Method and device for purifying hexafluorobutadiene
By purifying hexafluorobutadiene using a white pebble adsorption device and a molecular sieve adsorption device, the problem of complex and high cost in the prior art purification method is solved, and a high-purity and low-cost hexafluorobutadiene purification effect is achieved.
Patent Information
- Application Number
- CN202510132973.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-06
- Publication Date
- 2025-05-27
AI Technical Summary
The existing hexafluorobutadiene purification methods are complex in operation and high in cost, making them difficult to apply on a large scale.
The hydrogen fluoride in the hexafluorobutadiene raw material was chemically adsorbed by a white pebble adsorption device to obtain a preliminarily purified mixture, and further adsorption and distillation were carried out through a molecular sieve adsorption device and a distillation tower to obtain a preset purity hexafluorobutadiene.
It has achieved efficient purification of hexafluorobutadiene, which is simple to operate and low cost, is suitable for large-scale applications, with a purity of 99.999%, meeting the needs of semiconductor etching processes.
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Figure CN120040267A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of purification of hexafluorobutadiene, and particularly to a purification method and a purification device for hexafluorobutadiene. Background Art
[0002] Hexafluorobutadiene (C 4 F 6 , CAS No.: 685-63-2) is a colorless and odorless gas that can be liquefied under pressure. It is toxic and flammable, and is an important monomer material for preparing various new fluororesins, fluoroplastics, and fluororubbers. Moreover, hexafluorobutadiene can be used as a dry etching gas in integrated circuit manufacturing.
[0003] Hexafluorobutadiene applied in semiconductor etching processes needs to have high purity. Currently, the commonly used purification methods for hexafluorobutadiene mainly include adsorption method, distillation method, extraction method, etc. Among them, the adsorption-distillation method is the most commonly used method. However, in the prior art, the adsorption-distillation method generally has complex operations and high costs, making it difficult to be applied on a large scale. Summary of the Invention
[0004] In view of this, the present application provides a purification method and a purification device for hexafluorobutadiene to solve the problems of complex purification methods and high costs of hexafluorobutadiene in the prior art.
[0005] To solve the above technical problems, a technical solution adopted by the present application is: to provide a purification method for hexafluorobutadiene, including: introducing a hexafluorobutadiene raw material into a white pebble adsorption device to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material to obtain a first mixture after preliminary purification; performing adsorption and distillation on the first mixture to obtain hexafluorobutadiene with a preset purity.
[0006] According to an embodiment of the present application, the white pebble adsorption device is filled with natural white pebbles, and the natural white pebbles contain calcium carbonate; the step of chemically adsorbing hydrogen fluoride in the hexafluorobutadiene raw material to obtain a first mixture after preliminary purification includes: calcium carbonate in the natural white pebbles reacts with hydrogen fluoride in the hexafluorobutadiene raw material to generate a first mixture, and the first mixture includes hexafluorobutadiene, calcium fluoride, water, and carbon dioxide.
[0007] According to an embodiment of the present application, the step of performing adsorption and distillation on the first mixture to obtain hexafluorobutadiene with a preset purity includes: introducing the first mixture into a molecular sieve adsorption device to remove water and carbon dioxide in the first mixture to obtain a second mixture; performing distillation on the second mixture to obtain hexafluorobutadiene with a preset purity.
[0008] According to an embodiment of the present application, before introducing the first mixture into the molecular sieve adsorption device, the molecular sieve adsorption device is pretreated. The steps for pretreating the molecular sieve adsorption device include: introducing a predetermined amount of the first mixture into the molecular sieve adsorption device until the first mixture is completely adsorbed and penetrates through the molecular sieve adsorption device; regenerating and activating the molecular sieve adsorbent to obtain the pretreated molecular sieve adsorption device.
[0009] According to an embodiment of the present application, in the step of introducing the first mixture into the molecular sieve adsorption device to remove water and carbon dioxide in the first mixture to obtain the second mixture, the temperature range is 10°C to 25°C.
[0010] According to an embodiment of the present application, the steps of adsorbing and rectifying the first mixture to obtain hexafluorobutadiene with a preset purity include: introducing the second mixture into the first rectification tower, where the first rectification tower is used to remove the heavy components in the second mixture to obtain the third mixture; introducing the third mixture into the second rectification tower, where the second rectification tower is used to remove the light components in the third mixture to obtain hexafluorobutadiene with a preset purity.
[0011] According to an embodiment of the present application, the preset purity is greater than or equal to 99.999%.
[0012] According to an embodiment of the present application, the molecular sieve adsorption device is filled with 5A molecular sieve.
[0013] A second aspect of the present application provides a hexafluorobutadiene purification device applicable to the above-mentioned hexafluorobutadiene purification method. The hexafluorobutadiene purification device includes: a white pebble adsorption device, a molecular sieve adsorption device, and a rectification device that are connected in sequence; the white pebble adsorption device is used to adsorb hydrogen fluoride in the hexafluorobutadiene raw material, and the molecular sieve adsorption device and the rectification device respectively perform adsorption and rectification on the first mixture to obtain hexafluorobutadiene with a preset purity.
[0014] According to an embodiment of the present application, the rectification device includes a first rectification tower and a second rectification tower; the first rectification tower is used to remove the heavy components; the second rectification tower is used to remove the light components.
[0015] The beneficial effect of the present application is: to provide a hexafluorobutadiene purification method, which includes: introducing the hexafluorobutadiene raw material into the white pebble adsorption device to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material to obtain the preliminarily purified first mixture; performing adsorption and rectification on the first mixture to obtain hexafluorobutadiene with a preset purity. In the present application, the white pebble adsorption device is used to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material, which is simple in operation and low in cost, and can effectively purify hexafluorobutadiene. Description of the Drawings
[0016] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings. Among them:
[0017] Figure 1 is a schematic structural diagram of a purification device for hexafluorobutadiene provided by an embodiment of the present application;
[0018] Figure 2 is a schematic flow diagram of a purification method for hexafluorobutadiene provided by an embodiment of the present application;
[0019] Figure 3 is a schematic flow diagram of a purification method for hexafluorobutadiene provided by another embodiment of the present application;
[0020] Figure 4 is a schematic flow diagram of a purification method for hexafluorobutadiene provided by still another embodiment of the present application;
[0021] Figure 5 is a schematic flow diagram of a purification method for hexafluorobutadiene provided by another embodiment of the present application. Detailed Embodiments
[0022] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will provide a detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, rather than limiting the present application. Additionally, it should be noted that for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, rather than all the structures. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.
[0023] Referring to "embodiments" in this context means that the specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.
[0024] Hexafluorobutadiene can be used as a dry etching gas in integrated circuit manufacturing. The general purity requirement of hexafluorobutadiene applied in semiconductor etching processes is between 99.99% and 99.999%, and further purification is required on the basis of the crude product. At present, the commonly used purification methods of hexafluorobutadiene mainly include adsorption method, distillation method, extraction method, etc. Among them, the adsorption - rectification method is the most commonly used method, which uses an adsorbent to adsorb impurities in hexafluorobutadiene and then realizes purification through two - stage rectification. However, traditional adsorbents, such as activated carbon, silica gel, etc., will undergo isomer rearrangement when adsorbing hexafluorobutadiene, generating new impurities (hexafluoro - 2 - butyne), thus reducing the purification effect. In current technologies, methods for modifying and pretreating the adsorbent are proposed, such as surface - treating the adsorbent, loading active components, etc., to improve its adsorption performance and selectivity. However, these methods are generally complex in operation and high in cost, and it is difficult to apply them on a large scale.
[0025] Referring to Figure 1 and Figure 2 , Figure 1 FIG. is a schematic structural diagram of a purification device for hexafluorobutadiene provided by an embodiment of the present application. Figure 2 FIG. is a schematic flow diagram of a purification method for hexafluorobutadiene provided by an embodiment of the present application.
[0026] The present application provides a purification method for hexafluorobutadiene, and the purification method includes the following steps:
[0027] Step S210: Pass the hexafluorobutadiene raw material into the white pebble adsorption device 100 to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material, and obtain a first mixture after preliminary purification.
[0028] Among them, the white pebble adsorption device 100 is filled with natural white pebbles, and the natural white pebbles contain calcium carbonate. The step S210 of chemically adsorbing hydrogen fluoride in the hexafluorobutadiene raw material to obtain a first mixture after preliminary purification includes: calcium carbonate in the natural white pebbles reacts with hydrogen fluoride in the hexafluorobutadiene raw material to generate a first mixture, and the first mixture includes hexafluorobutadiene, calcium fluoride, water and carbon dioxide.
[0029] The white pebbles include natural white pebbles directly obtained from nature, or can also be white pebbles used after simple processing such as screening and cleaning after obtaining natural white pebble raw materials. The white pebbles are natural limestone, commonly used in building materials or garden layout, etc., with low price and easy to obtain. Pass the hexafluorobutadiene raw material in the raw material tank 104 into the adsorption device filled with natural white pebbles. The main chemical component of the natural white pebbles is calcium carbonate (CaCO 3 ), and the chemical adsorption reaction between calcium carbonate and hydrogen fluoride, the impurity in the hexafluorobutadiene raw material, is as follows:
[0030] CaCO 3+ 2HF → CaF 2 + H 2 O + CO 2 ↑.
[0031] Calcium carbonate reacts with hydrogen fluoride to form a first mixture, which at least includes hexafluorobutadiene, calcium fluoride, water and carbon dioxide.
[0032] After removing hydrogen fluoride from the hexafluorobutadiene raw material, subsequent steps of adsorption and rectification can reduce the subsequent purification pressure. Removing hydrogen fluoride first can also improve the purity of the final product. Generally, the relatively high-purity calcium carbonate or calcium bicarbonate available on the market is in powder form. Using the powdered adsorbent as the filling material of the chemical adsorption device will result in high resistance and low adsorption efficiency when directly introducing hexafluorobutadiene. Therefore, generally, calcium carbonate or calcium bicarbonate needs to be made into blocks or granules as the filling material, which increases the preparation process and cost. However, in this application, natural white pebbles are used as the filler of the adsorption device for chemical adsorption to effectively remove hydrogen fluoride impurities in the hexafluorobutadiene raw material. Among them, natural white pebbles are non-toxic and harmless, and no secondary pollution is generated during the adsorption process, meeting the environmental protection requirements. Moreover, natural white pebbles are easy to obtain, do not require modification treatment, and no special equipment is needed during the adsorption process, with simple operation and low cost, being suitable for large-scale application.
[0033] Step S310: Adsorb and rectify the first mixture to obtain hexafluorobutadiene with a preset purity.
[0034] In the embodiment of the present application, through preliminary purification by the white pebble adsorption device 100, a first mixture is obtained, and further adsorption and rectification are sequentially performed on the first mixture to obtain hexafluorobutadiene with a preset purity. Among them, water and carbon dioxide are removed from the first mixture by adsorption, and then other impurities such as dimers, fluorochlorocarbons, oxygen, nitrogen, carbon dioxide, etc. are removed in the rectification step, and finally hexafluorobutadiene with a preset purity is obtained.
[0035] In the embodiment of the present application, the preset purity of hexafluorobutadiene is greater than or equal to 99.999%, meeting the purity requirements of the semiconductor etching process.
[0036] According to an embodiment of the present application, referring to Figure 3 , Figure 3 is a schematic flow chart of the purification method of hexafluorobutadiene provided by another embodiment of the present application. The step S310 of adsorbing and rectifying the first mixture to obtain hexafluorobutadiene with a preset purity includes step S312 and step S313.
[0037] Step S312: Pass the first mixture into the molecular sieve adsorption device 101 to remove water and carbon dioxide in the first mixture, and obtain a second mixture.
[0038] After introducing the hexafluorobutadiene raw material into the white pebble adsorption device 100 for chemical adsorption to remove hydrogen fluoride in the hexafluorobutadiene raw material, a first mixture is obtained. The first mixture includes at least hexafluorobutadiene, calcium fluoride, water, and carbon dioxide. The first mixture is introduced into the molecular sieve adsorption device 101 to remove water and carbon dioxide in the first mixture, and a second mixture is obtained. The second mixture includes at least hexafluorobutadiene, heavy components, and light components, etc.
[0039] According to an embodiment of the present application, the molecular sieve adsorption device 101 is filled with 5A molecular sieve.
[0040] The 5A molecular sieve is used to remove water and carbon dioxide in the first mixture. The 5A molecular sieve is a chemical substance with the molecular formula 3 / 4CaO·1 / 4Na 2 O·Al 2 O 3 ·2SiO 2 ·9 / 2H 2 O, belonging to the calcium type molecular sieve of the A-type crystal structure, having excellent adsorption performance and being able to adsorb any molecule smaller than its pore size. Compared with other molecular sieves, when the hexafluorobutadiene molecule passes through the 5A molecular sieve, the number of isomerization rearrangements of the hexafluorobutadiene molecule is relatively low, resulting in higher purification efficiency and less loss of hexafluorobutadiene.
[0041] According to an embodiment of the present application, in the step of introducing the first mixture into the molecular sieve adsorption device 101 to remove water and carbon dioxide in the first mixture and obtaining a second mixture, the temperature range for molecular sieve adsorption is 10°C to 25°C.
[0042] In the embodiment of the present application, when using the molecular sieve adsorption device 101 to adsorb water and carbon dioxide in the first mixture, the temperature within the above range can preferably remove water and carbon dioxide in the first mixture, with high efficiency and less product loss. If the temperature is too high, it will cause the isomerization rearrangement of the hexafluorobutadiene molecule to form hexafluoro-2-butyne, and even the chemical bond will break. If the temperature is even higher, the hexafluorobutadiene will polymerize to form a polymer. If the temperature is too low, the hexafluorobutadiene will liquefy.
[0043] Step S313: Rectify the second mixture to obtain hexafluorobutadiene with a preset purity.
[0044] In the embodiment of the present application, after removing water and carbon dioxide in the first mixture and obtaining a second mixture, the second mixture is further rectified to obtain hexafluorobutadiene with a preset purity. Rectification can remove other impurities such as calcium fluoride, dimer, fluorocarbon chloride compound, oxygen, nitrogen, carbon dioxide, etc., and finally obtain hexafluorobutadiene with a preset purity. In the embodiment of the present application, the preset purity is greater than or equal to 99.999%, meeting the requirements of the semiconductor etching process.
[0045] According to an embodiment of the present application, with reference to Figure 4 , Figure 4 is a schematic flow chart of a method for purifying hexafluorobutadiene provided by another embodiment of the present application. The step S313 of rectifying the second mixture to obtain hexafluorobutadiene with a preset purity includes steps S3131 and S3132.
[0046] Step S3131: Feed the second mixture into the first rectifying column 102, and the first rectifying column 102 is used to remove the heavy components in the second mixture to obtain a third mixture.
[0047] In the embodiment of the present application, vacuum distillation is carried out at a temperature of 10°C to 30°C and a pressure of 0.1 Mpa to 0.2 Mpa. The first rectifying column 102 is a de-heavy column, which can remove the heavy components with higher boiling points in the second mixture. The heavy components include calcium fluoride, dimers, other fluorocarbon chlorides, etc. The third mixture includes at least hexafluorobutadiene and light components.
[0048] Step S3132: Feed the third mixture into the second rectifying column 103, and the second rectifying column 103 is used to remove the light components in the third mixture to obtain hexafluorobutadiene with a preset purity.
[0049] In the embodiment of the present application, the second rectifying column 103 is a de-light column, which can remove the light components with lower boiling points in the third mixture. The light components include oxygen, nitrogen, carbon dioxide, etc. The light components are recovered through the recovery bottle 106, and the hexafluorobutadiene with a preset purity is collected through the product bottle 105.
[0050] After the above two-step rectification, hexafluorobutadiene with a purity of 99.999% is obtained, meeting the requirements of the semiconductor etching process.
[0051] According to an embodiment of the present application, continue to refer to Figure 3 , before feeding the first mixture into the molecular sieve adsorption device 101, it includes step S311: pre-treat the molecular sieve adsorption device 101.
[0052] Refer to Figure 5 , Figure 5 is a schematic flow chart of a method for purifying hexafluorobutadiene provided by another embodiment of the present application. The step S311 of pre-treating the molecular sieve adsorption device 101 includes steps S3111 and S3112.
[0053] Step S3111: Feed a predetermined amount of the first mixture into the molecular sieve adsorption device 101 until the first mixture completely adsorbs and penetrates the molecular sieve adsorption device 101.
[0054] In the embodiments of the present application, if a large amount of the first mixture containing hexafluorobutadiene is directly introduced into the molecular sieve adsorption device 101, an exothermic reaction other than the isomer rearrangement of hexafluorobutadiene will occur inside the molecular sieve adsorption device 101, and the reaction is intense. If the internal temperature is too high, the chemical bonds of hexafluorobutadiene will break to form polymers, resulting in more impurities. This not only increases the loss of hexafluorobutadiene raw materials but also reduces the purification efficiency.
[0055] Therefore, it is necessary to pre-treat the molecular sieve adsorption device 101. The pre-treatment method is as follows: slowly introduce a predetermined amount of the first mixture into the molecular sieve adsorption device 101. The predetermined amount is the amount that can completely adsorb and penetrate the molecular sieve adsorption device 101. Generally, a small amount of the first mixture can adsorb and penetrate the molecular sieve adsorption device 101. During the process of slowly introducing the predetermined amount of the first mixture, the molecular sieve will gradually heat up. After the first mixture completely adsorbs and penetrates the molecular sieve adsorption device 101, stop introducing the first mixture and let it stand until the molecular sieve adsorption device 101 cools down to room temperature.
[0056] Since the molecular sieve adsorption device 101 has been pre-treated and heated, during the subsequent step S312 of introducing a large amount of the first mixture containing hexafluorobutadiene into the molecular sieve adsorption device 101 to remove water and carbon dioxide to obtain the second mixture, the overall heat generation inside the molecular sieve adsorption device 101 is less, which will not cause a large amount of isomer rearrangement of hexafluorobutadiene, thereby reducing the raw material loss and improving the purification efficiency.
[0057] Step S3112: Regenerate and activate the molecular sieve adsorbent to obtain the pre-treated molecular sieve adsorption device 101.
[0058] For environmental protection and economy, the first mixture that adsorbs and penetrates the molecular sieve adsorption device 101 in step S3111 is recycled. Then, the molecular sieve in the molecular sieve adsorption device 101 is regenerated. The regeneration method is to purge the inside of the molecular sieve adsorption device 101 with an inert gas and / or perform operations such as vacuum replacement. The regenerated molecular sieve adsorption device 101 still has a strong adsorption capacity for water and carbon dioxide.
[0059] In some embodiments, the molecular sieve adsorption device 101 may be pretreated before the step S210 of passing the hexafluorobutadiene raw material into the white pebble adsorption device 100 to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material to obtain a first mixture after preliminary purification. The pretreatment method is as follows: Slowly introduce a predetermined amount of hexafluorobutadiene raw material into the molecular sieve adsorption device 101. The predetermined amount is the amount that can completely adsorb and penetrate the molecular sieve adsorption device 101. Generally, a small amount of hexafluorobutadiene raw material can adsorb and penetrate the molecular sieve adsorption device 101. During the process of slowly introducing the predetermined amount of hexafluorobutadiene raw material, the molecular sieve will gradually heat up. After the hexafluorobutadiene raw material completely adsorbs and penetrates the molecular sieve adsorption device 101, stop introducing the hexafluorobutadiene raw material and let it stand to cool the molecular sieve adsorption device 101 to room temperature. Then, the molecular sieve adsorbent needs to be regenerated and activated to obtain the pretreated molecular sieve adsorption device 101.
[0060] The second aspect of the present application provides a hexafluorobutadiene purification device 10, which is applicable to the above-mentioned hexafluorobutadiene purification method. The hexafluorobutadiene purification device 10 includes: a white pebble adsorption device 100, a molecular sieve adsorption device 101, and a rectification device that are connected in sequence; the white pebble adsorption device 100 is used to adsorb hydrogen fluoride in the hexafluorobutadiene raw material, and the molecular sieve adsorption device 101 and the rectification device respectively perform adsorption and rectification on the first mixture to obtain hexafluorobutadiene with a preset purity.
[0061] In the embodiments of the present application, the hexafluorobutadiene raw material in the raw material tank 104 is passed into an adsorption device filled with natural white pebbles. The natural white pebbles are natural limestone, which is relatively common, inexpensive, and easy to obtain. After preliminary purification by the white pebble adsorption device 100, a first mixture is obtained, and then the first mixture is sequentially subjected to adsorption and rectification to obtain hexafluorobutadiene with a preset purity. Among them, water and carbon dioxide are removed by adsorption of the first mixture, and then other impurities such as dimers, fluorochlorocarbons, oxygen, nitrogen, carbon dioxide, etc. are removed through the rectification process, and finally hexafluorobutadiene with a preset purity is obtained. The present application uses natural white pebbles as the filler of the adsorption device for chemical adsorption, which can effectively remove hydrogen fluoride impurities in the hexafluorobutadiene raw material. Among them, natural white pebbles are non-toxic and harmless, and no secondary pollution is generated during the adsorption process, meeting environmental protection requirements. Moreover, natural white pebbles are easy to obtain, do not require modification treatment, and no special equipment is required during the adsorption process, with simple operation and low cost.
[0062] According to an embodiment of the present application, the rectification device includes a first rectification tower 102 and a second rectification tower 103; the first rectification tower 102 is used to remove heavy components; the second rectification tower 103 is used to remove light components.
[0063] In the embodiments of the present application, the first rectification column 102 is a heavy component removal column, which can remove the heavy components with higher boiling points in the second mixture. The heavy components include calcium fluoride, dimers, other fluorocarbon chlorine compounds, etc. The third mixture at least includes hexafluorobutadiene and light components. The second rectification column 103 is a light component removal column, which can remove the light components with lower boiling points in the third mixture. The light components include oxygen, nitrogen, carbon dioxide, etc. The light components are recovered through the recovery bottle 106, and the hexafluorobutadiene with a preset purity is collected through the product bottle 105. After two-step rectification, hexafluorobutadiene with a purity of 99.999% is obtained, meeting the requirements of the semiconductor etching process.
[0064] In summary, the beneficial effects that the present application can achieve are as follows:
[0065] (1) In the present application, the hexafluorobutadiene raw material is introduced into the white pebble adsorption device 100 to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material, obtaining a first mixture after preliminary purification. The present application uses natural white pebbles as the packing of the adsorption device for chemical adsorption, which can effectively remove hydrogen fluoride impurities in the hexafluorobutadiene raw material. Among them, natural white pebbles are non-toxic and harmless, and no secondary pollution is generated during the adsorption process, meeting the environmental protection requirements. Moreover, natural white pebbles are easy to obtain, do not require modification treatment, and no special equipment is needed during the adsorption process, with simple operation and low cost.
[0066] (2) Before introducing the first mixture into the molecular sieve adsorption device 101, the molecular sieve adsorption device 101 needs to be pretreated. A predetermined amount of hexafluorobutadiene is slowly introduced into the molecular sieve adsorption device 101, and the predetermined amount is the amount that can completely adsorb and penetrate the molecular sieve adsorption device 101. During the process of slowly introducing the predetermined amount of hexafluorobutadiene, the molecular sieve will gradually heat up. After the hexafluorobutadiene completely adsorbs and penetrates the molecular sieve adsorption device 101, the introduction of hexafluorobutadiene is stopped, and the molecular sieve adsorption device 101 is allowed to stand until it cools down to room temperature.
[0067] The molecular sieve adsorbent is regenerated and activated to obtain the pretreated molecular sieve adsorption device 101.
[0068] (3) The first mixture is introduced into the molecular sieve adsorption device 101 to remove water and carbon dioxide in the first mixture, obtaining a second mixture.
[0069] (4) The second mixture is introduced into the first rectification column 102, and the first rectification column 102 is used to remove the heavy components in the second mixture, obtaining a third mixture.
[0070] The third mixture is introduced into the second rectification column 103, and the second rectification column 103 is used to remove the light components in the third mixture, obtaining hexafluorobutadiene with a preset purity.
[0071] After the above steps, hexafluorobutadiene with a purity of 99.999% is obtained, meeting the requirements of the semiconductor etching process.
[0072] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation to the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.
[0073] The features and performance of the present application will be further described in detail below in conjunction with the embodiments.
[0074] Embodiment 1
[0075] 1. Chemical adsorption purification of hydrogen fluoride:
[0076] The hexafluorobutadiene raw material is introduced into the adsorption device 100 filled with 46 kg of white pebbles with a specification of 2 mm to 4 mm. The natural white pebbles fully adsorb the hydrogen fluoride impurities in the hexafluorobutadiene raw material to obtain a first mixture, which at least includes hexafluorobutadiene, calcium fluoride, water and carbon dioxide.
[0077] 2. Molecular sieve pretreatment:
[0078] A small part of the hexafluorobutadiene raw material is slowly introduced into the adsorber filled with 25 kg of 5A molecular sieve with a specification of 1 / 16. After the hexafluorobutadiene raw material completely adsorbs and penetrates the molecular sieve adsorption device 101, the introduction of the raw material is stopped and it is left to stand and cool down to room temperature. A total of 1 kg of raw material is slowly introduced for pretreatment. The hexafluorobutadiene raw material in the molecular sieve adsorption device 101 is recovered, and 0.5 kg of raw material is recovered.
[0079] After purging the molecular sieve adsorption device 101 with inert gas for 1 h, the molecular sieve adsorption device 101 is gradually heated to 350 °C and maintained at a high temperature. Continue to purge with inert gas for 8 h, then repeat the process of evacuating the vacuum 2 times and replacing helium for 1 h. Finally, stop heating and wait for the molecular sieve adsorption device 101 to cool down to room temperature for use.
[0080] 3. Molecular sieve dehydration and carbon dioxide adsorption:
[0081] The first mixture is introduced into the adsorber filled with 5A molecular sieve after pretreatment.
[0082] Adsorb at low temperature at 10 °C to remove the moisture and part of the carbon dioxide in the first mixture to obtain a second mixture, which at least includes hexafluorobutadiene, heavy components and light components, etc.
[0083] 4. Low-temperature rectification:
[0084] Perform low-temperature vacuum rectification on the second mixture after acid and water removal.
[0085] Perform vacuum distillation at a temperature of 10 - 30 °C and a pressure of 0.1 - 0.2 Mpa. In the first-stage rectification, remove the organic heavy components with higher boiling points, such as dimers, other fluorochlorocarbons, etc.; in the second-stage rectification, remove the light components with lower boiling points, such as oxygen, nitrogen, carbon dioxide, etc., to obtain high-purity hexafluorobutadiene with a purity of 99.999%.
[0086] The above is only the implementation mode of this application, and does not limit the patent scope of this application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of this application.
Claims
1. A method for purifying hexafluorobutadiene, characterized in that: include: Passing a hexafluorobutadiene raw material into a white pebble adsorption device to chemically adsorb hydrogen fluoride in the hexafluorobutadiene raw material to obtain a first mixture after preliminary purification; The first mixture is subjected to adsorption and rectification to obtain hexafluorobutadiene with a preset purity.
2. The method for purifying hexafluorobutadiene according to claim 1, characterized in that: The white pebble adsorption device is filled with natural white pebbles, and the natural white pebbles contain calcium carbonate; The step of chemically adsorbing the hydrogen fluoride in the hexafluorobutadiene raw material to obtain a first mixture after preliminary purification includes: reacting the calcium carbonate in the natural white pebbles with the hydrogen fluoride in the hexafluorobutadiene raw material to generate a first mixture, wherein the first mixture includes hexafluorobutadiene, calcium fluoride, water and carbon dioxide.
3. The method for purifying hexafluorobutadiene according to claim 2, characterized in that: The step of adsorbing and distilling the first mixture to obtain hexafluorobutadiene of a preset purity comprises: Passing the first mixture into a molecular sieve adsorption device to remove water and carbon dioxide in the first mixture to obtain a second mixture; The second mixture is distilled to obtain hexafluorobutadiene of the preset purity.
4. The method for purifying hexafluorobutadiene according to claim 3, characterized in that: Before the first mixture is introduced into the molecular sieve adsorption device, the molecular sieve adsorption device is pretreated, and the step of pretreating the molecular sieve adsorption device includes: Passing a predetermined amount of the first mixture into the molecular sieve adsorption device until the first mixture is completely adsorbed and penetrates the molecular sieve adsorption device; The molecular sieve adsorbent is subjected to regeneration and activation treatment to obtain a pretreated molecular sieve adsorption device.
5. The method for purifying hexafluorobutadiene according to claim 3, characterized in that: In the step of passing the first mixture into a molecular sieve adsorption device to remove water and carbon dioxide in the first mixture to obtain a second mixture, the temperature range is 10° C. to 25° C.
6. The method for purifying hexafluorobutadiene according to claim 3, characterized in that: The step of adsorbing and distilling the first mixture to obtain hexafluorobutadiene of a preset purity comprises: Passing the second mixture into a first distillation tower, wherein the first distillation tower is used to remove heavy components in the second mixture to obtain a third mixture; The third mixture is introduced into a second distillation tower, and the second distillation tower is used to remove light components in the third mixture to obtain hexafluorobutadiene with the preset purity.
7. The method for purifying hexafluorobutadiene according to claim 1, characterized in that: The preset purity is greater than or equal to 99.999%.
8. The method for purifying hexafluorobutadiene according to claim 3, characterized in that: The molecular sieve adsorption device is filled with 5A molecular sieve.
9. A hexafluorobutadiene purification device, characterized in that: The method for purifying hexafluorobutadiene applicable to any one of claims 1 to 8, wherein the hexafluorobutadiene purification device comprises: a white pebble adsorption device, a molecular sieve adsorption device and a distillation device connected in sequence; the white pebble adsorption device is used to adsorb hydrogen fluoride in the hexafluorobutadiene raw material, and the molecular sieve adsorption device and the distillation device respectively adsorb and distill the first mixture to obtain hexafluorobutadiene of a preset purity.
10. The hexafluorobutadiene purification device according to claim 9, characterized in that: The distillation device comprises a first distillation tower and a second distillation tower; the first distillation tower is used to remove heavy components; the second distillation tower is used to remove light components.