Process for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene

Abstract

A method for co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene, comprising: A1. a telomerization step: preparing 3-chloro-1,1,1,2-tetrafluoropropane through pressurized telomerization reaction of monofluoromonochloromethane and trifluoroethylene in the presence of a telomerization catalyst; the telomerization catalyst is a Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane; A2. a dehydrohalogenation step: 3-chloro-1,1,1,2-tetrafluoropropane undergoes dehydrochlorination and dehydrofluorination simultaneously in the presence of a composite dehalogenation catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene; the composite dehalogenation catalyst is prepared from an oxide or a fluoride of at least one of Al, Mg or Cr and activated carbon powder. The present application has the advantages of simple process, mild reaction conditions, high total yield of target products, etc.

Description

[0001] This invention is a divisional application of Chinese invention patent application filed on April 15, 2021, with application number CN202110404614.6 and invention title “Method for Co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trichloropropylene”. Technical Field

[0002] This invention relates to the preparation of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene, and particularly to a method for preparing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene by using trifluoroethylene as raw material, through liquid-phase pressure polymerization and dehydrohalogenation reaction. Background Technology

[0003] 2,3,3,3-Tetrafluoropropylene (HFO-1234yf) has an ODP of zero, a GWP of 4, and lower life-cycle climate performance (LCCP) than the traditional refrigerant HFC-134a. Its system refrigeration performance is superior to HFC-134a, and its atmospheric decomposition products are the same as HFC-134a. It is considered the most promising alternative to automotive refrigerants and has been accepted by several major automakers. Its preparation routes include the following:

[0004] I. Hexafluoropropylene route:

[0005] The preparation of 2,3,3,3-tetrafluoropropylene from hexafluoropropylene involves four steps: (1) hydrogenation of hexafluoropropylene and hydrogen to prepare 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); (2) dehydrofluorination of HFC-236ea under the action of a catalyst to prepare 1,1,1,2,3-pentafluoropropylene (HFO-1225ye); (3) hydrogenation of HFO-1225ye with hydrogen to prepare 1,1,1,2,3-pentafluoropropane (HFC-245eb); and (4) dehydrofluorination of HFC-245eb under the action of a catalyst to prepare 2,3,3,3-tetrafluoropropylene.

[0006] US patent US20070179324A, Chinese patents CN101544536A, CN102267869A and CN102026947A all disclose a method for preparing 2,3,3,3-tetrafluoropropylene from hexafluoropropylene through a four-step reaction involving hydrogenation, dehydrofluorination, rehydrogenation and redehydrofluorination. This method is characterized by its simple process and mature technology. However, it involves many reaction steps and requires the separation and purification of various intermediate products, resulting in problems such as complex process steps, large equipment investment, low reaction yield, high separation cost and high energy consumption.

[0007] To address the shortcomings of the aforementioned patented technologies, Chinese patent CN103449963B discloses a method for synthesizing 2,3,3,3-tetrafluoropropylene via a multi-step continuous reaction using hexafluoropropylene as a raw material. This method enables the continuous production of intermediate products such as HFC-236ea, HFO-1225ye, and HFC-245eb without separation. However, the lack of separation and purification of intermediate products means that impurities will continuously accumulate and be added to the reactants, ultimately affecting the yield of the target product, 2,3,3,3-tetrafluoropropylene. It also increases the difficulty of distilling and separating the 2,3,3,3-tetrafluoropropylene product.

[0008] II. Tetrachloropropylene (TCP) route:

[0009] Patent CN101395108B discloses a method for preparing 2,3,3,3-tetrafluoropropylene using 1,1,2,3-tetrachloropropene as a raw material through a three-step reaction. The reaction steps include: (1) 1,1,2,3-tetrachloropropene and HF undergo a gas-phase fluorination reaction to prepare 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), with a selectivity of 80-96%. When using Cr2O3 and FeCl3 / C catalysts, the selectivity reaches 96%, and the conversion rate is only 20%; (2) HCFO-1233xf undergoes an addition reaction with HF to generate 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), with SbCl5 as the catalyst; (3) HCFC-244bb undergoes a gas-phase dehydrochlorination reaction under the action of an activated carbon catalyst to obtain the target product 2,3,3,3-tetrafluoropropylene. The process involves complex reaction steps, which is detrimental to industrial production, and also suffers from problems such as low conversion rate and high reaction temperature.

[0010] US Patent 20090099396 discloses a two-step method for preparing 2,3,3,3-tetrafluoropropylene from 1,1,2,3-tetrachloropropene as a raw material. The reaction steps include: (1) liquid-phase fluorination of 1,1,2,3-tetrachloropropene and HF to prepare 1,1,1,2,3-pentafluoropropane (HFC-245eb), with SbCl5 as the catalyst. The TCP conversion rate can reach 100%, but the selectivity of HFC-245eb is only 53-59%, and a large number of by-products are generated; (2) HFC-245eb undergoes liquid-phase defluorination under the action of alkali metal hydroxide to generate the target product 2,3,3,3-tetrafluoropropene. This process has the advantages of fewer reaction steps and less equipment investment, but the intermediate product HFC-245eb has low selectivity and the separation of by-products is difficult.

[0011] III. Trifluoropropylene Route:

[0012] Patent CN101979364A discloses a method for preparing 2,3,3,3-tetrafluoropropylene using 3,3,3-trifluoropropylene as a raw material. The reaction is carried out in four steps: (1) 3,3,3-trifluoropropylene reacts with chlorine under photocatalysis to generate 1,2-dichloro-3,3,3-trifluoropropane, with a raw material conversion rate of 95% and a selectivity of 90%; (2) 1,2-dichloro-3,3,3-trifluoropropane undergoes a liquid-phase dehydrochlorination reaction under the action of alkali metal hydroxide to generate 2-chloro-3,3,3-trifluoropropylene (HCFO- 1233xf), the conversion rate and selectivity both reached 90%; (3) HCFO-1233xf and HF underwent an addition reaction to generate 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), the catalysts were SnCl4 and TiCl4 fluorosulfonic acid, the raw material conversion rate reached 95%, and the selectivity was 90-96%; (4) HCFC-244bb underwent a liquid-phase dechlorination reaction under the action of an alkali metal catalyst to prepare the target product CF3CF=CH2, the raw material conversion rate was 95%, and the selectivity was 90-95%. The synthesis route of this process is long, the first step of the chlorination reaction has high equipment requirements, the two steps of the dehalogenation reaction generate a lot of waste liquid, the overall reaction yield is low, and the synthesis cost is high.

[0013] IV. Other routes:

[0014] Asahi Glass's patent WO2011162341A discloses a method for preparing 2,3,3,3-tetrafluoropropene from 1,1-dichloro-2,3,3,3-tetrafluoropropene (CFO-1214ya) via hydrogenation reduction in the presence of a palladium catalyst. However, this method is difficult to control the degree of hydrogenation reduction, easily generating intermediates or over-reduction products such as 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd), 1-chloro-2,3,3,3-tetrafluoropropane (HCFC-244eb), and 2,3,3,3-tetrafluoropropane (HFC-254eb). The product selectivity is low, post-processing is complex, and the byproduct HFC-254eb is prone to further dehydrofluorination during alkaline washing to generate 3,3,3-trifluoropropene (HFO-1243zf), which has a boiling point close to that of HFO-1234yf, further increasing the difficulty of impurity separation. Although the above problems can be improved by controlling the reaction temperature of the catalyst bed and the absorption temperature of the alkaline washing, the improvement is not significant, and the process conditions are difficult to control, making it unsuitable for industrial scale-up.

[0015] 1-Chloro-3,3,3-trifluoropropylene (HCFO-1233zd), with a boiling point of 19°C, an atmospheric lifetime of 26 days, an ODP value of approximately zero, and a GWP value of less than 5, is the preferred next-generation environmentally friendly foaming agent. It is suitable for foaming polyurethane insulation materials in home appliances, building insulation, cold chain transportation, and industrial insulation, and is the best alternative to CFCs, HCFCs, HFCs, and other non-fluorocarbon foaming agents. Compared with existing foaming agent systems (HFC-245fa and cyclopentane), it exhibits superior exothermic thermal conductivity and overall energy consumption, reducing thermal conductivity by 7% and 12% respectively compared to refrigerators using the same HFC-245fa and cyclopentane systems, and reducing overall energy consumption by 3% and 7% respectively.

[0016] PCT patent WO9724307A1 discloses a method for preparing HCFO-1233zd from 1,1,1,3,3-pentachloropropane (HCC-240fa) via a gas-phase fluorination reaction with hydrogen fluoride. This route is simple and is currently the main commercial production method. However, the reaction process produces various byproducts such as HCFC-242fa and HCFC-244fa, resulting in a low yield of HCFO-1233zd.

[0017] To address the issue of low yield of the aforementioned HCFO-1233zd product, US Patent 6844475A developed a method for preparing HCFO-1233zd by liquid-phase catalytic fluorination of HCC-240fa and HF. However, this method generates a large amount of heavy byproducts, oligomers, and tar during the process, and with the accumulation of reaction time, it leads to catalyst deactivation, thereby affecting the catalytic reaction efficiency.

[0018] Patent CN108383679A discloses a method for the co-production of HCFO-1233zd and HFO-1234yf. Using 1,1,1,3,3-pentachloropropane and 1,1,1,2,3-pentachloropropane as raw materials, the process first involves a fluorination reaction with hydrogen fluoride under the action of catalyst A to obtain trans-1-chloro-3,3,3-trifluoropropene, cis-1-chloro-3,3,3-trifluoropropene, and 2-chloro-3,3,3-trifluoropropene. These products, along with hydrogen chloride and hydrogen fluoride, are directly fed into a second reactor without separation, where they continue to react under the action of catalyst B, co-producing trans-1-chloro-3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene. This method is simple, efficient, and energy-saving, but its drawback is the difficulty in obtaining the raw material 1,1,1,2,3-pentachloropropane. Summary of the Invention

[0019] To address the aforementioned technical problems, this invention proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene, which is simple in process, has mild reaction conditions, and is suitable for industrial production.

[0020] The objective of this invention is achieved through the following technical solution:

[0021] A method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene, characterized in that: the co-production method includes:

[0022] A1. Telogenization step: 3-chloro-1,1,1,2-tetrafluoropropane is prepared by pressurized telogenization reaction of monofluorochloromethane and trifluoroethylene under the action of a telogenization catalyst; the telogenization catalyst is a Lewis acid catalyst or a mixed catalyst of Lewis acid catalyst and dichloromethane.

[0023] A2. Dehydrohalogenation step: 3-chloro-1,1,1,2-tetrafluoropropane undergoes both dehydrochlorination and dehydrofluorination reactions under the action of a composite dehalogenation catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The composite dehalogenation catalyst is prepared by reacting an oxide or fluoride of at least one of Al, Mg, or Cr with activated carbon powder.

[0024] The oxide or fluoride of at least one of Al, Mg or Cr is selected from at least one of Al2O3, AlF3, MgF2 and Cr2O3; the activated carbon powder is selected from coconut shell activated carbon, coal-based activated carbon or wood-based activated carbon.

[0025] The reaction equation for the co-production process of this invention is as follows:

[0026]

[0027] The Lewis acid catalyst of this invention is selected from at least one halide of Al, Sb, Ti, Zr, and Hf. Preferably, the Lewis acid catalyst is selected from at least one of ZrCl4, HfCl4, TiCl4, AlF3, AlCl3, and SbF5. More preferably, the Lewis acid catalyst is ZrCl4 or HfCl4.

[0028] The telomerization reaction of the raw materials monofluorochloromethane and trifluoroethylene in this invention is carried out under pressure. Under the reaction conditions, the raw material monofluorochloromethane partially or completely forms a liquid. In addition, the 3-chloro-1,1,1,2-tetrafluoropropane produced by the telomerization reaction is a liquid. Therefore, step A1 of this invention preferably adopts a solvent-free reaction to reduce the separation steps of intermediates and / or products.

[0029] The telomerization catalyst described in this invention can be a single Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane. When a mixed catalyst is used, the Lewis acid catalyst dissociates and activates monofluorochloromethane to form F...- CH2Cl + Cl - CH2F + Plasma; dichloromethane inhibits the formation of F2+ from dissociation. - CH2Cl + Cl - CH2F + Plasma recombines, thereby ensuring F - CH2Cl + Ions undergo a directional telomerization reaction with trifluoroethylene to selectively produce the telomerization product CF3CHFCH2Cl.

[0030] In chemical reactions, the ratio of raw materials, the ratio of raw materials to catalysts, reaction temperature, and reaction time all affect the reaction results. In particular, the combination of multiple variables can have a significant impact on the reaction outcome.

[0031] In the telomerization step described in this invention, the molar ratio of monofluorochloromethane to trifluoroethylene is 1:0.1 to 1:10; more preferably, the molar ratio of monofluorochloromethane to trifluoroethylene is 1:1 to 1:5. The amount of Lewis acid catalyst is 0.01 to 50 wt% of the mass of monofluorochloromethane; more preferably, the amount of Lewis acid catalyst is 0.1 to 10 wt% of the mass of monofluorochloromethane. When a mixed catalyst of Lewis acid catalyst and dichloromethane is used, the molar ratio of dichloromethane to monofluorochloromethane is 1:0.01 to 1:10; more preferably, the molar ratio of dichloromethane to monofluorochloromethane is 1:0.1 to 1:5.

[0032] The telomerization step described in this invention is carried out under pressure, with a reaction temperature of -30 to 100°C, a reaction pressure of 0.5 to 5.0 MPa, and a reaction time of 1 to 50 h. More preferably, the reaction temperature is 0 to 50°C, the reaction pressure is 0.8 to 3.0 MPa, and the reaction time is 5 to 10 h.

[0033] In the dehydrohalogenation step of this invention, under the action of a composite dehalogenation catalyst, when 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed on activated carbon, a dehydrochlorination reaction occurs; when 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed on Al2O3 and / or AlF3 and / or MgF2 and / or Cr2O3, a dehydrofluorination reaction occurs, thereby simultaneously obtaining 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene.

[0034] The composite dehalogenation catalyst of this invention can be prepared using conventional methods, as long as the composite dehalogenation catalyst of this invention can be obtained. Preferably, it is prepared using a co-mixing method, comprising the following steps:

[0035] B1. Mixing: Al2O3 and / or AlF3 and / or MgF2 and / or Cr2O3 are mixed with activated carbon powder at a mass ratio of (0.01:0.25):1 and thoroughly mixed by mechanical stirring or ball milling;

[0036] B2. Sieving: The mixture is sieved to remove unevenly mixed portions;

[0037] B3. Forming: The sieved material is fed into a tablet press for tableting.

[0038] B4. The shaped catalyst is dried to prepare the composite dehalogenation catalyst, such as Al2O3. 3- Catalysts such as AC, AlF3-AC, MgF2-AC, and Cr2O3-AC.

[0039] The B3 molding step can produce shapes such as columnar or sheet-like forms, and there are no restrictions on the specific shape.

[0040] In step B4, the drying process is generally carried out at 90℃~120℃ for more than 12 hours.

[0041] The composite dehalogenation catalyst of this invention, when Al2O3 is blended with activated carbon powder, has an Al2O3 content of 1.0–20 wt% of the total catalyst; when AlF3 is blended with activated carbon powder, has an AlF3 content of 1.0–20 wt% of the total catalyst; when MgF2 is blended with activated carbon, has an MgF2 content of 1.0–20 wt% of the total catalyst; and when Cr2O3 is blended with activated carbon, has a Cr2O3 content of 1.0–20 wt% of the total catalyst.

[0042] The dehydrohalogenation step described in this invention is a gas-solid phase reaction. 3-chloro-1,1,1,2-tetrafluoropropane is vaporized and then carried into the catalyst bed by nitrogen gas for the dehydrohalogenation reaction. The volume hourly space velocity (VHSV) of the feedstock for the dehydrohalogenation reaction is 50–300 h⁻¹. -1 The volume ratio of N2 / 3-chloro-1,1,1,2-tetrafluoropropane is (0.5-3.0):1, preferably (1.5-2.0):1.

[0043] The reaction temperature of the dehydrohalogenation step described in this invention is 300–500°C, preferably 350–450°C.

[0044] By adjusting the preparation process of the composite dehalogenation catalyst, the content of the active component in the catalyst, and the reaction conditions, the product distribution of the dehydrohalogenation step can be adjusted within a certain range. Generally, the dehydrohalogenation step yields 10–50% 2,3,3,3-tetrafluoropropene and 10–70% 1-chloro-3,3,3-trifluoropropene; preferably, the elimination step product contains 20–40% 2,3,3,3-tetrafluoropropene and 30–60% 1-chloro-3,3,3-trifluoropropene, with the remainder being unknown byproducts.

[0045] To further reduce the difficulty of post-processing, the 3-chloro-1,1,1,2-tetrafluoropropane obtained from the telomerization step is used for the dehydrohalogenation step after being separated by distillation.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] This invention uses monofluorochloromethane and trifluoroethylene as raw materials, and obtains 3-chloro-1,1,1,2-tetrafluoropropane through pressure polymerization under the action of Lewis acid catalyst or a mixed catalyst of Lewis acid catalyst and dichloromethane. Under the catalysis of a composite dehalogenation catalyst, 3-chloro-1,1,1,2-tetrafluoropropane undergoes both dehydrochlorination and defluorination reactions, co-producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. This method has the advantages of simple process, mild reaction conditions, and high yield of target products, making it suitable for industrial production. Detailed Implementation

[0048] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements and equivalents that may be included within the scope of the claims.

[0049] Preparation Example 1

[0050] This preparation example describes the preparation of a Cr2O3-AC blended catalyst of Cr2O3 and activated carbon powder. The preparation steps include:

[0051] S1. Mix Cr2O3 and coconut shell activated carbon powder at a mass ratio of 1 / 9, and then put the mixture into a ball mill for ball milling to mix the components evenly.

[0052] S2. The mixed material is sieved to remove unevenly mixed portions;

[0053] S3. After sieving, the material is fed into a tablet press for tableting to form columnar catalyst.

[0054] S4. The shaped catalyst was dried at 120℃ for 12h to prepare the Cr2O3-AC catalyst, denoted as cat1.

[0055] Preparation Example 2

[0056] The procedure in this preparation example is the same as in Preparation Example 1, except that AlF3 is used instead of Cr2O3 to prepare the AlF3-AC catalyst, denoted as cat2.

[0057] Preparation Example 3

[0058] The procedure in this preparation example is the same as in Preparation Example 1, except that the mass ratio of Cr2O3 to activated carbon is changed to 1 / 4, and a Cr2O3-AC catalyst is prepared, denoted as cat3.

[0059] Example 1

[0060] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene, including a telomerization step and a dehydrohalogenation step, as detailed below:

[0061] I. Aggregation Steps

[0062] A1. Using a 250mL Inconel alloy autoclave as the reactor, 3.0g HfCl4 and 20.0g dichloromethane were added to the autoclave respectively. After sealing the autoclave, nitrogen gas at a pressure of 1.0MPa or higher was introduced to replace the air in the autoclave. This process was repeated three times.

[0063] A2. After the air in the reactor is completely replaced, 19.9 g (0.29 mol) of monofluorochloromethane and 24.6 g (0.30 mol) of trifluoroethylene are introduced successively.

[0064] A3. Set the reaction temperature to 10℃, the stirring speed to 300rpm, the initial reaction pressure to 0.9MPa, and gradually reduce the pressure as the reaction proceeds. The reaction time is 10h.

[0065] A4. After the reaction is complete, collect the unreacted gaseous raw materials trifluoroethylene and / or monofluorochloromethane, as well as a small amount of telomerization products and dichloromethane; perform solid-liquid separation treatment such as filtration or distillation on the materials in the reactor. The solid part is Lewis acid catalyst (HfCl4), and the liquid part is dichloromethane and telomerization products. After distillation, 3-chloro-1,1,1,2-tetrafluoropropane with a purity of 99.9% is obtained and used in the dehydrohalogenation step.

[0066] Unreacted gaseous feedstocks can be separated, and the resulting Lewis acid catalyst can be returned to the telomerization step for reuse.

[0067] Gas chromatography was used to analyze the gas and liquid phase materials. The conversion rate of monofluorochloromethane was 76.5%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 81.2%, the main byproduct was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.3%, and there were a small amount of other byproducts.

[0068] II. Dehydrohalogenation Steps

[0069] B1. An Inconel alloy reaction tube with an inner diameter of 19 mm and a length of 800 mm was used as a fixed-bed reactor. 20 mL of cat1 was filled into the middle of the fixed-bed reactor, the reaction pipeline was connected, and nitrogen was introduced for purging at a flow rate of 100 mL / min.

[0070] B2. Set the reaction temperature to 350℃ and the heating rate to 5℃ / min, and start heating the reactor.

[0071] B3. After the catalyst bed reaches the reaction temperature, adjust the nitrogen flow rate to 20 mL / min, and simultaneously continuously introduce 3-chloro-1,1,1,2-tetrafluoropropane with a purity of 99.9% into the fixed-bed reactor at a rate of 5.0 g / h to start the reaction;

[0072] B4. The gas mixture exiting the reactor was treated with heat preservation and analyzed by online GC and GC / MS. The conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane reached 88.7%, the content of 2,3,3,3-tetrafluoropropene in the product reached 24.1%, and the content of 1-chloro-3,3,3-trifluoropropene reached 58.7%.

[0073] Example 2

[0074] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that: in the telomerization step, ZrCl4 is used instead of HfCl4, and the amount is 4.0 g; the amount of monofluorochloromethane is increased to 39.7 g (0.58 mol), and the amount of trifluoroethylene is increased to 71.3 g (0.87 mol), while other conditions remain unchanged.

[0075] Gas chromatography analysis of the gas and liquid phase materials in the polymerization step showed that the conversion rate of monofluorochloromethane was 99.0%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 89.9%, the main byproduct was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 5.3%, and there were also a small amount of other byproducts.

[0076] Example 3

[0077] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 2, except that dichloromethane is not used in the telomerization step, the amount of trifluoroethylene is increased to 95.1 g (1.16 mol), the reaction temperature is increased to 30 °C, the initial reaction pressure is increased to 1.5 MPa, and other conditions remain unchanged.

[0078] Gas chromatography analysis of the gas and liquid phase materials in the polymerization step showed that the conversion rate of monofluorochloromethane was 99.5%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.1%, the main byproduct was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 4.1%, and there were also a small amount of other byproducts.

[0079] Example 4

[0080] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 2, except that: in the telomerization step, AlCl3 is used instead of ZrCl4, and the amount remains the same at 4.0 g; at the same time, dichloromethane is not used, and the amount of trifluoroethylene is reduced to 52.5 g (0.64 mol), while other conditions remain unchanged.

[0081] Gas chromatography analysis of the gas and liquid phase materials in the polymerization step showed that the conversion rate of monochlorofluoromethane was 99.6%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 75.5%, the main byproduct was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.9%, and there were also a small amount of other byproducts.

[0082] Example 5

[0083] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that in step A2 of the polymerization step, after sequentially introducing monofluorochloromethane and trifluoroethylene into the autoclave, high-purity high-pressure nitrogen is used to pressurize the autoclave, increasing the pressure inside the autoclave from 0.9 MPa to 3.0 MPa, while keeping other conditions unchanged.

[0084] Gas chromatography analysis of the gas and liquid phase materials in the polymerization step showed that the conversion rate of monofluorochloromethane was 99.8%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.6%, the main byproduct was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 7.6%, and there were also a small amount of other byproducts.

[0085] Example 6

[0086] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that in the dehydrohalogenation step, cat2 is used instead of cat1.

[0087] Chromatographic analysis of the dehydrohalogenation reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 92.9%, the content of 2,3,3,3-tetrafluoropropene in the products was 20.3%, and the content of 1-chloro-3,3,3-trifluoropropene was 58.7%.

[0088] Example 7

[0089] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that the amount of cat1 is increased to 40 mL in the dehydrohalogenation step.

[0090] Chromatographic analysis of the dehydrohalogenation reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane exceeded 95.9%, and the content of 2,3,3,3-tetrafluoropropene in the products was 16.1%, while the content of 1-chloro-3,3,3-trifluoropropene was 44.6%.

[0091] Example 8

[0092] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that the reaction temperature is 450°C in the dehydrohalogenation step.

[0093] Chromatographic analysis of the dehydrohalogenation reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 98.3%, the content of 2,3,3,3-tetrafluoropropene in the products was 15.9%, and the content of 1-chloro-3,3,3-trifluoropropene was 60.0%.

[0094] Comparative Example 1

[0095] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that trichloromethane is used instead of dichloromethane, and the amount is 20g, while other conditions remain unchanged.

[0096] Chromatographic analysis of the material after the telomerization step showed that the conversion rate of monofluorochloromethane was 86.9%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 46.1%, a large amount of dichloromethane, a disproportionation product of monofluorochloromethane, was produced with a selectivity of 40.3%, and a small amount of other telomerization byproducts were also produced.

[0097] Comparative Example 2

[0098] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The operation is the same as in Example 1, except that ZnCl2 is used instead of HfCl4, and the amount is 3.0 g, while other conditions remain unchanged.

[0099] Chromatographic analysis of the material after the telomerization step showed that the conversion rate of monofluorochloromethane was 20.8%, and no target product 3-chloro-1,1,1,2-tetrafluoropropane was produced.

[0100] Comparative Example 3

[0101] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that HfCl4 and dichloromethane are not added, while other conditions remain unchanged.

[0102] Chromatographic analysis of the material after the polymerization step showed that the conversion rate of monofluorochloromethane was 7.6%, with no target product 3-chloro-1,1,1,2-tetrafluoropropane produced, and only a small amount of dichloromethane, a disproportionation product of monofluorochloromethane, produced.

[0103] Comparative Example 4

[0104] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that in the dehydrohalogenation step, pretreated coconut shell activated carbon (dried at 120°C for 12 h) is used instead of cat1, while other conditions remain unchanged.

[0105] Chromatographic analysis of the dehydrohalogenation reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane exceeded 99.7%, the content of 2,3,3,3-tetrafluoropropene in the products was 99.0%, and no 1-chloro-3,3,3-trifluoropropene was generated.

[0106] Comparative Example 5

[0107] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene. The operation is the same as in Example 1, except that a Pd / AC catalyst (Pd loading of 1 wt%) is used instead of cat1, while other conditions remain unchanged.

[0108] Chromatographic analysis of the dehydrohalogenation reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 83.5%, the content of 2,3,3,3-tetrafluoropropene in the products was 96.4%, the content of 1-chloro-2,3,3,3-tetrafluoropropene was 1.3%, and no 1-chloro-3,3,3-trifluoropropene was produced.

Claims

1. A method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene, characterized in that: The co-production preparation method includes: A1. Telogenization step: 3-chloro-1,1,1,2-tetrafluoropropane is prepared by pressurized telogenization reaction of monofluorochloromethane and trifluoroethylene in the presence of a telogenization catalyst; the telogenization catalyst is a mixed catalyst of Lewis acid catalyst and dichloromethane; the Lewis acid catalyst is selected from at least one of ZrCl4, HfCl4, TiCl4, AlF3, and AlCl3; A2. Dehydrohalogenation step: 3-chloro-1,1,1,2-tetrafluoropropane undergoes both dehydrochlorination and dehydrofluorination reactions under the action of a composite dehalogenation catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene; The composite dehalogenation catalyst is prepared by Cr2O3 or AlF3 and activated carbon powder.

2. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The molar ratio of monofluorochloromethane to trifluoroethylene is 1:0.1 to 1:

10.

3. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The Lewis acid catalyst is 0.01 to 50 wt% of monofluorochloromethane.

4. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The molar ratio of dichloromethane to monochlorofluoromethane is 1:0.01 to 1:

10.

5. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The pressurized polymerization reaction is carried out at a temperature of -30 to 100°C and a pressure of 0.5 to 5.0 MPa for a reaction time of 1 to 50 h.

6. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The activated carbon powder is selected from fruit shell activated carbon, coal-based activated carbon, or wood-based activated carbon.

7. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The content of AlF3 is 1.0 to 20 wt% of the total catalyst, and the content of Cr2O3 is 1.0 to 20 wt% of the total catalyst.

8. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: 3-Chloro-1,1,1,2-Tetrafluoropropane is vaporized and then carried by nitrogen into a catalyst bed for dehydrohalogenation. The volume hourly space velocity (VHSV) of the dehydrohalogenation reaction is 50–300 h⁻¹. -1 The volume ratio of N2 / 3-chloro-1,1,1,2-tetrafluoropropane is (0.5~3.0):

1.

9. The method for co-producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene according to any one of claims 1-8, characterized in that: The dehydrohalogenation step yields 10–50% 2,3,3,3-tetrafluoropropylene and 10–70% 1-chloro-3,3,3-trifluoropropylene.

10. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The composite dehalogenation catalyst is prepared by a co-mixing method, including the following steps: B1. Mixing: AlF3 or Cr2O3 and activated carbon powder are mixed at a mass ratio of (0.01 to 0.25):1 by mechanical stirring or ball milling. B2. Sieving: The mixture is sieved to remove unevenly mixed portions; B3. Forming: The sieved material is fed into a tablet press for tableting. B4. The shaped catalyst is dried to prepare the composite dehalogenation catalyst.

11. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The reaction temperature for the dehydrohalogenation step is 300–500 °C.

12. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-3,3,3-trifluoropropylene according to claim 1, characterized in that: The 3-chloro-1,1,1,2-tetrafluoropropane obtained through the telomerization step was used for the dehydrohalogenation step after being separated by distillation.

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