JP4735500B2 - Production method of hydrogen peroxide by anthraquinone method - Google Patents

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 in which an anthraquinone having an alkyl substituent or 5,6,7,8-tetrahydroanthraquinone having an alkyl substituent (hereinafter, both may be collectively referred to as “anthraquinones”) is dissolved in a working solution. be called. As the solvent, a mixture of two kinds of a nonpolar organic solvent and a polar organic solvent is used.

  In the anthraquinone method, a reduction process in which anthraquinones are reduced with hydrogen in the presence of a catalyst, an oxidation process in which the generated anthrahydroquinones are oxidized and converted back to anthraquinones, and at the same time, hydrogen peroxide is generated. 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. In this, the low-boiling-point modified product derived from a solvent is also contained.

  Conventionally, 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 to 170 ° C. using a solid or aqueous solution of a halide such as aluminum or ammonium as the same treatment with chemicals. 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, crystallization clogging of the distillate is prevented. For this purpose, a method is described in which the vapor distilled from the second stage distillation is condensed on a liquid film of a 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 decomposition product is useful because it is useful as a solubility aid for hydroquinones, and the purpose is to remove only harmful heavy decomposition products.

  As described above, in the proposed technique, a method for efficiently removing a low-boiling modified substance derived from an organic solvent has not been reported. 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.

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. 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. When there are many organic substances in the hydrogen peroxide used as a raw material, there is a problem that the adsorption resin for purification and the reverse osmosis membrane deteriorate so much that the replacement frequency increases.
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 by purifying the solvent in the working solution, it is possible to continue the operation stably without lowering the production efficiency, and the organic matter A method for producing hydrogen peroxide having a reduced concentration is provided.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have recovered the solvent from the working solution, added an alkali compound thereto and distilled it, thereby preventing the accumulation of solvent-modified products, and the impurity concentration It was found that hydrogen peroxide having a reduced amount could be produced, and the present invention was completed.

That is, the present invention relates to a method for producing hydrogen peroxide by an anthraquinone method,
(1) recovering the solvent from at least one of the following AC:
(A) a distillate obtained by distilling a part of the working solution,
(B) Oxidation process exhaust gas,
(C) distillate from the solvent distillation step,
(2) Add an alkali compound to the recovered solvent and distill,
(3) The distillate obtained by distillation is used for at least one of the following a to d.
The present invention relates to a method for producing hydrogen peroxide, characterized in that (a) the working solution is returned to the circulation line, (b) the raw material for preparing the working solution, (c) the solvent for hydrogen peroxide cleaning, and (d) the solvent for catalyst cleaning.

  According to the present invention, it is possible to remove solvent-denatured substances accumulated in the working solution, and it is possible to efficiently produce hydrogen peroxide by an environment-friendly process with little solvent loss. 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 10), and a crude hydrogen peroxide solution is obtained from the extraction process.

  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.

  The solvent to be treated in the present invention preferably does not contain a solute such as anthraquinones (hereinafter referred to as solid content). The following is illustrated as a method of obtaining the solvent which does not contain this solid content. The solvent used as a raw material for these treatments is referred to as “crude solvent”. The treated solvent is referred to as “purified solvent”.

(A) Distillate obtained by distilling a part of the working solution The working solution distillation step 7 is used mainly for the purpose of removing heavy anthraquinone-modified products accumulated in the working solution. In the first stage distillation, the solvent component in the working solution is distilled at a pressure of atmospheric pressure or lower, and then in the second stage distillation, anthraquinones which are solutes are distilled under high vacuum, The anthraquinone modified product is removed. In the present invention, the solvent obtained by the first stage distillation is used as a raw material for the alkali addition distillation step 8.

(B) Oxidation process The solvent vapor contained in the exhaust gas of the oxidation process 2 is recovered and used as a raw material for the alkali addition distillation process 8. Solvent recovery includes a cryogenic separation method in which the exhaust gas is cooled to liquefy and recover the solvent vapor, and an activated carbon adsorption method in which the solvent vapor is adsorbed on the activated carbon and collected, and desorbed and recovered by performing a steaming process. Etc. are used.

(C) Solvent distillation process The hydrogen peroxide solution extracted from the working solution contains a very small amount of working solution components (such as anthraquinones), and the working solution components are recovered and the hydrogen peroxide solution is purified. For the purpose of cleaning with a solvent (hydrogen peroxide cleaning step 5). Moreover, in order to remove the working solution component adhering to the catalyst when replacing the catalyst, it is washed with a solvent (catalyst washing step 9).

  Such a cleaning solvent contains anthraquinones in a small amount, but is concentrated by distilling the solvent by distillation (solvent distillation step 4). The distillate solvent from which the anthraquinones have been removed is used as a raw material for the alkali addition distillation step 8.

  Alkali compounds include alkali metal hydroxides, carbonates, bicarbonates, or alkaline earth metal hydroxides, carbonates, bicarbonates, etc., with sodium hydroxide and potassium hydroxide being preferred. Used for.

  The alkaline aqueous solution is a non-volatile inorganic alkali solution and needs to have a pH of 10 or more, preferably 12 or more. The amount of alkali in the aqueous alkali solution is appropriately adjusted because the required amount varies depending on the amount of acidic substance contained in the crude solvent to be treated, but a 0.3 to 5.0% solution is sufficient as an excessive amount. 0.5 to 2.0% is preferable. If the alkali concentration is too high, the amount of distillate of the neutral solvent-modified product increases. Therefore, it is determined as an amount sufficient to make the acidic degradation product water-soluble.

  The amount of the crude solvent that can be treated with respect to 1 part of the aqueous alkaline solution is preferably 5 to 30 parts, more preferably 8 to 15 parts. When the amount of treatment is small, the amount of wastewater of the alkaline aqueous solution increases, which is not preferable due to wastewater treatment costs and environmental problems. On the contrary, if the processing amount is increased, the amount of the solvent-modified product mixed in the purification solvent increases, and the quality of the obtained hydrogen peroxide is somewhat deteriorated.

  The distillation apparatus is not particularly limited, and a commonly used batch distillation apparatus, continuous distillation apparatus, thin film distillation apparatus or the like is used. Distillation conditions are appropriately selected depending on the type of solvent used in the working solution, and thus cannot be specified unconditionally. However, the pressure is preferably atmospheric pressure, and the temperature is determined as the conditions for distilling the alkaline aqueous solution. The Usually, it is about 100 ° C.

  The operation method may be either a method in which an aqueous alkaline solution is previously charged in a kettle and a crude solvent is fed, or a method in which an alkaline aqueous solution and a crude solvent are mixed and continuously fed. It is also possible to obtain a purified solvent continuously by refluxing water so that the aqueous alkali solution remains in the distillation column and the crude solvent is continuously added. The distilled water is separated and returned as reflux water, and only the purified solvent is recovered. The bottoms concentrated with the solvent modification product can be discarded without neutralizing the environment by neutralizing and treating the activated sludge.

The distillate of the alkali addition distillation 8 can be used for at least one of the following a to d.
(A) Return to the working solution circulation line.
(B) The raw material of the working solution preparation step 6 is used.
(C) Used as a solvent in the hydrogen peroxide cleaning step 5.
(D) Used as a cleaning solvent in the catalyst cleaning step 9.
In addition, although (a) and (b) are returned before the reduction process in FIG. 1, they are not limited to this, and may be before the oxidation process and before the extraction process.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these.

Example 1 (Process A)
(Preparation of crude solvent as processing raw material)
15 liters of working solution used in an apparatus for producing hydrogen peroxide by anthraquinone method having a circulation process of reduction, oxidation and extraction was distilled under a reduced pressure of 13 kPa to obtain 12 liters of a crude solvent. The crude solvent includes dimethylbenzoic acid, alkylphthalic anhydride, aliphatic carboxylic acids, trimethylphenol (TMP), 2,6-dimethyl-2,4-heptanediol in addition to the solvent components pseudocumene and diisobutylcarbinol. It contained solvent-modified products such as (C9 diol). This crude solvent is referred to as crude solvent 1.

(Alkali-added distillation)
1 liter of a 1.0% NaOH aqueous solution is charged into a distillation apparatus (distillation tank with 2 liters of stirrer, 20 cm packed high-melapack rectification tower), and the above-mentioned crude solvent 1 is continuously added, heated and heated with solvent and water The mixture was distilled. The mixture was separated in a stationary tank, and the distilled water was returned to the tower as reflux water, and only the distilled purified solvent was recovered. The crude solvent 1 was continuously supplied, and the supply was stopped when the total supply amount reached 10 liters. The distilled purified solvent was analyzed and the results are shown in Table 1. As the amount of treatment increases, the solvent-denatured product is concentrated in the kettle, so that it partially comes out on the distillation side, but the overall removal rate is maintained.

処理倍率： アルカリ水溶液に対する粗製溶剤の処理量
除去率＝留出総量÷粗製溶剤含有量
酸価： ＪＩＳ−Ｋ００７０により測定

Treatment magnification: Treatment removal rate of crude solvent with respect to alkaline aqueous solution = Total amount of distillate / Crude solvent content Acid value: measured according to JIS-K0070

Example 2
(Confirmation that catalyst poisons have been removed)
A working solution was prepared from the recovered purified solvent and anthraquinones, and the effect on the activity of the hydrogenation catalyst was evaluated. Evaluation of the activity of the hydrogenation catalyst was performed using a batch type evaluation apparatus. 1 part by weight of catalyst and 20 parts by weight of working solution were charged into the reaction vessel. A stainless steel stirring blade was attached to the reaction tank, and after air-tightness, the reaction system was replaced with hydrogen. The amount of hydrogen absorbed per unit catalyst amount was measured for 30 minutes with stirring at 1000 rpm. The reaction temperature was controlled to 30 ° C., and the reaction pressure was controlled to normal pressure. The results are shown in Table 2.

Example 3 (Process B)
The solvent component was recovered from the oxidation tower exhaust gas by a cryogenic separation method. The crude solvent 2 recovered here was subjected to alkali addition distillation under the same conditions as in Example 1. The crude solvent 2 was continuously supplied, and the supply was stopped when the total supply amount reached 15 liters. The purified solvent distilled was analyzed, and the results are shown in Table 3.

Example 4 (Process C)
The distilling solvent obtained by distilling the cleaning solvent used in the hydrogen peroxide cleaning step is referred to as crude solvent 3. The crude solvent 3 was subjected to alkali addition distillation under the same conditions as in Example 1. The crude solvent 3 was continuously supplied, and the supply was stopped when the total supply amount reached 15 liters. The purified solvent distilled was analyzed and the results are shown in Table 4.

Example 5
The alkali concentration was changed from 1.0% NaOH aqueous solution to 0.5%, and other conditions were the same as in Example 1 except that alkali addition distillation was performed. The crude solvent 1 was continuously supplied, and the supply was stopped when the total supply amount reached 10 liters. The purified solvent distilled was analyzed and the results are shown in Table 5.

Example 6
The alkali concentration was changed from 1.0% NaOH aqueous solution to 2.0%, and the other conditions were the same as in Example 1 except that alkali addition distillation was performed. The crude solvent was continuously supplied, and the supply was stopped when the total supply amount reached 10 liters. The purified solvent distilled was analyzed, and the results are shown in Table 6.

Example 7
The alkali concentration was changed from 1.0% NaOH aqueous solution to 10.0%, and other conditions were the same as in Example 1, and alkali addition distillation was performed. The crude solvent 1 was continuously supplied, and the supply was stopped when the total supply amount reached 10 liters. The purified solvent distilled was analyzed and the results are shown in Table 7.

Comparative Example 1
(Normal distillation purification)
The above-mentioned crude solvent 1 was continuously added to a distillation apparatus (distiller with 2 liters of stirrer, 20 cm packed high melapack rectification tower), and heated to distill and collect the solvent. The supply was stopped when the total supply amount reached 10 liters. The purified solvent distilled was analyzed and the results are shown in Table 8.

Example 8
After obtaining the crude solvent and recovered anthraquinone by the same operation as in Example 1, the crude solvent was subjected to alkali addition distillation to obtain a purified solvent. Then, this purified solvent and recovered anthraquinone were mixed to newly prepare a working solution. Using a small-scale hydrogen peroxide production apparatus equipped with hydrogenation, oxidation, and extraction steps, operation was performed with the working solution prepared as described above to obtain hydrogen peroxide having a concentration of 40% obtained by extraction. . Next, this extracted hydrogen peroxide was washed with the purification solvent obtained in Example 4 to remove the working solution component dissolved in a trace amount. Finally, the hydrogen peroxide after washing was concentrated under a reduced pressure of 5 kPa to obtain 60% hydrogen peroxide. As a result of analyzing this hydrogen peroxide with a total carbon analyzer, the total carbon concentration was 45 mg / L.

Comparative Example 2
A small-scale hydrogen peroxide production apparatus was operated using the untreated working solution used in Example 1 to obtain hydrogen peroxide having a concentration of 40% obtained by extraction. Next, the extracted hydrogen peroxide was washed with the crude solvent which is the raw material of Example 4. Finally, as in Example 8, the solution was concentrated under a reduced pressure of 5 kPa to obtain 60% hydrogen peroxide. As a result of analyzing this hydrogen peroxide with a total carbon analyzer, the total carbon concentration was 175 mg / L.

Hydrogen peroxide production flow of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reduction process 2 Oxidation process 3 Extraction process 4 Solvent distillation process 5 Hydrogen peroxide washing process 6 Working solution preparation process 7 Working solution distillation process 8 Alkaline addition distillation process 9 Catalyst washing process 10 Working solution circulation line

Claims (2)

In the method for producing hydrogen peroxide by the anthraquinone method,
(1) recovering the solvent from at least one of the following AC:
(A) a distillate obtained by distilling a part of the working solution,
(B) Oxidation process exhaust gas,
(C) distillate from the solvent distillation step,
(2) Add an alkali compound to the recovered solvent and distill,
(3) The distillate obtained by distillation is used for at least one of the following a to d.
(A) Return to working fluid circulation line (b) Preparation raw material of working solution (c) Hydrogen peroxide cleaning solvent (d) Catalyst cleaning solvent Method for producing hydrogen peroxide according to claim 1 wherein the alkali compound is sodium hydroxide.

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