A method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor

Abstract

The present application relates to the technical field of high-purity tungsten hexafluoride preparation, and particularly relates to a method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, comprising the following steps: using a special segmented fluorination reactor with in-situ pre-activation sub-zones, sequentially completing the sealed replacement of tungsten powder, in-situ HF low-temperature pre-activation, segmented fluorination with sub-zone gradient temperature control, in-situ tail-end adsorption impurity removal, and fractional condensation and rectification purification in the same equipment; the segmented fluorination reactor comprises a vertical cylinder, a sealed feeding device, an in-situ pre-activation zone separated by porous flow guide plates, a main fluorination zone and a deep fluorine supplement zone, a jacketed heat exchange device, and an integrated adsorption impurity removal bin; three zones are independently provided with air inlets and independently controlled in temperature. The present application cancels external high-temperature calcination equipment, suppresses the generation of oxygen-containing impurities and low-valence fluorides from the source, supports closed-loop circulation of all components of tail gas, and the F2 utilization rate is greater than or equal to 92%; the product purity can reach 6N-7N grade, the WOF4 can be as low as 2.9 ppb, the yield is greater than or equal to 92%, and the present application is suitable for industrialized production of high-purity tungsten hexafluoride.

Description

Technical Field

[0001] This invention relates to the field of high-purity tungsten hexafluoride preparation technology, specifically to a method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor. Background Technology

[0002] Tungsten hexafluoride (WF6) is a colorless, irritating gas at room temperature and pressure, with a triple point of 2.0℃, a melting point of 2.3℃, a boiling point of 17.2℃, and a saturated vapor pressure of 118 kPa at 25℃. It is easily liquefied, and its liquid state facilitates transport in precision steel cylinders. Tungsten hexafluoride is an indispensable core electronic specialty gas in integrated circuit manufacturing. It is the only industrially available precursor raw material for the preparation of tungsten thin films by chemical vapor deposition (CVD). Globally, over 75% of high-purity WF6 consumption is concentrated in the semiconductor industry, covering the production of all types of chips from mature processes to 3nm / 2nm advanced logic, DRAM, and 3D NAND. It is primarily used for filling chip contact holes / vias and preparing tungsten interconnect films. With the iteration of AI computing chips, high-bandwidth memory HBM, and 3D NAND layers, the demand for high-purity 6N / 7N grade WF6 continues to rise, making it one of the key materials in semiconductor metallization processes.

[0003] According to the electronic grade purity classification (SEMI standard), tungsten hexafluoride is divided into: 5N grade (99.999%), impurities <10ppm, used in mature process (≥28nm) logic, power devices, and low-end memory; 6N grade (99.9999%), total metal impurities <10ppb, used in 7-28nm logic, conventional DRAM, and 3D NAND with up to 100 layers, which is the current mainstream semiconductor specification; 7N grade (99.99999%), metal impurities <10ppt, moisture <50ppt, HF <50ppt, used in 3nm / 2nm advanced process, HBM, and 200+ layer ultra-high stacked 3D NAND, which is a necessity for high-end chips.

[0004] Currently, this product is mainly produced by Kanto Denka and Chuo Glass of Japan (accounting for approximately 25% of global capacity), SK and Foosung of South Korea, and Chinese manufacturers. In 2026, Japanese companies will gradually cease production due to constraints on high-purity tungsten powder raw materials, leading to a contraction in the global supply of high-end WF6 and a significant increase in the price of 6N / 7N products (7N long-term contract price of 3.3-3.6 million yuan / ton).

[0005] Current industrial-scale production commonly employs a direct fluorination process involving tungsten powder and fluorine gas. Tungsten powder has WO2 and WO3 oxide layers on its surface, and the industry standard pretreatment method is high-temperature vacuum roasting at 350-550℃ to remove the oxide scale. This method has the following significant drawbacks: high-temperature roasting consumes a lot of energy; tungsten powder is prone to sintering and agglomeration; secondary oxidation occurs upon contact with air; and subsequent fluorination easily generates oxygen-containing impurities such as WOF4. Conventional fluorination temperatures are 280-420℃, the reaction is strongly exothermic, prone to localized temperature runaway, and produces low-valent fluoride impurities such as WF5 as byproducts. Existing technologies can only rely on multi-stage distillation and downstream molecular sieve adsorption for impurity removal, resulting in large equipment investment, high refining costs, and stable 5N-level products, making it difficult to mass-produce 6N / 7N high-purity products. Furthermore, industrial exhaust gases are generally treated with alkaline neutralization, resulting in significant fluorine feedstock loss and the generation of large amounts of hazardous fluorine-containing waste, leading to high environmental costs.

[0006] Existing tungsten hexafluoride fluorination reactors are mostly single-chamber fixed-bed or ordinary fluidized-bed reactors with unified gas inlet and temperature control throughout the chamber, making it impossible to complete in-situ HF pre-activation of tungsten powder within a single unit. Traditional processes require a separate high-temperature vacuum calcination furnace to remove oxide scale from the tungsten powder, resulting in high equipment investment and the risk of secondary oxidation due to air and moisture introduction during material transfer. Ordinary reactors introduce fluorine gas at a single point, leading to concentrated exothermic reactions that can cause localized overheating and the production of oxygen-containing impurities and low-valent fluorides as byproducts. Conventional equipment lacks an integrated in-situ adsorption chamber at the tail end, requiring an external independent adsorption device for the crude product. This pipeline is prone to gas leakage, introducing impurities and making it difficult to stably prepare high-purity 6N / 7N WF6. Conventional feed inlets lack a sealed gas-tight structure, allowing fluorine gas to backflow into the feed chamber, causing blockages and safety hazards.

[0007] Among existing patent documents, CN108946816A discloses a method for preparing tungsten hexafluoride and its reactor, the reactor being divided into upper and lower reaction zones, reacting with high-purity fluorine gas under the action of solid explosives; CN116854138B discloses a tungsten hexafluoride preparation apparatus, system, and method; CN119569123A discloses an apparatus and method for improving the efficiency of tungsten hexafluoride synthesis in a fluidized bed reactor. However, none of the above-mentioned prior art discloses an integrated production scheme that completes in-situ low-temperature HF pre-activation, segmented fluorination, in-situ impurity removal, and closed-loop circulation of all components within the same reactor.

[0008] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, which aims to solve the technical problems in the existing tungsten hexafluoride preparation process, such as the need for independent high-temperature calcination equipment for tungsten powder pretreatment, the high temperature of the fluorination reaction which easily generates by-products, the complex purification process of crude product, and the generation of a large amount of fluorine-containing hazardous waste in the tail gas treatment.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, comprising the following steps: S1. A segmented fluorination reactor is provided, comprising a vertical cylindrical body, a sealed feeding device disposed at the top of the vertical cylindrical body, at least two layers of porous guide plates disposed inside the vertical cylindrical body dividing the vertical cylindrical body from top to bottom into an in-situ pre-activation zone, a main fluorination zone, and a deep fluorination replenishment zone, a jacketed heat exchange device disposed on the outer periphery of the vertical cylindrical body, and an adsorption and impurity removal chamber disposed at the lower end of the vertical cylindrical body and integrally connected to the vertical cylindrical body; the side wall of the in-situ pre-activation zone is provided with an HF mixed gas inlet and an N2 purge port, the main fluorination zone and the deep fluorination replenishment zone are respectively provided with independent fluorine gas inlets, and each inlet branch is respectively equipped with an independent mass flow meter and a pressure regulating valve; the adsorption and impurity removal chamber is filled with adsorption packing material, and a refrigerant jacket is disposed on the outer periphery of the chamber; S2. Industrial tungsten powder is continuously and quantitatively added to the segmented fluorination reactor through the closed feeding device, so that the tungsten powder passes through the in-situ pre-activation zone, the main fluorination zone and the deep fluorination replenishment zone in sequence. S3. In the in-situ pre-activation zone, an anhydrous HF mixture diluted with N2 is introduced into the tungsten powder at a temperature of 25-70°C for in-situ pre-activation to etch the oxide layer on the surface of the tungsten powder. The activation endpoint is determined by online tail gas monitoring. After activation, the residual HF in the reactor is purged with N2. S4. The activated tungsten powder falls to the main fluorination zone by its own weight. A mixture of F2 and N2 is introduced into the main fluorination zone at a temperature of 150-175℃ to carry out the main fluorination reaction and generate tungsten hexafluoride. S5. Unreacted tungsten powder continues to fall into the deep fluorine replenishment zone. High-purity F2 is introduced into the deep fluorine replenishment zone at a temperature of 160-180℃ to carry out the deep fluorine replenishment reaction, so that the tungsten powder is fully fluorinated. S6. The gaseous tungsten hexafluoride generated by the main fluorination reaction and the deep fluorination reaction enters the adsorption and impurity removal chamber downwards. At a temperature of -10 to 10°C, WOF4, HF and low-valent fluoride impurities are selectively adsorbed and removed by the adsorption packing to obtain crude tungsten hexafluoride. S7. The crude tungsten hexafluoride is purified by staged condensation and distillation to obtain high-purity tungsten hexafluoride product.

[0011] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein in step S3, the volume fraction of HF in the HF mixture is 0.3%-8%, and the pressure of the in-situ pre-activation is 0.02-0.05 MPa.

[0012] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein in step S3, the criterion for determining the activation endpoint is: the concentration of WOF4 in the exhaust gas monitored online is <0.5ppm.

[0013] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein in step S4, the volume ratio of F2 to N2 in the F2 and N2 mixture is 1:1.2-1:2.0.

[0014] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein in step S6, the adsorption packing is a modified cesium fluoride-lithium fluoride composite molecular sieve.

[0015] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein in step S7, the staged condensation includes: a first stage of condensing and collecting tungsten hexafluoride liquid at -35℃ to 0℃ and separating non-condensable gases; and a second stage of removing low-boiling-point impurities at -100℃ to -35℃.

[0016] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein the closed feeding device is a spiral closed feeder, equipped with upper and lower N2 gas sealing chambers.

[0017] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, wherein the porous guide plate is made of Monel alloy; and the vertical cylinder is made of Monel alloy.

[0018] The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor further includes a tail gas stage separation and closed-loop circulation step: the reaction tail gas is sequentially subjected to -120℃ cryogenic condensation to recover trace amounts of WF6, -80℃ separation to recover HF, the remaining F2 is returned to the fluorination process after pressurized purification, and N2 is returned to the pre-activation purging process.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1) Eliminate external high-temperature roasting equipment and simplify the process: This invention completes the low-temperature pre-activation of HF to remove the oxide layer of tungsten powder in situ inside the reactor, eliminating the need for a separate high-temperature vacuum roasting furnace and its supporting equipment. The entire process of tungsten powder from feeding to fluorination is completed in a closed reactor, with no material transfer links. This fundamentally avoids the problem of secondary oxidation of tungsten powder after activation when it comes into contact with air, significantly reducing equipment investment and the floor space required for the production line.

[0020] 2) Low-temperature fluorination suppresses impurity formation at the source: This invention uses low-temperature fluorination at 150-180℃, which is much lower than the traditional process of 280-420℃. The low temperature effectively suppresses the formation of oxygen-containing impurities in WOF4 and low-valent fluoride byproducts such as WF5, thus improving product purity from the source of the reaction. At the same time, the circulating heat transfer oil in the reactor jacket removes the heat released by the reaction, making full use of the self-heating of the reaction to maintain the temperature, eliminating the need for external auxiliary heating and significantly reducing energy consumption.

[0021] 3) Simplified purification process through in-situ adsorption and impurity removal at the reactor tail: This invention integrates an adsorption and impurity removal chamber at the bottom of the reactor, where the main impurities are adsorbed and removed before the gaseous crude WF6 exits the reactor; the modified CsF-LiF composite molecular sieve has excellent selective adsorption capacity for WOF4, HF and low-valent fluorides, and the impurities in the crude product are reduced to the ppb level after adsorption. Only a single-stage shallow cold distillation is needed to achieve high purity, eliminating the need for independent multi-stage adsorption devices and complex pipeline connections in traditional processes, and reducing the risk of impurities being introduced through pipeline leakage; 4) Closed-loop recycling of all components of exhaust gas, green and environmentally friendly: This invention performs staged cold trap separation of exhaust gas, recovers WF6, HF, F2 and N2 respectively, and returns them all to the corresponding processes for reuse; the whole process has no alkaline washing, no fluoride-containing wastewater or hazardous waste discharge, and the total utilization rate of F2 has increased from the traditional 78% to more than 92%, which greatly reduces the cost of raw materials and environmental treatment.

[0022] 5) Excellent product quality: The tungsten hexafluoride product prepared by the method of this invention can reach the purity of 6N-7N, with WOF4 as low as 2.9 ppb, total oxygen impurities <5 ppb, and product yield ≥92%, meeting the stringent requirements of advanced semiconductor processes for ultra-high purity tungsten hexafluoride. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to the present invention.

[0024] Figure 2 This is a schematic diagram of the structure of a segmented fluorination reactor provided by the present invention. Detailed Implementation

[0025] This invention provides a method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0026] Please see Figure 1 , Figure 1A flowchart of a method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, provided by the present invention, is shown in the figure, which includes the following steps: S1. A segmented fluorination reactor is provided, comprising a vertical cylindrical body, a sealed feeding device disposed at the top of the vertical cylindrical body, at least two layers of porous guide plates disposed inside the vertical cylindrical body dividing the vertical cylindrical body from top to bottom into an in-situ pre-activation zone, a main fluorination zone, and a deep fluorination replenishment zone, a jacketed heat exchange device disposed on the outer periphery of the vertical cylindrical body, and an adsorption and impurity removal chamber disposed at the lower end of the vertical cylindrical body and integrally connected to the vertical cylindrical body; the side wall of the in-situ pre-activation zone is provided with an HF mixed gas inlet and an N2 purge port, the main fluorination zone and the deep fluorination replenishment zone are respectively provided with independent fluorine gas inlets, and each inlet branch is respectively equipped with an independent mass flow meter and a pressure regulating valve; the adsorption and impurity removal chamber is filled with adsorption packing material, and a refrigerant jacket is disposed on the outer periphery of the chamber; S2. Industrial tungsten powder is continuously and quantitatively added to the segmented fluorination reactor through the closed feeding device, so that the tungsten powder passes through the in-situ pre-activation zone, the main fluorination zone and the deep fluorination replenishment zone in sequence. S3. In the in-situ pre-activation zone, an anhydrous HF mixture diluted with N2 is introduced into the tungsten powder at a temperature of 25-70°C for in-situ pre-activation to etch the oxide layer on the surface of the tungsten powder. The activation endpoint is determined by online tail gas monitoring. After activation, the residual HF in the reactor is purged with N2. S4. The activated tungsten powder falls to the main fluorination zone by its own weight. A mixture of F2 and N2 is introduced into the main fluorination zone at a temperature of 150-175℃ to carry out the main fluorination reaction and generate tungsten hexafluoride. S5. Unreacted tungsten powder continues to fall into the deep fluorine replenishment zone. High-purity F2 is introduced into the deep fluorine replenishment zone at a temperature of 160-180℃ to carry out the deep fluorine replenishment reaction, so that the tungsten powder is fully fluorinated. S6. The gaseous tungsten hexafluoride generated by the main fluorination reaction and the deep fluorination reaction enters the adsorption and impurity removal chamber downwards. At a temperature of -10 to 10°C, WOF4, HF and low-valent fluoride impurities are selectively adsorbed and removed by the adsorption packing to obtain crude tungsten hexafluoride. S7. The crude tungsten hexafluoride is purified by staged condensation and distillation to obtain high-purity tungsten hexafluoride product.

[0027] like Figure 2 As shown, the segmented fluorination reactor provided by the present invention includes a vertical cylindrical body, a sealed feeding device 20 disposed at the top of the vertical cylindrical body, at least two layers of porous guide plates 30 disposed inside the vertical cylindrical body to divide the vertical cylindrical body from top to bottom into an in-situ pre-activation zone 11, a main fluorination zone 12 and a deep fluorination replenishment zone 13, a jacketed heat exchange device 40 disposed on the outer periphery of the vertical cylindrical body, and an adsorption and impurity removal chamber 50 disposed at the lower end of the vertical cylindrical body and integrally connected to the vertical cylindrical body, wherein the sealed feeding device...

[0028] The in-situ pre-activation zone 11 has a first air inlet 111 on its side wall. The first air inlet can be used to introduce anhydrous HF mixed gas diluted with N2 or N2 alone. For example, it can be used to introduce anhydrous HF mixed gas diluted with N2 into the zone for in-situ etching and activation of the oxide layer on the surface of tungsten powder, and to introduce N2 to purge residual HF after activation. The other end of the side wall of the in-situ pre-activation zone 11 has a corresponding first exhaust port 112 for discharging residual HF, N2 and WOF4 and other impurity gases. The outer periphery of the cylinder of the in-situ pre-activation zone 11 is independently provided with a first jacketed heat exchange device 41. The lower side of the first jacketed heat exchange device 41 has a first heat transfer oil inlet 411, and the upper side of the other side of the first jacketed heat exchange device 41 has a first heat transfer oil outlet 412. The heat transfer oil enters from the first heat transfer oil inlet 411 and flows out from the first heat transfer oil outlet 412, thereby heating the corresponding in-situ pre-activation zone 11.

[0029] The main fluorination zone 12 and the deep fluorination replenishment zone 13 are each equipped with an independent fluorine gas inlet, such as Figure 2 As shown, a second air inlet 121 is provided at the lower end of the side wall of the main fluorination zone 12, and a second air outlet 122 is provided at the upper end of the other side wall of the main fluorination zone 12. A second jacketed heat exchange device 42 is independently provided on the outer periphery of the main fluorination zone 12. A second heat transfer oil inlet 421 is provided at the lower end of the side of the second jacketed heat exchange device 42, and a second heat transfer oil outlet 422 is provided at the upper end of the other side of the second jacketed heat exchange device 42. The heat transfer oil enters from the second heat transfer oil inlet 421 and flows out from the second heat transfer oil outlet 422, thereby heating the corresponding main fluorination zone 12.

[0030] A third air inlet 131 is provided at the lower end of the side wall of the cylinder in the deep refrigerant replenishment zone 13; a third jacketed heat exchange device 43 is independently provided on the outer periphery of the cylinder in the deep refrigerant replenishment zone 13, a third heat transfer oil inlet 431 is provided at the lower end of the side of the third jacketed heat exchange device 43, and a third heat transfer oil outlet 432 is provided at the upper end of the other side of the third jacketed heat exchange device 43. The heat transfer oil enters from the third heat transfer oil inlet 431 and flows out from the third heat transfer oil outlet 432, thereby heating the corresponding deep refrigerant replenishment zone 13; the main fluorination zone 12 and the deep refrigerant replenishment zone 13 are respectively provided with independent mass flow meters and pressure regulating valves for each feed inlet branch, so as to realize independent air intake, independent temperature control, and independent adjustment of gas composition and flow rate for each reaction zone. Correspondingly, the independent air intake design of the in-situ pre-activation zone 11, the main fluorination zone 12, and the deep fluorination replenishment zone 13 allows the reaction atmosphere of each reaction zone to be independently optimized according to process requirements, avoiding the problem of uneven reaction caused by a single cavity with uniform air intake.

[0031] The adsorption and impurity removal chamber 50 is filled with adsorption packing material for selectively adsorbing and removing WOF4, residual HF, and low-valent fluoride impurities from gaseous crude tungsten hexafluoride. A refrigerant jacket is installed around the outer perimeter of the chamber to control the adsorption section temperature within the preferred adsorption temperature range of -10 to 10°C. Figure 2 As shown, a drain outlet 51 for removing impurities and exhaust gas is provided at its bottom.

[0032] Preferably, the closed feeding device 20 is a spiral closed feeder, equipped with upper and lower N2 gas sealing chambers, to achieve continuous quantitative addition of tungsten powder while preventing fluorine gas in the reactor from backflowing into the feeding chamber, causing blockage and safety hazards; for example Figure 2 As shown, the top of the sealed feeding device 20 is provided with a feed port 21 for adding tungsten powder.

[0033] Preferably, the porous guide plate is made of Monel alloy, and the vertical cylinder is made of Monel alloy; Monel alloy has excellent corrosion resistance to HF and F2, which can ensure the long-term stable operation of the reactor under a highly corrosive atmosphere.

[0034] Preferably, the adsorption packing is a modified cesium fluoride-lithium fluoride composite molecular sieve. This composite molecular sieve has excellent selective adsorption capacity for WOF4, HF and low-valent fluorides. After adsorption saturation, it can be regenerated by low-temperature desorption. The desorbed HF and trace amounts of F2 can be returned to the pre-activation process for reuse.

[0035] In step S2, the tungsten powder raw material is commercially available metallic tungsten powder, preferably with a particle size of 1-80 μm. The tungsten powder is continuously and quantitatively added via a top-mounted spiral closed feeder, and passes sequentially through the three functional zones of the reactor under gravity. The two lower-stage N2 gas-sealing chambers continuously introduce N2 during the feeding process to form a gas seal, effectively preventing corrosive gases from flowing back into the reactor along the feed channel. Before feeding, the reactor needs to undergo a closed-loop pretreatment: the air and water vapor inside the reactor are repeatedly purged and replaced with high-purity N2 (preferably 7N grade) until the system oxygen content is <1 ppm. Strict control of the oxygen content is to avoid introducing oxygen impurities into the product during the subsequent fluorination reaction, and also to ensure the smooth progress of the HF pre-activation process.

[0036] In step S3, WO2 and WO3 oxide layers inevitably form on the surface of tungsten powder during storage and transportation. If these oxide layers are not treated before fluorination, oxygen-containing impurities such as WOF4 will be generated, severely affecting product purity. This invention introduces a mixture of N2-diluted anhydrous HF into the tungsten powder in the in-situ pre-activation zone at the top of the segmented fluorination reactor under ambient to slightly heated conditions (25-70°C, no high-temperature heating required). The HF reacts chemically with the WO3 and WO2 on the surface of the tungsten powder. WO3 + 4HF = WOF4 + 2H2O WO2 + 4HF = WOF4 + 2H2O Through the above reaction, the oxide layer on the surface of the tungsten powder is removed by in-situ etching, and the generated trace amounts of WOF4 are carried out of the reactor with the activation exhaust gas. Since the activation temperature is only 25-70℃, far lower than the 350-550℃ of traditional high-temperature calcination, the tungsten powder will not sinter or agglomerate. Moreover, the activation is completed in a closed reactor, and the activated tungsten powder does not come into contact with the outside air, thus fundamentally avoiding secondary oxidation.

[0037] The volume fraction of HF in the HF mixture is 0.3%-8%, preferably 1%-3%. Too low an HF concentration results in insufficient activation efficiency and excessively long activation time; too high an HF concentration may cause excessive corrosion of the equipment and increase the tail gas recovery load. The activation pressure is a slightly positive pressure of 0.02-0.05 MPa. This slightly positive pressure environment facilitates sufficient contact between the HF gas and the tungsten powder surface, while preventing outside air from seeping into the reactor.

[0038] In this step, the activation endpoint is determined by online exhaust gas monitoring: when the WOF4 concentration in the exhaust gas is <0.5ppm, it indicates that the oxide layer on the surface of the tungsten powder has been basically etched away, and the activation is considered complete. At this point, the HF gas supply is cut off, and the residual HF in the reactor is purged with high-purity N2. The purged residual HF is then recycled into the exhaust gas separation system.

[0039] In step S4, the activated tungsten powder falls into the main fluorination zone in the middle under gravity through a porous guide plate. A mixture of F2 and N2 is introduced into the main fluorination zone, where F2 reacts with the tungsten powder in the main reaction: W + 3F2 = WF6. This reaction is strongly exothermic. This invention fully utilizes the exothermic reaction itself to maintain the reaction temperature, and removes excess reaction heat through circulating heat transfer oil in the reactor jacket. The temperature of the main fluorination zone can be controlled at 150-175℃ without external auxiliary heating throughout the process. This temperature is much lower than the 280-420℃ of the traditional process, and the low temperature effectively suppresses the formation of byproducts such as WOF4 and WF5.

[0040] The volume ratio of F2 to N2 in the F2 / N2 mixture is 1:1.2-1:2.0. The F2 concentration is gradually increased to this range to avoid excessively high initial F2 concentration, which could lead to an overly vigorous reaction and localized overheating. N2 acts as a dilution gas, reducing the partial pressure of F2 to regulate the reaction rate and carrying the generated WF6 gas downwards as a carrier gas. The independent inlet design of the main fluorination zone allows for precise control of the F2 concentration and flow rate based on the tungsten powder falling speed and reaction progress. Three sheathed thermocouples provide independent temperature measurement to ensure uniform temperature distribution and precise control.

[0041] In step S5, after passing through the main fluorination zone, most of the tungsten powder has been converted into WF6, but trace amounts of unreacted elemental tungsten continue to fall with the feed stream to the lower deep fluorination replenishment zone. High-purity F2 (preferably 99.999%) is introduced into the deep fluorination replenishment zone, allowing the trace amounts of unreacted elemental tungsten to undergo deep fluorination in this area: W + 3F2 = WF6. The temperature in the deep fluorination replenishment zone is controlled at 160-180℃, slightly higher than that of the main fluorination zone, to ensure the complete fluorination reaction. By setting up an independent deep fluorination replenishment zone, low-valent fluorides (such as WF5) byproducts generated due to incomplete reaction in the main fluorination zone can be eliminated, further improving product purity and raw material utilization. The deep fluorination replenishment zone is also equipped with an independent mass flow meter and pressure regulating valve to achieve independent and precise gas control.

[0042] In step S6, the gaseous WF6 generated in the main fluorination zone and the deep fluorination replenishment zone, carrying trace amounts of WOF4, residual HF, and low-valent fluoride impurities, flows downwards within the reactor and enters the adsorption and impurity removal chamber, which is integrally welded at the lower end of the cylinder. The adsorption and impurity removal chamber is filled with modified cesium fluoride-lithium fluoride (CsF-LiF) composite molecular sieve packing. This composite molecular sieve exhibits excellent selective adsorption capacity for WOF4, HF, and low-valent fluorides, while its adsorption capacity for the target product WF6 is extremely weak, thus enabling selective removal of impurities. The temperature of the adsorption section is controlled between -10 and 10°C by a refrigerant jacket around the chamber. Within this temperature range, the adsorption capacity and selectivity of the composite molecular sieve are optimal. Too low a temperature may cause WF6 to condense, affecting adsorption efficiency; too high a temperature will reduce adsorption capacity.

[0043] After in-situ adsorption and impurity removal, the impurities in the crude WF6 have been reduced to the ppb level. High purity can be achieved with just a single-stage shallow cold distillation, eliminating the need for the complex multi-stage distillation and downstream molecular sieve adsorption devices required in traditional processes. After the adsorption packing is saturated, it can be regenerated through low-temperature desorption. The desorbed impurities are collected and treated harmlessly, while the regenerated HF and trace amounts of F2 are returned to the pre-activation process for reuse.

[0044] In step S7, the crude WF6, after in-situ adsorption and impurity removal, enters the purification system and undergoes staged condensation and distillation purification in sequence. The staged condensation includes: First-stage condensation: WF6 liquid is collected by condensation at -35℃ to 0℃. The boiling point of WF6 is 17.2℃. At -35℃ to 0℃, WF6 is condensed into liquid, while non-condensable gases (excess F2, N2, etc.) are separated and enter the exhaust gas recirculation system.

[0045] Second-stage condensation: This is carried out at temperatures ranging from -100℃ to -35℃. Low-boiling-point impurities such as CF4 and SiF4 are removed at the top of the column at -72℃, while trace amounts of high-boiling-point heavy metal fluorides are removed at the bottom of the column at 18℃. Low-boiling-point impurities such as CF4 (boiling point -128℃) and SiF4 (boiling point -86℃) exhibit significantly different volatility compared to WF6 under low-temperature conditions and can be effectively separated by distillation.

[0046] The distillation and refining process includes: heating the condensed and purified WF6 before feeding it into a distillation column, where it undergoes two stages of distillation—one for removing light components and the other for removing heavy components—to remove both heavy and light impurities. The top temperature of the distillation column is controlled at 0-15℃, and the bottom temperature is controlled at 25-75℃. By precisely controlling the distillation temperature, complete separation of WF6 from residual impurities is achieved.

[0047] Product collection: The WF6 liquid after distillation is vaporized and sampled for testing. Under normal operating conditions, the product purity can reach 6N (99.9999%). By fine-tuning process parameters such as HF activation concentration and F2 gradient ratio, it can reach 7N (99.99999%), with all impurities <10ppb.

[0048] In some embodiments, as a preferred technical solution of the present invention, the method further includes a tail gas staged separation and a closed-loop circulation step for all components. The main components of the reaction tail gas are unreacted F2, diluted N2, trace amounts of HF, and a small amount of WOF4, wherein the tail gas passes through the following sequentially: -120℃ cryogenic condensation: recovering trace amounts of WF6 entrained in the exhaust gas; -80℃ low-temperature separation: separation and recovery of HF; The remaining F2 is purified under pressure and then returned to the fluorination process for reuse. N2 is returned to the pre-activation purging process for reuse.

[0049] The entire process involves alkaline-free washing, increasing the total F2 utilization rate from 78% in traditional processes to over 92%, and eliminating the discharge of fluoride-containing wastewater and hazardous waste, thus achieving green and environmentally friendly production.

[0050] The present invention will be further explained and illustrated below through specific embodiments: Example 1 (Conventional industrial mass production, stable 6N grade) 1. Reactor preparation and replacement The industrial-grade segmented fluorination reactor features a vertical cylindrical body with a total height of 3.2m and an inner diameter of 0.8m, constructed of Monel alloy. Two layers of porous Monel baffles inside divide the reactor into three zones: an upper in-situ pre-activation zone with an effective volume of 320L, a middle main fluorination zone with a volume of 550L, and a lower deep fluorination replenishment zone with a volume of 280L. A DN80 spiral sealed feeder is installed at the top, along with two-stage N2 gas-sealed chambers. The outer jacket of the reactor is circulated with heat transfer oil, and a combined heating and cooling system is included.

[0051] The air and water vapor inside the reactor were repeatedly purged and replaced with 7N high-purity N2, and the oxygen content of the system was reduced to <1ppm.

[0052] 2. Feeding 50.0 kg of commercial tungsten powder (particle size 1-80 μm) is continuously and quantitatively added to the reactor via a top-mounted spiral closed feeder. Under gravity, the tungsten powder sequentially passes through the in-situ pre-activation zone, the main fluorination zone, and the deep fluorination replenishment zone. During the feeding process, N2 is continuously introduced into the upper and lower N2 gas-sealed chambers to form a gas seal.

[0053] 3. In-situ HF pre-activation A mixture of anhydrous HF diluted with N2 (2.0% HF volume fraction) was introduced into the in-situ pre-activation zone at an activation temperature of 45°C and a system pressure of 0.03 MPa. The HF reacted with WO3 and WO2 on the surface of the tungsten powder. WO3 + 4HF = WOF4 + 2H2O WO2 + 4HF = WOF4 + 2H2O The concentration of WOF4 in the exhaust gas was monitored online. After 2.5 hours of activation, the WOF4 concentration in the exhaust gas was less than 0.5 ppm, indicating that the activation was complete. The HF gas supply was cut off, and the residual HF in the reactor was purged with 7N N2. The purged residual HF was sent to the recovery section.

[0054] Results: This embodiment uses low-temperature activation at 45℃, and the tungsten powder did not sinter or agglomerate. After activation, the oxide layer on the surface of the tungsten powder was effectively etched away, providing high-quality raw materials for subsequent low-temperature fluorination. Compared with traditional high-temperature calcination at 350-550℃, energy consumption is reduced by approximately 85%, and there is no risk of secondary oxidation.

[0055] 4. Segmented fluorination Main fluorination zone: Temperature 160℃, F2:N2 volume ratio = 1:1.5 mixed gas is introduced, tungsten powder and F2 undergo the main reaction: W + 3F2 = WF6, the heat transfer oil in the reactor jacket is circulated to remove the heat released by the reaction, and the temperature is maintained at 160℃ by the self-heating of the reaction, without the need for external auxiliary heating.

[0056] Deep fluorination zone: Temperature 170℃, 99.999% high-purity F2 is introduced to deeply fluorinate trace amounts of unreacted elemental tungsten and eliminate low-valent fluoride byproducts.

[0057] Results: In this embodiment, the main fluorination temperature is 160℃ and the fluorination replenishment temperature is 170℃, which is far lower than the traditional process of 280-420℃. The low temperature effectively suppresses the formation of byproducts such as WOF4 (formation temperature is usually >200℃) and WF5. The reactor has three independent gas inlet zones and independent temperature control. The F2 concentration and temperature in each reaction zone can be independently optimized according to process requirements, resulting in uniform reaction and no localized temperature runaway.

[0058] 5. In-situ adsorption and impurity removal The gaseous WF6 generated in the main fluorination zone and the deep fluorination replenishment zone carries trace impurities downwards into the adsorption and impurity removal chamber at the tail end of the reactor. The adsorption chamber is filled with CsF-LiF composite modified molecular sieves, and the temperature is controlled between -10 and 10°C by a refrigerant jacket outside the chamber. When the gaseous crude WF6 passes through the packing layer, WOF4, residual HF, and low-valent fluoride impurities are selectively adsorbed, while the WF6 passes through smoothly.

[0059] Performance Description: The CsF-LiF composite molecular sieve exhibits an adsorption capacity of over 8 wt% for WOF4 and over 12 wt% for HF. After in-situ adsorption, the WOF4 content in the crude product decreases from several hundred ppb to below 10 ppb, and the HF content decreases to below 5 ppb. After adsorption saturation, the product can be regenerated through low-temperature desorption, with the desorbed HF and trace amounts of F2 returned to the pre-activation process for reuse.

[0060] 6. Staged condensation and distillation refining The coarse WF6 is subjected to staged condensation in sequence: First-stage condensation: The -35℃ to 0℃ cold trap condenses and collects WF6 liquid, while non-condensable gases (excess F2, N2) are separated and recycled to the tail gas.

[0061] Second-stage condensation: -100℃ to -35℃, with the top of the column at -72℃ to remove low-boiling impurities such as CF4 and SiF4, and the bottom of the column at 18℃ to remove trace amounts of high-boiling heavy metal fluorides.

[0062] After condensation and impurity removal, the WF6 is heated and fed into a distillation column, where it undergoes two stages of distillation—one for removing light components and the other for removing heavy components—to remove both heavy and light impurities. The top temperature of the distillation column is 0-15℃, and the bottom temperature is 25-75℃.

[0063] 7. Finished product collection and exhaust gas recirculation After distillation, WF6 liquid is vaporized and sampled for testing. The tail gas is separated by a staged cold trap: trace amounts of WF6 are recovered by cryogenic condensation at -120℃; HF is separated and recovered at -80℃; the remaining F2 is pressurized and purified and returned to the fluorination process; N2 is returned to the pre-activation purging process.

[0064] 8. Product testing results WF6 purity 99.99992% (6N+), WOF4=7ppb, total oxygen impurities 3.8ppb; product yield 93.5%; F2 raw material utilization rate 92.8%.

[0065] Results: This embodiment successfully and stably prepared high-purity tungsten hexafluoride of grade 6N and above, with significantly higher product yield and F2 utilization rate than traditional processes (traditional processes typically yield 85-90% and F2 utilization rate typically ≤78%). The entire process generates no fluoride-containing wastewater, achieving green production.

[0066] Example 2 (Ultra-high purity optimized process, 7N grade) 1. Reactor preparation and replacement Same as Example 1.

[0067] 2. Feeding 50.0 kg of commercial tungsten powder.

[0068] 3. In-situ HF pre-activation The HF volume fraction was 1.2%, the activation temperature was 32℃, the slight positive pressure was 0.03MPa, and the activation time was 3.2h. After the exhaust gas WOF4 met the standard, it was purged with N2.

[0069] Results: This embodiment uses a lower HF concentration (1.2%) and a lower activation temperature (32℃, close to room temperature), further reducing the risk of HF corrosion to the equipment. Meanwhile, extending the activation time (3.2h) ensures effective activation. At the 32℃ activation temperature, the tungsten powder does not sinter at all, resulting in a gentler and more thorough removal of the surface oxide layer.

[0070] 4. Segmented fluorination Main fluorination zone: 155℃, F2:N2=1:1.8; Deep refrigerant replenishment area: 165℃, high-purity F2 refrigerant replenishment.

[0071] Effect description: This embodiment uses a lower fluorination temperature (155℃ in the main fluorination zone and 165℃ in the supplemental fluorination zone) and a higher N2 dilution ratio (F2:N2=1:1.8), which further reduces the reaction intensity, making the fluorination reaction more mild and uniform, and suppressing the formation of oxygen-containing impurities and low-valent fluorides to the greatest extent from the source.

[0072] 5. In-situ adsorption and impurity removal Same as Example 1.

[0073] 6. Staged condensation and distillation refining After in-situ adsorption, the staged condensation parameters are the same as in Example 1. A high-purity side stream is added for distillation to further optimize impurity removal.

[0074] 7. Finished product collection and exhaust gas recirculation Same as Example 1.

[0075] 8. Product testing results WF6 purity 99.999991% (7N), total oxygen impurities <5ppb, WOF4=2.9ppb; product yield 93.8%; F2 utilization rate 93.2%.

[0076] Results: This embodiment successfully prepared 7N-grade ultra-high purity tungsten hexafluoride by optimizing the HF activation concentration (1.2%), lowering the fluorination temperature (155 / 165℃), increasing the N2 dilution ratio (1:1.8), and adding a high-purity side stream for distillation. WOF4 was reduced to 2.9 ppb, and total oxygen impurities were <5 ppb, meeting the stringent requirements for ultra-high purity WF6 in advanced 3nm / 2nm processes, HBM, 200-layer chips, and 3D NAND manufacturing.

[0077] Example 3 (Low HF dosage condition, low-cost pilot process) 1. Reactor preparation and replacement A pilot-scale small-scale reactor was used: the total height of the cylinder was 1.8m and the inner diameter was 0.4m. The volume of the three zones was scaled down proportionally. The structure, zoned air intake, jacketed heat exchange, and tail integrated adsorption chamber structure were the same as in Example 1.

[0078] 2. Feeding 50.0 kg of commercial tungsten powder.

[0079] 3. In-situ HF pre-activation The HF volume fraction was 0.8%, the activation temperature was 50℃, the micro-positive pressure was 0.04MPa, and the activation time was 4.0h.

[0080] Results Description: This embodiment uses a lower HF concentration (0.8%) to verify the activation effect and process economy under low HF dosage conditions. Although the activation time is extended to 4.0 h, the HF dosage is significantly reduced, lowering raw material costs and tail gas recovery load, while also reducing HF corrosion of equipment. The activation temperature of 50℃ is still far below the traditional high-temperature calcination temperature, and the tungsten powder does not sinter.

[0081] 4. Segmented fluorination Main fluorination zone: 162℃, F2:N2=1:1.3; Deep fluoride replenishment zone: 172℃, high-purity F2.

[0082] 5. In-situ adsorption and impurity removal Same as Example 1.

[0083] 6. Staged condensation and distillation refining Standard single-stage distillation.

[0084] 7. Finished product collection and exhaust gas recirculation Same as Example 1.

[0085] 8. Product testing results WF6 purity 99.99990% (6N), WOF4 = 8.1 ppb; yield 92.7%, F2 utilization 91.9%.

[0086] Results: This embodiment verifies the feasibility of the process under low HF concentration conditions. Although the HF concentration is reduced to 0.8%, satisfactory activation results can still be obtained by appropriately extending the activation time (4.0 h) and slightly increasing the activation temperature (50 °C). The product purity reaches 6N grade (99.99990%), WOF4=8.1 ppb, meeting the requirements of mainstream semiconductor processes. The F2 utilization rate is 91.9%, significantly better than traditional processes.

[0087] Example 4 (Near-room temperature activation, 6N high-order process) 1. Reactor preparation and replacement Same as Example 1.

[0088] 2. Feeding 50.0 kg of commercial tungsten powder.

[0089] 3. In-situ HF pre-activation The HF volume fraction was 2.8%, the activation temperature was 26℃ (near room temperature), the micro-positive pressure was 0.025MPa, and the activation time was 3.8h.

[0090] Results: This embodiment employs near-room temperature (26°C) activation, serving as an important example to verify the minimum activation temperature boundary of the present invention. At 26°C, the reaction rate between HF and the oxide layer on the tungsten powder surface decreases somewhat; however, by increasing the HF concentration (2.8%) and extending the activation time (3.8 h), effective activation can still be achieved near-room temperature. Near-room temperature activation significantly reduces energy consumption, while maintaining the optimal original morphology and reactivity of the tungsten powder.

[0091] 4. Segmented fluorination Main fluorination zone: 152℃, F2:N2=1:2.0; Deep fluoride replenishment zone: 162℃, high-purity F2.

[0092] 5. In-situ adsorption and impurity removal Same as Example 1.

[0093] 6. Staged condensation and distillation refining The distillation side stream was slightly optimized for extraction.

[0094] 7. Finished product collection and exhaust gas recirculation Same as Example 1.

[0095] 8. Product testing results WF6 purity 99.99997% (6N high-order, close to 7N), WOF4=4.2ppb; yield 93.2%, F2 utilization 92.5%.

[0096] Results: This example demonstrates that under the combined conditions of near-room temperature activation (26°C), a high N2 dilution ratio (F2:N2=1:2.0), and low-temperature fluorination (main fluorination zone 152°C), a high-purity product (99.99997%) close to 7N grade can be obtained. WOF4 decreased to 4.2 ppb, indicating that near-room temperature activation combined with high dilution ratio and low-temperature fluorination has a significant effect on suppressing oxygen-containing impurities. This combination of conditions is particularly suitable for production scenarios with extremely high product purity requirements and high energy consumption sensitivity.

[0097] Example 5 (Hundred-kilogram scale-up and industrial verification) 1. Reactor preparation and replacement Same as Example 1.

[0098] 2. Feeding 100.0 kg of commercial tungsten powder (twice the amount fed in Example 1) was used to verify the feasibility of scaling up the process.

[0099] 3. In-situ HF pre-activation The HF volume fraction was 1.8%, the activation temperature was 40℃, the micro-positive pressure was 0.035MPa, and the activation time was 3.0h.

[0100] Results: This embodiment scales up the feed rate from 50kg to 100kg, verifying the stability and repeatability of the process at a larger scale. The activation parameters are taken as the median between Example 1 and Example 2 (HF 1.8%, temperature 40℃, time 3.0h), indicating that the process parameters have a wide operating window, suitable for flexible adjustment in industrial production.

[0101] 4. Segmented fluorination Main fluorination zone: 158℃, F2:N2=1:1.4; Deep refrigerant replenishment zone: 168℃, high-purity F2.

[0102] 5. In-situ adsorption and impurity removal Same as Example 1.

[0103] 6. Staged condensation and distillation refining Double-tower shallow distillation purification.

[0104] 7. Finished product collection and exhaust gas recirculation Same as Example 1.

[0105] 8. Product testing results WF6 purity 99.99991% (6N), WOF4 = 7.5 ppb; overall yield 92.9%, F2 utilization rate 92.1%.

[0106] Results: This embodiment successfully scaled up the feed rate to 100 kg, with product purity remaining stable at 6N level (99.99991%). The yield and F2 utilization rate were essentially the same as at the 50 kg level, demonstrating the excellent scalability and industrial feasibility of the process. The dual-tower shallow distillation further optimized impurity removal, laying the foundation for larger-scale industrial production.

[0107] The above five embodiments comprehensively verify the feasibility and superiority of the technical solution of the present invention under different combinations of process parameters. Regarding purity: all embodiments consistently achieve a purity of 6N or higher, with Embodiment 2 reaching 7N (99.999991%) and Embodiment 4 reaching a high-order 6N (99.99997%, close to 7N). This indicates that the method of the present invention has good process adaptability for the preparation of 6N-7N grade high-purity tungsten hexafluoride. Regarding impurity control: WOF4, the most critical oxygen-containing impurity index in tungsten hexafluoride, was controlled within the range of 2.9-8.1 ppb in all five embodiments, far superior to the tens to hundreds of ppb levels typically achievable by traditional processes. This is attributed to the three core technologies of the present invention: 1) in-situ low-temperature HF pre-activation to remove the oxide layer from the source and avoid secondary oxidation; 2) low-temperature fluorination at 150-180℃ to inhibit WOF4 formation from the reaction source; and 3) efficient removal of residual WOF4 by in-situ adsorption of CsF-LiF composite molecular sieve at the tail end. Regarding yield and utilization: the product yield remained stable at 92.7%-93.8%, and the F2 utilization rate remained stable at 91.9%-93.2%, both significantly better than traditional processes (yield 85-90%, F2 utilization rate ≤78%). The high yield is attributed to the segmented fluorination design that allows for complete reaction of the tungsten powder; the high F2 utilization rate is attributed to the complete recovery of unreacted F2 by the tail gas closed-loop circulation system. Regarding the process window: Examples 1-5 cover a wide range of process parameters, including HF concentration of 0.8%-2.8%, activation temperature of 26-50℃, main fluorination temperature of 152-162℃, and F2:N2 ratio of 1:1.3-1:2.0, all of which yielded products of grade 6N or higher, indicating that the process of this invention has a wide operating window and good industrial adaptability.

[0108] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor, characterized in that, Includes the following steps: S1. A segmented fluorination reactor is provided, comprising a vertical cylindrical body, a sealed feeding device disposed at the top of the vertical cylindrical body, at least two layers of porous guide plates disposed inside the vertical cylindrical body dividing the vertical cylindrical body from top to bottom into an in-situ pre-activation zone, a main fluorination zone, and a deep fluorination replenishment zone, a jacketed heat exchange device disposed on the outer periphery of the vertical cylindrical body, and an adsorption and impurity removal chamber disposed at the lower end of the vertical cylindrical body and integrally connected to the vertical cylindrical body; the side wall of the in-situ pre-activation zone is provided with an HF mixed gas inlet and an N2 purge port, the main fluorination zone and the deep fluorination replenishment zone are respectively provided with independent fluorine gas inlets, and each inlet branch is respectively equipped with an independent mass flow meter and a pressure regulating valve; the adsorption and impurity removal chamber is filled with adsorption packing material, and a refrigerant jacket is disposed on the outer periphery of the chamber; S2. Industrial tungsten powder is continuously and quantitatively added to the segmented fluorination reactor through the closed feeding device, so that the tungsten powder passes through the in-situ pre-activation zone, the main fluorination zone and the deep fluorination replenishment zone in sequence. S3. In the in-situ pre-activation zone, an anhydrous HF mixture diluted with N2 is introduced into the tungsten powder at a temperature of 25-70°C for in-situ pre-activation to etch the oxide layer on the surface of the tungsten powder. The activation endpoint is determined by online tail gas monitoring. After activation, the residual HF in the reactor is purged with N2. S4. The activated tungsten powder falls to the main fluorination zone by its own weight. A mixture of F2 and N2 is introduced into the main fluorination zone at a temperature of 150-175℃ to carry out the main fluorination reaction and generate tungsten hexafluoride. S5. Unreacted tungsten powder continues to fall into the deep fluorine replenishment zone. High-purity F2 is introduced into the deep fluorine replenishment zone at a temperature of 160-180℃ to carry out the deep fluorine replenishment reaction, so that the tungsten powder is fully fluorinated. S6. The gaseous tungsten hexafluoride generated by the main fluorination reaction and the deep fluorination reaction enters the adsorption and impurity removal chamber downwards. At a temperature of -10 to 10°C, WOF4, HF and low-valent fluoride impurities are selectively adsorbed and removed by the adsorption packing to obtain crude tungsten hexafluoride. S7. The crude tungsten hexafluoride is purified by staged condensation and distillation to obtain high-purity tungsten hexafluoride product.

2. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, In step S3, the volume fraction of HF in the HF mixture is 0.3%-8%, and the pressure of the in-situ pre-activation is 0.02-0.05 MPa.

3. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, In step S3, the criterion for determining the activation endpoint is: the concentration of WOF4 in the exhaust gas monitored online is <0.5ppm.

4. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, In step S4, the volume ratio of F2 to N2 in the F2 to N2 mixture is 1:1.2-1:2.

0.

5. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, In step S6, the adsorption packing material is a modified cesium fluoride-lithium fluoride composite molecular sieve.

6. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, In step S7, the staged condensation includes: a first stage of condensing and collecting tungsten hexafluoride liquid at -35℃ to 0℃ and separating non-condensable gases; and a second stage of removing low-boiling-point impurities at -100℃ to -35℃.

7. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, The sealed feeding device is a spiral sealed feeder, equipped with upper and lower N2 air seal chambers.

8. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, The porous guide plate is made of Monel alloy; the vertical cylinder is made of Monel alloy.

9. The method for preparing high-purity tungsten hexafluoride based on a segmented fluorination reactor according to claim 1, characterized in that, The method also includes a tail gas staged separation and full component closed-loop circulation step: the reaction tail gas is sequentially subjected to -120℃ cryogenic condensation to recover trace amounts of WF6, -80℃ separation to recover HF, the remaining F2 is returned to the fluorination process after pressurized purification, and N2 is returned to the pre-activation purging process.

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