JPS6271548A - Monolithic catalyst carrier and its production - Google Patents

Abstract

PURPOSE:To prevent the ejection of a ceramic packing material for reinforcement by using a ceramic material having air permeability for at least one of the ceramic materials packed to both front and rear open ends of the vent holes of a monolithic catalyst carrier. CONSTITUTION:This invention relates to the carrier of the monolithic catalyst to be used for cleaning up the exhaust gas of an automobile, in which the material having air permeability is used for the ceramic packing material 12 at least either open end of the ceramic packing materials 12 packed into both front and rear open ends of the vent holes 11 on the outermost circumferential side. Then the air sealed into the vent holes leaks from the air permeable ceramic packing material side to the outside even if the air expands thermally during the calcination. A pressure increase in the vent holes is thus obviated and the ejection of the ceramics for reinforcement is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a monolithic catalyst carrier used for purifying automobile exhaust gas and a method for producing the carrier.

As is well known in the art, the monolithic carrier used for automobile exhaust gas purification is a ceramic honeycomb-shaped @reductor in which a catalytic material is supported on the inner circumferential surface of the vent holes. It has the advantages of a wide surface area and excellent heat resistance. In this type of catalyst carrier, in order to increase the porosity as much as possible, it is desirable to make the partition walls forming the vents thinner, but as the partition walls become thinner, the mechanical strength decreases, and the exhaust gas Tightening when assembling into a system increases the risk of breakage due to pressure and vibrations associated with driving the engine.

By the way, monolithic catalysts are generally fixed by fitting them into a cylindrical container and pressing the outer periphery of both ends in the axial direction with retainers. , it no longer functions to purify waste scum. Conventionally, in order to prevent a decrease in physical strength due to thinning of the ventilation hole partition wall, the ventilation hole near the outer periphery that is closed by the retainer has been used for reinforcement. Showa 5
6 129042M discloses a ceramic honeycomb structure in which openings at both ends of a ventilation hole near the outer periphery are filled with ceramic to prevent chipping of the ends.

Problems to be Solved by the Invention As mentioned above, when filling the opening end of the ventilation hole with ceramic for reinforcement, as described in the above-mentioned Japanese Patent Application Laid-Open No. 56-129042, A method of filling ceramic material in the form of a slurry and firing it to solidify it is considered to be advantageous in terms of workability and required equipment, but conventionally known methods have the following problems. There was a point.

That is, when filling both ends of the vent holes 2 on the outer periphery of the honeycomb structure 1 with ceramic 3 as shown in FIG. 4, there is a method in which both ends are simultaneously filled with slurry ceramic 3 and fired. 11, or by filling one end with slurry ceramic 3 and firing it, and then filling the other end with ceramic 3 in the same way and firing it. In either method, firing is performed with both ends closed by the ceramic 3, so the air confined within the vent 2 thermally expands, resulting in a type of bumping phenomenon and complete firing. The ceramic 3 that has not yet solidified is blown away, and the scattered ceramic lumps 4 are as shown in Fig. 5.
It may adhere to the open end of the vent hole 2 on the center side and seal the vent hole 2, or it may rise over the open end side of the vent hole 2 on the outer periphery and cause inconvenience when storing the monolith converter container l\. Problems arise.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a monolithic catalyst carrier in which reinforcing ceramic fillers do not eject, and a method for producing the same.

Means for Solving the Problems In order to achieve the above object, the monolithic catalyst carrier of the present invention has a ceramic material filled in both the front and rear open ends of the vent, and the ceramic material in at least one of the open ends. It is characterized by being breathable.

In addition, the method of the present invention, when forming ceramic fillers at both end openings of the vents near the outer periphery of a structure for a catalyst carrier in which a large number of vents are formed, uses combustible materials that are flammable and scattered at temperatures below the firing temperature. This method is characterized in that a ceramic slurry mixed with a biological substance is filled into at least one open end and fired to form a reinforcing ceramic filler that allows ventilation.

Effect: According to the catalyst carrier and manufacturing method of the present invention, when the air sealed in the vents undergoes thermal expansion during firing, it leaks to the outside from the air-permeable ceramic material side, thus causing a pressure increase in the vents. Since this does not occur, ejection of the reinforcing ceramic material is prevented.

DETAILED DESCRIPTION OF THE INVENTION As described above, the monolithic catalyst carrier of the present invention has a structure in which a ceramic filler for providing air permeability is provided at the open end of the vent hole in the outer periphery, and this is illustrated in FIGS. It is as shown in Figure 2.

That is, the carrier structure 10 is a honeycomb-shaped ceramic cylindrical body in which a large number of ventilation holes 11 are formed along the axial direction. i.e. porous) ceramic filler 12
is provided at a predetermined length, and a non-porous ceramic filler 13 is provided at the other open end. These ceramic fillers 12 and 13 are for reinforcement, and are made mainly of alumina, for example.

Each ceramic filler 1 provided in the above combined structure 10
2.13 can be formed by drying and firing the ceramic slurry at 92. During the firing, the air in the vent hole 11 blocked by the ceramic slurry thermally expands and the porous ceramic Ceramic filling iJ'12. leaks to the outside from the filling material 12 side.
13 will not be scattered.

In addition, the above-mentioned groove reflux body 10 is made into a monolithic catalyst by coating and supporting catalyst components in the open vent holes 11. Then, as in the conventional case, it is inserted into a predetermined container and fixed by pressing the outer periphery of both ends with a retainer, but since the parts that contact the retainer are reinforced with the filler material 12 and 13, there is no risk of breakage. do not have. Furthermore, since the fillers 12 and '13 are in surface contact with the retainer, the contact area is wider than before, and the sealing performance is improved.

Therefore, even if the porous ceramic filler 12 is installed on the upstream side with respect to the exhaust gas, there is almost no risk that the exhaust gas will enter the vent hole 11 on the outer periphery. Even if a gap occurs, filler 1
Since the opening diameter of the micropores 2 is extremely small and the flow resistance is large, it is difficult for the exhaust gas to enter the vent hole 11, and even if the exhaust gas roughly enters the vent hole 11 on the outer periphery, the other ceramic filler 13 can close the vent hole 11. Since it is closed, there is no risk of exhaust gas being emitted unpurified. Furthermore, even if the partition wall of the vent hole 11 on the outer periphery is damaged and communicates with the vent hole 11 on the center part, there is almost no possibility that exhaust gas will enter the vent hole 11 on the outer periphery; Exhaust gas leaking from the vent hole 11 to the center vent hole 11 is purified by the catalyst and then discharged, so that no particular trouble occurs. Hey,
Since it is necessary to prevent exhaust gas from flowing into the vent hole 11 provided with the filler 12 and 13, it is preferable to place the non-breathable ceramic filler 13 on the upstream side.

Next, the method of the present invention for producing the above-mentioned carrier will be explained.

First, a ceramic honeycomb-shaped m-return body with a number of ventilation holes is prepared, and a mask plate is attached to the center of one end of the body, leaving the outer periphery that sometimes comes into contact with the retainer. Close.

In this state, it is immersed in a predetermined ceramic slurry, and the vent holes on the outer periphery are filled with the ceramic slurry. Here, the ceramic slurry used has a composition containing a substance, such as carbon, that burns and scatters at the firing temperature. After filling the ceramic slurry, it is dried in a heated bag at a predetermined temperature, and then fired and solidified. During this process, combustible substances such as carbon are burned and scattered, so the filler made of 1q becomes porous and has air permeability.

After providing the filler on one end as described above, the other end is similarly filled with a ceramic slurry containing no combustible substances such as carbon, which is then dried and fired. During this second drying and firing, the vent holes on the outer periphery are closed with the fired and solidified filler and the ceramic slurry, but the already fired ceramic filler has air permeable porous holes. However, the air trapped in the vents expands during combustion and leaks outside through the breathable ceramic filler, so the internal pressure does not increase.
Ceramic slurry is not blown away.

One free time: Shiri Next, examples of the method of the present invention will be described together with comparative examples.

Example A mask plate with a diameter of 100 pieces is attached to the center of the downstream end face of a carrier honeycomb @ crushed body with a diameter of 107 seconds, a length of 111.3 AI72, and a number of ventilation holes of 400 per square inch. The outer vent hole was filled with the ceramic slurry.

Ceramic slurry Nialumina Silua 00! ? (Alumina Kisso 1i1Qwt
%), aluminum nitrate water) 8 liquid 15CXJ (40wt
%), aluminum 100 (1), carbon 1009, and distilled water 450 rJ.

After the ceramic slurry was optically filled into the outer circumferential ventilation hole at the downstream end, the mask plate was removed and dried at 200'C for 1 hour, and then fired at 700'C for 2 hours.

For the upstream end, the process was the same as above, except that a ceramic slurry with a composition obtained by removing the force pump from the above composition was used. Filling, drying, and firing of ceramic slurry I did it.

A ceramic slurry with carbon removed from the composition of the ceramic slurry used in the Toretsukan example was used, and the other points were the same as in the above example. Fill the ventilation hole with ceramic slurry,
'F2 dried and fired.

FIG. 3(A>(B)) is a schematic view of the upstream end surface of the obtained carrier, and in the 'J1 example of the present invention shown in FIG. Street ceramic filling material 13
was formed. On the other hand, in the comparative example shown in FIG. 3(B), the alumina lumps 14 were scattered at many locations on the upstream end face, unnecessarily clogging the ventilation holes.

In addition, each of the obtained carriers was coated with alumina, and then 1g of Pt and 0.1g of Rh were supported per unit length to form a monolithic catalyst.This was incorporated into an engine and tested in an actual machine. We investigated the purification performance of As a result, the purification ability of the monolithic catalyst according to the uninvented example was better than that of the comparative example 1. This seems to be because in the comparative example, there were vent holes that were unnecessarily blocked, resulting in less catalyst components contributing to moss for exhaust gas purification.

Effects of the Invention As is clear from the above explanation, according to the carrier of the present invention and its manufacturing method, ceramic slurry is used for reinforcement.
When filling and drying and firing, the air trapped in the vent hole can be released, so there is no scattering of the ceramic slurry, and there is no need to prevent unnecessary blockage of the vent hole or B leakage to the end surface side. Fixation defects can be effectively prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a carrier according to the present invention;
Fig. 2 is a front view thereof, Fig. 3 (A>(B) is a schematic diagram showing the end portion of the carrier obtained by the example and comparative example of the method of the present invention, and Fig. 4 is a cross section showing a conventional carrier. 5 is a cross-sectional view showing a state in which the ceramic slurry is scattered. 10...Structure for carrier, 11...Vent hole, 12
...Breathable ceramic filling material, 13...
Non-porous ceramic filling.

Claims (2)

[Claims] (1) In a monolithic catalyst carrier in which a large number of ventilation holes are formed and the ventilation holes near the outer periphery at both front and rear ends are filled with a ceramic filler, at least one of the fillers in the openings is filled with a ceramic filler. A monolithic catalyst carrier characterized in that the filler at the open end is an air-permeable filler. (2) When forming a ceramic filler at the openings at both ends of the ventilation holes near the outer periphery of the catalyst carrier structure in which many ventilation holes are formed, at least one opening end is burned at a temperature higher than the firing temperature. A method for manufacturing a monolithic catalyst carrier, comprising filling the monolithic catalyst carrier with a ceramic slurry mixed with a scattering combustible material and firing the ceramic slurry to form an air-permeable ceramic filler.