JPH0685873B2 - Method of manufacturing honeycomb structure carrier comprising boria silica-alumina composition - Google Patents

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 structure carrier composed of a boria-silica-alumina composition having excellent properties as a catalyst carrier.

[0002]

2. Description of the Related Art Since a catalyst carrier of a honeycomb structure has a large number of parallel flow passages, it has various characteristics such as a small pressure loss and a large apparent surface area per unit volume when flowing a fluid. It is widely used as a catalyst carrier for waste gas treatment, a catalyst carrier for combustion, and the like. These honeycomb structures are formed by molding a ceramic material, such as mullite, cordierite, or α-alumina, into a honeycomb shape, and
The substrate surface obtained by firing was coated with γ-Al ₂ O ₃ to obtain a catalyst carrier. However, γ-Al
₂ O ₃ has insufficient heat resistance and improves heat resistance. Therefore, the applicant has found and proposed a boria-silica-alumina composite oxide having a high specific surface area and excellent heat resistance. (Japanese Patent Application No. 2-8162).

[0003]

However, a catalyst carrier having excellent heat resistance can be obtained by coating a ceramic honeycomb substrate with this boria-silica-alumina composition. And a boria-silica-alumina composition coating process.
There is also a problem that the coating amount of the composition is limited.

The present invention provides a method for producing a catalyst carrier having a very large specific surface area even at a high temperature and excellent heat resistance by one step by directly forming a honeycomb structure from a boria-silica-alumina composition. It is intended to be provided.

[0005]

As a result of intensive studies to solve the above problems and achieve the above object, the present inventor has formed a boria-silica-alumina composition having a specific composition by molding, drying and firing. -The present invention has been completed by finding that the object can be achieved by pulverizing, adding various compounds and firing as a honeycomb structure at a specific temperature. That is, the present invention uses 3 to 10% by weight of boria (B
₂ O ₃ ), 4-19 wt% silica (SiO ₂ ) and the balance alumina (Al ₂ O ₃ ), after molding, drying-calcining and then crushing , An organic lubricant and an organic binder, or a clay, an organic lubricant and an organic binder, and water are added and kneaded, and the mixture is extruded into a honeycomb structure, dried, and then dried.
It is a method for manufacturing a honeycomb structure carrier made of a boria-silica-alumina composition, which is fired at a temperature of 1400C.

[0006]

The boria-silica-alumina composition of the present invention is
For example, in an alumina hydrate slurry produced by hydrolysis of an aqueous solution of aluminum sulfate and an aqueous solution of sodium aluminate, 4 to 19% by weight as silica (SiO ₂ ) is added.
The alumina-silica hydrate slurry obtained by adding an aqueous solution of sodium silicate so as to fall within the range of 3 is added to the alumina-silica hydrate cake obtained by filtration and washing to obtain ₃ as boria (B ₂ O ₃ ). Add orthoboric acid and / or an aqueous solution of orthoboric acid so as to be in the range of 10 to 10% by weight and mix well. Next, the obtained mixture is kneaded by heating in a kneader with a humidifying jacket, extruded by a molding machine having a die having a desired shape, and then crushed to a range of 10 to 40 μ, and boria-silica. Manufactured as oxide powder of alumina.

In the boria-silica-alumina composition of the present invention, ₃ to 10% by weight of B ₂ O ₃ and 4 to 1 of SiO ₂ are added.
The range of 9 wt% is that the composition of B ₂ O ₃ less than 3 wt% and more than 10 wt% and SiO ₂ less than 4 wt% and more than 19 wt% significantly decreases the specific surface area at high temperature. This is because the heat resistance is reduced.

In the boria-silica-alumina oxide powder of the present invention, boria-silica-alumina hydrate is molded, dried at 80 to 120 ° C, and usually 500 to 1000 ° C, preferably 500 to 800 ° C. Bake for hours. If the firing temperature is less than 500 ° C, it will not be in an oxide state,
If the temperature exceeds 0 ° C., sintering will occur, making it difficult to crush in the next step.

Next, the obtained fired product has an average particle size of 10
It is desirable to crush it to a range of -40 μ.
The average particle size may be less than 10 μ, but the crushing process requires a long time, and if the average particle size exceeds 40 μ, a preferable honeycomb molded body cannot be obtained.

In this manner, the boria-silica-alumina oxide powder is obtained in the honeycomb structure obtained by using the oxide obtained by drying and firing boria-silica-alumina hydrate. This is because cracks occur and a preferable honeycomb structure cannot be obtained.

Boria-silica-obtained in this way
Next, the alumina oxide powder was sufficiently kneaded and plasticized by adding 25% by weight or less of clay, an organic lubricant and an organic binder, or an organic lubricant and an organic binder, and water. After that, it is extruded through a honeycomb mold having a desired shape using a vacuum extrusion molding machine, and molded into a honeycomb structure having through holes. Next, the molded body is dried at a temperature of 70 to 90 ° C. and a humidity of 80 to 95% and fired at a temperature of 600 to 1400 ° C. to obtain a honeycomb structure carrier.

Examples of clay to be added as a binder when molding the honeycomb structure of the present invention include kaolin, bentonite, sericite, etc. The addition amount is preferably 25% by weight or less, and 25% by weight or less. %
If it is added over the range, the specific surface area as a catalyst carrier decreases, which is not preferable.

Examples of organic lubricants include aluminum stearate, magnesium stearate,
Fatty acid triglyceride etc. are mentioned, and the addition amount is 5
It is desirable to set it in the range of 15% by weight, and if the addition amount is less than 5% by weight, a preferable honeycomb molded body cannot be obtained.
Although it may be added in an amount exceeding the amount by weight, when the honeycomb structure is dried and fired, the organic lubricant may be burned to cause an abnormally high temperature and a part of the honeycomb structure may collapse. Not preferable.

Further, examples of the organic binder include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, dextrin and the like,
The addition amount is preferably in the range of 4 to 10% by weight. If the addition amount is less than 4% by weight, the plasticity is insufficient and a preferable honeycomb structure cannot be obtained, and it may be added in excess of 10% by weight, but when the honeycomb structure is dried and fired, the organic substance is not added. It is not preferable because the binder may be burned to cause an abnormally high temperature in part, and the honeycomb structure may be destroyed.

The formed honeycomb structure was heated at a temperature of 70-9.
Although the honeycomb structure is dried at 0 ° C. and a humidity of 80 to 95%, under a low humidity condition of less than 80%, a crack occurs in a part of the honeycomb structure, and a preferable honeycomb structure cannot be obtained. The firing temperature is set in the range of 600 to 1400 ° C. because the organic lubricant and the organic binder remain as carbon without being decomposed at a temperature lower than 600 ° C. and a specific surface area at a temperature higher than 1400 ° C. Is reduced and the properties as a catalyst carrier are lost.

[0016]

EXAMPLES Next, examples of the present invention will be described. Example 1 In a stainless steel reaction tank with a stirrer having a capacity of 100 l,
49.5 l of water was added, and 774 g of Al ₂ O ₃ was added.
9540 g of an aluminum sulfate aqueous solution containing
A sodium aluminate aqueous solution containing 1275 g of Al ₂ O ₃ was added dropwise while being heated to and held at ℃ while stirring to obtain an alumina hydrate slurry having a pH of 9.0. Next, 55 g of nitric acid having a concentration of 30% was added to the slurry to adjust the pH to 5.4, and then 1800 g of an aqueous sodium silicate solution containing 252 g of SiO ₂ while stirring.
Is added dropwise to obtain an alumina-silica hydrate having a pH of 8.5,
It was filtered and washed to obtain an alumina-silica hydrate cake. To this 6760 g of alumina-silica hydrate cake (1014 g as alumina-silica), 94.4 g of reagent grade orthoboric acid (53.4 g as B ₂ O ₃ ) was added and kneaded by heating in a kneader to give a diameter of 5. Molded by an extrusion molding machine having a 0 mm die, dried at 110 ° C. for 15 hours, baked at 600 ° C. for 2 hours in an electric furnace, and then crushed, 5.0 wt% of B ₂ O ₃ having an average particle size of 20 μm. , SiO ₂
Boria containing 10.5 wt% and Al ₂ O ₃ 84.6 wt%
A silica-alumina oxide powder was obtained. Then, 840 g of the powder was added with 150 g (14% by weight) of aluminum stearate, 50 g (5% by weight) of methylcellulose, and 1050 ml of water, and kneaded until sufficiently plasticized, and then the wall thickness was 0.4 mm and the wall thickness was 0.4 mm Molded into a honeycomb structure through a cell-shaped square honeycomb mold with a distance of 2.0 mm,
After drying at a temperature of 85 ° C and a humidity of 90% for 48 hours,
The honeycomb structure carrier A was obtained by firing at 1200 ° C. for 3 hours.

The honeycomb structure was dried in the same manner as described above and then fired at temperatures of 600 ° C., 1000 ° C. and 1400 ° C. for 3 hours to obtain honeycomb structure carriers B, C and D.

Properties of the honeycomb structure carriers A, B, C and D,
Table 1 shows the specific surface area (m ² / g) obtained by the BEF method by nitrogen gas adsorption. Even if calcined at 1400 ° C. for 3 hours, the specific surface area is 13 m ² / g, and it is clear that it can be sufficiently applied as a catalyst carrier having excellent heat resistance. Comparative Example 1 A honeycomb structure carrier R-1 was obtained in substantially the same manner as in Example 1 except that commercially available γ-Al ₂ O ₃ was used. Table 1 shows the properties of the obtained honeycomb structure carrier. It is clear that the specific surface area is significantly inferior to the honeycomb structure carrier of the present invention obtained in Example 1. Also 1200
It is also apparent that the calcination at a temperature of ° C transforms into α-Al ₂ O ₃ and loses the specific surface area as the heat-resistant catalyst carrier. Example 2 80/20 wt% as Al ₂ O ₃ / SiO ₂ , 95 /
Except that the addition amount of the sodium silicate aqueous solution added to the alumina hydrate slurry was changed to be 5% by weight, the production method for obtaining the boria-silica-alumina oxide powder of Example 1 was repeated. B ₂ O with an average particle size of 20μ
₃ 5.0% by weight, SiO ₂ 19.0% by weight, Al ₂ O ₃
76.0% by weight, B ₂ O ₃ 5.0% by weight, SiO
₂ 4.8 _{wt%, Al} 2 O 3 90.2% by weight of boria -
A silica-alumina oxide powder was obtained. Next, honeycomb structure carriers E and F were obtained in the same manner as in the method for obtaining the honeycomb structure of Example 1 using the powder. Table 1 shows the properties of the obtained honeycomb structure carrier. B ₂ O ₃ / SiO ₂ / A
I ₂ O ₃ as 5.0 / 19.0 / 76.
Even if the boria-silica-alumina oxide powder of 0% by weight and 5.0 / 4.8 / 90.2% by weight is used, a honeycomb structure carrier having a high specific surface area and excellent heat resistance can be obtained. It is clear that Comparative Example 2 Except that the amount of orthoboric acid added to the alumina-silica hydrate cake obtained in substantially the same manner as in Example 1 was changed to 2.0% by weight and 15% by weight as B ₂ O _3. A honeycomb structure carrier R-2 was obtained in the same manner as in Example 1. The properties are shown in Table 1. When the content of B ₂ O ₃ is less than 30% by weight or exceeds 15% by weight, it is clear that the specific surface area is small and the heat resistance is poor. Example 3 The amount of the binder added when the boria-silica-alumina oxide powder obtained in the same manner as in Example 1 was added to the honeycomb structure was 5% by weight of sericite and 10% by weight of aluminum stearate. , Methylcellulose 5% by weight
A honeycomb structure carrier G was obtained in the same manner as in Example 1 except for the addition. In addition, 20 Sericite as a binder
Honeycomb structure carrier H in the same manner as above except that the weight% was added.
Got

Table 1 shows the properties of the obtained honeycomb structure carriers G and H. It is clear that when the amount of clay added is in the range of 5 to 20% by weight, a honeycomb structure carrier having a high specific surface area and excellent heat resistance can be obtained. Comparative Example 3 Except that 30% by weight of sericite, 10% by weight of aluminum stearate, and 5% by weight of methylcellulose were added to the boria-silica-alumina oxide powder obtained in the same manner as in Example 1. A honeycomb structure carrier R-4 was obtained in the same manner as in Example 1. The properties are shown in Table 1.
It is clear that when the amount of clay added is 30% by weight, the specific surface area of the resulting honeycomb structure carrier is reduced and the heat resistance is poor.

[0020]

[Table 1]

[0021]

The present invention is intended to obtain a boria-silica-alumina oxide powder having a specific composition range, and to add a binder to the powder, and to fire the honeycomb structure in a specific temperature range. A honeycomb structure carrier having a high specific surface area having excellent heat resistance can be obtained in the process, and a remarkable effect is recognized.

[Table 1]

[Table 1]

Claims (2)

[Claims] 1. A boria-silica-alumina hydrate comprising ₃ to 10% by weight of boria (B ₂ O ₃ ), 4 to 19% by weight of silica (SiO ₂ ) and the balance alumina (Al ₂ O ₃ ). After molding, drying and firing, and then crushing, an organic lubricant and an organic binder or clay, an organic lubricant and an organic binder, and water are added and kneaded to form a honeycomb structure. Extruded and dried, then 600-1400 ℃
A method for producing a honeycomb structure carrier comprising a boria-silica-alumina composition, which comprises firing at a temperature of. 2. The method for producing a honeycomb structure carrier comprising the boria-silica-alumina composition according to claim 1, wherein the amount of clay added is 25% by weight or less.