JP2005270388A - Method for decomposing organic halogen compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for decomposing an organic halogen compound capable of performing from decomposion to collection of oil by decomposing a trace amount of organic halogen compound contained in oil, such as insulating oil or the like, and recovering a medium and the treated oil for reuse. <P>SOLUTION: The method for decomposing an organic halogen compound comprises the following steps: (A) a step 101 for mixing the oil containing an organic halogen compound with an alkaline material and a hydrogen donor, and contacting the obtained mixed solution with a medium to decompose the organic halogen compound; (B) a step 102 for distilling the obtained decomposed solution to recover the hydrogen donor and a decomposed product; and (C) a step 103 for distilling the residue obtained by the distillation of the decomposed solution to recover the oil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for consistently performing a decomposition treatment of trace organic halogen compounds in oil such as insulating oil from decomposition to oil recovery.

  Among various organic halogen compounds, polychlorinated biphenyl (hereinafter sometimes abbreviated as PCB) is extremely harmful to living organisms including the human body. Therefore, it was designated as a specified chemical substance in 1973, and its manufacture, importation, Use is prohibited. However, after that, tens of thousands of tons of PCBs are left untreated without determining an appropriate disposal method. PCB decomposes PCB safely technically because chlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF), which are highly toxic dioxins, are by-produced at high temperature (30 to 750 ° C) decomposition. This is difficult, and various safe and efficient decomposition methods for PCBs have been studied for many years.

  The present inventors have already proposed a method in which a hydrogen donor and an alkaline substance are added to an insulating oil containing a trace amount of an organic halogen compound such as PCB, and contacted with a catalyst to decompose at low temperature and atmospheric pressure (Patent Document). 1-3). However, since the decomposition treatment liquid after decomposition contains neutralized salt of halogen and alkali released, decomposition products of hydrogen donor, etc. in addition to oil, hydrogen donor and alkali substance, There was a problem that it was difficult to collect the treated oil. In addition, it was necessary to reduce the detoxification cost by reusing the chemicals used for detoxification.

  There are many known methods of adding alkali to PCB-containing oils for decomposition, but conventionally, water is added to the oil after decomposition, and the alkali and neutralized salt are transferred to the aqueous phase, followed by oil-water separation. The treated oil separated in this way is recovered (see Patent Document 4 etc.). Alternatively, a method has been proposed in which an alkali and a sulfoxide solvent are added to a PCB-containing oil and thermally decomposed, and then a solvent phase containing a reaction product and a contaminant-removed oil are separated by a separation device (Patent Document 5). etc).

However, the oil-water separation method has a problem that emulsion-contaminated water is generated because oil and water cannot be emulsified and separated successfully. Further, when the solvent phase and the oil are separated, since the centrifugal separation or the membrane separation is performed, there is a problem that the processing amount of the contaminated cleaning agent generated by washing these separation devices increases. Under such circumstances, there has not yet been reported a process for decomposing PCB in oil, distilling the solvent from the decomposition treatment liquid by distillation, and recovering oil from the distillation residue by vacuum distillation.
Japanese Patent Application No. 2003-376247 Japanese Patent Application No. 2004-73286 Japanese Patent Application No. 2003-378252 JP 2000-254246 A JP-T 61-500442 Publication

  The present invention has been made in view of the above-described conventional problems, and after decomposing a trace amount of organic halogen compound in oil such as insulating oil, the solvent is recovered and reused, and further processed oil is recovered. By reusing this, an object of the present invention is to provide a method for decomposing an organic halogen compound that is consistently performed from decomposition to oil recovery.

  In the present invention, the organic halogen compound in the oil is decomposed by a specific method, the solvent is separated from the decomposition treatment liquid by a specific method, and the oil is separated from the residue after the solvent separation by a specific method. Later, when these are reused, the above-mentioned problems can be effectively solved.

  That is, the present invention includes (A) a step of decomposing the organic halogen compound by mixing an oil containing an organic halogen compound with an alkali substance and a hydrogen donor, and then contacting the resulting mixed solution with a catalyst. ) Distilling the obtained decomposition treatment liquid to recover the hydrogen donor and its decomposition product, and (C) Recovering the oil by distilling the residue obtained by distilling the decomposition treatment liquid. Provided is a method for decomposing an organic halogen compound.

  In the present invention, the hydrogen donor is at least one compound selected from the group consisting of a heterocyclic compound, an amine compound, an alcohol compound, a ketone compound and an alicyclic compound, and the catalyst is a carbon crystal compound and a metal. It is preferably at least one compound selected from the group consisting of supported carbon compounds. The oil is preferably an insulating oil, and more preferably the insulating oil is filled or stored in a pole transformer, a large transformer, or an OF cable insulating oil tank.

  Further, the hydrogen donor in the step (A) is 5 to 50% (vol / vol) with respect to the oil, and the alkaline substance is 0.1 to 10% (wt / vol) with respect to the hydrogen donor. Is preferred.

  According to the method of the present invention, after decomposing an organic halogen compound in oil, the decomposition treatment liquid is recovered by distillation, and further, oil is recovered from the distillation residue. Therefore, there is a great industrial advantage in that work efficiency is high. Moreover, according to the method of the present invention, the recovered solvent and oil can be effectively reused, and the inorganic substances in the oil can be removed at a relatively low temperature, so that the decomposition treatment cost can be reduced.

  In the method for decomposing an organic halogen compound of the present invention, (A) after mixing an oil containing an organic halogen compound, an alkaline material and a hydrogen donor, the resulting mixed solution is brought into contact with a catalyst to decompose the organic halogen compound. (B) a step of distilling the obtained decomposition treatment liquid to recover the hydrogen donor and its decomposition product, and (C) a step of recovering oil by distilling the residue obtained by distilling the decomposition treatment liquid, It is characterized by adopting.

  In the present invention, first, in step (A), an oil containing an organic halogen compound is mixed with an alkaline substance and a hydrogen donor, and then the obtained mixed solution is brought into contact with a catalyst to decompose the organic halogen compound. Here, examples of the organic halogen compound include polychlorinated biphenyls (PCBs) and dioxins. Examples of the oil in which a trace amount of the organic halogen compound is mixed include, for example, an electrical insulating oil, a heat medium oil, a lubricating oil, or a mineral oil obtained by extracting an organic halogen compound contained in a solid. In the present invention, the insulating oil may be filled or stored in a container, for example, insulating oil filled or stored in a pole transformer, a large transformer, an OF cable insulating oil tank, or the like. This is because pole transformers, large transformers, OF cable insulation oil tanks, and the like are often filled or stored with contaminated oil mixed with trace amounts of organic halogen compounds.

  Examples of the alkaline substance include one kind or a mixture of two or more kinds of caustic soda, caustic potash, sodium alkoxide, potassium alkoxide, calcium hydroxide and the like. Of these alkaline substances, caustic soda and caustic potash are particularly preferable from the viewpoints of cost and handling properties.

  The hydrogen donor may be any compound that can donate a hydrogen atom to a radical generated from an organic halogen compound. Examples of the hydrogen donor include a heterocyclic compound, an amine compound, an alcohol compound, a ketone compound and an alicyclic compound, or a combination thereof. Of these compounds, alcohol compounds, ketone compounds, and alicyclic compounds are preferable from the viewpoint of safety, and further, safety, cost, availability, ease of reaction control, and recovery are excellent. More preferred is an alcohol compound. Of the alcohol compounds, secondary alcohols such as isopropyl alcohol and cyclohexanol are particularly preferred from the viewpoint of high PCB decomposition efficiency.

  In the present invention, the amount of the alkali substance and hydrogen donor used is not limited, but the alkali substance is preferably used in an amount of 0.1 to 50% (wt / vol), more preferably 0.1% with respect to the hydrogen donor. -10% (wt / vol). If it is less than 0.1%, the decomposition reaction does not proceed. On the other hand, if it exceeds 50%, the alkali cannot be completely dissolved. The alkaline substance is preferably used in an amount of 0.02 to 10% (wt / vol) with respect to the oil. The hydrogen donor is preferably used in an amount of 5 to 50% (vol / vol) based on the oil. If it is less than 5%, the viscosity of the oil increases and the decomposition rate decreases. On the other hand, the reaction proceeds sufficiently even when it exceeds 50%. However, as described above, when a small amount of PCB in the insulating oil filled in the pole transformer or the like is decomposed, hydrogen in the gap of the pole transformer or the like The upper limit is preferably about 50% with respect to the oil because the donor may not be able to enter.

  The alkaline substance and the hydrogen donor may be added separately to the oil, or the alkali substance previously dissolved in the hydrogen donor may be added to the oil. Alternatively, oil and an alkali substance previously dissolved in a hydrogen donor may be separately introduced into the cracking reactor.

  In the present invention, any catalyst can be used without limitation as long as it can accelerate the dehalogenation reaction of the organic halogen compound. The type of the catalyst is not limited, but the inorganic catalyst has a long catalyst life and is alkaline. It is preferable because it is stable even in the presence of a substance. Of the inorganic catalysts, preferred specific examples include composite metal oxides, carbon crystal compounds, metal-supported carbon compounds, metal oxides, and the like alone or in combination. Among these catalysts, a carbon crystal compound and a metal-supported carbon compound are preferable, and a metal-supported carbon compound is particularly preferable because of its high stability in an alkaline atmosphere. Specific examples of the metal-supported carbon compound include Pd / C (palladium-supported carbon compound), Ru / C (ruthenium-supported carbon compound), and Pt / C (platinum-supported carbon compound).

  In the present invention, the amount of the catalyst used is not limited, but is preferably 0.000001 to 0.5 parts by mass, more preferably 0.0001 to 0.1 parts by mass, particularly 100 parts by mass of the reaction solution. Preferably it is 0.001-0.02 mass part. The catalyst may be added in advance to the oil or hydrogen donor, may be used by adding or fixing to the cracking reactor, or may be used as a catalyst column prepared by packing the catalyst in the column. Good.

  The decomposition temperature in the step (A) is preferably −15 to 200 ° C., more preferably −15 to 80 ° C., and still more preferably 10 to 80 ° C. Although reaction time is not limited, it is good to set it as 2 hours-300 hours, More preferably, it is 12 hours-300 hours.

  In the present invention, it is preferable to mix the oil, the alkaline substance, and the hydrogen donor, and then supply the mixed solution to a reactor equipped with a catalyst for decomposition treatment. For example, an alkali substance and a hydrogen donor are added to and mixed with oil contained in a container, and the mixed liquid is passed through a catalyst tank (reactor) filled with the catalyst and brought into contact with the catalyst. Decompose by circulating. In this case, the distribution speed can be arbitrary. The decomposition treatment by such an operation is preferable in that it is not necessary to transport the oil to the PCB treatment facility and the decomposition treatment can be performed at a storage place of the transformer.

  FIG. 1 is a process flow diagram showing a batch type method for decomposing PCBs in insulating oil according to the present invention, and FIG. 2 is a process flow diagram showing a method for decomposing PCBs in insulating oil according to the present invention. 1 and 2 show a preferred embodiment of the present invention, and the present invention is not limited to these examples.

  In the decomposition treatment liquid after the decomposition treatment in step (A) 101, in addition to oil, hydrogen donor (alcohol), and alkaline substance, hydrogen donor decomposition product, neutralization of halogen and alkali released from PCB Contains salt.

  In the present invention, in step (B) 102, after removing dust through a strainer or the like as necessary in the decomposition treatment liquid, alcohol and alcohol decomposition products (solvents in the figure) are recovered by distillation.

  FIG. 3 is a process flow diagram showing a preferred example using KOH as the alkaline substance and isopropyl alcohol (IPA) as the hydrogen donor. Here, when IPA is used, acetone is generated by decomposition of IPA.

  In step (B) 102 of the present invention, it is preferable to recover the hydrogen donor (IPA) and its decomposition product (acetone) by distillation such as atmospheric distillation or vacuum distillation or / and rectification using a rectifying column. . The decomposition product (acetone) and hydrogen donor (IPA) are preferably separated and recovered. In the present invention, the acetone thus recovered can be used again as a cleaning solvent for the decomposition step of the present invention. IPA can also be used again as a hydrogen donor in the cracking process of the present invention. On the other hand, the distillation residue in the step (B) can be introduced into the next step (C) as it is.

  In the present invention, in step (C) 103, the first-stage distillation residue is preferably recovered by distillation such as vacuum distillation. When the atmospheric oil is distilled, there is a problem that the insulating oil is burnt and polymerized when the insulating oil is recovered by distillation, and the required energy increases because the distillation temperature of the insulating oil is as high as about 300 to 400 ° C. This is because a problem arises. The insulating oil recovered by vacuum distillation can be reused as fuel or the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to a following example.

Example 1
(Disassembly test)
200 parts by volume of Type 1 No. 2 insulating oil containing 10 ppm of PCB, 40 parts by volume of isopropyl alcohol as a hydrogen donor (20% by volume of insulating oil), and 0.34 parts by weight of KOH as an alkali (0.17 w / v of insulating oil) %) Was added and stirred to obtain an oil to be treated.

  On the other hand, the catalyst column was packed with 10.04 g of a catalyst in which 4.8% palladium (Pd) was supported on granular activated carbon. The oil to be treated was passed through the catalyst column at a rate of 10 ml / min using a diaphragm metering pump (STDOSDOS FEM08 manufactured by KNF Neuberger GmbH) and sampled periodically. The PCB concentration in the sampled solution was analyzed using a gas chromatography mass spectrometer QP5050 (hereinafter, “GC-MS”) manufactured by Shimadzu Corporation using DB1 (manufactured by J & W Scientific) as a capillary column. As a result of passing through for 8 days, the PCB concentration in the solution was 0.23 ppm.

(First stage: Solvent distillation at low temperature)
The solution after passing through was collected, and acetone for cleaning the instrument was added thereto to make a decomposition waste liquid. 485 kg of this decomposition waste liquid was poured into a rotary evaporator (model: REN-1000) made of iwaki glass, set in a water bath made of iwaki glass (model: THB-1000) whose hot water temperature was controlled at 50 ° C., and an aspirator made by ULVAC Kiko. Distillation was performed while reducing the pressure to 0.01 MPa (model: MDA-015 type). At this time, the coolant used was a solution of ethylene glycol diluted with water and circulated at −10 ° C. As a result, the distillate was 341 kg, the bottom concentrated waste liquid amount was 144 kg, and the decomposition waste liquid contained 70.3% acetone.

(First stage: Evaporation of solvent at high temperature)
Separately, 20 ml of isopropyl alcohol was added to 100 ml of Type 1 No. 2 insulating oil to prepare a simulated test oil, which was injected into a rotary evaporator (model: REN-1000) made of Iwaki Glass, and the hot water temperature was controlled at 80 ° C. It was set in a water bath made of iwaki glass (model: THB-1000), and distilled for 15 minutes while reducing pressure to 0.01 MPa with an aspirator (model: MDA-015 model) manufactured by ULVAC KIKOH. At this time, the coolant used was a solution of ethylene glycol diluted with water, and was circulated at −10 ° C. As a result, the distillate was 20 ml and the concentrated waste liquid amount was 100 ml, and the test oil could be separated into the solvent and the insulating oil.

(Second stage: Distillation of insulating oil)
Separately, 0.4 g of KOH as an alkali and 0.04 g of KCl as a salt were added to 200 ml of Type 1 No. 2 insulating oil not containing PCB, and heated and dissolved to prepare a simulated test oil. A distillation curve was obtained from this by a reduced pressure distillation test method defined in JIS K-2254. A graph showing the relationship between the loss capacity and the top temperature when the degree of vacuum is 50 torr is shown in FIG. The initial boiling point is top 161.5 ° C. (atmospheric pressure conversion: 255 ° C.), bottom 196.5 ° C. (atmospheric pressure conversion: 294.5 ° C.), and the temperature at the 95% distillation is top 256.5 ° C. ( Atmospheric pressure conversion: 360 ° C.) and bottom 270.0 ° C. (atmospheric pressure conversion: 375.0 ° C.), and the residue was not solidified and was oily.

  It was confirmed that by distilling under reduced pressure, the temperature could be kept lower than under atmospheric pressure, and oil scorching and polymerization could be suppressed.

Example 2
To 200 ml of No. 7 Type 4 insulating oil not containing PCB, 0.4 g of KOH as an alkali and 0.04 g of KCl as a salt were added and dissolved by heating separately as a simulated test oil. The distillation curve when the degree of vacuum was 50 torr was obtained by the reduced pressure distillation test method specified in JIS K-2254. A graph showing the relationship between the loss capacity and the top temperature is shown in FIG. The initial boiling point is top 179.5 ° C. (atmospheric pressure conversion: 274.0 ° C.), bottom 218.5 ° C. (atmospheric pressure conversion: 317.5 ° C.), and the temperature at the 95% distillation is top 272.5 C. (atmospheric pressure conversion: 378.5.degree. C.) and bottom 287.0.degree. C. (atmospheric pressure conversion: 394.5.degree. C.), and the residue was not solidified and was oily.

  It was confirmed that by distilling under reduced pressure, the temperature could be kept lower than under atmospheric pressure, and oil scorching and polymerization could be suppressed.

It is a process flow figure of PCB decomposition method in batch type insulating oil by the present invention. It is a process flow figure of the PCB decomposition | disassembly method in continuous insulation oil by this invention. It is a process flow figure showing one embodiment of a PCB decomposition method in insulating oil by the present invention. It is a graph which shows the distillation characteristic of the 1 type 2 insulating oil in a process (C). It is a graph which shows the distillation characteristic of the 7 type 4 insulation oil in a process (C).

Explanation of symbols

101: Process (A)
102: Process (B)
103: Process (C)

Claims (6)

(A) Step of decomposing the organic halogen compound by bringing the mixed solution obtained into contact with a catalyst after mixing the oil containing the organic halogen compound, an alkali substance and a hydrogen donor, and (B) the resulting decomposition treatment An organic halogen compound characterized by adopting a step of recovering a hydrogen donor and its decomposition product by distilling the liquid, and a step of recovering oil by distilling a residue obtained by distilling the decomposition treatment liquid Decomposition method. The method according to claim 1, wherein the hydrogen donor is at least one compound selected from the group consisting of a heterocyclic compound, an amine compound, an alcohol compound, a ketone compound, and an alicyclic compound. The method according to claim 1, wherein the catalyst is at least one compound selected from the group consisting of a carbon crystal compound and a metal-supported carbon compound. The method of claim 1, wherein the oil is an insulating oil. The method according to claim 4, wherein the insulating oil is filled or stored in a pole transformer, a large transformer, or an OF cable insulating oil tank. The hydrogen donor in the step (A) is 5 to 50% (vol / vol) with respect to the oil, and the alkaline substance is 0.1 to 10% (wt / vol) with respect to the hydrogen donor. The method according to claim 1.

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