JP3247543B2 - Alkali decomposition method for halogenated aromatic compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Completely and safely decomposing halogenated aromatic compounds for environmental protection has been a serious concern for more than 20 years. The present method relates to a method for achieving the above objective chemically.

[0002]

2. Description of the Related Art Hitherto, many efforts have been made regarding removal or decomposition of halogenated aromatic compounds. Some examples are shown in U.S. Pat. S. P.
2,951,804 describes the alumina-alkali method. Further, U. S. P. No. 4,532,028 discloses a method in which an alkali and 50,000 ppm or less of PCB are reacted at 200 ° C. or less in a mixture of an alkyl or alkylene sulfoxide and a polyol to give several ppm. Other examples include Canadian Patent 408,116 which uses a melt of sodium and Italian Patent 22,215 which uses an alkaline earth metal adsorbed with polyethylene glycol, but still removes PCBs to a substantially safe concentration. Has not been realized. Recently, a reduction method using paraffin as a hydrogen source has also been studied, but this method has a drawback that the residual ratio of PCB is about 1 ppm and the reaction temperature is high.

[0003]

The above-mentioned prior arts have their respective features and are expected to be quite effective. However, in practice, the solvent is not suitable for a large amount of alkaline substances at 150 ° C. or more. It cannot be said that it is a technology that can be implemented industrially, such as that it cannot withstand very high temperatures. The present inventors have conducted many experiments particularly on the action of alkali, and as a result, have solved these problems.

[0004]

Means for Solving the Problems The present inventors have selected a special polar solvent having a high boiling point, heat resistance, and alkali resistance, and have a ratio of the halogenated aromatic compound and the amount which is much larger than the amount dissolved in the polar solvent. It has been found that the method of contacting with an alkali substance at 150 ° C. or more and 300 ° C. or less is an effective means for substantially decomposing a halogenated aromatic compound below the detection limit of a currently known method.

The polar solvents selected here are those which are readily available on the market and have low toxicity, high heat resistance and strong alkali resistance. Dissolve. As the reaction progresses, it is required that the halogenated aromatic compound in the solvent be advanced from the concentration of several mg / kg to the detection limit or less (0.5 ppb or less) to complete the reaction. The present invention has solved just that.

The aprotic polar solvent effective in the present invention, which is heat-resistant, alkali-resistant and low in toxicity, is 1,3-dimethyl-
Either 2-imidazolidinone (hereinafter abbreviated as DM1), tetramethylene sulfone (hereinafter abbreviated as sulfolane), or a mixture of both in an arbitrary ratio, and in some cases, dimethyl sulfoxide, N-methyl It is practically possible to mix up to 35% or less of one or more mixtures selected from the group consisting of pyrrolidone, tetramethylurea, diethylene glycol dimethyl ether and polyethylene glycol dimethyl ether.

What makes the present invention most effective is a combination in which an alkali of 5,000 mg / kg or more, particularly preferably 7,000 mg / kg or more, coexists with the aprotic polar solvent.

Means for excessively using one of the inexpensive chemicals in order to complete the reaction is generally well known.
The presence of a large excess of alkali in the present invention, as evident from Table 1, is not merely a matter of the ratio of alkali to halogenated aromatic compound to be decomposed, but rather the action of the aprotic polar solvent. It is important in doing.

It is not possible at this stage to fully explain the essential mechanism of the chemical reaction carried out in the present invention, but by carrying out the method of the present invention, the starting halogenated aromatic compound can be obtained. Group compounds are degraded to a substantially undetectable concentration over a wide range from 100% to a few mg / kg.

[0010]

EXAMPLES The method for removing and decomposing halogenated aromatic compounds is carried out as described above. A number of modifications were studied on the basis of the method of the present invention. However, since it is not always appropriate to clarify the gist of the present invention, Table 1 shows a basic example and Table 2 shows a comparative example. In these Examples, a remarkable effect was shown, but in Comparative Examples, when the alkali concentration was low, it was shown that the decomposition effect of PCB was not remarkable.

[0011]

[Table 1]

[0012]

[Table 2]

Example 1 50 g of insulating oil containing 80 ppm of PCB, DMI 100
g, and 2 g of powdered NaOH as alkali. The system was adjusted to an alkali concentration of about 13,000 ppm, and kept at 200 ° C. for 6 hours while thoroughly stirring the whole. Next, the mixture was cooled to room temperature, and the DMI in the lower layer was removed, and the PCB in the oil layer was subjected to gas chromatography mass spectrometry (hereinafter referred to as G
C-MS). D.
(Below the detection limit of GC-MS, that is, 0.5 ppb [0.
5 μg / kg or less). On the other hand, in Comparative Example 1, the reaction was carried out under the same conditions as in Example 1, but only the added alkali concentration was 2,000 mg / kg (2,
000 ppm). In this case, let it react for 6 hours,
When the residual PCB concentration of the oil layer was analyzed by GC-MS,
It is 4,000 ppb (4,000 μg / kg), and the effect of increasing the alkali concentration is obvious.

Example 2 The same treatment as in Example 1 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 3 The same treatment as in Example 1 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 4 The same treatment as in Example 1 was carried out under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 5 The same treatment as in Example 1 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 6 The same treatment as in Example 1 was carried out under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 7 The same treatment as in Example 1 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 8 The same processing as in Example 1 is performed under the conditions shown in Table 1. However, in this case, since a small amount of insulating oil was dissolved in the DMI layer, the analysis of PCB in DMI was performed by GC-MS.
Do with. First, as an alkali, add powdery NaOH to 1
Add 3g to increase alkali concentration to 130,000mg / kg
(130,000 ppm) and reacted for 5 hours with good stirring. After this, the remaining P in the DMI
When CB was analyzed, N.V. D. (0.5ppb)
Had decreased to

Example 9 The same treatment as in Example 8 was performed under the conditions shown in Table 1. D. (Less than 0.5 ppb).

Example 10 The same treatment as in Example 8 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 11 The same treatment as in Example 8 was performed under the conditions shown in Table 1 except that no insulating oil was added.
D. (Less than 0.5 ppb).

Example 12 The same treatment as in Example 11 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 13 The same treatment as in Example 11 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

Example 14 The same treatment as in Example 11 was performed under the conditions shown in Table 1, and the remaining PCB D. (Less than 0.5 ppb).

[0027]

Industrial Applicability According to the present invention, halogenated aromatic compounds (mainly PCs) which are considered to pose a problem to environmental protection even in a small amount or to cause direct harm to the human body
B) can be substantially completely decomposed until it is considered harmless, and it has become possible to remove and decompose B) from the hydrocarbon oil containing them.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Fumio Tanimoto 15th institute of Shimogamo Morihoncho, Sakyo-ku, Kyoto, Kyoto Prefecture (72) Inventor Kiyohiko Kujuku Kiyohiko Kumogamo, Shimogamo-cho, Sakyo-ku, Kyoto, Kyoto No. 15 Inside the Research Institute for Production Science (72) Inventor Mitsuhiko Nakamura 4-8-6 Fuse Shinmachi, Kashiwa City, Chiba Prefecture (72) Inventor Tsuneo Yano 413-14 Kawadera Hanno City, Saitama Prefecture (72) Inventor Nobuhiro Suzuki Tokyo 2-4-1 Nishi-Atsujigaoka, Tokyo-Chofu City Tokyo Electric Power Co., Inc. (72) Inventor Toshiro Togan 2-4-1, Nishi-Atsujigaoka, Chofu-shi, Tokyo Tokyo Electric Power Co., Inc. (72 ) Inventor Koichi Furuhashi 1-1, Oike-cho, Kosai-cho, Koga-gun, Shiga Prefecture Inside Neos Co., Ltd. (72) Nobuyuki Nakayama 1-1, Oike-cho, Kosai-cho, Koga-gun, Shiga Prefecture Stock Association (56) References JP-A-6-25691 (JP, A) JP-A-49-126651 (JP, A) JP-A-7-8572 (JP, A) JP-A-58-500200 (JP, A) A) JP-A-8-511766 (JP, A) U.S. Pat. No. 4,910,353 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07B 35/06 A62D 3/00 ZAB

Claims (5)

(57) [Claims] 1. A method according to claim 1, wherein the halogenated aromatic compound and the alkali are mixed at 150 ° C. to 300 ° C. in an aprotic polar solvent.
Contact for 1 hour to 10 hours, and halogenated aromatic compound
Halogen treating residual concentration of substances to less than 1 ppb order
In the alkali decomposition method aromatics, a (i). Beginning proportion of alkali in the system, aprotic polar solvent
5,000 mg / kg or more to the agent , and (ii) the alkali ratio (the halogen of the halogenated aromatic compound)
The ratio of the number of moles of alkali to the number of moles), 1.0 or more
A method for alkali decomposition of a halogenated aromatic compound, characterized by the above . 2. The method according to claim 1, wherein the halogenated aromatic compound is at least one kind or a mixture of two or more kinds selected from the group consisting of polychlorinated biphenyls, polychlorinated terphenyls and polybrominated biphenyls. A method for alkali decomposition of a halogenated aromatic compound as described above. 3. The method according to claim 1, wherein the halogenated aromatic compound is a hydrocarbon oil whose main component is a non-aromatic hydrocarbon.
The alkali decomposition method of a halogenated aromatic compound according to claim 1, wherein the compound is diluted in a range of 2% / kg or less to 2mg / kg or more. 4. The halogenated fragrance according to claim 1, wherein the alkali is at least one or a mixture of two or more selected from the group consisting of caustic soda, caustic potash, calcium hydroxide, and magnesium hydroxide. For decomposing group III compounds with alkali. 5. An aprotic polar solvent comprising 1,3-dimethyl-2-imidazolidinone or tetramethylene sulfone or a mixture in any ratio thereof as a main component, and optionally dimethyl sulfoxide. ,
One or a mixture of two or more selected from the group consisting of N-methylpyrrolidone, tetramethylurea, diethylene glycol, polyethylene glycol dimethyl ether
The alkali decomposition method for halogenated aromatic compounds according to claim 1, which contains 5% or less.