KR20210093846A - How to treat the working solution - Google Patents

Abstract

It is an object of the present invention to treat a working solution to increase the amount of anthraquinones by regenerating by-products derived from anthraquinones and having no hydrogen peroxide generating ability into anthraquinones contained in a working solution that is used repeatedly. to provide a way According to the present invention, there is provided a method of treating a working solution continuously used in a method for producing hydrogen peroxide by an anthraquinone method including a hydrogenation step, an oxidation step and an extraction step by mixing with an alkali metal compound, an alkali metal compound and A treatment method, characterized in that, as the working solution to be treated before mixing, a working solution having an anthrahydroquinone concentration represented by the following general formula (1) or (2) of less than 0.20 mol/L is used. provided (in general formulas (1) and (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms).

Description

How to treat the working solution

The present invention relates to a method for treating a working solution used for the production of hydrogen peroxide by the anthraquinone method, and to a method for producing hydrogen peroxide using the treated working solution. Specifically, a treatment method for regenerating anthraquinone derivatives having no hydrogen peroxide generating ability into anthraquinones such as alkylanthraquinone and alkyltetrahydroanthraquinone by mixing a repeatedly used working solution with an alkali metal compound, and treatment It relates to a method for the production of hydrogen peroxide using a working solution.

The main production method of hydrogen peroxide currently being industrially used is anthraquinone, tetrahydroanthraquinone, alkylanthraquinone or alkyltetrahydroanthraquinone (hereinafter, collectively referred to as anthraquinones) as a reaction medium, It is an anthraquinone method. Anthraquinones are normally used in the state melt|dissolved in two types of mixed solvents of a polar organic solvent and a non-polar organic solvent. The solution prepared by dissolving anthraquinones in this mixed solvent is called a working solution.

The anthraquinone method mainly consists of a hydrogenation process, an oxidation process, and an extraction process. The hydrogenation step is a step of hydrogenating anthraquinones in a working solution in the presence of a catalyst to generate corresponding anthrahydroquinones. In the subsequent oxidation step, the obtained anthrahydroquinones are oxidized with air or a gas containing oxygen to return to the anthraquinones. At this time, hydrogen peroxide is generated and dissolved in the working solution. In the subsequent extraction process, the hydrogen peroxide produced is extracted with water and separated from the working solution. The working solution after the extraction step is returned to the hydrogenation step again, and is continuously used for the oxidation step and the extraction step...

While the hydrogen peroxide production process is repeated, in the working solution, anthraquinones such as anthrone, oxyanthrone, tetrahydroanthraquinoneepoxide, alkylanthrone, alkyloxyanthrone, and alkyltetrahydroanthraquinoneepoxide are caused by side reactions. derivatives are formed. The anthraquinone derivative does not produce hydrogen peroxide even when subjected to a hydrogenation step and an oxidation step. Although the amount of by-products of the anthraquinone derivative is very small per pass, it accumulates in the working solution while repeating the hydrogen peroxide production process, causing various disturbances.

As a technique for regenerating anthraquinones usable in the hydrogen peroxide production process from by-produced anthraquinone derivatives, Patent Document 1 discloses that an inactive component (anthraquinone derivative as a by-product) is converted into alkyltetrahydro by treating a working solution with an alkali and aqueous alkali solution. A technique for conversion to anthraquinones has been proposed. However, the technique of patent document 1 requires a long-time reaction. In addition, since the alkyltetrahydroanthraquinone converted from the inactive component is recovered by crystallization, in order to use the recovered alkyltetrahydroanthraquinone for the production of hydrogen peroxide again, it is necessary to dissolve it in a solvent to prepare a working solution again. there is. Therefore, when the technique of patent document 1 considers the complexity of the installation and operation, it is a technique with very bad efficiency. Therefore, it has been desired to establish a technique for regenerating by-product anthraquinone derivatives that is a short-time reaction and does not require complicated treatment steps such as crystallization.

In addition, in Patent Document 2, in order to convert an alkyltetrahydroanthraquinone epoxide, which is an anthraquinone derivative that does not contribute to the production of hydrogen peroxide, into an alkyltetrahydroanthraquinone useful for the production of hydrogen peroxide, a liquid containing an alkylanthrahydroquinone is used. , a method of contacting with a solid catalyst including alumina oxide has been proposed. However, since the method of patent document 2 requires a high concentration of alkylanthrahydroquinone, it reduces the efficiency of hydrogen peroxide production remarkably. Moreover, reaction conditions are high temperature exceeding 100 degreeC, and it is a long time of 1 to 20 hours. Therefore, there has been a demand for a technology for regenerating by-product anthraquinone derivatives that can be carried out in a short reaction time at a low reaction temperature without lowering the efficiency of hydrogen peroxide production.

Japanese Patent Publication No. 39-8806 Japanese Patent Publication No. 43-11658

Therefore, there is a need for a method for treating a working solution that increases the amount of anthraquinones by regenerating by-products derived from anthraquinones and having no hydrogen peroxide generating ability into anthraquinones contained in a working solution that is used repeatedly. is becoming

That is, this invention is as follows.

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

[Formula 1]

(In general formulas (1) and (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms)

<2> With respect to the working solution obtained after the hydrogenation step and partially extracted before the oxidation step, or after the hydrogenation step and partially extracted before the oxidation step, the working solution before the hydrogenation step The treatment method according to <1> above, wherein the solution is added and diluted.

<3> The treatment method according to <1>, wherein the working solution to be treated is a working solution partially extracted after the extraction step and before the hydrogenation step.

<4> The treatment method according to any one of <1> to <3>, wherein the concentration of the anthrahydroquinones is 0.05 to 0.10 mol/L.

<5> Any one of <1> to <4>, wherein the working solution to be treated further contains at least one anthraquinone derivative selected from the group consisting of the following general formulas (a) to (e) The treatment method described in one.

[Formula 2]

(In general formulas (a) to (e), R has the same meaning as the general formulas (1) and (2) above)

<6> The processing method according to any one of <1> to <5>, wherein R is an ethyl group, a butyl group, or an amyl group.

<7> The treatment method according to any one of <1> to <6>, wherein the working solution to be treated is mixed with an alkali metal compound at a temperature of 0 to 60°C.

<8> Any of <1> to <7>, wherein the working solution to be treated and the aqueous solution of the alkali metal compound are mixed in an amount of working solution to be treated: aqueous alkali metal compound = 1 or more: 1 (volume) The treatment method described in one.

The <9> processing method in any one of said <1>-<8> whose said alkali metal compound is sodium hydroxide or potassium hydroxide.

<10> The processing method in any one of said <1>-<9> in which the density|concentration of sodium hydroxide mixes the sodium hydroxide aqueous solution 0.5 mol/L or more.

<11> The treatment method according to any one of <1> to <10>, wherein the working solution to be treated is mixed with the aqueous solution of the alkali metal compound using a line mixer.

After mixing with <12> alkali metal compound, the processing method in any one of said <1>-<11> which mixes an acid and performs post-processing.

<13> The treatment method according to the above <12>, wherein the acid is nitric acid or phosphoric acid.

<14> The treatment method according to <12> or <13>, in which an acidic aqueous solution having a concentration of nitric acid or phosphoric acid of 0.20 mol/L or more is further mixed after mixing with the <14> alkali metal compound.

<15> The processing method in any one of said <12>-<14> which performs mixing with an acid using a stirring mixer.

After mixing the <16> said acid, the processing method in any one of said <12>-<15> which further mixes water and post-processes.

<17> according to any one of <12> to <16>, wherein the working solution after the post-treatment is stirred with pure water to stand still, and post-treatment is performed so that the pH of the separated aqueous layer is 7 or less processing method.

<18> A method for producing hydrogen peroxide, comprising producing hydrogen peroxide by an anthraquinone method using the working solution treated by the method according to any one of <1> to <17>.

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 anthraquinone derivative as a by-product is regenerated into anthraquinones to increase the amount of anthraquinones. can

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the manufacturing method of this invention.
Fig. 2 is a diagram showing the relationship between the concentration of amylanthrahydroquinones and the rate of increase of amylanthraquinones in the working solutions to be treated in Examples 1 to 5 and Comparative Example 1.
3 : is a figure which shows the pH of the aqueous layer obtained in Examples 6-9.
4 : is a figure which shows the pH of the aqueous layer obtained in Examples 13-16.

Hereinafter, the present invention will be described in detail. The following embodiment is an illustration for demonstrating this invention, and it is not the meaning to limit this invention only to this embodiment. The present invention can be embodied in various forms without departing from the gist thereof.

The present invention is that, in a method for producing hydrogen peroxide by anthraquinone method, a working solution in which by-products have accumulated due to continuous use is treated with an alkali.

In the anthraquinone method, a working solution in which anthraquinones are dissolved in an organic solvent is used.

As anthraquinones to be used, anthraquinone, tetrahydroanthraquinone, alkylanthraquinone, and alkyltetrahydroanthraquinone are mentioned. Hereinafter, anthraquinone and alkylanthraquinone may be generically called (alkyl)anthraquinone. Moreover, tetrahydroanthraquinone and alkyltetrahydroanthraquinone may be generically called (alkyl)tetrahydroanthraquinone in some cases. Each of (alkyl)anthraquinone and (alkyl)tetrahydroanthraquinone may be a mixture of a plurality of (alkyl)anthraquinone and (alkyl)tetrahydroanthraquinone. As (alkyl) anthraquinone, anthraquinone, ethyl anthraquinone, t-butyl anthraquinone, an amyl anthraquinone, etc. are illustrated. Examples of the (alkyl)tetrahydroanthraquinone include tetrahydroanthraquinone, ethyltetrahydroanthraquinone, t-butyltetrahydroanthraquinone, and amyltetrahydroanthraquinone.

As an alkyl group which anthraquinones have, a C1-C10 alkyl group is preferable, and an ethyl group, a butyl group, or an amyl group is especially preferable.

As the organic solvent, although both a non-polar solvent and a polar solvent can be used, a mixed solvent of a non-polar solvent and a polar solvent is preferable. Examples of the non-polar solvent include aromatic hydrocarbons, specifically, benzene or a benzene derivative containing an alkyl substituent having 1 to 5 carbon atoms. As a benzene derivative, pseudocumene is mentioned, for example. Examples of the polar solvent include higher alcohols such as diisobutylcarbinol, carboxylate esters, tetrasubstituted urea, cyclic urea, and trioctyl phosphoric acid. A preferable organic solvent is a combination of an aromatic hydrocarbon and a higher alcohol, or a combination of an aromatic hydrocarbon and a carboxylic acid ester of cyclohexanol or alkylcyclohexanol or tetrasubstituted urea.

When mixing the non-polar organic solvent and the polar organic solvent, the mixing ratio (volume) is preferably non-polar organic solvent: polar organic solvent = 9: 1 to 1: 9, more preferably 8: 2 to 2: 8, and 4 :6-6:4 is especially preferable.

Usually, a catalyst in which a transition metal is supported on a carrier is added to the working solution and subjected to hydrogenation reaction. The carrier is not particularly limited, and for example, from the group consisting of silica, silica-alumina, alumina, titania, zirconia, silica-alumina composite oxide, silica-titania composite oxide, alumina-titania composite oxide, and physical mixtures thereof. At least one selected may be used. The carrier preferably has a total pore volume of 0.2 to 2.0 ml/g. Particularly preferred carriers are silica, alumina or silica-alumina complex oxide having a total pore volume of 0.2 to 2.0 ml/g. In addition, the total pore volume can be measured by the mercury intrusion method.

As a transition metal, the single-piece|unit or its compound of palladium, rhodium, ruthenium, or platinum is preferable, and the single-piece|unit or its compound of palladium is more preferable. As a compound, an oxide is preferable from a viewpoint of being easily reduced under reaction conditions to become a metal.

It is preferable that the transition metal is usually supported in an amount of 0.1 to 10 mass% with respect to the carrier. The hydrogenation catalyst carrying the transition metal is preferably used in an amount of 1 to 100 g/L as the catalyst slurry concentration in the working solution.

The specific process of the anthraquinone method is demonstrated, referring FIG. In Fig. 1, the movement of the working solution is indicated by a solid arrow and a dashed-dotted arrow. The solid arrow indicates the mainstream of the working solution in the anthraquinone method. The dashed-dotted arrows indicate the following working solutions:

· Working solution after hydrogenation process and partly extracted before oxidation process

· Working solution partially extracted during the hydrogenation process

· Working solution extracted in part after the extraction process and before the hydrogenation process

This shows a flow returning to the mainstream of the anthraquinone method after being subjected to the steps of alkali treatment and post-treatment.

In the anthraquinone method, first, a hydrogenation treatment in which hydrogen is added to the working solution is performed. Thereby, anthraquinones in the working solution are hydrogenated to produce corresponding anthrahydroquinones (hydrogenation step). Next, the obtained anthrahydroquinones are oxidized with air or a gas containing oxygen to return to the anthraquinones. At this time, hydrogen peroxide is generated and dissolved in the working solution (oxidation step). Then, the produced hydrogen peroxide is extracted with water and separated from the working solution (extraction process). The hydrogen peroxide is then supplied to a purification process and a concentration process according to a conventional method to be commercialized. On the other hand, the working solution after the extraction step is provided for the hydrogenation step, and thereafter, it is repeatedly used for the oxidation step and the extraction step.

(alkaline treatment)

The continuously used working solution contains anthraquinone-derived by-products, for example, at least one anthraquinone derivative selected from the group consisting of the following general formulas (a) to (e) by a side reaction.

[Formula 3]

(In general formulas (a) to (e), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, preferably an ethyl group, a butyl group or an amyl group)

The anthraquinone derivatives described above do not have the ability to produce hydrogen peroxide. Therefore, regenerating these into anthraquinones having the ability to produce hydrogen peroxide is meaningful in terms of production efficiency of hydrogen peroxide production. In the present invention, regeneration to anthraquinones is realized by mixing a continuously used working solution with an alkali metal compound. In this specification, the regeneration process using this alkali metal compound is called alkali treatment.

In the present invention, the concentration of anthrahydroquinones in the continuously used working solution, that is, the concentration of anthrahydroquinones represented by the following general formula (1) or the following general formula (2), is determined by mixing with the alkali metal compound. In the previous step, it is important that it is less than 0.20 mol/L. It is experimentally proven that the anthraquinone derivative is effectively regenerated into anthraquinones and the amount of anthraquinones increases when the working solution to be treated (sometimes referred to as a working solution to be treated) satisfies the above conditions. (refer to Examples and Comparative Examples to be described later).

[Formula 4]

(In the general formulas (1) and (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, preferably an ethyl group, a butyl group or an amyl group)

As the reason that effective regeneration to anthraquinones cannot be realized when the anthrahydroquinones are 0.20 mol/L or more, the present inventors have found that anthrahydroquinones are easily dissolved in an aqueous solution of an alkali metal compound. If is excessive, more anthrahydroquinones than the anthraquinones generated in the regeneration reaction are dissolved in the aqueous solution of the alkali metal compound and are lost, so it is presumed that the regeneration to the anthraquinones is not realized.

The concentration of anthrahydroquinones in the working solution to be treated for alkali treatment is preferably 0.02 to 0.10 mol/L, and particularly preferably 0.05 to 0.10 mol/L. When the concentration is within these numerical ranges, the rate of increase of anthraquinones represented by the following formula:

Increase 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) x 100

This is because it tends to be high. Although the reason why the increase rate of anthraquinones rises is not certain, the present inventors guess as follows. The hydrogen added in the hydrogenation process of anthrahydroquinones is highly reactive enough to generate|generate hydrogen peroxide from oxygen without a catalyst, and the whole solution becomes a reducing atmosphere. It is considered that the anthraquinone derivative (degraded product) is efficiently regenerated into anthraquinones by reaction of this reducing atmosphere and aqueous alkali solution.

The concentration of anthrahydroquinones can be measured using a gas chromatography analyzer (GC), as is carried out in the Examples described later.

In the present invention, the working solution to be treated with the alkali is a part of the working solution obtained from the hydrogen peroxide manufacturing process, except for the step after the oxidation process and before the extraction process. After the oxidation process, the working solution before the extraction process contains a high concentration of hydrogen peroxide compared to the working solution of other processes, so there is a safety problem, so in principle, it is not treated. Specifically, the working solution to be treated includes a working solution partially extracted after the hydrogenation process and before the oxidation process, a working solution partially extracted from the hydrogenation column during the hydrogenation process, and a part after the extraction process and before the hydrogenation process. and the extracted working solution.

When the concentration of anthrahydroquinones in the extracted working solution is too high, dilution is carried out. For example, anthrahydroquinones are not contained in the working solution extracted after the extraction process and before the hydrogenation process, or even if they are contained, there is little possibility that dilution will be required, but after the hydrogenation process and the oxidation process The previously extracted working solution is highly likely to require dilution because many anthrahydroquinones are generated by hydrogenation. For dilution, it is preferable to use the working solution after the extraction step and before the hydrogenation step.

The amount of the working solution to be extracted may be appropriately determined. Usually, 0.1 to 20.0% of the total working solution flowing, particularly preferably 1.0 to 10.0%. If the amount extracted is excessive, the amount of the working solution contributing to hydrogen peroxide production will decrease, and if it is too small, the alkali treatment effect will become insufficient.

The alkali metal used for the alkali treatment should just be an alkali metal of Group 1 (Group Ia) of the periodic table, and lithium, sodium or potassium is preferable. Specific examples of the alkali metal compound include lithium hydroxide, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, sodium borate, sodium diphosphate, sodium boron dioxide, sodium nitrite, sodium trioxide borate, sodium hydrogen phosphate, sodium silicate, sodium disilicate, sodium trisilicate, sodium tartrate, sodium sulfide, sodium thiosulfate, sodium tungstate, potassium hydroxide, potassium borohydride, potassium carbonate, potassium cyanide, potassium nitrite, potassium phenoxide, potassium hydrogen phosphate, potassium diphosphate, potassium tartrate, etc. can Preferred alkali metal compounds are sodium hydroxide or potassium hydroxide.

The alkali metal compound is usually used in an aqueous solution state. It has been experimentally confirmed that the increase rate of anthraquinones improves as the concentration of the alkali metal compound increases (not disclosed herein). In addition, when the concentration is too low, when the alkali metal compound and the working solution are separated after treatment, the difference in density between the two solutions is small, and there is a high possibility that a long time is required for the separation. Therefore, it is preferable that the density|concentration in the aqueous solution of an alkali metal compound shall be 0.5 mol/L or more. The upper limit of the concentration is not particularly limited, but is usually 10.0 mol/L.

The working solution to be treated and the aqueous alkali metal compound aqueous solution are usually mixed in an amount of the working solution to be treated: aqueous alkali metal compound solution = 1 or more: 1 (volume), preferably 1 to 30:1 (volume). It is mixed in an amount, particularly preferably in an amount of 1 to 20:1 (volume).

As a result of the present inventors examining by experiment about the temperature condition at the time of mixing, it is confirmed that temperature does not affect alkali treatment. Therefore, there is no restriction|limiting in particular in temperature conditions, What is necessary is just to implement mixing at arbitrary temperature. What is necessary is just to implement at 0-60 degreeC normally.

The mixing time may be appropriately determined so that the working solution to be treated and the aqueous alkali metal compound solution are sufficiently mixed. For example, when stirring and mixing, mixing for 3 minutes or longer is sufficient. Moreover, in the case of mixing in piping using a line mixer, in principle, the mixing time is less than a few seconds, but this effect can be obtained without any problems. What is necessary is just to complete mixing at an appropriate timing, since it is confirmed that it does not affect the increase rate of anthraquinones even if it lengthens mixing time by the experiment of the present inventors.

(After treatment)

By the alkali treatment, a mixed solution of a working solution for regeneration and an aqueous alkali metal compound solution is obtained. Alkali metal compounds cause a neutralization reaction with hydrogen peroxide to decompose hydrogen peroxide. This decomposition reaction of hydrogen peroxide may cause disasters such as sudden rise in pressure or explosion in the plant, and must be absolutely avoided. Therefore, it is necessary to return the regeneration working solution to the hydrogen peroxide production process after performing a post-treatment to remove the alkali metal compound.

Specifically, after separating the regeneration working solution and the aqueous solution of the alkali metal compound by using a known means such as stationary separation, at least one of acid treatment and water washing is further performed, preferably acid treatment or acid treatment Either of and water washing are performed, Especially preferably, both acid treatment and water washing are performed. When performing both acid treatment and water washing, it is preferable to carry out in order of acid treatment and water washing.

Conditions for bringing the mixture of the regeneration working solution and the aqueous alkali metal compound solution into contact with an acid are very important for the safety and stable operation of the plant.

Examples of the acid used for the acid treatment include acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and nitric acid or phosphoric acid is preferable. Although the material of the main structure of a hydrogen peroxide manufacturing plant is SUS material and an aluminum material, it is because nitric acid and phosphoric acid do not have corrosiveness with respect to these materials. This is because there is no fear of remaining in the working solution and poisoning the hydrogenation catalyst.

The acid treatment is carried out by stirring and contacting the regeneration working solution and the acidic aqueous solution in which the acid is dissolved by a known means such as a stirring mixer. The acidic aqueous solution concentration is usually 0.20 mol/L or more, but from the viewpoint of particularly excellent effect of removing alkali metal compounds, it is preferably higher than 0.25 mol/L, more preferably 0.30 mol/L or more, still more preferably Preferably it is 0.35 mol/L or more, Especially preferably, it is 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 is less than 3 mol/L from the viewpoint of the balance between the removal effect and the cost and safety. What is necessary is just to vent inert gas, such as nitrogen, during stirring. After completion of the stirring, the working solution and the aqueous solution are separated using known means such as stationary separation.

Washing with water is carried out by stirring and contacting the regeneration working solution and water by a known means such as a stirring mixer. As "water", distilled water, ion-exchanged water, water purified by a reverse osmosis method or the like is preferable. The ratio of water to regeneration working solution is at least 0.02 parts by volume, preferably at least 0.10 parts by volume, of water to 1 part by volume of working solution. Although there is no particular upper limit, it is normally 0.50 volume part.

The water washing time may be appropriately determined so that the working solution and water are sufficiently mixed. For example, when stirring and mixing, mixing for 1 minute or longer is sufficient. There is no upper limit for the washing time, and what is necessary is just to determine suitably. Moreover, you may perform mixing in piping using a line mixer.

The temperature of the water to wash is 0-70 degreeC, More preferably, it is 10-60 degreeC, Especially preferably, it is 20-50 degreeC.

What is necessary is just to vent inert gas, such as nitrogen, during stirring. After completion of the stirring, the working solution and water are separated by a known technique such as stationary separation.

The post-treatment is preferably performed so that the working solution after the post-treatment is left still and the pH of the separated aqueous layer is 7 or less, particularly 6 or less.

The regeneration working solution from which the alkali metal compound has been removed by the post-treatment is returned to the hydrogen peroxide production process. The step of returning may be appropriately determined. The regeneration working solution also contains anthrahydroquinones in addition to anthraquinones, and the anthrahydroquinones can produce hydrogen peroxide by oxidation. Therefore, from the viewpoint of efficiently producing hydrogen peroxide by effectively using the anthrahydroquinones produced in the hydrogenation step, it is preferable to return to the oxidation step after the hydrogenation step as shown in FIG. 1 .

Although the regeneration of the working solution by alkali treatment has been described so far, in the present invention, alkali treatment and known regeneration treatment may be combined. For example, separately from the alkali treatment, a regeneration reaction in which a part of the working solution is extracted after the extraction step and before the hydrogenation step is brought into contact with granular alumina may be performed.

Example

The present invention will be more specifically described below by way of examples, but the present invention is not limited by the following examples.

<Gas chromatography (GC) analysis>

Amylanthraquinone, amyltetrahydroanthraquinone and amylanthrahydroquinones (amylanthraquinone and amyltetrahydroanthrahydroquinone) in the working solutions in Examples and Comparative Examples were measured by GC under the following conditions and analyzed. .

Apparatus: GC-2014 manufactured by Shimadzu Corporation

Detector: Hydrogen Salt Ionization Detector (FID)

Analysis column: Rtx-50 manufactured by Restek

(length 30 m, inner diameter 0.25 mm, film thickness 0.5 μm)

Carrier gas: He

Sample inlet temperature: 250 ℃

Detector temperature: 310℃

Sample introduction amount: 1 μl

Split ratio: 50

Temperature increase program: 110 ℃ (keep 8 minutes) → increase temperature 10 ℃/min → 310 ℃ (keep 10 minutes)

<pH measurement>

The residual alkali metal compound in the regeneration working solution after the post-treatment was judged by measuring the pH. Specifically, the working solution after the post-treatment was left still, and the pH of the separated aqueous layer was measured with a pH meter.

Apparatus: pH meter D-74 manufactured by Horiba Mfg.

Electrode: pH electrode 9625-10D manufactured by Horiba Mfg.

Reagents for pH calibration:

Neutral phosphate pH standard solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) pH 6.86

Phthalate pH standard solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) pH 4.01

Borate pH standard solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) pH 9.18

<Example 1>

(hydrogenation treatment)

Contains amylanthraquinone at a concentration of 0.543 mol/L, and contains amyltetrahydroanthraquinone at a concentration of 0.053 mol/L, and a mixed organic solvent (pseudocumene: diisobutylcarbinol=55:45) A working solution using This working solution was actually a working solution that had been repeatedly used in the plant. Hereinafter, this working solution is referred to as a working solution before hydrogenation.

This working solution before hydrogenation was subjected to hydrogenation treatment to prepare a working solution containing 0.020 mol/L of amylanthrahydroquinones. In the hydrogenation treatment, 50 ml of the working solution before hydrogenation and 100 mg of a hydrogenation catalyst in which palladium was supported on silica/alumina were collected in a flask, hydrogen was replaced in the gas phase, and reduced by stirring. The reduction amount (amylanthrahydroquinone concentration) was calculated from the hydrogen absorption amount. After reaching a predetermined hydrogen absorption amount, the working solution was separated from the catalyst by filtration using a disposable syringe and a cartridge filter to obtain a working solution in which the hydrogenation reaction was completed.

(alkaline treatment)

The working solution in which the hydrogenation reaction was completed was used as a working solution to be treated and brought into contact with alkali. 50 ml of the working solution to be treated was brought into stirring contact with 50 ml of a 1 mol/L aqueous sodium hydroxide solution. Stirring was carried out on a 50°C hot water bath by venting nitrogen. After 15 minutes, stirring was stopped, and the working solution and the aqueous sodium hydroxide solution were separated by a separatory funnel to obtain a regenerated working solution A.

(acid treatment)

The obtained regeneration working solution A was brought into stirring contact with 50 ml of 1 mol/L nitric acid. Stirring was carried out on a 50°C hot water bath by venting nitrogen. After 15 minutes, stirring was stopped, and the working solution and nitric acid were separated with a separatory funnel to obtain a regenerated working solution B.

(wash)

The obtained regeneration working solution B was brought into stirring contact with 50 ml of pure water. Stirring was carried out on a 50°C hot water bath by venting nitrogen. After 15 minutes, stirring was stopped, and the working solution and pure water were separated by a separatory funnel to obtain a regenerated working solution C.

<Example 2>

Hydrogenation treatment, alkali treatment, acid treatment and washing with water were carried out in the same manner as in Example 1 except that a working solution to be treated containing 0.050 mol/L of amylanthrahydroquinones was obtained and used, and regeneration working solution C got

<Example 3>

Hydrogenation treatment, alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 1 except that a working solution to be treated containing 0.100 mol/L of amylanthrahydroquinones was obtained, and this was used. got

<Example 4>

Hydrogenation treatment, alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 1 except that a working solution to be treated containing 0.150 mol/L of amylanthrahydroquinones was obtained, and this was used. got

<Example 5>

Hydrogenation treatment, alkali treatment, acid treatment and washing with water were carried out in the same manner as in Example 1, except that a working solution to be treated having a concentration of amylanthrahydroquinones of 0.000 mol/L was obtained and this was used to obtain a regenerated working solution. C was obtained. The working solution to be treated having a concentration of amylanthrahydroquinones of 0.000 mol/L is a working solution obtained by setting the hydrogen absorption to zero in the hydrogenation treatment described in Example 1.

<Comparative Example 1>

Hydrogenation treatment, alkali treatment, acid treatment and washing with water were carried out in the same manner as in Example 1 except that a working solution to be treated containing 0.200 mol/L of amylanthrahydroquinones was obtained and used, and regeneration working solution C got

Table 1 shows the amylanthraquinone concentrations (referred to as AmAQ concentrations in the table) and amyltetrahydroanthraquinone concentrations for the working solution before hydrogenation, the working solution to be treated, and the working solution C for regeneration obtained in the above Examples and Comparative Examples. (in the table, it is described as AmTHAQ concentration) is shown. In addition, for the working solution to be treated, the concentration of amylanthrahydroquinones (described as the concentration of AmHQ in the table) is also shown.

Furthermore, 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 treated 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 working solution to be treated + AmTHAQ concentration in working solution to be treated + AmHQ concentration in working solution to be treated ) × 100

From these results, it was found that the amount of amylanthraquinone regenerated varies depending on the concentration of amylanthrahydroquinones in the working solution to be treated. In Examples 1 to 5, the AmAQ concentration in the regeneration working solution C was higher than in the working solution before hydrogenation (0.543 mol/L). The amylanthraquinone regeneration effect by the alkali treatment was excellent when the amylanthrahydroquinone concentration was in the range of 0.02 to 0.10 mol/L, particularly 0.05 to 0.10 mol/L. Moreover, when the amylanthrahydroquinones concentration was 0.05-0.10 mol/L, the hydrogenation rate represented by a following formula was 8 to 16 %.

Hydrogenation rate (%) = Concentration of amylanthrahydroquinones in the working solution to be treated (mol/L)/sum of amylanthraquinone and amyltetrahydroanthraquinone in the working solution before hydrogenation (mol/L) x 100

In alkali treatment not containing amylanthrahydroquinones (no hydrogenation treatment), the amylanthraquinone concentration only increases to 0.545 mol/L, so by making the amylanthrahydroquinone concentration within the above range, amylanthrahydroquinone The amylanthraquinone regeneration effect exceeding the condition in which non-non-current was not contained was obtained.

<Example 6>

An experiment was conducted about mixing with an acid carried out after contact with an alkali metal compound. As described above, in the hydrogen peroxide production process, when the alkali metal compound comes into contact with hydrogen peroxide, decomposition of hydrogen peroxide is promoted. This decomposition reaction of hydrogen peroxide may cause a disaster such as a sudden rise in pressure or an explosion in the plant, and must be avoided. In short, the conditions for bringing the working solution into contact with the acid after contact with the alkali metal are very important for the safety and stable operation of the plant.

(hydrogenation treatment)

Contains amylanthraquinone at a concentration of 0.543 mol/L, and contains amyltetrahydroanthraquinone at a concentration of 0.053 mol/L, and a mixed organic solvent (pseudocumene: diisobutylcarbinol=55:45) A working solution using This working solution was actually a working solution that had been repeatedly used in the plant. This working solution was subjected to hydrogenation treatment to prepare a working solution to be treated containing 0.100 mol/L of amylanthrahydroquinones. In the hydrogenation treatment, 500 ml of the working solution before hydrogenation and 1000 mg of a hydrogenation catalyst in which palladium was supported on silica/alumina were collected in a flask, hydrogen was replaced in the gas phase, and reduced by stirring. The reduction amount (amylanthrahydroquinone concentration) was calculated from the hydrogen absorption amount. After reaching a predetermined amount of hydrogen absorption, the working solution was separated from the catalyst by filtration using a disposable syringe and a cartridge filter to obtain a working solution to be treated.

(alkaline treatment)

500 ml of the working solution to be treated and 25 ml of a 2.0 mol/L sodium hydroxide aqueous solution were placed in a 1 L beaker and stirred for 5 minutes. Stirring was performed at 25 degreeC by venting nitrogen. After stopping the stirring, the working solution and the aqueous sodium hydroxide solution were separated by a separatory funnel to obtain a regenerated working solution D.

(acid treatment)

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

(wash)

The obtained regeneration working solution E was brought into stirring contact with 50 ml of pure water. Stirring was carried out at 25°C by venting nitrogen. After 5 minutes, stirring was stopped, and the working solution and the aqueous layer were separated by a separatory funnel.

<Example 7>

Alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 6 except that 0.5 mol/L nitric acid was used for the acid treatment, and the working solution and the aqueous layer were separated with a separatory funnel.

<Example 8>

Alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 6 except that 0.35 mol/L nitric acid was used for the acid treatment, and the working solution and the aqueous layer were separated with a separatory funnel.

<Example 9>

Alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 6 except that 0.25 mol/L nitric acid was used for the acid treatment, and the working solution and the aqueous layer were separated with a separatory funnel.

In Table 2 and FIG. 3, about the aqueous layer obtained in the said Examples 6-9, the pH measurement result is shown.

In Examples 6-9, a sufficient amount of amylanthraquinones was obtained. When the concentration of nitric acid used for acid treatment was 0.35 mol/L or more, the pH of the pure water after contacting the regeneration working solution was sufficiently below 7, and the alkali metal compound was removed from the regeneration working solution. On the other hand, when the nitric acid concentration was 0.25 mol/L, the pH of the pure water after contacting the regeneration working solution was over 7, and a part of the alkali metal compound remained in the regeneration working solution. Therefore, it has been shown that in order to sufficiently remove the alkali metal compound from the regeneration working solution, acid treatment can be carried out using nitric acid, preferably at a concentration higher than 0.25 mol/L, more preferably at a concentration of 0.35 mol/L or higher. Furthermore, although it is thought that the removal effect of an alkali metal compound is improved as nitric acid is thick, from a viewpoint of the balance of a removal effect, cost and safety point, acid treatment using nitric acid with a concentration of 0.50 mol/L or more and less than 3 mol/L It is preferable to carry out

Although the above-mentioned various Examples/Comparative Examples demonstrate that anthraquinones are regenerated by the treatment of the present invention, it is found that regeneration of anthraquinones is regeneration from by-products (anthraquinone derivatives) to anthraquinones. To directly prove it, the following experiment was conducted.

<Example 10>

With respect to the alkyloxyanthrones represented by the general formulas (d) to (e) described above, an experiment was conducted on the regeneration to anthraquinones useful for the production of hydrogen peroxide.

Specifically, as the working solution before hydrogenation, amylanthraquinone (AmAQ) is contained in a concentration of 0.509 mol/L, amyloxyanthrone (AmOX) is contained in a concentration of 0.012 mol/L, and a mixed organic solvent A regenerated working solution C was obtained in the same manner as in Example 1 except that a working solution using (pseudocumene: diisobutylcarbinol = 55:45) was used. As a result, the concentration of amylanthraquinone (AmAQ) contained in the regeneration working solution C was 0.527 mol/L, and the concentration of amyloxyanthrone (AmOX) was 0.001 mol/L.

In the regeneration working solution C, the amount of amyloxyanthrone was greatly reduced, and a sufficient regeneration effect of amyloxyanthrone to amylanthraquinone was obtained.

<Example 11>

An experiment was conducted on a phenomenon in which the alkyltetrahydroanthraquinone epoxide represented by the aforementioned general formula (a) is regenerated into anthraquinones useful for the production of hydrogen peroxide.

Specifically, as a working solution before hydrogenation, a predetermined amount of amyltetrahydroanthraquinone epoxide is dissolved in a mixed organic solvent (pseudocumene: diisobutylcarbinol = 60: 40), and amyltetrahydroanthraquinone is Regeneration working solution C was prepared in the same manner as in Example 1 except that 50 ml of a working solution containing 0.016 mol/L of epoxide, 0.092 mol/L of amylanthraquinone and 0.000 mol/L of amyltetrahydroanthraquinone was used. got it As a result, the concentration of amyltetrahydroanthraquinoneepoxide (AmTHEP) contained in the regeneration working solution C was 0.003 mol/L, the concentration of amyltetrahydroanthraquinone (AmTHAQ) was 0.009 mol/L, and amylanthraquinone (AmAQ) The concentration of was 0.094 mol/L.

In the regeneration working solution C, the amount of amyltetrahydroanthraquinone epoxide was greatly reduced and the amount of amyltetrahydroanthraquinone as the regeneration destination was increased. Accordingly, sufficient regenerating effect of amyltetrahydroanthraquinone epoxide to amyltetrahydroanthraquinone was obtained.

<Example 12>

An experiment was conducted on a phenomenon in which the alkylanthrones represented by the aforementioned general formulas (b) and (c) are regenerated into anthraquinones useful for the production of hydrogen peroxide.

Specifically, since the amount of alkylanthrone normally contained in the working solution of the actual plant is small, (R=hydrogen) anthron having no alkyl group (Anthron, Fujifilm Wako Pure Pharmaceutical Co., Ltd., Wako Co., Ltd.) The experiment was conducted using However, in Fujifilm Wako Pure Medicine, Anthron is described as Anthron.

As a working solution before hydrogenation, a predetermined amount of anthrone was dissolved in a mixed organic solvent (pseudocumene: diisobutylcarbinol = 60: 40), and 50 ml of a working solution containing 0.050 mol/L of anthrone was prepared. A regeneration working solution C was obtained in the same manner as in Example 1 except for use. The concentration of anthrone (AN) contained in the working solution and the regeneration working solution C was 0.032 mol/L, and the concentration of anthraquinone (AQ) was 0.020 mol/L.

In the regeneration working solution C, anthrone was decreased and anthraquinone as a regeneration target was increased. Therefore, it was possible to obtain a sufficient regenerating effect of anthrone to anthraquinone.

From Examples 10 to 12, it was confirmed that amyltetrahydroanthraquinone epoxide, amyloxyanthrone and anthrone were regenerated into amylanthraquinones. However, it is presumed that there is a sufficient possibility that, besides these, anthraquinone byproducts that have not yet been identified are also regenerated into anthraquinones, thereby contributing to the improvement of the concentration of anthraquinones in the working solution after alkali treatment.

<Example 13>

The same experiment as in Example 6 was conducted using phosphoric acid instead of nitric acid. However, since phosphoric acid is a weak acid compared to nitric acid, the number of times of contact with the acid was increased from one to two. Specifically, the following operation was performed.

(hydrogenation and alkali treatment)

Hydrogenation treatment and alkali treatment were carried out in the same manner as in Example 6 using the same working solution as in Example 6 to obtain a regenerated working solution D.

(1st acid treatment)

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

(2nd acid treatment)

The obtained regeneration working solution E1 was stirred and brought into contact with 50 ml of 1.00 mol/L phosphoric acid. Stirring was carried out at 25°C by venting nitrogen. After 15 minutes, stirring was stopped, and the working solution and phosphoric acid were separated by a separatory funnel to obtain a regenerated working solution E2.

(wash)

The obtained regeneration working solution E2 was brought into stirring contact with 50 ml of pure water. Stirring was carried out at 25°C by venting nitrogen. After 5 minutes, stirring was stopped, and the working solution and the aqueous layer were separated by a separatory funnel.

<Example 14>

Alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 13 except that 0.50 mol/L phosphoric acid was used for the two acid treatments, and the working solution and the water layer were separated with a separatory funnel.

<Example 15>

Alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 13 except that 0.25 mol/L phosphoric acid was used for the two acid treatments, and the working solution and the aqueous layer were separated with a separatory funnel.

<Example 16>

Alkali treatment, acid treatment and water washing were carried out in the same manner as in Example 13 except that 0.13 mol/L phosphoric acid was used for the two acid treatments, and the working solution and the aqueous layer were separated with a separatory funnel.

In Table 3 and FIG. 4, about the aqueous layer obtained in the said Examples 13-16, the pH measurement result is shown.

In Examples 13 to 16, a sufficient amount of amylanthraquinones was obtained. When the concentration of phosphoric acid used for acid treatment was 0.25 mol/L or more, the pH of the aqueous layer after contacting the pure water with the regeneration working solution was sufficiently below 7, and the alkali metal compound was sufficiently removed from the regeneration working solution. On the other hand, when the nitric acid concentration was 0.13 mol/L, the pH of the aqueous layer after bringing the pure water into contact with the working solution for regeneration exceeded 7, and some alkali metal compounds remained in the working solution for regeneration. Therefore, it has been shown that in order to sufficiently remove the alkali metal compound from the regeneration working solution, it is preferable to carry out acid treatment using phosphoric acid at a concentration of 0.25 mol/L or more. In addition, it is thought that the stronger the nitric acid, the better the removal effect of the alkali metal compound, but from the viewpoint of the balance between the removal effect, cost and safety, phosphoric acid at a concentration of 0.50 mol/L or more and less than 3 mol/L is used to acid It turned out that it is preferable to perform a process.

Claims (18)

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

(In general formulas (1) and (2), R represents hydrogen or an alkyl group having 1 to 10 carbon atoms) The method of claim 1,
The working solution before the hydrogenation process is added to the working solution after the hydrogenation process and partially extracted before the oxidation process, or to the working solution after the hydrogenation process and partly extracted before the oxidation process A treatment method that is diluted with The method of claim 1,
The treatment method, wherein the working solution to be treated is a working solution partially extracted after the extraction step and before the hydrogenation step. 4. The method according to any one of claims 1 to 3,
The treatment method, wherein the concentration of the anthrahydroquinones is 0.05 to 0.10 mol/L. 5. The method according to any one of claims 1 to 4,
A treatment method, wherein the working solution to be treated further contains at least one anthraquinone derivative selected from the group consisting of the following general formulas (a) to (e).

(In general formulas (a) to (e), R has the same meaning as the general formulas (1) and (2) above) 6. The method according to any one of claims 1 to 5,
wherein R is an ethyl group, a butyl group or an amyl group. 7. The method according to any one of claims 1 to 6,
A treatment method in which the working solution to be treated is mixed with an alkali metal compound at a temperature of 0 to 60°C. 8. The method according to any one of claims 1 to 7,
and mixing the working solution to be treated and the aqueous solution of the alkali metal compound in an amount of working solution to be treated: aqueous alkali metal compound solution = 1 or more: 1 (volume). 9. The method according to any one of claims 1 to 8,
The processing method in which the said alkali metal compound is sodium hydroxide or potassium hydroxide. 10. The method according to any one of claims 1 to 9,
A treatment method in which an aqueous sodium hydroxide solution having a concentration of sodium hydroxide of 0.5 mol/L or more is mixed. 11. The method according to any one of claims 1 to 10,
and mixing the working solution to be treated with the aqueous solution of the alkali metal compound using a line mixer. 12. The method according to any one of claims 1 to 11,
After mixing with an alkali metal compound, the processing method which performs post-processing by mixing an acid further. 13. The method of claim 12,
wherein the acid is nitric acid or phosphoric acid. 14. The method according to claim 12 or 13,
A treatment method in which an acidic aqueous solution having a concentration of nitric acid or phosphoric acid of 0.20 mol/L or more is further mixed after mixing with the alkali metal compound. 15. The method according to any one of claims 12 to 14,
A processing method in which mixing with an acid is performed using a stirring mixer. 16. The method according to any one of claims 12 to 15,
After mixing the acid, further mixing with water to perform post-treatment. 17. The method according to any one of claims 12 to 16,
A treatment method in which the working solution after the post-treatment is stirred with pure water and allowed to stand, and the post-treatment is performed so that the pH of the separated aqueous layer is 7 or less. A method for producing hydrogen peroxide, characterized in that hydrogen peroxide is produced by an anthraquinone method using a working solution treated by the method according to any one of claims 1 to 17.

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