JP3678739B1 - Dechlorination method for high concentration PCB - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be practically possible, capable of dechlorinating highly concentrated PCBs, which are difficult to dechlorinate, safely and in large quantities, at a lower cost, and less likely to produce side reaction products. A dechlorination method is provided.
SOLUTION: A mixed solution of high-concentration polychlorinated biphenyl (PCB) and a solution obtained by dissolving an alkali compound in a hydrogen donor is stirred at room temperature (in the presence of a catalyst in which a metal is supported on a carrier). It is dechlorinated by allowing it to stand and react at −15 to 60 ° C., thereby detoxifying the PCB.
[Selection figure] None

Description

  The present invention relates to a method for dechlorinating polychlorinated biphenyl (hereinafter sometimes abbreviated as PCB) to render it harmless.

  Among various halogenated organic compounds, PCB is extremely harmful to living organisms including the human body. Therefore, it was designated as a specific chemical substance in 1973, and its manufacture, import and use are 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.

  For example, in Patent Document 1, harmful organic chlorine compounds are dechlorinated by irradiating microwaves while blowing hydrogen gas into a mixed system containing activated carbon supporting platinum and an aromatic chlorine compound (parachlorophenol). A method has been proposed.

  Patent Document 2 discloses a hydrocarbon oil containing a small amount of a halogenated aromatic compound (recovered trans oil containing PCB) in the presence of an alkaline substance such as sodium ethoxide or NaOH and having a high boiling point and a heat-resistant alkaline polar solvent ( Method of removing PCB from hydrocarbon oil by separating hydrocarbon oil and solvent after contacting with 1,3-dimethyl-2-imidazolidinone (DMI), sulfolane) at 100 to 300 ° C. Has been proposed. This describes that the PCB can be removed from the PCB-containing hydrocarbon oil until the PCB is substantially harmless.

  On the other hand, Patent Document 3 proposes a method in which an aromatic halogen compound is decomposed by heating to 30 to 100 ° C. in the presence of a decomposition catalyst and an alkali compound in a second alcohol. Specifically, a predetermined amount of alkali and catalyst are added to 2-propanol in which PCB is dissolved to form a suspension, and then heated to the vicinity of the boiling point (83 ° C.) of 2-propanol and refluxed for 2 hours. Alternatively, it is described that by performing a decomposition reaction for 3 hours, PCB can be decomposed to a level where it is not detected.

  Furthermore, in Patent Document 4, a base metal catalyst such as a zeolite / nickel catalyst is added to an electrical insulating oil containing an organic chlorine compound, and dechlorination is performed by hydrogenation in a hydrogen gas atmosphere under heating temperature conditions. A method has been proposed.

  In Patent Document 5, an alkali-resistant polar solvent (1,3-dimethyl-2-imidazolidinone, sulfolane) containing 15% by weight or less of PCB is contacted with an alkaline substance at 100 to 300 ° C., and then precipitated. There has been proposed a method for decomposing PCBs by removing substances from polar solvents. Thus, it is described that the PCB can be decomposed and removed until it is substantially harmless.

  Patent Document 6 and Patent Document 7 exceeded the amount dissolved in PCB diluted with PCB or hydrocarbon oil and heat-resistant and alkali-resistant solvent (1,3-dimethyl-2-imidazolidinone, sulfolane). There has been proposed a method for decomposing PCB by contacting a quantitative ratio of an alkaline substance at 150 to 300 ° C. (150 to 250 ° C. in the presence of a reaction promoting substance such as quinoline). Thus, it is described that PCB can be removed and decomposed from PCB-containing hydrocarbon oil until PCB is substantially harmless.

In Patent Document 8, a PCB-containing insulating oil and excess alkali are stirred at 100 to 300 ° C. in an aprotic polar solvent (1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, etc.) In the method of dechlorination reaction by mixing, after the reaction, excess unreacted alkali from the reaction product is dissolved in lower alcohol, separated and recovered, and reused in the reaction, making PCB economically harmless A method has been proposed.
JP 2001-19646 A (Claim 1 etc.) JP-A-6-25691 (Claim 1, paragraph number 0004, Table 1 on page 3, paragraph number 0019, etc.) JP-A-8-266888 (claim 1, paragraph number 0008, embodiment 2 of 0012, embodiment 3 of 0013, page 3, column 4, lines 46-50) JP-A-4-202500 (Patent No. 1982066) (Claim 1 etc.) Japanese Patent Laid-Open No. 7-8572 (Claim 1, paragraph number 0006, Table 1 on page 3, paragraph number 0027, etc.) JP-A-7-289656 (Claim 1, paragraph numbers 0004 and 0006, page 3, table 1, paragraph number 0027, etc.). JP-A-7-313620 (paragraph numbers 0004 and 0006, Table 1 on page 4, paragraph number 0028, etc.) JP-A-9-253602 (Claim 1, paragraph numbers 0008 and 0012, paragraph number 0037, etc.)

  However, in the method described in Patent Document 1, it is necessary to supply hydrogen gas from the outside to a reaction system containing an aromatic chlorine compound, which is not preferable as a practical technique.

  Further, in the method described in Patent Document 4, hydrogen addition is essential, and an explosion-proof device for handling hydrogen is required, which is not practical. Moreover, since it is reaction at high temperature (150-250 degreeC), possibility that a side reaction product will produce | generate is high.

  In the methods described in Patent Document 2 and Patent Documents 5 to 8, on the assumption that it is necessary to decompose PCB at least at 100 ° C. or higher in an alkali in order to decompose PCB, A solvent that can withstand temperatures of 150 ° C. or higher is selected, and PCB is decomposed at 160 ° C. to 210 ° C. in this heat and alkali resistant solvent. The solvent DMI (1, 3) used in these methods is used. -Dimethyl-2-imidazolidinone) is expensive at 2000 yen / kg, and the method has a large ratio of residual PCB, and it is necessary to lengthen the reaction time for sufficient dechlorination. It is not suitable for mass processing.

  On the other hand, in the method described in Patent Document 3, it is necessary to heat a solution obtained by dissolving PCB in 2-propanol to reflux conditions (78 ° C.), and there is a concern that a by-product is generated. Furthermore, no mention is made of the effect of the alkali and hydrogen donor mixture by pre-stirring.

  Currently, assessment is required for the construction of PCB processing facilities and PCB transportation, so PCBs can be detoxified at sites such as transformer storage without using special equipment. It is desired to develop a method that can be safely processed in large quantities and can be decomposed at low cost.

  Therefore, the present invention has been made in view of the above-described conventional problems, and high-concentration PCBs that are difficult to dechlorinate can be safely dechlorinated and detoxified in a large amount at a lower cost. It is an object of the present invention to provide a practically usable dechlorination method with a low possibility of generating a side reaction product.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have added a mixed solution of an organic hydrogen donor and an alkali compound to a high concentration PCB, and further added a specific catalyst and stirred to thereby generate hydrogen from the outside. And it discovered that dechlorination of PCB became possible in 2 to 3 weeks, without supplying heat, and came to complete this invention.

That is, the present invention is a catalyst in which polychlorinated biphenyl (PCB) having a concentration of 100% is mixed with a mixed solution in which an alkali compound is previously dissolved in a hydrogen donor , and the mixed solution is supported on palladium on a carrier. In the presence of a catalyst, the catalyst ratio (ratio of the mass of the supported metal to the mass of polychlorinated biphenyl) is 0.035 or more , and dechlorination is performed by reacting at room temperature ( non-heated ) with stirring. A method for dechlorination of biphenyl chloride is provided.

In dechlorination method polychlorinated biphenyls of the present invention, as the catalyst, the palladium is needed use those obtained by supporting on a carrier. Moreover, (the ratio of the mass of the supported metal to the mass of polychlorinated biphenyls) the catalyst ratio, Ru der 0.035 or more. By performing under such conditions, the dechlorination efficiency of PCB at room temperature can be increased.

  In the method of the present invention, the polychlorinated biphenyl concentration is preferably 500 to 100,000 ppm (in the total amount of the mixed solution), and the concentration is particularly preferably 1,000 to 10,000 ppm. The amount of hydrogen donor added is particularly preferably 100 to 1000 times (volume) the amount of PCB.

  According to the present invention, PCB can be dechlorinated without supplying hydrogen and heat from the outside. Therefore, a large amount of PCB can be safely dechlorinated and detoxified at low cost. Furthermore, the amount of drug to be added is preferably 100 to 1000 times the amount (capacity) of the PCB, but even in such a case, there is no need to increase the processing temperature (no heating is required), and the repository that stores the transformer It is also possible to process on-site.

  In the polychlorinated biphenyl dechlorination method, the hydrogen donor is preferably at least one compound selected from the group consisting of amine compounds, alcohol compounds, ketone compounds and alicyclic compounds. More preferably, it is at least one compound selected from alcohol compounds. Among the hydrogen donors, the use of one or a mixture of two or more of these organic hydrogen donors can increase the dechlorination efficiency of PCB.

  In the polychlorinated biphenyl dechlorination method, the alkali compound is preferably at least one compound selected from the group consisting of caustic soda, caustic potash, sodium alkoxide, potassium alkoxide, and calcium hydroxide. By using one or two or more of these compounds among the alkali compounds, the dechlorination efficiency of PCB can be increased.

  In the polychlorinated biphenyl dechlorination method of the present invention, it is preferable that the hydrogen donor and the alkali compound are completely dissolved in the hydrogen donor by pre-stirring to form a mixed solution. It is no exaggeration to say that this pre-stirring enables decomposition at room temperature and suppresses the formation of by-products.

  The polychlorinated biphenyl dechlorination method of the present invention is preferably applied to the dechlorination of polychlorinated biphenyl extracted from a transformer.

  As described above, according to the present invention, high-concentration PCB can be easily decomposed at room temperature and normal pressure, so that dechlorination can be carried out as it is at a site such as a transformer store. . Therefore, since it becomes possible to detoxify a large amount of high-concentration PCB on a practical scale, its practical value is great.

The method for dechlorinating a high concentration PCB of the present invention comprises adding a mixed solution of a hydrogen donor and an alkali compound to a high concentration PCB to form a mixed solution, or adding and mixing a high concentration PCB to a mixed solution of a hydrogen donor and an alkali compound. The solution is characterized in that it is dechlorinated by stirring it in the presence of a catalyst having palladium supported on a carrier, and allowing it to react at room temperature. Details of the present invention will be described below.

  The polychlorinated biphenyl targeted in the present invention includes a compound in which a chlorine atom is substituted in a biphenyl compound, and the number of substituted chlorine atoms is 1 to 10. The average number of substituted chlorine atoms is generally 2-6. In the present invention, at least one selected from these polychlorinated biphenyls can be used, and those individually or in any combination of two or more can also be used.

  In general, polychlorinated biphenyls do not exist as a single compound but exist as a mixture having different numbers of chlorine atoms and different substitution positions. Therefore, there are 209 isomers based on the combination of the number of chlorine atoms and the substitution position, and more than 100 isomers exist in the commercial product.

  For example, as a coplanar PCB, 3,4,4 ′, 5-tetrachlorobiphenyl, 3,3 ′, 4,4′-tetrachlorobiphenyl, 3,3 ′, 4,4 ′, 5-pentachlorobiphenyl, 3,3 ′, 4,4 ′, 5,5′-hexachlorobiphenyl, 2,3,3 ′, 4,4′-pentachlorobiphenyl, 2,3,4,4 ′, 5-pentachlorobiphenyl, 2 3 ′, 4,4 ′, 5-pentachlorobiphenyl, 2 ′, 3,4,4 ′, 5-pentachlorobiphenyl, 2,3,3 ′, 4,4 ′, 5-hexachlorobiphenyl, 2, 3,3 ′, 4,4 ′, 5′-hexachlorobiphenyl, 2,3 ′, 4,4 ′, 5,5′-hexachlorobiphenyl, 2,3,3 ′, 4,4 ′, 5,5 ′ -Heptachlorobiphenyl and the like

  PCBs are usually marketed as a mixture of PCBs alone, and these are used for capacitors and transformers. Specific examples include KC-200 (biphenyl dichloride), KC-300 (biphenyl trichloride), KC-400 (biphenyl tetrachloride), KC-500 (biphenyl pentachloride), KC of Kaneka Chemical Co., Ltd. -600 (biphenyl hexachloride), KC-1000 (mixture of KC500 / trichlorobenzene = 60/40 (mass ratio)), Arochlor 1254 (54% Chlorine) manufactured by Mitsubishi Monsite Corporation, and the like.

As an example, the distribution (% by weight) of isomers of the commercial product KC-300 is shown below.
Monochrome biphenyl slightly dichlorobiphenyl 12.10%
Trichlorobiphenyl 54.98%
Tetrachlorobiphenyl 27.05%
Pentachlorobiphenyl 4.72%
Hexachlorobiphenyl 1.08%
Heptachlorobiphenyl slightly Octachlorobiphenyl 0
Nonachlorobiphenyl 0
Decachlorobiphenyl 0

  In the present invention, the “hydrogen donor” means a compound that can donate a hydrogen atom to a radical generated from polychlorinated biphenyl, for example, an amine compound, an alcohol compound, a ketone compound, And organic hydrogen donors such as alicyclic compounds. These compounds are excellent in PCB dechlorination efficiency. Among these, alcohol compounds, ketone compounds, and alicyclic compounds are preferable from the viewpoint of safety. In particular, they are highly safe, can be obtained at low cost, can be easily controlled, and have high PCB decomposition efficiency. From the viewpoint, alcohol compounds are preferred. A hydrogen donor can be used individually or in combination of 2 or more types.

  Examples of the amine compound include dimethylethylenediamine.

  The alcohol compound may be either an aliphatic alcohol or an aromatic alcohol, and examples thereof include a monohydric alcohol or a polyhydric alcohol having a linear or branched chain. The carbon number of the alcohol compound is preferably in the range of 1 to 12, more preferably in the range of 2 to 9, and still more preferably in the range of 3 to 6. Specific examples of the alcohol compound include, for example, methanol, ethanol, 1-propanol, 2-propanol, n-butanol, s-butanol, t-butanol, 1-pentanol, 2-pentanol, and 3-pentanol. 1-hexanol, 2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol and other aliphatic alcohols, cyclopropyl alcohol, cyclobutyl alcohol, cyclopentyl alcohol, cyclohexyl Examples thereof include alicyclic alcohols such as alcohol, cycloheptyl alcohol and cyclooctyl alcohol, and polyhydric alcohols such as ethylene glycol, propylene glycol and decalin diol. Among these, 2-propanol and cyclohexanol are particularly preferable from the viewpoint of decomposition efficiency.

  Examples of the ketone compound include methyl ethyl ketone, cyclohexanone, tricyclododecanone, and the like.

  Examples of the alicyclic compound include tetralin and cyclohexane.

  The alkali compound used in the present invention can be used without limitation as long as it can accelerate the dechlorination reaction of polychlorinated biphenyl, but from the viewpoint of increasing the dechlorination efficiency, caustic soda, caustic potash, sodium alkoxide, Potassium alkoxide, calcium hydroxide and the like are preferably used. Among these, caustic soda or caustic potash is more preferable from the viewpoint of cost and handling properties. An alkali compound can be used individually or in combination of 2 or more types.

  The catalyst in which a metal is supported on the carrier used in the present invention can be used without limitation as long as it can accelerate the dechlorination reaction of polychlorinated biphenyl, and the type thereof is not particularly limited. Since this catalyst has a long catalyst life and is stable even in the presence of an alkali compound, it is preferably used. Examples of the carrier include carbons such as activated carbon and graphite, metal oxides such as silica gel and alumina, composite metal oxides such as zeolite, and resins such as polyethylene. Among these carriers, dechlorination efficiency A metal-supported carbon compound in which a metal is supported on a carbon support is preferable from the viewpoint of high safety and high safety in an alkaline atmosphere. These catalysts can be used individually or in combination of 2 or more types.

The metal-supported carbon compound can be used without limitation as long as it is a carbon compound supporting a metal, and the amount of the metal supported is 1 to 20 wt%, more preferably 5 to 10 wt% with respect to the total amount of the catalyst. There should be. The metal supported, from the viewpoint of enhancing the dechlorination efficiency, palladium is used. Specific examples of the metal-supported carbon compound include Pd / C (palladium-supported carbon compound ) . The particle size of the metal-supported carbon compound is preferably 75 to 300 μm. When the particle size exceeds 300 μm, the reactivity deteriorates, and when it is less than 75 μm, the handling property deteriorates. More preferably, 125 to 250 μm is desirable.

  In the dechlorination method of the present invention, it is important to pre-stir the hydrogen donor and the alkali compound in advance to dissolve the alkali compound in the hydrogen donor. The pre-stirring method is not particularly limited. For example, it is possible to completely dissolve the alkali compound in the hydrogen donor by mixing the hydrogen donor and the alkali compound and stirring the mixture for about 20 minutes with a 3000 rpm homomixer.

  In the method of the present invention, the hydrogen donor is preferably used in an amount of 1 to 10,000 (volume ratio) with respect to polychlorinated biphenyl. When the volume ratio of the hydrogen donor is less than 1, the viscosity of the solution increases and the decomposition reaction does not proceed. On the other hand, when the volume ratio of the hydrogen donor exceeds 10,000, the reaction proceeds sufficiently, but there is no practical meaning. The volume ratio is preferably 50 to 5000, and particularly preferably 100 to 1000.

  The amount of the alkali compound in the hydrogen donor / alkali compound mixture is preferably 0.1 to 50% as a ratio (% by mass) to the total amount of the alkali solution. When the mass ratio is less than 0.1%, the decomposition reaction does not proceed, and when it exceeds 50%, the alkali cannot be completely dissolved. The mass ratio is more preferably 1 to 10%, and particularly preferably 2 to 5%.

The amount of the catalyst shall be the amount of catalyst ratio (ratio of the mass of the supported metal to the mass of polychlorinated biphenyls) is 0.035 or more. When the catalyst ratio is less than 0.035, the amount of hydrogen generation is reduced, and therefore dechlorination at room temperature is difficult to proceed. In consideration of economy, the catalyst ratio is more preferably 0.035 to 0.20, and still more preferably 0.05 to 0.10.

  In the dechlorination method of the present invention, in the case of stirring, there are three methods of stirring from the outside by shaking, stirring from the inside by a stirrer, and microscopic stirring by ultrasonic waves, whichever method is used. May be. As stirring from the outside by shaking, for example, a method of vibrating a transformer container using a vibrating stirrer, a shaking table, a shaker, etc. (for example, a method of parallel vibration in the vertical and / or horizontal direction, And a method of rotating vibration). Examples of stirring from the inside using a stirrer include a method of stirring the reaction solution using a stirrer such as a stirring blade or a magnetic stirrer.

  In the case of shaking or stirring with a stirrer, the rotational speed is preferably in the range of 5 rpm to 500 rpm. If it is less than 5 rpm, the decomposition reaction rate will be slow, and if it exceeds 500 rpm, the energy efficiency of shaking will be poor. More preferably, the range of 20 rpm to 200 rpm is desirable.

  In the case of stirring, either continuous stirring or intermittent stirring may be employed. The stirring time and the stirring stop time can be appropriately determined according to the PCB concentration in the solution, the type and amount of the hydrogen donor, the type and amount of the reaction catalyst, and the like.

  Although reaction time is not specifically limited, 0.5 days-6 months are desirable. If it is less than 0.5 days, the PCB decomposition reaction is insufficient, and if the reaction time exceeds 6 months, there is no practical meaning. More desirably, it is 1 day to 3 months.

In the method of the present invention, a PCB, a mixture of alkali compound / hydrogen donor were mixed, with stirring, since dechlorination of PCB proceeds by standing at normal temperature, the external heating is not necessary There is . Na you, in order to suppress by-products, the reaction temperature is better to select a hydrogen donor so as not to reflux condition of the hydrogen donor.

  According to the method of the present invention, the high-concentration PCB is completely decomposed, so that it can be reused as fuel by collecting the biphenyl decomposed by the method.

  According to the method for dechlorinating a high-concentration PCB of the present invention, the PCB is decomposed and dechlorinated at a slightly lower rate than when hydrogen gas or heat is applied from the outside. Although the mechanism is not clear, it is considered that the alkali metal alkoxide provided from the alkali compound / hydrogen donor mixture promotes the dehalogenation reaction of PCB, and hydrogen radicals from the hydrogen donor enter there. Even if the decomposition rate is slow, PCBs can be processed by simply leaving them without preparing a new heating source or the like at a site such as a transformer storage.

  In the present invention, when polychlorinated biphenyls such as transformers are dechlorinated, the required amount is extracted and transferred to a separately prepared reaction tank, and a hydrogen donor and an alkali compound are added to dilute to a desired polychlorinated biphenyl concentration. Above, it is preferable to perform a decomposition treatment with a catalyst. After the decomposition treatment, the treated solution is stored in a treated solution tank prepared separately.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited only to a following example. In the following examples and the like, “mass%” is abbreviated as “%” unless otherwise specified.

  As a high-concentration PCB, 1 ml of KC-400 (biphenyl tetrachloride, produced by Kaneka Chemical Co., Ltd.) was prepared in an Erlenmeyer flask. There, 4.36 g of Nippon Soda KOH flakes (95%) as an alkaline substance and 100 ml of Wako Pure Chemicals isopropyl alcohol as an organic hydrogen donor were stirred for 20 minutes with a 3000 rpm homomixer to obtain a mixed solution. Was added. Further, 1 g of 80-100 mesh activated carbon (Pd / C: manufactured by Wako Pure Chemical Industries) carrying 10% palladium (catalyst ratio: 0.072) was added as a catalyst, and a shaker (EYELA3010 model) manufactured by Tokyo Rika Machinery Co., Ltd. was added. ) At 60 rpm for 21 days. The experiment was performed at room temperature (about 25 ° C.). The evaluation results are shown in Table 1.

The isomer distribution (% by weight) of KC-400 used in the experiment is shown below.
Monochrome Robiphenyl 0.01%
Dichlorobiphenyl 0.48%
Trichlorobiphenyl 17.47%
Tetrachlorobiphenyl 51.43%
Pentachlorobiphenyl 27.92%
Hexachlorobiphenyl 2.55%
Heptachlorobiphenyl 0.14%
Octachlorobiphenyl 0%
Nonachlorobiphenyl 0%
Decachlorobiphenyl 0%

(Composition of tetrachlorobiphenyl)
2,3,4,5-tetrachlorobiphenyl, 2,3,4,6-tetrachlorobiphenyl, 2,2 ′, 3,4-tetrachlorobiphenyl, 2,3,3 ′, 4-tetrachlorobiphenyl, Mainly contains 2,3,4,4′-tetrachlorobiphenyl, 3,4,4 ′, 5-tetrachlorobiphenyl, 3,3 ′, 4,4′-tetrachlorobiphenyl and the like.

(Evaluation methods)
The solution before and after the reaction was subjected to a gas chromatography mass spectrometer QP5050 (hereinafter referred to as “GC-MS”) manufactured by Shimadzu Corporation using DB1 (manufactured by J & W Scientific) as a capillary column. Chlorination (decomposition rate) was confirmed. At the same time, the amount of biphenyl as a decomposition product was also measured.

The evaluation of the dechlorination reaction was performed according to the following criteria.
○: Good (decomposition rate of 90% or more), X: Poor (decomposition rate of less than 90%)

  From the results shown in Table 1, in Example 1, the reaction time was 21 days, but most of the PCB disappeared, and it was confirmed that an equivalent amount of biphenyl was produced as a decomposition product.

  As a high-concentration PCB, 0.1 ml of KC-400 (biphenyl tetrachloride, produced by Kaneka Chemical Co., Ltd.) was prepared in an Erlenmeyer flask. Then, 2.18 g of Nippon Soda KOH flakes (95%) as an alkaline substance and 100 ml of Wako Pure Chemicals isopropyl alcohol as an organic hydrogen donor were stirred for 20 minutes with a 3000 rpm homomixer to obtain a mixed solution. added. Further, 1 g of 80-100 mesh activated carbon (Pd / C: manufactured by Wako Pure Chemical Industries) carrying 10% palladium (catalyst ratio: 0.72) was added as a catalyst, and a shaker (EYELA3010 type, manufactured by Tokyo Rika Machinery Co., Ltd.) was added. ) At 60 rpm for 21 days. The experiment was performed at room temperature (about 25 ° C.).

  As a high-concentration PCB, 1 ml of KC-400 (biphenyl tetrachloride, produced by Kaneka Chemical Co., Ltd.) was prepared in an Erlenmeyer flask. There, 1.38 g of KOH flakes (95%) manufactured by Nippon Soda as an alkaline substance and 100 ml of isopropyl alcohol manufactured by Wako Pure Chemical as an organic hydrogen donor were stirred for 20 minutes with a 3000 rpm homomixer to obtain a mixed solution. Was added. Further, 1 g of 80-100 mesh activated carbon (Pd / C: manufactured by Wako Pure Chemical Industries) carrying 10% palladium (catalyst ratio: 0.072) was added as a catalyst, and a shaker (EYELA3010 model) manufactured by Tokyo Rika Machinery Co., Ltd. was added. ) At 60 rpm for 21 days. The experiment was performed at room temperature (about 25 ° C.).

  The experimental conditions and evaluation results of Examples 2 to 3 are summarized in Table 2.

  From the results in Table 2, it was confirmed that PCB disappeared over time.

  The same operation as in Example 3 was performed except that 1 ml of KC-300 (biphenyl trichloride, manufactured by Kaneka Chemical Co., Ltd.) was used as the high-concentration PCB, and the mixture was shaken continuously for 14 days.

  The same operation as in Example 3 was performed except that 1 ml of KC-1000 (KC500 / trichlorobenzene mixture, manufactured by Kaneka Chemical Co., Ltd.) was used as the high-concentration PCB and the mixture was shaken continuously for 14 days.

(Comparative Example 1)
As a high-concentration PCB, 1 ml of KC-400 (biphenyl tetrachloride, produced by Kaneka Chemical Co., Ltd.) was prepared in an Erlenmeyer flask. Thereto, 1.38 g of Nippon Soda KOH flakes (95%) as an alkaline substance and 100 ml of Wako Pure Chemicals isopropyl alcohol as an organic hydrogen donor were added. Further, 1 g of 80-100 mesh activated carbon (Pd / C: manufactured by Wako Pure Chemical Industries) carrying 10% palladium (catalyst ratio: 0.072) was added as a catalyst, and a shaker (EYELA3010 model) manufactured by Tokyo Rika Machinery Co., Ltd. was added. ) At 60 rpm for 21 days. The experiment was performed at room temperature (about 25 ° C.).

Table 3 summarizes the experimental conditions and evaluation results of Examples 4 to 5 and Comparative Example 1. From the results of Table 2 and Table 3, it was confirmed that PCB disappeared in 3 weeks.

Claims (7)

The polychlorinated biphenyl was mixed with a mixed solution in which an alkali compound was previously dissolved in a hydrogen donor , and the mixed solution was mixed with a catalyst ratio (mass of polychlorinated biphenyl) in the presence of a catalyst in which palladium was supported on a carrier. A method of dechlorinating polychlorinated biphenyls, characterized in that dechlorination is carried out by reacting at a normal temperature ( non-heated ) with stirring at a mass ratio of the supported metal to 0.035 or more . The method for dechlorination of polychlorinated biphenyl according to claim 1, wherein the concentration of the polychlorinated biphenyl is 500 to 100,000 ppm (in the total amount of the mixed solution). The method for dechlorination of polychlorinated biphenyls according to claim 1, wherein the concentration of the alkali compound is 0.1 to 50% by mass (in the total amount of the alkali solution). The hydrogen donor is an amine-based compounds, alcohol compounds, polychlorinated biphenyls according to any one of claims 1 to 3, at least one compound selected from the group consisting of ketone compounds, and alicyclic compounds Dechlorination method. The method for dechlorination of polychlorinated biphenyls according to claim 4 , wherein the hydrogen donor is at least one compound selected from alcohol compounds. The method for dechlorination of polychlorinated biphenyl according to any one of claims 1 to 3 , wherein the alkali compound is at least one compound selected from the group consisting of caustic soda, caustic potash, sodium alkoxide, potassium alkoxide, and calcium hydroxide. . The polychlorinated biphenyl is a polychlorinated biphenyl in a transformer, and the polychlorinated biphenyl extracted from the transformer is dechlorinated by the method according to any one of claims 1 to 6 . Method.