JPH08198608A - Method for purifying phosphorus oxychloride - Google Patents

Abstract

PURPOSE: To easily separate off impurities difficult to separate and to obtain high-grade phosphorus oxychloride without conducting distillation, etc., by bringing groups 4 and 5 elements into contact with the phosphorus oxychloride contg. the impurities. CONSTITUTION: Groups 4 and 5 elements such as Cu are brought into contact with the phosphorus oxychloride contg. such impurities as the impurities in the raw material and the impurities (e.g. AsCl3 ) by-produced in the production to separate off the contained impurities. The elements are appropriately used in the form of powder and also used in the form of wire or sheet. As the appropriate method to bring the phosphorus oxychloride contg. impurities into contact with the elements, the elements are added to the product liq. reactant of phosphorus oxychloride, or the gaseous phosphorus oxychloride is passed through the packed elements. When the elements are added to the product liq. reactant of phosphorus oxychloride, the molar ratio of the elements to the total impurities is preferably controlled to 4 to 10. Consequently, the impurities are reduced to the order of <= severa ppm in terms of As and S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to impurities in the raw material yellow phosphorus in the production of phosphorus oxychloride, impurities by-produced mainly from sulfur and arsenic, and trichloride by-produced from variations in the molar balance of yellow phosphorus, chlorine and oxygen. The present invention relates to a method for removing phosphorus and phosphorus pentachloride.

[0002]

2. Description of the Related Art A method for producing phosphorus oxychloride by blowing chlorine gas and oxygen gas into yellow phosphorus is well known.
A number of manufacturing methods are known. The raw material yellow phosphorus contains yellow phosphorus, sulfur, arsenic, and other impurities including elements such as Al, Fe, Ca, Si, Fe, and Pb. In the process of producing phosphorus oxychloride, for example, S and As are chlorine gas. React to AsCl
It is known that ₃ and PSCl ₃ are by-produced. Also,
The molar balance of the raw materials may be disrupted, and due to slight deviations in temperature control, phosphorus trichloride and phosphorus pentachloride may be by-produced or may remain unreacted. Since these impurities are mixed in phosphorus oxychloride, they are generally purified by distillation or the like. However, in order to completely remove these impurities by distillation, rectification using a high-stage distillation apparatus was necessary.

There is also a method of purifying and removing sulfur and arsenic in the raw material yellow phosphorus in order to prevent by-products such as AsCl ₃ and PSCl ₃ , but this method is very dangerous.

The inventors of the present invention have made extensive studies as to a method for separating impurities in phosphorus oxychloride by a chemical reaction other than chemical engineering separation. As a result, the periodic solution is added to the reaction solution after the production of phosphorus oxychloride. By adding elements of the 4th to 5th periods in the table, As, S, PCl ₃ ,
The inventors have found that impurities such as PCl ₅ can be reduced to a concentration of several ppm or less, and have completed the present invention.

That is, according to the present invention, when producing phosphorus oxychloride, phosphorus oxychloride containing impurities and Periodic Tables 4 to 5 are used.
It is a method for purifying phosphorus oxychloride, which comprises contacting with a periodic element.

As the element used in the present invention, one or more kinds of transition elements or typical elements of the 4th to 5th periods of the periodic table, for example, Cu, Ni, Ag, Zn, Sn, etc., preferably Cu Is used. Of course, other elements may be used. At the time of use, the form of the element may be any form of powder, wire and plate, but use of powder usually gives good removal results. As a method of bringing the phosphorus oxychloride containing impurities into contact with the element, the element is added to the reaction solution of phosphorus oxychloride, or the phosphorus oxychloride gas is passed through the packing of the element. When an element is added to the reaction solution, the addition amount of the element varies depending on the content of impurities in the phosphorus oxychloride reaction solution, but is usually about 1 to 20 mole ratio, preferably 4 to 10 moles with respect to the total number of moles of impurities. Is a ratio. In principle, the metal elements are added individually, but they may be mixed and used. The removal temperature has a processing temperature of room temperature to 110 ° C.
It is best to carry out at the boiling point of phosphorus oxychloride (108 ° C.), although the degree is low. The treatment time varies depending on the treatment temperature, but when the treatment is carried out at the boiling point, it is 0.5 to 10 hours, and the economical and effective treatment time is 1 to 6 hours.

The element used in the present invention, in particular, the average particle size in the case of powder is 0.1 to 30 μm, preferably 2 to 10 μm for copper powder. The specific surface area of the powder is, for example, 0.05 to 5.0 m ^{2 to} g for copper powder,
It is preferably 0.5 to 2.0 m ² / g. Also, metal particles having a large particle size, for example, about 0.1 to 5 mm may be used, but since the specific surface area cannot be taken, the amount used is large and the glass lining of the reaction tank is adversely affected, and therefore it is not recommended.

Further, in order to carry out the present invention more efficiently, either the powder of the metal element is added and then stirred and the temperature is raised to the boiling point of phosphorus oxychloride, or the powder of the metal element is added after boiling. The method of is also good. It is not recommended to use without stirring, but it requires time and the post-treatment is complicated such that the metal powder is hardened in the tank. The amount of metal added is 2
There is no problem even if the operation is divided into three parts. If the added metal powder is, for example, copper powder, the light pink luster disappears and the powder changes to black powder. This powder can be recycled, but it is not normally used. After reacting for a certain period of time under boiling, post-treatment is carried out according to a conventional method. As S of the phosphorus oxychloride reaction solution from which the treated powder has been separated, the content of PCl ₃ , PCl _5, etc. as S is reduced to the order of several ppm or less. Although the reaction solution can be used as it is, it is slightly colored, so that high-purity phosphorus oxychloride containing almost no impurities can be obtained almost quantitatively by performing ordinary distillation.

When phosphorus oxychloride gas is passed through the packing of elements, steam heating or electrical heating is used so that phosphorus oxychloride does not condense in the packing and is circulated by gas. It is necessary to let Otherwise, the treatment method is the same as the submerged treatment.

Next, the present invention will be described in more detail with reference to examples. Example 1 A reaction solution of phosphorus oxychloride containing AsCl ₃ and PSCl ₃ (containing 200 ppm of As and 74 ppm of S) (550 g) was charged into a 500 ml four-necked flask equipped with a thermometer, a Teflon stirring blade and a Dimroth condenser, Next, 1.22 g of powdered copper powder having an average particle size of 2.13 microns and a specific surface area of 0.703 m ² / g (Cu mole number / As + S total mole number = 7.0 mole ratio) was charged and slowly stirred with a mantle heater. The temperature was raised to the boiling point of phosphorus oxychloride by heating. The internal temperature is 70 ℃
The copper powder gradually began to turn black from the position (approx. 30 minutes). At the boiling point, the whole was dark and was dispersed and stirred. 10
After continuing stirring at 7 to 108.2 ° C. for 2 hours, it was cooled to room temperature by air cooling. A part of the reaction solution was collected and the copper powder was filtered. When this liquid was measured by a high frequency inductively coupled plasma optical emission spectrometer (ICP), As was 0.2 ppm, S
As a result, a value of 2 ppm was obtained.

Example 2 250 g of a phosphorus oxychloride reaction solution containing AsCl ₃ (190 ppm as As) and PSCl ₃ (76 ppm as S) as impurities was charged in a 4-necked flask equipped with a thermometer, a stirring blade and a Dimroth condenser. . Next, 0.55 g of electrolytic copper powder (dendritic powder) was charged. (Cu mole number / As + S mole number = 7.0 mole ratio) The average diameter of the copper powder is 5.64 microns and the specific surface area is 0.2.
It was 65 m ² / g. The temperature was raised by heating the mantle heater while stirring. From around 60 ° C, the light pink copper powder gradually became black. After stirring at the boiling point of phosphorus oxychloride for 4 hours, the mixture was cooled to room temperature. A liquid obtained by collecting a part of the reaction liquid and filtering the copper powder was subjected to ICP analysis to obtain 0.2 p as As.
A value of 2.6 ppm was obtained as pm and S. This yellow processing liquid (copper powder as it is) was used for a Wiggly distillation column (length 20
247 g of colorless phosphorus oxychloride after slowly distilling
I got (Distillation recovery rate 98.8 w / w%) This product was subjected to ICP to obtain an analytical value of not detected as As and 0.5 ppm as S.

Example 3 Using the same processing apparatus as in Example 1, 15 p as As
Phosphorus oxychloride reaction solution 4 containing 15 ppm as pm and S
One copper particle 5 having an average weight of 0.0119 g per 00 g
7.3 g was charged, and the reaction was performed under reflux for 6 hours in consideration of the specific surface area. After cooling to room temperature, the supernatant was sampled and subjected to ICP analysis, As: 0.5 ppm, S: 1.2
A ppm result was obtained. The surface of the copper particles was changed from pink to black.

Example 4 The same processing apparatus as in Example 1 was used to obtain 20 As.
To 500 g of phosphorus oxychloride reaction liquid containing 0 ppm and 80 ppm as S, 0.49 g (3.0 mol ratio) of flaky copper powder having an average diameter of 2.13 microns and a specific surface area of 0.703 m ² / g was stirred at room temperature. And heated to boiling in about 26 minutes. Reflux for 2 hours, sample a part of the reaction solution, filter the copper powder, and perform ICP analysis.
It was 7 ppm and S: 65 ppm. Next, the same copper powder
After charging 65 g (4.0 mol) under boiling and refluxing for 2 hours and cooling, a part of the reaction solution was sampled and IC
As a result of P analysis, As was 0.1 ppm and S was 1 ppm.

Example 5 A 5-necked flask equipped with a stirring blade was prepared, a spherical glass tube was attached to one of the necks, and 63.5 g (specific surface area: 0) of copper particles having a particle size of 1.45 mm was placed between the glass wools. The specific surface area was made to be the same as that of copper powder of .268 m ² / g.) The filled one was set. The specific surface area of the copper particles was 352 cm ² / g. The tip of the ball was connected to a Dimroth condenser set on another neck so that the vaporized phosphorus oxychloride could return to the inside of the flask, and the sheath heater was wound so as not to cause a condes on the way. Also, a liquid seal was provided on the way to prevent backflow. In this: As: 12
ppm, S: phosphorus oxychloride 700 containing 11 ppm
I charged g. The temperature of the flask was slowly raised with stirring. The gas phase reaction was carried out for 5 hours while controlling the temperature so that the temperature was raised to the boiling point and the liquid was slowly circulated. When a part of the circulating liquid was sampled and analyzed by ICP, As: 0.3 ppm and S: 0.9 ppm were obtained.

Example 6 5000 liters of a reaction solution of phosphorus oxychloride containing 22 ppm of As and 16 ppm of S was charged.
3.0 g of flaky copper powder having an average diameter of 2.13 microns and a specific surface area of 0.703 m ² / g in a GL reactor equipped with a stirrer of m ^3.
g was added at room temperature with stirring. Then, while passing steam, it took about 70 minutes to raise the temperature to boiling. The mixture was stirred under reflux for 4 hours and then cooled. The copper powder was treated by a conventional method and a part of the reaction solution was sampled for ICP analysis.
The As and S contents of the removed phosphorus oxychloride reaction solution are A
s was 0.1 ppm and S was 0.6 ppm. As was not detected in the distilled product obtained by distilling this liquid at a reflux ratio of 0.5, and S was 0.2 ppm.

Example 7 Using the same reactor as in Example 1, 69 p as As
Phosphorus oxychloride reaction solution 8 containing 66 ppm as pm and S
50 g was charged, 8.0 g (5.0 mol ratio) of copper powder and 5.0 g (3.0 mol ratio) of zinc powder were added, and the mixture was refluxed under boiling for the same time and then treated according to a conventional method. When a part of the liquid is analyzed, 0.7 ppm as As and 3.1 p as S
The value of pm was obtained. It was ppm.

The charged reaction solution 600g of phosphorous oxychloride containing Example 8 PCl ₃ 1.2 wt% to 4 necked flask 500ml Teflon stirring blade and Bariteru type capacitor is set, then the average particle size of 2.13 microns , Specific surface area 0.703m
23.3 g of ² / g copper powder (Cu / PCl ₃ molar ratio =
7.0) was charged and slowly heated with a mantle heater while stirring to raise the temperature to the boiling point of phosphorus oxychloride. Approximately 20 minutes after boiling, the copper powder gradually became dark and began to change color. Thereafter, the entire copper powder became black and solidly solidified without being solidified under stirring. 106 ~
After stirring at 108 ° C. for 5 hours, the mixture was air-cooled and cooled to room temperature with stirring. A part of the reaction solution was sampled and the copper powder was filtered through a filter paper with folds. When this solution was measured by FT-NMR ( ³¹ P) using a probe modified for measuring phosphorus compounds, PCl ₃ was not detected. The GC analysis revealed that the PCl ₃ content was ND. On the other hand, the classical volumetric analysis result showed that the PCl ₃ content was 0.006 wt%.

Example 9 500 g of a phosphorus oxychloride reaction solution containing 192 ppm of PCl ₃ as an impurity was charged into a 500 ml four-necked flask equipped with a Varitail condenser, a thermometer and a stirring blade. Next, 0.32 g of flaky copper powder (Cu / PCl
₃ = 7 molar ratio) was charged. The average particle size of copper powder is 5.68.
Micron, specific surface area was 0.273 m ² / g. Stirring was started and the temperature was raised by heating with a mantle heater. About 15 minutes after boiling, the shiny copper powder turned black. After stirring at the boiling point of phosphorus oxychloride for 5 hours, the mixture was cooled to room temperature. A part of the reaction solution was collected, the copper powder was removed by filtration, and PCl ₃ was quantified by FT-NMR ( ³¹ P), which was not detected. A volumetric analysis gave a value of 0.004 wt%.

Example 10 560 g of a phosphorus oxychloride reaction solution containing 528 ppm of PCl ₃ was thermometered, a stirring blade and a Dimroth condenser,
The mixture was placed in a 500 ml-4 neck flask with a silica gel tube set. Next, 1.00 g of electrolytic copper (dendritic powder) (Cu
/ PCl ₃ molar ratio = 7.0). Copper powder has an average particle size of 5.66 microns and a specific surface area of 0.306 m ² / g
Met. The mixture was heated with a mantle heater while stirring and heated.
About 20 minutes after boiling at 108 ° C., the copper powder turned black. After stirring and heating at this boiling point for 5 hours, it was cooled to room temperature by air. When the content of PCl ₃ was analyzed in the same manner as in Example 1 with respect to the liquid obtained by sampling a part of the reaction liquid and filtering the copper powder, it was not detected.

Example 11 Phosphorus oxychloride reaction solution 5 containing 0.002 wt% of PCl ₃
200 liters of 6m ^{3 with} a stirrer G
L reactor with an average diameter of 2.20 microns and a specific surface area of 0.7
0.573 kg of 1 m ² / g flaky copper powder was charged and heated with steam under stirring to raise the temperature to the boiling point of phosphorus oxychloride, and then under reflux with stirring for 6 hours. The reaction tank was cooled to normal temperature, copper powder was removed by a conventional method, a part of the reaction solution was sampled, and quantitatively determined by ³¹ P-NMR, and residual PCl ₃ was not detected. On the other hand, a value of 0.001 wt% was obtained by volumetric analysis.

Example 12 A 5-neck flask was prepared and a glass tube (length 1
0 cm, diameter 1.6 cm) was set, and both ends were packed with glass wool, and 86 g of copper particles having a particle size of 1.45 mm were packed between them. (Specific surface area: 552 cm ² / g) A thermometer and a stirring blade were set on the other neck. A condenser was connected to the upper part of the glass tube so that vaporized phosphorus oxychloride could return to the inside of the flask so as not to be liquefied on the way, and a sheath heater was wound to control. 9 mL of PCl _{3 in} this flask
680 g of phosphorus oxychloride containing 2 ppm was added. While stirring, the temperature was slowly raised to boiling and the liquid was vaporized and circulated, while controlling the temperature with a mantle heater, the copper particles and the gas of phosphorus oxychloride were brought into gas phase contact with each other and reacted for 7 hours. Sampling a part of the circulating reaction solution, ³¹ P
PCl ₃ residual amount Once you have quantified by -NMR was undetected. On the other hand, the volumetric analysis was 0.001 wt% or less.

Example 13 A 2.0-liter 4-neck flask was charged with 1.0 liter of a phosphorus oxychloride reaction solution containing 0.011 wt% of PCl _{3, and} 0.600 g of copper powder and 1.120 g of tin powder were stirred.
Was charged to a boiling point, and the mixture was kept under reflux for 5 hours. After the reaction is complete, the mixture is air-cooled and cooled to room temperature, a part of the reaction solution is sampled, the metal powder is filtered, and the residual P
Cl ₃ was measured and a value of 9 ppm was obtained.

Example 14 Phosphorus oxychloride reaction solution 6 containing 0.053 wt% of PCl ₃
A 500 ml 4-necked flask was charged with 00 g, and 1.10 g of zinc powder was charged with stirring, the temperature was raised, and the mixture was kept under reflux at the boiling point of phosphorus oxychloride for 6 hours. After completion of the reaction, after air cooling and cooling to room temperature, a part of the reaction solution was sampled, zinc powder was separated, and residual PCl ₃ was measured by volumetric analysis.
It was 0.0009 wt%.

[0024] is Example 15 PCl ₃ as 0.92% and AsCl ₃ (As 1
1200ppm of phosphorus oxychloride reaction solution containing 10ppm) and PSCl ₃ (58ppm as S) 1000ml with Teflon stirring blade and Varitail condenser
In a 4-necked flask, and then 38.0 g of copper powder having an average diameter of 2.20 microns and a specific surface area of 0.723 m ² / g.
(Cu / PCl ₃ + As + S molar ratio = 7.0) was charged and slowly heated with a mantle heater while stirring to raise the temperature to the boiling point of phosphorus oxychloride. About 2 after the temperature starts
After 5 minutes, the added copper powder gradually became dark and began to change color. After that, the copper powder became black in its entirety but did not solidify and was in a state of being uniformly dispersed under stirring.
After continuing stirring at 106 to 108 ° C. for 5 hours, the mixture was air-cooled and cooled to room temperature. When this solution was measured by FT-NMR ( ³¹ P) using a probe modified for measuring phosphorus compounds, no PCl ₃ content was detected. Further, in the volume analysis, the residual amount of PCl ₃ was 0.003 wt% or less.
On the other hand, in order to confirm the remaining amounts of As and S, the reaction solution was separately sampled and subjected to ICP analysis.
It was 2 ppm and S was 2 ppm.

Example 16 A 200 ml 4-necked flask was charged with AsCl ₃ (as As 46
ppm), PSCl ₃ (33 ppm as S) and PCl
_{5 A} phosphorus oxychloride solution containing 27.15 g (0.130 mol) was prepared. After this liquid was stirred and kept under reflux for 1 hour, 82 g of Cu powder (1.29 mol, Cu / As + S
+ PCl ₅ = 7.5 molar ratio) was added. Then, it was kept under reflux (104 to 106 ° C.) for 4 hours. The added copper powder was black. After cooling the reaction solution, a part of it was sampled and 0.7 ppm as As was measured by ICP.
2.0 ppm as S, PCl _{5 by} ³¹ P-NMR measurement
Was not detected.

Comparative Example 1 500 ml of a phosphorus oxychloride reaction solution containing 52 ppm as As and 36 ppm as S was charged in an Erlenmeyer flask,
Using a 30 cm Widmer rectification column, the whole solution was slowly distilled over 5 hours. If this liquid is analyzed by ICP, As
Of 12 ppm and S of 16 ppm were obtained.

Comparative Example 2 6000 liters of a phosphorus oxychloride reaction solution containing 31 ppm as As and 18 ppm as S was distilled at a reflux ratio of 3 for 13 hours using a 30 m packed column. Distillation yield is 9
It was 9.2%. ICP analysis of a part of 5950 liters of the obtained product revealed that it contained 5.0 ppm as As and 10 ppm as S.

Comparative Example 3 5500 liters of a reaction solution of phosphorus oxychloride containing 0.1% AsCl ₃ was rectified using a 10 m packed column at a reflux ratio of 3 for 12 hours. At the time of 4000 liters of Hondome, part of the sample was sampled and analyzed by ICP.
It was contained as 72 ppm. The distillate was 4800 liters, leaving 700 liters remaining in the kettle, but when this solution was sampled and ICP analysis was performed, it was 0.7% as As.
Met.

Comparative Example 4 The same reaction method as in Example 1 was repeated except that CuO was used in a molar ratio of 7.0, but As and S were not removed at all.

COMPARATIVE EXAMPLE 5 CuCl7.
PCL ₃ was removed using a 5 molar ratio and a similar analysis was conducted, but PCL ₃ was not removed at all.

[0031]

EFFECTS OF THE INVENTION According to the purification method of the present invention, as is apparent from the comparative examples, impurities that are difficult to separate can be easily separated and removed without performing operations such as distillation, and high-quality phosphorus oxychloride can be almost quantified. This is a very excellent method industrially because it can be obtained in a desired manner.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Miyaki 300 Mukaihonmachi, Takaoka City, Toyama Prefecture Inside the Takaoka Factory of Nippon Soda Co., Ltd.

Claims (2)

[Claims] 1. A method for purifying phosphorus oxychloride, which comprises contacting phosphorus oxychloride containing impurities with an element of the 4th to 5th periods of the periodic table in the production of phosphorus oxychloride. 2. The elements of the 4th to 5th periods of the periodic table are Cu and A.
The method for purifying phosphorus oxychloride according to claim 1, which is g, Zn, Sn, or Ni.