Preparation method of 2, 3, 3, 3-tetrafluoropropene

Abstract

The invention relates to a preparation method of 2, 3, 3, 3-tetrafluoropropene, which comprises the following steps: carrying out free radical addition on carbon tetrachloride and ethylene to generate 1, 1, 1, 3-tetrachloropropane; the method comprises the following steps of: chlorinating 1, 1, 1, 1, 3-tetrachloropropane to generate 1, 1, 1, 2, 3-pentachloropropane; the method comprises the following steps: carrying out fluorine and chlorine exchange on 1, 1, 1, 1, 2, 3-pentachloropropane liquid phase to generate 1, 1, 1, 2-tetrafluoro-3-chloropropane; and carrying out dehydrochlorination on the 1, 1, 1, 2-tetrafluoro-3-chloropropane to generate the 2, 3, 3, 3-tetrafluoropropene. Carbon tetrachloride and ethylene are used as starting raw materials, and the raw materials are low in cost and easy to obtain; hydrogen and noble metal hydrogenation catalysts are not needed, so that the safety risk and high cost of hydrogenation reaction are avoided; the fluorine-chlorine exchange process effectively reduces polyfluorinated by-products, and the product is high in purity and yield; reaction conditions are mild, intermediate products are easy to separate, and the method is suitable for large-scale continuous production; the byproduct HCl can be absorbed to prepare hydrochloric acid, so that recycling is realized, and green chemical requirements are met.

Description

Technical Field

[0001] This invention relates to the field of synthesis of fluorinated organic compounds, and in particular to a method for preparing 2,3,3,3-tetrafluoropropylene. Background Technology

[0002] 2,3,3,3-Tetrafluoropropylene (HFO-1234yf), as a new generation of environmentally friendly refrigerant, has excellent environmental performance with an ozone depletion potential (ODP) of 0 and a global warming potential (GWP) of only 4. It is a core product to replace traditional hydrofluorocarbon (HFC) refrigerants and is widely used in automotive air conditioning, household refrigeration equipment and cold chain transportation.

[0003] There are multiple technical routes for the preparation of HFO-1234yf. Among them, the route using hexafluoropropylene as the starting material is more representative. The process is usually as follows: hexafluoropropylene is hydrogenated in the presence of a catalyst to produce hexafluoropropane. Hexafluoropropane then undergoes a dehydrofluorination reaction to produce pentafluoropropylene. Pentafluoropropylene continues to undergo a hydrogenation reaction with hydrogen to produce pentafluoropropane. Finally, pentafluoropropane is dehydrofluorinated to obtain HFO-1234yf. However, this route has significant drawbacks: First, the starting material hexafluoropropylene is expensive and relies on a specific fluorinated chemical industry chain, resulting in poor product economics; second, the two hydrogenation reactions need to be carried out at 80-120℃. Although the temperature is lower than that of high-temperature hydrogenation processes, hydrogen is a flammable and explosive gas. Even in medium and low temperature environments, there is still a safety risk of hydrogen leakage and mixing with air to form an explosion limit. This places stringent requirements on the sealing, explosion-proof, and gas concentration monitoring systems of production equipment, resulting in high equipment investment and maintenance costs; third, the catalysts used in the hydrogenation reaction are mostly precious metals (such as palladium / carbon and platinum / alumina supported catalysts). The catalyst preparation cost is high and the activity is easily reduced due to the adsorption of fluorinated intermediates, requiring frequent regeneration or replacement, which further increases the cost of industrial production.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing 2,3,3,3-tetrafluoropropylene, in order to solve the problems of expensive raw materials, flammable and explosive hydrogenation reaction, and expensive catalysts in existing routes, thereby reducing the difficulty and cost of industrial production.

[0006] A first aspect of the present invention provides a method for preparing 2,3,3,3-tetrafluoropropylene, comprising the following steps: S1, carbon tetrachloride, reacts with ethylene radicals to form 1,1,1,3-tetrachloropropane; The reaction equation is: CCl4 + C2H4 → CCl3CH2CH2Cl (1,1,1,3-tetrachloropropane); S2, 1,1,1,3-tetrachloropropane is chlorinated to produce 1,1,1,2,3-pentachloropropane; The reaction equation is: CCl3CH2CH2Cl + Cl2 → CCl3CHClCH2Cl (1,1,1,2,3-pentachloropropane); S3, 1,1,1,2,3-pentachloropropane undergoes liquid-phase fluorine-chlorine exchange to generate 1,1,1,2-tetrafluoro-3-chloropropane; The reaction equation is: CCl3CHClCH2Cl + 4HF → [SbCl5, liquid phase] CF3CHFCH2Cl (1,1,1,2-tetrafluoro-3-chloropropane) + 4HCl; S4, 1,1,1,2-tetrafluoro-3-chloropropane undergoes dehydrochlorination to produce 2,3,3,3-tetrafluoropropene; The reaction equation is: CF3CHFCH2Cl → CF3CF=CH2(2,3,3,3-tetrafluoropropene, HFO-1234yf) + HCl.

[0007] Preferably, step S1 includes: S11. Add carbon tetrachloride and free radical catalyst to the reactor and heat to 50-120℃; S12. Introduce ethylene into the reactor at a flow rate of 0.5-1.0 L / min, maintain the reaction temperature at 50-120℃, and react for 5-7 hours. S13. After the reaction is complete, distillation yields 1,1,1,3-tetrachloropropane.

[0008] Preferably, the free radical catalyst is one or two of benzoyl peroxide and azobisisobutyronitrile, and its amount is 1-5% of the weight of carbon tetrachloride.

[0009] Preferably, the molar ratio of carbon tetrachloride to ethylene is 1.05-3.0:1, that is, carbon tetrachloride is in excess by 5%-150%, which suppresses side reactions, and unreacted raw materials can be recycled, further reducing raw material loss.

[0010] Preferably, the carbon tetrachloride has a purity of ≥98%, and the ethylene has a purity of ≥99.9%.

[0011] Preferably, step S2 includes: S21. Add 1,1,1,3-tetrachloropropane and Lewis acid catalyst to the reactor and heat to 40-120℃; S22. Introduce chlorine gas into the reactor at a flow rate of 0.3-0.5 L / min, maintain the reaction temperature at 40-120℃, and react for 4-6 hours. S23. After the reaction is complete, distillation yields 1,1,1,2,3-pentachloropropane.

[0012] Preferably, the Lewis acid catalyst is ferric chloride, and its amount is 0.2-3.0% of the mass of 1,1,1,3-tetrachloropropane.

[0013] Preferably, the purity of the chlorine gas is ≥99.5%.

[0014] Preferably, step S3 includes: S31. Add 1,1,1,2,3-pentachloropropane and liquid catalyst to the reactor and stir to mix evenly; S32. Add anhydrous hydrofluoric acid slowly at a dropping rate of 5-10 g / min to avoid local overheating. Raise the temperature to 50-200℃, maintain the reaction pressure at 0.5-1.5 MPa (self-pressure of the liquid phase system), stir at 200-300 rpm, and react for 6-8 hours. S33. After the reaction is complete, distillation yields 1,1,1,2-tetrafluoro-3-chloropropane.

[0015] Preferably, the liquid-phase catalyst is antimony pentachloride, and its dosage is 0.5-5% of the weight of 1,1,1,2,3-pentachloropropane. The reaction system is a pure liquid phase environment with no gas phase participation. The liquid-phase method with antimony pentachloride catalyst has high selectivity for the target fluorine-chlorine exchange reaction, effectively reduces polyfluorinated by-products, ensures a high yield of 95%, and makes it easy to meet the product purity standard.

[0016] Preferably, a sealed reactor lined with polytetrafluoroethylene (with a pressure resistance of ≥2MPa and equipped with a mechanical stirring and temperature control system) is used to avoid contact between antimony pentachloride and metal materials, which could lead to corrosion or catalyst deactivation.

[0017] Preferably, the anhydrous hydrofluoric acid (HF) has a purity of ≥99.9%.

[0018] Preferably, the molar ratio of 1,1,1,2,3-pentachloropropane to HF is 1:4-8.

[0019] Preferably, step S4 includes: S41. Heat the fixed-bed reactor filled with solid base catalyst to 150-250℃; S42, 1,1,1,2-tetrafluoro-3-chloropropane is heated at 150-200 h -1 The volume hourly space velocity is introduced into the reactor to carry out the reaction; S43. After the reaction is complete, distillation yields 2,3,3,3-tetrafluoropropylene.

[0020] Preferably, the solid base catalyst is KOH / Al2O3, with a KOH loading of 15-20 wt%, and its loading is 60-70% of the volume of the fixed bed reactor.

[0021] In a second aspect, the present invention provides 2,3,3,3-tetrafluoropropylene prepared by the aforementioned method.

[0022] A third aspect of the invention provides the application of the 2,3,3,3-tetrafluoropropylene in the field of refrigeration.

[0023] Specifically, the refrigeration field includes, but is not limited to, automotive air conditioning, household refrigeration equipment, and cold chain transportation.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The raw material economy is significantly better than the existing route: The present invention uses carbon tetrachloride and ethylene as starting materials. Both are bulk basic chemical products with market prices of only 1 / 5 to 1 / 10 of hexafluoropropylene and stable supply. In the first step, the side reaction is suppressed by using an excess of carbon tetrachloride of 5%-150%. Unreacted raw materials can be recycled, further reducing raw material loss.

[0025] (2) Completely avoids the safety risks and high costs of hydrogenation reaction: The present invention does not require the participation of hydrogen gas throughout the process, and there is no risk of explosion due to hydrogen leakage in the hydrogenation process. There is no need to configure additional gas explosion prevention and concentration monitoring systems, and the safety production coefficient is significantly improved. At the same time, there is no need to use precious metal hydrogenation catalysts. The catalysts (peroxide, ferric chloride, antimony pentachloride, etc.) are all inexpensive industrial-grade reagents, which greatly reduces the industrialization cost.

[0026] (3) The advantages of the fluorine-chlorine exchange process are prominent: the third step adopts the liquid phase method + antimony pentachloride catalyst. Antimony pentachloride has high selectivity for the target fluorine-chlorine exchange reaction, effectively reduces polyfluorinated by-products, ensures a high yield of 95%, and the product purity is easy to meet the standard.

[0027] (4) Clear yield and high total yield: The yield of the first step is 95% based on ethylene, and the yields of the second to fourth steps are 92%, 95% and 93% respectively. The total yield of the whole process (based on ethylene) reaches more than 77%, which further improves the economic efficiency of the product.

[0028] (5) High industrial feasibility: The reaction conditions of each step are mild (temperature ≤220℃, pressure ≤1.5MPa), and conventional fluoropolymer / stainless steel equipment can meet the requirements; there are only four reaction steps, the intermediate products are easy to separate, suitable for large-scale continuous production, there is no wastewater, and the by-product HCl can be absorbed to prepare hydrochloric acid to realize resource utilization, which meets the requirements of green chemical industry. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1 This embodiment provides a method for preparing 2,3,3,3-tetrafluoropropylene, comprising four core reactions, with precise control of reaction conditions in each step and a clearly defined yield for each step, as detailed below: The first step is to prepare 1,1,1,3-tetrachloropropane. 1100g of carbon tetrachloride (99.5% purity, 1.1:1 molar ratio to ethylene) and 10g of benzoyl peroxide were added to a 2L atmospheric pressure reactor equipped with a stirrer, temperature control jacket, and gas inlet. The temperature was raised to 90℃ to completely dissolve the catalyst. Then, 182g of ethylene was introduced at a flow rate of 0.8L / min, and the reaction was maintained at 90℃ for 6 hours. During the reaction, the ethylene conversion rate was monitored in real time by gas chromatography. The reaction was terminated when the ethylene content was lower than 0.5%. After the reaction, the reaction solution was cooled to 25-30℃ and distilled under atmospheric pressure. The fraction at 76-78℃ was carbon tetrachloride, and the fraction at the top of the column at 159-162℃ was 1,1,1,3-tetrachloropropane. After distillation, 1123.1g of 1,1,1,3-tetrachloropropane with a purity of 98.8% and a yield of 95% based on ethylene were obtained. 100g of unreacted carbon tetrachloride was recovered and collected for the next batch of reaction.

[0033] The second step involves the preparation of 1,1,1,2,3-pentachloropropane. 1000g of 1,1,1,3-tetrachloropropane and 6g of ferric chloride were added to a 2L reactor equipped with a reflux condenser, chlorine distributor, and tail gas absorption device. The temperature was raised to 75℃. Chlorine gas was introduced at a flow rate of 0.4L / min, and the reaction was carried out for 6 hours. The residual amount of 1,1,1,3-tetrachloropropane was monitored by gas chromatography. When the residual amount was ≤1%, the chlorine gas introduction was stopped. Nitrogen gas (flow rate 1.0L / min) was introduced into the reaction solution to displace the excess chlorine gas for 30 minutes. Then, the solution was distilled at atmospheric pressure (top temperature 195-197℃). After distillation, 1094g of 1,1,1,2,3-pentachloropropane was obtained with a purity of 98.6%, and the yield was 92% based on 1,1,1,3-tetrachloropropane.

[0034] The third step involves the preparation of 1,1,1,2-tetrafluoro-3-chloropropane. Add 880g to a 2L sealed reactor lined with polytetrafluoroethylene. 1,1,1,2,3-Pentachloropropane and 35g of antimony pentachloride were mixed thoroughly by stirring. The reaction temperature was maintained at 120-125℃. 569.5g of anhydrous hydrofluoric acid (molar ratio 1:7) was slowly added at a rate of 8g / min to avoid local overheating. After the addition was complete, the temperature was raised to 130-135℃, the pressure was maintained at 1.2MPa, and the stirring speed was 250rpm. The reaction was stopped after 7 hours. The conversion rate of 1,1,1,2,3-pentachloropropane was monitored by gas chromatography. The reaction was stopped when the conversion rate was ≥99%. The reaction product was cooled to 30-40℃, and nitrogen gas was slowly introduced to remove and recover the remaining hydrogen chloride and hydrogen fluoride gases. The product was then subjected to atmospheric distillation. The fraction with a top temperature of 42-43.5℃ was collected. After distillation, 581.7g of 1,1,1,2-tetrafluoro-3-chloropropane was obtained with a purity of 98.5%, and the yield was 95% based on 1,1,1,2,3-pentachloropropane.

[0035] Step 4: Preparation of 2,3,3,3-tetrafluoropropylene 560g of 1,1,1,2-tetrafluoro-3-chloropropane was subjected to a process that lasted 180 hours. -1 The gas is introduced at high space velocity into a stainless steel fixed-bed reactor (inner diameter 20-30 mm, length 500-800 mm, filled with KOH / Al2O3 catalyst) equipped with a heating furnace and gas collection device. The reaction temperature is 210℃. During the reaction, the product composition is monitored by gas chromatography. When the selectivity of 2,3,3,3-tetrafluoropropene is ≤98%, the catalyst is replaced. The reaction product is then distilled through a pressure distillation column. At a pressure of 0.8 MPa, the fraction with a top temperature of 19-20℃ is collected. After distillation, 394.5 g of 2,3,3,3-tetrafluoropropene is obtained with a purity of 99.7%, and the yield is 93% based on 1,1,1,2-tetrafluoro-3-chloropropane.

[0036] The fluorine spectrum data of the 2,3,3,3-tetrafluoropropylene prepared in this embodiment are as follows: 19F-NMR (CDC13): δ -72.1 ppm (3F), -124.7 ppm (1F, JH-F=47Hz).

[0037] Example 2 This embodiment provides a method for preparing 2,3,3,3-tetrafluoropropylene, comprising four core reactions, with precise control of reaction conditions in each step and a clearly defined yield for each step, as detailed below: The first step is to prepare 1,1,1,3-tetrachloropropane. 1500g of carbon tetrachloride (98.5% purity, 1.5:1 molar ratio to ethylene, 50% excess) and 6g of azobisisobutyronitrile (AIOBR) were added to a 2L atmospheric pressure reactor equipped with a stirrer, temperature control jacket, and gas inlet. The temperature was raised to 85℃ to completely dissolve the catalyst. 182g of ethylene was introduced at a flow rate of 0.7L / min, and the reaction was maintained at 88℃ for 5.5 hours. During the reaction, the ethylene conversion rate was monitored in real time by gas chromatography. When the ethylene content was below 0%, the reaction was stopped. The reaction ended after 0.5%; after the reaction, the reaction solution was cooled to 25-30℃ and distilled under normal pressure. The fraction collected at 76-78℃ was carbon tetrachloride, and the fraction at the top of the column at 159-162℃ was 1,1,1,3-tetrachloropropane. After distillation, 1126g of 1,1,1,3-tetrachloropropane was obtained with a purity of 98.6% and a yield of 95.1% based on ethylene. 500g of unreacted carbon tetrachloride was recovered and collected for the next batch of reaction.

[0038] The second step involves the preparation of 1,1,1,2,3-pentachloropropane. 1126 g of 1,1,1,3-tetrachloropropane and 7 g of ferric chloride were added to a 2 L reactor equipped with a reflux condenser, chlorine distributor, and tail gas absorption device, and the temperature was raised to 78 °C. Chlorine gas was introduced at a flow rate of 0.35 L / min, and the reaction was carried out for 4.5 hours. The residual amount of 1,1,1,3-tetrachloropropane was monitored by gas chromatography, and the chlorine gas introduction was stopped when the residual amount was ≤1%. Nitrogen gas (flow rate 1.0 L / min) was introduced into the reaction solution to displace the excess chlorine gas for 30 minutes, and then the solution was distilled at atmospheric pressure (top temperature 195-197 °C). After distillation, 1235 g of 1,1,1,2,3-pentachloropropane was obtained with a purity of 98.9%, and the yield was 92.2% based on 1,1,1,3-tetrachloropropane.

[0039] The third step involves the preparation of 1,1,1,2-tetrafluoro-3-chloropropane. Add 850g to a 2L sealed reactor lined with polytetrafluoroethylene. 1,1,1,2,3-Pentachloropropane and 20 g of antimony pentachloride were mixed thoroughly by stirring. While maintaining the reaction temperature at 120-125 °C, 630 g of anhydrous hydrofluoric acid (molar ratio 1:8) was slowly added at a rate of 10 g / min to avoid localized overheating. After the addition was complete, the temperature was raised to 130 °C, the pressure was maintained at 1.3 MPa, and the stirring speed was 280 rpm. The reaction was stopped after 6.5 hours. The conversion rate of 1,1,1,2,3-Pentachloropropane was monitored by gas chromatography. The reaction was stopped when the conversion rate was ≥99%. The reaction product was cooled to 30-40 °C, and nitrogen gas was slowly introduced to remove and recover the remaining hydrogen chloride and hydrogen fluoride gases. The product was then subjected to atmospheric distillation, and the fraction with a top temperature of 42-43.5 °C was collected. After distillation, 562 g of 1,1,1,2-tetrafluoro-3-chloropropane was obtained with a purity of 98.6%, and the yield (based on 1,1,1,2,3-pentachloropropane) was 95.1%.

[0040] Step 4: Preparation of 2,3,3,3-tetrafluoropropylene 562g of 1,1,1,2-tetrafluoro-3-chloropropane was subjected to a reaction at 190h. -1 The gas is introduced at high space velocity into a stainless steel fixed-bed reactor (inner diameter 20-30 mm, length 500-800 mm, filled with KOH / Al2O3 catalyst) equipped with a heating furnace and gas collection device. The reaction temperature is 215℃. During the reaction, the product composition is monitored by gas chromatography. When the selectivity of 2,3,3,3-tetrafluoropropene is ≤98%, the catalyst is replaced. The reaction product is then distilled through a pressure distillation column. At a pressure of 0.8 MPa, the fraction with a top temperature of 19-20℃ is collected. After distillation, 396 g of 2,3,3,3-tetrafluoropropene is obtained with a purity of 99.6%, and the yield is 93% based on 1,1,1,2-tetrafluoro-3-chloropropane.

[0041] In summary, this invention uses bulk chemical raw materials carbon tetrachloride and ethylene as starting materials, and achieves a highly efficient method for preparing 2,3,3,3-tetrafluoropropylene through controllable free radical addition, chlorination, liquid-phase fluorine-chlorine exchange, and dehydrochlorination reaction. This method solves the problems of expensive raw materials, flammable and explosive hydrogenation reactions, and expensive catalysts in existing hexafluoropropylene routes, clarifies the yield of each key step, and reduces the difficulty and cost of industrial production.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing 2,3,3,3-tetrafluoropropylene, characterized in that, Includes the following steps: S1, carbon tetrachloride, reacts with ethylene radicals to form 1,1,1,3-tetrachloropropane; S2, 1,1,1,3-tetrachloropropane is chlorinated to produce 1,1,1,2,3-pentachloropropane; S3, 1,1,1,2,3-pentachloropropane undergoes liquid-phase fluorine-chlorine exchange to generate 1,1,1,2-tetrafluoro-3-chloropropane; S4, 1,1,1,2-tetrafluoro-3-chloropropane undergoes dehydrochlorination to produce 2,3,3,3-tetrafluoropropene.

2. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that, Step S1 includes: S11. Add carbon tetrachloride and free radical catalyst to the reactor and heat to 50-120℃; S12. Introduce ethylene into the reactor and maintain the reaction temperature at 50-120℃. S13. After the reaction is complete, distillation yields 1,1,1,3-tetrachloropropane.

3. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 2, characterized in that, The free radical catalyst is one or both of benzoyl peroxide and azobisisobutyronitrile, and its amount is 1-5% of the weight of carbon tetrachloride.

4. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that, Step S2 includes: S21. Add 1,1,1,3-tetrachloropropane and Lewis acid catalyst to the reactor and heat to 40-120℃; S22. Introduce chlorine gas into the reactor and maintain the reaction temperature at 40-120℃; S23. After the reaction is complete, distillation yields 1,1,1,2,3-pentachloropropane.

5. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 4, characterized in that, The Lewis acid catalyst is ferric chloride, and its dosage is 0.2-3.0% of the mass of 1,1,1,3-tetrachloropropane.

6. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that, Step S3 includes: S31. Add 1,1,1,2,3-pentachloropropane and liquid catalyst to the reactor and stir to mix evenly; S32. Add anhydrous hydrofluoric acid, heat to 50-200℃, and maintain the reaction pressure at 0.5-1.5MPa; S33. After the reaction is complete, distillation yields 1,1,1,2-tetrafluoro-3-chloropropane.

7. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 6, characterized in that, The liquid-phase catalyst is antimony pentachloride, and its dosage is 0.5-5% of the weight of 1,1,1,2,3-pentachloropropane.

8. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that, Step S4 includes: S41. Heat the fixed-bed reactor filled with solid base catalyst to 150-250℃; S42. 1,1,1,2-Tetrafluoro-3-chloropropane is introduced into the reactor to carry out the reaction. S43. After the reaction is complete, distillation yields 2,3,3,3-tetrafluoropropylene.

9. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 8, characterized in that, The solid base catalyst is KOH / Al2O3, with a KOH loading of 15-20 wt%, and its loading is 60-70% of the volume of the fixed bed reactor.

10. 2,3,3,3-tetrafluoropropylene prepared by the method of any one of claims 1-9, and its application in the field of refrigeration.