KR101462751B1 - Method for the production of nitrogen trifluoride - Google Patents

Abstract

The present invention relates to a method for producing nitrogen trifluoride, comprising the steps of: ₁ ) generating fluorine (F ₂ ) gas by electrolyzing hydrofluoric acid (HF) in a first electrolyzer; 2) reacting the fluorine (F ₂ ) gas with ammonia (NH ₃ ) in a fluorination reactor to obtain nitrogen trifluoride (NF ₃ ) and producing a first acid ammonium fluoride (AAF-1) as a byproduct; 3) A second acidic ammonium fluoride (AAF-2) is prepared by adjusting the molar ratio of hydrofluoric acid (HF), ammonia (NH ₃ ) or the like to the first acid ammonium fluoride (AAF-1) ; 4) electrolyzing the second acid ammonium fluoride (AAF-2) in a second electrolytic cell to produce nitrogen trifluoride (NF ₃ ); And 5) is characterized in that by adding the nitrogen trifluoride (NF _3), obtained in three nitrogen trifluoride obtained in the fluorination reactor (NF ₃₎ and step 4) of said step 2) comprises the step of obtaining a final product. The NF ₃ of the present invention The production method is very economical due to low electric power consumption and HF and NH ₃ consumption for NF ₃ production. Therefore, NF ₃ Lt; / RTI >

Description

METHOD FOR THE PRODUCTION OF NITROGEN TRIFLUORIDE < RTI ID = 0.0 >

The present invention relates to a novel method for economically producing nitrogen trifluoride (hereinafter referred to as NF ₃ ) on an industrial scale.

Nitrogen trifluoride (NF ₃ ) is a colorless gas having a boiling point of about -129 ° C and a melting point of about -208 ° C, and is usually used as a gas for plasma cleaning of a CVD apparatus and a gas for plasma cleaning such as silicon, polysilicon, Si ₃ N ₄ , WSi ₂ , MoSi _2, etc., and gases for excimer lasers. Recently, fluorine sources that are less active than fluorine have been used as fluorine sources in the production of fluoroolefins and as oxidants of high-energy fuels It is an industrially important gas used.

In particular, considering the specificity of the semiconductor field, which is constantly demanded for high purity control of raw materials and materials in accordance with the integration and miniaturization of semiconductors and precision, nitrogen trifluoride used in the above-mentioned applications has high purity Quality and manufacturing cost reduction are urgently required.

NF ₃ The industrial production method of the gas can be largely divided into direct fluorination (hereinafter referred to as DF method) and electrochemical fluorination (hereinafter referred to as ECF method).

The DF method is characterized in that a fluorine (F ₂ ) gas is produced by electrolysis (electrolysis) of HF in the first step, and the F ₂ gas and NH ₃ gas obtained in the first step in the second step are reacted in a liquid phase of acid ammonium fluoride (Crude) NF ₃ gas by reacting at a temperature of 110 ° C to 135 ° C (see US Pat. No. 4,091,081).

On the other hand, the characteristics of the ECF process is NH ₃ and a non-aqueous molten salt consisting of HF (for example, NH ₃ · 2.6HF) in the electrolyte solution, and the crude NF ₃ gas by electrolysis and directly to 110 ℃ ~ 135 ℃ (See Japanese Patent No. 3986175).

The crude NF ₃ gas obtained by the DF method and the ECF method is purified to obtain the product NF ₃ (see Japanese Patent No. 1446989).

The DF method has the advantage that the reaction yield of NF ₃ is as high as about 90% and the electric power used for electrolysis is small. However, the NF ₃ In the reaction, the by-product HF is reacted with NH ₃ (NH ₃ · nHF, hereinafter referred to as AAF), which must be removed and discarded out of the system, resulting in an increase in the amount of raw HF and NH ₃ used.

On the other hand, ECF method do not need to be removed and discarded out of the system because the AAF deliver the ammonium acid fluoride (AAF) The amount of HF and NH ₃ is low, NF ₃ There is a drawback that the reaction yield is as low as about 70% and the electric power used for electrolysis is large.

DF method An outline of an industrial production method of NF ₃ gas is as follows.

In the first electrolytic cell, HF was electrolyzed in the presence of KF to produce F ₂ from the anode and H ₂ from the cathode. The F ₂ was removed and the acid ammonium fluoride (hereinafter abbreviated as AAF-1) NH ₃ to obtain NF ₃ gas. The reaction formula is as follows.

Step 1:

6HF? 3H ₂ + 3F ₂

Second-step reaction:

3F ₂ + NH _{3 -} > NF ₃ + 3HF

mNH ₃ + 3HF? m (NH ₃ .nHF) = m (AAF-1)

(N = 1.5 to 3, n 占 m = 3, and m = 1 to 2)

The above reaction schemes are summarized as one reaction formula.

_{(1 + m) NH 3 +} 6HF → NF 3 + 3H 2 + mAAF-1

AAF-1 produced as a by-product in the fluorination reactor of the DF method is usually discarded. The theoretical value of HF required to produce 1 kg of NF ₃ is 1.69 and NH ₃ is 0.48 to 0.72.

On the other hand, an outline of an industrial production method of the ECF method NF ₃ gas is as follows.

The electrolytic solution is acidic ammonium fluoride (hereinafter abbreviated as AAF-2 in the ECF method) and commercially available ammonia (NH ₃ ), ammonium fluoride (NH ₃ .HF) or acid ammonium fluoride (NH ₃ 2HF) and anhydrous hydrogen fluoride (HF). This electrolytic solution is electrolyzed to a nickel anode. NF ₃ The gas is generated from the anode, and the crude NF ₃ Gas is obtained. The reaction formula is as follows.

NH ₃ + 3HF? NF ₃ + 3H ₂

The theoretical value of HF required to produce 1 kg of NF ₃ is 0.85 and NH ₃ is 0.24. That is, although the amount of HF and NH ₃ required for the production of NF ₃ is half the level of the DF method, the ECF method uses a large amount of power.

As described above, the DF method consumes a small amount of raw material but consumes a small amount of raw material instead of using a large amount of raw material and a large amount of electricity in contrast to the ECF method. Therefore, NF ₃ Development of the manufacturing process is urgently needed.

U.S. Patent No. 4091081 Japanese Patent No. 3986175 Japanese Patent No. 1446989

Accordingly, the present invention with that the advantages of the DF method, that is, less power usage, and advantages of the ECF method, i.e. HF and a small amount of NH ₃ is that, that a novel With all advantages of the two methods NF ₃ production Process.

According to an aspect of the present invention,

1) electrolyzing fluoric acid (HF) in a first electrolytic cell to generate fluorine (F ₂ ) gas;

2) reacting the fluorine (F ₂ ) gas with ammonia (NH ₃ ) in a fluorination reactor to obtain nitrogen trifluoride (NF ₃ ) and producing a first acid ammonium fluoride (AAF-1) as a byproduct;

3) A second acidic ammonium fluoride (AAF-2) is prepared by adjusting the molar ratio of hydrofluoric acid (HF), ammonia (NH ₃ ) or the like to the first acid ammonium fluoride (AAF-1) ;

4) electrolyzing the second acid ammonium fluoride (AAF-2) in a second electrolytic cell to produce nitrogen trifluoride (NF ₃ ); And

5) combining the nitrogen trifluoride (NF _3), obtained in three nitrogen trifluoride (NF ₃₎ obtained in the fluorination reactor and the three-step 4) of said step 2) comprises the step of obtaining a final product

A method for producing nitrogen trifluoride is provided.

The NF ₃ of the present invention The production method is very economical due to low electric power consumption and HF and NH ₃ consumption for NF ₃ production. Therefore, NF ₃ Lt; / RTI >

1 is a schematic process diagram of a method for producing NF ₃ according to a preferred embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings. Unless otherwise noted,% refers to% by weight.

1 is a schematic process configuration diagram of a preferred embodiment of the present invention.

The present invention relates to a method for economically producing nitrogen trifluoride,

1) generating fluorine (F ₂ ) gas by electrolyzing hydrofluoric acid (HF) in the first electrolyzer 21;

2) reacting the fluorine (F ₂ ) gas with ammonia (NH ₃ ) in the fluorination reactor 25 to obtain nitrogen trifluoride (NF ₃ ) and producing a first acid ammonium fluoride (AAF-1) ;

3) A second acidic ammonium fluoride (AAF-2) is prepared by adjusting the molar ratio of hydrofluoric acid (HF), ammonia (NH ₃ ) or the like to the first acid ammonium fluoride (AAF-1) ;

4) electrolyzing the second acid ammonium fluoride (AAF-2) in a second electrolytic bath 26 to produce nitrogen trifluoride (NF ₃ ); And

5) combining the nitrogen trifluoride (NF _3), obtained in three nitrogen trifluoride (NF ₃₎ obtained in the fluorination reactor and the three-step 4) of said step 2) comprises the step of obtaining a final product

A method for producing nitrogen trifluoride is provided.

According to a preferred embodiment of the present invention, the molar ratio of hydrofluoric acid to ammonia in the first acid ammonium fluoride (AAF-1) is 1.5 to 3.

According to a preferred embodiment of the present invention, the molar ratio of hydrofluoric acid to ammonia in the second acidic ammonium fluoride (AAF-2) may be adjusted to 2 to 3.5.

According to a preferred embodiment of the present invention, the fluorine gas generated in the first electrolyzer 21 of the step 1) is refined in the first refining tower 24 before the fluorine gas introduced into the fluorination reactor 25 of the step 2) Step < / RTI >

Further, according to a preferred embodiment of the present invention, the nitrogen trifluoride generated in the second electrolytic bath 26 of the step 4) is purified in the second purification tower 29 before the nitrogen trifluoride obtained in the step 4) is combined with nitrogen trifluoride Step < / RTI >

The present invention, in the DF method, the first acidic ammonium fluoride by reacting the F ₂ and NH ₃ is obtained by electrolysis of HF in a first electrolytic bath 21 in the fluorination reactor that produced NF _3, and then by-product herein (NH ₃ · nHF, n is 1.5 to 3) are taken out and HF and NH ₃ are added by adding HF and / or NH ₃ The molar ratio a in a second acidic ammonium fluoride is adjusted to 2 to 3.5, and then, this ECF method of claim 2, NF ₃ to be delivered is introduced into the electrolytic bath 26, and from the fluorination reactor to the product NF ₃ with a NF ₃ obtained new Lt; / RTI >

More specifically, the method of the present invention is characterized in that fluorine (F ₂ ) generated by electrolyzing hydrofluoric acid (HF) in the first electrolytic cell 21 is reacted with ammonia (NH ₃ ) in a fluorination reactor in the presence of AAF- 2 obtained by adding HF and / or NH ₃ to AAF-1 as a by-product in the reaction for producing NF ₃ at a temperature of 50 to 200 A / dm ² and it passes to the density is a very economical NF ₃ production process to obtain a product NF ₃ with the NF ₃ from NF ₃ and a second electrolytic cell (26) from the generation by the NF _3, fluorination reactor (25).

DF method is found in F ₂ from, generally, the carbon electrode of HF under KF present, a current density of 100 ~ 300 · A first electrolytic bath 21, and electrolysis, the anode 22 in the condition as described above, the dm ^-2 And H ₂ from the cathode 23. The anode gas containing impurities such as HF generated from the anode 22 is purified in the first purification column 24 and F ₂ is taken out and introduced into the fluorination reactor 25 and NH ₃ and NH ₃ are introduced into the fluorination reactor 25 in the presence of AAF- And reacted at a temperature of 110 ° C to 135 ° C. Here, the yield of crude NF ₃ is as high as 90%. Most of the gaseous side reaction impurities are N ₂ , and the approximate compositions are 90% NF _{3 and} 10% N ₂ .

The HF produced in the fluorination reaction reacts with the liquid raw material, NH ₃ , to produce the liquid by-product AAF-1. The n of AAF-1 is determined depending on the reaction temperature and the like, but is usually about 1.5 to 3.

The AAF-1 is taken out of the fluorination reactor 25, and then HF and / or NH ₃ is added to adjust the n of the AAF to 2 to 3.5, resulting in AAF-2. AAF-2 is supplied to the second electrolytic cell 26 of the ECF method and is delivered to the nickel anode 27 to obtain crude NF ₃ gas from the anode 27. In the cathode 28, H ₂ is generated. NF ₃ in the second electrolytic bath 26 The yield is about 70%. Most of the gaseous side-reaction impurities of the second electrolytic bath 26 are N ₂ , and the approximate composition is 70% of NF _{3 and} 30% of N ₂ . In the second electrolytic bath 26, the entire amount of AAF-2 is used without being discarded.

The current density of the ECF electrolyzer 26 is 50 to 200 A · dm ^-2 and the electrolytic temperature is 110 to 135 ° C. . Below the lower limit of the current density, the productivity of NF ₃ gas decreases but there is no technical limitation. If the upper limit of the current density is exceeded, the heat generated in the vicinity of the electrode is almost proportional to the current density. Therefore, if the current density is remarkably increased, the temperature of the electrolyte locally becomes higher and the composition of the electrolyte is not stabilized. A problem arises. The range of the current density is more preferably in the range of 60 to 150 A · dm ^-2 .

On the other hand, as the cathode 27 used for electrolysis, iron, stainless steel, nickel, monel and the like can be used.

Article 2 NF ₃ gas obtained from the anode 27 of the electrolytic cell 26 and a second purifying column (29), the NF ₃ and the combined product NF ₃ is purified coming from the fluorination reactor 25 through the pipe 13 via do.

<Examples>

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following examples are only illustrative examples of the present invention, and thus the scope of the present invention is not limited thereto.

Example  One

DF method HF was supplied to the first electrolytic cell 21 at a rate of 2.20 kg / h by the piping 1 and electrolyzed to obtain 1.99 kg / h of F ₂ through the refining tower 24. This F ₂ was supplied to the fluorination reactor 25 by the pipe 5, and NH ₃ was supplied at 0.77 kg / h by the pipe 2. 1.10 kg / h of NF ₃ and 0.05 kg / h of N ₂ were obtained by the pipe 7 from the fluorination reactor 25. This was discharged _{AAF-1 (NH 3 · 2.2HF} ) of 1.60 kg / h by the pipe 8. The power consumption was 38 kWh. The HF was added to the AAF-1 of the pipe 8 at 0.21 kg / h by the pipe 9 to produce 1.81 kg / h of AAF-2, and the ECF-method second electrolytic bath 26 was produced by the pipe 10, . 1.13 kg / h of NF ₃ and 0.19 kg / h of N ₂ were obtained from the pipe 13 by electrolysis in the second electrolytic bath 26. The power consumption was 45 kWh. In the pipe 15, 2.23 kg / h of NF ₃ and 0.24 kg / h of N ₂ were obtained. In this manufacturing method, the HF unit was 1.08, the NH ₃ unit was 0.35, and the power unit was 37.2 kWh.

Comparative Example  One

In Example 1, the DF method alone produced NF ₃ , where the HF unit was 2.00, the NH ₃ unit was 0.70, and the power unit was 34.5 kWh.

Comparative Example  2

In Example 1, the ECF method alone produced NF ₃ , where the HF unit was 1.20, NH ₃ The basic unit was 0.40 and the electric power unit was 39.8 kWh.

As can be understood from the above examples and comparative examples, the production method of the present invention is an epoch-making NF ₃ production method having a low basic unit of HF and NH ₃ and an economical efficiency because of low electric power consumption.

pipe
1. HF 9. HF
2. NH ₃ 10. AAF-2
3. HF + F ₂ 11. NF ₃ + HF
4. H ₂ 12. H ₂
5. F ₂ 13. NF ₃
6. HF 14. HF
7. NF ₃ 15. NF ₃
8. AAF-1 16. H ₂
Device
21. First electrolyzer
22. Anode
23. Cathode
24. First purification tower
25. Fluorination Reactor
26. Second electrolyzer
27. Anode
28. Cathode
29. Second Tablet Tower

Claims (5)

1) electrolyzing fluoric acid (HF) in a first electrolytic cell to generate fluorine (F ₂ ) gas;
2) reacting the fluorine (F ₂ ) gas with ammonia (NH ₃ ) in a fluorination reactor to obtain nitrogen trifluoride (NF ₃ ) and producing a first acid ammonium fluoride (AAF-1) as a byproduct;
3) adding a hydrofluoric acid (HF) to the first acid ammonium fluoride (AAF-1) to produce a second acid ammonium fluoride (AAF-2) in which the molar ratio of hydrofluoric acid to ammonia is adjusted;
4) electrolyzing the second acid ammonium fluoride (AAF-2) in a second electrolytic cell to produce nitrogen trifluoride (NF ₃ ); And
5) combining the nitrogen trifluoride (NF _3), obtained in three nitrogen trifluoride (NF ₃₎ obtained in the fluorination reactor and the three-step 4) of said step 2) comprises the step of obtaining a final product
A method for producing nitrogen trifluoride.
The method according to claim 1,
Wherein the first acidic ammonium fluoride (AAF-1) has a molar ratio of hydrofluoric acid to ammonia of 1.5-3.
The method according to claim 1,
Wherein the second acidic ammonium fluoride (AAF-2) has a molar ratio of hydrofluoric acid to ammonia adjusted to 2 to 3.5.
The method according to claim 1,
Further comprising the step of purifying the fluorine gas generated in the first electrolytic cell of the step 1) in the first purification tower before introducing the fluorine gas into the fluorination reactor of the step 2).
The method according to claim 1,
Further comprising purifying the nitrogen trifluoride in the second purification tower before combining the nitrogen trifluoride generated in the second electrolytic cell in step 4) with the nitrogen trifluoride obtained in step 4).

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