JP2008120631A - Manufacturing process of hydrogen peroxide with anthraquinone method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for manufacturing hydrogen with the anthraquinone method by which hydrogen peroxide having a reduced content of organic matters is obtained without lowering manufacturing efficiency and with a continued stable plant operation by removing degenerated matter derived from the organic solvent constituting of the working solution. <P>SOLUTION: The manufacturing process of hydrogen peroxide with the anthraquinone method involves (1) separating organic phase 1 and water phase 1 by washing the bottom liquid obtained from the solvent distillation step and (2) removing the solvent-degenerated matter by treating separated water phase 1 in order to remove the solvent-degenerated matter accumulated in the working solution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for efficiently producing hydrogen peroxide by removing impurities accumulated in a working solution.

  At present, industrial production of hydrogen peroxide is a method using anthraquinones as a reaction medium and is called an anthraquinone method. A solution obtained by dissolving an anthraquinone having an alkyl substituent or 5,6,7,8-tetrahydroanthraquinone having an alkyl substituent (hereinafter sometimes referred to as “anthraquinones”) in an organic solvent is a working solution. The organic solvent is usually a mixture of two types, a nonpolar organic solvent and a polar organic solvent.

  In the anthraquinone method, a reduction step of reducing anthraquinones with hydrogen in the presence of a catalyst, an oxidation step of oxidizing the generated anthrahydroquinones and converting them back to anthraquinones, and simultaneously generating hydrogen peroxide, The working solution after extraction is returned to the reduction step again to form a circulation process.

  Here, as the anthraquinones are repeatedly reduced and oxidized, by-products are generated and accumulated, which causes a reduction in the productivity of hydrogen peroxide, and also hinders stable operation of the plant. Further, not only the modified product of anthraquinones but also a modified product is produced in the organic solvent in the working solution, which adversely affects the productivity.

  To solve this problem, various by-product removal / regeneration methods have been proposed. Patent Document 1 describes a method in which reduced anthraquinones are extracted with an alkaline aqueous solution to remove ineffective anthraquinones that do not contribute to hydrogen peroxide production. When processing is performed using chemicals as in this method, there is a problem that a large amount of alkaline waste liquid is generated.

  Patent Document 2 describes a method of regenerating ineffective anthraquinones by treating a working solution at 100-170 ° C. using a solid or aqueous solution of a halide such as aluminum or ammonium, as a similar chemical treatment. Has been. Patent Document 3 describes a method in which a working solution is treated with ozone, then extracted with an aqueous alkali metal hydroxide solution, and the working solution after extraction and separation is brought into contact with activated alumina or activated magnesia.

  In Patent Document 4, when the first-stage distillation for separating the solvent in the working solution and the second-stage distillation for separating the anthraquinones and light substances of monoanthracene are prevented, the crystallization clogging of the distillate is prevented. For this purpose, a method is described in which the distilled vapor of the second stage distillation is condensed on a liquid film of cold solvent. The working solution contains a solvent, anthraquinones, a heavy decomposition product (polyanthracene), a light decomposition product, and, in some cases, a hydroxy compound. In this method, the light degradation product is useful because it is useful as a solubility aid for hydroquinones, and the purpose is to remove only harmful heavy degradation products.

  As described above, although there are methods for removing and regenerating modified anthraquinones such as anthraquinone monomer by-products, solvent addition products of anthraquinones, and polymers of anthraquinones in the proposed technology, solvent modification There has been no report on how to remove objects. Since the solvent-modified product changes the physical properties such as the specific gravity, viscosity, and surface tension of the working solution, it causes a reduction in efficiency of the reduction / oxidation / extraction process of the working solution and an obstacle to stable operation. In an environment-friendly plant with little solvent loss, the amount of solvent discharged into the environment is very small, and solvent-modified products are not discharged, so the problem of accumulation becomes obvious.

  In the anthraquinone method, the crude hydrogen peroxide solution obtained in the extraction step is washed with a solvent to remove dissolved working solution components, and then dissolved in a distillation step that also serves to adjust the concentration. Ingredients have been removed. However, this method has a problem that it is difficult to remove the water-soluble polar solvent-modified product.

In recent years, as the degree of integration of semiconductors has increased, the demand for hydrogen peroxide used as a cleaning agent has become stricter, and reduction of residual organic substances in hydrogen peroxide is desired. As a method for reducing organic substances, there are methods using adsorption resins and reverse osmosis membranes, but when there are many organic substances in hydrogen peroxide as a raw material, there was a problem that resin and membranes deteriorated and replacement frequency was high. .
In view of the above, there is a demand for a method capable of obtaining hydrogen peroxide with low residual organic matter and easy purification.
JP-A-6-135705 Japanese Patent Publication No.41-18497 Japanese Examined Patent Publication No. 45-19164 Japanese Patent Publication No.55-23762

  The object of the present invention is to solve the above-mentioned problems in the prior art, and to remove the denatured product derived from the organic solvent constituting the working solution, thereby continuing the stable operation of the plant without reducing the production efficiency. Another object of the present invention is to provide a method for producing hydrogen peroxide having a reduced organic substance concentration.

As a result of intensive research on the removal of the solvent-modified product, the present inventors have found that the polar solvent-modified product is concentrated in the bottoms of the solvent distillation step. As a result, the present inventors have completed a method for efficiently removing the water.
That is, in the method for producing hydrogen peroxide by the anthraquinone method, the present invention includes (1) washing the bottoms obtained in the solvent distillation step with water in order to remove the solvent modification product accumulated in the working solution. The present invention relates to a method for producing hydrogen peroxide, characterized by separating into an organic phase 1 and an aqueous phase 1 and (2) treating the separated aqueous phase 1 to remove solvent modification products.

  According to the present invention, it is possible to remove the denatured polar solvent accumulated in the working liquid, and it is possible to efficiently produce hydrogen peroxide by an environment-friendly process with little solvent loss. A hydrogen peroxide solution with a reduced organic matter concentration can be obtained.

  The flow of FIG. 1 which is an example of the embodiment of the present invention will be described. The working solution circulates through the reduction process 1, the oxidation process 2 and the extraction process 3 (line 11), and a crude hydrogen peroxide solution is obtained from the extraction process 3.

  Examples of the anthraquinone used in the present invention include ethyl anthraquinone, t-butylanthraquinone, and amylanthraquinone having an alkyl substituent. These may be used alone or in combination of two or more. Examples of the tetrahydroanthraquinone having an alkyl substituent include ethyltetrahydroanthraquinone, t-butyltetrahydroanthraquinone, amyltetrahydroanthraquinone and the like. These may be used alone or in combination of two or more.

  The organic solvent used for preparing the working solution in the present invention is not particularly limited. Preferred organic solvents include aromatic hydrocarbons as nonpolar solvents. For example, benzene or a benzene derivative containing an alkyl substituent having 1 to 5 carbon atoms. Examples of the polar solvent include higher alcohols, carboxylic acid esters, tetrasubstituted ureas, cyclic ureas, and trioctyl phosphoric acid.

  Solvent-modified products are mainly oxides and decomposition products of solvent components. Specific examples include carboxylic acids, polyols, and phenols. Since some of these compounds act as catalyst poisons in the hydrogenation step, accumulation in the working solution causes a reduction in hydrogenation efficiency due to deterioration in catalyst activity. In addition, these solvent component-modified products change physical properties such as the specific gravity, viscosity, and surface tension of the working solution, which causes a reduction in the efficiency of the reduction / oxidation / extraction process of the working solution and an obstacle to stable operation. . A part of the solvent-modified product in the working solution is dissolved in hydrogen peroxide, so that it remains as an organic impurity in the product hydrogen peroxide water, thereby degrading the quality of hydrogen peroxide.

<Solvent distillation process 4>
The solvent recovered from the exhaust gas in the oxidation process 2, the solvent recovered from the hydrogen peroxide cleaning process 7, the solvent recovered from the catalyst cleaning process, the recovery solvent used for filter cleaning, and the like are distilled in the solvent distillation process 4.

  The solvent contained in the exhaust gas of the oxidation step 2 is a cryogenic separation method in which the exhaust gas is cooled to liquefy the solvent vapor, or activated carbon adsorption in which the solvent vapor is adsorbed on the activated carbon to be collected and desorbed by performing a steaming treatment. Collected by law.

  The crude hydrogen peroxide solution extracted from the working solution contains a very small amount of working solution components (such as anthraquinones). In the hydrogen peroxide cleaning step 7, the working solution components are recovered and the hydrogen peroxide solution is purified. For the purpose of washing with a solvent.

  In order to remove the working solution component adhering to the catalyst when the catalyst is replaced, the catalyst is washed with a solvent in the catalyst washing step. In addition, the filter is washed with a solvent in the filter washing step for the purpose of removing the working liquid component adhering during maintenance of the filter in the step of using the working solution. Such washing solvents contain a small amount of anthraquinones and modified polar solvents.

  As the distillation apparatus, generally used distillation equipment can be used, and there is no particular limitation. For example, a batch distillation apparatus, a continuous distillation apparatus, a thin film distillation apparatus, etc. are mentioned. Since the oxidation tower exhaust gas recovery solvent, the hydrogen peroxide cleaning solvent and the like are constantly recovered, a continuous distillation apparatus is preferable. Distillation conditions are appropriately selected depending on the organic solvent used in the working solution, and thus cannot be defined unconditionally, but the following conditions are selected. That is, the pressure is preferably 1 to 100 kPa (atmospheric pressure), and more preferably 5 to 30 kPa. The temperature is preferably 50 to 200 ° C.

  The solvent distillation distillate (line 13) is reused as a purification solvent in the hydrogen peroxide washing step 7, the catalyst washing step, and the filter washing step. A part of the purification solvent is returned to the circulation line 11 via the working solution preparation step or directly. The place to be returned may be before the reduction step 1, before the oxidation step 2, or before the extraction step 3. The solvent containing a small amount of anthraquinones used in each step (purified solvent after use) is returned to the solvent distillation step 4 and recycled.

<Bottom liquid washing process 5>
The bottoms of solvent distillation (line 12) is separated into organic phase 1 (line 14) and aqueous phase 1 (line 15) by washing with water in bottoms washing step 5, and the organic phase from which the polar solvent denatured product has been removed. 1 is returned to line 11. The place to be returned may be before the reduction step 1, before the oxidation step 2, or before the extraction step 3. The aqueous phase 1 containing the polar solvent modification product is recycled after removing the polar solvent modification product in the washing water treatment step 6. The apparatus used in the washing step is not particularly limited, and for example, a mixer settler, a centrifugal extractor, a counter-current liquid / liquid extraction tower, and the like can be used. A mixer-settler system is preferable.

  The water used for washing may be water that does not substantially contain acid, alkali, or organic matter. Ion exchange water, distilled water, ultrapure water, etc. can be used without problems. Economically, it is preferable to use steam condensate. Since metal components, scales, and the like are mixed in the steam condensed water, it is preferably filtered with a filter of 10 μm or less, preferably 1 μm or less. Moreover, you may perform an ion exchange process and a reverse osmosis membrane process as needed. The amount of water to be washed increases as the amount of the denatured product is removed as it is used in a large amount with respect to the bottoms. However, since the amount of water after extraction also increases, 1 to 10 times is usually appropriate. A 7-fold amount is preferred.

<Washing water treatment process 6>
The aqueous phase 1 contains a high concentration of organic matter, and it is not preferable to treat it as waste water as it is because of environmental burden. Therefore, the treatment load of waste water is reduced by washing the polar solvent modified product contained in the aqueous phase 1 with an organic solvent. As the organic solvent, those having low solubility in water, a large partition coefficient of the polar solvent modified product, and a boiling point difference from the polar solvent modified product of 50 ° C. or more are desirable. Specifically, dichloromethane and chloroform are preferable. For this cleaning, for example, an apparatus such as a mixer settler, steam stripping, centrifugal extractor, AC liquid / liquid extraction tower or the like can be used. The amount of the organic solvent is appropriately selected according to the magnitude of the partition coefficient is at least rinsing after cleaning water 1 m ³ per 0.01 m ^3. It is preferably 0.1 m ³ or more per 1 m ^{3 of} washing water after washing with water.

<Organic phase distillation step 8>
The polar solvent modified product separated from the aqueous phase 1 to the organic phase 2 (line 16) by the washing treatment step 6 is concentrated and separated by the organic phase distillation step 8 (line 19). The distillation apparatus is not particularly limited, and a batch distillation apparatus, a continuous distillation apparatus, a thin film distillation apparatus, or the like can be used. As a pressure, 50-100 kPa is suitable. The temperature is preferably 50 to 80 ° C. Here, the organic solvent (line 17) contained in the distillate is recycled to the washing of the water washing liquid. In addition, the polar solvent-modified product obtained as the bottoms is discarded.

<Aqueous phase treatment process 9>
On the other hand, the aqueous phase 2 (line 18) from which the polar solvent-modified product has been removed can be reused as water used in the bottoms washing process by removing the organic solvent by steam distillation in the aqueous phase treatment process 9. .

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these. In addition, the solvent used for the working solution and the solvent was diisobutylcarbinol and pseudocumene as a polar solvent and a nonpolar solvent, respectively. The 2,6-dimethyl-2,4-heptanediol concentration was quantified as a polar solvent modified product. Quantification was performed using FID-GC as an analytical instrument and 1-nonanol as an internal standard. In the examples, 2,6-dimethyl-2,4-heptanediol was quantified as a representative substance in order to compare the removal amount of the polar solvent-modified product. However, the polar solvent-modified products are various mixtures. .

Example 1
Using the working solution used in the hydrogen peroxide production system by the anthraquinone method having a reduction, oxidation, and extraction circulation process, continuous operation was performed using a small-scale hydrogen peroxide production system. The solvent recovered from the exhaust gas in the oxidation process was used in the catalyst cleaning process and the hydrogen peroxide cleaning process in the reduction process. The solvent recovered from the two washing steps was distilled in the solvent distillation step, the distillate was recycled as a purified solvent, and part of it was returned to the circulating working solution.
The bottoms were washed in a bottoms washing step using pure water with a volume ratio of 5 times using a countercurrent 5-stage mixer / settler extractor. The organic phase after washing was returned to the circulating working solution. The aqueous phase was discarded. A small-scale hydrogen peroxide production unit was operated for 3 months.
Table 1 shows the 2,6-dimethyl-2,4-heptanediol concentration and the total organic carbon concentration of the obtained hydrogen peroxide solution in each step at the start and end of operation. By washing the bottoms with water, the denatured polar solvent contained in the working solution decreased, and the total organic carbon concentration of the resulting hydrogen peroxide solution also decreased.

Example 2
<Washing water treatment process 6>
100 liters of the wash water from which the bottoms were washed in Example 1 was washed with 10 liters of chloroform using a countercurrent 5-stage mixer / settler extractor. As an aqueous phase after washing, 2,6-dimethyl-2,4-heptanediol concentration = 0.05 g / l was obtained. As the chloroform layer, 2,6-dimethyl-2,4-heptanediol concentration = 7.8 g / l was obtained.

Example 3
<Organic phase distillation step 8>
Using a rotary evaporator, 10 liters of the chloroform layer obtained in Example 2 was distilled off at a target of 95% of the charged solution at 50 kPa and 50 ° C. Distillation was carried out to a distillation rate of 96%, and the chloroform purity of the distillate was measured and found to be 99% or more.

Example 4
<Water phase treatment process>
Steam was blown into 10 liters of the washed aqueous layer obtained in Example 2, and chloroform was distilled off. Distillation was carried out to a distillation rate of 10%, and the chloroform concentration in the aqueous layer was measured and found to be 1 ppm or less.

Comparative Example 1
The treatment was carried out in the same manner as in Example 4 except that the solvent distillation can effluent washing water obtained at the start of operation in Example 1 was used as the distillation raw material. The 2,6-dimethyl-2,4-heptanediol concentration in the aqueous layer was measured and found to be 0.7 g / l.

Example 5
A small-scale hydrogen peroxide production apparatus was operated in the same manner as in Example 1 except that the water obtained by performing the treatment corresponding to Example 4 was used as washing water. The 2,6-dimethyl-2,4-heptanediol concentration and the total organic carbon concentration of the obtained hydrogen peroxide solution in each step at the start and end of operation were as follows. By washing the bottoms with reuse of washing water, the polar solvent denatured product contained in the working solution was reduced, and the total organic carbon concentration of the resulting hydrogen peroxide solution was also reduced. The results are shown in Table 2.

It is a flowchart which shows the aspect of the manufacturing process by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reduction process 2 Oxidation process 3 Extraction process 4 Solvent distillation process 5 Drained liquid washing process 6 Washing water treatment process 7 Hydrogen peroxide washing process 8 Organic phase distillation process 9 Water phase treatment process

Claims (5)

  In the method for producing hydrogen peroxide by the anthraquinone method, in order to remove the solvent denatured product accumulated in the working solution, (1) the bottoms obtained in the solvent distillation step are washed with water, and the organic phase 1 and water A method for producing hydrogen peroxide, characterized by separating into phase 1 and (2) treating the separated aqueous phase 1 to remove solvent modification products.   The production method according to claim 1, wherein the separated organic phase 1 is added to the working fluid.   The method according to claim 1, wherein the separated aqueous phase 1 is washed with an organic solvent, separated into an organic phase 2 and an aqueous phase 2, and the organic phase 2 is treated to remove a solvent modification product.   The method according to claim 3, wherein the separated aqueous phase 2 is used for washing the bottoms.   The manufacturing method of Claim 1 which reuses the distillate obtained by the solvent distillation process as a refinement | purification solvent.

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