Full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane

Abstract

The present application discloses a full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, including a telomerization reaction: vinyl chloride, carbon tetrachloride, catalyst 1 and a cocatalyst are added to a pre-reactor mixer for premixing to obtain mixture 1, mixture 1 is pumped into a reactor system for telomerization reaction to obtain the material of the telomerization reaction, the material of the telomerization reaction is continuously pumped out and separated to obtain R240fa, and the separated vinyl chloride, carbon tetrachloride, catalyst 1, cocatalyst and unseparated R240fa are returned to the pre-reactor mixer for continuous reaction; a fluorination reaction: the R240fa, chlorine gas and anhydrous hydrogen fluoride obtained from the telomerization reaction are continuously introduced into a fluorination reaction kettle containing activated catalyst 2 for fluorination reaction to obtain a fluorination reaction product, the fluorination reaction product is separated to obtain 1,1,1,3,3-pentafluoropropane, and the remaining product after separating 1,1,1,3,3-pentafluoropropane is returned to the fluorination reaction kettle for continuous reaction.

Description

Technical Field

[0001] The present application relates to the technical field of 1,1,1,3,3-pentafluoropropane, and specifically provides a full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane. Background Art

[0002] At present, the industrial production of 1,1,1,3,3-pentafluoropropane mainly uses 1,1,1,3,3-pentachloropropane (R240fa) as the raw material through two major categories: liquid-phase fluorination method or gas-phase fluorination method. For example, Patent CN101913983B discloses a method for preparing R245fa by liquid-phase fluorination, and Patent CN103214342B discloses a method for synthesizing R245fa by two-step gas-phase fluorination under the action of a chromium-based catalyst.

[0003] With the continuous technological improvement of each production enterprise, the above-mentioned R245fa preparation process has become increasingly mature. However, inevitably, there are still impurities such as R11, R12, R13, R114, R115, R113, 244fa, etc. in the product, which are other first-generation, second-generation, and third-generation refrigerant impurities. The generation of the above impurities mainly comes from the fluorination reaction of the substance R240fa, and a small part also comes from the impurities in the raw material R240fa. For example, the impurity hexachloroethane is generated during the production process of R240fa. However, due to its boiling point being close to that of R240fa, it is difficult to separate by conventional distillation, and inevitably affects the product quality. Although the content of the above impurities mostly only remains between dozens and hundreds of ppm, with the continuous implementation of relevant international agreements, there are also higher standards for the product quality of R245fa, and the content requirements for relevant impurities have become increasingly stringent. At present, the products for some uses require zero detection of first-generation refrigerant impurities. It can be foreseen that in the future, the content requirements for second-generation and third-generation refrigerant impurities in the product will also be put on the agenda. In view of the above problems, there is still much work to be considered and studied to optimize and improve the production process of high-quality R245fa. Summary of the Invention

[0004] The present application provides a full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, which has the advantages of high reaction yield, high product quality, good production safety, less pollution emissions, and can achieve full-process continuous production and automatic control.

[0005] The technical solution adopted by the present application to solve its technical problems is: to provide a full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, and the synthesis route is as follows.

[0006]

[0007] The synthesis process specifically includes:

[0008] Telomerization reaction: Vinyl chloride, carbon tetrachloride, catalyst I and cocatalyst are added to the pre-mixer before the reactor in a molar ratio of 1:0.8 - 3:0.01 - 0.1:0.01 - 0.2 to obtain mixture I. Mixture I is pumped into the reactor system at a rate of 600 - 2000 kg / h. Telomerization reaction is carried out at a reaction pressure of 0.3 - 1.0 MPa and a reaction temperature of 60 - 150 °C to obtain the materials of the telomerization reaction. The materials of the telomerization reaction are continuously pumped out and separated to obtain R240fa. When separating R240fa, the separated vinyl chloride, carbon tetrachloride, catalyst I, cocatalyst and unseparated R240fa are returned to the pre-mixer before the reactor for continuous reaction;

[0009] Fluorination reaction: Using the liquid-phase fluorination method, R240fa, chlorine gas and anhydrous hydrogen fluoride obtained from the above telomerization reaction are continuously introduced into the fluorination reaction kettle containing catalyst II activated by known technology in a molar ratio of 1:0.0001 - 0.0005:5 - 6. The molar ratio of the hourly feed rate of R240fa to catalyst II and the amount of hydrogen fluoride in the fluorination reaction kettle is 1:0.1 - 5:10 - 100. Fluorination reaction is carried out at a reaction pressure of 0.4 - 1.0 MPa and a reaction temperature of 60 - 150 °C to obtain the fluorination reaction product. After separating the fluorination reaction product to obtain 1,1,1,3,3-pentafluoropropane, when separating 1,1,1,3,3-pentafluoropropane, the remaining product after separating 1,1,1,3,3-pentafluoropropane from the fluorination reaction product is returned to the fluorination reaction kettle for continuous reaction.

[0010] In this continuous process for the synthesis of 1,1,1,3,3-pentafluoropropane, hydrogen fluoride is used to activate the catalyst, and at the same time, hydrogen fluoride also acts as a fluorination reagent and a solvent to dissolve the fluorination catalyst. To ensure the catalytic effect of the fluorination catalyst, there are certain requirements for the ratio of the hourly feed rate of R240fa, the fluorination catalyst and the hydrogen fluoride in the fluorination reaction kettle. If the ratio is too large, the production capacity is limited; if the ratio is too small, the catalyst cannot be fully dissolved, which also affects the reaction efficiency. Therefore, in the present invention, the molar ratio of the hourly feed rate of R240fa to catalyst II and the amount of hydrogen fluoride in the fluorination reaction kettle is 1:0.1 - 5:10 - 100;

[0011] In the present invention, the main function of chlorine gas is to maintain the catalytic activity of the fluorination catalyst. However, due to the one-step continuous liquid-phase fluorination method adopted in the present invention, a small amount of olefin intermediate products such as trifluorochloropropene and tetrafluoropropene will be generated during the process. If the content of chlorine gas is too high, side reaction impurities may be generated with these olefins, and if the content is too low, the activity of the catalyst cannot be maintained. Therefore, to ensure high-quality fluorinated products in the fluorination reaction, the feed rate of continuously fed chlorine gas needs to be strictly controlled. In the present invention, R240fa, chlorine gas, and anhydrous hydrogen fluoride are continuously introduced into the fluorination reactor containing the activated catalyst II in a molar ratio of 1:0.0001 - 0.0005:5 - 6.

[0012] Since the boiling point of chlorine gas is -34°C, which is close to the boiling points of the olefin intermediate products, and the amount of chlorine gas used is small, it is difficult to separate by distillation technology, which may cause the cumulative increase of the chlorine gas content in the recycled light-component materials, resulting in the decline of product quality; or in order to ensure the complete separation of chlorine gas, the separation capacity of the fluorination continuous separation system is limited, affecting the production capacity of the entire continuous process. Considering the above reasons, a continuous water washing and alkali washing tower is provided before the light components returning to the reaction system in the present invention to remove chlorine gas, realizing an efficient continuous separation process.

[0013] Preferably, in the telomerization reaction, the reactor system is a CSTR. When separating R240fa, the materials of the telomerization reaction are pumped into the light-component tower of the 240 continuous separation system by the 240 continuous separation system to separate vinyl chloride and carbon tetrachloride. The separated vinyl chloride and carbon tetrachloride are returned to the pre-reactor mixer to continue the reaction. The bottom materials of the light-component tower enter the 240 tower of the 240 continuous separation system for distillation separation. R240fa is separated from the top of the 240 tower, and vinyl chloride, carbon tetrachloride, catalyst I, co-catalyst, and unseparated R240fa at the bottom of the 240 tower are returned to the pre-reactor mixer to continue the reaction.

[0014] Preferably, in the telomerization reaction, the 240 continuous separation system further includes a heavy-component tower. The heavy-component tower is connected to the 240 tower. R240fa is separated from the top of the heavy-component tower. The heavy-component tower is used for the separation of high-boiling butane compounds and deactivated catalysts and co-catalysts that may accumulate during long-term continuous reactions.

[0015] Preferably, in the fluorination reaction, when separating 1,1,1,3,3-pentafluoropropane, the fluorination reaction product is introduced into a hydrogen chloride tower. Hydrogen chloride is separated from the top of the hydrogen chloride tower. The bottom material of the hydrogen chloride tower is introduced into a hydrogen fluoride tower. The light components containing R245fa separated from the top of the hydrogen fluoride tower sequentially enter a water washing tower and an alkali washing tower. The bottom material of the hydrogen fluoride tower is returned to the fluorination reaction kettle for re-reaction. After the hydrogen fluoride and chlorine in the light components containing R245fa are removed in the alkali washing tower, the product is introduced into a dehydrogenation tower. The light components containing R1234ze separated from the top of the dehydrogenation tower are returned to the fluorination reaction kettle for continuous reaction. After the bottom material of the dehydrogenation tower is rectified in a 245 tower, the top product of the 245 tower is introduced into a drying tower, and the product is dried in the drying tower to obtain 1,1,1,3,3-pentafluoropropane. The bottom material of the 245 tower is returned to the fluorination reaction kettle for continuous reaction.

[0016] Preferably, the CSTR includes three series-connected telomerization kettles. The capacity of the telomerization kettle is 2000 - 5000L. There are no special requirements for the material of the telomerization kettle, and ordinary steel-lined enamel material can be used.

[0017] Preferably, the first catalyst is at least one of iron, zinc, ferrous chloride or cuprous chloride.

[0018] Preferably, the cocatalyst is an alkyl phosphate or an alkyl phosphite.

[0019] Preferably, the reaction temperature of the telomerization reaction is 80 - 140°C, and the reaction pressure is 0.4 - 0.8 MPa.

[0020] Preferably, the reaction temperature of the fluorination reaction is 80 - 120°C, and the reaction pressure is 0.5 - 0.8 MPa.

[0021] Preferably, the second catalyst is one of antimony trichloride, antimony pentachloride, tin tetrachloride or titanium tetrachloride.

[0022] The substantial effects of this application are:

[0023] 1. This full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane uses CSTR technology to achieve synchronous and efficient mass transfer and heat transfer in the radial and circumferential directions. Compared with traditional synthesis technologies, it has more excellent mass transfer and heat transfer effects. Moreover, due to the short residence time of the reaction materials in the reaction stage in CSTR technology, there are fewer reaction by-products, the product separation is simple, the product quality is high, and the product yield is good;

[0024] 2. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane adopts the CSTR technology. Compared with the traditional batch production, in which mass transfer and heat transfer are achieved only by stirring inside the reaction kettle, the reaction heat generated instantaneously when vinyl chloride contacts carbon tetrachloride is difficult to effectively remove, resulting in the situation that the local materials in the kettle overheat far beyond the process temperature. And too high reaction temperature will lead to the generation of a larger amount and more types of by-products in this reaction, so more complex equipment and more stringent separation conditions are required to obtain high-purity products. The CSTR technology adopts the design of continuous multi-stage series stirring kettles, which realizes heat and material transfer in the radial direction of the material transfer pipeline synchronously in addition to the circumferential mass transfer and heat transfer inside the reaction kettle. At the same time, with the setting of continuous multi-stage kettles, smaller reaction kettles can be selected under the same production capacity, reducing the influence of the scale-up effect, obtaining purer reaction products, and reducing the subsequent separation difficulty;

[0025] 3. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane realizes the full-process continuous production process from raw material feeding, reaction to product separation. The whole process can be automatically controlled, the production cost is greatly reduced, the production capacity is greatly improved, the reaction process is safe and reliable, the pollution emission is less, and it is friendly to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic process flow diagram of the full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane in this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] As Figure 1 shown, the full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane in this application includes:

[0028] Telomerization reaction: Vinyl chloride, carbon tetrachloride, catalyst I and cocatalyst are added to the pre-mixer before the kettle in a molar ratio of 1:0.8 - 3:0.01 - 0.1:0.01 - 0.2 to obtain mixture I. Catalyst I is at least one of iron, zinc, ferrous chloride or cuprous chloride, and the cocatalyst is an alkyl phosphate or an alkyl phosphite. Mixture I is pumped into three series-connected telomerization kettles at a rate of 600 - 2000 kg / h. The capacity of the telomerization kettle is 2000 - 5000 L. The telomerization reaction is carried out at a reaction pressure of 0.3 - 1.0 MPa and a reaction temperature of 60 - 150 °C to obtain the material of the telomerization reaction. The material of the telomerization reaction is continuously pumped out and separated to obtain R240fa. When separating R240fa, the material of the telomerization reaction is pumped into the light component tower of the 240 continuous separation system by the 240 continuous separation system to separate vinyl chloride and carbon tetrachloride. The separated vinyl chloride and carbon tetrachloride are returned to the pre-mixer before the kettle for continuous reaction. The bottom material of the light component tower enters the 240 tower of the 240 continuous separation system for rectification separation. R240fa is separated from the top of the 240 tower. The vinyl chloride, carbon tetrachloride, catalyst I, cocatalyst and unseparated R240fa at the bottom of the 240 tower are returned to the pre-mixer before the kettle for continuous reaction. The 240 continuous separation system also includes a heavy component tower. The heavy component tower is connected to the 240 tower for separating the butane-based high-boiling substances, inactivated catalyst and cocatalyst that may accumulate during long-term continuous reaction. R240fa is separated from the top of the heavy component tower;

[0029] Fluorination reaction: Using the liquid-phase fluorination method, R240fa, chlorine gas, and anhydrous hydrogen fluoride obtained from the above telomerization reaction are continuously introduced into a fluorination reaction kettle containing the activated catalyst II at a molar ratio of 1:0.0001 - 0.0005:5 - 6. The catalyst II is one of antimony trichloride, antimony pentachloride, tin tetrachloride, or titanium tetrachloride. The molar ratio of the hourly feed rate of R240fa to the amount of catalyst II and hydrogen fluoride in the fluorination reaction kettle is 1:0.1 - 5:10 - 100. The fluorination reaction is carried out at a reaction pressure of 0.4 - 1.0 MPa and a reaction temperature of 60 - 150 °C to obtain a fluorination reaction product. The fluorination reaction product is separated to obtain 1,1,1,3,3-pentafluoropropane. When separating 1,1,1,3,3-pentafluoropropane, the fluorination reaction product is introduced into a hydrogen chloride tower. Hydrogen chloride is separated from the top of the hydrogen chloride tower. The bottom material of the hydrogen chloride tower is introduced into a hydrogen fluoride tower. The light components containing R245fa are separated from the top of the hydrogen fluoride tower and sequentially enter a water washing tower and an alkali washing tower. The bottom material of the hydrogen fluoride tower is returned to the fluorination reaction kettle for re-reaction. After the alkali washing tower removes hydrogen fluoride and chlorine gas from the light components containing R245fa, the product is introduced into a dehydrogenation tower. The light components containing R1234ze are separated from the top of the dehydrogenation tower and returned to the fluorination reaction kettle for continuous reaction. The bottom material of the dehydrogenation tower is introduced into a 245 tower for rectification. The top product of the 245 tower is introduced into a drying tower. The drying tower dries the product to obtain 1,1,1,3,3-pentafluoropropane. The bottom material of the 245 tower is returned to the fluorination reaction kettle for continuous reaction.

[0030] The following are specific examples to further illustrate the technical solutions of the present application.

[0031] Example 1

[0032] A full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane includes:

[0033] Telomerization reaction: Carbon tetrachloride, vinyl chloride, iron powder, and tributyl phosphate were premixed in a pre-mixer in front of the kettle at a mass ratio of 300:50:1:6, and then pumped into the CSTR reaction system. The total feed flow rate was 1800 kg / h. The size of the telomerization reactor was 5000 L, the reaction temperature was 90 - 100 °C, and the reaction pressure was 0.6 ± 0.1 MPa. After the materials reacted in the CSTR reaction system, they were continuously pumped out to the 240 continuous separation system. In the light component tower, light components such as vinyl chloride and carbon tetrachloride were separated and returned to the pre-mixer in front of the kettle for continued reaction. The bottom materials of the tower went to the 240 tower for rectification and separation. The top product R240fa was used for the fluorination reaction. The bottom heavy components, including a small amount of unseparated R240fa, iron powder, and tributyl phosphate mixture, were pumped back to the pre-mixer in front of the kettle for cyclic reaction. About 12 h after feeding, the flow rates of the cyclic materials, R240fa extraction materials, etc. were stable. At this time, the flow rate of R240fa for the fluorination reaction was about 860 kg / h. The feed materials were adjusted to 620 kg / h of carbon tetrachloride and 250 kg / h of vinyl chloride to keep the materials in the whole system in dynamic equilibrium;

[0034] Fluorination reaction: 1000 kg of the catalyst antimony trichloride was put into the fluorination reactor, and 5000 kg of anhydrous hydrogen fluoride was pumped in. After pre-activating antimony trichloride, it was kept at 80 - 90 °C for heat preservation, waiting for the output of the telomerization reaction to carry out the fluorination reaction. The R240fa, chlorine gas, and anhydrous hydrogen fluoride obtained from the telomerization reaction were introduced into the fluorination reactor at a molar ratio of 1:0.0001 - 0.0005:5 - 6. After the telomerization reaction stably discharged materials, the feed flow rates of each material were 860 kg / h of R240fa, 0.1 kg / h of chlorine gas, and 470 kg / h of anhydrous hydrogen fluoride. The reaction pressure in the fluorination reactor was controlled at 0.6 ± 0.1 MPa. The products of the fluorination reaction were taken out from the top of the reactor to the continuous separation system. Hydrogen chloride was separated from the top of the hydrogen chloride tower, and the bottom materials of the tower went to the hydrogen fluoride tower. The bottom materials of the hydrogen fluoride tower were returned to the fluorination reactor for re-reaction. The light components containing R245fa were separated from the top, and after being washed in the water washing tower and the alkali washing tower to remove hydrogen fluoride and chlorine gas in the light components, they went to the de-light tower. A small amount of light components such as R1234ze were separated and returned to the fluorination reactor for continued reaction. The bottom materials of the light component tower went to the 245 tower for rectification and drying to obtain high-quality R245fa. The bottom materials of the 245 tower were returned to the fluorination reactor for continued reaction. About 10 h after the stable feeding of R240fa, the output flow rate of the R245fa finished product and the flow rate of the cyclic materials were stable. At this time, the output flow rate of the finished R245fa was about 525 kg / h.

[0035] Data summary: In this example, from the start of feeding in the telomerization reaction to the stable discharge of the fluorination section, it took about 22 hours. Starting from the time when the whole process was stable, it was continuously operated for 300 hours. The results were summarized as follows: A total of 75 t of vinyl chloride, 186 t of carbon tetrachloride, 30 kg of chlorine gas, and 141 t of anhydrous hydrogen fluoride were consumed, and 157.5 t of the R245fa finished product was obtained, with a yield of 97.9% and a purity of ≥99.9%.

[0036] Example 2

[0037] A full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, comprising:

[0038] Telomerization reaction: Carbon tetrachloride, vinyl chloride, iron powder, and tributyl phosphate are premixed in a pre-mixer in front of the kettle at a mass ratio of 300:50:1:6, and then pumped into the CSTR reaction system. The total feed flow rate is 1800 kg / h. The size of the telomerization reaction kettle is 5000 L, the reaction temperature is 80 - 90 °C, and the reaction pressure is 0.5 ± 0.1 MPa. After the materials react in the CSTR reaction system, they are continuously pumped out to the 240 continuous separation system. In the light component tower, light components such as vinyl chloride and carbon tetrachloride are separated and returned to the pre-mixer in front of the kettle for continued reaction. The materials at the bottom of the tower go to the 240 tower for rectification separation. The R240fa at the top of the tower goes to the fluorination reaction, and the heavy components at the bottom of the tower, including a small amount of unseparated R240fa, iron powder, and tributyl phosphate mixture, are pumped back to the pre-mixer in front of the kettle for cyclic reaction. After about 12 h of feeding, the flow rates of the cyclic materials, R240fa extraction materials, etc. are stable. At this time, the flow rate of R240fa for the fluorination reaction is about 830 kg / h. The feeding materials are adjusted to 600 kg / h of carbon tetrachloride and 240 kg / h of vinyl chloride to keep the materials in the whole system in dynamic balance.

[0039] Fluorination reaction: 1000 kg of the catalyst antimony pentachloride is put into the fluorination reaction kettle, and 5000 kg of anhydrous hydrogen fluoride is pumped in. After pre-activating antimony pentachloride, it is kept at 90 - 100 °C and waits for the telomerization reaction to discharge for the fluorination reaction. The R240fa, chlorine, and anhydrous hydrogen fluoride obtained from the telomerization reaction are fed into the fluorination reaction kettle at a molar ratio of 1:0.0001 - 0.0005:5 - 6. After the telomerization reaction stably discharges, the feeding flow rates of each material are 830 kg / h of R240fa, 0.1 kg / h of chlorine, and 425 kg / h of anhydrous hydrogen fluoride. The fluorination reaction kettle controls the reaction pressure at 0.6 ± 0.1 MPa. The product of the fluorination reaction is taken out from the top of the reaction kettle and sent to the continuous separation system. Hydrogen chloride is separated at the top of the hydrogen chloride tower, and the materials at the bottom of the tower go to the hydrogen fluoride tower. The materials at the bottom of the hydrogen fluoride tower are returned to the fluorination reaction kettle for re-reaction. The light components containing R245fa are separated at the top of the tower and go to the water washing tower and alkali washing tower after washing to remove hydrogen fluoride and chlorine in the light components, and then go to the light component removal tower. A small amount of light components such as R1234ze are separated and returned to the fluorination reaction kettle for continued reaction. The materials at the bottom of the light component tower go to the 245 tower for rectification and drying to obtain high-quality R245fa. The materials at the bottom of the 245 tower are returned to the fluorination reaction kettle for continued reaction. After about 10 h of stable feeding of R240fa, the flow rates of the R245fa finished product discharge and cyclic materials are stable. At this time, the discharge flow rate of the finished R245fa is about 505 kg / h.

[0040] Data summary: In this embodiment, from the start of feeding in the telomerization reaction to the stable discharge of the fluorination section, it took about 22 hours. Starting from the time when the whole process became stable, it ran stably for 300 hours. The results are summarized as follows: A total of 72 t of vinyl chloride, 180 t of carbon tetrachloride, 30 kg of chlorine gas, and 127.5 t of anhydrous hydrogen fluoride were consumed, and 151.5 t of R245fa finished product was obtained, with a yield of 98.1% and a purity of ≥99.9%.

[0041] Example 3

[0042] A full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, comprising:

[0043] Telomerization reaction: Carbon tetrachloride, vinyl chloride, iron powder, and tributyl phosphate were premixed in a pre-mixer in front of the kettle at a mass ratio of 300:50:1:6, and then pumped into the CSTR reaction system. The total feed flow rate was 1000 kg / h. The size of the telomerization reactor was 3000 L, the reaction temperature was 90 - 100 °C, and the reaction pressure was 0.6 ± 0.1 MPa. After the materials reacted in the CSTR reaction system, they were continuously pumped out to the 240 continuous separation system. In the light component tower, light components such as vinyl chloride and carbon tetrachloride were separated and returned to the pre-mixer in front of the kettle for continued reaction. The materials at the bottom of the tower were sent to the 240 tower for rectification separation. The R240fa at the top of the tower went to the fluorination reaction, and the heavy components at the bottom of the tower, including a small amount of unseparated R240fa, iron powder, and tributyl phosphate mixture, were pumped back to the pre-mixer in front of the kettle for cyclic reaction. After about 12 h of feeding, the flow rates of the cyclic materials, the R240fa extraction materials, etc. were stable. At this time, the flow rate of R240fa for the fluorination reaction was about 450 kg / h. The feed materials were adjusted to 323 kg / h of carbon tetrachloride and 130 kg / h of vinyl chloride to keep the materials in the whole system in dynamic balance.

[0044] Fluorination reaction: 800 kg of catalyst antimony pentachloride was put into the fluorination reactor, and 4000 kg of anhydrous hydrogen fluoride was pumped in. After pre-activating antimony pentachloride, the temperature was maintained at 90 - 100 °C, waiting for the feed from the telomerization reaction to carry out the fluorination reaction. The R240fa, chlorine gas, and anhydrous hydrogen fluoride obtained from the telomerization reaction were fed into the fluorination reactor at a molar ratio of 1:0.0001 - 0.0005:5 - 6. After the telomerization reaction stably discharged the product, the feed flow rates of each material were 450 kg / h for R240fa, 0.05 kg / h for chlorine gas, and 230 kg / h for anhydrous hydrogen fluoride. The reaction pressure in the fluorination reactor was controlled at 0.6 ± 0.1 MPa. The fluorination reaction product was taken out from the top of the reactor and sent to the continuous separation system. Hydrogen chloride was separated from the top of the hydrogen chloride tower, and the bottom material of the tower was sent to the hydrogen fluoride tower. The bottom material of the hydrogen fluoride tower was returned to the fluorination reactor for re-reaction. The light components containing R245fa were separated from the top of the tower and sent to the water washing tower and alkali washing tower to remove hydrogen fluoride and chlorine gas in the light components, and then sent to the de-light tower. A small amount of light components such as R1234ze were separated and returned to the fluorination reactor for continuous reaction. The bottom material of the light component tower was sent to the 245 tower for rectification and drying to obtain high-quality R245fa. The bottom material of the 245 tower was returned to the fluorination reactor for continuous reaction. After about 18 h of stable feeding of R240fa, the finished product of R245fa was discharged, and the flow rate of the circulating material was stable. At this time, the discharge flow rate of the finished product R245fa was about 270 kg / h.

[0045] Data summary: From the start of feeding in the telomerization reaction to the stable discharge of the fluorination section in this example, it took about 30 hours. Starting from the time when the whole process was stable, it was stably operated for 300 hours, and the results were summarized as follows: A total of 39 t of vinyl chloride, 96.9 t of carbon tetrachloride, 15 kg of chlorine gas, and 69 t of anhydrous hydrogen fluoride were consumed, and 81 t of the finished product R245fa was obtained, with a yield of 96.8% and a purity of ≥99.9%.

[0046] Example 4

[0047] A full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, including:

[0048] Telomerization reaction: Carbon tetrachloride, vinyl chloride, iron powder, and triethyl phosphate were premixed in a pre-reactor mixer at a mass ratio of 300:50:1:4, and then pumped into a CSTR reaction system. The total feed flow rate was 1800 kg / h. The size of the telomerization reactor was 5000 L, the reaction temperature was 90 - 100 °C, and the reaction pressure was 0.6 ± 0.1 MPa. After the materials reacted in the CSTR reaction system, they were continuously pumped out to a 240 continuous separation system. In the light component tower, light components such as vinyl chloride and carbon tetrachloride were separated and returned to the pre-reactor mixer for further reaction. The bottom materials of the tower went to the 240 tower for rectification separation. The top product R240fa went to the fluorination reaction, and the bottom heavy components, including a small amount of unseparated R240fa, iron powder, and triethyl phosphate mixture, were pumped back to the pre-reactor mixer for circulation reaction. About 12 h after feeding, the flow rates of the circulating materials, R240fa extraction materials, etc. were stable. At this time, the flow rate of R240fa for the fluorination reaction was about 857 kg / h. The feed materials were adjusted to 620 kg / h of carbon tetrachloride and 250 kg / h of vinyl chloride to maintain dynamic balance of the materials in the whole system.

[0049] Fluorination reaction: 1000 kg of the catalyst antimony pentachloride was put into the fluorination reactor, and 5000 kg of anhydrous hydrogen fluoride was pumped in. After pre-activating antimony pentachloride, it was kept at 90 - 100 °C and waited for the telomerization reaction product to carry out the fluorination reaction. The R240fa, chlorine, and anhydrous hydrogen fluoride obtained from the telomerization reaction were fed into the fluorination reactor at a molar ratio of 1:0.0001 - 0.0005:5 - 6. After the telomerization reaction stably discharged materials, the feed flow rates of each material were 857 kg / h of R240fa, 0.03 kg / h of chlorine, and 470 kg / h of anhydrous hydrogen fluoride. The fluorination reactor controlled the reaction pressure at 0.6 ± 0.1 MPa. The fluorination reaction product was taken out from the top of the reactor and sent to a continuous separation system. Hydrogen chloride was separated from the top of the hydrogen chloride tower, and the bottom materials of the tower went to the hydrogen fluoride tower. The bottom materials of the hydrogen fluoride tower were returned to the fluorination reactor for re-reaction. The light components containing R245fa were separated from the top, and after being washed in a water washing tower and an alkali washing tower to remove hydrogen fluoride and chlorine in the light components, they went to the light component removal tower. A small amount of light components such as R1234ze were separated and returned to the fluorination reactor for further reaction. The bottom materials of the light component tower went to the 245 tower for rectification and drying to obtain high-quality R245fa. The bottom materials of the 245 tower were returned to the fluorination reactor for further reaction. About 10 h after the stable feeding of R240fa, the flow rates of the R245fa finished product discharge and the circulating materials were stable. At this time, the discharge flow rate of the finished product R245fa was about 523 kg / h.

[0050] Data summary: In this example, from the start of feeding in the telomerization reaction to the stable discharge of the fluorination section, it took about 22 hours. Starting from the time when the whole process was stable, it was continuously operated for 300 hours. The results were summarized as follows: A total of 75 t of vinyl chloride, 186 t of carbon tetrachloride, 9 kg of chlorine, and 141 t of anhydrous hydrogen fluoride were consumed, and 156.9 t of the R245fa finished product was obtained, with a yield of 97.5% and a purity of ≥99.9%.

[0051] Example 5

[0052] A full - process continuous process for synthesizing 1,1,1,3,3 - pentafluoropropane, comprising:

[0053] Telomerization reaction: Carbon tetrachloride, vinyl chloride, ferrous chloride, and triethyl phosphate are pre - mixed in a pre - reactor mixer at a mass ratio of 300:50:1:4, and then pumped into a CSTR reaction system. The total feed flow rate is 1800 kg / h. The size of the telomerization reactor is 5000 L, the reaction temperature is 70 - 80 °C, and the reaction pressure is 0.45 ± 0.1 MPa. After the materials react in the CSTR reaction system, they are continuously pumped out to a 240 continuous separation system. In the light - component tower, light components such as vinyl chloride and carbon tetrachloride are separated and returned to the pre - reactor mixer for further reaction. The bottom materials of the tower go to the 240 - tower for rectification separation. The top R240fa goes to the fluorination reaction, and the bottom heavy components, including a small amount of unseparated R240fa, ferrous chloride, and triethyl phosphate mixture, are pumped back to the pre - reactor mixer for cyclic reaction. About 12 h after feeding, the flow rates of the cyclic materials, R240fa extraction materials, etc. are stable. At this time, the flow rate of R240fa for the fluorination reaction is about 796 kg / h. The feed materials are adjusted to 575 kg / h of carbon tetrachloride and 230 kg / h of vinyl chloride to keep the materials in the whole system in dynamic balance.

[0054] Fluorination reaction: 1000 kg of catalyst antimony pentachloride is put into the fluorination reactor, and 5000 kg of anhydrous hydrogen fluoride is pumped in. After pre - activating antimony pentachloride, it is kept at 100 - 110 °C and waits for the telomerization reaction product to enter for the fluorination reaction. The R240fa, chlorine, and anhydrous hydrogen fluoride obtained from the telomerization reaction are fed into the fluorination reactor at a molar ratio of 1:0.0001 - 0.0005:5 - 6. After the telomerization reaction stably discharges materials, the feed flow rates of each material are 796 kg / h of R240fa, 0.1 kg / h of chlorine, and 440 kg / h of anhydrous hydrogen fluoride. The fluorination reactor controls the reaction pressure at 0.6 ± 0.1 MPa. The fluorination reaction products are taken out from the top of the reactor and sent to a continuous separation system. Hydrogen chloride is separated from the top of the hydrogen chloride tower, and the bottom materials of the tower go to the hydrogen fluoride tower. The bottom materials of the hydrogen fluoride tower are returned to the fluorination reactor for re - reaction. The light components containing R245fa are separated from the top and, after being washed in a water - washing tower and an alkali - washing tower to remove hydrogen fluoride and chlorine in the light components, go to a de - light tower. A small amount of light components such as R1234ze are separated and returned to the fluorination reactor for further reaction. The bottom materials of the light - component tower go to the 245 - tower for rectification and drying to obtain high - quality R245fa. The bottom materials of the 245 - tower are returned to the fluorination reactor for further reaction. About 10 h after the R240fa stably feeds, the flow rates of the R245fa finished product discharge and the cyclic materials are stable. At this time, the discharge flow rate of the finished R245fa is about 480 kg / h.

[0055] Data summary: In this embodiment, from the start of feeding in the telomerization reaction to the stable discharge after commissioning in the fluorination section, it took about 22 hours. Starting from the time when the whole process became stable, it ran stably for 300 hours, and the results are summarized as follows: A total of 69 t of vinyl chloride, 172.5 t of carbon tetrachloride, 30 kg of chlorine, and 132 t of anhydrous hydrogen fluoride were consumed, and 144 t of R245fa finished product was obtained, with a yield of 97.3% and a purity of ≥99.9%.

[0056] Based on the comprehensive analysis of the above embodiments,

[0057] 1. Comparing Example 1 and Example 2, the different telomerization reaction temperatures have an impact on the product yield of R240fa per unit time of the intermediate product. Under the same feeding conditions, more R240fa can be obtained per unit time at 90 - 100 °C than at 80 - 90 °C.

[0058] 2. Comparing Example 1 and Example 3, the application effect of the CSTR technology in the telomerization reaction has a certain influence on the size of the reaction equipment. Compared with a 5000 L reaction kettle, a 3000 L reaction kettle can obtain more R240fa per unit volume per unit time. The main reason, after analysis, may be that the reaction rate of this reaction is relatively fast, the reaction releases heat sharply, and a large amount of reaction heat is generated instantaneously between the materials. Although through the application of CSTR technology, the reaction materials are mixed circumferentially in the reaction kettle and synchronously transported radially in the pipeline, achieving efficient mass transfer and heat transfer, but for a larger reaction kettle, due to its too large volume, although the phenomenon is not obvious compared with a small reaction kettle, there will still be a phenomenon of local overheating of the materials, resulting in relatively more by-products of side reactions, affecting the final product yield. Therefore, it is also extremely crucial to select a reaction kettle of an appropriate size under the condition of meeting the production capacity requirements.

[0059] 3. Comparing Example 1 with Example 4 and Example 5, the selection of different catalysts and cocatalysts also has an impact on the yield of the telomerization reaction. For the fluorination reaction, the catalyst selection, the feeding ratio of the materials, and the reaction temperature are also very critical control indicators.

[0060] The above-described embodiments are only a preferred solution of this application and do not impose any form of limitation on this application. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane, comprising: Telomerization reaction: Vinyl chloride, carbon tetrachloride, catalyst I and cocatalyst are added to a pre-mixer before the reactor in a molar ratio of 1:0.8 - 3:0.01 - 0.1:0.01 - 0.2 to obtain mixture I. Mixture I is pumped into the reactor system at 600 - 2000 kg / h. A telomerization reaction is carried out at a reaction pressure of 0.3 - 1.0 MPa and a reaction temperature of 60 - 150 °C to obtain the material of the telomerization reaction. The material of the telomerization reaction is continuously pumped out and separated to obtain R240fa. When separating R240fa, the separated vinyl chloride, carbon tetrachloride, catalyst I, cocatalyst and unseparated R240fa are returned to the pre-mixer before the reactor for continuous reaction; Fluorination reaction: Using the liquid-phase fluorination method, catalyst II is put into the fluorination reactor, and anhydrous hydrogen fluoride is pumped in to activate catalyst II. The R240fa, chlorine gas and anhydrous hydrogen fluoride obtained from the above telomerization reaction are continuously introduced into the fluorination reactor containing the activated catalyst II in a molar ratio of 1:0.0001 - 0.0005:5 - 6. The molar ratio of the hourly feed amount of R240fa to catalyst II and the amount of hydrogen fluoride in the fluorination reactor is 1:0.1 - 5:10 - 100. A fluorination reaction is carried out at a reaction pressure of 0.4 - 1.0 MPa and a reaction temperature of 60 - 150 °C to obtain the fluorination reaction product. The fluorination reaction product is separated to obtain 1,1,1,3,3-pentafluoropropane. When separating 1,1,1,3,3-pentafluoropropane, the remaining product after separating 1,1,1,3,3-pentafluoropropane from the fluorination reaction product is returned to the fluorination reactor for continuous reaction; In the telomerization reaction, the reactor system is a CSTR. When separating R240fa, the material of the telomerization reaction is pumped into the light component tower of the 240 continuous separation system to separate vinyl chloride and carbon tetrachloride. The separated vinyl chloride and carbon tetrachloride are returned to the pre-mixer before the reactor for continuous reaction. The bottom material of the light component tower enters the 240 tower of the 240 continuous separation system for rectification separation. R240fa is separated from the top of the 240 tower. The vinyl chloride, carbon tetrachloride, catalyst I, cocatalyst and unseparated R240fa at the bottom of the 240 tower are returned to the pre-mixer before the reactor for continuous reaction; In the telomerization reaction, the 240 continuous separation system further includes a heavy component tower. The heavy component tower is connected to the 240 tower, and R240fa is separated from the top of the heavy component tower.

2. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, In the fluorination reaction, when separating 1,1,1,3,3-pentafluoropropane, the fluorination reaction product is introduced into the hydrogen chloride tower. Hydrogen chloride is separated from the top of the hydrogen chloride tower. The bottom material of the hydrogen chloride tower is introduced into the hydrogen fluoride tower. The light components containing R245fa separated from the top of the hydrogen fluoride tower enter the water washing tower and the alkali washing tower in sequence. The bottom material of the hydrogen fluoride tower is returned to the fluorination reaction kettle for re-reaction. After the hydrogen fluoride and chlorine in the light components containing R245fa are removed in the alkali washing tower, the product is introduced into the dehydrogenation tower. The light components containing R1234ze separated from the top of the dehydrogenation tower are returned to the fluorination reaction kettle for continuous reaction. After the bottom material of the dehydrogenation tower is rectified in the 245 tower, the top product of the 245 tower is introduced into the drying tower, and the drying tower dries the product to obtain 1,1,1,3,3-pentafluoropropane. The bottom material of the 245 tower is returned to the fluorination reaction kettle for continuous reaction.

3. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, The CSTR includes three serially connected telomerization kettles, and the capacity of the telomerization kettle is 2000 - 5000L.

4. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, The first catalyst is at least one of iron, zinc, ferrous chloride or cuprous chloride.

5. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, The cocatalyst is an alkyl phosphate or an alkyl phosphite.

6. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, The reaction temperature of the telomerization reaction is 80 - 140 °C, and the reaction pressure is 0.4 - 0.8 MPa.

7. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, The reaction temperature of the fluorination reaction is 80 - 120 °C, and the reaction pressure is 0.5 - 0.8 MPa.

8. The full-process continuous process for synthesizing 1,1,1,3,3-pentafluoropropane according to claim 1, characterized in that, The second catalyst is one of antimony trichloride, antimony pentachloride, tin tetrachloride or titanium tetrachloride.

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