Azeotropic or azeotrope-like compositions containing 1-chloro-2, 2-difluoroethane and hydrogen fluoride

Abstract

The present invention provides a novel azeotropic or azeotrope-like composition containing 1-chloro-2, 2-difluoroethane (HCFC-142) and hydrogen fluoride, and a separation method using the same. The invention relates to an azeotropic or azeotrope-like composition containing HCFC-142 and hydrogen fluoride. The invention relates to a method for separating a composition. The composition contains HCFC-142 and hydrogen fluoride.

Description

[0001] This case is filed on April 9, 2020 、Application number is 202080027618.0 (PCT / JP2020 / 015962) , divisional application for the invention entitled "Azeotropic or azeotrope-like composition containing 1,1,2-trifluoroethane, 1-chloro-2,2-difluoroethane or 1,2-dichloro-1-fluoroethane and hydrogen fluoride." Technical Field

[0002] The present invention relates to an azeotropic or azeotropic-like composition containing 1,1,2-trifluoroethane, 1-chloro-2,2-difluoroethane or 1,2-dichloro-1-fluoroethane and hydrogen fluoride, and a method for separating hydrogen fluoride by utilizing the properties of the composition. Background Art

[0003] 1,1,2-Trifluoroethane (HFC-143) is useful as a foaming agent for polyolefins and polyurethanes, an aerosol propellant, a refrigerant, a heat transfer medium, a gaseous dielectric, a fire extinguishing agent, a power cycle working fluid, a polymerization medium, a particle removal fluid, a carrier fluid, a polishing abrasive, and a displacement desiccant (Patent Document 1). The boiling point of HFC-143 is about 4°C.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 94 / 011460 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The technical problem to be solved by the present invention is to provide a novel azeotropic or azeotropic-like composition containing 1,1,2-trifluoroethane, 1-chloro-2,2-difluoroethane or 1,2-dichloro-1-fluoroethane and hydrogen fluoride, and a separation method using the same.

[0009] Technical solutions for solving technical problems

[0010] Item 1. An azeotropic or azeotrope-like composition comprising 1,1,2-trifluoroethane (HFC-143) and hydrogen fluoride.

[0011] Item 2. The azeotropic or azeotrope-like composition according to Item 1, comprising 40% by mass or more and less than 100% by mass of the HFC-143 based on 100% by mass of the total of the HFC-143 and the hydrogen fluoride.

[0012] Item 3. An azeotropic or azeotrope-like composition comprising 1-chloro-2,2-difluoroethane (HCFC-142) and hydrogen fluoride.

[0013] Item 4. The azeotropic or azeotrope-like composition according to Item 3, comprising 10 mass % to 99 mass % of the HCFC-142 based on 100 mass % of the total of the HCFC-142 and the hydrogen fluoride.

[0014] Item 5. An azeotropic or azeotrope-like composition comprising 1,2-dichloro-1-fluoroethane (HCFC-141) and hydrogen fluoride.

[0015] Item 6. The azeotropic or azeotrope-like composition according to Item 5, comprising 20 mass % to 99 mass % of the HCFC-141 based on 100 mass % of the total of the HCFC-141 and the hydrogen fluoride.

[0016] Item 7. A method for separating a composition comprising at least one selected from 1,1,2-trifluoroethane (HFC-143), 1-chloro-2,2-difluoroethane (HCFC-142) and 1,2-dichloro-1-fluoroethane (HCFC-141) and hydrogen fluoride, the method comprising steps (a) and (b), and, if necessary, steps (c) and (d).

[0017] (a) a step of supplying a composition containing at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride to a first distillation column;

[0018] (b) a step of extracting an azeotropic or azeotrope-like composition containing at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride as a first distillate, and extracting a composition having a higher concentration of i) at least one selected from HFC-143, HCFC-142 and HCFC-141 or ii) hydrogen fluoride than the supplied composition as a bottom composition of the first distillation column;

[0019] (c) a step of supplying the bottom composition of the first distillation column to a second distillation column having a different operating temperature and / or operating pressure to carry out distillation;

[0020] (d) a step of extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column when the concentration of the liquid stream is higher than that of the supplied liquid stream, and extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column, and extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher concentration of at least one selected from the group consisting of HFC-143, HCFC-142 and HCFC-141 as the bottom composition of the second distillation column when the concentration of at least one selected from the group consisting of HFC-143, HCFC-142 and HCFC-141 is higher than that of the supplied liquid stream.

[0021] Effects of the Invention

[0022] According to the present invention, there can be provided a novel azeotropic or azeotrope-like composition containing 1,1,2-trifluoroethane, 1-chloro-2,2-difluoroethane or 1,2-dichloro-1-fluoroethane and hydrogen fluoride, and a separation method using the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram showing an example of a separation method using an azeotropic or azeotrope-like composition.

[0024] Figure 2 This is a diagram showing another example of a separation method using an azeotropic or azeotrope-like composition. DETAILED DESCRIPTION

[0025] In this specification, the term "azeotrope-like composition" refers to a composition that can be treated substantially the same as an azeotropic composition. Specifically, in this specification, the term "azeotrope-like composition" refers to a constant boiling point or a substantially constant boiling point mixture of two or more substances that substantially behaves as a single substance. As one of the characteristics of azeotrope-like compositions, it can be cited that the composition of the vapor generated by the evaporation or distillation of the liquid does not substantially change from the composition of the liquid. That is, in this specification, when a certain mixture boils, distills or refluxes without substantially changing in composition, the mixture is referred to as an azeotrope-like composition. Specifically, when the difference between the bubble point vapor pressure of a composition at a certain specific temperature and the dew point vapor pressure of the composition is 3% or less (based on the bubble point pressure), the composition is defined as an azeotrope-like composition in the present invention.

[0026] In the present specification, an azeotropic composition and an azeotrope-like composition in which the liquid phase is separated into two liquid phases are also referred to as a heterogeneous azeotropic composition and a heterogeneous azeotrope-like composition, respectively.

[0027] Among them, as a method for producing HFC-143, there is a method of performing a fluorination reaction using 1-chloro-2,2-difluoroethane (HCFC-142) or 1,2-dichloro-1-fluoroethane (HCFC-141) as a raw material.

[0028] The inventors of the present invention have focused on the fact that the raw materials used in the existing HFC-143 production method are not all converted into the target product, and some method is needed to separate and recover the intermediates and unreacted raw materials for reuse. The reason is that if these raw materials are not recovered, they will be lost, resulting in increased costs.

[0029] The present inventors have found that combinations of specific components contained in these raw materials form azeotropic or azeotrope-like compositions and that these compositions are useful when separated by distillation, extraction, liquid-liquid separation or the like, thereby completing the present invention.

[0030] 1. Composition 1

[0031] Composition 1 is an azeotropic or azeotrope-like composition comprising HFC-143 and hydrogen fluoride (HF).

[0032] In Composition 1, from the viewpoint of recovering unreacted hydrogen fluoride and improving the yield, the content of HFC-143 is preferably 40% by mass or more and less than 100% by mass, more preferably 50% by mass or more and less than 100% by mass, and even more preferably 60% by mass or more and less than 100% by mass, based on 100% by mass of the total of HFC-143 and hydrogen fluoride.

[0033] In Composition 1, for example, when 68 mol% (90 mass%) of HFC-143 is contained relative to 100 mol% (100 mass%) of the total of HFC-143 and hydrogen fluoride at 40°C and a pressure of 539 kPa, an azeotropic composition (heterogeneous azeotropic composition) is obtained. In Composition 1, for example, when 20 mol% to 95 mol% (51 mass% to 99 mass%) of HFC-143 is contained relative to 100 mol% (100 mass%) of the total of HFC-143 and hydrogen fluoride at 40°C and a pressure of 524 to 554 kPa, an azeotropic-like composition is obtained. The above pressure is a pressure range (at 40°C) that provides an azeotropic and azeotropic-like composition.

[0034] The above mass % and mol % represent values ​​in a liquid phase.

[0035] In addition, in this specification, pressure means absolute pressure unless otherwise specified.

[0036] In addition to HFC-143 and hydrogen fluoride, composition 1 may contain additional compounds.

[0037] The additional compound is not particularly limited, and can be widely selected within the range that does not prevent the composition 1 from becoming an azeotropic or azeotrope-like composition. The additional compound may be one or more.

[0038] Examples of the additional compound include 1,1,2-trifluoroethylene (HFC-1123), 1,1-difluoromethane (HFC-152a), fluoroethane (HFC-161), 1-chloro-1,2,2-trifluoromethane (HCFC-133), 2-chloro-1,1,1-trifluoroethane (HCFC-133a), 1-chloro-1,1,2-trifluoroethane (HCFC-133b), 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), and 1,2-difluoroethane (HFC-152).

[0039] The total content of the additional compounds can be appropriately selected within a range that does not prevent the composition 1 from becoming an azeotropic or azeotrope-like composition.

[0040] When the additional compounds are contained, the total content thereof is preferably greater than 0 mass % and less than 1 mass %, more preferably greater than 0 mass % and less than 0.5 mass %, and further preferably greater than 0 mass % and less than 0.1 mass %, based on 100 mass % of the entire composition 1.

[0041] Composition 1 can be an important composition when azeotropic distillation is performed to separate hydrogen fluoride from HFC-143 in a mixture of HFC-143 and hydrogen fluoride.

[0042] For example, an azeotropic or azeotrope-like composition containing HFC-143 and hydrogen fluoride is extracted from a composition containing at least HFC-143 and hydrogen fluoride by azeotropic distillation, thereby separating hydrogen fluoride from HFC-143. In addition, HF remaining in the extracted azeotropic or azeotrope-like composition can be separated and recovered by using methods such as absorption (extraction) using H2SO4 or water washing.

[0043] Azeotropic distillation is a method of concentrating or separating a target product by operating a distillation column under conditions where an azeotropic or azeotrope-like composition is separated. Azeotropic distillation may be used to distill only the component to be separated, but azeotropic distillation may occur for the first time when one or more components to be separated and another component that forms an azeotropic mixture are added from the outside. In this specification, both the former and the latter are referred to as azeotropic distillation.

[0044] 2. Composition 2

[0045] Composition 2 is an azeotropic or azeotrope-like composition comprising HCFC-142 and hydrogen fluoride (HF).

[0046] In Composition 2, from the viewpoint of recovering unreacted hydrogen fluoride and improving the yield, the content of HCFC-142 is preferably 10% by mass to 99% by mass, more preferably 20% by mass to 99% by mass, and still more preferably 36% by mass to 99% by mass, based on 100% by mass of the total of HCFC-142 and hydrogen fluoride.

[0047] In Composition 2, for example, when 36.2 mol% (74 mass%) of HCFC-142 is contained relative to 100 mol% (100 mass%) of the total of HCFC-142 and hydrogen fluoride at 40°C and a pressure of 281 kPa, an azeotropic composition (heterogeneous azeotropic composition) is obtained. In Composition 2, for example, when 10 mol% to 95 mol% (36 mass% to 99 mass%) of HCFC-142 is contained relative to 100 mol% (100 mass%) of the total of HCFC-142 and hydrogen fluoride at 40°C and a pressure of 272 to 290 kPa, an azeotropic-like composition is obtained. The above pressure is a pressure range (at 40°C) that provides an azeotropic and azeotropic-like composition.

[0048] The above mass % and mol % represent values ​​in a liquid phase.

[0049] In addition to HCFC-142 and hydrogen fluoride, composition 2 may contain additional compounds.

[0050] The additional compound is not particularly limited, and can be widely selected within the range that does not prevent the composition 2 from becoming an azeotropic or azeotrope-like composition. The additional compound may be one or more.

[0051] Examples of the additional compound include 1,1,2-trifluoroethylene (HFC-1123), 1,1-difluoromethane (HFC-152a), fluoroethane (HFC-161), 1,1,2-trifluoroethane (HFC-143), 1-chloro-1,2,2-trifluoromethane (HCFC-133), 2-chloro-1,1,1-trifluoroethane (HCFC-133a), 1-chloro-1,1,2-trifluoroethane (HCFC-133b), 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), and 1,2-difluoroethane (HFC-152).

[0052] The total content of the additional compounds can be appropriately selected within a range that does not prevent the composition 2 from becoming an azeotropic or azeotrope-like composition.

[0053] When the additional compounds are contained, the total content thereof is preferably greater than 0 mass % and less than 1 mass %, more preferably greater than 0 mass % and less than 0.5 mass %, and further preferably greater than 0 mass % and less than 0.1 mass %, based on 100 mass % of the entire composition 2.

[0054] Composition 2 can be an important composition when azeotropic distillation is performed to separate hydrogen fluoride from HCFC-142 in a mixture of HCFC-142 and hydrogen fluoride.

[0055] For example, an azeotropic or azeotrope-like composition containing HCFC-142 and hydrogen fluoride is extracted from a composition containing at least HCFC-142 and hydrogen fluoride by azeotropic distillation, thereby separating hydrogen fluoride from HCFC-142. In addition, HF remaining in the extracted azeotropic or azeotrope-like composition can be separated and recovered by using a method such as absorption (extraction) using H2SO4 or water washing.

[0056] 3. Composition 3

[0057] Composition 3 is an azeotropic or azeotrope-like composition comprising HCFC-141 and hydrogen fluoride (HF).

[0058] In Composition 3, from the viewpoint of recovering unreacted hydrogen fluoride and improving the yield, the content of HCFC-141 is preferably 20% by mass to 99% by mass, more preferably 30% by mass to 99% by mass, and even more preferably 39% by mass to 99% by mass, relative to 100% by mass of the total of HCFC-141 and hydrogen fluoride.

[0059] In Composition 3, for example, when 42.9 mol% (81 mass%) of HCFC-141 is contained relative to 100 mol% (100 mass%) of the total of HCFC-141 and hydrogen fluoride at 40°C and a pressure of 196 kPa, an azeotropic composition (heterogeneous azeotropic composition) is obtained. In Composition 3, for example, when 10 mol% to 95 mol% (39 mass% to 99 mass%) of HCFC-141 is contained relative to 100 mol% (100 mass%) of the total of HCFC-141 and hydrogen fluoride at 40°C and a pressure of 190 to 202 kPa, an azeotropic-like composition is obtained. The above pressure is a pressure range (at 40°C) that provides an azeotropic and azeotropic-like composition.

[0060] The above mass % and mol % represent values ​​in a liquid phase.

[0061] In addition to HCFC-141 and hydrogen fluoride, composition 3 may contain additional compounds.

[0062] The additional compound is not particularly limited, and can be widely selected within the range that does not prevent the composition 3 from becoming an azeotropic or azeotrope-like composition. The additional compound may be one or more.

[0063] Examples of the additional compound include 1,1,2-trifluoroethylene (HFC-1123), 1,1-difluoromethane (HFC-152a), fluoroethane (HFC-161), 1,1,2-trifluoroethane (HFC-143), 1-chloro-1,2,2-trifluoromethane (HCFC-133), 2-chloro-1,1,1-trifluoroethane (HCFC-133a), 1-chloro-1,1,2-trifluoroethane (HCFC-133b), 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), and 1,2-difluoroethane (HFC-152).

[0064] The total content of the additional compounds can be appropriately selected within a range that does not prevent the composition 3 from becoming an azeotropic or azeotrope-like composition.

[0065] When the additional compounds are contained, the total content thereof is preferably greater than 0 mass % and less than 1 mass %, more preferably greater than 0 mass % and less than 0.5 mass %, and further preferably greater than 0 mass % and less than 0.1 mass %, based on 100 mass % of the entire composition 3.

[0066] Composition 3 can be an important composition when azeotropic distillation is performed to separate hydrogen fluoride from HCFC-141 in a mixture of HCFC-141 and hydrogen fluoride.

[0067] For example, an azeotropic or azeotrope-like composition containing HCFC-141 and hydrogen fluoride can be extracted from a composition containing at least HCFC-141 and HF by azeotropic distillation, thereby separating hydrogen fluoride from HCFC-141. In addition, HF remaining in the extracted azeotropic or azeotrope-like composition can be separated and recovered by using methods such as absorption (extraction) using H2SO4 or water washing.

[0068] 4. Separation method

[0069] The present invention also discloses a method for separating the components of the above composition.

[0070] The separation method of the present invention is a separation method for the following composition, wherein the composition contains at least one selected from 1,1,2-trifluoroethane (HFC-143), 1-chloro-2,2-difluoroethane (HCFC-142) and 1,2-dichloro-1-fluoroethane (HCFC-141) and hydrogen fluoride,

[0071] The separation method of the present invention comprises steps (a) and (b), and if necessary, steps (c) and (d).

[0072] (a) a step of supplying a composition containing at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride to a first distillation column;

[0073] (b) a step of extracting an azeotropic or azeotrope-like composition containing at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride as a first distillate, and extracting a composition having a higher concentration of i) at least one selected from HFC-143, HCFC-142 and HCFC-141 or ii) hydrogen fluoride than the supplied composition as a bottom composition of a first distillation column;

[0074] (c) a step of supplying the bottom composition of the first distillation column to a second distillation column having a different operating temperature and / or operating pressure to carry out distillation;

[0075] (d) a step of extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column when the concentration of the liquid stream is higher than that of the supplied liquid stream, and extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column, and extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher concentration of at least one selected from the group consisting of HFC-143, HCFC-142 and HCFC-141 as the bottom composition of the second distillation column when the concentration of at least one selected from the group consisting of HFC-143, HCFC-142 and HCFC-141 is higher than that of the supplied liquid stream.

[0076] The above separation method is a separation method comprising the following steps of separating a composition containing at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride into at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride. The above method is a method of performing distillation separation by utilizing the property of forming an azeotropic or azeotrope-like composition of HFC-143, HCFC-142 or HCFC-141 and hydrogen fluoride.

[0077] For example, hydrogen fluoride can be separated from HFC-143, HCFC-142 or HCFC-141 by extracting an azeotropic or azeotrope-like composition containing HFC-143, HCFC-142 or HCFC-141 and hydrogen fluoride from a composition containing at least HFC-143, HCFC-142 or HCFC-141 and hydrogen fluoride by azeotropic distillation.

[0078] Furthermore, as shown in the Examples described below, compositions containing HFC-143, HCFC-142, and HCFC-141 and hydrogen fluoride can also be separated by distillation by utilizing the property of forming azeotropic or azeotrope-like compositions.

[0079] In the above separation method, the starting composition used in step (a), i.e., the composition containing at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride, may be a composition consisting only of at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride, or may be a composition containing other components in addition to at least one selected from HFC-143, HCFC-142 and HCFC-141 and hydrogen fluoride.

[0080] In the above step (b), in the composition after the first distillate is distilled off from the supplied composition, the concentration of either i) or ii) is higher than that in the supplied composition (because the total amount and composition of the composition change). Then, the composition having a higher concentration of either i) or ii) than that in the supplied composition is extracted as the bottom composition of the first distillation column.

[0081] In the step (c), the bottom composition of the first distillation column is supplied to a second distillation column having a different operating temperature and / or operating pressure for distillation. The operating conditions (operating temperature and / or operating pressure) of the first and second distillation columns can be appropriately set. In addition, it is preferred to make the operating conditions of the second distillation column different from those of the first distillation column in terms of distillation efficiency and the like.

[0082] In the above step (d), when the concentration of hydrogen fluoride in the composition extracted as the bottom composition of the first distillation column is higher than that of the supplied liquid stream, the liquid stream having a higher concentration of hydrogen fluoride is extracted as the bottom composition of the second distillation column, and when the concentration of at least one selected from the group consisting of HFC-143, HCFC-142 and HCFC-141 is higher than that of the supplied liquid stream, the liquid stream having a higher concentration of at least one selected from the group consisting of HFC-143, HCFC-142 and HCFC-141 is extracted as the bottom composition of the second distillation column.

[0083] The "liquid stream supplied" in the step (d) refers to the liquid stream supplied to the first distillation column in the step (a).

[0084] In the above separation method, the above steps (c) to (d) are not essential steps but are steps that can be performed arbitrarily. The above separation method may be a method consisting of only the above steps (a) to (b), a method consisting of only the above steps (a) to (d), or a method including other steps in addition to the above steps (a) to (d).

[0085] An example of the above separation method is shown in Figure 1 , another example is shown in Figure 2.

[0086] exist Figure 1 In the above, C1 represents the first distillation column, C2 represents the second distillation column, Figure 1 It is shown that a composition is supplied from S11 to C1, a first distillate is obtained from S13, a bottom composition of the first distillation column is extracted from S12 and supplied to C2, a second distillate is obtained from S15, and a bottom composition of the second distillation column is extracted from S14.

[0087] exist Figure 2 In the above, C1 represents the first distillation column, Figure 2 2 shows that a composition is supplied from S11 to C1, a first distillate is obtained from S13, and a bottom composition of the first distillation column is extracted from S12.

[0088] Specifically, for example, the following examples can be given.

[0089] From S11, a composition composed of HFC-143, HCFC-142, HCFC-141 and hydrogen fluoride is supplied to the distillation column C1. From S13, an azeotropic composition of HFC-143 and hydrogen fluoride is distilled off, and from S12, HCFC-142, HCFC-141 and hydrogen fluoride are obtained.

[0090] S13 is sent to the next step, and liquid-liquid separation is performed to separate into an HF-rich phase and an HFC-143-rich phase. The HF-rich phase is reused in the reaction step (HFC-143 production step). The HFC-143-rich phase can be completely removed from the trace amount of residual HF by a method that does not use water, such as washing with water or washing with water using an alkaline aqueous solution, or absorption with H2SO4, to produce a product.

[0091] The obtained HCFC-142, HCFC-141 and hydrogen fluoride are supplied to C2 from S12. In C2, distillation using an azeotropic or azeotropic-like composition is performed in the same manner as C1, and the mixture is separated into a liquid stream S15 mainly composed of an azeotropic or azeotropic-like composition of HCFC-142 and hydrogen fluoride, and a liquid stream S14 mainly composed of HCFC-141 and hydrogen fluoride. These streams may be reused in the reaction step (HFC-143 production step), respectively.

[0092] A small amount of HF extracted as an azeotropic or azeotropic-like composition can be recovered by other general methods (absorption by water), thereby minimizing the loss and reducing the burden on the equipment. In addition, if a recovery method for HF that does not use water, such as absorption by H2SO4, is used, it can be reused as a raw material for the reaction together with each compound and HF. In this case, the recovery equipment using corrosive H2SO4 can be minimized, and the equipment cost can be suppressed.

[0093] Thus, according to the separation method of the present invention, hydrogen fluoride can be separated efficiently.

[0094] As mentioned above, although embodiment is described, it should be understood that various changes in form and details can be made without departing from the spirit and scope of the scope of claims.

[0095] Example

[0096] The following is a more detailed description using examples as examples, but the present invention is not limited to these examples.

[0097] Example 1

[0098] The gas-liquid equilibrium data of the mixture of HFC-143, HCFC-142 or HCFC-141 and hydrogen fluoride (HF) at 40°C are shown in Tables 1 to 3. The numerical units in the tables for each compound in the liquid phase and the gas phase are molar ratios (the total number of moles of each compound and HF in each of the liquid phase and the gas phase is set to 1).

[0099] Table 1

[0100]

[0101] Table 2

[0102]

[0103] Table 3

[0104]

[0105] Table 1 shows that in the composition of HFC-143 and HF, when 68 mol% (90 mass%) of HFC-143 is contained in the liquid phase, the compositions of the liquid phase and the gas phase are the same and an azeotropic composition (heterogeneous azeotropic composition) is obtained, and when 20 to 95 mol% (51 to 99 mass%) of HFC-143 is contained, an azeotropic-like composition is obtained.

[0106] Table 2 shows that in the composition of HCFC-142 and HF, when 36.2 mol% (74 mass%) of HCFC-142 is contained in the liquid phase, the compositions of the liquid phase and the gas phase are the same and an azeotropic composition (heterogeneous azeotropic composition) is obtained, and when 10 to 95 mol% (36 to 99 mass%) of HCFC-142 is contained, an azeotropic-like composition is obtained.

[0107] Table 3 shows that in the composition of HCFC-141 and HF, when 42.9 mol% (81 mass%) of HCFC-141 is contained in the liquid phase, the compositions of the liquid phase and the gas phase are the same and an azeotropic composition (heterogeneous azeotropic composition) is obtained, and when 10 to 95 mol% (39 to 99 mass%) of HCFC-141 is contained, an azeotropic-like composition is obtained.

[0108] Thus, according to the vapor-liquid equilibrium data at 40°C, when the composition of HFC-143 and HF contains 20 to 95 mol% of HFC-143, when the composition of HCFC-142 and HF contains 10 to 95 mol% of HCFC-142, and when the composition of HCFC-141 and HF contains 10 to 95 mol% of HCFC-141, the difference between the bubble point vapor pressure and the dew point vapor pressure of each of the above compositions at 40°C is 3% or less, and they are azeotropic-like compositions.

[0109] From the above, it was found that HFC-143, HCFC-142 and HCFC-141 each form an azeotropic or azeotrope-like composition with HF, and these become important compositions when separating from HF using a distillation column.

[0110] Example 2

[0111] The method of separating at least one selected from HFC-143, HCFC-142 and HCFC-141 from hydrogen fluoride is performed as follows.

[0112] Figure 1 An example of a separation method using an azeotropic or azeotropic composition is shown in Table 4. Figure 1 The flow rates of HFC-143, HCFC-142, HCFC-141 and hydrogen fluoride in S11 to S15.

[0113] Table 4

[0114]

[0115] From S11, a composition composed of HFC-143, HCFC-142, HCFC-141 and hydrogen fluoride is supplied to the distillation column C1. From S13, an azeotropic composition of HFC-143 and hydrogen fluoride is distilled off, and from S12, HCFC-142, HCFC-141 and hydrogen fluoride are obtained.

[0116] S13 is sent to the next step, and liquid-liquid separation is performed to separate into an HF-rich phase and an HFC-143-rich phase. The HF-rich phase is reused in the reaction step (HFC-143 production step). The HFC-143-rich phase can be completely removed from the trace amount of residual HF by a method that does not use water, such as washing with water or washing with water using an alkaline aqueous solution, or absorption with H2SO4, to produce a product.

[0117] The obtained HCFC-142, HCFC-141 and hydrogen fluoride are supplied from S12 to C2. In C2, distillation using an azeotropic or azeotropic-like composition is performed in the same manner as C1, and the mixture is separated into a liquid stream S15 mainly composed of an azeotropic or azeotropic-like composition of HCFC-142 and hydrogen fluoride, and a liquid stream S14 mainly composed of hydrogen fluoride. These streams may be reused in the reaction step (HFC-143 production step), respectively.

[0118] Alternatively, a liquid-liquid separation process may be used instead of distillation. The composition of HCFC-142, HCFC-141 and hydrogen fluoride obtained from S12 is subjected to liquid-liquid separation in a range of, for example, -40°C to 40°C to separate into a phase mainly rich in HF and a phase mainly rich in organics (HCFC-142, HCFC-141), which can be reused in the reaction step (HFC-143 production step).

[0119] By the separation operation by distillation, the reaction conditions (contact time, hydrogen fluoride / organic matter molar ratio) in the reaction step can be controlled, and the reaction activity and catalytic activity can be maintained at a good level.

Claims

1. An azeotropic or azeotrope-like composition, characterized in that: Contains 1-chloro-2,2-difluoroethane (HCFC-142) and hydrogen fluoride.

2. The azeotropic or azeotrope-like composition of claim 1, wherein: The HCFC-142 is contained in an amount of 10% by mass or more and 99% by mass or less relative to 100% by mass of the total of the HCFC-142 and the hydrogen fluoride.

3. A method for separating a composition comprising 1-chloro-2,2-difluoroethane (HCFC-142) and hydrogen fluoride, the method comprising: comprising steps (a) and (b), and, if necessary, steps (c) and (d), (a) a step of supplying a composition containing HCFC-142 and hydrogen fluoride to a first distillation column; (b) extracting an azeotropic or azeotrope-like composition containing HCFC-142 and hydrogen fluoride as a first distillate, and extracting a composition having a higher concentration of either i) HCFC-142 or ii) hydrogen fluoride than the supplied composition as a bottom composition of the first distillation column; (c) a step of supplying the bottom composition of the first distillation column to a second distillation column having a different operating temperature and / or operating pressure to carry out distillation; (d) a step of extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column when the concentration of hydrogen fluoride is higher than that of the supplied liquid stream, and extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column, and extracting, from among the compositions extracted as the bottom composition of the first distillation column, a liquid stream having a higher hydrogen fluoride concentration as the bottom composition of the second distillation column when the concentration of HCFC-142 is higher than that of the supplied liquid stream.

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