CN114917855B - Reaction system and method for continuously preparing perfluoroalkyl vinyl ether - Google Patents

Abstract

The invention discloses a reaction system and a method for continuously preparing perfluoroalkyl vinyl ether, wherein the reaction system comprises a salifying screw reactor for preparing carboxylate solution, a raw material recovery reactor for recovering unreacted acyl fluoride in the salifying screw reactor, and a decarboxylation screw reactor for decarboxylating carboxylate in the carboxylate solution, wherein a raw material recovery feed inlet of the raw material recovery reactor is connected with a first discharge outlet through a pipeline, and the raw material recovery reactor is also connected with a recovery tank for condensing and collecting unreacted raw materials; the reaction system also comprises a condenser, a product collecting tank and a bottom liquid collecting tank, wherein decarboxylation reaction occurs in the decarboxylation screw reactor, gas-phase products are collected in the product collecting tank through condensation of the product condenser, and liquid-solid mixed phase decarboxylation bottom liquid flows into the bottom liquid collecting tank through the pipeline. The invention can realize continuous salification and decarboxylation, has simple reaction operation steps and is easy for industrial production.

Description

A reaction system and method for continuously preparing perfluoroalkyl vinyl ether

Technical field

The invention belongs to the technical field of fluorine chemicals, and specifically relates to the technology for preparing perfluoroalkyl vinyl ether.

Background technique

Perfluoroalkyl vinyl ether is a widely used fluorine-containing monomer with the general formula:

Perfluoroalkyl vinyl ether has a large bond energy due to its C-F bond, which makes the π bond in its double bonds more relaxed and easy to polymerize with other monomers. Therefore, it is often used as a comonomer with tetrafluoroethylene monomer. Special functional polymer materials can be obtained by copolymerizing fluorine-containing olefins such as polymers. In addition, due to the copolymerization of perfluoroalkyl vinyl ether, flexible branches are introduced into the original polymer chain and the crystallinity of the polymer is reduced. Therefore, the polymerization can be improved without changing the original excellent properties of the fluoropolymer. Other properties of the material, such as: low temperature resistance, solvent resistance, toughness, tear resistance, bonding performance with the substrate, etc.

There are many methods for preparing perfluoroalkyl vinyl ether, which are mainly obtained by reacting acid fluorides with metal salt compounds to form carboxylates and then thermally cracking them to release CO ₂ and metal fluorides. The methods for preparing perfluoroalkyl vinyl ethers through salt-forming decarboxylation of acyl fluoride can be mainly divided into two categories:

The first type uses a one-step method, that is, the acid fluoride is directly decarboxylated with the metal carbonate in a reactor that is higher than the decarboxylation temperature of the intermediate carboxylate to obtain the alkenyl ether.

U.S. Patent No. 3321532 uses acyl fluoride and sodium carbonate to directly form salts for decarboxylation in a tubular reactor. The decarboxylation temperature is 300°C and the yield is up to 95%. U.S. Patent No. 3291843 also uses a tubular reactor. The acyl fluoride and silicon oxide are heated at 390°C. It is cracked into ether when it is broken down, and the yield is up to 85%; 3M Innovation Co., Ltd.'s Chinese patent CN101213168A uses acyl fluoride and metal carbonate in a stirred bed reactor for high-temperature decarboxylation. The decarboxylation temperature is 100-300°C, and the yield is about 70%. ; Asahi Glass Company's Chinese patent CN1196666C uses a method of high-temperature decarboxylation of acyl fluoride and metal carbonate in a fluidized bed. The conversion rate is 100%, but the yield is only 55%; Juhua Group's patent CN102702035B describes a method A method of continuously preparing fluorinated vinyl ether using a twin-screw extruder. The front stage of the twin-screw is formed into salt and the subsequent stage is decarboxylated. The temperature of the decarboxylation section is between 180°C and 320°C, and the highest conversion rate is 88.2%. It can be seen from the above patents that the yield of alkenyl ether prepared by one-step decarboxylation is not high. The main problem is that during the solid-phase decarboxylation process, the alkenyl ether product will react with the residual raw material acyl fluoride to form by-products, reducing the product yield; in addition , due to the high solid-phase decarboxylation temperature and uneven heating, it is easy to cause decomposition and carbonization of the alkylene ether products, leading to problems of carbon deposition and wall sticking. It will not only make the reactor difficult to clean, but also reduce the heat transfer effect of the reactor wall.

The second type uses a two-step method, including two-step solid phase decarboxylation and two-step liquid phase decarboxylation: the former refers to first treating the acid fluoride in a mixture of organic solvent and carbonate or sodium hydroxide, potassium hydroxide or sodium carbonate. React in an aqueous solution to form a salt, then remove the solvent to obtain a dry salt, and then directly decarboxylate the dry salt at high temperature to obtain an alkenyl ether product; the latter refers to using acyl fluoride to form a salt at low temperature in a mixture of solvent and carbonate, and then decarboxylating it at high temperature to obtain the product .

Zhonghao Chenguang Chemical Research Institute's patent CN101659602B uses a method of first removing the solvent and then solid-phase decarboxylation in a reactor or cracking furnace. The patent describes that this method can reduce the amount of hydrogen-containing by-products, and the product yield is less than 80%. ; Asahi Kasei Co., Ltd.'s Chinese patent CN100338013C reports a similar method of first desolvating salts and then solid-phase decarboxylation to prepare fluorine-containing vinyl ether; Shanghai Sanaifu New Materials Co., Ltd.'s patent CN102992969B discloses a method of producing fluorine-containing vinyl ether from acyl fluoride The process route of fluorovinyl ether and the cylindrical decarboxylation equipment with a scraper, that is, the acid fluoride is first salted, the solvent is removed, and then it is coated in the scraper barrel and heated for decarboxylation. The decarboxylation temperature is 120°C to 250°C. The product The yield can reach up to 96%. These schemes all belong to two-step solid-phase decarboxylation, which have common problems with solid-phase decarboxylation, that is, the decarboxylation temperature is high, side reactions are prone to occur, and the residues such as fluoride salts are difficult to clean. In addition, two-step solid-phase decarboxylation also has operational problems. Disadvantages of complexity and difficulty in solvent removal.

Patent CN101215225B of Zhonghao Chenguang Chemical Research Institute discloses a method in which organic amine is added as a catalyst in a polar solvent. Perfluoroalkoxypropionyl fluoride and carbonate form salts at low temperatures and are decarboxylated at 120°C to 160°C. A method for obtaining perfluoroalkyl vinyl ether has a yield of 92.3%. The patent CN103965023B of Sinochem Blue Sky Group Co., Ltd. uses perfluoroalkoxypropionyl fluoride and a salt-forming agent to form a salt at 20-80°C under the action of a catalyst, and decarboxylate it at 110-150°C to prepare the corresponding fluoroalkyl vinyl ether. , prepared under a small amount of laboratory conditions, the yield can reach up to 93.8%. The above solutions are all two-step liquid phase decarboxylation. They all use a one-pot reaction in a reactor. The solvent layer is thick. The decarboxylated product cannot quickly cross the solvent layer. If it stays in the solvent for a long time, it will interact with the alkenyl ether products and residues in the solvent. The acyl fluoride raw materials further react to form by-products. Moreover, when using this one-pot liquid-phase decarboxylation method, there are many intermittent operations and continuous production is not possible. In addition, the solvents and catalysts used in liquid-phase decarboxylation cannot be recycled, which has a great impact on the environment.

Contents of the invention

In view of the defects and shortcomings of the existing technology, the present invention provides a reaction system and method for continuously preparing perfluoroalkyl vinyl ether, which can continuously form salts and decarboxylate, and make the salt-forming and decarboxylation reactions more thorough.

On the one hand, a reaction system for continuously preparing perfluoroalkyl vinyl ether is provided, including a salt-forming screw reactor for preparing a carboxylate solution, a raw material recovery reactor for recovering unreacted acyl fluoride in the salt-forming screw reactor, and A decarboxylation screw reactor for decarboxylating carboxylates in carboxylate solutions, wherein,

The salt-forming screw reactor includes a first tubular shell arranged horizontally in the axial direction, and a first screw located in the first tubular shell. The first screw has blades distributed along the axial direction. The first tube The front part of the type housing is provided with a first feed port, and the rear part is provided with a first discharge port, a first exhaust port, and a first bottom drain port, and the first discharge port is located in the first pipe The upper middle side wall of the shell;

The raw material recovery inlet and the first outlet of the raw material recovery reactor are connected through a pipeline, and the raw material recovery reactor is also connected to a recovery tank for condensing and collecting unreacted raw materials;

The decarboxylation screw reactor includes a second tubular shell arranged axially horizontally and a second screw disposed in the second tubular shell. The second screw has blades distributed along the axial direction. The second tubular shell is arranged horizontally in the axial direction. The front part of the housing is provided with a second feed port, and the rear part is provided with a second discharge port, a second exhaust port, and a second bottom drain port, and the second discharge port is provided on the second pipe type The middle and lower side walls of the shell;

The raw material recovery outlet of the raw material recovery reactor is connected to the second feed port, so that the salt solution in the raw material recovery reactor is continuously sent to the decarboxylation screw reactor during the reaction process,

The reaction system also includes a condenser, a product collection tank, and a bottom liquid collection tank. The decarboxylation reaction occurs in the decarboxylation screw reactor. The gas phase product is condensed and collected in the product collection tank through the product condenser. The liquid-solid mixed phase decarboxylation bottom liquid passes through the pipeline. Flow into the bottom liquid collection tank.

Preferably, the blades are spiral blades or paddles.

Preferably, the distance between the outer edge of the blade and the inner wall of the tubular housing is 1-10 mm.

Preferably, the salt solution in the raw material recovery reactor is continuously sent to the decarboxylation screw reactor by a metering pump.

Preferably, the salt-forming screw reactor is provided with a first discharge lifting plate corresponding to the first discharge port.

Preferably, the decarboxylation screw reactor is provided with a second discharge lifting plate corresponding to the second discharge port.

On the other hand, a method for continuously preparing perfluoroalkyl vinyl ether is provided. The reaction system for continuously preparing perfluoroalkyl vinyl ether is used for continuous production, including the following steps:

1) Add solvent and salt-forming agent into the salt-forming screw reactor, and continuously feed acyl fluoride under stirring to cause a salt-forming reaction between the acyl fluoride and the salt-forming agent to generate the corresponding carboxylate. After the reaction is complete, continue to add Add solvent and salt-forming agent, and react continuously to obtain a carboxylate solution;

2) The carboxylate solution in the salt-forming screw reactor continuously flows into the raw material recovery reactor, and unreacted acyl fluoride is continuously recovered into the recovery tank under heating and stirring;

3) The carboxylate solution in the raw material recovery reactor is continuously pumped to the decarboxylation screw reactor. The decarboxylation reaction occurs under heating and stirring, and the perfluoroalkyl vinyl ether is obtained and condensed and collected in the product collection tank. The fluorine generated by decarboxylation The salt solids are sent into the bottom liquid collection tank along with the solvent.

Preferably, the solvent is one or two of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and N-methylpyrrolidone. The above combination; and/or, the salt-forming agent is one or a combination of two of potassium carbonate and sodium carbonate.

Preferably, the mass ratio of the acyl fluoride to the solvent participating in the reaction in the salt-forming screw reactor is 1:0.5-5; and/or the molar ratio of the acyl fluoride to the salt-forming agent is 1:1-2.

Preferably, the reaction temperature in the salt-forming screw reactor is 5°C to 40°C; and/or the reaction temperature in the decarboxylation screw reactor is 120°C to 180°C.

The present invention adopts the above technical solution and has the following beneficial effects:

The carboxylate solution is prepared in the salt-forming screw reactor. The raw material recovery reactor recovers unreacted acyl fluoride in the salt-forming screw reactor. The carboxylate solution in the raw material recovery reactor is continuously pumped to the decarboxylation screw reactor. The decarboxylation reaction occurs under heating and stirring, and the perfluoroalkyl vinyl ether is condensed and collected in the product collection tank. The fluoride salt solid generated by decarboxylation is sent to the bottom liquid collection tank along with the solvent. Therefore, salt formation and decarboxylation can be performed continuously, and the reaction operation steps are simple and easy for industrial production.

Different from conventional screw reactors, the screw reactor used in the present invention is provided with a discharge port at a specific height on the side and a corresponding discharge lifting plate, and the distance between the outer edge of the blade and the wall is required to be within a specified range;

First of all, the first discharge port is located in the upper middle part of the first tubular housing, and the second discharge port is located in the middle lower part of the second tubular housing. By setting the appropriate discharge port position, sufficient discharge port can be ensured. The reaction residence time makes the salt-forming and decarboxylation reactions more thorough; it can also keep the salt solution level in the decarboxylation screw reactor low to achieve thin-layer decarboxylation, reduce the residence time of the product in the solvent, reduce the production of by-products, and improve the purity of the product. .

Secondly, the salt-forming and decarboxylation screw reactors are equipped with stirring paddles or spiral blades, which can make the reaction occur under stirring and mixing, ensuring uniform heating (or heat dissipation) and sufficient reaction; and equipped with a discharge plate and a short The distance between the outer edge of the blade and the wall can allow the fluoride salt produced by the reaction to be discharged in time with the solvent without accumulating on the wall, preventing the fluoride salt from carbonizing in the reactor, and improving the problem of frequent disassembly and cleaning of the reactor.

In addition, using this decarboxylation screw reactor, the carboxylate solution can undergo continuous decarboxylation reaction under low-temperature heating and stirring. It can also carry out continuous low-temperature liquid phase decarboxylation reaction at a higher concentration of carboxylate solution to keep the product continuous. Discharging and continuously discharging the decarboxylation bottom liquid not only improves product purity and yield, reduces salt accumulation, but also has certain advantages in increasing output, and is suitable for industrial production.

The specific technical solutions and beneficial effects of the present invention will be described in detail in the following specific embodiments in conjunction with the accompanying drawings.

Description of the drawings

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

Figure 1 is a schematic structural diagram of a reaction system for continuously preparing perfluoroalkyl vinyl ether according to the present invention;

Figure 2 is a schematic structural diagram of the salt-forming screw reactor in the present invention;

Figure 3 is a schematic structural diagram of the first screw in the present invention;

Figure 4 is a schematic structural diagram of the decarboxylation screw reactor in the present invention;

Figure 5 is a schematic structural diagram of the second screw in the present invention;

Numbers in the figure: salt-forming screw reactor 1, feed pipe 10, feed pipe 2 11, feed pipe 3 12, pipe 1 13, pipe 2 14, pipe 3 15, pipe 4 16, pipe 5 17, pipe Six 18; raw material recovery reactor 2, first condenser 3, recovery tank 4, metering pump 5, decarboxylation screw reactor 6, bottom liquid collection tank 7, second condenser 8, product collection tank 9;

The first tubular housing 100, the first discharge port 112, the first condensate outlet 113, the first bottom drain port 114, the first steam outlet 115, the first exhaust port 116, the motor 120, and the first screw 130 , paddle-shaped blade 131, first discharging plate 132;

The second tubular housing 200, the second feed port 210, the second discharge port 212, the second condensed water outlet 213, the second bottom drain port 214, the second steam outlet 215, the second exhaust port 216, The second screw 230, the spiral blade 231, and the second discharging plate 232.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

As shown in Figures 1 to 5, a reaction system for continuously preparing perfluoroalkyl vinyl ether includes a salt-forming screw reactor 1 for preparing a carboxylate solution, and a salt-forming screw reactor 1 for recovering unreacted acyl fluoride. Raw material recovery reactor 2, decarboxylation screw reactor 6 for decarboxylating the carboxylate in the carboxylate solution, first condenser 3, second condenser 8, product collection tank 9, and bottom liquid collection tank 7.

As shown in Figures 2 and 3, the salt-forming screw reactor 1 includes a first tubular shell 100 arranged axially horizontally, and a first screw 130 disposed in the first tubular shell. The first screw 130 has blades distributed along the axial direction. The front part of the first tubular housing 100 is provided with a first feed port and a first condensed water outlet 113, and the rear part is provided with a first discharge port 112 and a first row. The air port 116 , the first bottom drain port 114 and the first steam outlet 115 , the first outlet 112 is provided on the upper middle side wall of the first tubular housing 100 .

As an embodiment, the blades provided on the first screw 130 are paddle-shaped blades 131 . The paddle blade 131 is made of welded round steel and includes a radial section and an axial section. The middle part of the axial section is connected to the outer end of the radial section, and the radial section and the axial section form a T shape. A total of four sets of paddle blades 131 are provided, distributed along the axial direction of the first screw 130, and the four sets of paddle blades 131 are distributed at 90-degree intervals in the circumferential direction of the first screw 130, of which two sets of paddle blades 131 are on the first screw. The axial positions of the other two sets of paddle blades 131 on the first screw correspond to each other and are distributed at 180-degree intervals along the circumferential direction. The above two sets of paddle blades 131 and the other two sets of paddle blades 131 are staggered in the axial direction on the first screw. Of course, the projections in the radial direction may partially overlap in the axial section.

Further, the distance between the edge of the paddle blade 131 and the inner wall of the first tubular housing 100 is 1-10 mm, preferably 5 mm. The first screw 130 is provided with a first discharge lifting plate 132 corresponding to the first discharge port 112 .

Among them, the first feed inlet is provided with feed pipe one 10, feed pipe two 11, and feed pipe three 12. Feed pipe one 10 introduces solvent into the salt-forming screw reactor 1, feed pipe two 11 introduces alkali metal carbonate into the salt-forming screw reactor 1, feed pipe three 12 introduces acid fluoride into the salt-forming screw reaction Device 1. The raw material recovery inlet and the first outlet 112 of the raw material recovery reactor 2 are connected through a pipeline 13. The raw material recovery reactor 2 is also connected to a recovery tank 4 for condensing and collecting unreacted raw materials. The first steam outlet 115 is connected to the second pipe 14, the second pipe 14 is connected to the first condenser 3, and the third pipe 15 is connected between the raw material recovery reactor 2 and the recovery tank 4. Acid fluoride and alkali metal carbonate react in the salt-forming screw reactor 1 to obtain a carboxylate solution. Under the action of the first discharge plate 132, it flows into the raw material recovery reactor 2 through pipeline 13. The unreacted acyl fluoride reacts in the salt-forming screw reactor 1 to obtain a carboxylate solution. The carbon dioxide produced along with the fluorine reaction passes through pipeline three 15, the condensate is collected in the recovery tank 4, and the carbon dioxide tail gas enters the tail gas absorption system for absorption treatment.

In addition, the other structure of the salt-forming screw reactor 1 refers to the existing tubular reactor, and is also provided with a motor 120, a reducer, a sealing component and a jacket outside the reactor. The motor 120 is connected to the reducer, and the output of the reducer The shaft is connected to the first screw 130 .

As shown in Figures 4 and 5, similar to the structure of the salt-forming screw reactor 1, the decarboxylation screw reactor 6 includes a second tubular shell 200 arranged horizontally in the axial direction. The second screw 230 in the body has blades distributed along the axial direction. The front part of the second tubular housing is provided with a second feed port 210 and a second condensate outlet 213, and the rear part is provided with There is a second discharge port 212, a second exhaust port 216, a second bottom drain port 214 and a second steam outlet 215. The second discharge port 212 is located at the middle and lower portion of the second tubular housing 200. side walls.

Wherein, the raw material recovery outlet of the raw material recovery reactor 2 is connected to the second feed port, so that the salt solution in the raw material recovery reactor 2 is continuously sent to the decarboxylation screw reactor 6 during the reaction process. The second steam outlet 215 is connected to the pipeline five 17 , and the pipeline five 17 is connected to the second condenser 8 . The second condenser 8 and the product collection tank 9 are connected through a pipe 618.

As an embodiment, the blades provided on the second screw 230 are spiral blades 231 and extend spirally along the axial direction of the second screw 230 . The distance between the edge of the spiral blade 231 and the inner wall of the second tubular housing 200 is 1-10 mm, preferably 5 mm. The second screw 230 is provided with a second discharge lifting plate 232 corresponding to the second discharge port 212 .

Furthermore, a connecting pipe and a metering pump 5 are provided between the raw material recovery outlet of the raw material recovery reactor 2 and the second feed port 210 of the decarboxylation screw reactor 6. The salt solution in the raw material recovery reactor 2 is continuously fed by the metering pump 5. Enter decarboxylation screw reactor 6.

When this reaction system is used, the raw materials are continuously put into the salt-forming screw reactor 1, and after stirring and reacting for a certain period of time, they are continuously discharged to the raw material recovery reactor 2. The stirring reaction time in the salt-forming screw reactor 1 is determined by the position of the outlet. Setting a reasonable outlet position can ensure that the salt-forming reaction is complete. In this embodiment, the first outlet 112 is located at the middle height position of the first tubular housing 100, and the distance between the first outlet 112 and the center line in the height direction of the first tubular housing is 1-10 cm, preferably 5 cm.

The carboxylate solution entering the raw material recovery reactor 2 is continuously pumped into the decarboxylation screw reactor 6 by the metering pump 5 while recovering the raw material acyl fluoride under stirring and heating. The reaction occurs under the heating of the reactor jacket of the decarboxylation screw reactor 6. Decarboxylation reaction yields gas phase products. The reaction residence time is determined by the position of the outlet. By setting the appropriate outlet position, the decarboxylation reaction can be ensured while keeping the salt solution level in the reactor low, achieving thin-layer decarboxylation and reducing by-products. In this embodiment, the second discharge port 212 is located at a lower height of the second tubular housing 200, and the distance between the second discharge port and the inner bottom wall of the second tubular housing is 1-20 cm, preferably 5 cm.

In addition, the fluoride salt solution produced by decarboxylation is spirally pushed by the second screw to the second discharge port. The second discharge port is connected to the pipe 416, and flows into the bottom liquid collection tank 7 under the action of the second discharge lifting plate to prevent Fluoride salt accumulates and forms walls inside the reactor. Finally, the crude product generated by the reaction is condensed and collected in the product collection tank 9 through the second condenser 8 .

The invention also relates to a method for preparing perfluoroalkyl vinyl ether using perfluoroalkoxy acid fluoride as raw material, continuous salt formation and decarboxylation:

1) Add an appropriate amount of solvent and salt-forming agent into the salt-forming screw reactor, pass low-temperature water into the reactor jacket, and continuously pass in the acid fluoride represented by the general formula (I) under stirring to mix it with the salt-forming agent. A salt-forming reaction occurs to generate the corresponding carboxylate (represented by general formula (ⅠⅠ)). After the reaction is complete, the solvent and salt-forming agent are continuously added in a certain proportion to continuously react to obtain a carboxylate solution. The CO ₂ generated simultaneously is The acyl fluoride is recovered by condensation and then enters the tail gas absorption system for absorption treatment;

2) The carboxylate solution in the salt-forming screw reactor continuously flows into the raw material recovery reactor under the action of the discharge plate, and the unreacted acyl fluoride is continuously recovered under stirring and heating to the recovery tank, and a certain amount is collected before proceeding. Reuse;

3) The carboxylate solution in the raw material recovery reactor is continuously pumped to the decarboxylation screw reactor, and the decarboxylation reaction occurs under heating and stirring to obtain the perfluoroalkyl vinyl ether represented by formula (III), which is condensed and collected in the product collection In the tank, the fluoride salt solid generated by decarboxylation is sent to the bottom liquid collection tank through the discharge plate along with the solvent. It is desalted by centrifugation and reused. The relevant reaction formula is as follows:

Among them, M is an alkali metal atom; n=0,1,2.

The solvent is one or a combination of two or more of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and N-methylpyrrolidone, Tetraethylene glycol dimethyl ether is preferred.

The salt-forming agent is one or a combination of two of potassium carbonate and sodium carbonate, preferably potassium carbonate.

The mass ratio of the acyl fluoride and the solvent participating in the reaction in the salt-forming screw reactor is 1:0.5-5, preferably 1:0.5-2, and the molar ratio of the acyl fluoride to the salt-forming agent is 1:1-2, preferably 1: 1.05～1.25; the salt-forming reaction temperature is 5℃～40℃, preferably 15℃～30℃; the acid fluoride recovery temperature is 60℃～100℃, preferably 80℃～90℃; the heating decarboxylation temperature is 120℃～180℃, The temperature is preferably 120°C to 140°C. In addition, the position of the outlet can be set to maintain the liquid level of the carboxylate solution in the decarboxylation screw reactor at 1-20cm, preferably 5-15cm.

The present invention will be further described below in conjunction with the examples.

Example 1:

Add 10kg of solvent diethylene glycol dimethyl ether and 3.5kg of anhydrous sodium carbonate into the salt-forming screw reactor, start stirring, and add the raw material perfluoro (2-methyl-3-oxahexyl) fluoride at 10kg/ H is continuously pumped into the salt-forming screw reactor, and the two undergo a salt-forming reaction in the salt-forming screw reactor. The reaction temperature is controlled to 30°C and the reaction time is 1 hour. After the reaction is completed, diethylene glycol dimethyl ether is continuously added at a rate of 10kg/h, and anhydrous sodium carbonate is continuously added at a rate of 3.5kg/h;

After the obtained sodium carboxylate solution reaches the outlet position, it will continue to flow into the raw material recovery reactor under the action of the discharging plate. The raw material recovery reactor will be started for stirring. The temperature is controlled to 80°C. The unreacted acid fluoride will be condensed through recovery. The containers are collected in recycling tanks;

The sodium carboxylate solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor at a speed of 20kg/h by a metering pump. The decarboxylation reaction occurs in the decarboxylation screw reactor. The reaction temperature is 130°C. The crude product generated by the reaction passes through the condenser. Condensation is collected in the product collection tank.

A total of 5 hours of feeding, 50kg of perfluoro (2-methyl-3-oxahexyl) fluoride, of which 2.6kg of acid fluoride was recovered, and 35.2kg of crude perfluoro-n-propyl vinyl ether product, of which perfluoro-n-propyl Vinyl ether content is 96.25%. The product yield of perfluoro-n-propyl vinyl ether is 89.21%.

Example 2:

Add 10kg of solvent diethylene glycol dimethyl ether and 3.5kg of anhydrous sodium carbonate into the salt-forming screw reactor, start stirring, and add the raw material perfluoro (2-methyl-3-oxahexyl) fluoride at 10kg/ H is continuously pumped into the salt-forming screw reactor, and the two undergo a salt-forming reaction in the salt-forming screw reactor. The reaction temperature is controlled to 15°C and the reaction time is 1 hour. After the reaction is completed, diethylene glycol dimethyl ether is continuously added at a rate of 10kg/h, and anhydrous sodium carbonate is continuously added at a rate of 3.5kg/h;

After the obtained sodium carboxylate solution reaches the outlet position, it will continue to flow into the raw material recovery reactor under the action of the discharging lifting plate. The raw material recovery reactor is started for stirring. The temperature is controlled at 90°C. The unreacted acid fluoride is recovered and condensed. The containers are collected in recycling tanks;

The sodium carboxylate solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor at a speed of 20kg/h by a metering pump. A decarboxylation reaction occurs in the decarboxylation screw reactor. The reaction temperature is 130°C. The crude product generated by the reaction passes through the condenser. Condensation is collected in the product collection tank.

Feeding for a total of 5 hours, 50kg of perfluoro(2-methyl-3-oxahexyl) fluoride was added, of which 3.1kg of acid fluoride was recovered, and 35.6kg of perfluoro-n-propyl vinyl ether crude product was collected, of which 35.6kg of perfluoro-n-propyl vinyl ether was collected. Vinyl ether content is 95.72%. The product yield of perfluoro-n-propyl vinyl ether is 90.69%.

Example 3:

Add 10kg of solvent tetraethylene glycol dimethyl ether and 3.5kg of anhydrous sodium carbonate into the salt-forming screw reactor, start stirring, and add the raw material perfluoro (2-methyl-3-oxahexyl) fluoride at 10kg/ H is continuously pumped into the salt-forming screw reactor, and the two undergo a salt-forming reaction in the salt-forming screw reactor. The reaction temperature is controlled to 30°C and the reaction time is 1 hour. After the reaction is completed, tetraethylene glycol dimethyl ether is continuously added at a rate of 10kg/h, and anhydrous sodium carbonate is continuously added at a rate of 3.5kg/h;

After the obtained sodium carboxylate solution reaches the outlet position, it will continue to flow into the raw material recovery reactor under the action of the discharging lifting plate. The raw material recovery reactor is started for stirring. The temperature is controlled at 90°C. The unreacted acid fluoride is recovered and condensed. The containers are collected in recycling tanks;

The sodium carboxylate solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor at a speed of 20kg/h by a metering pump. A decarboxylation reaction occurs in the decarboxylation screw reactor. The reaction temperature is 140°C. The crude product generated by the reaction passes through the condenser. Condensation is collected in the product collection tank.

A total of 5 hours of feeding, 50kg of perfluoro (2-methyl-3-oxahexyl) fluoride, of which 2.4kg of acid fluoride was recovered, and 36.2kg of crude perfluoro-n-propyl vinyl ether product, of which perfluoro-n-propyl Vinyl ether content is 95.11%. The product yield of perfluoro-n-propyl vinyl ether is 90.28%.

Example 4:

Add 10kg of solvent tetraethylene glycol dimethyl ether and 4.5kg of anhydrous potassium carbonate into the salt-forming screw reactor, start stirring, and add the raw material perfluoro(2-methyl-3-oxahexyl) fluoride at 10kg/ H is continuously pumped into the salt-forming screw reactor, and the two undergo a salt-forming reaction in the salt-forming screw reactor. The reaction temperature is controlled to 30°C and the reaction time is 1 hour. After the reaction is completed, tetraethylene glycol dimethyl ether is continuously added at a rate of 10kg/h, and anhydrous potassium carbonate is continuously added at a rate of 4.5kg/h;

After the obtained potassium carboxylate solution reaches the outlet position, it will continue to flow into the raw material recovery reactor under the action of the discharge plate. The raw material recovery reactor will be started for stirring. The temperature will be controlled at 90°C. The unreacted acyl fluoride will be condensed through recovery. The containers are collected in recycling tanks;

The potassium carboxylate solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor at a speed of 20kg/h by a metering pump. A decarboxylation reaction occurs in the decarboxylation screw reactor. The reaction temperature is 140°C. The crude product generated by the reaction passes through the condenser. Condensation is collected in the product collection tank.

A total of 5 hours of feeding, 50kg of perfluoro (2-methyl-3-oxahexyl) fluoride, of which 2.3kg of acid fluoride was recovered, and 36.5kg of crude perfluoro-n-propyl vinyl ether product, of which perfluoro-n-propyl Vinyl ether content is 96.78%. The product yield of perfluoro-n-propyl vinyl ether is 92.43%.

Example 5:

Add 10kg of solvent tetraethylene glycol dimethyl ether and 3.0kg of anhydrous potassium carbonate into the salt-forming screw reactor, start stirring, and mix the raw material 2,5-bis(trifluoromethyl)-3,6-dioxa Undecafluorononanoyl fluoride is continuously pumped into the salt-forming screw reactor at a speed of 10kg/h. The two undergo a salt-forming reaction in the salt-forming screw reactor. The reaction temperature is controlled to 30°C and the reaction time is 1 hour. After the reaction is completed, diethylene glycol dimethyl ether is continuously added at a rate of 10kg/h, and anhydrous potassium carbonate is continuously added at a rate of 3.0kg/h;

After the obtained potassium carboxylate solution reaches the discharge port, it will continue to flow into the raw material recovery reactor under the action of the discharge plate. The raw material recovery reactor will be started for stirring. The temperature is controlled to 80°C. The unreacted acyl fluoride will be condensed through recovery. The containers are collected in recycling tanks;

The potassium carboxylate solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor at a speed of 20kg/h by a metering pump. A decarboxylation reaction occurs in the decarboxylation screw reactor. The reaction temperature is 140°C. The crude product generated by the reaction passes through the condenser. Condensation is collected in the product collection tank.

A total of 5 hours of feeding, 50kg of raw material 2,5-bis(trifluoromethyl)-3,6-dioxaundecanoyl fluoride, 1.1kg of acyl fluoride, and 2-(heptafluoropropoxy) ) The yield of hexafluoropropyl trifluorovinyl ether was 39.7kg of crude product, in which the content of 2-(heptafluoropropoxy)hexafluoropropyl trifluorovinyl ether was 93.81%. The yield of 2-(heptafluoropropoxy)hexafluoropropyl trifluorovinyl ether is 87.80%.

Example 6:

Add 10kg of solvent tetraethylene glycol dimethyl ether and 4.5kg of anhydrous potassium carbonate into the salt-forming screw reactor, start stirring, and add the raw material perfluoro(2-methyl-3-oxahexyl) fluoride at 10kg/ H is continuously pumped into the salt-forming screw reactor, and the two undergo a salt-forming reaction in the salt-forming screw reactor. The reaction temperature is controlled to 30°C and the reaction time is 1 hour. After the reaction is completed, tetraethylene glycol dimethyl ether is continuously added at a rate of 10kg/h, and anhydrous potassium carbonate is continuously added at a rate of 4.5kg/h;

After the obtained potassium carboxylate solution reaches the outlet position, it will continue to flow into the raw material recovery reactor under the action of the discharge plate. The raw material recovery reactor will be started for stirring. The temperature will be controlled at 90°C. The unreacted acyl fluoride will be condensed through recovery. The containers are collected in recycling tanks;

The potassium carboxylate solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor at a speed of 20kg/h by a metering pump. A decarboxylation reaction occurs in the decarboxylation screw reactor. The reaction temperature is 140°C. The crude product generated by the reaction passes through the condenser. Condensation is collected in the product collection tank.

Continuous day shift feeding for one month, a total of 2330.5kg of perfluoro (2-methyl-3-oxahexyl) fluoride was input, of which 101.2kg of acyl fluoride was recovered (90kg has been reused in the system, and the remaining 11.2kg is collected in the recovery tank ), 1785.8kg of perfluoro-n-propyl vinyl ether crude product was collected, in which the content of perfluoro-n-propyl vinyl ether was 96.10%. The product yield of perfluoro-n-propyl vinyl ether is 92.07%. Disassemble the reactor and observe inside the reactor. Except for a small amount of salt-containing solution, there is basically no salt accumulation and wall formation.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the above specific embodiments. Any modifications that do not depart from the functional and structural principles of the invention are intended to be included in the scope of the claims.

Claims (4)

1. A reaction system for continuously preparing perfluoroalkyl vinyl ether, which is characterized in that it includes a salt-forming screw reactor for preparing a carboxylate solution, and a raw material recovery reactor for recovering unreacted acyl fluoride in the salt-forming screw reactor. and a decarboxylation screw reactor for decarboxylating carboxylates in carboxylate solutions, wherein, The salt-forming screw reactor includes a first tubular shell arranged horizontally in the axial direction, and a first screw located in the first tubular shell. The first screw has blades distributed along the axial direction. The first tube The front part of the type housing is provided with a first feed port, and the rear part is provided with a first discharge port, a first exhaust port, and a first bottom drain port, and the first discharge port is located in the first pipe The upper middle side wall of the shell; The raw material recovery inlet and the first outlet of the raw material recovery reactor are connected through a pipeline, and the raw material recovery reactor is also connected to a recovery tank for condensing and collecting unreacted raw materials; The decarboxylation screw reactor includes a second tubular shell arranged axially horizontally and a second screw disposed in the second tubular shell. The second screw has blades distributed along the axial direction. The second tubular shell is arranged horizontally in the axial direction. The front part of the housing is provided with a second feed port, and the rear part is provided with a second discharge port, a second exhaust port, and a second bottom drain port, and the second discharge port is provided on the second pipe type The middle and lower side walls of the shell; The raw material recovery outlet of the raw material recovery reactor is connected to the second feed port, so that the salt solution in the raw material recovery reactor is continuously sent to the decarboxylation screw reactor during the reaction process, The reaction system also includes a condenser, a product collection tank, and a bottom liquid collection tank. The decarboxylation reaction occurs in the decarboxylation screw reactor. The gas phase product is condensed and collected in the product collection tank through the product condenser. The liquid-solid mixed phase decarboxylation bottom liquid passes through the pipeline. Flow into the bottom liquid collection tank; The distance between the outer edge of the blade and the inner wall of the tubular shell is 1-10 mm. The salt-forming screw reactor is provided with a first discharge plate corresponding to the first discharge port. The decarboxylation screw reactor is corresponding to the first discharge port. The second discharge port is provided with a second discharge lifting plate; Using the above reaction system for continuous production includes the following steps: 1) Add solvent and salt-forming agent into the salt-forming screw reactor, and continuously introduce acyl fluoride under stirring. The mass ratio of acyl fluoride to solvent is 1:0.5~5, and the molar ratio of acyl fluoride to salt-forming agent is 1:1~2, control the reaction temperature between 5~40℃, make the salt-forming reaction between the acyl fluoride and the salt-forming agent occur, and generate the corresponding carboxylate. After the reaction is complete, continue to add the solvent and salt-forming agent, and the carboxylic acid salt is obtained through the continuous reaction. acid salt solution; 2) The carboxylate solution in the salt-forming screw reactor continuously flows into the raw material recovery reactor, and unreacted acyl fluoride is continuously recovered into the recovery tank under heating and stirring; 3) The carboxylate solution in the raw material recovery reactor is continuously pumped to the decarboxylation screw reactor, and the decarboxylation reaction occurs under heating and stirring. The reaction temperature is 120~180°C, and the perfluoroalkyl vinyl ether is condensed and collected. In the product collection tank, the fluoride salt solid generated by decarboxylation is sent to the bottom liquid collection tank along with the solvent. 2. A reaction system for continuously preparing perfluoroalkyl vinyl ether according to claim 1, characterized in that: the blades are spiral blades or paddles. 3. A reaction system for continuously preparing perfluoroalkyl vinyl ether according to claim 1, characterized in that the salt solution in the raw material recovery reactor is continuously fed into the decarboxylation screw reactor by a metering pump. 4. A reaction system for continuously preparing perfluoroalkyl vinyl ether according to claim 1, characterized in that: the solvent is diethylene glycol dimethyl ether, diethylene glycol diethyl ether, or triethylene glycol dimethyl ether. One or more combinations of glycol dimethyl ether, tetraethylene glycol dimethyl ether and N-methylpyrrolidone; and/or the salt-forming agent is one or two of potassium carbonate and sodium carbonate. combination.