JP3254321B2 - Catalyst slurry, catalyst carrier slurry, and method for producing catalyst using them - 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 for catalytic combustion used for mixing a liquid fuel such as kerosene or a gaseous fuel such as city gas with air for catalytic combustion, or generated from various combustion equipment, automobiles and the like. The present invention relates to a purification catalyst used for detoxifying exhaust gas generated, and more particularly to an improvement of a catalyst using a metal substrate.

[0002]

^2. Description of the Related Art In general, a catalyst for catalytic combustion or a purifying catalyst is formed by forming a coating layer made of activated alumina or the like called a wash coat on a honeycomb-like ceramic made of cordierite or the like, and having a specific surface area of usually 10 to 50 m ² / cm ² . g, and the carrier coating layer was prepared by supporting a noble metal component. The ceramics such as cordierite used here have a small coefficient of thermal expansion, so they have little effect on the catalyst coating layer formed on the surface, and even if the catalyst coating layer is dense or porous, peeling does not occur. It rarely occurred. However, in recent years, a base material made of a ferritic stainless steel containing aluminum excellent in pressure loss and warm-up performance has been used in order to improve catalyst performance, and a new problem has arisen. In the case of this metal substrate, the coefficient of thermal expansion is much larger than that of cordierite ceramics, and there is a large difference in the coefficient of expansion between the metal substrate and the catalyst coating layer formed on the surface thereof. In addition, since the catalyst coating layer is formed on the surface of the substrate having almost no water absorption, it is hard to say that the adhesion is good. Therefore, in order to improve the adhesion between the base material and the catalyst coating layer, the base material is oxidized at a high temperature to form a whisker-like oxide film on the surface of the base material.

[0003]

However, when a catalyst body in which a catalyst layer is coated on a substrate having an oxide film formed thereon is used for catalytic combustion, the most upstream part of the catalyst body is brought to a considerably high temperature state. Because of the exposure, even if heat-resistant particles such as activated alumina are used as the catalyst carrier, the particles gradually sinter due to the high temperature, and finally become α and undergo thermal contraction, and are easily peeled from the substrate.
In addition, in the case of a metal substrate, in order to perform wash coating on a material having almost no water absorption, after being immersed in a catalyst slurry and pulled up, the lower part of the metal substrate is compared with ceramics such as cordierite. Large pools are likely to form. The liquid pool part where the coating amount is locally increased is
It is weak to thermal shock and mechanical shock, and easily causes peeling during use. Then, when peeled, it naturally causes deterioration of performance.

Further, since a substrate having no water absorbency is wash-coated, it is necessary to select whether the viscosity of the catalyst slurry is set higher or the number of times of wash coating is increased as compared with the prior art. When the slurry viscosity is increased, a larger liquid pool is likely to occur. In addition, when the number of times of wash coating is increased, the liquid pool formed in the first time has more water absorbing power than the others, so that the coating amount in this portion tends to increase in the second time. When the repetition is performed five or six times, only the coating amount at the end of the metal base tends to be abnormally large as compared with other places, which causes the end peeling. The present invention has been made in view of the conventional problems described above, and uniformly from upstream to downstream with respect to the catalyst body using a metal substrate,
Another object of the present invention is to provide a catalyst slurry or a catalyst carrier slurry for forming a catalyst coating layer having excellent thermal shock resistance and a catalyst obtained by using the same.

[0005]

The catalyst slurry of the present invention comprises an aqueous composition containing at least inorganic heat-resistant particles having a high specific surface area, a noble metal, polyethylene glycol and acetylene glycol. Further, the catalyst carrier slurry of the present invention comprises an aqueous composition containing at least inorganic heat-resistant particles having a high specific surface area, polyethylene glycol and acetylene glycol. Here, the inorganic heat-resistant particles having a high specific surface area preferably have an average particle diameter of 4 to 6 μm. Further, the catalyst body of the present invention comprises a substrate made of ferritic stainless steel containing aluminum and a catalyst coating layer formed on the surface thereof, the catalyst coating layer has a cumulative pore volume of 1 to 2 cc / g, and a membrane. The thickness is 40 μm or less.

[0006]

The present invention relates to a catalyst slurry for coating the surface of a base material made of ferritic stainless steel containing aluminum, comprising, in addition to inorganic heat-resistant particles having a high specific surface area serving as a catalyst carrier and a noble metal, polyethylene glycol and acetylene glycol. Contains at least. Among them, the functions of polyethylene glycol are to improve the wettability to the substrate surface, to improve the film-forming property, and to maintain the porosity in the coating layer. Since the metal substrate does not have water absorbency, repelling of the catalyst slurry or the catalyst carrier slurry is liable to occur if the surface of the metal substrate is dirty. Polyethylene glycol is effective in preventing this. In addition, in the case of a slurry composed of a solvent containing only water, at the time of drying, the cohesive force of the inorganic heat-resistant particles is strengthened at some point, and cracks are likely to occur in the coating layer in which the liquid is collected. Since the drying speed is reduced and the inorganic heat-resistant particles act as a buffer when drying and shrinking, cracks hardly occur. Furthermore, since polyethylene glycol having a large molecular weight (average molecular weight of about 20,000) acts as a buffer for heat-resistant particles, the heat-resistant particles can be loosely bonded to form a coating layer, so that the porosity can be controlled. By controlling the type and the amount of addition, a coating layer having a large porosity can be easily formed.

[0007] The functions of acetylene glycol are to improve the wettability to the base material, to suppress the change of the viscosity of the catalyst slurry or the catalyst carrier slurry with time, and to reduce the pool. Acetylene glycol is a nonionic surfactant, and the effect of improving the wettability to the substrate is even better than polyethylene glycol. Further, the viscosity of the catalyst slurry or the catalyst carrier slurry slightly decreases with time. However, the addition of acetylene glycol emulsifies the inorganic heat-resistant particles, which is effective in suppressing the change of the catalyst slurry with time. Furthermore, as an important function, the base material having no water absorption is immersed in the catalyst slurry or the catalyst carrier slurry, the liquid drainage property when the base material is pulled up is improved, and the generation of the liquid pool is improved. This is a result of the ability to reduce the surface tension of the catalyst slurry by adding acetylene glycol. Therefore, the honeycomb structure using the corrugated metal base material is immersed in the slurry, and the excess slurry remaining in the lattice after being pulled up can be treated with an air gun of a weak pressure, and can be processed from the upstream to the downstream of the coating layer. Variation in coating amount can be improved. Even in the case of performing a plurality of wash coats, since the amount of liquid pool at one time is reduced, the variation in the coating amount from the upstream to the downstream is improved, and the coating layer is formed more uniformly than in the past, and as a result, In addition, the pressure loss when using the catalyst can be effectively reduced.

In the present invention, the average particle size is 4 to 6 μm
By using the inorganic heat-resistant particles of (1) and polyethylene glycol having a large molecular weight as an additive, a catalyst coating layer having a large porosity can be formed on a metal substrate. Conventionally, it has been considered that it is desirable that the metal substrate be firmly adhered to the catalyst coating layer.However, as a result of investigations by the present inventors, it has been found that a coating layer can be formed on a substrate having a large thermal expansion coefficient. Even so, as long as it is firmly adhered, the difference in expansion coefficient between the base material and the coating layer becomes a significant problem,
It turns out that it cannot withstand severe thermal shock. Also,
To reduce the particle size to firmly adhere the coating layer,
When a binder such as alumina sol is used, the sintering of the coating layer is promoted. Therefore, the present inventors studied a preferable catalyst slurry or catalyst carrier slurry for thinly coating a catalyst coating layer having a large porosity so as not to cause excessive force even under severe thermal shock conditions on a metal substrate, The present invention has been reached. The catalyst coating layer having a large porosity obtained in the present invention was sufficiently resistant to severe thermal shock in catalytic combustion.

The catalyst coating layer coated on a substrate using the catalyst slurry of the present invention has a cumulative pore volume of 1-2.
Excellent characteristics can be obtained at a cc / g and a film thickness of 40 μm or less. Further, the catalyst carrier coating layer coated on the substrate using the catalyst carrier slurry of the present invention becomes a catalyst coating layer by supporting a noble metal catalyst later. A larger cumulative pore volume improves the porosity of the coating layer and is suitable for the purpose of the present invention. However, if the cumulative pore volume is too large, the coating layer is weak and cannot withstand mechanical impact. Further, even if the cumulative pore volume is 1 to 2 cc / g, if the film thickness is large, the film is easily affected by the difference in expansion coefficient between the base material and the coating layer, which causes peeling. Therefore, the above-described conditions are necessary to obtain a catalyst coating layer that can withstand severe thermal shock.

[0010]

EXAMPLE A method for producing a catalyst using a catalyst slurry according to one example of the present invention will be described below. [Example 1] Fe-Cr-Al-based ferritic stainless steel having a Cr content of 20 wt% and an Al content of 5 wt% (thickness of 50%)
μm) was cut into a size of 55 × 82 mm and bent into a substrate having three concave portions. Next, the substrate was heat-treated at 900 ° C. for 30 minutes to form an oxide film on the surface. Then, BaO.Al ₂ O ₃ .Ce with an alumina content of about 80 wt%
100 g of O ₂ powder (specific surface area 120 m ² / g), water 180
g, polyethylene glycol (average molecular weight: 20,000) 6 g,
An aqueous composition containing 0.2 g of acetylene glycol and 4 g of an aqueous solution of dinitrodiammine platinum in terms of Pt was prepared by ball milling, and had an average particle size of 4.5 μm and a viscosity of 120 c.
ps catalyst slurry.

While holding the upper end of the base material having the three concave portions on the surface of the electromagnet, the base material is immersed in the catalyst slurry at a speed of 2 mm / sec while leaving the upper end portion of 4 mm, and 1 mm / sec.
After being pulled up at a speed of c and dried, a heat treatment was performed at 500 ° C. for 10 minutes. Then, while immersing the catalyst slurry in a state where the upper end portion is kept 4 mm while holding the upper end of the base material on the electromagnet surface in the same manner as in the first time, and pulled up at a speed of 1 mm / sec and dried, Heat treatment was performed at 500 ° C. for 10 minutes. As a result, 200 mg of the catalyst coating layer
The formed catalyst body 1 was obtained. Next, a base material having two concave portions and two half portions thereof to be engaged with the catalyst body 1 is similarly prepared, and after forming an oxide film on the base material, a catalyst coating layer is formed in the same manner. Medium 2 was used. Catalysts 1 and 2 were fixed in mold containers 3 and 4, respectively, so that catalysts 1 and 2 did not come off from the mold containers. The heat generating unit shown in FIGS. 1 and 2 was assembled by combining the mold containers 3 and 4 as a heat generating portion.

Comparative Example 1 Same Fe—Cr—
Al-based ferritic stainless steel (50 μm thick)
It was cut into a size of × 82 mm and bent into a substrate having three concave portions. Next, the substrate was heat-treated at 900 ° C. for 30 minutes to form an oxide film on the surface. After that, BaO ・ A
l ₂ O ₃ · CeO ₂ powder (specific surface area 120 m ² / g) 100
g, 175 g of water and 4 g of an aqueous solution of dinitrodiammine platinum in terms of Pt were prepared in a ball mill to prepare a catalyst slurry having an average particle size of 4.5 μm and a viscosity of 120 cps. 2 mm / sec in the catalyst slurry while holding the upper end of the substrate having three recesses on the electromagnet surface.
At a speed of 1 mm / s while leaving 4 mm at the upper end.
After being pulled up and dried at a speed of ec, a heat treatment was performed at 500 ° C. for 10 minutes. Thereafter, while the direction is reversed from that of the first time, and the upper end of the base material is similarly held on the electromagnet surface, the base material is immersed in the catalyst slurry while leaving the upper end 4 mm, and 1 mm / sec.
And then heat-treated at 500 ° C. for 10 minutes. As a result, the catalyst coating layer has a 200
mg of the formed catalyst body a was obtained. Next, a base material having two concave portions and two half thereof that are to be engaged with the catalyst body a is prepared, an oxide film is formed on the base material, and a catalyst coating layer is similarly formed. b. The catalysts a and b were fixed in the mold containers 3 and 4, respectively, so that the catalysts a and b did not come off from the mold containers. The heat generating unit shown in FIGS. 1 and 2 was assembled by combining the mold containers 3 and 4 as a heat generating portion.

1 and 2, reference numeral 5 denotes an isobutane gas cylinder. Valves 7 and 8 are provided between the cylinder 5 and the nozzle 6. The valve 7 is a main valve.
Is a sub-valve that is opened and closed by a bimetal (not shown). The fuel gas ejected from the nozzle 6 sucks the surrounding air by the attraction of the gas flow, is uniformly mixed in the mixing chamber 9, and is supplied to the combustion chamber 10. The combustion chamber 10 is provided inside a heat generating portion composed of two aluminum mold containers. On the wall surface of the combustion chamber 10, catalyst bodies 1 and 2 are provided inside the mold vessels 3 and 4. It is fixed by a boss 11 installed on the wall with a slight gap between them. The gap was adjusted by embossing (not shown) the surface of the aluminum mold container. In order to efficiently transfer the reaction heat (combustion heat) generated by the catalysts 1 and 2 to the outside, the aluminum mold containers 3 and 4 are provided with heat transfer fins 12 and 1.
The surfaces of the heat transfer fins 12 and 13 are also embossed (not shown). A piezoelectric ignition element 14 is arranged behind the catalyst bodies 1 and 2.

Next, the operation principle will be briefly described. First, the valve 7, which is the main valve, is opened, and fuel gas is supplied from the nozzle 6 to the mixing chamber 9, and at the same time, air is also supplied by the attraction. The fuel gas mixed with air is supplied to the combustion chamber 1
After the gas is introduced into the inner space, the spark is sparked by the piezoelectric ignition element 14 to form a temporary flame behind the catalyst body and near the exhaust port 15, and the reaction heat immediately heats the downstream portion of the catalyst body. To start catalytic combustion, and the catalytic combustion immediately shifts to the uppermost stream of the catalyst body. Combustion exhaust gas is exhaust port 1
Exhausted from 5 The heat of reaction is provided to the outside via a heat generating portion composed of aluminum mold containers 3 and 4 where the combustion exhaust gas and the catalyst are in contact with each other. The valve 8 is of a bimetal type, detects the temperature of one place (not shown) on the side of the heat generating part, closes at a certain temperature (about 220 ° C.) or higher, stops the supply of fuel gas, and adjusts the temperature of the heat generating part. used. This is for the purpose of preventing the temperature of the uppermost stream portion of the catalyst body from excessively rising to prevent the catalyst body from being rapidly deteriorated, and to protect the heat transfer fins 12 and 13 made of aluminum. Therefore, in the heat generating device, the supply and the stop of the fuel gas are repeated, and as a result, the catalyst also repeatedly generates and cools.

The fuel was burned for 1,000 hours under the conditions of an excess air ratio (air / fuel) of 1.02 and 500 kcal / h using isobutane as a fuel. As a result, the upstream part of the catalyst body has a considerably high temperature (about 900 ° C.) when the fuel gas is supplied.
Above, and is cooled to about 250 ° C. when the fuel gas is stopped. Therefore, the substrate was subjected to a heat cycle of 900 to 250 ° C. at intervals of 1 to 2 minutes, and the base material was also thermally deformed in the upstream portion of the metal base material. However, since the catalyst body according to the present invention was uniformly coated on the surface of the base material while having porosity, peeling did not occur even after 1000 hours. The catalyst body obtained in the comparative example had peeling at the upstream liquid pool. As in the present embodiment, the metal substrate is arranged in a thin plate in parallel with the flow direction of the mixed gas, and the fuel gas is supplied.
When the catalytic combustion is performed by repeating the stop, the upstream portion undergoes a large heat cycle, and a large temperature difference occurs in the catalyst body from the upstream portion to the downstream portion, resulting in thermal deformation of the base material. During the thermal deformation, a mechanical stress is applied, and the liquid pool portion is apt to peel off. Further, when the heat load on the upstream portion becomes excessive, the base material itself is largely thermally deformed and cannot be returned to its original state. In this case, a uniform and porous coating layer as in the present invention is required in order to prevent the catalyst coating layer from peeling off.

In Example 1, Ba having an average particle size of 4.5 μm was used.
Although O.Al ₂ O ₃ .CeO ₂ powder was used, the inorganic heat-resistant particles having a high specific surface area used in the present invention are preferably those mainly composed of activated alumina. However, those containing an alkaline earth metal for the purpose of improving the heat resistance of the activated alumina, or those containing a rare earth metal or the like as a promoter may be used. Further, zeolite may be added to some extent for the purpose of adsorption and deodorization. However, it is desirable to limit the average particle size to 4 to 6 μm.
Even if the average particle size is less than 4 μm, the effect is somewhat improved by increasing the amount of polyethylene glycol to be added, but the effect is also improved by 3%.
If it was less than μm, it was impossible, and cracks occurred in the liquid pool. On the other hand, even if it exceeds 6 μm, the effect is somewhat improved by reducing the amount of polyethylene glycol. However, the effect is unreasonable at 7 μm or more, the coating layer is brittle, and it is too vulnerable to mechanical impact, making practical use difficult. there were.

In Example 1, 6 wt% of polyethylene glycol was used with respect to the heat-resistant inorganic particles. However, the amount of addition was determined in consideration of the average particle size of the heat-resistant inorganic particles as described above. If it is big, you need to control it a little. The molecular weight of the polyethylene glycol used was suitably about 20,000.
By controlling the average particle size of the inorganic heat-resistant particles and the amount of polyethylene glycol added, a catalyst coating layer having a cumulative pore volume of 1 to 2 cc / g could be formed on the metal substrate. Since this coating layer is composed of heat-resistant particles having an average particle size of 4 to 6 μm, the pore distribution has peaks near 1 μm and 1 to 3 nm in diameter, and the pore volume near 1 μm is about 30 μm. % Or more. That is, 1 μm in diameter
The vicinity of m is a pore constituted by aggregation of heat-resistant particles, and the vicinity of a diameter of 1 to 3 nm is micropores of the heat-resistant particle itself. If the cumulative pore volume is less than 1 cc / g,
The coating layer became dense, inferior in thermal shock resistance, and peeled off. Further, when the cumulative pore volume is larger than 2 cc / g, the thermal shock resistance is excellent, but the coating layer is brittle and practically difficult. Further, even if the cumulative pore volume satisfies the above conditions, if the coating amount is large, the heat generating device as shown in this example is inferior in thermal shock resistance and peeled off, so that the film thickness is 40 μm or less, More preferably, it was required to be 30 μm or less.

In the examples, acetylene glycol was used in an amount of 0.2 wt% with respect to the inorganic heat-resistant particles. However, acetylene glycol is a nonionic surfactant, and does not need to be added in a large amount. It does not poison the catalytic metal. However, in order to obtain the effects of the present invention, 0.1 wt% or more is required. If the amount is too large, the catalyst slurry or the catalyst carrier slurry may generate liquid dripping on the substrate surface before drying. . Therefore, it is preferable that the content be at most 0.5 wt% or less.

[Embodiment 2] The same Fe-Cr-
Honeycomb structure using a corrugated substrate made of Al-based ferritic stainless steel (50 μm thick) (cell density 400 cells / inch ² , diameter 100, length 115 m)
m) was prepared. Next, this substrate was heat-treated at 900 ° C. for 4 hours to form an oxide film on the surface. After that, BaO
Al ₂ O ₃ .CeO ₂ powder (specific surface area 120 m ² / g) 10
00g, water 3000g, polyethylene glycol 60
g, 4 g of acetylene glycol, an aqueous solution of dinitrodiammine platinum, and 10 g and 2 g of rhodium chloride in terms of Pt and Rh, respectively, were prepared in a ball mill to prepare a 40 cps catalyst slurry.

While holding the upper end of the base material on the electromagnet surface,
The whole was immersed in the catalyst slurry at a speed of 2 mm / sec, pulled up at a speed of 2 mm / sec, and then transferred onto a 16-mesh Teflon net to remove excess catalyst slurry accumulated in the honeycomb lattice into 0 mesh. After blowing off with an air gun of 0.4 kg / cm ² , it was sufficiently dried with warm air of 60 ° C. and heat-treated at 500 ° C. for 30 minutes. Thereafter, the whole was immersed in the catalyst slurry while the upper end of the base material was similarly held on the electromagnet surface by reversing the direction from the first time, and 2 mm / sec.
c, lifted at a speed of c, transferred onto a 16-mesh Teflon net, blown off excess catalyst slurry remaining in the honeycomb lattice with an air gun of 0.4 kg / cm ² , dried, and then dried at 500 ° C. for 30 minutes. Heat treated. Thereafter, this work process was further repeated twice, and wash-coating was performed four times in total, thereby forming 120 g of the catalyst coating layer on the metal honeycomb.

Comparative Example 2 The same honeycomb substrate as in Example 2 was heat-treated at 900 ° C. for 4 hours to form an oxide film on the surface. Thereafter, an aqueous mixture obtained by adding 1000 g of BaO.Al ₂ O ₃ .CeO ₂ powder (specific surface area: 120 m ² / g), 3000 g of water, 10 g of an aqueous solution of dinitrodiammine platinum, and 10 g and 2 g of rhodium chloride in terms of Pt and Rh, respectively, was ball milled. Prepared and made a catalyst slurry of 40 cps. While holding the upper end of the base material on the electromagnet surface, the whole was immersed in the catalyst slurry at a speed of 2 mm / sec.
/ Sec, and then transferred onto a 16-mesh Teflon net. Excess catalyst slurry remaining in the honeycomb lattice is blown off with an air gun of 0.4 kg / cm ² , and then heated to a temperature of 60 ° C. Dry enough with air, 500 ℃
For 30 minutes. After that, the whole was immersed in the catalyst slurry while the upper end of the base material was similarly held on the electromagnet surface by reversing the direction from the first time, pulled up at a speed of 2 mm / sec, and transferred onto a 16-mesh Teflon net. Then, the excess catalyst slurry accumulated in the honeycomb lattice is reduced to 0.
4 kg / cm ² blown off with an air gun and dried
Heat treatment was performed at 500 ° C. for 30 minutes. Thereafter, this work process was further repeated twice, and wash-coating was performed four times in total, thereby forming 120 g of the catalyst coating layer on the metal honeycomb.

As a result of comparing the pressure loss of the honeycomb catalyst bodies obtained in Example 2 and Comparative Example 2, the catalyst body of the present invention was more effective in reducing the pressure loss by about 2%. In addition, the appearance of the catalyst body of the present invention was clearly reduced in liquid appearance at the end. The honeycomb catalyst body is generally used for purifying exhaust gas, but in such a case, the demand for thermal shock resistance is weaker than that for combustion. However, it is expected that the catalyst body will be used under more severe conditions in the field of exhaust gas purification in the future, and in that case, the catalyst obtained by the present invention can exhibit excellent performance.

The ferritic stainless steel containing aluminum used in the present invention is a material having excellent heat resistance and corrosion resistance, and generally contains 15 to 20% by weight of Cr and 3 to 10% by weight of Al.
At 5 wt%, a few additives and the balance are used in the composition of Fe. When this material is heat-treated at a high temperature of 900 ° C., an oxide film is formed, which enhances the adhesion to the catalyst coating layer by an anchoring effect. However, when coating a porous catalyst layer as in the present invention, an anchoring effect cannot be expected. However, it has been found that this oxide film is effective in preventing the oxidation (rust) inside the metal substrate from occurring due to the catalytic action of the noble metal contained in the catalyst coating layer. If an oxide film is formed for the purpose of preventing the oxidation (rust) inside the metal base material, the treatment at 900 ° C. for 4 hours, which has been conventionally mentioned, is not necessary. It was effective. The noble metal used in the present invention is
It may be supported on inorganic heat-resistant particles in advance, or may be contained in the catalyst slurry in the form of an aqueous solution. In the above examples, a catalyst slurry containing a catalyst component was used.However, a catalyst carrier coating layer was formed using a catalyst carrier slurry from which the catalyst component had been removed, and a catalyst metal was supported thereon by a conventional method. As described above, it is possible to form a uniform catalyst coating layer having excellent thermal shock resistance.

[0024]

According to the present invention, it is possible to form a catalyst coating layer having an appropriate and uniform porosity from upstream to downstream on a metal substrate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a heating device used in an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 Catalyst 3, 4 type container 5 Cylinder 6 Nozzle 7, 8 Valve 9 Mixing chamber 10 Combustion chamber 11 Boss 12, 13 Fin 14 Piezoelectric ignition element 15 Exhaust port

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01J 21/00-38/74 B01D 53/86

Claims (6)

(57) [Claims] 1. A catalyst slurry for coating a surface of a substrate made of ferritic stainless steel containing aluminum, comprising an aqueous composition containing at least inorganic heat-resistant particles having a high specific surface area, a noble metal, polyethylene glycol and acetylene glycol. A catalyst slurry, comprising: 2. A catalyst carrier slurry coated on the surface of a substrate made of ferritic stainless steel containing aluminum, comprising an aqueous composition containing at least inorganic heat-resistant particles having a high specific surface area, polyethylene glycol and acetylene glycol. A catalyst carrier slurry characterized by the above-mentioned. 3. The inorganic heat-resistant particles have an average particle size of 4 to 6 μm.
The catalyst slurry according to claim 1, wherein m is m. 4. An inorganic heat-resistant particle having an average particle size of 4 to 6 μm.
The catalyst carrier slurry according to claim 2, wherein m is m. 5. The method according to claim 1, wherein
Made of ferritic stainless steel containing aluminum
A catalyst coating having a cumulative pore volume of 1 to 2 cc / g
Forming a cover layer.
Manufacturing method. 6. Use of the catalyst carrier slurry according to claim 2
From ferritic stainless steel containing aluminum
Having a cumulative pore volume of 1 to 2 cc / g
Forming a medium carrier coating layer;
Having a step of supporting a noble metal catalyst on the cover layer.
A method for producing a catalyst body.