JP5305165B2 - Method for producing purified hydrogen peroxide water - Google Patents

Description

  The present invention relates to a method for producing purified hydrogen peroxide solution, and more specifically, high purity capable of reproducibly removing hydrophobic substances contained in hydrogen peroxide solution, that is, hydrophobic organic substances and hydrophobic colloidal metal compounds. The present invention relates to a method for producing hydrogen peroxide water and an apparatus for producing purified hydrogen peroxide water therefor.

  Hydrogen peroxide solution is widely used in many fields such as paper, pulp bleaching, chemical polishing liquid, etc., but in recent years, its use in the electronics industry such as silicon wafer cleaning agents and semiconductor process cleaning agents has increased. In connection with this, high-purity quality in which various impurities in hydrogen peroxide water are reduced as much as possible is required.

  In general, hydrogen peroxide is currently produced mainly by the anthraquinone method. The production method is as follows. First, an anthraquinone derivative such as 2-alkylanthraquinone is hydrogenated in the presence of a hydrogenation catalyst in a water-insoluble solvent to form anthrahydroquinone, and after removing the catalyst, it is oxidized by air. -This is a method for regenerating alkyl anthraquinone and extracting the hydrogen peroxide produced at this time with water to obtain a hydrogen peroxide-containing aqueous solution. This method is called anthraquinone auto-oxidation method (AO method).

  The hydrogen peroxide water produced by this method contains organic impurities caused by the production method in addition to inorganic ions and compound impurities such as Al, Fe, and Cr caused by the material of the apparatus. For this reason, the operation of purifying the hydrogen peroxide solution to a higher purity by removing these impurities according to the quality requirements to be used.

  Several technologies for purifying hydrogen peroxide water with high purity have already been put into practical use, but the most excellent and inexpensive one is the ion exchange resin method, which will be widely used in the future. Expected.

  However, this ion exchange resin method is extremely vulnerable to contamination. Therefore, the performance deterioration of ion exchange resin and the shortening of life are often seen. Therefore, in order to maximize the capability of the ion exchange resin, it is necessary to remove the contaminant impurities that cause damage to the ion exchange resin in a step before the treatment with the ion exchange resin. This can also contribute to the final wafer cleaning.

  Contaminating impurities contained in hydrogen peroxide water and contaminating the ion exchange resin are hydrophobic substances, that is, hydrophobic organic substances and hydrophobic colloidal metal compounds. Hydrophobic organic substances and hydrophobic colloidal metal compounds in hydrogen peroxide water are very easy to adsorb, and gradually adsorb on the ion exchange resin, blocking the ion exchange groups and hindering the exchange capacity of the ion exchange resin. In addition, the life of the ion exchange resin is shortened, which is a cause of deterioration of the ion exchange resin. In cleaning semiconductor wafers, hydrophobic substances are easily adsorbed on the wafer surface, and organic substances adhering to the wafer surface cause degradation of oxide breakdown voltage due to crystal defects, increase in leakage current, degradation of dielectric breakdown voltage of silicon oxide film, etc. It is also a cause of causing.

  Therefore, it is required to reduce the hydrophobic substance that adheres to the wafer surface even in the hydrogen peroxide solution. It should be noted that a hydrophilic substance has a lower adsorptivity than a hydrophobic substance and can be washed away with ultrapure water rinse, so that it does not remain on the wafer.

There are roughly two types of hydrophobic substances in hydrogen peroxide water, one is a hydrophobic organic substance, and the other is a colloidal metal compound.
Among hydrophobic substances in hydrogen peroxide water, as a method for removing hydrophobic organic substances, a method of treating with a synthetic adsorbent or a method of treating with a reverse osmosis membrane (RO membrane) has been proposed (Patent Documents 1 to 8). In addition, it has also been proposed to physically adsorb organic substances on the surface of the adsorbing resin with a van der Waals force (Patent Documents 9 to 11). In addition, an adsorbent that uses activated carbon (Patent Document 12) or zeolite (Patent Document 13) has also been proposed.

  Further, as a pretreatment for purifying the hydrogen peroxide solution, the low molecular organic substances remaining after the organic substances are oxidatively decomposed by causing ozone to act on the industrial hydrogen peroxide solution are distilled and removed. Has been proposed.

  In addition, when air or inert gas is blown into the hydrogen peroxide solution containing organic impurities from below, the bubbles that rise will cause the organic matter to adhere and rise, and hydrogen peroxide with reduced organic matter can be taken out from below, thereby removing the hydrogen peroxide solution. It is also known to purify (Patent Document 16). Furthermore, a method of distilling industrial hydrogen peroxide using a vacuum distillation apparatus composed of Teflon (registered trademark) members has also been proposed (Patent Document 17).

  Furthermore, Patent Document 18 discloses that organic substances in industrial hydrogen peroxide water can be reduced by extraction with supercritical carbon dioxide, and Patent Document 18 discloses that TOC is reduced from 145 ppm to 80 ppm.

  There is no prior art for removing colloidal metal compounds, which are another hydrophobic substance of hydrogen peroxide.

Patent No. 2976776 Patent No. 3265929 Japanese Unexamined Patent Publication No. 7-33408 Patent No. 3978546 JP 2000-302418 A Japanese Patent Laid-Open No. 2003-1070 Patent No. 3226256 JP-A-10-330102 JP 2000-203812 JP Patent No. 2570308 Japanese Patent Laid-Open No. 10-114507 Special Table 2003-535007 Publication Japanese Patent Laid-Open No. 11-35305 JP-A-9-71404 JP-A-9-71405 Japanese Patent Laid-Open No. 9-100106 JP-A-8-231208 Japanese Patent Laid-Open No. 8-104503

  In the RO membranes of Patent Documents 1 to 8, inorganic substances and organic substances are captured and deposited on the film surface. Since the surface is extruded at a high pressure of 1 to several MPa, the deposits laminated on the film surface permeate little by little. For this reason, the amount of inorganic substances and organic substances in the hydrogen peroxide solution that has passed through the RO membrane gradually increases with time. In the method using the adsorptive resin of Patent Documents 9 to 11, the activated carbon of Patent Document 12, and the zeolite of Patent Document 13, most of the organic substances are physically adsorbed by the van der Waals force on the surface, but the adsorptive power is weak. On the surface, the adsorption and desorption of organic substances are constantly repeated, so that they cannot be removed sufficiently. In addition, the amount of organic matter in the treated hydrogen peroxide water increases with time.

  As in Patent Documents 14 and 15, when organic substances are oxidized with ozone to reduce the molecular weight and removed by adsorption or ion exchange, ozone is decomposed by hydrogen peroxide in hydrogen peroxide water, and the organic substances are sufficiently oxidized. This reaction is unlikely to occur.

In the treatments of Patent Documents 16 and 17, a large amount of organic substances azeotroped with hydrogen peroxide cannot be reduced so much, and it is difficult and impractical to make a decompression section with a Teflon (registered trademark) member.
The method described in Patent Document 18 focuses on removing the entire organic matter, but this extraction method is inefficient. Japanese Patent Application Laid-Open No. 2004-67402 discloses that hydrogen peroxide water is treated with a porous ceramic filter having an average pore diameter of 5 μm or less as a pre-stage of the treatment of the ion exchange resin. There is no description about the removal of a certain colloidal metal compound, and even if an attempt is made to remove a hydrophobic substance by such a method, the blocking rate of the film is low, and the leak increases at an early time.

  As a result of intensive studies on removing hydrophobic substances from hydrogen peroxide water, the present inventors have found the following views. That is, the hydrophobic substance contained in the hydrogen peroxide solution adheres to the ion exchange groups of the ion exchange resin, shortening the purification failure and life of the hydrogen peroxide solution, or adhering to the wafer surface in wafer cleaning. It has been found that the wafer has poor characteristics.

  In the methods disclosed in the patent documents so far, there is a risk that a part of the hydrophobic substance leaks, and further, the ion exchange resin also passes through and enters the final high-purity hydrogen peroxide solution. In addition, the synthetic adsorption resin imposes a burden on the environment by using a large amount of organic solvent in the regeneration. In RO membranes, contamination of organic matter, etc., clogs the pores of the membrane, making it impossible to remove the organic matter, which places a burden on the environment, such as having to replace expensive polymer membranes frequently. As described above, both have problems.

Under such circumstances, the present inventors have found that a hydrophobic substance in hydrogen peroxide water is removed as a pretreatment for the purification treatment of the ion exchange resin.
Conventionally, removal of organic substances has been studied. However, organic substances having a large influence on wafer cleaning and the like are hydrophobic organic substances having a large molecular weight. In addition to such hydrophobic organic substances, the influence of hydrophobic metal colloids derived from alumina and aluminum hydroxide is also great, and the idea of removing both of these has not been found in the prior art.

  As a pretreatment of such an ion exchange treatment, the present inventors contact a hydrophobic substance contained in hydrogen peroxide with liquid, subcritical or supercritical carbon dioxide, or filter it with a ceramic membrane. I thought about processing.

  Liquid, subcritical or supercritical carbon dioxide acts as a solvent for dissolving the hydrophobic organic substance, and can efficiently remove only the hydrophobic organic substance. As a result, the liquid, subcritical or supercritical carbon dioxide method always extracts only the hydrophobic organic substance, and it is possible to obtain hydrogen peroxide solution from which only the hydrophobic organic substance is removed regardless of the passage of time. I found it.

  In addition, by adding a chelating agent to the hydrogen peroxide solution and filtering through a ceramic membrane to remove the colloidal metal compound that is a hydrophobic substance, a hydrogen peroxide solution that solves all of the above problems can be obtained. I found out that

  By removing both of these hydrophobic organic substances and colloidal metal compounds, it has been difficult to remove continuously, and the hydrophobic substances in the raw hydrogen peroxide solution have been problematic in terms of purification efficiency and environment. It was found that all of these can be removed.

  By combining hydrogen peroxide water, from which both hydrophobic organic substances and colloidal metal compounds have been removed as a pretreatment, with the ion exchange resin treatment, the life of the ion exchange resin is extended, making it more efficient than before. In addition, the inventors have found that metal impurities and the like can be stably removed for a long period of time, and have completed the present invention.

The configuration of the present invention is as follows.
[1] In a method for purifying a raw material hydrogen peroxide solution containing a hydrophobic substance as an impurity using a purification tower packed with an ion exchange resin,
As a pretreatment for the purification process,
(I) Contact with a liquid, subcritical or supercritical carbon dioxide fluid to dissolve and extract hydrophobic organic substances in carbon dioxide, and remove hydrophobic organic substances from the hydrophobic substances contained in hydrogen peroxide water To produce purified hydrogen peroxide solution.
[2] In a method of purifying a raw material hydrogen peroxide solution containing a hydrophobic substance as an impurity using a purification tower packed with an ion exchange resin,
As a pretreatment for the purification process,
(Ii) A method for producing purified hydrogen peroxide solution in which a chelating agent is added to hydrogen peroxide solution and filtered through a ceramic filter to remove a hydrophobic colloidal metal compound from hydrophobic substances contained in the hydrogen peroxide solution. .
[3] In a method of purifying a raw material hydrogen peroxide solution containing a hydrophobic substance as an impurity using a purification tower packed with an ion exchange resin,
As a pretreatment for the purification process,
(I) Contact with a liquid, subcritical or supercritical carbon dioxide fluid to dissolve and extract hydrophobic organic substances in carbon dioxide, and remove hydrophobic organic substances from the hydrophobic substances contained in hydrogen peroxide water And
(Ii) Purifying peroxidation characterized by adding a chelating agent to hydrogen peroxide solution and filtering with a ceramic filter to remove hydrophobic colloidal metal compounds from hydrophobic substances contained in hydrogen peroxide solution A method for producing hydrogen water.
[4] The purified hydrogen peroxide solution according to any one of [1] to [3], wherein impurities obtained in the hydrogen peroxide solution are further removed from the obtained hydrogen peroxide solution by a cation ion exchange resin and / or an anion ion exchange resin. A method for producing hydrogen water.
[5] Purified peroxidation that purifies hydrogen peroxide solution using a purification tower filled with cation ion exchange resin and / or anion ion exchange resin as raw material hydrogen peroxide solution containing hydrophobic substance A hydrogen water purifier,
As pre-processing means,
(i) together with means for heating and pressurizing carbon dioxide,
(ii) an extraction means for mixing the carbon dioxide fluid and hydrogen peroxide solution to extract the hydrophobic organic impurities into the carbon dioxide fluid; (iii) from the carbon dioxide fluid, converting the carbon dioxide into a gas and removing the hydrophobic organic impurities. Hydrophobic organic substance removing means comprising gas-liquid separating means for separation, and / or
A refining apparatus comprising a colloidal metal compound removing means for adding a chelating agent to a raw material hydrogen peroxide solution and filtering it with a ceramic filter.

  If a hydrophobic substance is contained in the hydrogen peroxide solution that comes into contact with the ion exchange resin to remove inorganic ions and compound impurities, the hydrophobic substance gradually chemisorbs on the ion exchange resin, and the ions of the ion exchange resin It clogs the exchange base, impedes the exchange capacity of the ion exchange resin, shortens the life of the ion exchange resin, and causes deterioration of the ion exchange resin. In addition, hydrophobic substances are easily adsorbed even in the cleaning of semiconductor wafers, which causes the breakdown voltage of the silicon oxide film to deteriorate.

  According to the present invention, these problems are solved, and the life of the ion exchange resin can be maintained for a long time without impairing the ion exchange ability of the ion exchange resin for removing inorganic ions and compound impurities. In addition, hydrogen peroxide solution without a hydrophobic substance can contribute to the reduction of defects in semiconductor cleaning wafer characteristics. Furthermore, the present invention is also an environmentally friendly technology that does not generate a regenerated solvent for adsorbent regeneration and can reduce the disposal of ion exchange resin.

FIG. 1 is a flowchart showing one embodiment of the pretreatment of the purification apparatus according to the present invention. FIG. 2 is a flowchart showing one embodiment of the pretreatment of the purification apparatus according to the present invention.

  Hereinafter, the method for producing purified hydrogen peroxide solution according to the present invention will be described in detail. In the present specification, ppm, ppb and ppt all indicate ppm by weight, weight ppb and weight ppt.

[Production method of purified hydrogen peroxide]
Raw material hydrogen peroxide solution As the raw material hydrogen peroxide solution used in the present invention, one produced by a known production method such as an anthraquinone auto-oxidation method or a direct synthesis method in which hydrogen and oxygen are directly reacted is used. Usually, the hydrogen peroxide concentration in the raw hydrogen peroxide solution is not particularly limited as long as it is 70% or less. Usually, since the stabilizer is already added to the raw hydrogen peroxide solution, no additional additive is particularly required.

  This hydrogen peroxide solution usually contains a hydrophobic substance as an impurity in the order of several ppb to several tens of ppm. This hydrophobic substance is derived, for example, from organic components, catalysts, organic solvents, water, air, or other organic components used during production (extraction, distillation, dilution), or production equipment materials.

  Examples of such hydrophobic impurities include hydrophobic organic substances and hydrophobic colloidal metal compounds. Examples of hydrophobic organic substances include aromatic hydrocarbons and derivatives containing the hydrophobic groups, anthraquinone derivatives, cyclohexane derivatives, and aromatic naphtha. Carboxylic acid esters and the like. These are relatively high polymers. Examples of the hydrophobic colloidal metal compound include colloids such as metals such as aluminum, iron, calcium, magnesium, tin, zinc, nickel, chromium, lead, and silicon, and their hydroxides and oxides. Note that low-molecular organic substances are usually hydrophilic and rarely cause problems in ion exchange resin processing and wafer cleaning.

In the purification method according to the present invention,
As the pretreatment (i), the raw hydrogen peroxide solution is brought into contact with a liquid, subcritical or supercritical carbon dioxide fluid to dissolve and extract the hydrophobic organic substance in carbon dioxide, or pretreatment ( As ii), a chelating agent is added to the hydrogen peroxide solution and filtered through a ceramic filter to remove the hydrophobic colloidal metal compound among the hydrophobic substances contained in the hydrogen peroxide solution.

[Pretreatment (i)]
Carbon dioxide fluid In the present invention, liquid, subcritical or supercritical carbon dioxide is used as the carbon dioxide fluid. Supercritical carbon dioxide is obtained at a temperature of 31.17 ° C. or higher and a pressure of 7.386 MPa or higher. The density of this supercritical fluid is close to that of a liquid, the diffusion coefficient is significantly higher than that of a liquid, and has the effect of dissolving nonpolar, weakly polar oils and fats, and the dissolving power changes by changing temperature and / or pressure.
Carbon dioxide can be vaporized, removed, liquefied and reused only under pressure conditions, and it is possible to easily construct these circulation processes.

Removal of hydrophobic organic substances The organic matter solubility of carbon dioxide varies depending on the extraction conditions, but practically preferred operating conditions from the viewpoint of safety, device design, and economy are a temperature of 10 to 50 ° C. and a pressure of 30 MPa or less, Excessive high temperature and high pressure conditions are not preferred. In performing the extraction operation, the density of carbon dioxide is suitably 800 to 900 kg / m ^3. For example, in the case of a supercritical carbon dioxide fluid having a temperature of 35 ° C., this condition can be achieved at 14 MPa to 30 MPa.

  The extraction efficiency depends on the mixing method of carbon dioxide and hydrogen peroxide solution, the residence time in the mixed state, and the mixing ratio of hydrogen peroxide solution and carbon dioxide. As the mixing method, high-pressure micromixer, two-component mixing mixer, turbulent mixing, and contraction mixing with good mixing efficiency are effective so that the wetted area of hydrogen peroxide solution and carbon dioxide is increased. In the present invention, organic substances contained in the hydrogen peroxide solution are extracted and removed by supplying an excess of carbon dioxide that exceeds the amount of carbon dioxide that is saturated and dissolved in the hydrogen peroxide solution.

  Usually, carbon dioxide and hydrogen peroxide other than carbon dioxide that is dissolved in saturation are separated immediately after mixing. Therefore, in order to avoid separation of organic substances in carbon dioxide without completely dissolving, in the present invention, it is desirable to provide a two-liquid mixed retention area so that the two liquids can remain mixed after mixing.

Specifically, a swirl mixer, a static mixer, a turbulent mixing mixer, a multistage reduced flow mixer, and the like are installed.
In the purification method according to the present invention, carbon dioxide having a saturation solubility or higher with respect to the hydrogen peroxide solution supply amount may be supplied. Although the amount of extraction increases by supplying an excess amount of carbon dioxide, increasing the amount of carbon dioxide used and increasing the amount of circulation increase the running cost, so supplying a large excess amount of carbon dioxide from an economic point of view Practically, a carbon dioxide supply amount that is about the same as the hydrogen peroxide solution supply amount to about four times is preferable.

  The mixing device for mixing the hydrogen peroxide solution and carbon dioxide is a swirl mixer, a static mixer, a turbulent mixing mixer, a multistage reduced flow mixer, or the like. The hydrogen peroxide solution and carbon dioxide are kept in contact for a long time so that the organic matter in the hydrogen peroxide solution can be dissolved in the carbon dioxide.

Next, hydrogen peroxide solution and carbon dioxide are separated from the mixed solution. Carbon dioxide and hydrogen peroxide after extraction of organic substances in hydrogen peroxide water are separated by the difference in specific gravity of each solvent. Usually, the density of carbon dioxide 800~900kg / m ^3, the density of the hydrogen peroxide solution is 35~60% 1120~1250 kg / m ^3, carbon dioxide top layer, the hydrogen peroxide water is separated from the lower layer.

  The separated carbon dioxide is depressurized by a back pressure valve and separated into gaseous carbon dioxide and an organic liquid (hydrophobic organic substance extracted from hydrogen peroxide solution) by a separation tank. The separated gaseous carbon dioxide is cooled in a condenser, liquefied, and recycled again. The separated extract is discharged out of the system from the separation tank.

On the other hand, the hydrogen peroxide solution separated by the specific gravity difference separation passes through the back pressure valve and the deaeration device, and after degassing CO ₂ , is recovered in the hydrogen peroxide solution recovery tank. As the degassing device, hollow fiber membrane degassing or the like is effective in which hydrogen peroxide solution is passed through the inside of the hollow fiber, the outside is decompressed, and dissolved gas is discharged.
The entire device is made of a pressure resistant material. The material that comes into contact with the hydrogen peroxide solution is preferably a Teflon (registered trademark) lining as much as possible.
In the present invention, as pretreatment (ii), a chelating agent is added to the raw hydrogen peroxide solution, and the mixture is filtered through a ceramic filter to remove the hydrophobic colloidal metal compound (colloid).

[Pretreatment (ii)]
Removal of Hydrophobic Colloidal Metal Compound In the present invention, a chelating agent is added in advance to the raw material hydrogen peroxide solution, and ultrafiltration is performed with a ceramic filter to remove the hydrophobic colloidal metal compound (colloid).

The hydrogen peroxide concentration in the hydrogen peroxide water used is not particularly limited as long as it is 70% by weight or less. If the concentration is too high, the durability of the filter or device may be reduced.
The chelating agent preferably has a high molecular weight, and is added in order to block the colloid in its molecular structure and increase the molecular weight of the colloid so that it does not physically pass through the filtration membrane. The high molecular weight chelating agent added to the hydrogen peroxide solution takes in the colloid and does not pass through the ceramic filter of 20 nm or less.

  As the chelating agent, a phosphorus compound is usually used. Examples of phosphorus compounds include aminotri (methylenephosphonic acid) and salts thereof, 1-hydroxyethylidene-1,1-diphosphone and salts thereof, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and salts thereof, nitrilomethylene At least one phosphorus selected from the group consisting of phosphonic acid and its salt, 1,2-propylenediaminetetra (methylenephosphonic acid) and its salt, metaphosphoric acid and its salt, polyphosphoric acid and its salt, pyrophosphoric acid and its salt, etc. System compounds are preferably used. Of these, those having a molecular weight of several thousands to one million are most preferably used.

  Most of the colloids in hydrogen peroxide water are Al colloids. It is desirable to add such a phosphorus compound in an amount of 15 to 30 times (as P), preferably 18 to 25 times the amount of Al colloid in the hydrogen peroxide solution.

  Hydrogen peroxide containing colloid blocked with this chelating agent is ultrafiltered with a ceramic filter. As the filter, a known porous ceramic filter made of an inorganic material such as alumina, zirconium oxide or titanium oxide can be used. The pore diameter is 20 nm or less, preferably 20 to 4 nm or less. As a filtration method, it is desirable to use a hollow type porous ceramic filter and use a cross flow method (flowing liquid parallel to the inner surface of the membrane and filtering with the flow pressure). When the cross flow is used, the colloid deposited in a filter is filtered while being washed away with the liquid, so that the permeation filtration flow rate can be maintained for a long time.

The filter filtration pressure ((inlet pressure + outlet pressure) / 2) is 0.2 MPa or less, preferably 0.16 MPa or less. With this filtration pressure, the colloid can be efficiently filtered.
When the hydrogen peroxide solution added with the chelating agent is ultrafiltered with a ceramic filter, 99% of colloidal impurities in the hydrogen peroxide solution can be removed. Since the colloid concentrates in the concentration tank, the colloid removal from the raw hydrogen peroxide solution can be efficiently performed by removing and using the colloid-rich hydrogen peroxide solution periodically.

In the present invention, either the pretreatment (i) or (ii) is performed. Further, the pretreatments (i) and (ii) may be combined. The order of these pretreatments (i) and (ii) is not particularly limited.
In the present invention, the hydrogen peroxide solution purified by the pretreatment as described above is brought into contact with the ion exchange resin to remove impurities such as inorganic ions.

Usually, the hydrogen peroxide solution is further purified by passing through a single bed or mixed bed ion exchange resin tower.
The ion exchange resin is generally recyclable, and a cation ion exchange resin or an anion ion exchange resin is used. The cation ion exchange resin is used as an H ⁺ type cation exchange resin, and the anion ion exchange resin is used as an F ⁻ type anion exchange resin, an HCO ₃ ⁻ type anion exchange resin, or a CO ₃ ²⁻ type anion exchange resin.

As the ion exchange treatment, an ion exchange resin described in Japanese Patent No. 3895540 may be combined.
The hydrogen peroxide solution after the pretreatment is brought into contact with an H ⁺ type cation exchange resin, and then brought into contact with a carbonate ion (CO ₃ ²⁻ ) type or hydrogen carbonate ion (HCO ₃ ⁻ ) type anion exchange resin, Contact with H ⁺ type cation exchange resin. Alternatively, the hydrogen peroxide solution after the pretreatment is brought into contact with an H ⁺ type cation exchange resin, then brought into contact with a fluoride ion (F ⁻ ) type anion exchange resin, and then carbonate ion (CO ₃ ²⁻ ) type. Alternatively, it is brought into contact with a bicarbonate ion (HCO ₃ ⁻ ) type anion exchange resin, and further brought into contact with an H ⁺ type cation exchange resin.

  As a pretreatment means for removing the hydrophobic substance contained in the raw material hydrogen peroxide solution as an impurity in this way, after removing the hydrophobic organic substance in the raw material hydrogen peroxide solution using a carbon dioxide fluid, the ceramic film is further removed. Hydrogen peroxide water from which hydrophobic colloidal metal compounds have been removed by filtration with a high-purity peroxidation from which metal ion impurities, etc. have been removed as much as possible by treating with a subsequent 3-stage or 4-stage ion exchange resin Hydrogen water can be produced stably. In addition, the ion exchange capacity and life of the ion exchange resin can be extended longer than before.

[Hydrogen peroxide water purification equipment]
In the method for purifying hydrogen peroxide solution according to the present invention, as a pretreatment means,
(1) Means for dissolving and removing hydrophobic organic substances in hydrogen peroxide water using subcritical or supercritical carbon dioxide and / or liquid carbon dioxide as a separation solvent, and / or
(2) A means for removing a colloidal metal compound in hydrogen peroxide solution by adding a chelating agent to the hydrogen peroxide solution and filtering with a ceramic filter is provided.

Pretreatment means (1)
Pre-processing means (1)
(i) means for heating and pressurizing carbon dioxide,
(ii) an extraction means for mixing a carbon dioxide fluid and hydrogen peroxide water to extract hydrophobic organic impurities into the carbon dioxide fluid;
(iii) Hydrophobic organic substance removing means comprising gas-liquid separating means for separating carbon dioxide from a carbon dioxide fluid into gas and separating hydrophobic organic impurities.

FIG. 1 is a flowchart showing an example of this embodiment.
In the hydrophobic organic substance removing apparatus used in the present invention, the mixing unit 8 includes a carbon dioxide supply line, a raw material hydrogen peroxide supply line, and a two-part mixing unit 8, and the mixed solution is provided below the mixing unit 8. The specific gravity difference separation tank 9 that separates the hydrogen peroxide, the hydrogen peroxide recovery tank 12 that collects the hydrogen peroxide solution separated from the bottom of the specific gravity difference separation tank 9, and the raw material hydrogen peroxide from the specific gravity difference separation tank 9 A carbon dioxide recovery line is provided for recovering carbon dioxide containing organic matter extracted from.

  The carbon dioxide recovery line cools and stores the gaseous carbon dioxide separated and recovered from the separator I23 and the separator II24 by the condenser 3 and the liquid carbon dioxide replenished from the replenishing liquefied carbon dioxide cylinder 1 by the cooling device 2. Furthermore, the condenser 3 is equipped with a liquid level meter, a thermometer, and a pressure gauge, and can always store a certain amount of liquid carbon dioxide.

  The carbon dioxide supply line cools the liquid carbon dioxide stored in the condenser 3 with the cooler 4, and transfers the liquid carbon dioxide with the high-pressure pump 5. It is heated by the heater 7 via the flow meter 6, and continuously supplied to the mixing unit 8 via the check valve 14.

At the same time, the raw hydrogen peroxide solution is supplied from the hydrogen peroxide solution supply line to the mixing unit 8 via the heater 16 and the check valve 15 by the high-pressure pump 17.
A high-pressure micromixer is used for the mixing section 8, and the shape of the mixer is a swirl mixer, a static mixer, a turbulent mixing mixer, a multistage reduced flow mixer, etc., and hydrogen peroxide water and carbon dioxide are instantly used. And mix efficiently. After mixing, carbon dioxide not dissolved in the hydrogen peroxide solution is instantly separated due to the difference in specific gravity, so the contact area between the hydrogen peroxide solution and carbon dioxide is increased, and the mixed fluid is used to increase the contact time. Is again divided and mixed with a high-pressure micromixer. After repeating this operation, carbon dioxide and hydrogen peroxide are continuously transferred to the specific gravity difference separation tank 9. From the lower part of the specific gravity difference separation tank 9, the hydrogen peroxide solution is removed via the liquid level control valve 10, the carbon dioxide dissolved in the degassing device 11 is removed, and the hydrogen peroxide solution is recovered in the hydrogen peroxide solution tank 12. To do.
From the upper part of the specific gravity difference separation tank 9, carbon dioxide dissolving organic matter is transferred to the separator I 23 via the pressure control valve 19 and the line heater 20.

  The carbon dioxide dissolved in the organic matter transferred to the separation tank I23 is heated again by the heater 25 and separated into gaseous carbon dioxide and organic matter liquid. The gaseous carbon dioxide is transferred to the activated carbon 30 and collected in the condenser 3. The organic liquid is transferred to the separator II 24 via the valve 27 and discharged out of the system through the valve 29.

Further, the organic liquid collected in the separator II 24 can be taken out during continuous operation by operating the valve 27, valve 28, and valve 29.
The gaseous carbon dioxide transferred from the separator I23 and the separator II24 is vaporized together with the gaseous carbon dioxide by the activated carbon 30 to collect the transferred organic liquid, and only the gaseous carbon dioxide is transferred to the subsequent condenser 3. Further, the gaseous carbon dioxide exiting the deaerator 11 is transferred to the condenser 3 via the booster pump 31.

  Two liquids are mixed in the mixing section of carbon dioxide supplied from the supercritical carbon dioxide supply section and the raw material hydrogen peroxide water, and organic substances, particularly hydrophobic organic substances in the hydrogen peroxide water are extracted and transferred to carbon dioxide.

Pretreatment means (2)
Pre-processing means (2)
This is a means for adding a chelating agent to a raw material hydrogen peroxide solution containing a hydrophobic metal colloid and filtering it with a ceramic filter to remove the colloidal metal compound in the hydrogen peroxide solution.

FIG. 2 is a flowchart showing an example of this embodiment.
2 includes a circulation tank 31, a circulation pump 32, a ceramic filter 33, and a circulation line 34.

  The raw hydrogen peroxide solution and the chelating agent are sent from the circulation tank 31 to the ceramic filter 33 by the pump 32. The chelating agent may be previously mixed with the raw hydrogen peroxide solution in a mixing tank (not shown) or may be mixed in the circulation tank 31. Hydrogen peroxide is divided into circulating and permeating water. Most of the hydrogen peroxide solution returns to the circulation tank through the hollow part of the ceramic filter. At the same time, some hydrogen peroxide passes through the ceramic filter and is discharged as colloid-free hydrogen peroxide.

  In addition, since the colloidal metal compound is gradually concentrated in the circulation tank 31, the processing of the ceramic membrane is stopped each time about 20 times as much permeated hydrogen peroxide solution as the concentration tank is obtained. Regular extraction of concentrated hydrogen peroxide containing a large amount of metal compound also contributes to stable filtration without colloidal metal compound leaking into the permeate.

  The filtration pressure of the ceramic filter is determined by adjusting the filter hole diameter, pump rotational speed, inlet pressure and outlet pressure. The tank material and the piping material are preferably those that do not corrode or have impurities mixed therein. Typically, Teflon (registered trademark) coated stainless steel or Teflon (registered trademark) lined stainless steel is used. The valve for adjusting the pressure is preferably made of Teflon (registered trademark).

  The filter is made of porous ceramic (hollow type) as described above, and the housing is made of stainless steel coated with Teflon (registered trademark) or stainless steel coated with Teflon (registered trademark). The packing in the apparatus of the present invention is preferably made of Teflon (registered trademark) or Viton.

By such a purification method and a purification apparatus of the present invention, the hydrophobic organic substance and colloidal metal compound in the purified hydrogen peroxide water are reduced by about 1/1000 to 1/10000 compared to before the treatment.
The pretreatment means (1) and (2) need only have either one, and preferably have both.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to these Examples at all.

[Example 1]
First, put 50% hydrogen peroxide solution with a total organic carbon concentration of 37ppm, Al concentration, and evaporation residue of 106ppm into an extraction vessel, and put supercritical carbon dioxide at a pressure of 25MPa and a temperature of 35 ℃ into the hydrogen peroxide solution. And supercritical carbon dioxide were contacted. Supercritical carbon dioxide was separated, and the total organic carbon concentration in the hydrogen peroxide remaining in the extraction vessel was 8 ppm.

  Next, this hydrogen peroxide solution was taken out, and sodium metaphosphate having an Al concentration of about 22 times as the P concentration was added thereto, followed by filtration with a 20 nm ceramic filter (Tl-250L manufactured by Noritake) in a cross flow manner.

  The Al concentration in the permeated hydrogen peroxide solution was 1 ppb or less. The evaporation residue was 0.2 ppm or less.

DESCRIPTION OF SYMBOLS 1 ... Liquid carbon dioxide cylinder for replenishment 2 ... Cooling device 3 ... Condenser 4 ... Cooler 5 ... High-pressure pump 6 ... Flow meter 7 ... Heater 8 ... Mixing Part 9: Specific gravity difference separation tank
10 ... Liquid level control valve
11 ... Deaeration device
12 ... Hydrogen peroxide recovery tank
13, 21, 22 ... safety valve
14, 15 ... Check valve
16 ... heater
17 ... High pressure pump
18 ... Hydrogen peroxide tank
19 ... Liquid level control valve
23 ... Separator I
24 ・ ・ ・ Separator II
20 ... Line heater
25, 26 ... Heater
30 ... Activated carbon
27, 28, 29 ... Valve
31 ... circulation tank
32 ... circulation pump
33 ... Ceramic filter
34 ... circulation line
MFM mass flow meters
TC thermal controller
PG pressure gauge
PIC pressure indicated controller
LIC liquid level indicated controller
Tl thermal indicator
Pl pressure indicator

Claims (4)

In a method for purifying a raw material hydrogen peroxide solution containing a hydrophobic substance as an impurity using a purification tower packed with an ion exchange resin,
As a pretreatment for the purification process,
(I) Contact with a liquid, subcritical or supercritical carbon dioxide fluid to dissolve and extract hydrophobic organic substances in carbon dioxide, and remove hydrophobic organic substances from the hydrophobic substances contained in hydrogen peroxide water A method for producing purified hydrogen peroxide water, comprising: In a method for purifying a raw material hydrogen peroxide solution containing a hydrophobic substance as an impurity using a purification tower packed with an ion exchange resin,
As a pretreatment for the purification process,
(I) Contact with a liquid, subcritical or supercritical carbon dioxide fluid to dissolve and extract hydrophobic organic substances in carbon dioxide, and remove hydrophobic organic substances from the hydrophobic substances contained in hydrogen peroxide water And
(Ii) Purifying peroxidation characterized by adding a chelating agent to hydrogen peroxide solution and filtering with a ceramic filter to remove hydrophobic colloidal metal compounds from hydrophobic substances contained in hydrogen peroxide solution A method for producing hydrogen water.   The obtained hydrogen peroxide solution is further subjected to removal of impurities contained in the hydrogen peroxide solution with a cation ion exchange resin and / or an anion ion exchange resin. A method for producing purified hydrogen peroxide water. Purified hydrogen peroxide solution that purifies hydrogen peroxide solution using a purification tower filled with cation ion exchange resin and / or anion ion exchange resin as raw material hydrogen peroxide solution containing a hydrophobic substance as an impurity A purification device,
As pre-processing means,
(i) together with means for heating and pressurizing carbon dioxide,
(ii) an extraction means for mixing a carbon dioxide fluid and hydrogen peroxide water to extract hydrophobic organic impurities into the carbon dioxide fluid;
(iii) from carbon dioxide fluid, the carbon dioxide in the gas, consisting comprises a hydrophobic organic substance removing means comprising a gas-liquid separation means for separating the hydrophobic organic impurities purifier.

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