JP2019198603A - Decomposition method of organic halide - Google Patents

Abstract

To overcome a problem with a method for decomposing organic halide by using a catalyst carrying a platinum element, which is preferable in safety because it can be conducted at ordinary temperature and ordinary pressure, that solid solution separation is complicated with current catalysts, and catalyst performance is quickly reduced.SOLUTION: By decomposition treating organic halide by using a catalyst carrying a platinum element catalyst by inside of a fiber by introducing an anion exchange group to a graft side chain of an organic polymer fiber substrate and sodium formate as a hydrogen donor, decomposition of organic halide with easy solid liquid separation and small deterioration of catalyst performance can be done.SELECTED DRAWING: Figure 1

Description

Detailed Description of the Invention

  The present invention relates to a method for decomposing organic halogen compounds such as pentachlorophenol (PCP) which is a pest control agent and polychlorinated biphenyl (PCB) which is an insulating material.

  Various organic halogen compounds discharged as waste include pesticides such as pentachlorophenol (PCP), and polychlorinated biphenyls (PCB) that are collected and stored after their manufacture and new use are prohibited. There is. These are not only harmful to the human body, but are very stable against heat and oxidation, and while this feature has been used as an advantage, the persistence in the environment and the difficulty of processing are now problematic. It has become. In addition, when incineration or thermal decomposition treatment, dioxins may be generated in an oxygen atmosphere, and it is necessary to decompose them thoroughly. Therefore, development of many decomposition and detoxification treatment techniques has been vigorously advanced, including treatment methods using catalysts and microorganisms.

  In the decomposition reaction of an organic halogen compound using a catalyst, there is a method of performing hydrodehalogenation using hydrogen gas in a gas phase and a liquid phase. For those having relatively high volatility, a reaction in the gas phase is effective, but a strong acid such as HCl gas is generated as a product, and there are problems such as catalyst deterioration due to halogen poisoning and corrosion of the apparatus. In the liquid phase reaction, in order to increase the solubility of hydrogen gas in the solvent, the reaction is usually performed under a pressure of about 50 atm, so that there remains a problem in safety.

  In contrast, hydrodehalogenation reactions using various organic compounds such as alcohols and formates as hydrogen sources have been studied (Patent Document 1, Non-Patent Document 1). This method is characterized in that the reaction proceeds at normal pressure and at a relatively low temperature without using expensive hydrogen gas. Previous studies have used palladium carbon (Pd / C) with palladium (Pd) supported on activated carbon for the decomposition reaction of organic halogen compounds. Since these are particles, there are problems that the pressure loss is large when the column is packed and used in the flow method, and the operations such as packing and discharging the column become complicated. In the batch method rather than the distribution method, the catalyst and the liquid to be treated are introduced into the reaction tank, and the organic halogen compound is decomposed while stirring under predetermined conditions. However, a solid-liquid separation operation is required between the catalyst and the liquid to be treated. Additional operations such as filtration and centrifugation are required. Therefore, there is an increasing expectation for the proposal of a new catalyst that facilitates solid-liquid separation and the development of a new decomposition method.

  There is a radiation graft polymerization method as a production method capable of providing a catalyst carrier that can be easily separated into solid and liquid. Since the radiation graft polymerization method can impart a function to an existing polymer, it has been applied in various fields. There is an example in which an organic polymer fiber is irradiated with radiation, an anion exchange group is introduced, a palladium chloro complex is ion-exchanged and adsorbed, hydrazine is added, reduction treatment is performed, and palladium is supported on the fiber (Patent Document) 2). In this prior example, the palladium-supported fiber is used for removing redox substances such as hydrogen peroxide in an aqueous solution, but in order to remove a very small amount of hydrogen peroxide at the ppb level present in pure water. However, it was not applied to a chemical reaction such as catalytic decomposition of an organic halogen compound, which is a technical field of the present invention. Therefore, it is necessary to develop an efficient decomposition method capable of maintaining the repeatability of the catalyst with a high decomposition rate of the organic halogen compound, while taking advantage of the feature that solid-liquid separation is easy.

JP-A-8-266888 JP 2017-70939 A

“Dehalogenation reaction of organohalogen compound using Pd / C catalyst in 2-propanol”, Nikka, 1998, No. 1 5, p369-371

  The present invention is to find a production condition of a platinum group element-supported catalyst having high decomposition efficiency of an organic halogen compound by using a radiation graft polymerization method, and to provide a novel decomposition method of the organic halogen compound by using this catalyst.

  The present invention solves the problem by providing a method for decomposing an organic halogen compound having the following characteristics.

(1) A method for decomposing an organic halogen compound, comprising contacting an anion exchanger carrying a platinum group element with an organic halogen compound and an anionic hydrogen donor in an aqueous medium. (2) The anionic hydrogen donation (3) The anion exchanger carrying the platinum group element is imparted to the anion exchanger by a single platinum group element or a platinum group element complex anion. (1) to (3) The method for decomposing an organohalogen compound according to (1) or (2), wherein the platinum group element is selected from palladium, ruthenium, rhodium and platinum (5) The anion exchanger may have an anion exchange group after irradiating the organic polymer fiber with radiation. It is obtained by graft polymerization of a monomer that can be converted to an anion exchange group. When the monomer that can be converted to an anion exchange group is graft polymerized, it is obtained by carrying out an anion exchange group introduction reaction next ( 1) A method for decomposing an organic halogen compound according to any one of (4)

  Various materials have been proposed as carriers for supporting platinum group elements, but anion exchangers are preferred because many of the platinum group elements form chloro complexes and exist as anions. As the anion exchanger, a typical commercially available styrene-divinylbenzene-based bead-shaped anion exchange resin can be used. However, since the shape is a bead shape, a column distribution system for filling the column and circulating the liquid to be treated, etc. Usage is limited. Examples of the functional group of the anion exchange resin include a strong basic anion exchange resin having a quaternary ammonium group and a weak basic anion exchange resin having a lower amino group such as a tertiary amino group and a secondary amino group. Can be used.

  Since the radiation graft polymerization method can introduce an anion exchange group into existing polymers having various shapes, it can be used in a manner not found in conventional ion exchange resins. After irradiating radiation with an existing polymer as a base material, polymerizing a polymerizable monomer (monomer) having an anion exchange group, or polymerizing a monomer that can be converted to an anion exchange group, and then introducing an anion exchange group By doing so, an anion exchanger utilizing the shape of the polymer of the substrate can be produced. This method using radiation is called a radiation graft polymerization method, and a material having a large surface area suitable for catalytic reaction can be selected, so that it is suitable for treating a small amount of special harmful substances as in the present invention.

Hereinafter, in order to explain in more detail, palladium as a platinum group element, an anion exchange fiber in which an anion exchange group is introduced by applying a radiation graft polymerization method to a fiber as a carrier of the platinum group element, and 2-chlorophenol as an organic halogen compound A specific description will be given by taking (2-C ₆ H ₅ ClO) as an example.

FIG. 1 shows a production process of the platinum group element-supported catalyst of the present invention and an organic halogen compound decomposition process using the same. A process of obtaining a graft fiber having a tertiary amino group by graft polymerization of dimethylaminoethyl methacrylate (DMAEMA) after irradiating the polyolefin fiber as a base material with gamma rays, and then a palladium chloride (PdCl ₄ ²⁻ ) complex. Shows a step of ion-exchange adsorption, a step of reducing the adsorbed palladium chloride complex with an aqueous sodium formate solution and supporting metal palladium (Pd ⁰ ) on the fiber. Furthermore, the Pd ⁰ using sodium formate as carrier fibers and a hydrogen donor, describes until decomposing organohalogen compounds.

  The radiation graft polymerization method is characterized in that it can use existing polymer substrates of various shapes, but it is also a great feature that ion exchange groups can be introduced into the substrate. Although depending on the type of radiation and the irradiation energy, when irradiated with radiation, radicals can be generated even inside the base polymer, and graft polymerization proceeds from that point as the starting point. This is a feature that differs greatly from mere surface modification. Therefore, when a fiber is selected as the base material, radicals are uniformly generated not only in the fiber surface layer but also inside. Therefore, graft polymerization occurs not only on the fiber surface but also inside, and the amount of functional groups can be increased. For example, the graft rate (weight increase rate) can easily be 50% or more, and can be 100% or more. The meaning of the numerical value that the graft ratio is 100% indicates that the weight of the graft side chain is the same as the weight of the base fiber, so that a large ion exchange capacity is obtained and the fiber diameter is considerably increased.

  The nature of the graft side chain can be easily understood by referring to FIG. A normal polymer such as polyethylene or polyamide is composed of an amorphous part 1 and a crystalline part 2 as shown in the left figure. One end of the graft side chain is covalently bonded to the base polymer, but the other end is a free end, so that there are a portion staying inside the fiber and a portion extending from the fiber surface to the outside. The former is called polymer root 3 and the latter is called polymer brush 4. The graft side chain does not have a cross-linked structure, and has a high adsorption rate and diffusion rate of adsorbed ions and exhibits excellent properties as a separation material.

The ion exchange group is positively or negatively charged depending on the type. For example, an anion exchange group such as an amino group is positively charged, and a cation exchange group such as a sulfonic acid group or a carboxyl group is negatively charged. When a graft side chain having an ion exchange group is bonded, both the roots and the brush are repelled and the space between the graft side chains is expanded. Therefore, anions and adsorbed substances in the aqueous solution can easily enter the fiber. Since palladium chloride is a divalent anion in the form of PdCl ₄ ²⁻ , it enters the inside of the fiber and adsorbs by ion exchange. Since the free end of the graft side chain is extended, the polymer brush is preferable for adsorption separation of ions and charged particles. An ion exchange resin has a cross-linked structure with a cross-linking agent such as divinylbenzene, and is not suitable for ion diffusion transfer because swelling is suppressed. From this point also, the radiation graft polymerization method is preferable as a method for producing a catalyst carrier. .

In order to use the adsorbed palladium chloride as a catalyst, it is necessary to reduce Pd ²⁺ to Pd ⁰ . The reducing agent can be selected from hydrazine hydrate, hydrazine salts such as hydrazine hydrochloride and hydrazine sulfate, organic acids such as formic acid, ascorbic acid and oxalic acid and alkali metal salts thereof, sodium sulfite, sodium borohydride and the like. . However, in the present invention, an anion exchanger obtained by radiation graft polymerization, particularly a fibrous anion exchanger, is used as a carrier, so that it can easily enter the anion exchange group inside the carrier and has an anionic property such as sodium formate, which has a high reduction rate. A reducing agent is preferred.

Palladium chloride (PdCl ₄ ²⁻ ) was adsorbed on a weakly basic anion exchange fiber grafted with DMAEMA by the radiation graft polymerization method, and the relationship between the adsorption amount of palladium chloride and the anion exchange group of DMAEMA fiber was investigated. As a result, the result of FIG. 3 was obtained. The reason for dividing the functional group amount by 2 is that palladium chloride is a divalent anion. The value of [charging amount] / [1/2 of the exchange capacity] is 1, and the adsorption amount of palladium chloride is saturated. The weight increase rate at the time of saturation is almost the same value as the weight increase rate calculated from the graft rate, and it can be seen that palladium chloride is quantitatively adsorbed on the ion exchange groups introduced into the fiber surface and inside.

The relationship between the Pd ⁰ carrying amount after reducing the palladium chloride adsorbed amount to the DMAEMA grafted fibers shown in FIG. The adsorption amount and the loading amount are in a one-to-one relationship, indicating that there is no omission when Pd ²⁺ is reduced to Pd ⁰ by contact with sodium formate. Therefore, the supported amount of Pd ⁰ can be easily controlled by the graft ratio and the amount of palladium chloride (PdCl ₄ ²⁻ ). When other reducing agents such as hydrazine hydrate (N ₂ H ₄ .H ₂ O) are used, reduction to Pd ⁰ can also be achieved by optimizing the reaction time by increasing the concentration. However, sodium formate can be effectively used as a hydrogen donor used when decomposing organic halogen compounds, and it has many advantages such as the ability to share chemicals and the high decomposition rate of organic halogen compounds. Sodium is preferred.

As described above, graft side chains by the radiation graft polymerization method exist as roots and brushes inside and outside the fiber. Palladium chloride (PdCl ₄ ²⁻ ) is adsorbed on the graft side chain as a divalent anion, and metal palladium is supported on the spot by contact with the reducing agent. PdCl ₄ ²⁻ adsorbed on the polymer brush portion is supported as Pd ⁰ near the fiber surface. In the case of a normal inorganic material, the addition of palladium chloride and the reduction support to the metal palladium are performed on the surface of the support, and may be lost due to the aggregation of Pd ⁰ particles accompanying the reduction treatment operation or the like, The palladium of the present invention is adsorbed and reduced not only on the fiber surface but also inside, and is supported as ultrafine particles on the spot.

Sodium formate can be used not only as a reducing agent to reduce Pd ²⁺ to Pd ⁰ , but also as a hydrogen donor. Further, it is highly compatible with organic halogen compounds, and chlorophenol can be dissolved and contacted with a catalyst without the addition of an organic solvent such as alcohol. In addition, since sodium formate is an anionic reducing agent, it can easily diffuse and penetrate into the anion exchange group inside the fiber and come into contact with the metal palladium fine particles. Since the organic halogen compound can be decomposed without adding an organic solvent such as alcohol, it is preferable for work and environmental measures. When alcohol is added, moisture around the anion exchange group introduced into the fiber is removed, so that the graft side chains shrink and mass transfer is reduced, which is not preferable for the catalytic decomposition reaction. In the case of an organic halogen compound that is not mixed with sodium formate, an organic solvent such as alcohol or sodium hydroxide may be added within a range in which the decomposition rate does not greatly decrease.

When anionic sodium formate is used as a hydrogen donor, a larger chlorophenol decomposition rate can be obtained than a cationic hydrogen donor such as hydrazine or a salt thereof. When Pd ²⁺ is reduced to Pd ⁰ , sodium formate can easily penetrate into the fiber with an anionic reducing agent, so that a large reduction rate can be obtained. This seems to be due to the effective use of.

The catalyst performance is preferably a catalyst capable of maintaining the performance for a long time without being deteriorated by repeated use. For example, in the decomposition process of an organic halogen compound, it is known that the catalyst performance is lowered due to contamination by coexisting oily components. That the catalyst of the present invention are preventing the hydrophilicity of the catalyst supporting sites because it extends to the inside of the fiber as well as the surface, it adheres closely organic contaminants missing small dots or hydrophobic Pd ⁰ This is considered to work effectively to maintain the catalyst performance. Therefore, even if the catalyst is used repeatedly, the performance deterioration is small.

FIG. 5 shows the results of reducing Pd ²⁺ of palladium chloride (PdCl ₄ ²⁻ ) with an aqueous sodium formate solution and decomposing chlorophenol using catalyst fibers supporting Pd ⁰ . Further, the results of the decomposition of chlorophenol using sodium formate as a hydrogen donor were omitted, and the step of reducing Pd ²⁺ was omitted. Since there is no difference in the decomposition rate of chlorophenol, it can be seen that the step of reducing the adsorbed palladium chloride to Pd ⁰ is unnecessary. Sodium formate used as a hydrogen donor also functions as a reducing agent. By using sodium formate as a reducing agent and a hydrogen donor, the chemical can be made common, and it is effective for simplifying the decomposition apparatus and the decomposition process. The simplified decomposition process of the organic halogen compound is as shown in FIG.

  Since the performance of the catalyst deteriorates quickly, it is an important performance evaluation item that it can be used repeatedly for a long time. When the performance of a conventional catalyst deteriorates, it must be replaced or replenished with a new or regenerated product and must be procured from a catalyst manufacturer. In the method for decomposing an organic halogen compound of the present invention, the initial decomposition efficiency can be maintained for a long time, but it must be considered that deterioration always occurs. According to the method for decomposing an organic halogen compound of the present invention, palladium chloride is adsorbed in advance before performing the decomposition treatment if the ion exchange capacity of the anion exchanger remains even if the catalyst performance is deteriorated. Therefore, the decomposition performance can be maintained for a long time.

When an organic halogen compound is decomposed using sodium formate as a hydrogen donor in the presence of a palladium catalyst, hydrochloric acid produced by the dehalogenation reaction is neutralized by sodium formate, and corrosion of the apparatus is suppressed. It is preferable for maintaining the soundness of the apparatus.
(4) Effects of the invention

  Since organohalogen compounds are stable, there have been safety issues such as the use of high temperature and pressure as a decomposition method. In recent years, a method for decomposing under mild conditions using a catalyst has been developed. However, since an expensive catalyst is used, the cost of decomposition treatment is high and the work process is complicated. The present invention employs a radiation graft polymerization method in which an existing organic polymer is irradiated with radiation and a monomer having an anion exchange group is graft-polymerized, whereby various decomposition catalysts according to the storage state of the organic halogen compound can be used. Can be provided in shape. In particular, by selecting a fiber having a large surface area as the base material, the reaction rate can be increased and the molding processability is good. Therefore, it has become possible to work more easily than conventional methods of use. In addition, the platinum group element is supported on the anion exchanger and an anionic hydrogen donor such as sodium formate can be added to increase the decomposition rate of the organic halogen compound, and the catalyst performance during repeated use can be maintained for a long time. Became. Furthermore, it is also practically important that the performance of a deteriorated catalyst can be recovered by a simple treatment.

It is a flowchart which shows the preparation method of the palladium carrying | support fiber of this invention, and the decomposition | disassembly method of an organic halogen compound. It is a conceptual diagram which shows the property of the graft side chain at the time of performing radiation graft polymerization to a polymer base material. It is a figure which shows the relationship between the ratio of the preparation amount of a palladium chloride and the anion exchange group of DMAEMA fiber x1 / 2 ([palladium chloride] / [functional group amount / 2]) and the weight increase rate after palladium chloride adsorption. . Is a diagram showing a relationship between palladium chloride adsorbed amount and Pd ⁰ carrying amount after reduction to DMAEMA grafted fibers. The adsorption amount and the loading amount have a one-to-one relationship, and when Pd ²⁺ is reduced to Pd ⁰ by contact with sodium formate, it is quantitatively reduced and there is no omission. Pd is a graph showing the degradation characteristics of both in the case of decomposing while chlorophenol adsorbed palladium chloride (PdCl 4 ^_2-) without passing through the reduction treatment in the case of using a ⁰ fiber. Both fibers also chlorophenol degradation rate is the same, the reduction process for the Pd ²⁺ to Pd ⁰ is a diagram showing that it is not necessary. It is a flowchart which shows the preparation method of the palladium carrying | support fiber of this invention, and the decomposition | disassembly method of the organic halogen compound which does not pass through a reduction process process. Mall-like structure Wind filter It is the figure which compared the chlorophenol decomposition | disassembly rate in the case of using sodium formate and hydrazine as a hydrogen donor. In the case of sodium formate, the decomposition rate reaches 100% in about 1 hour, but in the case of hydrazine, the decomposition rate is slightly higher than 90% after reacting for 8 hours. This is a diagram showing that the decomposition rate of sodium formate is high. Is a graph showing changes in degradation rate when repeated chlorophenol decomposition test of Pd ⁰ supported catalyst 5 times Sodium formate as hydrogen donor. Even after being repeated five times, the decomposition rate is maintained at 90% or more, and the deterioration of the catalyst performance is small. Is a graph showing changes in degradation rate when repeated 5 times chlorophenol decomposition test of Pd ⁰ supported catalyst the hydrazine hydrochloride as a hydrogen donor. From the second time, the decomposition rate decreased to 50%, and after that, the decomposition rate was about 50% even if it was repeated three times.

  The characteristics of radiation graft polymerization are the existing polymers of various shapes, such as single fibers, twisted yarns that are aggregates of single fibers, woven or non-woven fabrics that have been processed into sheets, films and porous films, Any of porous hollow fibers and particles can be used. Therefore, the adsorption rate can be increased by using fibers that have a large surface area and are easy to mold. Molded products such as a wind filter using twisted yarn and a pleated filter using non-woven fabric can be combined with functions of filtration and ion adsorption.

  Examples of the fiber material include synthetic fibers, natural fiber cellulose fibers such as cotton, animal fibers such as silk and wool, regenerated fibers, or mixed fibers thereof. Synthetic fibers include polyester, polyamide, acrylic, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyurethane, polyvinyl alcohol, fluorine, and the like. Cellulosic fibers include natural cellulose fibers such as cotton and hemp, viscose rayon, copper ammonia rayon, regenerated cellulose fibers such as polynosic, purified cellulose fibers such as tencel, and semi-synthetic fibers such as acetate and diacetate. It is. Animal fibers include animal hair fibers such as wool, silk and the like. The recycled fiber includes chitin / chitosan fiber, collagen fiber and the like. Among these, polymers such as polyolefins typified by polyethylene, polyamides typified by nylon, and celluloses are particularly preferable. Among these materials, it can be appropriately determined in consideration of radiation resistance, graft polymerizability, chemical resistance and the like.

  Ionizing radiation to irradiate fibers includes α rays, β rays, gamma rays, electron beams, neutron rays, ultraviolet rays, etc., but gamma rays and electron beams that have the ability to penetrate from the surface of the fiber that is the substrate to deep parts. Is preferably used. The irradiation condition of radiation is not particularly limited, but in order to obtain sufficient grafting efficiency, it is preferably 5 to 200 kGy, particularly 15 to 100 kGy in a deoxygenated state. At this time, the oxygen concentration may be a concentration at which graft polymerization can be achieved at a required polymerization rate, and is preferably 1% or less, more preferably 100 ppm or less. In FIG. 1, gamma rays are used.

  When the fiber is irradiated with ionizing radiation, radicals are generated on the fiber surface and inside. If the monomer which has an ion exchange group or the monomer which can be converted into an ion exchange group is made to contact here, a monomer will superpose | polymerize on the basis of the generated radical. Graft polymerization is divided into a pre-irradiation graft polymerization method and a simultaneous irradiation graft polymerization method depending on the timing of radiation irradiation. The pre-irradiation graft polymerization method is a polymerization method in which a base material and a monomer are brought into contact with each other after irradiating the base material in advance, and is generally used as a method for producing a separation material because the amount of homopolymer is small. It is a suitable method. The simultaneous irradiation graft polymerization method is a graft polymerization method in which radiation is irradiated in the presence of a substrate and a monomer. Although any irradiation method can be adopted in the present invention, it is more preferable as a method for producing a separation material, which is an application of the present invention, to use a pre-irradiation graft polymerization method with a small amount of homopolymer (homopolymer). FIG. 1 shows an example of graft polymerization by a pre-irradiation graft polymerization method.

  In the graft polymerization, when the monomer to be contacted is a liquid, it is called a liquid phase graft polymerization method, and when it is a gas, it is called a gas phase graft polymerization method. Further, when an emulsion monomer solution is used in the liquid phase graft polymerization method, it is called an emulsion graft polymerization method. Furthermore, there is an impregnation graft polymerization method positioned between the liquid phase graft polymerization method and the gas phase graft polymerization method. The impregnation graft polymerization method is a graft polymerization method in which a monomer amount is calculated in advance so that a predetermined graft ratio is obtained, and a necessary amount of monomer is immersed in an organic polymer molded body in advance. Any method can be applied in the present invention.

  As the emulsion graft polymerization method, a method described in a patent document (Japanese Patent Application Laid-Open No. 2005-344047) can be adopted. That is, an emulsion solution comprising a hydrophobic monomer such as GMA or styrene, a surfactant, and water can be prepared and carried out by a liquid phase graft polymerization method, and a graft ratio of 100% or more can be easily obtained. As the surfactant, any of cationic, anionic and nonionic surfactants can be used.

  After generating a radical by irradiation, the graft side chain having an anion exchange group grows by contacting with a monomer having an anion exchange group. In this way, an anion exchange group can be introduced into the fiber. As monomers having an anion exchange group, vinylbenzyltrimethylammonium chloride, arylamine, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate (DMAEMA), N, N-diethylaminoethyl methacrylate, N, N-dimethyl Examples include acrylamide, N, N-dimethylaminopropyl acrylamide, and quaternary ammonium salts of N, N-dimethylaminopropyl acrylamide.

  Although the monomer itself does not have an anion exchange group, a monomer that can be converted into an anion exchange group by a secondary reaction can also be used, such as glycidyl methacrylate (GMA), styrene, chloromethyl styrene and the like. After graft polymerization of these monomers, for example, in the case of GMA, a tertiary amino group can be introduced by reacting an amine having a secondary amine such as dimethylamine, diethylamine or diethanolamine. A quaternary ammonium group can be introduced by reacting a polyamine such as trimethylamine, triethylamine or a salt thereof, triethylenediamine and the like, and can be used as a support for supporting a platinum group element of the present invention.

Adsorption of palladium chloride on the anion exchanger, and subsequent reduction to Pd ⁰ with sodium formate can be done in a batch or column manner. The supported amount of Pd ⁰ can be easily controlled by the graft ratio and the amount of palladium chloride used, but can be appropriately set according to the treatment amount and concentration of the organic halogen compound and the decomposition treatment conditions. Since palladium chloride is an expensive chemical, it is not necessary to add an amount corresponding to the anion exchange group. According to the simplified method for decomposing an organic halogen compound of the present invention, by adsorbing a small amount of palladium chloride before the treatment of the organic halogen compound, an effect equivalent to that when Pd ⁰ is supported is recognized. It is done. It is not necessary to use a catalyst carrying a large amount of palladium from the beginning. When the catalyst performance starts to deteriorate, a small amount of palladium chloride is contacted with the remaining anion exchange group before the decomposition treatment of the organic halogen compound. If Pd ²⁺ is adsorbed on the catalyst, the catalyst performance can be maintained for a long time, and palladium can be saved.

In the decomposition treatment of the organic halogen compound, addition of Pd ⁰ supporting fiber in a mixture of sodium formate solution and an organic halogen compound, it can be carried out for a predetermined time decomposition reaction. At the end of decomposition, solid-liquid separation can be performed by removing the fibers. Required Pd ⁰ supported catalyst fiber content and processing conditions, the quality of the organic halogen compound to be processed, the amount, the processing conditions and the like, can be determined beforehand by preliminary tests. When sodium formate and the organic halogen compound are not mixed, an organic solvent such as alcohol may be added. The need for organic solvents can be examined by conducting a preliminary test.

  Since the fibrous adsorbent can be easily molded after graft polymerization, various shapes and usage methods can be selected depending on the use environment. Shapes such as twisted yarn and non-woven fabric are easy to handle when manufacturing the adsorbent. In addition, as molded products, bobbin-like structures wound with twisted yarn, cartridge filter structures, molding-like (braid-like) fiber structures, rope-like, sheet-like fiber aggregates such as nonwoven fabrics and woven fabrics, and their cutting The one selected from the processed products can be used.

  As shown in FIG. 7, the molding structure is a kind of braid having a structure in which the twisted yarn 5 is radially projected outside the core 6. The molding structure is suitable for use by immersing an organic halogen compound in a liquid. It can be easily collected by a method such as immersing for a certain period of time and winding up one end of the molding when a predetermined treatment is completed. In addition, the cut fiber can be packed in a packed tower and used in a distribution system, or can be used in a flow system.

  For example, in the case of the wind filter shown in FIG. 8, the cartridge filter structure is a pleated shape in which a twisted yarn 5 carrying catalyst fibers is wound around an inner cylinder (perforated core) 7 or a non-woven sheet or a porous membrane sheet around the inner cylinder. It is like a pleated filter (not shown) that has been processed and rolled. The cartridge filter is often used by being housed in a suitable housing as a pre-filter, and the present invention can also be used by being housed in such a housing. Originally, the cartridge filter has a filtration function, so that both functions of filtration and catalyst decomposition can be combined.

  As mentioned above, although this invention demonstrated the example using the anion exchanger manufactured by the radiation graft polymerization method, a commercially available anion exchange resin can also be utilized. Further, although the description has been given by taking the catalyst supporting palladium as an example, the same applies to the catalyst to which other platinum group elements such as ruthenium and rhodium are added. Although 2-chlorophenol has been described as an example of a representative example of the organic halogen compound, it can be applied to other organic halogen compounds.

The following specific examples further illustrate the present invention.

(1) Production of weakly basic anion exchange fiber After replacing 500 g of polyethylene fiber having a diameter of about 25 μm with a plastic bag with a chuck, irradiation with 100 kGy of gamma rays was performed. This irradiated fiber was immersed in a 10% aqueous solution of dimethylaminoethyl methacrylate (DMAEMA) previously subjected to nitrogen bubbling for 30 minutes, and reacted at 40 ° C. for 5 hours. The fibers after the reaction were taken out and batch-washed 5 times with pure water at 40 ° C. When the weight after drying was measured, the weight increase rate was 58%, that is, the graft rate was 58%. This fiber was a weakly basic anion exchange fiber having a tertiary amine of 2.8 mmol / g.

(2) Supporting Pd ⁰ 10 g of graft-polymerized fiber was taken and immersed in 1 L of 1% palladium chloride solution at room temperature for 1 hour to adsorb palladium chloride. The taken out fiber was batch washed with 1 L of pure water 5 times and dried. The weight increase after drying was 21.8%, which was 97% of the weight increase calculated from the anion exchange capacity. In the radiation graft polymerization method, tertiary amine is introduced not only into the surface layer of the fiber but also into the interior, so that palladium chloride is uniformly adsorbed into the interior of the fiber. Next, it was immersed in a 2% aqueous solution of sodium formate, and Pd ²⁺ was supported on Pd ⁰ by reduction. Pd ⁰ was a weight increase rate of 10.6% with respect to the weakly basic anion exchange fiber.

(3) Chlorophenol degradation test with sodium formate 0.1 g of Pd ^0- supported fiber was added to a 0.69 M sodium formate (HCOONa) solution containing 2.4 mmol of chlorophenol (C ₆ H ₅ ClO) at 30 ° C., liquid fiber It was immersed in shaking for 5 hours under the condition of a ratio of 200 ml / g. Here, the molar ratio of chlorophenol / PdCl ₄ ²⁻ was 20, and sodium formate / PdCl ₄ ⁻ was 100. During the chlorophenol decomposition reaction, sampling was performed every predetermined time, and chlorophenol and phenol were analyzed with a gas chromatograph analyzer. The results are shown in FIG. Chlorophenol began to decompose rapidly immediately after the reaction and reached a decomposition rate of 100% in about 1 hour.

[Comparative Example 1]
(4) Chlorophenol degradation test with hydrazine hydrochloride A chlorophenol degradation test was conducted under the same conditions except that a 0.4 M hydrazine hydrochloride solution was used instead of sodium formate in (3). Here, hydrazine hydrochloride was dissolved in a solution of 1M NaOH / ethanol = 37.5 / 62.5 (v / v)%. The results are also shown in FIG. The decomposition rate was about 50% in 2 hours after the reaction and 75% after 4 hours, and the decomposition rate was low.

From Example 1 and Comparative Example 1, radiation-induced graft polymerization anion exchange fibers to Pd ⁰ supported catalyst fibers of 2-chlorophenol decomposition test results with by, the larger sodium formate than hydrazine hydrochloride as a hydrogen donor Degradation rate was obtained.

(5) Chlorophenol decomposition repeated test using sodium formate as a hydrogen donor The chlorophenol decomposition test of (3) was repeated 5 times, and the decomposition rate of chlorophenol was measured. The results are shown in FIG. Even at the fifth reaction, a decomposition rate close to 100% was obtained and no tendency to deteriorate was observed.

[Comparative Example 2]
(6) Repeated test using hydrazine hydrochloride as a hydrogen donor The chlorophenol decomposition test of (4) in [Comparative Example 1] was repeated 5 times to measure the decomposition rate of chlorophenol. The results are shown in FIG. The decomposition rate of the second reaction was lowered to 45% of the initial value, and the decomposition rate was constant at about 45% after the second time.

  From Example 2 and Comparative Example 2, sodium formate had a smaller decrease in catalyst performance than hydrazine hydrochloride, and a favorable result as a hydrogen donor was obtained.

In [Example 2], the same chlorophenol decomposition test as in (3) was performed using palladium chloride-adsorbed fibers (Pd ²⁺ fibers) without reduction. As a result, a decomposition rate of about 100% was obtained in about 1 hour, and it was demonstrated that chlorophenol can be decomposed without performing an operation of reducing Pd ²⁺ to Pd ⁰ in advance, and that the decomposition process can be simplified. It was.

  According to the present invention, it is possible to decompose an organic halogen compound having various features such as a high decomposition rate of the organic halogen compound, a small decrease in catalyst performance, and easy solid-liquid separation.

DESCRIPTION OF SYMBOLS 1 Amorphous part 2 Crystal 3 Polymer roots 4 Polymer brush 5 Catalyst fiber 6 Core 7 Core

Claims (5)

  A method for decomposing an organic halogen compound, comprising contacting an anion exchanger carrying a platinum group element with an organic halogen compound and an anionic hydrogen donor in an aqueous medium.   The method for decomposing an organic halogen compound according to claim 1, wherein the anionic hydrogen donor is sodium formate.   3. The method for decomposing an organic halogen compound according to claim 1, wherein the platinum group element-supported anion exchanger is obtained by adding a single platinum group element or a platinum group element complex anion to the anion exchanger.   The method for decomposing an organic halogen compound according to any one of claims 1 to 3, wherein the platinum group element is selected from palladium, ruthenium, and rhodium.   The anion exchanger is obtained by irradiating an organic polymer fiber with radiation, and then graft-polymerizing a monomer having an anion exchange group or being convertible to an anion exchange group. The method for decomposing an organic halogen compound according to any one of claims 1 to 4, further comprising an anion exchange group introduction reaction in the case of graft polymerization.