JP4624920B2 - Method for producing nitrogen trifluoride - Google Patents

Description

The present invention efficiently reacts nitrogen trifluoride (NF ₃ ) by reacting fluorine gas (F ₂ gas) and ammonia gas (NH ₃ gas) in the gas phase in the presence of a diluent gas under non-catalytic conditions. It relates to a manufacturing method.

NF ₃ is used, for example, as a dry etching gas or a cleaning gas in a semiconductor device manufacturing process. In general, the production method is roughly classified into a chemical method and an electrolytic method. Examples of the chemical method include (1) a method of blowing F ₂ gas and NH ₃ gas into molten ammonium acid fluoride (see Japanese Patent Publication No. 55-8926 (Patent Document 1)), and (2) F ₂ gas. A method of directly reacting NH ₃ gas with NH ₃ gas (see JP-A-2-255513 (Patent Document 2), JP-A-5-105411 (Patent Document 3)) is known.

On the other hand, as an electrolytic method, for example, (3) a method of electrolysis using graphite ammonium as an anode, (4) a method of electrolysis using nickel as an anode, etc. are known. . Ruff et al. Reacted F ₂ and NH ₃ in a gas phase and synthesized NF ₃ by a chemical method although the yield was 6% or less (Z. anorg. Allg. Chem. 197, 395 (1931). )), Morrow et al. Also reported that NF ₃ was synthesized in the gas phase in a yield of 24.3% (J. Amer. Chem. Soc. 82.5301 (1960)).

In the conventional direct fluorination reaction in which NF ₃ is synthesized by reacting F ₂ gas with NH ₃ , there is a risk of explosion or corrosion because of the extremely reactive F ₂ gas. And the temperature in the reactor rises, and N ₂ , HF, N ₂ F ₂ , N ₂ O, NH ₄ F (ammonium fluoride) and NH ₄ HF are decomposed due to side reactions and decomposition or side reactions of the generated NF _{3. 2} (acidic ammonium fluoride) and the like are produced, resulting in a decrease in yield, and a problem in that the reactor and piping are blocked by the solid content of NH ₄ F and NH ₄ HF ₂ .

Among these problems, the reactor and piping clogging, etc., are described in JP-A-2-255511 (Patent Document 4) and JP-A-2-255512 (Patent Document 5). Therefore, it can be improved by using a reactor having an ammonia gas blowing tube above it and a fluorine gas blowing tube on the side, and installing the reactor in a heat medium tank maintained at 80 to 250 ° C. It is shown. However, the yield is as low as 17% (based on NH ₃ ) by either method. JP-A-2-255513 (Patent Document 2) discloses that the yield can be improved to 59.5% (based on NH ₃ ) by using ₃ to 20 times as much F ₂ gas as NH ₃ gas. As shown, the yield based on F ₂ is poor and not economical.

In Japanese Patent Laid-Open No. 5-105411 (Patent Document 3), the reactor gas and the piping are blocked by mixing and reacting the source gas by flowing the source gas spirally along the inner wall of the reactor inside the reactor. It shows that the yield is improved to 63% (NH ₃ standard). However, since expensive F ₂ gas is used as a raw material, further improvement in yield is a problem.

Japanese Patent Application Laid-Open No. 2001-322806 (Patent Document 6) shows that the reaction is carried out at 80 ° C. or lower in the presence of a diluent gas, and the yield is improved to about 76% (F ₂ basis) There is a problem for clogging of the vessel and improvement of yield.
Japanese Patent Publication No.55-8926 JP-A-2-255513 JP-A-5-105411 JP-A-2-255511 JP-A-2-255512 JP 2001-322806 A Z. anorg. allg. chem. 197, 395 (1931) J. et al. Amer. Chem. Soc. 82.5301 (1960)

The present invention is intended to solve the problems associated with the prior art as described above, in which F ₂ gas and NH ₃ gas are reacted, and NF ₃ is directly industrially safe by a fluorination method. It is an object of the present invention to provide a method capable of continuously producing with high yield.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have made a reaction in which fluorine gas and ammonia gas are reacted in the gas phase in the presence of a diluent gas under non-catalytic conditions to produce NF ₃ . In a state where at least one of fluorine gas, ammonia gas and dilution gas is cooled, the mixed gas A of the fluorine gas and dilution gas and the mixed gas B of the ammonia gas and dilution gas are respectively opened. The part is supplied to the tubular reactor from a gas introduction pipe arranged toward the center of the cross section of the tubular reactor, and the fluorine gas and the ammonia gas are subjected to a temperature of 60 ° C. or less and a gas residence time of 20 seconds or less. It was found that NF ₃ can be continuously produced with good yield by reacting.

In addition, when one hydrogen atom in NH ₃ is substituted with one fluorine atom in the reaction of F ₂ and NH ₃ , a large reaction heat of about −110 Kcal / mol is generated. Therefore, when NF ₃ is produced by a direct fluorination reaction in which F ₂ gas and NH ₃ gas are reacted, a large reaction heat of about −330 Kcal / mol is generated, and the temperature is locally increased. When the temperature in the reactor increases, a side reaction [the following formula (2)] occurs predominantly in addition to the target NF ₃ production reaction [the following formula (1)].

4NH ₃ + 3F ₂ → NF ₃ + 3NH ₄ F (1)
2NH ₃ + 3F ₂ → N ₂ + 6HF (2)
As a result of intensive studies to selectively advance the reaction of the above formula (1), the present inventors have closely related the reaction temperature and the side reaction, controlled the reaction temperature, and introduced the raw material gas. By improving the method, it has been found that NF ₃ can be continuously produced with good yield, and the present invention has been completed.
That is, the present invention is a method for producing NF ₃ shown in the following [1] to [11].

  [1] In a state where at least one of fluorine gas, ammonia gas and dilution gas is cooled, mixed gas A of fluorine gas and dilution gas and mixed gas B of ammonia gas and dilution gas are respectively The gas is supplied from the gas introduction pipe whose opening is disposed toward the center of the cross section of the tubular reactor to the tubular reactor having a cooling structure, and the fluorine gas and the ammonia gas are kept at a temperature of 60 ° C. or less. Reacting in a gas phase in the presence of a diluent gas in the presence of a diluent gas in a non-catalytic condition for a time of 20 seconds or less, a solid product mainly composed of nitrogen trifluoride and mainly ammonium fluoride and / or ammonium acid fluoride A method for producing nitrogen trifluoride, comprising:

  [2] The method for producing nitrogen trifluoride according to [1] above, wherein the gas cooling temperature is 5 ° C. or lower.

  [3] Trifluoride according to the above [1] or [2], wherein the reaction is carried out using two or more of the tubular reactors and switching between the two or more tubular reactors Nitrogen production method.

  [4] The method for producing nitrogen trifluoride according to any one of the above [1] to [3], wherein the tubular reactor is installed so that a length direction thereof is a vertical direction. .

  [5] Any one of [1] to [4] above, wherein the fluorine gas and the ammonia gas are supplied in a molar ratio (fluorine gas: ammonia gas) in the range of 1: 1 to 1: 2. The manufacturing method of nitrogen trifluoride of description.

  [6] The method for producing nitrogen trifluoride according to any one of [1] to [5], wherein the supply concentration of the fluorine gas is 3 mol% or less with respect to the total amount of the supply gas.

  [7] The method for producing nitrogen trifluoride according to any one of [1] to [6], wherein the supply concentration of the ammonia gas is 6 mol% or less with respect to the total amount of the supply gas.

  [8] The method for producing nitrogen trifluoride according to any one of the above [1] to [7], wherein fluorine gas and ammonia gas are reacted at a pressure of 0.05 to 1.0 MPa.

  [9] The dilution gas is at least one gas selected from the group consisting of nitrogen, helium, argon, sulfur hexafluoride, hexafluoroethane, octafluoropropane, and nitrogen trifluoride. The method for producing nitrogen trifluoride according to any one of [1] to [8].

  [10] The method for producing nitrogen trifluoride according to any one of the above [1] to [9], wherein a dilution gas is circulated and used.

  [11] The method for producing nitrogen trifluoride according to any one of [1] to [10], wherein after the reaction, unreacted fluorine gas is treated with an alkaline aqueous solution and / or alumina.

According to the present invention, conventional, in NF ₃ production process of reacting the F ₂ gas and NH ₃ gas, when adopting the direct fluorination reaction of directly reacting F ₂ gas and NH ₃ gas, a large reaction heat generation However, before supplying the raw material gas and / or dilution gas to the tubular reactor in response to problems and problems such as locally high temperature or temperature rise due to turbulent or uneven flow of the supply gas Cool sufficiently, and supply a mixed gas of fluorine gas and diluent gas and a mixed gas of ammonia gas and diluent gas from a gas introduction pipe whose opening is arranged toward the center of the cross section of the tubular reactor. By reacting fluorine gas and ammonia gas under conditions of a temperature of 60 ° C. or less and a gas residence time of 20 seconds or less, a method capable of producing NF ₃ continuously and with high yield economically can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.
First, the reactor and apparatus used for the method for producing nitrogen trifluoride of the present invention will be described. The reactor preferably has a cooling structure, and examples thereof include a jacket-type tubular reactor. Moreover, it is preferable that the reactor is installed so that the length direction becomes a vertical direction so that the solid product adhering to the inner wall can be easily removed. In addition, the reactor contains
In particular, it is preferable that a device for removing the solid product adhering to the inner wall of the reactor is installed. Such devices include vibration generators and scrapers. Either one of the vibration generator and the scraper may be used, but is preferably used in combination.

  Examples of the vibration generator include an air knocker and an air type piston vibrator. One or more, preferably two or more air knockers are provided outside the reactor, and the solid product adhering to the inner wall of the reactor is periodically impacted by a timer or the like to drop off the solid product. It is a device that prevents blockage. The pneumatic piston vibrator is composed of, for example, a muffler, a web cover, an O-ring, a piston, a cylinder, a taper spring, and the like. There are effects such as blocking prevention and sliding promotion. That is, one or more, preferably two or more, air-type piston vibrator devices are provided outside the reactor, and the solid product attached to the inner wall of the reactor is impacted to drop off the solid product. It is a device that prevents the blockage of the.

  The scraper is not particularly limited as long as it has the same shape as the cross section of the reactor and does not hinder the passage of gas, but a ring-shaped thin plate provided with a support rod is preferably used. Further, when the tubular reactor is installed so that its longitudinal direction is the vertical direction, the scraper can freely drive the inside of the reactor in the vertical vertical direction and / or the radial cross section of the reactor. It is preferable that the inside of the reactor can be freely rotated about a vertical axis passing through the center of the reactor.

Moreover, it is preferable that the manufacturing apparatus used for this invention has a means to store the solid product removed from the said reactor, and a means to isolate | separate a solid product and a gas component. Specifically, it is preferable that an apparatus for separating and discharging a solid content (hereinafter referred to as “solid separation / discharge apparatus”) is installed at the lower part of the reactor. The solid separation / discharge device preferably has a cross section larger than that of the reactor. More specifically, a solid storage tank that can be exchanged periodically is preferable, and two tanks are provided in series, and two tanks and tanks that can be separated from each other by a rotary valve are provided and switched. It is preferable to have a structure capable of Moreover, it is preferable that the solid separation and discharge device is provided with a gas discharge line through the filter for leading the target NF ₃ and the dilution gas to the next step. This filter can remove a small amount of solids accompanying the gas. Furthermore, it is more preferable that two gas discharge lines are provided, for example, and the gas flow is switched periodically to operate continuously.

Moreover, it is preferable that the production apparatus used in the present invention has two or more of the above-mentioned reactors, and it is preferable to use these two or more reactors by periodically switching them. Specifically, for example, when two reactors A and B are used, NF ₃ is produced in the reactor A for a certain period of time, and then a raw material gas is supplied to the reactor B to start the reaction. Next, the supply of the raw material gas to the reactor A is stopped, and NF ₃ is produced only in the reactor B. During this time, the solid product is removed from the solid separation and discharge device installed at the bottom of the reactor A, and the solid product remaining in the reactor A, piping, filter, solid separation and discharge device, etc. These devices are preferably removed by heat treatment in the presence of. After producing NF ₃ for a certain period of time in the reactor B, the reactor is switched in the same manner as described above, and NF ₃ is produced again in the reactor A. By repeating this series of operations, NF ₃ can be stably produced in high yield without stopping the production line.

Of the above-described constituent devices and parts, the material of the devices and parts other than the filter is preferably SUS316.
Next, the manufacturing method of the nitrogen trifluoride of this invention is demonstrated. The raw materials F ₂ gas and NH ₃ gas are diluted with a dilution gas to prepare mixed gases A (F ₂ gas and dilution gas) and B (NH ₃ gas and dilution gas), and F ₂ gas and NH ₃ gas are prepared. The mixed gas is supplied to the reactor in a state where at least one of the diluent gas is cooled. At this time, after sufficiently cooling at least one of F ₂ gas, NH ₃ gas, and dilution gas with, for example, a cooler or the like, the mixed gas may be prepared, or after preparing the mixed gas, For example, the mixed gas may be sufficiently cooled by a cooler or the like. The cooling temperature is preferably 5 ° C. or less, and more preferably in the range of −40 to −5 ° C. The F ₂ gas and / or NH ₃ gas is preferably cooled after being diluted with a diluent gas. The F ₂ gas and the NH ₃ gas are preferably high purity.

The mixed gases A and B need to be supplied into the reactor through different gas introduction pipes and contacted and mixed for the first time in the reactor. Mixing the mixed gases A and B at the reactor inlet and supplying them to the reactor is not preferable because the reaction proceeds in the mixing section and solids are generated and the piping is blocked. Further, the mixed gases A and B need to be supplied into the reactor from different gas introduction pipes each having an opening disposed toward the center of the cross section of the reactor. The distance between the openings of the gas introduction pipe is preferably 20 to 1500 mm. When F ₂ gas and NH ₃ gas are supplied to the reactor from the gas introduction pipe arranged in this way, the contact and mixing of the source gas occurs efficiently, and the gas residence time can be shortened, so the reactor is designed to be small. This is economically advantageous.

Since the use of F ₂ gas rich very reactive in the direct fluorination reaction using F ₂ gas, and NH ₃ containing hydrogen is reacted at a high concentration and F ₂ is caused a risk of combustion and explosion, even greater This is not preferable because the temperature rises due to heat of reaction and the yield of the target product, NF ₃ , decreases. Therefore, F ₂ gas and NH ₃ gas is required to react at a low concentration region by dilution. The F ₂ gas is preferably diluted with a dilution gas and supplied at 3 mol% or less of the total amount of the supply gas, and the NH ₃ gas is preferably diluted with a dilution gas and supplied at 6 mol% or less of the total amount of the supply gas. That is, it is preferable that the raw material gases (NH ₃ gas and F ₂ gas) are 9 mol% or less in total and the dilution gas is 91 mol% or more. If the NH ₃ gas concentration exceeds 6 mol% and the fluorine gas exceeds 3 mol%, there is a risk of a rapid increase in temperature such as an increase in reaction heat, combustion, or explosion, which is not preferable. Examples of the dilution gas include inert gases such as nitrogen, helium, argon, sulfur hexafluoride, hexafluoroethane, octafluoropropane, and nitrogen trifluoride. These diluent gases can be used alone or in admixture of two or more. Of these dilution gases, sulfur hexafluoride, hexafluoroethane, and octafluoropropane are preferred in consideration of the specific heat of the dilution gas, separation / purification in the distillation step, and the like. Furthermore, a high purity gas is preferable, and 99.999% or more of sulfur hexafluoride is particularly preferable.

Further, _{F 2} gas and NH ₃ gas molar ratio _{(F 2} gas: NH ₃ gas) 1: 1 to 1: are preferably fed to the reactor at 2 range. Supplying an excessive amount of F ₂ gas is not preferable because there is a risk of a sudden rise in temperature such as an increase in reaction heat, combustion, or explosion. In addition, it is not preferable to supply NH ₃ gas in excess of twice the mole of F ₂ gas because the yield of NF ₃ with respect to NH ₃ decreases.

In this way, the diluted F ₂ gas and NH ₃ gas are supplied to the reactor, mixed and contacted in the reactor, and reacted in the gas phase under non-catalytic conditions. The reaction temperature is 60 ° C or lower, preferably -20 to 60 ° C, more preferably -20 to 50 ° C. As a method for controlling the reaction temperature, for example, a method of controlling the temperature in the reactor by a heat medium circulation external cooling system using a jacket type reactor, or cooling before introducing raw materials and / or dilution gas into the reactor in advance. Thus, a method of supplying them is preferable. The reaction pressure is preferably in the range of 0.05 to 1.0 MPa. If it exceeds 1.0 MPa, it is not economically preferable because it is necessary to increase the pressure resistance of the apparatus.

The gas residence time in the reactor is 20 seconds or less, preferably 10 seconds or less. If the gas residence time is too long, a large reactor is required, which is not economically preferable. Moreover, it is preferable that the gas inside the reactor flows vertically downward.

The above reaction produces a gas product mainly composed of nitrogen trifluoride. Further, as the above reaction proceeds, a solid product mainly composed of ammonium fluoride and / or ammonium acid fluoride is generated and adheres to the inner wall of the reactor. Since the adhered solid product causes, for example, a decrease in yield and selectivity of the target NF ₃ due to a temperature increase due to a decrease in cooling efficiency, a disturbance in gas flow, an increase in linear velocity, etc. Need to be removed. For this reason, the solid product is removed from the inner wall of the reactor using the vibration generator attached to the reactor, or scraped off using the scraper attached to the inside of the reactor. . It is preferable to use this combination of scraping and scraping.

  The removed solid product is collected in the solid separation and discharge device installed at the lower part of the reactor. In order to facilitate this recovery, as described above, the reactor is preferably installed so that its length direction is vertical.

By further separating and purifying the solid product recovered in the solid separation / discharge device, the obtained ammonium fluoride and ammonium acid fluoride can be used for other purposes.
On the other hand, the gas product contains a small amount of unreacted F ₂ gas and the like in addition to the target NF ₃ and the dilution gas. For this reason, it is preferable to remove unreacted F ₂ gas from the gas product that has passed through the filter provided at the top of the solid separation / discharge device. As a method of removing unreacted F ₂ gas, for example, a dry removal method of removing by reacting with alumina (aluminum oxide) or a wet removal method of removing by contacting with an alkaline aqueous solution is preferably applied. Depending on the case, both methods may be used in combination. As the alkaline aqueous solution, a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution are preferable.

Since water is contained in the mixed gas of NF ₃ and diluent gas from which unreacted F ₂ gas has been removed, it is preferable to dehydrate using a molecular sieve or the like. The molecular sieve is preferably 3A, 4A, or 5A. These molecular sieves may be used alone or in combination of two or more.

The dehydrated gas is separated into NF ₃ and a diluent gas in a distillation / separation process, and NF ₃ is recovered to become a product, and the diluent gas can be reused as a raw material or a diluent gas for a reaction system.
Among the above production methods, at least two nitrogen trifluoride production apparatuses equipped with a means for cooling the raw material gas, a tubular reactor, an apparatus for removing solid products, and a solid separation and discharge apparatus are used, and at least one of them The nitrogen trifluoride generation reaction is performed at the same time, and on the other hand, the reaction is stopped and the solid product adhering to the reactor is removed. Preferably, at least a part of the solid product is heat-treated in the presence of an inert gas. It is desirable to remove them.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by this Example.

The apparatus shown in FIG. 1 was used. As shown in FIG. 1, an SUS316L tubular reactor (with a jacket 4 and a refrigerant circulation cooling type) 1 having an inner diameter of 54.9 mm and a length of 400 mm has an opening disposed toward the center of the cross section of the reactor. It is equipped with an automatic vertical drive type scraper 2 in which a shaft (rod) and a handle are mounted on a ring-shaped thin plate having an outer diameter of 53.9 mm and an inner diameter of 53.1 mm. In addition, an air knocker 3 (manufactured by Seishin Co., Ltd., air knocker SK / 30 type) is provided outside. In addition, a solid storage tank 5 made of SUS316L having an inner diameter of 109.8 mm and a length of 350 mm is attached to the lower part of the tubular reactor 1, and a gas discharge line 7 is connected to the upper part of the solid storage tank 5 through a filter 6. It is connected. The two source gas supply lines are provided with a cooler 10.

The mixed gas of F ₂ gas 7.6 NL / hr and octafluoropropane 180 NL / hr, and the mixed gas of NH ₃ gas 10.11 NL / hr and octafluoropropane 182.30 NL / hr are cooled by the cooler 10, respectively. The reactor was cooled at a temperature of −20 ° C., supplied to the tubular reactor 1 from different source gas supply lines, and F ₂ gas and NH ₃ gas were mixed in the reactor 1 and reacted with a gas residence time of 9 seconds. . During the reaction, the scraper 2 was reciprocated up and down two times within the reactor 1 every 30 minutes by a timer. Further, the air knocker 3 was operated with a timer at a knocker hitting interval of 30 minutes. Further, the reaction was carried out while cooling the reactor 1 with a refrigerant. Five hours after the start of the reaction, the peak temperature in the reactor 1 was 17.8 ° C.

The gas recovered from the gas discharge line 7 was treated with an aqueous potassium iodide solution to remove unreacted fluorine gas and generated hydrogen fluoride, and then gas components were analyzed by gas chromatography. The results are shown below.
NF ₃ yield: 98.6% (F ₂ basis)

As is clear from this result, by using the cooled source gas and dilution gas, supplying the source gas so as to be in a low concentration and a specific mixed state, and controlling the temperature in the reactor, the gas residence time is Under conditions of 10 seconds or less, NF ₃ could be continuously obtained in a high yield (98% or more).

Furthermore, when the reaction in the reactor 1 was continued, the peak temperature in the reactor 1 after 24 hours from the start of the reaction was 17.6 ° C. The gas recovered from the gas discharge line was analyzed in the same manner as described above. The results are shown below.
NF ₃ yield: 98.2% (F ₂ basis)

When the reaction in the reactor 1 was further continued, the peak temperature in the reactor 1 after 48 hours from the start of the reaction was 17.9 ° C. The gas recovered from the gas discharge line was analyzed in the same manner as described above. The results are shown below.
NF ₃ yield: 97.9% (F ₂ basis)

The method for producing nitrogen trifluoride according to the present invention uses a direct fluorination reaction in which F ₂ gas and NH ₃ are reacted in the gas phase in the presence of a diluent gas in a non-catalytic condition. By using this, it is possible to overcome conventional problems and problems, and to produce NF ₃ industrially safely, continuously and economically with a high yield.

FIG. 1 is a schematic view showing an example of a production apparatus used in the method for producing nitrogen trifluoride according to the present invention.

Explanation of symbols

1 Tubular reactor 2 Scraper 3 Air knocker 4 Jacket (refrigerant or steam circulation type)
5 Solid storage tank 6 Filter 7 Gas exhaust line 8 Exhaust gas (mainly NF ₃ and dilution gas)
9 Refrigerant 10 Cooler 11 Thermocouple insertion tube

Claims (8)

In a state where at least one of fluorine gas, ammonia gas and dilution gas is cooled to a cooling temperature of 5 ° C. or lower , mixed gas A of the fluorine gas and dilution gas, and mixing of the ammonia gas and dilution gas Gas B is supplied to a tubular reactor having a cooling structure from a gas introduction pipe whose opening is disposed toward the center of the cross section of the tubular reactor,
The fluorine gas and the ammonia gas are reacted at a temperature of 60 ° C. or less, a gas residence time of 20 seconds or less, in the presence of a diluent gas, in the gas phase, under non-catalytic conditions,
A method for producing nitrogen trifluoride that produces a gas product mainly composed of nitrogen trifluoride and a solid product mainly composed of ammonium fluoride and / or ammonium acid fluoride ,
The supply concentration of the fluorine gas is 3 mol% or less with respect to the total amount of the supply gas, and the supply concentration of ammonia gas is 6 mol% or less with respect to the total amount of the supply gas . Production method. The method for producing nitrogen trifluoride according to claim 1 , wherein two or more tubular reactors are used, and the reaction is performed while switching the two or more tubular reactors. The method for producing nitrogen trifluoride according to claim 1 or 2, wherein the tubular reactor is installed such that the length direction thereof is a vertical direction. The nitrogen trifluoride according to any one of claims 1 to 3 , wherein the fluorine gas and the ammonia gas are supplied in a molar ratio (fluorine gas: ammonia gas) in the range of 1: 1 to 1: 2. Manufacturing method. The method for producing nitrogen trifluoride according to any one of claims 1 to 4 , wherein fluorine gas and ammonia gas are reacted at a pressure of 0.05 to 1.0 MPa. The dilution gas is at least one gas selected from the group consisting of nitrogen, helium, argon, sulfur hexafluoride, hexafluoroethane, octafluoropropane, and nitrogen trifluoride. 6. The method for producing nitrogen trifluoride according to any one of 5 above. The method for producing nitrogen trifluoride according to any one of claims 1 to 6 , wherein a dilution gas is circulated and used. The method for producing nitrogen trifluoride according to any one of claims 1 to 7 , wherein after the reaction, unreacted fluorine gas is treated with an alkaline aqueous solution and / or alumina.

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