JP3410797B2 - Decomposition method of halogenated organic compounds - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing a halogenated organic compound, and more particularly to a method for decomposing a halogenated organic compound by eliminating halogen in the halogenated organic compound with an alkali to render it harmless.

[0002]

2. Description of the Related Art Halogenated organic compounds such as PCB (polychlorinated biphenyl), dioxins, and halogenated pesticides have become a serious problem as environmental pollutants. Especially P
Since CB has excellent insulating properties and is flame-retardant, it has been widely produced and widely used mainly as an electrical insulating oil, but PCBs released into the environment are accumulated in the human body and cause strong liver damage. Proved to be toxic and prohibited from production and new use. PCB is difficult to dispose because it is difficult to decompose, and various disposal methods have been studied. For example, various treatment methods such as a high temperature combustion method, a microbial decomposition method, and a chemical decomposition method have been proposed. Among them, the chemical decomposition treatment method is characterized in that it can be decomposed at low temperature in a short time.

As a chemical decomposition treatment method, in International Patent Application No. PCT / US91 / 01112, a thermal decomposition product of a carbohydrate is used as a catalyst and a high boiling point hydrocarbon is used as a hydrogen donor to reductively decompose PCB and the like. A method is disclosed. In this patent, the carbon catalyst is a pyrolysis product of carbohydrate (sucrose), but this does not necessarily mean carbon. That is, it includes a process of thermally decomposing a carbohydrate to generate a carbon-based catalyst. However, this process is difficult to carry out on an industrial scale with explosive and violent phenomena. Further, the carbon-based catalyst produced becomes tar-like and is difficult to disperse in the solvent, and the efficiency as a catalyst is poor.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, is excellent in safety and can be efficiently decomposed,
Moreover, it is an object of the present invention to provide a method for chemically decomposing a halogenated organic compound, which can easily dispose of a decomposed product.

[0005]

In order to solve the above problems SUMMARY OF THE INVENTION In the present invention, the halogenated organic compound is heated in the presence of a high boiling oil and alkaline substances, reductively dehalogenated The method for decomposing a halogenated organic compound is characterized by using a detoxified organic compound . In the present invention, as the halogenated organic compound,
Polychlorinated biphenyls (PCB), dibenzodioxins, dibenzofurans, and the like, which are hardly decomposable, can be mentioned, and they can be suitably applied to the decomposition of these halogenated organic compounds.

As described above, in the present invention, powdery carbon which is easily dispersed in a solvent is used as a catalyst,
It is intended to detoxify a harmful halogenated organic compound by reductively dehalogenating it. That is, it is a method of detoxifying a harmful halogenated organic compound by using a high boiling point oil as a solvent and a hydrogen donor and performing a reduction reaction using powdery carbon as a catalyst.

The high boiling point oil is selected from mineral oils, aliphatic hydrocarbons, aromatic hydrocarbons and the like, and has a boiling point of 200 to 50.
It is 0 ° C., and preferably has a boiling point of 300 to 400 ° C. as a main component. In such high boiling point oil, P
A medium containing CB or PCB is mixed and used.
The medium containing PCB means transformer oil or condenser oil. At this time, in order to avoid a sudden reaction, P
The CB concentration is preferably 10% or less.

The carbon includes amorphous carbon powder, carbon black, graphite and activated carbon, and preferably has a particle size of 25 μm or less. The amount of carbon used is 0.1 to 10% (W / V), preferably 1 to 2% (W / V) with respect to the high boiling point oil. For example, when residual carbon content is contained as in C heavy oil, it is not always necessary to add carbon.

The alkaline substance includes hydroxides, oxides, carbonates and bicarbonates of alkali metals and alkaline earth metals, preferably sodium hydroxide and potassium hydroxide. The alkaline substance can be used as a solid or an aqueous solution. The amount of alkaline substance added is
1 for chlorine of halogenated organic compounds such as PCB
It is 10 to 10 equivalents, preferably 3 to 5 equivalents. The reaction temperature is 270 to 400 ° C., preferably 300 to 350.
℃. It is sufficient to react at this temperature for 2-3 hours. The reaction is preferably carried out in an inert gas atmosphere in order to create a reducing atmosphere and prevent ignition. Nitrogen, argon and the like can be used as the inert gas.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Example 1 PCB (3 ml) was dissolved in high boiling mineral oil (150 ml), sodium hydroxide (10 g) and amorphous carbon powder (1.5 g) were added, and the mixture was heated with stirring at 330 to 340 ° C. for 2 hours under a nitrogen atmosphere. did. When the reaction solution was analyzed by GC / MS, PCB was decomposed and only biphenyl was detected.

Example 2 PCB (3 ml) was dissolved in high boiling mineral oil (150 ml), sodium hydroxide (10 g) and carbon black (1.5 g) were added, and the mixture was heated at 330 to 340 ° C. for 2 hours under a nitrogen atmosphere. It was stirred. When the reaction solution was analyzed by GC / MS, PCB was decomposed and only biphenyl was detected.

Example 3 PCB (3 ml) was dissolved in high boiling mineral oil (150 ml), sodium hydroxide (10 g) and graphite (1.5 g) were added, and the mixture was heated with stirring at 330 to 340 ° C. for 3 hours under a nitrogen atmosphere. did. When the reaction solution was analyzed by GC / MS, PCB was decomposed and only biphenyl was detected.

Example 4 PCB (3 ml) was dissolved in high boiling mineral oil (150 ml), sodium hydroxide (10 g) and activated carbon (1.5 ml).
g) was added, and the mixture was heated with stirring at 330 to 340 ° C. for 3 hours under a nitrogen atmosphere. When the reaction solution was analyzed by GC / MS, PCB was decomposed and only biphenyl was detected.

Example 5 Trans oil (60 ml) containing 0.5% of PCB was mixed with high boiling mineral oil (90 ml) to obtain amorphous carbon powder (1.5 ml).
g) and sodium hydroxide (3.5 g) were added, and the mixture was heated with stirring at 330 to 340 ° C. for 2 hours under a nitrogen atmosphere. GC / M
When the reaction solution was analyzed by S, PCB was decomposed and only biphenyl was detected.

Example 6 Chlorodibenzodioxins (10 mg) were dissolved in high boiling mineral oil (150 ml), and sodium hydroxide (1.
0 g) and activated carbon (1.5 g) were added and under nitrogen atmosphere 3
The mixture was heated and stirred at 30 to 340 ° C. for 3 hours. When the reaction solution was analyzed by GC / MS, the raw material was completely decomposed,
Not detected.

Example 7 Chlorodibenzofurans (10 mg) were dissolved in high boiling mineral oil (150 ml), and sodium hydroxide (1.0 mg) was added.
g) and activated carbon (1.5 g) were added and under a nitrogen atmosphere 33
The mixture was heated and stirred at 0 to 340 ° C for 3 hours. When the reaction solution was analyzed by GC / MS, the raw material was completely decomposed and was not detected.

[0017]

EFFECTS OF THE INVENTION Conventionally, a heavy metal compound is often used as a catalyst for the reduction / dehalogenation reaction, but since carbon is used in this reaction, the high boiling point oil used after the decomposition treatment and the detoxified oil are detoxified. The combustion treatment can be easily performed without generating harmful substances together with the organic compound. Further, in the present invention, since the carbon as the catalyst is used in a dispersed state in the high boiling point oil, the contact efficiency is good,
Moreover, the decomposition reaction proceeds safely.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Taniguchi 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION (56) References JP-A-1-131676 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A62D 3/00 C07B 37/06 B09B 3/00

Claims (5)

(57) [Claims] The method according to claim 1 halogenated organic compounds, then heated in the presence of carbon and the alkaline material in a high boiling oil, reductive
A method for decomposing a halogenated organic compound, which comprises dehalogenating the organic compound into a harmless organic compound. Wherein said halogenated organic compound is polychlorinated biphenyls (PCB), dibenzo dioxins, that consist of one or more selected from dibenzofurans JP
The method for decomposing a halogenated organic compound according to claim 1, which is a characteristic of the method. 3. The high boiling point oil has a boiling point of 200 to 500.
℃ mineral oil, selected from an aliphatic hydrocarbon or an aromatic hydrocarbon
Decomposition method according to claim 1 or 2 halogenated organic compounds according you, characterized in that. 4. The alkaline substance comprises at least one selected from hydroxides, oxides, carbonates, and bicarbonates of alkali metals or alkaline earth metals, and is suitable for chlorine in the halogenated organic compound. Patent the use 1 to 10 equivalents Te
The method for decomposing a halogenated organic compound according to claim 1, 2 or 3, which is a characteristic of the method. 5. The carbon is selected from amorphous carbon, carbon black, graphite or activated carbon, and is used in an amount of 0.1 to 10% (W / V) with respect to the high boiling point oil.
The method for decomposing a halogenated organic compound according to any one of claims 1 to 4, which is characterized in that .