JPS62117633A - Production of monolithic catalyst - Google Patents

Abstract

PURPOSE:To obtain the titled catalyst having high activity even after long use by dipping a monolithic catalyst carrier into a soln. contg. the catalytic component from one end at a specified speed while placing the other end at the upper part at all times to deposit more catalytic component on the one end and then baking the material. CONSTITUTION:The monolithic catalyst carrier is obtained by coating alumina on a columnar monolith catalyst carrier base material of a honeycomb structure, etc., made of cordierite, etc. The monolitic carrier 4 is hung by a holder 3 and dipped in the liq. 6 contg. a catalytic component such as platinum in the axial direction. The dipping velocity can be made constant, increased or decreased or even dipping can be temporarily stopped. The material is dried after dipping and a catalyst having the concn. distribution of the catalytic component in the flowing direction of the exhaust gas can be obtained. The catalyst carries less catalytic substance on the upstream side of the exhaust gas where catalyst poisons such as Pb and P are easy to deposit and carries more catalytic substance on the downstream side. Consequently, the catalytic component purifies the exhaust gas effectively and the durability is also enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention relates to a method for producing a monolithic catalyst that reduces deterioration during shedding. This provides a J-building method.

The monolithic catalyst produced by the method of the present invention has excellent durability and maintains high catalytic activity even after long-term use.

[Prior art 1] Exhaust gas purification catalysts, under actual conditions of use, do not contain catalyst pollutants (lead (Pb) in fuel, phosphorus (in oil)).
P) etc.> are deposited more on the upstream side of the exhaust gas. Therefore, the catalytic activity of J5 in the upstream portion is extremely low.
In some cases, after long-term use, the catalyst performance deteriorates significantly.

In view of this drawback, a monolithic catalyst has been conventionally provided in which the catalyst component is increased from the upstream side of the exhaust gas to the downstream side of the exhaust gas and is temporarily retained (Japanese Patent Application Laid-Open No. 52-56091). As a method for producing a monolithic catalyst having a deep slope, for example,
As shown in Japanese Patent Application No. 85, there is a method in which a certain amount of catalyst component-containing liquid equal to the water absorption m of a monolithic carrier is introduced from one end of the carrier.

[Problems that R Ming tries to solve] However, in the above method, the amount of water absorbed by the monolithic carrier is
The thickness of the supporting layer such as activated alumina, the drying state of the supporting layer,
Furthermore, it fluctuates depending on the humidity in the air, etc. Therefore, it is extremely difficult to obtain an optimal concentration distribution that compensates for the degree of decrease in catalyst performance in the axial direction.

The present invention has been devised in view of the above circumstances, and provides a method for manufacturing a monolithic catalyst having an optimal concentration distribution of catalyst components, which compensates for the performance degradation of the monolithic catalyst by matching the degree of decline in the axial direction. This is what we provide.

[Means for Solving the Problems 1] The present invention is a method for producing a monolithic catalyst characterized by a method of supporting catalyst components.

That is, the present invention provides a monolithic catalyst 11 on which a melting medium supporting layer is formed.
One end of the body is always held up and the other end is always held down, and the other end is immersed into the IIIr catalyst component ah solution at a predetermined rate so that the other end has more of the catalyst component, It is characterized in that it is then fired.

The configuration requirements will be explained below.

A monolith catalyst carrier is a monolith catalyst base material with a support layer formed thereon.

The monolith catalyst base defines the external shape ζ of the catalyst, and its material is generally cordierite, but other materials such as mullite, spinel, or heat-resistant metals may also be used. The base material has a honeycomb structure with a large number of pores (100-600 pores/square inch) extending in the direction of exhaust gas flow, and an integrally molded structure with a three-dimensional network structure, and its outer shape is columnar. (A shape that matches the internal shape of the exhaust system in which the monolithic catalyst is to be installed, such as a cylinder or a square pillar).

The catalyst support layer is formed by applying a fluid such as a slurry containing the support layer components to the surface of the E Norris catalyst base material. JsaUl
After that, it is dried and fired.

In addition to activated alumina, known components such as titanium oxide (TiOz) and zirconium oxide (7roz) can be used as supporting layer components.

A feature of the present invention is that the direct immersion speed is adjusted in accordance with the supporting speed of the catalyst component.

Here, the supporting speed of the catalyst component is influenced by the concentration of the remaining catalyst component in the solution. That is, as the catalyst component concentration decreases, the loading rate decreases. Incidentally, the supporting speed can be determined uniquely from the catalyst component content 1d in the solution.

In addition, the immersion speed is the immersion amount [%] of the monolithic catalyst carrier.
(Axial dipping with one end always up and one end down) Ratio of increment to time.

Therefore, if the immersion time is the same, the faster the supporting speed is, the more catalyst components will adhere to the support 1.1 layer. On the other hand, if the supporting speed is the same, the dipping speed is faster, and the shorter the dipping time in the same part, the less the supported layer is in the same part.

The soaking speed may be constant, gradually decreasing or increasing. Alternatively, it may be temporarily set to O (ie, stopped state).

In addition, as catalyst components to be supported, platinum < Pt, palladium (Pd), which are conventionally known catalyst components, are used.
, Iridium (Irl Ruthenium (Ru), Rhodium (
Rh), osmium (O5>, etc.) or chromium (Cr>, nickel (Ni>, vanaji cum)
V), copper (Cu), etc.! ;Ii1 combination etc. can be used. Incidentally, during the immersion, the one end of the carrier may be kept protruding from the surface of the aqueous solution at all times.

[Example 1 The present invention will be explained below based on specific examples.

(1) Production of Rimples Examples Sample 1.2 and Comparative Rimples were produced according to the following procedure. In addition, in producing each sample, we used a monolith catalyst base material (honeycomb structure made of cordierite, φ93 x 100, cell density 400 cells/square inch) and alumina slurry (mixed and stirred activated alumina powder, aluminum sol, and water). A common one was used.

(Example Sample 1) The monolithic catalyst II material was immersed in the alumina slurry described in F, pulled up, dried, and fired to form a catalyst support layer.The monolithic catalyst support was 100g.
Met.

FIG. 1 is an explanatory diagram showing the process of manufacturing an example package.

As shown in the figure, there is a slide 12 on the rotating shaft of the Nervo motor 1.
is fixed, and the monolith carrier 4 is suspended by a holder 3 attached to the other end of the wire, one end of which engages with the pulley 2. Here, as the rotation shaft of the motor 1 rotates, the monolith carrier 4 is immersed in the catalyst component-containing liquid 6 in the water tank 5 in the axial direction a.

Now, the monolithic catalyst carrier is attached to the holder 3, and the motor 1 is driven to make the immersion degree approximately uniform in the dinitrodiammine platinum aqueous solution [Pt (N+-13> 2 <NO2) 2 ] in the water tank 5. and reduce the immersion amount from 0% to 10% in 20 minutes.
0%, and then immersed as it was (405).

Next, dry and use the same method to obtain a rhodium chloride aqueous solution (Rh).
CR3) kj, 2iQ, dry shite, support m KaP t
=i, oqz' sentence, [to mah=o, 1] ,,/monolith catalyst 8 of the sentence (q.

(Sample 2 of Example) Example (1 Sample 2 is almost the same as Example Sample 1. The difference is that the suspension of the support layer is 9E5q, and the immersion in the aqueous solution is performed as follows. This is a memorial service for the deceased.
Dip in dinitrodiammine platinum aqueous solution at 10% for 15 seconds, then immerse at 10% for 30 seconds, immerse at ff130% Te30
seconds, N ia ffi 40% r, 45 seconds, 5
1 minute each at 0%, 60%, and 70%, 2 minutes at 80% soaking level, 3 minutes at 90% soaking amount, 50 minutes at 1006,
It was soaked for 8160 minutes. Also, immerse iFt in the aqueous solution of 1]dium chloride in the same way (0 serial number is Pt-1,09/J!
, Rh-0.1 g, /monolith catalyst B (q).

(Comparative Example Sample) The comparative example sample was the same as the above example sample up to the formation of the catalyst support layer, and the suspension of the support layer was 100q.

The entire monolithic catalyst was simultaneously immersed in a dinitrodiammine platinum aqueous solution for 60 minutes, dried, and then similarly immersed in a rhodium chloride solution until the supported amount was Pt=1. Oq/l
Monolithic catalyst C with Rh=0.1Q/1 was prepared at 1:7.

(2) Results of sample production Figure 2 shows the lfl retention rate and dipping rate of platinum in Example Sample 1, and Figure 3 shows the platinum holding rate and dipping rate in Example Sample 2. In addition, substantially the same loading speed and dipping speed were used for rhodium.

Further, FIGS. 4 and 5 show the catalytic components of Sample 1.2 of Example 1.2 and Comparative Example.

That is, Fig. 4 shows the 11 suspension of the plastic arp in the axial position, and Fig. 5 shows the IEI of rhodium in the axial position.
18 fit is shown. As shown in FIGS. 4 and 5, the amount of catalyst metal supported in the axial direction is proportional to ia+
! It can be controlled by the immersion rate corresponding to it.

Here, it is easy to set the dipping speed to a predetermined value. Therefore, in the axial direction d31. According to the present invention, it is also easy to specify the desired value of the carrier layer.

(3) Plan The performance of each tumble made as described above was evaluated as follows.

First, each lean pull was held in a metal container (converter) with the side with the least amount of PT and Rh carried on the exhaust gas inflow side, and was attached to the engine exhaust system of a vehicle to simulate city driving. The pattern was run for 2001L'j.Next, each rimple reached 1!' on a 2°8 liter L engine with 1111 air suspension, and the engine was 20QQrplTT, -
3801111Il [1g of exhaust gas operated under the conditions is introduced into the catalyst to generate hydrocarbons (HC), -carbon oxides (CO)
, the purification rate of nitrogen oxides (NOx) was measured. The results are shown in Figure 6.

As can be seen from FIG. 6, the catalytic activity of Example Rimple 1.2 was higher than that of the Comparative Example after being used for a long time. This is because, as a result of immersing the Norris catalyst carrier into an aqueous solution containing catalyst components at a predetermined rate as described above, the amount of catalyst components supported was small at the top of the Norris catalyst and increased at the bottom, resulting in the presence of toxic substances. This is thought to be because there is less catalytic material near the exhaust gas inlet side, where most of the poisonous substances adhere, and more catalytic material on the downstream side, where almost no toxic substances adhere, so that the catalytic components effectively perform the purifying function.

[Effect 1] The present invention changes the dipping speed of the monolithic catalyst in accordance with the supporting speed of the catalyst component. That is, the faster the supporting speed is, the more supports (supports 51) the catalyst component adheres to the support layer in the same immersion time, and the faster the immersion speed is, the fewer the supported layers are. Therefore, by adjusting the dipping speed in accordance with the supporting speed, it is possible to change the supported layer of the catalyst component in the axial direction of the monolithic catalyst carrier. I can do it. Therefore, a monolithic catalyst with stable performance and less variation can be produced. Furthermore, in the monolithic catalyst obtained by the J-process, less catalyst components are supported on the exhaust gas inflow side of the catalyst, and more on the outflow side of the catalyst. As a result, there is less catalytic material near the exhaust gas inflow side, where most of the poisonous substances adhere, and there are more poisonous substances, resulting in good durability and catalytic activity. Also, 15? a monolith catalyst with the same performance as the conventional one? If desired, by applying the method of the present invention, a small amount of the catalyst component is sufficient.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the manufacturing process of the example rimple. FIG. 2 shows the loading speed and dipping speed of platinum in Example Sample 1. Figure 3 shows the platinum loading speed and dipping speed in Example Sample 2. Figure 4 shows the platinum loading m in the axial position of Example Sample 1.2 and Comparative Example Sample. Figure 5 shows the loading of rhodium in the axial position of Example Sample 1.2 and Comparative Example Sample.
1 shows the purification rate (%) of Sample 1.2 and Comparative Example sample. Patent applicant: Toyota Motor Corporation Agent
Patent attorney Hirotoshi Okawa Patent attorney Akihito Maruyama;

Claims (4)

[Claims] (1) One end of the monolithic catalyst carrier on which the catalyst support layer has been formed is always held at the top and the other end is always held at the bottom, and the monolithic catalyst carrier is immersed from the other end into the catalyst component-containing solution at a predetermined speed so that the amount of water is increased on the other end. A method for producing a monolithic catalyst, characterized by supporting a catalyst component and then calcining it. (2) The method for producing a monolithic catalyst according to claim 1, wherein the predetermined speed is determined depending on the concentration of the residual catalyst component in the catalyst component-containing solution. (3) The method for manufacturing a monolith catalyst according to claim 1, wherein the predetermined speed includes at least one stop state. (4) The method for producing a monolith catalyst according to claim 1, wherein the predetermined speed is large in the early stage of immersion and small in the latter stage.