CN116078292A - Synthesis reactor of lithium hexafluorophosphate, continuous synthesis reaction system and process - Google Patents

Abstract

The invention discloses a synthesis reactor of lithium hexafluorophosphate, a continuous synthesis reaction system and a process, wherein the reactor comprises: the reactor comprises a reactor body, a raw material gas inlet and a synthetic liquid outlet which are arranged at the lower part of the reactor body, and a liquid inlet and a reaction gas outlet which are arranged at the upper part of the reactor body; the PF 5-containing raw gas enters the reactor body from the raw gas inlet, is dispersed by the gas distributor, then is contacted and reacted with LiF-containing reaction liquid which enters the reactor body from the liquid inlet and is dispersed by the liquid distributor, the generated LiPF 6-containing synthesis liquid is discharged from the synthesis liquid outlet, and unreacted gas is discharged from the reaction gas outlet; the gas distributor and the liquid distributor are arranged in the reactor body, and the arrangement height of the liquid distributor is higher than that of the gas distributor. The invention can continuously feed and continuously discharge, realizes the continuous synthesis of lithium hexafluorophosphate, and has the advantages of high reactant conversion rate, high reaction efficiency, stable operation, suitability for industrialization and the like.

Description

A synthesis reactor, continuous synthesis reaction system and process for lithium hexafluorophosphate

technical field

The invention relates to the preparation of lithium hexafluorophosphate, in particular to a synthesis reactor, continuous synthesis reaction system and continuous synthesis process of lithium hexafluorophosphate.

Background technique

Lithium hexafluorophosphate is an electrolyte with good comprehensive performance. It is the main component of the electrolyte of lithium-ion batteries. It can make lithium batteries have higher energy density and cycle capacity, lower self-discharge rate and long warranty period. The key material of performance index. However, lithium-ion batteries have high requirements on the purity of lithium hexafluorophosphate. The electrolyte made of lithium hexafluorophosphate containing impurities will increase the internal resistance of the lithium battery, and the battery capacity will decay too quickly, and the safety performance of the battery cannot be guaranteed. Therefore, the purity of lithium hexafluorophosphate determines the quality of lithium-ion batteries. However, lithium hexafluorophosphate has low thermal stability, high hygroscopicity and easy hydrolysis, which greatly increases the difficulty and uncertainty of obtaining high-purity lithium hexafluorophosphate. Therefore, the preparation of high-purity lithium hexafluorophosphate depends on the preparation process of lithium hexafluorophosphate and the control of the preparation process.

At present, the synthesis methods of lithium hexafluorophosphate mainly include gas-solid phase reaction method, organic solvent method, hydrofluoric acid solvent method, etc. Most domestic and foreign manufacturers of lithium hexafluorophosphate use the hydrofluoric acid solvent method. From a process point of view, the production of lithium hexafluorophosphate by the hydrofluoric acid solvent method mostly adopts a batch process. Compared with the continuous process, the batch process has the advantages of low raw material utilization rate, long single-batch production cycle, difficult judgment of the reaction end point, and large equipment investment. The phosphorus pentafluoride feed conduit is easy to block, and the safety risk of plugging is high.

Zhuhai Saiwei Electronics patent CN101712467A discloses a synthesis method of lithium hexafluorophosphate: add dry lithium chloride and potassium hexafluorophosphate to an organic solvent to dissolve, then add a catalyst to the solution, heat up while stirring and mixing, and control the reaction temperature to 30 ~80°C, the reaction time is 2-16 hours, after the reaction solution is cooled, the insoluble matter is filtered to obtain an organic solution containing lithium hexafluorophosphate. However, the organic solution of this method also contains impurities such as catalyst and by-product potassium chloride, the quality of the lithium hexafluorophosphate product is not high, the equipment efficiency is low, and the use of organic solvents increases safety risks and environmental pollution risks.

Jiangsu Xintai material patent CN112079367A discloses a high-efficiency synthesis process of lithium hexafluorophosphate: liquid hydrogen fluoride and solid phosphorus pentachloride are used to react to obtain a mixed gas including phosphorus pentafluoride, hydrogen fluoride and hydrogen chloride, and the mixed gas is added to the mixed gas through a pressurized condensation tank. After cooling under pressure, a separated liquid phase and a gas phase that can be recovered to prepare industrial hydrochloric acid are obtained, wherein the liquid phase includes liquid phase phosphorus pentafluoride and hydrogen fluoride, which are used to react with liquid phase lithium fluoride to prepare lithium hexafluorophosphate. However, the core of this patent lies in the recovery and utilization of hydrogen fluoride in the gas phase, and does not involve the synthesis process of lithium hexafluorophosphate.

Jiangsu Xintai Materials Patent CN105668537A discloses a method for improving reaction efficiency in the production process of lithium hexafluorophosphate, which includes the following steps: 1) vaporize liquid hydrogen fluoride, and convert the liquid hydrogen fluoride into a gaseous state by heating the liquid hydrogen fluoride through a hot water jacket; 2) liquefy gaseous hydrogen fluoride, The above-mentioned gaseous hydrogen fluoride gas is transported to a low-temperature condenser through a delivery pipeline for heat exchange and condensation, and the gaseous hydrogen fluoride is converted into a liquid state; 3) The above-mentioned liquid hydrogen fluoride is added dropwise at a uniform speed into a reaction tank equipped with phosphorus pentachloride for reaction. The method mainly discloses the condensation and purification technology after liquid-phase hydrogen fluoride is evaporated. Lithium hexafluorophosphate is still synthesized by adding liquid hydrogen fluoride dropwise into a reaction tank containing phosphorus pentachloride, which belongs to the intermittent production process of lithium hexafluorophosphate.

Hubei Maikekai patent CN110817831A discloses a continuous synthesis method of lithium hexafluorophosphate, including: introducing chlorine gas and phosphorus trichloride into the first microreactor to react to synthesize phosphorus pentachloride gas; anhydrous hydrogen fluoride and the first microreactor The phosphorus pentachloride gas synthesized in the second microreactor is introduced into the reaction to generate phosphorus pentafluoride gas; the lithium fluoride solution and the phosphorus pentafluoride gas generated in the second microreactor are introduced into the third microreactor for reaction A synthetic solution of lithium hexafluorophosphate was obtained. But in this method, chlorine, phosphorus trichloride synthesize solid phosphorus pentachloride in the first microreactor, easily cause the first microreactor to block, cause no intermediate product of phosphorus pentachloride to the second microreactor and hydrofluoric acid The reaction cannot continuously synthesize lithium hexafluorophosphate.

Jiangsu Jiujiujiu patent CN106185860A discloses a synthesis process of lithium hexafluorophosphate with a stable reaction system, including: the lithium fluoride anhydrous hydrogen fluoride solution in the preparation tank is transferred from the lithium fluoride anhydrous hydrogen fluoride solution intermediate pump to the constant temperature mixing cooling tank through the intermediate tank, It is pumped from the circulating absorption pump to the feed port of the reaction tower, atomized through the atomizing nozzle, and then undergoes sufficient heat transfer, mass transfer and synthesis reaction with the phosphorus pentafluoride gas from the phosphorus pentafluoride purification section, and a small amount of unreacted The phosphorus pentafluoride gas is further reacted and absorbed by the lithium fluoride anhydrous hydrogen fluoride solution in the tail gas balance absorber. After setting the value, it is quantitatively and continuously transported to the crystallization section through the synthetic liquid pump. However, the synthesis process involves a blending tank, intermediate tank, constant temperature cooling tank, reaction tower, tail gas system, etc. The system is complex, and the lithium hexafluorophosphate solution is not easy to form a concentration gradient, and it is difficult to continuously produce a stable lithium hexafluorophosphate solution.

Luoyang Senlan Chemical Patent CN101544361A discloses a continuous preparation process of lithium hexafluorophosphate, including: after mixing lithium fluoride solution and phosphorus pentafluoride or a mixed gas of phosphorus pentafluoride and other gases, a multi-stage tubular reaction is adopted Synthesis of lithium hexafluorophosphate. However, its tubular reactor is only connected by pipes or pipelines filled with fillers, without considering the uniform distribution of gas-liquid phase materials, there is bias flow between gas phase and liquid phase, poor mass transfer and heat transfer performance, low synthesis efficiency of equipment, and great difficulty in industrial application .

Zaozhuang Haidi New Energy patent CN103633324A discloses a lithium hexafluorophosphate synthesis device, which produces large specific surface droplets through a high-speed atomization nozzle, thereby increasing the reaction area and making the raw materials LiF and PF5 react quickly. However, the manufacture of the atomizing nozzle is difficult, and the highly toxic PF5 is easy to leak when rotating at high speed, which has a high safety risk and is not suitable for industrial applications.

The patent CN102838103A of Zhangjiagang Yayuan High-tech Materials Co., Ltd. discloses a synthetic device for lithium hexafluorophosphate, including: a reactor, the top of the reactor is provided with a jet inhaler with a gas suction port and a reflux liquid inlet, and the lower end of the jet inhaler is set There is a connecting pipe, the lower end of the connecting pipe is provided with a gas-liquid mixer, and a guide tube is set outside the connecting tube and the gas-liquid mixer. There is a gap between the top of the guide tube and the connecting tube, and a There is a "W" type deflector, and a spiral deflector that spirally rises from the lower part of the guide cylinder to the upper end of the guide cylinder is arranged on the outer circumferential surface of the guide cylinder; the lower end of the reaction kettle is provided with a reflux liquid outlet, The reflux liquid outlet is connected to the reflux liquid inlet through a circulation pipeline, and a reflux valve and a circulation pump are arranged on the circulation pipeline. However, the synthesis device is a batch synthesis process, and the equipment manufacturing is difficult, and the industrial application is not high.

To sum up, the synthesis of lithium hexafluorophosphate in the prior art is mostly a batch process, with multiple production links, complex processes, low production efficiency, high equipment requirements, high operating costs, and difficult industrialization. Therefore, it is of great industrial value to study an efficient and stable gas-liquid phase continuous synthesis process for lithium hexafluorophosphate.

Contents of the invention

In order to solve the above technical problems, the present invention proposes a lithium hexafluorophosphate synthesis reactor, a continuous synthesis reaction system and a continuous synthesis process that are efficient, stable and suitable for industrial application.

The purpose of the present invention is achieved by the following technical solutions:

A synthesis reactor for lithium hexafluorophosphate, the reactor comprising: a reactor body, a raw material gas inlet and a synthetic liquid outlet arranged at the lower part of the reactor body, a liquid inlet and a reaction gas outlet arranged at the upper part of the reactor body;

The raw material gas containing PF5 enters the reactor body from the raw gas inlet, and is dispersed through a gas distributor, and then contacts and reacts with the LiF-containing reaction liquid that enters the reactor body from the liquid inlet and is dispersed through the liquid distributor. LiPF6 synthesis liquid is discharged from the outlet of the synthesis liquid, and unreacted gas is discharged from the outlet of the reaction gas; the gas distributor and the liquid distributor are arranged in the reactor body, and the height of the liquid distributor is higher than that of the gas distribution the setting height of the controller.

Preferably, the gas distributor is located at the lower part of the reactor, and the liquid distributor is located at the upper part of the reactor.

After the PF5-containing raw material gas is dispersed by the gas distributor, it can be evenly distributed in the reaction liquid with a smaller bubble diameter, so that the gas-liquid phase mass transfer effect is better; after the LiF-containing reaction liquid passes through the liquid phase distributor, the concentration distribution is more uniform .

Reactor of the present invention also includes:

A series of tubes, the series of tubes are arranged in the reactor body, one end is connected to the outlet of the gas distributor, and the other end is connected to the outlet of the liquid distributor;

The first sealing plate, the setting height of the first sealing plate is lower than the outlet end of the tubes connected to the outlet of the liquid distributor;

The second sealing plate, the setting height of the second sealing plate is higher than the outlet end of the tubes connected to the outlet of the gas distributor;

The tubes are fixed by the first sealing plate and the second sealing plate.

The outer space of the tubes enclosed by the first sealing plate, the second sealing plate and the reactor body can be filled with refrigerant to exchange heat for the reaction materials in the tubes and adjust the reaction temperature.

Further, the reactor is placed upright, so that the raw material gas containing PF5 and the reaction solution containing LiF have sufficient contact time, so that the reaction can be carried out as completely as possible.

The type of the reactor is not specifically limited, as long as the gas-liquid phase can be sufficiently reacted. Preferably, the reactor is selected from a vertical reactor, a reaction tower or a tubular reactor.

The reactor of the present invention also includes a demister, the demister is connected to the reaction gas outlet, and is used to remove the mist droplets entrained in the unreacted gas, and the liquid outlet of the demister is connected to the reactor . The demister is installed with demister packing, such as wire mesh demister, plastic demister, etc.

The reactor also includes a jacket arranged outside the reactor body, which is used for heat conduction during the reaction process and to adjust the reaction temperature.

The present invention also provides a continuous synthesis reaction system of lithium hexafluorophosphate, the continuous synthesis reaction system includes at least two reactors described above that are connected in sequence, and the raw material gas containing PF5 enters from the raw material gas inlet of the first-stage reactor Entering the reaction system, the LiF-containing reaction liquid enters the reaction system from the liquid inlet of the last-stage reactor, the reaction gas outlet of the previous-stage reactor is connected to the raw material gas inlet of the latter-stage reactor, and the synthetic liquid outlet of the latter-stage reactor Connect the liquid inlet of the previous stage reactor, and the generated synthetic liquid containing LiPF6 is discharged from the reaction system from the synthetic liquid outlet of the first stage reactor.

Preferably, the continuous synthesis reaction system includes three to five stages of any one of the above-mentioned reactors connected in sequence.

In the continuous synthesis reaction system, the feed gas containing PF5 flows from the first-stage reactor to the last-stage reactor step by step under the action of pressure difference; The reactor flows to the first-stage reactor step by step; the gas-phase material and the liquid-phase material flow in reverse, and in each stage of the reactor, the gas-phase material and the liquid-phase material contact and react in reverse to improve the gas-liquid mass transfer effect.

Further, a demister is arranged between the reaction gas outlet of the former reactor and the raw material gas inlet of the latter reactor, and the liquid outlet of the demister communicates with the former reactor. That is to say, after each reactor is defoamed by the demister, the unreacted gas continues to enter the next reactor, and the liquid returns to the current reactor.

Further, the reaction gas outlet of the last stage reactor is connected to the tail gas recovery system for HF and/or HCl recovery. If the tail gas contains hydrogen chloride gas, it can be made into industrial hydrochloric acid after separation; if the tail gas entrains hydrogen fluoride in the reaction liquid phase, the separated hydrogen fluoride can be reused for the preparation of lithium hexafluorophosphate.

Further, the feed gas inlet of the first-stage reactor of the present invention can be directly connected to a phosphorus pentafluoride storage tank or buffer tank, or connected to a PF5 generator, and the PF5 generator outputs a feed gas containing PF5.

The liquid inlet of the last stage reactor is connected with LiF storage tank.

Further, the synthesis liquid outlet of the first-stage reactor is connected to a crystallization system, and the crystallization system includes a synthesis liquid storage tank, a crystallizer, a dryer, and a mother liquor tank connected to the crystallizer in sequence.

The present invention also provides a continuous synthesis process for lithium hexafluorophosphate, the continuous synthesis process comprising:

Provide the continuous synthesis reaction system described in any one of the above;

Filling the outer space of the tubes formed by the jacket and/or the first sealing plate, the second sealing plate, and the reactor body;

To the feed gas inlet of the first-stage reactor of the continuous synthesis reaction system, feed the feed gas containing PF5, and feed the LiF-containing reaction solution to the liquid inlet of the last-stage reactor;

PF5 and LiF undergo a gas-liquid contact reaction in each reactor, LiF reacts completely in the first reactor, PF5 completely reacts in the last reactor, and unreacted PF5 in the previous reactor passes through its reaction gas The raw material gas inlet of the outlet and the latter stage reactor enters the latter stage reactor step by step to continue to participate in the reaction. The unreacted LiF reaction liquid in the latter stage reactor and the generated LiPF6 synthesis liquid pass through its synthesis liquid outlet, the former one The liquid inlet of the first-stage reactor enters the previous one-stage reactor step by step to continue to participate in the reaction;

The generated LiPF6 synthetic liquid is discharged from the synthetic liquid outlet of the first-stage reactor.

The reaction temperature of the reactors at all levels is -20-40°C, and the reaction pressure is 0.1-1.0MPa. The reaction temperature is controlled by the refrigerant in the jacket of the outer wall of each stage of reactor and/or the refrigerant in the sealed space outside the tubes, preferably the reaction temperature is -5-20°C.

The reaction pressure is preferably 0.1-0.5 MPa, and the reaction pressure of the former reactor is higher than that of the latter reactor, and the raw material gas containing PF5 enters the next reactor by pressure difference. As preferably, the reaction pressure of the first stage reactor is higher than the reaction pressure of the latter stage reactor by at least 0.05MPa, so as to ensure that the feed gas containing PF5 enters the next stage reactor smoothly.

The raw material gas containing PF5 is phosphorus pentafluoride gas, or a mixed gas of phosphorus pentafluoride and hydrogen chloride. It can be prepared by reacting solid phosphorus pentachloride with hydrogen fluoride, phosphorus trichloride and liquid chlorine, or polyphosphoric acid and hydrogen fluoride.

The LiF-containing reaction solution is a LiF solution in HF, or LiF is dissolved in a mother liquor after crystallization and filtration of lithium hexafluorophosphate, or LiF is dissolved in an organic solvent. Described organic solvent is such as EMC, DMC. However, considering the post-treatment of organic solvents, the present invention prefers the HF solution of LiF, or the mother liquor in which LiF is dissolved in lithium hexafluorophosphate crystals and filtered.

In the continuous synthesis process of lithium hexafluorophosphate according to the present invention, the phosphorus pentafluoride gas and LiF in the first-stage reactor are counted by the phosphorus pentafluoride gas in the feed gas containing PF5 and the LiF in the LiF reaction solution respectively. The ratio is 3-6:1, and the molar ratio of phosphorus pentafluoride gas and LiF in the last reactor is 1:3-6. Preferably, the molar ratio of phosphorus pentafluoride gas to LiF in the first-stage reactor is 3-5:1, and the molar ratio of phosphorus pentafluoride gas to LiF in the last-stage reactor is 1:3-4.

Since the present invention is a continuous reaction, the phosphorus pentafluoride gas and LiF are fed continuously, and the amount ratio thereof can be converted into the feed flow rate accordingly. Under this dosage, LiF in the first-stage reactor is guaranteed to complete the reaction, and PF5 in the last-stage reactor is completely reacted.

The unreacted gas discharged from each reactor enters the next-stage reactor to participate in the reaction after removing the mist droplets entrained in the unreacted gas through the demister, and the removed liquid returns to the primary reaction through the liquid outlet of the demister device.

Further, the continuous synthesis process also includes:

Prepare raw material gas containing PF5 in PF5 generator;

Carry out crystallization, drying and mother liquor recovery of LiPF6 synthesis liquid in the crystallization system;

HF and/or HCl recovery is carried out in the tail gas recovery system.

The crystallization system may be a static crystallization system or a dynamic crystallization system.

In a specific embodiment, the continuous synthesis process of the present invention comprises the following steps:

S1. in PF5 generator, preparation obtains containing PF5 raw material gas (band pressure);

S2. described containing PF feed gas enters described continuous synthesis reaction system through the feed gas inlet of the first reactor, the LiF reaction liquid in the LiF storage tank enters described continuous synthesis reaction system through the liquid inlet of last stage reactor, The continuous synthesis reaction system comprises four stages of synthesis reactors connected in sequence, each stage of synthesis reactor comprising a demister;

S3. The tail gas discharged from the last stage enters the tail gas recovery system for HF and/or HCl recovery;

The LiPF6 synthesis liquid discharged from the outlet of the first-stage reactor synthesis liquid is crystallized, filtered and dried to obtain LiPF6 finished product, and the filtered mother liquor can be recycled for LiF dissolution.

The product purity of the lithium hexafluorophosphate obtained by the invention is ≥99.95%wt, the acidity is ≤80ppm, and the LiF content is ≤100ppm. Preferably, the product purity of lithium hexafluorophosphate is ≥99.97%wt, the acidity is ≤50ppm, and the LiF content is ≤90ppm.

Compared with prior art, the beneficial effect that the present invention has is as follows:

1. The synthesis reactor of the present invention is equipped with a gas phase distributor and a liquid phase distributor, and at the same time, it is supplemented by a tube design to maximize the contact area between the gas phase and the liquid phase, and has a good mass transfer effect.

2. The present invention adopts multi-stage synthesis reactors connected in series, and gas phase materials and liquid phase materials flow in reverse to ensure complete reaction of LiF in the first-stage reactor; at the same time, from the last-stage reactor to the first-stage reactor, lithium hexafluorophosphate The concentration is gradually increased, and LiPF6 synthesis liquid discharged from the first-stage reactor hardly contains LiF, which improves the product purity and quality of lithium hexafluorophosphate.

3. After the heat of reaction is taken away by transporting the refrigerant in the jacket, the unreacted gas can also take away part of the heat of reaction during the flow process, so that each stage of the reactor can maintain a stable reaction temperature during operation.

4. The gas-phase material and liquid-phase material of the present invention are continuously fed, and the LiPF6 synthetic liquid is continuously discharged, which not only has the advantages of high conversion rate of reactants, high reaction efficiency, and stable operation, but also realizes continuous production of lithium hexafluorophosphate, which is suitable for industrialization application.

Description of drawings

Fig. 1 is the structural representation of lithium hexafluorophosphate synthesis reactor of the present invention;

Figure 2 is a schematic structural view of the continuous synthesis reaction system for lithium hexafluorophosphate in Example 1 of the present invention;

Fig. 3 is a flow chart of the continuous synthesis reaction process of lithium hexafluorophosphate in Example 1 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to these specific implementations. Those skilled in the art will realize that the present invention covers all alternatives, modifications and equivalents as may be included within the scope of the claims.

Example 1

The present embodiment provides a synthesis reactor and continuous synthesis reaction system of lithium hexafluorophosphate, as shown in Figure 1, the synthesis reactor comprises:

The reactor body 1, and the feed gas inlet 11 and the synthesis liquid outlet 13 arranged at the bottom of the reactor body (such as the bottom), the liquid inlet 12 and the reaction gas outlet 14 arranged at the top of the reactor body (such as the top);

Gas distributor 2, located in the lower part of the reactor;

Liquid distributor 3, located in the upper part of the reactor;

A series of tubes 4, the series of tubes are arranged in the reactor body, one end is connected to the outlet of the gas distributor 2, and the other end is connected to the outlet of the liquid distributor 3;

The first sealing plate 51, the setting height of the first sealing plate is lower than the outlet end of the tubes connected to the outlet of the liquid distributor;

The second sealing plate 52, the setting height of the second sealing plate is higher than the outlet end of the tubes connected to the outlet of the gas distributor;

Demister 6, the demister is connected to the reaction gas outlet 14, used to remove the mist droplets entrained in the unreacted gas, the liquid outlet of the demister is connected to the reactor of this stage, after removing the droplets The gas enters the next stage reactor;

The tubes are fixed by the first sealing plate and the second sealing plate, and the outer space of the tubes enclosed by the first sealing plate, the second sealing plate and the reactor body is filled with refrigerant. The reactor body is also provided with a refrigerant inlet 15 and a refrigerant outlet 16 for controlling the reaction temperature.

PF5-containing raw material gas enters the reactor body from the raw material gas inlet 11, and is dispersed through the gas distributor 2, and then contacts and reacts with the LiF-containing reaction liquid that enters the reactor body from the liquid inlet 12 and is dispersed through the liquid distributor 3 , the contact reaction is carried out in each column tube, the generated synthetic liquid containing LiPF6 is discharged from the synthetic liquid outlet 13, and the unreacted gas is discharged from the reaction gas outlet 14.

As shown in Fig. 2, the continuous synthesis reaction system is composed of four-stage synthesis reactors, from left to right, respectively, the first-stage reactor, the second-stage reactor, the third-stage reactor and the fourth-stage reactor. The PF5-containing raw material gas enters the reaction system from the raw material gas inlet of the first-stage reactor, the LiF-containing reaction liquid enters the reaction system from the liquid inlet of the fourth-stage reactor, and the reaction gas outlet of the first-stage reactor is connected to the raw material of the second-stage reactor The gas inlet and the synthetic liquid outlet of the latter stage reactor are connected to the liquid inlet of the previous stage reactor, and the generated synthetic liquid containing LiPF6 is discharged from the reaction system from the synthetic liquid outlet of the primary reactor.

Figure 3 schematically shows the block diagram of the continuous synthesis reaction process of lithium hexafluorophosphate, in addition to the continuous synthesis reaction system, it also includes a PF5 generator, LiF storage tank, tail gas treatment system (HCl post-treatment system or HF recovery system), and Crystallization system including LiPF6 synthesis liquid storage tank, crystallizer, dryer, finished product storage tank. The PF5-containing raw material gas prepared by the PF5 generator enters the first-stage reactor, and the LiF reaction liquid transported by the LiF storage tank enters the fourth-stage reactor. The gas phase material PF5 and the liquid phase material LiF flow countercurrently in the continuous synthesis reaction system, and are Gas-liquid reverse contact reaction in each reactor. The tail gas is discharged from the reaction gas outlet of the fourth-stage reactor, and goes to the HCl post-treatment system or the HF recovery system for recycling. The LiPF6 synthetic liquid is discharged from the synthetic liquid outlet of the primary reactor, and enters the synthetic liquid storage tank, crystallizer, and dryer in turn to obtain the finished product of lithium hexafluorophosphate.

Example 2

This example is the application of the synthesis reactor, continuous synthesis reaction system and process in Example 1.

In this embodiment, phosphorus trichloride and liquid chlorine are used as raw materials to prepare a raw material gas in a PF5 generator. The molar composition of the raw material gas is as follows: PF5=12%, HCl=60%, entrained HF=28% , and unreacted traces of Cl2.

The LiF reaction liquid adopts LiF hydrogen fluoride solution, and the mass composition is as follows: LiF=2wt%, AHF=98%. Control the feed flow rate of the raw material gas to be about 1.5m/s, and the pressure is 1.0MPa; the feed flow rate of the LiF reaction liquid is about 2.0m/s, and the pump is used to transport; so that the phosphorus pentafluoride gas and LiF in the primary reactor The molar ratio of phosphorus pentafluoride gas and LiF in the four-stage reactor is 1:3. The temperature of each reactor is controlled to be about 20°C, the pressure of the first reactor is 0.4MPa, the pressure of the second reactor is 0.3MPa, the pressure of the third reactor is 0.2MPa, and the pressure of the fourth reactor is 0.1MPa.

Adopt static crystallization system to carry out crystallization treatment to LiPF6, obtain LiPF6 finished product (solid) after filtering, primary drying, secondary drying, after testing, the purity of LiPF6 finished product is 99.97wt%, free acid content 50ppm, LiF content (insoluble matter content) 90ppm.

During the operation of the system, no crystallization of LiPF6 and clogging of the gas-phase distributor and liquid-phase distributor occurred, and the operation was stable. And LiF reacts completely in the first reactor, and PF5 reacts completely in the fourth reactor.

Example 3

The operation of this example is the same as that of Example 2, except that the continuous synthesis reaction system is composed of three-stage synthesis reactors.

The purity of LiPF6 finished product obtained by detecting the crystallization is 99.96wt%, the content of free acid is 65ppm, and the content of LiF (insoluble matter) is 80ppm.

During the operation of the system, no crystallization of LiPF6 and clogging of the gas-phase distributor and liquid-phase distributor occurred, and the operation was stable. And LiF completely reacts in the first reactor, and PF5 completely reacts in the third reactor.

Example 4

The operation of this embodiment is the same as that of Embodiment 2, the only difference being that the temperature of each stage reactor is about 10°C. Detect the LiPF that crystallization obtains Finished product purity is 99.96wt%, free acid content 66ppm, LiF (insoluble matter) content 80ppm.

During the operation of the system, no crystallization of LiPF6 and clogging of the gas-phase distributor and liquid-phase distributor occurred, and the operation was stable. And LiF reacts completely in the first reactor, and PF5 reacts completely in the fourth reactor.

Example 5

The operation of this embodiment is the same as that of Example 2, the only difference being that the feed flow velocity of the control feed gas is 1.5m/s, and the feed flow velocity of the LiF reaction solution is 0.5m/s, so that phosphorus pentafluoride in the primary reactor The molar ratio of gas and LiF is 4:1, and the molar ratio of phosphorus pentafluoride gas and LiF in the four-stage reactor is 1:3.

The purity of the LiPF6 finished product obtained by detecting the crystallization is 99.95wt%, the free acid content is 50ppm, and the LiF (insoluble matter) content is 85ppm.

During the operation of the system, no crystallization of LiPF6 and clogging of the gas-phase distributor and liquid-phase distributor occurred, and the operation was stable. And LiF reacts completely in the first reactor, and PF5 reacts completely in the fourth reactor.

Example 6

The operation of this embodiment is the same as that of Example 2, the only difference being that: with phosphorus pentachloride and liquid-phase hydrogen fluoride as raw materials, the raw material gas is prepared in a PF5 generator, and the composition of the raw material gas is the same as in Example 2.

The purity of LiPF6 finished product obtained by detecting the crystallization is 99.97wt%, the content of free acid is 61ppm, and the content of LiF (insoluble matter) is 75ppm.

During the operation of the system, no crystallization of LiPF6 and clogging of the gas-phase distributor and liquid-phase distributor occurred, and the operation was stable. And LiF reacts completely in the first reactor, and PF5 reacts completely in the fourth reactor.

Example 7

The operation of this embodiment is the same as that of Embodiment 2, the only difference is that the pressure of the primary reactor is controlled to 0.6 MPa, the pressure of the secondary reactor is 0.5 MPa, the pressure of the third reactor is 0.4 MPa, and the pressure of the fourth reactor is 0.3 MPa. The purity of LiPF6 finished product obtained by detecting the crystallization is 99.96wt%, the content of free acid is 65ppm, and the content of LiF is 80ppm. During the operation of the system, no crystallization of LiPF6 and clogging of the gas-phase distributor and liquid-phase distributor occurred, and the operation was stable. And LiF reacts completely in the first reactor, and PF5 reacts completely in the fourth reactor.

Claims (21)

1. A lithium hexafluorophosphate synthesis reactor, characterized in that: the reactor comprises: the reactor comprises a reactor body, a raw material gas inlet and a synthetic liquid outlet which are arranged at the lower part of the reactor body, and a liquid inlet and a reaction gas outlet which are arranged at the upper part of the reactor body;

the PF 5-containing raw gas enters the reactor body from the raw gas inlet, is dispersed by the gas distributor, then contacts and reacts with LiF-containing reaction liquid which enters the reactor body from the liquid inlet and is dispersed by the liquid distributor, the generated LiPF 6-containing synthesis liquid is discharged from the synthesis liquid outlet, and unreacted gas is discharged from the reaction gas outlet; the gas distributor and the liquid distributor are arranged in the reactor body, and the arrangement height of the liquid distributor is higher than that of the gas distributor.

2. The lithium hexafluorophosphate synthesis reactor according to claim 1, wherein: the gas distributor is positioned at the lower part of the reactor, and the liquid distributor is positioned at the upper part of the reactor.

3. The synthesis reactor of lithium hexafluorophosphate according to claim 1 or 2, characterized in that: the reactor further comprises:

the tube array is arranged in the reactor body, one end of the tube array is communicated with the outlet of the gas distributor, and the other end of the tube array is communicated with the outlet of the liquid distributor;

the first sealing plate is arranged at a height lower than the outlet end of the tube array communicated with the outlet of the liquid distributor;

the second sealing plate is higher than the outlet end of the tube array communicated with the outlet of the gas distributor.

4. The lithium hexafluorophosphate synthesis reactor according to claim 1, wherein: the reactor also comprises a foam remover, wherein the foam remover is connected with the reaction gas outlet and is used for removing mist droplets entrained in unreacted gas, and a liquid outlet of the foam remover is communicated with the reactor.

5. The lithium hexafluorophosphate synthesis reactor according to claim 1, wherein: the reactor also comprises a jacket arranged outside the reactor body.

6. The lithium hexafluorophosphate synthesis reactor according to any one of claims 1-5, wherein: the reactor is selected from a vertical reaction kettle, a reaction tower or a tubular reactor.

7. A continuous synthesis reaction system of lithium hexafluorophosphate is characterized in that: the continuous synthesis reaction system comprises at least two stages of the reactors of any one of claims 1-5 which are sequentially connected, the raw material gas containing PF5 enters the reaction system from the raw material gas inlet of the first stage reactor, the reaction liquid containing LiF enters the reaction system from the liquid inlet of the last stage reactor, the reaction gas outlet of the former stage reactor is connected with the raw material gas inlet of the latter stage reactor, the synthesis liquid outlet of the latter stage reactor is connected with the liquid inlet of the former stage reactor, and the generated synthesis liquid containing LiPF6 is discharged from the synthesis liquid outlet of the first stage reactor.

8. The continuous synthesis reaction system of lithium hexafluorophosphate according to claim 7, wherein: the continuous synthesis reaction system comprises three to five stages of reactors as claimed in any one of claims 1 to 5 connected in sequence.

9. The continuous synthesis reaction system of lithium hexafluorophosphate according to claim 7, wherein: a foam remover is arranged between a reaction gas outlet of the former-stage reactor and a raw gas inlet of the latter-stage reactor, and a liquid outlet of the foam remover is communicated with the former-stage reactor.

10. The continuous synthesis reaction system of lithium hexafluorophosphate according to claim 7, wherein: the reaction gas outlet of the final stage reactor is connected with a tail gas recovery system for recovering HF and/or HCl.

11. The continuous synthesis reaction system of lithium hexafluorophosphate according to claim 7, wherein: the feed gas inlet of the first stage reactor is connected with a PF5 generator.

12. The continuous synthesis reaction system of lithium hexafluorophosphate according to claim 7, wherein: the liquid inlet of the last stage reactor is connected to a LiF reservoir.

13. The continuous synthesis reaction system of lithium hexafluorophosphate according to claim 7, wherein: the synthetic liquid outlet of the first-stage reactor is connected with a crystallization system, and the crystallization system comprises a synthetic liquid storage tank, a crystallizer, a dryer and a mother liquid tank connected with the crystallizer.

14. A continuous synthesis process of lithium hexafluorophosphate is characterized in that: the continuous synthesis process comprises the following steps:

providing a continuous synthesis reaction system according to any one of claims 7 to 13;

filling a refrigerant in the jacket and/or the shell-and-tube outer space formed by the first sealing plate, the second sealing plate and the reactor body in a surrounding manner;

introducing PF 5-containing raw material gas into a raw material gas inlet of a first stage reactor of the continuous synthesis reaction system, and introducing LiF-containing reaction liquid into a liquid inlet of a final stage reactor;

the PF5 and LiF generate gas-liquid contact reaction in each stage of reactor, liF in the first stage of reactor is completely reacted, PF5 in the last stage of reactor is completely reacted, unreacted PF5 in the previous stage of reactor enters the next stage of reactor step by step through a reaction gas outlet and a feed gas inlet of the next stage of reactor to continuously participate in the reaction, and unreacted LiF reaction liquid in the next stage of reactor and the generated LiPF6 synthetic liquid enter the previous stage of reactor step by step through a synthetic liquid outlet and a liquid inlet of the previous stage of reactor to continuously participate in the reaction;

the resultant LiPF6 synthesis liquid was discharged from the synthesis liquid outlet of the first stage reactor.

15. The continuous synthesis process of lithium hexafluorophosphate according to claim 14, wherein: the reaction temperature of each stage of reactor is-20-40 ℃ and the reaction pressure is 0.1-1.0 MPa.

16. The continuous synthesis process of lithium hexafluorophosphate according to claim 15, wherein: the reaction pressure of the former stage reactor is higher than that of the latter stage reactor, and the raw material gas containing PF5 enters the latter stage reactor by means of pressure difference.

17. The continuous synthesis process of lithium hexafluorophosphate according to claim 14, wherein: the PF 5-containing raw material gas is phosphorus pentafluoride gas or mixed gas of phosphorus pentafluoride and hydrogen chloride.

18. The continuous synthesis process of lithium hexafluorophosphate according to claim 14, wherein: the LiF-containing reaction solution is an HF solution of LiF, or LiF is dissolved in a mother solution obtained after lithium hexafluorophosphate is crystallized and filtered, or LiF is dissolved in an organic solvent.

19. The continuous synthesis process of lithium hexafluorophosphate according to claim 14, wherein: the molar ratio of phosphorus pentafluoride gas and LiF in the first-stage reactor is 3-6:1, and the molar ratio of phosphorus pentafluoride gas and LiF in the final-stage reactor is 1:3 to 6.

20. The continuous synthesis process of lithium hexafluorophosphate according to claim 14, wherein: unreacted gas discharged from each stage of reactor enters the next stage of reactor to participate in reaction after mist droplets entrained in the unreacted gas are removed by a foam remover, and the removed liquid returns to the stage of reactor through a liquid outlet of the foam remover.

21. The continuous synthesis process of lithium hexafluorophosphate according to claim 14, wherein: the continuous synthesis process further comprises:

preparing a PF 5-containing feed gas in a PF5 generator;

crystallizing, drying and mother liquor recovery of LiPF6 synthesis liquid in a crystallization system;

HF and/or HCl recovery is performed in a tail gas recovery system.

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