Preparation device of octafluorocyclopentene and use method thereof

Abstract

The invention relates to an octafluorocyclopentene preparation device and a use method thereof.The device comprises a pyrolyzing furnace, a filter, a condenser, a water washing device, an alkali washing device, a water removing device and a deep cooling device which are connected through pipelines, a pyrolyzing pipe is arranged in the pyrolyzing furnace, a composite catalyst is placed in the pyrolyzing pipe, and the filter is arranged in the filter; the front end of the distillation tower is connected with a raw material gas tank and a purging gas tank through a three-way pipe, the rear part of the distillation tower is sequentially connected to a filter, a condenser, a water washing device, an alkali washing device, a polymerization inhibition device, a water removal device and a cryogenic device, and finally collected condensate is distilled. The device is simple and reasonable in overall structure, simple in preparation process, efficient and safe.

Description

An apparatus for preparing octafluorocyclopentene and its method of use Technical Field

[0001] This invention belongs to the field of semiconductor technology of fluorine-containing electronic etching gases, and relates to an apparatus for preparing octafluorocyclopentene and its usage method. Background Technology

[0002] Octafluorocyclopentene (ZFL-58), with a boiling point of 27°C and a density of 1.58 g / cm³, is a toxic, non-flammable, low-boiling-point colorless liquid. It is a saturated fluoroalkane with a low global warming potential (GWP100 = 78.1) and zero ozone depletion potential (ODP), and an atmospheric lifetime of 1.1 years. Octafluorocyclopentene is used for etching silicon dioxide and silicon nitride dielectric materials, particularly excelling in the ultrafine etching of oxide thin films. The etching process involves the ionization of C₅F₈ into plasma and free radicals, such as CF*, CF₂*, and CF₃*, under a high ionization field. These radicals then react with SiO₂ (CF* + SiO₂ → SiF₄ + CO / CO₂) to complete the etching. During the reaction, phosphorus (F) plays an etching role, while carbon (C) contributes to the formation of (CH)n polymers. C5F8 has a low F / C ratio, high etching selectivity, and is suitable for devices with smaller linewidths. It produces ideal aspect ratios in silicon and silicon oxide etching, forming a polymer film (photoresist) that protects the sidewalls during etching. It is hydrogen-free, allowing for the etching of deep and narrow openings. Its high molecular weight results in strong etching power. With a low GWP (global warming potential) and short atmospheric lifetime, it is environmentally friendly, making it one of the most ideal alternatives to etchant C4F8. Due to its green and environmentally friendly properties, it will be used as a next-generation environmentally friendly etchant electronic specialty gas to replace second-generation traditional high-temperature-effect electronic specialty gases. It belongs to the next generation of fluorinated electronic specialty gases for development, application, and promotion. Typically, C5F8 is formulated with other inorganic gases such as O2 and Ar to form etchants for use in the etching process of semiconductor device manufacturing, especially for etching the smallest geometric features (such as the width of interconnects, contacts, trenches, etc.) with both size and selectivity. Furthermore, octafluorocyclopentene is a five-membered ring with similar carbon atom angles, exhibiting lower stress than three- or four-membered cycloalkanes and a more stable chemical structure. Most existing synthetic methods use perfluorocyclopentene and its fluorochloro derivatives as intermediates, and octafluorocyclopentene as a precursor to further synthesize octafluorocyclopentene.For example, patent CN112209805A describes the process of obtaining octafluorocyclopentene from perfluorocyclopentene, sodium trifluoromethanesulfonate, and ferrocene through fluorination under mercury irradiation and distillation, with a final product yield of 98.5%. This process has extremely high equipment requirements and is not suitable for large-scale industrial production. Patent CN110563545B describes the process of obtaining octafluorocyclopentene from cyclopentene through chlorination, negative pressure distillation, fluoride fluorination, and distillation. Data shows that in 2023, China's cyclopentene production capacity was 700,000 tons, with a price of 35,000 yuan / ton. This process has sufficient raw material supply, but involves many hazardous chemical unit operations, a wide range of highly toxic substances, a high risk factor, and many by-product impurities. DuPont and Zeon Corporation of Japan use 1,2 Octafluorocyclopentene is obtained from 1,2-dichlorohexafluorocyclopentene and alkali metal potassium fluoride through a series of pretreatments and distillations, achieving a purity of 99.98%. However, this raw material, 1,2-dichlorohexafluorocyclopentene, is limited in supply, expensive, and highly toxic. Therefore, it is necessary to consider using other readily available and safer raw materials to further synthesize octafluorocyclopentene. Patents CN110637001A and CN107188778B mention 1-chloroheptafluorocyclopentene as a raw material, and both involve the direct synthesis of octafluorocyclopentene from fluorochloro compounds of cyclopentene. These methods face the same problems as the above, including limited supply and high price, hindering industrial-scale production. Therefore, further improvements to the synthesis method of octafluorocyclopentene are necessary.

[0003] To address this issue, an apparatus for preparing octafluorocyclopentene and its method of use were designed to overcome the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a simple and reasonable apparatus for preparing octafluorocyclopentene and its method of use, which is simple in structure, easy in preparation process, and highly efficient and safe.

[0005] The present invention is achieved through the following technical solution: The device includes a pyrolysis furnace, a filter, a condenser, a water washing device, an alkaline washing device, a polymerization inhibitor device, a dehydration device, and a cryogenic device, which are connected to each other by pipelines. The pyrolysis furnace is provided with a pyrolysis tube, in which a composite catalyst is placed. Its front end is connected to the raw material gas tank and the purge gas tank through a three-way pipe, and its rear end is sequentially connected to the filter, condenser, water washing device, alkaline washing device, polymerization inhibitor device, dehydration device, and cryogenic device. Finally, the collected condensate is distilled.

[0006] Preferably, the purging gas in the purging gas tank is N2, Ar, or He gas.

[0007] Preferably, the pyrolysis tube is a stainless steel tube or a quartz tube with a diameter of 40 mm.

[0008] Preferably, the catalyst is a metal or metal oxide catalyst.

[0009] Preferably, at least one alkaline washing device or a water washing device is provided.

[0010] A method for using an apparatus for preparing octafluorocyclopentene, the method comprising the following steps: S1) A composite catalyst is loaded into a pyrolysis tube with a diameter of φ40mm, and purge gas is continuously introduced to expel air from the apparatus. After heating by an electric heating program, the discharge valve on the raw material gas tank is opened to release perfluorocyclohexene. The perfluorocyclohexene rapidly vaporizes and enters the pyrolysis tube, with the flow rate controlled at 200~300 mL / min and the residence time at 0.5~3s; S2) The pyrolysis gas passes through a filter and undergoes at least two stages of heat exchange to reach 30~50℃; S3) The condensed gas undergoes water washing and alkali washing processes in a water washing device and an alkali washing device, respectively, and then a polymerization inhibitor and a dehydration device are added before deep cooling to obtain condensate; S4) The condensate collected in S3) is distilled, and the boiling range fraction at 30~45℃ is collected, stored, and numbered. The crude product yield and purity are then determined by gas chromatography analysis.

[0011] Preferably, the pyrolysis temperature in step S1 is 400~600℃ and the reaction pressure is 0~0.5 MPa.

[0012] Preferably, the mass ratio of catalyst to feed gas in step S1 is 1:3.

[0013] Preferably, the catalyst filling method in step S1 is a bundling type filling.

[0014] Preferably, the alkaline solution in the alkaline washing device in step S3 is a NaOH solution with a concentration of 10%~15%W.

[0015] Preferably, the composite catalyst in step S1 is SiO2-Al2O3.

[0016] The beneficial effects of the present invention are as follows: Compared with the existing technology, the octafluorocyclopentene preparation device and its method designed in this invention use non-highly toxic raw materials to prepare octafluorocyclopentene, reducing the number of hazardous chemical unit operation links and thus reducing the risk to a certain extent. The process has low toxicity and is less harmful to operators. The overall preparation process is simple, the equipment requirements are low, and the industrialization investment cost is small. Moreover, the present invention can obtain a high purity of the target product crude product. Attached Figure Description

[0017] Figure 1 is a flowchart of the process for obtaining crude gas by pyrolysis according to the present invention.

[0018] Figure 2 is a flow chart of the crude gas purification process of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to more clearly understand the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "lateral", and "vertical" is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this invention, and is not intended to indicate or imply that the device or component referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] The invention will now be described in detail with reference to the accompanying drawings: As shown in Figures 1-2, an apparatus for preparing octafluorocyclopentene includes a pyrolysis furnace 1, a filter 2, a condenser 3, a water washing device 4, an alkaline washing device 5, a dehydration device 6, a polymerization inhibitor 12, and a cryogenic device 7, all connected by pipes. The pyrolysis furnace 1 contains a pyrolysis tube 8, within which a composite catalyst is placed. Its front end is connected to a raw material gas tank 10 and a purge gas tank 11 via a three-way pipe 9, and its rear end is sequentially connected to the filter 2, condenser 3, water washing device 4, alkaline washing device 5, polymerization inhibitor 12, dehydration device 6, and cryogenic device 7. Finally, the collected condensate is distilled. The purge gas in the purge gas tank 11 is N2, Ar, He, or other gases. The pyrolysis tube 8 is a stainless steel or quartz tube with a diameter of 40 mm. The catalyst is a metal or metal oxide catalyst. At least one alkaline washing device 5 or a water washing device 4 is provided.

[0022] A method for using an apparatus for preparing octafluorocyclopentene, the method comprising the following steps: S1) A composite catalyst is loaded into a pyrolysis tube 8 with a diameter of φ40mm, and purge gas is continuously introduced to expel air from the apparatus. After heating by an electric heating program, the discharge valve 13 on the raw material gas tank 10 is opened to release perfluorocyclohexene. The perfluorocyclohexene rapidly vaporizes and enters the pyrolysis tube 8, with the flow rate controlled at 200~300 mL / min and the residence time at 0.5~3s; S2) The pyrolysis gas passes through a filter 2 and undergoes at least two stages of heat exchange to reach 30~50℃; S3) The condensed gas undergoes water washing and alkali washing processes in a water washing device 4 and an alkali washing device 5, respectively, and then a polymerization inhibitor and a dehydration device 6 are added before deep cooling to obtain condensate; S4) The condensate collected in S3) is distilled, and the boiling range fraction at 30~45℃ is collected, stored, and numbered. The crude product yield and purity are then determined by gas chromatography analysis.

[0023] In step S1, the pyrolysis temperature is 400-600℃, preferably 500-530℃, and the reaction pressure is 0-0.5 MPa, preferably 0.1-0.3 MPa. The mass ratio of catalyst to feed gas in step S1 is 1:3. The catalyst in step S1 is packed using a bundled packing method. The alkaline solution in the alkaline washing device 5 in step S3 is a NaOH solution with a concentration of 10%-15%W. The composite catalyst in step S1 is SiO2-Al2O3.

[0024] The technical features of this invention are as follows: Overall control method: The reaction pressure is controlled by controlling the raw material flow rate, the inert component flow rate, and the flow meter size; The pyrolysis furnace adopts a 304 material pyrolysis reactor with a pressure resistance of 10MPa and a temperature resistance of 1200℃; Supporting facilities: Water washing and alkali washing are added to remove water-soluble impurities generated in the pyrolysis unit; Water washing: Process water, at room temperature and pressure; Alkali washing: 10%~15% (w) liquid alkali (NaOH solution), at room temperature and pressure; Filter: Generally a wire mesh filter is added after the pyrolysis tube to prevent particulate matter from being carried out and clogging the pipeline; Cryogenic device: The pyrolysis gas temperature is high, and it should be cooled down as soon as possible at the outlet to prevent the generation of impurity gases or the polymerization to form tar and other substances during the pyrolysis process. A two-stage condensation device is added after the wire mesh filter to perform secondary heat exchange on the pyrolysis gas to cool it down to 30~50℃ before product purification.

[0025] Example 1: A method for preparing octafluorocyclopentene, comprising the following steps: S1) A composite catalyst is packed into a stainless steel tube with a diameter of φ40mm. Ar is continuously introduced to purge the air from the device. After heating to 500℃ using an electric heating program, the perfluorocyclohexene discharge valve is opened. The perfluorocyclohexene rapidly vaporizes and enters the pyrolysis tube. The flow rate is controlled at 250~300 mL / min, and the residence time is 0.5~2s. S2) The pyrolysis gas passes through a wire mesh filter and undergoes two-stage heat exchange to reach 40~50℃. S3) The condensed gas is subjected to water washing, alkali washing, and other processes, followed by deep cooling to obtain condensate. S4) The condensate collected in S3) is distilled, and the fraction with a boiling range of 35~42℃ is collected and stored, labeled H1. Product H1 is analyzed by gas chromatography, and the crude yield of octafluorocyclopentene is 42.5%, with a purity of 90.5%.

[0026] Example 2: A method for preparing octafluorocyclopentene, comprising the following steps: S1) A composite catalyst is packed into a stainless steel tube with a diameter of φ40mm. Ar is continuously introduced to purge the air from the device. After heating to 500℃ using an electric heating program, the perfluorocyclohexene discharge valve is opened. The perfluorocyclohexene rapidly vaporizes and enters the pyrolysis tube. The flow rate is controlled at 150~200 mL / min, and the residence time is 1~3s. S2) The pyrolysis gas passes through a wire mesh filter and undergoes two-stage heat exchange to reach 40~50℃. S3) The condensed gas is subjected to water washing, alkali washing, and other processes, followed by deep cooling to obtain condensate. S4) The condensate collected in S3) is distilled, and the fraction with a boiling range of 35~42℃ is collected, stored, and labeled as H2. Product H2 is analyzed by gas chromatography, and the crude yield of octafluorocyclopentene is 27.8%, with a purity of 82.63%.

[0027] Example 3: A method for preparing octafluorocyclopentene, comprising the following steps: S1) A composite catalyst is packed into a stainless steel tube with a diameter of φ40mm. Ar is continuously introduced to purge the air from the device. After heating to 550℃ using an electric heating program, the perfluorocyclohexene discharge valve is opened. The perfluorocyclohexene rapidly vaporizes and enters the pyrolysis tube. The flow rate is controlled at 250~300 mL / min, and the residence time is 0.5~3s. S2) The pyrolysis gas passes through a wire mesh filter and undergoes two-stage heat exchange to reach 40~50℃. S3) The condensed gas is subjected to water washing, alkali washing, and other processes, followed by deep cooling to obtain condensate. S4) The condensate collected in S3) is distilled, and the fraction with a boiling range of 35~42℃ is collected and stored, labeled H3. Product H3 is analyzed by gas chromatography, and the crude yield of octafluorocyclopentene is 37.6%, with a purity of 87.6%.

[0028] Comparative Experiment 1: The composite catalyst in S2 was replaced with an equal amount of zeolite, and all other steps were the same as in Example 1. The resulting product was denoted as H4. Gas chromatography analysis of product H4 showed that the crude yield of octafluorocyclopentene was 32.7%, and the purity was 52.4%.

[0029] Comparative Experiment 2: The carrier gas Ar was removed in S1), and everything else remained the same as in Example 1. The resulting product was denoted as H5. Gas chromatography analysis of product H5 showed that the yield of octafluorocyclopentene was 0%.

[0030] The above examples demonstrate that, under suitable carrier gas and catalyst conditions, product yield and selectivity can be optimized. Compared with existing technologies, the method for preparing octafluorocyclopentene according to this invention provides ample raw material supply, high crude product purity, and avoids the use of highly toxic hazardous chemicals, ensuring high process safety, reducing toxicity to experimental personnel and operators, lowering equipment requirements, and providing a certain reference for subsequent industrial-scale production.

[0031] The specific embodiments described herein are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. An apparatus for preparing octafluorocyclopentene, characterized in that... The device includes a pyrolysis furnace, a filter, a condenser, a water washing device, an alkaline washing device, a polymerization inhibitor device, a dehydration device, and a cryogenic device, all connected by pipes. The pyrolysis furnace contains a pyrolysis tube, inside which a composite catalyst is placed. Its front end is connected to a raw material gas tank and a purge gas tank via a three-way pipe, and its rear end is sequentially connected to the filter, condenser, water washing device, alkaline washing device, polymerization inhibitor device, dehydration device, and cryogenic device. Finally, the collected condensate is distilled.

2. The apparatus for preparing octafluorocyclopentene according to claim 1, characterized in that: The purging gas in the purging gas tank is N2, Ar, or He gas.

3. The apparatus for preparing octafluorocyclopentene according to claim 1, characterized in that: The pyrolysis tube is a stainless steel tube or a quartz tube with a diameter of 40 mm.

4. The apparatus for preparing octafluorocyclopentene according to claim 1, characterized in that: The catalyst is a metal or metal oxide catalyst.

5. The apparatus for preparing octafluorocyclopentene according to claim 1, characterized in that: At least one alkaline washing device or water washing device is provided.

6. A method of using the apparatus for preparing octafluorocyclopentene according to any one of claims 1-5, characterized in that, The method includes the following steps: S1) The composite catalyst is loaded into a pyrolysis tube with a diameter of φ40mm. Purge gas is continuously introduced to remove air from the device. After heating by an electric heating program, the discharge valve on the raw material gas tank is opened to release perfluorocyclohexene. The perfluorocyclohexene is rapidly vaporized and enters the pyrolysis tube. The flow rate is controlled at 200~300 mL / min and the residence time is 0.5~3s; S2) The pyrolysis gas is filtered and then subjected to at least two stages of heat exchange to reach 30~50℃; S3) The condensed gas is subjected to water washing and alkali washing processes in a water washing device and an alkali washing device, respectively. Then, a polymerization inhibitor and a dehydration device are added, and then the gas is cryogenically cooled to obtain condensate. S4) The condensate collected in S3) is distilled to collect the boiling range fraction of 30~45℃, which is then stored and numbered. The crude product yield and purity are then determined by gas chromatography.

7. The apparatus for preparing octafluorocyclopentene according to claim 1, characterized in that: In step S1, the pyrolysis temperature is 400~600℃ and the reaction pressure is 0~0.5 MPa.

8. The apparatus for preparing octafluorocyclopentene according to claim 6, characterized in that: In step S1, the mass ratio of catalyst to raw gas is 1:3, and the catalyst is filled in a bundled packing method.

9. The apparatus for preparing octafluorocyclopentene according to claim 6, characterized in that: The alkaline solution in the alkaline washing device in step S3 is a NaOH solution with a concentration of 10%~15%W.

10. The apparatus for preparing octafluorocyclopentene according to claim 6, characterized in that... The feed gas in S1 is perfluorocyclohexene, and its chemical equation is: 2 C6F10 → 2 C5F8 + C2F4.

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