Preparation method of high-purity potassium hexafluoromanganate

Abstract

The invention relates to the technical field of synthesis of potassium hexafluoromanganate, and provides a preparation method of high-purity potassium hexafluoromanganate, which comprises the following steps: S1, mixing hydrofluoric acid and potassium hydroxide to obtain a mixed solution I; s2, adding manganous oxide into the mixed solution I, reacting, filtering and freezing to obtain a mixed solution II; s3, adding potassium permanganate into the mixed solution II, and stirring to obtain potassium hexafluoromanganate. Through the technical scheme, the problem of low purity of potassium hexafluoromanganate prepared in related technologies is solved.

Description

Technical Field

[0001] The invention relates to the technical field of potassium hexafluoromanganate synthesis, and in particular to a method for preparing high-purity potassium hexafluoromanganate. Background Art

[0002] Potassium hexafluoromanganate is a high-density compound. During the battery charging process, potassium hexafluoromanganate releases electrons and cations, which flow through the external circuit to generate current; during the discharge process, potassium hexafluoromanganate absorbs electrons and cations in the external circuit, and this process releases the energy stored in the compound. Therefore, potassium hexafluoromanganate plays the role of storing and releasing energy in the battery. Potassium hexafluoromanganate has good thermal and chemical stability, and can maintain good performance under high temperature and strong acid and strong alkali conditions. Therefore, it is widely used in aerospace and new energy fields.

[0003] Currently, potassium hexafluoromanganate is mainly prepared by fluorine gas oxidation method and manganese chloride oxidation method, but the potassium hexafluoromanganate prepared by these methods has low purity and cannot meet the use of high-end products. Therefore, the purpose of the present invention is to provide a preparation method of high-purity potassium hexafluoromanganate to meet the demand of high-end products for high-purity potassium hexafluoromanganate. Summary of the invention

[0004] The invention provides a method for preparing high-purity potassium hexafluoromanganate, which solves the problem of low purity of potassium hexafluoromanganate in the preparation of related technologies.

[0005] The technical solution of the present invention is as follows: The present invention provides a method for preparing high-purity potassium hexafluoromanganate, comprising the following steps: S1, mixing hydrofluoric acid and potassium hydroxide to obtain a mixed solution I; S2, adding manganous oxide to the mixed solution I, reacting, filtering and freezing to obtain a mixed solution II; S3. Add potassium permanganate into the mixed solution II, and obtain potassium hexafluoromanganate after stirring.

[0006] As a further technical solution, in step S1, the mass ratio of the potassium hydroxide to the hydrofluoric acid is 1:5-6.

[0007] In the present invention, by adding an excess of hydrofluoric acid, the hydrolysis of potassium hexafluoromanganate and the generation of manganese dioxide in step S3 can be prevented, and at the same time, most of the anionic and cationic impurities can be taken away, thereby improving the yield of the product.

[0008] As a further technical solution, in step S2, the mass ratio of the manganous oxide to the hydrofluoric acid is 1:180-220.

[0009] In the present invention, the amount of manganous oxide added is relatively small, and hydrofluoric acid and potassium hydroxide are added in excess, and the excess potassium can promote the precipitation of potassium hexafluoromanganate in the subsequent reaction, thereby improving the yield of the product.

[0010] As a further technical solution, in step S2, the reaction temperature is 80-85°C, and the reaction time is 1-2h.

[0011] As a further technical solution, in step S2, the freezing temperature is -15~-20°C.

[0012] In the present invention, by limiting the freezing temperature to below -15°C, the stability of the product can be improved.

[0013] As a further technical solution, in step S3, the mass ratio of the potassium permanganate to the manganous oxide is 1.49-1.51:1.

[0014] As a further technical solution, in step S3, the stirring temperature is 5-15°C, and the stirring time is 10-15 minutes.

[0015] As a further technical solution, the purification of potassium hexafluoromanganate includes sedimentation, filtration, washing and drying.

[0016] As a further technical solution, the sedimentation time is 5 to 10 minutes; the washing solvent is ethanol; the washing times are 2 to 3 times; the drying temperature is 100 to 120° C., and the drying time is 3 to 5 hours.

[0017] As a further technical solution, in step S1, the mass concentration of the hydrofluoric acid is 50%.

[0018] Reaction equation of the present invention is: KOH+HF=KF+H2O 2KF+MnO+2HF=K2MnF4+H2O 3K2MnF4+2KMnO4+16HF+2KF=5K2MnF6+8H2O The working principle and beneficial effects of the present invention are: In the present invention, the characteristics of manganous oxide being soluble in acid and potassium permanganate being soluble in water are utilized to neutralize the divalent manganese ions and the heptavalent manganese ions, thereby obtaining the tetravalent manganese required for potassium hexafluoromanganate. No other impurities are introduced during the process, and the reaction temperature is controlled to prevent the potassium hexafluoromanganate from being hydrolyzed, thereby improving the purity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0020] Figure 1 This is the XRD spectrum of potassium hexafluoromanganate prepared in Example 1. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 A method for preparing high-purity potassium hexafluoromanganate comprises the following steps: S1, add 10kg 50wt% HF into a tetrafluoroethylene reactor, add 2kg KOH, control the free acid content to 38.9%, the potassium content to 10.09%, and obtain a mixed solution of potassium fluoride and hydrofluoric acid; S2, add 50g of manganous oxide to the mixed solution of potassium fluoride and hydrofluoric acid, heat to 85°C and stir to react for 1.5h, dissolve until transparent, filter through a 0.1μm precision filter, put into a freezer and freeze to -15°C to obtain a mixed solution whose main components are manganese, potassium, fluorine and hydrogen ions; S3. Add a mixed solution whose main components are manganese, potassium, fluorine and hydrogen ions into a PP reactor, stir at a speed of 150 rpm / min, slowly add 71 g of potassium permanganate thereto, the reaction color changes from dark brown to stable lavender, and a golden precipitate appears at the bottom. During the process, control the temperature below 15° C. and continue stirring for 10 min to obtain a potassium hexafluoromanganate synthetic solution; S4. After the potassium hexafluoromanganate synthetic solution was settled for 5 minutes, the upper solution was removed, the bottom precipitate was taken out, filtered, the filter cake was washed twice with ethanol, the filter cake was placed in a tetrafluoro crucible, and dried at 120°C for 5 hours to obtain 219.8g of potassium hexafluoromanganate finished product. The impurity content of the obtained potassium hexafluoromanganate finished product was tested by ICP-OES-5110, and the test results are shown in Table 1; the XRD spectrum of potassium hexafluoromanganate prepared in this embodiment is shown in Figure 1 shown.

[0023] Table 1 Purity determination results of potassium hexafluoromanganate in Example 1

[0024] Example 2 A method for preparing high-purity potassium hexafluoromanganate comprises the following steps: S1, add 50kg 50wt% HF into a tetrafluoroethylene reactor, add 10kg KOH, control the free acid content to 40.63%, the potassium content to 11.27%, and obtain a mixed solution of potassium fluoride and hydrofluoric acid; S2, add 250g of manganous oxide to the mixed solution of potassium fluoride and hydrofluoric acid, heat to 80°C and stir to react for 1.5h, dissolve until transparent, filter through a 0.1μm precision filter, put into a freezer and freeze to -20°C to obtain a mixed solution whose main components are manganese, potassium, fluorine and hydrogen ions; S3. Add a mixed solution whose main components are manganese, potassium, fluorine and hydrogen ions into a PP reactor, stir at a speed of 150 rpm / min, slowly add 371 g of potassium permanganate thereto, the reaction color changes from dark brown to stable lavender, and a golden precipitate appears at the bottom. During the process, control the temperature below 15° C. and continue stirring for 15 min to obtain a potassium hexafluoromanganate synthetic solution; S4, after the potassium hexafluoromanganate synthetic solution was settled for 10 minutes, the upper solution was removed, the bottom precipitate was taken out, filtered, the filter cake was washed 3 times with ethanol, the filter cake was placed in a tetrafluoro crucible, and dried at 120°C for 3 hours to obtain 1116.1g of potassium hexafluoromanganate finished product. The obtained potassium hexafluoromanganate finished product was tested for impurity content therein by ICP-OES-5110, and the test results are shown in Table 2.

[0025] Table 2 Purity determination results of potassium hexafluoromanganate in Example 2

[0026] Example 3 A method for preparing high-purity potassium hexafluoromanganate comprises the following steps: S1, add 100kg 50wt% HF into a tetrafluoroethylene reactor, add 20kg KOH, control the free acid content to 39.96%, and the potassium content to 10.88%, to obtain a mixed solution of potassium fluoride and hydrofluoric acid; S2, add 500g of manganous oxide to the mixed solution of potassium fluoride and hydrofluoric acid, heat to 80°C and stir to react for 1h, dissolve until transparent, filter through a 0.1μm precision filter, put into a freezer and freeze to -20°C to obtain a mixed solution whose main components are manganese, potassium, fluorine and hydrogen ions; S3, adding a mixed solution whose main components are manganese, potassium, fluorine and hydrogen ions into a PP reactor, stirring at a speed of 150 rpm / min, slowly adding 738 g of potassium permanganate thereto, the reaction color changes from dark brown to stable lavender, and a golden precipitate appears at the bottom, the temperature is controlled below 15°C during the process, and stirring is continued for 15 minutes to obtain a potassium hexafluoromanganate synthetic solution; S4, after the potassium hexafluoromanganate synthetic solution was settled for 10 minutes, the upper solution was removed, the bottom precipitate was taken out, filtered, the filter cake was washed 3 times with ethanol, the filter cake was placed in a tetrafluoro crucible, and dried at 120°C for 5 hours to obtain 2224.3g of potassium hexafluoromanganate finished product. The obtained potassium hexafluoromanganate finished product was tested for impurity content therein by ICP-OES-5110, and the test results are shown in Table 3.

[0027] Table 3 Purity determination results of potassium hexafluoromanganate in Example 3

[0028] It can be obtained from the test data of potassium hexafluoromanganate prepared in Examples 1 to 3 that potassium hexafluoromanganate is prepared by adopting the redox reaction of manganous oxide and potassium permanganate. The potassium hexafluoromanganate prepared by this method has high purity, meets the use requirements of high-end products, and has a high yield, which promotes the industrial production of high-purity potassium hexafluoromanganate.

[0029] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-purity potassium hexafluoromanganate, characterized in that: The following steps are involved: S1, mixing hydrofluoric acid and potassium hydroxide to obtain a mixed solution I; S2, adding manganous oxide to the mixed solution I, reacting, filtering and freezing to obtain a mixed solution II; S3. Add potassium permanganate into the mixed solution II, and obtain potassium hexafluoromanganate after stirring.

2. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, wherein: In step S1, the mass ratio of the potassium hydroxide to the hydrofluoric acid is 1:5-6.

3. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: In step S2, the mass ratio of the manganous oxide to the hydrofluoric acid is 1:180-220.

4. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: In step S2, the reaction temperature is 80-85° C., and the reaction time is 1-2 h.

5. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: In step S2, the freezing temperature is -15~-20°C.

6. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: In step S3, the mass ratio of the potassium permanganate to the manganous oxide is 1.49-1.51:

1.

7. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: In step S3, the stirring temperature is 5-15° C., and the stirring time is 10-15 min.

8. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: The purification of potassium hexafluoromanganate includes sedimentation, filtration, washing and drying.

9. The method for preparing high-purity potassium hexafluoromanganate according to claim 8, characterized in that: The sedimentation time is 5 to 10 minutes; the washing solvent is ethanol; the washing times are 2 to 3 times; the drying temperature is 100 to 120° C., and the drying time is 3 to 5 hours.

10. The method for preparing high-purity potassium hexafluoromanganate according to claim 1, characterized in that: In step S1, the mass concentration of the hydrofluoric acid is 50%.

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