JPH075298B2 - Manufacturing method of micro spherical alumina - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing fine spherical alumina, and more specifically, it is suitable for a carrier of a fluidized bed catalyst or a powder catalyst used in a suspended state or a slurry state. The present invention relates to a method for producing substantially spherical fine alumina having excellent wear resistance strength.

[Conventional technology and its problems]

The method of using the powdered catalyst in a fluidized bed system or in a suspended state is more advantageous than the method of using the catalyst in a fixed bed system.
Since the solid or liquid-solid or gas-liquid-solid contact efficiency is high, the reaction rate is high, and in reactions involving heat generation, heat absorption, etc., the heat can be easily removed and supplied. However, it is widely used in many reactions such as catalytic reforming, oxychlorination of ethylene, and Fisher-Tropsch reaction synthesis reaction. Generally, when using a fluidized catalyst industrially,
In order to maintain a good fluid state, it must have an appropriate particle size distribution and bulk density, be substantially spherical, and have particularly excellent abrasion resistance, but those that simultaneously satisfy these conditions It was profitable.

[Means for solving problems]

The present inventors, as a result of various studies in view of the above problems, a fluidized bed catalyst satisfying these conditions by a specific production method,
Alternatively, the inventors have reached the present invention by knowing that it is possible to easily provide alumina suitable for a carrier for a powder catalyst used in a suspended state or a slurry state.

That is, the gist of the present invention relates to a method for producing fine spherical alumina, which comprises peptizing an aqueous slurry of alumina or alumina hydrate with an acid, then gelating with an alkali, followed by spray drying and firing. Exist.

Hereinafter, the present invention will be described in detail.

The alumina or alumina hydrate used in the present invention may be commercially available, but pseudoboehmite is particularly preferable.
Aqueous slurry in which alumina or alumina hydrate is dispersed in water is used, and the concentration of this slurry is usually 0.1 / -30 wt% as Al ₂ O ₃ , preferably 5-20 wt%. If the slurry concentration is too low, productivity is poor and it is not economical. On the contrary, if it is too high, the viscosity of the slurry after gelation becomes too high, which causes a problem in transportation during spray drying.

The acid used for deflocculating the alumina or alumina hydrate slurry to form a sol is not particularly limited as long as it is an acid, and inorganic acids such as hydrochloric acid, nitric acid and perchloric acid can also be used such as acetic acid and propionic acid. Although an organic acid may be used, it is preferable to use an organic acid having an appropriate peptizing action and mild corrosiveness to the material of the apparatus, and acetic acid is particularly preferable. The amount of acid used is preferably 0.01 / 1.0 in terms of the molar ratio of acid (acid / Al ₂ O ₃ ) to alumina.
0.05-0.10 is preferable.

Then, it is gelled with an alkali. The alkali used in this gelation step is not particularly limited, but ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like are particularly preferable, and among them, ammonia which is easily volatilized during firing is preferable. The amount of alkali used is 0.5 of the acid used previously.
˜5 times mole, preferably 1.0 to 2.0 times mole.

The desired microspherical alumina is obtained by spray-drying and firing the obtained gel.

For spray drying, a spray dryer is usually used. The spraying method of the spray dryer is not particularly limited and may be appropriately determined depending on the desired shape of the particle size distribution, the production amount, and the like.

Further, the firing temperature and time are not particularly limited, but generally
500 to 1100 ° C, 10 minutes to 2 hours. Further, the method may be any one of pine full furnace firing, fluidized firing, rotary furnace firing, belt furnace firing, etc., but the firing conditions such as firing temperature, time, atmosphere, etc. are determined by physical properties such as specific surface area and pore distribution of the obtained alumina carrier. Since it has a great influence, it is necessary to determine the conditions according to the required physical properties.

〔The invention's effect〕

Alumina obtained by the method of the present invention is substantially spherical and has excellent abrasion resistance, and is excellent as a catalyst carrier for various reactions.

As will be apparent from Examples and Comparative Examples described below, when the raw material alumina source is spray-dried simply by deflocculating with an acid, or instead of deflocculating, the alumina source is finely pulverized by a vibrating ball mill and spray-dried. In the method of the present invention, the abrasion resistance strength can be remarkably improved by the combination of the solization by the peptization method and the gelation, which is extremely useful industrially. It is something.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The wear resistance strength test method is a fluid catalytic cracking catalyst (so-called
FCC catalyst) is known as a test method. ″ Test Method for Synthetic Cracking Catalys
ts) ″ was carried out according to the method described in American Cyanamid Co., Ltd. 6 / 31-4m-1 / 57. The R and I values of the wear loss (%) shown in Table 1 were obtained from the following formulas. It is a thing.

However, A: Weight of alumina carrier that scatters or wear is lost in 0 to 5 hours (g) B: Weight of alumina carrier that is worn and lost in 5 to 20 (g) C: Weight of alumina carrier used in the test (g) In this test, C was set to 50 in all cases.

Example 1 Pseudo-boehmite powder (CONDEA CHEMIE Pural SB) 2.0 kg
Was poured into 17 kg of water and sufficiently stirred to form a uniform slurry, and 1 kg of an 8 wt% acetic acid aqueous solution was added over 10 minutes.

After stirring for 20 minutes, 136 g of 25 wt% ammonia water (NH
₍ Corresponding to 1.5 times mol of acetic acid as ₃ ) was added. After 3 minutes, gelation occurred and became very viscous, but the viscosity decreased with stirring, and after 10 minutes, a slurry having a stable viscosity was formed. This alumina gel slurry is supplied to a rotary disk type spray dryer at 7 liters per hour and sprayed in air at 230 ° C for about 1.5
kg powder was obtained. Next, this powder was fired in a pine fur furnace at 800 ° C. for 1 hour to obtain 1.27 kg of alumina powder.

The alumina powder thus obtained was almost spherical and
The% diameter was 53 μm.

The results of the measurement of wear resistance strength are shown in Table 1 together with other examples and comparative examples.

Example 2 Alumina powder 1.26 kg was obtained in the same manner as in Example 1 except that 1 kg of a 10% by weight aqueous acetic acid solution was used and the amount of 25% by weight aqueous ammonia used was 170 g (1.5 times the molar amount of acetic acid).

Example 3 Alumina powder was prepared in the same manner as in Example 1 except that 1 kg of 10 wt% water-soluble acetic acid was used in the same manner as in Example 2 except that 119 g of 25 wt% ammonia water (1.05 times mol of acetic acid was used).
I got 1.27 kg.

Comparative Example 1 The same pseudoboehmite powder as in Example 1 (2.0 kg) was added to water (17 kg) to form a uniform slurry, and then 8% by weight acetic acid aqueous solution (1 k) was added.
g was added in 10 minutes. Example 1 after stirring for 20 minutes
Spray drying and firing were performed under the same conditions as above to obtain 1.08 kg of alumina powder.

Comparative Example 2 Boehmite (3 kg) and water (3 kg) were wet-milled for 1 hour with a vibrating ball mill, then water was added to boehmite (3 kg) at a ratio of 17 kg of water, and the mixture was sufficiently stirred to form a uniform slurry. Spray drying and firing were performed under the same conditions as in 1.

After firing, 1.63 kg of powder was obtained.

Comparative Example 3 2.0 kg of the same pseudo-boehmite powder as in Example 1 was fired as it was under the same conditions as in Example 1 without any treatment.

About 1.6 kg of baked product was obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 61-270201 (JP, A) JP 61-174103 (JP, A) JP 61-72624 (JP, A) JP 57- 61626 (JP, A)

Claims (3)

[Claims] 1. A method for producing fine spherical alumina, which comprises peptizing an aqueous slurry of alumina or alumina hydrate with an acid, then gelating with an alkali, and then spray-drying and firing. 2. An acid is acetic acid, hydrochloric acid, nitric acid or perchloric acid, and an alkali is ammonia, sodium hydroxide, potassium hydroxide or lithium hydroxide. A method for producing the fine spherical alumina described above. 3. The method for producing microspherical alumina according to claim (1) or (2), wherein the alumina hydrate is pseudo-boehmite.