Method for purifying octafluoropropane

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying octafluoropropane. Method is carried out by interaction of crude octafluoropropane comprising impurities with the impurity-decomposing agent at increased temperature and then with adsorbent that are able to remove indicated impurities up to the content less 0.0001 wt.-% from indicated crude octafluoropropane. The impurity-decomposing agent comprises ferric (III) oxide and compound of alkaline-earth metal in the amount from 5 to 40 wt.-% of ferric oxide and from 60 to 95 wt.-% of compound of alkaline-earth metal as measured for the complete mass of the impurity-decomposing agent. Ferric (III) oxide represents γ-form of iron hydroxyoxide and/or γ-form of ferric (III) oxide. Impurities represent at least one compound taken among the group consisting of chloropentafluoroethane, hexafluoropropene, chlorotrifluoromethane, dichlorodifluoromethane and chlorodifluoromethane. Adsorbent represents at least one substance taken among the group consisting of activated coal, molecular sieves and carbon molecular sieves. Crude octafluoropropane comprises indicated impurities in the amount from 10 to 10 000 mole fr. by mass. Invention proposes gas, etching gas and purifying gas comprising octafluoropropane with purity degree 99.9999 wt.-% and above and containing chlorine compound in the concentration less 0.0001 wt.-%. Invention provides enhancing purity of octafluoropropane.

EFFECT: improved purifying method.

13 cl, 11 tbl, 12 ex

 

This application is filed under 35 U.S.. §111 (a) with the use of priority in accordance with 35 U.S.. §119 (e) (1) the filing date of the provisional application 60/264,320, filed January 29, 2001, in accordance with 35 U.S. §111(b).

The technical FIELD

The present invention relates to a method of cleaning OCTAFLUOROPROPANE, the method of producing OCTAFLUOROPROPANE high purity, OCTAFLUOROPROPANE high purity and its application.

The LEVEL of TECHNOLOGY

Up to the present time in the production process of semiconductor devices used gas etching to partially remove material thin film to form a topology schema on different materials, thin films, which consist of semiconductor circuits, and at the same time to remove the deposits used cleaning gas to get rid of the source materials for thin films, deposited in the reactor in the process of formation of a thin film. One of the etching gas or a cleaning gas, commonly used in the manufacturing process of semiconductor devices, is OCTAFLUOROPROPANE (hereinafter referred to as "FC-218").

On the other hand, given the General trends improve performance, reduce size, increase the density of electrical or electronic equipment, structure topologies schemes becomes thinner, and for education the project for a topology schema during etching with high accuracy requires the use of an etching gas of high purity, from which the extracted impurities as possible. If the etching gas that contains the impurity, even in very small quantities, it can cause an increase in the width of lines in the process of formation of the fine structure topology and to increase the number of defects of the product containing an integrated circuit of high density.

Later in the process of removing sediments using gas purifying the amount of residual impurities in the manufacturing process of semiconductor devices after cleaning should be as low as possible to provide a device of high quality and purity, this requires a cleaning gas of high purity, essentially not containing impurities.

As for ways to get FC-218, it is known, for example, a method of electrolytic fluorination of 1-chloropropane (see patent US 3709800), the mode of interaction of cryptococcaceae with manganese TRIFLUORIDE (see patent US 2578721) and the mode of interaction of fluoride and chlorine with such gases as propane and propylene (see patent US 5220083). However, in these methods as starting substances use of chlorine-containing compounds and, therefore, as a by-product also receive compounds containing chlorine that fall in FC-218 as impurities.

On the other hand, known methods for producing FC-218 using the original the substances, not containing chlorine, for example, a method of electrolytic fluorination of propane (see patent US 3840445). However, for the industrial production of these methods are disadvantageous because of the high complexity of the hardware implementation and low output.

In addition, there is a method of fluorination of geksaftorpropena (hereinafter sometimes referred to as "FC-1216") to obtain the FC-218. For example, there is a method of interaction of FC-1216 with gaseous fluorine when diluted with an inert gas and a gaseous target product (used herein, the term "JP-a" means the publication of the Japanese application, the examined), the method of electrolytic fluorination FC-1216 fluoride (see JP-B-62-61115) and the way of interaction of at least one fluoride polyvalent metal selected from cobalt TRIFLUORIDE, manganese TRIFLUORIDE, and diferida fluoride polyvalent metal selected from cobalt TRIFLUORIDE, manganese TRIFLUORIDE, and diferida silver, FC-1216 (see JP-B-62-54777).

In this case, to obtain the FC-1216 known, for example, a process involving thermal decomposition of Chlorodifluoromethane (hereinafter sometimes referred to as "HCFC-22"), and the method including fluoridation perhalogenated chlorofluorocarbon containing up to 3 carbon atoms, with the subsequent dihalogenoalkane fluorinated product with the receipt of FC-1216 (see patent S 5057634).

However, these methods are also commonly used as starting compounds chlorinated compounds and therefore in the resulting FC-1216, usually present as impurities compounds containing chlorine. In the FC-218, obtained from the FC-1216, contains chlorinated compounds together with unreacted FC-1216.

Thus, these chlorine-containing and fluorocarbon impurities such as FC-1216, should be removed from FC-218.

For example, attempts have been made separation of these impurities from FC-218 by distillation or similar processes. More specifically, impurities contained in FC-218, it is theoretically possible to remove by distillation, if they have a boiling point different from the boiling point of FC-218. However, as shown below in Table 1, CHLOROPENTAFLUOROETHANE (hereinafter sometimes referred to as "CFC-115"), FC-1216, DICHLORODIFLUOROMETHANE (hereinafter sometimes referred to as "CFC-12") and HCFC-22, which are often present in the mixture as impurities, have a boiling point close to the boiling point of FC-218. Therefore, it is very difficult to separate these impurities by distillation and obtain FC-218 high purity.

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Table 1
Connection nameThe structural formulaBoiling point (°)
OCTAFLUOROPROPANE (FC-218)CF3CF3CF3-36.7
CHLOROPENTAFLUOROETHANE (CFC-115)CClF2CF3-38.7
Hexaferrite (FC-1216)CF3CF=CF2-31
DICHLORODIFLUOROMETHANE (CFC-12)CCl2F2-29.8
Chlorodifluoromethane (HCFC-22)CHClF2-41

Therefore, attempts are being made to use other methods of purification, in addition to separation by distillation, such as extractive distillation, membrane separation and adsorption branch.

However, the problem method of extractive distillation is the need of expensive equipment, and the process itself is quite complex. The problem of the method of membrane separation is not known suitable and convenient membrane having the properties necessary for the Department FC-218 from impurities, and it is difficult to clean to a high degree of purity, for example, that the content of impurities in FC-218 was 1 M. D. (million share) by weight or less.

In addition, as shown in Table 2, there are almost no differences in the size of the molecules (calculated value at a stable structural condition) between FC-218 and CFC-115 or FC-1216, and no differences in t is mperature boiling between FC-218 and impurities, ie FC-218 and impurities have a similar structure and physical properties. Thus, it is impossible to clean to a high degree of purity by removing impurities using the adsorption branch using the known adsorbents such as activated carbon, silica gel, zeolite (molecular sieve) and carbon molecular sieve (hereinafter referred to as "MSC").

Table 2
Connection nameThe size of the molecule (calculated value)
OCTAFLUOROPROPANE (FC-218)from 4.9 to 6.1
CHLOROPENTAFLUOROETHANE (CFC-115)from 4.3 to 5.6
Hexaferrite (FC-1216)from 4.9 to 5.9

Among these compounds FC-1216 is one of the impurities which can be removed by adsorption using activated carbon or MSC, but such chlorine-containing compounds as CFC-115, can not be separated.

Thus, using conventional cleaning methods, it is difficult to get FC-218 high purity by reducing the concentration of fluorocarbon impurities, including chlorine compounds, as CFC-115, to values less than 1 ppm by mass.

In resultativity deep research in order to solve these problems, the authors of the present invention have found, what if the crude OCTAFLUOROPROPANE containing impurities such as chlorine compounds, is brought into contact with the agent, corrosive impurities containing iron oxide and a compound of alkaline earth metal, and then with an adsorbent, these impurities can easily be essentially removed.

More specifically, the present invention has developed a method of purification of FC-218, in which FC-218, containing fluorocarbon impurities as CFC-115, FC-1216, CFC-12, CFC-13 (CHLOROTRIFLUOROMETHANE) and HCFC-22, at a concentration of from 10 to 10,000 ppm by weight of lead in contact with the agent, corrosive impurities, and then with an adsorbent, and as a result, the content of these impurities can be reduced to less than 1 ppm by weight. The present invention was created on the basis of this development.

The PURPOSE of the INVENTION

The aim of the present invention is to solve the above problems existing in the art, and the creation of a method of cleaning OCTAFLUOROPROPANE, with which you can essentially remove impurities from the crude OCTAFLUOROPROPANE containing impurities.

Another objective of the present invention is to provide a method for obtaining OCTAFLUOROPROPANE, including the above-described stage of cleaning and OCTAFLUOROPROPANE high purity and its application.

The INVENTION

The way to clean OCTAFLUOROPROPANE in accordance with this is Subramaniam differs that crude OCTAFLUOROPROPANE containing impurities is brought into contact with the agent, corrosive impurities at elevated temperature (heating), and then with an adsorbent to essentially remove impurities from the crude OCTAFLUOROPROPANE.

Agent, demoralizing impurities, preferably includes iron oxide and the compound of alkaline earth metal.

The iron oxide is preferably an oxide of iron (III)and iron oxide (III) is preferably γ-hydroxyacid iron and/or γ-iron oxide (III).

Connection alkaline earth metal preferably represents at least one compound selected from the group consisting of oxides, hydroxides and carbonates of alkaline earth metals magnesium, calcium, strontium or barium.

Agent, demoralizing impurities, preferably contains from 5 to 40% by weight of iron oxide and from 60 to 95% by weight of compounds of alkaline earth metal, based on total weight of the agent, present and degrades impurities.

Agent, demoralizing impurities, is preferably in the form of granules, comprising a powder of iron oxide with an average particle size of 100 μm or less and powder compounds of the alkaline earth metal with an average particle size of 100 μm or less.

Agent, demoralizing impurities, is preferably in the form of granules with an average the particle size from 0.5 to 10 mm

The crude OCTAFLUOROPROPANE preferably brought into contact with the agent, corrosive impurities, at a temperature of from 250 to 380°C.

The adsorbent preferably represents at least one substance selected from the group consisting of activated carbon, molecular sieves and carbon molecular sieves.

The crude OCTAFLUOROPROPANE may contain impurities in an amount of from 10 to 10,000 ppm by mass.

The admixture preferably represents at least one compound selected from the group consisting of CHLOROPENTAFLUOROETHANE, hexaferrite, CHLOROTRIFLUOROMETHANE, DICHLORODIFLUOROMETHANE and Chlorodifluoromethane.

After impurities are being removed, the concentration of impurities remaining in OCTAFLUOROPROPANE, may be less than 1 ppm by mass.

The method of producing OCTAFLUOROPROPANE in accordance with the present invention differs in that it includes a stage of obtaining the crude OCTAFLUOROPROPANE containing impurities, and bring the specified crude OCTAFLUOROPROPANE in contact with the agent, corrosive impurities by heating, and then the adsorbent, with the receipt of OCTAFLUOROPROPANE, from which pollutants are being removed.

The stage of obtaining the crude OCTAFLUOROPROPANE containing impurities, can be a fluoridation of hexaferrite. In addition, note the camping can represent at least one connection, selected from the group consisting of CHLOROPENTAFLUOROETHANE, hexaferrite, CHLOROTRIFLUOROMETHANE, DICHLORODIFLUOROMETHANE and Chlorodifluoromethane.

OCTAFLUOROPROPANE in accordance with the present invention differs in that it contains less than 0.0001% by weight of chlorine and has a purity of 99.9999% by mass or more.

Gas in accordance with the present invention differs in that it contains the above OCTAFLUOROPROPANE.

Etching gas in accordance with the present invention differs in that it contains the above-described gas.

The cleaning gas in accordance with the present invention differs in that it contains the above-described gas.

DETAILED description of the INVENTION

[Purification method]

The way to clean OCTAFLUOROPROPANE in accordance with the present invention includes a step of bringing the crude OCTAFLUOROPROPANE containing impurities in contact with the agent, corrosive impurities, when heated (high temperature), and then with an adsorbent to essentially remove impurities from the crude OCTAFLUOROPROPANE. This method of purification described below in detail.

"Crude OCTAFLUOROPROPANE", as used in the present invention, refers to OCTAFLUOROPROPANE containing impurities, which has not passed the stage of cleaning of the present invention. "Essentially removed", as used here, oboznachaet is, that there's absolutely no or almost no impurities.

Agent, demoralizing impurities

In the present invention preferably use an agent, demoralizing impurities comprising iron oxide and a compound of alkaline earth metal.

Examples of oxides include iron oxide (II) and iron oxide (III). Among them, preferred are oxides of iron (III). Among the oxides of iron (III) are preferred γ-FeOOH (γ-hydroxyacid iron) and γ-Fe2About3(γ-iron oxide (III)), a γ-FeOOH is the most preferred.

These oxides can be used alone or in combination with other oxides of iron.

It is believed that the reason γ-FeOOH and γ-Fe2About3are preferred compared to α-Fe2About3associated with the activity of iron oxides. γ-FeOOH and γ-Fe2About3have a higher reactivity and activity in relation to the chlorine compounds decreases in the following order γ-FeOOH > γ-Fe2O3> α-FeOOH > Fe2About3>> α-Fe2About3. It is assumed that this difference in activity relative to the chlorine compounds is due to the fact that the binding energy between the atoms of iron and oxygen in γ- FeOOH or γ-Fe2About3lower than in α-FeOOH.

Connection deliciosum the high metal used in the present invention, is preferably a hydroxide, oxide or carbonate of alkaline earth metal. Examples of alkaline earth metals include magnesium, calcium, strontium and barium.

Among these compounds, alkaline earth metals, preferably using a hydroxide or calcium oxide, and calcium hydroxide is the most preferred. These compounds are alkaline earth metals can be used alone or in combination with other compounds of alkaline earth metals.

Agent, demoralizing impurities used in the present invention preferably contains iron oxide and the compound of alkaline earth metal in the same proportion that the amount of iron oxide is from 5 to 40% by weight, preferably from 20 to 30 mass%, and the number of connections alkaline earth metal is from 60 to 95% by weight, preferably from 70 to 80% by weight, respectively, based on the total weight of the agent, present and degrades impurities.

It is assumed that, if the amount of iron oxide and compounds of the alkaline earth metal contained in the agent, corrupting impurities, is in the above range, it is possible to effectively carry out the decomposition of impurities and to remove decomposition products as described below, while effective treatment is due to the COI is whether the distinctive properties of iron oxide and compounds of alkali-earth metal.

Agent, demoralizing impurities may be in any form, without particular limitation, but it is preferable that he was in the form of particles. When the iron oxide and the compound of the alkali earth metal is in the form of particles, the average size of these particles prior to their mixing, i.e. before formation agent, present and degrades impurities, is preferably 100 μm or less, more preferably 10 μm or less, more preferably 1 μm or less. The average particle size is preferably from 0.01 to 100 μm, more preferably from 0.01 to 10 μm, more preferably from 0.01 to 1 μm.

If the average size of each particle of iron oxide and compounds of the alkali earth metal is 100 μm or less, you can get OCTAFLUOROPROPANE a higher degree of purity, and also to carry out more effective cleaning. This, presumably, is because the iron oxide and the compound of alkaline earth metal in the form of fine particles have an increased specific surface area and is easily mixed with each other, as a result of increasing the surface area of the iron oxide and compounds of alkali-earth metal, and the possibility of contact of the crude OCTAFLUOROPROPANE agent, corrosive impurities.

The concentration and type of impurities in the iron oxide and the compound of alkaline earth metal, n is of major importance, if they do not affect the ability of the decomposition of impurities in the raw OCTAFLUOROPROPANE.

Agent, demoralizing impurities may be in any form, without particular limitations, and any shape can be used for cleaning, however, it is preferable that the agent, demoralizing impurities, was in the form of granules or particles. Specific examples of the forms of these granules include tablet shape and a spherical shape. The average size of the individual granules is preferably from 0.5 to 10 mm, more preferably from 1 to 5 mm

If the average size of the individual granules is in the above range, increases the possibility of contact of the contaminants with the agent, corrosive impurities, and can effectively carry out the decomposition and removal of these impurities. If the average particle size of the agent is present and degrades impurities exceeds 10 mm, the surface area involved in the adsorption and diffusion of gas decreases accordingly, and sometimes decreases the diffusion rate. On the other hand, if the average particle size of the agent is present and degrades impurities is less than 0.5 mm, the surface area involved in the adsorption and diffusion, respectively is increased, although the diffusion rate could also be increased, sometimes there is a strong pressure drop.

To obtain agent, present and degrades impurities, comprising OK the ID of iron and connection alkaline earth metal, mix the powder of iron oxide and powder of the compound of alkaline earth metal and get an agent, demoralizing impurities, by any method without limitation. The production of pellets (pellet), unless the mixing ratio is within the above range, a successful granulation can be accomplished by adding to the mixture of the water. If the particle size of iron oxide or compounds of alkali earth metal, more granulation can be performed by adding water and binder. The type and amount of binder does not matter, and you can use any known binder, if only it does not affect the performance of the resulting agent is present and degrades impurities. Examples of inorganic binders include clay and gypsum, and examples of organic binders include methylcellulose, polyvinyl alcohol and starch.

Such granular agent, demoralizing impurities can be obtained by mixing iron oxide and compounds of alkali-earth metal, add appropriate amount of water, mixing this mixture and granulating the mixed mass.

Apparatus for mixing required to obtain such granules can have such a device in which the mixing and granulation m is tenderly carried out simultaneously or these processes can be performed separately. Examples of apparatus for mixing, which mixing and granulation occur at the same time, include a Henschel mixer, vertical mixer. It is also possible to carry out the mixing in a Henschel mixer or the mixer, V-type, and then granulating plate granulator or drum granulator.

Thus obtained granules are preferably dried at a temperature of from 100 to 150°C for 3 to 5 hours in a stream of inert gas, such as air and nitrogen, to increase their stiffness and evaporation of the contained water. The water content of the agent, corrupting impurities, after drying, is considered satisfactory if the weight loss after drying at 110°C for 2-3 hours in an air dryer is 1% by mass or less.

It is assumed that when using this agent, present and degrades impurities, such impurities in the raw OCTAFLUOROPROPANE as fluorocarbons, interact with the connection alkaline earth metal in the composition of the agent, present and degrades impurities, and due to this decay. More specifically, a mixture of CFC-115 interacts with the hydroxide, oxide or carbonate of the alkaline earth metal in the composition of the agent, present and degrades impurities, with the receipt of fluoride and chloride of the alkali earth metal and simultaneous formation of carbon monoxide, water and the like. Monoxide in the of Lerida and water, formed during this reaction, undergo further interaction with the use of iron as a catalyst to produce hydrogen or methane. It is assumed that these reactions take place continuously, with chlorine in the composition of CFC-115 is replaced with the separated hydrogen with obtaining Pentafluoroethane (hereinafter sometimes referred to as "HFC-125"). By the same reaction mechanism of CFC-115 is formed FC-1114. More specifically, it is assumed that of CFC-115 is obtained HFC-125, a result of detachment from the HFC-125 HF is formed FC-1114. These formed fluorocarbons size of the molecule is less than that of CFC-115 (size molecules: from 4.3 to 5.6). For example, the size of a molecule of HFC-125 is from 3.4 to 4.9and the size of the molecule FC-1114 ranges from 3.5 to 4.9. The difference in the sizes of molecules between OCTAFLUOROPROPANE (from 4.9 to 6.1) and HFC-125, as such, becomes significant compared to the difference in the sizes of molecules between OCTAFLUOROPROPANE and CFC-115, suggesting that these impurities can be easily removed by contact with an adsorbent after contact with the agent, corrosive impurities. In this case, OCTAFLUOROPROPANE is a relatively stable compound and therefore does not degrade upon contact with the agent, corrosive impurities, when heated to t is mperature from 250 to 380° C.

The adsorbent

In the purification method of the present invention after contact with the agent, corrosive impurities at elevated temperature the crude OCTAFLUOROPROPANE then lead into contact with the adsorbent.

Here it is possible to use any known adsorbent. Examples of adsorbents which can be used preferably include activated carbon, zeolite (molecular sieve) and carbon molecular sieves. Activated charcoal or carbon molecular sieves before use can be subjected to preliminary treatment such as acid treatment, heat treatment or steam treatment.

Among these preferred adsorbents are molecular sieves with pore size of 4 to 7and carbon molecular sieves, and the most preferred are carbon molecular sieves 5.

The adsorbent may be a commercially available product.

These adsorbents may be used alone or in combination with other adsorbents.

The method of purification of the crude OCTAFLUOROPROPANE

The way to clean OCTAFLUOROPROPANE in accordance with the present invention includes a step of bringing the crude OCTAFLUOROPROPANE containing impurities in contact with the agent, corrosive impurities at elevated temperature is round (heated) (cleaning stage 1) and stage further brought into contact with the adsorbent (cleaning stage 2). The crude OCTAFLUOROPROPANE, which can be used in the present invention may be a product obtained by a known method or a commercially available product.

(Cleaning stage 1)

In the practical implementation of the decomposition reaction of such impurities as fluorocarbons, in the raw OCTAFLUOROPROPANE, agent, present and degrades impurities, for example, are placed in a reactor for the decomposition and served in this reactor, the crude OCTAFLUOROPROPANE for contact with the agent, corrosive impurities. Stage of contact, you can spend any way, without particular limitations, for example, preferably using a flow method in a continuous mode with a fixed layer.

As to the reaction pressure, the reaction can be carried out both under pressure, and without it, and usually the treatment is carried out under pressure, which is easy to create, but preferably the reaction is carried out under pressure, i.e. there is due to excessive pressure, which ranges from 0 to 2 MPa, more preferably from 0 to 1 MPa.

The size (volume) of the reactor for the decomposition and the volumetric rate can be anything, if only crude OCTAFLUOROPROPANE and agent, demoralizing impurities can be in contact within a specified period of time, but preferably, they are selected so that the residence time of neoch the seal OCTAFLUOROPROPANE in the reactor for the decomposition ranged from 1 to 30 seconds, more preferably from 4 to 30 seconds.

The temperature of the decomposition reaction in the reactor for the decomposition is preferably from 250 to 380°S, more preferably from 280 to 360°C. If the temperature of the decomposition reaction is in this interval, the agent, demoralizing impurities, can retain its activity. If the temperature of the decomposition reaction is less than 250°C, the activity of the agent is present and degrades impurities, does not develop and the rate of decomposition is reduced, and if the temperature of the decomposition reaction exceeds 380°With the agent, demoralizing impurities, he is destroyed by heating and decomposition of impurities in the raw OCTAFLUOROPROPANE may be terminated.

(Cleaning stage 2)

After the cleanup phase 1 impurities are then put in contact with the adsorbent, it basically is deleting them, so you can get OCTAFLUOROPROPANE a high degree of purity.

The process of adsorption can be accomplished, for example, by filling the adsorption column adsorbent and passing through her crude OCTAFLUOROPROPANE after decomposition reaction. In this case, the process of adsorption can be hold by any known method without limitation, for example, preferably using a flow method in a continuous mode with a fixed layer.

To contact the crude OCTAFLUOROPROPANE, proseds what about the purification stage 1, with the adsorbent can be used in gas phase or liquid phase. The linear velocity in the case of gas-phase contact method is preferably from 1 to 10 m/min, more preferably from 1 to 5 m/min, and in the case of liquid-phase contact method preferably from 0.2 to 5 m/h, more preferably from 0.5 to 2 m/h.

Treatment can usually be carried out under pressure, which is easy to create, and there is no need to use a special mode, such as the creation of excess pressure. Typically, the pressure is preferably from 0 to 2 MPa in the value of the excess pressure.

The temperature in the implementation procedure of adsorption is usually approximately equal to room temperature, and the heating or cooling is not required.

When the adsorption capacity of the adsorbent is completely exhausted, the adsorbent can be regenerated and reused. In this case, regeneration of the adsorbent is carried out by passing through the adsorbent various inert gases such as nitrogen, heated to high temperatures, with the aim desorption OCTAFLUOROPROPANE and such impurities as fluorocarbons.

When the regeneration temperature of the inert gas in the case of the adsorbent on the basis of the zeolite is preferably from 20 to 600°and, in the case of the adsorbent on the basis of activated charcoal or carbon molecular what's Sith preferably from 100 to 400° C.

[Method of producing OCTAFLUOROPROPANE]

In the method of producing OCTAFLUOROPROPANE first get the crude OCTAFLUOROPROPANE, and then it applies the above-described cleaning method. More specifically, after receiving the crude OCTAFLUOROPROPANE carry out the above-described purification stages 1 and 2.

As a method of obtaining the crude OCTAFLUOROPROPANE can be used any known method without limitation. As indicated above, the crude OCTAFLUOROPROPANE can be obtained by a known method, for example, by electrolytic fluorination of 1-chloropropane (see patent US 3709800), through the cooperation of cryptococcaceae with manganese TRIFLUORIDE (see patent US 2578721) or by the interaction of fluoride and chlorine, for example, propane and propylene (see patent US 5220083).

To obtain the crude OCTAFLUOROPROPANE containing impurities, it is possible to use a method of fluorination of hexaferrite. For example, the crude OCTAFLUOROPROPANE can be obtained by the known methods such as a method of interaction of FC-1216 and gaseous fluorine when diluted with an inert gas and gaseous reaction product, the method of electrolytic fluorination FC-1216 fluoride (see JP-B-62-61115) and the method of interaction of at least one fluoride polyvalent metal selected from cobalt TRIFLUORIDE, manganese TRIFLUORIDE is diferida silver with FC-1216 (see JP-B-62-54777).

Thus obtained crude OCTAFLUOROPROPANE passes above the cleanup phase 1 and 2, it is possible to obtain OCTAFLUOROPROPANE, from which pollutants are being removed.

[OCTAFLUOROPROPANE high purity]

Using the purification method of the present invention, can be effectively removed from the crude OCTAFLUOROPROPANE impurities such as fluorocarbons, particularly CHLOROPENTAFLUOROETHANE (CFC-115), hexaferrite (FC-1216), DICHLORODIFLUOROMETHANE (CFC-12), CHLOROTRIFLUOROMETHANE (CFC-13) and Chlorodifluoromethane (HCFC-22). In particular, it is possible essentially to remove impurities, which represents a chlorine compounds, which are difficult to remove using conventional cleaning methods, such as CFC-115, CFC-12, CFC-13 and HCFC-22, and get OCTAFLUOROPROPANE a high degree of purity.

The above impurities normally contained in the raw OCTAFLUOROPROPANE in the range from 10 to 10000 ppm by weight, and when using the cleaning method of the present invention, these impurities contained in OCTAFLUOROPROPANE, you can remove content less than 1 ppm by weight (0.0001% by mass), and the purity of OCTAFLUOROPROPANE obtained after purification, can reach 99.9999% by mass or more.

In this case, the purity of OCTAFLUOROPROPANE defined as the value obtained by subtracting the content of other fluorocarbons than OCTAFLUOROPROPANE, from 100% by weight. EN is Liz received OCTAFLUOROPROPANE with a purity of 99.9999% by mass or more can be realized by using (1) gas chromatography (GC), using the method TCD detector (thermal conductivity), the method FID detector (flame ionization) (including in each case, the method pre-shutdown) or ECD method (detector electron capture) and (2) gas chromatography and mass spectrometer (GC-MS).

[Application]

When impurities are essentially removed, OCTAFLUOROPROPANE obtained by the method according to the present invention, can be used as the etching gas phase etching in semiconductor devices.

More specifically, when manufacturing such semiconductor devices, such as LSI (large integrated circuit (LSI)and TFT (thin film transistor), OCTAFLUOROPROPANE usually used as etching gas to form a topology diagram of the thin or thick film obtained by the CVD method (chemical deposition from the gas (vapor) phase), by spraying or vacuum deposition method.

OCTAFLUOROPROPANE can also be used as a cleaning gas in the cleaning stage of a semiconductor device.

More specifically, in the apparatus for production of thin or thick films are cleaned to remove excess sediment that has accumulated on the inner walls of the apparatus and process of the devices, because these deposits can cause the formation of particles and to obtain films of good quality you should delete them. chapterplay in accordance with the present invention is suitable for use with this purpose as a cleaning gas.

Gas in accordance with the present invention includes OCTAFLUOROPROPANE high purity. This gas may be a pure OCTAFLUOROPROPANE or may additionally contain other gases. Examples of these gases include, Ne, Ar, and O2. The amount of these gases for mixing with OCTAFLUOROPROPANE has no special limitation, and in the case of OCTAFLUOROPROPANE high purity in accordance with the present invention as an etching or cleaning gas, the amount of mixed gas varies depending on connection type and thickness protravlivanija layer, and depending on the number and thickness of the removed sediments.

The technical result

In accordance with the methods of cleaning or receive OCTAFLUOROPROPANE of the present invention easily can essentially remove impurities such as chlorine compounds, which are still hardly yielded to remove, and get OCTAFLUOROPROPANE high purity. In addition, OCTAFLUOROPROPANE obtained using the purification method of the present invention are essentially free of impurities, and therefore, it can effectively be used as an etching or cleaning gas for semiconductor devices and the like.

Examples

The present invention is hereinafter described in more detail what about using Examples, however, it should not be construed as limited by these Examples.

[Examples 1-3]

[Crude OCTAFLUOROPROPANE]

OCTAFLUOROPROPANE received through the interaction of FC-1216 with fluoride polyvalent metal.

Of cobalt chloride formed tablets (5 mm × 5 mm) and were ferromoly gaseous HF, and then gaseous F2obtaining F3. 480 g of the obtained F3put in a Nickel reactor (100 mm × 1000 mm) and was introduced there by flowing the method of FC-1216 at the reaction temperature of 270°and atmospheric pressure. The crude OCTAFLUOROPROPANE resulting from the reaction was collected and identified a number of contaminants using gas chromatography. The conditions of the analysis by gas chromatography is shown below.

Hardware: GC-14B (released Shimadzu Seisakusho K.K.)

Media: No

Detector: hydrogen flame ionization detector (FID)

The number of specimen: 0.2 ml

The method of determining the absolute calibration curve method

As a result of analysis obtained in untreated OCTAFLUOROPROPANE were detected following impurities: CFC-115 in the amount of 770 ppm by mass, FC-1216 in the amount of 200 ppm by weight of CFC-13 in the amount of 20 ppm by weight and each of CFC-12 and HCFC-22 in an amount of 10 ppm by mass.

[Preparation tube for the decomposition of impurities]

Agent, demoralizing p is imesi, comprising iron oxide and a compound of alkaline earth metal, was prepared as follows. The components were mixed in the following ratio γ-FeOOH (produced by Ishihara Sangyo)/Ca(OH)2(Yoshizawa Sekkai Kogyo)=30/70% by weight (Example 1), γ-Fe2About3(produced by Toda Kogyo)/Ca(OH)2=20/80% by weight (Example 2) or γ-FH/caso3(produced by Okutama Kogyo)=20/80% by weight (Example 3). After adding water each mixture was granulated, dried at 105°C for 2 hours and sieved to obtain granules with an average particle size of from 0.85 to 2.8 mm. then 1.9 g of each of the agents, decomposing impurities, was placed in a stainless steel tube (reaction tube) with an inner diameter of 16 mm layer height 8 cm (volume 15 ml) and treated by passing nitrogen at 300°C for 3 hours or more with the receiving tube for the decomposition of impurities containing agent, demoralizing impurities.

[Preparation of adsorption column]

MSC-5A (trade name, manufactured Ajinomoto Fine Techno) was used as adsorbent. 71 g MSC-5A as adsorbent was placed in a stainless steel tube with an outer diameter of 1/2 inch (12.7 mm) (parameters adsorption columns: 11 mm (inner diameter) × 150 cm (length of column), volume: 130 ml) and processed by passing nitrogen at 60°C for 1 hour and at 160°during the course the e : 7 hours a total of 8 hours. The adsorption column with adsorbent attached to the end of the tube for the decomposition of impurities, filled with the agent, corrosive impurities.

[Purification of the crude OCTAFLUOROPROPANE]

Prepared previously untreated OCTAFLUOROPROPANE in the gas phase conceded under pressure 0.7 MPa with a bulk velocity of 650 h-1through a tube for the decomposition of impurities and with a linear speed of 1 m/min through the adsorption column. The temperature of the decomposition reaction in the tube for the decomposition of impurities was 350°s OCTAFLUOROPROPANE passing through the tube for the decomposition of impurities, and OCTAFLUOROPROPANE passing through the adsorption column, respectively, were collected and analyzed using gas chromatography under these conditions.

In Example 1, the content of such impurities as fluorocarbons, OCTAFLUOROPROPANE outlet tube for the decomposition of impurities and OCTAFLUOROPROPANE at the outlet of the adsorption column were analyzed after 2 hours, 5 hours and 10 hours after the beginning of its transmission. The results obtained are shown in Table 3.

In the analysis, it was found that fluorocarbon impurities contained in the incoming gas, CFC-115, FC-1216, CFC-12, CFC-13 and HCFC-22 was hardly detected in the exit tube for the decomposition of impurities, but were found HFC-125, FC-1114. Fluorocarbon impurities (decomposed products is I) at the output of the tube to decompose the impurities can be removed by adsorption. Thus, it was found that from OCTAFLUOROPROPANE you can remove CFC-115, FC-1216, CFC-12, CFC-13 and HCFC-22.

Changes in the concentration of CFC-115 contained in OCTAFLUOROPROPANE, at the outlet of the adsorption column after 2 hours and 5 hours after the start of transmission and remote amount of CFC-115 to the point of breakthrough is shown in Table 6. Here breakthrough point is the time when the content found fluorocarbon impurities at the outlet of the adsorption column is 1 ppm by mass and the amount of CFC-115, missed, to the point of breakthrough, is the number of remote CFC-115.

In the case of γ-Fe2About3as iron oxide (III) (Example 2) and caso3as compounds of alkaline earth metal (Example 3) were also obtained excellent results in the destruction of CFC-115, which confirms the possibility of cleaning OCTAFLUOROPROPANE to a high degree of purity.

[Comparative Example 1]

Investigation of the adsorption removal of fluorocarbon impurities from OCTAFLUOROPROPANE carried out by the same procedure as in Example 1, except that was skipped stage of decomposition of the impurities. The impurity concentration before and after passing through the MSC-5A as adsorbent was determined by the same procedure as in Example 1, using gas chromatography.

Change Konz is Tracii fluorocarbon impurities, contained in OCTAFLUOROPROPANE at the outlet of the adsorption column, within 1 hour, 5 hours and 10 hours after the start of transmission of OCTAFLUOROPROPANE shown in Table 4. For CFC-115 the breakthrough point coincides with the beginning of the transmission of OCTAFLUOROPROPANE, which implies CFC-115 is not removed by adsorption only when exposed to the adsorbent. For CFC-12, CFC-13 and HCFC-22 the breakthrough point was also in the range of 5 to 10 hours, suggesting a low efficiency of adsorption.

The number of FC-1216, remote by using the cleaning method of the present invention (Example 1)and the number of FC-1216, remote only due to adsorption treatment (Comparative Example 1)shown in Table 5. Taking as a point of breakthrough moment at the outlet of the adsorption column a certain concentration of FC-1216 in OCTAFLUOROPROPANE is 1 ppm by mass, the amount of FC-1216, missed, to the point of breakthrough, is the remote number. Although from the results of Example 1 and Comparative Example 1, it follows that FC-1216 can be removed by adsorption, unknown, decomposes whether FC-1216, if the stage adsorption conduct stage of decomposition, as in Example 1. However, judging by the remote number FC-1216, it is higher compared to conventional methods adsorption treatment, which confirms the higher efficiency of the purification method according to the present image is the shadow.

Table 4

Changes in the concentration of each of the impurities at the outlet of the adsorption column (Comparative Example 1)
Elapsed time (hour)Changes in the concentration of each impurity (ppm by mass)
CFC-115FC-1216CFC-12CFC-13HCFC-22
The number of sample700200102010
1390000
54870540
10700010155

Table 5

The number of the remote FC-1216
 The number of the remote FC-1216 (mg)
Example 1400
Comparative Example 1210

[Comparative Examples 2-4]

Studies were performed in the same conditions as in Examples 1-3, except for the use of other agents, decomposing impurities.

Used and the coefficients, decomposing impurities, was a γ-FeOOH=100% by weight (Comparative Example 2), γ-Fe2O3=100% by weight (Comparative Example 3) and CA(Oh)2=100% by weight (Comparative Example 4), and through each of these agents, decomposing impurities, missed the same OCTAFLUOROPROPANE as in Examples 1-3. The breakthrough point was taken when the output of the adsorption columns, a certain concentration of fluorocarbon impurities in OCTAFLUOROPROPANE was 1 ppm by mass.

Changing the concentration of CFC-115 contained in OCTAFLUOROPROPANE at the outlet of the adsorption column after 2 hours and 5 hours after the start of transmission of OCTAFLUOROPROPANE, and remote amount of CFC-115 is shown in Table 6.

Agent, demoralizing admixture containing only iron oxide (III) (Comparative Examples 2 and 3) can't save the form, and the potential for this reason, the breakthrough point CFC-115 at the outlet of the adsorption column comes early. The reaction of the decomposition FC-115 hardly flows in the presence of only connections alkaline earth metal (Comparative Example 4), and the remote number FC-115 was very small. From this it follows that, if you do not use an agent, demoralizing admixture containing iron oxide (III)and the compound of alkaline earth metal, mixed in a suitable ratio, CFC-115 is decomposed with difficulty and difficult get the ü good results in his destruction.

Table 6

Changes in the concentration at the outlet of the adsorption column and a remote amount of CFC-115 in each study
 The composition of the agent, impurities present and degradesLast-neck time (hour)Changes in the concentration of FC-115 (ppmRemote number FC-115 (mg)
(mass%) by weight) 
Number  770 
Example 1γ-FeOOH3020 
 CA(Oh)27050705
Example 2γ-Fe2About32020 
 CA(Oh)28050600
Example 3γ-FeOOH2020 
 Caso38050585
Comparative Example 1Only the adsorbent (MSC-5A) 2

5
130

355
10
Comparativeγ-FeOOH100260 
Example 2  523585
Comparativeγ-Fe2About31002100 
Example 3  529540
ComparativeCA(Oh)21002110 
Example 4  535015

[Reference Examples 1 and 2]

Studies were performed in the same conditions as in Example 1, except the temperature of decomposition.

The decomposition temperature was 240°With (Reference Example 1) and 400°With (Reference Example 2).

Changes in the concentration of CFC-115 at the outlet of the adsorption column after 2 hours, 5 hours and 10 hours after the start of transmission of OCTAFLUOROPROPANE shown in Table 7. The results imply that the activity of AG is NTA, present and degrades impurities, is not manifested at a very low temperature 240°and, probably for this reason there was no decomposition of CFC-115. At too high a temperature of 400°With the agent, demoralizing impurities, he collapsed from the heat and the breakthrough point CFC-115 at the outlet of the adsorption column came early. Remote amount of CFC-115 was about 10 mg each of Reference Examples 1 and 2, which is a very low value.

Table 7

Changes in the concentration of CFC-115 at the outlet of the adsorption column, depending on the temperature of decomposition
Elapsed Time (hour)Changes in the concentration of CFC-115 (ppm by mass)
Example 1 (350°)Reference Example 1 (240°)Reference Example 2 (400°)
Number770770770
20350260
50530500
100700700

Additional examples

Example 1

Purification of the crude OCTAFLUOROPROPANE was carried out in the same manner as in Example 1, are given in the description, with the exception of the group, that was used crude OCTAFLUOROPROPANE FC-218, containing CFC-115 in the amount of 1700 ppm by weight instead of 770 ppm by mass, and FC-1216 in the amount of 300 ppm by weight instead of 200 ppm by weight, and the reaction temperature was changed to 300°instead of 350°C. Remote amount of CFC-115 before the concentration of CFC-115 at the exit of the adsorption columns was reduced to 1 ppm, amounted to 690 mg of the Obtained results are shown in Table A.

Example II

Purification of the crude OCTAFLUOROPROPANE was carried out in the same way as in the Example I provided in the description, except that was used crude OCTAFLUOROPROPANE FC-218, containing CFC-115 in the amount of 1700 ppm by weight instead of 770 ppm but the weight and FC-1216 in the amount of 300 ppm by weight instead of 200 ppm by weight. Remote amount of CFC-115 before the concentration of CFC-115 at the exit of the adsorption columns was reduced to 1 ppm, amounted to 780 mg of the Obtained results are shown in Table C.

Example III

Purification of the crude OCTAFLUOROPROPANE was carried out in the same manner as in Example 1, contained in the description, except that was used crude OCTAFLUOROPROPANE FC-218, containing CFC-115 in the amount of 5000 ppm by weight instead of 770 ppm by mass, and FC-1216 in the amount of 300 ppm by weight instead of 200 ppm by weight. Remote amount of CFC-115 before the concentration of CFC-115 at the output of the BPA is blonay columns decreased to 1 ppm, 750 mg of the Obtained results are shown in Table C.

Deleted from OCTAFLUOROPROPANE amount of CFC-115 at the exit of the adsorption column until the concentration of each impurity was reduced to 1, 10 or 100 ppm by weight shown in Table D together with excerpts from Table 6 of the description.

Table And

Changes in the concentration of each impurity at a pipe outlet decomposition of impurities and at the outlet of the adsorption column
 Time (hrs.)Changes in the concentration of each impurity (ppm by mass)
  CFC-115FC-1216CFC-12With FC-13HCFC-22HFC-125FC-1114
The obtained samples 170030010201000
The pipe outlet2000004008
decomposition of impurities50000048020
 1090 000044040
 15700200020020
The outlet of the adsorption column2

5
0

0
0

0
0

0
0

0
0

0
0

0
0

0
1080000500
153000000250

10
The table In

Changes in the concentration of each impurity at a pipe outlet decomposition of impurities and at the outlet of the adsorption column
 Time (hrs.)Changes in the concentration of each impurity (ppm by mass)
  CFC-115FC-1216CFC-12CFC-13HCFC-22HFC-125FC-1114
The obtained samples 1700300201000
The pipe outlet decomposition impurities200000500
5000002903
1023000036022
1568095000255
The outlet of the adsorption column20000000
50000000
1080050000
152700025000

Table

Changes in the concentration of each impurity on you the ode pipes decomposition of impurities and at the outlet of the adsorption column
 Time hour.Changes in the concentration of each impurity (ppm by mass)
  CFC-115FC-1216CFC-12CFC-13HCFC-22HFC-125FC-1114
The obtained samples 500030010201000
The pipe outlet decomposition impurities2000001200
56500006403
10750000075022
15280095000705
Output adsorbtion Noi columns20000000
538000060 0
1065000002500
1525500000700

Table D

Fixed amount of CFC-217ba in each example
 The composition of the agent, present and degrades the impurity (wt. %)Fixed number FC-115(mg) *1Fixed number FC-115(mg) *2Fixed number FC-115(mg) *3
Example 1γ-FeOOH CA(Oh)230

70
7057801310
Example 2γ-Fe2O3CA(Oh)220

80
6006601130
Example 3γ-FeOOH, caso320

80
5856401050
Comparative example 1Only the adsorbent (MSC-5A) 101118
Comparative example 2γ-FeOOH1008595 120
Comparative example 3γ-Fe2O3100404468
Comparative

example 4
CA(Oh)2100151618
Example Iγ-FeOOH CA(Oh)230

70
6908601173
Example IIγ-FeOOH CA(Oh)230

70
7808501250
Example IIIγ-FeOOH CA(Oh)230

70
750820890
*1 End when 1 h/MLP weight

*2 End if 10 ppm by mass

*3 Complete at 100 ppm by mass

1. The way to clean OCTAFLUOROPROPANE, comprising a stage of bringing the crude OCTAFLUOROPROPANE containing impurities in contact with the corrosive impurities agent at elevated temperature, and then with an adsorbent that can remove these impurities content of less than 0,0001%by weight, from the specified raw OCTAFLUOROPROPANE, and specified demoralizing impurities agent comprises iron oxide (III) and the compound of alkaline earth metal, these impurities not only is jut a, at least one compound selected from the group consisting of CHLOROPENTAFLUOROETHANE, hexaferrite, CHLOROTRIFLUOROMETHANE, DICHLORODIFLUOROMETHANE and Chlorodifluoromethane.

2. The way to clean OCTAFLUOROPROPANE according to claim 1, characterized in that the iron oxide (III) is a γ-hydroxyacid iron and/or γ-iron oxide (III).

3. The way to clean OCTAFLUOROPROPANE according to claim 1 or 2, characterized in that the specified connection alkaline earth metal is at least one compound selected from the group consisting of oxides, hydroxides and carbonates of alkaline earth metals magnesium, calcium, strontium and barium.

4. The way to clean OCTAFLUOROPROPANE according to claims 1 to 3, characterized in that the specified demoralizing impurities agent contains from 5 to 40% by weight of iron oxide and from 60 to 95% by weight of compounds of alkaline earth metal, based on total weight of impurities present and degrades agent.

5. The way to clean OCTAFLUOROPROPANE according to claims 1 to 4, characterized in that the specified demoralizing impurities agent represents granules comprising the powder of the specified iron oxide with an average particle size of 100 μm or less, and the powder of the compounds of the alkaline earth metal with an average particle size of 100 μm or less.

6. The way to clean OCTAFLUOROPROPANE according to claims 1 to 5, characterized in that the specified razloga the speaker impurities agent represents granules with an average particle size of from 0.5 to 10 mm

7. The way to clean OCTAFLUOROPROPANE according to any one of claims 1 to 6, characterized in that the adsorbent is at least one substance selected from the group consisting of activated carbon, molecular sieves and carbon molecular sieves.

8. The way to clean OCTAFLUOROPROPANE according to claims 1 to 7, characterized in that the crude OCTAFLUOROPROPANE contains the impurity in an amount of from 10 to 10,000 ppm by mass.

9. The way to clean OCTAFLUOROPROPANE according to claim 1, characterized in that after the admixture is essentially removed, the concentration of impurities remaining in OCTAFLUOROPROPANE is less than 1 ppm by mass.

10. The way to clean OCTAFLUOROPROPANE according to claim 1, characterized in that OCTAFLUOROPROPANE with purity 99,9999 wt.% or more and containing less than 0,0001% by weight chlorine compounds.

11. Gas, including OCTAFLUOROPROPANE with purity 99,9999 wt.% or more and containing less than 0,0001% by weight chlorine compounds.

12. Etching gas including OCTAFLUOROPROPANE with purity 99,9999 wt.% or more and containing less than 0,0001% by weight chlorine compounds.

13. Purifying gas comprising OCTAFLUOROPROPANE with purity 99,9999 wt.% or more and containing less than 0,0001% by weight chlorine compounds.



 

Same patents:

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying octafluorocyclobutane. Method is carried out by interaction of crude octafluorocyclobutane containing impurities with the impurity-decomposing agent at increased temperature and then with adsorbent that is able to eliminate indicated impurities up to the content less 0.0001 wt.-% from the mentioned crude octafluorocyclobutane. Impurity-decomposing agent comprises ferric (III) oxide and compound of alkaline-earth metal in the amount from 5 to 40 wt.-% of ferric oxide and from 60 to 95 wt.-% of compound of alkaline-earth metal as measured for the complete mass of the impurity-decomposing agent. Ferric (III) oxide represents γ-form of iron hydroxyoxide and/or γ-form of ferric (III) oxide. Impurity represents at least one fluorocarbon taken among the group consisting of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,2,2,2-tetrafluoroethane, 1-chloro-1,1,2,2-tetrafluoroethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane, hexafluoropropene and 1H-heptafluoropropane. Adsorbent represents at least one of representatives taken among the group including activated carbon, carbon molecular sieves and activated coal. Crude octafluorocyclobutane interacts with the mentioned impurity-decomposing agent at temperature from 250oC to 380oC. Invention proposes gas, etching gas and purifying gas including octafluorocyclobutane with purity degree 99.9999 wt.-% and above and comprising fluorocarbon impurity in the concentration less 0.0001 wt.-%. Invention provides enhancing purity of octafluorocyclobutane.

EFFECT: improved purifying method.

26 cl, 13 tbl, 10 ex

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EFFECT: improved preparing method.

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FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying octafluorocyclobutane. Method is carried out by interaction of crude octafluorocyclobutane containing impurities with the impurity-decomposing agent at increased temperature and then with adsorbent that is able to eliminate indicated impurities up to the content less 0.0001 wt.-% from the mentioned crude octafluorocyclobutane. Impurity-decomposing agent comprises ferric (III) oxide and compound of alkaline-earth metal in the amount from 5 to 40 wt.-% of ferric oxide and from 60 to 95 wt.-% of compound of alkaline-earth metal as measured for the complete mass of the impurity-decomposing agent. Ferric (III) oxide represents γ-form of iron hydroxyoxide and/or γ-form of ferric (III) oxide. Impurity represents at least one fluorocarbon taken among the group consisting of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,2,2,2-tetrafluoroethane, 1-chloro-1,1,2,2-tetrafluoroethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane, hexafluoropropene and 1H-heptafluoropropane. Adsorbent represents at least one of representatives taken among the group including activated carbon, carbon molecular sieves and activated coal. Crude octafluorocyclobutane interacts with the mentioned impurity-decomposing agent at temperature from 250oC to 380oC. Invention proposes gas, etching gas and purifying gas including octafluorocyclobutane with purity degree 99.9999 wt.-% and above and comprising fluorocarbon impurity in the concentration less 0.0001 wt.-%. Invention provides enhancing purity of octafluorocyclobutane.

EFFECT: improved purifying method.

26 cl, 13 tbl, 10 ex

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