Bromofluoroethylene and method for purifying the same, and etching gas

Abstract

To provide a method for purifying bromofluoroethylene capable of removing impurities from bromofluoroethylene.SOLUTION: The method for purifying bromofluoroethylene includes a purification step of bringing bromofluoroethylene containing impurities into contact with an adsorbent having pores and having an average pore diameter of the pores of 3 Å or more and 50 Å or less to adsorb the impurities in the bromofluoroethylene onto the adsorbent to reduce the content of the impurities in the bromofluoroethylene. The impurity is at least one selected from the group consisting of a nitrogen-containing compound which is a compound having a nitrogen atom in a molecule and having a molecular weight of 50 or more, and a carbon-containing compound which is a compound having a carbon atom in a molecule and having a molecular weight of 150 or more. The carbon-containing compound is a compound different from bromofluoroethylene and a compound different from the nitrogen-containing compound.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to bromofluoroethylene and a purification method thereof, and an etching gas. [Background technology]

[0002] Bromofluoroethylene may be used, for example, as a raw material for polymers or as an etching gas for dry etching. Various methods for producing bromofluoroethylene are known, and for example, a method for producing 1-bromo-1,2,2-trifluoroethylene (CF2=CBrF) is known in which 1,2-dibromo-1,1,2-trifluoroethane is dehydrobrominated using a base (see Patent Document 1). Bromofluoroethylene is a compound with insufficient stability, and therefore, there is a risk that bromofluoroethylenes may react with each other to cause self-polymerization reactions, homo-coupling reactions, etc. As a result, there is a risk that self-reaction products such as bromofluoroethylene polymers (e.g., trimers), cyclic polymers, homo-coupling products, etc. may be produced.

[0003] For example, 1-bromo-1,2,2-trifluoroethylene may produce 1,2-dibromo-1,2,3,3,4,4-hexafluorocyclobutane (C4F6Br2) which is a cyclic polymer, or hexafluorobutadiene (CF2=CFCF=CF2) which is a homo-coupling product, or its isomers. As a result, the cyclic polymer or homo-coupling product may be mixed into 1-bromo-1,2,2-trifluoroethylene. In order to suppress such reactions between bromofluoroethylenes, a polymerization inhibitor such as an alkylamine is sometimes added to the bromofluoroethylene. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2006 / 026400 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when bromofluoroethylene is used as an etching gas for dry etching, the above-mentioned self-reaction products such as polymers, cyclic polymers, homo-coupling products, etc., and polymerization inhibitors become impurities, which may damage the etching equipment, reduce the yield due to particle generation, and reduce the etching rate. Therefore, it is desirable to remove these impurities from bromofluoroethylene as much as possible. In particular, tri-n-butylamine used as a polymerization inhibitor is a factor that causes clogging in the etching equipment, so it is desirable to remove it before introducing bromofluoroethylene into the etching equipment.

[0006] An object of the present disclosure is to provide a method for purifying bromofluoroethylene that can remove impurities from bromofluoroethylene. Another object of the present disclosure is to provide high-purity bromofluoroethylene and an etching gas that have a low content of impurities. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present disclosure is as follows [1] to

[13] . [1] A purification process comprising the steps of: bringing bromofluoroethylene containing impurities into contact with an adsorbent having pores with an average pore diameter of 3 Å or more and 50 Å or less; and adsorbing the impurities in the bromofluoroethylene onto the adsorbent to reduce the content of the impurities in the bromofluoroethylene; the impurity is at least one selected from the group consisting of a nitrogen-containing compound which is a compound having a nitrogen atom in its molecule and a molecular weight of 50 or more, and a carbon-containing compound which is a compound having a carbon atom in its molecule and a molecular weight of 150 or more, A method for purifying bromofluoroethylene, wherein the carbon-containing compound is a compound different from the bromofluoroethylene and a compound different from the nitrogen-containing compound.

[0008] [2] The method for purifying bromofluoroethylene according to [1], wherein the nitrogen-containing compound is an alkylamine. [3] The method for purifying bromofluoroethylene according to [2], wherein the alkylamine is at least one of trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, and tri-n-butylamine.

[0009] [4] The method for purifying bromofluoroethylene according to any one of [1] to [3], wherein the carbon-containing compound is at least one selected from the group consisting of a cyclized polymer of the bromofluoroethylene, a homo-coupling product of the bromofluoroethylene, and a polymer of the bromofluoroethylene. [5] The method for purifying bromofluoroethylene according to any one of [1] to [4], wherein the bromofluoroethylene subjected to the purification step has a total content of the impurities of 2 volume % or less.

[0010] [6] The method for purifying bromofluoroethylene according to any one of [1] to [5], wherein the bromofluoroethylene is at least one of 1-bromo-1,2,2-trifluoroethylene, 1-bromo-1-fluoroethylene, 1-bromo-2-fluoroethylene, 1-bromo-1,2-difluoroethylene, and 1-bromo-2,2-difluoroethylene.

[0011] [7] The method for purifying bromofluoroethylene according to any one of [1] to [6], wherein in the purification step, the bromofluoroethylene is contacted with the adsorbent under a pressure of 0.5 MPa or less. [8] The method for purifying bromofluoroethylene according to any one of [1] to [7], wherein in the purification step, the bromofluoroethylene is contacted with the adsorbent at a temperature of 0° C. or higher and 40° C. or lower.

[0012] [9] The method for purifying bromofluoroethylene according to any one of [1] to [8], wherein in the purification step, the total content of the impurities in the bromofluoroethylene is reduced to 1000 ppm by volume or less.

[10] The method for purifying bromofluoroethylene according to any one of [1] to [9], wherein in the purification step, the total content of the nitrogen-containing compounds in the bromofluoroethylene is reduced to 500 ppm by volume or less.

[0013]

[11] Bromofluoroethylene containing impurities, the impurity is at least one selected from the group consisting of a nitrogen-containing compound which is a compound having a nitrogen atom in its molecule and a molecular weight of 50 or more, and a carbon-containing compound which is a compound having a carbon atom in its molecule and a molecular weight of 150 or more, the carbon-containing compound is a compound different from the bromofluoroethylene and a compound different from the nitrogen-containing compound, Bromofluoroethylene, the total content of said impurities being 1000 ppm by volume or less.

[0014]

[12] The bromofluoroethylene according to

[11] , wherein the total content of the nitrogen-containing compounds is 500 ppm by volume or less.

[13] An etching gas containing bromofluoroethylene according to

[11] or

[12] . Effect of the Invention

[0015] According to the present disclosure, impurities can be removed from bromofluoroethylene to provide high-purity bromofluoroethylene and an etching gas having a low impurity content. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing an example of a purification processing apparatus for carrying out a method for purifying bromofluoroethylene according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of the present disclosure will be described below. Note that this embodiment shows an example of the present disclosure, and the present disclosure is not limited to this embodiment. In addition, various modifications or improvements can be made to this embodiment, and such modifications or improvements can also be included in the present disclosure.

[0018] The method for purifying bromofluoroethylene according to this embodiment includes a purification step of contacting bromofluoroethylene containing impurities with an adsorbent having pores with an average pore diameter of 3 Å or more and 50 Å or less, thereby causing the impurities in the bromofluoroethylene to be adsorbed onto the adsorbent, thereby reducing the content of impurities in the bromofluoroethylene.

[0019] The impurity is at least one selected from the group consisting of a nitrogen-containing compound, which is a compound having a nitrogen atom in the molecule and a molecular weight of 50 or more, and a carbon-containing compound, which is a compound having a carbon atom in the molecule and a molecular weight of 150 or more. The carbon-containing compound is a compound different from the bromofluoroethylene and different from the nitrogen-containing compound.

[0020] That is, the method for purifying bromofluoroethylene according to this embodiment includes a purification step of contacting bromofluoroethylene containing impurities with an adsorbent having pores with an average pore diameter of 3 Å or more and 50 Å or less, and adsorbing the impurities in the bromofluoroethylene onto the adsorbent, thereby reducing the content of the impurities in the bromofluoroethylene, the impurity is at least one selected from the group consisting of a nitrogen-containing compound which is a compound having a nitrogen atom in its molecule and a molecular weight of 50 or more, and a carbon-containing compound which is a compound having a carbon atom in its molecule and a molecular weight of 150 or more, The carbon-containing compound is preferably a compound different from the bromofluoroethylene and different from the nitrogen-containing compound, and the method for purifying bromofluoroethylene is preferably such that the carbon-containing compound is a compound different from the bromofluoroethylene and different from the nitrogen-containing compound.

[0021] With the above-mentioned configuration, impurities can be removed from bromofluoroethylene, so that high-purity bromofluoroethylene with a low impurity content can be produced. The obtained high-purity bromofluoroethylene can be used as an etching gas.

[0022] Moreover, with the above-mentioned configuration, since no large-scale purification treatment device is required, impurities can be easily removed from bromofluoroethylene. Furthermore, by changing the type of adsorbent, it is possible to selectively remove specific impurities. Furthermore, since it is possible to regenerate and reuse the adsorbent, the method for purifying bromofluoroethylene according to this embodiment is also excellent from the viewpoint of reducing waste.

[0023] The method for purifying bromofluoroethylene according to this embodiment will be described in further detail below. [Bromofluoroethylene] Bromofluoroethylene is a compound having 2 carbon atoms and a degree of unsaturation of 1, containing at least one bromine atom and one fluorine atom in the molecule. Bromofluoroethylene may contain atoms other than carbon, bromine, and fluorine atoms in the molecule. For example, it may contain hydrogen, chlorine, iodine, oxygen, and nitrogen atoms.

[0024] The type of bromofluoroethylene that can be purified by the bromofluoroethylene purification method of this embodiment is not particularly limited, but taking into consideration the ease of separation from the solid adsorbent, bromofluoroethylene having 1 or more and 3 or less bromine atoms is preferred, bromofluoroethylene having 1 or 2 bromine atoms is more preferred, and bromofluoroethylene having 1 bromine atom is even more preferred.

[0025] Specific examples of bromofluoroethylene include 1-bromo-1-fluoroethylene (CFBr=CH2), 1-bromo-2-fluoroethylene (CHF=CHBr, E and Z forms), 1-bromo-1,2-difluoroethylene (CFBr=CHF, E and Z forms), 1-bromo-2,2-difluoroethylene (CF2=CHBr), 1-bromo-1,2,2-trifluoroethylene (CFBr=CF2), 1,2-dibromo-1,2-difluoroethylene (CFBr=CF2), Examples of fluoroethylene include fluoroethylene (CFBr=CFBr, E and Z forms), 1,2-dibromo-1-fluoroethylene (CFBr=CHBr, E and Z forms), 1-bromo-2,2-difluoroethylene (CHBr=CF2), 1,1-dibromo-2,2-difluoroethylene (CBr2=CF2), 1,1-dibromo-2-fluoroethylene (CBr2=CHF), and 1,1,2-tribromo-2-fluoroethylene (CBr2=CFBr).

[0026] Among these bromofluoroethylenes, 1-bromo-1-fluoroethylene, (E)-1-bromo-2-fluoroethylene, (Z)-1-bromo-2-fluoroethylene, (E)-1-bromo-1,2-difluoroethylene, (Z)-1-bromo-1,2-difluoroethylene, 1-bromo-1,2,2-trifluoroethylene, and 1-bromo-2,2-difluoroethylene, which are easy to handle, are more preferred. That is, the bromofluoroethylene is more preferably at least one of 1-bromo-1,2,2-trifluoroethylene, 1-bromo-1-fluoroethylene, 1-bromo-2-fluoroethylene, 1-bromo-1,2-difluoroethylene, and 1-bromo-2,2-difluoroethylene.

[0027] The bromofluoroethylene to be subjected to the purification step of the purification method of the present embodiment may be in the form of gas or liquid. Also, the bromofluoroethylene to be subjected to the purification step of the purification method of the present embodiment may be a reaction product produced by a synthesis reaction, or may be stored in a gas cylinder.

[0028] When bromofluoroethylene is the reaction product, the reaction product produced by the synthesis reaction may be subjected directly to the purification step of the method for purifying bromofluoroethylene according to this embodiment, but before being subjected to the purification step of the method for purifying bromofluoroethylene according to this embodiment, impurities may be removed in advance by a conventional technique such as distillation to reduce the impurity content in the bromofluoroethylene, and then the reaction product may be subjected to the purification step.

[0029] [Nitrogen-containing impurities] Nitrogen-containing compounds, which are impurities contained in bromofluoroethylene, are compounds that have a nitrogen atom in the molecule and have a molecular weight of 50 or more, preferably a molecular weight of 80 or more, and more preferably a molecular weight of 120 or more.

[0030] Examples of nitrogen-containing impurities include alkylamines used as polymerization inhibitors for bromofluoroethylene, and among alkylamines, trialkylamines are preferred. Examples of alkylamines include trimethylamine (C3H9N), triethylamine (C6H 15 N), tri-n-propylamine (CH 21 N), triisopropylamine (CH 21 N), and tri-n-butylamine (C 12 H 27 Other examples of nitrogen-containing impurities include diisopropylethylamine (CH 19 N), cyclohexylamine (CH 13 N), pyrrolidine (C4H9N), piperidine (C5H 11 N) are listed.

[0031] [Carbon-containing compound] The carbon-containing compounds that are impurities contained in bromofluoroethylene are compounds that have carbon atoms in their molecules and have a molecular weight of 150 or more, preferably 180 or more, and more preferably 220 or more.

[0032] Examples of the carbon-containing compound include self-reaction products of bromofluoroethylene, specifically at least one selected from the group consisting of cyclic polymers of bromofluoroethylene, homo-coupling products of bromofluoroethylene, and polymers of bromofluoroethylene.

[0033] A cyclized polymer of bromofluoroethylene is a cyclized dimerization product of two molecules of bromofluoroethylene. A bromofluoroethylene oligomer is a oligomerization product of two or more molecules of bromofluoroethylene. A homo-coupling product of bromofluoroethylene is a coupling product in which a bromine atom or a fluorine atom of bromofluoroethylene is eliminated to form a carbon-carbon bond.

[0034] Specific examples of such compounds include 1,3-dibromo-2,4-difluorocyclobutane, 1,2-dibromo-3,4-difluorocyclobutane, 1,3-dibromo-1,3-difluorocyclobutane, 1,2-dibromo-1,2-difluorocyclobutane, 1,3-dibromo-1,2,3,4-tetrafluorocyclobutane, 1,2-dibromo-1,2,3,4-tetrafluorocyclobutane, 1,3-dibromo 1,2-dibromo-3,3,4,4-tetrafluorocyclobutane, 1,3-dibromo-1,2,2,3,4,4-hexafluorocyclobutane, 1,2-dibromo-1,2,3,3,4,4-hexafluorocyclobutane, 1,1,3,3-tetrabromo-2,4-difluorocyclobutane, 1,1,2,2-tetrabromo-3,4-difluorocyclobutane, 1,1,3,3-tetrabromo-2,2,4,4-tetrafluorocyclobutane, 1,1,2,2-tetrabromo-3,3,4,4-tetrafluorocyclobutane, 1,2,3,4-tetrabromo-1,3-difluorocyclobutane, 1,2,3,4-tetrabromo-1,2-difluorocyclobutane, 1,2,3,4-tetrabromo-1,2,3,4-tetrafluorocyclobutane, hexafluorobutadiene, Examples of such fluorobutadiene include 1,4-dibromo-1,2,3,4-tetrafluorobutadiene, 2,3-dibromo-1,1,4,4-tetrafluorobutadiene, 1,4-dibromo-1,4-difluorobutadiene, and 1,4-dibromo-2,3-difluorobutadiene.

[0035] The content of impurities in the bromofluoroethylene subjected to the purification step is not particularly limited, but in consideration of increasing the rate of removal of impurities from bromofluoroethylene, it is preferable that it is as follows: That is, the total content of impurities in the bromofluoroethylene subjected to the purification step is preferably 2 vol % or less, more preferably 1.5 vol % or less, and even more preferably 1 vol % or less. In this specification, bromofluoroethylene that is subjected to the purification step is sometimes referred to as "crude bromofluoroethylene", and bromofluoroethylene that has been purified by the purification step is sometimes referred to as "purified bromofluoroethylene".

[0036] [Adsorbent] The adsorbent used in the purification step of the purification method of bromofluoroethylene according to the present embodiment is, for example, a solid adsorbent. Examples of the adsorbent include activated carbon, zeolite, activated alumina, and silica gel. Examples of the zeolite include A-type zeolite and X-type zeolite. These adsorbents may be used alone or in combination of two or more in any ratio.

[0037] Among these adsorbents, activated carbon and zeolite are preferred from the viewpoint of removing impurities. The cationic species of zeolite are preferably potassium ion, sodium ion, and calcium ion. Examples of zeolite include zeolite MS-3A (average pore size: 3 Å, KA type), zeolite MS-4A (average pore size: 4 Å, NaA type), zeolite MS-5A (average pore size: 5 Å, CaA type), and zeolite MS-13X (average pore size: 10 Å, NaA type).

[0038] The average pore diameter of the adsorbent is preferably 3 Å or more and 50 Å or less, more preferably 4 Å or more and 30 Å or less, and even more preferably 5 Å or more and 20 Å or less. The method for measuring the average pore diameter of the adsorbent is not particularly limited, but it can be measured, for example, by the BET adsorption method. An example of the measurement conditions for the average pore diameter by the BET adsorption method is shown below.

[0039] Measuring equipment: BELSORP-max manufactured by Nikkiso Co., Ltd. Adsorbate: Nitrogen gas Measurement temperature: -196℃ Pretreatment of the adsorbent: Heat-dried at 300℃ for 6 hours under vacuum conditions. Amount of adsorbent used: 0.10g

[0040] It is preferable to subject the adsorbent to an activation treatment before use in the purification step of the purification method of bromofluoroethylene according to the present embodiment. Examples of the activation treatment include a heat treatment with a dry gas at 100°C or more and 350°C or less, and a heat treatment at a temperature of 100°C or more and 350°C or less under reduced pressure. Examples of the dry gas include helium (He), nitrogen gas (N2), and argon (Ar). Such an activation treatment improves the impurity removal efficiency of the adsorbent.

[0041] [Refining process] In the purification step, it is preferable to contact bromofluoroethylene with the adsorbent under a pressure of 0.5 MPa or less. In more detail, the pressure of bromofluoroethylene when contacting bromofluoroethylene with the adsorbent in the purification step is not particularly limited, but is preferably 0 MPa or more and 0.5 MPa or less, more preferably 0.05 MPa or more and 0.4 MPa or less, and even more preferably 0.2 MPa or more and 0.35 MPa or less. In this disclosure, unless otherwise specified, the pressure is expressed as a gauge pressure.

[0042] In the purification step, it is preferable to contact bromofluoroethylene with the adsorbent at a temperature of 0° C. or more and 40° C. or less. In particular, the temperature at which bromofluoroethylene is contacted with the adsorbent in the purification step is not particularly limited, but is preferably 0° C. or more and 40° C. or less, and more preferably 0° C. or more and 30° C. or less.

[0043] The contact time between the adsorbent and bromofluoroethylene in the purification step is not particularly limited, but the longer the contact time, the higher the adsorption efficiency of the adsorbent and the easier it is to obtain bromofluoroethylene with a high purity.On the other hand, the shorter the contact time, the higher the processing capacity and the more efficiently bromofluoroethylene can be purified.

[0044] In the purification method of bromofluoroethylene according to this embodiment, it is preferable to reduce the total content of impurities in bromofluoroethylene to 1000 ppm by volume or less in the purification step. More specifically, the total content of impurities contained in purified bromofluoroethylene is preferably 1000 ppm by volume or less, more preferably 500 ppm by volume or less, and even more preferably 100 ppm by volume or less.

[0045] In the purification method of bromofluoroethylene according to this embodiment, it is preferable to reduce the total content of nitrogen-containing compounds in bromofluoroethylene to 500 ppm by volume or less in the purification step. More specifically, the total content of nitrogen-containing compounds contained in purified bromofluoroethylene is preferably 500 ppm by volume or less, more preferably 400 ppm by volume or less, and even more preferably 100 ppm by volume or less.

[0046] In the purification method of bromofluoroethylene according to this embodiment, it is preferable to reduce the total content of carbon-containing compounds in the bromofluoroethylene to 1000 ppm by volume or less in the purification step. More specifically, the total content of carbon-containing compounds contained in the purified bromofluoroethylene is preferably 1000 ppm by volume or less, more preferably 400 ppm by volume or less, and even more preferably 100 ppm by volume or less.

[0047] If the total content of impurities contained in the refined bromofluoroethylene is within the above range, the refined bromofluoroethylene can be suitably used, for example, as an etching gas. If bromofluoroethylene having a total content of impurities within the above range is used as an etching gas, it is easy to obtain the effect of suppressing damage to the etching apparatus (e.g., chamber) and a decrease in yield and a decrease in etching rate due to particle generation.

[0048] [Refining Treatment Equipment] The material forming the part of the purification processing device that purifies bromofluoroethylene that comes into contact with bromofluoroethylene is not particularly limited as long as it is a material that is unlikely to generate impurities by reaction with bromofluoroethylene. Examples include corrosion-resistant metals such as stainless steel, Inconel (registered trademark), Monel (registered trademark), Hastelloy (registered trademark), and nickel. Note that the parts of the members formed of corrosion-resistant metals that come into contact with bromofluoroethylene may be lined with glass or fluororesin to improve corrosion resistance.

[0049] Next, an example of a purification processing apparatus for carrying out the method for purifying bromofluoroethylene according to this embodiment and an example of a method for purifying bromofluoroethylene using the purification processing apparatus will be described with reference to FIG. The purification treatment apparatus in FIG. 1 comprises a crude bromofluoroethylene cylinder 1 filled with crude bromofluoroethylene containing impurities, an adsorption purification column 4 for purifying the crude bromofluoroethylene, a collection cylinder 6 for collecting the purified bromofluoroethylene after purification, a crude bromofluoroethylene supply pipe 3 connecting the crude bromofluoroethylene cylinder 1 and the adsorption purification column 4, and a purified bromofluoroethylene transfer pipe 5 connecting the adsorption purification column 4 and the collection cylinder 6.

[0050] A crude bromofluoroethylene supply unit 2 consisting of a mass flow controller or the like is provided in the upstream portion of the crude bromofluoroethylene supply pipe 3 (i.e., the portion close to the crude bromofluoroethylene cylinder 1). The crude bromofluoroethylene in the crude bromofluoroethylene cylinder 1 is supplied to the adsorption purification column 4 via the crude bromofluoroethylene supply pipe 3 while the flow rate is controlled by the crude bromofluoroethylene supply unit 2.

[0051] The adsorption purification column 4 is installed so that its length direction is parallel to the vertical direction, and the inside of the adsorption purification column 4 is filled with an adsorbent. The crude bromofluoroethylene transferred through the crude bromofluoroethylene supply pipe 3 is supplied to the inside of the adsorption purification column 4 from the upper part, and passes through the inside of the adsorption purification column 4 toward the lower part. Impurities contained in the crude bromofluoroethylene are adsorbed by the adsorbent in the adsorption purification column 4, and purified bromofluoroethylene with a reduced impurity content is recovered in a collection cylinder 6.

[0052] [Refined bromofluoroethylene and etching gas] The bromofluoroethylene (refined bromofluoroethylene) according to this embodiment is bromofluoroethylene containing impurities, and the impurities are at least one selected from the group consisting of nitrogen-containing compounds, which are compounds having a nitrogen atom in the molecule and a molecular weight of 50 or more, and carbon-containing compounds, which are compounds having a carbon atom in the molecule and a molecular weight of 150 or more. The carbon-containing compound is a compound different from the bromofluoroethylene and different from the nitrogen-containing compound. The total content of the impurities is 1000 ppm by volume or less. The total content of the nitrogen-containing compounds is preferably 500 ppm by volume or less.

[0053] Such purified bromofluoroethylene having a low content of impurities can be obtained by purifying crude bromofluoroethylene using the method for purifying bromofluoroethylene according to this embodiment. The bromofluoroethylene (refined bromofluoroethylene) according to this embodiment has a low impurity content and is highly pure, and therefore can be used as an etching gas in the etching step in the manufacturing process of semiconductor devices. That is, the etching gas according to this embodiment is a gas containing the bromofluoroethylene according to this embodiment. EXAMPLES

[0054] The present disclosure will be described in more detail below with reference to examples and comparative examples. First, bromofluoroethylene containing various impurity contents (crude bromofluoroethylene) was prepared. Preparation examples of crude bromofluoroethylene are described below. In the following, the composition of crude bromofluoroethylene was determined from GC area % by gas chromatography (GC-FID).

[0055] The measurement conditions for the gas chromatograph are as follows: Gas chromatograph: Shimadzu Corporation GC-2014 Column: Agilent Technologies DB-1 Injection temperature: 200℃ Column temperature: 40℃ Detector: FID Detector temperature: 200℃ Carrier gas: Helium

[0056] [Preparation Example 1] A manganese steel cylinder A with a capacity of 10 L and a sealable cylinder I with a capacity of 1 L made of SUS316 were prepared. Cylinder A was filled with 5000 g of 1-bromo-1,2,2-trifluoroethylene, and cylinder I was empty with nothing filled in it.

[0057] Cylinder I was filled with 5.1 g of tri-n-butylamine and cooled to −78° C., after which the inside pressure was reduced to 1 kPa or less using a vacuum pump. 500 g of 1-bromo-1,2,2-trifluoroethylene gas was extracted from the upper outlet of cylinder A where the gas phase exists, passed through a filter, and then collected in cylinder I under reduced pressure. Since cylinder I was cooled to -78°C, 1-bromo-1,2,2-trifluoroethylene was liquefied inside cylinder I.

[0058] The filter used was an in-line filter manufactured by Swagelok, with a sintered metal element filter type and a bore size of 0.5 μm. The flow rate of the gas passing through the filter was controlled at 500 mL / min by a mass flow controller. The total amount of 1-bromo-1,2,2-trifluoroethylene and tri-n-butylamine collected in cylinder I was 503 g. The crude bromofluoroethylene collected in cylinder I was designated sample 1-1.

[0059] The gas phase inside cylinder I was extracted and analyzed by gas chromatography, which revealed that it contained 0.32% by volume of tri-n-butylamine, a nitrogen-containing compound. In addition, neither the cyclic polymer (dimer) nor the homo-coupling product of 1-bromo-1,2,2-trifluoroethylene was detected (less than 1 ppm by volume). Therefore, the purity of 1-bromo-1,2,2-trifluoroethylene was 99.68% by volume. The results are shown in Table 1.

[0060] [Table 1]

[0061] [Preparation Example 2] A sealable cylinder II made of SUS316 with a capacity of 1 L was prepared. Cylinder II was empty and not filled with anything. After the pressure inside cylinder II was reduced to less than 1 kPa using a vacuum pump, trimethylamine was transferred into cylinder II, which was then cooled to -78°C to liquefy it, and 4.4 g of trimethylamine was filled into cylinder II.

[0062] 500 g of 1-bromo-1,2,2-trifluoroethylene gas was extracted from the upper outlet of cylinder A where the gas phase exists, and after passing through a filter, it was collected in cylinder II under reduced pressure. Since cylinder II was cooled to -78°C, 1-bromo-1,2,2-trifluoroethylene was liquefied inside cylinder II.

[0063] The filter used was the same as in Preparation Example 1. The flow rate of the gas passing through the filter was controlled to 500 mL / min by a mass flow controller. The total amount of 1-bromo-1,2,2-trifluoroethylene and trimethylamine collected in cylinder II was 501 g. The crude bromofluoroethylene collected in cylinder II was designated sample 1-2.

[0064] The gas phase inside Cylinder II was extracted and analyzed by gas chromatography, which revealed that it contained 1.13% by volume of triethylamine, a nitrogen-containing compound. In addition, neither the cyclic polymer (dimer) nor the homo-coupling product of 1-bromo-1,2,2-trifluoroethylene was detected (less than 1 ppm by volume). Therefore, the purity of 1-bromo-1,2,2-trifluoroethylene was 98.87% by volume. The results are shown in Table 1.

[0065] [Preparation Example 3] A manganese steel cylinder B having a capacity of 10 L and a sealable cylinder III having a capacity of 1 L made of SUS316 were prepared. Cylinder B was filled with 5000 g of 1-bromo-1,2,2-trifluoroethylene, and cylinder III was empty.

[0066] 500 g of 1-bromo-1,2,2-trifluoroethylene gas was extracted from the upper outlet of cylinder B where the gas phase exists, passed through a filter, and then collected in cylinder III. Since cylinder III was cooled to -78°C, 1-bromo-1,2,2-trifluoroethylene was liquefied in cylinder III.

[0067] The filter used was the same as in Preparation Example 1. The flow rate of the gas passing through the filter was controlled to 500 mL / min by a mass flow controller. The amount of 1-bromo-1,2,2-trifluoroethylene gas collected in cylinder III was 500 g. The crude bromofluoroethylene collected in cylinder III was designated as sample 1-3.

[0068] The gas phase inside cylinder III was extracted and analyzed by gas chromatography. It was found to contain 0.67% by volume of 1,2-dibromo-1,2,3,3,4,4-hexafluorocyclobutane, a cyclic polymer (dimer) of 1-bromo-1,2,2-trifluoroethylene, and 0.05% by volume of hexafluorobutadiene, a homo-coupling product of 1-bromo-1,2,2-trifluoroethylene. Therefore, the purity of 1-bromo-1,2,2-trifluoroethylene was 99.28% by volume. The results are shown in Table 1.

[0069] [Preparation Example 4] A manganese steel cylinder C having a capacity of 10 L and a sealable cylinder IV having a capacity of 1 L made of SUS316 were prepared. The cylinder C was filled with 3000 g of 1-bromo-1-fluoroethylene, and the cylinder IV was empty.

[0070] Cylinder IV was filled with 4.8 g of tri-n-butylamine and cooled to −78° C., and then the inside pressure was reduced to 1 kPa or less using a vacuum pump. 500 g of 1-bromo-1-fluoroethylene gas was extracted from the upper outlet of cylinder C where the gas phase exists, passed through a filter, and then collected in cylinder IV under reduced pressure. Since cylinder IV was cooled to -78°C, 1-bromo-1-fluoroethylene was liquefied in cylinder IV.

[0071] The filter used was the same as in Preparation Example 1. The flow rate of the gas passing through the filter was controlled to 500 mL / min by a mass flow controller. The total amount of 1-bromo-1-fluoroethylene and tri-n-butylamine collected in cylinder IV was 503 g. The crude bromofluoroethylene collected in cylinder IV was designated sample 1-4.

[0072] The gas phase inside Cylinder IV was extracted and analyzed by gas chromatography, which revealed that it contained 0.28% by volume of tri-n-butylamine, a nitrogen-containing compound. In addition, neither the cyclic polymer (dimer) nor the homo-coupling product of 1-bromo-1-fluoroethylene was detected (less than 1 ppm by volume). Therefore, the purity of 1-bromo-1-fluoroethylene was 99.72% by volume. The results are shown in Table 1.

[0073] [Preparation Example 5] A sealable cylinder V made of SUS316 with a capacity of 1 L was prepared. Cylinder V was empty and not filled with anything. Cylinder V was filled with 4.4 g of tri-n-butylamine and cooled to −78° C., and then the inside pressure was reduced to 1 kPa or less using a vacuum pump.

[0074] 500 g of 1-bromo-1,2,2-trifluoroethylene gas was extracted from the upper outlet of cylinder B where the gas phase exists, passed through a filter, and then collected in cylinder V under reduced pressure. Since cylinder V was cooled to -78°C, 1-bromo-1,2,2-trifluoroethylene was liquefied inside cylinder V.

[0075] The filter used was the same as in Preparation Example 1. The flow rate of the gas passing through the filter was controlled to 500 mL / min by a mass flow controller. The total amount of 1-bromo-1,2,2-trifluoroethylene and tri-n-butylamine collected in cylinder V was 503 g. The crude bromofluoroethylene collected in cylinder V was designated sample 1-5.

[0076] The gas phase inside cylinder V was extracted and analyzed by gas chromatography, and it was found to contain 0.30% by volume of tri-n-butylamine, a nitrogen-containing compound. It also contained 0.65% by volume of 1,2-dibromo-1,2,3,3,4,4-hexafluorocyclobutane, a cyclic polymer (dimer) of 1-bromo-1,2,2-trifluoroethylene, and 0.07% by volume of hexafluorobutadiene, a homo-coupling product of 1-bromo-1,2,2-trifluoroethylene. Therefore, the purity of 1-bromo-1,2,2-trifluoroethylene was 98.98% by volume. The results are shown in Table 1.

[0077] [Preparation Example 6] A sealable cylinder VI made of SUS316 with a capacity of 1 L was prepared. Cylinder VI was empty and not filled with anything. The inside of cylinder VI was decompressed to 1 kPa or less with a vacuum pump, and then dimethylamine was transferred into cylinder VI, cooled to −78° C. to liquefy, and 3.5 g of dimethylamine was filled into cylinder VI.

[0078] 500 g of 1-bromo-1,2,2-trifluoroethylene gas was extracted from the upper outlet of cylinder A where the gas phase exists, and after passing through a filter, it was collected in cylinder VI under reduced pressure. Since cylinder VI was cooled to -78°C, 1-bromo-1,2,2-trifluoroethylene was liquefied in cylinder VI.

[0079] The filter used was the same as in Preparation Example 1. The flow rate of the gas passing through the filter was controlled to 500 mL / min by a mass flow controller. The total amount of 1-bromo-1,2,2-trifluoroethylene and dimethylamine collected in cylinder VI was 505 g. The crude bromofluoroethylene collected in cylinder VI was designated as sample 1-6.

[0080] The gas phase inside Cylinder VI was extracted and analyzed by gas chromatography, which revealed that it contained 0.91% by volume of dimethylamine, a nitrogen-containing compound. In addition, neither the cyclic polymer (dimer) nor the homo-coupling product of 1-bromo-1,2,2-trifluoroethylene was detected (less than 1 ppm by volume). Therefore, the purity of 1-bromo-1,2,2-trifluoroethylene was 99.09% by volume. The results are shown in Table 1.

[0081] Example 1 A tubular member made of SUS316 (inner diameter 48 mm, length 500 mm) was prepared and filled with 46.1 g of activated carbon as an adsorbent. This activated carbon was Granular Shirasagi G2x manufactured by Osaka Gas Chemicals Co., Ltd., with an average particle size of 4 to 6 mesh and an average pore size of 20 Å. While flowing nitrogen gas inside the tubular member, the activated carbon inside was heated and dried to form an adsorption purification tower. The heating conditions were 150°C and 6 hours.

[0082] Sample 1-1 was introduced into this adsorption purification tower at room temperature (20°C) and atmospheric pressure (0.1 MPa) and purification treatment was performed. The flow rate of Sample 1-1 introduced into the adsorption purification tower was controlled to 50 mL / min by a mass flow controller. The gas discharged from the adsorption purification tower was collected in a Tedlar bag. Then, the gas was extracted from the Tedlar bag and analyzed by gas chromatography to measure the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene. The results are shown in Table 2.

[0083] [Table 2]

[0084] (Examples 2 and 3) The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 1, except that the type of sample to be analyzed and the amount of adsorbent packed in the adsorption purification tower were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2.

[0085] (Examples 4, 5, and 6) The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 1, except that the type of sample to be analyzed and the type and amount of adsorbent packed in the adsorption purification tower were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2. The type of adsorbent packed in the adsorption purification tower was zeolite MS-13X manufactured by Resonac Universal Co., Ltd., and had an average pore diameter of 10 Å.

[0086] Example 7 The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 1, except that the type of sample to be analyzed and the type and amount of adsorbent packed in the adsorption purification tower were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2. The type of adsorbent packed in the adsorption purification tower was zeolite MS-4A manufactured by Resonac Universal Co., Ltd., and its average pore diameter was 4 Å.

[0087] Example 8 The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 1, except that the type of sample to be analyzed and the type and amount of adsorbent packed in the adsorption purification tower were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2.

[0088] Example 9 The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 1, except that the purification temperature and the adsorbent loading were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2. Compared to Example 1, the removal rate of tri-n-butylamine decreased, and the content of dimers increased.

[0089] Comparative Example 1 The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 1, except that the type and amount of adsorbent packed in the adsorption purification tower were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2. The type of adsorbent packed in the adsorption purification tower was silica gel Wakogel (registered trademark) C-200 manufactured by Wako Pure Chemical Industries, Ltd., and its average pore diameter was 70 Å. There was no change in the contents of tri-n-butylamine and dimer contained in 1-bromo-1,2,2-trifluoroethylene before and after the purification treatment.

[0090] Comparative Example 2 The crude bromofluoroethylene was purified and analyzed in the same manner as in Comparative Example 1, except that the type of sample to be analyzed and the amount of adsorbent packed were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupled products of bromofluoroethylene were measured. The results are shown in Table 2. The contents of dimers and homo-coupled products in the 1-bromo-1,2,2-trifluoroethylene after the purification treatment increased slightly compared to before the purification treatment.

[0091] Comparative Example 3 The crude bromofluoroethylene was purified and analyzed in the same manner as in Example 7, except that the type of sample to be analyzed and the amount of adsorbent packed were as shown in Table 2, and the contents of nitrogen-containing compounds, cyclized polymers (dimers) of bromofluoroethylene, and homo-coupling products of bromofluoroethylene were measured. The results are shown in Table 2. There was no change in the content of dimethylamine contained in 1-bromo-1,2,2-trifluoroethylene before and after the purification treatment. [Explanation of symbols]

[0092] 1 Crude bromofluoroethylene cylinder 4. Adsorption purification tower 6. Collection cylinder

Claims

1. a purification step of contacting bromofluoroethylene containing impurities with an adsorbent having pores with an average pore size of 3 Å or more and 50 Å or less, thereby causing the impurities in the bromofluoroethylene to be adsorbed by the adsorbent, thereby reducing the content of the impurities in the bromofluoroethylene, the impurity is at least one selected from the group consisting of a nitrogen-containing compound which is a compound having a nitrogen atom in its molecule and a molecular weight of 50 or more, and a carbon-containing compound which is a compound having a carbon atom in its molecule and a molecular weight of 150 or more, A method for purifying bromofluoroethylene, wherein the carbon-containing compound is a compound different from the bromofluoroethylene and a compound different from the nitrogen-containing compound.

2. 2. The method for purifying bromofluoroethylene according to claim 1, wherein the nitrogen-containing compound is an alkylamine.

3. 3. The method for purifying bromofluoroethylene according to claim 2, wherein the alkylamine is at least one of trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, and tri-n-butylamine.

4. The method for purifying bromofluoroethylene according to any one of claims 1 to 3, wherein the carbon-containing compound is at least one selected from the group consisting of a cyclized polymer of the bromofluoroethylene, a homo-coupling product of the bromofluoroethylene, and a polymer of the bromofluoroethylene.

5. 4. The method for purifying bromofluoroethylene according to claim 1, wherein the total content of the impurities in the bromofluoroethylene subjected to the purification step is 2% by volume or less.

6. The method for purifying bromofluoroethylene according to any one of claims 1 to 3, wherein the bromofluoroethylene is at least one of 1-bromo-1,2,2-trifluoroethylene, 1-bromo-1-fluoroethylene, 1-bromo-2-fluoroethylene, 1-bromo-1,2-difluoroethylene, and 1-bromo-2,2-difluoroethylene.

7. 4. The method for purifying bromofluoroethylene according to claim 1, wherein in the purification step, the bromofluoroethylene is contacted with the adsorbent under a pressure of 0.5 MPa or less.

8. 4. The method for purifying bromofluoroethylene according to claim 1, wherein in the purification step, the bromofluoroethylene is contacted with the adsorbent at a temperature of 0° C. or higher and 40° C. or lower.

9. 4. The method for purifying bromofluoroethylene according to claim 1, wherein in the purification step, the total content of the impurities in the bromofluoroethylene is reduced to 1000 ppm by volume or less.

10. 4. The method for purifying bromofluoroethylene according to claim 1, wherein in the purification step, the total content of the nitrogen-containing compounds in the bromofluoroethylene is reduced to 500 ppm by volume or less.

11. Bromofluoroethylene containing impurities, the impurity is at least one selected from the group consisting of a nitrogen-containing compound which is a compound having a nitrogen atom in its molecule and a molecular weight of 50 or more, and a carbon-containing compound which is a compound having a carbon atom in its molecule and a molecular weight of 150 or more, the carbon-containing compound is a compound different from the bromofluoroethylene and a compound different from the nitrogen-containing compound, Bromofluoroethylene, the total content of said impurities being 1000 ppm by volume or less.

12. The bromofluoroethylene according to claim 11, wherein the total content of the nitrogen-containing compounds is 500 ppm by volume or less.

13. An etching gas containing the bromofluoroethylene according to claim 11 or 12.

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