Continuous production method of perfluorobutene and modified catalyst

Abstract

This invention relates to the field of haloalkanes preparation technology, providing a continuous production method for perfluorobutene and a modified catalyst. The continuous production method for perfluorobutene uses trifluorochloroethylene as raw material and consists of three steps: Step 1, Step 2, and Step 3. The key features are: Step 1 involves the gasification of trifluorochloroethylene followed by continuous contact reaction with a modified catalyst in a fixed bed; Step 2 involves the tail gas being passed into a condenser reactor, which is filled with active zinc powder as a catalyst, and the reactor temperature is maintained at 5–100°C; Step 3 involves the generated and remaining gases in the condenser reactor entering a condenser separator, where solid and liquid separation is performed, and the separated solids and liquids are collected and purified; the modified catalyst is modified using ball milling or impregnation methods, and consists of a metal active center and a support. Therefore, this invention enables continuous production, is highly efficient, environmentally friendly, energy-efficient, and has low production costs, making it suitable for mass production.

Description

Technical Field

[0001] This invention relates to the field of haloalkanes preparation technology, and more particularly to a continuous production method for perfluorobutene and a modified catalyst. Background Technology

[0002] Hexafluoro-1,3-butadiene (HFBD), molecular formula C4F6, structural formula CF2=CF-CF=CF2, boiling point 6℃, density 1.4 kg·L -1 (15℃).

[0003] Perfluorobutadiene (PFB) can be reacted with small amounts of 1,1-difluoroethylene (CF2=CH2) and C3F6 to form fluorinated rubber, and with perfluoroethylene (CH2=CH2) and trihydrofluoronitrosoethane trimerization to synthesize fluorinated elastomers. Currently, PFB's applications are mainly concentrated in the dry etching process for very large-scale integrated circuits (VLSI). Studies have shown that compared to traditional plasma etching gases, PFB has higher etching precision and selectivity, enabling dry etching of widths smaller than 100 nm or even narrower, making it more suitable for high aspect ratio etching processes. Furthermore, PFB has an atmospheric lifetime of only 1.9 days, a GWP (100) value of 290, and an ODP value of 0, making it a green and environmentally friendly product with extremely low greenhouse effect. With the strong global demand for VLSI and increased focus on greenhouse gases, PFB has high market potential and will gradually become an important high-end fluorinated electronic gas in the future.

[0004] There are various methods for synthesizing perfluorobutadiene, such as fluorination, telomerization, coupling dehalogenation, and thermal polymerization dehalogenation.

[0005] Fluorination method: Patent US2716141 describes the fluorination of dimerized 1,2-dichlorodifluoroethylene (chemical formula CFCl=CFCl) to obtain 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, which is then dechlorinated with zinc in anhydrous ethanol to prepare perfluorobutadiene. This reaction involves numerous side reactions, making subsequent separation and purification difficult. The reaction requires fluorine gas (F2) and must be carried out at low temperatures of -75 to -70°C, posing significant risks and high energy consumption, thus leading to substantial production costs for actual industrial scale-up.

[0006] Telogenization: CN 202011579415 describes the telogenization of perfluoroethylene prepared by the hydrothermal reaction with R22, which reacts with Br2 to form 1,2-dibromotetrafluoroethane. The 1,2-dibromotetrafluoroethane is then telogenized with perfluoroethylene in an organic solvent using zinc to obtain perfluorobutadiene. This process is a liquid-phase batch reaction, which is not conducive to continuous industrial production. Furthermore, the selectivity of the telogenization reaction is difficult to control, posing a high risk.

[0007] Coupling dehalogenation method: JP2001114710 isomerizes 1,2-dibromotetrafluoroethane to 1,1-dibromotetrafluoroethane in Lewis acid, then reacts it with zinc powder in an aprotic solvent to generate trifluorobromovinyl zinc reagent. The trifluorobromovinyl zinc reagent then reacts with Fe in an aprotic solvent... 3+ or Cu 2+ The compound reacts to form perfluorobutadiene. The overall yield of this method is 47%, but the organozinc reagent is prone to decomposition at high temperatures, resulting in a large amount of waste.

[0008] CN202010018723 describes a process where 1,2-dibromotetrafluoroethane reacts with AlX3 and zinc in an organic solvent to generate an organometallic reagent, which is then reacted with 1,2-dibromotetrafluoroethane. Trifluoroethylene (C2F3Br) is slowly added, and the reaction is catalyzed by palladium (Pd) for 12-28 hours to synthesize perfluorobutadiene. This process uses the expensive noble metal catalyst tetra(triphenylphosphine)palladium, is a liquid-phase reaction, involves multiple steps, and is complex, making it unsuitable for industrial production.

[0009] US3046304 discloses a method for preparing perfluorobutadiene from trifluorochloroethylene (trifluorochloroethylene) as a raw material. Trifluorochloroethylene reacts with iodine chloride (ICl) to give 1,2-dichloro-1,2,2-trifluoroiodoethane, which is then coupled with an stoichiometric amount of mercury under ultraviolet light to give 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. Subsequently, it is dechlorinated in an alcohol solvent with the aid of zinc powder to obtain perfluorobutadiene. This method requires stoichiometric amounts of iodine chloride and mercury, the reagents are expensive, and one of the products, mercuric iodide, is highly toxic.

[0010] Patents CN201510760125.9 and CN201410764358.1 describe the generation of trifluorobromoethylene zinc reagent from zinc in an organic solvent using an initiator. The former uses halogen (Cl2 or Br2) for dechlorination to synthesize perfluorobutadiene, while the latter uses Fe... 3+ or Cu 2+ Catalytic coupling to perfluorobutadiene. However, the source of trifluorobromoethylene is difficult. Therefore, CN201510157823 uses 1,1,1,2-tetrafluoroethane (referred to as R134a) to catalytically remove HF at high temperature to trifluoroethylene, which is then subjected to Br2 addition and HBr removal to trifluorobromoethylene, and then coupled to synthesize perfluorobutadiene. CN201510800131.2 also uses 1,1,1,2-tetrafluoroethane as a raw material, reacting it with Br2 at high temperature to generate 1,1-dibromotetrafluoroethane, which is then converted to an organozinc reagent with zinc in an organic solvent, and then reacted with Fe in an aprotic polar solvent. 3+ or Cu 2+Catalytic coupling is used to synthesize perfluorobutadiene. CN201910774511.1 modifies this method by hydrogenating and dechlorinating trifluorochloroethylene to trifluoroethylene, which is then brominated and de-HBr removed to produce trifluorobromoethylene. This trifluorobromoethylene is then reacted with zinc in an organic solvent to form a trifluorobromovinyl zinc reagent, followed by catalytic coupling to synthesize perfluorobutadiene. All these methods ultimately result in the synthesis of a zinc reagent from trifluorobromoethylene and zinc, followed by coupling to obtain perfluorobutadiene. However, the zinc reagent has poor thermal stability and is not easily stored for long periods. Furthermore, the preparation from other raw materials requires multiple chemical reactions, separation processes, and repeated solvent uses, resulting in a long reaction process, large amounts of waste, and unsuitability for continuous production.

[0011] Thermal Polymerization Dehalogenation Method: US2668182 reports a method for synthesizing perfluorobutadiene by dehalogenation after thermal polymerization of trifluorochloroethylene. Trifluorochloroethylene is passed through a high-temperature tube to obtain substance I and substance II (substance II is a mixture of 1,2-dichlorohexafluorocyclobutane and 3,4-dichlorohexafluoro-1-butene). After separating substance I, substance II undergoes photochlorination or bromination to convert the 3,4-dichlorohexafluoro-1-butene in substance II into the corresponding alkane. After separation and dehalogenation, perfluorobutadiene is obtained. This patent also proposes directly dechlorinating the product after photochlorination to prepare hexafluorocyclobutene and perfluorobutadiene, which are then separated using dry ice to obtain perfluorobutadiene. This patent has an extremely low product yield; 94g of raw material trifluorochloroethylene yields only 4g of the intermediate 1,2,3,4-tetrachlorohexafluorobutane. Furthermore, the use of photochlorination and bromination reactions results in high equipment costs, requires multiple separations, and is cumbersome, hindering industrial-scale production.

[0012] CN202110224766.8 describes the direct synthesis of perfluorobutadiene from 1,2-dichlorohexafluoro-3-butene through dechlorination in the presence of zinc, an organic solvent, and an initiator. After the reaction, distillation removes the heavy components to produce perfluorobutadiene with a purity of over 99%. The heavy components are then mixed with the raw material 1,2-dichlorohexafluoro-3-butene for reuse. The de-heavy perfluorobutadiene is then subjected to an iridium-clamp catalyst, or CsF or KF, to rearrange the byproducts back into perfluorobutadiene. Further distillation removes the lighter components, and filtration yields the final product, perfluorobutadiene. The lighter components from the distillation are then recycled through catalytic conversion. This patent suffers from difficulties in sourcing the raw materials, the use of an expensive iridium-clamp catalyst, and a focus on the distillation and catalytic conversion of impurities such as 1,2-dichlorohexafluorocyclobutane and hexafluoro-2,3-dichloro-2-butene in the raw materials.

[0013] CN202210174985.4 improves upon this method, disclosing a production process and apparatus for the thermal polymerization of trifluorochloroethylene to 1,2-dichlorohexafluoro-3-butene, followed by dechlorination to synthesize perfluorobutadiene. This invention primarily targets a production apparatus for the thermal polymerization process. The process requires separating 1,2-dichlorohexafluoro-3-butene from the thermal polymerization product, followed by liquid-phase dechlorination in a zinc / ethanol solvent for 24 hours, making continuous production impossible. Furthermore, the separation of 1,2-dichlorohexafluoro-3-butene is difficult in this invention, and the actual production efficiency of the process is not clearly defined.

[0014] CN115259993 describes a process where liquid-phase trifluorochloroethylene is thermally polymerized to obtain an intermediate. The low-boiling intermediate and the residue from the reactor are then fractionated. The intermediate is added to ethanol containing a zinc catalyst and refluxed. The collected gas undergoes ring-opening reaction with HI gas at high temperature and is then condensed and recovered. The condensate is then mixed with the residue from the previous step and subjected to a photocatalytic reaction with chlorine water. This mixture is then added to butylcarbitol and heated with a zinc catalyst. The mixture is condensed and refluxed to remove impurities, and then passed through a porous solid catalyst at high temperature to obtain perfluorobutadiene. This invention achieves a perfluorobutadiene yield of over 85%, but the process involves steps such as thermal polymerization, separation, dehalogenation, ring-opening, chlorination, and dehalogenation, resulting in a relatively long synthetic route.

[0015] RU2264376C1 involves the pyrolysis and condensation of trifluorochloroethylene, followed by fractionation to obtain 1,2-dichlorohexafluoro-3-butene and 1,2-dichlorohexafluorocyclobutane. The former is dechlorinated with zinc powder in a polar solvent to obtain perfluorobutadiene. The conversion rate of trifluorochloroethylene can reach approximately 70%, while the yields of 1,2-dichlorohexafluorocyclobutane and 1,2-dichlorohexafluoro-3-butene are approximately 34% and 27%, respectively.

[0016] In summary, the main raw materials for the synthesis of perfluorobutadiene are trifluorochloroethylene, perfluoroethylene, and 1,1,1,2-tetrafluoroethane. Different intermediates are obtained using different methods, but most of them are converted into trifluorovinyl zinc reagent and 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, and then obtained by coupling, telomerization, or dehalogenation reaction to produce perfluorobutadiene. Summary of the Invention

[0017] To address the aforementioned shortcomings, the present invention aims to provide a continuous production method for perfluorobutene and a modified catalyst. This invention targets existing perfluoroolefins, including perfluorobutadiene and perfluorocyclobutene. This method provides a continuous production process for perfluorobutene, including methods for producing perfluorobutadiene and perfluorocyclobutene, catalysts for gas-phase and liquid-phase reactions, and methods for separating perfluorobutadiene and perfluorocyclobutene. It significantly improves the production process, increases production efficiency, and reduces waste. Perfluorocyclobutene can be produced simultaneously with perfluorobutadiene. Furthermore, the catalyst is inexpensive, readily available, and easily industrialized.

[0018] To achieve the above objectives, this invention provides a continuous production method for perfluorobutene, using trifluorochloroethylene as raw material, comprising three steps: step one, step two, and step three. The method is characterized in that, in step one, the trifluorochloroethylene is vaporized and then continuously reacts with a modified catalyst in a fixed bed, wherein the mass hourly space velocity (MSV) of the trifluorochloroethylene feed is 180–3600 h⁻¹. -1 The catalytic reaction temperature is 300–800℃, and the reaction pressure is 0–2.0 MPa; the chemical formula for the reaction in the fixed bed is:

[0019]

[0020]

[0021]

[0022] The tail gas from the fixed bed is unreacted trifluorochloroethylene, and the reaction produces dichlorohexafluorobutene (C4F6Cl2 (chain)), dichlorohexafluorocyclobutane (C4F6Cl2 (ring)), perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts;

[0023] Step two involves passing the tail gas into a condensation reactor, which is filled with 2-700 mesh active zinc as a catalyst, and the temperature of the condensation reactor is 5-100℃. The dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed tail gas are condensed and dechlorinated in the condensation reactor, and are converted into perfluorobutadiene and perfluorocyclobutene, respectively.

[0024] The third step involves the generated and residual gases in the condensation reactor entering the condensation separator. The temperature of the condenser is controlled at -50 to 5°C for gas-liquid separation. The temperature is then adjusted to below -60°C to form a solid-liquid separation state. After solid-liquid separation, the separated solids and liquids are collected, stored, and further purified.

[0025] In step three, perfluorocyclobutene, with a melting point of -60°C, is solidified, while perfluorobutadiene remains in the liquid phase. The perfluorobutadiene and perfluorocyclobutene are condensed, while trifluorochloroethylene, in the gas phase, is returned to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse. Perfluorobutadiene remains in the liquid phase, while hexafluorocyclobutene remains in the solid phase. After separation, the purity of both perfluorobutadiene and hexafluorocyclobutene can reach over 99%. Further distillation purification can achieve a purity of over 99.999%.

[0026] According to a continuous production method of perfluorobutene of the present invention, a solvent is provided in the condensation reactor, wherein the solvent is an aprotic polar solvent of amide or / and ether or / and nitrile or / and sulfoxide or / and ketone.

[0027] According to a continuous production method of perfluorobutene of the present invention, in step one, the reaction temperature in the fixed bed is 400-600°C and the reaction pressure is 0-1.0 MPa.

[0028] According to a continuous production method of perfluorobutene of the present invention, in step two, the zinc in the condensation reactor is 100-700 mesh, and the temperature of the condensation reactor is 10-50°C.

[0029] According to a continuous production method of perfluorobutene of the present invention, the zinc needs to be activated before use. The activation method is to treat it in a 0.1-30 wt% hydrochloric acid, nitric acid and / or acetic acid solution for 1-60 min, and then quickly wash it with anhydrous alcohol until it is free of acidity.

[0030] A catalyst, primarily composed of molecular sieves with different crystal structures, either naturally or artificially synthesized.

[0031] A modified catalyst for producing perfluorobutadiene as described in claim 1, characterized in that the catalyst is modified using a ball milling or impregnation method, the modified catalyst comprising a metal active center and a support, wherein the support comprises one, two, or more combinations of molecular sieves with different crystal structures (natural or synthetic), SiO2, Al2O3, and activated carbon AC, and the metal of the metal active center is selected from Fe. 3+ Al 3+ Ce 3+ Cr 3+ Cr 6+ Cu 2+ Ag + K + Ca 2+ La 3 + Li + and Co 2+ One, two, or more combinations of salts are first dried at 80–200°C, then calcined at 200–500°C. The catalyst used for modification is in a 2–100 mesh form. The ball-milled modified catalyst is pretreated in an H2 atmosphere at 100–400°C for 1–10 h with an H2 space velocity of 100–36000 h⁻¹. -1 .

[0032] This invention provides a modified catalyst, wherein the modified catalyst requires activation, specifically within the range of 100–36000 h. -1 Activation was performed in an H2 atmosphere at 100–400 °C for 1–10 h, and at 100–36000 h. -1 The activation is carried out in an atmosphere of fluorine and chlorine-containing compounds at space velocity for 100-800°C for 1-10 hours, or a combination of two of these conditions, wherein the activation time is preferably 2-5 hours and the activation temperature is preferably 200-600°C.

[0033] This invention provides a modified catalyst in which, when modified by ball milling, the mass ratio of the support to the metal active center is (1-2):(1-2).

[0034] This invention provides a modified catalyst, wherein the concentration of the metal salt solution used in the modification process via the impregnation method is 0.01–5.0 mol·L⁻¹. -1 The metal loading is 0.1–30 wt%.

[0035] The present invention provides a modified catalyst, wherein the ball-milled modified catalyst is pretreated in an H2 atmosphere at 200-350°C for 2-5 hours; then activated in an atmosphere containing fluorine and chlorine compounds at an activation temperature of 200-350°C for 2-5 hours.

[0036] The purpose of this invention is to provide a continuous production method for perfluorobutene and a modified catalyst. By providing a continuous production method for perfluorobutene, the production process is significantly improved, production efficiency is increased, and the amount of waste is reduced. Perfluorocyclobutene can be co-produced simultaneously with perfluorobutadiene, effectively reducing production costs and making it suitable for mass production. Furthermore, by providing a catalyst for the continuous production of perfluoroolefins, catalyst costs are reduced, thereby lowering production costs, increasing production efficiency, and making the process easier to industrialize. In summary, the beneficial effects of this invention are: high production efficiency, environmental friendliness, low energy consumption, low production costs, and suitability for mass production. Attached Figure Description

[0037] Figure 1 This is a simplified flow chart of the continuous production method of perfluorobutene. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] This invention provides a continuous production method for perfluorobutene, using trifluorochloroethylene as raw material, comprising three steps: step one, step two, and step three. The key feature is that in step one, trifluorochloroethylene is vaporized and then continuously reacted with a modified catalyst in a fixed bed. The mass hourly space velocity (HHSV) of the trifluorochloroethylene feed is 180–3600 h⁻¹. -1 The catalytic reaction temperature is 300–800℃, and the reaction pressure is 0–2.0 MPa; the chemical formula for the reaction in the fixed bed is:

[0040]

[0041]

[0042]

[0043] The tail gas from the fixed bed is unreacted trifluorochloroethylene, and the reaction produces dichlorohexafluorobutene (C4F6Cl2 (chain)), dichlorohexafluorocyclobutane (C4F6Cl2 (ring)), perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts;

[0044] Step two involves passing the tail gas into a condenser reactor, which is filled with 2-800 mesh active zinc as a catalyst, and the temperature of the condenser reactor is 5-100℃. The dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed tail gas are condensed in the condenser reactor and undergo dechlorination reactions, converting into perfluorobutadiene and perfluorocyclobutene, respectively.

[0045] Step three involves the generation and residual gas in the condenser reactor entering the condenser separator. The temperature of the condenser is controlled at -50 to 5°C for gas-liquid separation. The temperature is then adjusted to below -60°C to form a solid-liquid separation state. After solid-liquid separation, the separated solids and liquids are collected, stored, and further purified.

[0046] In step three, perfluorocyclobutene, with a melting point of -60℃, is solidified, while perfluorobutadiene remains in the liquid phase. The perfluorobutadiene and perfluorocyclobutene are condensed, while trifluorochloroethylene, in the gas phase, is returned to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse. Perfluorobutadiene remains in the liquid phase, while hexafluorocyclobutene remains in the solid phase. After separation, the purity of both perfluorobutadiene and hexafluorocyclobutene can reach over 99%. Further distillation purification can achieve a purity of over 99.999%.

[0047] A simplified flow chart of the continuous production method of perfluorobutene can be found here. Figure 1 .

[0048] As a preferred embodiment, the condensation reactor contains a solvent, which is an aprotic polar solvent of the form of amides or / and ethers or / and nitriles or / and sulfoxides or / and ketones.

[0049] As a preferred method, in step one, the reaction temperature in the fixed bed is 400-600℃ and the reaction pressure is 0-1.0 MPa.

[0050] As a preferred method, in step two, the zinc in the condensation reactor is 100-700 mesh, and the temperature of the condensation reactor is 10-50℃.

[0051] As a preferred method, zinc needs to be activated before use. The activation method is to treat it in a 0.1-30 wt% hydrochloric acid, nitric acid and / or acetic acid solution for 1-60 min, and then quickly wash it with anhydrous alcohol until it is free of acidity.

[0052] A catalyst, primarily composed of molecular sieves with different crystal structures, either naturally or artificially synthesized.

[0053] A modified catalyst for producing perfluorobutadiene as described in claim 1, characterized in that the catalyst is modified using a ball milling or impregnation method, the modified catalyst comprising a metal active center and a support, the support comprising one, two, or more combinations of molecular sieves with different crystal structures (natural or synthetic), SiO2, Al2O3, and activated carbon AC, and the metal of the metal active center being selected from Fe. 3+ Al 3+ Ce 3+ Cr 3+ Cr 6+ Cu 2+ Ag + K + Ca 2+ La 3+ Li + and Co 2+ One, two, or more combinations of salts are first dried at 80–200℃, then calcined at 200–500℃. The catalyst used for modification is in the form of 2–100 mesh. The ball-milled modified catalyst is pretreated in an H2 atmosphere at 100–400℃ for 1–10 h with an H2 space velocity of 100–36000 h⁻¹. -1 .

[0054] As a preferred method, the modified catalyst needs to be activated, with an activation time of 100–36000 h. -1 Activation was performed in an H2 atmosphere at 100–400 °C for 1–10 h, and at 100–36000 h. -1 The activation is carried out in an atmosphere of fluorine and chlorine-containing compounds at space velocity for 100-800°C for 1-10 hours, or a combination of two of these conditions, wherein the activation time is preferably 2-5 hours and the activation temperature is preferably 200-600°C.

[0055] As a preferred method, when using ball milling for modification, the mass ratio of the carrier to the metal active center is (1-2):(1-2).

[0056] As a preferred method, when using the impregnation method for modification, the concentration of the metal salt solution used is 0.01–5.0 mol·L⁻¹. -1 The metal loading is 0.1–30 wt%.

[0057] As a preferred method, the ball-milled modified catalyst is pretreated in an H2 atmosphere at 200–350°C for 2–5 h; then activated in an atmosphere containing fluorine and chlorine compounds at 200–350°C for 2–5 h.

[0058] Example 1

[0059] 40-mesh activated zinc granules were packed into the gas-solid phase catalytic converter, and the raw material trifluorochloroethylene was fed at a space velocity of 360 h⁻¹. -1 A fixed bed at 600℃ is introduced to carry out thermal polymerization and isomerization reactions.

[0060] The tail gas from the fixed bed consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other byproducts from the reaction.

[0061] The exhaust gas is fed into a condenser reactor filled with 400-mesh activated zinc powder catalyst. The temperature of the condenser reactor is controlled at 45°C. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed exhaust gas are condensed and dechlorinated in the condenser reactor, converting into perfluorobutadiene and perfluorocyclobutene, respectively. These components, along with other components in the fixed-bed exhaust gas, then enter the condenser in the gas phase.

[0062] The temperature of the condenser is controlled at 0℃ to condense perfluorobutadiene and perfluorocyclobutene, while trifluorochloroethylene is in the gas phase and returns to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse.

[0063] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0064]

[0065] Example 2

[0066] Take 40-mesh active zinc granules and add them to the gas-solid phase catalytic converter at a mass ratio of 1:1 with KF. The raw material trifluorochloroethylene is fed at a space velocity of 360 h⁻¹. -1 A fixed bed at 600℃ is introduced to carry out thermal polymerization and isomerization reactions.

[0067] The tail gas from the fixed bed consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts.

[0068] The exhaust gas is fed into a condenser reactor filled with 400-mesh activated zinc powder catalyst. The temperature of the condenser reactor is controlled at 45°C. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed exhaust gas are condensed and dechlorinated in the condenser reactor, converting into perfluorobutadiene and perfluorocyclobutene, respectively. These components, along with other components in the fixed-bed exhaust gas, then enter the condenser in the gas phase.

[0069] The temperature of the condenser is controlled at 0℃ to condense perfluorobutadiene and perfluorocyclobutene, while trifluorochloroethylene is in the gas phase and returns to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse.

[0070] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0071]

[0072] Example 3

[0073] Take 40-mesh activated zinc granules and pack them into a gas-solid phase adsorption device with KF and Fe2O3 at a mass ratio of 1:1:1. The raw material trifluorochloroethylene is introduced at a space velocity of 360 h⁻¹. -1 A fixed bed at 600℃ is introduced to carry out thermal polymerization and isomerization reactions.

[0074] The tail gas from the fixed bed consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts.

[0075] The exhaust gas is fed into a condenser reactor filled with 400-mesh activated zinc powder catalyst. The temperature of the condenser reactor is controlled at 45°C. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed exhaust gas are condensed and dechlorinated in the condenser reactor, converting into perfluorobutadiene and perfluorocyclobutene, respectively. These components, along with other components in the fixed-bed exhaust gas, then enter the condenser in the gas phase.

[0076] The temperature of the condenser is controlled at 0℃ to condense perfluorobutadiene and perfluorocyclobutene, while trifluorochloroethylene is in the gas phase and returns to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse.

[0077] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0078]

[0079] Example 4

[0080] 40-mesh ZSM-5 molecular sieve was used as the catalyst and packed into a gas-solid phase adsorption device. The raw material, trifluorochloroethylene, was introduced at a space velocity of 360 h⁻¹. -1A fixed bed at 600℃ is introduced to carry out thermal polymerization and isomerization reactions.

[0081] The fixed-bed tail gas consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts. This tail gas is then passed into a condenser reactor.

[0082] In the condenser reactor, active zinc powder catalyst and organic solvent DMF are reacted. The condenser reactor temperature is controlled at 45℃. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed tail gas undergo dechlorination reactions, converting into perfluorobutadiene and perfluorocyclobutene, respectively. These, along with other components in the fixed-bed tail gas, enter the condenser in the gas phase. The condenser temperature is controlled at 0℃, condensing the perfluorobutadiene and perfluorocyclobutene. Trifluorochloroethylene, in the gas phase, returns to the front end of the reaction heat pipe, mixes with the feedstock trifluorochloroethylene, and then re-enters the fixed bed for reuse.

[0083] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0084]

[0085] Example 5

[0086] Take 50g of the finished granular product (average particle size approximately 20-40 mesh), with a specific surface area of ​​1000-1500 m². 2 ·g -1 Activated carbon with a molar concentration of 0.1 mol·L⁻¹ -1 The hydrochloric acid was refluxed in a water bath at 90°C for 4 hours, then repeatedly washed with distilled water until neutral, and dried in a forced-air dryer at 110°C for 4 hours before use.

[0087] Take 10g of activated carbon AC and trifluorochloroethylene for 360h -1 The gas is introduced into the reaction heat pipe at a high space velocity, while the temperature of the reaction heat pipe is simultaneously increased from room temperature to 600°C over 2 hours. At this space velocity and reaction temperature, trifluorochloroethylene undergoes thermal polymerization and isomerization reactions. The fixed-bed tail gas consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts. This tail gas is then introduced into a condenser reactor.

[0088] In the condenser reactor, active zinc powder catalyst and organic solvent DMF are reacted. The condenser reactor temperature is controlled at 45℃. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed tail gas undergo dechlorination reactions, converting into perfluorobutadiene and perfluorocyclobutene, respectively. These, along with other components in the fixed-bed tail gas, enter the condenser in the gas phase. The condenser temperature is controlled at 0℃, condensing the perfluorobutadiene and perfluorocyclobutene. Trifluorochloroethylene, in the gas phase, returns to the front end of the reaction heat pipe, mixes with the feedstock trifluorochloroethylene, and then re-enters the fixed bed for reuse.

[0089] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0090]

[0091] Example 6

[0092] Take 50g of the finished granular product (average particle size approximately 20-40 mesh), with a specific surface area of ​​1000-1500 m². 2 ·g -1 Activated carbon with a molar concentration of 0.1 mol·L⁻¹ -1 The hydrochloric acid was refluxed in a water bath at 90°C for 4 hours, then repeatedly washed with distilled water until neutral, and dried in a forced-air dryer at 110°C for 4 hours before use.

[0093] Take 10g of activated carbon AC and add 0.1mol·L⁻¹ -1 10.5 ml of Zn(NO3)2 solution was used for immersion for 24 hours, followed by overnight drying in a 110℃ forced-air drying oven. A certain amount of sample was placed in a gas-solid phase adsorption device and activated in situ at 350℃ in an H2 atmosphere for 2 hours. The feed gas, trifluorochloroethylene, was then introduced at a space velocity of 360 h⁻¹. -1 Simultaneously, the temperature is raised to 600℃ for 2 hours to carry out thermal polymerization and isomerization reactions. The tail gas from the fixed bed consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts.

[0094] The exhaust gas is fed into a condenser reactor filled with active zinc powder catalyst. The temperature of the condenser reactor is controlled at 45°C. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed exhaust gas undergo dechlorination reactions, converting into perfluorobutadiene and perfluorocyclobutene, respectively, and then enter the condenser in the gas phase along with other components in the fixed-bed exhaust gas.

[0095] The temperature of the condenser is controlled at 0℃ to condense perfluorobutadiene and perfluorocyclobutene, while trifluorochloroethylene is in the gas phase and returns to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse.

[0096] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0097]

[0098] Example 7

[0099] Weigh 10g of ZSM-5 and 20g of Zn(NO3)2 solid, place them in a ball mill and grind them thoroughly for 60 minutes. Then remove them and calcine them at 350℃ for 8 hours to promote Zn production. 2+ Dispersed on the surface of activated carbon.

[0100] A certain amount of sample was placed in a gas-solid phase adsorption device and activated in situ at 350℃ in an H2 atmosphere for 2 hours. The feed gas, trifluorochloroethylene, was then introduced at a space velocity of 360 h⁻¹. -1 Simultaneously, the temperature is raised to 600℃ over 2 hours for thermal polymerization and isomerization reactions. The fixed-bed tail gas consists of unreacted trifluorochloroethylene, dichlorohexafluorobutene, dichlorohexafluorocyclobutane, perfluorobutadiene, hexafluorocyclobutene, and trace amounts of other reaction byproducts. This tail gas is then introduced into a condenser reactor.

[0101] An active zinc powder catalyst is used in the condenser reactor. The temperature of the condenser reactor is controlled at 45℃. Dichlorohexafluorobutene and dichlorohexafluorocyclobutane in the fixed-bed tail gas undergo dechlorination reactions, converting into perfluorobutadiene and perfluorocyclobutene, respectively, and then enter the condenser in the gas phase along with other components in the fixed-bed tail gas.

[0102] The temperature of the condenser is controlled at 0℃ to condense perfluorobutadiene and perfluorocyclobutene, while trifluorochloroethylene is in the gas phase and returns to the front end of the reaction heat pipe. It is then mixed with the raw material trifluorochloroethylene and reintroduced into the fixed bed for reuse.

[0103] After collecting liquid perfluorobutadiene and perfluorocyclobutene into 2 / 3 of the condenser volume, the collection is switched to another container, and the original condenser is replaced with dry ice condensation. Perfluorocyclobutene, with a melting point of -60℃, is solidified into a solid, while perfluorobutadiene remains in the liquid phase. After solid-liquid separation, the contents of both perfluorobutadiene and perfluorocyclobutene are above 99%.

[0104]

[0105] In summary, this invention provides a continuous production method for perfluorobutene, significantly improving the production process, increasing production efficiency, and reducing waste. It can simultaneously produce perfluorocyclobutene, effectively reducing production costs and making it suitable for mass production. Furthermore, by providing a catalyst for the continuous production of perfluoroolefins, it reduces catalyst costs, thereby lowering overall production costs, increasing efficiency, and facilitating industrialization. The beneficial effects of this invention are: high production efficiency, environmental friendliness, low energy consumption, low production costs, and suitability for mass production.

[0106] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A continuous production method for perfluorobutene, using trifluorochloroethylene as raw material, comprising three steps: step one, step two, and step three, characterized in that... Step one involves the following: after being vaporized, the trifluorochloroethylene enters a fixed bed and continuously reacts with the modified catalyst. The mass hourly space velocity (MSV) of the trifluorochloroethylene feed is 180–3600 h⁻¹. -1 The catalytic reaction temperature is 300–800℃, and the reaction pressure is 0–2.0 MPa; The second step involves passing the exhaust gas into a condensation reactor, which is filled with 100-700 mesh active zinc as a catalyst, and the temperature of the condensation reactor is 10-50°C. The condensation reactor contains a solvent, which is an aprotic polar solvent of amides or / and ethers or / and nitriles or / and sulfoxides or / and ketones. The third step involves the generated and residual gas in the condensation reactor entering the condensation separator. The temperature of the condenser is controlled at -50 to 5°C for gas-liquid separation. The temperature is then adjusted to below -60°C to form a solid-liquid separation state. After solid-liquid separation, the separated solids and liquids are collected, stored, and further purified. The modified catalyst is modified using ball milling or impregnation methods. The modified catalyst consists of a metal active center and a support. The support comprises one, two, or more of the following: a molecular sieve with different crystal structures (natural or synthetic), SiO2, Al2O3, and activated carbon AC. The metal of the metal active center is selected from Fe. 3+ Al 3 + Ce 3+ Cr 3+ Cr 6+ Cu 2+ Ag + K + Ca 2+ La 3+ Li + and Co 2+ One, two, or more combinations of salts are first dried at 80–200°C and then calcined at 200–500°C. The catalyst used for modification is in the form of 2–100 mesh. The modified catalyst needs to be activated, preferably within the range of 100–36000 h. -1 Activation was performed in an H2 atmosphere at 100–400 °C for 1–10 h, and at 100–36000 h. -1 One or a combination of two of the following: activation at 100–800 °C for 1–10 h in an atmosphere of fluorine- or chlorine-containing compounds at space velocity.

2. The continuous production method of perfluorobutene according to claim 1, characterized in that, In step one, the reaction temperature in the fixed bed is 400–600°C, and the reaction pressure is 0–1.0 MPa.

3. The continuous production method of perfluorobutene according to claim 1, characterized in that, The zinc needs to be activated before use. The activation method is to treat it in a 0.1-30 wt% hydrochloric acid, nitric acid and / or acetic acid solution for 1-60 min, and then quickly wash it with anhydrous alcohol until it is free of acidity.

4. The continuous production method of perfluorobutene according to claim 1, characterized in that, When the modified catalyst is modified by ball milling, the mass ratio of the support to the metal active center is (1-2):(1-2).

5. The continuous production method of perfluorobutene according to claim 1, characterized in that, When the modified catalyst is modified using the impregnation method, the concentration of the metal salt solution used is 0.01–5.0 mol·L⁻¹. -1 The metal loading is 0.1–30 wt%.

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