JPH11268916A - High-purity antimony pentachloride and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high-purity antimony pentoxide with low residual concentrations of chlorine and arsenic. SOLUTION: The chlorinating reaction of antimony trichloride is made to progress at a temperature not lower than the boiling point of arsenic trichloride and not higher than the boiling point of the antimony pentachloride (130-140 deg.C under atmospheric pressure) and an inert gas or gaseous carbon dioxide, etc., is then introduced into the melt to drive off the residual chlorine to the outside of the system. Thereby, high-purity antimony pentachloride at <=0.1 wt.% chlorine concentration and <=1 ppm arsenic concentration is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high-purity antimony pentachloride having an extremely small residual amount of arsenic and chlorine and a method for producing the same.

[0002]

2. Description of the Related Art Antimony pentachloride is widely used as a raw material for medicines and agricultural chemicals or as a chlorination catalyst. As an industrial method of producing antimony pentachloride, antimony pentachloride is produced by contacting chlorine gas with antimony metal to generate antimony trichloride and further introducing chlorine gas into the melt of antimony trichloride. .

In the production of antimony pentachloride,
Usually, the raw material antimony contains 30% of arsenic, a homologous element.
Since 0 to 500 ppm is mixed, antimony pentachloride obtained by chlorinating antimony trichloride is subjected to vacuum distillation at about 200 ° C. to volatilize and remove arsenic. By this distillation under reduced pressure, arsenic is reduced to about 200 ppm in about the first third of the melt, and antimony pentachloride having an arsenic concentration of about 10 ppm is obtained in the main stream of about 2/3.

In the conventional manufacturing method as described above,
A further rectification (distillation) step is required after the production of antimony pentachloride, which imposes a burden on the equipment configuration and production cost. Also, in the rectification step, the first distillation having a high arsenic concentration is returned to the chlorination step of antimony trichloride and the like, and is reused.
The production efficiency is low because only about two-thirds of the product is the main product. Further, the arsenic concentration in the antimony pentachloride after rectification is reduced to about 10 ppm, but it is difficult to further reduce the arsenic concentration. Further, when chlorinating antimony trichloride, it is common to introduce excessive chlorine in order to avoid the unreacted portion from remaining. However, the residual amount of chlorine in antimony pentachloride increases.

[0005]

An object of the present invention is to solve the above-mentioned problems in the conventional production method, and to provide high-purity antimony pentachloride in which the residual concentrations of arsenic and chlorine are extremely low, and to obtain the same in good yield. It is intended to provide a manufacturing method capable of performing the following.

[0006]

That is, the present invention relates to (1) a high-purity antimony pentachloride having a chlorine concentration of 0.1 wt% or less and an arsenic concentration of 1 ppm or less.

Further, the present invention relates to (2) a method for producing antimony pentachloride by introducing chlorine gas into a melt of antimony trichloride, wherein the temperature is higher than the boiling point of arsenic trichloride and lower than the boiling point of antimony pentachloride. Arsenic is volatilized and removed by allowing the chlorination reaction to proceed at a temperature. After the chlorination reaction is completed, a gas having no reactivity with antimony pentachloride is further introduced into the melt to remove the residual chlorine in the liquid. The present invention relates to a method for producing antimony pentachloride, which is driven out of the system by a gas to obtain high-purity antimony pentachloride with reduced contents of arsenic and chlorine.

[0008] The production method of the present invention comprises: (3) starting a chlorination reaction at a temperature not lower than the boiling point of antimony pentachloride;
Includes a production method in which the chlorination reaction is advanced by controlling the temperature to a temperature not lower than the boiling point of arsenic trichloride and not higher than the boiling point of antimony pentachloride. Further, in the above production method, (4) a production method in which the gas used in the dechlorination step is an inert gas or carbon dioxide gas,
(5) A production method in which the dechlorination step is performed at room temperature, and (6) a production method in which the obtained antimony pentachloride has a chlorine concentration of 0.1 wt% or less and an arsenic concentration of 1 ppm or less.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The production method of the present invention will be described below in detail. (I) Chlorination Step An antimony trichloride crystal is heated to a melting point (about 73 ° C.) or higher at normal pressure, and dry molten chlorine gas is blown into the melt to perform chlorination. This chlorination reaction is carried out in a temperature range not lower than the boiling point of arsenic trichloride and not higher than the boiling point of antimony pentachloride. Arsenic trichloride is converted to arsenic pentachloride by a chlorination reaction, but is decomposed at a reaction temperature of 80 ° C. or higher, and is considered to be present in the system as arsenic trichloride. The boiling point of arsenic trichloride at normal pressure is 13
0 ° C. and the boiling point of antimony pentachloride is 140 ° C. Therefore, the production method of the present invention is carried out at 130 ° C. to 1
The chlorination reaction is performed in a temperature range of 40 ° C. The chlorination reaction may be performed at normal pressure, but may be performed under reduced pressure. Since the boiling point under reduced pressure is lower than that under normal pressure, the reaction temperature is controlled accordingly. As the starting material, antimony trichloride may be directly introduced from the chlorination step of antimony metal or in the molten state.

By performing the chlorination reaction within the above temperature range, arsenic trichloride mixed in antimony trichloride volatilizes and is removed from the system. In addition, lead is often mixed with arsenic as an impurity, but lead tetrachloride (boiling point 110 ° C) generated by this chlorination reaction and hydrogen chloride (azeotropic point 110 ° C) generated by introduction of chlorine gas are also subjected to the above reaction. Volatile under temperature and removed out of the system. In this chlorination step, the arsenic concentration in the liquid is reduced to 1 ppm or less, and the residual concentration of lead is also reduced to 1 ppm or less.

The initial stage of the reaction is antimony trichloride (boiling point 221 ° C.)
, The melt does not boil even at a liquid temperature of 140 ° C. or higher. Therefore, in order to surely remove arsenic trichloride out of the system, it is preferable to perform chlorination at a temperature as high as possible within the above temperature range at the beginning of the reaction. That is, after starting the chlorination reaction at a temperature higher than the boiling point of antimony pentachloride (normal pressure 140 ° C. or higher), it is higher than the boiling point of arsenic trichloride and lower than the boiling point of antimony pentachloride (normal pressure 130 ° C. to 140 ° C.). The temperature is preferably controlled to allow the chlorination reaction to proceed.

Since heat is generated by the chlorination reaction, the temperature of the reaction system is preferably controlled according to the progress of the reaction.
In the conventional production method, the reaction system is cooled with water and the chlorination reaction is performed in the temperature range of the melting point of antimony trichloride (73 ° C.) to 100 ° C., but the production method of the present invention is considerably higher than before. Perform chlorination reaction in the temperature range.

As the chlorination reaction proceeds, antimony trichloride is converted to antimony pentachloride. At the end of the reaction, the blowing of chlorine gas may be terminated when unreacted chlorine gas is discharged out of the system. Note that chlorine gas is introduced in a slightly excessive amount than the reaction equivalent so that unreacted antimony trichloride does not remain. The blowing amount of chlorine gas may be about 0.24 kg per 1 kg of antimony pentachloride.

(II) Dechlorination Step After producing antimony pentachloride by the chlorination reaction, an inert gas is blown into the liquid instead of chlorine gas. By the bubbling of the inert gas, chlorine remaining in the liquid is driven out of the system. The blowing amount of the inert gas may be about 6 liters per 1 kg of antimony pentachloride. By this dechlorination, the chlorine concentration in the liquid is reduced to about 0.1%. The gas used for bubbling is not limited to an inert gas, and may be any gas that does not react with antimony pentachloride such as carbon dioxide gas and is in a dry state. Further, these gases may be blown into the reaction vessel using a supply pipe into which the chlorine gas has been introduced after the blowing of the chlorine gas is completed. The temperature of the dechlorination step is preferably room temperature to 120 ° C. If the dechlorination step is carried out at 120 ° C. or higher, the generated antimony pentachloride is also undesirably discharged outside the system.

According to the above manufacturing method, the chlorine concentration is 0.1 w
High-purity antimony pentachloride having an arsenic concentration of 1 ppm or less and a low lead content is obtained. By the way, the content of arsenic, chlorine and lead of conventional antimony pentachloride is as follows:
As an example, arsenic is 50 ppm, chlorine is 2.0 wt%, and lead is 3 ppm. However, the impurity amount of antimony pentachloride according to the production method of the present invention is 1 ppm or less of arsenic, 0.1 wt% of chlorine, and 1 ppm or less of lead. Highly purified high purity antimony pentachloride.

[0016]

EXAMPLES AND COMPARATIVE EXAMPLES Examples 1 to 5 10 kg of antimony trichloride having the amount of impurities shown in Table 1 was added to 90
° C and melted, and the temperature of this melt is shown in Table 1.
(130 ° C. to 150 ° C.), and chlorine gas was blown into the melt at a flow rate of 0.5 kg / h for 6.5 hours. Thereafter, the introduction of chlorine gas was stopped, and instead nitrogen gas was blown into the melt at a flow rate of 5 L / min to cause bagling for 3 hours. The gas in the container was discharged out of the system together with the introduction of chlorine gas and nitrogen gas. Antimony pentachloride was obtained by this manufacturing process. Table 1 shows the amounts of impurities of this antimony pentachloride.

Comparative Example 1 According to a conventional production method, a melt of antimony trichloride (10 kg) was maintained at a temperature of 90 ° C., and chlorine gas was blown into the melt at a flow rate of 0.5 kg / h for 6.5 hours to perform chlorination. did. This was purified in a dry nitrogen atmosphere by reducing the pressure with a vacuum pump to 14 mmHg. The boiling point of this fraction was 68.5 ° C. The impurity concentration of antimony pentachloride is shown in comparison with Table 1.

Comparative Example 2 Antimony pentachloride was produced in the same manner as in Example except that the introduction of nitrogen gas was omitted (Comparative Example 2). The impurity concentration of antimony pentachloride is shown in comparison with Table 1.

[0019]

[Table 1]

[0020]

As shown in Table 1, the antimony pentachloride of the present invention has a much lower residual concentration of arsenic and chlorine than the conventional antimony pentachloride, and a high-purity pentachloride with a significantly reduced lead content. It is antimony. Further, according to the production method of the present invention, the high-purity antimony pentachloride can be easily produced.

Claims (6)

[Claims] 1. A high-purity antimony pentachloride having a chlorine concentration of 0.1 wt% or less and an arsenic concentration of 1 ppm or less. 2. When chlorinating gas is introduced into a melt of antimony trichloride to produce antimony pentachloride, the chlorination reaction proceeds at a temperature higher than the boiling point of arsenic trichloride and lower than the boiling point of antimony pentachloride. To volatilize and remove arsenic,
After the completion of the chlorination reaction, a gas having no reactivity with antimony pentachloride was further introduced into the melt, and residual chlorine in the solution was driven out of the system by the gas to reduce the contents of arsenic and chlorine. A method for producing antimony pentachloride, which comprises obtaining high-purity antimony pentachloride. 3. The chlorination reaction is started at a temperature higher than the boiling point of antimony pentachloride, and then controlled to a temperature higher than the boiling point of arsenic trichloride and lower than the boiling point of antimony pentachloride. The method according to claim 2. 4. The method according to claim 2, wherein the gas used in the dechlorination step is an inert gas or a carbon dioxide gas. 5. The dechlorination step is performed at room temperature.
Or the production method according to 4. 6. The obtained antimony pentachloride has a chlorine concentration of 0.1% by weight or less and an arsenic concentration of 1 ppm or less.
6. The production method according to any one of items 1 to 5,