Device system and method for continuously producing phosphorus pentafluoride

Abstract

The invention provides a device system and method for continuously producing phosphorus pentafluoride. The device system comprises a first reaction kettle, a second reaction kettle, a third reaction kettle and a decomposition kettle which are connected in sequence, wherein a solid-phase distributor and a gas-phase distributor are arranged in the first reaction kettle, and liquid-phase distributors and / or gas-phase distributors are arranged in the second reaction kettle and the third reaction kettle; stirring paddles are respectively arranged in the first reaction kettle, the second reaction kettle, the third reaction kettle and the decomposition kettle. According to the invention, efficient continuous production of phosphorus pentafluoride is realized in a continuous reaction mode by virtue of the specific layout of the reaction kettle and the decomposition kettle and the gas-phase, liquid-phase and solid-phase distributors, meanwhile, decomposition of hexafluorophosphoric acid is avoided, the content of impurities is reduced, the purity and yield of the product are improved, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, and relates to a device system for producing phosphorus pentafluoride, and in particular to a device system and method for continuously producing phosphorus pentafluoride. Background Art

[0002] Phosphorus pentafluoride (PF 5 ) is a colorless, toxic gas that emits smoke in the air. This gas is used to prepare lithium hexafluorophosphate (LiPF), a key electrolyte for lithium-ion batteries. 6 ) is one of the main raw materials of lithium hexafluorophosphate. Since phosphorus pentafluoride is active and not suitable for large-scale storage, the production of lithium hexafluorophosphate generally adopts the method of immediate use.

[0003] At present, the methods for preparing phosphorus pentafluoride by technicians include: reaction of elemental phosphorus with fluorine gas, reaction of phosphorus pentachloride with hydrofluoric acid, reaction of phosphorus trichloride, chlorine gas and hydrofluoric acid, etc. The above reaction directly generates phosphorus pentafluoride, so it is called direct method. Since the cost of raw materials required for the direct method is relatively high, how to use relatively low-cost raw materials such as phosphorus pentoxide, polyphosphoric acid, phosphorus oxytrifluoride, etc. to synthesize phosphorus pentafluoride has become a current research hotspot. The above raw materials cannot directly prepare phosphorus pentafluoride, and need to be prepared by thermal decomposition of the intermediate hexafluorophosphoric acid, so it is called indirect method.

[0004] CN115784182A discloses a process for synthesizing phosphorus pentafluoride from polyphosphoric acid and hydrogen fluoride, which mainly comprises the following steps: S1. introducing nitrogen into a reactor for displacement, and then introducing polyphosphoric acid and anhydrous hydrogen fluoride, the reaction temperature is between -10°C and 0°C, and the reaction time is 2 to 5 hours; wherein the molar amount of anhydrous hydrogen fluoride is 33% to 37% in excess; S2. slowly introducing oleum into the reactor for dehydration, and the molar ratio of oleum to polyphosphoric acid is 5.5 to 5:1; S3. introducing the product into a thermal decomposition reactor to start decomposition to generate phosphorus pentafluoride gas; wherein the decomposition temperature of the thermal decomposition reactor is controlled between 148°C and 153°C, and the obtained phosphorus pentafluoride mixed gas is introduced into an absorption tower for impurity removal.

[0005] However, in the process of producing phosphorus pentafluoride, hexafluorophosphoric acid is easily decomposed into other impurities, resulting in low purity, high impurities and low yield of phosphorus pentafluoride. An excess of anhydrous hydrogen fluoride is required, resulting in low utilization rate of anhydrous hydrogen fluoride. There is still much room for improvement.

[0006] CN114604833A discloses a method for preparing phosphorus pentafluoride, comprising the following steps: (1) adding phosphorus pentoxide to anhydrous hydrogen fluoride, and then adding sulfur trioxide to the reaction system after the addition of phosphorus pentoxide is complete, heating the system for reaction, and obtaining a mixed gas containing phosphorus pentafluoride; (2) condensing the mixed gas containing phosphorus pentafluoride to obtain the phosphorus pentafluoride.

[0007] However, the above method uses phosphorus pentoxide and hydrogen fluoride to intermittently synthesize phosphorus pentafluoride, and solid phosphorus pentoxide needs to be added to a large amount of anhydrous hydrogen fluoride. Due to the violent reaction, the risk of feeding is high; the intermediate product is easy to decompose and bring in impurities, resulting in low purity and low yield; the reaction is an intermittent reaction, which takes a long time, requires a lot of equipment, and has low efficiency; during the initial reaction of phosphorus pentoxide and hydrogen fluoride, the material is relatively sticky and cannot be stirred evenly, and the unreacted material is wrapped therein, with many impurities and low conversion rate, and at the same time, it causes high local heat and generates impurities. In addition, anhydrous hydrogen fluoride needs to be excessive during the reaction, and the excess hydrogen fluoride needs to be recovered by condensation equipment, and some of it cannot be completely recycled, requiring a lot of equipment, and the cost investment is large, which easily causes unnecessary waste of anhydrous hydrogen fluoride.

[0008] It can be seen that how to provide a method for producing phosphorus pentafluoride to avoid decomposition of hexafluorophosphoric acid, reduce the impurity content, thereby improving product purity and yield, while improving reaction efficiency and reducing equipment costs has become an urgent problem that technicians in this field need to solve. Summary of the invention

[0009] The object of the present invention is to provide a device system and method for continuously producing phosphorus pentafluoride. By means of a continuous reaction mode, with the help of a specific reactor and a decomposition reactor layout and gas phase, liquid phase and solid phase distributors, efficient continuous production of phosphorus pentafluoride is achieved, while decomposition of hexafluorophosphoric acid is avoided, impurity content is reduced, product purity and yield are improved, and large-scale promotion and application are facilitated.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a device system for continuously producing phosphorus pentafluoride, the device system comprising a first reactor, a second reactor, a third reactor and a decomposition reactor connected in sequence.

[0012] Among them, the first reactor is provided with a solid phase distributor and a gas phase distributor, the second reactor and the third reactor are provided with a liquid phase distributor and / or a gas phase distributor; the first reactor, the second reactor, the third reactor and the decomposition reactor are respectively provided with stirring paddles.

[0013] The device system provided by the present invention connects three reaction kettles and one decomposition kettle in sequence, realizes continuous feeding and discharging, is convenient for controlling the feeding speed and reaction rate, and is provided with gas phase, liquid phase and solid phase distributors and stirring paddles in the kettle, so that the contact area of ​​each phase material can be maximized, the mass transfer effect and reaction uniformity are improved, and the device system is particularly suitable for efficient and continuous production of phosphorus pentafluoride. The whole device system has a simple structure, low equipment investment cost and maintenance cost, and is conducive to large-scale promotion and application.

[0014] Preferably, the volume ratio of the first reactor, the second reactor and the third reactor is 1:1:(1-2), for example, it can be 1:1:1, 1:1:1.2, 1:1:1.4, 1:1:1.6, 1:1:1.8 or 1:1:2, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, the first reactor, the second reactor and the third reactor are respectively provided with frame-type stirring paddles, and the decomposition reactor is provided with an anchor-type stirring paddle.

[0016] Preferably, the side walls of the first reactor, the second reactor, the third reactor and the decomposition reactor are respectively provided with jackets.

[0017] Preferably, a solid phase distributor is disposed above the interior of the first reaction kettle, and a gas phase distributor is disposed below the interior.

[0018] Preferably, a first discharge port is provided at the side wall between the solid phase distributor and the gas phase distributor.

[0019] Preferably, the height of the first discharge port is located at 1 / 2 to 2 / 3 of the height of the first reactor, more preferably at 2 / 3, and the first discharge port is connected to the bottom of the second reactor.

[0020] Preferably, a first feed inlet is provided on the top of the first reaction kettle.

[0021] Preferably, a liquid phase distributor and a gas phase distributor are arranged in parallel at the lower part of the second reaction kettle, and a second discharge port is arranged at the upper side wall of the interior.

[0022] Preferably, the height of the second discharge port is located at 1 / 2 to 2 / 3 of the height of the second reactor, more preferably at 2 / 3, and the second discharge port is connected to the bottom of the third reactor.

[0023] Preferably, a second feed inlet is provided at the bottom of the second reaction kettle.

[0024] Preferably, a first exhaust port is provided on the top of the second reactor, and the first exhaust port is connected to the bottom of the first reactor.

[0025] Preferably, two groups of liquid phase distributors are arranged in parallel at the lower part of the third reaction kettle, and a third discharge port is arranged at the upper side wall of the interior.

[0026] Preferably, the height of the third discharge port is located at 1 / 2 to 2 / 3 of the height of the third reaction kettle, more preferably at 2 / 3, and the third discharge port is connected to the bottom of the decomposition kettle.

[0027] Preferably, a third feed inlet is provided at the bottom of the third reaction kettle.

[0028] In the present invention, the second reactor and the third reactor both adopt a bottom-in-top-out material transmission method, which promotes the full reaction of the materials in the reactor and further improves the yield of phosphorus pentafluoride.

[0029] Preferably, the bottom of the decomposition kettle is provided with an acid discharge port, and the top of the kettle is provided with a second exhaust port.

[0030] In a second aspect, the present invention provides a method for continuously producing phosphorus pentafluoride using the device system as described in the first aspect, the method comprising the following steps:

[0031] (1) adding phosphorus pentoxide into a solid phase distributor of a first reaction kettle, and introducing anhydrous hydrogen fluoride gas into a gas phase distributor of the first reaction kettle, and reacting under stirring conditions to obtain a first reaction liquid;

[0032] (2) introducing the first reaction liquid into the liquid phase distributor of the second reaction kettle, and introducing the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle into the gas phase distributor of the second reaction kettle, reacting under stirring conditions to obtain the second reaction liquid; then introducing the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle back into the gas phase distributor of the first reaction kettle to react with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid;

[0033] (3) introducing the second reaction liquid into the liquid phase distributor of the third reaction kettle, and introducing the mixed acid into the liquid phase distributor of the third reaction kettle, and reacting under stirring conditions to obtain a third reaction liquid;

[0034] (4) The third reaction liquid is introduced into a decomposition kettle and heated and decomposed under stirring conditions to obtain a mixed gas containing phosphorus pentafluoride.

[0035] Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

[0036] The method provided by the present invention adopts a continuous reaction mode, so that the contact reaction between a large amount of hexafluorophosphoric acid solution, phosphorus pentoxide and hydrogen fluoride in the kettle is relatively mild, and local high temperature will not be generated, thereby avoiding the decomposition of hexafluorophosphoric acid to generate impurities, improving the purity and yield of the product, and because a large amount of hexafluorophosphoric acid solution exists in the kettle due to the continuous reaction, the reaction liquid will not have the phenomenon of material stickiness and resulting in the inability to stir, thereby avoiding local excessive temperature or wrapping of unreacted phosphorus pentoxide, and further improving the reaction uniformity.

[0037] In addition, after the continuous reaction is established, the anhydrous hydrogen fluoride gas is introduced into the second reactor, and the phosphorus pentoxide is introduced into the first reactor. In the first reactor, the excess phosphorus pentoxide causes the hydrogen fluoride to react completely, so there is no need to discharge the hydrogen fluoride gas, and in the second reactor, the excess hydrogen fluoride causes the phosphorus pentoxide to react completely, avoiding the introduction of impurities by unreacted materials. The entire reaction process has no exhaust gas discharge and no material waste, which meets the green and environmentally friendly production requirements.

[0038] Preferably, the molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas in step (1) is 1:(10-15), for example, 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, the temperature inside the first reaction kettle in step (1) is between -10°C and 10°C, for example, it can be -10°C, -8°C, -6°C, -4°C, -2°C, 0°C, 2°C, 4°C, 6°C, 8°C or 10°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, in step (1) and step (2), the residence time of the first reaction liquid in the first reaction kettle is 1-3 h, for example, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] Preferably, the temperature inside the second reaction kettle in step (2) is 20°C to 50°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] Preferably, in step (2), the residence time of the second reaction liquid in the second reaction kettle is 1-3 h, for example, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] Preferably, the temperature inside the third reaction kettle in step (3) is between -20°C and 0°C, for example, -20°C, -18°C, -16°C, -14°C, -12°C, -10°C, -8°C, -6°C, -4°C, -2°C or 0°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, the mixed acid in step (3) comprises fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is (1-1.05):1, for example, it can be 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1 or 1.05:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] In the present invention, the fluorosulfonic acid in the mixed acid can effectively remove the water produced by the reaction, and the excess hydrogen fluoride in the mixed acid can effectively stabilize the hexafluorophosphoric acid to prevent it from decomposing during the dehydration process to produce other impurities, thereby further improving the purity and yield of the product.

[0046] Preferably, the residence time of the third reaction liquid in step (3) in the third reaction kettle is 2-6 h, for example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0047] Preferably, the temperature inside the decomposition kettle in step (4) is 60°C to 90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] As a preferred technical solution of the second aspect of the present invention, the method comprises the following steps:

[0049] (1) phosphorus pentoxide is fed into a solid phase distributor of a first reaction kettle through a first feed port, and anhydrous hydrogen fluoride gas is introduced into a gas phase distributor of the first reaction kettle, while the molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas is controlled to be 1:(10-15), the temperature in the first reaction kettle is between -10°C and 10°C, and a first reaction liquid is obtained after reaction under stirring conditions, and the residence time of the first reaction liquid in the first reaction kettle is 1-3 hours;

[0050] (2) The first reaction liquid is introduced into the liquid phase distributor of the second reaction kettle through the first discharge port, and the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle is introduced into the gas phase distributor of the second reaction kettle through the second feed port, while the temperature in the second reaction kettle is controlled to be 20° C. to 50° C., and the second reaction liquid is obtained after the reaction is reacted under stirring conditions, and the residence time of the second reaction liquid in the second reaction kettle is 1-3 hours; then, the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle is returned to the gas phase distributor of the first reaction kettle through the first exhaust port to react with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid, and the residence time of the first reaction liquid in the first reaction kettle is 1-3 hours;

[0051] (3) introducing the second reaction liquid into the liquid phase distributor of the third reaction kettle through the second discharge port, and introducing the mixed acid into the liquid phase distributor of the third reaction kettle through the third feed port, while controlling the temperature in the third reaction kettle to be between -20°C and 0°C, reacting under stirring conditions to obtain a third reaction liquid, and the residence time of the third reaction liquid in the third reaction kettle is 2-6 hours; the mixed acid comprises fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is (1-1.05):1;

[0052] (4) The third reaction liquid is introduced into the decomposition kettle through the third discharge port, while the temperature inside the decomposition kettle is controlled to be 60° C. to 90° C., and the decomposition is carried out under stirring to obtain a mixed gas containing phosphorus pentafluoride, which is collected through the second exhaust port, and the remaining material is regularly discharged through the acid discharge port.

[0053] Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

[0054] The chemical reaction formula involved in the method provided by the present invention is as follows:

[0055] P 2 O 5 + 12HF = 2HPF 6 + 5H 2 O

[0056] HPF 6 =PF 5 + HF

[0057] HSO 3 F + H 2 O = H 2 SO 4 + HF

[0058] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The device system provided by the present invention connects three reactors and one decomposition reactor in sequence, realizes continuous feeding and discharging, and is convenient for controlling the feeding speed and reaction rate. Gas phase, liquid phase and solid phase distributors and stirring paddles are arranged in the reactor, so that the contact area of ​​each phase material can be maximized, the mass transfer effect and reaction uniformity are improved, and it is particularly suitable for the efficient and continuous production of phosphorus pentafluoride. The whole device system has a simple structure, low equipment investment cost and maintenance cost, and is conducive to large-scale promotion and application.

[0061] (2) The method provided by the present invention adopts a continuous reaction mode, so that the contact reaction between a large amount of hexafluorophosphoric acid solution, phosphorus pentoxide and hydrogen fluoride in the kettle is relatively mild, and no local high temperature is generated, thereby avoiding the decomposition of hexafluorophosphoric acid to produce impurities, improving the purity and yield of the product, and because the continuous reaction causes a large amount of hexafluorophosphoric acid solution to exist in the kettle, the reaction liquid will not become sticky and unable to be stirred, thereby avoiding local excessive temperature or wrapping of unreacted phosphorus pentoxide, further improving the reaction uniformity.

[0062] (3) After the continuous reaction is established, anhydrous hydrogen fluoride gas is introduced into the second reactor, and phosphorus pentoxide is introduced into the first reactor. In the first reactor, the excess phosphorus pentoxide causes the hydrogen fluoride to react completely, so there is no need to discharge the hydrogen fluoride gas. In the second reactor, the excess hydrogen fluoride causes the phosphorus pentoxide to react completely, thus avoiding the introduction of impurities by unreacted materials. The entire reaction process does not emit waste gas and does not waste materials, which meets the production requirements of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 The present invention provides a schematic diagram of the structure of a device system for continuously producing phosphorus pentafluoride.

[0064] Among them: 10-first reactor; 11-first discharge port; 12-first feed port; 20-second reactor; 21-second discharge port; 22-second feed port; 23-first exhaust port; 30-third reactor; 31-third discharge port; 32-third feed port; 40-decomposition reactor; 41-acid discharge port; 42-second exhaust port; 51-frame stirring paddle; 52-anchor stirring paddle; 60-jacket; 71-solid phase distributor; 72-gas phase distributor; 73-liquid phase distributor. DETAILED DESCRIPTION

[0065] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0066] Example 1

[0067] This embodiment provides a device system for continuously producing phosphorus pentafluoride, such as Figure 1 As shown, the device system includes a first reaction kettle 10, a second reaction kettle 20, a third reaction kettle 30 and a decomposition kettle 40 which are connected in sequence.

[0068] Specifically, the volume ratio of the first reactor 10, the second reactor 20 and the third reactor 30 is 1:1:2. The first reactor 10, the second reactor 20 and the third reactor 30 are respectively provided with frame-type stirring paddles 51, the decomposition reactor 40 is provided with anchor-type stirring paddles 52, and the side walls of the first reactor 10, the second reactor 20, the third reactor 30 and the decomposition reactor 40 are respectively provided with jackets 60.

[0069] For the first reactor 10, a solid phase distributor 71 is arranged on the upper part thereof, and a gas phase distributor 72 is arranged on the lower part thereof; a first discharge port 11 is arranged on the side wall between the solid phase distributor 71 and the gas phase distributor 72; the height of the first discharge port 11 is located at 2 / 3 of the height of the first reactor 10, and the first discharge port 11 is connected to the bottom of the second reactor 20; a first feed port 12 is arranged on the top of the first reactor 10.

[0070] For the second reactor 20, a liquid phase distributor 73 and a gas phase distributor 72 are arranged in parallel at the lower part of the interior, and a second discharge port 21 is arranged at the side wall at the upper part of the interior; the height of the second discharge port 21 is located at 2 / 3 of the height of the second reactor 20, and the second discharge port 21 is connected to the bottom of the third reactor 30; the bottom of the second reactor 20 is provided with a second feed port 22, the top of the reactor is provided with a first exhaust port 23, and the first exhaust port 23 is connected to the bottom of the first reactor 10.

[0071] For the third reactor 30, two groups of liquid phase distributors 73 are arranged in parallel at the lower part thereof, and a third discharge port 31 is arranged at the side wall at the upper part thereof; the height of the third discharge port 31 is located at 2 / 3 of the height of the third reactor 30, and the third discharge port 31 is connected to the bottom of the decomposition reactor 40; a third feed port 32 is arranged at the bottom of the third reactor 30.

[0072] The decomposition kettle 40 has an acid discharge port 41 at its bottom and a second exhaust port 42 at its top.

[0073] The device system provided in this embodiment connects three reaction kettles and one decomposition kettle in sequence, realizes continuous feeding and discharging, and is convenient for controlling the feeding speed and reaction rate. Gas phase, liquid phase and solid phase distributors and stirring paddles are arranged in the kettle, so that the contact area of ​​each phase material can be maximized, the mass transfer effect and reaction uniformity are improved, and it is particularly suitable for the efficient and continuous production of phosphorus pentafluoride. The whole device system has a simple structure, low equipment investment cost and maintenance cost, and is conducive to large-scale promotion and application.

[0074] Application Example 1

[0075] This application example uses the device system provided in Example 1 to continuously produce phosphorus pentafluoride. The specific method includes the following steps:

[0076] (1) phosphorus pentoxide is fed into the solid phase distributor 71 of the first reaction kettle 10 through the first feed port 12, and anhydrous hydrogen fluoride gas is introduced into the gas phase distributor 72 of the first reaction kettle 10, while the molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas is controlled to be 1:12, the temperature in the first reaction kettle 10 is 0° C., and a first reaction liquid is obtained after reaction under stirring conditions, and the residence time of the first reaction liquid in the first reaction kettle 10 is 2 hours;

[0077] (2) The first reaction liquid is introduced into the liquid phase distributor 73 of the second reaction kettle 20 through the first discharge port 11, and the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle 10 is introduced into the gas phase distributor 72 of the second reaction kettle 20 through the second feed port 22, and the temperature in the second reaction kettle 20 is controlled to be 35° C., and the second reaction liquid is obtained after the reaction is reacted under stirring conditions, and the residence time of the second reaction liquid in the second reaction kettle 20 is 2 hours; then, the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle 20 is returned to the gas phase distributor 72 of the first reaction kettle 10 through the first exhaust port 23, and reacts with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid, and the residence time of the first reaction liquid in the first reaction kettle 10 is 2 hours;

[0078] (3) introducing the second reaction liquid into the liquid phase distributor 73 of the third reaction kettle 30 through the second discharge port 21, and introducing the mixed acid into the liquid phase distributor 73 of the third reaction kettle 30 through the third feed port 32, while controlling the temperature in the third reaction kettle 30 to be -10°C, reacting under stirring conditions to obtain a third reaction liquid, and the residence time of the third reaction liquid in the third reaction kettle 30 is 4 hours; the mixed acid is fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is 1.02:1;

[0079] (4) The third reaction liquid is introduced into the decomposition kettle 40 through the third discharge port 31, and the temperature inside the decomposition kettle 40 is controlled to be 75° C. The decomposition is heated under stirring conditions to obtain a mixed gas containing phosphorus pentafluoride, which is collected through the second exhaust port 42, and the remaining material is regularly discharged through the acid discharge port 41.

[0080] Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

[0081] The mixed gas containing phosphorus pentafluoride obtained in this embodiment can be directly used to synthesize lithium hexafluorophosphate, and the purity of the produced lithium hexafluorophosphate is as high as 99.9%.

[0082] Application Example 2

[0083] This application example uses the device system provided in Example 1 to continuously produce phosphorus pentafluoride. The specific method includes the following steps:

[0084] (1) phosphorus pentoxide is fed into the solid phase distributor 71 of the first reaction kettle 10 through the first feed port 12, and anhydrous hydrogen fluoride gas is introduced into the gas phase distributor 72 of the first reaction kettle 10, while the molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas is controlled to be 1:10, the temperature in the first reaction kettle 10 is -10°C, and a first reaction liquid is obtained after reaction under stirring conditions, and the residence time of the first reaction liquid in the first reaction kettle 10 is 3 hours;

[0085] (2) The first reaction liquid is introduced into the liquid phase distributor 73 of the second reaction kettle 20 through the first discharge port 11, and the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle 10 is introduced into the gas phase distributor 72 of the second reaction kettle 20 through the second feed port 22, and the temperature in the second reaction kettle 20 is controlled to be 20° C., and the second reaction liquid is obtained after the reaction is reacted under stirring conditions, and the residence time of the second reaction liquid in the second reaction kettle 20 is 3 hours; then, the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle 20 is returned to the gas phase distributor 72 of the first reaction kettle 10 through the first exhaust port 23, and reacts with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid, and the residence time of the first reaction liquid in the first reaction kettle 10 is 3 hours;

[0086] (3) introducing the second reaction liquid into the liquid phase distributor 73 of the third reaction kettle 30 through the second discharge port 21, and introducing the mixed acid into the liquid phase distributor 73 of the third reaction kettle 30 through the third feed port 32, while controlling the temperature in the third reaction kettle 30 to be -20°C, reacting under stirring conditions to obtain a third reaction liquid, and the residence time of the third reaction liquid in the third reaction kettle 30 is 6 hours; the mixed acid is fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is 1:1;

[0087] (4) The third reaction liquid is introduced into the decomposition kettle 40 through the third discharge port 31, and the temperature inside the decomposition kettle 40 is controlled to be 60° C. The decomposition is heated under stirring conditions to obtain a mixed gas containing phosphorus pentafluoride, which is collected through the second exhaust port 42, and the remaining material is regularly discharged through the acid discharge port 41.

[0088] Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

[0089] The mixed gas containing phosphorus pentafluoride obtained in this embodiment can be directly used to synthesize lithium hexafluorophosphate, and the purity of the produced lithium hexafluorophosphate is as high as 99.9%.

[0090] Application Example 3

[0091] This application example uses the device system provided in Example 1 to continuously produce phosphorus pentafluoride. The specific method includes the following steps:

[0092] (1) phosphorus pentoxide is fed into the solid phase distributor 71 of the first reaction kettle 10 through the first feed port 12, and anhydrous hydrogen fluoride gas is introduced into the gas phase distributor 72 of the first reaction kettle 10, while the molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas is controlled to be 1:15, the temperature in the first reaction kettle 10 is 10° C., and a first reaction liquid is obtained after reaction under stirring conditions, and the residence time of the first reaction liquid in the first reaction kettle 10 is 1 hour;

[0093] (2) The first reaction liquid is introduced into the liquid phase distributor 73 of the second reaction kettle 20 through the first discharge port 11, and the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle 10 is introduced into the gas phase distributor 72 of the second reaction kettle 20 through the second feed port 22, and the temperature in the second reaction kettle 20 is controlled to be 50° C., and the second reaction liquid is obtained after the reaction is reacted under stirring conditions, and the residence time of the second reaction liquid in the second reaction kettle 20 is 1 hour; then, the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle 20 is returned to the gas phase distributor 72 of the first reaction kettle 10 through the first exhaust port 23, and reacts with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid, and the residence time of the first reaction liquid in the first reaction kettle 10 is 1 hour;

[0094] (3) introducing the second reaction liquid into the liquid phase distributor 73 of the third reaction kettle 30 through the second discharge port 21, and introducing the mixed acid into the liquid phase distributor 73 of the third reaction kettle 30 through the third feed port 32, while controlling the temperature in the third reaction kettle 30 to be 0° C., reacting under stirring conditions to obtain a third reaction liquid, and the residence time of the third reaction liquid in the third reaction kettle 30 is 2 hours; the mixed acid is fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is 1.05:1;

[0095] (4) The third reaction liquid is introduced into the decomposition kettle 40 through the third discharge port 31, and the temperature inside the decomposition kettle 40 is controlled to be 90° C. The decomposition is heated under stirring conditions to obtain a mixed gas containing phosphorus pentafluoride, which is collected through the second exhaust port 42, and the remaining material is regularly discharged through the acid discharge port 41.

[0096] Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

[0097] The mixed gas containing phosphorus pentafluoride obtained in this embodiment can be directly used to synthesize lithium hexafluorophosphate, and the purity of the produced lithium hexafluorophosphate is as high as 99.9%.

[0098] It can be seen that the method provided in Application Examples 1-3 adopts a continuous reaction mode, so that the contact reaction between a large amount of hexafluorophosphoric acid solution, phosphorus pentoxide and hydrogen fluoride in the kettle is relatively mild, and no local high temperature is generated, thereby avoiding the decomposition of hexafluorophosphoric acid to produce impurities, improving the purity and yield of the product, and because a large amount of hexafluorophosphoric acid solution exists in the kettle due to the continuous reaction, the reaction liquid will not become sticky and unable to stir, thereby avoiding local excessive temperature or wrapping of unreacted phosphorus pentoxide, further improving the reaction uniformity.

[0099] In addition, after the continuous reaction is established, the anhydrous hydrogen fluoride gas is introduced into the second reactor, and the phosphorus pentoxide is introduced into the first reactor. In the first reactor, the excess phosphorus pentoxide causes the hydrogen fluoride to react completely, so there is no need to discharge the hydrogen fluoride gas, and in the second reactor, the excess hydrogen fluoride causes the phosphorus pentoxide to react completely, avoiding the introduction of impurities by unreacted materials. The entire reaction process has no exhaust gas discharge and no material waste, which meets the green and environmentally friendly production requirements.

[0100] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A device system for continuously producing phosphorus pentafluoride, characterized in that: The device system comprises a first reactor, a second reactor, a third reactor and a decomposition reactor which are connected in sequence; Among them, the first reactor is provided with a solid phase distributor and a gas phase distributor, the second reactor and the third reactor are provided with a liquid phase distributor and / or a gas phase distributor; the first reactor, the second reactor, the third reactor and the decomposition reactor are respectively provided with stirring paddles.

2. The device system according to claim 1, characterized in that: The volume ratio of the first reactor, the second reactor and the third reactor is 1:1:(1-2); The first reactor, the second reactor and the third reactor are respectively provided with frame-type stirring paddles, and the decomposition reactor is provided with an anchor-type stirring paddle; The side walls of the first reactor, the second reactor, the third reactor and the decomposition reactor are respectively provided with jackets.

3. The device system according to claim 2, characterized in that: A solid phase distributor is arranged above the interior of the first reactor, and a gas phase distributor is arranged below the interior; A first discharge port is provided at the side wall between the solid phase distributor and the gas phase distributor; The height of the first discharge port is located at 1 / 2 to 2 / 3 of the height of the first reaction kettle, and the first discharge port is connected to the bottom of the second reaction kettle; The top of the first reaction kettle is provided with a first feed inlet.

4. The device system according to claim 3, characterized in that: A liquid phase distributor and a gas phase distributor are arranged in parallel at the lower part of the second reactor, and a second discharge port is arranged at the upper side wall of the interior; The height of the second discharge port is located at 1 / 2 to 2 / 3 of the height of the second reactor, and the second discharge port is connected to the bottom of the third reactor; The bottom of the second reaction kettle is provided with a second feed inlet; The top of the second reactor is provided with a first exhaust port, and the first exhaust port is connected to the bottom of the first reactor.

5. The device system according to claim 4, characterized in that: Two groups of liquid phase distributors are arranged in parallel at the lower part of the third reaction kettle, and a third discharge port is arranged at the upper side wall of the inner part; The height of the third discharge port is located at 1 / 2 to 2 / 3 of the height of the third reaction kettle, and the third discharge port is connected to the bottom of the decomposition kettle; The bottom of the third reaction kettle is provided with a third feed inlet.

6. The device system according to claim 5, characterized in that: The bottom of the decomposition kettle is provided with an acid discharge port, and the top of the kettle is provided with a second exhaust port.

7. A method for continuously producing phosphorus pentafluoride using the device system as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) adding phosphorus pentoxide into a solid phase distributor of a first reaction kettle, and introducing anhydrous hydrogen fluoride gas into a gas phase distributor of the first reaction kettle, and reacting under stirring conditions to obtain a first reaction liquid; (2) introducing the first reaction liquid into the liquid phase distributor of the second reaction kettle, and introducing the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle into the gas phase distributor of the second reaction kettle, reacting under stirring conditions to obtain the second reaction liquid; then introducing the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle back into the gas phase distributor of the first reaction kettle to react with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid; (3) introducing the second reaction liquid into the liquid phase distributor of the third reaction kettle, and introducing the mixed acid into the liquid phase distributor of the third reaction kettle, and reacting under stirring conditions to obtain a third reaction liquid; (4) introducing the third reaction liquid into a decomposition kettle and heating and decomposing the mixture under stirring to obtain a mixed gas containing phosphorus pentafluoride; Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

8. The method according to claim 7, characterized in that The molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas in step (1) is 1:(10-15); Step (1) The temperature inside the first reaction kettle is between -10°C and 10°C; In step (1) and step (2), the first reaction liquid stays in the first reaction kettle for 1-3 hours; Step (2) The temperature inside the second reaction kettle is 20°C to 50°C; The residence time of the second reaction liquid in the second reaction kettle in step (2) is 1-3 hours.

9. The method according to claim 8, characterized in that The temperature inside the third reaction kettle in step (3) is between -20°C and 0°C; The mixed acid in step (3) includes fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is (1-1.05):1; The residence time of the third reaction liquid in the third reaction kettle in step (3) is 2-6 hours; The temperature inside the decomposition kettle in step (4) is 60°C to 90°C.

10. The method according to any one of claims 7 to 9, characterized in that: The method comprises the following steps: (1) phosphorus pentoxide is fed into a solid phase distributor of a first reaction kettle through a first feed port, and anhydrous hydrogen fluoride gas is introduced into a gas phase distributor of the first reaction kettle, while the molar ratio of phosphorus pentoxide to anhydrous hydrogen fluoride gas is controlled to be 1:(10-15), the temperature in the first reaction kettle is between -10°C and 10°C, and a first reaction liquid is obtained after reaction under stirring conditions, and the residence time of the first reaction liquid in the first reaction kettle is 1-3 hours; (2) The first reaction liquid is introduced into the liquid phase distributor of the second reaction kettle through the first discharge port, and the unreacted anhydrous hydrogen fluoride gas in the first reaction kettle is introduced into the gas phase distributor of the second reaction kettle through the second feed port, while the temperature in the second reaction kettle is controlled to be 20° C. to 50° C., and the second reaction liquid is obtained after the reaction is reacted under stirring conditions, and the residence time of the second reaction liquid in the second reaction kettle is 1-3 hours; then, the unreacted anhydrous hydrogen fluoride gas in the second reaction kettle is returned to the gas phase distributor of the first reaction kettle through the first exhaust port to react with the continuously added phosphorus pentoxide to continue to obtain the first reaction liquid, and the residence time of the first reaction liquid in the first reaction kettle is 1-3 hours; (3) introducing the second reaction liquid into the liquid phase distributor of the third reaction kettle through the second discharge port, and introducing the mixed acid into the liquid phase distributor of the third reaction kettle through the third feed port, while controlling the temperature in the third reaction kettle to be between -20°C and 0°C, reacting under stirring conditions to obtain a third reaction liquid, and the residence time of the third reaction liquid in the third reaction kettle is 2-6 hours; the mixed acid comprises fluorosulfonic acid obtained by the reaction of fuming sulfuric acid and anhydrous hydrogen fluoride, and the molar ratio of the fluorosulfonic acid to the generated water is (1-1.05):1; (4) introducing the third reaction liquid into the decomposition kettle through the third discharge port, while controlling the temperature inside the decomposition kettle to be 60° C. to 90° C., heating and decomposing under stirring conditions, and collecting the mixed gas containing phosphorus pentafluoride through the second exhaust port, and regularly discharging the remaining material through the acid discharge port; Wherein, steps (2) to (4) are carried out continuously to continuously produce phosphorus pentafluoride.

Images