System and method for continuous synthesis of lithium hexafluorophosphate
By adopting continuous synthesis systems and methods in the production of lithium hexafluorophosphate, the reaction contact time and area are increased, and the problems of low production efficiency and low product purity in the existing technology are solved, and efficient and low-cost lithium hexafluorophosphate production are achieved, improving product quality.
Patent Information
- Application Number
- CN202411701556.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-04-04
AI Technical Summary
The existing hydrofluoric acid solvent method uses batch production method, resulting in low efficiency and high cost; the products produced by the organic solvent method are relatively low in purity and are easy to adsorb organic solvents, which are difficult to get rid of.
The system and method for continuously synthesizing lithium hexafluorophosphate is adopted. By setting up the front and rear reactors and the reaction towers on the reactor, the contact time and contact area between the phosphorus pentafluoride and the lithium fluoride hydrofluoric acid solution are increased to achieve continuous synthesis reaction, and the utilization rate of phosphorus pentafluoride is ensured by setting up an absorption tower.
It improves the production efficiency and product quality of lithium hexafluorophosphate, reduces the waste of raw materials and production costs, and ensures the high purity and good performance of the product.
Smart Images
Figure CN119746766A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of lithium hexafluorophosphate production methods, specifically relating to a system for the continuous synthesis of lithium hexafluorophosphate. This invention also relates to a method for the continuous synthesis of lithium hexafluorophosphate. Background Technology
[0002] Lithium hexafluorophosphate (LiPF6) is the most critical solute in the electrolyte, which is one of the four major components of a lithium battery. It is currently the most widely used solute in commercially available lithium batteries and accounts for a significant portion of the electrolyte cost. It possesses good ion transference number, a moderate dissociation constant, high conductivity and electrochemical stability, good oxidation resistance, and excellent aluminum foil passivation capability, while also being compatible with various positive and negative electrode materials.
[0003] Currently, there are six main production methods for lithium hexafluorophosphate: organic solvent method, hydrofluoric acid solvent method, gas-solid reaction method, rheological phase method, solid-solid method, and ion exchange method. Among these, the hydrofluoric acid solvent method and the organic solvent method are the most widely used in the market, while the other four production processes have not yet achieved large-scale industrial production. The hydrofluoric acid solvent method involves dissolving LiF in anhydrous HF to form a LiF·HF solution, then introducing high-purity PF5 gas to react and obtain LiPF6 crystals, which are then separated and dried to obtain the LiPF6 product. The organic solvent method involves dissolving solid LiF in an organic solvent (such as carbonates), then introducing high-purity PF5 gas; the resulting LiPF6 is directly dissolved in the organic solvent, and the resulting solvent can be directly used as an electrolyte for lithium-ion batteries.
[0004] Currently, the hydrofluoric acid solvent method for producing lithium hexafluorophosphate often employs an intermittent production approach, which not only results in a long preparation cycle for lithium hexafluorophosphate but also leads to relatively high production costs. The organic solvent method for producing lithium hexafluorophosphate often produces products with lower purity, as the products easily adsorb organic solvents, making further removal difficult. Summary of the Invention
[0005] The purpose of this invention is to provide a system for the continuous synthesis of lithium hexafluorophosphate, which solves the problems of low efficiency and high cost of the intermittent production method used in the existing hydrofluoric acid solvent method for producing lithium hexafluorophosphate.
[0006] Another object of the present invention is to provide a method for the continuous synthesis of lithium hexafluorophosphate.
[0007] The first technical solution adopted in this invention is: a system for continuous synthesis of lithium hexafluorophosphate, including a synthesis vessel, a gas feed pipe that extends into the bottom of the synthesis vessel, a discharge pipe that connects the bottom of the synthesis vessel to the outside, and a front and rear reaction vessels that are connected to the top of the synthesis vessel through a pipe. Each stage of the reaction vessel is connected to a reaction tower above its top. The top of the front reaction tower is connected to the rear reaction vessel through a pipe, and the top of the rear reaction tower is connected to an absorption tower through a pipe. The top of the absorption tower is connected to a liquid inlet pipe.
[0008] The first technical solution of the present invention is further characterized in that, The two-stage reactor is equipped with a pre-stage air inlet pipe that extends into its bottom. The pre-stage air inlet pipe is connected to the top of the synthesis reactor through a pre-stage gas delivery pipe. The bottom of the pre-stage reactor is connected to the top of the synthesis reactor through a synthesis liquid delivery pipe. A synthesis delivery pump is connected to the synthesis liquid delivery pipe.
[0009] The downstream reactor is equipped with a downstream air inlet pipe that extends into its bottom. The downstream air inlet pipe is connected to the top of the upstream reaction tower via a downstream gas delivery pipe. The bottom of the downstream reactor is connected to the top of the upstream reaction tower via a upstream liquid delivery pipe. A upstream delivery pump is connected to the upstream liquid delivery pipe.
[0010] The bottom of the absorption tower is connected to the top of the subsequent reaction tower via an absorption gas supply pipeline, and the bottom of the absorption tower is connected to the top of the subsequent reaction tower via a subsequent liquid supply pipeline. A subsequent delivery pump is connected to the subsequent liquid supply pipeline.
[0011] The top of the absorption tower is connected to a condenser via a condensation gas supply pipe. The bottom of the condenser is connected to one side of the absorption tower via a condensation gravity flow pipe. A U-shaped liquid seal pipe connects the condenser and the condensation gravity flow pipe. An exhaust pipe is connected to the condenser.
[0012] Level gauges are installed in the synthesis reactor, the pre-stage reactor, the post-stage reactor, and the absorption tower.
[0013] A flow meter is installed on the inlet pipeline.
[0014] The pre-stage reaction tower, post-stage reaction tower, and absorption tower are all packed towers.
[0015] An air inlet line is connected to the top of the gas feed pipe.
[0016] The second technical solution adopted in this invention is a method for continuous synthesis of lithium hexafluorophosphate. PF5 gas from the inlet pipeline is fed into the synthesis reactor through a gas feed pipe, and LiF·HF solution is fed into the absorption tower through a liquid feed pipe. The PF5 gas introduced through the gas feed pipe enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor and reacts with the incompletely reacted LiF. Excess PF5 gas sequentially enters the pre-stage reactor, pre-stage reaction tower, post-stage reactor, and post-stage reaction tower to react with the unreacted LiF in the mixed solution. The remaining PF5 gas enters the absorption tower and is absorbed by the LiF·HF solution fed through the liquid feed pipe. The LiPF6, LiF, and HF mixed solution obtained after the LiF·HF solution absorbs the PF5 gas is sequentially fed into the post-stage reaction tower, post-stage reactor, pre-stage reaction tower, pre-stage reactor, and synthesis reactor to synthesize LiPF6 through the reaction of LiF and PF5 gas. The resulting pure LiPF6 and HF solution are periodically discharged to the crystallization process through the discharge pipeline.
[0017] The beneficial effects of this invention are as follows: The system and method for continuous synthesis of lithium hexafluorophosphate of this invention, by setting up two-stage reaction vessels and reaction towers on the reaction vessels, increases the contact time and contact area between phosphorus pentafluoride and lithium fluoride hydrofluoric acid solution, thereby increasing the conversion efficiency of the product. Simultaneously, it achieves a continuous synthesis reaction. Furthermore, the use of an absorption tower ensures the utilization rate of phosphorus pentafluoride, and the use of a synthesis vessel ensures the utilization rate of lithium fluoride while improving product quality. This invention improves production efficiency and product quality, fully utilizes raw materials, and reduces costs. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the system for the continuous synthesis of lithium hexafluorophosphate according to the present invention.
[0019] In the diagram, 1. Synthesis vessel, 2. Gas feed pipe, 3. Discharge pipeline, 4. Pre-stage reaction tower, 5. Post-stage reaction vessel, 6. Post-stage reaction tower, 7. Absorption tower, 8. Liquid inlet pipeline, 9. Pre-stage reaction vessel, 10. Pre-stage gas inlet pipe, 11. Pre-stage gas delivery pipeline, 12. Synthesis liquid delivery pipeline, 13. Synthesis transfer pump, 14. Post-stage gas inlet pipe, 15. Post-stage gas delivery pipeline, 16. Pre-stage liquid delivery pipeline, 17. Pre-stage transfer pump, 18. Absorption gas delivery pipeline, 19. Post-stage liquid delivery pipeline, 20. Post-stage transfer pump, 21. Condensation gas delivery pipeline, 22. Condenser, 23. Condensation gravity flow pipeline, 24. U-shaped liquid seal pipe, 25. Exhaust pipeline, 26. Liquid level gauge, 27. Flow meter, 28. Gas inlet pipeline. Detailed Implementation
[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0021] This invention provides a system for the continuous synthesis of lithium hexafluorophosphate, such as... Figure 1 As shown, the reactor includes a synthesis vessel 1, which has a gas feed pipe 2 extending inward to its bottom. The top of the gas feed pipe 2 is connected to an inlet pipe 28. A discharge pipe 3 connects outward from the bottom of the synthesis vessel 1. The top of the synthesis vessel 1 is connected sequentially to a pre-stage reactor 9 and a post-stage reactor 5 via pipes. A packed pre-stage reaction tower 4 is connected above the top of the pre-stage reactor 9, and a packed post-stage reaction tower 6 is connected above the top of the post-stage reactor 5. The top of the pre-stage reaction tower 4 is connected to the post-stage reactor 5 via a pipe, and the top of the post-stage reaction tower 6 is connected to a packed absorber tower 7 via a pipe. Level gauges 26 are installed in the synthesis vessel 1, pre-stage reactor 9, post-stage reactor 5, and absorber tower 7. An inlet pipe 8 connects to the top of the absorber tower 7, and a flow meter 27 is installed on the inlet pipe 8. The top of the absorption tower 7 is connected to a condenser 22 via a condensation gas supply pipe 21. The bottom of the condenser 22 is connected to one side of the absorption tower 7 via a condensation gravity flow pipe 23. A U-shaped liquid seal pipe 24 connects the condenser 22 and the condensation gravity flow pipe 23. An exhaust pipe 25 is connected to the condenser 22.
[0022] The pre-stage reactor 9 is equipped with a pre-stage air inlet pipe 10 that extends into its bottom. The pre-stage air inlet pipe 10 is connected to the top of the synthesis reactor 1 via a pre-stage air delivery pipe 11. The bottom of the pre-stage reactor 9 is connected to the top of the synthesis reactor 1 via a synthesis liquid delivery pipe 12. A synthesis delivery pump 13 is connected to the synthesis liquid delivery pipe 12.
[0023] The downstream reactor 5 is equipped with a downstream air inlet pipe 14 that extends into its bottom. The downstream air inlet pipe 14 is connected to the top of the upstream reaction tower 4 through the downstream air delivery pipe 15. The bottom of the downstream reactor 5 is connected to the top of the upstream reaction tower 4 through the upstream liquid delivery pipe 16. The upstream liquid delivery pipe 16 is connected to the upstream delivery pump 17.
[0024] The bottom of the absorption tower 7 is connected to the top of the subsequent reaction tower 6 through the absorption gas supply pipe 18, and the bottom of the absorption tower 7 is connected to the top of the subsequent reaction tower 6 through the subsequent liquid supply pipe 19. The subsequent liquid supply pipe 19 is connected to the subsequent delivery pump 20.
[0025] This invention also provides a method for the continuous synthesis of lithium hexafluorophosphate. PF5 gas from inlet pipe 28 is fed into synthesis vessel 1 via gas feed pipe 2, and LiF·HF solution is fed into absorption tower 7 via liquid feed pipe 8. The PF5 gas introduced through gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in synthesis vessel 1 and reacts with incompletely reacted LiF. Excess PF5 gas sequentially enters the pre-stage reactor 9, pre-stage reaction tower 4, post-stage reactor 5, and post-stage reaction tower 6 to react with unreacted LiF in the mixed solution. The remaining PF5 gas enters absorption tower 7 and is absorbed by the LiF·HF solution fed through liquid feed pipe 8. The resulting mixed solution of LiPF6, LiF, and HF after PF5 gas absorption is sequentially fed into post-stage reaction tower 6, post-stage reactor 5, pre-stage reaction tower 4, pre-stage reactor 9, and synthesis vessel 1 to synthesize LiPF6 through a LiF-PF5 gas reaction. The resulting pure LiPF6 and HF solution are periodically discharged to the crystallization process via outlet pipe 3.
[0026] Through the above-described manner, the system and method for continuous synthesis of lithium hexafluorophosphate of the present invention, by setting up two-stage reaction vessels and reaction towers on the reaction vessels, increases the contact time and contact area between phosphorus pentafluoride and lithium fluoride hydrofluoric acid solution, thereby increasing the conversion efficiency of the product and achieving continuous synthesis reaction. Furthermore, the absorption tower 7 ensures the utilization rate of phosphorus pentafluoride, and the synthesis vessel 1 ensures the utilization rate of lithium fluoride while improving product quality. Additionally, the condenser 22 improves the utilization rate of the solvent hydrofluoric acid. The present invention improves production efficiency and product quality, fully utilizes raw materials, and reduces costs.
[0027] Example 1 During the continuous synthesis of lithium hexafluorophosphate, PF5 gas from the inlet pipeline 28 is fed into the synthesis reactor 1 through the gas feed pipe 2, and LiF·HF solution is fed into the absorption tower 7 through the liquid inlet pipeline 8. The flow rate of LiF·HF solution is controlled by the flow meter 27 to maintain the liquid level at the bottom of the absorption tower 7. The PF5 gas introduced through the gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor 1 and reacts with the incompletely reacted LiF to obtain pure LiPF6 dissolved in HF solvent. The liquid level is monitored by the liquid level gauge 26 on the synthesis reactor 1 and discharged periodically to the crystallization process through the discharge pipeline 3.
[0028] Excess PF5 gas and volatile HF gas in synthesis vessel 1 enter the pre-stage reactor 9 sequentially through the pre-stage gas supply pipe 11 and the pre-stage gas inlet pipe 10. The PF5 gas reacts with LiF in the mixed solution of LiPF6, LiF, and HF in the pre-stage reactor 9. The generated LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into synthesis vessel 1 through synthesis liquid delivery pipe 12 and synthesis transfer pump 13. The liquid level is monitored by the liquid level gauge 26 on the pre-stage reactor 9, completing the material transfer. Unreacted PF5 gas and volatile HF gas in the pre-stage reactor 9 enter the packing of the pre-stage reaction tower 4 and undergo gas-liquid mass transfer reaction with LiF in the mixed solution of LiPF6, LiF, and HF coming down from the top of the tower. The generated LiPF6 dissolves in the HF solvent and falls into the pre-stage reactor 9 with the mixed solution. The top of the pre-stage reaction tower 4 yields approximately 10% of the remaining PF5 gas and volatile HF gas.
[0029] The remaining approximately 10% of PF5 gas and volatile HF gas at the top of the pre-stage reaction tower 4 enters the post-stage reaction vessel 5 sequentially through the post-stage gas supply pipe 15 and the post-stage gas inlet pipe 14. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in the post-stage reaction vessel 5. The resulting LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into the top of the pre-stage reaction tower 4 through the pre-stage liquid supply pipe 16 and the pre-stage transfer pump 17. The liquid level is monitored by the liquid level gauge 26 on the post-stage reaction vessel 5, completing the transfer. The unreacted PF5 gas and volatile HF gas in the post-stage reaction vessel 5 enter the packing of the post-stage reaction tower 6, where they undergo a gas-liquid mass transfer reaction with the LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into the post-stage reaction vessel 5 along with the mixed solution. Approximately 0.5% of PF5 gas and volatile HF gas remain at the top of the post-stage reaction tower 6.
[0030] The remaining approximately 0.5% PF5 gas and volatile HF gas obtained from the top of the downstream reaction tower 6 enter the absorption tower 7 through the absorption gas supply pipe 18. The PF5 gas undergoes gas-liquid mass transfer with the fresh LiF·HF solution coming down from the top of the absorption tower 7, and the generated LiPF6 dissolves in the HF solvent. The resulting LiPF6, LiF, and HF mixed solution is continuously discharged into the top of the downstream reaction tower 6 through the downstream liquid supply pipe 19 and the downstream transfer pump 20. The liquid level is monitored by the liquid level gauge 26 on the absorption tower 7, completing the material transfer. After absorption, the remaining PF5 gas drops to below 100 PPM, and the volatile HF gas enters the condenser 22 through the condenser gas supply pipe 21. The HF solvent obtained after condensation in the condenser 22 enters the absorption tower 7 through the U-shaped liquid seal pipe 24 and the condenser gravity flow pipe 23. The impurities and non-condensable gases, such as hydrogen chloride gas, carried in the PF5 gas introduced by the inlet pipe 28 are finally discharged through the exhaust pipe 25 after passing through the condenser 22.
[0031] Example 2 During the continuous synthesis of lithium hexafluorophosphate, PF5 gas from the inlet pipeline 28 is fed into the synthesis reactor 1 through the gas feed pipe 2, and LiF·HF solution is fed into the absorption tower 7 through the liquid inlet pipeline 8. The flow rate of LiF·HF solution is controlled by the flow meter 27 to maintain the liquid level at the bottom of the absorption tower 7. The PF5 gas introduced through the gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor 1 and reacts with the incompletely reacted LiF to obtain pure LiPF6 dissolved in HF solvent. The liquid level is monitored by the liquid level gauge 26 on the synthesis reactor 1 and discharged periodically to the crystallization process through the discharge pipeline 3.
[0032] Excess PF5 gas and volatile HF gas in synthesis vessel 1 enter the pre-stage reactor 9 sequentially through the pre-stage gas supply pipe 11 and the pre-stage gas inlet pipe 10. The PF5 gas reacts with LiF in the mixed solution of LiPF6, LiF, and HF in the pre-stage reactor 9. The generated LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into synthesis vessel 1 through synthesis liquid delivery pipe 12 and synthesis transfer pump 13. The liquid level is monitored by the liquid level gauge 26 on the pre-stage reactor 9, completing the material transfer. Unreacted PF5 gas and volatile HF gas in the pre-stage reactor 9 enter the packing of the pre-stage reaction tower 4 and undergo gas-liquid mass transfer reaction with LiF in the mixed solution of LiPF6, LiF, and HF coming down from the top of the tower. The generated LiPF6 dissolves in the HF solvent and falls into the pre-stage reactor 9 with the mixed solution. The top of the pre-stage reaction tower 4 contains approximately 9.5% remaining PF5 gas and volatile HF gas.
[0033] The remaining approximately 9.5% PF5 gas and volatile HF gas at the top of the pre-stage reaction tower 4 sequentially enter the post-stage reaction vessel 5 through the post-stage gas supply pipe 15 and the post-stage gas inlet pipe 14. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in the post-stage reaction vessel 5. The resulting LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into the top of the pre-stage reaction tower 4 through the pre-stage liquid supply pipe 16 and the pre-stage transfer pump 17. The liquid level is monitored by the liquid level gauge 26 on the post-stage reaction vessel 5, completing the transfer. The unreacted PF5 gas and volatile HF gas in the post-stage reaction vessel 5 enter the packing of the post-stage reaction tower 6, where they undergo a gas-liquid mass transfer reaction with the LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into the post-stage reaction vessel 5 along with the mixed solution. The top of the post-stage reaction tower 6 is then filled with approximately 0.45% PF5 gas and volatile HF gas.
[0034] The remaining approximately 0.45% PF5 gas and volatile HF gas obtained from the top of the downstream reaction tower 6 enter the absorption tower 7 through the absorption gas supply pipe 18. The PF5 gas undergoes gas-liquid mass transfer with the fresh LiF·HF solution coming down from the top of the absorption tower 7, and the generated LiPF6 dissolves in the HF solvent. The resulting mixed solution of LiPF6, LiF, and HF is continuously discharged into the top of the downstream reaction tower 6 through the downstream liquid supply pipe 19 and the downstream transfer pump 20. The liquid level is monitored by the liquid level gauge 26 on the absorption tower 7, completing the material transfer. After absorption, the remaining PF5 gas drops to below 100 PPM, and the volatile HF gas enters the condenser 22 through the condenser gas supply pipe 21. The HF solvent obtained after condensation in the condenser 22 enters the absorption tower 7 through the U-shaped liquid seal pipe 24 and the condenser gravity flow pipe 23. The impurities and non-condensable gases, such as hydrogen chloride gas, carried in the PF5 gas introduced by the inlet pipe 28 are finally discharged through the exhaust pipe 25 after passing through the condenser 22.
[0035] Example 3 During the continuous synthesis of lithium hexafluorophosphate, PF5 gas from the inlet pipeline 28 is fed into the synthesis reactor 1 through the gas feed pipe 2, and LiF·HF solution is fed into the absorption tower 7 through the liquid inlet pipeline 8. The flow rate of LiF·HF solution is controlled by the flow meter 27 to maintain the liquid level at the bottom of the absorption tower 7. The PF5 gas introduced through the gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor 1 and reacts with the incompletely reacted LiF to obtain pure LiPF6 dissolved in HF solvent. The liquid level is monitored by the liquid level gauge 26 on the synthesis reactor 1 and discharged periodically to the crystallization process through the discharge pipeline 3.
[0036] Excess PF5 gas and volatile HF gas in synthesis reactor 1 enter pre-reactor 9 sequentially through pre-gas supply pipe 11 and pre-gas inlet pipe 10. The PF5 gas reacts with LiF in the mixed solution of LiPF6, LiF, and HF in pre-reactor 9. The resulting LiPF6 dissolves in the HF solvent. The resulting mixed solution is continuously discharged into synthesis reactor 1 through synthesis liquid supply pipe 12 and synthesis transfer pump 13. The liquid level is monitored by level gauge 26 on pre-reactor 9, completing the material transfer. Unreacted PF5 gas and volatile HF gas in pre-reactor 9 enter the packing of pre-reaction tower 4 and undergo gas-liquid mass transfer reaction with LiF in the mixed solution of LiPF6, LiF, and HF coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into pre-reactor 9 along with the mixed solution. Approximately 10.5% of PF5 gas and volatile HF gas remain at the top of pre-reaction tower 4.
[0037] The remaining approximately 10.5% PF5 gas and volatile HF gas at the top of the pre-stage reaction tower 4 sequentially enter the post-stage reaction vessel 5 through the post-stage gas supply pipe 15 and the post-stage gas inlet pipe 14. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in the post-stage reaction vessel 5. The resulting LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into the top of the pre-stage reaction tower 4 through the pre-stage liquid supply pipe 16 and the pre-stage transfer pump 17. The liquid level is monitored by the liquid level gauge 26 on the post-stage reaction vessel 5, completing the transfer. The unreacted PF5 gas and volatile HF gas in the post-stage reaction vessel 5 enter the packing of the post-stage reaction tower 6, where they undergo a gas-liquid mass transfer reaction with the LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into the post-stage reaction vessel 5 along with the mixed solution. The top of the post-stage reaction tower 6 is then filled with approximately 0.55% PF5 gas and volatile HF gas.
[0038] The remaining approximately 0.55% PF5 gas and volatile HF gas obtained from the top of the downstream reaction tower 6 enter the absorption tower 7 through the absorption gas supply pipe 18. The PF5 gas undergoes gas-liquid mass transfer with the fresh LiF·HF solution coming down from the top of the absorption tower 7, and the generated LiPF6 dissolves in the HF solvent. The resulting LiPF6, LiF, and HF mixed solution is continuously discharged into the top of the downstream reaction tower 6 through the downstream liquid supply pipe 19 and the downstream transfer pump 20. The liquid level is monitored by the liquid level gauge 26 on the absorption tower 7, completing the material transfer. After absorption, the remaining PF5 gas drops to below 100 PPM, and the volatile HF gas enters the condenser 22 through the condenser gas supply pipe 21. The HF solvent obtained after condensation in the condenser 22 enters the absorption tower 7 through the U-shaped liquid seal pipe 24 and the condenser gravity flow pipe 23. The impurities and non-condensable gases, such as hydrogen chloride gas, carried in the PF5 gas introduced by the inlet pipe 28 are finally discharged through the exhaust pipe 25 after passing through the condenser 22.
[0039] Example 4 During the continuous synthesis of lithium hexafluorophosphate, PF5 gas from the inlet pipeline 28 is fed into the synthesis reactor 1 through the gas feed pipe 2, and LiF·HF solution is fed into the absorption tower 7 through the liquid inlet pipeline 8. The flow rate of LiF·HF solution is controlled by the flow meter 27 to maintain the liquid level at the bottom of the absorption tower 7. The PF5 gas introduced through the gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor 1 and reacts with the incompletely reacted LiF to obtain pure LiPF6 dissolved in HF solvent. The liquid level is monitored by the liquid level gauge 26 on the synthesis reactor 1 and discharged periodically to the crystallization process through the discharge pipeline 3.
[0040] Excess PF5 gas and volatile HF gas in synthesis reactor 1 enter pre-reactor 9 sequentially through pre-gas supply pipe 11 and pre-gas inlet pipe 10. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in pre-reactor 9. The generated LiPF6 dissolves in the HF solvent. The resulting mixed solution is continuously discharged into synthesis reactor 1 through synthesis liquid supply pipe 12 and synthesis transfer pump 13. The liquid level is monitored by level gauge 26 on pre-reactor 9, completing the material transfer. Unreacted PF5 gas and volatile HF gas in pre-reactor 9 enter the packing of pre-reaction tower 4 and undergo gas-liquid mass transfer reaction with LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The generated LiPF6 dissolves in the HF solvent and falls into pre-reactor 9 along with the mixed solution. Approximately 9% of PF5 gas and volatile HF gas remain at the top of pre-reaction tower 4.
[0041] Approximately 9% of the remaining PF5 gas and volatile HF gas at the top of the pre-stage reaction tower 4 sequentially enter the post-stage reaction vessel 5 through the post-stage gas supply pipe 15 and the post-stage gas inlet pipe 14. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in the post-stage reaction vessel 5. The resulting LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into the top of the pre-stage reaction tower 4 through the pre-stage liquid supply pipe 16 and the pre-stage transfer pump 17. The liquid level is monitored by the liquid level gauge 26 on the post-stage reaction vessel 5, completing the transfer. The unreacted PF5 gas and volatile HF gas in the post-stage reaction vessel 5 enter the packing of the post-stage reaction tower 6, where they undergo a gas-liquid mass transfer reaction with the LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into the post-stage reaction vessel 5 along with the mixed solution. Approximately 0.4% of the remaining PF5 gas and volatile HF gas are obtained at the top of the post-stage reaction tower 6.
[0042] The remaining approximately 0.4% PF5 gas and volatile HF gas obtained from the top of the downstream reaction tower 6 enter the absorption tower 7 through the absorption gas supply pipe 18. The PF5 gas undergoes gas-liquid mass transfer with the fresh LiF·HF solution coming down from the top of the absorption tower 7, and the generated LiPF6 dissolves in the HF solvent. The resulting mixed solution of LiPF6, LiF, and HF is continuously discharged into the top of the downstream reaction tower 6 through the downstream liquid supply pipe 19 and the downstream transfer pump 20. The liquid level is monitored by the liquid level gauge 26 on the absorption tower 7, completing the material transfer. After absorption, the remaining PF5 gas drops to below 100 PPM, and the volatile HF gas enters the condenser 22 through the condenser gas supply pipe 21. The HF solvent obtained after condensation in the condenser 22 enters the absorption tower 7 through the U-shaped liquid seal pipe 24 and the condenser gravity flow pipe 23. The impurities and non-condensable gases, such as hydrogen chloride gas, carried in the PF5 gas introduced by the inlet pipe 28 are finally discharged through the exhaust pipe 25 after passing through the condenser 22.
[0043] Example 5 During the continuous synthesis of lithium hexafluorophosphate, PF5 gas from the inlet pipeline 28 is fed into the synthesis reactor 1 through the gas feed pipe 2, and LiF·HF solution is fed into the absorption tower 7 through the liquid inlet pipeline 8. The flow rate of LiF·HF solution is controlled by the flow meter 27 to maintain the liquid level at the bottom of the absorption tower 7. The PF5 gas introduced through the gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor 1 and reacts with the incompletely reacted LiF to obtain pure LiPF6 dissolved in HF solvent. The liquid level is monitored by the liquid level gauge 26 on the synthesis reactor 1 and discharged periodically to the crystallization process through the discharge pipeline 3.
[0044] Excess PF5 gas and volatile HF gas in synthesis vessel 1 enter the pre-stage reactor 9 sequentially through the pre-stage gas supply pipe 11 and the pre-stage gas inlet pipe 10. The PF5 gas reacts with LiF in the mixed solution of LiPF6, LiF, and HF in the pre-stage reactor 9. The generated LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into synthesis vessel 1 through synthesis liquid delivery pipe 12 and synthesis transfer pump 13. The liquid level is monitored by the liquid level gauge 26 on the pre-stage reactor 9, completing the material transfer. Unreacted PF5 gas and volatile HF gas in the pre-stage reactor 9 enter the packing of the pre-stage reaction tower 4 and undergo gas-liquid mass transfer reaction with LiF in the mixed solution of LiPF6, LiF, and HF coming down from the top of the tower. The generated LiPF6 dissolves in the HF solvent and falls into the pre-stage reactor 9 with the mixed solution. The top of the pre-stage reaction tower 4 yields approximately 11% of the remaining PF5 gas and volatile HF gas.
[0045] The remaining approximately 11% of PF5 gas and volatile HF gas at the top of the pre-stage reaction tower 4 sequentially enter the post-stage reaction vessel 5 through the post-stage gas supply pipe 15 and the post-stage gas inlet pipe 14. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in the post-stage reaction vessel 5. The resulting LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into the top of the pre-stage reaction tower 4 through the pre-stage liquid supply pipe 16 and the pre-stage transfer pump 17. The liquid level is monitored by the liquid level gauge 26 on the post-stage reaction vessel 5, completing the transfer. The unreacted PF5 gas and volatile HF gas in the post-stage reaction vessel 5 enter the packing of the post-stage reaction tower 6, where they undergo a gas-liquid mass transfer reaction with the LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into the post-stage reaction vessel 5 along with the mixed solution. Approximately 0.6% of PF5 gas and volatile HF gas remain at the top of the post-stage reaction tower 6.
[0046] The remaining approximately 0.6% PF5 gas and volatile HF gas obtained from the top of the downstream reaction tower 6 enter the absorption tower 7 through the absorption gas supply pipe 18. The PF5 gas undergoes gas-liquid mass transfer with the fresh LiF·HF solution coming down from the top of the absorption tower 7, and the generated LiPF6 dissolves in the HF solvent. The resulting LiPF6, LiF, and HF mixed solution is continuously discharged into the top of the downstream reaction tower 6 through the downstream liquid supply pipe 19 and the downstream transfer pump 20. The liquid level is monitored by the liquid level gauge 26 on the absorption tower 7, completing the material transfer. After absorption, the remaining PF5 gas drops to below 100 PPM, and the volatile HF gas enters the condenser 22 through the condenser gas supply pipe 21. The HF solvent obtained after condensation in the condenser 22 enters the absorption tower 7 through the U-shaped liquid seal pipe 24 and the condenser gravity flow pipe 23. The impurities and non-condensable gases, such as hydrogen chloride gas, carried in the PF5 gas introduced by the inlet pipe 28 are finally discharged through the exhaust pipe 25 after passing through the condenser 22.
[0047] Example 6 During the continuous synthesis of lithium hexafluorophosphate, PF5 gas from the inlet pipeline 28 is fed into the synthesis reactor 1 through the gas feed pipe 2, and LiF·HF solution is fed into the absorption tower 7 through the liquid inlet pipeline 8. The flow rate of LiF·HF solution is controlled by the flow meter 27 to maintain the liquid level at the bottom of the absorption tower 7. The PF5 gas introduced through the gas feed pipe 2 enters the mixed solution of LiPF6, LiF, and HF in the synthesis reactor 1 and reacts with the incompletely reacted LiF to obtain pure LiPF6 dissolved in HF solvent. The liquid level is monitored by the liquid level gauge 26 on the synthesis reactor 1 and discharged periodically to the crystallization process through the discharge pipeline 3.
[0048] Excess PF5 gas and volatile HF gas in synthesis vessel 1 enter the pre-stage reactor 9 sequentially through the pre-stage gas supply pipe 11 and the pre-stage gas inlet pipe 10. The PF5 gas reacts with LiF in the mixed solution of LiPF6, LiF, and HF in the pre-stage reactor 9. The generated LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into synthesis vessel 1 through synthesis liquid delivery pipe 12 and synthesis transfer pump 13. The liquid level is monitored by the liquid level gauge 26 on the pre-stage reactor 9, completing the material transfer. Unreacted PF5 gas and volatile HF gas in the pre-stage reactor 9 enter the packing of the pre-stage reaction tower 4 and undergo gas-liquid mass transfer reaction with LiF in the mixed solution of LiPF6, LiF, and HF coming down from the top of the tower. The generated LiPF6 dissolves in the HF solvent and falls into the pre-stage reactor 9 with the mixed solution. The top of the pre-stage reaction tower 4 yields approximately 8% of the remaining PF5 gas and volatile HF gas.
[0049] The remaining approximately 8% of PF5 gas and volatile HF gas at the top of the pre-stage reaction tower 4 sequentially enter the post-stage reaction vessel 5 through the post-stage gas supply pipe 15 and the post-stage gas inlet pipe 14. The PF5 gas reacts with LiF in the LiPF6, LiF, and HF mixed solution in the post-stage reaction vessel 5. The resulting LiPF6 dissolves in the HF solvent, and the resulting mixed solution is continuously discharged into the top of the pre-stage reaction tower 4 through the pre-stage liquid supply pipe 16 and the pre-stage transfer pump 17. The liquid level is monitored by the liquid level gauge 26 on the post-stage reaction vessel 5, completing the transfer. The unreacted PF5 gas and volatile HF gas in the post-stage reaction vessel 5 enter the packing of the post-stage reaction tower 6, where they undergo a gas-liquid mass transfer reaction with the LiF in the LiPF6, LiF, and HF mixed solution coming down from the top of the tower. The resulting LiPF6 dissolves in the HF solvent and falls into the post-stage reaction vessel 5 along with the mixed solution. Approximately 0.3% of PF5 gas and volatile HF gas remain at the top of the post-stage reaction tower 6.
[0050] The remaining approximately 0.3% PF5 gas and volatile HF gas obtained from the top of the downstream reaction tower 6 enter the absorption tower 7 through the absorption gas supply pipe 18. The PF5 gas undergoes gas-liquid mass transfer with the fresh LiF·HF solution coming down from the top of the absorption tower 7, and the generated LiPF6 dissolves in the HF solvent. The resulting LiPF6, LiF, and HF mixed solution is continuously discharged into the top of the downstream reaction tower 6 through the downstream liquid supply pipe 19 and the downstream transfer pump 20. The liquid level is monitored by the liquid level gauge 26 on the absorption tower 7, completing the material transfer. After absorption, the remaining PF5 gas drops to below 100 PPM, and the volatile HF gas enters the condenser 22 through the condenser gas supply pipe 21. The HF solvent obtained after condensation in the condenser 22 enters the absorption tower 7 through the U-shaped liquid seal pipe 24 and the condenser gravity flow pipe 23. The impurities and non-condensable gases, such as hydrogen chloride gas, carried in the PF5 gas introduced by the inlet pipe 28 are finally discharged through the exhaust pipe 25 after passing through the condenser 22.
Claims
1. A system for continuously synthesizing lithium hexafluorophosphate, characterized in that: The invention comprises a synthesis kettle (1), wherein a gas feed pipe (2) is arranged on the synthesis kettle (1) and is led into the bottom thereof, the bottom of the synthesis kettle (1) is connected to a discharge pipeline (3) outwardly, the top of the synthesis kettle (1) is connected to a front and a rear reactor in sequence outwardly through a pipeline, the top of each reactor is connected to a reaction tower, the top of the front reactor (4) is connected to the rear reactor (5) through a pipeline, the top of the rear reactor (6) is connected to an absorption tower (7) through a pipeline, and the top of the absorption tower (7) is connected to a liquid inlet pipeline (8).
2. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The front-stage reactor (9) in the two-stage reactor is provided with a front-stage air inlet pipe (10) which is connected to the bottom of the reactor. The front-stage air inlet pipe (10) is connected to the top of the synthesis reactor (1) through a front-stage air supply pipe (11). The bottom of the front-stage reactor (9) is connected to the top of the synthesis reactor (1) through a synthesis liquid supply pipe (12). The synthesis liquid supply pipe (12) is connected to a synthesis delivery pump (13).
3. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The rear-stage reaction kettle (5) is provided with a rear-stage air inlet pipe (14) which leads inwardly into the bottom thereof; the rear-stage air inlet pipe (14) is connected to the top of the front-stage reaction tower (4) via a rear-stage air delivery pipe (15); the bottom of the rear-stage reaction kettle (5) is connected to the top of the front-stage reaction tower (4) via a front-stage liquid delivery pipe (16); and the front-stage liquid delivery pipe (16) is connected to a front-stage delivery pump (17).
4. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The bottom of the absorption tower (7) is connected to the top of the subsequent reaction tower (6) via an absorption air delivery pipeline (18), and the bottom of the absorption tower (7) is connected to the top of the subsequent reaction tower (6) via a subsequent liquid delivery pipeline (19), and the subsequent liquid delivery pipeline (19) is connected to a subsequent delivery pump (20).
5. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The top of the absorption tower (7) is connected to a condenser (22) via a condensation air supply pipeline (21); the bottom of the condenser (22) is connected to one side of the absorption tower (7) via a condensation gravity pipeline (23); a U-shaped liquid seal pipe (24) is connected between the condenser (22) and the condensation gravity pipeline (23); and an exhaust pipeline (25) is connected to the condenser (22).
6. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: Liquid level meters (26) are provided in the synthesis kettle (1), the front-stage reaction kettle (9), the rear-stage reaction kettle (5), and the absorption tower (7).
7. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The liquid inlet pipeline (8) is provided with a flow meter (27).
8. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The front-stage reaction tower (4), the rear-stage reaction tower (6), and the absorption tower (7) are all packed towers.
9. The system for continuously synthesizing lithium hexafluorophosphate according to claim 1, characterized in that: The top end of the gas feed pipe (2) is connected to a gas intake line (28).
10. A method for continuously synthesizing lithium hexafluorophosphate using the system for continuously synthesizing lithium hexafluorophosphate as claimed in claim 1, characterized in that: The PF5 gas from the gas inlet line (28) is fed into the synthesis reactor (1) through the gas feed pipe (2), and the LiF·HF solution is fed into the absorption tower (7) through the liquid inlet line (8). The PF5 gas introduced into the gas feed pipe (2) enters the mixed solution of LiPF6, LiF and HF in the synthesis reactor (1) to react with the unreacted LiF, and the excess PF5 gas enters the front-stage reaction reactor (9), the front-stage reaction tower (4), the rear-stage reaction reactor (5), and the rear-stage reaction tower (6) in sequence to react with the unreacted LiF in the mixed solution. The remaining PF5 gas enters the absorption tower (7) and is absorbed by the LiF·HF solution fed in through the liquid inlet pipeline (8). The mixed solution of LiPF6, LiF and HF obtained after the LiF·HF solution absorbs the PF5 gas is sequentially fed into the subsequent reaction tower (6), the subsequent reactor (5), the previous reaction tower (4), the previous reactor (9) and the synthesis reactor (1) to generate LiPF6 through the synthesis reaction of LiF and PF5 gas. The pure LiPF6 and HF solution is regularly discharged to the crystallization process through the discharge pipeline (3).