JPS58109140A - Production of honeycomb catalyst - Google Patents

Abstract

PURPOSE:To obtain a ceramic honeycomb catalyst having an improved thermal shock resistance by coating a honeycomb carrier with a water soluble polymer org. compd. then immersing the same into liquid dispersed with a catalyst compsn. CONSTITUTION:A ceramic honeycomb carrier is coated with a water soluble polymer org. compd. such as polyvinyl alcohol. On the other hand, a catalyst compsn. prepd. by dispersing, depositing and fixing base metal compds. and noble metal compds. which are catalytic active components on active refractory metallic oxides such as active alumina is dispersed in an aq. medium. The carrier to be coated is immersed in said dispersion. Thereafter, the carrier is dried and calcinated whereby the catalytic compsn. contg. active alumina, etc. are deposited thereon. By the above-mentioned method, the honeycomb catalyst of the monolithic structure having an improved thermal shock resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a honeycomb catalyst. Specifically, the present invention relates to a method for manufacturing a ceramic honeycomb catalyst having an integral structure with improved thermal shock resistance.

Generally, honeycomb catalysts are produced on a monolithic ceramic support containing mainly active refractory metal oxides such as alumino, °alumina-silica, silica, titania, zirconia, and platinum group metals such as platinum, palladium, rhodium, and ruthenium. Furthermore, a catalyst component in which transition metals such as copper, nickel, cobalt, and iron or their oxides, rare earth elements such as cerium and lanthanum, etc. are combined as necessary is supported.

This honeycomb is used for the purification of carbon monoxide, hydrocarbons, and nitrogen oxides in the exhaust gas of internal combustion engines such as automobiles, and for general industrial use, such as catalytic combustion for deodorizing waste gas and generating primary energy. widely used for. Particularly when used in automobiles, thermal shock resistance is required because the m degree of the catalyst used changes from moment to moment depending on the operating conditions.

In other words, in a honeycomb catalyst having an integral structure, the coefficient of thermal expansion differs between the ceramic honeycomb carrier and the catalyst component supported on the carrier, which tends to cause distortion between the carrier and the catalyst component, resulting in repeated cycles of rapid concentration changes. It has been pointed out that over time, honeycomb catalysts develop cracks, which gradually grow, and in the worst case scenario, the catalyst itself may break into two or more pieces, which may impede its use.

In particular, when a honeycomb catalyst is installed close to the engine outlet, the exhaust temperature is high and the operating temperature difference becomes large, so the physical temperature of the honeycomb catalyst, especially thermal shock resistance, is strongly required. That's what happens.

An object of the present invention is to provide a method for producing a ceramic honeycomb catalyst that fully satisfies this requirement.

As a result of intensive studies to satisfy this objective, the present inventors found that when coating a honeycomb carrier with the catalyst component described above, the honeycomb carrier was coated with a water-soluble polymeric organic compound in advance, and then the obtained honeycomb carrier was activated. A catalyst is obtained by immersing a catalyst composition obtained by dispersing and fixing a base metal compound and/or a noble metal compound as a catalytically active component on a refractory metal oxide in a dispersion solution in an aqueous medium. Significantly improves thermal shock resistance without causing practical problems such as peeling of the catalyst coating layer from the honeycomb catalyst due to vibrations and exhaust gas flow during driving of automobiles, etc., and without having any negative effect on catalyst activity. They discovered that it is possible to do this and completed the present invention.

The purpose of the present invention will be further explained. In the conventional method, the honeycomb and the catalyst supported thereon have a high coefficient of thermal expansion as described above, and therefore are directly affected by rapid temperature changes during use.

In particular, in the case of ceramic honeycombs having tooth-shaped pores with an average pore diameter of 1 to 10 microns, catalyst components such as alumina with different coefficients of thermal expansion are infiltrated and supported in the pores of the honeycomb carrier. The crack occurrence rate tends to increase. In the present invention, in order to prevent the occurrence of cracks in the carrier, which may be caused by the difference in thermal expansion coefficient between the honeycomb carrier and the supported catalyst component, a polymeric organic compound is first coated on the surface of the honeycomb carrier, and then the catalyst is coated on each layer. When the components are supported and fired, the high molecular weight organic compound coated with the caulking burns and disappears, and a gap equivalent to a thin film is partially created between the honeycomb carrier and the supported catalyst component. It is possible to alleviate distortion caused by expansion differences. Therefore, according to the method of the present invention, by changing the amount of the polymeric organic compound coated first, that is, by changing the thickness of the coating film, the desired level of thermal shock resistance can be changed. .

The present invention also provides a treatment method for preventing etching of ceramic honeycomb carriers encountered when supporting catalyst components. That is, in the conventional method, a catalyst is provided in which a catalyst component consisting of a base metal compound or a noble metal compound as a catalyst component element is dispersedly supported on an activated refractory metal oxide such as -H activated alumina on a honeycomb carrier. The aqueous dispersions and aqueous solutions used for these coating treatments and dispersion support treatments are generally used with the addition of carboxylic acid or μ acid to ensure stability. The components tend to remain in the carrier even after the coating treatment and after 1 hour of dispersion, and under the high temperature conditions during drying and firing (i. the honeycomb base material is etched and the mechanical strength of the carrier base material is greatly weakened). Sisters,
It tends to increase the hair 9 lac generation I of the catalyst.

Although this tendency is slightly layered by coating the honeycomb carrier with the above-mentioned polymeric organic compound, the occurrence of hair cracks cannot be sufficiently prevented. The inventors 1, [&! We have discovered that an extremely excellent hair crack prevention effect can be obtained by bringing the residual acid component-containing support composition into contact with a basic compound before exposing it to high temperature conditions to neutralize the acid component, and have improved honeycomb catalysts. We have now completed the manufacturing method.

Based on the above findings, the present inventors have come to specify the present invention as follows.

(1) In the method for producing a ceramic balm catalyst having an integral structure, a) the honeycomb carrier is coated with a water-soluble polymeric organic compound in advance, and b) the coated carrier obtained is activated. A honeycomb catalyst characterized in that a catalyst composition comprising a base metal compound and/or a noble metal compound as a catalytically active component dispersed and fixed on a refractory metal oxide is immersed in a dispersion in an aqueous medium. vJ construction method.

(2) The method described in (1) above, characterized in that an organic salt, an inorganic salt, or a hydroxide of the active refractory metal oxide is allowed to coexist in the dispersion □1' liquid □.

(3) The method described in (1) or (2) above, characterized in that an organic acid or an inorganic acid is allowed to coexist in the dispersion.

(4) The supported composition obtained by the immersion treatment,
The method according to (3) above, characterized in that the remaining acid component is neutralized by contacting with a basic compound-containing gas.

(5) The above (1), (2), wherein the water-soluble polymeric organic compound is polyvinyl alcohol.
The method described in (3) or (4).

(6) The above (1), (2), (3), and (4), wherein the activated refractory metal oxide is activated alumina.
) or the method described in (5).

(7) The method according to (4), (5) or (6) above, wherein the basic compound is ammonia.

The present invention will be explained in more detail below.

The polymeric organic compound used in the present invention is desirably water-soluble for handling purposes. The molecular value of the polymer compound used is preferably 200 or more. Particularly preferably, it is 500 or more and 1. In use, it is limited by the viscosity of the aqueous solution, and is less than 500 cp (centiboise), preferably less than 20 GCI), particularly preferably 100 cp or more. After coating and drying, the high-molecular organic compound used in the present invention forms a so-called film, and has an affinity with the aqueous medium containing the catalyst composition during the next operation of supporting the catalyst composition. It is desirable to have properties that have some degree of .

More specifically preferred water-soluble polymeric organic compounds include, for example, various starches (wheat, corn, potato, tapioca), natural gums such as funori, jintachi hibiin, gum arabic, and gum tragacanth. products, glue, h-zein, various processed starches, starch derivatives, methylcellulose,
Ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, various polyvinyl alcohols,
Polyacrylic acid J: Bizo derivatives, maleic acid copolymers, such as vinyl acetate maleic anhydride copolymers,
Examples include subrene maleic acid copolymer, which can be used alone or in a mixture of two or more.

In consideration of film-forming properties and ease of subsequent catalyst support, various polyvinyl alcohols, polyacrylic acids, and derivatives thereof are particularly preferred.

The amount of the above-mentioned polymeric organic compound used is 0 in aqueous solution.
．． It can be used in an amount of 5 to 50% by volume, but preferably 1 to 20% by volume, and the optimum amount can be determined depending on the viscosity of the threatening molecular organic compound and film formability.

Coating method for ceramic honeycomb carrier: The honeycomb carrier is immersed in the aqueous solution of the above-mentioned water-soluble molecular organic compound (at normal pressure, reduced pressure, or pressurized), then taken out and, for example, blown off the excess solution in an air stream. Blow off and dry at room temperature or below 200°C (that is, the water-soluble polymeric organic compound will not deteriorate due to combustion, etc.), or if necessary, directly use it for the next catalyst loading operation.

Next, a catalyst composition is prepared by dispersing and fixing a base metal compound and/or a noble metal compound in the catalytic activity region 5) on an active refractory metal oxide, and a dispersion liquid is prepared by dispersing this in an aqueous medium. Next, a method of coating a catalyst composition on a honeycomb carrier coated with a water-soluble polymeric organic compound using this dispersion will be explained.

Conventionally, the coating method for preparing the honeycomb catalyst is as follows:
There are things like the following.

A: Coating a slurry of a soluble compound of an active refractory metal oxide, such as soluble alumina, and firing to form an active refractory metal oxide, such as an activated alumina film, followed by loading the catalytically active component and further firing. Zuru.

B: It is coated with a slurry of an active refractory metal oxide, such as activated alumina, and after sintering, the catalytic active component is supported and further sintered.

C: A part of the catalytic active component is mixed and coated in the active refractory metal oxide slurry, and the remaining residue is removed after firing. ! ! The active ingredient is supported and further baked.

D A catalytically active component is mixed into a biactive refractory metal oxide slurry, subjected to N treatment, and fired.

However, all of these methods do not give sufficient consideration to thermal shock resistance, require coating, supporting treatment, and calcination treatment multiple times, and even if coated, the catalytic active components tend to migrate easily. However, it had some disadvantages such as (causing a decrease in catalyst activity).

In contrast, in the method of the present invention, the base metal element 1')ff, which is a catalytically active component, is deposited on the active refractory metal oxide in advance.
+ Dispersion carrier of metal element in oxide or metal form 1) Fixation C
This method involves preparing a catalyst composition, forming an aqueous dispersion, and coating the honeycomb carrier with the catalyst composition.It is sufficient to bring the carrier and the catalyst composition into contact with each other in a single, extremely simple operation, and a high-temperature treatment called calcination is required. Just do it the minimum number of times (,
Moreover, it has the advantage that the catalytically active components can be used stably and effectively. Conventionally, even when coating a honeycomb carrier with an active refractory metal oxide, the catalytic active component is supported (each time the honeycomb 1111j body is exposed to an acid component added to the Li aqueous medium). However, according to the method of the present invention, since it is first coated with an aqueous polymeric organic compound, etching is not only considerably prevented, but also acid remaining in the support composition is removed. Since the components are almost completely neutralized by the salt V-type compound, it also has the advantage of being able to completely prevent the occurrence of oxidation.

The active refractory metal oxide C used in the present invention includes alumina, silica/alumina, magnesiff, titania, zirconia, silica/magnesia, etc. Among them, alumina and zirconia are used in powdered, spherical, cylindrical, etc. used in the form Base metal elements are iron, cobalt, nickel, mannonone, copper, silver, chromium, molybdenum, tungsten, butane, zircon, zinc, germanium, tin, lead, phosphorus, antimony, bismuth, rare earth elements, alkali metals, and alkaline earths. It can be used in the form of any compound selected from metals and fixed to an active refractory metal oxide, such as nitrates, hydrochlorides, sulfates, carbonates, organic acid salts, ammine complexes, Examples include hydroxides, oxides, etc., and use of nitrates, carbonates, acetates, formates, hydroxides and oxides is particularly preferred.

The noble metal elements are selected from among platinum, palladium, rhodium, nium, and iridium, and nitrates, hydrochlorides, metal acids, and their salts are used in the form of an aqueous solution or in the form of one ide.

The method for preparing the catalyst composition includes thoroughly mixing the above-mentioned active refractory metal oxide or its precursor, such as a hydrate or partial hydrate, with a base metal element compound and/or a noble metal log compound in an aqueous solution or slurry state; They are mutually fixed by drying and firing or reduction, and Ino 0 drying is performed at 80-200°C.
Calcination may be carried out at 200 to 800°C, either in air, and reduction may be carried out at room temperature with hydrogen sulfide, hydrazine, etc., or reduction treatment may be carried out at 100 to 400°C in a nitrogen-hydrogen stream.

The Nigaru catalyst composition prepared above is composed of base metal elements and noble metal elements, which are catalytically active components, dispersed and supported in an oxide or metal state on an active refractory metal oxide and fixed with good stability. An aqueous dispersion for coating ceramic carriers is prepared with excellent stability.

First, the active refractory metal oxides or their precursors, such as hydrates and partial hydrates, may be partially water-soluble, or may be porous fine powders or compacts. good. In particular, substances with a large specific surface area, such as activated alumina, are in the form of porous compacts with an average diameter of 1 to 6.
A commercially available product (2) is used as it is to contain and support a catalytically active substance, and can be easily and uniformly dispersed in a molded body and fixed with sufficient stability by firing at a high temperature.

The catalyst composition composed of the oxide and the metal element thus obtained is then ground if necessary, water is added, and if necessary, a small amount of the colloidal refractory metal oxide and the A metal salt or an acid component is added and the slurry is pulverized in a wet pulverizer, such as a ball mill or a colloid mill, to form a slurry, which is then subjected to IWI.

As the colloidal refractory metal oxide added in a small amount to the aqueous medium, for example, boehmite-like hydrated alumina, alumina sol, silica sol, titania sol, etc. can be used, and it is added in a range of 2 to 2011% to the solid catalyst composition. . Examples of salts include aluminum nitrate (Al (
NOa ) a ) is used and Al (No srs
It is added in an amount of 0.1 to 7% by weight based on the solid catalyst composition. The acid is nitric acid, J! Acid, acetic acid, etc. are used, and can be added in an amount of 0.05 to 6% by weight based on the solid catalyst composition.

The slurry prepared in this way is immersed in a honeycomb carrier coated with a water-soluble polymeric organic compound in advance as described above, and the excess slurry is blown off using high-pressure air to remove the required amount of catalyst. Coating the composition. When using an aqueous medium containing a catalyst composition containing a small amount of an acid component as described above, if necessary, the S residual acid component may be neutralized by exposing it to an atmosphere containing a basic gas immediately after coating or before calcination. It's good to do that. It is preferable to perform this neutralization operation LL immediately after the coating process, but it is effective if it is performed after drying or before the firing process. That is, the state before heating and firing, specifically 200°C or less, preferably room temperature to 150°C
Particularly preferably, it is placed in a basic gas-containing atmosphere at room temperature.

Examples of the basic gas used in the present invention include ammonium chloride, hydrazine, methylamine, ethylamine, propylamine, etc., and any of these gases may be used alone or in combination.

The concentration of the basic gas used is 0.1% by volume or more, and it is sufficient that it is 1% by volume, and these are used in a dry state or mixed with humid air, nitrogen, etc. Among these basic gases, ammonia is particularly preferable in terms of cost and the like, and liquid aqueous ammonia can also be used. When ammonia is used, it is particularly preferable to use a mixed gas containing it in the air at a concentration of 1 to 20% by volume;
Conditions of exposure at room temperature, preferably from 1 minute to 30 minutes, are chosen to give the best results.

The honeycomb carrier coated with the catalyst composition is then dried at below 200°C, usually between 100 and 150°C, and if necessary at 800°C.
The finished catalyst is obtained by calcination at temperatures below °C, but as mentioned earlier, the catalyst composition is pre-calcined and is in the oxide or metal state, so calcination can be omitted, which is industrially advantageous. It is a manufacturing method.

The ceramic honeycomb carrier used in the present invention can be of any type as long as it is commonly used in the field, and in particular, cordierite, Murai 1, α-alumino,
Heat resistant ceramics such as zirconia, titania, butane phosphate, aluminum titanate, petalite, subodiemene, aluminosilicate, magnesilate silicate, etc. give favorable results.

EXAMPLES The present invention will be specifically explained below using Examples, but the present invention is not limited to these Examples.

Length m Example 1 5% by weight aqueous solution of completely saponified polyvinyl alcohol with a molecular weight of 50G [■ PVA105 manufactured by Kuraray] 1.5
J? , with a diameter of 105.3111111., having an aperture of 300 cells/inch square. A cylindrical cordierite ceramic honeycomb (average pore size 4 microns) of length 11516!11 was completely immersed in the above solution for 2 minutes, then removed, and the excess solution was blown off in a stream of air for 120 minutes. It was dried at ℃ for about 5 hours. Dry IP approx. 1.5 (
An increase in weight of 1 was observed.

Next, the specific surface area is 120m'/g1', and the average diameter is 33II1
m) 1500 g of spherical activated alumina was added to 75.79 g [
] Lotitraamine palladium (Pd (NHs)4
) The carrier was impregnated with 1.5 tons of aqueous solution containing C11 and 22.50 acetic acid to uniformly disperse palladium inside the carrier, dried at 150°C, and then calcined at 500°C to obtain a catalyst composition. This catalyst composition was added to 1512 cc of an aqueous solution containing 25.29 g of aluminum nitrate and ground in a ball mill for 16 hours. The honeycomb carrier subjected to the iI treatment was immersed in the resulting slurry for 1 minute, taken out, the excess slurry was blown off in an air stream, dried at 120°C, and fired in air at 400°C to obtain palladium powder. A finished catalyst containing .5 g and 700 g of catalyst composition was obtained.

Example 2 A complete catalyst was obtained in the same manner as in Example 1 except that a 3% by weight aqueous solution of polyvinyl alcohol (PVA217 manufactured by Kuraray) having a molecular weight of 1700 and saponified to approximately 80% was used.

Example 3 A complete catalyst was obtained in the same manner as in Example 1 except that a 3% by weight aqueous solution of completely saponified polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd.) having a molecular weight of 1700 was used.

Example 4 Ammonium polyacrylate with a molecular weight of about 4000
A finished catalyst was obtained in the same manner as in Example 1, except that a wt% aqueous solution was used.

Example 5 A finished catalyst was obtained in the same manner as in Example 1 except that a 5% by weight aqueous solution of corn starch was used.

Comparative Example 1 A finished catalyst was obtained in the same manner as in Example 1 except that the polyvinyl alcohol coating treatment was not performed in the same manner as in Example 1.

Comparative Example 2 A carrier similar to that used in Example 1 was used with a specific surface area of 120
110 activated alumina powder (approximately 50 Metsu J) 1500
1512cc containing 25.2Q of aluminum nitrate
The resulting slurry was immersed in an aqueous solution of 100% and ground for 16 hours using a ball mill, taken out, the excess slurry was blown off in an air stream, and dried at 120°C. was carried.

Then 11 including palladium of 18.750! ! The above alumina support was immersed in 1.5 t of palladium nitric acid aqueous solution (containing 52.5 °C of nitric acid) for 1 minute, taken out, the excess solution was blown off, dried at 120°C, and then immersed in air for 500 °C.
The finished catalyst containing 1.5 g of palladium was obtained by calcination at .degree.

Example 6 A honeycomb carrier similar to that used in Example 1 was subjected to a coating treatment in the same manner as in Example 1, and then a specific surface area of 100
Cylindrical activated alumino 1500 (+ 255.10 cerium nitrate (
Ce (No 3) 3) To40.4o (DMi
The catalyst composition, which was thoroughly mixed with an aqueous solution of i-platinum Wi@containing (''・su 1,5/), dried at 150°C, and calcined at 500°C, was added to 1650cc of an aqueous solution containing 82.7g of acetic acid. In addition, the slurry was ground in a ball mill for 20 hours, immersed in the resulting slurry for 2 minutes, taken out, the excess slurry was blown away in an air stream, dried at 150°C, and reduced and calcined at 400°C for 1 hour in a nitrogen stream containing 5% hydrogen. and 1g of platinum,
A finished catalyst containing cerium oxide 79 and a total catalyst composition 861) was obtained.

Example 7 A honeycomb carrier similar to that used in Example 1 was subjected to a coating treatment in the same manner as in Example 3, and then a cylindrical activated alumina 15001J similar to that used in Example 6 was coated for 15 minutes.
1,5 in an aqueous solution containing 7.9 g of cerium nitrate and 508.643 g of nickel nitrate (Ni (NO8>2)), dried at 150 °C, calcined at 600 °C, and then the total amount of this composition was , dichlorodihydroxotetate of 23.69 ammineplatinum (Pt(NH3)4(OH
) 2) C12 and 4.2 g of tric [10 hexaammine rhodium (Rh (Ni-13)6) C13 and 22.
5 (J) to uniformly disperse platinum and rhodium in an aqueous solution at 15°C containing acetic acid, dry at 150°C, and reduce at 400°C for 30 minutes in a nitrogen stream containing 5% hydrogen. The catalyst composition obtained by firing was poured into 9 mouths of 1778 cc of an aqueous solution containing 57.5 s of nitric acid, and ground in a ball mill for 20 hours. Drying at 130 DEG C. yielded a finished catalyst for ternary use containing 09 g of platinum, 1 g of rhodium O, 6 g of cerium oxide, 15 g of nickel oxide and containing 130 g of total catalyst composition.

Example 8 A honeycomb carrier similar to that used in Example 1 was coated in the same manner as in Example 3, and then 150 Gg of cylindrical activated aluminum was coated in the same manner as in Example 6. 14
5.90 cerium nitrate (C.(NO3)3) 233,
29 iron nitrate (Fe(No3)s), 203
Impregnated in an aqueous solution of 1,51 containing 0% phosphoric acid, 19.119% chloroplatinic acid, 805g palladium nitrate and 261g rhodium chloride, dried at 150°C and dried at 600°C.
A catalyst composition was obtained by calcining at ℃. This catalyst composition
In addition to 1661 cc of an aqueous solution containing 8 g of nitric acid, the resulting slurry was ground for 20 hours in a ball mill, immersed for 2 minutes, taken out, and the excess slurry was blown off in a stream of air.
kept for 20 minutes in an air atmosphere containing approximately 2% ammonia 1
Dry at 30℃, platinum 0.710, palladium 0.29
i) A finished catalyst for the binary system was obtained containing 0.11 J of 10 dium, 6 g of cerium oxide, 69 iron oxide and 0.05 Q of phosphorus and containing 130 g of total catalyst composition.

Example 9 A honeycomb carrier similar to that used in Example 1 was subjected to coating treatment in the same manner as in Example 1, and then activated alumina powder 15G09 similar to Comparative Example 2 and iron oxide powder 78. 3
(], 148.4 tll of cerium nitrate, 1,0
9 g dinitrodiaminoplatinum (Pt (Nj(3)2
<NO2)2) was sufficiently mixed with an aqueous solution of L 1.5t containing 2.62g of rhodium chloride, dried at 150°C, and calcined at 600°C to obtain a catalyst composition. This catalyst composition was added to 70 cc of an aqueous solution containing 20.89 acetic acid, ground in a ball mill for 20 hours, immersed in an IJ cleaner for 1 minute, removed, blown off excess slurry in an air stream, Dry at ℃, platinum 0.8
99, rhodium 0.099! II, cerium oxide 6g
, a ternary finished catalyst of 4J containing 6 g of iron oxide and a total catalyst composition of 128 g was obtained.

Example 10 A honeycomb carrier 4 similar to that used in Example 1 was subjected to coating treatment in the same manner as in Example 4, and then pseudoboehmite alumina powder (alumina content 175%) 1900 (l, 3
01! I+ lanthanum nitrate [t, a (coa) 3) and 5
A catalyst composition which had been thoroughly mixed with an aqueous solution of 2.Ot containing palladium chloride of 3.39, dried at 150°C and calcined at 600°C was mixed with 100 g of the same pseudo-boehmite alumina as above and nitric acid of 27.617. Contains I G33c
c), milled in a ball mill for 18 hours, immersed in the slurry for 2 minutes, taken out, blown off the excess slurry in an air stream, dried at 150 °C, and then dried at 150 °C for 5 minutes.
A finished catalyst containing 1.517 g of palladium, 7.1 g of lanthanum oxide, and 79 g of the catalyst composition was obtained by calcining at 00°C.

・Example 11 A honeycomb carrier similar to that used in Example 1 was subjected to a coating treatment in the same manner as in Example 2, and then 69.6 g of activated alumina t5oog as used in Example 6 was applied. Dichlorotetraamminepalladium (Pd (NH)
) A catalyst composition containing CI□ and 22.50 acetic acid was impregnated in 1.5 tons of aqueous solution, palladium was dispersed inside the carrier, dried at 150 °C, and calcined at 500 °C, and added to 1530 cc of aqueous solution. , immersed in the slurry obtained by crushing the ball mill C for 30 hours for 1 minute,
Remove, blow off excess slurry in a stream of air, and
The finished catalyst was dried at 30° C. and contained 1.4 g of palladium and 71 g of catalyst composition.

Example 12 The thermal shock resistance of each catalyst obtained in Examples 1 to 11 and Comparative Examples 1 to 2 was tested as follows.

That is, each sample was placed on a 15-inch-thick mullite plate stand, placed in an electric furnace set at each temperature for 30 minutes, and after 30 minutes, taken out to room temperature in the stand and oven, and left for 30 minutes. Cool down. After repeating this series of heating and cooling for 10 times, clear cracks appeared in the catalyst.If no cracks appeared, then I raised the temperature of the electric furnace by 50℃ and repeated the same process for 7 times. The result is as follows:

Table 1 According to Table 1, it can be seen that each example according to the present invention is superior to each comparative example.

Claims (7)

[Claims] (1) In the method for producing a ceramic honeycomb catalyst having an integral structure, i+) the honeycomb carrier is coated in advance with a water-soluble polymeric organic compound, and b) the coated carrier thus obtained is treated with activated refractory material. A honeycomb catalyst characterized by being immersed in a dispersion in which a catalyst composition comprising a base metal compound and/or a noble metal compound as a catalytically active component dispersed and fixed on an aqueous metal oxide is dispersed in an aqueous medium. Ij31i method. (2) an organic salt of the active refractory metal in the fraction;
The method according to claim (1), characterized in that an inorganic salt or hydroxide is allowed to coexist. (3) Claim (1) or (2) characterized in that an organic acid or an inorganic acid is allowed to coexist in the dispersion.
) method described. (4) The supported composition obtained by the immersion treatment,
The method according to claim (3), characterized in that the remaining acid component is neutralized by contacting with a basic compound-containing gas. (5) Claim (1) characterized in that the water-soluble polymeric organic compound is polyvinyl alcohol.
, (2), (3) or (4). (6) Claims (1), (2), (2) characterized in that the activated refractory metal oxide is activated alumina.
3), (4) or the method described in (5). (7) The method according to claim (4), (5) or (6), wherein the basic compound is ammonia.