Device and method for preparing ethoxypentafluorocyclotriphosphazene

Abstract

The invention provides a preparation device and method of ethoxypentafluorocyclotriphosphazene. The preparation device comprises a fluorination reaction system, a first solid-liquid separation system, an intermediate purification system, an etherification reaction system, a second solid-liquid separation system, a post-treatment system and a solvent recovery and product refining system which are connected in sequence. Through innovative processes such as low-temperature reaction, distillation desublimation purification and solvent pretreatment, the yield and the purity of the ethoxypentafluorocyclotriphosphazene are remarkably improved, and meanwhile, the safety problem in the production process is solved.

Description

Technical Field

[0001] This invention relates to the field of organophosphorus nitrile compound synthesis technology, and more specifically, to an apparatus and method for preparing ethoxypentafluorocyclotriphosphazene. Background Technology

[0002] With the rapid development of new energy vehicles and the energy storage industry, the safety of lithium batteries has received increasing attention. As a key functional additive for improving the flame retardant performance of lithium battery electrolytes, organophosphazene flame retardants, especially ethoxypentafluorocyclotriphosphazene (PFPN), are crucial. Due to its excellent flame retardant efficiency, good electrochemical stability, and excellent compatibility with electrolyte systems, market demand continues to rise.

[0003] However, a systematic search and analysis of existing patents, literature, and industrial production data revealed that the current synthesis process of PFPN still faces significant technical bottlenecks, mainly in terms of low yield and poor safety.

[0004] 1) Product yield is low, generally below 50%.

[0005] The overall yield in the synthetic route from hexachlorocyclotriphosphazene (HCCP) to PFPN is difficult to exceed 50%, mainly for the following reasons:

[0006] Low conversion rate of fluorination reaction: The fluorination step involves a solid-liquid two-phase reaction with poor mass transfer efficiency, which makes it difficult for HCCP to be completely converted, thus limiting the supply of raw materials for subsequent reactions.

[0007] The intermediate HFP has poor stability: The key intermediate hexafluorocyclotriphosphazene (HFP) has extremely poor thermal stability—it is physically prone to sublimation and chemically prone to thermal decomposition. In traditional processes, its purification relies on high-temperature distillation or rectification operations (>80℃), which easily leads to the decomposition and sublimation loss of HFP, significantly reducing the yield.

[0008] Insufficient selectivity in etherification reaction: HFP molecules contain six active sites, making it difficult to precisely control the degree of substitution during etherification with ethanol. This can easily lead to the formation of over-substituted byproducts, affecting the purity and yield of the target product.

[0009] 2) Significant safety hazards in the production process

[0010] Phosphazene compounds are highly susceptible to thermal runaway under high-temperature conditions. Current processes require high-temperature purification of unstable HFP intermediates, posing significant safety risks.

[0011] HFP is easily decomposed at high temperatures, releasing toxic fluorinated gases (such as HF);

[0012] At the same time, polymerization reactions may occur, leading to pipe blockage, pressure buildup, and even equipment failure or safety accidents.

[0013] High-risk operations place extremely high demands on equipment materials, sealing, and the operating environment, significantly increasing the difficulty and cost of industrial scale-up.

[0014] Therefore, in view of the above situation, there is an urgent need to develop a method to avoid high-temperature separation and purification of intermediate HFP, to achieve a milder and continuous reaction process, to significantly improve product yield and process safety, and to have good scalability to meet the needs of large-scale industrial production. Summary of the Invention

[0015] The purpose of this invention is to provide an apparatus and method for preparing ethoxypentafluorocyclotriphosphazene, which aims to solve the problems mentioned in the background art.

[0016] The present invention is implemented as follows: an apparatus for preparing ethoxypentafluorocyclotriphosphazene includes a fluorination reaction system, a first solid-liquid separation system, an intermediate purification system, an etherification reaction system, a second solid-liquid separation system, a post-processing system, and a solvent recovery and product purification system connected in sequence.

[0017] The fluorination reaction system includes a fluorination reactor with a cooling jacket, a stirrer, and a precision temperature control system.

[0018] The first solid-liquid separation system includes a first filter for removing salt residue, a byproduct of the fluorination reaction;

[0019] The intermediate purification system is an integrated distillation and sublimation purification device that combines a negative pressure distillation column, a low temperature sublimator, a rotary scraper system, and an HFP solid receiving tank.

[0020] The etherification reaction system includes an etherification reactor equipped with a cryogenic jacket, a stirrer, and an ethoxy reagent dripping system;

[0021] The second solid-liquid separation system includes a second filter for removing salt residue, a byproduct of the etherification reaction;

[0022] The post-processing system includes a water washing tank with stirring function and a phase separation tank for static phase separation;

[0023] The solvent recovery and product purification system includes a fluorinated solvent circulating distillation column, an etherified solvent circulating distillation column for etherified solvent distillation to remove light pretreatment, and a product distillation column in the form of a vacuum precision distillation column for product purification.

[0024] Optionally, in the fluorination reaction system, the solvent for the fluorination reaction is selected from ethylene glycol dimethyl ether; in the intermediate purification system, the absolute operating pressure of the negative pressure distillation column is 0.1–30 kPa, and the refrigerant temperature of the low-temperature sublimator is ≤0°C; in the etherification reaction system, the solvent for the etherification reaction is selected from n-decane.

[0025] Optionally, the product distillation column operates at an absolute pressure of <10 kPa and can output ethoxypentafluorocyclotriphosphazene product with a purity of ≥99.9%.

[0026] Optionally, the water washing vessel is used to wash the filtrate after the etherification reaction with deionized water, and the phase separation vessel is used to allow the washed material to stand and separate into layers to extract the organic phase.

[0027] Another object of the present invention is a method for preparing ethoxypentafluorocyclotriphosphazene, using the aforementioned preparation apparatus, comprising the following steps:

[0028] S1. Fluorination reaction: Dissolve hexachlorocyclotriphosphazene in a fluorination solvent and put it into a fluorination reaction vessel. Add fluorination reagent under stirring and cooling conditions, control the reaction temperature at 0℃~60℃, and react for 6~15 hours.

[0029] S2. Solid-liquid separation and intermediate purification: The reaction material in step S1 is filtered and desalted through the first filter. The filtrate is sent to the integrated distillation and sublimation purification equipment. Distillation is carried out under negative pressure to allow the hexafluorocyclotriphosphazene vapor to enter the low-temperature sublimator and condense into a solid, and high-purity hexafluorocyclotriphosphazene is collected.

[0030] S3, Etherification reaction: Dissolve the hexafluorocyclotriphosphazene obtained in step S2 in an etherification solvent that has been pretreated by distillation to remove light content, transfer it to an etherification reactor, add ethoxy reagent under stirring and deep cooling conditions, control the reaction temperature at -30℃~20℃, and react for 4~10 hours.

[0031] S4. Post-processing and product refining: The reaction material from step S3 is filtered through a second filter to remove salt. The filtrate is transferred to a water washing kettle for washing with deionized water, and then placed in a phase separation kettle for phase separation to extract the organic phase. The organic phase is then sequentially passed through an etherification solvent circulating distillation column to recover the solvent and a product distillation column to obtain ethoxypentafluorocyclotriphosphazene product.

[0032] Optionally, in step S1, the fluorinating agent is selected from potassium fluoride or sodium fluoride.

[0033] Optionally, in step S2, the absolute pressure of the negative pressure condition is 0.1 to 30 kPa, the temperature of the low-temperature sublimator is ≤0℃, and the yield of the collected hexafluorocyclotriphosphazene is >90%, and the purity is >96.0%.

[0034] Optionally, in step S3, the etherification solvent is n-decane, and the ethoxy reagent is selected from sodium ethoxide or ethanol.

[0035] Optionally, in step S4, the deionized water washing is performed 3 times, and the ratio of deionized water volume to filtrate volume for each washing is 3:10; the operating absolute pressure of the product distillation column is <10 kPa.

[0036] Optionally, based on hexachlorocyclotriphosphazene, the total yield of the ethoxypentafluorocyclotriphosphazene is >70%, and the product purity is ≥99.9%.

[0037] The present invention provides an apparatus and method for preparing ethoxypentafluorocyclotriphosphazene, which has the following beneficial effects:

[0038] This invention integrates low-temperature fluorination, distillation and sublimation purification, low-temperature etherification, and efficient refining processes. It creatively employs a "negative pressure distillation-low-temperature sublimation" coupling technology to achieve high solid-phase purification of HFP intermediates (>90%), avoiding high-temperature decomposition and sublimation losses. Combined with end-to-end low-temperature control (-30~60℃), it significantly improves the inherent safety of production. Simultaneously, it introduces a distillation pretreatment process for removing light components from the etherification solvent, effectively removing impurities to improve the final product distillation yield. Ultimately, the total yield from HCCP to ethoxypentafluorocyclotriphosphazene (PFPN) is stably increased to over 70%, with a product purity exceeding 99.9%. This solves the bottleneck problems of low yield and poor safety in traditional processes, achieving efficient, safe, and scalable production of high-purity PFPN, and possesses significant industrial application value.

[0039] In summary, this invention significantly improves the yield and purity of ethoxypentafluorocyclotriphosphazene through innovative processes such as low-temperature reaction, distillation and sublimation purification, and solvent pretreatment, while solving safety issues in the production process and realizing efficient, safe, and scalable industrial production.

[0040] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0042] Figure 1 A process flow diagram of the apparatus for preparing ethoxypentafluorocyclotriphosphazene provided in an embodiment of the present invention. Detailed Implementation

[0043] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0044] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0045] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0046] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0047] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0048] The following is a detailed description, with reference to the accompanying drawings, of an apparatus and method for preparing ethoxypentafluorocyclotriphosphazene according to an embodiment of the present invention.

[0049] like Figure 1 The diagram illustrates an apparatus for preparing ethoxypentafluorocyclotriphosphazene according to an embodiment of the present invention. Through a series of optimized designs, the product yield and production safety are effectively improved. The apparatus mainly comprises, in sequence, a fluorination reaction system, a first solid-liquid separation system, an intermediate purification system, an etherification reaction system, a second solid-liquid separation system, a post-processing system, and a solvent recovery and product purification system.

[0050] Fluorination reaction system: This system comprises a fluorination reactor equipped with a cooling jacket, a stirrer, and a precision temperature control system, used for carrying out fluorination reactions at room temperature. The solvent for the fluorination reaction is selected from ethylene glycol dimethyl ether or anhydrous acetonitrile, preferably ethylene glycol dimethyl ether.

[0051] First solid-liquid separation system: including a first filter for removing salt residue produced after fluorination reaction.

[0052] Intermediate purification system: This is the core innovative component, employing an integrated distillation and sublimation purification system combining a negative pressure distillation column and a cryogenic sublimator, equipped with a rotary scraper system and an HFP solid receiving tank to achieve efficient HFP purification. The negative pressure distillation column operates at an absolute pressure of 0.1–30 kPa, and the refrigerant temperature of the cryogenic sublimator is ≤0℃.

[0053] Etherification reaction system: Composed of an etherification reactor equipped with a cryogenic jacket, a stirrer, and an ethoxylated reagent dropwise addition system, suitable for etherification reactions under low-temperature conditions. In this etherification reaction system, the solvent for the etherification reaction is selected from n-hexane or n-decane, preferably n-decane.

[0054] Second solid-liquid separation system: A second filter is used to remove the by-product salt residue after the etherification reaction.

[0055] Post-processing system: includes a water washing vessel with stirring function and a phase separation vessel for settling and phase separation. The water washing vessel is used to wash the filtrate after the etherification reaction with deionized water, and the phase separation vessel is used to allow the washed material to settle and separate into layers to extract the organic phase.

[0056] The solvent recovery and product purification system comprises a fluorinated solvent circulating distillation column, an etherified solvent circulating distillation column, and a product distillation column, used for solvent recovery and final product purification, respectively. The fluorinated solvent circulating distillation column is used to recover and purify fluorinated solvents such as ethylene glycol dimethyl ether; the etherified solvent circulating distillation column is used for distillation pretreatment of the etherified solvent n-decane to remove light components and to recover and purify n-decane and other etherified solvents; the product distillation column (a vacuum precision distillation column) is used for final purification to obtain PFPN product with a purity >99.9%. The operating absolute pressure of the product distillation column is <10 kPa.

[0057] In addition, the fluorination reactor, etherification reactor and piping system are preferably made of 316L stainless steel or nickel-based alloy to resist fluoride corrosion and extend the service life of the equipment.

[0058] like Figure 1 As shown, one embodiment of the present invention also provides a method for preparing ethoxypentafluorocyclotriphosphazene, which uses the above-described apparatus to prepare ethoxypentafluorocyclotriphosphazene, comprising the following steps:

[0059] S1, Fluorination reaction:

[0060] Hexachlorocyclotriphosphazene (HCCP) is dissolved in a selected fluorination reaction solvent and added to the fluorination reaction vessel.

[0061] Add a fluorinating agent (such as potassium fluoride or sodium fluoride, preferably potassium fluoride) under stirring and cooling conditions, control the reaction temperature at 0℃ to 60℃, and continue the reaction for 6 to 15 hours.

[0062] The temperature of the fluorination reaction is preferably controlled at 10°C to 20°C, and the reaction time is preferably 12 hours.

[0063] S2. Solid-liquid separation and purification of intermediates (HFP):

[0064] After the reaction is complete, the material is filtered through the first filter to remove by-product salts, and then the filtrate is sent to an integrated distillation and sublimation purification device.

[0065] Distillation is carried out under negative pressure (absolute pressure 0.1~30kPa), allowing HFP vapor to enter a low-temperature condenser (coolant temperature ≤0℃) and directly condense into a high-purity solid, which is then collected in an HFP solid receiving tank.

[0066] The yield of the collected hexafluorocyclotriphosphazene was >90%, and the purity was >96.0%.

[0067] S3, Etherification reaction:

[0068] The high-purity HFP solid obtained in step S2 is dissolved in a pretreated etherification reaction solvent (the etherification reaction solvent is selected from n-hexane and n-decane, preferably n-decane; and the n-decane needs to be pretreated by distillation to remove light components before use in an etherification solvent circulating distillation column) and transferred to the etherification reaction vessel.

[0069] Under stirring and deep cooling conditions, slowly add an ethoxylated reagent (such as sodium ethoxide or ethanol, preferably sodium ethoxide), control the reaction temperature at -30℃ to 20℃, and continue for 4 to 10 hours.

[0070] The temperature of the etherification reaction is preferably controlled at -20℃ to 10℃, and the reaction time is preferably 6 to 8 hours.

[0071] S4. Post-processing and product finishing:

[0072] After the reaction solution passes through the second filter to remove the remaining salt residue, it is transferred to a water washing kettle for washing with deionized water, and then enters a phase separation kettle for static phase separation to extract the organic phase.

[0073] The organic phase first enters the etherification solvent circulating distillation column to recover the solvent, and then the top liquid enters the product distillation column for precision distillation under negative pressure (absolute pressure <10 kPa). Finally, ethoxypentafluorocyclotriphosphazene product with a purity of over 99.9% is collected, and the total yield is >70%.

[0074] The deionized water washing is performed 3 times, and the ratio of deionized water volume to filtrate volume for each washing is 3:10.

[0075] The above-described apparatus and method enable the efficient and safe synthesis of ethoxypentafluorocyclotriphosphazene, solving the problems of low yield and safety hazards in traditional processes.

[0076] Example 1

[0077] In a 2L fluorination reactor, 1000mL of anhydrous ethylene glycol dimethyl ether and 200g (0.575mol) of hexachlorocyclotriphosphazene (HCCP) were added. Stirring was started and the cooling system was activated to lower the reaction temperature to 10°C. Then, 240g (4.13mol) of dry potassium fluoride powder was slowly added via a feeding device, controlling the temperature to remain below 20°C during the reaction. After the addition was complete, the reaction was continued at 20°C with stirring for 12 hours.

[0078] After the reaction is complete, the material is separated into solid and liquid components by passing it through the first filter. The filter cake is washed with a small amount of ethylene glycol dimethyl ether. The filtrate and washing liquid are combined to obtain a solution containing the intermediate hexafluorocyclotriphosphazene (HFP).

[0079] The filtrate was transferred to an integrated distillation-sublimation purification system. The system was evacuated to an absolute pressure of 20.0 kPa and heated to 38°C for vacuum distillation. The generated HFP vapor entered a cryogenic sublimator at 0°C (provided by an ethylene glycol / dry ice cryogenic unit) and condensed directly into a white, flaky solid. The solid was collected using a rotating scraper system, yielding 136.5 g (0.548 mol) of HFP, with a yield of 95.3%. Gas chromatography (GC) analysis showed a purity >96.0%.

[0080] The obtained HFP solid (136.5 g, 0.548 mol) was dissolved in 800 mL of n-decane pretreated with light radicals, transferred to an etherification reactor, and the reaction system was cooled to -20 °C. Under continuous stirring, a suspension prepared from 37.5 g (0.551 mol) sodium ethoxide and 250 mL of n-decane was slowly added dropwise, controlling the temperature during the addition process to be below 5 °C. After the addition was complete, the reaction was continued at -20 °C for 6 hours.

[0081] After the reaction is complete, the material is filtered through a second filter to remove byproduct salts and impurities. The filtrate is then transferred to a washing vessel and washed with deionized water (300 mL × 3 times). After washing, the material is allowed to stand in a phase separation vessel to separate the organic phase.

[0082] The organic phase was first fed into an etherification solvent circulating distillation column to recover the n-decane solvent. The distillate from the top of the column then entered a product distillation column for vacuum precision distillation under an absolute pressure of 5 kPa. The target fraction was collected to obtain 120.0 g (0.436 mol) of colorless, transparent liquid ethoxypentafluorocyclotriphosphazene (PFPN). Gas chromatography (GC) analysis showed that the product purity was 99.98%.

[0083] Based on the initial HCCP, the total yield of PFPN in this embodiment is 75.8%, which is significantly better than the conventional process.

[0084] Example 2

[0085] In a 2L fluorination reactor, add 1000mL of anhydrous ethylene glycol dimethyl ether and 200g (0.575mol) of HCCP. Start stirring and cool to 20°C. Slowly add 240g (4.13mol) of dry potassium fluoride powder, controlling the reaction temperature not to exceed 30°C. After the addition is complete, react at 20°C for 6 hours.

[0086] After the reaction was completed, the mixture was filtered through the first filter, and the filter cake was washed with a small amount of solvent. The filtrate and washings were then combined.

[0087] The filtrate was transferred to a distillation-sublimation apparatus. The system was evacuated to an absolute pressure of 10.0 kPa and heated to 30 °C for vacuum distillation. The HFP vapor entered a sublimator at 10 °C (ethylene glycol / dry ice cooling) and directly sublimated into a solid product. 129.3 g (0.519 mol) of white flaky HFP solid was collected by a rotating scraper, with a yield of 90.0% and a purity >96.0% as determined by GC.

[0088] 129.3 g (0.519 mol) of solid HFP was dissolved in 1000 mL of n-decane that had undergone light-weight removal pretreatment, and the solution was transferred to an etherification reactor and cooled to -10 °C. 35.32 g (0.519 mol) of solid sodium ethoxide was slowly added under stirring. After the addition was complete, the reaction was carried out at -10 °C for 12 hours.

[0089] The reaction solution was filtered through a second filter to remove salt residue. The filtrate was transferred to a water washing vessel and washed with deionized water (300 mL × 3 times). After phase separation, the organic phase was collected.

[0090] The organic phase was first passed through an etherification solvent circulating distillation column to recover n-decane. The top liquid was then fed into a product distillation column and vacuum distilled at an absolute pressure of 7 kPa. The target fraction was collected to obtain 108.0 g (0.393 mol) of PFPN product with a GC purity of 99.96%.

[0091] Based on HCCP, the overall yield was 68.3%, indicating that the process still has good efficiency and stability even with a short reaction time.

[0092] Example 3

[0093] Following the operating procedure of Example 1, only the fluorination reaction solvent was replaced with anhydrous acetonitrile instead of ethylene glycol dimethyl ether; all other reaction conditions, equipment configuration, and post-processing steps remained the same.

[0094] The results showed that the yield of HFP intermediate was 80.0%, and 110.1 g (0.364 mol) of PFPN product was finally obtained, with an overall yield of 63.3% and a GC purity of 99.92%.

[0095] These results indicate that although acetonitrile can also be used as a solvent for fluorination reactions, its promoting effect on HFP formation and its system stability are inferior to those of ethylene glycol dimethyl ether, resulting in a decrease in both intermediate and final product yields. Therefore, ethylene glycol dimethyl ether is a better choice as a solvent for fluorination reactions.

[0096] Comparative Example

[0097] Traditional high-temperature distillation for HFP purification yields only 60% with a purity of <95%, and decomposition occurs during the process. Therefore, the method of this invention is significantly superior to the comparative method in terms of yield, purity, and safety.

[0098] The above embodiments of the present invention provide an apparatus and method for preparing ethoxypentafluorocyclotriphosphazene. Through specific low-temperature reaction, innovative purification process, and integrated device design, a total yield of over 70% is achieved, fundamentally eliminating the high-temperature safety risks and low product yield problems in the production process. The following are the main innovations of the present invention and their beneficial effects:

[0099] 1) Innovative intermediate purification process

[0100] Coupling technology of negative pressure distillation and low-temperature sublimation: This invention is the first to use a coupling technology of "negative pressure distillation and low-temperature sublimation" to replace traditional high-temperature distillation for the purification of the thermosensitive intermediate HFP. This method directly transforms HFP from the gas phase to the solid phase, perfectly avoiding its unstable range of liquid and high temperature, fundamentally solving the yield loss problem caused by thermal decomposition and easy sublimation (increasing yield from usually <60% to >90%), and significantly reducing safety risks. This is the core innovation of this scheme that enables high overall yield.

[0101] 2) End-to-end low-temperature control and high safety

[0102] Low-temperature operation: From fluorination (0–60°C) to HFP purification (low-temperature solid state) and etherification reaction (-30–20°C), the entire process is carried out at low temperatures, completely eliminating the decomposition, polymerization, and safety hazards caused by high temperatures in existing technologies. This end-to-end low-temperature control not only improves production safety but also ensures the stability of product quality.

[0103] 3) Unique solvent pretreatment process

[0104] A distillation pretreatment step to remove light components was proposed for the etherification solvent n-decane. This process effectively removes trace amounts of n-decane isomers from the solvent. These impurities are treated as heavy components during product distillation and need to be removed, leading to product yield loss. After pretreatment, the yield of the product distillation section is further improved, which is another key innovation for improving the overall yield.

[0105] 4) High yield and high purity

[0106] Mild reaction conditions and innovative purification process: This invention ensures high selectivity of the reaction and high purity of the product through mild reaction conditions and an innovative purification process. The overall yield from HCCP to PFPN is steadily increased from the industry average of <50% to over 70%, with a product purity consistently >99.9%, meeting the requirements of high-end lithium battery applications. This not only improves economic efficiency but also provides higher quality raw materials for downstream applications.

[0107] In summary, this invention relates to the field of organophosphorus nitrile compound synthesis technology, and specifically provides an integrated apparatus and method for producing high-purity ethoxypentafluorocyclotriphosphazene (PFPN) using hexachlorocyclotriphosphazene as the main raw material, through low-temperature fluorination, distillation and sublimation purification, low-temperature etherification, and high-efficiency refining. This product is mainly used as a flame retardant additive in lithium battery electrolytes. This invention significantly improves production efficiency, product quality, and safety, and has significant industrial application value.

[0108] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. An apparatus for preparing ethoxypentafluorocyclotriphosphazene, characterized in that, It includes a fluorination reaction system, a first solid-liquid separation system, an intermediate purification system, an etherification reaction system, a second solid-liquid separation system, a post-processing system, and a solvent recovery and product refining system connected in sequence. The fluorination reaction system includes a fluorination reactor with a cooling jacket, a stirrer, and a precision temperature control system. The first solid-liquid separation system includes a first filter for removing salt residue, a byproduct of the fluorination reaction; The intermediate purification system is an integrated distillation and sublimation purification device that combines a negative pressure distillation column, a low temperature sublimator, a rotary scraper system, and an HFP solid receiving tank. The etherification reaction system includes an etherification reactor equipped with a cryogenic jacket, a stirrer, and an ethoxy reagent dripping system; The second solid-liquid separation system includes a second filter for removing salt residue, a byproduct of the etherification reaction; The post-processing system includes a water washing tank with stirring function and a phase separation tank for static phase separation; The solvent recovery and product purification system includes a fluorinated solvent circulating distillation column, an etherified solvent circulating distillation column for etherified solvent distillation to remove light pretreatment, and a product distillation column in the form of a vacuum precision distillation column for product purification.

2. The apparatus for preparing ethoxypentafluorocyclotriphosphazene according to claim 1, characterized in that, In the fluorination reaction system, the solvent for the fluorination reaction is selected from ethylene glycol dimethyl ether; In the intermediate purification system, the absolute operating pressure of the negative pressure distillation column is 0.1–30 kPa, and the refrigerant temperature of the low-temperature sublimator is ≤0°C. In the etherification reaction system, the solvent for the etherification reaction is selected from n-decane.

3. The apparatus for preparing ethoxypentafluorocyclotriphosphazene according to claim 2, characterized in that, The product distillation column operates at an absolute pressure of <10 kPa and can output ethoxypentafluorocyclotriphosphazene with a purity of ≥99.9%.

4. The apparatus for preparing ethoxypentafluorocyclotriphosphazene according to claim 3, characterized in that, The water washing kettle is used to wash the filtrate after the etherification reaction with deionized water; The phase separation vessel is used to allow the washed material to stand and separate into layers in order to extract the organic phase.

5. A method for preparing ethoxypentafluorocyclotriphosphazene, using the preparation apparatus as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Fluorination reaction: Dissolve hexachlorocyclotriphosphazene in a fluorination solvent and put it into a fluorination reaction vessel. Add fluorination reagent under stirring and cooling conditions, control the reaction temperature at 0℃~60℃, and react for 6~15 hours. S2. Solid-liquid separation and intermediate purification: The reaction material in step S1 is filtered and desalted through the first filter. The filtrate is sent to the integrated distillation and sublimation purification equipment. Distillation is carried out under negative pressure to allow the hexafluorocyclotriphosphazene vapor to enter the low-temperature sublimator and condense into a solid, and high-purity hexafluorocyclotriphosphazene is collected. S3, Etherification reaction: Dissolve the hexafluorocyclotriphosphazene obtained in step S2 in an etherification solvent that has been pretreated by distillation to remove light content, transfer it to an etherification reactor, add ethoxy reagent under stirring and deep cooling conditions, control the reaction temperature at -30℃~20℃, and react for 4~10 hours. S4. Post-processing and product refining: The reaction material from step S3 is filtered through a second filter to remove salt. The filtrate is transferred to a water washing kettle for washing with deionized water, and then placed in a phase separation kettle for phase separation to extract the organic phase. The organic phase is then sequentially passed through an etherification solvent circulating distillation column to recover the solvent and a product distillation column to obtain ethoxypentafluorocyclotriphosphazene product.

6. The method for preparing ethoxypentafluorocyclotriphosphazene according to claim 5, characterized in that, In step S1, the fluorinating agent is selected from potassium fluoride or sodium fluoride.

7. The method for preparing ethoxypentafluorocyclotriphosphazene according to claim 6, characterized in that, In step S2, the absolute pressure of the negative pressure condition is 0.1 to 30 kPa, the temperature of the low-temperature sublimator is ≤0℃, and the yield of the collected hexafluorocyclotriphosphazene is >90%, and the purity is >96.0%.

8. The method for preparing ethoxypentafluorocyclotriphosphazene according to claim 7, characterized in that, In step S3, the etherification solvent is n-decane, and the ethoxylated reagent is selected from sodium ethoxide or ethanol.

9. The method for preparing ethoxypentafluorocyclotriphosphazene according to claim 8, characterized in that, In step S4, the deionized water washing is performed 3 times, and the ratio of deionized water volume to filtrate volume for each washing is 3:

10. The absolute operating pressure of the product distillation column is <10 kPa.

10. The method for preparing ethoxypentafluorocyclotriphosphazene according to claim 9, characterized in that, Based on hexachlorocyclotriphosphazene, the total yield of the ethoxypentafluorocyclotriphosphazene is >70%, and the product purity is ≥99.9%.

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