JPH08217427A - Purification of phosphorus oxychloride - Google Patents

Abstract

PURPOSE: To obtain a high-grade purified product by blowing an ozone gas into phosphorus oxychloride in a production of phosphorus oxychloride and removing impurities without separating operation such as distillation. CONSTITUTION: In a production of phosphorus oxychloride blowing a chlorine gas and an oxygen gas into yellow phosphorus, the objective purified product of phosphorus oxychloride is obtained by removing impurities in a generated material derived from a raw material in treating with an ozone gas containing 1-70g/m<3> in an amount of 2-4 times mol of S-content of the impurities at a temperature around boiling point of phosphorus oxychloride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing impurities by blowing ozone gas into impurities in raw material yellow phosphorus in the production of phosphorus oxychloride, especially impurities by-produced from sulfur and arsenic contained therein.

[0002]

2. Description of the Related Art Phosphorus oxychloride is generally produced by blowing chlorine gas and oxygen gas into yellow phosphorus. However, impurities by-produced from the impurities in the raw material yellow phosphorus are mixed into the product, so the purification method is an important issue. Is.

Conventionally, as a purification method of phosphorus oxychloride, a method of stripping and separating a low boiling point material, a method of rectifying at a reflux ratio, etc. are generally performed. However, although such a method is effective when the content of impurities is relatively large, it has a drawback that it is not very effective when the content of impurities is small.

[0004]

Means for Solving the Problems The inventors of the present invention have made various studies on purification methods, and by blowing ozone gas into phosphorus oxychloride, impurities such as sulfur in yellow phosphorus, which is one of the raw materials for producing phosphorus oxychloride, are added as secondary substances. The inventors have found that the PSCl _{3 and the} like produced can be removed, and completed the present invention.

That is, the present invention is a method for purifying phosphorus oxychloride, which comprises removing impurities by treating them with ozone gas in the production of phosphorus oxychloride in which chlorine gas and oxygen gas are blown into yellow phosphorus.

The ozone gas used to carry out the present invention is generated by an ozone generator and blown into phosphorus oxychloride containing PSCl _{3 and the} like. The concentration of ozone gas is not particularly limited, but is 1 to 70 g / m ³ , preferably 10 to 6
It is 0 g / m ³ . If the concentration is too high, there is a problem that materials, especially resin materials, cannot be used, and there is a danger to the human body in the case of leakage, and it is a dimer of phosphorus oxychloride.
_It is not preferable because the amount of ₂ O ₃ Cl ₄ by-product increases. Even if the concentration of ozone gas is low, there is no problem in the reaction, but since a large amount of gas is collected and phosphorus oxychloride that escapes with the gas is collected, a large cooling device is required, which is not economically preferable. The reaction may be carried out at room temperature, but it is preferable to introduce ozone gas at or near the boiling point of phosphorus oxychloride. It is sufficient to use ozone gas in an amount of 2 to 4 times the mol of the S content. If the amount introduced is larger than this, it does not affect the reaction, but it is not economically useful.

[0007]

Next, the present invention will be described in more detail with reference to examples. Example 1 A 300 ml four-necked flask equipped with a variter condenser.
A thermometer and a stirring blade were set, and an ozone gas blowing tube was set. Next, 102.3 g of phosphorus oxychloride containing 10% by weight of PSCl ₃ was charged into the flask and heated and boiled while stirring. Next, the ozone generator was operated and blown. Ozone gas concentration is 1.05 × 10 ^-3 mol /
Blown in liters for 5 hours. The amount of ozone blown is 0.
It was 158 mol. Brine at -30 ° C was circulated through the condenser to prevent gas entrainment of the reaction. The exhaust gas was trapped with a 20% NaOH solution.
After completion of the reaction, when cooled to room temperature, a very small amount of white precipitate was deposited. The reaction liquid recovery rate was 99.7 wt%. After confirming the residual PSCl ₃ in the reaction solution by ICP analysis,
It was 02 mol%. Example 2 A 300 ml four-necked flask was set in the same manner as in Example 1, brine-cooled, and the condenser was cooled to -25 ° C. On the other hand, 30 Nl / Hr of oxygen gas was supplied to the ozone generator.
And ozone gas was adjusted so as to have a concentration of 1.0 × 10 ⁻³ mol / liter. On the other hand, 7 as S in the flask
295.2 g of phosphorus oxychloride containing 5 ppm was charged. After heating and refluxing, ozone gas which had been purged was blown thereinto to carry out a reaction for 3 hours. The total amount was weighed after stopping the gas blowing and cooling. Recovery rate is 9
It was 9.3 wt%. When a part of the reaction solution was sampled and analyzed by ICP, it was S: 10 ppm. Also, P
₂ O ₃ Cl ₄ was produced as a byproduct of 0.2 mol% / POCl ₃ . Example 3 The same reaction method as in Example 1 was performed in a 300 ml flask.
Phosphorus oxychloride containing 1 wt% PSCl ₃ 30
1.2g was charged. The reaction was carried out for 4 hours at an oxygen flow rate of 30 Nl / Hr and an ozone concentration of 1.12 × 10 ⁻³ mol / liter. The reaction liquid recovery rate was 98.6 wt%. When post-treatment was performed and ICP analysis was performed in the same manner as in Example 1, the PSCl ₃ concentration was 0.081 wt%. In addition, P ₂ O ₃ Cl ₄ was produced as a byproduct of 0.2 mol% / POCl ₃ . Example 4 Using the same reactor as in Example 1, 220 g of phosphorus oxychloride having a PSCl ₃ concentration of 4.8 mol% was charged. The reaction was carried out for 5 hours at an oxygen flow rate of 75 Nl / Hr and an ozone concentration of 5.13 mol / liter. Liquid weight recovery rate is 98.4 wt%
Met. After cooling, the PSCl ₃ concentration in the reaction solution was measured and was not detected. As a by-product, 0.6 mol
% / POCl ₃ of P ₂ O ₃ Cl ₄ was confirmed by NMR. Comparative Example 1 710 g (containing S: 1000 ppm) of a reaction solution of phosphorus oxychloride was charged in a 500 ml eggplant-type distillation apparatus and distilled at a reflux ratio of 4 for 7 hours using a rectification column corresponding to 6 stages. When a part of the main stream was sampled and analyzed by ICP, a value of S of 560 ppm was obtained. Recovery rate: 98.2 wt%.

[0008]

As is apparent from the comparative examples, the purification method of the present invention can easily separate and remove impurities that are difficult to separate without performing a chemical engineering separation operation such as distillation to obtain a high-grade oxidant. Since phosphorus chloride can be obtained almost quantitatively, it is an industrially excellent method.

Claims (2)

[Claims] 1. A method for purifying phosphorus oxychloride, which comprises removing impurities by treating them with ozone gas in the production of phosphorus oxychloride by blowing chlorine gas and oxygen gas into yellow phosphorus. 2. The concentration of ozone gas is 1.0 g / m ^{3 to} 7
The purification method according to claim 1, which is 0 g / m ³ .