JPH09215920A - Method for treating halogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the generation of a polymeric by-product and to dehalogenation-decompose efficiently and almost completely by reacting a halogen compound with dispersed alkali metal in specified conditions of temperature and the concentration of the halogen compound. SOLUTION: When a halogen compound such as polychlorobiphenyl is dehalogenation-decomposed by dispersed alkali metal, the reaction is carried out in an organic solvent at 10-70 deg.C with the concentration of the halogen compound kept not exceeding 1%. The quantity of the alkali metal for the halogen compound is 1-50 times, preferably 1.05-20 times, the theoretical quantity, and 2.0 or less mol, preferably 0.1-1.5mol, of an active hydrogen compound is used for 1mol of the alkali metal. Kerosene, transformer oil, benzene, toluene, etc., are used as the organic solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of dehalogenating and decomposing halogen compounds such as polychlorinated biphenyls (hereinafter abbreviated as PCB) with an alkali metal dispersion.

[0002]

2. Description of the Related Art When dehalogenating a halogen compound in an organic solvent with an alkali metal dispersion, a side reaction product of a polymer is likely to be produced depending on the reaction conditions, and the post-reaction treatment becomes complicated. Further, since the dehalogenation reaction of the side reaction product of the polymer is slow, there is a problem that once it is generated, it takes time to complete the reaction. A method of dehalogenating and decomposing a halogen compound with an alkali metal dispersion is described in JP-A-49-82570 and the like, but according to the examples, the reaction is carried out at a temperature of 100 ° C. or higher. However, a high-molecular side reaction product was produced, and the post-treatment was troublesome.

[0003]

The object of the present invention is to dehalogenate a halogen compound with an alkali metal dispersion quickly, efficiently and almost completely by suppressing the formation of a polymer side reaction product. And

[0004]

Means for Solving the Problems When the halogen compound and the alkali metal dispersion are reacted in an organic solvent at a low temperature of 10 ° C. or higher and 70 ° C. or lower, the inventors of the present invention have a halogen compound concentration of 1 It was found that by carrying out the reaction at a low concentration of not more than 100%, the production of side reaction products of the polymer can be suppressed and the dehalogenation decomposition can be carried out almost completely.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is carried out in an organic solvent at a temperature of 10 ° C. or higher and 70 ° C. or lower at a halogen compound concentration of 1% in the reaction solution.
This can be achieved by reacting a halogen compound with an alkali metal dispersion under the following conditions, but if necessary, an active hydrogen compound may be added to increase the reaction rate, so that the effect can be further enhanced. The active hydrogen compound does not need to be uniformly mixed with the organic solvent, and water, methanol, etc., which have little influence on the post-treatment, are suitable. The order of adding the halogen compound, the alkali metal dispersion, and the active hydrogen compound is not particularly limited, and one or some of them may be added dropwise at the end.

The addition amount of the alkali metal dispersion is 1 to 50 times the theoretical amount with respect to the halogen compound, preferably 1.05.
~ 20 times the amount used. The amount of the active hydrogen compound added is 2.0 times or less, preferably 0.1 to 1.5 times the mol of the alkali metal dispersion.

The reaction time may be any time at which the reaction is completed, but is preferably 0.5 to 3 hours. However, when the concentration of the halogen compound is high, it is necessary to add the halogen compound so that the concentration of the halogen compound in the reaction solution becomes 1% or less. Therefore, it is preferable to extend the reaction time if necessary.

As the organic solvent, kerosene, transformer oil,
Aliphatic or aromatic hydrocarbons such as benzene, toluene and xylene are used. For safety, the present invention is preferably operated under an atmosphere of an inert gas such as argon or nitrogen.

Sodium as the alkali metal dispersion,
Potassium, lithium, rubidium, cesium or their alloys with kerosene, trans oil, benzene, toluene,
A solvent dispersed in an inert organic solvent such as an aliphatic or aromatic hydrocarbon such as xylene is used, and the solvent at that time may be the same as that used in the decomposition reaction of the halogen compound described above, or It can be different. Further, a dispersant such as aluminum stearate and an anti-aggregation agent may be added in advance. When a solvent that stabilizes an alkali metal dispersion such as a high viscosity solvent is used as the solvent, the dispersant and the anti-aggregation agent are No need to add.

The alkali metal concentration in the alkali metal dispersion may be any concentration, but is preferably about 5 to 50%.

After the reaction, a large amount of methanol, water or an aqueous solution of alkali metal halide is added or the reaction solution is added therein to decompose the alkali metal dispersion, and then neutralize or separate liquids. The necessary post-processing is performed to complete the processing.

When the reaction conditions are inappropriate, a large amount of insoluble polymer side reaction product is produced, which makes liquid separation difficult and also involves considerable difficulty in performing filtration for removal thereof. Since halogen in the polymer side reaction product is hard to escape, if a nearly complete dehalogenation decomposition is required, a longer reaction time is required. When the halogen compound concentration is low at a low temperature, which is the reaction condition of the present invention, the dehalogenation reaction is easily completed because polymer side reaction products are scarcely produced.
The polymer side reaction product can be confirmed by HLC analysis using a GPC column.

[0013]

【Example】

Example 1 In a 200 ml three-necked flask equipped with a thermometer and a stirrer,
PCB with an average of 3 nuclear substitution chlorine (Kanebuchi Chemical Co., Ltd., trade name Kanechlor 300) (hereinafter KC-3
(Abbreviated as 00) 0.02 g was dissolved in 50 ml of decalin and charged with 50 ml of a 400 ppm KC-300 decalin solution, and argon gas was swirled under stirring. 0.6 g of a 40 wt% sodium dispersion (hereinafter abbreviated as SD) having an average particle diameter of 10 μm, which was prepared by adding 1% to sodium and using a decalin solvent, was added, and
The reaction was performed at 0 ° C. for 1 hour. After the reaction, the mixture was cooled to 50 ° C. or lower, and then 10 ml of water was added dropwise while further cooling to decompose the remaining SD. After that, 50 ml of water was added and then filtered. There was almost no insoluble matter by filtration. The filtered mother liquor was separated, and the organic layer was further washed twice with 50 ml of water and separated. The water layer was collected, a part of it was neutralized with dilute nitric acid, and the chloride ion was analyzed by silver nitrate titration.
00%. After taking 1 ml of the organic layer and subjecting it to silica gel column chromatography with a hexane solvent, 1 ppm of P was added.
Analysis by gas chromatography with an ECD detector under conditions where CB could be detected, but PCB was not detected.

Example 2 In the same manner as in Example 1, 50 ml of 400 ppm KC-400 transformer oil solution and 0.05 g of water were charged, and 50
Made in transformer oil without dispersant at ℃ 10
% SD2.6g was added and it was made to react at 50 degreeC for 1 hour. The post-treatment was carried out in the same manner as in Example 1, but as in Example 1, there was almost no filtration insoluble matter, and the chlorine ion recovery rate in the aqueous layer was almost 1.
At 00%, no PCB was detected in the organic layer.

Reference Example 1 By the same method as in Example 1, 20000 ppm KC-30
50 ml of 0 decalin solution was charged, 50.1 g of 40 wt% SD prepared in the same manner as in Example 1 was added at 100 ° C., and the mixture was reacted at 100 to 120 ° C. for 1 hour. After the reaction, the temperature was cooled to 50 ° C or lower, and then, while further cooling, methanol was added.
60 ml was added dropwise to decompose the remaining SD. Then, 100 ml of water was added and the mixture was filtered and dried to obtain 0.36 g of a polymer compound containing aluminum stearate. The filtered mother liquor was separated, and the organic layer was further washed twice with 50 ml of water and separated. When the chlorine ion of the water layer was analyzed, the recovery rate was 79.4%. No PCB was detected in the organic layer. In addition, the polymer compound in the organic layer was used as Shodex GPC KF-802.
Analysis by HLC analysis using a column (Eluent THF) showed the presence of large amounts of polymeric compounds.

Reference Example 2 In the same reaction as in Reference Example 1, the reaction temperature was room temperature for 1 hour and 100 to 120 ° C. for 1 hour. The same post-treatment as in Reference Example 1 was performed to obtain 0.27 g of a dried filter product. The chlorine ion recovery rate was 91.9%, PCB was not detected in the organic layer, and it was confirmed that a small amount of the polymer compound was present in the organic layer.

Reference Example 3 50,000 ppm KC-300 was prepared in the same manner as in Reference Example 1.
Charge 20 ml of decalin solution, 40% SD2 at 50 ℃
7.4 g was added and reacted at 50 ° C. for 4 hours. Reference example 1
Post-treatment was carried out in the same manner as above to obtain 0.36 g of a filtered and dried product. The chlorine ion recovery rate was 80%, and PCB was not detected in the organic layer.

Example 3 The same reaction as in Reference Example 3 was carried out by dropping the PCB solution in 1 hour. Post-treatment was carried out in the same manner as in Reference Example 3 to obtain 0.12 g of a dried filter product. The chlorine ion recovery was 95%, and PCB was not detected in the organic layer.

[0019]

INDUSTRIAL APPLICABILITY In the reaction between a halogen compound and an alkali metal dispersion, generation of by-products can be suppressed, post-treatment can be facilitated, and dehalogenation decomposition can be carried out almost completely.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Kamiyama 345 Takada, Odawara-shi, Kanagawa Odawara Research Institute, Nippon Soda Co., Ltd.

Claims (4)

[Claims] 1. A method for dehalogenating a halogen compound, which comprises reacting the halogen compound with an alkali metal in a dispersed state at a temperature of 10 ° C. to 70 ° C. and a halogen compound concentration of 1% or less. 2. The method according to claim 1, wherein the reaction temperature is 45 ° C. or higher and 55 ° C. or lower. 3. The concentration of the halogen compound in the reaction solution is 0.1.
% Or less, The method according to claim 1 or 2. 4. The halogen compound is a hardly decomposable halogen compound such as polychlorinated biphenyls.
Method described in