JP3067633B2 - Method for producing perfluorocarbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing perfluorocarbon by reacting hydrofluorocarbon and fluorine gas in the gas phase, wherein the enhanced reaction of hydrofluorocarbon and fluorine gas in the gas phase in the first reaction zone is carried out. The product gas generated by contacting at the temperature is led to the second reaction zone as a diluent gas, and a hydrofluorocarbon different from the first reaction zone is supplied with a fluorine gas as needed, and the gas is contacted at an increased reaction temperature. And a method for producing a perfluorocarbon. Perfluorocarbon is a compound that is gaseous at room temperature, has a wide range of uses such as an etching gas and a cleaning gas in the semiconductor industry, and a compound that is liquid at room temperature is a liquid for cooling and is industrially useful.

[0002]

2. Description of the Related Art Various methods have been proposed for producing perfluorocarbons. For example,
In the case of perfluorocarbon having one carbon atom, tetrafluoromethane (hereinafter referred to as “FC-14” or “CF ₄ ”), a method of reacting chlorotrifluoromethane (CCIF ₃ ) with HF in the presence of a catalyst (Japanese Patent Publication No. 62-1
0211), dichlorodifluoromethane (CCl
₂ F ₂₎ and No. 42-3004 method (JP-B is reacted with HF in the presence of a catalyst), carbon tetrachloride (method of reacting with the CCl ₄₎ HF (Japanese Patent Publication No. 43-10601), trifluoromethane (CHF ₃ ) reacting F ₂ with F ₂ (G
B-1116920: 1986 years), a method of reacting carbon (C) and F ₂ in BrF ₃ or IF ₅ (JP 58-16
2536), ethylene tetrafluoride (CF ₂ = CF ₂ )
For thermally decomposing CO ₂ and CO ₂ at high temperature (US Pat. No. 4,365,651)
02: 1982).

Further, for example, hexafluoroethane of perfluorocarbon having two carbon atoms (hereinafter referred to as “FC-1”)
16 "or" CF ₃ CF ₃ "), an electrolytic fluorination method using ethane and / or ethylene as a raw material,
Pyrolysis method of pyrolyzing ethylene tetrafluoride, etc., fluorination of acetylene, ethylene and / or ethane, etc. using metal fluoride, dichlorotetrafluoroethane, chloropentafluoroethane, etc. using hydrogen fluoride A fluorination method, a direct fluorination method of reacting with ethane or the like using fluorine gas, and the like are known.

Further, for example, octafluoropropane of perfluorocarbon having three carbon atoms (hereinafter referred to as "FC
-218 "or the" called C ₃ F ₈ "), directly reacted with propane using a fluorine gas fluorination method (E
P-31519: 1981).

In the direct fluorination method using fluorine gas, (a) a method in which fluorine gas and ethane are reacted by a jet reactor to obtain FC-14 or FC-116 (.)
J. Amer. Chem. Soc., 77, 3307 (1955), J. Amer. Chem. So
c., 82, 5827 (1960)), (b) Method of fluorinating CH with fluorine gas in a reactor having a porous alumina tube (EP-3)
1519 (1981)), (c) A method of fluorinating linear hydrocarbons with fluorine gas in a reactor having a porous metal tube (double tube structure) in the presence of a diluent gas: SF as diluent gas ₆ ,
Use of CF ₄ , C ₂ F ₆ and C ₃ F ₈ (EP-33210 (1981)) and the like are known. As another reaction example using a fluorine gas, (d) a method of producing a hydrofluorocarbon by reacting a saturated or unsaturated hydrocarbon or a partially fluorinated hydrocarbon with a fluorine gas (US-5406008 (199)
5)) and a method of producing an alkene fluoride from an alkene and carbon containing fluorine gas by adsorption (Japanese Patent Laid-Open No. 2-207052).

[0006]

As described above, the direct fluorination method using fluorine gas uses fluorine gas which is extremely reactive, so that the explosion and corrosion of the organic compound as a substrate with the fluorine gas can be prevented. There is a danger, and further, a breakage or polymerization of a C—C bond due to heat generation, a sudden reaction due to generation and deposition of carbon (C), and a side reaction such as an explosion are also dangerous.
For example, in the case of synthesizing a perfluorocarbon by a direct fluorination method in which a linear hydrocarbon compound is reacted with a fluorine gas, a very large heat of reaction is involved as follows.

[0007]

Embedded image Thus, in order to replace one C—H bond with a C—F bond, a reaction heat of about −110 Kcal / mol is generated. In the direct fluorination method in which propane and fluorine gas are reacted, ΔH is about -880 Kcal / mol.

When methane is used as a raw material (formula 2), 4 moles of fluorine are required per mole of methane, and when ethane is used as a raw material (formula 3), 6 moles of fluorine are required per mole of ethane. Thus, the heat of reaction is proportional to the number of moles of fluorine used, and the larger the amount of fluorine, the greater the heat of reaction. For this reason, breakage of the CC bond, explosion, etc. due to heat generation are likely to occur, and furthermore, the yield is lowered, which is a problem in industrial production and operation. For this reason, as a method of suppressing rapid generation of reaction heat in the direct fluorination method, a method of diluting fluorine with another inert gas (nitrogen, helium, or the like), a method of converting an organic compound as a substrate into an inert gas with respect to fluorine. A method of dissolving in a solvent at a low concentration, a method of performing a reaction in a low temperature range,
When the reaction is carried out in the gas phase, a method has been considered in which a device is devised in a jet reactor or the like so that the fluorine gradually contacts the organic compound as a substrate.

The present invention has been made to solve the above-mentioned problems and problems. Accordingly, the object of the present invention is to provide a direct fluorination method using an organic compound as a substrate and fluorine gas, which is industrially required. An object of the present invention is to provide a production method capable of producing perfluorocarbon safely, efficiently and economically.

[0010]

SUMMARY OF THE INVENTION The above-mentioned problems and problems are to be solved in a method for producing perfluorocarbon by reacting hydrofluorocarbon and fluorine gas in the gas phase. The reaction gas produced by contacting at an elevated reaction temperature is led to the second reaction zone as a diluent gas, and a hydrofluorocarbon different from the first reaction zone and, if necessary, fluorine gas are supplied thereto to increase the reaction. It is characterized in that the contact is performed at a temperature, and at least a part of the product gas in the second reaction zone is circulated and used as a diluent gas in the first reaction zone.

[0011] The diluent gas is tetrafluoromethane, hexafluoroethane, octafluoropropane and hydrogen fluoride, preferably tetrafluoromethane, hexafluoroethane and hydrogen fluoride, more preferably rich in hydrogen fluoride. Component.

In carrying out this reaction, it is necessary to carry out the reaction at a concentration of 8 mol% or less at the inlet of each reaction zone with the hydrofluorocarbon as a raw material. Further, it is desirable that the reaction temperature is in an elevated temperature range, preferably in the range of 200 to 550 ° C. in each reaction zone. It is desirable to carry out the reaction pressure within the range of 0 to 5 MPa in each reaction zone. There are two or more types of perfluorocarbons obtained by this reaction, FC-14,
FC-116 and FC-218, preferably
C-14 and FC-116.

The supplied hydrofluorocarbon has the following general formula: CxHyFz (1 ≦ x ≦ 3, 1 ≦ y ≦ 4, 1
Y + z = 4 when ≦ z ≦ 7 and x is 1, y when x is 2
It is an integer satisfying y + z = 8 when + z = 6 and x is 3. ), Preferably fluoromethane (CH ₃ F), difluoromethane (CH ₂ F ₂ ), trifluoromethane (CHF ₃ ), trifluoroethane (C ₂ H ₃ F ₃ ) ,
Tetrafluoroethane (C ₂ H ₂ F ₄ ), pentafluoroethane (C ₂ HF ₅ ), pentafluoropropane (C
₃ H ₃ F ₅ ), hexafluoropropane (C ₃ H
₂ F ₆₎ and heptafluoropropane (C ₃ HF ₇₎
And more preferably fluoromethane, difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane and pentafluoroethane, even more preferably difluoromethane, trifluoromethane, tetrafluoroethane and pentafluoroethane. . Further, it is preferable to use a hydrofluorocarbon having a concentration of a chlorine-containing compound as an impurity contained in the supplied hydrofluorocarbon of 2 mol% or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing perfluorocarbon of the present invention will be described below in more detail. In the present invention, the second reaction is performed by using a product gas (perfluorocarbon and / or hydrogen fluoride) produced by bringing a hydrofluorocarbon and a fluorine gas into contact with each other in a gas phase at an elevated reaction temperature in a first reaction zone as a diluent gas. A perfluorocarbon, which is supplied to a hydrofluorocarbon different from that of the first reaction zone and, if necessary, is supplied with fluorine gas at an elevated reaction temperature. By circulating at least a portion of fluorocarbon and / or hydrogen fluoride) and using it as a diluent gas in the first reaction zone, it overcomes the problems and problems of the conventional direct fluorine method, and is industrially safe, efficient and economical. Useful perfluorocarbons can be produced.

The first point of the present invention is a diluent gas. In the case of producing perfluorocarbon using hydrofluorocarbon and fluorine gas in this reaction, the reaction formula and reaction heat are as follows.

Embedded image

As the diluent gas, an inert gas such as nitrogen, helium, argon or the like is generally used. However, in consideration of the separation and purification of the perfluorocarbon of interest and these inert gases in the distillation step. It is not a method advantageous from the viewpoint of cost, and the diluent gas is a gas containing a product gas of tetrafluoromethane, hexafluoroethane, octafluoropropane and hydrogen fluoride, preferably tetrafluoromethane, hexafluoroethane and A gas containing hydrogen fluoride, more preferably a component rich in hydrogen fluoride, is economical.

According to the present invention, hydrogen fluoride (boiling point: 20 ° C.) is produced as a by-product, for example, as in the above formulas (4) to (7). For example, when difluoromethane is used as a raw material organic compound, 1 mol of FC-14 and 2 mol of hydrogen fluoride are produced. In the case of pentafluoroethane,
One mole of FC-116 and one mole of hydrogen fluoride are produced, and the desired products, FC-14 (boiling point: -127.9 ° C.) and FC
The boiling point difference between −116 (boiling point: −78.5 ° C.) and hydrogen fluoride as a by-product is about 100 ° C., so that hydrogen fluoride can be easily separated in distillation and purification steps, and helium ( (Boiling point: -286.9 ° C.), etc., each of which has a higher boiling point, and has an advantageous energy cost for separation and purification.

Further, it is more cost-effective to use the reaction gas (perfluorocarbon and hydrogen fluoride) as the diluent gas as it is. In addition, hydrogen fluoride may be recovered as hydrogen fluoride in a distillation and purification process as a diluting gas and recycled, but is usually used for other purposes. In the direct fluorination method using fluorine gas, as described above, carbon is generated or deposited due to cleavage of C—C bonds or a polymer in a long-term reaction. There is a danger of a rapid reaction or explosion with the fluorine gas in the generation and deposition of carbon, but the generation and deposition of carbon can be suppressed by using a component rich in hydrogen fluoride as a diluent gas. The component rich in hydrogen fluoride means that hydrogen fluoride is a main component.

The reaction is carried out in the presence of a hydrofluorocarbon (reaction substrate), fluorine gas and a diluent gas. Before introduction into the reactor, either or both of the reaction substrate and fluorine gas are diluted with the diluent gas. Later, it is common to introduce into the reactor. In consideration of safety, it is desirable that both the substrate for the reaction and the fluorine gas be diluted with a diluent gas as low as possible.

The second point of the present invention is to carry out the reaction with the hydrofluorocarbon as a substrate for the reaction at a reactor inlet concentration of 8 mol% or less. As described above, in the direct fluorination method using fluorine gas, an extremely reactive fluorine gas is used, so that an organic compound (particularly a compound containing hydrogen) serving as a substrate burns or explodes when exposed to fluorine. There is danger. In this reaction,
Since hydrogen-containing hydrofluorocarbon is used as an organic compound as a substrate, prevention of explosion of hydrofluorocarbon and fluorine is an important point. To prevent explosion, it is necessary to keep the composition of the gas mixture out of the explosion range. The present inventors examined the explosion range of hydrofluorocarbon and fluorine gas,
Although the value varies depending on the type of hydrofluorocarbon, it has been found that the lower limit of the explosion range of these hydrofluorocarbons is 8 mol% or less, and a safe range of the organic compound inlet concentration in this reaction can be set.

The reaction temperature is also one of the important conditions for efficiently proceeding this reaction, and the optimum range of the reaction temperature varies depending on the contact time and the type of the starting material hydrofluorocarbon. For example, when reacting 1,1,1,2-tetrafluoroethane and fluorine in the presence of a diluent gas, when the contact time is long (contact time 15 seconds), the reaction temperature is about 50.
The reaction takes place at about 250 ° C, and the conversion is about 100% at about 250 ° C.
It is. The reaction temperature is in an elevated temperature range, and the first reaction zone and the second reaction zone are preferably 200 to 55, respectively.
Within the range of 0 ° C.

If the reaction temperature is lower than 200 ° C., the conversion of hydrofluorocarbon decreases, and if it exceeds 550 ° C., the C—C bond is broken or polymerized to lower the yield. It is not preferable because it has a problem such as an increase in cost. Although the contact time is not particularly limited, for example, in the range of 0.1 to 120 seconds, if the contact time is increased, the reactor becomes large and it is not economical.
Second, more preferably in the range of 3 to 30 seconds, it is also important to improve the mixing of the reaction substrate with the fluorine gas.

The molar ratio between the hydrofluorocarbon and the fluorine gas supplied to the reaction system is preferably in the range of 0.5 to 5.0, more preferably 1.0 to 5.0.
It is in the range of 3.0. The supply molar ratio of the fluorine gas is 0.
If it is less than 5, the reaction does not proceed and the efficiency is poor. If it exceeds 5.0, the fluorine gas becomes excessive and equipment for recovery thereof is required, which is not economical. The method for supplying the fluorine gas is not particularly limited.For example, an excess amount may be supplied to the first reaction zone, and the reaction of the second reaction zone may be performed with the remaining unreacted fluorine gas. It is preferable to supply both to the second reaction zone from the viewpoint of safety.

In carrying out this reaction, the reaction pressure is also important for preventing danger such as explosion. The higher the pressure, the broader the explosion range generally becomes. Therefore, the reaction is desirably performed at a lower pressure, and the reaction pressure in the first reaction zone and the second reaction zone is preferably in the range of 0 to 5 MPa.

The reactor is preferably made of a material having resistance to corrosive gas, and examples thereof include nickel, inconel and hastelloy.
As described above, the direct fluorination method between an organic compound as a substrate and fluorine gas involves a very large heat of reaction, and the heat of reaction is proportional to the number of moles of the fluorine gas used. Therefore, the CH bond is changed to C-
The smaller the number of substitutions by the F bond, the easier the control of the reaction heat, which becomes a problem, and the less the amount of expensive fluorine gas used, the more economical.

The third point of the present invention is that an organic compound as a substrate does not use a linear hydrocarbon having a large number of C—H bonds replaced by C—F bonds as described above, and is partially used. By using a fluorinated hydrofluorocarbon (HFC), the number of substitution of C—H bonds by C—F bonds is reduced to facilitate control of the reaction heat, and two or more types of hydrofluorocarbons are supplied. To produce more than one kind of perfluorocarbon. The hydrofluorocarbon used is represented by the following general formula: CxHyFz (general formula) (where x, y, and z are respectively 1 ≦ x ≦ 3, 1 ≦ y ≦
4, when 1 ≦ z ≦ 7 and x is 1, y + z = 4,
when x is 2, y + z = 6, and when x is 3, it is an integer satisfying y + z = 8).

Preferably, fluoromethane, difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, pentafluoropropane, wherein the number of substitution of C—H bonds by C—F bonds is 3 or less. It is selected from the group of fluoropropane and heptafluoropropane, and is more preferably fluoromethane, difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane and pentafluoroethane from the availability of raw materials, and more preferably a CH bond. Is a difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane, and pentafluoroethane in which the number of substituents to be a C—F bond is 2 or less, and these hydrofluorocarbons are, for example, chlorofuran. As replacements for Rokabon (CFC) and hydrochlorofluorocarbon (HCFC), also have been industrially produced as a refrigerant, it is good and it is easy purity even 99.9% availability.

As described above, when compared with the production of perfluorocarbon using fluorine gas of a linear hydrocarbon compound (formulas 2 and 3), the use of hydrofluorocarbon as described above reduces the heat of reaction by about 1/2. From 1/6
(Equations 4 to 7) can be suppressed. These hydrofluorocarbons can be used alone or in a mixture, and the perfluorocarbons of interest obtained therefrom are two or more, preferably tetrafluoromethane,
Hexafluoroethane and / or octafluoropropane, more preferably tetrafluoromethane and hexafluoroethane.

It is desirable that the hydrofluorocarbon as a raw material for the reaction does not contain a chlorine-containing compound, and when the chlorine-containing compound is contained, chlorine or chlorine fluoride is generated by the reaction, which is preferable in terms of equipment materials and distillation operation. Absent. The concentration of the chlorine-containing compound is preferably 2 mol% or less, preferably 1 mol% or less, and more preferably 0.1 mol% or less.
1 mol% or less.

The fourth important point of the present invention is to provide an economical, safe and efficient production method which is obtained by adding the above three points and the reaction conditions. Fluorine gas is contacted at an elevated reaction temperature to generate the first perfluorocarbon and hydrogen fluoride, and a part or all of these are introduced into the second reaction zone as a diluent gas, and this is mixed with the first reaction zone. A different hydrofluorocarbon from that supplied to the reactor and a fluorine gas, if necessary, are contacted at an elevated reaction temperature to generate a second perfluorocarbon and hydrogen fluoride, and a part of these is used as a diluent gas to form a second gas. One reaction zone and / or
Alternatively, it is a production method of recycling and using in the second reaction zone.

For example, 1,1,1,2-tetrafluoroethane and fluorine gas as hydrofluorocarbons in a gas phase are supplied as diluent gases together with a component rich in hydrogen fluoride to a first reaction zone at an elevated temperature, In the first reaction zone, FC-116 and hydrogen fluoride are produced as perfluorocarbons. A part of the gas at the outlet of the reactor can be used as it is as a diluent gas or can be led to a distillation step, but is usually led to a second reactor. As a different hydrofluorocarbon at the inlet of the second reactor, for example, difluoromethane and, if necessary, fluorine gas are mixed with the outlet gas of the first reaction zone and supplied to the second reaction zone at an increased reaction temperature, and as perfluorocarbon FC-
14 and hydrogen fluoride.

As the outlet gas of the second reaction zone, a mixture containing FC-116 and FC-14 as perfluorocarbons and excess hydrogen fluoride with respect to perfluorocarbons as by-products is obtained. A part of the mixture of the outlet gas of the second reaction zone is circulated and used as a dilution gas in the first reaction zone and / or the second reaction zone, and the remainder is converted into perfluorocarbon and hydrogen fluoride in the distillation and purification steps. Separated.

As described above, the present production method for producing two or more types of perfluorocarbons from two or more types of hydrofluorocarbons is different from the usual production of one perfluorocarbon from one type of hydrofluorocarbon, and is more difficult in terms of equipment such as a distillation step. It is economical in terms of simplification and energy costs.

In the reaction zone, one reactor can be divided into zones, but usually it is preferable to use two or more reactors from the viewpoint of operability and safety. The combination of the reactors can be selected either in parallel or in series, but usually the series is preferred. It is also possible to produce one kind of perfluoro compound, for example FC-14, from two or more kinds of hydrofluorocarbons, for example, difluoromethane and trifluoromethane. It is also possible to feed separately to the reaction zone and the second reaction zone to make the reaction mild. As described above, this production method is an industrially safe, efficient and economical production method of perfluorocarbon.

[0035]

Examples of the present invention will be described below. First, the raw material hydrofluorocarbon used in this reaction is shown below. [Difluoromethane] HCFC-22 (CHClF)
Supplied by and difluoromethane as replacements for _{2) (CH 2 F 2)} · Ekoroe - scan 32 (trade name: using Showa Denko). The pure content is 99.95% or more, contains 1,1,1-trifluoroethane (CF ₃ CH ₃ ) and fluoromethane (CH ₃ F) as impurities, and almost no chlorine-containing compound is detected.

[Trifluoromethane] Trifluoromethane (CHF ₃ ) Ecoloace 23 (trade name, manufactured by Showa Denko) currently supplied as a refrigerant was used. The pure content is 99.95% or more, and chlorodifluoromethane (CHClF ₂ ) or chlorotrifluoromethane (CCl
F ₃ ) and other chlorine-containing compounds.

[1,1,1,2-Tetrafluoroethane] The 1,1,1,2-tetrafluoroethane (CF ₃ CH ₂ F) currently supplied as a substitute for CFC-12 (CCIF ₂ ) Ecoleace 134a (trade name:
(Showa Denko) was used. The pure content is 99.99% or more, including the isomer 1,1,2,2-tetrafluoroethane,
No chlorine-containing compounds are detected.

[Pentafluoroethane] HCFC
Pentafluoroethane (CF ₃ CHF ₂ ) Ecoloace 125 (trade name, manufactured by Showa Denko) supplied as a substitute for -22 (CHClF ₂ ) was used. The pure content is 99.
95% or more, CF ₃ CH ₂ F, CF ₃ C
Chloropentafluoroethane as H ₃ and chlorine-containing compounds (CF ₃ CClF _2), contains a 1-chloro-1,2,2,2-tetrafluoroethane (CHClFCF _3).

Example 1 FIG. 1 is a diagram showing a flow of a method for producing perfluorocarbon according to the present invention. As the hydrofluorocarbon (symbol 12 in the figure), the above-mentioned trifluoromethane and fluorine gas (symbol 11 in the figure) are mixed with a diluent gas (symbol 19 in the figure) to form a mixed gas (symbol 1 in the figure).
3) was introduced into the first reaction zone (reference numeral 1 in the figure). The first reaction zone has a reaction pressure of 1.5 MPa, a reaction temperature of 400 ° C., and F ₂ /
The reaction was carried out under the conditions of a molar ratio of trifluoromethane = 1.51 and an inlet concentration of trifluoromethane of 2.1 mol%,
An outlet gas (reference numeral 14 in the figure) of the first reaction zone was obtained.

As a new hydrofluorocarbon (symbol 16 in the figure), 1,1,1,2-tetrafluoroethane and fluorine gas (symbol 15 in the figure) are mixed with the outlet gas to form a mixed gas (symbol 17 in the figure). Was introduced into the second reaction zone (symbol 2 in the figure). The second reaction zone has a reaction pressure of 1.5 MPa,
Reaction temperature 370 ° C., molar ratio of F ₂ /1,1,1,2-tetrafluoroethane=2.06 and 1,1,1,2-
The reaction was carried out under the conditions of an inlet concentration of tetrafluoroethane of 1.35 mol% to obtain an outlet gas (reference numeral 18 in the figure) of the second reaction zone. The outlet gas was divided into a diluent gas (19 in the figure) and a gas (20 in the figure) led to the distillation and purification steps. Table 1 shows the results. The numbers in the table are the numbers in FIG.

[Example 2] Hydrofluorocarbon (reference numeral 12 in the figure) was manufactured in the same manufacturing method flow as in Example 1.
Pentafluoroethane and fluorine gas (1 in the figure)
1) was mixed with a diluent gas (19 in the figure), and a mixed gas (13 in the figure) was introduced into the first reaction zone (1 in the figure).
The first reaction zone has a reaction pressure of 1.5 MPa and a reaction temperature of 370.
The reaction was carried out under the conditions of ° C., a molar ratio of F ₂ /pentafluoroethane=1.47 and an inlet concentration of pentafluoroethane of 3.2 mol%, and an outlet gas in the first reaction zone (reference numeral 14 in the figure)
I got

The outlet gas is mixed with difluoromethane and fluorine gas (reference numeral 15 in the figure) as new hydrofluorocarbons (reference numeral 16 in the figure) to form a mixed gas (reference number 1 in the figure).
7) was introduced into the second reaction zone (reference numeral 2 in the figure). In the second reaction zone, the reaction pressure was 1.5 MPa, the reaction temperature was 350 ° C., and F ₂ /
The reaction was carried out under the conditions of a molar ratio of difluoromethane = 2.01 and an inlet concentration of difluoromethane of 2.05 mol% to obtain an outlet gas (reference numeral 18 in the drawing) of the second reaction zone. The outlet gas was separated into a diluent gas (19 in the figure) and a gas (20 in the figure) guided to the distillation and purification steps. Table 2 shows the results.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

The method for producing perfluorocarbon of the present invention can provide a method for producing perfluorocarbon which is industrially safe, efficient and economical.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a flow of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st reaction zone 2 2nd reaction zone 3 Distillation and purification process 11 Fluorine gas supplied to 1st reaction zone 12 Hydrofluorocarbon supplied to 1st reaction zone 13 Gas component supplied to 1st reaction zone 14th One reaction zone outlet gas component 15 Fluorine gas supplied to the second reaction zone 16 Hydrofluorocarbon supplied to the second reaction zone 17 Gas component supplied to the second reaction zone 18 Second reaction zone outlet gas component 19 Diluent gas 20 Gases led to distillation and purification processes

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Oi 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko KK Kawasaki Plant (56) References JP-A 1-180838 (JP, A) 60-109533 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 17/10 C07C 19/08

Claims (14)

(57) [Claims] 1. A gas produced by contacting hydrofluorocarbon and fluorine gas in a gaseous phase at an elevated reaction temperature in a first reaction zone is led to a second reaction zone as a diluting gas, and the second reaction zone is produced. In the method for producing perfluorocarbon, a hydrofluorocarbon different from the first reaction zone and a fluorine gas, if necessary, are supplied and brought into contact at an elevated reaction temperature. 2. The method according to claim 1, wherein at least a part of the product gas in the second reaction zone is used as a diluent gas in the first reaction zone. 3. The method according to claim 1, wherein the diluent gas of the first reaction zone and / or the second reaction zone contains at least one of tetrafluoromethane, hexafluoroethane, octafluoropropane and hydrogen fluoride. The production method described in 1. 4. The method according to claim 1, wherein the dilution gas is a component rich in hydrogen fluoride. 5. The production method according to claim 1, wherein the inlet concentration of the hydrofluorocarbon in the first reaction zone and / or the second reaction zone is 8 mol% or less. 6. The reaction temperature of the first reaction zone and / or the second reaction zone is in a temperature range of 200 to 550 ° C.
The production method described in 1. 7. The method according to claim 1, wherein the reaction pressure in the first reaction zone and / or the second reaction zone is in the range of 0 to 5 MPa. 8. The method according to claim 1, wherein two or more kinds of perfluorocarbons are obtained. 9. The obtained perfluorocarbon is at least two kinds selected from tetrafluoromethane, hexafluoroethane and octafluoropropane.
The production method described in 1. 10. The method according to claim 9, wherein the obtained perfluorocarbons are tetrafluoromethane and hexafluoroethane. 11. A hydrofluorocarbon represented by the following general formula (Formula 1): CxHyFz (Formula 1) (where x, y, and z are respectively 1 ≦ x ≦ 3, 1 ≦ y ≦
4, when 1 ≦ z ≦ 7 and x is 1, y + z = 4,
The production method according to claim 1, wherein x is an integer satisfying y + z = 6 when x is 2, and y + z = 8 when x is 3.) 12. The hydrofluorocarbon is at least two members selected from the group consisting of fluoromethane, difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane and heptafluoropropane. The manufacturing method according to claim 11. 13. The method according to claim 13, wherein the hydrofluorocarbon is at least two members selected from the group consisting of difluoromethane, trifluoromethane, tetrafluoroethane and pentafluoroethane. 14. The hydrofluorocarbon having a chlorine-containing compound concentration of 2 mol% or less as an impurity contained in the hydrofluorocarbon.
2. The production method according to 1.