A process for the preparation of 2,3,3,3-tetrafluoropropene

Abstract

This invention discloses a method for preparing 2,3,3,3-tetrafluoropropylene. Using ethylene and carbon tetrachloride as raw materials, 1,1,1,3-tetrachloropropane (HCC-250fb) is first prepared. Then, 1,1,1,3-tetrachloropropane is decomposed to obtain 1,1,3-trichloropropene (HCC-1240za). This 1,1,3-trichloropropene is then reacted with chlorine to generate 1,1,1,2,3-pentachloropropane (HCC-240db). The 1,1,1,2,3-pentachloropropane is then decomposed to obtain 1,1,2,3-tetrachloropropene (HCC-1230xa). The 1,1,2,3-tetrachloropropene is reacted with hydrofluoric acid to generate 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf). Finally, 2,3,3,3-tetrafluoropropylene is prepared using two different methods. This invention has low raw material costs and high yield.

Description

Technical Field

[0001] This invention belongs to the field of organic compound preparation, and specifically relates to a method for preparing 2,3,3,3-tetrafluoropropylene. Background Technology

[0002] 2,3,3,3-Tetrafluoropropylene (HFO-1234yf) possesses excellent physicochemical and environmental properties, making it a widely applicable refrigerant, foaming agent, fire extinguishing agent, heat transfer medium, propellant, gaseous dielectric, sterilizing agent carrier, power circulation working fluid, polymer monomer, and pharmaceutical and pesticide intermediate. Therefore, the production of 2,3,3,3-tetrafluoropropylene can bring significant economic benefits. HFO-1234yf is one of the representatives of fourth-generation refrigerants, exhibiting low global warming potential (GWP) and environmentally friendly characteristics, and is widely used in automotive air conditioning, commercial refrigeration, and other fields.

[0003] Currently, there are various methods for preparing 2,3,3,3-tetrafluoropropylene, such as: (1) using 1,1,2,3,3,3-hexafluoropropylene (HFP) as raw material to prepare 2,3,3,3-tetrafluoropropylene. This method has a long preparation route and high raw material cost; (2) reacting 1,1,2,3-tetrachloropropylene with a first fluorinating agent to generate 2-chloro-3,3,3-trifluoropropylene (HCFO-1233xf) and a first intermediate composition of the first chlorine-containing byproduct; reacting the first intermediate composition of the first chlorine-containing byproduct with a second fluorinating agent to generate 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) and a second intermediate composition of the second chlorine-containing byproduct; and then catalytically dehydrochlorinating at least a portion of HCFC-244bb to generate 2,3,3,3-tetrafluoropropylene. This route synthesizes 2,3,3,3-tetrafluoropropylene in three steps. HCFO-1233xf is converted into HCFC-244bb in a liquid-phase reactor. The third step, saponification, produces a lot of waste and has a low yield.

[0004] It is evident that existing technologies for preparing 2,3,3,3-tetrafluoropropylene suffer from problems such as long preparation routes, high raw material costs, and low yields. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing 2,3,3,3-tetrafluoropropylene. Addressing the deficiencies of existing technologies, this method uses ethylene and carbon tetrachloride as raw materials. First, 1,1,1,3-tetrachloropropane (HCC-250fb) is prepared. Then, 1,1,1,3-tetrachloropropane is decomposed to obtain 1,1,3-trichloropropene (HCC-1240za). This 1,1,3-trichloropropene then reacts with chlorine to generate 1,1,1,2,3-pentachloropropane (HCC-240db). The 1,1,1,2,3-pentachloropropane is then decomposed to obtain 1,1,2,3-tetrachloropropene (HCC-1230xa). The 1,1,2,3-tetrachloropropene is reacted with hydrofluoric acid to generate 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf). Finally, 2,3,3,3-tetrafluoropropylene is prepared using two different methods. This invention has low raw material costs and high yield.

[0006] To solve the above technical problems, the following technical solution is adopted:

[0007] A method for preparing 2,3,3,3-tetrafluoropropylene includes the following steps:

[0008] (1) 1,1,3-trichloropropene was prepared by dehydrochlorination of 1,1,1,3-tetrachloropropane under the action of a catalyst at a reaction temperature of 200~400℃;

[0009] (2) 1,1,1,2,3-pentachloropropane was prepared using the following two methods:

[0010] Method 1: Under the action of a liquid-phase reaction catalyst, 1,1,3-trichloropropene obtained in step (1) is dissolved in a solvent and chlorine gas is introduced to obtain 1,1,1,2,3-pentachloropropane. The reaction temperature is 30~150℃.

[0011] Method 2: Under the action of a gas-phase reaction catalyst, 1,1,3-trichloropropene obtained in step (1) is introduced into a reactor together with chlorine to obtain 1,1,1,2,3-pentachloropropane. The reaction temperature is 50~200℃.

[0012] (3) Under the action of a catalyst, 1,1,1,2,3-pentachloropropane obtained in step (2) is dehydrochlorinated to prepare 1,1,2,3-tetrachloropropene, and the reaction temperature is 200~400℃;

[0013] (4) Under the action of a catalyst, the 1,1,2,3-tetrachloropropene obtained in step (3) is reacted with hydrofluoric acid to obtain 2-chloro-3,3,3-trifluoropropene. The reaction temperature is 200~400℃.

[0014] (5) 2,3,3,3-tetrafluoropropylene was prepared using the following two methods:

[0015] Method 1: Under the action of a catalyst, 2-chloro-3,3,3-trifluoropropene obtained in step (4) is reacted with hydrofluoric acid to obtain 2,3,3,3-tetrafluoropropene. The reaction temperature is 200~450℃, which is 20~80℃ higher than the reaction temperature in step (4).

[0016] Method 2: Under the action of a catalyst, 2-chloro-3,3,3-trifluoropropene obtained in step (4) is reacted with hydrofluoric acid to obtain 2-chloro-1,1,1,2-tetrafluoropropane at a reaction temperature of 30~150℃; then 2-chloro-1,1,1,2-tetrafluoropropane is dehydrochlorinated under a gas-phase reaction catalyst to obtain 2,3,3,3-tetrafluoropropene at a reaction temperature of 200~450℃.

[0017] After optimization, the 1,1,1,3-tetrachloropropane is prepared by the following method: ethylene is reacted with carbon tetrachloride to prepare 1,1,1,3-tetrachloropropane under the action of a catalyst and a co-catalyst, the reaction temperature is 80℃~150℃, the reaction pressure is 0~3MPa, and the reaction time is 2~10h.

[0018] After optimization, in the preparation process of 1,1,1,3-tetrachloropropane, the catalyst used is reduced iron powder, and the co-catalyst used is a phosphate ester or a phosphite ester, specifically one or more of tributyl phosphate, dibutyl phosphate, triethyl phosphate, trimethyl phosphite, and tributyl phosphite.

[0019] After optimization, the catalyst in step (1) is one or more of ferric chloride, barium chloride, and copper chloride supported on activated carbon.

[0020] After optimization, the liquid-phase reaction catalyst in step (2) of method 1 is one or more of ferric chloride, chromium chloride, aluminum chloride, and copper chloride.

[0021] After optimization, the solvent in step (2) of method 1 is one of carbon tetrachloride, chloroform, and dichloromethane.

[0022] After optimization, the gas-phase reaction catalyst in step (2) mode 2 is ferric chloride, chromium chloride, aluminum chloride, or copper chloride supported on activated carbon or fluorinated chromium oxide.

[0023] After optimization, the catalyst in step (3) is one or more of ferric chloride, barium chloride, and copper chloride supported on activated carbon.

[0024] After optimization, the catalyst in step (4) is either supported or unsupported chromium oxide, wherein the support is selected from one or more of magnesium, zinc, aluminum, nickel, and cobalt.

[0025] After optimization, in step (5), the catalyst used in method 1 is supported or unsupported chromium oxide, wherein the support is selected from one or more of magnesium, zinc, aluminum, nickel and cobalt.

[0026] After optimization, in step (5), the catalyst used in method 2 is one or more of titanium tetrachloride, tin tetrachloride, antimony pentachloride, and fluorosulfonic acid, and the gas phase reaction catalyst is one or more of activated carbon, Pd / C, Pt / C, and metal halide supported activated carbon.

[0027] The above technical solution has the following beneficial effects:

[0028] The raw materials for this route are readily available and low in cost. Unreacted raw materials can be recycled and reused for further reactions, resulting in minimal emissions of waste. Detailed Implementation

[0029] This invention aims to provide a method for preparing 2,3,3,3-tetrafluoropropylene. Using ethylene and carbon tetrachloride as raw materials, 1,1,1,3-tetrachloropropane (HCC-250fb) is first prepared. Then, 1,1,1,3-tetrachloropropane is decomposed to obtain 1,1,3-trichloropropene (HCC-1240za). This 1,1,3-trichloropropene is then reacted with chlorine to generate 1,1,1,2,3-pentachloropropane (HCC-240db). The 1,1,1,2,3-pentachloropropane is then decomposed to obtain 1,1,2,3-tetrachloropropene (HCC-1230xa). The 1,1,2,3-tetrachloropropene is reacted with hydrofluoric acid to generate 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf). Finally, 2,3,3,3-tetrafluoropropylene is prepared using two different methods. This invention has low raw material costs and high yield.

[0030] The present invention will now be described in detail with reference to specific embodiments. It should be understood that the implementation of the present invention is not limited to the embodiments described below, and any modifications or alterations made to the present invention will fall within the protection scope of the present invention.

[0031] In the following embodiments, unless otherwise specified, the reagents, materials and equipment used are commercially available, prepared by conventional methods, or commonly used in the industry.

[0032] Example 1

[0033] The method for preparing 2,3,3,3-tetrafluoropropylene according to the present invention includes the following steps:

[0034] Step 1: CH2=CH2 + CCl4 → CCl3CH2CH2Cl (HCC-250fb)

[0035] 2 kg of carbon tetrachloride, 20 g of reduced iron powder, and 20 g of tributyl phosphate were added to a 5 L nitrogen-purged reactor. Stirring was started, and the reactor temperature was raised to 110 °C. At the reaction temperature, ethylene was introduced into the reactor at a rate of 80 g / h. Cooling water was circulated through the reactor to remove the heat of reaction. 260 g of ethylene was introduced, and the reaction was terminated after 5 hours. GC analysis revealed that the product mixture contained 0.43% ethylene, 63.52% 1,1,1,3-tetrachloropropane, 31.99% carbon tetrachloride, 3.53% unknown substances, and 0.53% tributyl phosphate.

[0036] Step 2: CCl3CH2CH2Cl → CCl2=CHCH2Cl (HCC-1240za) + HCl

[0037] 200 mL of activated carbon-supported ferric chloride catalyst was packed in a fixed-bed reactor and reacted at 250 °C. After purification, 99.9% of 1,1,1,3-tetrachloropropane was passed into the reactor at a rate of 130 g / h to remove hydrogen chloride. The product was washed with alkali and analyzed by GC, which showed that it contained 84.5% 1,1,3-trichloropropene, 13.2% 1,1,1,3-tetrachloropropane, and 2.1% high-boiling chlorocycloalkanes or chlorocycloolefins.

[0038] Step 3: CCl2=CHCH2Cl + Cl2 → CCl3CHClCH2Cl (HCC-240db)

[0039] 100g of purified 99.9% 1,1,3-trichloropropene and 0.013mol Lewis catalyst dissolved in carbon tetrachloride were introduced into a reactor, and 48.8g of chlorine gas was introduced at 150℃ to react. The product was washed with alkali and analyzed by GC. The results are shown in the table below.

[0040] Table 1

[0041] catalyst Reaction temperature / ℃ Conversion rate / selectivity (%) <![CDATA[FeCl3]]> 120 70 / 100 <![CDATA[FeCl3]]> 100 23 / 95.6 <![CDATA[AlCl3]]> 120 65 / 93.7 <![CDATA[CuCl2]]> 120 43 / 89 <![CDATA[CrCl3]]> 120 57 / 95.2 none 150 15 / 30

[0042] Step 4: CCl3CHClCH2Cl → CCl2=CClCH2Cl(HCC-1230xa) + HCl

[0043] A 200 mL activated carbon-supported ferric chloride catalyst was placed in a fixed-bed reactor and reacted at 200 °C. After purification, 99.9% 1,1,1,2,3-pentachloropropane was passed into the reactor at a rate of 193 g / h to remove hydrogen chloride. The product was washed with alkali and analyzed by GC, which showed that it contained 49.1% 1,1,2,3-tetrachloropropene, 48.9% 1,1,1,2,3-pentachloropropane, and 1.8% high-boiling chlorocycloalkanes or chlorocycloolefins.

[0044] Step 5: CCl2=CClCH2Cl + 3HF → CF3CCl=CH2 (HCFO-1233xf) + 3HCl

[0045] 200 mL of chromium oxide was placed in a fixed-bed reactor, and HF was passed through to completely fluorinate the catalyst. The molar ratio of 1,1,1,2,3-pentachloropropane to HF was 1:8. After purification, 99.9% of the 1,1,1,2,3-pentachloropropane was introduced into a preheater at a flow rate of 107 g / h for preheating, and then introduced into the reactor with HF for fluorination reaction at 250 °C. The product was washed with alkali and analyzed by GC, which showed that it contained 43.2% 2-chloro-3,3,3-trifluoropropene, 0.4% 2,3,3,3-tetrafluoropropene, 52.5% 1,1,1-trifluoro-2,3-dichloropropane, 0.7% 1-chloro-3,3,3-trifluoropropene, and 3.1% 1,1,1,2,3-pentafluoropropane. 1,1,1-trifluoro-2,3-dichloropropane and 1,1,1,2,3-pentafluoropropane were returned to the reactor in step 4 to continue the reaction and yield 2-chloro-3,3,3-trifluoropropene.

[0046] Step 6: CF3CCl=CH2 + HF → CF3CF=CH2 (HFO-1234yf) + HCl

[0047] 200 mL of chromium oxide was placed in a fixed-bed reactor, and HF was passed through to completely fluorinate the catalyst. The molar ratio of 2-chloro-3,3,3-trifluoropropene to HF was 1:5. The purified 2-chloro-3,3,3-trifluoropropene was preheated in a preheater at a flow rate of 97.1 g / h and then reacted with HF in the reactor at 300 °C for fluorination. The product was washed with alkali and analyzed by GC, which showed that it contained 1.2% 2-chloro-3,3,3-trifluoropropene, 76.7% 2,3,3,3-tetrafluoropropene, 20.8% 1,1,1,2,2-pentafluoropropane, and 1.1% 1,1,1,2,3-pentafluoropropane. The 1,1,1,2,2-pentafluoropropane and 1,1,1,2,3-pentafluoropropane were separated from the unconverted 2-chloro-3,3,3-trifluoropropene and returned to the reactor for further reaction to obtain 2,3,3,3-tetrafluoropropene.

[0048] Example 2 (Alternative Route)

[0049] Steps 1 to 5: Same as in Example 1, to obtain intermediate HCFO-1233xf.

[0050] The alternative route includes the following steps in sequence:

[0051] Liquid-phase fluorination reaction: CF3CCl=CH2 + HF → CF3CClFCH3 (HFC-244bb)

[0052] The catalyst tin tetrachloride was added to the reactor, and hydrofluoric acid was introduced for reaction. The reaction temperature was raised to 90°C, and 2-chloro-3,3,3-trifluoropropene and hydrofluoric acid were introduced into the reactor at a molar ratio of 1:1. The discharge pipe was adjusted by a valve, and the gaseous material was passed through a water scrubber and an alkali scrubber. A sample was taken from the outlet of the alkali scrubber to measure GC. The conversion rate was 95%, and the selectivity was 98%.

[0053] Dehydrochlorination reaction: CF3CClFCH3 → CF3CF=CH2 (HFO-1234yf) + HCl

[0054] 200 mL of barium chloride-supported activated carbon was placed in a fixed-bed reactor. Purified 2-chloro-1,1,1,2-tetrafluoropropane was preheated in a preheater at a flow rate of 50 g / h before entering the reactor for dehydrochlorination at 250 °C. The product was passed through a water scrubber and an alkali scrubber. A GC sample was taken from the alkali scrubber outlet and analyzed: 68.2% 2,3,3,3-tetrafluoropropene and 30.7% 2-chloro-1,1,1,2-tetrafluoropropane.

[0055] Example 3 (Alternative Route)

[0056] Steps 1, 2, and 4 through 6: Same as in Example 1. Step 3 is different from that in Example 1.

[0057] The alternative route includes the following steps:

[0058] Gas-phase reaction: 200 mL of activated carbon-supported ferric chloride catalyst was packed in a fixed-bed reactor. The molar ratio of 1,1,3-trichloropropene to Cl2 was 1:0.1 to 1:1.1. After purification, 99.9% 1,1,3-trichloropropene was preheated in a preheater at a flow rate of 100 g / h, and chlorine gas was introduced at a flow rate of 48.8 g / h before entering the reactor for chlorination at 200–300 °C. The product was washed with alkali and analyzed by GC. The results are shown in the table below.

[0059] Table 2

[0060] Reaction temperature / ℃ Conversion rate / selectivity (%) 60 70 / 95 60 68 / 95.6 80 86 / 93 80 89 / 90 100 96 / 80 100 95 / 84

[0061] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing 2,3,3,3-tetrafluoropropylene, characterized in that... The process includes the following steps: (1) under the action of a catalyst, 1,1,1,3-tetrachloropropane is dehydrochlorinated to prepare 1,1,3-trichloropropene, and the reaction temperature is 200~400℃; (2) 1,1,1,2,3-pentachloropropane is prepared by the following two methods: Method 1: under the action of a liquid-phase reaction catalyst, 1,1,3-trichloropropene obtained in step (1) is dissolved in a solvent and chlorine gas is introduced to obtain 1,1,1,2,3-pentachloropropane, and the reaction temperature is 300~400℃. 0~150℃; Method 2: Under the action of a gas-phase reaction catalyst, 1,1,3-trichloropropene obtained in step (1) is introduced into a reactor together with chlorine to obtain 1,1,1,2,3-pentachloropropane, and the reaction temperature is 50~200℃; (3) Under the action of a catalyst, 1,1,1,2,3-pentachloropropane obtained in step (2) is dehydrochlorinated to prepare 1,1,2,3-tetrachloropropene, and the reaction temperature is 200~400℃; (4) Under the action of a catalyst Next, the 1,1,2,3-tetrachloropropene obtained in step (3) is reacted with hydrofluoric acid to obtain 2-chloro-3,3,3-trifluoropropene at a reaction temperature of 200~400℃; (5) 2,3,3,3-tetrafluoropropene is prepared by the following two methods: Method 1: Under the action of a catalyst, the 2-chloro-3,3,3-trifluoropropene obtained in step (4) is reacted with hydrofluoric acid to obtain 2,3,3,3-tetrafluoropropene at a reaction temperature of 200~450℃. The reaction temperature is increased by 20~80℃ above the reaction temperature in step (4); Method 2: Under the action of a catalyst, 2-chloro-3,3,3-trifluoropropene obtained in step (4) is reacted with hydrofluoric acid to obtain 2-chloro-1,1,1,2-tetrafluoropropane, and the reaction temperature is 30~150℃; then 2-chloro-1,1,1,2-tetrafluoropropane is dehydrochlorinated under a gas-phase reaction catalyst to obtain 2,3,3,3-tetrafluoropropene, and the reaction temperature is 200~450℃.

2. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The 1,1,1,3-tetrachloropropane is prepared by the following method: ethylene is reacted with carbon tetrachloride in the presence of a catalyst and a co-catalyst to prepare 1,1,1,3-tetrachloropropane. The reaction temperature is 80℃~150℃, the reaction pressure is 0~3MPa, and the reaction time is 2~10h.

3. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 2, characterized in that: In the preparation process of 1,1,1,3-tetrachloropropane, the catalyst used is reduced iron powder, and the co-catalyst used is a phosphate ester or a phosphite ester, specifically one or more of tributyl phosphate, dibutyl phosphate, triethyl phosphate, trimethyl phosphite, and tributyl phosphite.

4. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The catalyst in step (1) is one or more of ferric chloride, barium chloride, and copper chloride supported on activated carbon.

5. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: In step (2) of method 1, the liquid-phase reaction catalyst is one or more of ferric chloride, chromium chloride, aluminum chloride, and copper chloride; the solvent is one of carbon tetrachloride, chloroform, and dichloromethane.

6. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The gas-phase reaction catalyst in step (2) of method 2 is ferric chloride, chromium chloride, aluminum chloride, or copper chloride supported on activated carbon or fluorinated chromium oxide.

7. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The catalyst in step (3) is one or more of ferric chloride, barium chloride, and copper chloride supported on activated carbon.

8. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The catalyst in step (4) is either supported or unsupported chromium oxide, wherein the supporting material is selected from one or more of magnesium, zinc, aluminum, nickel, and cobalt.

9. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: In step (5), the catalyst used in Method 1 is supported or unsupported chromium oxide, wherein the supporting material is selected from one or more of magnesium, zinc, aluminum, nickel, and cobalt.

10. The method for preparing 2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: In step (5), the catalyst used in method 2 is one or more of titanium tetrachloride, tin tetrachloride, antimony pentachloride, and fluorosulfonic acid, and the gas phase reaction catalyst is one or more of activated carbon, Pd / C, Pt / C, and metal halide supported activated carbon.