JPH0568881A - Production of honeycomb structure catalyst carrier consisting essentially of boria-alumina composition - Google Patents

Abstract

PURPOSE:To provide a method to manufacture a honeycomb structure catalyst carrier having excellent heat resistance and high specific surface area of >=10m<2>/g required as a catalyst carrier by using a boria-alumina compsn. as the material to manufacture the honeycomb structure. CONSTITUTION:The honeycomb structure catalyst carrier consists essentially of a boria-alumina compsn. This carrier is manufactured by the following process. A boria-amumina hydrate consisting of 5-15wt.% B2O3 and the balance substantially Al2O3 is molded, dried, calcined, and pulverized, to which a clay and/or org. lubricant, org. binder, and water are added and kneaded. The kneaded material is molded into a honeycomb structure by extrusion molding, dried and calcined at 600-1300 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a honeycomb-structured catalyst carrier mainly composed of a boria-alumina-based composition having excellent performance as a catalyst carrier.

[0002]

2. Description of the Related Art A honeycomb structured catalyst carrier has a large number of parallel flow passages, and therefore has a small pressure loss when a fluid is flown and has a large apparent surface area per unit volume. It is widely used as a catalyst carrier, a catalyst carrier for combustion, and the like.

These honeycomb structure catalyst carriers are formed by molding a ceramic material made of mullite, cordierite, α-alumina or the like into a honeycomb shape, and drying and firing the coated honeycomb substrate, and the surface of the honeycomb structure substrate is coated with γ-alumina. Was obtained.

However, as a coating material, γ-
When alumina is used, the heat resistance when the catalyst carrier is exposed to high temperature for a long time is insufficient, and
There is a problem that part or all of the alumina undergoes thermal transition to α-alumina. Therefore, the inventors previously replaced the γ-alumina with a composition composed of a B ₂ O ₃ —Al ₂ O ₃ composite oxide (hereinafter referred to as a boria-alumina-based composition).
Was proposed as a coating material. (Japanese Patent Application No. 2-8161)

[0005]

By coating a ceramic honeycomb structure substrate with this boria-alumina-based composition, a catalyst support having a high specific surface area and excellent heat resistance was successfully obtained. According to the method, the coating amount is limited in terms of the adhesiveness of the coating material, and the catalyst carrier is manufactured by a honeycomb structure substrate made of ceramics and a boria-alumina composition coating step.
There is a problem that it is not efficient because it requires steps.

The present inventors obtained a honeycomb structure catalyst carrier in one step if the boria-alumina-based composition was used not as a coating material but as a material for directly manufacturing a honeycomb structure, and the above-mentioned adhesive property was obtained. The present invention has been completed in view of solving a problem, and the present invention uses a boria-alumina-based composition as a material for producing a honeycomb structure and requires 10 m ² / g as a catalyst carrier.
It is an object of the present invention to provide a method for obtaining a honeycomb structure catalyst carrier having the above high specific surface area.

[0007]

The present invention for achieving the above object provides a boria-alumina hydrate comprising 5 to 15% by weight of B ₂ O ₃ and the balance substantially Al ₂ O _3. Molded, dried and fired, then crushed the fired product, then clay and / or organic lubricant, organic binder and water are added and kneaded, and the kneaded product is extruded into a honeycomb structure. The method for producing a honeycomb structured catalyst carrier mainly comprising a boria-alumina-based composition is characterized in that after drying, it is fired at a temperature of 600 to 1300 ° C.

In the method for producing the catalyst carrier of the present invention, the average particle size of the calcined and crushed boria-alumina hydrate is 10 to 10.
It is preferably about 40 μm. When clay is added to the crushed product as a molding aid, the addition amount is 2
It is desirable that the amount is 5% by weight or less, preferably 20% by weight or less, and when the organic lubricant is added, the addition amount is preferably in the range of 5 to 15% by weight.

[0009]

The operation of the present invention will be described in detail below. In the production method of the present invention, the boria-alumina hydrate used as a raw material is, for example, an alumina hydrate obtained by filtering and washing an alumina hydrate slurry produced by hydrolysis of aluminum sulfate and sodium aluminate. It is prepared by adding orthoboric acid and / or an aqueous solution of boric acid to the product cake so as to be in the range of 5 to 15% by weight as B ₂ O ₃ and thoroughly mixing them. The thus obtained boria-alumina hydrate was kneaded by heating in a kneader with a heating jacket, and then extruded using a molding machine having a die having a desired shape,
Dry at a temperature of 80 to 120 ° C, and further 500 to 100
Baking at 0 ° C. for about 2 hours gives a fired product with an average particle size of 10 to 10.
The powder is crushed to a range of 40 μm to obtain a boria-alumina composition powder.

As described above, in order to obtain a honeycomb structure carrier, the boria-alumina hydrate is not used directly, but the hydrate is used as a honeycomb structure carrier after once calcination to remove water of crystallization. This is because, when the honeycomb structure is manufactured by, the honeycomb structure is cracked and a preferable product cannot be obtained.

In the production method of the present invention, the reason why the content of B ₂ O ₃ in the boria-alumina composition is in the range of 5 to 15% by weight is that B ₂ O ₃ is less than 5% by weight, or This is because when it exceeds 15% by weight, the heat resistance of the honeycomb structure carrier obtained through the subsequent steps is lowered, and the specific surface area is also remarkably reduced to deteriorate the performance as the catalyst carrier.

After the boria-alumina hydrate is dried in the boria-alumina composition powder of the present invention, it is 500 to 10
Firing in the temperature range of 00 ° C is performed at a firing temperature of 500 ° C.
If it is less than 1, the water of crystallization is not sufficiently removed, and
If the temperature exceeds 000 ° C., sintering will occur between the oxides, making it difficult to perform the crushing work performed in the next crushing step. A particularly preferable firing temperature is 500 to 800 ° C.
The range is.

The average particle size of the crushed product is 10-40.
Make sure that the average particle size is 40 μm in the range of μm.
If it exceeds 10, the moldability is deteriorated and a preferable honeycomb structure cannot be obtained, and if it is less than 10 μm, the crushing step requires a long time, which is not preferable in terms of production efficiency.

The boria-alumina composition powder obtained by the procedure described above is then thoroughly kneaded by adding 25% by weight or less of clay and / or organic lubricant, a small amount of organic binder and water. After being plasticized, a vacuum extrusion molding machine is used to perform extrusion molding with a honeycomb die having a desired shape to form a honeycomb structure. Then, the honeycomb structure is dried in an atmosphere having a temperature of about 70 to 90 ° C. and a humidity of about 80% or more, and then 600 to 130.
A honeycomb structure carrier is obtained by firing in a temperature range of 0 ° C.

In the step of obtaining the honeycomb structure of the present invention, the boria-alumina composition powder is mixed with clay and / or
Alternatively, the lubricant is added to improve the moldability of the composition, and examples of the clay to be added include kaolin, bentonite, and sericite. Further, examples of the organic lubricant include aluminum stearate, magnesium stearate, fatty acid triglyceride and the like. In the case of adding clay, the addition amount is set to 25% by weight or less, because the performance as a catalyst carrier in the honeycomb structure carrier obtained by adding more than 25% by weight deteriorates. Further, in the case of adding an organic lubricant, it is preferable that the addition amount be in the range of 5 to 15% by weight. If the addition amount is less than 5% by weight, it is not possible to form a preferable honeycomb structure, and even if the addition amount exceeds 15% by weight, the effect of improving the moldability cannot be obtained any more.
This is because when the honeycomb structure is dried and then fired, a part of the organic lubricant is burned to cause a partial overheated state, and there is a risk that a part of the honeycomb structure is collapsed.

Examples of the organic binder include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, dextrin and the like. The addition amount is 4-1
If the amount of addition is less than 4% by weight, the plasticity is insufficient so that a preferable honeycomb structure cannot be obtained, and if it is added in excess of 10% by weight, further addition effect can be obtained. Not only this, but also as in the case of the organic lubricant, there is a risk that a part of it will burn during firing, leading to partial collapse of the honeycomb structure.

The firing temperature of the honeycomb structure is 600-13.
The temperature range of 00 ° C is set at a temperature lower than 600 ° C because the honeycomb structure carrier having high strength cannot be obtained due to insufficient firing and the decomposition of the added organic lubricant and organic binder does not proceed sufficiently. The carbon component remains,
This is because if the firing is carried out at a temperature higher than 00 ° C., the specific surface area of the honeycomb structure carrier is remarkably reduced and the performance as a catalyst carrier is impaired.

[0018]

EXAMPLES Next, examples of the present invention and comparative examples will be described. Further, the specific surface area values of the honeycomb structure carriers obtained in these Examples and Comparative Examples are collectively shown in Table 1 below. The specific surface area was measured by the BET method using nitrogen gas adsorption. Example 1 Water 49.
Into 5 l, 9540 g of an aluminum sulfate aqueous solution containing 774 g as Al ₂ O ₃ was added, and the mixture was heated to 70 ° C., and while maintaining the same temperature and stirring, an aqueous solution of sodium aluminate containing 1275 g of A ₂ O ₃ was added. Was added dropwise to obtain an alumina hydrate slurry having a pH of 9.0. The slurry was then filtered and washed to give an alumina hydrate cake. This alumina hydrate cake (10% as Al ₂ O ₃
14 g), and 316.8 g of the reagent grade orthoboric acid (B
As ₂ O _{3 179.0g)} was added was molded using an extrusion molding machine having a die heated kneading diameter 5.0mm in a kneader, after calcination for 2 hours at 600 ° C. The molded product after drying furnace B ₂ O ₃ 1 having an average particle size of 20 μm after crushing
A boria-alumina oxide powder containing 5.0% and Al ₂ O ₃ 85.0% was obtained.

Then, the boria-alumina oxide powder 84
After adding 150 g (14% by weight) of aluminum stearate, 50 g (5% by weight) of methyl cellulose, and 1050 ml of water to 0 g and kneading until the mixture was sufficiently plasticized, the wall thickness was 0.4 mm and the distance between the walls was 2. A honeycomb structure was formed by using a 0 mm cell-shaped square honeycomb mold, dried under an atmospheric condition of a temperature of 85 ° C. and a humidity of 90% for 48 hours, and then baked at 1300 ° C. for 3 hours to form a honeycomb structure carrier. I got A.

The dried honeycomb structure obtained by the same procedure as described above was subjected to
Honeycomb structure carrier B, which was fired at 0 ° C for 3 hours each,
C and D were obtained. Table 1 shows the results of measuring the specific surface areas of the A, B, C, and D honeycomb structure carriers. Table 1
As can be seen from the above, all of the honeycomb structure carriers obtained by firing the dry honeycomb structure within the temperature range defined in the present invention are suitable for the catalyst carrier because of their specific surface area values.
The specific surface area is 13m even when baked at high temperature for 3 hours.
It is understood that ² / g and the catalyst carrier can be sufficiently applied. Comparative Example 1 A honeycomb structure carrier R-1 was obtained in substantially the same manner as in Example 1A (carrier baking temperature 1300 ° C.) except that commercially available γ-alumina was used as the main raw material of the honeycomb structure.
The results of measuring the specific surface area of the obtained honeycomb structure carrier are shown in Table 1.

According to Table 1, when γ-alumina is used as the main raw material of the honeycomb structure, the specific surface area value of the obtained honeycomb structure carrier is extremely small and unsuitable as a catalyst carrier, and at a temperature of 1300 ° C. When calcination is performed for 3 hours, most of γ-alumina undergoes thermal transition to α-alumina, so that it cannot perform a predetermined catalyst support function. Example 2 5/95 wt% as B ₂ O ₃ / Al ₂ O ₃ , respectively,
An average particle size of 20 μm was obtained using the same method as in Example 1 except that the addition amount of orthoboric acid added to the alumina hydrate slurry was changed to 10/90% by weight. B ₂ O ₃ 5.0%, Al ₂
Boria-alumina oxide powder containing 95.0% O ₃ and B
_{2 O 3 10.0%, Al 2} O 3 boria containing 90.0% - oxide powder was prepared alumina, then a similar honeycomb carrier production method (support firing temperature as in Example 1A using these powders Honeycomb structure carriers E and F were obtained at 1300 ° C. Table 1 shows the results of measuring the specific surface area values of these honeycomb structure carriers.

From the results shown in Table 1, within the range defined in the present invention, the honeycomb structure carrier obtained by changing the content ratios of B ₂ O ₃ and Al ₂ O ₃ contained in the boria-alumina composition was obtained. It can be seen that the specific surface area of (1) shows a value that can be satisfied as a catalyst carrier. Comparative Example 2 The addition amount of orthoboric acid added to the alumina hydrate cake obtained by the method similar to the method of Example 1 was changed to B ₂ O _3.
In the same manner as in Example 1A, except that the content was changed to 3.0 wt% and 20.0 wt%.
0 ° C.) Honeycomb structure carriers R-2 and R-3 were obtained. Table 1 shows the results of measuring the specific surface area of these honeycomb structure carriers.

From the results shown in Table 1, the alumina hydrate cake has a B ₂ O ₃ content range of 5.0 to 15.0 defined in the present invention.
In the honeycomb structure carrier obtained by using the orthoboric acid-containing boria-alumina oxide powder containing B ₂ O ₃ in a range deviating from the weight percentage, the others are manufactured by the method satisfying the present invention. Even if it does, it can be seen that the specific surface area value is remarkably reduced, so that it is not suitable as a catalyst carrier. Example 3 When the boria-alumina oxide powder obtained by substantially the same method as in Example 1 was molded into a honeycomb structure, the amount of binder added was 5% by weight of sericite, 10 of aluminum stearate. % By weight, methyl cellulose 5
A honeycomb structure carrier G was obtained by the same manufacturing method as that of Example A (carrier baking temperature 1300 ° C.) except that the content was changed to wt%. A honeycomb structure carrier H was obtained by the same manufacturing method as above except that the addition amount of sericite was changed to 20% by weight in the above method. Table 1 shows the results of measuring the specific surface area of these honeycomb structure carriers.

From the results shown in Table 1, if the amount of clay added to the boria-alumina oxide powder is within the range of 5 to 20% by weight defined in the present invention, the specific surface area value of the obtained honeycomb structure carrier is It turns out that it is a satisfactory catalyst carrier. Comparative Example 3 The amount of the binder added when molding the boria-alumina oxide powder obtained by substantially the same method as in Example 1 into a honeycomb structure was 30% by weight of sericite, 10 of aluminum stearate. Honeycomb structure carrier R-4 was obtained by the same manufacturing method as in Example A (carrier baking temperature 1300 ° C.) except that the content was 5% by weight and methyl cellulose was 5% by weight. Table 1 shows the results of measuring the specific surface area of this honeycomb structure carrier.

From the results shown in Table 1, when the amount of clay added to the boria-alumina oxide powder is 30% by weight, which is outside the amount specified in the present invention, the specific surface area of the obtained honeycomb structure carrier is remarkably reduced. Is understood.

[0026]

[Table 1]

[0027]

As described above, according to the present invention, the boria-alumina composition having excellent heat resistance can be used not as the coating material but as the skeleton forming material of the honeycomb structure, so that the coating step can be omitted. In addition, since the obtained honeycomb structure carrier has a high specific surface area and has excellent performance as a catalyst carrier, it can be said to be an invention of high industrial value.

Claims (3)

[Claims] 1. A boria-alumina hydrate comprising 5 to 15% by weight of B ₂ O ₃ and the balance substantially Al ₂ O ₃ is molded, dried and fired, and then the fired product is crushed. After that, clay and / or an organic lubricant, an organic binder, and water are added and kneaded, and the kneaded product is extruded into a honeycomb structure, dried, and then baked at a temperature of 600 to 1300 ° C. A method for producing a honeycomb structure catalyst carrier, which is mainly composed of a boria-alumina-based composition. 2. The method for producing a honeycomb structure catalyst carrier mainly comprising a boria-alumina-based composition according to claim 1, wherein the amount of clay added is 25% by weight or less. 3. The amount of the organic lubricant added is 5 to 15% by weight.
The method for producing a honeycomb-structured catalyst carrier mainly comprising the boria-alumina-based composition according to claim 1.