TWI758412B - Oxidation tower and hydrogen peroxide production apparatus equipped with oxidation tower - Google Patents

Abstract

An oxidation tower for use in bringing a working solution and air into contact with each other when hydrogen peroxide is produced using an anthraquinone method includes three small oxidation towers vertically connected to one another. At least a bottommost small oxidation tower is configured to bring the working solution and air into countercurrent contact with each other. The remaining small oxidation towers are configured to bring the working solution and air into cocurrent contact with each other.

Description

Oxidation tower and hydrogen peroxide production device with oxidation tower

The present invention relates to an oxidation tower and a hydrogen peroxide production apparatus having the oxidation tower.

The main production method of hydrogen peroxide currently carried out industrially is a method using anthraquinones as a reaction medium, which is called an anthraquinone method. Generally, it is used after dissolving anthraquinones in an organic solvent. The organic solvent can be used alone or in a mixture, usually a mixture of two organic solvents is used. A solution prepared by dissolving anthraquinones in an organic solvent is called a working solution.

The method for producing hydrogen peroxide by anthraquinone method includes a hydrogenation step, an oxidation step and an extraction step. In the hydrogenation step, the anthraquinones in the working solution are reduced with hydrogen in the presence of a catalyst (hereinafter referred to as hydrogenation) to generate the corresponding anthrahydroquinones. In the oxidation step, the anthrahydroquinones in the working solution generated in the hydrogenation step are oxidized with air or oxygen-containing gas. Thereby, the anthrahydroquinones in the working solution are restored to anthraquinones, and hydrogen peroxide is generated at the same time.

In the oxidation step, the hydrogen peroxide generated in the working solution is usually extracted with water in the extraction step. The working solution after the hydrogen peroxide has been extracted is returned to the hydrogenation step for reuse. That is, the working solution is circulated between the hydrogenation step, the oxidation step and the extraction step. This cyclic treatment is essentially the production of hydrogen peroxide from hydrogen and air, which is an extremely efficient treatment. Hydrogen peroxide has been produced industrially using recycling processes.

In the oxidation step, an oxidation tower is usually used to contact the working solution with air. The oxidation method using an oxidation tower is roughly classified into two types: co-current oxidation and counter-current oxidation.

Co-current oxidation is a system in which air and the hydrogenated working solution flow in the same direction inside the oxidation tower, and are disclosed in Patent Documents 1 to 3.

In co-current oxidation, in general, air and working solution are sent to the lower part of the oxidation tower. When the air and the working solution flow from the lower part to the upper part of the oxidation tower, the anthrahydroquinones contained in the working solution are oxidized, and at the same time, hydrogen peroxide is generated in the working solution.

Countercurrent oxidation is a method in which the air and the hydrogenated working solution flow in opposite directions in the oxidation tower, and is disclosed in Patent Document 4.

In countercurrent oxidation, generally speaking, the air is sent to the lower part of the oxidation tower, and the working solution is sent to the upper part of the oxidation tower. Air flows from the lower part of the oxidation tower to the upper part, and the working solution flows from the upper part of the oxidation tower to the lower part. During this period, the anthrahydroquinones contained in the working solution are oxidized, and at the same time, hydrogen peroxide is generated in the working solution.

In general, co-current oxidation is easier to control the reaction than counter-current oxidation, and it is said that it is easier to implement industrially. For such a reason, co-current oxidation is more commonly used industrially than counter-current oxidation.

[Prior Art Literature] [Patent Documents]

[Patent Document 1] U.S. Patent No. 3,880,596

[Patent Document 2] Japanese Patent Publication No. Sho 62-502821

[Patent Document 3] Chinese Patent No. 103803501

[Patent Document 4] US Patent No. 2902347

Figure 2 is a flow diagram showing an example of a conventional oxidation tower for co-current oxidation.

As shown in FIG. 2 , the conventional oxidation tower 100 includes three small oxidation towers 102a to 102c. These three small oxidation towers 102a-102c are stacked and connected in the up-down direction.

The working solution sent from the hydrogenation step first flows into the lower part of the first small oxidation tower 102a positioned on the uppermost side. The working solution that has flowed into the lower part of the first small oxidation tower 102a flows from the lower part of the first small oxidation tower 102a to the upper part, and is discharged from the upper part of the first small oxidation tower 102a.

Then, the working solution discharged from the upper part of the first small oxidation tower 102a flows into the lower part of the second small oxidation tower 102b located in the middle. The working solution flowing into the lower part of the second small oxidation tower 102b flows from the lower part of the second small oxidation tower 102b to the upper part, and is discharged from the upper part of the second small oxidation tower 102b.

The working solution discharged from the upper part of the second small oxidation tower 102b is separated into air by the first gas-liquid separator 104a, and then flows into the lower part of the third small oxidation tower 102c positioned on the lowest side. The working solution flowing into the lower part of the third small oxidation tower 102c flows from the lower part of the third small oxidation tower 102c to the upper part, and is discharged from the upper part of the third small oxidation tower 102c.

The working solution discharged from the upper part of the third small oxidation tower 102c is transferred to the subsequent extraction step after the air is separated by the second gas-liquid separator 104b. In the extraction step, the hydrogen peroxide generated in the working solution is extracted with water. The working solution after the hydrogen peroxide has been extracted is returned to the hydrogenation step. In the hydrogenation step, the anthraquinones in the working solution are hydrogenated to anthrahydroquinones. In this way, the working solution is circulated between the hydrogenation step, the oxidation step and the extraction step.

On the other hand, the air in contact with the working solution first flows into the lower part of the second small oxidation tower 102b and the lower part of the third small oxidation tower 102c.

The air that has flowed into the lower part of the second small oxidation tower 102b flows from the lower part of the second small oxidation tower 102b to the upper part, and is discharged from the upper part of the second small oxidation tower 102b. The air discharged from the upper part of the second small oxidation tower 102b flows into the lower part of the first small oxidation tower 102a after the working solution is separated by the first gas-liquid separator 104a.

The air that has flowed into the lower part of the third small oxidation tower 102c flows from the lower part of the third small oxidation tower 102c to the upper part, and is discharged from the upper part of the third small oxidation tower 102c. After the air discharged from the upper part of the third small oxidation tower 102c is separated into the working solution by the second gas-liquid separator 104b, the working solution is separated by the first gas-liquid separator 104a. The air after separating the working solution by the first gas-liquid separator 104a flows into the lower part of the first small oxidation tower 102a.

The air which flowed into the lower part of the 1st small oxidation tower 102a flows from the lower part of the 1st small oxidation tower 102a to the upper part, and is discharged|emitted from the upper part of the 1st small oxidation tower 102a.

Inside each small oxidation tower, the working solution and the air contact each other while flowing in the same direction (cocurrent oxidation). However, looking at the entire oxidation tower, the air flows from the bottom to the top, and the working solution flows from the top to the bottom, so it looks like countercurrent oxidation.

The conventional oxidation method has a problem that the hydrogen peroxide generated in the working solution tends to accumulate in the lower part of the third small oxidation tower 102c located on the lowermost side. The reason is that, in general, the working solutions used in the manufacture of hydrogen peroxide are less dense than hydrogen peroxide.

Impurities such as fine powder of the catalyst used in the hydrogenation reaction may be present in the oxidation tower. If the hydrogen peroxide is accumulated in the lower part of the oxidation tower, the decomposition of the hydrogen peroxide will be accelerated by the fine powder of the catalyst existing in the oxidation tower, and there is a possibility that a safety problem will occur.

In view of the above problems, the present invention aims to provide an oxidation tower capable of preventing accumulation of hydrogen peroxide in the lower part of at least the lowermost small oxidation tower, and a hydrogen peroxide production apparatus using the oxidation tower.

The present invention is as follows.

(1) a kind of oxidation tower is used in order to make working solution contact with air when utilizing the anthraquinone method to manufacture hydrogen peroxide, and this oxidation tower is composed of 3 small oxidation towers connected along the up-down direction, At least the lowermost small oxidation tower is constructed so that the working solution is in countercurrent contact with the air, and the remaining small oxidation towers are constructed so that the working solution and the air are in cocurrent contact.

(2) as the oxidation tower of (1), wherein, the small oxidation tower on the lowermost side is constituted by the mode that the working solution is in countercurrent contact with air, and the 2 small oxidation towers on the upper side are in order to make the working solution and the air The way the flow contacts constitute.

(3) An apparatus for producing hydrogen peroxide including the oxidation tower of (1) or (2).

(4) A kind of hydrogen peroxide, which is produced by the hydrogen peroxide production apparatus as in (3).

(5) A method for producing hydrogen peroxide, comprising the steps of: using an oxidation tower such as (1) or (2) to oxidize anthrahydroquinones in a working solution.

According to the present invention, there are provided an oxidation tower capable of preventing accumulation of hydrogen peroxide in the lower part of at least the lowermost small oxidation tower, and a hydrogen peroxide production apparatus using the oxidation tower.

10, 100: Oxidation tower

12a, 102a: The first small oxidation tower

12b, 102b: The second small oxidation tower

12c, 102c: The third small oxidation tower

14a, 104a: The first gas-liquid separator

14b, 104b: Second gas-liquid separator

[Fig. 1] shows the flow chart of the oxidation tower.

[Fig. 2] shows the flow chart of the conventional oxidation tower.

The present invention will be described in detail below. The following embodiments are examples for explaining the present invention, and the present invention is not limited to these embodiments. The present invention can be implemented in various forms without departing from the gist.

The present invention relates to an oxidation tower used for bringing a working solution into contact with air when producing hydrogen peroxide by an anthraquinone method. As mentioned above, the anthraquinone method is a method using anthraquinones as a reaction medium. In the anthraquinone method, a working solution prepared by dissolving anthraquinones in an organic solvent is used.

The method for producing hydrogen peroxide by anthraquinone method includes a hydrogenation step, an oxidation step and an extraction step. In the hydrogenation step, the anthraquinones in the working solution are reduced with hydrogen in the presence of a catalyst to generate corresponding anthrahydroquinones. In the oxidation step, the anthrahydroquinones in the working solution generated in the hydrogenation step are oxidized by air or oxygen-containing gas. Thereby, the anthrahydroquinones in the working solution are restored to anthraquinones, and hydrogen peroxide is generated at the same time.

The anthraquinones used in the present invention are preferably alkyl anthraquinones, alkyl tetrahydroanthraquinones or their mixtures. The alkyl anthraquinones and the alkyl tetrahydroanthraquinones can each be a mixture of most of the alkyl anthraquinones and the alkyl tetrahydroanthraquinones. Examples of the alkyl anthraquinone include ethyl anthraquinone, tert-butyl anthraquinone, pentyl anthraquinone, and the like. Moreover, ethyltetrahydroanthraquinone, t-butyltetrahydroanthraquinone, pentyltetrahydroanthraquinone, etc. are mentioned as an alkyltetrahydroanthraquinone.

The organic solvent used for preparing the working solution is not particularly limited. Ideal organic solvents, such as the combination of aromatic hydrocarbons and higher alcohols, the combination of aromatic hydrocarbons and cyclohexanol, the combination of aromatic hydrocarbons and alkyl cyclohexanol, the combination of aromatic hydrocarbons and carboxylate, aromatic hydrocarbons Combination with tetra-substituted urea, and trioctyl phosphate.

The carrier of the hydrogenation catalyst used in the production of hydrogen peroxide by the anthraquinone method is not particularly limited as long as it is a normal catalyst carrier.

The carrier of the hydrogenation catalyst, for example, is preferably selected from the group consisting of silicon dioxide, silicon dioxide·alumina, aluminum oxide, titanium oxide, zirconium oxide, silicon dioxide·alumina composite oxide, silicon dioxide·titanium oxide At least one selected from the group consisting of composite oxides, alumina-titanium oxide composite oxides, and mixtures thereof is preferred.

The total pore volume of the support of the hydrogenation catalyst is preferably 0.2 to 2.0 ml/g.

The carrier of the hydrogenation catalyst is preferably silica, alumina or silica-alumina composite oxide with a total pore volume of 0.2-2.0 ml/g.

The metal contained in the hydrogenation catalyst used in the present invention is preferably at least one selected from the group consisting of palladium, rhodium, ruthenium and platinum. Among them, palladium is preferable. The mass of the hydrogenation catalyst is preferably 0.1 to 10% relative to the mass of the catalyst carrier. The hydrogenation catalyst is preferably supported in a metallic state. The hydrogenation catalyst can also be supported in a state where it is easily reduced under the conditions of a hydrogenation reaction to become a metal oxide.

Fig. 1 is a flow chart showing an example of an oxidation tower according to an embodiment of the present invention.

As shown in FIG. 1, the oxidation tower 10 of this embodiment has three small oxidation towers 12a-12c. These three small oxidation towers 12a-12c are stacked and connected in the up-down direction.

The working solution sent from the hydrogenation step first flows into the lower part of the first small oxidation tower 12a positioned on the uppermost side. The working solution flowing into the lower part of the first small oxidation tower 12a flows from the lower part of the first small oxidation tower 12a to the upper part, and is discharged from the upper part of the first small oxidation tower 12a.

Then, the working solution discharged from the upper part of the first small oxidation tower 12a flows into the lower part of the second small oxidation tower 12b located in the middle. The working solution flowing into the lower part of the second small oxidation tower 12b flows from the lower part of the second small oxidation tower 12b to the upper part, and is discharged from the upper part of the second small oxidation tower 12b.

The working solution discharged from the upper part of the second small oxidation tower 12b is separated into air by the first gas-liquid separator 14a, and then flows into the upper part of the third small oxidation tower 12c positioned on the lowermost side. The working solution flowing into the upper part of the third small oxidation tower 12c flows from the upper part of the third small oxidation tower 12c to the lower part, and is discharged from the lower part of the third small oxidation tower 12c.

The working solution discharged from the lower part of the third small oxidation tower 12c is transferred to the subsequent extraction step. In the extraction step, the hydrogen peroxide formed in the working solution is extracted with water. After the hydrogen peroxide has been extracted, the working solution is returned to the hydrogenation step. In the hydrogenation step, the anthraquinones in the working solution are hydrogenated to anthrahydroquinones. In this way, the working solution is circulated between the hydrogenation step, the oxidation step and the extraction step.

On the other hand, the air in contact with the working solution first flows into the lower part of the second small oxidation tower 12b and the lower part of the third small oxidation tower 12c.

The air flowing into the lower part of the second small oxidation tower 12b flows from the lower part of the second small oxidation tower 12b to the upper part, and is discharged from the upper part of the second small oxidation tower 12b. The air discharged from the upper part of the second small oxidation tower 12b flows into the lower part of the first small oxidation tower 12a after the working solution is separated by the first gas-liquid separator 14a.

The air which flowed into the lower part of the 3rd small oxidation tower 12c flows from the lower part of the 3rd small oxidation tower 12c to the upper part, and is discharged|emitted from the upper part of the 3rd small oxidation tower 12c. After the air discharged from the upper part of the third small oxidation tower 12c is separated from the working solution by the second gas-liquid separator 14b, the working solution is separated by the first gas-liquid separator 14a. liquid. The air after separating the working solution by the first gas-liquid separator 14a flows into the lower part of the first small oxidation tower 12a.

The air which flowed into the lower part of the 1st small oxidation tower 12a flows from the lower part of the 1st small oxidation tower 12a to the upper part, and is discharged|emitted from the upper part of the 1st small oxidation tower 12a.

Inside the first small oxidation tower 12a and the second small oxidation tower 12b, the working solution and the air contact each other while flowing in the same direction (cocurrent oxidation).

Inside the third small oxidation tower 12c, the working solution and the air come into contact with each other while flowing in opposite directions (counter-flow oxidation).

The oxidation tower 10 of this embodiment is used in the step (oxidation step) of bringing the working solution into contact with air when producing hydrogen peroxide by the anthraquinone method. As described above, the oxidation tower 10 includes three small oxidation towers 12a to 12c connected in the vertical direction. The lowermost small oxidation tower 12c is constituted so that the working solution is brought into contact with the air in countercurrent flow. The remaining two small oxidation towers 12a and 12b are constituted so that the working solution and the air are brought into cocurrent contact. With such a configuration, the following effects can be obtained.

According to the oxidation tower 10 of the present embodiment, it is possible to prevent the accumulation of hydrogen peroxide in the lower part of the lowermost small oxidation tower 12c. Thereby, the decomposition|disassembly of the accumulated hydrogen peroxide by impurities, such as a catalyst fine powder, can be prevented, and the safety|security of a hydrogen peroxide manufacturing apparatus can be improved.

According to the oxidation tower 10 of the present embodiment, it is possible to prevent the accumulation of hydrogen peroxide in the lower part of the lowermost small oxidation tower 12c. Thereby, the generation|occurence|production of the hydrogen peroxide which cannot be utilized as a product can be reduced, and the yield of hydrogen peroxide can be improved.

According to the oxidation tower 10 of the present embodiment, the generated hydrogen peroxide does not easily stay in the lower part of the lowermost small oxidation tower 12c. Thereby, the catalyst fine powder carried in from the hydrogenation step and accumulated in the lower part of the small oxidation tower 12c can be prevented from coming into contact with hydrogen peroxide and generating hydrogen peroxide. As a result, the safety of the hydrogen peroxide production apparatus can be improved.

<Other Embodiments>

In the above-described embodiment, the lowermost small oxidation tower 12c is shown as a counter-flow, and the upper two small oxidation towers 12a and 12b are shown as a parallel flow, but the present invention is not limited to such an aspect. For example, if the two small oxidation towers 12b and 12c on the lower side are in countercurrent flow, and only the small oxidation tower 12a on the uppermost side is in parallel flow, the effect of the present invention can also be obtained.

The air sent to the lower part of each of the small oxidation towers 12a to 12c may be fine air bubbles. For example, a nozzle for blowing air in the state of minute air bubbles may be provided in the lower part of each of the small oxidation towers 12a to 12c. By blowing air in the state of minute air bubbles, the anthrahydroquinones contained in the working solution can be oxidized more efficiently. As a result, the yield of hydrogen peroxide can be improved. The microscopic air bubbles referred to here refer to air bubbles having a diameter of 50 μm or less.

10: Oxidation tower

12a: The first small oxidation tower

12b: The second small oxidation tower

12c: The third small oxidation tower

14a: The first gas-liquid separator

14b: 2nd gas-liquid separator

Claims (4)

An oxidation tower is used for contacting working solution with air when utilizing anthraquinone method to manufacture hydrogen peroxide. It is constructed in such a way that the working solution is in countercurrent contact with air, and the remaining small oxidation towers are constructed in such a way that the working solution and air are in cocurrent contact. Such as the oxidation tower of claim 1 of the scope of application, wherein the small oxidation tower on the lowermost side is formed in such a way that the working solution is in countercurrent contact with the air, and the two small oxidation towers on the upper side are formed so that the working solution and the air are mixed together. The way the flow contacts constitute. An apparatus for producing hydrogen peroxide, which is provided with an oxidation tower as claimed in item 1 or 2 of the scope of the application. A method for producing hydrogen peroxide, comprising the following steps: using an oxidation tower as claimed in item 1 or 2 of the patented scope to oxidize anthrahydroquinones in a working solution.

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