chloride and tin chloride (CuCl: 2)
6.8 g, SnCl ₄ : 22 g / HCl 200 cc),
Cuprous chloride and chromium nitrate @ CuCl: 26.8 g, Cr
(NO ₃ ) ₂ : 17.8 g / HCl 200 cc｝, cuprous chloride and zirconium tetrachloride (CuCl: 26.8 g,
ZrCl ₄ : 18 g / HCl 200 cc), cuprous chloride and cobalt chloride (CuCl: 26.8 g, CoCl _2.
6H ₂ O: 24 g / HCl 200 cc), cuprous chloride and manganese chloride (CuCl: 26.8 g, MnCl ₂ : 2)
0g / HCl 200cc), cuprous chloride and iron chloride (Cu
_{Cl: 26.8g, FeCl 3 · 6H} 2 O: 22g / H
Cl 200cc), cupric chloride and nickel chloride (CuC
_{l 2 · 2H 2 O: 33g} , NiCl · 6H 2 O: 24g
/ H ₂ O ₂₀₀ cc), cupric chloride and calcium chloride (CuCl ₂ .2H ₂ O: 33 g, CaCl ₂ .2H ₂
O: 20 g / H ₂ O ₂₀₀ cc), cupric chloride and magnesium chloride (CuCl ₂ .2H ₂ O: 33 g, MgCl _{2
2 · 6H 2 O: 35g /} H 2 O200cc), cupric barium chloride _{(CuCl 2 · 2H 2 O:} 33g, B
_{aCl 2 · 2H 2 O: 43g} / H 2 O200cc), cupric strontium chloride (CuCl ₂ · 2H
₂ O: 33 g, SrCl ₂ .6H ₂ O: 40 g / H ₂ O
200 cc) of each solution to obtain honeycomb catalysts 18 'to 30' in the same manner as in the catalysis of Example 1.

Example 10 Using the layered composite crystalline silicate 1 of Example 6, 0.04M copper acetate and 0.04M
Ion exchange was performed by immersing in a cobalt chloride aqueous solution at 30 ° C. and stirring. After washing and drying, a powder catalyst b was obtained.

Next, a monolith substrate was coated with the above-mentioned powder catalyst b in the same manner as in Example 6 to obtain a honeycomb catalyst 31 '.

Comparative Example 2 A cuprous chloride / hydrochloric acid solution (CuCl 26.8 g /
HCl 200 cc) to obtain a honeycomb catalyst 32 ′ in the same manner as in Example 1.

The constitutions of the above-mentioned catalysts of the present invention, catalysts of reference examples and comparative catalysts are summarized in Tables 6 and 7 below.

[0057]

[Table 7]

[0058]

[Table 8]

(Experimental Example 3) Examples 6, 7, 8, 9, 10
An activity evaluation test was performed on the honeycomb catalysts 1 'to 32' prepared in Comparative Example 2. The activity evaluation conditions are the same as those shown in Experimental Example 1. Tables 8 and 9 show the denitration rates of the catalyst in the initial state at the reaction temperatures of 350 and 450 ° C.

(Experimental Example 4) A forced deterioration test was performed on the honeycomb catalysts 1 'to 32' in a rich atmosphere (reducing atmosphere). The forced deterioration test is the same as in Experimental Example 2.

Catalysts 1 'to 3 treated under forced deterioration conditions
2 ′ was subjected to an activity evaluation test under the activity evaluation conditions of Experimental Example 1. Tables 8 and 9 show the denitration rates of the catalysts after the forced deterioration test at reaction temperatures of 350 and 450 ° C. As shown in Tables 8 and 9, the catalysts of the present invention 1 'to 12', 14 '
No. 31 ' confirmed that the activity of the catalyst was maintained high even in a reducing atmosphere.

[0062]

[Table 9]

[0063]

[Table 10]

[0064]

As described above, the exhaust gas treatment catalyst according to the present invention can be a stable catalyst with high durability, and can be used as a catalyst for purifying exhaust gas from lean burn engines of gasoline vehicles or purifying exhaust gas from diesel engines. Available.

Continuation of the front page (56) References JP-A-4-16239 (JP, A) JP-A-4-4045 (JP, A) JP-A-3-165816 (JP, A) JP-A-3-196842 (JP) , A) JP-A-61-21611 (JP, A) JP-A-4-118030 (JP, A) JP-T2-500822 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B01J 21/00-38/74

Claims (4)

(57) [Claims] 1. An X-ray diffraction pattern as shown in Table 1, which is expressed as a molar ratio of oxide (1 ± 0.8) R ₂ O · [aM ₂ O ₃ · bM ′ in a dehydrated state. O ・ cA
l ₂ O ₃ ] · ySiO ₂ (wherein R is an alkali metal ion and / or hydrogen ion, M is selected from the group consisting of group VIII elements, rare earth elements, titanium, vanadium, chromium, niobium, antimony and gallium. And at least one or more element ions, M 'is magnesium, calcium,
Strontium, barium alkaline earth metal ions,
a ≧ 0, 20>b> 0 , a + c = 1, 3000>y> 1
1) A crystalline silicate having a chemical formula represented by the following formula: cobalt, titanium, zirconium, chromium, manganese,
Iron, lanthanum, zinc, aluminum, tin, nickel,
An exhaust gas treatment catalyst comprising at least one metal selected from the group consisting of magnesium, calcium, strontium and barium. [Table 1] 2. The crystalline silicate according to claim 1, wherein the crystalline silicate synthesized in advance is used as a mother crystal, and a crystalline silicate made of Si and O having the same crystal structure as the mother crystal on the outer surface of the mother crystal. The exhaust gas treatment catalyst according to claim 1, wherein the exhaust gas treatment catalyst is a layered composite crystalline silicate obtained by growing silicate. 3. The crystalline silicate according to claim 1, further comprising copper, titanium, zirconium, chromium, manganese,
Iron, cobalt, zinc, aluminum, tin, nickel,
An exhaust gas treatment catalyst comprising at least one metal selected from the group consisting of magnesium, calcium, strontium and barium. 4. The crystalline silicate according to claim 1, wherein the crystalline silicate synthesized in advance is used as a mother crystal, and the outer surface of the mother crystal has the same crystal structure as that of the mother crystal. 4. The exhaust gas treatment catalyst according to claim 3, wherein the catalyst is a layered composite crystalline silicate obtained by growing.