TW202028167A - Processing method for working solution - Google Patents

Abstract

The objective of the present invention is to provide a processing method for a working solution, wherein the amount of anthraquinones is increased by regenerating, into anthraquinones, by-products derived from anthraquinones and having no hydrogen peroxide generation ability, the by-products being contained in a repeatedly used working solution. According to the present invention, provided is a processing method for a working solution by mixing the working solution with an alkali metal compound, the working solution being continuously used in a method for producing hydrogen peroxide through an anthraquinone process including a hydrogenation step, an oxidation step, and an extraction step, wherein the method is characterized by using, as a working solution to be processed before the working solution is mixed with an alkali metal compound, a working solution which has a concentration of anthraquinones represented by general formula (1) or general formula (2), of less than 0.20 mol/L (in general formula (1) and general formula (2), R represents hydrogen or an alkyl group having 1-10 carbon atoms).

Description

Working solution processing method

The present invention relates to a method for treating a working solution in the production of hydrogen peroxide by the anthraquinone method, and a method for producing hydrogen peroxide using the treated working solution. In detail, it relates to the regeneration of anthraquinone derivatives that do not have the ability to generate hydrogen peroxide into anthraquinones such as alkylanthraquinones and alkyltetrahydroanthraquinones by mixing the reused working solution with alkali metal compounds. This kind of treatment method, and the production method of hydrogen peroxide using the treated working solution.

The main production method of hydrogen peroxide currently practiced in industry is to use anthraquinone, tetrahydroanthraquinone, alkyl anthraquinone or alkyl tetrahydroanthraquinone (hereinafter sometimes collectively referred to as anthraquinones) as the reaction solvent. Anthraquinone method. Anthraquinones are usually used in a state of being dissolved in a mixed solvent of two types of polar organic solvents and non-polar organic solvents. The solution prepared by dissolving anthraquinones in the mixed solvent is called the working solution.

The anthraquinone method is mainly composed of a hydrogenation step, an oxidation step and an extraction step. The hydrogenation step is a step of performing hydrogenation treatment to hydrogenate the anthraquinones in the working solution in the presence of a catalyst to generate the corresponding anthrahydroquinones. The subsequent oxidation step is to oxidize the obtained anthrahydroquinones in air or a gas containing oxygen to convert them back to anthraquinones. At this time, hydrogen peroxide is generated and dissolved in the working solution. The next extraction step is to extract the generated hydrogen peroxide with water and separate it from the working solution. The working solution after the extraction step is again returned to the hydrogenation step, oxidation step, extraction step... for continuous use.

When the hydrogen peroxide production process is repeated, anthrone, xanthone, epoxy tetrahydroanthraquinone, alkyl anthrone, alkyl xanthone, and alkylene oxide are generated due to side reactions in the working solution. Anthraquinone derivatives such as hydroanthraquinone. Even if the anthraquinone derivative is supplied to the hydrogenation step and the oxidation step, hydrogen peroxide is not generated. Although the amount of by-products of the anthraquinone derivative in each process is very small, the anthraquinone derivative will accumulate in the working solution when the hydrogen peroxide production process is repeated, which causes various obstacles.

Regarding the technology of regenerating the anthraquinones from the by-produced anthraquinone derivatives that can be used in the hydrogen peroxide production process, it is proposed in Patent Document 1 to treat the working solution with an alkali and an aqueous alkali solution to remove the inactive components ( The by-product anthraquinone derivative) is converted into alkyl tetrahydroanthraquinone technology. However, the technique of Patent Document 1 requires a long-term reaction. In addition, the alkyltetrahydroanthraquinone obtained from the conversion of inactive components is recovered by crystallization. Therefore, to reuse the recovered alkyltetrahydroanthraquinone in the production of hydrogen peroxide, it needs to be dissolved in The solvent prepares the working solution again. Therefore, the technology of Patent Document 1 is a very inefficient technology if considering the complexity of its equipment and operations. Therefore, it is desired to establish a regeneration technology of by-produced anthraquinone derivatives that takes a short time and does not require complicated processing steps such as crystallization.

In addition, in Patent Document 2, in order to convert epoxyalkyltetrahydroanthraquinone, which is an anthraquinone derivative that does not contribute to the generation of hydrogen peroxide, into alkyltetrahydroanthraquinone useful for the generation of hydrogen peroxide, A method of contacting a liquid containing alkylanthrahydroquinone with a solid catalyst starting with alumina is proposed. However, the method of Patent Document 2 requires a high concentration of alkylanthrahydroquinone, which significantly reduces the efficiency of hydrogen peroxide production. In addition, the reaction conditions are a high temperature exceeding 100°C and a long time of 1 to 20 hours. Therefore, it is expected that the regeneration technology of by-produced anthraquinone derivatives can be implemented with a low reaction temperature and a short time without reducing the efficiency of hydrogen peroxide production. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 39-8806 [Patent Document 2] Japanese Patent Publication No. 43-11658

[The problem to be solved by the invention]

Therefore, it is desired to regenerate the by-products from the anthraquinones that do not have the ability to generate hydrogen peroxide contained in the reused working solution into anthraquinones to increase the amount of anthraquinones in the working solution. [Means to solve the problem]

通式(1)及通式(2)中，R係表示氫或碳數1～10之烷基。 >2>如>1>之處理方法，其中，該要被處理之工作溶液係在氫化步驟之後且在氧化步驟之前抽出之一部分的工作溶液、或者係對於在氫化步驟之後且在氧化步驟之前抽出之一部分的工作溶液添加氫化步驟之前的工作溶液進行稀釋而獲得之工作溶液。 >3>如>1>之處理方法，其中，該要被處理之工作溶液係在萃取步驟之後且在氫化步驟之前抽出之一部分之工作溶液。 >4>如>1>～>3>中任一項之處理方法，其中，該蒽氫醌類之濃度為0.05～0.10mol/L。 >5>如>1>～>4>中任一項之處理方法，其中，該要被處理之工作溶液中更含有選自於由下述通式(a)～(e)構成之群組中之一種以上的蒽醌衍生物； [化2]

通式(a)～通式(e)中，R表示之含意與該通式(1)及(2)相同。 >6>如>1>～>5>中任一項之處理方法，其中，該R係乙基、丁基或戊基。 >7>如>1>～>6>中任一項之處理方法，其中，於0～60℃之溫度，將該要被處理之工作溶液與鹼金屬化合物混合。 >8>如>1>～>7>中任一項之處理方法，其中，將該要被處理之工作溶液與該鹼金屬化合物之水溶液，以要被處理之工作溶液：鹼金屬化合物水溶液=1以上：1(體積)之量進行混合。 >9>如>1>～>8>中任一項之處理方法，其中，該鹼金屬化合物係氫氧化鈉或氫氧化鉀。 >10>如>1>～>9>中任一項之處理方法，其中，混合氫氧化鈉之濃度為0.5mol/L以上之氫氧化鈉水溶液。 >11>如>1>～>10>中任一項之處理方法，其中，使用管道混合器(line mixer)將該要被處理之工作溶液與該鹼金屬化合物之水溶液進行混合。 >12>如>1>～>11>中任一項之處理方法，其中，在與鹼金屬化合物混合後，更混合酸來進行後處理。 >13>如>12>之處理方法，其中，該酸係硝酸或磷酸。 >14>如>12>或>13>之處理方法，其中，在與鹼金屬化合物混合後，更混合硝酸或磷酸之濃度為0.20mol/L以上的酸性水溶液。 >15>如>12>～>14>中任一項之處理方法，其中，使用攪拌混合機進行與該酸的混合。 >16>如>12>～>15>中任一項之處理方法，其中，混合該酸後，更混合水來進行後處理。 >17>如>12>～>16>中任一項之處理方法，其中，以將後處理後之工作溶液與純水進行攪拌並靜置，使分離出之水層的pH成為7以下之方式進行後處理。 >18>一種過氧化氫之製造方法，係使用經如>1>～>17>中任一項之處理方法處理的工作溶液，藉由蒽醌法製造過氧化氫。 [發明之效果]That is, the present invention is as follows. >1>A treatment method by mixing the working solution in continuous use with an alkali metal compound in a method of producing hydrogen peroxide by an anthraquinone method including a hydrogenation step, an oxidation step, and an extraction step. The method is characterized in that: as a working solution to be treated before mixing with an alkali metal compound, the concentration of anthrahydroquinone represented by the following general formula (1) or the following general formula (2) is less than 0.20 mol /L of working solution; [化1]

In general formula (1) and general formula (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms. >2> The processing method as in >1>, wherein the working solution to be processed is a part of the working solution withdrawn after the hydrogenation step and before the oxidation step, or is withdrawn after the hydrogenation step and before the oxidation step A part of the working solution is diluted by adding the working solution before the hydrogenation step to obtain the working solution. >3> The processing method as in >1>, wherein the working solution to be processed is a part of the working solution extracted after the extraction step and before the hydrogenation step. >4> The treatment method of any one of >1> to >3>, wherein the concentration of the anthrahydroquinones is 0.05 to 0.10 mol/L. >5> The processing method of any one of >1>～>4>, wherein the working solution to be processed further contains selected from the group consisting of the following general formulas (a)～(e) One of more than one anthraquinone derivatives; [化2]

In general formula (a) to general formula (e), the meaning represented by R is the same as the general formula (1) and (2). >6> The treatment method of any one of >1> to >5>, wherein the R is ethyl, butyl or pentyl. >7> The processing method of any one of >1> to >6>, wherein the working solution to be processed is mixed with an alkali metal compound at a temperature of 0-60°C. >8> The processing method of any one of >1>～>7>, wherein the working solution to be processed and the aqueous solution of the alkali metal compound are the working solution to be processed: aqueous alkali metal compound = 1 or more: 1 (volume) for mixing. >9> The treatment method of any one of >1> to >8>, wherein the alkali metal compound is sodium hydroxide or potassium hydroxide. >10> The treatment method of any one of >1>～>9>, wherein the sodium hydroxide aqueous solution whose concentration of sodium hydroxide is 0.5mol/L or more is mixed. >11> The processing method of any one of >1> to >10>, wherein the working solution to be processed is mixed with the aqueous solution of the alkali metal compound using a line mixer. >12> The treatment method of any one of >1> to >11>, wherein after mixing with an alkali metal compound, an acid is further mixed for post-treatment. >13> The treatment method of >12>, wherein the acid is nitric acid or phosphoric acid. >14> The treatment method such as >12> or >13>, wherein after mixing with the alkali metal compound, an acidic aqueous solution with a concentration of nitric acid or phosphoric acid of 0.20 mol/L or more is mixed. >15> The treatment method of any one of >12>～>14>, wherein a stirring mixer is used for mixing with the acid. >16> The treatment method of any one of >12>～>15>, wherein after mixing the acid, water is further mixed for post-treatment. >17> The treatment method of any one of >12>～>16>, wherein the working solution after the post-treatment and pure water are stirred and left to stand so that the pH of the separated water layer becomes less than 7 Method for post-processing. >18> A method for producing hydrogen peroxide, using a working solution that has been processed by any one of >1>～>17> to produce hydrogen peroxide by the anthraquinone method. [Effects of Invention]

In the treatment method of the present invention, by mixing a working solution containing a specific amount of anthrahydroquinones with an alkali metal compound, the by-product anthraquinone derivatives are regenerated into anthraquinones, and the amount of anthraquinones can be reduced increase.

The present invention is explained in detail below. The following embodiment is an illustration for explaining the present invention, and does not mean that the present invention is limited to only the embodiment. The present invention can be implemented in various forms without exceeding the gist.

The present invention is a method for producing hydrogen peroxide by the anthraquinone method, which treats the working solution accumulated by-products due to continuous use with alkali.

The anthraquinone method uses a working solution obtained by dissolving anthraquinones in an organic solvent.

The anthraquinones used include anthraquinone, tetrahydroanthraquinone, alkylanthraquinone, and alkyltetrahydroanthraquinone. Hereinafter, anthraquinone and alkylanthraquinone may be collectively referred to as (alkyl)anthraquinone. In addition, tetrahydroanthraquinone and alkyltetrahydroanthraquinone are sometimes collectively referred to as (alkyl)tetrahydroanthraquinone. The (alkyl)anthraquinone and (alkyl)tetrahydroanthraquinone may also be a mixture of multiple (alkyl)anthraquinones and (alkyl)tetrahydroanthraquinones. As for (alkyl)anthraquinone, anthraquinone, ethylanthraquinone, tertiary butylanthraquinone, amylanthraquinone, etc. are exemplified. As for (alkyl)tetrahydroanthraquinone, tetrahydroanthraquinone, ethyltetrahydroanthraquinone, tert-butyltetrahydroanthraquinone, pentyltetrahydroanthraquinone, etc. can be illustrated.

As for the alkyl group having anthraquinones, it is preferably an alkyl group having 1 to 10 carbon atoms, and particularly preferably an ethyl, butyl or pentyl group.

As for the organic solvent, either a non-polar solvent or a polar solvent can be used, and a mixed solvent of a non-polar solvent and a polar solvent is preferable. Examples of non-polar solvents include aromatic hydrocarbons, and specifically, benzene or benzene derivatives containing a C1-C5 alkyl substituent. Examples of benzene derivatives include 1,2,4-trimethylbenzene (Pseudocumene). Examples of polar solvents include higher alcohols such as diisobutyl methanol, carboxylic acid esters, tetrasubstituted ureas, cyclic ureas, and trioctyl phosphoric acid. The ideal organic solvent is a combination of aromatic hydrocarbons and higher alcohols, or a combination of aromatic hydrocarbons and cyclohexanol, alkyl cyclohexanol carboxylate or tetra-substituted urea.

In the case of mixing a non-polar organic solvent and a polar organic solvent, the mixing ratio (volume) should preferably be a non-polar organic solvent: polar organic solvent = 9:1～1:9, more preferably 8:2～2:8, especially 4:6～6:4.

Usually, a catalyst obtained by supporting a transition metal on a support is added to the working solution, and it is supplied to the hydrogenation reaction. The support is not particularly limited. For example, it can be selected from the group consisting of silica, silica, alumina, alumina, titania, zirconia, silica, alumina composite oxide, silica and titania composite At least one of oxides, aluminum oxide/titanium dioxide composite oxides, and physical mixtures of these. The support preferably has a total pore volume of 0.2 to 2.0 ml/g. Especially ideal carrier system has a total pore volume of 0.2～2.0ml/g of silica, alumina or silica･alumina composite oxide. In addition, the total pore volume can be measured by mercury intrusion method.

As for the transition metal, it is preferably a support of palladium, rhodium, ruthenium or platinum or a compound thereof, and more preferably a monomer or a compound of palladium. As for the compound, considering that it is easily reduced to a metal under reaction conditions, an oxide is suitable.

The amount of the supported transition metal is usually 0.1-10% by mass relative to the support. It is advisable to use the hydrogenation catalyst loaded with transition metal in an amount of 1-100 g/L in terms of the catalyst slurry concentration in the working solution.

The specific process of the anthraquinone method will be described with reference to Figure 1. In Figure 1, the dynamics of the working solution are represented by solid arrows and one-dot chain arrows. The solid arrow indicates the mainstream of the working solution in the anthraquinone method. The one-dot chain arrow indicates the flow of the following working solution back to the mainstream of the anthraquinone method after being supplied to the steps of alkali treatment and post-treatment: ・A part of the working solution is extracted after the hydrogenation step and before the oxidation step ・A part of the working solution is extracted during the hydrogenation step • After the extraction step and before the hydrogenation step, extract a portion of the working solution.

In the anthraquinone method, first, hydrogen is added to the working solution to perform hydrogenation treatment. In this way, the anthraquinones in the working solution are hydrogenated to generate corresponding anthrahydroquinones (hydrogenation step). Then, the obtained anthrahydroquinones are oxidized with air or a gas containing oxygen to return to anthraquinones. At this time, hydrogen peroxide is generated and dissolved in the working solution (oxidation step). Then, the generated hydrogen peroxide is extracted with water and separated from the working solution (extraction step). The hydrogen peroxide is then supplied to the refining step and the concentration step following the usual method to produce a product. On the other hand, the working solution after the extraction step is supplied to the hydrogenation step, and then repeatedly used in the oxidation step, extraction step...

通式(a)～通式(e)中，R表示氫或碳數1～10之烷基，適宜為表示乙基、丁基或戊基。(Alkali treatment) The working solution for continuous use contains by-products derived from anthraquinones caused by side reactions, for example, one selected from the group consisting of the following general formulas (a) to (e) The above anthraquinone derivatives. [化3]

In general formulas (a) to (e), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and suitably represents an ethyl group, a butyl group, or a pentyl group.

The above-mentioned anthraquinone derivatives do not have the ability to generate hydrogen peroxide. Therefore, regenerating them into anthraquinones with the ability to generate hydrogen peroxide is meaningful from the viewpoint of the production efficiency of hydrogen peroxide production. In the present invention, the continuous use of the working solution and the alkali metal compound are mixed to achieve regeneration into anthraquinones. In this specification, this regeneration treatment using an alkali metal compound is referred to as alkali treatment.

通式(1)及通式(2)中，R表示氫或碳數1～10之烷基，適宜表示乙基、丁基或戊基。In the present invention, what is important is the concentration of the anthrahydroquinones in the working solution for continuous use, that is, the concentration of the anthrahydroquinones represented by the following general formula (1) or the following general formula (2). The stage before the metal compound is mixed does not reach 0.20 mol/L. It has been confirmed in experiments (refer to the following examples and comparative examples) that the working solution of the processing object (sometimes referred to as the working solution to be processed) will make the anthraquinone derivative effectively Regenerate into anthraquinones and increase the amount of anthraquinones. [化4]

In general formula (1) and general formula (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and suitably represents an ethyl group, a butyl group or a pentyl group.

Regarding the reason that the anthrahydroquinones cannot be effectively regenerated into anthraquinones when the anthrahydroquinones are 0.20mol/L or more, the inventors of this case speculate that the anthrahydroquinones are easily dissolved in the aqueous solution of alkali metal compounds. There are too many quinones. Compared with the anthraquinones produced by the regeneration reaction, more anthrahydroquinones will dissolve in the aqueous solution of alkali metal compounds and cause loss. Therefore, regeneration into anthraquinones cannot be achieved.

The concentration of anthrahydroquinones supplied to the working solution to be processed in the alkali treatment is suitably 0.02～0.10 mol/L, especially 0.05～0.10 mol/L. The reason is that if the concentration is within this value range, there is a tendency for the increase rate of anthraquinones expressed by the following formula to be high: Increasing rate of anthraquinones (%) = amount of anthraquinones in the working solution after treatment (mol/L)/total amount of anthraquinones and anthrahydroquinones in the working solution to be treated (mol/L) ×100. Although the reason for the increase in the increase rate of anthraquinones has not yet been determined, the inventors of the present application speculate as follows. The hydrogen added in the hydrogenation step of anthrahydroquinones is highly reactive like hydrogen peroxide from oxygen without a catalyst, and the entire solution becomes a reducing environment. It is considered that the reaction between the reducing environment and the alkaline aqueous solution allows the anthraquinone derivatives (degradants) to be efficiently regenerated into anthraquinones.

The concentration of anthrahydroquinones can be measured using a gas chromatography analyzer (GC) as in the examples described later.

In the present invention, the working solution to be treated, which is the object of alkali treatment, is obtained by extracting a part of the working solution at the stages other than the oxidation step and the extraction step in the hydrogen peroxide production process. After the oxidation step, the working solution before the extraction step has a safety problem because it contains a higher concentration of hydrogen peroxide than the working solution of other steps, and is not treated as a treatment object in principle. The working solution to be treated, specifically, a part of the working solution is extracted after the hydrogenation step and before the oxidation step, a part of the working solution is extracted from the hydrogenation tower during the hydrogenation step, after the extraction step and before the hydrogenation step Take out a part of the working solution, etc.

When the concentration of anthrahydroquinones in the extracted working solution is too concentrated, dilute it. For example, in the working solution extracted after the extraction step and before the hydrogenation step, because it does not contain anthrahydroquinones or even if it contains very little content, the possibility of dilution is low, and it is extracted after the hydrogenation step and before the oxidation step. The working solution, because hydrogenation leads to a large amount of anthrahydroquinones, so there is a high possibility that it needs to be diluted. In terms of dilution, it is preferable to use the working solution after the extraction step and before the hydrogenation step for dilution.

The amount of the working solution to be drawn out can be determined appropriately, usually 0.1-20.0% of the total working solution that flows, especially 1.0-10.0%. If the amount of extraction is too large, the amount of working solution that contributes to the production of hydrogen peroxide decreases, and if it is too small, the alkali treatment effect is insufficient.

The alkali metal used in the alkali treatment may be any alkali metal of Group 1 (Group IA) of the Periodic Table, preferably lithium, sodium or potassium. Specific examples of alkali metal compounds include lithium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium borate, sodium diphosphate, sodium boron dioxide, sodium nitrite, sodium borate trioxide, hydrogen phosphate Sodium, sodium silicate, sodium disilicate, sodium trisilicate, sodium stannate, sodium sulfide, sodium thiosulfate, sodium tungstate, potassium hydroxide, potassium borohydride, potassium carbonate, potassium cyanide, potassium nitrite , Potassium phenate, potassium hydrogen phosphate, potassium diphosphate, potassium stannate, etc. Suitable alkali metal compounds are sodium hydroxide or potassium hydroxide.

The alkali metal compound is usually used in the state of an aqueous solution. It has been experimentally confirmed that the higher the concentration of alkali metal compounds, the higher the increase rate of anthraquinones (not described in this specification). In addition, if the concentration is too low, when the alkali metal compound is separated from the working solution after the treatment, the density difference between the two solutions becomes small, and there is a high possibility that a lot of time is required for separation. Therefore, the concentration of the alkali metal compound in the aqueous solution is preferably 0.5 mol/L or more. The upper limit of the concentration is not particularly limited, and is usually 10.0 mol/L.

The working solution to be processed and the alkali metal compound aqueous solution are usually mixed in an amount of working solution to be processed: alkali metal compound aqueous solution=1 or more:1 (volume), and it is suitable to mix in an amount of 1-30:1 (volume), It is especially suitable to mix in an amount of 1-20:1 (volume).

Regarding the temperature conditions during mixing, the inventors of the present case have conducted experiments and confirmed that the alkali treatment is not affected by temperature. Therefore, the temperature conditions are not particularly limited and can be mixed at any temperature. It is usually carried out at 0-60°C.

The mixing time may be appropriately determined by the manner in which the working solution to be processed and the aqueous alkali metal compound are sufficiently mixed. For example, when stirring and mixing, 3 minutes or more is sufficient. In addition, when mixing in a pipe using a pipe mixer, the mixing time is less than a few seconds in principle, but this effect can still be obtained without any problems. Through experiments by the inventors of the present application, it has been confirmed that even if the mixing time is extended, the increase rate of anthraquinones will not be affected, so the mixing can be terminated at an appropriate time.

(Post-processing) By alkali treatment, a mixture of regeneration working solution and alkali metal compound aqueous solution can be obtained. Alkali metal compounds neutralize with hydrogen peroxide to decompose hydrogen peroxide. However, the decomposition reaction of hydrogen peroxide may cause a rapid increase in pressure or explosion in the plant, and it must be avoided. . For this reason, it is necessary to return the regeneration working solution to the hydrogen peroxide production process after the treatment after the removal of the alkali metal compound.

Specifically, after the regenerated working solution is separated from the aqueous solution of the alkali metal compound by known means such as static separation, at least one of acid treatment and water washing is carried out, preferably both acid treatment and washing, or any of the acid treatments. One is particularly suitable for both acid treatment and water washing. When performing both acid treatment and water washing, it is advisable to proceed in the order of acid treatment and water washing.

The conditions for bringing the mixture of the regeneration working solution and the aqueous alkali metal compound solution into contact with the acid are very important for the safe and stable operation of machinery and equipment.

The acid used in the acid treatment includes acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and nitric acid or phosphoric acid is preferable. This is because the main structure of hydrogen peroxide manufacturing equipment is made of SUS material or aluminum material, and nitric acid and phosphoric acid are not corrosive to these materials. In addition, the reason is that there is no risk of being left in the working solution to poison the hydrogenation catalyst.

The regenerated working solution and the acidic aqueous solution in which the acid is dissolved are stirred and brought into contact with a known means such as a stirring mixer to perform acid treatment. The concentration of the acidic aqueous solution is usually 0.20 mol/L or more. Considering that the alkali metal compound removal effect is particularly excellent, it is preferably more than 0.25 mol/L, more preferably 0.30 mol/L or more, and further preferably 0.35 mol/L or more, It is particularly suitable to be 0.50 mol/L or more. The upper limit of the concentration of the acidic aqueous solution is usually 5.00 mol/L or less, and it is less than 3 mol/L in view of the balance between the removal effect, cost and safety. Pass through inert gas such as nitrogen during stirring. After the stirring, the working solution is separated from the aqueous solution using known means such as static separation.

Water washing is performed by stirring and contacting the regenerated working solution with water by a known means such as a stirring mixer. As far as "water" is concerned, it is preferably distilled water, ion exchange water, water purified by reverse osmosis, etc. The ratio of water to the regenerated working solution is 0.02 parts by volume or more, preferably 0.10 parts by volume or more, relative to 1 part by volume of the working solution. The upper limit is not particularly limited, and is usually 0.50 parts by volume.

The washing time may be appropriately determined so that the working solution and water are sufficiently mixed. For example, when stirring and mixing, mixing for more than 1 minute is sufficient. There is no upper limit for the washing time, and it may be determined appropriately. In addition, it can also be mixed in a pipe using a pipe mixer.

The temperature of the washing water is 0 to 70°C, more preferably 10 to 60°C, and particularly preferably 20 to 50°C.

Passive gas such as nitrogen can also be introduced during stirring. After the stirring, the working solution and water are separated by known techniques such as static separation.

The post-treatment is preferably carried out so that the pH of the water layer obtained by standing and separating the working solution after the post-treatment becomes 7 or less, especially 6 or less.

The regenerated working solution from which alkali metal compounds are removed by post-treatment is returned to the hydrogen peroxide manufacturing process. The stage of return can be determined appropriately. The regeneration working solution also contains anthrahydroquinones in addition to anthraquinones, and anthrahydroquinones may generate hydrogen peroxide through oxidation reaction. Therefore, considering the viewpoint of efficiently using the anthrahydroquinones generated in the hydrogenation step to efficiently produce hydrogen peroxide, it is preferable to return it to the stage after the hydrogenation step and before the oxidation step as shown in FIG. 1.

Although the regeneration of the working solution by alkali treatment has been described so far, the present invention can also combine alkali treatment and known regeneration treatment. For example, in addition to the alkali treatment, a part of the working solution after the extraction step and before the hydrogenation step may be extracted and brought into contact with granular alumina to perform a regeneration reaction. [Example]

The following examples illustrate the present invention more specifically, but the present invention is not limited by the following examples.

>Gas Chromatography (GC) Analysis> Under the following conditions, GC was used to determine and analyze the amylanthraquinone, amyltetrahydroanthraquinone and amylanthrahydroquinones (amylanthrahydroquinone and amyltetrahydroquinone) in the working solutions of the examples and comparative examples. Anthrahydroquinone). Installation: GC-2014 manufactured by Shimadzu Corporation Detector: Flame Dissociation Detector (FID) Analysis column: Rtx-50 manufactured by Restek (Length 30m, inner diameter 0.25mm, film thickness 0.5μm) Carrier gas: He Temperature of sample introduction part: 250℃ Detector temperature: 310℃ Sample import volume: 1μL Split ratio: 50 Heating program: 110℃(maintain for 8 minutes)→heat up 10℃/minute→310℃(maintain for 10 minutes)

>pH measurement> Regarding the residual alkali metal compound in the regeneration working solution after post-treatment, it is judged by the measurement of pH. Specifically, the pH of the water layer obtained by allowing the working solution after the post-treatment to stand still and separated is measured with a pH meter. Installation: pH meter D-74 manufactured by Horiba Manufacturing Co., Ltd. Electrode: pH electrode 9625-10D manufactured by Horiba Manufacturing Co., Ltd. Reagent for pH correction: Neutral phosphate pH standard solution (manufactured by FUJIFILM Wako Pure Chemical Corporation) pH 6.86 Phthalate pH standard solution (manufactured by FUJIFILM Wako Pure Chemical Corporation) pH 4.01 Borate pH standard solution (manufactured by FUJIFILM Wako Pure Chemical Corporation) pH 9.18

>Example 1> (Hydrotreating) Prepare pentylanthraquinone with a concentration of 0.543mol/L, pentyltetrahydroanthraquinone with a concentration of 0.053mol/L, and use a mixed organic solvent (1,2,4-trimethylbenzene: diisobutyl methanol = 55:45) working solution. The working solution is actually a working solution that is repeatedly used in machinery and equipment. Hereinafter, this working solution is referred to as a working solution before hydrogenation. Hydrotreating was performed on this working solution before hydrogenation, and a working solution containing 0.020 mol/L of amylanthrahydroquinones was prepared. Hydrogenation treatment is to take 50 mL of the working solution before hydrogenation and 100 mg of palladium-supported hydrogenation catalyst of silica and alumina into the flask, replace the gas phase with hydrogen, and perform reduction by stirring. The reduction amount (amylanthrahydroquinone concentration) was calculated from the hydrogen absorption amount. After reaching the predetermined amount of hydrogen absorption, use a disposable syringe and a cartridge filter to filter and separate the working solution from the catalyst to obtain a hydrogenated working solution.

(Alkali treatment) The hydrogenated working solution is used as the working solution to be processed and brought into contact with the base. 50 mL of the working solution to be processed was brought into contact with stirring with 50 mL of 1 mol/L sodium hydroxide aqueous solution. Stirring was carried out in a hot water bath at 50°C by introducing nitrogen gas. After 15 minutes, the stirring was stopped, and the working solution was separated from the sodium hydroxide aqueous solution by a separatory funnel to obtain a regenerated working solution A.

(Acid treatment) The obtained regenerated working solution A was stirred and contacted with 50 mL of 1 mol/L nitric acid. Stirring was carried out in a hot water bath at 50°C with nitrogen gas. After 15 minutes, the stirring was stopped, and the working solution was separated from the nitric acid by a separatory funnel to obtain a regenerated working solution B.

(Washed) The obtained regeneration working solution B was brought into contact with 50 mL of pure water with stirring. Stirring was carried out in a hot water bath at 50°C with nitrogen gas. After 15 minutes, the stirring was stopped, and the working solution was separated from the pure water by a separatory funnel to obtain a regenerated working solution C.

>Example 2> A working solution to be treated containing 0.050 mol/L of amylanthrahydroquinones was obtained, and the working solution to be treated was used, except that the hydrogenation treatment, alkali treatment, and acid treatment were performed in the same manner as in Example 1. Treat and wash with water to obtain regeneration working solution C.

>Example 3> A working solution to be treated containing 0.100 mol/L of amylanthrahydroquinone was obtained, and the working solution to be treated was used, except that the hydrogenation treatment, alkali treatment, and acid treatment were performed in the same manner as in Example 1. Treat and wash with water to obtain regeneration working solution C.

>Example 4> A working solution to be treated containing 0.150 mol/L of amylanthrahydroquinones was obtained, and the working solution to be treated was used, except that the hydrogenation treatment, alkali treatment, and acid treatment were carried out in the same manner as in Example 1. Treat and wash with water to obtain regeneration working solution C.

>Example 5> A working solution to be treated with a concentration of 0.000mol/L of amylanthrahydroquinones was obtained, and the working solution to be treated was used, except that the hydrogenation treatment and alkali treatment were performed in the same manner as in Example 1. , Acid treatment and water washing, to obtain regeneration working solution C. The working solution to be treated with a concentration of pentylanthrahydroquinone of 0.000mol/L refers to the working solution obtained by reducing the hydrogen absorption amount to zero in the hydrogenation treatment described in Example 1.

>Comparative Example 1> A working solution to be treated containing 0.200 mol/L of amylanthrahydroquinones was obtained, and the working solution to be treated was used, except that the hydrogenation treatment, alkali treatment, and acid treatment were performed in the same manner as in Example 1. Treat and wash with water to obtain regeneration working solution C.

Table 1 shows the concentration of amylanthraquinone (recorded as AmAQ concentration in the table) and amyltetrahydroanthracene for the working solution before hydrogenation, the working solution to be treated, and the regenerating working solution C obtained in the above examples and comparative examples. Quinone concentration (recorded as AmTHAQ concentration in the table). In addition, for the working solution to be processed, the concentration of amylanthrahydroquinones (recorded as AmHQ concentration in the table) is also displayed. In addition, the increase rate of amylanthraquinones was calculated using the following formula, and the relationship between the increase rate of amylanthraquinones and the concentration of amylanthrahydroquinones in the working solution to be processed is shown in FIG. 2. Increase rate of amylanthraquinones = (AmAQ concentration in regeneration working solution C + AmTHAQ concentration in regeneration working solution C)/(AmAQ concentration in the working solution to be processed + AmTHAQ in the working solution to be processed Concentration + AmHQ concentration in the working solution to be processed)×100

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Working solution before hydrogenation AmAQ concentration (mol/L) 0.543 AmTHAQ concentration (mol/L) 0.053 Working solution after hydrogenation (working solution to be processed) AmAQ concentration (mol/L) 0.543 0.543 0.496 0.446 0.543 0.396 AmTHAQ concentration (mol/L) 0.033 0.003 0.000 0.000 0.053 0.000 AmHQ concentration (mol/L) 0.020 0.050 0.100 0.150 0.000 0.200 Regeneration working solution C AmAQ concentration (mol/L) 0.559 0.572 0.570 0.554 0.545 0.538 AmTHAQ concentration (mol/L) 0.055 0.055 0.049 0.048 0.053 0.049

From these results, it is found that the regeneration amount of amylanthraquinone varies depending on the concentration of amylanthrahydroquinones in the working solution to be processed. In Examples 1 to 5, the concentration of AmAQ in the regeneration working solution C was higher than that in the working solution before hydrogenation (0.543mol/l). The regeneration effect of amylanthraquinone by alkali treatment is excellent when the amylanthrahydroquinone concentration is 0.02 to 0.10 mol/L, especially 0.05 to 0.10 mol/L. In addition, when the concentration of amylanthrahydroquinones is 0.05 to 0.10 mol/L, the hydrogenation rate represented by the following formula is 8 to 16%. Hydrogenation rate (%) = concentration of amylanthrahydroquinones in the working solution to be processed (mol/L) / the total of amylanthraquinone and amyltetrahydroanthraquinone in the working solution before hydrogenation (mol/L )×100 Considering that in alkali treatment without pentyl anthrahydroquinones (no hydrogenation treatment), the concentration of pentyl anthraquinone only rises to 0.545 mol/L, and setting the concentration of pentyl anthrahydroquinones in the above range can be more optimal The regeneration effect of amylanthraquinone without containing amylanthrahydroquinones.

>Example 6> Experiments were performed for mixing with an acid after contact with an alkali metal compound. As mentioned above, in the hydrogen peroxide production process, if the alkali metal compound comes into contact with hydrogen peroxide, the decomposition of hydrogen peroxide is promoted. The decomposition reaction of hydrogen peroxide has the possibility of causing a rapid increase in pressure in machinery and equipment or explosions and other disasters, which must be avoided. In other words, the conditions under which the working solution after contact with alkali metals come into contact with acid are very important for the safe and stable operation of machinery and equipment.

(Hydrotreating) Prepare pentyl anthraquinone with a concentration of 0.543 mol/L and pentyl tetrahydroanthraquinone with a concentration of 0.053 mol/L, and use a mixed organic solvent (1,2,4-trimethylbenzene: diisobutyl methanol = 55:45) working solution. The working solution is actually a working solution that is repeatedly used in machinery and equipment. Hydrotreating is performed on the working solution, and a working solution to be processed containing 0.100 mol/L of amylanthrahydroquinones is prepared. In the hydrogenation process, 500 mL of the working solution before hydrogenation and 1000 mg of hydrogenation catalyst supporting palladium on silica and alumina are collected in a flask, and the gas phase is replaced with hydrogen, and reduction is performed by stirring. The reduction amount (amylanthrahydroquinone concentration) was calculated from the hydrogen absorption amount. After reaching the predetermined amount of hydrogen absorption, use a disposable syringe and cartridge filter to filter and separate the working solution from the catalyst to obtain the working solution to be processed.

(Alkali treatment) Add 500 mL of the working solution to be processed and 25 mL of 2.0 mol/L sodium hydroxide aqueous solution into a 1 L beaker and stir for 5 minutes. Stirring was carried out at 25°C with nitrogen gas. After the stirring is stopped, the working solution and the sodium hydroxide aqueous solution are separated by a separatory funnel to obtain a regenerated working solution D.

(Acid treatment) The obtained regeneration working solution D was brought into contact with 50 mL of 1 mol/L nitric acid with stirring. Stirring was carried out at 25°C with nitrogen gas. After 15 minutes, the stirring was stopped, and the working solution was separated from the nitric acid by a separatory funnel to obtain a regenerated working solution E.

(Washed) The obtained regeneration working solution E was brought into contact with 50 mL of pure water with stirring. Stirring was carried out at 25°C with nitrogen gas. After 5 minutes, the stirring was stopped, and the working solution was separated from the water layer by a separatory funnel.

>Example 7> Except for using 0.5 mol/L nitric acid for the acid treatment, alkali treatment, acid treatment, and water washing were performed in the same manner as in Example 6, and the working solution and the water layer were separated by a separatory funnel.

>Example 8> For the acid treatment, except that 0.35 mol/L nitric acid was used, alkali treatment, acid treatment, and water washing were performed in the same manner as in Example 6, and the working solution was separated from the water layer by a separatory funnel.

>Example 9> Except that 0.25 mol/L nitric acid was used for the acid treatment, alkali treatment, acid treatment, and water washing were performed in the same manner as in Example 6, and the working solution and the water layer were separated by a separatory funnel.

In Table 2 and Figure 3, the pH measurement results are shown for the water layers obtained in the above Examples 6-9. [Table 2] Concentration of nitric acid used in acid treatment The pH of pure water after contact with working solution mol/L - 1.00 1.73 0.50 2.26 0.35 3.29 0.25 11.7

Examples 6-9 obtained a sufficient amount of amylanthraquinones. When the concentration of nitric acid used in the acid treatment is 0.35 mol/L or more, the pH of the pure water after contacting the regeneration working solution is much lower than 7, and the alkali metal compounds are removed from the regeneration working solution. On the other hand, when the concentration of nitric acid is 0.25 mol/L, the pH of the pure water after contacting the regeneration working solution exceeds 7, and some alkali metal compounds remain in the regeneration working solution. Therefore, it means that in order to sufficiently remove alkali metal compounds from the regeneration working solution, nitric acid with a concentration preferably higher than 0.25 mol/L, more preferably 0.35 mol/L or higher, can be used for acid treatment. In addition, it is believed that the more concentrated the nitric acid, the more effective the removal of alkali metal compounds will be. However, considering the balance of removal effect, cost and safety, it is advisable to use nitric acid with a concentration of 0.50mol/L or more and less than 3mol/L for acid deal with.

The above various examples/comparative examples prove that anthraquinones are regenerated by the treatment of the present invention. However, in order to directly prove that the regeneration of anthraquinones is regenerated from by-products (anthraquinone derivatives) to anthraquinones, the following experiment was performed.

>Example 10> With respect to the alkylxanthones represented by the above general formulas (d) to (e), experiments were performed on regeneration of anthraquinones useful in the production of hydrogen peroxide. Specifically, as the working solution before hydrogenation, amylanthraquinone (AmAQ) with a concentration of 0.509mol/L, amylxanthone (AmOX) with a concentration of 0.012mol/L was used, and a mixed organic solvent was used ( Except for the working solution of 1,2,4-trimethylbenzene:diisobutylmethanol=55:45), in the same manner as in Example 1, a regenerated working solution C was obtained. As a result, the concentration of amylanthraquinone (AmAQ) contained in the regeneration working solution C is 0.527 mol/L, and the concentration of amylxanthone (AmOX) is 0.001 mol/L.

The regeneration working solution C series amylxanthone is greatly reduced, and sufficient amylxanthone is regenerated into amylanthraquinone.

>Example 11> Experiments were conducted on the phenomenon that the alkylene oxide tetrahydroanthraquinone represented by the above general formula (a) is regenerated into anthraquinones useful in the production of hydrogen peroxide. Specifically, as a working solution before hydrogenation, a predetermined amount of epoxypentyltetrahydroanthraquinone was dissolved in a mixed organic solvent (1,2,4-trimethylbenzene: diisobutylmethanol=60:40), A working solution of 50 mL containing 0.016 mol/L of epoxypentyl tetrahydroanthraquinone, 0.092 mol/L of pentyl anthraquinone, and 0.000 mol/L of pentyl tetrahydroanthraquinone was carried out in the same manner as in Example 1 except that , Obtain the regeneration working solution C. As a result, the concentration of epoxypentyltetrahydroanthraquinone (AmTHEP) contained in the regeneration working solution C is 0.003mol/L, the concentration of amyltetrahydroanthraquinone (AmTHAQ) is 0.009mol/L, and the concentration of amylanthraquinone (AmTHEP) is 0.009mol/L. The concentration of AmAQ) is 0.094mol/L.

The regeneration working solution C-epoxypentyltetrahydroanthraquinone has been greatly reduced, and the regeneration target of pentyltetrahydroanthraquinone has increased. Therefore, a sufficient regeneration of epoxypentyltetrahydroanthraquinone into pentyltetrahydroanthraquinone can be obtained.

>Example 12> Experiments were conducted on the phenomenon that the alkyl anthrone represented by the above general formulas (b) and (c) are regenerated into anthraquinones useful in the production of hydrogen peroxide. Specifically, because alkyl anthrone is usually contained in a small amount in the working solution of actual machines, tools and equipment, anthrone without an alkyl group (R = hydrogen) (Anthrone, manufactured by FUJIFILM Wako Pure Chemical Corporation, Wako Special Grade) is used. )conduct experiment. However, FUJIFILM Wako Pure Chemical Corporation describes anthrone as Anthrone. As a working solution before hydrogenation, 50mL of a working solution containing a predetermined amount of anthrone dissolved in a mixed organic solvent (1,2,4-trimethylbenzene: diisobutylmethanol=60:40) and containing 0.050mol/L of anthrone Except for this, in the same manner as in Example 1, a regeneration working solution C was obtained. The concentration of anthrone (AN) contained in the regeneration working solution C is 0.032 mol/L, and the concentration of anthraquinone (AQ) is 0.020 mol/L.

The regeneration working solution C series anthrone decreases, and the anthraquinone that is the target of regeneration increases. Therefore, a sufficient effect of regenerating anthrone into anthraquinone can be obtained.

From the foregoing Examples 10 to 12, it was confirmed that epoxypentyltetrahydroanthraquinone, amylxanthone, and anthrone were regenerated into amylanthraquinones. However, since there are other unidentified anthraquinone by-products that are also regenerated into anthraquinones, it is speculated that there is a sufficient possibility to help increase the concentration of anthraquinones in the working solution after alkali treatment.

>Example 13> Instead of using nitric acid, phosphoric acid was used, and the same experiment as in Example 6 was carried out. However, because phosphoric acid is a weaker acid than nitric acid, the number of acid contacts increased from one to two. Specifically, perform the following operations.

(Hydrogenation and alkali treatment) Using the same working solution as in Example 6, hydrogenation treatment and alkali treatment were performed in the same manner as in Example 6, to obtain a regeneration working solution D.

(The first acid treatment) The obtained regeneration working solution D was brought into contact with 50 mL of 1.0 mol/L phosphoric acid with stirring. Stirring was carried out at 25°C with nitrogen gas. After 15 minutes, the stirring was stopped, and the working solution was separated from the phosphoric acid by a separatory funnel to obtain the regenerated working solution E1.

(2nd acid treatment) The obtained regeneration working solution E1 was brought into contact with 50 mL of 1.00 mol/L phosphoric acid with stirring. Stirring was carried out at 25°C with nitrogen gas. After 15 minutes, the stirring was stopped, and the working solution was separated from the phosphoric acid by a separatory funnel to obtain the regenerated working solution E2.

(Washed) The obtained regeneration working solution E2 was brought into contact with 50 mL of pure water while stirring. Stirring was carried out at 25°C with nitrogen gas. After 5 minutes, the stirring was stopped, and the working solution was separated from the water layer by a separatory funnel.

>Example 14> In the second acid treatment, 0.50 mol/L phosphoric acid was used, except that the alkali treatment, acid treatment, and water washing were performed in the same manner as in Example 13, and the working solution and the water layer were separated by a separatory funnel.

>Example 15> Except that 0.25 mol/L phosphoric acid was used for the second acid treatment, alkali treatment, acid treatment, and water washing were performed in the same manner as in Example 13, and the working solution was separated from the water layer by a separatory funnel.

>Example 16> In the second acid treatment, 0.13 mol/L phosphoric acid was used, except for this point, alkali treatment, acid treatment, and water washing were performed in the same manner as in Example 13, and the working solution was separated from the water layer by a separatory funnel.

Table 3 and FIG. 4 show the pH measurement results of the water layers obtained in Examples 13-16. [table 3] Concentration of phosphoric acid used in acid treatment The pH of pure water after contact with working solution mol/L - 1.00 1.89 0.50 2.35 0.25 2.92 0.13 12.03

In Examples 13-16, a sufficient amount of amylanthraquinones was obtained. When the concentration of phosphoric acid used in acid treatment is 0.25 mol/L or more, the pH of the water layer after contacting pure water with the regeneration working solution is much lower than 7, and the alkali metal compounds are sufficiently removed from the regeneration working solution. On the other hand, when the concentration of nitric acid is 0.13 mol/L, the pH of the water layer after contacting pure water with the regeneration working solution exceeds 7, and a part of the alkali metal compound remains in the regeneration working solution. Therefore, in order to sufficiently remove alkali metal compounds from the regeneration working solution, it is advisable to use phosphoric acid with a concentration of 0.25 mol/L or more for acid treatment. In addition, it is believed that the more concentrated the nitric acid, the more effective the removal of alkali metal compounds will be. However, considering the balance of the removal effect, cost and safety, it is known that the concentration of 0.50mol/L or more and less than 3mol/L should be used. Phosphoric acid for acid treatment.

[Fig. 1] A diagram showing an example of the manufacturing method of the present invention. [Figure 2] A graph showing the relationship between the concentration of amylanthrahydroquinones and the increase rate of amylanthraquinones in the working solution to be treated in Examples 1 to 5 and Comparative Example 1. [Figure 3] A graph showing the pH of the water layer obtained in Examples 6-9. [Figure 4] A graph showing the pH of the water layer obtained in Examples 13-16.

Claims (18)

A processing method is a method of processing a working solution that is continuously used in a method of producing hydrogen peroxide by an anthraquinone method including a hydrogenation step, an oxidation step, and an extraction step, and an alkali metal compound. It is characterized in that: as the working solution to be treated before mixing with the alkali metal compound, the concentration of anthrahydroquinone represented by the following general formula (1) or the following general formula (2) is less than 0.20mol/L Working solution

In general formula (1) and general formula (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms. For example, the processing method of item 1 in the scope of the patent application, wherein the working solution to be processed is a part of the working solution extracted after the hydrogenation step and before the oxidation step, or a part of the working solution is extracted after the hydrogenation step and before the oxidation step A part of the working solution is diluted by adding the working solution before the hydrogenation step to obtain the working solution. For example, the processing method of item 1 in the scope of patent application, wherein the working solution to be processed is a part of the working solution extracted after the extraction step and before the hydrogenation step. For example, the treatment method of any one of items 1 to 3 in the scope of patent application, wherein the concentration of the anthrahydroquinones is 0.05 to 0.10 mol/L. For example, the processing method of any one of items 1 to 4 in the scope of patent application, wherein the working solution to be processed further contains selected from the group consisting of the following general formulas (a) to (e) More than one anthraquinone derivative;

In general formula (a) to general formula (e), the meaning represented by R is the same as the general formula (1) and (2). Such as the processing method of any one of items 1 to 5 in the scope of patent application, wherein the R is ethyl, butyl or pentyl. For example, the processing method of any one of items 1 to 6 in the scope of patent application, wherein the working solution to be processed is mixed with an alkali metal compound at a temperature of 0-60°C. For example, the processing method of any one of items 1 to 7 in the scope of patent application, wherein the working solution to be processed and the aqueous solution of the alkali metal compound are the working solution to be processed: aqueous alkali metal compound solution = 1 or more :1 (volume) for mixing. For example, the processing method of any one of items 1 to 8 in the scope of patent application, wherein the alkali metal compound is sodium hydroxide or potassium hydroxide. For example, the processing method of any one of items 1 to 9 in the scope of patent application, wherein the sodium hydroxide aqueous solution with the concentration of sodium hydroxide above 0.5 mol/L is mixed. For example, the processing method of any one of items 1 to 10 in the scope of patent application, wherein the working solution to be processed is mixed with the aqueous solution of the alkali metal compound using a line mixer. Such as the treatment method of any one of items 1 to 11 in the scope of patent application, wherein after mixing with an alkali metal compound, an acid is further mixed for post-treatment. Such as the processing method of item 12 of the scope of patent application, wherein the acid is nitric acid or phosphoric acid. For example, the treatment method of item 12 or 13 in the scope of patent application, wherein after mixing with an alkali metal compound, an acidic aqueous solution with a concentration of nitric acid or phosphoric acid of 0.20 mol/L or more is mixed. Such as the processing method of any one of items 12 to 14 in the scope of patent application, wherein a stirring mixer is used for mixing with the acid. For example, the treatment method of any one of items 12 to 15 in the scope of patent application, wherein after mixing the acid, water is further mixed for post-treatment. For example, the processing method of any one of items 12 to 16 in the scope of the patent application, wherein the working solution after the post-treatment and pure water are stirred and left to stand so that the pH of the separated water layer becomes 7 or less Post-processing. A method for producing hydrogen peroxide is to produce hydrogen peroxide by the anthraquinone method using a working solution that has been processed by any one of the treatment methods in the scope of patent application 1 to 17.

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