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

Abstract

A method for co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, 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 removal step: 3-chloro-1,1,1,2-tetrafluoropropane simultaneously undergoes dehydrochlorination and dehydrogenation reactions in the presence of an activated carbon-supported noble metal catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene; the activated carbon-supported noble metal catalyst is at least one of Pd / AC and Pt / AC. The present application has the advantages of simple process, mild reaction conditions, high yield of target product, etc.

Description

[0001] This invention is a divisional application of Chinese invention patent application filed on April 15, 2021, with application number CN202110404622.0 and invention title “Method for Co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene”. Technical Field

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

[0003] 2,3,3,3-Tetrafluoropropylene (HFO-1234yf) has an ODP of zero and a GWP of 4. Its life-cycle climate performance (LCCP) is lower than that of the traditional refrigerant HFC-134a, while its system refrigeration performance is superior to HFC-134a. Its atmospheric decomposition products are the same as HFC-134a, making it considered the most promising alternative to automotive refrigerants and it has been accepted by several major automakers. 1-Chloro-2,3,3,3-Tetrafluoropropylene (HCFO-1224yd) has an ODP of zero and a GWP of less than 1. It exhibits good chemical stability and excellent refrigeration performance, making it suitable for use in air conditioning, refrigerators, and other refrigeration systems, as well as as a fire extinguishing agent.

[0004] 2,3,3,3-Tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene are both high-performance refrigerants, and are currently mostly produced industrially by their respective manufacturers. The preparation routes for 2,3,3,3-tetrafluoropropene include the following:

[0005] I. Hexafluoropropylene route:

[0006] 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.

[0007] 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.

[0008] 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.

[0009] II. Tetrachloropropylene (TCP) route:

[0010] 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.

[0011] 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.

[0012] III. Trifluoropropylene Route:

[0013] 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.

[0014] IV. Other routes:

[0015] 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.

[0016] The following are publicly reported methods for preparing HCFO-1224yd in the prior art:

[0017] Asahi Glass's patent WO2017146189A discloses a method for preparing HCFO-1224yd by hydrogenation reduction of 1,1-dichloro-2,3,3,3-tetrafluoropropene (CFO-1214ya). This method improves the selectivity of the target product HCFO-1224yd by suppressing the formation of byproducts (HFO-1234yf, HFC-254eb, and other over-reduction products) through modifying the catalyst formulation, reducing the amount of hydrogen, and controlling the catalyst bed temperature. Specifically, the molar ratio of hydrogen to CFO-1214ya (H2 / 1214ya) is controlled below 1.4, and can even be below 1.0, but considering the yield of product 1224yd, H2 / 1214ya needs to be higher than 0.4; the catalyst bed temperature is controlled below 130°C; and a catalyst with a specific surface area of ​​less than 40 m² is used. 2 The palladium catalyst (supported on activated carbon) exhibited good catalytic activity, stability, and product selectivity. However, the selectivity of the main product HCFO-1224yd was still below 20%.

[0018] Asahi Glass's patent WO2018030408A discloses that in the hydrogenation reduction process of CFO-1214ya, adding an appropriate amount of chloride ions to a palladium catalyst can promote catalytic activity, stability and product selectivity, but the final selectivity of HCFO-1224yd is still less than 30%.

[0019] Komtech patent CN106573857A discloses a method for reacting compound CF3CF2CHXCl, where X is H or Cl, or compound CF3CF=CXCl, where X is H or Cl, with hydrogen in the presence of a catalyst essentially composed of Cu, Ru, Cu-Pd, Ni-Cu, and Ni-Pd, to obtain reaction products containing hydrofluoropropylene or intermediates that can be converted into said hydrofluoropropylene. For example, in the presence of a Cu-Pb / C catalyst, the reaction of the feedstock HCFC-225ca with hydrogen at 125–160°C can directly yield HCFO-1224yd, but at the same time, a large amount of over-hydrogenation products HFO-1234yf and HCFC-235cb are also produced, and the target product HCFO-1224yd exists only as a byproduct.

[0020] The above-mentioned method for preparing HCFO-1224yd by hydrogenation reduction has low product selectivity. The reaction products contain a variety of byproducts, such as 1-chloro-1,2,2,3,3,3-hexafluoropropane, 1-chloro-1,1,2,2,3,3-hexafluoropropane, 1-chloro-1,3,3,3-tetrafluoropropene, and 2-chloro-1,3,3,3-tetrafluoropropene. These byproducts have similar properties, making it difficult to effectively remove these impurities using ordinary distillation, which increases the difficulty of post-processing.

[0021] Currently, there are few reports on the co-production process of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. Only Asahi Glass's patent WO2019003896A1 mentions a method for preparing HFO-1234yf using 2,3,3-trichloro-1,1,1,2-tetrafluoropropane (HCFC-224ba) as a raw material. The method involves first obtaining CFO-1214ya through a dehydrochlorination reaction, and then obtaining HCFO-1224yd and HFO-1234yf through a hydrogenation dechlorination reaction. However, the patent does not disclose specific reaction data. Furthermore, HCFC-224ba is mainly prepared through the telomerization reaction of dichlorofluoromethane and trichlorofluoroethylene. However, this reaction has low selectivity, and the telomerization product contains several isomers of tetrafluorotrichloropropane, namely 1,3,3-trichloro-1,1,2,2-tetrafluoropropane (HCFC-224ca), 1,2,3-trichloro-1,1,2,3-tetrafluoropropane (HCFC-224bb), and 1,1,3-trichloro-1,2,2,3-tetrafluoropropane (HCFC-224cb). Among them, HCFC-224ca is the main product, with a content of about 60%, while the target product HCFC-224ba has a content of less than 20%. In addition, these four isomers have similar boiling points, all in the range of 90-92℃, making them difficult to separate and purify. Summary of the Invention

[0022] To address the aforementioned technical problems, this invention proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene, which is simple in process, has mild reaction conditions, and is suitable for industrial production.

[0023] The objective of this invention is achieved through the following technical solution:

[0024] A method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, characterized in that: the co-production method includes:

[0025] 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.

[0026] A2. Removal step: 3-chloro-1,1,1,2-tetrafluoropropane undergoes both dehydrochlorination and dehydrogenation reactions under the action of an activated carbon-supported noble metal catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The activated carbon-supported noble metal catalyst is at least one of Pd / AC and Pt / AC.

[0027] The reaction equation for the co-production process of this invention is as follows:

[0028]

[0029] 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.

[0030] 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.

[0031] 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, yielding the telomerization product CF3CHFCH2Cl with high selectivity.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In the removal step described in this invention, under the action of a noble metal catalyst supported on activated carbon, when the raw material 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed on activated carbon, a dehydrochlorination reaction occurs; when the raw material 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed on the noble metal sites on activated carbon, a dehydrogenation reaction occurs, thereby simultaneously obtaining 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene.

[0036] The activated carbon-supported noble metal catalyst can be prepared using conventional methods, as long as the activated carbon-supported noble metal catalyst of this invention can be obtained. Preferably, this invention uses an impregnation method, comprising the following steps:

[0037] B1. Carrier pretreatment: Activated carbon is dried at 90-120℃ for more than 12 hours;

[0038] B2. Metal salt impregnation: Pretreated activated carbon is impregnated with a soluble salt solution of Pd or Pt under vacuum or normal pressure conditions;

[0039] B3. Dry the impregnated activated carbon at a temperature of 90-120℃ for at least 12 hours.

[0040] B4. The dried activated carbon is reduced with a hydrogen-nitrogen mixture to obtain the activated carbon-supported noble metal catalyst; the volume ratio of hydrogen in the hydrogen-nitrogen mixture is 5-50%, and the reduction temperature is 150-300℃.

[0041] In the activated carbon-supported noble metal catalyst, the loading of Pd and Pt is 0.1 to 5.0 wt%, preferably 0.5 to 1.5 wt%.

[0042] The removal step described in this invention is a gas-solid phase reaction. 3-chloro-1,1,1,2-tetrafluoropropane is vaporized and then carried into a catalyst bed by nitrogen gas for the removal reaction. The volume hourly space velocity (VHSV) of the material in the removal 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 removal step described in this invention is 300-600°C, preferably 400-450°C.

[0044] By adjusting the preparation process of the activated carbon-supported noble metal catalyst, the amount of noble metal loaded in the catalyst, and the reaction conditions, the product distribution of the A2 removal step can be adjusted within a certain range. Generally, the A2 removal step yields 30-90% 2,3,3,3-tetrafluoropropene and 10-50% 1-chloro-2,3,3,3-tetrafluoropropene; preferably, the product of the removal step contains 50-60% 2,3,3,3-tetrafluoropropene and 30-50% 1-chloro-2,3,3,3-tetrafluoropropene, with the remainder being byproducts, such as 1-chloro-3,3,3-trifluoropropene.

[0045] To further reduce the difficulty of post-processing, the 3-chloro-1,1,1,2-tetrafluoropropane obtained from the polymerization step is separated by distillation and then used for the removal step.

[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 noble metal catalyst supported on activated carbon, 3-chloro-1,1,1,2-tetrafluoropropane undergoes both dehydrochlorination and dehydrogenation reactions, co-producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. This method has advantages such as simple process and mild reaction conditions, and two products can be obtained using a single process, 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] Take 6.0 mL of chloropalladium acid solution (concentration of 0.033 g Pd / mL) and dilute it evenly with 80.0 mL of distilled water. Take 20.0 g of pretreated activated carbon (dried at 120℃ for 12 h) and add it to the above impregnation solution. Impregnate for more than 12 h and then dry at 120℃ for 12 h to obtain 1% wt. Pd / AC catalyst, denoted as cat1.

[0051] Preparation Example 2

[0052] Take 9.2 mL of chloropalladium acid solution (concentration of 0.033 g Pd / mL) and dilute it evenly with 80.0 mL of distilled water. Take 20.0 g of pretreated activated carbon (dried at 120℃ for 12 h) and add it to the above impregnation solution. Impregnate for more than 12 h and then dry at 120℃ for 12 h to obtain a 1.5 wt.% Pd / AC catalyst, denoted as cat2.

[0053] Preparation Example 3

[0054] Take 0.35g of PtCl4 and dissolve it in 80.0mL of distilled water. Take 20.0g of pretreated activated carbon (dried at 120℃ for 12h) and add it to the above impregnation solution. Impregnate for more than 12h and then dry at 120℃ for 12h to obtain 1wt.% Pt / AC catalyst, denoted as cat3.

[0055] Preparation Example 4

[0056] Take 0.52g of PtCl4 and dissolve it in 80.0mL of distilled water. Take 20.0g of pretreated activated carbon (dried at 120℃ for 12h) and add it to the above impregnation solution. Impregnate for more than 12h and then dry at 120℃ for 12h to obtain 1.5wt.% Pt / AC catalyst, denoted as cat4.

[0057] Example 1

[0058] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene, including a polymerization step and a removal step, as detailed below:

[0059] I. Aggregation Steps

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 for the removal step.

[0064] Unreacted gaseous feedstock and the separated Lewis acid catalyst can be returned to the telomerization step for reuse.

[0065] 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.

[0066] II. Removal Steps

[0067] 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.

[0068] B2. Set the reaction temperature to 450℃ and the heating rate to 5℃ / min. The reactor starts heating.

[0069] B3. After the catalyst bed reaches the reaction temperature, the nitrogen flow rate is adjusted to 20 mL / min, and at the same time, 3-chloro-1,1,1,2-tetrafluoropropane with a purity of 99.9% is continuously introduced into the fixed bed reactor at a rate of 5.0 g / h using a peristaltic pump to start the reaction;

[0070] 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 was 96.8%, and the content of 2,3,3,3-tetrafluoropropene in the product was 56.3% and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 31.4%.

[0071] Example 2

[0072] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. 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.

[0073] 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.

[0074] Example 3

[0075] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. 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.

[0076] 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.

[0077] Example 4

[0078] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. 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 4g; at the same time, dichloromethane is not used, and the amount of trifluoroethylene is reduced to 52.5g (0.64mol), while other conditions remain unchanged.

[0079] 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.

[0080] Example 5

[0081] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. The operation is the same as in Example 1, except that in step A2 of the polymerization step, monofluorochloromethane and trifluoroethylene are introduced into the autoclave beforehand, and 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.

[0082] 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.

[0083] Example 6

[0084] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. The operation is the same as in Example 1, except that in the removal step, cat3 is used instead of cat1.

[0085] Chromatographic analysis of the removal reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 89.3%, the content of 2,3,3,3-tetrafluoropropene in the products was 90.3%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 7.7%.

[0086] Example 7

[0087] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The operation is the same as in Example 1, except that the amount of cat1 used in the removal step is increased to 40 mL.

[0088] Chromatographic analysis of the removal reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 95.8%, the content of 2,3,3,3-tetrafluoropropene in the products was 65.7%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 26.8%.

[0089] Example 8

[0090] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. The operation is the same as in Example 1, except that in the removal step, cat2 is used instead of cat1.

[0091] Chromatographic analysis of the removal reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 70.1%, the content of 2,3,3,3-tetrafluoropropene in the products was 39.2%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 28.5%.

[0092] Example 9

[0093] This embodiment proposes a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. The operation is the same as in Example 1, except that the reaction temperature is 400℃ in the removal step.

[0094] Chromatographic analysis of the removal reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 96.7%, the content of 2,3,3,3-tetrafluoropropene in the products was 85.2%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 10.3%.

[0095] Comparative Example 1

[0096] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The operation is the same as in Example 1, except that chloroform is used instead of dichloromethane, and the amount is 20.0 g, while other conditions remain unchanged.

[0097] 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 46.2%, 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.

[0098] Comparative Example 2

[0099] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. 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.

[0100] 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.

[0101] Comparative Example 3

[0102] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. The operation is the same as in Example 1, except that HfCl4 and dichloromethane are not added, while other conditions remain unchanged.

[0103] Chromatographic analysis of the material after the polymerization step showed that the conversion rate of monofluorochloromethane was 7.7%, 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.

[0104] Comparative Example 4

[0105] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene. The operation is the same as in Example 1, except that in the removal step, pretreated activated carbon (dried at 120°C for 12 h) is used instead of cat1, while other conditions remain unchanged.

[0106] Chromatographic analysis of the removal reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 99.7%, the content of 2,3,3,3-tetrafluoropropene in the products was 99.0%, and no 1-chloro-2,3,3,3-tetrafluoropropene was generated.

[0107] Comparative Example 5

[0108] This comparative example presents a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The operation is the same as in Example 1, except that Al2O3 is used instead of cat1, while other conditions remain unchanged.

[0109] Chromatographic analysis of the removal reaction products showed that the conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 50.1%, the content of 2,3,3,3-tetrafluoropropene in the products was 3.1%, the content of 1-chloro-3,3,3-trifluoropropene was 62.2%, and no 1-chloro-2,3,3,3-tetrafluoropropene was produced.

Claims

1. A method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, 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. Removal step: 3-chloro-1,1,1,2-tetrafluoropropane undergoes both dehydrochlorination and dehydrogenation reactions under the action of an activated carbon-supported noble metal catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The activated carbon-supported noble metal catalyst is at least one of Pd / AC and Pt / AC.

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

10.

5. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene 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-2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The activated carbon-supported noble metal catalyst is prepared by impregnation method, including the following steps: B1. Carrier pretreatment: Activated carbon is dried at 90-120℃ for more than 12 hours; B2. Metal salt impregnation: Pretreated activated carbon is impregnated with a soluble salt solution of Pd or Pt under vacuum or normal pressure conditions; B3. Dry the impregnated activated carbon at a temperature of 90-120℃ for at least 12 hours. B4. The dried activated carbon is reduced with a hydrogen-nitrogen mixture to obtain the activated carbon-supported noble metal catalyst; the volume ratio of hydrogen in the hydrogen-nitrogen mixture is 5-50%, and the reduction temperature is 150-300℃.

7. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: In activated carbon-supported noble metal catalysts, the loading of Pd and Pt is 0.1–5.0 wt%, and after an A2 removal step, 2,3,3,3-tetrafluoropropylene containing 30–90% and 10–50% of 1-chloro-2,3,3,3-tetrafluoropropylene are obtained.

8. The method for co-producing 2,3,3,3-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: 3-Chloro-1,1,1,2-Tetrafluoropropane is vaporized and then carried by nitrogen into the catalyst bed for a removal reaction. The volume hourly space velocity (VHSV) of the material in the removal 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-tetrafluoropropylene and 1-chloro-2,3,3,3-tetrafluoropropylene according to claim 1, characterized in that: The reaction temperature for the removal step is 300–600°C.

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

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