JPH0694372B2 - Method for producing high-purity antimony pentoxide powder - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing high-purity Sb ₂ O ₅ powder in a short time and with high yield.

Antimony oxide is mixed into plastics, fibers, etc. as a flame retardant material. Types of antimony oxide include antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony pentoxide (Sb ₂ O ₅ ), etc., all of which are used as flame retardants, Since Sb ₂ O ₅ can obtain a finer powder than Sb ₂ O ₃ , the amount of its use has increased in recent years.

[Prior art and problems] Among various antimony oxides, Sb ₂ O ₄ is the most stable at 900 ° C or lower, and when Sb ₂ O ₃ is burned in the air, it becomes Sb ₂ O ₄ and obtains Sb ₂ O _5. I can't. Therefore, conventionally, the following method has been known as a method for producing Sb ₂ O ₅ .

(A) Method of reacting Sb ₂ O ₃ with KOH and hydrogen peroxide to form potassium antimonate (KSbO ₃ ) and deionizing it with an ion exchange resin to obtain colloidal Sb ₂ O ₅ (Japanese Patent Publication No. 57-11848).

(B) A method of reacting Sb ₂ O ₃ with hydrogen peroxide while flowing through a special tubular reaction vessel at a temperature of 90 ° C. or higher (Japanese Patent Publication No.
53-20479).

The above method (a) is for producing Sb ₂ O ₅ by ion exchange of KSbO ₃ , in which case the raw material Sb ₂ O ₃ powder is water,
Utilizing the property that it is hard to dissolve in alcohol and is easily dissolved in a concentrated KOH solution, further, hydrogen peroxide is mixed with KOH to dissolve Sb ₂ O ₃ in a small number of moles of KOH, and ion exchange in the subsequent step is performed. It reduces the burden. However, even in this method, it is unavoidable that K remains in the colloidal precipitate, and it is extremely difficult to obtain high-purity Sb ₂ O ₅ .

The above method (b) oxidizes the diameter Sb ₂ O ₃ without using KOH, does not cause the problem of K residue, and does not use acid or alkali, so that corrosion of the equipment can be avoided and continuous production is possible. Can be carried out, but the devices that can be used are limited, and
There is a drawback that the yield is low.

[Knowledge on Problem Solving] The present inventors, unlike the conventional method using Sb ₂ O ₃ as a starting material, use SbCl ₃ as a starting material and use ammonia (NH ₄
It has been found that fine high-purity Sb ₂ O ₅ powder can be easily produced by reacting with (OH) and oxidizing with hydrogen peroxide.

According to the present invention, antimony trichloride (SbCl ₃ ) is reacted with NH ₄ OH, and then the product is oxidized with hydrogen peroxide to produce antimony pentoxide (Sb ₂ O ₅ ). Methods are provided.

Further, as a preferred embodiment thereof, at room temperature to 100 ° C., SbCl ₃ solution dissolved in hydrochloric acid or alcohol is added dropwise to NH ₄ OH, or NH ₄ OH is added dropwise to SbCl ₃ solution, and after completion of the reaction. Further, hydrogen peroxide was added dropwise to form a colloidal Sb ₂ O ₅ precipitate, and the precipitate was separated and dried to obtain Sb ₂ O ₅
A method of making a powder is provided.

In the manufacturing method of the conventional Sb ₂ O ₃ as raw materials, it is contemplated that using NH ₄ OH instead of KOH in order to avoid residual alkali during the dissolving Sb ₂ O ₅ powder, Sb ₂ O ₃ is NH ₄ OH
It is hard to dissolve in and cannot be used. Sb ₂ without KOH
If O _{3 is} to be directly oxidized, a special reaction vessel must be used (method b) above, and the yield is low.

The present invention uses SbCl ₃ as a raw material. In addition to this, there is antimony pentachloride SbCl _{5 as} antimony chloride, but this SbCl ₅ is immediately hydrolyzed in water to form coarse particles of Sb ₂ O ₅ , and a fine powder cannot be obtained. The above SbCl ₃ is previously dissolved in hydrochloric acid or alcohol. To react the SbCl ₃ with NH ₄ OH
SbCl ₃ solution may be added dropwise to NH ₄ OH solution, also SbC a NH ₄ OH solution
l It may be added dropwise to the ₃ liquid. The reaction temperature is room temperature to about 100 ° C. Even if SbCl ₃ is not dissolved in hydrochloric acid or alcohol and brought into direct contact with hydrogen peroxide, hydrolysis of SbCl ₃ does not proceed in the commonly used 35% H ₂ O ₂ solution, and Sb ₂ O ₅ can be obtained. Can not.

The reaction between the SbCl ₃ solution and the NH ₄ OH solution forms antimony oxychloride (Sb ₄ O ₅ Cl _2, etc.) as shown in the following formula.

_{4SbCl 3 + 10NH 4 OH → Sb} 4 O 5 Cl 2 + 10NH 4 Cl + 5H 2 after O reaction, was added dropwise hydrogen peroxide to oxidize the product.

Sb ₄ O ₅ Cl ₂ ＋ 4H ₂ O ₂ → 2Sb ₂ O ₅ ＋ 2HCl ＋ 3H ₂ O Usually, potassium permanganate and potassium dichromate are used as oxidizing agents in addition to hydrogen peroxide. If the agent is used, K, Cr, and Mn may remain, which is not preferable. When the reaction with NH ₄ OH and the reaction with hydrogen peroxide are carried out at 60 ° C. or lower, the temperature is raised to 80 ° C. or higher and the reaction is terminated by stirring for 20 to 30 minutes.

NH ₄ Cl, which is a by-product of the above oxidation reaction, is removed by repeating decantation. Decantation is performed using a conductivity meter until the solution shows a conductivity similar to that of distilled water. Alternatively, add AgNO ₃ solution dropwise until the white precipitate does not occur. Further, after separating the colloidal precipitate, it is dried and calcined at a temperature of 500 ° C. or higher to produce NH ₄ Cl.
Sublimates and the residual Cl content is largely removed by less than 1/2.

After separating, it is dried and calcined at 500 ° C. for 2 hours to obtain a powder whose X-ray diffraction graph shows a peak of Sb ₆ O ₁₃ . Sb ₆ O ₁₃ is a mixed atom oxide represented by Sb ₂ Sb ₄ O. In general, anhydrous Sb ₂ O ₅ is difficult to generate because dehydration and deoxidation occur, and it is usually generated as a hydrate of Sb ₂ O ₅ · nH ₂ O (n = 1 to 5). The Sb ₂ O ₅ .nH ₂ O is dehydrated by heating, and the dehydration ends near 400 ° C., but at the same time, deoxidation also occurs and Sb ₆ O ₁₃ is changed. Sb ₆ O ₁₃ is stable even when heated to 600 to 800 ° C., and decomposes into Sb ₂ O ₄ near 900 ° C.

From the above, in the present invention, antimony pentoxide is:
Includes Sb ₆ O _{13 in} addition to Sb ₂ O ₅ .

[Effects of the Invention] Since the production method of the present invention does not use a solution containing an alkali metal or the like, these metal elements do not remain, and ammonia and chlorine are also removed in the firing step, so that extremely high purity pentoxide is obtained. Antimony powder can be obtained. By the way,
In the antimony pentoxide powder produced by the conventional method, 1.90% and 124 ppm of alkali metal and Cl remain, respectively, whereas the amount of alkali metal and Cl detected in the present invention is 1 ppm or less.

Furthermore, while the powder according to the conventional manufacturing method has a specific surface area of about 27 m ² / g, the powder obtained by the present invention has a specific surface area of 37 to 39 m ² / g, and a significantly fine powder is obtained. To be

In addition, the method of the present invention has a high production efficiency because the reaction is completed in a relatively short time, and the operation is simple and easy to carry out.

[Example] 413 ml of 25% NH4OH was added to ₄ liters of distilled water and stirred. This NH
420 g of SbCl ₃ powder (manufactured by Mitsubishi Metals, 99.999%) in ₄ OH liquid
A solution dissolved in 280 ml of 6N hydrochloric acid was added dropwise with a metering pump over 10 minutes to cause a reaction. After continuously stirring for 5 minutes, 223 g of 35% hydrogen peroxide was added, the temperature was raised to 80 ° C., and the mixture was stirred for 30 minutes to form a colloidal precipitate.

Then, the above precipitate was washed with distilled water until the conductivity of the liquid reached 0.01 mS / cm, separated, dried, and pulverized, and the specific surface area and the residual amounts of alkali metal and Cl were measured. The results are shown in the table below.

Subsequently, when the powder was calcined at 500 ° C. for 2 hours and subjected to X-ray diffraction, only a peak of Sb ₆ O ₁₃ was detected. The specific surface area after firing, alkali metal, amount of Cl and conventional products are also shown in the following table.

Claims (2)

[Claims] 1. A method for producing antimony pentoxide (Sb ₂ O ₅ ) by reacting antimony trichloride (SbCl ₃ ) with aqueous ammonia and then oxidizing the product with hydrogen peroxide. 2. At room temperature to 100 ° C., the SbCl ₃ solution is dropped into ammonia water, or the ammonia water is dropped into the SbCl ₃ solution, and after completion of the reaction, hydrogen peroxide is dropped further to form a colloidal form. _2. The production method according to claim 1, wherein the Sb ₂ O ₅ precipitate is produced, the precipitate is separated and dried to produce Sb ₂ O ₅ powder.