A continuous process for the production of phosphorus pentafluoride

Abstract

The application discloses a continuous production method of phosphorus pentafluoride, belongs to the technical field of phosphorus pentafluoride production, and adopts diaphosphorus pentoxide and anhydrous hydrogen fluoride to synthesize a hexafluorophosphoric acid aqueous solution; when starting for the first time, the anhydrous hydrogen fluoride solution is used as a reaction substrate; when normally operating, the hexafluorophosphoric acid aqueous solution is used as the reaction substrate; by continuously feeding the diaphosphorus pentoxide and liquid hydrogen fluoride, and continuously discharging the hexafluorophosphoric acid aqueous solution, the continuous synthesis of the hexafluorophosphoric acid is realized, and a prerequisite for the continuous synthesis of the phosphorus pentafluoride is provided. The reaction time for synthesizing the hexafluorophosphoric acid is greatly reduced, the liquid reaction system has high heat transfer efficiency, temperature control is easier, the strength requirement of a stirrer is greatly reduced, and the method has extremely high engineering value.

Description

Technical Field

[0001] This invention relates to the field of phosphorus pentafluoride production technology, and more specifically to a continuous production method for phosphorus pentafluoride. Background Technology

[0002] Phosphorus pentafluoride (PF5) is a gaseous substance at room temperature used in the electronics industry as a fluorinating agent in various chemical reactions. It is particularly important as a starting material for manufacturing hexafluorophosphates (DPF6, D = Li, Na, K, etc.) used in battery electrolytes. In the case of D = Li, lithium hexafluorophosphate is a crucial electrolyte for lithium-ion batteries. Lithium hexafluorophosphate is exceptionally safe and possesses excellent physical properties, making it a highly anticipated and indispensable material in lithium-ion secondary batteries, with significant potential for future applications in hybrid vehicles.

[0003] Chinese patent CN101570328A, published on June 12, 2013, describes a method for preparing an aqueous solution of hexafluorophosphate by reacting phosphorus pentoxide with anhydrous hydrogen fluoride. Fuming sulfuric acid is then added, and the solution is decomposed at 150°C to produce phosphorus pentafluoride. The decomposed phosphorus pentafluoride is then condensed at -40°C to obtain clean phosphorus pentafluoride, which is then reacted with lithium fluoride in a hydrogen fluoride solvent to synthesize lithium hexafluorophosphate. This method uses phosphorus pentoxide as the reaction substrate, with liquid anhydrous hydrogen fluoride added dropwise under stirring, and the reaction temperature controlled at around 0°C. However, because phosphorus pentoxide is a solid powder, the addition of liquid hydrogen fluoride inevitably leads to intense localized exothermic reactions, making temperature control extremely difficult. Furthermore, once a certain amount of hydrogen fluoride is added, a large amount of solid agglomerates appear in the reaction apparatus, making stirring extremely difficult and further increasing the difficulty of cooling. Therefore, this patented method is unlikely to be industrially viable.

[0004] Chinese patent CN104261369A, published on July 21, 2023, uses the reaction of polyphosphoric acid and hydrogen fluoride. Although this solves the problem of difficult heat transfer and difficulty in industrialization in the synthesis of hexafluorophosphoric acid aqueous solution, this method will cause a significant increase in the water content of the hexafluorophosphoric acid aqueous solution, which will inevitably lead to a significant increase in fuming sulfuric acid and a significant increase in the amount of by-product sulfuric acid. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, this invention provides a continuous production method for phosphorus pentafluoride. The method uses phosphorus pentoxide and anhydrous hydrogen fluoride to synthesize an aqueous solution of hexafluorophosphate. During initial startup, anhydrous hydrogen fluoride solution is used as the reaction substrate. During normal operation, the aqueous solution of hexafluorophosphate is used as the reaction substrate. By continuously adding phosphorus pentoxide and liquid hydrogen fluoride while simultaneously continuously extracting the aqueous solution of hexafluorophosphate, continuous synthesis of hexafluorophosphate is achieved, providing the prerequisites for continuous phosphorus pentafluoride synthesis. This significantly reduces the reaction time for hexafluorophosphate synthesis. Furthermore, the liquid reaction system offers high heat transfer efficiency, making temperature control easier and reducing the requirements for the strength of the stirrer, thus possessing significant engineering value.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A continuous production method for phosphorus pentafluoride includes the following steps:

[0008] Step 1: Add anhydrous hydrogen fluoride to the hexafluorophosphate synthesis reactor. The molar ratio of hydrogen fluoride to phosphorus pentoxide is 12~24:1. Start stirring and cooling, and control the temperature inside the synthesis reactor at -5~5℃.

[0009] Step 2: Open the compressed air inlet valve and fully open the phosphorus pentoxide feed valve to continuously feed phosphorus pentoxide powder into the synthesis reactor; at the same time, open the anhydrous hydrogen fluoride feed valve to continuously introduce anhydrous hydrogen fluoride into the hexafluorophosphate synthesis reactor.

[0010] Step 3: The reaction tail gas in the hexafluorophosphate synthesis reactor is condensed by a condenser and the condensed hydrogen fluoride is returned to the synthesis reactor; the uncondensed tail gas is discharged after passing through the tail gas scrubbing system.

[0011] Step 4: Once the liquid level in the hexafluorophosphate synthesis reactor reaches 70%~80%, the hexafluorophosphate synthesis reactor will begin to continuously extract hexafluorophosphate aqueous solution.

[0012] Step 5: When the liquid level in the decomposition vessel reaches 40%~50% of the total liquid level in the decomposition vessel, the hexafluorophosphate aqueous solution is switched to other decomposition vessels. Then, fuming sulfuric acid is added to the decomposition vessel containing the hexafluorophosphate aqueous solution to prepare for heating and decomposition.

[0013] Step 6: After adding fuming sulfuric acid, the hexafluorophosphoric acid solution is heated to 100~200℃ to decompose and release crude phosphorus pentafluoride gas. The crude phosphorus pentafluoride gas is then condensed and dried at -60~-70℃ to obtain phosphorus pentafluoride product gas.

[0014] Preferably, in step one, the flow rate of phosphorus pentoxide powder is controlled to be 0.5 kg / min by the speed of the feeding screw, the stirring speed is 50~200 r / min, and cooling is achieved using -15℃ low-temperature heat transfer oil.

[0015] Preferably, in step two, the ratio of phosphorus pentoxide powder to compressed air is 0.1:1.

[0016] Preferably, in step three, the temperature of the condenser reflux condenser is set to -5~0℃.

[0017] Preferably, in step three, the condensed uncondensed exhaust gas is washed with water at room temperature, then washed with alkaline solution at room temperature, and finally discharged into the air.

[0018] Preferably, in step four, phosphorus pentoxide and liquid hydrogen fluoride are continuously added, and hexafluorophosphate aqueous solution is continuously extracted to maintain a constant liquid level in the reactor.

[0019] Preferably, in step five, the molar ratio of free sulfur trioxide in fuming sulfuric acid to phosphorus in the hexafluorophosphate aqueous solution is 3 to 5.

[0020] Preferably, in step six, the purified phosphorus pentafluoride has a purity greater than 99%.

[0021] The beneficial effects of this technical solution are as follows:

[0022] I. This invention provides a continuous production method for phosphorus pentafluoride, which uses phosphorus pentoxide and anhydrous hydrogen fluoride to synthesize an aqueous solution of hexafluorophosphate. During initial startup, anhydrous hydrogen fluoride solution is used as the reaction substrate; during normal operation, the aqueous solution of hexafluorophosphate is used as the reaction substrate. By continuously adding phosphorus pentoxide and liquid hydrogen fluoride while simultaneously continuously extracting the aqueous solution of hexafluorophosphate, continuous synthesis of hexafluorophosphate is achieved, providing a prerequisite for the continuous synthesis of phosphorus pentafluoride or lithium hexafluorophosphate. This significantly reduces the reaction time for synthesizing hexafluorophosphate. Furthermore, the liquid reaction system has high heat transfer efficiency, making temperature control easier and reducing the strength requirements for the stirrer. It solves the problem of the difficulty in engineering the preparation of phosphorus pentafluoride using phosphorus pentoxide as a raw material, and has extremely high engineering value.

[0023] II. This invention provides a continuous production method for phosphorus pentafluoride. Using phosphorus pentoxide as raw material, this method significantly reduces the amount of byproduct sulfuric acid (by more than one-third) compared to using polyphosphoric acid as raw material (as in current industrial methods). Furthermore, it lowers the temperature required for the decomposition of hexafluorophosphoric acid, saving energy and reducing the requirements for the decomposition vessel material (the decomposition temperature is approximately 30°C lower than when using polyphosphoric acid as raw material).

[0024] Third, the continuous production method of phosphorus pentafluoride provided by the present invention uses compressed air to blow phosphorus pentoxide into the synthesis reactor, which can avoid the reaction of phosphorus pentoxide at the pipe opening and the resulting pipe blockage. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the continuous production system for phosphorus pentafluoride in this invention;

[0026] In the diagram: 1. Synthesis vessel; 2. Decomposition vessel; 3. Anhydrous hydrogen fluoride inlet pipe; 4. Phosphorus pentoxide inlet pipe; 5. Condenser reflux condenser; 6. Hexafluorophosphate aqueous solution feed pipe; 7. Fuming sulfuric acid inlet pipe; 8. Phosphorus pentafluoride refining system; 81. Condenser; 82. Gas-liquid separator; 9. Phosphorus pentoxide powder silo; 10. Compressed air inlet pipe; 11. Molecular sieve tower drying device; 12. Tail gas scrubbing system; 121. Water scrubbing tower; 122. Alkali scrubbing tower; 13. Hydrogen fluoride feed valve; 14. Phosphorus pentoxide feed valve; 15. Compressed air inlet valve; 16. First thermometer. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0028] like Figure 1 As shown, a continuous production system for phosphorus pentafluoride includes a hexafluorophosphate synthesis reactor 1 and a hexafluorophosphate decomposition reactor 2. The hexafluorophosphate synthesis reactor 1 is connected to anhydrous hydrogen fluoride inlet pipe 3, phosphorus pentoxide inlet pipe 4, and a condenser reflux 5. The hexafluorophosphate synthesis reactor 1 and the hexafluorophosphate decomposition reactor 2 are connected by a hexafluorophosphate aqueous solution feed pipe 6. The hexafluorophosphate decomposition reactor 2 is also connected to a fuming sulfuric acid inlet pipe 7 and a phosphorus pentafluoride refining system 8.

[0029] The phosphorus pentafluoride refining system 8 includes a condenser 81 and a gas-liquid separator 82.

[0030] The phosphorus pentoxide inlet pipe 4 is connected to the phosphorus pentoxide powder silo 9 and the compressed air inlet pipe 10.

[0031] The compressed air inlet pipe 10 is equipped with a molecular sieve tower drying device 11.

[0032] The phosphorus pentoxide powder silo 9 is equipped with a screw feeder at its lower end.

[0033] The condenser reflux unit 5 is also connected to the exhaust gas scrubbing system 12.

[0034] The exhaust gas scrubbing system 12 includes a water scrubbing tower 121 and an alkaline scrubbing tower 122 connected in sequence.

[0035] The anhydrous hydrogen fluoride inlet pipe 3 is equipped with a hydrogen fluoride inlet valve 13, the phosphorus pentoxide inlet pipe 4 is equipped with a phosphorus pentoxide inlet valve 14, and the compressed air inlet pipe 10 is equipped with a compressed air inlet valve 15.

[0036] The hexafluorophosphate synthesis reactor 1 is equipped with a first thermometer 16.

[0037] It also includes a DCS (Distributed Control System), which is connected to the hydrogen fluoride feed valve 13, the phosphorus pentoxide feed valve 14, the compressed air intake valve 15, and the first thermometer 16.

[0038] Examples 1 to 3 and Comparative Examples 1 to 4 all used the above-described continuous production system for phosphorus pentafluoride.

[0039] Example 1

[0040] A continuous production method for phosphorus pentafluoride includes the following steps:

[0041] Step 1: Add anhydrous hydrogen fluoride to hexafluorophosphate synthesis reactor 1. The molar ratio of hydrogen fluoride to phosphorus pentoxide is 12:1. Start stirring and cooling, and control the temperature inside the synthesis reactor 1 at -5℃ (the first thermometer 16 shows -5℃). Control the flow rate of phosphorus pentoxide powder to 0.5kg / min by the speed of the feeding screw, and the stirring speed to 50r / min. Utilize -15℃ low-temperature heat transfer oil for cooling.

[0042] Step 2: Open the compressed air inlet valve 15 and the fully open phosphorus pentoxide feed valve 14 to continuously feed phosphorus pentoxide powder into the synthesis reactor 1. The ratio of phosphorus pentoxide powder to compressed air is 0.1:1. At the same time, open the anhydrous hydrogen fluoride feed valve 13 to continuously feed anhydrous hydrogen fluoride into the hexafluorophosphate synthesis reactor 1.

[0043] Step 3: The reaction tail gas in the hexafluorophosphate synthesis reactor 1 is condensed by the condenser reflux 5. The temperature of the condenser reflux 5 is set to -5℃, and the condensed hydrogen fluoride is returned to the synthesis reactor 1. The uncondensed tail gas is discharged after passing through the tail gas washing system 12. The condensed uncondensed tail gas is then washed with water spray and then washed with alkali spray before being discharged into the air.

[0044] Step 4: After the liquid level in the hexafluorophosphate synthesis reactor 1 reaches 70%, phosphorus pentoxide and liquid hydrogen fluoride are continuously added, and the hexafluorophosphate aqueous solution is continuously extracted to maintain the liquid level in the synthesis reactor 1.

[0045] Step 5: When the liquid level in decomposition vessel 2 reaches 40% of the total liquid level in decomposition vessel 2, the hexafluorophosphate aqueous solution is switched to other decomposition vessels 2. Then, fuming sulfuric acid is added dropwise to the decomposition vessel 2 containing the hexafluorophosphate aqueous solution to prepare for heating and decomposition. The molar ratio of free sulfur trioxide in the fuming sulfuric acid to phosphorus in the hexafluorophosphate aqueous solution is 3.

[0046] Step 6: After adding fuming sulfuric acid, the hexafluorophosphoric acid solution is heated to 100°C to decompose and release crude phosphorus pentafluoride gas. The crude phosphorus pentafluoride gas is then condensed and dried at -60°C to obtain the phosphorus pentafluoride product gas.

[0047] The obtained phosphorus pentafluoride gas was reacted with excess lithium fluoride. By detecting the content of lithium hexafluorophosphate and the total mass increase during the synthesis of lithium hexafluorophosphate, the purity of phosphorus pentafluoride was calculated to be 99.1%, and the yield was 55%.

[0048] Example 2

[0049] A continuous production method for phosphorus pentafluoride includes the following steps:

[0050] Step 1: Add anhydrous hydrogen fluoride to hexafluorophosphate synthesis reactor 1. The molar ratio of hydrogen fluoride to phosphorus pentoxide is 18:1. Start stirring and cooling, and control the temperature inside the synthesis reactor 1 at 0℃ (the first thermometer 16 shows 0℃). Control the flow rate of phosphorus pentoxide powder to 0.5 kg / min by the speed of the feeding screw, and the stirring speed to 125 r / min. Use -15℃ low-temperature heat transfer oil for cooling.

[0051] Step 2: Open the compressed air inlet valve 15 and the fully open phosphorus pentoxide feed valve 14 to continuously feed phosphorus pentoxide powder into the synthesis reactor 1. The ratio of phosphorus pentoxide powder to compressed air is 0.1:1. At the same time, open the anhydrous hydrogen fluoride feed valve 13 to continuously feed anhydrous hydrogen fluoride into the hexafluorophosphate synthesis reactor 1.

[0052] Step 3: The reaction tail gas in the hexafluorophosphate synthesis reactor 1 is condensed by the condenser reflux 5. The temperature of the condenser reflux 5 is set to -2℃, and the condensed hydrogen fluoride is returned to the synthesis reactor 1. The uncondensed tail gas is discharged after passing through the tail gas washing system 12. The condensed uncondensed tail gas is then washed with water spray and then washed with alkali spray before being discharged into the air.

[0053] Step 4: After the liquid level in the hexafluorophosphate synthesis reactor 1 reaches 75%, continuously add phosphorus pentoxide and liquid hydrogen fluoride, and continuously extract the hexafluorophosphate aqueous solution to maintain the liquid level in the synthesis reactor 1.

[0054] Step 5: When the liquid level in decomposition vessel 2 reaches 45% of the total liquid level in decomposition vessel 2, the hexafluorophosphate aqueous solution is switched to other decomposition vessels 2. Then, fuming sulfuric acid is added dropwise to the decomposition vessel 2 containing the hexafluorophosphate aqueous solution to prepare for heating and decomposition. The molar ratio of free sulfur trioxide in the fuming sulfuric acid to phosphorus in the hexafluorophosphate aqueous solution is 4.

[0055] Step 6: After adding fuming sulfuric acid, the hexafluorophosphoric acid solution is heated to 150°C to decompose and release crude phosphorus pentafluoride gas. The crude phosphorus pentafluoride gas is then condensed and dried at -65°C to obtain the phosphorus pentafluoride product gas.

[0056] The obtained phosphorus pentafluoride gas was reacted with excess lithium fluoride. By detecting the content of lithium hexafluorophosphate and the total mass increase during the synthesis of lithium hexafluorophosphate, the purity of phosphorus pentafluoride was calculated to be 99.3% and the yield was 76%.

[0057] Example 3

[0058] A continuous production method for phosphorus pentafluoride includes the following steps:

[0059] Step 1: Add anhydrous hydrogen fluoride to hexafluorophosphate synthesis reactor 1. The molar ratio of hydrogen fluoride to phosphorus pentoxide is 24:1. Start stirring and cooling, and control the temperature inside the synthesis reactor 1 at 5℃ (the first thermometer 16 shows 5℃). Control the flow rate of phosphorus pentoxide powder to 0.5kg / min by the speed of the feeding screw, and the stirring speed to 200r / min. Use -15℃ low-temperature heat transfer oil for cooling.

[0060] Step 2: Open the compressed air inlet valve 15 and the fully open phosphorus pentoxide feed valve 14 to continuously feed phosphorus pentoxide powder into the synthesis reactor 1. The ratio of phosphorus pentoxide powder to compressed air is 0.1:1. At the same time, open the anhydrous hydrogen fluoride feed valve 13 to continuously feed anhydrous hydrogen fluoride into the hexafluorophosphate synthesis reactor 1.

[0061] Step 3: The reaction tail gas in the hexafluorophosphate synthesis reactor 1 is condensed by the condenser reflux 5. The temperature of the condenser reflux 5 is set to 0°C, and the condensed hydrogen fluoride is returned to the synthesis reactor 1. The uncondensed tail gas is discharged after passing through the tail gas washing system 12. The condensed uncondensed tail gas is then washed with water spray and then washed with alkali spray before being discharged into the air.

[0062] Step 4: After the liquid level in the hexafluorophosphate synthesis reactor 1 reaches 80%, continuously add phosphorus pentoxide and liquid hydrogen fluoride, and continuously extract the hexafluorophosphate aqueous solution to maintain the liquid level in the synthesis reactor 1.

[0063] Step 5: When the liquid level in decomposition vessel 2 reaches 50% of the total liquid level in decomposition vessel 2, switch the hexafluorophosphate aqueous solution to another decomposition vessel 2. Then, add fuming sulfuric acid dropwise to the decomposition vessel 2 containing the hexafluorophosphate aqueous solution to prepare for heating and decomposition. The molar ratio of free sulfur trioxide in the fuming sulfuric acid to phosphorus in the hexafluorophosphate aqueous solution is 5.

[0064] Step 6: After adding fuming sulfuric acid, the hexafluorophosphoric acid solution is heated to 200°C to decompose and release crude phosphorus pentafluoride gas. The crude phosphorus pentafluoride gas is then condensed and dried at -70°C to obtain the phosphorus pentafluoride product gas.

[0065] The obtained phosphorus pentafluoride gas was reacted with excess lithium fluoride. By detecting the content of lithium hexafluorophosphate and the total mass increase during the synthesis of lithium hexafluorophosphate, the purity of phosphorus pentafluoride was calculated to be 99% and the yield was 91%.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that the molar ratio of hydrogen fluoride to phosphorus pentoxide is 10:1.

[0068] The obtained phosphorus pentafluoride gas was reacted with excess lithium fluoride. By detecting the content of lithium hexafluorophosphate and the total mass increase during the synthesis of lithium hexafluorophosphate, the purity of phosphorus pentafluoride was calculated to be 96.5%, and the yield was 23%.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 3 is that the molar ratio of hydrogen fluoride to phosphorus pentoxide is 26:1.

[0071] The obtained phosphorus pentafluoride gas was reacted with excess lithium fluoride. By detecting the content of lithium hexafluorophosphate and the total increase in mass during the synthesis of lithium hexafluorophosphate, the purity of phosphorus pentafluoride was calculated to be 99%, and the yield was 92%, which was not significantly improved compared with Example 3.

[0072] Comparative Example 3

[0073] The difference between this comparative example and Example 2 is that the temperature inside the synthesis reactor 1 is controlled at -10°C; the material inside the synthesis reactor solidifies.

[0074] Comparative Example 4

[0075] The difference between this comparative example and Example 2 is that the molar ratio of free sulfur trioxide in fuming sulfuric acid to phosphorus in the aqueous solution of hexafluorophosphate is 8, resulting in phosphorus pentafluoride with a purity of 99% and a yield of 40%.

[0076] Finally, it should be noted that the above embodiments are only for illustration and not for limiting the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A continuous production method for phosphorus pentafluoride, characterized in that, Includes the following steps: Step 1: Add anhydrous hydrogen fluoride to the hexafluorophosphate synthesis reactor, start stirring and cooling, and control the temperature inside the synthesis reactor at -5~5℃; Step 2: Open the compressed air inlet valve and fully open the phosphorus pentoxide feed valve to continuously feed phosphorus pentoxide powder into the synthesis reactor; at the same time, open the anhydrous hydrogen fluoride feed valve to continuously pass anhydrous hydrogen fluoride into the hexafluorophosphate synthesis reactor. The molar ratio of anhydrous hydrogen fluoride to phosphorus pentoxide is 12~24:

1. Step 3: The reaction tail gas in the hexafluorophosphate synthesis reactor is condensed by a condenser and the condensed hydrogen fluoride is returned to the synthesis reactor; the uncondensed tail gas is discharged after passing through the tail gas scrubbing system. Step 4: Once the liquid level in the hexafluorophosphate synthesis reactor reaches 70%~80%, the hexafluorophosphate synthesis reactor will begin to continuously extract hexafluorophosphate aqueous solution. Step 5: When the liquid level in the decomposition vessel reaches 40%~50% of the total liquid level in the decomposition vessel, the hexafluorophosphate aqueous solution is switched to other decomposition vessels. Then, fuming sulfuric acid is added to the decomposition vessel containing the hexafluorophosphate aqueous solution to prepare for heating and decomposition. Step 6: After adding fuming sulfuric acid, the hexafluorophosphoric acid solution is heated to 100~200℃ to decompose and release crude phosphorus pentafluoride gas. The crude phosphorus pentafluoride gas is then condensed and dried at -60~-70℃ to obtain phosphorus pentafluoride product gas.

2. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step one, the flow rate of phosphorus pentoxide powder is controlled to be 0.5 kg / min by the speed of the feeding screw, the stirring speed is 50~200 r / min, and cooling is achieved using -15℃ low temperature heat transfer oil.

3. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step two, the ratio of phosphorus pentoxide powder to compressed air is 0.1:

1.

4. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step three, the temperature of the condenser reflux condenser is set to -5~0℃.

5. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step three, the condensed uncondensed exhaust gas is washed with water at room temperature, then washed with alkaline solution at room temperature, and finally discharged into the air.

6. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step four, phosphorus pentoxide and liquid hydrogen fluoride are continuously added, and hexafluorophosphate aqueous solution is continuously extracted to maintain a constant liquid level in the reactor.

7. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step five, the molar ratio of free sulfur trioxide in fuming sulfuric acid to phosphorus in the aqueous solution of hexafluorophosphate is 3 to 5.

8. The continuous production method of phosphorus pentafluoride according to claim 1, characterized in that: In step six, the purified phosphorus pentafluoride has a purity greater than 99%.

Images