JP2011098253A - Method of reactivating degraded catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of reactivating a catalyst, whereby a catalyst comprising supported noble metal having been used in decomposing an organochlorine compound present in oil to be treated and caused to decrease its decomposition capability, can be made reusable. <P>SOLUTION: There is provided the method of reactivating a catalyst, whereby a catalyst caused to decrease its decomposition capability in a process of decomposing an organochlorine compound can be made reusable, in which process a liquid mixture of insulation oil comprising an organochlorine compound, an alkali-metal hydroxide and isopropanol, is allowed to flow through a catalyst column to contact the catalyst comprising noble metal supported by a support to decompose the organochlorine compound. The method includes reducing the catalyst of decreased decomposition capability present in an apparatus filled with the catalyst without taking the same out of the apparatus, by allowing an isopropanol solution of the alkali-metal hydroxide to flow through the catalyst of decreased decomposition capability to heat the catalyst. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention is a method for regenerating a catalyst capable of reusing a deteriorated catalyst having a reduced resolution, and more specifically, a noble metal-supported catalyst having a reduced resolution used for decomposing organochlorine compounds in oil to be treated. The present invention relates to a method for regenerating a catalyst, which can be reused.

  Among various organic chlorine 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 production, importation, Use is prohibited. However, after that, tens of thousands of tons of PCBs are left untreated without determining an appropriate disposal method. In view of the fact that PCB is a by-product of chlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF), which are highly toxic dioxins in high temperature decomposition, it is difficult to decompose PCB safely. An efficient decomposition method is desired.

  Against this background, many methods have been proposed for dechlorinating and decomposing organochlorine compounds such as PCB under mild conditions at relatively low temperatures. Among them, as a method capable of decomposing PCB and the like at a low temperature and in a short time, in the presence of a catalyst in which a hydrogen donor and an alkali compound are added to an insulating oil containing PCB or low concentration PCB and palladium is supported on activated carbon. A method for efficiently decomposing PCB by irradiating microwaves is known (see, for example, Patent Documents 1 and 2).

  When PCB is decomposed by such a method, as the PCB decomposition reaction is repeated, the catalyst deteriorates and its activity decreases. Since noble metal-supported catalysts are expensive, it is essential to regenerate and reuse a catalyst with reduced activity in order to reduce the cost of PCB decomposition treatment. In particular, decomposition treatment of PCB contained in insulating oil In the case of the catalyst used in the above, regeneration is not easy because insulating oil additives such as deteriorated oil and antioxidants and decomposition products thereof adhere to the surface and block the active site of the catalyst. Therefore, various methods for regenerating the catalyst have been proposed.

  In Patent Document 3, a catalyst used for dechlorination treatment of PCB in insulating oil and having reduced activity is washed with water or an organic solvent to remove salts generated from the detached chlorine and the alkali used in the reaction. Thus, a method for regenerating the catalyst is disclosed. Examples of the organic solvent used for washing include alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as acetone, esters such as ethyl acetate, and hydrocarbons such as hexane and toluene.

  In Patent Document 4, a catalyst having reduced activity used for PCB dechlorination treatment in insulating oil is washed with an organic solvent, then washed with water, and then treated with a reducing agent to regenerate the catalyst. A method is disclosed. Examples of organic solvents used for washing include alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as acetone, esters such as ethyl acetate, and hydrocarbons such as hexane and toluene, and reducing agents include hydrogen, hydrazine, and hydrogenation. Examples include aluminum lithium and sodium borohydride. In the examples, after washing with acetone, washing with water and air-drying, acetone is added and extraction treatment is performed at 200 ° C., followed by extraction treatment at 200 ° C. with subcritical water, followed by drying, and hydrogen / nitrogen. A method of reduction by adding a mixed gas or hydrazine is described.

  In addition, as a method for regenerating the activity-reducing catalyst used in the decomposition treatment of high-concentration PCB using only PCB as an insulating oil, in Patent Document 5, it is washed with isopropyl alcohol and then with a hydrocarbon solvent, Furthermore, a method of washing with a hydrophilic organic solvent, washing with water and then drying is disclosed.

  Patent Documents 3 to 5 describe that in the cleaning step in the regeneration process of the catalyst, it is possible to adopt a method in which the cleaning agent is circulated in the catalyst tank (catalyst column) filled with the catalyst without taking out the catalyst. However, the method described in Patent Document 3 cannot generate hydrogen, and therefore cannot be cleaned in a reducing atmosphere, or has a problem that a large amount of solvent is required because regeneration is performed only by a cleaning operation. is there.

In addition, the methods described in Patent Documents 4 and 5 combine cleaning with an organic solvent and cleaning with water, and it is necessary to perform a plurality of cleaning steps, and when cleaning with water is performed. However, in order to reuse the regenerated catalyst, it is necessary to remove the water adhering to the catalyst, which causes a problem that the catalyst regeneration process becomes complicated in multiple stages. In addition, since the method described in Patent Document 4 requires an extraction process at a high temperature, it is difficult to process the catalyst in a state where it is packed in a catalyst filling apparatus.
Furthermore, when the catalyst is actually deteriorated in the PCB processing apparatus, the reaction must be interrupted once, and the deteriorated catalyst must be taken out of the catalyst filling apparatus and regenerated, resulting in poor work efficiency. There is also a problem that removal from the catalyst filling device becomes an operation at a management level because it adheres, and there is a risk that the catalyst particles may collapse and shorten the catalyst life during removal from the catalyst filling device.

Japanese Patent No. 3678740 Japanese Patent No. 3678738 JP 2005-270837 A JP 2007-111161 A JP 2008-272584 A

  The present invention has been made in view of the above circumstances, and treats a catalyst without removing a noble metal-supported catalyst having a reduced resolution used for the decomposition of organochlorine compounds in oil to be treated from the catalyst filling device. Therefore, it is an object of the present invention to provide a method for regenerating a catalyst which does not require the use of a special apparatus and can be reused by a simple operation.

  The present inventors diligently studied to solve the above problems. As a result, it is possible to use the isopropyl alcohol as a cleaning agent and to act as a hydrogen donor by heating the mixed solution of the alkali metal hydroxide and isopropyl alcohol through the catalyst with reduced resolution. The present inventors have found that the catalyst can be effectively regenerated and have reached the present invention.

That is, the present invention is as follows.
(1) A mixture of an insulating oil containing an organic chlorine compound, an alkali metal hydroxide and isopropyl alcohol is circulated through a catalyst filling device filled with a catalyst in which a noble metal is supported on a carrier, and brought into contact with the catalyst to form organic chlorine. In the decomposition process to decompose the compound,
A method for regenerating a catalyst that makes it possible to reuse a catalyst with reduced resolution,
In a state where the catalyst filling device is filled without removing the catalyst having reduced resolution, heating is performed while circulating an alkali metal hydroxide and isopropyl alcohol through the catalyst filling device, and the catalyst is reduced using isopropyl alcohol as a hydrogen donor. A method for regenerating a catalyst.
(2) The method for regenerating a catalyst according to (1), wherein the amount of isopropyl alcohol used is 1 to 10 L per kg of the catalyst.
(3) The method for regenerating a catalyst according to (1) or (2) above, wherein the amount of alkali metal hydroxide used is 0.1 to 0.3 w / v% based on isopropyl alcohol.
(4) The method for regenerating a catalyst according to any one of (1) to (3), wherein the heating temperature is 30 to 60 ° C.
(5) The method for regenerating a catalyst according to any one of (1) to (4), wherein the heating is microwave heating.
(6) The method for regenerating a catalyst according to any one of (1) to (5), wherein the noble metal is palladium.
(7) The method for regenerating a catalyst according to any one of (1) to (6), wherein the support is selected from the group consisting of carbon, a resin, and a combination thereof.
(8) In any one of the above (1) to (7), the organic chlorine compound is an organic chlorine compound selected from the group consisting of PCBs, dioxins, aromatic chlorine compounds, and mixtures of two or more thereof. A method for regenerating the catalyst as described.

According to the method for regenerating a catalyst according to the present invention, it is possible to remove hydrophobic impurities derived from trace components in insulating oil, which are thought to be accumulated or adsorbed on the catalyst during the organic chlorine compound decomposition reaction, and Because it can be processed with the catalyst filled, the catalyst on the surface of the catalyst layer where the most impurities are present can be concentrated and irradiated with microwaves without mixing with other catalysts. The catalyst can be efficiently regenerated.
The alkali metal hydroxide and isopropyl alcohol used for regeneration are the same as the alkali metal hydroxide and isopropyl alcohol added to decompose the organic chlorine compound contained in the insulating oil. Therefore, the catalyst after the regeneration treatment and the alkali metal hydroxide and isopropyl alcohol used in the regeneration treatment can be subjected to a decomposition treatment of insulating oil containing an organic chlorine compound from the state after the regeneration treatment is completed. it can.

  That is, in the catalyst regeneration method according to the present invention, the catalyst can be regenerated in a one-step process in which an alkali metal hydroxide and isopropyl alcohol are added, circulated and heated. It is extremely simple and economical because it does not require any special equipment for regeneration and does not require recovery or purification of the solvent that is generated when a solvent different from isopropyl alcohol is used for catalyst regeneration. The present invention provides a method for regenerating a typical catalyst and a method for decomposing an organic chlorine compound contained in an insulating oil or the like.

It is the schematic which shows the decomposition | disassembly apparatus of the organochlorine compound used in the Example of this invention. It is a graph which shows the PCB density | concentration change in the decomposition | disassembly test of the Example of this invention.

In the catalyst regeneration method of the present invention, a mixed liquid of an insulating oil containing an organic chlorine compound, an alkali metal hydroxide and isopropyl alcohol is circulated through a catalyst filling apparatus filled with a catalyst having a noble metal supported on a carrier, and the catalyst In the decomposition treatment that decomposes organochlorine compounds by contacting with
A method for regenerating a catalyst that makes it possible to reuse a catalyst with reduced resolution,
In a state where the catalyst filling device is filled without removing the catalyst having reduced resolution, heating is performed while circulating an alkali metal hydroxide and isopropyl alcohol through the catalyst filling device, and the catalyst is reduced using isopropyl alcohol as a hydrogen donor. It is characterized by this.

  In the catalyst regeneration method according to the present invention, details of the reason why the catalyst is effectively regenerated are unknown, but are estimated as follows.

  Based on the experience of disassembling various types of PCBs, it has been found that low-concentration PCBs containing PCB in insulating oil are more difficult to decompose than high-concentration PCBs using PCB itself as insulating oil. This suggests that additives (such as antioxidants) in the insulating oil and oxidative degradation products of the insulating oil over time strongly inhibit the catalytic reaction.

  In the present invention, since isopropyl alcohol is used for regeneration of the catalyst, the insulating oil or the like adhering to the catalyst surface is dissolved and removed in isopropyl alcohol, and at the same time, isopropyl alcohol is hydrogenated by using an alkali metal hydroxide in combination. In order to effectively act as a donor, it is presumed that the oxidative degradation product of the insulating oil is reductively decomposed to be easily desorbed from the catalyst surface. Therefore, in the present invention, it is considered that the catalyst can be effectively regenerated with a small amount of isopropyl alcohol as compared with the case of simply washing with an organic solvent or the like.

  A decomposition reaction apparatus such as PCB to which the catalyst regeneration method of the present invention can be applied is an apparatus equipped with a catalyst filling apparatus, which is a mixture of an insulating oil containing an organic chlorine compound such as PCB, an alkali metal hydroxide, and isopropyl alcohol. Any device having a function of circulating and circulating the liquid in the catalyst, a function of heating the catalyst when the mixed liquid flows through the catalyst, and a function of maintaining the mixed liquid at a predetermined temperature may be used. . A specific example of the apparatus used in the present invention is shown in FIG.

  The apparatus of FIG. 1 contains the catalyst filling device 1, the catalyst filling device 1 in the upper part thereof, the catalyst tank 4 in which the lower part is a liquid reservoir, the liquid in the liquid reservoir is taken out and supplied to the catalyst filling device 1, A circulation system (line 11, line 12 and pump 13) for returning the liquid to the liquid pool again, a microwave device 8 for irradiating the catalyst filling device 1 with microwaves, and a cooling coil 10 for cooling the liquid in the liquid pool. Have. Reference numeral 16 denotes a temperature controller capable of controlling the microwave irradiation amount. The catalyst 3 is filled in the catalyst cartridge 2 and installed in the catalyst filling device 1. A rod-like structure 5 made of a heat-resistant material that transmits microwaves, such as ceramic or Teflon (registered trademark), is disposed in the catalyst cartridge 2. It plays a role to communicate up to.

  The liquid flowing through the catalyst layer flows out through a flow hole (not shown) opened at the bottom of the catalyst cartridge 2, overflows from the overflow port 6 provided in the catalyst filling device 1, and flows into the catalyst tank. Circulate by returning to the 4 reservoir. Since the liquid heated by the microwave irradiation when circulating in the catalyst layer is cooled by the cooling coil 10 in the liquid reservoir and then circulated to the catalyst filling device 1, the microwave irradiation time and intensity are electrically controlled. By controlling so that the temperature of the liquid flowing through the catalyst layer can be controlled to a predetermined temperature.

  In the present invention, the organic chlorine compound includes an organic chlorine compound selected from the group consisting of PCB; dioxins; aromatic chlorine compounds such as trichlorobenzene and dichlorobenzene, and a mixture of two or more thereof.

  As insulating oil containing an organic chlorine compound, what is filled or stored in a pole transformer, a large transformer, an OF cable insulating oil tank, a ballast, etc. are mentioned.

  When decomposing an organic chlorine compound, a mixture of an insulating oil containing an organic chlorine compound, an alkali metal hydroxide and isopropyl alcohol is circulated through a catalyst filling device filled with a catalyst having a noble metal supported on a carrier. The organochlorine compound is decomposed by being brought into contact with the catalyst. As the organochlorine compound is decomposed, acetone, biphenyl and the like as by-products are contained in the mixed solution. The alkali metal hydroxide is added to capture chlorine desorbed from the organic chlorine compound. Among them, the dechlorination efficiency is high, it is available at low cost, the handling property is good, From the viewpoint of excellent solubility, NaOH or KOH is preferably used. An alkali metal hydroxide may be used independently and may use 2 or more types together. Isopropyl alcohol is added as a hydrogen donor, and is excellent in terms of safety, cost, decomposition efficiency of organochlorine compounds, and ease of reaction control.

  The amount of alkali metal hydroxide and isopropyl alcohol used in the decomposition treatment is not limited, but the alkali metal hydroxide is preferably used in an amount of 0.1 to 50% (wt / vol) relative to isopropyl alcohol. Preferably it is 0.1 to 10% (wt / vol). If the amount of the alkali metal hydroxide is too small, the decomposition reaction does not proceed. On the other hand, if the amount is too large, the alkali metal hydroxide cannot be completely dissolved. The alkali metal hydroxide is preferably used in an amount of 0.02 to 10% (wt / vol) with respect to the insulating oil. Isopropyl alcohol is preferably used in an amount of 5 to 200% (vol / vol) based on the insulating oil. If it is less than 5%, the viscosity of the insulating oil increases and the decomposition reaction does not proceed. On the other hand, even if it exceeds 200%, the reaction proceeds sufficiently, but becomes uneconomical. In addition, when decomposing a small amount of PCB in the insulating oil filled in the pole transformer, etc., the hydrogen donor may not be able to enter the gap of the container such as the pole transformer. On the other hand, the upper limit is preferably about 50%.

  As the decomposition method, a known method can be applied, and examples include a method in which microwaves are irradiated continuously or intermittently and decomposed at 50 to 80 ° C.

  The catalyst in which the noble metal is supported on the carrier is not particularly limited as long as it can accelerate the dechlorination reaction of the organic chlorine compound. The supported amount of the noble metal in the catalyst is preferably 1 to 20% by mass, more preferably 5 to 10% by mass with respect to the total amount of the catalyst. Examples of the noble metal to be supported include palladium, ruthenium, palladium, rhodium, iridium, osmium, and platinum. In consideration of high dechlorination efficiency, palladium, ruthenium, and platinum are preferable, and palladium is particularly preferable.

  Any carrier can be used as long as it is generally used as a carrier for a noble metal catalyst. Specifically, a carrier having excellent alkali resistance such as carbon such as activated carbon generally used as an adsorbent; resin such as silicone resin, polyethylene resin and polystyrene resin; metal oxide or composite metal oxide; It is done. Among these carriers, carbon and resin are preferable because of high microwave absorption, and carbon is particularly preferable.

  Specific examples of catalysts in which a metal is supported on a carbon support include Pd / C (palladium-supported carbon compound), Ru / C (ruthenium-supported carbon compound), Pt / C (platinum-supported carbon compound), and the like. .

  The catalyst may be granular or honeycomb-shaped. The catalyst particle diameter is preferably 75 μm to 5 mm, and if it exceeds 5 mm, handling becomes worse, and if it is less than 75 μm, clogging tends to occur when packed in a column or the like. More preferably, it is 150 μm to 3 mm.

  The catalyst to be subjected to the regeneration treatment is used when the organic chlorine compound is decomposed by allowing the mixed solution to flow through the catalyst filling device and contacting the catalyst. The timing of treating the catalyst can be grasped by the occurrence of clogging of the catalyst packing device (column), and the method of measuring the concentration of the organic chlorine compound in the reaction solution using a known organic chlorine compound analyzer such as GC-MS But I can understand.

  In the method of the present invention, the regeneration of the catalyst is performed as follows. That is, the liquid to be treated in the catalyst tank 4 is left at the bottom of the catalyst tank 4 while the liquid to be treated for the decomposition reaction of the organic chlorine compound such as PCB is left in the catalyst filling device 1. It discharges | emits from the exit 14, and also discharges | emits the to-be-processed liquid in the catalyst filling apparatus 1 from the discharge port 7 installed in the lower part of the catalyst filling apparatus to the last minute in which a catalyst is not exposed to a gaseous phase. Next, a solution in which an alkali metal hydroxide is dissolved in isopropyl alcohol is introduced into the catalyst filling device 1 through a line (not shown) and the pump 13. Thereafter, the introduced solution is circulated to the catalyst filling device 1 via the liquid reservoir in the catalyst tank 4 and the lines 11 and 12 and uniformly mixed with the liquid to be treated remaining in the catalyst filling device 1. The circulation time varies depending on the capacity of the catalyst filling device, but is usually about 10 to 30 minutes. Then, it heats by irradiating a microwave, and it implements by carrying out reduction processing while washing a catalyst.

  As the alkali metal hydroxide, NaOH or KOH is preferably used. If the alkali metal hydroxide is the same as that used in the decomposition treatment, the preparation of the alkali solution and the recovery operation of the by-product salt can be easily performed. Become.

  The amount of the alkali metal hydroxide is 0.1 to 0.3 w / v%, preferably 0.15 to 0.2 w / v% with respect to isopropyl alcohol. If the amount of the alkali metal hydroxide used is small, the catalyst regeneration efficiency decreases, which is not preferable. On the other hand, if the amount used is too large, the catalyst regeneration efficiency is no longer improved, which is uneconomical.

  Alkali metal hydroxide is used by dissolving in isopropyl alcohol. However, a solution in which alkali metal hydroxide is dissolved in isopropyl alcohol is prepared in advance, and the solution may be put into a liquid reservoir in a catalyst tank. Alternatively, alkali metal hydroxide and isopropyl alcohol may be added separately and stirred and dissolved in the liquid reservoir of the catalyst tank.

  When discharging the liquid to be treated from the catalyst filling device after decomposition of the organochlorine compound, the catalyst is dried by exposing the catalyst used for the decomposition reaction, and the inhibitor adhering to the catalyst surface is more firmly adsorbed. Since it is difficult to regenerate the catalyst, it is desirable to keep the liquid level of the liquid to be treated higher than the upper surface of the catalyst layer so that the catalyst is always in contact with the liquid. Moreover, when the catalyst surface is exposed, there is a risk that ignition or the like may occur due to microwave heating.

  In the present invention, by leaving the liquid to be treated in the catalyst filling device, it is possible to prevent the above-mentioned adverse effects and dangers due to the exposure of the catalyst, and further, as the catalyst is regenerated, the organic chlorine such as PCB again. Since the decomposition reaction of the compound proceeds, the PCB remaining in the liquid to be treated can be used as an index for grasping the regeneration state of the catalyst.

  The amount of the liquid to be treated left in the catalyst filling device 1 is sufficient if it is sufficient to immerse the catalyst layer, and if it is left too much, the regeneration efficiency of the catalyst may be lowered. Usually, during the decomposition reaction of PCB or the like, the amount of catalyst filled in the catalyst cartridge 2 is below the overflow port 6 so that the catalyst layer is sufficiently immersed in the liquid to be treated. When the catalyst regeneration process is performed, the inside of the catalyst filling device 1 is adjusted so that the liquid level of the liquid to be treated remaining in the catalyst filling device 1 becomes the uppermost surface of the catalyst layer. A part of the liquid to be treated should be discharged out of the system.

  The amount of isopropyl alcohol used for the regeneration of the catalyst is sufficient if it is 1 L or more with respect to 1 kg of the catalyst, and usually 1 to 10 L, preferably 2.5 to 6 L is used with respect to 1 kg of the catalyst. If the amount of isopropyl alcohol is too small, there may be a problem in circulating from the liquid in the catalyst tank to the catalyst filling device, and the cleaning effect of inorganic salts (KCl, etc.) adhering to the catalyst surface is insufficient. It becomes. On the other hand, if the amount is too large, the regeneration efficiency of the catalyst is no longer improved, which is uneconomical.

  The alkali metal hydroxide and isopropyl alcohol introduced into the liquid reservoir in the catalyst tank are circulated to the catalyst filling device and uniformly mixed with the liquid to be treated remaining in the catalyst filling device, and then the same as the decomposition treatment of the organic chlorine compound. In the method, the catalyst is regenerated by heating while circulating through the catalyst filling device. The circulation time varies depending on the capacity of the catalyst filling device and the degree of deterioration of the catalyst, but is usually about 10 to 30 hours. As the catalyst is regenerated, the undecomposed organochlorine compound contained in the mixture begins to decompose again, so the catalyst regeneration status should be tracked by measuring the change in the concentration of the organochlorine compound. Can do.

  That is, in the catalyst regeneration method of the present invention, the concentration of the organic chlorine compound in the mixed solution is used as an index as a criterion for determining the success or failure of the catalyst regeneration, and the organic chlorine compound concentration is the graduation reference value in the decomposition treatment. It is determined that the regeneration of the catalyst has been completed when it has dropped to 0.5 ppm or less.

  The heating temperature of the mixed solution in the catalyst regeneration treatment is preferably in the range of 30 to 60 ° C. The higher the heating temperature, the higher the amount of hydrogen generated and the higher the catalyst regeneration efficiency. On the other hand, the higher the heating temperature, the easier it is to generate dioxins due to decomposition of the remaining PCB.

  As a heating method, heating by microwave irradiation is preferable. By using microwaves, the catalyst can be heated effectively and the heating device can be made compact.

  The output of the microwave is preferably in the range of 10 W to 20 kW while being electrically controlled, and the frequency of the microwave is preferably 0.5 to 10 GHz.

  The microwave irradiation is performed continuously or intermittently while being electrically controlled according to the cooling state of the liquid mixture in the liquid reservoir of the catalyst tank, and the temperature of the liquid mixture flowing through the catalyst filling device is kept within a predetermined range. It is good to control.

  In the catalyst regeneration method of the present invention, an alkali metal hydroxide and a hydrogen donor are added to an insulating oil containing an organic chlorine compound such as PCB to form a mixed solution, and this mixed solution is placed in a catalyst tank filled with the above catalyst. In the method of decomposing an organochlorine compound through circulation, it can be particularly suitably applied as a method of regenerating a catalyst having a decreased activity when isopropyl alcohol is used as a hydrogen donor.

  When isopropyl alcohol is used as the hydrogen donor during the decomposition treatment of the organic chlorine compound, the same compound may be used as the alkali metal hydroxide and the hydrogen donor in the decomposition treatment of the organic chlorine compound and the catalyst regeneration treatment. Therefore, it is not necessary to remove the liquid remaining in the catalyst tank or the storage tank when the regeneration of the catalyst is finished. Insulating oil containing an organic chlorine compound is put into the storage tank and mixed, and this mixed liquid is mixed with the catalyst tank. It is possible to immediately restart the decomposition treatment of the organic chlorine compound.

  When decomposing organochlorine compounds following catalyst regeneration, add insulating oil containing organochlorine compounds and, if necessary, add additional alkali metal hydroxide and isopropyl alcohol. Is desirable.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited only to a following example. In the following experiments, the apparatus shown in FIG. 1 was used.

[Example 1]
(PCB decomposition test the first time)
A test liquid containing 9 L of PCB-containing insulating oil and by-product acetone, biphenyl and the like, 14 L of isopropyl alcohol and 150.7 g of KOH used in the actual machine were stirred to prepare a liquid to be treated. The PCB concentration in the liquid to be treated after the preparation was 1.6 ppm as a result of analysis by GC-MS (QP2010) manufactured by Shimadzu Corporation using DB5MS as a capillary column. The catalyst cartridge 2 is filled with 2 kg of Pd / C catalyst (5% palladium is supported on activated carbon having a particle size of 0.425 to 1.7 mm), and the prepared liquid to be treated is distributed to the catalyst filling device 1 at a rate of 800 ml / min. Then, the microwave was irradiated from the microwave device 8 and the temperature was maintained at 60 ° C. while being measured by the temperature sensor 9. The time-dependent change in the PCB concentration in the liquid to be treated was analyzed by using the GC-MS by taking a sample from the sampling valve 13. After starting the circulation and circulation of the liquid to be treated to the catalyst filling device 1, the PCB concentration dropped to 0.3 ppm in 12 hours and cleared the graduation standard value, so the circulation of the liquid to be treated and the microwave irradiation were stopped. Then, the PCB decomposition reaction was completed. After completion of the decomposition reaction, the liquid to be treated was extracted from the apparatus to such an extent that the catalyst was not exposed in the gas phase. The amount of the remaining liquid at this time was 8L.

(PCB decomposition test second time)
A test liquid containing 10.9 L of a test liquid containing PCB-containing insulating oil and by-product acetone, biphenyl, etc., 1.82 L of isopropyl alcohol, and 101.1 g of KOH used in the actual machine was prepared to prepare the liquid to be processed. Then, it was circulated for 30 minutes while being circulated through the catalyst filling device 1. The PCB concentration at this point was measured and found to be 10.8 ppm. As a result of starting PCB irradiation while maintaining the temperature at 60 ° C., the catalyst filling apparatus 1 was subjected to a PCB decomposition reaction. As a result, the PCB concentration after 15 hours was 8.2 ppm, so the catalytic activity was significantly reduced. The reaction was stopped.

(First catalyst regeneration process)
The regeneration treatment was carried out using the catalyst having the above-mentioned reduced activity. First, after completion of the above PCB decomposition test, the liquid to be treated remaining in the liquid reservoir of the catalyst tank 4 was discharged from the discharge port 14. Next, the liquid to be treated in the catalyst filling device 1 was extracted to such an extent that the catalyst was not exposed in the gas phase. The liquid remaining in the catalyst filling device 1 was 8 L.
A solution obtained by dissolving 20 g of KOH in 10.6 L of isopropyl alcohol is added to the liquid reservoir in the catalyst tank 4, and the mixture is circulated for 30 minutes while being circulated through the catalyst filling device 1. The KOH in isopropyl alcohol was mixed uniformly. The PCB concentration in this mixed solution was 1.6 ppm.
Microwave irradiation was started while circulating the mixed liquid through the catalyst filling device, and the catalyst was regenerated while maintaining the temperature at 60 ° C. The regeneration state of the catalyst was followed by analyzing the change in the PCB concentration in the mixed solution by the GC-MS.
5 hours after the start of regeneration, the PCB concentration in the mixed solution began to decrease, and after 19 hours it decreased to 0.4 ppm. Since the graduation criteria in the decomposition treatment were cleared, it was judged that the regeneration of the catalyst was completed, Distribution and microwave irradiation were stopped, and the regeneration process of the catalyst was completed.

(First PCB decomposition test with regenerated catalyst)
After completion of the first regeneration treatment of the catalyst, 5.1 L of a test solution (PCB concentration 6.1 ppm) containing PCB-containing insulating oil and by-product acetone, biphenyl, etc. used in the actual apparatus in the catalyst filling device 1 and isopropyl alcohol Add 0.5 L and 50.5 g of KOH, circulate for 30 minutes while circulating in the catalyst filling device 1, and evenly with the liquid remaining in the device after the catalyst regeneration process (catalyst filling device and catalyst reservoir). Mixed. The PCB concentration in this mixed solution was 1.4 ppm.
Microwave irradiation was started while circulating the mixed liquid through the catalyst filling device 1, and the temperature was kept at 60 ° C., and the PCB decomposition reaction was performed. After 44 hours, the PCB concentration dropped to 0.3 ppm and graduated. Since the standard was cleared, the flow of the mixed solution and the microwave irradiation were stopped, and the PCB decomposition reaction was completed.

(PCB decomposition test with regenerated catalyst second time)
After the first PCB decomposition test with the regenerated catalyst is completed, 0.35 L of a test solution (PCB concentration 406 ppm) containing PCB-containing insulating oil and by-product acetone, biphenyl, etc. used in the actual machine is introduced into the catalyst filling device 1. The mixture was circulated for 30 minutes while being circulated through the catalyst filling device 1 and uniformly mixed with the liquid remaining in the device (catalyst filling device and catalyst layer liquid reservoir). The PCB concentration in this mixed solution was 8.9 ppm.
Microwave irradiation was started while circulating the mixed liquid through the catalyst filling device 1 and the temperature was kept at 60 ° C., and PCB decomposition reaction was carried out. In 40 hours, the PCB concentration dropped to 0.4 ppm and graduated. Since the standards were cleared, the mixture flow and microwave irradiation were stopped, and the decomposition reaction was completed.

(3rd PCB decomposition test with regenerated catalyst)
After the second PCB decomposition test using the regenerated catalyst is completed, 0.25 L of a test solution containing PCB-containing insulating oil and by-product acetone, biphenyl, etc. (PCB concentration 406 ppm) used in the actual machine is subsequently supplied to the catalyst filling device 1. Then, the PCB was decomposed in the same manner as in the second PCB decomposition test using the regenerated catalyst. The PCB concentration at the start of decomposition was 7.8 ppm, but the PCB concentration dropped to 0.3 ppm in 42 hours, and cleared the graduation standard.

(4th PCB decomposition test with regenerated catalyst)
After completion of the third PCB decomposition test using the regenerated catalyst, 0.25 L of a test solution (PCB concentration: 406 ppm) containing PCB-containing insulating oil and by-product acetone, biphenyl, etc. used in the actual machine was subsequently applied to the catalyst filling device 1. Then, the PCB was decomposed in the same manner as in the second PCB decomposition test using the regenerated catalyst.
The PCB concentration at the start of decomposition was 6.0 ppm, and the PCB concentration dropped to 0.3 ppm at 83 hours, which cleared the graduation standard. However, compared with the 1st to 3rd PCB decomposition tests using the regenerated catalyst, the time required for the PCB concentration to decrease was approximately doubled, indicating that the activity of the catalyst was reduced.

  The relationship between the decomposition time and the PCB concentration change in the above decomposition test is shown in FIG. FIG. 2 shows that by regenerating the catalyst by the method of the present invention, the catalyst can be decomposed in a short time without removing the catalyst from the apparatus.

[Example 2]
(Second catalyst regeneration process)
Regeneration treatment was performed on the catalyst whose activity decreased in the fourth PCB decomposition test using the regenerated catalyst. First, after the fourth PCB decomposition test using the regenerated catalyst is completed, the liquid to be processed remaining in the liquid reservoir of the catalyst tank 4 is discharged from the discharge port 14, and then the liquid to be processed in the catalyst filling device 1 is taken out. The liquid level was adjusted to be the uppermost surface of the catalyst layer 3.
A solution in which 21.42 g of KOH was dissolved in 10 L of isopropyl alcohol was added to the liquid reservoir in the catalyst tank 4 and circulated for 30 minutes while being circulated through the catalyst filling device 1, and the liquid to be treated remaining in the catalyst filling device 1 was newly added. An isopropyl alcohol solution of KOH was mixed uniformly. The PCB concentration in this mixed solution was 0.1 pm.
Microwave irradiation was started while circulating the mixed solution through the catalyst filling device 1, and catalyst regeneration was performed while maintaining the temperature at 60 ° C. After the regeneration starts, the PCB concentration gradually increases, increases to 0.4 ppm after 4 hours, starts to decrease, and when the PCB concentration decreases to less than 0.1 ppm 30 hours after the regeneration starts, the catalyst regeneration treatment Ended.

(5th PCB decomposition test with regenerated catalyst)
After the second regeneration of the catalyst, the test solution containing PCB-containing insulating oil and by-product acetone, biphenyl, etc. (PCB concentration 406 ppm) used in the actual machine was introduced into the catalyst filling device 1 to regenerate the catalyst. The PCB decomposition reaction was carried out in the same manner as in the second PCB decomposition test. The PCB concentration at the start of decomposition was 7.5 ppm, but after 14 hours the PCB concentration dropped to 0.2 ppm, which cleared the graduation standard.

  As shown in the above examples, it can be seen that the catalyst is effectively regenerated by heating the catalyst having decreased activity using a solution of alkali metal hydroxide such as KOH and isopropyl alcohol. Further, from Example 2, even if the activity of the catalyst is reduced during the PCB decomposition treatment, the catalyst activity is restored by heating using a solution of an alkali metal hydroxide such as KOH and isopropyl alcohol, It can be seen that the PCB decomposition process can be continued.

  According to the catalyst regeneration method of the present invention, it is possible to regenerate a catalyst whose activity has been reduced by using it in a decomposition reaction of an organic chlorine compound such as PCB without taking it out of the apparatus. Since the product and isopropyl alcohol are used, after the regeneration of the catalyst is completed, the decomposition reaction of the organic chlorine compound contained in the insulating oil or the like can be subsequently carried out, so that the decomposition treatment cost of various PCBs and dioxins can be reduced, and the organic It becomes possible to treat insulating oil containing a chlorine compound efficiently and economically.

DESCRIPTION OF SYMBOLS 1 Catalyst filling apparatus 2 Catalyst cartridge 3 Catalyst 4 Catalyst tank 5 Structure 6 Overflow port 7 Discharge port 8 Microwave apparatus 9 Temperature sensor 10 Cooling coil 11, 12 Line 13 Pump 14 Discharge port 15 Sampling valve 16 Temperature controller

Claims (8)

Distribute the mixed solution of insulating oil, alkali metal hydroxide and isopropyl alcohol containing organochlorine compound to a catalyst filling device filled with a catalyst with a noble metal supported on the carrier, and contact the catalyst to decompose the organochlorine compound. In the disassembly process to
A method for regenerating a catalyst that makes it possible to reuse a catalyst with reduced resolution,
In a state where the catalyst filling device is filled without removing the catalyst having reduced resolution, heating is performed while circulating an alkali metal hydroxide and isopropyl alcohol through the catalyst filling device, and the catalyst is reduced using isopropyl alcohol as a hydrogen donor. A method for regenerating a catalyst.   The method for regenerating a catalyst according to claim 1, wherein the amount of isopropyl alcohol used is 1 to 10 L per kg of the catalyst.   The method for regenerating a catalyst according to claim 1 or 2, wherein the amount of the alkali metal hydroxide used is 0.1 to 0.3 w / v% with respect to isopropyl alcohol.   The method for regenerating a catalyst according to any one of claims 1 to 3, wherein the heating temperature is 30 to 60 ° C.   The method for regenerating a catalyst according to any one of claims 1 to 4, wherein the heating is microwave heating.   The method for regenerating a catalyst according to any one of claims 1 to 5, wherein the noble metal is palladium.   The method for regenerating a catalyst according to any one of claims 1 to 6, wherein the support is selected from the group consisting of carbon, a resin, and combinations thereof. The method for regenerating a catalyst according to any one of claims 1 to 7, wherein the organic chlorine compound is an organic chlorine compound selected from the group consisting of PCBs, dioxins, aromatic chlorine compounds, and mixtures of two or more thereof. .

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