Method for preparing 1-chloro-2, 3, 3-trifluoropropene through resource utilization of 1, 1, 2-trifluoroethane

Abstract

The invention discloses a method for preparing 1-chloro-2, 3, 3-trifluoropropene through resource utilization of 1, 1, 2-trifluoroethane, which comprises the following steps: (1) dehydrofluorination: 1, 1, 2-trifluoroethane is subjected to a dehydrofluorination process under the action of a gas-phase dehydrofluorination catalyst to obtain 1, 2-difluoroethylene; (2) telomerization: under the combined action of the prefluorinated telomerization catalyst, the accelerant and the polar aprotic solvent, telomerization is performed on the 1, 2-difluoroethylene and the dichlorofluoromethane to obtain 3, 3-dichloro-1, 1, 2-trifluoropropane; and (3) a dehydrochlorination step: carrying out dehydrochlorination on the 3, 3-dichloro-1, 1, 2-trifluoropropane to obtain the 1-chloro-2, 3, 3-trifluoropropene. The method has the advantages of easily available raw materials, high product selectivity, high purity, easiness in separation, suitability for industrial application and the like.

Description

Technical Field

[0001] The present invention relates to the preparation of fluorochloroolefins, and particularly to a method for preparing 1-chloro-2,3,3-trifluoropropene by three-step reactions of dehydrofluorination, telomerization and dehydrochlorination in sequence using by-product 1,1,2-trifluoroethane as a raw material. Background Art

[0002] 1,1,2-Trifluoroethane (HFC-143) is a by-product of the hydrodechlorination of chlorotrifluoroethylene (CTFE) to prepare trifluoroethylene (TrFE). At present, it is mostly burned in the fluorochemical industry chain. There are also studies on the resource utilization of HFC-143. For example, as proposed in patent WO2019216175A1, the HFC-143 by-product can be converted into 1,2-difluoroethylene (HFO-1132). The conversion rate of HFC-143 after 1 hour of reaction and the selectivity of HFO-1132 can reach 89% and 90% respectively. However, the Cr-based catalyst used in the reaction has high toxicity, and the catalyst conversion rate drops rapidly to 52% after 10 hours of reaction. It is necessary to delay carbon deposition deactivation through an oxygen atmosphere, but other by-products may be brought. In order to further highlight the use value of this by-product, improve the catalyst stability, extend the value chain of by-product utilization, and realize the co-production of multiple new environmentally friendly fluorinated olefin refrigerants, it is still necessary to further broaden its application scenarios.

[0003] 1-Chloro-2,3,3-trifluoropropene (abbreviation: HCFO-1233yd) has two cis-trans isomers. Among them, cis-HCFO-1233yd (Z) (boiling point 54 °C) and trans-HCFO-1233yd (E) (boiling point 48 °C), its ozone depletion potential (ODP) is close to 0, the atmospheric lifetime is about 2.3 days, GWP 100 = 0.016, has no flash point, the surface tension and viscosity are also very low, has good compatibility with mineral oil, has excellent physical and chemical properties, and has great application prospects in application fields such as cleaning agents, refrigerants, foaming agents, aerosols, insulating materials and flame retardants.

[0004] At present, the synthesis research of HCFO-1233yd mainly includes the following three routes:

[0005] I. Two-step route of chlorination and dehydrofluorination of tetrafluoropropanol

[0006] The patents of Daikin, CN107250088A, and AGC, CN201680044085, disclose a method for producing HCFO-1233yd(Z / E) by taking tetrafluoropropanol as a raw material, generating HCFC-244ca through a chlorination reaction, and then preparing it by dehydrofluorination. The dehydrofluorination reaction can be carried out in both the liquid phase and the gas phase, preferably in the liquid phase. In the gas-phase process with activated carbon as the catalyst, the conversion rate of the raw material is only 0.79%. In the liquid-phase process, an alkaline aqueous solution is formed by potassium hydroxide, water, and quaternary ammonium salt, and the reaction is carried out at 100 °C for 8 hours. The conversion rate of HCFC-244ca is 90%, the selectivity of 1233yd is 94.8%, and there are also 1.6% of 1-chloro-3,3-difluoropropyne, 2.1% of 1233zb, and 0.2% of 244fa.

[0007] However, the starting raw material tetrafluoropropanol in this process is flammable and has a relatively high cost. Among the reaction end products, the boiling points of HCFO-1233yd(Z) (boiling point 54 °C), HCFO-1233yd(E) (boiling point 48 °C), and the by-products 3-chloro-1,1,2-trifluoropropene (HCFO-1233yc, boiling point around 42 °C), 1-chloro-1,3,3-trifluoropropene (HCFO-1233zb, boiling point around 47 °C), etc., are similar, and their relative volatilities are close to 1, making it easy to form an azeotrope-like mixture and difficult to separate and purify by conventional distillation, resulting in an increase in production costs.

[0008] II. Two-step fluorination route of 1,1,2,3,3-pentachloropropane (HCC-240da)

[0009] The patent of Zibo Leima International Trade Co., Ltd., CN112125776A, discloses a method for obtaining HCFO-1233yd by taking 1,1,2,3,3-pentachloropropane (HCC-240da) as the starting raw material through two-step fluorination, specifically including: (1) Under the action of a chromium-based catalyst, HCC-240da is fluorinated by hydrogen fluoride to obtain 1,2-dichloro-3,3-difluoropropene (HCFO-1232aa); (2) Under the co-catalysis of a chromium-based catalyst treated with hydrogen fluoride as the main catalyst and at least one of Zn, Co, Ni, and Cu as the co-catalyst, it is fluorinated again to obtain HCFO-1233yd. The reaction temperature in step (1) is 275 °C, the space velocity is 240 h -1 、HF:HCC-240da = 15:1, the conversion rate of HCC-240da is 99.6%, and the selectivity of HCFO-1232aa is 90.4%; when the reaction temperature in step (2) is 350 °C, the space velocity is 220 h -1 、HF:HCC-240da = 4:1, the conversion rate of HCFO-1232aa is 65.16%, and the selectivity of HCFO-1233yd is 70.58%.

[0010] However, the starting material of the reaction, 1,1,2,3,3-pentachloropropane (HCC-240da), is a national key controlled elimination substance and cannot be obtained through procurement. It must be prepared by itself (such as by polymerization of trichloromethane and dichloroethylene), which makes the reaction route too long. Both fluorination steps use hydrogen fluoride as the fluorination reagent, which is not only highly corrosive, but also a gas at room temperature. The reaction process requires precise control of the HF / HCC-240da feed ratio to obtain the highly selective intermediate HCFO-1232aa, which is difficult to operate in the industry.

[0011] 3. Five-step process using dichloroethylene and chloroform as raw materials

[0012] AGC patent WO2019189024A discloses a method for obtaining HCFO-1233yd by using dichloroethylene and chloroform as starting materials through a five-step reaction. The method specifically comprises the following steps: (1) 240da is telomerized with dichloroethylene and chloroform under the action of a telomerization catalyst; (2) 240da is dehydrochlorinated under the action of an alkali solution to obtain 1230xd; (3) 1230xd is fluorinated under the action of a gas-phase fluorine-chlorine exchange reaction catalyst to obtain 1232xd; (4) 1232xd is fluorinated under the action of a fluorination catalyst to obtain 1,2-dichloro-2,3,3-trifluoropropane (HCFC-243ba); (5) HCFC-243ba is dehydrochlorinated under the action of an alkali solution to obtain HCFO-1233yd. Specifically, step (1) under the action of AlCl3, 40-45°C telomerization reaction for 28h to obtain 240da, 240da yield of 87.6%; step (2) 48wt% NaOH base catalyst, 19.8g TBAB (tetrabutylammonium bromide, phase shift agent), 50°C, 2.5h to obtain 99.9% purity 1230xd product; step (3) SbF3 fluorine-chlorine exchange catalyst, 130°C gas phase fluorine-chlorine exchange reaction to obtain 53% yield of 1232xd product The product is obtained by using a fluorination catalyst of SbCl5, 80-90°C, 0.95MPa, and reacting for 5h to obtain a 243ba product with a yield of 35.6%. The product is dehydrochlorinated by a liquid phase method at 50°C using a 40% KOH base catalyst, 1.01g TBAC (tetrabutylammonium chloride, a phase shift catalyst), and a conversion rate of 243ba of 98.2%, and the selectivities of HCFO-1233yd (Z) and HCFO-1233yd (E) are 94.2% and 5.7%, respectively. However, the method adopts a five-step method to obtain HCFO-1233yd (Z), which has a long process route and is difficult to control the reaction conditions. The actual yield of the intermediate 243ba prepared by the four-step method in the reaction steps (1) to (4) is only about 35%.

[0013] Therefore, from the perspective of industrialization, in the above three process routes, the raw materials are either difficult to obtain or the operation is relatively difficult, and they do not have the operability and economy for large-scale production. Summary of the Invention

[0014] To solve the above technical problems, the present invention provides a method for preparing 1-chloro-2,3,3-trifluoropropene, which has easily available raw materials, high product selectivity, high purity and easy separation, and is particularly suitable for industrial production.

[0015] The object of the present invention is achieved by the following technical solutions:

[0016] A method for preparing 1-chloro-2,3,3-trifluoropropene, the preparation method comprising:

[0017] (1) Dehydrofluorination step: 1,1,2-trifluoroethane (HFC-143) undergoes a gas-phase HF elimination reaction under the action of a dehydrofluorination catalyst to obtain 1,2-difluoroethylene (HFO-1132). The catalyst is a multi-component composite A-B / α-AlF3 catalyst composed of a carrier, an auxiliary component A, and an active component B. The reaction formula is as follows:

[0018]

[0019] (2) Telomerization step: Under the combined action of a pre-fluorinated telomerization catalyst, a promoter, and a polar aprotic solvent, 1,2-difluoroethylene (HFO-1132) and dichlorofluoromethane (R21) undergo a telomerization reaction to obtain 3,3-dichloro-1,1,2-trifluoropropane. The reaction formula is as follows:

[0020]

[0021] (3) Dehydrochlorination step: 3,3-dichloro-1,1,2-trifluoropropane undergoes a liquid-phase or gas-phase elimination of one hydrogen chloride under the action of a dehydrochlorination catalyst to obtain 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd). The reaction formula is as follows:

[0022]

[0023] In step (1), the catalyst carrier is α-type AlF3; the auxiliary component A is at least one selected from Pt, Pd, Ru, and Rh; the active component B is at least one selected from V, Fe, Ni, Co, Ce, Pr, W, etc.; preferably, the catalyst auxiliary component A is at least one of Pd and Ru, and the catalyst active component B is at least one of Fe, Ni, and Pr.

[0024] In step (1), the loading amount of the catalyst promoter component A is 0.01% to 2.0%, the loading amount of the active component B is 1% to 20%, and the rest is the carrier.

[0025] In step (1), the catalyst carrier α-AlF3 is in the form of nano-spherical particles with a specific surface area of ​​159 m 2 .g -1 , pore volume up to 0.48cm 3 .g -1 The average pore size is 15.5nm, and the surface of the mesoporous structure is rich in weak acid or medium-strength Lewis acid.

[0026] In step (1), the dehydrofluorination catalyst preparation method specifically includes: a carrier preparation step, an auxiliary component A vacuum impregnation step, an auxiliary component A hydrogen reduction step, an active component B vacuum impregnation step, and a catalyst pre-fluorination step.

[0027] In step (1), the raw material 1,1,2-trifluoroacetic acid enters the reactor after passing through a mass flow meter and a vaporizer, the reaction temperature is 300-500°C, and the raw material space velocity is 100-800h -1 The reaction time is 1 to 100 hours. The reaction is carried out in a tubular reactor made of corrosion-resistant Monel 400 or Inconel 600.

[0028] The 1,2-difluoroethylene obtained in step (1) is cis-1,2-difluoroethylene and / or trans-1,2-difluoroethylene.

[0029] In step (1), in a preferred embodiment, the AB / α-AlF3 catalyst is prepared by the following steps:

[0030] S1. The carrier preparation method is a modified sol-gel method, comprising the following steps:

[0031] A1. Weigh the metal organic alkoxide precursor into a PTFE tank, and add 200 ml of anhydrous ethylene glycol and 20 ml of polyethylene glycol respectively;

[0032] A2. The mixture was placed in a PTFE tank at -10 to -20 °C low temperature circulation tank and stirred at low temperature. At the same time, the prepared 20 wt% HF solution was added dropwise to the solution and stirred for 8 to 12 hours. After stirring at 80 °C for 6 hours, the mixture was filtered and centrifuged, and dried at 120 °C to obtain a yellow block catalyst precursor.

[0033] A3. The yellow block catalyst precursor is calcined at 300-500°C in an air atmosphere for 3-5 hours to obtain the metal fluoride carrier α-AlF3.

[0034] S2. Vacuum impregnation of promoter component A: Place the beaker containing the carrier in a vacuum vessel, and evacuate the system pressure to about -0.05 to -0.06 MPa; Weigh the precious metal chloride according to the loading amount, add an appropriate amount of 0.1 mol / L dilute hydrochloric acid and deionized water, and dropwise add the fully dissolved precious metal chloride aqueous solution onto the carrier surface at a rate of 0.5 to 5 ml / min through a micro-injection pump. After impregnation, dry it at 120 °C for 6 to 10 h.

[0035] S3. Hydrogen reduction of promoter component A: Transfer the catalyst obtained in S2 to a hydrogen reduction reaction furnace, and reduce it at 200 to 350 °C for 1 to 3 h in a reducing atmosphere of N2 / H2 = 2:1 to 4:1 to obtain the A / α-AlF3 catalyst.

[0036] S4. Vacuum impregnation of active component B: Weigh the precursor of the second active component according to the loading amount, add an appropriate amount of deionized water to dissolve it evenly, and then dropwise add the precursor aqueous solution onto the catalyst surface obtained in step S3 at a rate of 0.5 to 5 ml / min under a negative pressure system of -0.05 to -0.06 MPa. After impregnation, dry it at 120 °C for 6 to 10 h and calcine it at 400 to 550 °C for 2 to 4 h.

[0037] S5. Catalyst pre-fluorination: Pretreat it at 200 to 300 °C for 1 to 3 h in an atmosphere of N2 / HF = 2:1 to 3:1; Pretreat it at 300 to 400 °C and in an atmosphere of anhydrous HF for 2 to 5 h to obtain the A-B / α-AlF3 catalyst.

[0038] In step (2), the telomerization catalyst is a supported Lewis acid catalyst, the carrier is coal-based activated carbon pretreated with acid and alkali, and the catalyst is selected from at least one of AlCl3 / AC, GaCl3 / AC, ZrCl4 / AC, and SnCl4 / AC; The loading amount of the active component of the supported Lewis acid catalyst is 5 to 20%.

[0039] In step (2), the telomerization catalyst needs to be pre-fluorinated with at least one halogenated alkane such as dichlorofluoromethane, chlorofluoromethane, and trifluoromethane at a temperature of 200 to 300 °C for 2 to 3 h before the reaction, so that part of the catalyst surface forms chlorofluoride to improve the catalyst stability.

[0040] In step (2), in order to reduce the disproportionation reaction of the telogen during the telomerization reaction to produce other by-products, an appropriate amount of accelerator is added in the reaction process of the present invention to inhibit the disproportionation reaction of the telogen to a certain extent. The accelerator is at least one of chloroform, difluorochloromethane, and fluorochloromethane. The order of the saturated vapor pressures of the three accelerators from high to low is difluorochloromethane > fluorochloromethane > chloroform. Therefore, according to the different saturated vapor pressures, the chloroform accelerator with the lowest saturated vapor pressure needs to be added to the reaction kettle first before the reaction, and difluorochloromethane is added last.

[0041] In step (2), the polar aprotic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, dimethyl sulfoxide, N-methylpyrrolidone, and sulfolane.

[0042] In step (2), the telomerization reaction system is carried out in a polymerization reaction kettle, preferably a polymerization reaction kettle made of Monel 400 material.

[0043] In step (2), the reaction temperature of the telomerization reaction is 0-100 °C, the reaction pressure is 0.1-2.0 MPa, and the reaction time is 8-24 h. Preferably, the reaction temperature is 5-80 °C, the reaction pressure is 0.1-1.0 MPa, and the reaction time is 10-24 h.

[0044] In the telomerization reaction process, a suitable material ratio may obtain a better reaction effect.

[0045] In step (2), the mass ratio of the telomerization catalyst to 1,2-difluoroethylene is (0.001-0.5):1; the molar ratio of the accelerator to 1,2-difluoroethylene is (0.1-1):1, and the molar ratio of the solvent to 1,2-difluoroethylene is (1-5):1; preferably, the mass ratio of the catalyst to the raw material is (0.005-0.25):1, the molar ratio of the accelerator to 1,2-difluoroethylene is (0.5-1):1, and the molar ratio of the solvent to 1,2-difluoroethylene is (1.5-3):1.

[0046] In step (2), the molar ratio of the telomerization reaction raw materials 1,2-difluoroethylene and dichlorofluoromethane is 1:(0.1-10). Preferably, the molar ratio of 1,2-difluoroethylene and dichlorofluoromethane is 1:(1-5).

[0047] During the research process of the present invention, it was found that:

[0048] 1) The gas-phase dehydrohalogenation reaction of hydrofluoroalkanes is essentially an elimination process, and its reaction mechanism mainly has three mechanisms: E1, E2, and E1cb. Among them, the E1 mechanism: the carbon-halogen bond C-X in the reaction raw material molecule breaks to generate C + , and then C +The C-H bond connected thereto breaks to remove the proton H + After that, the reaction of eliminating HX is completed; while for some C + Rearrangement occurs, and the corresponding isomers are also generated; the E2 mechanism is that the free X and H interact to complete the reaction. The E1cb mechanism is mainly that the C-H bond breaks to generate C - Then C - Eliminates X - To complete the reaction. The specific reaction mechanism is shown in Equation 1.

[0049]

[0050] Related research shows that the dehydrofluorination reaction of fluoroalkanes proceeds through the E1 mechanism, that is, the C-F bond is first activated at the beginning of the reaction, breaks to form a carbocation, and then the H at the β-position is eliminated to complete the reaction. Due to the characteristics of the C-F bond in hydrofluoroalkanes, such as short bond length, high polarity, and low polarizability, the dissociation energy of the C-F bond is as high as 513.8±10.0 kJ / mol, showing high chemical inertness. Therefore, the breaking of the C-F bond has become the key step in the dehydrofluorination reaction of fluoroalkanes. And it is found that the dehydrofluorination reaction itself is a highly corrosive environment, so the choice of catalyst is mainly limited to AlF3, chromium fluoride CrO x , MgF2, etc. The activation of the C-F bond usually occurs at the coordinatively unsaturated metal sites or fluorine defect sites on these metal fluorides, that is, the Lewis acid sites. The F atom with strong electronegativity can be chemisorbed by the Lewis acid site to accelerate the breaking of the C-F bond. However, if the Lewis acidity on the catalyst surface is too strong, although this helps the breaking of the C-F bond, it also promotes the dissociation of C + Ions, and the unsaturated olefins in the product polymerize and coke to form carbon deposits, causing the catalyst to deactivate; while when the Lewis acidity on the catalyst surface is too weak, the C-F bond is difficult to break, hindering the progress of the dehydrofluorination reaction. That is to say, the Lewis acid sites on the catalyst surface are both the reaction active centers and the carbon deposition centers.

[0051] Therefore, finding suitable catalysts and controlling the acid amount of the catalysts are the key aspects of the dehydrofluorination reaction of hydrofluorocarbons. Modifying the dehydrofluorination catalyst with noble metals Pd, Pt, and Ru can not only improve the structural stability of the catalyst during calcination and reaction, avoiding crystal form changes and structural collapse, but also help decompose the olefin by-products of polymerization and coking in the decomposition reaction, thereby in-situ regenerating the Lewis acid sites of the catalyst and extending the service life of the catalyst. Modifying the catalyst with transition metals Ni, Fe, etc. can not only promote the dissociation of C-H bonds in the raw material molecules, thus accelerating the removal of HF, but also regulate the strength and acid density of the acid sites on the catalyst surface, improve the competitive adsorption of the raw materials by the Lewis acid active sites on the catalyst surface, weaken the adsorption ability of olefin products and by-products on the active sites, and to a certain extent avoid the reduction of the number of effective active sites caused by the long-term residence of olefin products and by-products on the adsorption sites and the occurrence of olefin polymerization and coking.

[0052] 2) Thermodynamic theoretical calculations show that the telomerization reaction of 1,2-difluoroethylene and dichlorofluoromethane is an exothermic reaction. Therefore, increasing the reaction temperature may not be conducive to the progress of this reaction, and it is necessary to screen a suitable telomerization reaction temperature. The telomerization reaction is a special addition reaction, and its active sites are mainly Lewis acid sites. The reaction raw material dichlorofluoromethane will activate the C-F or C-Cl bonds in the molecule under the action of a Lewis acid catalyst, and thus dissociate into CHFCl + , CHCl2 + , F - , Cl - four kinds of free radicals. Since the activation energy barrier of dichlorofluoromethane in an acidic catalyst is relatively low (only 0.79 eV), it is more likely to undergo a disproportionation reaction to form CHCl3 and CHF2Cl. Therefore, in the present invention, by adding chloroform and / or dichlorofluoromethane as a promoter, the disproportionation reaction of dichlorofluoromethane is inhibited to a certain extent.

[0053] During the reaction process, by adding a polar aprotic solvent, the reaction system becomes a strongly polar environment, and the affinity between the C-F bond in the telogen dichlorofluoromethane and the Lewis catalyst is increased, thereby inducing the directional dissociation of C-F in dichlorofluoromethane under the action of a supported Lewis acid catalyst, weakening the dissociation of the C-Cl bond, and increasing the selectivity of F - to be directionally added to the terminal C + . In addition, the supported Lewis acid-base catalyst developed in the present invention is moderately pre-fluorinated before the reaction, which can effectively regulate the acid amount and acid strength of the reaction system, reduce the occurrence of the disproportionation reaction of dichlorofluoromethane to a certain extent, and improve the stability of the telomerization catalyst.

[0054] In step (2), the crude telomerization product is subjected to conventional rectification to obtain 3,3-dichloro-1,1,2-trifluoropropane product and by-product 1,3-dichloro-1,2,3-trifluoropropane. The chlorofluorohydrocarbon can be further obtained by dehalogenation process to obtain 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd) and 3-chloro-1,2,3-trifluoropropene (HCFO-1233ye) respectively.

[0055] In step (3), the liquid-phase dehydrochlorination reaction is carried out under the action of a liquid alkali catalyst. The liquid alkali catalyst is selected from hydroxides of alkali metals, transition metals and alkaline earth metals, and oxides of alkali metals, transition metals and alkaline earth metals.

[0056] Preferably, the hydroxides of alkali metals, transition metals or alkaline earth metals are selected from at least one of NaOH, KOH, Mg(OH)2, Ca(OH)2, Ba(OH)2. The oxides of alkali metals or alkaline earth metals are selected from at least one of Na2O, K2O, MgO, CaO, BaO.

[0057] In order to promote the reaction, a phase transfer catalyst needs to be added in the liquid-phase dehydrochlorination reaction. The phase transfer catalyst is at least one of quaternary ammonium salts such as tetrabutylammonium chloride (TBAC), tetrabutylammonium bromide (TBAB), methyltrioctylammonium chloride (TOMAC) or crown ethers such as 18-crown-6-ether.

[0058] In step (3), the addition amount of the liquid alkali catalyst is 0.5 to 3 times the molar amount of the raw material, and the addition amount of the phase transfer catalyst is 0.001 to 0.1 times the mass of the raw material; more preferably, the addition amount of the alkali catalyst is 1 to 2 times the molar amount of the raw material, and the addition amount of the phase transfer catalyst is 0.005 to 0.05 times the mass of the raw material.

[0059] The present invention uses 1,1,2-trifluoroethane (HFC-143) as a raw material and prepares HCFO-1233yd by a three-step method, which specifically includes the following operating steps:

[0060] M1. The raw material 1,1,2-trifluoroethane (HFC-143) is vaporized through a vaporization chamber and then enters a gas-phase catalytic dehydrofluorination reactor, where a dehydrofluorination reaction occurs on the surface of the dehydrofluorination reaction catalyst bed to generate 1,2-difluoroethylene (HFO-1132); the reaction product is collected and rectified and purified to obtain a 1,2-difluoroethylene intermediate;

[0061] M2. Under the synergistic effect of a pre-fluorinated Lewis acid catalyst, a promoter, and a polar aprotic solvent, 1,2-difluoroethylene and dichlorofluoromethane (R21) undergo a telomerization reaction in a polymerization reactor to obtain 3,3-dichloro-1,1,2-trifluoropropane. An airbag is used to collect the unreacted low-boiling raw materials 1,2-difluoroethylene and dichlorofluoromethane, as well as the low-boiling promoter chlorodifluoromethane. The reaction liquid in the telomerization reactor is filtered and separated. Among them, the solid part is the Lewis acid catalyst, and the liquid part is separated by ordinary distillation to separate impurities such as the promoter chloroform from the product 3,3-dichloro-1,1,2-trifluoropropane.

[0062] M3. 3,3-Dichloro-1,1,2-trifluoropropane undergoes a liquid-phase dehydrochlorination reaction under the action of a phase-transfer catalyst. After the reaction ends, the crude reaction product is obtained by liquid-liquid separation and distillation to obtain the target product HCFO-1233yd.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] 1. The starting material 1,1,2-trifluoroethane (HFC-143) of the present invention is a by-product of the hydrogenation and dechlorination of chlorotrifluoroethylene (CTFE) to prepare trifluoroethylene (TrFE), and the CTFE raw material belongs to our company's advantageous products and is relatively easy to obtain. Through the resource utilization of by-products, not only can the by-product 1,1,2-trifluoroethane be converted into high-value-added and environmentally friendly fluorinated olefin monomers and fluorinated refrigerants, but also the production and by-product treatment costs of enterprises can be greatly reduced.

[0065] 2. The present invention uses 1,1,2-trifluoroethane (HFC-143) as a raw material and obtains HCFO-1233yd through three-step reactions. Compared with the existing 2,2,3,3-tetrafluoropropanol two-step process, the raw material cost is lower, the amount of three wastes is less, the product selectivity is high, the raw material conversion rate is high, and the product separation is relatively easy. The process of this application is particularly suitable for industrial production.

[0066] 3. In the dehydrofluorination reaction process of step (1) of the present invention, the α-AlF3 support with a large specific surface area spherical particle is prepared by the sol-gel method. The selected promoter components and active components are dispersed on the surface of the support by the stepwise vacuum impregnation method. The synergistic effect of the three is significant, the acidity strength of the catalyst is moderate, the active components are evenly dispersed, and while maintaining high stability, it can also in-situ remove the surface carbon of the catalyst, reduce the blockage and poisoning inactivation of the active site pores of the catalyst, and can better delay the carbon deposition inactivation of the catalyst when used in the gas-solid phase dehydrofluorination reaction, especially the dehydrofluorination reaction of 1,1,2-trifluoroethane, thereby improving the stability and service life of the catalyst.

[0067] 4. Step (2) of the present invention discloses a supported Lewis acid telomerization catalyst. Through the synergistic effect of a promoter and a polar aprotic solvent, carbon chain growth is achieved and the target product is obtained through a one-step telomerization reaction. Compared with traditional single-component anhydrous chlorides, the telomerization catalyst used is more friendly to the reaction system and reaction equipment, has no corrosion, requires less dosage, the catalyst can be regenerated, the reaction process is simple, the reaction conditions are mild, the selectivity of the target product is high, and the separation of the catalyst and the product is relatively easy, making it very suitable for industrial application. Specific Embodiments

[0068] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative, improved, and equivalent solutions that may be included within the scope of the claims.

[0069] Example 1

[0070] This example provides a method for preparing 1-chloro-2,3,3-trifluoropropene, which specifically includes the following steps:

[0071] Step (1) Dehydrofluorination reaction: The raw material 1,1,2-trifluoroethane (HFC-143) is vaporized in a vaporization chamber and then enters a gas-solid dehydrofluorination reactor (the catalyst is 1% Pd - 5% NiF2 / AlF3 catalyst), the reaction space velocity is 240 h -1 , the reaction temperature is 350 °C, and the reaction product is 1,2-difluoroethylene (HFO-1132), including cis-1,2-difluoroethylene and trans-1,2-difluoroethylene. The reaction products are analyzed by gas chromatography after 1 h, 10 h, and 50 h respectively. The specific reaction results are shown in Table 1.

[0072] Table 1 Dehydrofluorination reaction results of 1% Pd - 5% NiF2 / AlF3 at 350 °C

[0073]

[0074] Step (2) Telomerization reaction: A 0.5 L autoclave made of Monel 400 is used as the reactor. 3.5 g of pre-fluorinated 10% ZrCl4 / AC catalyst, 11.9 g (0.1 mol) of trichloromethane promoter, and 7.8 g (0.1 mol) of dimethyl sulfoxide solvent are successively added to the reaction kettle, purged with nitrogen 3 times, and the reaction kettle is evacuated to -0.1 MPa.

[0075] 25.8 g (0.25 mol) of dichlorofluoromethane, 8.9 g (0.14 mol) of 1,2-difluoroethylene, and 16.4 g (0.19 mol) of dichlorodifluoromethane were introduced successively. The reaction temperature was set at 30 °C, the stirring rate was set at 400 rpm / min, and the reaction time was set at 10 h. The unreacted raw materials, 1,2-difluoroethylene and dichlorofluoromethane, and the low-boiling-point promoter dichlorodifluoromethane were collected using an air bag. The reaction solution in the reaction kettle was filtered and separated. The solid part was the Lewis acid catalyst, and the liquid part was obtained as 3,3-dichloro-1,1,2-trifluoropropane by distillation.

[0076] The composition of the product was analyzed by gas chromatography. After calculation, the conversion rate of 1,2-difluoroethylene was 92.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 84.9%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 13.6%, and the rest were other by-products.

[0077] Step (3) - Dehydrochlorination reaction: About 0.02 g of the phase transfer catalyst TBAC was added to a three-necked flask containing 20 g of 3,3-dichloro-1,1,2-trifluoropropane solution. The reaction solution was then heated to 50 °C and stirred steadily for 1 h. Finally, about 25.3 g of a 40% KOH solution by mass was introduced, and the reaction continued for 5 h to obtain 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd), including cis-HCFO-1233yd and trans-HCFO-1233yd.

[0078] The reaction product was analyzed by gas chromatography. The conversion rate of 3,3-dichloro-1,1,2-trifluoropropane was 95.1%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene was 81.5%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene was 18.4%.

[0079] Example 2

[0080] The operation of this example was the same as that of Example 1, except that in reaction step (1), the dehydrofluorination reaction temperature was 400 °C, and the reactions were carried out continuously for 1 h, 10 h, and 50 h, respectively. The specific reaction results are shown in Table 2:

[0081] Table 2 Dehydrofluorination reaction results of 1% Pd - 5% NiF2 / AlF3

[0082]

[0083] Example 3

[0084] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the content of the noble metal component Pd in the dehydrofluorination reaction catalyst is changed to 0.5%, that is, 0.5% Pd - 5% Ni / AlF3. The specific reaction results are shown in Table 3:

[0085] Table 3 Dehydrofluorination reaction results of 0.5% Pd - 5% NiF2 / AlF3

[0086]

[0087] Example 4

[0088] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the content of the transition metal Ni in the dehydrofluorination reaction catalyst is changed to 10%, that is, 1% Pd - 10% Ni / AlF3. The specific results are shown in Table 4:

[0089] Table 4 Dehydrofluorination reaction results of 1% Pd - 10% NiF2 / AlF3

[0090]

[0091] Examples 5 - 7

[0092] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the dehydrofluorination performance at dehydrofluorination reaction temperatures of 300 °C, 450 °C, and 500 °C is examined. The specific results are shown in Table 5:

[0093] Table 5 Dehydrofluorination reaction results of 1% Pd - 5% NiF2 / AlF3 at different temperatures

[0094]

[0095] By examining the reaction activity of HFC - 143 at different temperatures, it is found that when the reaction temperature is 350 - 450 °C, the raw material conversion rate of HFC - 143 and the selectivity of the HFO - 1132 product can be better balanced.

[0096] Examples 8 - 11

[0097] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the dehydrofluorination reaction space velocities are 120 h -1 、360 h -1 、480 h -1 、720 h -1 respectively, and the dehydrofluorination reaction results are shown in Table 6 below:

[0098] Table 6 Dehydrofluorination reaction results of 1% Pd - 5% NiF2 / AlF3 at different space velocities

[0099]

[0100]

[0101] By investigating the reaction activity of HFC-143 under different space velocity conditions, it is found that when the reaction space velocity is 120-720 h -1 it can better balance the conversion rate of HFC-143 raw material and the selectivity of HFO-1132 product.

[0102] Example 12

[0103] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the transition metal Ni of the dehydrofluorination reaction catalyst is replaced with Fe, that is, 1% Pd-5% FeF3 / AlF3, and other operations remain unchanged. The specific reaction results are shown in Table 7.

[0104] Table 7 Dehydrofluorination reaction results of 1% Pd-5% FeF3 / AlF3 at 350°C

[0105]

[0106] Example 13

[0107] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the second component Ni of the dehydrofluorination reaction catalyst is replaced with Pr, that is, 1% Pd-5% PrF3 / AlF3, and other operations remain unchanged. The specific reaction results are shown in Table 8.

[0108] Table 8 Dehydrofluorination reaction results of 1% Pd-5% PrF3 / AlF3 at 350°C

[0109]

[0110] Example 14

[0111] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the noble metal Pd of the dehydrofluorination reaction catalyst is replaced with Ru, that is, 1% Ru-5% NiF2 / AlF3, and other operations remain unchanged. The specific reaction results are shown in Table 9.

[0112] Table 9 Dehydrofluorination reaction results of 1% Ru-5% NiF2 / AlF3 at 350°C

[0113]

[0114] Example 15

[0115] The operation of this example is the same as that of Example 1, except that: in reaction step (2), the telomerization reaction temperature is 10°C, and other operations remain unchanged.

[0116] The telomerization reaction product was analyzed by gas chromatography. After calculation, the conversion rate of 1,2-difluoroethylene was 93.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 86.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 13.4%, and the rest were other by-products.

[0117] Example 16

[0118] The operation of this example was the same as that of Example 1, except that in reaction step (2), the telomerization reaction temperature was 50 °C and other operations remained unchanged.

[0119] The product composition was analyzed by gas chromatography. After calculation, the conversion rate of 1,2-difluoroethylene was 83.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 76.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 19.5%, and the rest were other by-products.

[0120] Example 17

[0121] The operation of this example was the same as that of Example 1, except that in reaction step (2), the telomerization reaction temperature was 80 °C and other operations remained unchanged.

[0122] The product composition was analyzed by gas chromatography. After calculation, the conversion rate of 1,2-difluoroethylene was 70.3%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 73.7%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 25.4%, and the rest were other by-products.

[0123] Example 18

[0124] The operation of this example was the same as that of Example 1, except that in reaction step (2), the telomerization reaction catalyst was replaced with 3.5 g of 10% AlCl3 / AC and other conditions remained unchanged.

[0125] The product composition was analyzed by gas chromatography. After calculation, the conversion rate of 1,2-difluoroethylene was 90.1%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 78.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 18.7%, and the rest were other by-products.

[0126] Example 19

[0127] The operation of this example was the same as that of Example 1, except that in reaction step (2), the telomerization reaction catalyst was replaced with 3.5 g of 10% GaCl3 / AC and other conditions remained unchanged.

[0128] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 90.9%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 81.5%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 17.9%, and the rest were other by-products.

[0129] Example 20

[0130] The operation of this example was the same as that of Example 1, with the only difference being that: in reaction step (2), the dosage of the telomerization reaction catalyst was increased to 1 time the original amount, that is, 7 g of 10% ZrCl4 / AC, and the others remained unchanged.

[0131] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 81.7%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 79.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 16.7%, and the rest were other by-products.

[0132] Example 21

[0133] The operation of this example was the same as that of Example 1, with the only difference being that: in reaction step (2), the loading amount of the active component of the telomerization reaction catalyst was 5%, that is, 3.5 g of 5% ZrCl4 / AC, and the others remained unchanged.

[0134] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 86.9%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 84.2%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 12.9%, and the rest were unreacted raw materials and other by-products.

[0135] Example 22

[0136] The operation of this example was the same as that of Example 1, with the only difference being that: in reaction step (2), the molar ratio of the telomerization reaction raw materials 1,2-difluoroethylene to dichlorofluoromethane was 1:1, 8.9 g (0.14 mol) of 1,2-difluoroethylene and 14.4 g (0.14 mol) of dichlorofluoromethane, and the others remained unchanged.

[0137] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 77.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 71.5%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 20.8%, and the rest were other by-products.

[0138] Example 23

[0139] The operation of this example is the same as that of Example 1, except that: in reaction step (2), the molar ratio of the telomerization reaction raw materials 1,2-difluoroethylene to chlorodifluoromethane is 2:1, that is, 16 g (0.25 mol) of 1,2-difluoroethylene and 12.4 g (0.12 mol) of chlorodifluoromethane, and the others remain unchanged.

[0140] The product composition was analyzed by gas chromatography, and it was calculated that: the conversion rate of 1,2-difluoroethylene was 57.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 60.2%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 25.6%, and the rest were unreacted raw materials and other by-products.

[0141] Example 24

[0142] The operation of this example is the same as that of Example 1, except that: in reaction step (2), the polar aprotic solvent in the telomerization reaction was changed to 10.2 g of N,N-dimethylformamide, and the others remained unchanged.

[0143] The product composition was analyzed by gas chromatography, and it was calculated that: the conversion rate of 1,2-difluoroethylene was 90.1%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 85.5%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 10.5%, and the rest were unreacted raw materials and other by-products.

[0144] Example 25

[0145] The operation of this example is the same as that of Example 1, except that: in reaction step (2), the polar aprotic solvent in the telomerization reaction was changed to 16.8 g (0.14 mol) of sulfolane, and the others remained unchanged.

[0146] The product composition was analyzed by gas chromatography, and it was calculated that: the conversion rate of 1,2-difluoroethylene was 92.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 90.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 6.4%, and the rest were unreacted raw materials and other by-products.

[0147] Comparative Example 1

[0148] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the dehydrofluorination catalyst was only the carrier AlF3, and other operations remained unchanged. The specific reaction results are shown in Table 10.

[0149] Table 10 Dehydrofluorination reaction results of AlF3 at 350 °C

[0150]

[0151] Comparative Example 2

[0152] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the catalyst AlF3 is prepared by the precipitation method, and other operations remain unchanged. The specific reaction results are shown in Table 11.

[0153] Table 11 Results of the hydrogen fluoride elimination reaction of AlF3 prepared by the precipitation method at 350 °C

[0154]

[0155] Comparative Example 3

[0156] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the catalyst AlF3 is prepared by the mechanical mixing method, and other operations remain unchanged. The specific reaction results are shown in Table 12.

[0157] Table 12 Results of the hydrogen fluoride elimination reaction of AlF3 prepared by the mechanical mixing method at 350 °C

[0158]

[0159] Comparative Example 4

[0160] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the crystal form of the catalyst carrier is changed to γ-AlF3, and other operations remain unchanged. The specific reaction results are shown in Table 13.

[0161] Table 13 Reaction results of the Pd-Ni binary catalyst supported on the γ-AlF3 carrier at 350 °C

[0162]

[0163] Comparative Example 5

[0164] The operation of this example is the same as that of Example 1, except that: in reaction step (1), the catalyst carrier AlF3 is prepared by the precipitation method, and other operations remain unchanged. The specific reaction results are shown in Table 14.

[0165] Table 14 Results of the hydrogen fluoride elimination reaction of the Pd-Ni binary component supported on the precipitation method-AlF3 carrier at 350 °C

[0166]

[0167] Comparative Example 6

[0168] The operation of this comparative example is the same as that of Example 1, except that: in reaction step (1), the catalyst carrier is changed to MgF2, and other operations remain unchanged. The specific reaction results are shown in Table 15.

[0169] Table 15 Results of the dehydrofluorination reaction of MgF2 at 350 °C

[0170]

[0171] Comparative Example 7

[0172] The operation of this comparative example is the same as that of Example 1, except that: in reaction step (2), 3.5 g of 10% ZnCl2 / AC is used as the telomerization catalyst, and the others remain unchanged.

[0173] The product composition was analyzed by gas chromatography and calculated to obtain: the telomerization reaction of 1,2-difluoroethylene did not occur, and the target product of 3,3-dichloro-1,1,2-trifluoropropane was not obtained in the reaction products.

[0174] Comparative Example 8

[0175] The operation of this comparative example is the same as that of Example 1, except that: in reaction step (2), the promoter chloroform is not added in the telomerization reaction, and the others remain unchanged.

[0176] The product composition was analyzed by gas chromatography and calculated to obtain: the conversion rate of 1,2-difluoroethylene was 66.2%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 46.8%, the selectivity of by-product 1,3-dichloro-1,2,3-trifluoropropane was 20.3%, and the rest were the disproportionation reaction products of dichlorofluoromethane and other by-products.

[0177] Comparative Example 9

[0178] The operation of this comparative example is the same as that of Example 1, except that: in reaction step (2), 15.4 g (0.1 mol) of the non-polar solvent carbon tetrachloride is used as the solvent in the telomerization reaction.

[0179] The product composition after distillation was analyzed by gas chromatography and calculated to obtain: the conversion rate of 1,2-difluoroethylene was 83.7%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 63.3%, the selectivity of by-product 1,3-dichloro-1,2,3-trifluoropropane was 28.9%, and the rest were other by-products.

[0180] Comparative Example 10

[0181] The operation of this comparative example is the same as that of Example 1, except that: in reaction step (2), no polar aprotic solvent is added to the telomerization reaction system, and other conditions remain unchanged.

[0182] The composition of the product after rectification was analyzed by gas chromatography. After calculation, it was obtained that the conversion rate of 1,2-difluoroethylene was 81.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 54.9%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 36.6%, and the rest were unreacted raw materials and other by-products.

[0183] Comparative Example 11

[0184] The operation of this comparative example was the same as that of Example 1, except that: in reaction step (2), the telomerization reaction catalyst was only activated carbon, and the others remained unchanged.

[0185] The composition of the product after rectification was analyzed by gas chromatography. After calculation, it was obtained that 1,2-difluoroethylene did not undergo an addition reaction and no target product 3,3-dichloro-1,1,2-trifluoropropane was formed.

[0186] Comparative Example 12

[0187] The operation of this comparative example was the same as that of Example 1, except that: in reaction step (2), the telomerization reaction temperature was 120 °C, and the others remained unchanged.

[0188] The composition of the product was analyzed by gas chromatography. After calculation, it was obtained that the conversion rate of 1,2-difluoroethylene was 63.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 51.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 23.5%, and the rest were the polymerization products of 1,2-difluoroethylene and other by-products.

[0189] Comparative Example 13

[0190] The operation of this comparative example was the same as that of Example 1, except that: in reaction step (2), the telomerization reaction catalyst 10% ZrCl4 / AC participated in the reaction directly without being pre-fluorinated by the telomerization substrate dichlorofluoromethane (R21), and the others remained unchanged.

[0191] The composition of the product was analyzed by gas chromatography. After calculation, it was obtained that the conversion rate of 1,2-difluoroethylene was 77.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 64.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 9.5%, and the rest were unreacted raw materials and other by-products.

[0192] Comparative Example 14

[0193] The operation of this comparative example was the same as that of Example 18, except that: in reaction step (2), the telomerization catalyst 10% AlCl3 / AC participated in the reaction directly without being pre-fluorinated by the telomerization substrate dichlorofluoromethane (R21), and the others remained unchanged.

[0194] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 69.9%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 61.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 12.3%, and the rest were unreacted raw materials and other by-products.

[0195] Comparative Example 15

[0196] The operation of this comparative example was the same as that of Example 1, except that: in reaction step (2), the telomerization reaction catalyst was pre-fluorinated with inorganic HF, and other conditions remained unchanged.

[0197] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 90.6%, the selectivity of the target product 3,3-dichloro-1,1,2-trifluoropropane was 40.2%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 18.7%, and the selectivity of the remaining 41.1% was the by-product of the side reaction between the R21 disproportionation product dichlorofluoromethane (R22) and the raw material 1,2-difluoroethylene.

Claims

1. A method for the resource utilization of 1,1,2-trifluoroethane to prepare 1-chloro-2,3,3-trifluoropropene, characterized in that: The preparation method comprises: (1) Dehydrofluorination step: 1,1,2-trifluoroethane is subjected to a dehydrofluorination reaction under the action of a dehydrofluorination catalyst to obtain 1,2-difluoroethylene, wherein the catalyst is a multi-component composite AB / α-AlF3 catalyst composed of a carrier, an auxiliary component A and an active component B, wherein: The carrier is α-type AlF3 The auxiliary agent component A is selected from at least one of Pt, Pd, Ru and Rh; The active component B is selected from at least one of V, Fe, Ni, Co, Ce, Pr, and W; (2) a telomerization step: 1,2-difluoroethylene and dichlorofluoromethane are subjected to a one-step telomerization reaction under the combined action of a telomerization catalyst, a promoter, and a polar aprotic solvent to obtain 3,3-dichloro-1,1,2-trifluoropropane; (3) Dehydrochlorination step: 3,3-dichloro-1,1,2-trifluoropropane is dehydrochlorinated to obtain 1-chloro-2,3,3-trifluoropropene.

2. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (1), the loading amount of the auxiliary component A is 0.01% to 2.0%, the loading amount of the active component B is 1% to 20%, and the rest is the carrier.

3. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (1), the dehydrofluorination catalyst is prepared by a step-by-step vacuum impregnation method, which specifically includes: a carrier preparation step, an auxiliary component A vacuum impregnation step, an auxiliary component A hydrogen reduction step, an active component B vacuum impregnation step, and a catalyst pre-fluorination step.

4. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 3, characterized in that: The carrier preparation method in step (1) is a modified sol-gel method, comprising the following steps: A1: Weigh the metal organic alkoxide precursor into a PTFE tank, and add 200 ml of anhydrous ethylene glycol and 20 ml of polyethylene glycol respectively; A2: Place the PTFE tank containing the above mixed solution in a low-temperature circulation tank at -10 to -20°C and stir at low temperature. At the same time, add the prepared 20wt% HF solution dropwise into the above solution and continue stirring for 8 to 12 hours. Then, stir at 80°C for 6 hours, filter and centrifuge, and dry at 120°C to obtain a yellow block catalyst precursor. A3: Calcine the yellow block catalyst precursor at 300-500°C in air atmosphere for 3-5 hours to obtain the metal fluoride carrier α-crystalline AlF3.

5. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 3, wherein: In step (1), the hydrogen reduction step of the auxiliary agent component A is carried out in a reducing atmosphere of N2 / H2=2:1-4:1, the reduction temperature is 200-350°C, and the reduction time is 1-3h.

6. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (2), the polymerization catalyst is at least one of AlCl3 / AC, GaCl3 / AC, ZrCl4 / AC, and SnCl4 / AC pre-fluorinated with halogenated alkane.

7. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 6, characterized in that: In step (2), the halogenated alkane is at least one of difluorochloromethane, fluorochloromethane and trifluoromethane.

8. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 6, characterized in that: In step (2), the pre-fluorination temperature of the telomerization catalyst is 200-300° C., and the pre-fluorination time is 2-3 hours.

9. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (2), the loading amount of Lewis acid active component in the telomerization catalyst is 5 to 20%.

10. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (2), the promoter is at least one of chloroform, difluorochloromethane and fluorochloromethane.

11. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 7, characterized in that: In step (2), according to the different saturated vapor pressures, chloroform needs to be added to the reaction kettle before introducing the reaction raw materials, and difluorochloromethane and chlorofluoromethane need to be added to the reaction kettle before and after introducing the reaction raw materials.

12. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (2), the polar aprotic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, dimethyl sulfoxide, N-methylpyrrolidone, and sulfolane.

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