JPS61129043A - Method for supporting gatalytic component by ceramic substrate - Google Patents

Abstract

PURPOSE:To rapidly and uniformly support a catalytic component by a carrier, by impregnating a slurry or solution containing a catalytic component by a ceramic integrated structure and treating the impregnated one by a rotating and revolving centrifugal separator before baking the same. CONSTITUTION:An integrated structure comprising a ceramic substrate is supplied to a process 11 and impregnated with a slurry or solution containing a catalytic component. In this case, the ceramic substrate is pref. immersed for 30sec-5min. Subsequently, the impregnated substrate is introduced into containers 10a, 10b of the centrifugal separator of a process 12 and treated for about 20-120sec, in such a condition that a rotary speed is about 100-600rpm and rotation/revolution is about 1/10-1/100, to remove the excessive slurry or solution and the catalytic component is brought to a uniform coating layer. Next, the treated carrier is dried at about 80-180 deg.C for about 2-100hr in the heat-treatment process of a process 13.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for forming a catalyst component coating layer on a ceramic structure.

Catalysts in which catalyst components are supported on ceramic structures are used to purify toxic gases such as automobile exhaust gas and factory exhaust gas. The present invention relates to a method for forming a catalyst component coating layer on a ceramic structure more uniformly and efficiently.

<Prior Art> For exhaust gas purification, it is common practice to use a structure made of a ceramic base material, such as a monolith structure, on which a catalyst component coating layer is formed. These catalyst component coating layers are formed by impregnating and adhering a slurry or solution containing the catalyst component onto the surface of a ceramic substrate, and then removing the excess slurry or solution by blowing compressed air, or by removing the excess slurry or solution by blowing compressed air.
It is formed by applying and removing centrifugal force due to revolution, as described in Japanese Patent Application Laid-Open No. 57-7881. Then, by drying and, if desired, firing, a coating layer of alumina or the like is fixedly supported on the ceramic base material.

<Problems to be solved by the invention> The method of removing excess catalyst slurry or solution by blowing compressed air is difficult to uniformly blow away, especially when using a three-dimensional network structure. The drawback is that it doesn't pass.

In this respect, a method using centrifugal force is advantageous, but in a centrifugal separation method based on mere revolution, centrifugal force acts only in a fixed direction, and the slurry or solution also moves in a fixed direction. As a result, there is a difference in the amount of catalyst components supported between the center of rotation and the outer circumferential direction, and when this tendency becomes noticeable, there are drawbacks such as the holes being blocked in the outer circumferential direction.

<Means for Solving the Problems> The object of the present invention is to improve the above-mentioned drawbacks of the conventional methods and to quickly and uniformly support the slurry or solution of the deposited catalyst component. .

The method of coating a catalyst component on a ceramic substrate of the present invention includes immersing the ceramic substrate in a slurry or solution of the catalyst component,
The catalyst component is attached to the surface of the substrate, and then the excess slurry or solution is removed using a centrifugal separator consisting of a rotating container as shown in Fig. coated with a catalyst component,
The basic method is to uniformly coat and support the catalyst component by drying and, if desired, calcining.

<Structure of the invention> Next, the present invention will be explained based on the drawings.

FIG. 1 is a schematic diagram of an apparatus for removing excess catalyst slurry or solution from a ceramic substrate and forming a uniform coating layer. Excess slurry or solution is shaken off from the ceramic substrate set in the container 10 by the centrifugal force generated by the 10 revolutions of the revolution transmission shaft. As the container 10 rotates, the direction of shaking is gently changed, so that uneven distribution of the slurry or solution does not occur. In this case, the rotation speed is 1/ of the orbital speed.
to "/100" is preferable.

The rotation speed is 1/1o of the revolution speed. If it is smaller, it takes a longer time to rotate, and it takes time for the rotation to take effect. Also 1/. Even if the size is made larger, no better effect can be obtained, and on the contrary, the container and the ceramic base material are more likely to be damaged.To prevent this, the container has to be larger, and the mounting of the ceramic base material becomes complicated. In the device shown in FIG. 1, which is an example of a centrifugal separator for rotating containers, the revolution shaft 1 and the rotation transmission shaft 2 have a double structure so that they can transmit different rotational speeds.

If the revolution shaft 1 and the rotation transmission shaft 2 rotate at the same rotation speed, no rotation is transmitted between the rotation transmission gear 3 and the rotation gear 4, and therefore the container 10 only revolves. A difference in rotational speed is created between the revolution shaft 1 and the rotation transmission shaft 2 by changing the ratio of the revolution transmission pulley 7 and the rotation transmission pulley 8. Due to the difference, rotation is transmitted between the rotation transmission gear 3 and the rotation gear 4, and the container 10 rotates. Therefore, in the apparatus shown in FIG. 1, the ratio of the number of rotations of the container to the number of revolutions is determined by the ratio of the revolution transmission pulley 7 to the rotation transmission pulley 8 and the gear ratio of the rotation transmission gear 3 to the rotation gear 4. Note that the number of containers 10 may be one, or may be three or more.

The second step of supporting the catalyst component on the ceramic substrate according to the present invention
As shown in the figure. Step 11 is a step in which a slurry or solution containing a catalyst component is applied to a ceramic substrate, and the concentration and viscosity of the slurry or solution containing a catalyst component are determined depending on the shape and material of the substrate. A ceramic substrate is immersed in this slurry or solution for 30 seconds to 5 minutes to cause the slurry or solution containing the catalyst component to adhere to the surface of the substrate.

Thereafter, as shown in step 12, the revolution speed is reduced to io per minute using a centrifugal separator (see Figure 1).

to 6 f) at 0 rotation (centrifugal force of about 5 to 200 G) and rotation/revolution of 1/ to '/100 for about 20 to 120 seconds. Remove excess slurry or solution so that the catalyst component becomes a uniform coating layer. Make it.

Next, in step 13, a heat treatment step, the
C. for 2 to 10 hours. Further, if necessary, the catalyst component is coated and supported on the surface of the ceramic substrate by firing at 300'C to SOO°C in an inert gas stream such as air for 1 to 5 hours.

The removal of excess slurry or solution in step 12 is carried out by applying centrifugal force using the apparatus shown in Figure 1, but the applied G is mainly generated by revolution, and it depends on the desired amount of catalyst component supported and the substrate used. The concentration, revolution speed, rotation speed, rotation time, etc. of the slurry or solution are determined by the physical properties.

Example 1 γ- loaded with 1% by weight of platinum, 4% by weight of iron as Fe2O3, and 5% by weight of cerium as CeC2
All t Os powder was dispersed in ion-exchanged water to form a slurry to prepare a catalyst slurry having a solid content of 45% by weight (viscosity of 120 cps). A three-dimensional network structure of 20 meshes (average of 20 holes per inch length) made of cordierite was immersed in the above slurry for 1 minute to adhere the catalyst slurry to the substrate surface, and then as shown in Figure 1. It was attached to the container 10 of a centrifugal separator.

The device is rotated at a revolution speed of 300 revolutions per minute (centrifugal force of approximately 40
G) It was set so that rotation/revolution = /3o and operated for 60 seconds. Next, the network structure was taken out and dried at 150°C for 3 hours, and then calcined in air at 600°C for 2 hours to obtain a finished catalyst.

Example 2 Catalyst powder having the same composition as that used in Example 1 was used to prepare a slurry with a solid content of 40% by weight (viscosity 50 cps). A three-dimensional network structure made of cordierite with 24 meshes (with an average of 24 holes per inch of length) was
The sample was immersed in V- for 1 minute and then catalyzed in the same manner as in Example 1.

Example 3 A catalyst powder having the same composition as that used in Example 1 was used to prepare a slurry with a solid content of 48% by weight (viscosity of 400 cps). Cordierite honeycomb structure (400 cells/
2 inches) was immersed in the slurry for 30 seconds and attached to the container of the apparatus used in Example 1 with the end face parallel to the axis of rotation. The device was then operated for 30 seconds at a revolution speed of 300 revolutions per minute (centrifugal force of about 40 G) and rotation/revolution = flea.

The honeycomb structure from which excess slurry had been removed was taken out, dried at 150°C for 3 hours, and then dried at 600°C in air.
A completed catalyst was obtained by calcining at ℃ for 2 hours.

Comparative Example 1 A three-dimensional network structure of 20 meshes similar to that used in Example 1 was prepared in a state where the container of the centrifugal separator did not rotate at all (the revolution transmission pulley 7 and the rotation transmission and delivery pulley 8 rotated equally). ), and the orbital speed is 30 per minute.
Catalyticization was carried out using the same slurry and procedure as in Example 1, except for operating at 0 rotations (approximately 40 G) for 60 seconds.

Comparative Example 2 A three-dimensional network structure of 24 meshes similar to that used in Example 2 was catalyzed by the same operation as in Comparative Example 1 using a slurry obtained in the same manner as in Example 2. .

Comparative Example 3 A honeycomb structure (400 cells/square inch) similar to that used in Example 3 was immersed in the slurry obtained in the same manner as in Example 3 for 30 seconds, with one end face in the centrifugal direction. It was attached to the container of the same centrifugal separator as used in step 3, and the container was set so as not to rotate at all, and the container was rotated at 300 revolutions per minute for 30 seconds. The honeycomb structure from which excess slurry had been removed was then taken out, dried at 150°C for 3 hours, and calcined in air at 600°C for 2 hours to obtain a completed catalyst.

The dimensions of the ceramic substrate used in the above Examples and Comparative Examples are as shown in Figure 3 for the three-dimensional network structure: length: 80 mm, width: 140 mm, height: I41401.
A rectangular parallelepiped shown in Fig. 3 was used, and the ABCD plane shown in Fig. 3 was mounted on the revolution outer circumferential side and the EFGH plane was placed on the center side. A cylindrical honeycomb structure with a diameter of 4 inches and a length of 5 inches was used, and both end surfaces were oriented toward the outer circumferential side (side A) and the center side (side B).

Example 4 The ABCD plane, A plane, BFGH plane, and B plane of the ceramic substrates catalyzed in Examples 1, 2.3 and Comparative Examples 1, 2.3 were sampled to a depth of 5H, and the specific surface area of each was calculated. Measuring friend. The results are shown in Table 1.

Example 5 The catalyst obtained in Example 1 was viewed from the ABCD plane and the EFGH plane.
The specimens were cut out using a 3-diameter deep 20 mK diamond cutter to form Example 1-A and Example 1-B, respectively. Similarly, the catalysts obtained in Comparative Example 1 and Comparative Example 1-B were cut out.

The CO oxidation performance of each catalyst was measured using a desk reactor.

Reaction conditions Reaction temperature: 400°C Reaction gas: CO1% COy 10% 0.2cm H2O 10cm N2 Balance 8, V, 50,000hr' The measurement results are shown in Table 2.

Table 2

[Brief explanation of the drawing]

Figure 1 shows a cross-sectional view of an example of a revolution type centrifugal separator having an autorotation function according to the present invention. Figure 2 is a process diagram of a method for supporting a catalyst component on a ceramic substrate, and Figure 3 is an example. 1 and 2 and a perspective view of the rectangular parallelepiped three-dimensional and base-shaped structures used in Comparative Example 1.2 and Comparative Example 1.2, respectively. Patent applicant: Nippon Shokubai Chemical Industry Co., Ltd. No. 21 No. 3 Area

Claims (3)

[Claims] (1) An integrated structure made of a ceramic base material,
The structure is impregnated with a slurry or solution containing a catalyst component, and then the excess slurry or solution is removed using a centrifugal separator made up of a rotating container that is further revolved, followed by drying or further calcination. A method for supporting a catalyst component on an integrated structure made of a ceramic base material, characterized in that the catalyst component is uniformly supported on the ceramic base material. (2) The method according to claim (1), wherein the integrated structure made of the ceramic base material is a honeycomb-like monolith structure or a three-dimensional network structure. (3) Claim (1) or (2) characterized in that the rotation speed is 1/10 to 1/100 of the revolution speed.
Method described.