JP2005053901A - Azeotropic mixture of fluoromethane and hydrogen chloride, and method for purifying fluoromethane - Google Patents

Azeotropic mixture of fluoromethane and hydrogen chloride, and method for purifying fluoromethane Download PDF

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JP2005053901A
JP2005053901A JP2004210478A JP2004210478A JP2005053901A JP 2005053901 A JP2005053901 A JP 2005053901A JP 2004210478 A JP2004210478 A JP 2004210478A JP 2004210478 A JP2004210478 A JP 2004210478A JP 2005053901 A JP2005053901 A JP 2005053901A
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fluoromethane
hfc
hydrogen chloride
hcl
distillation column
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JP4574259B2 (en
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Hiromoto Ono
博基 大野
Yuji Sakai
雄二 酒井
Tomoki Shibuya
智希 渋谷
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Resonac Holdings Corp
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Showa Denko KK
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a high purity HFC-41 capable of being used as an etching gas for a semiconductor. <P>SOLUTION: This method for purifying the fluoromethane is provided by distilling a mixture containing the fluoromethane and hydrogen chloride to distill off the fluoromethane from the top of a distillation column, obtaining an azeotropic mixture of the fluoromethane with hydrogen chloride from the bottom of the distillation column and also preferably comprising a process of bringing the fluoromethane distilled off from the top of the column in contact with a treating agent containing water and/or an alkali for removing an acid component containing hydrogen chloride. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、フルオロメタン(以下、「CH3F」または「HFC−41」と称すること
がある。)と塩化水素(以下、「HCl」と称することがある。)との共沸混合物、フルオロメタンの精製方法およびその用途に関する。
The present invention relates to an azeotrope of fluoromethane (hereinafter sometimes referred to as “CH 3 F” or “HFC-41”) and hydrogen chloride (hereinafter sometimes referred to as “HCl”), fluoro The present invention relates to a method for purifying methane and its use.

ハイドロフルオロカーボン(HFC)類はオゾン破壊係数がゼロという特徴があり、またHFC−41、ジフルオロメタン(CH22)およびトリフルオロメタン(CHF3
などは半導体用エッチングガスとして有用な化合物である。
Hydrofluorocarbons (HFCs) are characterized by zero ozone depletion potential, and HFC-41, difluoromethane (CH 2 F 2 ) and trifluoromethane (CHF 3 ).
Are useful compounds as etching gases for semiconductors.

半導体用エッチングガスに用いられるHFC類は、高純度のものが求められており、特に酸成分(塩化水素、フッ化水素など)については好ましくは1.0wtppm以下、より好ましくは0.5wtppm以下であることが求められている。   HFCs used for semiconductor etching gases are required to have high purity. Particularly, acid components (hydrogen chloride, hydrogen fluoride, etc.) are preferably 1.0 wtppm or less, more preferably 0.5 wtppm or less. There is a need to be.

そのため、高純度のHFC類を製造するための多くの方法が提案されているが、HFC−41の製造方法については、あまり提案されていない。その主な理由としては、一般的なハロゲン化炭化水素をHFによりフッ素化する方法では、反応効率が悪いこと、分解反応などの副反応による副生成物が多いことなどが挙げられる。   Therefore, many methods for producing high-purity HFCs have been proposed, but a method for producing HFC-41 has not been proposed so much. The main reason is that, in the method of fluorinating a general halogenated hydrocarbon with HF, the reaction efficiency is poor and there are many by-products due to side reactions such as decomposition reactions.

こうした中、特許文献1(特公平4−7330号公報)には、メチルアルコールとフッ化水素(以下、「HF」と称することがある。)とを、フッ素化触媒(フッ化クロム)を用いて、100〜500℃の条件で気相反応させることにより、HFC−41を製造する方法が開示されている。しかし、この方法は、副生する水によってフッ素化触媒および反応装置の腐食を引き起こすという課題を有している。   Under such circumstances, Patent Document 1 (Japanese Patent Publication No. 4-7330) uses methyl alcohol and hydrogen fluoride (hereinafter sometimes referred to as “HF”) and a fluorination catalyst (chromium fluoride). And the method of manufacturing HFC-41 by carrying out a gas phase reaction on 100-500 degreeC conditions is disclosed. However, this method has a problem that corrosion of the fluorination catalyst and the reaction apparatus is caused by water generated as a by-product.

また、特許文献2(特開昭60−13726号公報)には、塩化メチル(CH3Cl)
とHFとを、フッ素化触媒(フッ化クロム)を用いて、反応温度100〜400℃の条件で気相反応させることにより、HFC−41を製造する方法が開示されている。しかし、この方法では、下記式1に示す平衡反応が生じること、ならびにHFC−41(大気圧下の沸点:−78.5℃)と塩化水素(大気圧下の沸点:−84.9℃)との沸点が近いため分離が難しいことなどの課題を有している。
Patent Document 2 (Japanese Patent Laid-Open No. 60-13726) discloses methyl chloride (CH 3 Cl).
Has disclosed a method of producing HFC-41 by reacting HF and HF in a gas phase reaction using a fluorination catalyst (chromium fluoride) at a reaction temperature of 100 to 400 ° C. However, in this method, the equilibrium reaction shown in the following formula 1 occurs, and HFC-41 (boiling point under atmospheric pressure: −78.5 ° C.) and hydrogen chloride (boiling point under atmospheric pressure: −84.9 ° C.) Since the boiling point is close, there are problems such as difficulty in separation.

Figure 2005053901
Figure 2005053901
特公平4−7330号公報Japanese Patent Publication No. 4-7330 特開昭60−13726号公報Japanese Patent Laid-Open No. 60-13726

本発明は、半導体用エッチングガスとして使用することができる高純度のHFC−41を効率的に製造する方法を提供することを課題とする。   An object of the present invention is to provide a method for efficiently producing high-purity HFC-41 that can be used as an etching gas for semiconductors.

本発明者らは、上記課題を解決すべく鋭意検討した結果、HFC−41とHClは最高共沸混合物を形成することを新たに見出した。また、HFC−41とHClとを含む混合物を蒸留することにより、蒸留塔の塔頂より実質的にHClを含まないHFC−41(HCl濃度:20wtppm以下)を得ることができること、さらに、得られたHFC−41を、水および/またはアルカリを含む処理剤に接触させることにより、HCl濃度が1.0wtppm以下である高純度HFC−41を得ることができることを見出し、本発明を完成するに至った。   As a result of intensive studies to solve the above problems, the present inventors have newly found that HFC-41 and HCl form the highest azeotrope. Further, by distilling a mixture containing HFC-41 and HCl, it is possible to obtain HFC-41 (HCl concentration: 20 wtppm or less) substantially free of HCl from the top of the distillation column. It was found that high purity HFC-41 having an HCl concentration of 1.0 wtppm or less can be obtained by contacting HFC-41 with a treatment agent containing water and / or alkali, and the present invention has been completed. It was.

本発明は、以下の[1]〜[7]に示されるHFC−41とHClとの共沸混合物、HFC−41の精製方法およびその用途に関する。
[1] フルオロメタンと塩化水素との共沸混合物。
[2] フロオロメタンと塩化水素とを含む混合物を蒸留し、蒸留塔の塔頂からフルオロメタンを留出させ、蒸留塔の塔底からフルオロメタンと塩化水素との共沸混合物を得ることを特徴とするフルオロメタンの精製方法。
[3] 0.1〜10.0MPaの範囲の操作圧力において蒸留することを特徴とする[2]に記載のフルオロメタンの精製方法。
[4] 前記蒸留塔の塔頂から留出させたフルオロメタン中に含まれる塩化水素濃度が20wtppm以下であることを特徴とする[2]または[3]に記載のフルオロメタンの精製方法。
[5] 前記蒸留塔の塔頂から留出させたフルオロメタンを、水および/またはアルカリを含む処理剤に接触させて、塩化水素を含む酸成分を除去する工程を含むことを特徴とする[2]〜[4]のいずれかに記載のフルオロメタンの精製方法。
[6] [2]〜[5]のいずれかに記載の方法により得られるフルオロメタンであって、塩化水素濃度が1.0wtppm以下であるフルオロメタンを含むことを特徴とするフルオロメタン製品。
[7] [6]に記載のフルオロメタン製品を含むことを特徴とするエッチングガス。
The present invention relates to an azeotropic mixture of HFC-41 and HCl shown in the following [1] to [7], a purification method of HFC-41, and use thereof.
[1] An azeotropic mixture of fluoromethane and hydrogen chloride.
[2] It is characterized by distilling a mixture containing fluoromethane and hydrogen chloride, distilling fluoromethane from the top of the distillation column, and obtaining an azeotrope of fluoromethane and hydrogen chloride from the bottom of the distillation column. To purify fluoromethane.
[3] The method for purifying fluoromethane according to [2], wherein distillation is performed at an operating pressure in the range of 0.1 to 10.0 MPa.
[4] The method for purifying fluoromethane according to [2] or [3], wherein the concentration of hydrogen chloride contained in the fluoromethane distilled from the top of the distillation column is 20 wtppm or less.
[5] The method includes contacting the fluoromethane distilled from the top of the distillation column with a treating agent containing water and / or alkali to remove an acid component containing hydrogen chloride. [2] The method for purifying fluoromethane according to any one of [4].
[6] A fluoromethane product obtained by the method according to any one of [2] to [5], comprising fluoromethane having a hydrogen chloride concentration of 1.0 wtppm or less.
[7] An etching gas comprising the fluoromethane product according to [6].

本発明によれば、HFC−41とHClとの共沸現象を利用することにより、HFC−41とHClとを含む混合物からHClを効率よく分離することができ、高純度のHFC−41を得ることができる。   According to the present invention, by utilizing the azeotropic phenomenon of HFC-41 and HCl, HCl can be efficiently separated from the mixture containing HFC-41 and HCl, and high purity HFC-41 is obtained. be able to.

以下に、本発明に係るHFC−41とHClとの共沸混合物、HFC−41の精製方法およびその用途について詳しく説明する。
HFC−41とHClは共沸混合物を形成する。大気圧下において、HFC−41の沸点は−78.5℃であり、HClの沸点は−84.9℃であり、この共沸混合物の沸点は約−73℃であることから、HFC−41とHClは最高共沸混合物を形成する。大気圧下における共沸組成は、HFC−41が約55モル%、HClが約45モル%である。また、他の圧力、たとえば2.0MPaにおいては、共沸混合物の沸点は約4℃であり、共沸組成はHFC−41が約53モル%、HClが約47モル%である。
Hereinafter, the azeotropic mixture of HFC-41 and HCl according to the present invention, the purification method of HFC-41 and its use will be described in detail.
HFC-41 and HCl form an azeotrope. Under atmospheric pressure, the boiling point of HFC-41 is -78.5 ° C, the boiling point of HCl is -84.9 ° C, and the boiling point of this azeotrope is about -73 ° C. And HCl form the highest azeotrope. The azeotropic composition under atmospheric pressure is about 55 mol% for HFC-41 and about 45 mol% for HCl. At other pressures, for example 2.0 MPa, the boiling point of the azeotropic mixture is about 4 ° C., and the azeotropic composition is about 53 mol% for HFC-41 and about 47 mol% for HCl.

このように、HFC−41とHClの2成分系には最高共沸混合物が存在するため、HFC−41とHClとの混合物を、たとえば大気圧下で蒸留しても、HFC−41とHClとのモル比(HFC−41/HCl)を約55/45以上に濃縮することができない。   Thus, since the highest azeotrope exists in the binary system of HFC-41 and HCl, even if the mixture of HFC-41 and HCl is distilled, for example, under atmospheric pressure, HFC-41 and HCl Cannot be concentrated to about 55/45 or more.

本発明のフルオロメタンの精製方法は、HFC−41とHClとの混合物中のHCl濃度が共沸組成より小さい場合、HFC−41とHClとを含む混合物を蒸留し、蒸留塔の塔頂からHFC−41を留出させ、蒸留塔の塔底からHFC−41とHClとの共沸混合
物を得ることを特徴とする。本発明の方法により、HClを実質的に含まないHFC−41、具体的にはHCl濃度が20wtppm以下のHFC−41を効率的に得ることができる。なお、HFC−41とHClとの混合物中のHCl濃度が共沸組成より大きい場合には、水洗浄などによりHCl濃度を低減させておくことが必要である。
In the method for purifying fluoromethane of the present invention, when the HCl concentration in the mixture of HFC-41 and HCl is smaller than the azeotropic composition, the mixture containing HFC-41 and HCl is distilled, and the HFC from the top of the distillation column is distilled. -41 is distilled, and an azeotropic mixture of HFC-41 and HCl is obtained from the bottom of the distillation column. By the method of the present invention, HFC-41 substantially free of HCl, specifically, HFC-41 having an HCl concentration of 20 wtppm or less can be efficiently obtained. When the HCl concentration in the mixture of HFC-41 and HCl is higher than the azeotropic composition, it is necessary to reduce the HCl concentration by washing with water or the like.

このような蒸留操作に使用できる蒸留装置は、通常の蒸留に必要な機能を備えていればよいが、より好ましくは棚段塔、充填塔などの精留装置を使用することが望ましい。また、連続蒸留またはバッチ蒸留のいずれの方法でも実施可能である。   A distillation apparatus that can be used for such a distillation operation may have a function necessary for normal distillation, but it is more preferable to use a rectification apparatus such as a plate column or a packed column. Further, it can be carried out by any method of continuous distillation or batch distillation.

蒸留の操作条件は、ユーティリティおよび要求される品質などにより種々の態様が可能であり、限定的なものでないが、蒸留塔の塔頂温度が低く成り過ぎないことを考慮すれば、操作圧力は0.1〜10MPa、より好ましくは0.5〜5MPaの範囲内であることが望ましい。この場合、塔頂温度は約−80〜60℃の範囲内となる。   Distillation operating conditions may vary depending on the utility and required quality, and are not limited. However, considering that the top temperature of the distillation column does not become too low, the operating pressure is 0. It is desirable that the pressure be in the range of 1 to 10 MPa, more preferably 0.5 to 5 MPa. In this case, the column top temperature is in the range of about −80 to 60 ° C.

上記のようにHFC−41とHClとの混合物を蒸留することにより、蒸留塔の塔頂から留出させたHFC−41中に含まれるHCl濃度は、通常20wtppm以下である。しかしながら、前述したように半導体用エッチングガスに用いる場合、酸成分(HCl、HFなど)の濃度は、好ましくは1.0wtppm以下、より好ましくは0.5wtppm以下であることが望まれている。   By distilling the mixture of HFC-41 and HCl as described above, the concentration of HCl contained in HFC-41 distilled from the top of the distillation column is usually 20 wtppm or less. However, as described above, when used for a semiconductor etching gas, the concentration of acid components (HCl, HF, etc.) is preferably 1.0 wtppm or less, more preferably 0.5 wtppm or less.

したがって本発明のフルオロメタンの精製方法は、塔頂から留出させたHFC−41を、水および/またはアルカリを含む処理剤に接触させて、HClを含む酸成分を除去する工程を含むことが好ましい。このような処理剤に用いることができるアルカリは、アルカリ水溶液でも、アルカリを含む固体材料(たとえば、ソーダライムなど)でもよい。好ましい処理剤としては、水またはアルカリ水溶液である。なお、アルカリ水溶液は、水酸化ナトリウム水溶液または水酸化カリウム水溶液が好ましく、アルカリ水溶液の濃度は0.01〜20%、好ましくは0.1〜10%の範囲内であることが望ましい。接触時間は特に限定されないが、接触温度は、HFC−41の水への溶解度がやや大きいことから、より低温領域が好ましく、具体的には5〜40℃の範囲内が望ましい。   Therefore, the method for purifying fluoromethane of the present invention comprises a step of contacting HFC-41 distilled from the top of the column with a treating agent containing water and / or alkali to remove an acid component containing HCl. preferable. The alkali that can be used for such a treatment agent may be an aqueous alkali solution or a solid material containing alkali (for example, soda lime). A preferable treating agent is water or an aqueous alkali solution. The alkaline aqueous solution is preferably a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, and the concentration of the alkaline aqueous solution is 0.01 to 20%, preferably 0.1 to 10%. Although the contact time is not particularly limited, the contact temperature is preferably in a lower temperature range because the solubility of HFC-41 in water is slightly high, and specifically, it is preferably in the range of 5 to 40 ° C.

上記のように、塔頂から留出したHFC−41を、水および/またはアルカリを含む処理剤に接触させることにより、HFC−41中のHCl濃度を1.0wtppm以下とすることができる。また、用いる処理剤によっては、HFC−41中の水分濃度が上昇することがあるが、その場合はモレキュラーシーブス(ゼオライト)などと接触させることにより水分濃度を5wtppm以下とすることができる。   As described above, the HFC-41 distilled from the top of the column is brought into contact with a treatment agent containing water and / or alkali, whereby the HCl concentration in the HFC-41 can be reduced to 1.0 wtppm or less. Depending on the treatment agent used, the water concentration in HFC-41 may increase. In this case, the water concentration can be reduced to 5 wtppm or less by contacting with molecular sieves (zeolite).

このようにして精製されたHFC−41中には、酸成分(HCl、HFなど)が1.0wtppm以下しか含まれず、高純度のHFC−41を得ることができる。なお、HFC−41中の酸成分の濃度は、イオンクロマトグラフィ−(IC)などの分析装置により測定することができる。   The purified HFC-41 contains only 1.0 wtppm or less of acid components (HCl, HF, etc.), and high purity HFC-41 can be obtained. In addition, the density | concentration of the acid component in HFC-41 can be measured with analyzers, such as ion chromatography (IC).

本発明の方法に用いることができるフルオロメタンの精製装置の一例をフロ−シートにて図1に示す。図1を用いて、本発明のフルオロメタンの精製方法をより詳細に説明する。   An example of a purification apparatus for fluoromethane that can be used in the method of the present invention is shown in FIG. 1 as a flow sheet. The method for purifying fluoromethane of the present invention will be described in more detail with reference to FIG.

まず、CH3ClとHFとをフッ素化触媒(たとえば、フッ化クロム)の存在下、反応
温度250℃で気相反応させ、HFC−41、HCl、CH3Cl、HFおよび微量の有
機不純物を含む反応生成物を得る。得られた反応生成物から、蒸留などにより塩化メチルおよびHFを除去し、主としてHFC−41およびHClを含む混合物(1)を得る。
First, CH 3 Cl and HF are reacted in a gas phase at a reaction temperature of 250 ° C. in the presence of a fluorination catalyst (for example, chromium fluoride), and HFC-41, HCl, CH 3 Cl, HF and a small amount of organic impurities are removed. A reaction product containing is obtained. Methyl chloride and HF are removed from the obtained reaction product by distillation or the like to obtain a mixture (1) mainly containing HFC-41 and HCl.

得られた混合物(1)を蒸留塔(2)に導入して蒸留操作を行う。この蒸留塔(2)の塔底部から、HFC−41とHClとの共沸混合物を塔底留出物(5)として取りだし、その一部を再沸蒸気(4)として蒸留塔の塔底部に戻す。また、蒸留塔(2)の塔頂から、実質的にHClを含まないHFC−41が塔頂留出物(3)として抜き出される。このようにして、前記混合物(1)中より、HClを効率的に除去することができる。このような操作は、バッチ式で行うことも可能であるが、連続操作により行なうことが好ましい。   The obtained mixture (1) is introduced into the distillation column (2) to perform a distillation operation. From the bottom of the distillation column (2), an azeotropic mixture of HFC-41 and HCl is taken out as a bottom distillate (5), and a part of the azeotrope is re-boiling vapor (4) at the bottom of the distillation column. return. Further, HFC-41 substantially free of HCl is extracted from the top of the distillation column (2) as a column top distillate (3). In this way, HCl can be efficiently removed from the mixture (1). Such an operation can be carried out batchwise, but is preferably carried out by a continuous operation.

蒸留塔(2)の理論段数および実段数ならびに還流比は、分離条件、塔効率などを考慮して決定し、混合物(1)は、計算上、塔頂部から留出するHClが最も少なくなる段数に供給することが好ましい。   The number of theoretical and actual stages and the reflux ratio of the distillation column (2) are determined in consideration of separation conditions, column efficiency, etc., and the mixture (1) is calculated to have the least number of stages of HCl distilled from the top of the column. It is preferable to supply to.

塔頂より抜き出された塔頂留出物(3)を酸成分処理装置(6)に導入し、たとえば水酸化カリウム水溶液(5%)と接触させることにより、HFC−41中の酸成分がさらに低減された高純度なHFC−41(7)が得られる。   The column top distillate (3) extracted from the column top is introduced into the acid component treatment device (6) and brought into contact with, for example, an aqueous potassium hydroxide solution (5%), whereby the acid component in HFC-41 is converted. Further reduced HFC-41 (7) is obtained.

上記のようにして得られる酸成分(HCl、HFなど)の濃度が1.0wtppm以下である高純度HFC−41の単独ガス、またはこの高純度HFC−41と他のガス(たとえば、He、N2、Ar、O2、NF3など)との混合ガス(以下、本明細書では、単独ガ
スおよび混合ガスともに「フルオロメタン製品」と称する。)は、半導体デバイス製造プロセスのエッチング工程において使用されるエッチングガスとして用いることができる。
A single gas of high purity HFC-41 having a concentration of acid components (HCl, HF, etc.) obtained as described above of 1.0 wtppm or less, or this high purity HFC-41 and another gas (for example, He, N, etc.) 2 , Ar, O 2 , NF 3, and the like (hereinafter, both single gas and mixed gas are referred to as “fluoromethane products”) are used in an etching process of a semiconductor device manufacturing process. It can be used as an etching gas.

より具体的には、本発明のフルオロメタン製品からなるエッチングガスは、LSIまたはTFTなどの半導体デバイスの製造プロセスにおいて、CVD法、スパッタリング法または蒸着法などにより形成された薄膜などをエッチングするために、プラズマエッチング、マイクロ波エッチングなどの各種ドライエッチング条件で用いることができる。   More specifically, the etching gas comprising the fluoromethane product of the present invention is used to etch thin films formed by CVD, sputtering or vapor deposition in the manufacturing process of semiconductor devices such as LSI or TFT. It can be used under various dry etching conditions such as plasma etching and microwave etching.

高純度HFC−41に混合することができるガスは特に限定されず、用途に応じて適宜選択され、1種だけでなく2種以上のガスを混合してもよい。混合量についても同様に特に限定されず、用途に応じて適宜調整することができる。   The gas that can be mixed with the high-purity HFC-41 is not particularly limited, and may be appropriately selected depending on the application, and not only one kind but also two or more kinds may be mixed. Similarly, the mixing amount is not particularly limited, and can be appropriately adjusted according to the application.

〔実施例〕
以下、実施例により本発明をより具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
〔Example〕
EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples.

(組成の分析)
塔底留出物については、吸収液として純水を入れたガス洗浄ビンに留出ガスを流通させ、吸収液を容量分析用水酸化ナトリウムで中和滴定することにより、留出ガス中のHClを定量し、ガス洗浄ビン出口ガスの体積を測定することによりHFC−41を定量して、これらの結果から組成比を求めた。
(Analysis of composition)
As for the bottom distillate, HCl in the distillate gas is removed by passing the distillate gas through a gas washing bottle containing pure water as the absorbent and neutralizing the absorbent with sodium hydroxide for volumetric analysis. The HFC-41 was quantified by quantifying and measuring the volume of the gas cleaning bottle outlet gas, and the composition ratio was determined from these results.

塔頂留出物については、吸収液として超純水を入れたガス洗浄ビンに留出ガスを流通させ、吸収液をイオンクロマトグラフィーで分析することによりClを定量し、ガス洗浄ビン出口ガスの体積を測定することによりHFC−41を定量して、これらの結果からHCl濃度を求めた。   For the column top distillate, Cl was quantified by circulating the distillate gas through a gas washing bottle containing ultrapure water as an absorbing solution and analyzing the absorbing solution by ion chromatography. HFC-41 was quantified by measuring the volume, and the HCl concentration was determined from these results.

イオンクロマトグラフィーによる測定条件
装置:島津製作所製HIC−SP
カラム:昭和電工(株)製Shodex IC SI−90 4E
(フルオロメタンの精製)
凝縮器を備えた直径150mmφ、理論段数20段(実段数36段)の蒸留塔を用いて、HFC−41およびHClからなる混合物(組成はモル比でHFC−41/HCl=80/20)を、常温で理論段数10段目に34.4g/hで供給し、操作圧力約2.0MPaで蒸留操作を行った。塔頂温度を−5℃になるように制御し、塔頂および塔底から、留出物をそれぞれ18.7g/hおよび15.7g/hで抜き出した。この蒸留操作において、還流比は10となるように制御した。蒸留塔内が安定した後、塔底留出物をサンプリングして組成を分析したところ、HFC−41とHClとのモル比は55/45(HFC−41/HCl)であった。同様に、塔頂留出物をサンプリングして組成を分析したところ、HFC−41中のHCl濃度は10wtppmであった。
Measurement conditions by ion chromatography Device: HIC-SP manufactured by Shimadzu Corporation
Column: Shodex IC SI-90 4E manufactured by Showa Denko KK
(Purification of fluoromethane)
Using a distillation column having a diameter of 150 mmφ and a theoretical plate number of 20 (36 actual plates) equipped with a condenser, a mixture of HFC-41 and HCl (composition is HFC-41 / HCl = 80/20 in molar ratio). The solution was supplied at 34.4 g / h to the theoretical plate number 10 at room temperature, and the distillation operation was performed at an operation pressure of about 2.0 MPa. The top temperature was controlled to be −5 ° C., and distillates were withdrawn from the top and bottom at 18.7 g / h and 15.7 g / h, respectively. In this distillation operation, the reflux ratio was controlled to be 10. After the inside of the distillation column was stabilized, the bottom distillate was sampled and the composition was analyzed. As a result, the molar ratio of HFC-41 to HCl was 55/45 (HFC-41 / HCl). Similarly, when the composition was analyzed by sampling the top distillate, the HCl concentration in HFC-41 was 10 wtppm.

これらの分析結果から、HFC−41より低い沸点を有するHCl(HFC−41の大気圧下沸点−78.5℃>HClの大気圧下沸点−84.9℃)が塔底部に回収されること、HFC−41とHClは最高共沸混合物を形成することが明らかとなった。   From these analysis results, HCl having a boiling point lower than that of HFC-41 (boiling point of HFC-41 under atmospheric pressure−78.5 ° C.> boiling point of HCl under atmospheric pressure−84.9 ° C.) is recovered at the bottom of the column. HFC-41 and HCl were found to form the highest azeotrope.

さらに、塔頂留出物を温度約5℃で2%水酸化カリウム水溶液に接触させた後、冷却捕集して液をサンプリングし、HFC−41中のHCl濃度をイオンクロマトグラフィ−により求めたところ、HCl濃度は0.5wtppmであり、高純度のHFC−41が得られた。   Furthermore, after the column top distillate was brought into contact with a 2% aqueous potassium hydroxide solution at a temperature of about 5 ° C., it was collected by cooling, the liquid was sampled, and the HCl concentration in HFC-41 was determined by ion chromatography. The HCl concentration was 0.5 wtppm, and high-purity HFC-41 was obtained.

本発明に用いることができるフルオロメタンの精製装置を示す概略図である。It is the schematic which shows the refiner | purifier of the fluoromethane which can be used for this invention.

符号の説明Explanation of symbols

1 フィード液(混合物)
2 蒸留塔
3 塔頂留出物
4 再沸蒸気
5 塔底留出物
6 酸成分処理装置
7 高純度フルオロメタン
1 Feed liquid (mixture)
2 Distillation column 3 Top distillate 4 Reboiling steam 5 Bottom distillate 6 Acid component treatment equipment 7 High purity fluoromethane

Claims (7)

フルオロメタンと塩化水素との共沸混合物。   An azeotropic mixture of fluoromethane and hydrogen chloride. フロオロメタンと塩化水素とを含む混合物を蒸留し、蒸留塔の塔頂からフルオロメタンを留出させ、蒸留塔の塔底からフルオロメタンと塩化水素との共沸混合物を得ることを特徴とするフルオロメタンの精製方法。   Fluoromethane characterized by distilling a mixture containing fluoromethane and hydrogen chloride, distilling fluoromethane from the top of the distillation column, and obtaining an azeotropic mixture of fluoromethane and hydrogen chloride from the bottom of the distillation column Purification method. 0.1〜10.0MPaの範囲の操作圧力において蒸留することを特徴とする請求項2に記載のフルオロメタンの精製方法。   The method for purifying fluoromethane according to claim 2, wherein the distillation is carried out at an operating pressure in the range of 0.1 to 10.0 MPa. 前記蒸留塔の塔頂から留出させたフルオロメタン中に含まれる塩化水素濃度が20wtppm以下であることを特徴とする請求項2または3に記載のフルオロメタンの精製方法。   The method for purifying fluoromethane according to claim 2 or 3, wherein the concentration of hydrogen chloride contained in the fluoromethane distilled from the top of the distillation column is 20 wtppm or less. 前記蒸留塔の塔頂から留出させたフルオロメタンを、水および/またはアルカリを含む処理剤に接触させて、塩化水素を含む酸成分を除去する工程を含むことを特徴とする請求項2〜4のいずれかに記載のフルオロメタンの精製方法。   The method comprises contacting the fluoromethane distilled from the top of the distillation column with a treatment agent containing water and / or alkali to remove an acid component containing hydrogen chloride. 5. The method for purifying fluoromethane according to any one of 4 above. 請求項2〜5のいずれかに記載の方法により得られるフルオロメタンであって、塩化水素濃度が1.0wtppm以下であるフルオロメタンを含むことを特徴とするフルオロメタン製品。   A fluoromethane product obtained by the method according to any one of claims 2 to 5, comprising fluoromethane having a hydrogen chloride concentration of 1.0 wtppm or less. 請求項6に記載のフルオロメタン製品を含むことを特徴とするエッチングガス。   An etching gas comprising the fluoromethane product according to claim 6.
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