JPS60248215A - Purifying body for exhaust gas - Google Patents

Abstract

PURPOSE:To obtain a purifying body for exhaust gas causing cracks scarcely and having improved thermal characteristics by covering the external surface of a porous ceramic body with a nonporous ceramic film having at least one slit on the surface. CONSTITUTION:The purifying body 1 for exhaust gas is constituted of a cellular structure having three-dimensional network provided with internal communicating spaces. The purifying body consists of a porous ceramic body 2 formed to an approximately elliptic cylinder as a whole, and a nonporous ceramic film 3 covering the external surface of the porous ceramic body 2 forming two uncovered faces 2a, 2b respectively on two specified parts of the porous ceramic body 2. Slits 4 comprising recessed grooves are formed on the surface of the ceramic film 3. Preferred distance between each slit is 0.4-20cm, and preferred thickness of the ceramic film is 0.05-3mm., and preferred depth of the slit is >=1/10 basing on the thickness of the film.

Description

[Detailed description of the invention]

The present invention is a three-dimensional net-like sail having an internal communication space.
- A non-porous ceramic membrane is integrally coated on the outer surface of a ceramic porous body having a circular structure so as to form open surfaces at two predetermined locations on the outer surface of the ceramic porous body.
No. 11 relates to a gas purifying body, and particularly relates to an exhaust gas purifying body having a clay-like structure with thermal shock resistance and heat stress resistance. Conventionally, as an exhaust gas purifying body, an exhaust gas purifying body is known in which a porous ceramic body having a three-dimensional network cell structure with an internal communication space is used as a purifying carrier. This purifying body uses the internal communication space of the ceramic porous body as an exhaust gas passage.
However, in this case, it is necessary to cover the outer surface of the ceramic porous body except for the two places forming the exhaust gas inlet and outlet so that the exhaust gas passing through the internal communication space does not leak. . As a method of coating the outer surface of such a porous ceramic body, there is a method of using a non-porous ceramic membrane. A ceramic porous body whose outer surface is coated with a Lamic membrane is subject to thermal shock and thermal stress when high-intensity IJI gas passes through it, and cracks easily occur in the non-porous ceramic membrane. 1 of the three-dimensional network inside as a result of the destruction?
There is a problem in that it also causes destruction of the ceramic porous body having a pore structure. Therefore, as a measure to increase the strength against thermal shock caused by rapid temperature changes and thermal stress caused by non-uniformity of heated stones, materials or compounds that reduce the thermal coefficient of 111 of the ceramic porous body and its covering hyalmic membrane are used. Although the measures mentioned above have been taken, there are limits to these measures alone, so it is desired to develop new methods to further improve thermal properties such as thermal shock resistance.
This was done in view of the above circumstances, and it's hot! i impact, thermal stress is applied~1;) Coating the outer surface of the ceramic porous body
It is an object of the present invention to provide an exhaust gas purifying body which has improved thermal properties by preventing cracks from forming in a non-porous ceramic membrane. That is, in order to achieve the above object, the present invention provides at least one sulin I~ on the outer surface of a ceramic porous body having a three-dimensional network cell 4R structure having an internal communication space. A non-porous ceramic membrane is integrally coated at two predetermined locations on the outer surface of the ceramic porous body so as to form a diagonal. According to the exhaust gas purifying body according to the present invention, By providing slits in the non-porous ceramic membrane that covers the outer surface of the porous ceramic body, it can respond well to temperature changes caused by repeated passage of high-temperature exhaust gas, and can resist rapid contraction or expansion due to thermal shock, etc. It effectively absorbs the deformation caused by the ceramic membrane and prevents the occurrence of cracks in the ceramic membrane, and prevents cracks from occurring in the ceramic membrane. The present invention will be further explained below with reference to the drawings. FIGS. 1 and 2 each show an embodiment of the exhaust gas purifying body of the present invention. This exhaust gas purifying body 1 has a three-dimensional network cell structure with an internal communication space, and has an approximately elliptical cylinder shape as a whole. The outer surface of the ceramic porous body 2 is formed so as to form -4- open surfaces 2a and 21+ at two predetermined locations (both end faces in the axial direction in the drawing) of the ceramic porous body 2. A non-porous ceramic membrane 3 is coated on the surface of the ceramic membrane 3, and a groove-like slit 4 is formed on the surface of the ceramic membrane 3. This exhaust gas purifying body 1 has one open hl! The surface 2a is the exhaust gas inlet, and the other open surface 2b is the 11F gas outlet. The exhaust gas that has flowed into the internal communication space of the porous body 2 is treated while flowing through this internal communication space, and the treated exhaust gas flows out from the exhaust gas outlet 1] (the other side 11 and 2h). , in the embodiment of FIG. 1, the slit is IJ1
This is an example in which a plurality of slits are formed at a predetermined distance from each other along the gas traveling direction (in the direction of the arrow in the figure), and in the embodiment shown in FIG. At the same time, in the direction perpendicular to these slits (
In other words, this is an example in which a plurality of slits are formed (along the circumferential direction) and slits are formed in a lattice pattern.
Cracks in the ceramic membrane 3 and the ceramic porous body 2 can be more reliably prevented, and as shown in the figure, the slits are formed at least in the direction orthogonal to the thermal stress, that is, along the traveling direction of the exhaust gas. It is excellent in terms of crack prevention effect. In addition, it is preferable to form a plurality of slits as shown in the figure, but in this case, the interval between the slits is 0.4 to 2.
0CI11. In particular, it is preferably 1 to 10c+n. However, the number of slits is not necessarily plural (or may be one in some cases). Also, the slit formation mode is not limited to the illustrated embodiment. The thickness of the ceramic membrane can be selected depending on the usage conditions of the exhaust gas purifier and the product application, but it is usually 0.05 to 3 mm, preferably 0.2 to 11 ww1. The depth is preferably 1/10 or more, particularly 1/2 to 9/10, of the thickness of the non-porous ceramic membrane.
Depending on the size of the ceramic porous body, the slit can be set as appropriate.

[1] can be adopted, but 0.1~
4, particularly preferably 0.5 to 1111 Wl. Moreover, the ceramic porous body is made by adhering ceramic slurry to a flexible polyurethane foam without a cell membrane 11, and by sintering this, the soft polyurethane foam is carbonized and removed, resulting in +IL! It is preferable to use a manufactured
This J: We decided to form a ceramic porous body from a flexible polyurethane foam that does not have a sea urchin membrane.A cylindrical ceramic porous body consisting only of the ridges of a regular dodecahedron was obtained, and this has a large porosity. Therefore, the exhaust gas passes through with less pressure loss, and since the internal communication space is intricate, the exhaust gas reliably contacts the grid when passing through the internal communication space, resulting in efficient processing. Here, the shape of the ceramic porous material is not limited to the elliptical columnar shape as shown in the figure, but can be changed in various ways. Further, the material of the ceramic porous body is not particularly limited as it is selected depending on the usage condition f1, but it is preferable to use alumina, mullite, zircon, aluminum ditanate, ricia, or cordierite. In this case, it is not possible to use a non-porous material (substantially the same material as the ceramic porous body) for the ramic membrane. In the present invention, there are no particular restrictions on the method for coating the outer surface of the ceramic porous body with the non-porous ceramic membrane provided with Surin 1, but for example, , A method of physically scraping a predetermined part of the slurry surface and submerging the Surin 1- before the slurry dries, ■ A method of applying ceramic slurry to a predetermined thickness on the outer surface of the ceramic porous body and then forming it. A method of placing a member having the same shape as the slit (for example, a net), then coating the -F with ceramic slurry by spraying, etc., removing the member, and providing Surin 1~ corresponding to this member, ■ Cerami Two 8 - After applying the ceramic slurry to the outer surface of the porous body at a predetermined angle and removing the number, apply a water repellent (silicone oil, etc.) to prevent the ceramic slurry from adhering to the specified location, and then coat the ceramic slurry. Various methods can be adopted, such as installing a slit corresponding to the water repellent area. The exhaust gas purifying body of the present invention can be obtained by drying and sintering the ceramic slurry provided with slits using this method. As explained above in Section 1, the present invention provides a non-porous ceramic membrane having at least one slit on the outer surface of a ceramic porous body having a three-dimensional network cell structure having an internal communication space. Since the outer surface of the ceramic porous body is integrally coated to form open surfaces at two predetermined locations, the thermal shock resistance and thermal stress resistance are improved, and the temperature difference (high temperature - room temperature) with respect to the exhaust gas purifying body is improved. Even if this occurs repeatedly, cracks are unlikely to occur in the non-porous ceramic membrane. For example, if there are no slits in the ceramic membrane, 7
While cracks occur at 00°C, in the case of Example -9= shown in the figure, cracks do not occur up to 900 to 950°C. Therefore, according to the present invention, it is possible to eliminate leakage of exhaust gas flowing into the ceramic porous body and to reliably treat the exhaust gas. Regarding this point, heat l1iv1. The actual test result of 11 is shown below. [Example, Comparative Example] Ceramic slurry containing cordierite as a main component was adhered to an elliptical cylinder-shaped flexible polyurethane foam without a cell membrane, dried and sintered to have a major axis of 280wnn. An elliptical ceramic porous body with a minor axis of 120 mm and a height of 60TIII11 was prepared, and the outer circumferential surface of this ceramic porous body was coated with a non-porous ceramic film having a thickness of 1 mm to prepare a sample. In this case, the sample used was Example 1, in which slits were formed on the surface of a non-porous ceramic membrane as shown in Figure 1.
), Example VIJ2 had slits formed as shown in Figure 2 (slit width 0.5n, slit spacing 10wm), and Comparative Example -10-b without slits. Each was used. Next, the above sample 11 was placed in a heated JF, and the temperature was increased in 50°C increments, and the test was continued until cracks or damage occurred in R1 (R1).In this case, the holding time was about 1 hour, and the J image was Placed in a dry room.The binding is shown in the table below.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 each show an embodiment of the present invention.
There is a perspective view. 1... Exhaust gas purifying body, 2... Ceramic porous body. 2ay21)...between 1k surface, 3...non-porous ceramic base, 4...slit. -11-

Claims (1)

[Claims] 1. A non-porous ceramic membrane having at least one slit on the outer surface of a ceramic porous body having a three-dimensional network cell structure having an internal communication space; 1. A 1JI gas purifying body, characterized in that the outer surface of the porous body is integrally coated to form open surfaces at two predetermined locations. 2. The exhaust gas purifying body according to claim 1, wherein the depth of the slit 4-1 provided in the non-porous ceramic membrane is 1/10 or more of the thickness of the ceramic membrane. 3. A gas purifying body according to claim 1 or 2, wherein the plurality of slits are spaced apart from each other by 0.2 to 2 ocyn and are formed in substantially the same direction as the exhaust gas traveling direction.