KR101343961B1 - Method for eliminating unwanted substances from a mixed gas comprising chlorine trifluoride and fluorine - Google Patents

Abstract

In the method for removing and treating a mixed gas composed of at least chlorine trifluoride and fluorine with a wet scrubber, the mixed gas may include halogen gas X ₂ (X = Cl, Br, or I) at a previous stage of the decontamination treatment with a wet scrubber. ) And reacting the fluorine in the mixed gas with halogen gas X ₂ (which represents X = Cl, Br or I), thereby reducing the fluorine in the mixed gas and producing perchloryl fluoride produced by the wet scrubber. A decontamination method is disclosed which prevents the production of (ClO ₃ F) in advance.

Description

METHOD FOR ELIMINATING UNWANTED SUBSTANCES FROM A MIXED GAS COMPRISING CHLORINE TRIFLUORIDE AND FLUORINE}

The present invention relates to a method for removing a mixed gas consisting of chlorine trifluoride and fluorine.

Chlorine trifluoride (ClF ₃ ) is widely known to be synthesized by the direct reaction of chlorine and fluorine, as shown in the following Scheme 1 (Non Patent Literatures 1 and 2).

[Formula 1]

Cl ₂ + 3F ₂ → 2ClF ₃

In a typical ClF ₃ production process, ClF ₃ produced in the reactor passes through a cold collector, and only the desired product is selectively collected.

Because normally it is not during the cooling gas passing through the collector are all F ₂ or a gas containing the unreacted collected ClF _3, it is treated by the harm-elimination of water or wet scrubber (exhaust gas treatment unit) with alkali solution.

However, in the case where the mixed gas of ClF ₃ and F ₂ is removed and treated with a wet scrubber using water, oxygen radicals are generated when fluorine reacts with water as shown in the following Scheme 2.

(2)

F ₂ + H ₂ O → 2HF + O ^*

In addition, as shown in the following Scheme 3, the generated oxygen radicals react with ClF ₃ to generate perchloryl fluoride (ClO ₃ F).

(3)

ClF ₃ + H ₂ O + 2O ^* → ClO ₃ F + 2HF

ClO ₃ F is a thermally stable compound and does not pyrolyze unless warmed to 470 ° C. In addition, it is insoluble in water and cannot be decomposed into an acid or an alkali. In addition, when ClO ₃ F is contained at a low concentration in a gas similar to that of ClO ₃ F, the separation and concentration by distillation are difficult, and thus there is a problem that removal is difficult.

In the countermeasure of the said problem, the method of using the absorption liquid containing a sulfur type reducing agent and a basic compound as a method of removing fluorine gas or oxygen fluoride from a fluorine-containing gas is proposed (patent document 1).

Japanese Laid-Open Patent Publication No. 2006-231105

 Fluorine Chemistry and Industry, Watanabe Nobuatsu Editing, Chemical Industry, p46-68  J. W. Grisard: J. Amer. Chem. Soc., 73, (1951) p5724

However, in the method of using the absorbent liquid containing the sulfur-based reducing agent and the basic compound proposed in Patent Literature 1, since the price of the reducing agent itself is expensive and the concentration control of the reducing agent in the absorbent liquid is required, a wet scrubber is used. There was a problem that the operation of the used decontamination treatment process was complicated.

Thus, the present invention is in the handling of harm-elimination by the mixed gas comprising the ClF ₃ and F ₂ in the wet scrubber, and I is a problem to provide a detoxicating way to suppress the generation of ClO ₃ F decomposable material.

The present inventors, in order to solve the above problems, example the review, a mixed gas containing ClF ₃ and F ₂ In the former (前) processing of harm-elimination by the wet scrubber, installing heating the reaction section, and Scheme 4 As can be seen from the above, by adding a halogen gas to the mixed gas, the unreacted fluorine gas is reacted with the halogen gas, and the unreacted fluorine gas is greatly reduced, which is a problem in the method for removing ClF ₃ using a conventional wet scrubber. It was found out that the generation of ClO ₃ F, which is a hardly decomposable substance, can be suppressed, and the present invention was reached.

[Formula 4]

F ₂ + X ₂ → 2XF (indicates X = Cl, Br or I)

That is, the present invention relates to a method of removing and treating a mixed gas composed of chlorine trifluoride and fluorine with a wet scrubber, wherein the mixed gas includes halogen gas X ₂ (X = By adding Cl, Br, or I) and reacting the fluorine in the mixed gas with halogen gas X ₂ (indicative of X = Cl, Br, or I), thereby reducing the fluorine in the mixed gas, thereby producing a wet scrubber. The present invention provides a method for preventing the formation of perchloryl fluoride.

1 is a schematic diagram of an experimental apparatus used in the present invention.

When the mixed gas containing ClF ₃ and F ₂ is removed by a wet scrubber, the present invention can greatly suppress the generation of ClO ₃ F, which is a hardly decomposable substance, and is effective for treating ClO ₃ F, which is a hardly decomposable substance. It is possible to provide a simple method that does not require the use of expensive reducing agents used or complicated concentration control.

In addition, the present invention can significantly reduce unreacted fluorine gas in the previous step of the decontamination treatment by the wet scrubber, and thus generates an oxyfluoride compound such as oxygen difluoride (OF ₂ ) having high toxicity in the wet scrubber. It is also effective to suppress.

Hereinafter, an example of the preferable embodiment of this invention is demonstrated.

The mixed gas of chlorine trifluoride and fluorine to be treated includes other interhalogen gases such as ClF ₅ , ClF, BrF ₅ , BrF ₃ , BrF, IF ₇ , IF ₅ , IF ₃ , IF, and NF ₃ . Do not disturb

Halogen gas other than fluorine is used for the raw material gas for reducing unreacted fluorine gas, and chlorine, bromine, or iodine can be used.

It is preferable to add halogen equivalents other than fluorine to add 1.0 equivalent or more with respect to unreacted fluorine gas.

In addition, although halogen gas other than fluorine to be added can be used without particular dilution, it can also be diluted and used with inert gas, such as nitrogen and argon.

The material used for the reactor is preferably nickel or monel having high fluorine gas resistance at high temperatures and having sufficient mechanical strength.

It is preferable that the temperature of a reaction part is 200 degreeC-400 degreeC, and, as for reaction temperature, 300 degreeC-350 degreeC are especially preferable. The reaction is less likely to proceed at a temperature lower than 200 ° C., and at temperatures higher than 400 ° C., the reactor is significantly corroded, which is not preferable.

In order to reduce fluorine in the mixed gas having a fluorine concentration of 1 to 10% to about 1 to 10 ppm, it is preferable to hold the mixed gas introduced into the reactor for at least 30 seconds or more.

The supply method of the mixed gas and halogen gas which consist of chlorine trifluoride and fluorine which introduce | transduce into a reactor will not be specifically limited if it can supply to a reactor.

It is preferable to use the scrubber using water or an alkaline solution, and, as for the wet scrubber used for decontamination process, it is especially preferable to use a water scrubber in the 1st stage and an alkali scrubber in the 2nd stage.

As the alkaline solution used for the wet scrubber, a KOH solution, a NaOH solution, or the like can be used. In particular, it is preferable to use a KOH solution having a relatively high solubility in water.

Example

The following Examples illustrate the present invention, but the present invention is not limited to these Examples.

1 shows a schematic schematic diagram of an experiment using the present invention. The mass flow controllers 1 and 2 control the flow rates of the halogen gas, the mixed gas of the chlorine trifluoride gas and the fluorine gas, respectively, and introduce the gas into the nickel cylindrical reactor 3. The nickel tubular reactor 3 can be heated to a predetermined temperature by a heater 4 provided outside.

After reacting the gas introduced into the nickel tubular reactor 3 previously heated to a predetermined temperature for a predetermined time, the scrubber of an alkaline solution having a KOH concentration of 0.1 mol / L and water connected to the rear end of the nickel tubular reactor 3 is A decontamination treatment operation is performed by the exhaust gas treating apparatuses 5 and 6.

In addition, the outlet gas of the scrubber flow is sampled and analyzed by FT-IR (IG-1000, manufactured by Otsuka Electronics Co., Ltd.), and the concentration of ClO ₃ F is measured.

Example 1

Mixing of 2.8 mol% fluorine gas and 3.5 mol% ClF ₃ using the massflow controller 1 by setting the outer wall temperature of the cylindrical reactor 3 made of nickel with a diameter of 30 mm and a length of 600 mm to 350 ° C. After gas was introduced at 75 ml / min and the mass flow controller 2, 3.4 mol% of chlorine gas was introduced into the cylindrical tubular reactor 3 at a flow rate of 10 ml / min, and reacted for 30 seconds. After decontamination by scrubbers (exhaust gas treatment apparatuses) 5 and 6 of an alkaline solution having a water and a KOH concentration of 0.1 mol / L, connected to the sample, the outlet gas of the scrubber flow was sampled, and FT-IR (Otsuka Electronics Co., Ltd.) It was 180 volppm when the ClO ₃ F concentration was analyzed using IG-1000).

Comparative Example 1

It carried out on the conditions similar to Example 1 except not adding chlorine gas. As a result, the ClO ₃ F concentration in the sampled gas was 6000 volppm.

[Example 2]

Mixing 5.0 mol% of fluorine gas and 3.0 mol% of ClF ₃ using the massflow controller 1 by setting the outer wall temperature of the cylindrical reactor 3 made of nickel 12.4 mm and the length 1000 mm to 350 ° C. After 493 ml / min of gas and the mass flow controller 2, 6.0 mol% of chlorine gas was introduced into the cylindrical tubular reactor 3 made of nickel at a flow rate of 44 ml / min, and reacted for 30 seconds. After decontamination by scrubbers (exhaust gas treatment apparatuses) 5 and 6 of an alkaline solution having a water and a KOH concentration of 0.1 mol / L, connected to the sample, the outlet gas of the scrubber flow was sampled, and FT-IR (Otsuka Electronics Co., Ltd.) It was 4 volppm when the ClO ₃ F concentration was analyzed using IG-1000).

Comparative Example 2

It carried out on the conditions similar to Example 2 except not adding chlorine gas. As a result, the ClO ₃ F concentration in the sampled gas was 3500 volppm.

[Example 3]

Mixing of 2.8 mol% fluorine gas and 3.5 mol% ClF ₃ using the massflow controller 1 was performed by setting the outer wall temperature of the cylindrical reactor 3 made of nickel with a diameter of 30 mm and a length of 600 mm to 370 ° C. After gas was introduced at 75 ml / min and the mass flow controller 2, 3.4 mol% of chlorine gas was introduced into the cylindrical tubular reactor 3 at a flow rate of 10 ml / min, and reacted for 30 seconds. After decontamination by scrubbers (exhaust gas treatment apparatuses) 5 and 6 of an alkaline solution having a water and a KOH concentration of 0.1 mol / L, connected to the sample, the outlet gas of the scrubber flow was sampled, and FT-IR (Otsuka Electronics Co., Ltd.) It was 160 volppm when the ClO ₃ F concentration was analyzed using IG-1000).

[Comparative Example 3]

It carried out on the conditions similar to Example 3 except not adding chlorine gas. As a result, the ClO ₃ F concentration in the sampled gas was 5600 volppm.

Claims (3)

In the method of removing the mixed gas containing chlorine trifluoride and fluorine with a wet scrubber,
In a step before decontamination by a wet scrubber, halogen gas X ₂ (which represents X = Cl, Br or I) is added to the mixed gas, and fluorine and halogen gas X ₂ (X in the mixed gas). Chlorine trifluoride, characterized in that fluorine in the mixed gas is reduced to prevent the generation of perchloryl fluoride (ClO ₃ F) produced by a wet scrubber. And a method for removing a mixed gas containing fluorine. The method of claim 1,
A method for removing a mixed gas containing chlorine trifluoride and fluorine, wherein 1.0 equivalent or more of halogen gas X ₂ (indicative of X = Cl or Br or I) is added to the fluorine gas in the mixed gas. 3. The method according to claim 1 or 2,
Method for removing a mixed gas containing chlorine trifluoride and fluorine characterized by reacting fluorine in the mixed gas and halogen gas X ₂ (which represents X = Cl, Br or I) at a temperature range of 200 ° C to 400 ° C. .

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