Method for producing purified trans-1, 2-difluoroethylene (HFO-1132 (E)), and composition containing HFO-1132 (E)

Abstract

The present invention provides a method for efficiently purifying HFO-1132 (E). Specifically disclosed is a method for producing purified HFO-1132 (E), which comprises an extraction and distillation step for bringing a composition containing 1, 1, 1-trifluoroethane (HFC-143a) and trans-1, 2-difluoroethylene (HFO-1132 (E)) into contact with a solvent containing an amine to obtain a composition in which HFC-143a has been reduced from the composition.

Description

Technical Field

[0001] The present invention relates to a method for producing purified trans-1,2-difluoroethylene (HFO-1132(E)) and a composition containing HFO-1132(E). Background Art

[0002] HFO-1132(E) has a low global warming potential (GWP) and is therefore attracting attention as a refrigerant to replace difluoromethane (HFC-32) and 1,1,1,2,2-pentafluoroethane (HFC-125), which are greenhouse gases.

[0003] Patent Document 1 discloses, regarding the present invention, "a method for producing purified HFO-1132(E) and / or HFO-1123, comprising an extractive distillation step, wherein an azeotropic composition or an azeotrope-like composition containing difluoromethane (HFC-32) and further containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or 1,1,2-trifluoroethylene (HFO-1123) is contacted with an extraction solvent to obtain a composition in which the HFC-32 content of the azeotropic composition or the azeotrope-like composition is reduced."

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2021 / 2611889 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] An object of the present invention is to provide a method for efficiently purifying HFO-1132(E) and a composition containing HFO-1132(E).

[0009] Technical solutions to problems

[0010] The present invention includes, for example, the inventions described in the following items.

[0011] Item 1. A method for producing purified HFO-1132(E), comprising an extractive distillation step in which a composition comprising 1,1,1-trifluoroethane (HFC-143a) and trans-1,2-difluoroethylene (HFO-1132(E)) is contacted with a solvent containing an amine to obtain a composition in which the HFC-143a content of the composition is reduced.

[0012] Item 2. The production method according to Item 1, further comprising a distillation step of distilling the composition obtained in the extractive distillation step to separate the composition containing the HFO-1132(E) as a main component and a composition containing the amine-containing solvent as a main component.

[0013] Item 3. The production method according to Item 1 or 2, wherein the extractive distillation step is performed at a pressure of 0.05 to 5 MPaG (gauge pressure) using a first distillation column for performing the extractive distillation step.

[0014] Item 4. The production method according to Item 2 or 3, wherein the distillation step is performed at a pressure of 0.05 to 3 MPaG (gauge pressure) using a second distillation column for performing the distillation step.

[0015] Item 5. The production method according to any one of Items 1 to 4, further comprising a solvent recovery step, in which the amine-containing solvent used in the extractive distillation step is recovered and the recovered amine-containing solvent is recycled in the extractive distillation step.

[0016] Item 6. The production method according to any one of Items 1 to 5 above, wherein the amine is represented by the general formula: NR 1 R 2 R 3 express,

[0017] 〔where R 1 、R 2 and R 3 are the same or different and represent hydrogen or a hydrocarbon group having 1 to 3 carbon atoms which may have a substituent. 1 、R 2 and R 3 The case where all of it is hydrogen. 〕

[0018] Item 7. The production method according to any one of Items 1 to 6, wherein the amine has a normal boiling point of -10 to 160°C.

[0019] Item 8. The production method according to any one of Items 1 to 7 above, wherein the amine is at least one selected from the group consisting of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, monoisopropylamine, and diisopropylamine.

[0020] Item 9. The production method according to Item 1, further comprising a distillation step in which the composition obtained in the extractive distillation step is distilled to separate the composition containing the HFO-1132(E) as a main component and the composition containing the amine-containing solvent as a main component.

[0021] The extractive distillation step is performed at a pressure of 0.05 to 5 MPaG (gauge pressure) using the first distillation column for performing the extractive distillation step.

[0022] The distillation step is performed at a pressure of 0.05 to 3 MPaG (gauge pressure) using a second distillation column for performing the distillation step.

[0023] The method further comprises a solvent recovery step, in which the solvent containing amines used in the extraction and distillation step is recovered and the recovered solvent containing amines is recycled in the extraction and distillation step.

[0024] The amine is at least one selected from the group consisting of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, monoisopropylamine, and diisopropylamine.

[0025] Item 10. A composition comprising trans-1,2-difluoroethylene (HFO-1132(E)), 1,1,1-trifluoroethane (HFC-143a), and an amine, wherein the total concentration of the three components is 99.5% by mass or more relative to the entire composition, the content of the HFC143a is greater than 0% by mass and less than 0.4% by mass relative to the entire composition, and the content of the amine is greater than 0% by mass and less than 0.1% by mass relative to the entire composition.

[0026] Item 11. A composition comprising trans-1,2-difluoroethylene (HFO-1132(E)) and an amine, wherein the total concentration of the two components is 99.5% by mass or more relative to the entire composition, and the content of the amine is greater than 0% by mass and less than 0.1% by mass relative to the entire composition.

[0027] Effects of the Invention

[0028] According to the present invention, HFO-1132(E) can be purified efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram showing an overview of the process of Example 1. DETAILED DESCRIPTION

[0030] The present inventors have conducted intensive studies and have discovered that HFO-1132(E) can be efficiently purified by a production method including an extractive distillation step of contacting a composition containing HFC-143a and HFO-1132(E) with a solvent containing an amine to obtain a composition in which the HFC-143a content is reduced.

[0031] The present invention has been completed as a result of further research based on such findings.

[0032] In this specification, the numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit (ie, "above, below").

[0033] In this specification, an azeotropic composition refers to a composition in which there is no difference in composition between a liquid phase and a gas phase at a certain pressure and they behave like a single substance.

[0034] In this specification, an azeotrope-like composition refers to a composition that, among compositions capable of forming an azeotropic composition, has a composition similar to that of an azeotropic composition and exhibits behavior similar to that of an azeotropic composition. Azeotrope-like compositions can be distilled and / or refluxed with little change in composition. Therefore, azeotrope-like compositions can be considered essentially equivalent to azeotropic compositions. Furthermore, one characteristic of an azeotrope-like composition is that the pressure difference between the boiling point curve and the dew point curve on a pressure-composition diagram is within 5%.

[0035] In this specification, the normal boiling point refers to the boiling point at a standard atmospheric pressure of 1013.25 hPa.

[0036] In this specification, gauge pressure refers to relative pressure relative to atmospheric pressure, and is the pressure difference obtained by subtracting atmospheric pressure from absolute pressure. In this specification, gauge pressure is indicated by "G" such as MPaG. On the other hand, when "G" is not indicated, it refers to atmospheric pressure.

[0037] In this specification, the "purity" of a refrigerant refers to the component ratio (mol % or mass %) obtained by quantitative analysis using gas chromatography.

[0038] In this specification, the main component refers to a component whose content is preferably 85 mol% to 99.9 mol%, more preferably 90 mol% to 99.9 mol%, further preferably 95 mol% to 99.9 mol%, and particularly preferably 99 mol% to 99.9 mol%.

[0039] As used herein, extractive distillation refers to a distillation operation in which an extraction solvent is added to a mixture of two or three components with very similar normal boiling points and a specific volatility (relative volatility) close to 1, or to a mixture with an azeotropic composition, to prepare an extraction mixture. This distillation operation reduces the relative volatility of the original two or three components to a value away from 1, thereby facilitating separation. However, if the relative volatility is 1, separation by distillation is impossible.

[0040] In this specification, the specific volatility (α) refers to the value obtained when the molar fraction of the liquid component A is x, when the composition containing at least the target component A and the target component B is in a gas-liquid equilibrium state. A, the molar fraction of liquid component B is x B , let the molar fraction of the gas phase component A in equilibrium with the liquid phase be y A The molar fraction of gas phase component B is set to y B When , the specific volatility of component A relative to component B is defined as:

[0041] α A→B =(y A / x A ) / (y B / x B ).

[0042] In this specification, when component A is HFC-143a and component B is HFO-1132(E), the relative volatility of component A to component B, that is, the relative volatility of HFC-143a to HFO-1132(E) is expressed as α 143a→1132(E) .

[0043] The present invention includes the following embodiments.

[0044] The production method of the present invention is a method for producing purified HFO-1132(E), comprising an extractive distillation step, wherein a composition containing HFC-143a and HFO-1132(E) is contacted with a solvent containing an amine to obtain a composition in which the HFC-143a content is reduced. The production method of the present invention is particularly preferably applied when the composition containing HFC-143a and HFO-1132(E) (also referred to as an "extractive distillation composition") is an azeotropic or azeotrope-like composition.

[0045] (Extraction and distillation process)

[0046] The extractive distillation step in the production method of the present invention is a step of contacting a composition containing HFC-143a and HFO-1132(E) (the extractive distillation composition) with a solvent containing an amine to obtain a composition in which the HFC-143a content has been reduced. In other words, the extractive distillation step is a step of extractively distilling the composition containing HFC-143a and HFO-1132(E) (the extractive distillation composition) in the presence of a solvent containing an amine to obtain a composition in which the HFC-143a content has been reduced. In the present invention, the term "reduction" in the extractive distillation step means reducing the content of the specific compound (HFC-143a) in the extractive distillation composition.

[0047] The extractive distillation composition preferably contains HFC-143a and HFO-1132(E) at a combined total concentration of preferably 99.5% by mass or greater, more preferably 99.7% by mass or greater, even more preferably 99.8% by mass or greater, and even more preferably 99.9% by mass or greater. For example, in the production process of HFO-1132(E), a composition (particularly an azeotropic composition or an azeotrope-like composition) containing HFC-143a and HFO-1132(E) at the combined total concentrations described above can be used after removing easily separable by-products through a preliminary separation step (such as an optional distillation step) as needed.

[0048] The extractive distillation composition is preferably composed of only HFO-1132(E) and HFC-143a, but may contain unavoidable impurities depending on the conditions of the production process of the extractive distillation composition.

[0049] Furthermore, HFC-143a (normal boiling point: -47.2°C) and HFO-1132(E) (normal boiling point: -53.0°C) exhibit azeotropy or azeotrope-like properties. The azeotropic composition or azeotrope-like composition of HFC-143a and HFO-1132(E) has a boiling point lower than the boiling point of either HFC-143a or HFO-1132(E) (at 0.1013 MPa, the azeotropic composition is HFC-143a = 0.94, and the temperature is -53.1°C). The composition of the extractive distillation composition provided to the extractive distillation step is preferably 80% to 99.999% and more preferably 90% to 99.999% in terms of the molar ratio of HFO-1132(E).

[0050] The extractive distillation step is preferably a step of bringing the extractive distillation composition into contact with a solvent containing an amine to perform extractive distillation, thereby obtaining a composition containing HFO-1132(E) and substantially containing no HFC-143a.

[0051] In this specification, “substantially free of HFC-143a” means that the HFC-143a content in the composition obtained in the extractive distillation step is preferably less than 1% by mass, more preferably less than 0.5% by mass, and particularly preferably less than 0.1% by mass.

[0052] In the extractive distillation step, a solvent containing amine is used as the extraction solvent.

[0053] The above-mentioned amine can be any liquid amine that can serve as an extraction solvent, and is preferably represented by the general formula: NR 1 R 2 R 3 Represents [where R1 、R 2 and R 3 The same or different, represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms which may have a substituent. However, R 1 、R 2 and R 3 The amine-containing solvent in the present invention preferably consists solely of amines (alone or as a mixture of amines), but may contain unavoidable impurities as long as they do not affect the extraction and distillation process. Hereinafter, the "amine-containing solvent" essentially refers to amines and is also referred to simply as the "extraction solvent."

[0054] Furthermore, the amine preferably has a normal boiling point of -10 to 160°C.

[0055] The amine is preferably at least one selected from monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, monoisopropylamine, and diisopropylamine. The Cas No. and standard boiling point of these amines are shown in Table 1 below.

[0056] [Table 1]

[0057] Substance name Cas No. Standard boiling point (℃) Monomethylamine 74－89－5 －6 dimethylamine 124－40－3 7.0 Trimethylamine 75－50－3 2.9 Monoethylamine 75－04－7 38 Diethylamine 109－89－7 56 Triethylamine 121－44－8 90 Monopropylamine 107－10－8 48 di-n-propylamine 142－84－7 110 Tri-n-propylamine 102－69－2 156 Monoisopropylamine 75－31－0 32 diisopropylamine 108－18－9 84

[0058] These amines can be used alone or in combination of two or more.

[0059] The normal boiling point temperature range in the extractive distillation step described above is sufficient as long as the temperature difference between the extraction solvent and the compound to be separated in the extractive distillation step is such that separation by simple distillation, steam stripping, or the like is achieved, typically a temperature difference of 20°C or greater. If the normal boiling point is too high, the extraction solvent itself may decompose. Therefore, from the perspective of efficient extractive distillation, the normal boiling point of the extraction solvent is preferably 30-135°C, more preferably 35-120°C, even more preferably 40-100°C, and particularly preferably 50-90°C.

[0060] The amount of the extraction solvent used in the extractive distillation step is preferably 1 to 30 times the molar equivalent of the extractive distillation composition supplied to the extractive distillation column, and more preferably 5 to 25 times the molar equivalent.

[0061] The HFC-143a concentration in the extractive distillation composition during the extractive distillation step is preferably 15 mol% or less, more preferably 10 mol% or less. The lower limit of the HFC-143a concentration in the extractive distillation composition during the extractive distillation step is preferably 0.001 mol% or more, more preferably 0.01 mol% or more, and even more preferably 0.1 mol% or more.

[0062] The extractive distillation column used in the extractive distillation step preferably has 10 or more theoretical plates, more preferably 20 or more. Furthermore, from an economical perspective, the extractive distillation column used in the extractive distillation step preferably has 60 or less theoretical plates, more preferably 50 or less theoretical plates.

[0063] In the extractive distillation step, the extractive solvent is preferably supplied to the upper stage of the extractive distillation column. Furthermore, the extractive solvent used in the extractive distillation step is preferably recovered and recycled in the extractive solvent recovery step described below.

[0064] In the extractive distillation step, the extractive distillation is preferably performed at a pressure (the pressure in the first distillation column) of 0.05 to 5 MPaG (gauge pressure). The lower limit of the pressure is preferably 0.05 MPaG, more preferably 0.1 MPaG, even more preferably 0.25 MPaG, and particularly preferably 0.5 MPaG. The upper limit of the pressure is preferably 5 MPaG, more preferably 4 MPaG, even more preferably 3 MPaG, and particularly preferably 2 MPaG.

[0065] The extractive distillation step can be performed discontinuously or continuously, but is preferably performed continuously from an industrial perspective. Furthermore, by repeating the extractive distillation, the distillate can be purified to a high purity.

[0066] When HFC-143a is distilled from the extractive distillation composition in the extractive distillation step, it is preferable to use an extractive solvent having a relative volatility (specific volatility) of HFC-143a relative to HFO-1132(E) of 1.1 or greater, preferably 1.2 or greater, when adding the extractive solvent. This increases the gas phase molar fraction of HFC-143a, increasing the amount of HFC-143a in the gas phase, allowing HFC-143a to be separated from the top of the extractive distillation column, and obtaining the extractive solvent and HFO-1132(E) from the bottom of the extractive distillation column.

[0067] (Extraction solvent recovery process)

[0068] The production method of the present invention preferably includes an extraction solvent recovery step of recovering the extraction solvent used in the extraction and distillation step and recycling the recovered extraction solvent in the extraction and distillation step.

[0069] The extraction solvent recovery step includes a distillation step (hereinafter also referred to as the "distillation step") of distilling the composition obtained in the extraction distillation step to separate it into a composition containing HFO-1132(E) as a main component and a composition containing the extraction solvent as a main component. This can be carried out by recovering the extraction solvent from the composition containing the extraction solvent as a main component and recycling it in the extraction distillation step.

[0070] The number of theoretical plates of the solvent recovery column (second distillation column) used in the distillation step is preferably 5 or more, more preferably 10 or more. Furthermore, from an economical perspective, the number of theoretical plates of the solvent recovery column is preferably 40 or less, more preferably 30 or less.

[0071] In the distillation step, the distillation pressure is preferably 0.05 to 3 MPaG (gauge pressure). The lower limit of the pressure is preferably 0.05 MPaG, more preferably 0.1 MPaG. The upper limit of the pressure is preferably 3 MPaG, more preferably 2.5 MPaG.

[0072] Through the distillation step, a composition containing HFO-1132(E) as a main component can be separated from the top of the solvent recovery column, and a composition containing the extraction solvent as a main component can be obtained from the bottom of the solvent recovery column.

[0073] The extraction solvent recovery step can be carried out by recovering the extraction solvent from the composition containing the extraction solvent as a main component obtained from the column bottom in the distillation step and recycling it to the extraction distillation step. Furthermore, the extraction solvent recovered from the column bottom may be further subjected to an arbitrary separation step such as rectification to remove impurities, as needed, before being recycled to the extraction distillation step.

[0074] The distillation step can be performed in a batch operation or a continuous operation, but is preferably performed in a continuous operation from an industrial viewpoint.

[0075] The production method of the present invention preferably includes an extractive distillation step and an extraction solvent recovery step, and more preferably includes an optional prior distillation step, an extractive distillation step, and an extraction solvent recovery step for improving the purity of the extractive distillation composition.

[0076] (Composition containing HFO-1132(E), HFC-143a and amine)

[0077] The present invention includes a composition containing trans-1,2-difluoroethylene (HFO-1132(E)), 1,1,1-trifluoroethane (HFC-143a), and an amine (hereinafter referred to as "refrigerant 1"). The type of amine is the same as that described in the extraction solvent section above.

[0078] Refrigerant 1 is a composition containing HFO-1132(E), HFC-143a, and an amine, wherein the total concentration of these three components is 99.5% by mass or greater relative to the overall composition, the HFC-143a content is greater than 0% by mass and less than 0.4% by mass relative to the overall composition, and the amine content is greater than 0% by mass and less than 0.1% by mass relative to the overall composition. A content exceeding 0% by mass may also be expressed as 0.01% by mass or greater.

[0079] The total concentration of the three components in the refrigerant 1 is preferably 99.7% by mass or more, more preferably 99.8% by mass or more, and even more preferably 99.9% by mass or more, based on the entire composition.

[0080] The refrigerant 1 is particularly preferably composed of only HFO-1132(E), HFC-143a, and amines, but may contain inevitable impurities.

[0081] The use of the refrigerant 1 is not limited, and the refrigerant 1 can be suitably used as, for example, a refrigerant for air conditioning, a heat transfer medium, a refrigerant for automobile air conditioning, and the like.

[0082] (Purified composition containing HFO-1132(E))

[0083] In the present invention, the purified HFO-1132(E)-containing composition includes a composition containing HFO-1132(E) and an amine (hereinafter also referred to as "Composition 1"), wherein the type of the amine is the same as that described in the above-mentioned extraction solvent section.

[0084] Composition 1 is a composition containing HFO-1132(E) and an amine, wherein the total concentration of these two components is 99.5% by mass or greater relative to the total composition, and the content of the amine is greater than 0% by mass and less than 0.1% by mass relative to the total composition. Furthermore, Composition 1 is a composition obtained by the production method of the present invention, wherein a trace amount of the extraction solvent (amine) remains in the purified HFO-1132(E)-containing composition. References exceeding 0% by mass may also be expressed as 0.01% by mass or greater.

[0085] The total concentration of the two components in the composition 1 is preferably 99.7% by mass or more, more preferably 99.8% by mass or more, and even more preferably 99.9% by mass or more, relative to the composition 1.

[0086] Composition 1 is particularly preferably composed of only HFO-1132(E) and amine, but may contain inevitable impurities.

[0087] The use of the composition 1 is not limited, and the composition 1 can be suitably used as, for example, a leak detector, a stabilizer, a tracer, etc. when used as a refrigerant.

[0088] Example

[0089] The present invention will be described in detail below with reference to the following examples, but the present invention is not limited to these examples.

[0090] In the examples, the concentrations of the components such as HFO-1132(E) were measured using the following measuring apparatus and conditions.

[0091] Measurement device: Gas chromatography (using FID detector)

[0092] Calculation method of concentration of each component:

[0093] HFO-1132(E) concentration = number of moles of HFO-1132(E) / (number of moles of HFO-1132(E) + number of moles of HFC-143a)

[0094] HFC-143a concentration = number of moles of HFC-143a / (number of moles of HFO-1132(E) + number of moles of HFC-143a)

[0095] Examples 1 to 4 and Comparative Examples 1 to 6

[0096] To a composition containing 80 mol% of HFO-1132(E) and 20 mol% of HFC-143a, 5 times the mol of each solvent was added to the above composition, and the specific volatility α of HFC-143a to HFO-1132(E) at 15°C was measured. 143a→1132(E) .

[0097] In Example 1, monomethylamine was used as the solvent, with a specific volatility of α 143a→1132(E) In Example 2, monoethylamine was used as the solvent, and the volatility α 143a→1132(E) In Example 3, mono-n-propylamine was used as the solvent, with a specific volatility of α 143a→1132(E) In Example 4, monoisopropylamine was used as the solvent, with a specific volatility of α 143a→1132(E) In Comparative Example 1, methanol was used as the solvent, and the volatility α 143a→1132(E) In Comparative Example 2, diethyl ether was used as the solvent, and the volatility α 143a→1132(E) In Comparative Example 3, n-hexane was used as the solvent, and the volatility α 143a→1132(E) In Comparative Example 4, methyl isobutyl ketone (MIBK) was used as the solvent, and the volatility α 143a→1132(E) In Comparative Example 5, acetonitrile was used as the solvent, and the volatility α 143a→1132(E) In Comparative Example 6, ethyl acetate was used as the solvent, and the volatility α143a→1132(E) is 1.2.

[0098] The results are summarized below.

[0099] [Table 2]

[0100]

[0101] From the above results, it can be seen that amines such as monomethylamine, monoethylamine, mono-n-propylamine, and monoisopropylamine are effective as extraction solvents.

[0102] Example 5

[0103] according to Figure 1 The flow chart shown uses an extractive distillation composition containing HFO-1132(E) and HFC-143a as a raw material and monoisopropylamine as an extraction solvent to produce purified HFO-1132(E) through a process including an extractive distillation step and an extraction solvent recovery step.

[0104] (Extraction and distillation process)

[0105] The extractive distillation composition was supplied to the extractive distillation column, which had 50 theoretical plates, at a rate of 9.8 mol / hr from the 15th stage from the top. The extraction solvent (monoisopropylamine) was supplied at a rate of 206 mol / hr from the 4th stage of the extractive distillation column. The operating pressure of the extractive distillation column was 0.45 MPaG, and the column top temperature was -12°C.

[0106] (Extraction solvent recovery process)

[0107] The bottoms liquid extracted from the extractive distillation step was fed to the 15th stage from the top of an extractive solvent recovery tower (hereinafter referred to as the "solvent recovery tower") with 30 theoretical stages. HFO-1132(E) product was recovered from the top of the tower at a purity of 99.99%. The solvent recovery tower operated at a pressure of 0.6 MPaG and a top temperature of -5°C.

[0108] The bottom liquid (monoisopropylamine flow rate: 206 mol / hr) containing monoisopropylamine extracted from the bottom of the recovery tower was recycled in the extraction distillation step.

[0109] about Figure 1 The material balance of Example 5 in the process of F1 is as follows: HFO-1132(E) is 9.4 mol / hr, HFC-143a is 0.4 mol / hr, and monoisopropylamine is 0 mol / hr. In F2, HFO-1132(E) is 9.5 mol / hr, HFC-143a is 6×10 -5mol / hr, monoisopropylamine is 206.0mol / hr. In F3, HFO-1132(E) is 2×10 -5 mol / hr, HFC-143a is 0.4 mol / hr, monoisopropylamine is 2×10 -6 mol / hr. In F4, HFO-1132(E) is 0.1 mol / hr, HFC-143a is 6×10 -5 mol / hr, monoisopropylamine is 206.0mol / hr. In F5, HFO-1132(E) is 9.4mol / hr, HFC-143a is 6×10 -5 mol / hr, monoisopropylamine is 2×10 -10 The material balance of Example 5 is summarized in Table 3 below.

[0110] [Table 3]

[0111]

[0112] In the amine-containing solvents shown in Examples 1 to 4, the relative volatility α of HFC-143a to HFO-1132(E) is 143a→1132(E) The values ​​were all between 1.6 and 1.8, significantly higher than those in the comparative examples (1.2 or less). Furthermore, the HFC-143a concentration in the gas phase reached over 50%, demonstrating a significant improvement in separation efficiency. Therefore, the process of the present invention, which uses an amine-containing solvent for extractive distillation, is highly effective in separating HFC-143a and HFO-1132(E).

[0113] Explanation of symbols

[0114] 1. Extractive distillation column

[0115] 2.Solvent recovery tower.

Claims

1. A method for producing purified HFO-1132(E), characterized by: The invention comprises an extractive distillation step, wherein a composition containing 1,1,1-trifluoroethane (HFC-143a) and trans-1,2-difluoroethylene (HFO-1132(E)) is contacted with a solvent containing an amine to obtain a composition in which the HFC-143a is reduced.

2. The manufacturing method according to claim 1, wherein: The method further includes a distillation step of distilling the composition obtained in the extractive distillation step to separate the composition into a composition containing the HFO-1132(E) as a main component and a composition containing the amine-containing solvent as a main component.

3. The manufacturing method according to claim 1, wherein: The extractive distillation step is performed at a pressure of 0.05 to 5 MPaG (gauge pressure) using a first distillation column for performing the extractive distillation step.

4. The manufacturing method according to claim 2, wherein: The distillation step is performed at a pressure of 0.05 to 3 MPaG (gauge pressure) using a second distillation column for performing the distillation step.

5. The manufacturing method according to claim 1, wherein: Also includes: A solvent recovery step includes recovering the amine-containing solvent used in the extractive distillation step and recycling the recovered amine-containing solvent in the extractive distillation step.

6. The manufacturing method according to claim 1, wherein: The amine is of the general formula: NR 1 R 2 R 3 express, Where R 1 、R 2 and R 3 are the same or different and represent hydrogen or a hydrocarbon group having 1 to 3 carbon atoms which may have a substituent, excluding R 1 、R 2 and R 3 All hydrogen.

7. The manufacturing method according to claim 1, wherein: The amine has a normal boiling point of -10 to 160°C.

8. The manufacturing method according to claim 1, wherein: The amine is at least one selected from the group consisting of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, monoisopropylamine and diisopropylamine.

9. The manufacturing method according to claim 1, wherein: The method further includes a distillation step, wherein the composition obtained in the extractive distillation step is distilled to separate the composition containing the HFO-1132(E) as a main component and the composition containing the amine-containing solvent as a main component. The extractive distillation step is performed using a first distillation column for performing the extractive distillation step at a pressure of 0.05 to 5 MPaG (gauge pressure). The distillation step is performed at a pressure of 0.05 to 3 MPaG (gauge pressure) using a second distillation column for performing the distillation step. The method further comprises a solvent recovery step, wherein the solvent containing amines used in the extraction and distillation step is recovered and the recovered solvent containing amines is recycled in the extraction and distillation step. The amine is at least one selected from the group consisting of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, monoisopropylamine and diisopropylamine.

10. A composition, characterized in that: Contains trans-1,2-difluoroethylene (HFO-1132(E)), 1,1,1-trifluoroethane (HFC-143a) and amines. The total concentration of the three components is 99.5% by mass or more relative to the entire composition, the content of HFC143a is greater than 0% by mass and less than 0.4% by mass relative to the entire composition, and the content of the amine is greater than 0% by mass and less than 0.1% by mass relative to the entire composition.

11. A composition, characterized in that: Contains trans-1,2-difluoroethylene (HFO-1132(E)) and amines. The total concentration of the two components is 99.5% by mass or more based on the entire composition, and the content of the amine is more than 0% by mass and is 0.1% by mass or less based on the entire composition.

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