JPS59193140A - Process for coating of monolithic carrier with alumina - Google Patents

Abstract

PURPOSE:To reduce the amt. of activated alumina to be used, and also to reduce the amt. of a noble metal to be carried afterward by coating activated alumina only on the inside wall of cell of a monolithic carrier. CONSTITUTION:Both end surfaces of an external peripheral wall of a monolithic carrier 11 are sealed by cylindrical bodies 12, 13 having an inside wall formed to an almost same shape as the sectional shape of the monolithic carrier. Activated alumina M is charged to the upper cylindrical body 13 and sucked by a previously evacuated tank 1 to let the activated alumina to pass through the inside wall of the cell of the monolithic carrier 11 and is coated thereon. Namely, since the activated alumina contained in the upper cylindrical body 13 is passed through the inside wall of the cell of the monolithic carrier utilizing the differential pressure which can be generated between the evacuated tank 1 and the upper cylindrical body 13, there is no fear of causing sticking of the activated alumina to the external peripheral wall of the monolithic carrier. Only the inside wall of the cell is coated with the activated alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for coating monolithic supports with alumina.

Conventionally, a natural sedimentation immersion treatment method as shown in FIG. 2 has been adopted as an alumina coating method for a monolith carrier during the production of a monolithic catalyst for purifying exhaust gas for automobiles. Zunawa, the monolithic carrier 50 is housed inside a container 51 with a hole 51a opened at the bottom, and the container 51 is
Activated alumina 52 whose main component is T-alumina powder etc.
The activated alumina 52 is charged from the top of the adjustment tank 53 containing the activated alumina 52 and
Activated alumina 52 is infiltrated through the hole 51 a opened at the bottom of the container 51 to coat the inner and outer walls of the monolithic carrier 5 ( ) with a certain amount of activated alumina 52 , and then the monolith carrier 5 ( A method is used to take out the activated alumina 52 and remove excess adhering activated alumina 52 using air or the like.

However, in such a natural sedimentation immersion treatment method, since the monolithic carrier 50 is completely immersed in the adjustment tank 53 in which the activated alumina 52 is stored, the activated alumina is absorbed even to the outer peripheral wall of the monolithic carrier 50 that does not contribute to the catalytic function. 52 is coated and the noble metal that is subsequently processed is also supported. For this reason, an unnecessary amount of activated alumina 52 is coated, and an unnecessary precious metal is supported, which causes a problem of significantly increasing the product cost.

The present invention was made to solve the above-mentioned problems, and the purpose is to coat only the inner walls of the cells of the monolithic carrier with activated alumina, thereby reducing the amount of activated alumina and precious metals used. The purpose of the present invention is to provide an alumina coating method.

The above object of the present invention is to cover both sides of the outer peripheral wall of the monolithic carrier.
It is sealed by a cylindrical body whose inner shape is approximately the same as the one-sided shape of the monolithic carrier, and activated alumina is charged into the upper cylindrical body, and the activated alumina in this cylindrical body is depressurized in advance. This is achieved by a method for coating a monolithic carrier with alumina, which is characterized in that activated alumina is passed between the inner walls of the cells of the monolithic carrier and coated with the activated alumina by applying suction through a reduced pressure tank.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic front view of the apparatus used to carry out the coating method of the present invention. In Figure 1, 1
is a pressure reducing tank formed in a popper shape, and a conduit 2 is connected to the side wall 1a of this pressure reducing tank 1, and a pressure gauge 3 is provided in the middle of this conduit 2. A vacuum pump 4 is provided at the tip of 2. The bottom part 1b of the decompression tank 1 is shaped like a funnel.
A discharge pipe 5 is connected to the exhaust pipe 5, and in the middle of this discharge pipe 5, a HAL PRO is provided, and a pump 7 is provided behind the HAL PRO.

A suction pipe 8 is connected to the upper part 1c of the decompression tank 1, and a valve 9 is provided in the middle of the suction pipe 8, and a popper-shaped valve is provided at the tip of the suction pipe 8. A saucer 1o is provided. Furthermore, this saucer 1
A flange 10a is formed on the upper part of the 0, and a lower cylindrical body 12 is placed on the upper part of the flange 10a to seal the lower outer circumferential wall end surface of the monolithic carrier 11 formed of copillite or the like. An upper cylindrical body 13 is placed above the carrier 11 to seal the end surface of the upper outer circumferential wall. The upper cylindrical body 13 and the lower cylindrical body 12 are formed with through holes 12a and 13a, respectively, which have substantially the same shape as the monolithic carrier 11 on the inside in order to seal both end surfaces of the outer peripheral wall of the monolithic carrier 11. has been
The through holes 12a and 13a are formed smaller than the outer shape of the monolithic carrier 11, and grooves 12b and 13 inclined toward the center are provided at the contact portion with the monolithic carrier 11.
b are formed respectively. Note that M is activated alumina whose main component is γ-alumina powder.

When coating the monolithic carrier 11 with activated alumina M, first close the valve 9 of the suction pipe 8 and the HALPRO of the discharge pipe 5 provided in the upper part 1c and the bottom part 1b of the decompression tank 1, and A vacuum pump 4 installed at the tip reduces the pressure in the decompression tank 1 to a predetermined level (for example, 3
00111K +18). Next, the monolith carrier 11
An upper cylindrical body 13 and a lower cylindrical body 12 are provided on both end surfaces of the outer peripheral wall of the
The grooves 13b and 12b are brought into contact and sealed, and the lower cylindrical body 12 is placed on the flange 10a of the saucer 10. After that, activated alumina M is inserted into the through hole 13a of the upper cylindrical body 13.
is introduced in an amount of 0.2 to 1.5 times the volume of the monolith carrier 11, and the valve 9 of the suction tube 8 is opened. At this time, a pressure difference is created between the pressure reducing tank 1 and the upper cylindrical body 13, and the activated alumina M accommodated in the upper cylindrical body 13 is sucked and passes between the inner walls of the cells of the monolithic carrier 11 to reduce the pressure. It is accommodated in tank 1. Then, when the activated alumina M passes between the inner walls of the cells of the monolithic carrier 11, the inner walls of the cells are coated with the activated alumina M. This results in
Activated alumina M can be coated only on the inner wall of the cell without adhering to the outer peripheral wall of the monolithic carrier j1.

As explained above, in the alumina coating method of the present invention, both end surfaces of the outer peripheral wall of the monolithic carrier are sealed by a cylindrical body whose inner shape is approximately the same as the cross-sectional shape of the monolithic carrier, and the upper Activated alumina is charged into the cylindrical body, and the activated alumina in the cylindrical body is sucked into a vacuum tank that has been depressurized in advance, and the activated alumina is passed between the inner walls of the cells of the monolithic carrier to coat it. A pressure difference can be generated between the tank and the upper cylindrical body, and the activated alumina housed in the upper cylindrical body can be passed between the inner walls of the cells of the monolithic carrier using the differential pressure. As a result, the activated alumina does not adhere to the outer peripheral wall of the monolithic carrier (it has the effect of coating only the inner wall of the cell).Therefore, the amount of activated alumina used can be reduced, and the amount of activated alumina that is later supported can be reduced. There is a rhinoceros fruit that can also reduce precious metals.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of an apparatus used to carry out the coating method of the present invention, and FIG. 2 is a schematic cross-sectional view of the apparatus for explaining the conventional coating method. L----Reducing pressure tank 1a----One side wall 1b-------Bottom part 1c----One upper part 3---One pressure gauge 4------Vacuum pump 5---One discharge Pipe 6.9 ---- Valve 7 ---- Pump 8 ---- One suction tube 10 - - One - = - Receiver 10 a - One - Flange 11 ---- Monolith carrier 12 ---- - Lower cylindrical body 12 a --- Consistent through hole 12 b --- One groove 13 --- One upper cylindrical body 13 a --- Continuous through hole 13 b --- Q Mizide Toyota Motor Co., Ltd. - Figure 1

Claims (1)

[Claims] Both end surfaces of the outer peripheral wall of the monolithic carrier are sealed by a cylindrical body whose inner shape is approximately the same as the cross-sectional shape of the monolithic carrier, activated alumina is charged into the upper cylindrical body, and the cylindrical body 1. A method for coating a monolithic carrier with alumina, which comprises sucking activated alumina into a vacuum tank that has been previously depressurized, and coating the monolithic carrier by passing the activated alumina between the inner walls of the cells of the monolithic carrier.