JPH04317419A - Production of aqueous manganese bromide solution - Google Patents

Abstract

PURPOSE:To efficiently obtain aq. manganese bromide soln. having high purity and high quality without containing bromine or hydrogen bromide by reacting metal manganese, bivalent basic manganese compd., with hydrogen bromide in water with a specified Mn/Br. CONSTITUTION:Metal manganese and/or bivalent basic manganese compd. such as MnO, Mn(OH)2, MnCO3, etc., is made to react with hydrogen bromide in water with 0.52-1.00 Mn/Br atomic ratio. If the Mn/Br atomic ratio is <0.52, the reaction proceeds vigorously, the heat of reaction is hardly removed, and unreacted hydrogen bromide remains. On the other hand, if the ratio is larger than 1.00, the reaction proceeds slowly, which takes long time to complete. Moreover, in this case, the reaction is apt to produce fine manganease hydroxide or manganese oxide hydrate which are hardly separated by filtering. It is preferable that pH at the end of the reaction is 0-4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aqueous solution of manganese bromide. Manganese bromide aqueous solution is
It is widely used as an oxidation catalyst for organic compounds, and is particularly useful as a catalyst for producing high-purity terephthalic acid.

0002

[Prior Art] Conventionally, methods for producing manganese bromide include passing a bromine stream through heated manganese, allowing bromine to act on manganese (II) oxide, reacting manganese with bromine water, manganese carbonate (II) ) in hydrobromic acid (Kyoritsu Shuppan Co., Ltd., page 610 of Kagaku Dictionary 4), and a method of reacting manganese acetate in benzene with excess acetyl bromide (GMELIN HANDBUC).
H Mn TEIL C5 page 265 197
8) etc. are known. Furthermore, a reaction between a metal and a hydrohalic acid is known as a general method for producing metal halides.

0003

[Problems to be Solved by the Invention] When the present inventors carried out these methods using a stoichiometric ratio of manganese source and bromine source, it was found that bromine or hydrogen bromide remained in the manganese bromide product. I found something to do. By the way, a high quality manganese bromide aqueous solution is required as a catalyst used in the automatic oxidation of organic compounds, particularly in the production of high purity terephthalic acid by air oxidation of p-xylene. As impurities,
Although metal ions such as Fe, Ni, and Pb are strictly limited, the content of unreacted bromine or hydrogen bromide is also important and must be kept low. These suppress the action of manganese bromide as a catalyst and promote corrosion of equipment materials (when corrosion occurs, not only does the equipment material become thinner, but also the constituent substances of the equipment material dissolve in the catalyst liquid, causing catalyst poisoning). ). Bromine or hydrogen bromide can be removed by neutralization with an alkaline substance or deaeration. However, when neutralized with sodium hydroxide, potassium hydroxide, ammonia, etc., the neutralization product becomes an impurity. When neutralizing with basic manganese compounds such as manganese oxide, manganese hydroxide, and manganese carbonate, the neutralized product does not become an impurity, but it is difficult to control the amount added, and the number of steps increases and becomes complicated. .

An object of the present invention is to provide a method for economically and efficiently producing a high-purity, high-quality manganese bromide aqueous solution that does not contain bromine or hydrogen bromide.

[0005]

[Means for Solving the Problems] In order to achieve this object, the present inventors conducted extensive research on a method for producing an aqueous solution of manganese bromide, and found that by adjusting the atomic ratio of bromine and manganese, It has been discovered that a high-purity, high-quality manganese bromide aqueous solution can be produced economically, efficiently, and with simple operations. That is, the present invention
Metallic manganese and/or divalent basic manganese compound and hydrogen bromide are mixed at an Mn/Br atomic ratio of 0.52 to 1.0.
This is a method for producing manganese bromide by reacting it in water at a ratio of 0.

The present invention will be explained in more detail below. The manganese source used in the present invention includes metallic manganese and/or
Or it is a divalent basic manganese compound. There are no particular limitations on the metal manganese, and commonly available commercially available electrolytic manganese metal, thermite metal manganese, carbon reduction metal manganese, and the like can be used. In terms of product quality, electrolytic manganese metal is of high quality and is preferred.

As the divalent basic manganese compound, M
Examples include divalent manganese oxide, manganese hydroxide, and manganese carbonate represented by nO, Mn(OH)2, MnCO3, etc., and all of these are sparingly soluble or insoluble in water. In addition to divalent manganese compounds, trivalent, tetravalent, and heptavalent compounds are known, and even if these compounds with a valence exceeding 2 are used, manganese bromide is produced ( "Manganese bromide" is limited to divalent ones.In other words, only divalent manganese bromides are known, and even if these high valence manganese compounds are used, the resulting bromide is only divalent. (of value)
At the same time, bromine, which is difficult to separate from the product, is produced as a by-product.
It does not interfere with the purpose of the present invention. These manganese compounds may be used in the form of powder or granules. Further, commercially available metallic manganese is available in flake form, and this flake form is preferable in terms of purity, operability, and the like.

[0008] Metallic manganese is particularly desirable as a manganese source. This is because metal manganese has an appropriate rate of reaction with hydrogen bromide, can be obtained with relatively high purity, and furthermore, residual hydrogen bromide can be easily controlled. The shape of the metal manganese is preferably flaky as described above. Initially, it was thought that the reaction would take a long time because flakes have a small surface area per unit weight, but contrary to expectations, the reactivity was good and manganese bromide could be produced efficiently. When metal manganese is reacted with hydrogen bromide, hydrogen gas is generated, but it can be operated outside the explosive range by diluting it with a large amount of nitrogen gas, air, etc., or by preventing air from getting mixed in. If the latter method is adopted, the by-product hydrogen gas will be obtained with high purity. If metallic manganese flakes are used, the purity is good as mentioned above, and the operability is also good.

In the present invention, hydrogen bromide is used as a bromine source. Manganese bromide can be obtained by using bromine, but its reactivity is extremely low compared to hydrogen bromide, and unreacted bromine cannot be avoided, and unreacted bromine cannot be removed by heating or reduced pressure. is also difficult.

In addition to these manganese sources and hydrogen bromide,
Water must also be supplied to the reaction system. Hydrogen bromide and water supply modes include hydrogen bromide gas and water, hydrobromic acid aqueous solution, hydrogen bromide gas and hydrobromic acid aqueous solution, water and hydrobromic acid aqueous solution, and hydrogen bromide gas and water Any solution such as an aqueous solution of hydrobromic acid can be used. These proportions and the concentration of the aqueous hydrobromic acid solution are determined in relation to the type of manganese source and the desired concentration of the aqueous manganese bromide solution to be obtained. If the concentration of the manganese bromide aqueous solution is too low, the transportation cost will naturally increase, and the activity will decrease when used as a catalyst, so for practical purposes, the concentration is preferably 20 wt% or more. However, the solubility of manganese bromide at room temperature is 60 wt%, so if a liquid with a higher manganese bromide content is produced, it will be necessary to separate the unreacted manganese source from the precipitated manganese bromide. Become. 20-6
In order to produce a 0 wt % manganese bromide aqueous solution, no matter which of the above embodiments is used, if metallic manganese is used, the weight ratio of hydrogen bromide and water supplied to the system should be 17
/83 to 54/46 is preferable. Usually, a commercially available aqueous solution of hydrobromic acid has a concentration of 47 wt %, and can be preferably used. Using this and metal manganese, approximately 5
A 4 wt % manganese bromide aqueous solution is obtained. for example,
Manganese bromide, which is sold as an oxidation catalyst for organic compounds, is a 50 to 60 wt% aqueous solution. To obtain this, use this 47 wt% aqueous solution of hydrobromic acid, or add hydrogen bromide gas to this. You can use them together. Further, for example, by charging water and a manganese source in a reaction tank and blowing hydrogen bromide gas into the reaction tank, the concentration of the resulting manganese bromide aqueous solution can be freely adjusted.

The gist of the present invention is to convert the above raw materials into Mn/Br
The atomic ratio is adjusted to be in the range of 0.52 to 1.00. If this ratio is less than 0.52, the reaction will be so intense that it will be difficult to remove the reaction heat, and unreacted hydrogen bromide will remain, making this treatment necessary. On the other hand, if it is larger than 1.00,
The reaction is slow and takes a long time to complete. In addition, fine manganese hydroxide and manganese oxide hydrate tend to be produced, and in this case, since they are fine particles, it is difficult to separate them by filtration. When this ratio is 0.52 to 1.00, the reaction is smooth, heat removal is easy, and unreacted manganese hydroxide, manganese oxide hydrate, etc. are not generated, and the operation is easy. . A more preferable range of the Mn/Br atomic ratio is 0.55 to 0.80, and the above-mentioned effect is further enhanced. (The fact that the reaction becomes vigorous when the Mn/Br atomic ratio is high and slow when it is low can be explained by the fact that the reaction between the manganese source and hydrogen bromide is very fast). Since the stoichiometric atomic ratio of Mn/Br in the reaction in which manganese bromide is obtained from a manganese source and hydrogen bromide is 0.5, the manganese source is used in excess in the present invention. Therefore, at the end of the reaction, an unreacted manganese source remains in the system, but whether it is metallic manganese or a divalent basic manganese compound, it is separated from the reaction solution and reused as the manganese source of the present invention. The entire amount can be used.

The pH at the end of the reaction is preferably in the range of 0 to 4, and in the present invention, it can be easily adjusted within this range by adjusting the Mn/Br atomic ratio and the concentration of the residual hydrobromic acid aqueous solution. be able to. If this pH is lower than 0, this means that an excess of hydrogen bromide remains, which becomes an impurity and corrodes the equipment and containers that come into contact with it. There will also be more. On the other hand, when the pH is higher than 4, the product manganese bromide is easily hydrolyzed.
The resulting fine particles of manganese hydroxide and manganese oxide hydrate precipitate during manufacturing, storage, and use, causing many harms. These fine particles may adhere to the walls of containers, pipes, etc.
or clog the pump. Also, when used as a catalyst, it will reduce the quality and purity of the product. pH
When the number is 0 to 4, the unreacted hydrogen bromide content is low, corrosion problems are suppressed, and the formation of precipitates due to hydrolysis can be prevented, and when used as a catalyst, its performance is further improved. pH can be easily measured and adjusted with a pH meter. Furthermore, the preferred pH range is 2 to 3,
The aforementioned effect becomes even greater. When the pH is within this range, when using 47 wt% hydrobromic acid and metal manganese,
The amount of remaining HBr can be 0.01 wt% or less. When the above Mn/Br atomic ratio is smaller than 0.52,
It takes a long time to raise the pH to 0 or higher, or it becomes impossible to raise the pH to 0 or higher.On the other hand, if it is higher than 1.00, the pH will exceed 4. The atomic ratio is 0.52 to 1.
By setting the pH to 00, it becomes easy to adjust the pH to 0 to 4.

The order of addition of the manganese compound and aqueous hydrogen bromide to the system is: (1) adding hydrogen bromide to the manganese source, (2) adding the manganese source to hydrogen bromide, (2) adding the manganese source and hydrogen bromide simultaneously. Either of these is fine. Further, the addition method may be a batch method, a semi-continuous method, or a continuous method. However, the reaction in the present invention is a large exothermic reaction, and the system with a higher Mn/Br atomic ratio has a milder reaction, so method (2) is preferable. In addition, for ease of operation, reaction control, removal of reaction heat, pH adjustment, etc., it is recommended to fill the reaction tank with a manganese source in advance, then add hydrogen bromide continuously or intermittently, and measure the pH after the addition is complete. However, it is most preferable to extract the liquid in a pH range of 0 to 4 and filter it if necessary. In particular, when using flaky metal manganese, a separate melting tube is provided, the metal manganese is put there and reacted with hydrogen bromide, and the reaction liquid is circulated between the tank and the melting tube, and then transferred to the tank. providing an aqueous hydrogen bromide source;
It is advantageous to perform cooling, heating, stirring (stirring is required for pH measurement), etc. in the tank.

Although it is preferable to stir the mixture in order to carry out the reaction uniformly, the reaction proceeds satisfactorily even without stirring. The stirring may be carried out by a normal stirrer or by pump circulation.

As described above, in the present invention, an excess manganese source remains at the end of the reaction. In order to remove the manganese source from the reaction system, it is necessary to filter it, but this filtration can be performed using a centrifugal filter, pressure filter, etc. using a normal glass fiber filter cloth, or a cartridge filter. good. In particular, when flaky metallic manganese is used, the remaining metallic manganese sinks to the bottom and there are very few suspended solids, making the filtration operation easy. Hydrogen is produced when metallic manganese is used, and carbon dioxide gas is produced when manganese carbonate is used, but these by-product gases can be discharged by condensing water, or they can be discharged with water still accompanying them. You may. When it is desired to obtain a highly concentrated manganese bromide aqueous solution, the latter is preferable, and when a 47 wt% hydrobromic acid aqueous solution is used, an increase in concentration of 2 to 3 wt% can be expected.

[0016]

ADVANTAGEOUS EFFECTS OF THE INVENTION According to the present invention, many and important effects are realized. Listed below. (1) By adjusting the Mn/Br atomic ratio of the raw materials to 0.52 to 1.00, a high-purity, high-quality manganese bromide aqueous solution can be produced economically, efficiently, and with simple operations. Can be done. (2) The excess amount of aqueous hydrogen bromide, which is especially important for quality, can be easily minimized, and equipment corrosion and generation of fine impurity particles can be suppressed, which is effective when the product is used as a catalyst. can be made larger. (3) The reaction is easy to control, and heat removal, amount of by-product gas, etc., which are issues in production, can be easily adjusted. (4) A highly pure and high quality manganese bromide aqueous solution with a pH of 0 to 4 can be easily produced.

[0017]

[Examples] Next, the present invention will be explained in more detail with reference to Examples. Example 1 Flake metal manganese (manufactured by Tosoh Corporation, ordinary product)
280.1 g was placed in a 2-liter round-bottomed flask equipped with a dropping funnel, stirring blade, sample extraction tube, and Dimroth cooling tube, and the inside was purged with nitrogen. While cooling the round bottom flask with water, addition of a 47 wt % hydrobromic acid aqueous solution (manufactured by Tosoh Corporation) was started using a dropping funnel. Hydrogen gas is generated at the same time as the hydrobromic acid aqueous solution is added, and the liquid temperature is approximately 90℃.
It rose to a certain point and then began to fall. Then, cooling with water was stopped, and the reaction solution was heated and maintained at 65°C. The generated hydrogen gas passes through a cooling pipe, condenses water, and returns to the flask.
Hydrogen gas was purged. Hydrobromic acid aqueous solution is 1403
．． 6g (i.e. Mn/Br atomic ratio 0.62) at 30
Added in portions. Stirring was started when about 500 g was added from the start of the addition. After the addition of hydrobromic acid was completed, stirring and temperature control of the reaction solution to 65°C were continued, and sampling was performed from time to time. When the pH of the reaction solution reached 2,
The reaction solution was filtered through glass fiber filter paper with a pore size of 1 μm. Filtration was extremely easy, and the entire amount was filtered within 3 minutes to obtain a clear manganese bromide aqueous solution. The pH of this manganese bromide aqueous solution was 2.8.

[0018] When this manganese bromide aqueous solution was analyzed, the manganese bromide concentration was 54.4 wt%, and the unreacted hydrogen bromide was 0.01 wt% or less, indicating high purity. Even when this manganese bromide aqueous solution was stored in a sample bottle for one year, it did not become cloudy and its composition did not change. The flaky manganese metal described above was added to the remaining manganese metal, and the test was carried out under the same conditions as above to obtain a manganese bromide aqueous solution having almost the same quality as above.

Comparative Example 1 537.4 g of flaky metallic manganese (that is, M
The reaction was carried out in the same manner as in Example 1 using (n/Br atomic ratio 1.20). However, the pH in the reaction solution after the reaction was difficult to adjust and rose within a short period of time to 4.20, resulting in the formation of yellow-brown fine particulate precipitates. The reaction solution had poor filterability and took a long time to filter. p of the obtained manganese bromide aqueous solution
H was 4.18, and there was no turbidity immediately after filtration, but when left for several hours, turbidity occurred and a precipitate was formed.

Comparative Example 2 223.9 g of flaky metallic manganese (that is, M
The reaction was carried out in the same manner as in Example 1 using (n/Br atomic ratio 0.50). However, the reaction was violent and a dangerous situation called bumping occurred at one point. In addition, the pH in the reaction solution did not rise to -1 or higher, and the filtration operation was carried out with the pH kept at such a low level. The pH of the obtained manganese bromide aqueous solution was -1 or less, and unreacted hydrogen bromide was 0.35 wt%.

Example 2 Manganese carbonate hemihydrate (manufactured by Kanto Kagaku Co., Ltd., reagent special grade,
) was placed in a 2-liter round-bottomed flask equipped with a dropping funnel, a stirring blade, a sample extraction tube, and a Dimroth cooling tube, and the inside was purged with nitrogen. While maintaining the temperature inside the round bottom flask at 50 to 70°C, 47W was added using the dropping funnel.
Addition of t% hydrobromic acid aqueous solution (manufactured by Tosoh Corporation) was started. Carbon dioxide gas was generated simultaneously with the dropping of the hydrobromic acid aqueous solution. The generated carbon dioxide gas was passed through a cooling pipe, water was condensed and refluxed into the flask, and the carbon dioxide gas was purged. 1032.6 g of the hydrobromic acid aqueous solution (ie, Mn/Br atomic ratio 0.59) was added over 30 minutes. Stirring was started when about 500 g was added from the start of the addition. After the addition of hydrobromic acid is completed, stirring and temperature control of the reaction solution to 65°C are continued, and sampling is performed from time to time to determine the pH of the reaction solution.
When the value reached 2.39, the reaction solution was filtered through glass fiber filter paper with a pore size of 1 μm. Filtration was extremely easy, and the entire amount was filtered within 5 minutes to obtain a clear manganese bromide aqueous solution. The pH of this manganese bromide aqueous solution is 2.
It was 66.

[0022] When this manganese bromide aqueous solution was analyzed, the manganese bromide concentration was 50.5 wt%, and the unreacted hydrogen bromide was 0.01 wt% or less, indicating high purity. The above-mentioned manganese carbonate was added to the remaining manganese carbonate and the process was carried out under the same conditions as above to obtain a manganese bromide aqueous solution having almost the same quality as above.

Claims (3)

[Claims] Claims: 1. Metallic manganese and/or divalent basic manganese compound and hydrogen bromide are mixed in an Mn/Br atomic ratio of 0.
A method for producing an aqueous solution of manganese bromide, which comprises reacting in water at a ratio of 52 to 1.00. 2. The method for producing an aqueous manganese bromide solution according to claim 1, wherein the metallic manganese and/or the divalent basic manganese compound is metallic manganese. 3. The method for producing an aqueous manganese bromide solution according to claim 1 or 2, wherein the pH of the aqueous solution at the end point of the reaction system is adjusted to 0 to 4.