Production process and equipment for producing phosphorus pentafluoride
By liquefaction of anhydrous hydrogen fluoride and liquid-solid reaction with phosphorus pentachloride, and using refrigerant to perform series cooling control, the problem of strong exothermic fluoride reaction in the prior art is solved, the volume and production capacity of the reactor are improved, and the safety is enhanced.
Patent Information
- Application Number
- CN202411727993.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-02-25
AI Technical Summary
In the process of producing phosphorus pentafluoride in the prior art, the fluorination reaction is a strong exothermic reaction, resulting in high internal pressure, strict temperature control, safety hazards, and low heat transfer efficiency of gas-solid reaction, limiting the volume and production capacity of the reactor.
After liquefaction of anhydrous hydrogen fluoride, the liquid-solid reaction is carried out with phosphorus pentachloride, and the low temperature of the reactor and condenser is maintained through the refrigerant, so as to realize the series cooling control of fluorination reaction and condensation reflux, reducing the pressure and temperature fluctuations in the reactor.
The pressure and temperature fluctuations in the reactor are reduced, the volume and production capacity of the reactor are improved, the amount of reaction materials that can be invested in a single reaction is increased, the production capacity is improved, and the safety and control of the reaction are improved.
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Figure CN119503744A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of phosphorus chemical production, in particular to a production process and equipment for producing phosphorus pentafluoride. Background Art
[0002] At present, in the lithium-ion battery process, the main component of lithium ion electrolyte is lithium hexafluorophosphate, which can provide a transmission path for lithium ions between the positive and negative electrodes, improve the cycle life and energy density of the battery, and lithium hexafluorophosphate also has good chemical stability and is inert to strong reducing agents. The most widely used method for the industrial production of lithium hexafluorophosphate is the hydrofluoric acid solvent method, that is, phosphorus pentafluoride and lithium fluoride dissolved in anhydrous hydrofluoric acid liquid react to obtain a lithium hexafluorophosphate solution. The solvent method for producing lithium hexafluorophosphate requires a large amount of phosphorus pentafluoride raw material, and phosphorus pentafluoride is a gas at room temperature and pressure, and its transportation cost is high. In addition, the purity of phosphorus pentafluoride directly affects the purity of lithium hexafluorophosphate. Therefore, most companies that use the solvent method to produce lithium hexafluorophosphate will first produce phosphorus pentafluoride themselves.
[0003] In the prior art, the method for producing phosphorus pentafluoride gas is through the reaction of anhydrous hydrogen fluoride and phosphorus pentachloride. Hydrogen fluoride is a colorless gas at room temperature and pressure, with a boiling point of 19.54°C, a melting point of -83.37°C, and a density of 1.008g / cm³ (25 / 4°C), which makes it easy to convert between gas and liquid under the influence of weather temperature. In order to stabilize the state of anhydrous hydrogen fluoride and ensure the stability of production, and its temperature is not high from the boiling point, the company will directly heat it, vaporize it and react with phosphorus pentachloride. The vaporized hydrogen fluoride molecules quickly diffuse to the surface of phosphorus pentachloride and react with it to form phosphorus pentafluoride.
[0004] Although the above method can prepare phosphorus pentafluoride, the fluorination reaction is a highly exothermic reaction, and the reactants (anhydrous hydrogen fluoride) and products (phosphorus pentafluoride) in the reactor are both gases. The pressure inside the reactor is very high. If the heat cannot be removed in time, the reactor will be overheated and over-pressurized, and an explosion will occur. Therefore, the temperature control is very strict, the process control is difficult, and there are safety hazards. Summary of the invention
[0005] The object of the present invention is to provide a production process and equipment for producing phosphorus pentafluoride, so as to solve the technical problem that the above-mentioned prior art process for producing phosphorus pentafluoride using anhydrous hydrogen fluoride and phosphorus pentachloride uses a gas-solid reaction, and the fluorination reaction is a highly exothermic reaction, which makes the temperature control in the production process strict and has potential safety hazards.
[0006] In order to solve the above problems, the technical solution adopted by the present invention is as follows: A production process for producing phosphorus pentafluoride comprises the following steps: Step 1, material preparation: pump the anhydrous hydrogen fluoride into the anhydrous hydrogen fluoride liquefaction tank, liquefy it with a refrigerant, and maintain low temperature to stabilize the anhydrous hydrogen fluoride into a liquid state, and transport the phosphorus pentachloride to the PCl5 silo for temporary storage; Step 2, feeding: pump the anhydrous hydrogen fluoride in the liquefaction to the reactor, start the reactor agitator, and after the speed reaches the specified speed, open the discharge valve at the bottom of the PCl5 temporary storage silo, and control the valve opening so that phosphorus pentachloride is slowly added into the reactor; Step 3, fluorination reaction: using a refrigerant to maintain the reaction temperature of the reactor at about 10-15°C for fluorination reaction, the mixed gas of PF5, HCL and entrained HF generated in the fluorination reaction; Step 4, condensation reflux: the mixed gas generated in step 3 is passed into a condenser for condensation, and the condenser uses a refrigerant to control the temperature at -25 to -35°C. The condenser in step 4 is tilted so that the condensed liquid in the condenser can flow back into the reactor; Step 5, collection: collecting the gas condensed by the condenser to obtain phosphorus pentafluoride.
[0007] A production device for phosphorus pentafluoride used in any one of the production processes of claims 1 to 4, comprising a frame, a reactor mounted on the frame, a liquefaction tank, a silo and a condenser arranged above the reactor, and a refrigeration device, the refrigeration device including a refrigerant pipeline, the reactor, the condenser and the liquefaction tank are all provided with a jacket structure, and the jacket structures of the condenser, the liquefaction tank and the reactor are sequentially connected by a refrigerant pipeline to form a multi-chamber channel.
[0008] The beneficial effects of this embodiment are: 1. In the prior art, when preparing phosphorus pentafluoride, it is usually gasified and reacted with phosphorus pentachloride. However, since the fluorination reaction is a highly exothermic reaction, and the reactants (anhydrous hydrogen fluoride) and the products (phosphorus pentafluoride) in the reactor are both gases, the pressure inside the reactor is very high. If the heat cannot be removed in time, the reactor will be overheated and overpressured, and then an explosion accident will occur. Therefore, the temperature control is very strict, and the process control is difficult and there are safety hazards. In the present application, the anhydrous hydrogen fluoride is liquefied before the reaction, and the gas-solid reaction process is changed into a liquid-solid reaction, thereby reducing the pressure in the reactor. Secondly, during the reaction process of the present application, the anhydrous hydrogen fluoride is always kept in a liquid state. When a large amount of reaction heat is generated, the specific heat capacity of the liquid anhydrous hydrogen fluoride is larger, and the temperature rise after absorbing heat is small. Compared with the prior art, it is less likely to have overheating and overpressure, and is therefore safer.
[0009] 2. In the prior art, since the fluorination reaction is a highly exothermic reaction, the reactor for producing phosphorus pentafluoride by the gas-solid method cannot be too large, because the reaction materials in the middle of the reactor cannot directly contact the side walls of the reactor, and the heat transfer efficiency of the gas is not high. Therefore, when the reactor is too large, the heat generated by the reaction cannot be quickly transferred to the side walls of the reactor by the gas materials, and then carried away by the refrigerant in the jacket of the reactor. Therefore, during the gas-solid reaction, the reaction heat in the middle of the reactor is difficult to be quickly discharged, which limits the volume of the reactor and further limits the amount of reaction materials that can be put into a single reaction. After the present application converts it into a liquid-solid reaction, the thermal conductivity of the liquid is usually better, so the heat of the reaction can be quickly transferred to the side walls of the reactor, so the volume of the reactor can be further increased, the amount of reaction materials that can be put into a single reaction is increased, and the production capacity can be greatly improved.
[0010] 3. Even if the volume of the reactor is not increased, the temperature of the liquid-solid reaction process of the present application is easier to control than the gas-solid reaction in the prior art due to the presence of liquid anhydrous hydrogen fluoride.
[0011] 4. After the anhydrous hydrogen fluoride is liquefied, the anhydrous fluorination can better wet the surface of the solid phosphorus pentachloride during the reaction, so that the contact area between the reactants is increased, the reaction is more complete, and the reaction residue is less.
[0012] 5. The residual residue from the incomplete reaction of the traditional gas-solid reaction needs to be dissolved by the introduction of additional liquid anhydrous hydrogen fluoride. The residual liquid of the present application can be directly discharged, which is easier to clean up.
[0013] Furthermore, in step 1, the temperature of the anhydrous hydrogen fluoride after liquefaction is maintained at 5-10°C.
[0014] Furthermore, the phosphorus pentachloride in step 1 is in the form of white powder.
[0015] Further, the production process also includes a refrigerant circulation process, in which the refrigerant in the refrigerant circulation process is cooled from the refrigeration equipment, and the condensation reflux, the liquefaction of the material preparation, and the fluorination reaction process are sequentially controlled by series cooling. Since the gas-solid reaction of anhydrous hydrogen fluoride and phosphorus pentachloride is converted into a liquid-solid reaction in the present application, and the boiling point of anhydrous hydrogen fluoride is low, and the fluorination reaction is a strong exothermic reaction, anhydrous hydrogen fluoride is easy to evaporate to form a gas phase, therefore, it is necessary to maintain the low temperature of anhydrous hydrogen fluoride in the liquefaction and fluorination stages, if it is cooled separately, it is necessary to lay new pipelines and cool the refrigerant, the transformation cost is large, and the low temperature utilization rate of the refrigerant is also insufficient, resulting in a large amount of refrigeration energy waste, and the overall energy consumption is increased, and the present application will be the original gas-solid reaction The refrigerant of the condensation part is cooled in series, and it is not necessary to invest a large transformation cost, and since the low temperature required for anhydrous hydrogen fluoride is low, it is completely sufficient to use the refrigerant after condensation to cool down, and it will not affect the overall condensation effect.
[0016] Furthermore, the condenser is arranged to be inclined toward the reaction kettle.
[0017] Further, the condenser is installed using a wedge-shaped mounting bracket.
[0018] Furthermore, the installation height of the condenser is higher than that of the liquefier tank, and the installation height of the liquefier tank is higher than that of the reactor. By utilizing the height difference of the installation, the refrigerant forms a flow pattern from top to bottom in the process of sequentially flowing through the condenser, the liquefier tank and the reactor. Therefore, the condensation of the liquefier tank only needs to ensure the refrigerant temperature at the reactor outlet to ensure the overall condensation effect, so that the anhydrous hydrogen fluoride is maintained in liquid form during the entire production process, and this series condensation method maximizes the use of the low temperature of the refrigerant. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a process flow chart of the present invention, Figure 2 It is a schematic diagram of the structure of the production equipment of the present invention. DETAILED DESCRIPTION
[0020] The following is further described in detail through specific implementation methods: The reference numerals in the drawings of the specification include: .
[0021] Implementation example Figure 1-2 As shown: A production process for producing phosphorus pentafluoride comprises the following steps: Step 1, material preparation: pump the anhydrous hydrogen fluoride into the anhydrous hydrogen fluoride liquefaction tank, liquefy it with a refrigerant, and maintain low temperature to stabilize the anhydrous hydrogen fluoride into a liquid state, and transport the phosphorus pentachloride to the PCl5 silo for temporary storage; The boiling point of anhydrous hydrogen fluoride is 19.54° C., so maintaining it at a low temperature can ensure that it is uniformly stable in liquid form. In this embodiment, the low temperature is controlled to be below 10° C. Phosphorus pentachloride is a white powder to ensure the purity and dryness of phosphorus pentachloride and to ensure that no moisture is introduced.
[0022] Step 2, feeding: pump the anhydrous hydrogen fluoride in the liquefaction to the reactor, start the reactor agitator, and after the speed reaches the specified speed, slowly add the phosphorus pentachloride in the PCl5 silo into the reactor; Step 3, fluorination reaction: maintaining the reaction temperature of the reactor at 10-15°C for fluorination reaction, and generating a mixed gas of PF5, HCL and a portion of HF entrained in the fluorination reaction; Step 4, condensation reflux: the mixed gas generated in step 3 is passed into a condenser for condensation, the condensation temperature is -25~-35°C, and the condenser in step 4 is tilted so that the condensed liquid in the condenser can flow back into the reactor; Step 5, collection: collecting the gas condensed by the condenser to obtain phosphorus pentafluoride.
[0023] Phosphorus pentafluoride is mixed with hydrogen chloride, but the hydrogen chloride gas does not affect the subsequent synthesis of lithium hexafluorophosphate. Lithium hexafluorophosphate synthesis: phosphorus pentafluoride and mother liquor containing lithium fluoride react to generate lithium hexafluorophosphate. Hydrogen chloride does not participate in the reaction, and the HF vaporized due to the heat release of the reaction is discharged from the tail gas tank.
[0024] The production process also includes a refrigerant circulation process. In the refrigerant circulation process, after the refrigerant is cooled from the refrigeration equipment, the condensation reflux, liquefaction of the prepared materials, and fluorination reaction processes are sequentially subjected to series cooling control.
[0025] Since the liquid state of anhydrous hydrogen fluoride needs to be kept at a low temperature throughout the process, the liquefaction and fluorination reactions of the prepared materials in the process need to be cooled and maintained at a low temperature. The low temperature of condensation is -25~-35℃, so the temperature of the refrigerant coming out of the condenser is very low. The refrigerant coming out of the condenser is reused to make full use of its low temperature to cool the liquefaction and fluorination reactions of the prepared materials.
[0026] A production equipment for producing phosphorus pentafluoride includes a frame 1, which is a frame welded with angle steels. A rectangular mounting frame 11 is formed in the center of the frame 1 by using transverse angle steels. The frame size of the mounting frame 11 is larger than the diameter of a reactor 2, so that the reactor 2 can be inserted into the mounting frame 11. Bolt holes are opened on the transverse angle steels of the mounting frame 11, and a mounting plate that is integrated with the reactor 2 is welded on the outer peripheral wall of the reactor 2, and bolt holes are also opened on the mounting plate. Therefore, when installing, the reactor 2 is inserted into the mounting frame 11, the bolt holes on the mounting plate are aligned with the bolt holes on the angle steels of the mounting frame 11, and the reactor 2 is fixed to the mounting frame 11 by bolts.
[0027] by Figure 2 The direction is the description direction, and the rack 1 includes a mounting frame 11 and three mounting platforms arranged on the left, right and rear sides of the mounting frame 11. The mounting platform forms a semi-enclosed structure with the mounting frame 11, and the mounting platforms are all rectangular frames welded with angle steels, and then the steel plates are welded on the upper surface of the rectangular frames to form the platforms.
[0028] The installation platform on the left side of the installation frame 11 is the first installation platform 12, which is the installation platform of the condenser 3, and its height is higher than the highest point of the reactor 2 and the liquefied tank 4. The first installation platform 12 is provided with an installation slant pillow, which is a wedge-shaped block with a high left side and a low right side. The installation slant pillow is designed with two front and rear slant pillows, which can just clamp the condenser in the middle. The installation slant pillow is provided with bolt holes, so the condenser 3 can be installed on the installation slant pillow by bolts, so that the condenser 3 is tilted toward the reactor 2.
[0029] A second mounting platform 13 is provided at the rear side of the mounting frame 11. The structure of the second mounting platform 13 is the same as that of the first mounting platform 13, but the height of the second mounting platform 13 is higher than the highest point of the reactor 2. The second mounting platform is the mounting platform of the liquefaction tank 4, so the installation height of the liquefaction tank 4 is higher than the height of the reactor 2. The liquefaction tank 4 is a cylindrical tank body with an arc-shaped top cover.
[0030] A third mounting platform 14 is provided on the right side of the mounting frame 11 . The third mounting platform 14 is a mounting platform for the PCl5 silo 5 . The structure of the third mounting platform 14 is the same as that of the first mounting platform 13 , and the height of the third mounting platform 14 is higher than the highest point of the reactor 2 .
[0031] The top surface of the reactor 2 is an arc-shaped top, and a stirring motor 21 is provided at the highest point of the arc-shaped top of the reactor 2. The output shaft of the stirring motor 21 penetrates the arc-shaped top of the reactor 2 and is key-connected with the stirring blades provided in the reactor 2, thereby driving the stirring blades to rotate in the reactor 2. The output shaft of the stirring motor 21 penetrates the arc-shaped top of the reactor 2 and is connected with a sealed bearing, so that the reactor 2 is separated from the outside.
[0032] An air outlet 22 is provided on the left side of the arc-shaped top of the reactor 2 around the stirring motor 21. The air outlet 22 is connected to the condenser 3. The condenser 3 is a distillation condenser, and its interior includes two channels, the tube side and the shell side. The air outlet 22 is connected to the shell side of the condenser 3 through a pipeline. A liquid inlet is provided on the rear side of the arc-shaped top of the reactor 2 around the stirring motor 21. The liquid inlet is connected to the liquid outlet pipe 41 of the liquefaction tank 4. A feed port 23 is provided on the right side. The feed port 23 is a conical tube structure with a larger upper part and a smaller lower part. A cover plate is provided at the upper end to close the feed port 23, but an opening is provided at the center of the cover plate, which is connected to the discharge pipe 51 of the PCl5 silo 5 through the opening. A screw feeder is provided at the bottom of the PCl5 silo 5. The screw feeder pushes the PCl5 powder in the PCl5 silo 5 into the discharge pipe 51, and then drops it into the reactor 2.
[0033] The reactor 2, condenser 3 and liquefaction tank 4 are all provided with jacket structures, and all jacket structures are provided with refrigerant inlet pipe 61 and refrigerant outlet pipe 64; the jacket structure of condenser 2 is the pipe side of the distillation condenser. The jackets of condenser 3, liquefaction tank 4 and reactor 2 are connected by refrigerant pipeline. Specifically, a first refrigerant pipeline 62 is provided between the refrigerant outlet pipe 64 of condenser 3 and the refrigerant inlet pipe 61 of liquefaction tank 4 for connection, and a second refrigerant pipeline 63 is provided between the refrigerant outlet pipe 64 of liquefaction tank 4 and the refrigerant inlet pipe 61 of reactor 2 for connection. Therefore, the jackets of condenser 3, liquefaction tank 3 and reactor 2 are penetrated by the first refrigerant pipe 62 and the second refrigerant pipe 63 to form a multi-chamber channel structure, the refrigerant inlet pipe 61 on condenser 3 is the only inlet of the whole multi-chamber channel structure, and the refrigerant outlet pipe 64 on reactor 2 is the only outlet of the whole multi-chamber channel structure. Since the second mounting platform 13 of the liquefaction tank 4 is higher than the reactor 2, and the first mounting platform 12 is higher than the second mounting platform 13, when the refrigerant flows in the entire multi-chamber channel structure, it flows from top to bottom.
[0034] A refrigeration device (not shown in the figure) is provided behind the rack 1. The refrigeration device includes an indirect refrigeration unit. The indirect refrigeration unit is a prior art. The indirect refrigeration unit includes a condenser and an evaporator, and the condenser and the evaporator are connected by a pipeline to form a closed cavity, and a refrigerant is injected into the cavity. The refrigeration effect is achieved by the circulation of the refrigerant between the condenser and the evaporator. The refrigerant absorbs heat in the condenser and becomes gaseous, and then is compressed by the compressor to become a high-temperature and high-pressure gas. Then, the high-temperature and high-pressure gas enters the evaporator, releases heat, and becomes liquid. Finally, the liquid refrigerant returns to the condenser again for circulating refrigeration. The refrigeration device also includes a heat exchange cavity and a refrigerant pipeline connected to the heat exchange cavity. The condenser and the heat exchange cavity of the indirect refrigeration unit share a side wall, so the refrigerant absorbs the heat in the heat exchange cavity in the condenser.
[0035] The multi-chamber channel structure is connected to the refrigerant pipeline of the refrigeration equipment to form a closed cavity, and a refrigerant medium is injected into the cavity, and dichloromethane can be selected as the refrigerant medium. After injection, the condenser 3, the liquefier tank 4 and the reactor 2 can use the refrigerant medium to control their temperature. After the refrigerant is cooled in the heat exchanger, it enters the multi-chamber channel structure from the refrigerant inlet pipe 61 of the condenser 3 to cool the condenser 3, the liquefier tank 4 and the reactor 2 in turn, and flows out from the refrigerant outlet pipe 64 on the reactor 2 after cooling.
[0036] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.
Claims
1. A production process for producing phosphorus pentafluoride, characterized in that: The following steps are involved: Step 1, material preparation: pump the anhydrous hydrogen fluoride into the anhydrous hydrogen fluoride liquefaction tank, liquefy it with a refrigerant, and maintain low temperature to stabilize the anhydrous hydrogen fluoride into a liquid state; transport phosphorus pentachloride to the PCl5 silo for temporary storage; Step 2, feeding: pump the anhydrous hydrogen fluoride in the liquefaction to the reactor, start the reactor agitator, and after the speed reaches 30-40 rpm, add the phosphorus pentachloride in the PCl5 silo into the reactor; Step 3, fluorination reaction: using a refrigerant to maintain the reaction temperature of the reactor at 10-15°C for fluorination reaction, and generating a mixed gas of PF5, HCL and a portion of HF entrained in the fluorination reaction; Step 4, condensation reflux: the mixed gas generated in step 3 is passed into a condenser for condensation, and the condenser uses a refrigerant to control the temperature at -25 to -35°C. The condenser in step 4 is tilted so that the condensed liquid in the condenser can flow back into the reactor; Step 5, collection: collecting the gas condensed by the condenser to obtain phosphorus pentafluoride.
2. The process for producing phosphorus pentafluoride according to claim 1, characterized in that: In the step 1, the temperature of the anhydrous hydrogen fluoride after liquefaction is maintained below 10°C.
3. The process for producing phosphorus pentafluoride according to claim 2, characterized in that: The phosphorus pentachloride in step 1 is in the form of white powder.
4. The process for producing phosphorus pentafluoride according to claim 1, characterized in that: The production process also includes a refrigerant circulation process. In the refrigerant circulation process, after the refrigerant is cooled from the refrigeration equipment, the condensation reflux, liquefaction of the prepared materials, and fluorination reaction processes are sequentially subjected to series cooling control.
5. A production device for phosphorus pentafluoride used in any one of the production processes of claims 1 to 4, comprising a frame, a reactor mounted on the frame, a liquefaction tank, a silo and a condenser arranged above the reactor, characterized in that: It also includes a refrigeration device, which includes a refrigerant pipeline. The reactor, condenser and liquefaction tank are all provided with a jacket structure. The jacket structures of the condenser, liquefaction tank and reactor are connected in sequence by the refrigerant pipeline to form a multi-chamber channel.
6. The production equipment for producing phosphorus pentafluoride according to claim 5, characterized in that: The condenser is arranged inclined toward the reaction kettle.
7. The production equipment for producing phosphorus pentafluoride according to claim 6, characterized in that: The condenser is mounted using wedge-shaped mounting brackets.
8. The production equipment for producing phosphorus pentafluoride according to claim 7, characterized in that: The installation height of the condenser is higher than that of the liquefaction tank, and the installation height of the liquefaction tank is higher than that of the reactor.