JP2002505311A - Method for purifying perfluorocyclobutane - Google Patents

Abstract

SUMMARY OF THE INVENTION Disclosed are PFC-C318 containing less than 10 parts per million of halogenated impurities, and methods of making such substantially pure PFC-C318. In operating these processes, various PFC-C318 containing azeotropes and azeotropic compositions have been discovered and are useful. These compositions include: perfluorocyclobutane (PFC-C318) and 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); perfluorocyclobutane (PFC-C318) and 1,1,2,2-tetrafluoroethane (HFC-134); perfluorocyclobutane (PFC-C318) and 1,1,1,2-tetrafluoroethane (HFC-134a); and perfluorocyclobutane (PFC-134) C318) and 1,1-difluoroethane (HFC-152a). The method of the present invention for producing substantially pure PFC-C318 comprises the following steps: a) an azeotropic distillation process for separating PFC-C318 from halogenated impurities, and b) ethers, ketones, alcohols Distillation process to separate PFC-C318 from halogenated impurities by using an entrainer selected from water, hydrocarbons, and hydrochlorocarbons.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] This application is related to US Provisional Application No. 60/07692, filed March 5, 1998.
Claim the benefit of priority 3

The present invention relates to an azeotropic and azeotropic composition containing perfluorocyclobutane, and to separating perfluorocyclobutane from a first mixture containing perfluorocyclobutane and halogenated impurities. Accordingly, the present invention relates to an azeotropic and extractive distillation method whereby high-purity perfluorocyclobutane can be obtained with high recovery efficiency.

BACKGROUND OF THE INVENTION [0003] Gaseous fluorine-containing compounds are used in the process of manufacturing semiconductor devices by the electronics industry. Perfluorocyclobutane (PFC-C3
The primary use of 18) is in plasma etching silicon-based materials during semiconductor device fabrication. Under plasma conditions, a plasma etchant such as PFC-C318 breaks down and these debris products interact with it while modifying the surface of the semiconductor device to provide an electrical path and define a composite surface. Provide the resulting surface functionalization.

[0004] PFC-C3 used as a plasma etchant in semiconductor manufacturing applications
Chemicals such as 18 are commonly referred to as "electronic gases." High purity electron gas is important in this application. It is known that even very small amounts of impurities in the electron gas result in wide linewidths and, therefore, less information per semiconductor device when such impure gases are used in semiconductor device manufacturing equipment. ing. Further, the presence of these impurities, including particulate, metal, moisture, and halocarbon impurities, even when present at levels as low as one part per million, increases the defect rate in the manufacture of high density integrated circuits. As a result, there is an increasing demand by the electronics industry for very high purity etching gases, and an increasing market value for materials of the required purity. The identification of impurities, and the method of removing them, represents a salient feature of the preparation of etching gases for these applications.

[0005] PFC-C318 in its pure state exhibits valuable properties for integrated circuit manufacturing and can also be used in various manufacturing processes. PFC-C3
The desire for an effective electron gas, such as 18, to be more accurate and consistent during integrated circuit fabrication makes extremely pure gases important in such applications. The presence of halogenated impurities in PFC-C318 is problematic for intended uses in this field. A method that allows for the production of PFC-C318 having a purity approaching that of 99.999 mole percent is desired, and a method that provides at least 99.9999 mole percent purity for electronic gas applications is preferred.

[0006] As disclosed in US Pat. No. 5,129,997, PFC-C318 can also be produced by pyrolysis of chlorodifluoromethane (CHClF ₂ , HCFC-22). It is difficult to obtain PFC-C318 with very high purity from the product stream produced by this method. It also produces various halogenated impurities with boiling points that are very close to PFC-C318 in isolated and pure form, or the specific volatility approaches 1.0 compared to PFC-C318. Or a non-ideal behavior that is equal to 1.0. Impurities of specific volatility approaching or equal to 1.0 compared to PFC-C318 are those from conventional PFC-C318 by distillation in recovering the PFC-C318 product from which impurities have been removed. Separation is ineffective. Such separation requires that the recovered PFC-C318 product be substantially free of halogenated impurities, and that the PFC-C318 product be PFC-C3
There is a particular problem when it is necessary to recover with high recovery efficiency from a mixture containing 18 and impurities.

[0007] Conventional methods for producing PFC-C318 products do not allow removal of various halogenated impurities from the PFC-C318 product, and therefore produce PFC-C318 having a purity of 99.999 or higher mole percent. It is not possible to manufacture. PFC- with 99.999 or higher mole percent purity
The manufacture of C318 was not known before the present invention.

[0008] The present invention addresses the problems associated with conventional distillation methods by providing a distillation process for removing halogenated impurities from PFC-C318 to produce highly purified PFC-C318 with high recovery efficiency. Solve.

SUMMARY OF THE INVENTION The present invention comprises PFC-C318 that is substantially free of halogenated impurities, preferably containing less than 10 parts per million of halogenated impurities.

The present invention further relates to perfluorocyclobutane (PFC-C318) and 2
-Chloro-1,1,1,2-tetrafluoroethane (HCFC-124); perfluorocyclobutane (PFC-C318) and 1,1,2,2-tetrafluoroethane (HFC-134); perfluorocyclobutane ( PFC-C318
) And 1,1,1,2-tetrafluoroethane (HFC-134a); and azeotropic compositions consisting essentially of perfluorocyclobutane (PFC-C318) and 1,1-difluoroethane (HFC-152a). . The invention further includes an azeotropic and extractive distillation method for separating perfluorocyclobutane (PFC-C318) from a first mixture containing perfluorocyclobutane (PFC-C318) and halogenated impurities.

DETAILED DESCRIPTION The present invention includes a PFC-C318 that is substantially free of impurities. Impurities are
Any halogenated compound other than PFC-C318 is meant. Substantially free or substantially pure refers to PFC-C3 produced by the method of the present invention.
18 is less than 10 parts per million (10 ppmm), preferably 1 ppmm
It contains less than 100 parts per million (100 ppbm) of halogenated impurities, most preferably less than 100 parts per million (mol). Thus, the present invention provides a PF having an impurity of less than 10 ppmm, preferably less than 1 ppmm, more preferably less than 100 ppbm.
C-C318. Analytical methods that may be used to analyze such concentrations of impurities in the PFC-C318 product are described in “Examining Purification and
Certification Strategies for High-Purity C ₂ F ₆ Process Gas ”, Micro Maga
Zine, April 1998, pages 35 et seq., which is hereby incorporated by reference.

[0012] The method used to manufacture PFC-C318 is based on PFC-C318 production.
Various halogenated impurities may be produced simultaneously in the product stream. PFC
-Specific examples of halogenated impurities that may be found in the C318 product stream
Are linear and cyclic, saturated and unsaturated, perfluorocarbons (PF
Cs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons
Bones (HCFCs), hydrofluorocarbons (HFCs), and high
Contains drochlorocarbons (HCCs). From these classes of halogenated impurities
Typical examples of include: PFC-31-10 (normal or iso-
-C_FourF_Ten, Perfluorobutane isomer), PFC-41-12 (C_FiveF₁₂, Par
Fluoropentane isomers), PFC-1318my (cis and trans-CF _Three CF = CFCF_Three), PFC-1318c (CF_ThreeCF_TwoCF = CF_Two), PFC-1216 (HFP or CF_ThreeCF = CF_Two), PFC-1114 (TFE or
Is CF_Two= CF_Two), Perfluoroisobutene (CF_Two= C (CF_Three)_Two), CFC-114 (CF_TwoClCF_TwoCl), CFC-114a (CFCl_TwoCF_Three), CF
C-216ba (CF_ThreeCFClCF_TwoCl), CFC-217ba (CF_ThreeCC IFCF_Three), CFC-1113 (CCIF = CF_Two), HCFC-22 (CHC
IF_Two), HCFC-21 (CHCl_TwoF), HCFC-124 (CHFCClCF _Three ), HCFC-124a (CCIF_TwoCHF_Two), HFC-134 (CHF_TwoCH
F_Two), HFC-134a (CH_TwoFCF_Three), HFC-152a (CH_ThreeCF_TwoH), HFC-125 (CF_ThreeCF_TwoH), HFC-227ca (CF_ThreeCF_TwoCHF _Two ), HFC-227ea (CF_ThreeCHFCF_Three), HFC-1225zc (CF_Three CH = CF_Two), HFC-236ca (CHF_TwoCF_TwoCHF_Two), HFC-236
ea (CHF_TwoCHFCF_Three), HFC-236fa (CF_ThreeCH_TwoCF_Three), HC C-30 (CH_TwoCl_Two), HCC-40 (CH_ThreeCl), and HCC-160 (CH_ThreeCH_TwoCl).

Some of these impurities form azeotropic or azeotropic mixtures with PFC-C318, and substantially pure PFC-C318 from such product streams
Makes high recovery efficiency difficult. Such impurities that form an azeotropic or azeotropic mixture with PFC-C318 include HCFC-124, HCFC-124a, HFC-124
134, HFC-134a and HFC-152a, respectively. Other halogenated impurities formed during the pyrolysis of HCFC-22, which represent a significant problem in obtaining a substantially pure PFC-C318 product, are PFC-1318my, PFC
-31-10, PFC-1318c, CFC-114, and CFC-114a
including.

High recovery efficiency means that more than 90%, preferably more than 95%, of the PFC-C318 in the first mixture is substantially free of at least one halogenated impurity as a result of the purification process -Means recovered as C318 product.

By azeotropic composition or azeotrope composition is meant a constant boiling mixture of two or more compounds that behave as pure compounds. One way to characterize an azeotropic composition is that the vapor produced by the partial evaporation or distillation of the liquid has the same composition as the liquid from which it was evaporated or distilled, i.e., the mixture has no change in composition. Distillation / reflux. Constant boiling compositions are characterized as azeotropic when they exhibit either a maximum or minimum boiling point compared to the boiling point of a non-azeotropic mixture of the same components. An azeotropic composition is also characterized by a minimum or maximum in the vapor pressure of the mixture relative to the vapor pressure of the neat component at a constant temperature.

By azeotropic is meant a composition that has constant boiling characteristics or has a tendency not to fractionate by boiling or evaporation. Thus, the composition of the vapor formed is the same or substantially the same as the composition of the original liquid. If the composition changes during boiling or evaporation, the composition of the liquid changes only to a minimal or negligible extent. An azeotropic composition may also be characterized as a function of the mole fraction of the components in the composition by the area adjacent to the maximum or minimum vapor pressure in a plot of the vapor pressure of the composition at a given temperature. it can. After about 50 weight percent of the original composition has vaporized or evaporated to yield the remaining composition, the change between the original composition and the remaining composition is about 6% by weight relative to the original composition. The composition is azeotropic if it is less than or equal to typically about 3% by weight.

A low-boiling azeotropic composition or azeotrope composition is a composition in which any one of its constituent compounds boils at a lower temperature at a given pressure than at a given pressure. Means Alternatively, a low-boiling azeotropic composition or azeotrope composition is defined as a vapor pressure at that temperature that is higher than the vapor pressure of any one of the compounds that make up the azeotrope at a given temperature. Means a composition having

A high boiling azeotrope is one in which an azeotropic or azeotropic composition boils at a higher temperature at that pressure than any one of its constituent compounds would separately boil at a given pressure. Means that. Alternatively, a high boiling azeotrope is defined as an azeotropic or azeotropic composition having a lower vapor pressure at that temperature than the vapor pressure of any one of its constituent compounds at a given temperature. Azeotropic or azeotropic composition having the formula:

As a substantially constant boiling mixture which appears under many guises, it is possible to characterize the azeotropic or azeotropic composition by several criteria, depending on the conditions chosen. * Since the term "azeotrope" is both clear and limiting, the composition can be defined as an azeotrope of two compounds, and this characteristic of a substance that can be a constant boiling composition Requires an effective amount of these two or more compounds for the composition.

* It is well known to those skilled in the art that at different pressures, the composition of a given azeotrope or azeotropic composition will vary at least to some extent, such as the boiling point temperature.
Thus, an azeotropic or azeotropic composition of two compounds exhibits a unique type of relationship, but with a composition that can vary with temperature and / or pressure. Thus, composition ranges rather than fixed compositions are often used to define azeotropes and azeotropic compositions.

* An azeotrope or azeotropic composition of two compounds is characterized by defining a composition characterized by a boiling point at a given pressure, and is therefore represented by a specific number The composition provides the features specified without unduly limiting the scope of the invention. The composition represented by a specific number is limited by the available analyzers and is only accurate on available analyzers.

It is recognized in the art that both the boiling point and the amount of each component of the azeotropic composition can change when the liquid composition of the azeotrope is subjected to boiling at different pressures. Thus, azeotropic compositions are characterized by the specific relationship that exists between the components,
Or it can be specified in terms of the exact amount of each component of the composition characterized by a fixed boiling point at a particular pressure.

When the relative volatility of the system, for example, the mixture of the present invention containing PFC-C318 and halogenated impurities, approaches 1.0, such forms an azeotropic composition. It is recognized in the art to define the system as such.
If the relative volatility is equal to 1.0, it defines the system as forming an azeotropic composition. Impurities with a specific volatility approaching or equal to 1.0 for PFC-C318 are extremely difficult or impossible to separate from PFC-C318 by conventional distillation. Conventional distillation means that only the specific volatility of the components of the mixture to be separated is used to separate the components.

To measure the relative volatility of any two compounds, a method known as the PTx method may be used. In this procedure, the total absolute pressure in a cell of known volume is measured at a constant temperature for various compositions of the two compounds. The use of the PTx method is described in “Phase Equilibrium in P
Rocess Design "Wiley-Interscience Publisher, 1970, pp. 124-126, which is hereby incorporated by reference.

These measured values are measured in a PTx cell in a non-random, two-liquid (Non-Random, Tw
An activity coefficient equation model, such as the o-Liquid (NRTL) equation, can be used to represent the non-ideality of the liquid phase and be converted to an equilibrium vapor and liquid composition. NRT
The use of activity coefficient equations such as the L equation is described by Reid, Prausnitz and Poling, published by McGraw Hill, "The Properties of Gases and Liquids", 4th edition, pages 241-287, and by Stanley M. Written by Walas in 1985
`` Phase Equilibria in Chemical Engineeri '' published by Butterworth Publishers
ng "on pages 165 to 244. All of the above references are hereby incorporated by reference.

Without wishing to be bound by any law or explanation, the NRTL equation, along with the PTx cell data, fully describes the specific volatility of the PFC-C318, halogenated impurities, and entrainer of the present invention. It is believed that the behavior of these mixtures in a multi-stage separator, such as a distillation column, can be predicted.

Surprisingly, PFC-C318 and HCFC-124 have 26.8 mol% PF at 20 ° C. and 49 psia (pounds per square inch).
It has been found by the inventors to form an azeotropic composition containing C-C318 and 73.2 mol% HCFC-124. From these data, PFC-
C318 and HCFC-124 at 26 ° C. and 24.6 psia
. It has been calculated to form an azeotropic or azeotropic composition containing 8 mol% PFC-C318 and 73.2 mol% HCFC-124. From these data, PFC-C318 and HCFC-124 were obtained at 80 ° C. and 234.1 psi.
27.5 mol% PFC-C318 and 72.5 mol% HCFC-1
It has been calculated to form an azeotropic or azeotropic composition containing 24. Accordingly, the present invention further comprises an azeotropic or azeotropic composition comprising 26.8 to 27.5 mol% PFC-C318 and 73.2 to 72.5 mol% HCFC-124, wherein the composition comprises It has a boiling point from 0 ° C. at 24.5 psia to 80 ° C. at 234.1 psia.

Surprisingly, PFC-C318 and HFC-134 have a
. 25.0 mol% PFC-C318 and 75.0 mol% H at 4 psia
It has been found by the present inventors to form an azeotropic composition containing FC-134. From these data, PFC-C318 and HFC-134 showed -3
It has been calculated to form an azeotropic or azeotropic composition containing 24.6 mol% PFC-C318 and 75.4 mol% HFC-134 at 0.0 <0> C and 10.35 psia. From these data, PFC-C318 and HFC
-134 is 23.2 mol% PFC- at 80 ° C and 325.8 psia.
It has been calculated to form an azeotropic or azeotropic composition containing C318 and 76.8 mol% HFC-134. Therefore, the present invention relates to 24.6 to 23
. Further comprising an azeotropic or azeotropic composition comprising 2 mol% PFC-C318 and 75.4 to 76.8 mol% HFC-134, wherein the composition is at 10.35 psia-
It has a boiling point from 30 ° C to 80 ° C at 325.8 psia.

[0029] Surprisingly, PFC-C318 and HFC-134a are
7.4 mol% PFC-C318 and 92.6 mol% HFC at 3 psia
It has been found by the present inventors to form an azeotropic composition containing -134a. From these data, PFC-C318 and HFC-134a showed -3
9.9 mol% PFC-C318 and 90.1 at 0 ° C. and 12 psia
It has been calculated to form an azeotropic or azeotropic composition containing mole% HFC-134a. From these data, PFC-C318 and HFC-134a
Has been calculated to form an azeotropic or azeotropic composition containing 0.6 mol% PFC-C318 and 99.4 mol% HFC-134a at 40 ° C. and 147 psia. Therefore, the present invention provides 9.9 to 0.6 mol% PFC
Further comprising an azeotropic or azeotropic composition comprising C318 and 90.1 to 99.4 mole% HFC-134a, wherein the composition is at -30 ° C to 147 ps at 12 psia.
It has a boiling point up to 40 ° C. in ia.

[0030] Surprisingly, PFC-C318 and HFC-152a are
23.1 mol% PFC-C318 and 76.9 mol% HF at 1 psia
It has been found by the present inventors to form an azeotropic composition containing C-152a. From these data, PFC-C318 and HFC-152a were
22.4 mol% PFC-C318 and 77 at 20 ° C. and 19 psia
. It has been calculated to form an azeotropic or azeotropic composition containing 6 mole% HFC-152a. From these data, PFC-C318 and HFC-15
2a was 21.3 mol% PFC-C318 at 80 ° C. and 349 psia.
It is calculated to form an azeotropic or azeotropic composition containing 78.7 mol% HFC-152a. Accordingly, the present invention further comprises an azeotropic or azeotropic composition comprising 23.1 to 21.3 mol% PFC-C318 and 76.9 to 78.7 mol% HFC-152a, wherein the composition comprises It has a boiling point from -20 <0> C at 19 psia to 80 <0> C at 349 psia.

In another embodiment of the present invention, a mixture containing PFC-C318 and at least one of these halogenated impurities is used to form a low boiling azeotrope containing PFC-C318 and the above impurities. Distilling under conditions and removing the azeotropic or azeotropic composition as a distillate product in the distillation allows for some degree of separation of PFC-C318 and the impurities.
Azeotropic distillation means that the distillation column is operated under conditions that allow an azeotropic or azeotropic composition to form, and the formation of at least one of the components is such that these components can also be separated by distillation. It refers to the process of changing the relative volatility for another component.

For example, a mixture containing PFC-C318 and HCFC-124 can be partially purified using the azeotropic composition described above. The distillation column can be operated at pressures and temperatures to form a low boiling azeotrope containing PFC-C318 and HCFC-124, and the azeotrope can be removed from the distillation column as an overhead stream . First mixture (crude raw material PF to be separated)
C-C318 / HCFC-124 mixture), the concentration of PFC-C318 is
If higher than the concentration in the azeotrope of PFC-C318 / HCFC-124 formed under distillation conditions, the PFC-C318 product can be removed as a residue stream in the distillation of the first mixture. In that case, the HC in the residue stream
The FC-124 concentration is reduced relative to the concentration of HCFC-124 in the first mixture;
On the other hand, the azeotropic PFC-C318 / HCFC-124 composition is removed from the distillation column as an overhead stream. Conversely, HCFC-12 in the first mixture
4 is higher than the concentration in the azeotropic composition containing PFC-C318 / HCFC-124 formed under distillation conditions, the HCFC-124 product is removed as a residue stream in the distillation of the first mixture. The PFC-C318 concentration in the residue stream is reduced relative to the PFC-C318 concentration in the first mixture, while the azeotropic PFC-C318 / HCFC-124 composition is removed from the distillation column as an overhead stream. The first PFC-C3 in a single distillation
Obtaining a PFC-C318 containing HCFC-124 at a reduced concentration compared to the 18 / HCFC-124 mixture (or a first PFC-C318 / HCFC-
HCFC-12 with reduced concentration of PFC-C318 compared to B.124 mixture
4) requires starting with a composition having a higher PFC-C318 (or HCFC-124) concentration than a composition of an azeotrope formed at the same temperature and pressure, but with a PFC-C318 Some portion of (or HCFC-124) always remains as an azeotrope of PFC-C318 / HCFC-124.

Each PFC-C318 azeotrope (eg, PFC-C318 / HCFC-
124; PFC-C318 / HFC-134; PFC-C318 / HCFC-1
24a; PFC-C318 / HFC-134a; PFC-C318 / HFC-1
If the formation and distillation of 52a) is used to separate PFC-C318 from halogenated impurities, the resulting azeotropic PFC-C318-containing composition will have a T
Useful as a feed stream to thermal processes for producing FE and HFP. Alternatively, PFC-C318 in the distillate product may be separated by the extractive distillation process of the present invention substantially free of halogenated impurities.

However, the use of the azeotropic compositions described above in distillation is useful for the partial purification of PFC-C318 or halogenated impurities, but by azeotropic distillation from a starting mixture of PFC-C318 / halogenated impurities. Substantially pure PF with high recovery efficiency
It is difficult to obtain the C-C318 product. In addition, such azeotropic distillation
Very often it does not result in the removal of other impurities that do not form an azeotropic composition comprising PFC-C318.

A number of other halogenated impurities found in the PFC-C318 production stream have a specific volatility approaching 1.0 for PFC-C318. Such halogenated impurities include CFC-12, HCC-20, HCFC-22, HFC
-32, CFC-114, CFC-114a, CFC-217ba, HFC-2
27ea, PFC-1318my, PFC-1318c and FC-31-10
including. CFC-114, CFC-114a, PFC-1318my and FC
31-10 is particularly problematic because it often appears in the PFC-C318 process stream at concentrations ranging from hundreds to millions of moles to thousands, or more. Separating these impurities from PFC-C318 requires expensive and expensive distillation columns, and substantially pure P with high recovery efficiency from such mixtures.
Obtaining FC-C318 is still extremely difficult, if not impossible.

We have determined that these and other halogenated impurities can be achieved by the use of an effective amount of a compound that acts in a non-ideal manner with at least one component of the first mixture of PFC-C318 / halogenated impurities. It was unexpectedly found that PFC-C318 could be recovered substantially free of it. Such a compound, hereinafter referred to as an entrainer, is used under distillation conditions for the at least one halogenated impurity in the first mixture.
Increases or decreases the volatility of FC-C318, thus making it possible to obtain PFC-C318 substantially free of halogenated impurities from PFC-C318 and the first mixture containing halogenated impurities.

Accordingly, the present invention provides a method for preparing PFC-C3 from at least one halogenated impurity.
18. The method further comprises separating the mixture containing PFC-C318 and halogenated impurities in the presence of at least one entrainer. The method further comprises distillation in the presence of the entrainer to increase the volatility of the PFC-C318 or halogenated impurity, one over the other.

[0038] The entraining agent means that when added to the first mixture containing PFC-C318 and halogenated impurities, the volatility of one of PFC-C318 and halogenated impurities in the mixture is higher than that of the other component. Means any compound that interacts with PFC-C318 and / or at least one of the halogenated impurities such that the PFC-C318 and the halogenated impurities can be separated by distillation.

[0039] The effective amount of the entraining agent means that in the presence of PFC-C318 and halogenated impurities,
It refers to the amount of at least one entrainer that increases or decreases the volatility of the halogenated impurities relative to the PFC-C318 sufficiently to allow the separation of the halogenated impurities from the PFC-C318 by distillation. This definition includes the case where the effective amount varies depending on the pressure applied to the composition as long as the change in specific volatility continues to exist.

Extractive distillation means a process in which the entraining agent is introduced at the feed point at the top of the distillation column, the mixture requiring separation is the same, or preferably, the entraining agent of the column is introduced. Introduced at a feed point that is relatively lower than the The entraining agent passes down through the trays or packings in the column and exits as a residue stream in the column containing one or more components of the mixture to be separated. And, in the presence of the entrainer, at least one of the components to be separated becomes relatively more or less volatile in the mixture than at least one of the other components, and more volatile components Exits as a distillation column overhead stream. The entraining agent fed to the distillation column at a point equal to or higher than the mixture to be separated and passing down the column, thus allowing separation by distillation, is herein referred to as extractive distilling agent or extractant. Agent.

To further clarify the extractive distillation process of the present invention, we
Impurities, FC-31-10, FC-1318my, FC-1318c, HF
C-134, HFC-134a, HCFC-124, HCFC-124a, CF
C-114, CFC-114a, CFC-217ba, HCC-20, and P
Optionally other halogenated compounds that may be present in the FC-C318 containing stream
Is an entrainer in the extractive distillation process from its PFC-C318
It has been found that they can be separated by the use of P from these halogenated impurities
Suitable entrainers that may be used as extractants for the separation of FC-C318 are
-Tels, ketones, alcohols, hydrocarbons, and hydrochlorocarbons
Including Suitable entrainers that may be used as extractants in the present invention are preferably
Alternatively, it has a standard boiling point of 30 ° C to 120 ° C. Suitable ethers are tetra
Hydrofuran (THF), 1,4-dioxane, and methyl tert-butyl
Includes dialkyl ethers such as ether (MTBE). Suitable ketones are
Contains setone and methyl ethyl ketone (MEK). Suitable alcohols are
Contains tanol and propanol. Suitable hydrocarbons include toluene and cycle
Contains hexane. Suitable hydrochlorocarbons are chloroform (CHCl _Three )including. Preferred entrainers for separating halogenated impurities from PFC-C318 by extractive distillation are THF, MEK, and 1,4-dioxane.

The relative volatility of the aforementioned halogenated impurities compared to PFC-C318 makes it difficult to separate the halogenated impurities from PFC-C318 by conventional distillation in the absence of the aforementioned extractants. I do. In the presence of at least one of the aforementioned extractants, P
The volatility of FC-C318 changes surprisingly with respect to the aforementioned halogenated impurities. Thus, in the presence of any one extractant, PFC-C318
It can be separated from the aforementioned halogenated impurities by extractive distillation and obtained as a product free of the aforementioned halogenated impurities. The present invention relates to PFC-C3
Also provided is a method of removing 18 from said halogenated impurities and recovering said halogenated impurities as a product stream substantially free of PFC-C318.

With the exception of certain halogenated impurities, such as FC-31-10, halogenated impurities unexpectedly do not become as volatile as PFC-C318 in the presence of the extractant of the present invention. . Thus, in the presence of the extractant, PFC-C318 substantially free of halogenated impurities can also be obtained as the overhead stream of the extractive distillation column, and the halogenated impurities can be extracted as the bottom stream of the distillation column. Collected with the agent.

Accordingly, the present invention further comprises a method for separating PFC-C318 and at least one of the aforementioned halogenated impurities, comprising the following steps: a) PFC-C
Contacting a first mixture containing 318 and at least one halogenated impurity with an entrainer to form a second mixture, and b) distilling the second mixture and containing PFC-C318 Recovering the distillation column overhead stream and the distillation column bottoms stream containing the entrainer and at least one halogenated impurity.

With respect to the other halogenated impurities described above, PFC-31-10 is
Although usually at a higher boiling point than C318, surprisingly it becomes even more volatile than PFC-C318 in the presence of the extractant of the present invention, and therefore PFC-31-
10 is separated from PFC-C318 as an overhead stream of the extractive distillation column, and PFC-C318 substantially free of PFC-31-10 is obtained as an extractive distillation column bottom stream.

Accordingly, the present invention further comprises a method of separating PFC-C318 and PFC-31-10, comprising the following steps: a) PFC-C318 and PFC-
Contacting a first mixture containing 31-10 with an entraining agent to form a second mixture; and b) distilling the second mixture and providing a distillation column containing PFC-31-10. Recovering the overhead stream and the distillation column bottoms stream containing the entrainer and PFC-C318.

FIG. 1 schematically illustrates a system that can be used to implement an embodiment of the extractive distillation process of the present invention. A first mixture containing PFC-C318 and FC-31-10 is supplied to distillation column 2 through conduit 1 . At least one extractive entrainer, for example THF, is passed through conduit 3 to distillation column 2 at a feed point higher in the distillation column than the mixture to be separated, for example, PFC-C318 and FC-31-10. Supplied. The overhead distillate from the tower is sent through conduit 4 to condenser 5 . At least a portion of the condensed distillate stream is returned to column 2 as reflux 6 . The residue of the condensed distillate is FC-C318 and FC-31 substantially free of THF.
Recovered through conduit 7 as -10 product. A stream containing PFC-C318 and THF substantially free of FC-31-10 may be removed from the residue of column 2 through conduit 8 and recovered as a product. Alternatively, the residue stream 8 of the tower may be fed to the distillation column 9, the distillation column 9 is operated to remove the compound from the entrainer. The distillate from column 9 is supplied to condenser 11 through conduit 10 . From the condenser 11 ,
Some amount of the condensed distillate is returned as reflux through conduit 12 to column 9 while the remainder substantially comprises, for example, FC-31-10 and an extractive entrainer. Is collected through the conduit 13 as PFC-C318 that is not contained in. Extractive entrainers, for example THF, are obtained as distillation column residue 14 at their reduced concentration compared to the concentration of non-THF compounds in stream 8 . The stream 14 optionally comprises a mixture to be separated, for example, FC-31-10 and an extractant feed supplied to the column at a feed point higher in the column than the feed point of PFC-C318. It may be returned to the distillation column 2 or optionally mixed with the stream 3 .

FIG. 1 illustrates another embodiment of the extractive distillation process of the present invention.
Figure 2 schematically illustrates a system that can be used for: PFC-C318 and FC-1318
The first mixture containing my1Through the distillation tower2Supplied to.
At least one extractive entrainer, for example THF, is a mixture to be separated, for example,
From the feed points of PFC-C318 and FC-1318my to the distillation column
Conduit with high feed point3Through the distillation tower2Supplied to. So
Overhead distillate from tower in conduit4Through the condenser5To
Sent. At least a portion of the condensed distillate stream is at reflux6As tower2 Is returned to. The residue of the condensed distillate yields FC-1318my and THF.
Conduit as qualitatively free PFC-C318 product7Collected through
. Contains FC-1318my and THF substantially free of PFC-C318
Stream to the tower2Conduit from residue8Removed through, and
It may be recovered as a product. Instead, the tower residue stream8Is a distillation tower 9 May be supplied to the distillation column9Removes compounds other than entrainer from entrainer
It is operated as follows. Tower9Distillate from the conduit10Through the condenser1 1 Supplied to condenser11From some amount of condensed distillate
Conduit as reflux12Tower through9While the remainder is
Thus, for example, FC-13 substantially free of PFC-C318 and an extractive entrainer
Conduit as 18 my13Recovered through. Extraction entrainer, for example TH
F is a stream8Reduced their concentration compared to the concentration of non-THF compounds in the
In the distillation column residue14Is obtained as stream14Is optionally separated
Of feed mixture, for example PFC-C318 and FC-1318my
Extractant feed to the tower at a higher feed point in the tower than
Distillation tower2Or optionally stream3And may be mixed.

In a conventional azeotropic or extractive distillation, the overhead or distillate stream leaving the column can also be condensed using a conventional reflux condenser. At least a portion of this condensed stream is returned to the top of the column as reflux and the remainder can be recovered as product or for other processing. The ratio of condensed material returned to the top of the column as reflux to recovered material is conventionally referred to as reflux ratio. In those cases where an entrainer is used, the compounds exiting the column as a residue stream and the entrainer are then stripped, or separated for by using conventional distillation or other known methods, and If desired, it can be passed to another distillation column for recycle of the entrainer to the first distillation column.

The specific conditions that can be used to carry out the process of the invention depend on a number of parameters, such as the diameter of the distillation column, the feed point, and the number of separation stages in the column, among others. I do. The operating pressure of the distillation system can range from 15 to 500 psia, usually 50 to 400 psia. Typically, increasing the feed rate of the entrainer relative to the feed rate of the mixture to be separated results in an increase in the purity of the product to be recovered with respect to those components being removed. The increase in reflux ratio is
This usually results in a reduced extractant concentration in the distillate stream. However, in general, the reflux ratio is in the range between 1/1 and 200/1. The temperature of the condenser located adjacent to the top of the column is usually sufficient to substantially completely condense the distillate exiting from the top of the column, or to reach the desired reflux ratio by means of partial reduction. Required temperature.

A mixture containing C-318 suitable for purification according to the invention is PFC-C318
It can be obtained from any manufacturing method or manufacturer that produces the contained mixture.
For example, PFC-C318 can be produced by pyrolysis of HCFC-22. Alternatively, the PFC-C318 containing mixture uses PFC-C318,
And it can be obtained from any manufacturing method that desires to recover PFC-C318 from the process. If desired, conventional distillation can also be used to reduce the initial amount of halogenated impurities. That is, the conventional distillation is P
It can also be used to remove relatively large or bulky amounts of halogenated impurities from the FC-C318-containing mixture, which mixture is then
PFC-C318 may be processed according to the methods of the present invention to recover and purify.

EXAMPLES The following examples are provided to illustrate embodiments of the method of the present invention and are not intended to limit the scope of the present invention. The following examples use the NRTL interaction parameters defined above. In the following examples, each stage has 10
Based on 0% operation or performance efficiency. Different column designs and operating conditions were used to maximize the performance of each distillation, with different extractants. In all embodiments, every stage includes a condenser and a reboiler, and the condenser is a stage no. Counted as one. In all examples, the stream flow is in pounds per hour (pph) or moles per hour (mph)
Temperature (“TEMP”) is expressed in degrees Celsius (° C.); concentrations are mole percent (mole%), weight percent (wt%), parts per million (ppm-mo
lar), and expressed in parts per million (ppm-wt) based on weight; heat flow removed from the condenser in the distillation column or introduced into the reboiler ("DUT
IES ") is expressed in pcu / hour or pcu / hr; and pressure (" PRES ") is expressed in pounds per square inch-absolute pressure (psia). The various values are based on distillation column residue ("BTMS"), distillate ("DIST"), condenser ("CONDS").
R "), reflux (" REFLUX "), and top (" TOP "). The values are given for the stream fed to the column for separation ("FEED") and for any extractant fed to the column ("EXTR" or "EXTR FEED"). In these examples, the recovery efficiency ("RECOV.EFF."
) Is the C31 fed to the distillation recovered in the C318 product stream
Means 8 percent.

[0053]Comparative Examples 1, 2, and 3 In Comparative Examples 1 to 3, 980 pph PFC-C318 and 20 pphC _Four F_TenThe mixture containing (PFC-31-10) is fed to a distillation column, and the PFC-C318 product stream is removed from the column as distillate using conventional distillation.
Removed and C_FourF_TenDistillation was performed under conditions such that the product stream was removed as column residue. Table 1 shows specific conditions and results of the distillation.

[0054]

[Table 1]

In Comparative Example 1, the PFC-C318 product stream from this conventional distillation contained 634 ppm mC ₄ F ₁₀ and the PFC-C318 recovery efficiency was only about 82%.

In Comparative Example 2, the number of columns in the tower and the thermal efficiency of the reboiler were twice as large as those in Comparative Example 1. Regardless of this, PFC-C 318 product obtained still contains the C ₄ F ₁₀ of greater than 3Ppmm, and PFC-C 318 recovery efficiency was only about 82%.

In Comparative Example 3, the distillation was performed at a reflux rate that was approximately 10 times the reflux rate of Comparative Example 1, and the removal rate of PFC-C318 residue was approximately one-tenth that of Comparative Example 1. Diminished. Recovery efficiency increased to 99% but, PFC-C 318 product stream was still contain C ₄ F ₁₀ of 6.3Ppmm.

These comparative examples demonstrate the difficulty in obtaining a substantially pure PFC-C318 product stream from a first stream containing PFC-C318 and C ₄ F ₁₀ with high recovery efficiency by conventional distillation. Is specifically shown.

[0059] In Comparative Examples 4 and 5 Comparative Examples 4 and 5 were fed a mixture containing impurities shown in PFC-C 318 and Table 2 below the distillation column. The mixture is purified using conventional distillation to give P
A product stream containing FC-C318 is removed from the column as distillate;
It was then distilled under conditions such that the product stream containing the impurities was removed as column residue. Table 2 shows specific conditions and results of the distillation.

[0060]

[Table 2]

Under the conditions of the distillation of Comparative Example 4, PFC-C318 was only 80% as distillate product
% Recovery efficiency and still contained 94 ppmm of total impurities.

In Comparative Example 5, the number of columns in the column and the reflux rate were all 2 compared to Comparative Example 4.
It is twice. Despite this, PFC-C318 still has only 80% PF
Recovered with C-C318 recovery efficiency and still contained 37 ppmm of total impurities.

[0063] These comparative examples demonstrate that substantially pure PFC-C
318 shows the difficulty of producing a 318 product stream with high recovery efficiency from a first stream containing various impurities common to PFC-C318 and PFC-C318 process streams.

Comparative Examples 6, 7, 8, 9 In Comparative Examples 6, 7, 8 and 9, streams containing 394 pph of PFC-C318 and 606 pph of HFC-134 were fed to the distillation column. Table 3
These were distilled using the various conditions shown in Table 1 and gave the results shown in Table 3.

[0065]

[Table 3]

As can be seen in these comparative examples, over a wide range of distillate rates, residue rates and reflux rates, this distillation results in a PFC from HFC-134.
There is essentially no separation of FC-C318. This is because PFC-C31
8 and HFC-134 feed rate at the operating conditions of the column
This is because it constitutes a composition of an azeotrope formed by No. 18 and HFC-134. This comparative example illustrates the futility of separating an azeotropic composition containing PFC-C318 and HFC-134 by conventional distillation.

[0067] In Comparative Examples 10, 11, 12, 13 Comparative Examples 10, 11, 12 and 13, PFC-C318 and HFC
The mixture containing -134 was fed to the distillation column. Table 4 shows the conditions and results of these distillations.

[0068]

[Table 4]

In these comparative examples, the distillation column was operated under conditions such that the composition of the PFC-C318 / HFC-134 azeotrope was formed at a PFC-C318 concentration lower than the PFC-C318 concentration of the feed mixture. did. Low boiling point HFC-134 / PFC-C
The 318 azeotrope went overhead in the column, and PFC-C 318 fed above the azeotrope composition was recovered in the column residue stream.

As the reflux rate increased between Comparative Examples 10, 11, 12 and 13, the efficiency of the distillation column in separating excess PFC-C318 from the azeotropic composition increased, thus increasing the excess PFC-C318 mostly free of HFC-134
As a column residue. However, obtaining this enhanced efficiency requires a significant increase in reflux rate and a significant decrease in distillate product rate. In addition, some of the supplied PFC-C318 will necessarily remain in the distillate as part of the composition of the PFC-C318 / HFC-134 azeotrope and the PFC-C318 recovery possible from such azeotropic distillation Limit efficiency.

Nevertheless, these comparative examples demonstrate that PFC-C318 and HF were used to obtain a PFC-C318 product stream substantially free of HFC-134.
How low boiling azeotropic compositions containing C-134 can be used to form PFC-C3
FIG. 4 shows whether HFC-134 can be removed from a first mixture containing 18 and HFC-134.

Comparative Examples 14, 15, 16, 17 In Comparative Examples 14, 15, 16, and 17, PFC-C318 and HFC
The mixture containing -134 was fed to the distillation column. Table 5 shows the conditions and results of these distillations.

[0073]

[Table 5]

In these comparative examples, under distillate temperature conditions such that a composition of the PFC-C318 / HFC-134 azeotrope is formed at an HFC-134 concentration lower than that of the feed mixture. The distillation column was operated. Low boiling point HFC-134 / PF
The C-C318 azeotrope went overhead in the column, and the HFC-134 fed above the azeotrope composition was recovered in the column residue stream.

As the reflux rate increases and the distillate rate decreases between Comparative Examples 14, 15, 16 and 17, the efficiency of the distillation column in separating excess HFC-134 increases, thus HF in which the excess is substantially free of PFC-C318
It can also be recovered as C-134. However, this increased efficiency requires a significant increase in reflux rate and a decrease in distillate product rate, increasing the energy expended in distillation. Furthermore, the supplied HFC-13
Some of H.4 will always remain in the distillate as part of the composition of the PFC-C318 / HFC-134 azeotrope and is possible from such azeotropic distillation.
Limit recovery efficiency.

Nevertheless, these comparative examples demonstrate that PFC-C318 and HF were used to obtain an HFC-134 product stream substantially free of PFC-C318.
How low boiling azeotropic compositions containing C-134 can be used to form PFC-C3
FIG. 6 shows whether PFC-C318 can be removed from a first mixture containing 18 and HFC-134.

[0077] In Comparative Examples 18 and 19 Comparative Examples 18 and 19, were fed feed stream containing PFC-C 318 and C ₄ F ₁₀ to the distillation column which is operated under the conditions shown in Table 6. PFC-
The extractant stream containing perfluorohexane (C ₆ F ₁₄₎ as an extractant stream at a point above the C318 / C ₄ F ₁₀ feed point of the feed to the column. Table 6 shows the results of these distillations.

[0078]

[Table 6]

In Comparative Examples 18 and 19, the feed stream composition was identical to that of Comparative Examples 1, 2 and 3. Extremely high extractant feed rate, extremely high tower, and extremely even at high reflux rate, C ₄ F ₁₀ concentration of PFC-C 318 product had been reduced down only slightly below 100Ppmm. Comparative Examples 18 and 19
It shows that when C ₆ F ₁₄ is used as the extractant, it does not provide any advantage over the conventional distillations shown in Comparative Examples 1, 2 and 3 for this separation. C ₆ F ₁₄ is an example of the extractive distillation by PFC-C 318 and C ₄ F separation Many compounds are not effective as an extractant to facilitate the _10.

[0080] In each of Examples 20 to 31 Example 20 31 supplies the crude feed stream containing HFC-C 318 and C ₄ F ₁₀ to the distillation column was operated under the conditions shown in Table 7. HFC-C3 in the feed stream for each of Examples 20 to 31
The concentrations of 18 and C ₄ F ₁₀ were the same as those of Comparative Examples 1, 2, _3, 18 and 19.

In each of Examples 20 to 31, different compounds were fed to the column as extractants. By operating the distillation column in these examples, the removing C ₄ F ₁₀ from the column as an overhead distillate, while was recovered PFC-C 318 product as the column residue. Table 7 shows the extractant and distillation results for each example.

[0082]

[Table 7-1]

[0083]

[Table 7-2]

By comparing these examples with Comparative Examples 1, 2, 3 and Comparative Examples 18 and 19, the extractants of Examples 20 to 33 significantly increase the efficiency of the distillation for this separation and therefore the C ₄ F ₁₀ seen to be an effective extractant for the separation from the PFC-C 318. PFC-C 318 having a C ₄ F ₁₀ of significantly reduced concentration relative to crude feed stream is recovered in PFC-C 318 raw composition as from the distillation column residues. Concentrations of C ₄ F ₁₀ of less than ₁₀ ppmm in the PFC-C318 product are extremely difficult or impossible to obtain in the comparative examples, whereas 1 ppmm of C ₄ F _{10 in} the PFC-C318 product Concentrations are obtained with high recovery efficiency of the PFC-C318 product in each of the examples in Table 7.

The eleven extractants were listed in order from the most effective to the least effective for PFC-C318 / C ₄ F ₁₀ separation. More effective ones are identified by those that require a lower molar flow rate of the extraction agent needed to produce a PFC-C 318 product containing 1ppmmC ₄ F _10. Based on this, the ranking of the extractants that are effective from "highest" to "lowest" is acetone, methyl ethyl ketone (MEK
), Tetrahydrofuran (THF), 1,4-dioxane, chloroform (CH
Cl _3), methanol, methyl tertiary butyl ether (MTBE), cyclohexane (CYANE), toluene, diethyl ether (DEE), and n-
Hexane. All of these extractants, reversed the standard ratio volatility of PFC-C 318 and C ₄ F ₁₀ as compared to distillation as conventionally Comparative Examples 1, 2 and 3, therefore, the presence of the extraction solvent C ₄ F ₁₀ is recovered in the distillate stream, whereas, PFC-C 318 was recovered as extractive distillation column residue. The extractant shown in each of Examples 20 to 33 exiting from the tower residue with PFC-C318 may optionally be separated from PFC-C318 by distillation or other methods.

[0086] Acetone is Ru one der the PFC-C318 / C ₄ F ₁₀ most effective extractant for the separation of acetone to form a low boiling azeotrope with PFC-C 318. ME
K, THF and 1,4-but-dioxane is almost equally effective just all in separating PFC-C 318 and C ₄ F _10, MEK and 1,4-dioxane PFC-C 318 and two liquids in the extraction tower Phases are formed, requiring more extractant flow, and increasing the difficulty of operating the column. Thus, the most preferred extractant for this separation is THF, followed by MEK and 1,4-dioxane.

[0087] In Example 32 This example, PFC-C 318 and C ₄ F ₁₀ supplies a stream containing the extraction distillation _{column, PFC-C318 / C 4 F} 10 extraction agent at points above the feed point of the Was fed to the column. Then, the P from the extraction tower
The residue stream containing FC-C318 and the THF extractant was fed to a stripping tower. In stripping column, to give the PFC-C 318 that does not include both the C ₄ F ₁₀ and THF extraction agent substantially as distillate product, whereas, THF
The extractant was recovered as a residual product and then recycled back to the extraction column as extractant feed. The operating conditions and results of these distillations are shown in Table 8.

[0088]

[Table 8]

This example shows how the extractive distillation of the present invention can be used to_FourF_TenPFC-318 product that is substantially free of both PTH-C318 and the THF extractant
Indicates whether to manufacture with high recovery efficiency. 980 pph of PFC-C318 and 20p
ph C_FourF_TenStarting from a feed stream containing 1.0 ppm mC_FourF _Ten And a PFC-C318 product containing 0.05 ppm mTHF
Obtained with the recovery efficiency of PFC-C318.

Example 33 Table 9 shows that CFC-114, HCFC-124a, CFC-217ba and PFC
Crude raw material PFC-C318 containing halogenated impurities including FC-1318my
Figure 2 shows both extractive distillation and stripping steps to purify the feed. The extractant used was THF. The PFC-C318 product was recovered as an extractor distillate substantially free of both halogenated impurities and THF. The halogenated impurities were recovered with the THF in the extractor residue stream, and this residue stream was then sent to the stripping tower as feed. The stripping tower removes organic impurities from the THF, recovers the organic impurities as stripping tower distillate, collects the THF as stripping tower residue, and then recycles the extractant feed back to the extraction tower. Was.

[0091]

[Table 9]

Examples 34-40 Table 10 shows seven specific examples of different extraction solvents for removing PFC-C318 from HFC-134 to produce substantially pure HFC-134. P
Seven extractants are shown in order from most effective to less effective in separating FC-C318 / HFC-134. More effective are those identified by those requiring a lower molar flow rate of extractant required to produce 0.1 ppm mPFC-C318 in the HFC-134 residual product. Based on this, "highest"
The order of validity is from 1,4-dioxane, tetrahydrofuran (TH
F), methyl ethyl ketone (MEK), methyl tertiary butyl ether (MT
BE), methanol, toluene and propanol. In the presence of the extraction solvent, PFC-C318 is a PFC substantially free of both HFC-134 and the extractant.
Recovered in the distillate stream as FC-C318 product, while HFC
-134 was recovered together with the extractant as extractive distillation column residue. The indicated extractant may then optionally be separated from HFC-134 by distillation or other methods.

[0093]

[Table 10]

[0094] Example 41 and 42 Table 11 shows the both operating conditions and results for Examples 41 and 42. These examples show that each of PFC-C318 and HFC-134 has 60.
6% by weight HFC-134 (75.1 mol%) and 39.4% by weight PFC-C3
1 shows an extractive distillation using THF recovered as an extractant from a feed mixture containing 18 (24.9 mol%). The feed composition is HFC-distilled at these distillation temperatures.
134 and an azeotropic composition formed by PFC-C318. As shown in Comparative Examples 6, 7, 8 and 9, HFC-134 and PFC-C318
It is practically impossible to separate the azeotropic compositions of the above by conventional distillation.

However, Examples 41 and 42 show that extractive distillation using THF as the extractant allows for its separation. In Example 41, the PFC-C318 product recovered as a distillation column distillate contained 0.1 ppmm total impurities (HFC-
134 and THF) and the recovery of the PFC-C318 product exceeded 99% of the PFC-C318 in the feed to the column. In Example 42, HFC
-134 product contains 0.1 ppm mPFC-C318 and HFC-1
Recovery of the 34 product was substantially 100% of the HFC-134 in the feed to the column.

[0096]

[Table 11]

[0097] In Example 43, 44 Examples 43 and 44, supplies a stream containing PFC-C 318 and C ₄ F ₁₀ to the extractive distillation column, where from point of THF a PFC-C318 / C ₄ F ₁₀ supplies At the above point, it was fed to the column as extractant. The operating conditions and results of these distillations are shown in Table 12.

[0098]

[Table 12]

Example 43 is the same as Example 22 above and has 99.5% P as an extractor residue stream containing PFC-C318 containing 1.0 ppm mC ₄ F _10.
A PFC-C318 product was produced with FC-C318 recovery efficiency. In Example 44, the extractant flow to the column is increased compared to the flow of Example 43, and the extractant flow is increased to 0.1.
Was prepared PFC-C 318 product in 99.5% PFC-C 318 recovery efficiency as extraction column residue stream comprising PFC-C 318 containing 1ppmmC ₄ F _10.

Example 45 This example demonstrates PFC-C318 and HCFC-124; PFC-C318
And HCFC-124a; PFC-C318 and HFC-134;
C318 and HFC-134a; and PFC-C318 and HFC-15
2 illustrates the presence of an azeotropic or azeotropic composition between the binary mixtures consisting essentially of 2a. The PTx method was used to measure the relative volatility of each binary system. In this procedure, for each binary system, the total absolute pressure in a known volume of the sample cell was measured at a constant temperature for various known binary compositions. These measurements were then converted to equilibrium vapor and liquid compositions using the NRTL equation.

The measured vapor pressure for the composition in the PTx cell for these binary systems is shown in FIGS. 3 to 7, respectively. The points in the experimental data are shown as solid points in each figure,
A solid line was drawn from data calculated using the NRTL equation.

Reference is now made to FIG. FIG. 2 shows 26.9 mol% PFC-C318 and 73.1 mol% HCFC- having the highest pressure at 20 ° C. over its composition range.
FIG. 3 illustrates the formation of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HCFC-124 at 20 ° C., as indicated by the mixture of 124.
Based on these findings, an azeotropic or azeotropic composition of 26.9 mole% PFC-C318 and 73.1 mole% HCFC-124 was formed at 0 ° C. and 24 psia, and 27.5 mole% PFC- C318 and 72.5 mol% HCFC-
It was calculated that 124 azeotropic or azeotropic compositions formed at 80 ° C. and 234 psia. Therefore, the present invention provides a method for preparing PFC-
Providing an azeotropic or azeotropic composition consisting essentially of C318 and 73.1 to 72.5 mol% HCFC-124, wherein the composition is at 24 psia at 0 ° C. to 234 p.
It has a boiling point up to 80 ° C. in sia.

Reference is now made to FIG. FIG. 3 shows 22.4 mol% PFC-C318 and 67.6 mol% HCFC- having the highest pressure at 20 ° C. over its composition range.
FIG. 4 illustrates the formation of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HCFC-124a at 20 ° C., as indicated by the mixture of 124a. Based on these findings, 33.1 mol% PFC-C318 and 66.9
Mole% HCFC-124a azeotropic or azeotropic composition at 0 ° C. and 24 psia
And 33.9 mol% PFC-C318 and 66.1 mol% HC
It was calculated that an azeotropic or azeotropic composition of FC-124a was formed at 80 ° C. and 229 psia. Therefore, the present invention provides 33.1 to 33.9 mol%
Provided is an azeotropic or azeotropic composition consisting essentially of PFC-C318 and 66.9 to 66.1 mole% HCFC-124a, the composition having a boiling point from 0 ° C at 24 psia to 80 ° C at 229 psia. Have.

Reference is now made to FIG. FIG. 4 shows 25.0 mol% PFC-C318 and 75.0 mol% HFC-13 having the highest pressure at 0 ° C. over their composition range.
PFC-C318 and HFC at 0 ° C. as indicated by the mixture of
3 illustrates the formation of an azeotropic and azeotropic composition consisting essentially of -134. Based on these findings, 24.6 mol% PFC-C318 and 75.4 mol% HFC
An azeotropic or azeotropic composition of -134 is formed at -30 ° C and 10 psia;
It was calculated that an azeotropic or azeotropic composition of 23.2 mol% PFC-C318 and 76.8 mol% HFC-134 was formed at 80 ° C and 326 psia. Therefore, the present invention relates to 24.6 to 23.2 mol% of PFC-C318.
And an azeotropic or azeotropic composition consisting essentially of 75.4 to 76.8 mole% HFC-134, wherein the composition is at -30 ° C to 326 psia at 10 psia.
With a boiling point up to 80 ° C.

Please refer to FIG. FIG. 5 shows 7.4 mol% PFC-C318 and 92.6 mol% HFC-134 having the highest pressure over the range of their composition at 0 ° C.
PFC-C318 and HFC at 0 ° C. as indicated by the mixture of
3 illustrates the formation of an azeotropic and azeotropic composition consisting essentially of -134a. Based on these findings, 9.9 mol% PFC-C318 and 90.1 mol% HFC
An azeotropic or azeotropic composition of -134a is formed at -30 ° C and 12 psia, and 0.6 mol% PFC-C318 and 99.4 mol% HFC-134a
Was formed at 40 ° C. and 147 psia. Accordingly, the present invention provides an azeotropic or azeotropic composition consisting essentially of 9.9 to 0.6 mol% PFC-C318 and 90.1 to 99.4 mol% HFC-134a, wherein said composition comprises The material is -30 psi to about 147 psi at 12 psia
It has a boiling point at 40 ° C. at a.

Reference is now made to FIG. FIG. 6 shows 23.1 mol% PFC-C318 and 76.9 mol% HFC-15 having the highest pressure at 0 ° C. over their composition range.
PFC-C318 and HF at 0 ° C. as shown by the mixture of 2a
3 illustrates the formation of an azeotropic and azeotropic composition consisting essentially of C-152a. Based on these findings, 22.4 mol% PFC-C318 and 77.6 mol% H
An azeotropic or azeotropic composition of FC-152a is formed at −20 ° C. and 19 psia, and 21.3 mol% PFC-C318 and 78.7 mol% HFC-1
It was calculated that an azeotropic or azeotropic composition of 52a was formed at 80 ° C. and 234 psia. Accordingly, the present invention relates to a method for preparing 23.1 to 21.3 mol% PFC-
Providing an azeotropic or azeotropic composition consisting essentially of C318 and 76.9 to 78.7 mole% HFC-152a, wherein the composition is -20 to 34 ° C at 19 psia.
It has a boiling point of up to 80 ° C. at 9 psia.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a distillation system that can be used to perform one embodiment of the method of the present invention.

FIG. 2 is a graphical representation of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HCFC-124 at a temperature of 20 ° C.

FIG. 3 is a graphical representation of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HCFC-124a at a temperature of 20 ° C.

FIG. 4 is a graphical representation of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HFC-134 at a temperature of 0 ° C.

FIG. 5 is a graphical representation at a temperature of 0 ° C. of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HFC-134a.

FIG. 6 is a graphical representation of an azeotropic and azeotropic composition consisting essentially of PFC-C318 and HFC-152a at a temperature of 0 ° C.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] May 20, 2000 (2000.5.20)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

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[0007] Conventional methods for producing PFC-C318 products do not allow removal of various halogenated impurities from the PFC-C318 product, and therefore produce PFC-C318 having a purity of 99.999 or higher mole percent. It is not possible to manufacture. PFC- with 99.999 or higher mole percent purity
The manufacture of C318 was not known before the present invention. In British Patent GB 886,714, Wist was aromatic or chlorinated as an extractant to separate perfluoropropylene and perfluorocyclobutane mixtures from other halogenated compounds obtained from the pyrolysis of chlorodifluoromethane. An extractive distillation process using aromatic hydrocarbons is disclosed.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mahler Barry Usher United States 19342 Glen Mills Carter Way, Pennsylvania 104 (72) Inventor Miller Ralph Newton United States 19711 Newark Hillstream Road, Delaware 39 F-term (reference) 4H006 AA02 AD12 AD40 BB11 BB12 BB14 BB15 BB16 BB25 BD82 EA12 [Continued Summary] An extractive distillation process that separates PFC-C318 from halogenated impurities by using an entrainer selected from carbons.

Claims (19)

[Claims] 1. Perfluorocyclobutane (PFC-C318), characterized in that it contains less than 10 parts per million of halogenated impurities. 2. Perfluorocyclobutane (PFC-C318) containing less than one part per million of halogenated impurities. 3. Perfluorocyclobutane (PFC-C318), characterized in that it contains less than 100 parts per billion of halogenated impurities. 4. 26.8 to 27.5 mole percent of perfluorocyclobutane (PFC-C318) and 73.1 to 72.5 mole percent of 2-
An azeotropic or azeotropic composition consisting essentially of chloro-1,1,1,2-tetrafluoroethane (HCFC-124), having a boiling point of 0 ° C. at 24 psia to 80 ° C. at 234 psia. A composition comprising: 5. 24.6 to 23.2 mole percent of perfluorocyclobutane (PFC-C318) and 75.4 to 76.8 mole percent of 1,
An azeotropic or azeotropic composition consisting essentially of 1,2,2-tetrafluoroethane (HFC-134) at -30 ° C to 326p at 10 psia.
A composition having a boiling point of 80 ° C. in sia. 6. 9.9 to 0.6 mole percent of perfluorocyclobutane (PFC-C318) and 90.1 to 99.4 mole percent of 1,1,
An azeotropic or azeotropic composition consisting essentially of 1,2-tetrafluoroethane (HFC-134a) at -30 ° C to 147 ps at 12 psia.
A composition having a boiling point in ia of 40 ° C. 7. 23.1 to 21.3 mole percent of perfluorocyclobutane (PFC-C318) and 76.9 to 78.7 mole percent of 1,
An azeotropic or azeotropic composition consisting essentially of 1-difluoroethane (HFC-152a), characterized in that it has a boiling point of -20C at 19 psia to 80C at 349 psia. 8. A method according to claim 1, wherein the first mixture containing perfluorocyclobutane (PFC-C318) and halogenated impurities is converted to perfluorocyclobutane (PFC-C318).
C318), wherein the amount of perfluorocyclobutane (PFC-C318) in said first mixture is determined by the amount of perfluorocyclobutane (PFC-C3).
18) and the amount of perfluorocyclobutane (PFC-C318) in the azeotropic or azeotropic composition containing impurities, and distilling said first mixture to obtain perfluorocyclobutane (PFC-C318).
) And a second mixture containing an azeotropic or azeotropic composition containing impurities, recovering the second mixture as a distillation column overhead stream, and using a perfluorocyclobutane (PFC-C318) as a distillation column bottom stream.
). 9. A method for separating at least one halogenated impurity from a first mixture containing perfluorocyclobutane (PFC-C318) and halogenated impurities, wherein the halogenated impurities in the first mixture are separated. Is greater than the amount of halogenated impurities in the azeotropic or azeotropic composition containing perfluorocyclobutane (PFC-C318) and impurities, and the first mixture is distilled to obtain perfluorocyclobutane (PFC-C318). -C318
) And forming a second mixture containing an azeotropic or azeotropic composition containing halogenated impurities, recovering the second mixture as a distillation column overhead stream, and recovering the halogenated impurities as a distillation column bottom stream. A method characterized in that: 10. Perfluorocyclobutane (PFC-C) in the presence of an entrainer
318) and a step of distilling a mixture containing the halogenated impurities from the halogenated impurities to perfluorocyclobutane (PFC-C31).
8) The method of separating. 11. In the presence of an entrainer, perfluorocyclobutane (PFC-
11. The method according to claim 10, wherein the volatility of C318) or impurities is enhanced with respect to one another. 12. A method for separating perfluorocyclobutane (PFC-C318) and halogenated impurities, comprising contacting a first mixture containing perfluorocyclobutane (PFC-C318) and halogenated impurities with an entrainer. To form a second mixture, and distilling said second mixture, and removing the perfluorocyclobutane (PFC-C3
Recovering a distillation column overhead stream containing 18) and a distillation column bottom stream containing the entraining agent and impurities. 13. A method for separating perfluorocyclobutane (PFC-C318) and halogenated impurities, comprising contacting a first mixture containing perfluorocyclobutane (PFC-C318) and halogenated impurities with an entrainer. To form a second mixture, and distill said second mixture, and a distillation column overhead stream containing halogenated impurities, an entrainer and perfluorocyclobutane (PFC-C3
Recovering the bottom stream of the distillation column containing 18). 14. The method according to claim 14, wherein the first mixture is a perfluorocyclobutane (PFC).
14. A process according to claim 12 or 13 comprising an azeotropic or azeotropic composition of -C318) and impurities. 15. The halogenated impurities include PFC-31-10 (C ₄ F ₁₀ ), PFC-41-12 (C ₅ F ₁₂ ), and PFC-1318my (cis and trans-CF ₃ CF = CFCF _{3). ), PFC-1318c (CF 3} CF 2 CF = CF 2), PFC-1216 (CF 3 CF = CF 2), PFC-1114 (CF 2 = CF 2), perfluoroisobutene (CF ₂ = C (CF ₃ ) ₂ ), CFC-114 (CF ₂ ClCF ₂ Cl), CFC-114a (CFCl ₂ CF ₃ ), CFC-216ba (CF ₃ CFClCF ₂ Cl), CFC-217ba (CF ₃ CClFCF ₃ ), C
FC-1113 (CCIF = CF ₂ ), HCFC-124 (CHFCClCF ₃ ),
_{HCFC-124a (CClF 2 CHF 2} ), HFC-134 (CHF 2 CHF 2)
_{, HFC-134a (CH 2 FCF} 3), HFC-152a (CH 3 CF 2 H), H
FC-125 (CF ₃ CF ₂ H), HFC-227ca (CF ₃ CF ₂ CHF ₂ ), HFC-227ea (CF ₃ CHFCF ₃ ), HFC-1225zc (CF ₃ CH = CF ₂ ), HFC-236ca (CHF ₂ CF ₂ CHF ₂ ), HFC-236ea
(CHF ₂ CHFCF ₃ ), HFC-236fa (CF ₃ CH ₂ CF ₃ ), HCC-30 (CH ₂ Cl ₂ ), HCC-40 (CH ₃ Cl), and HCC-160 (CH ₃ CH ₂ Cl) 10. The composition according to claim 8, wherein at least one of them is contained.
14. The method according to 10, 12, or 13. 16. The method according to claim 10, wherein the entraining agent is selected from the group consisting of ethers, ketones, alcohols, hydrocarbons, and hydrochlorocarbons. The described method. 17. The ethers are selected from the group consisting of methyl tertiary butyl ether, tetrahydrofuran, and 1,4-dioxane; the ketones are propanone (acetone) and 2-butanone (methyl ethyl ketone).
The alcohols are selected from the group consisting of methanol and propanol; the hydrocarbons are selected from the group consisting of toluene and cyclohexane; and the hydrochlorocarbons are selected from the group consisting of chloroform. 17. The method of claim 16, wherein the method is selected. 18. The perfluorocyclobutane (PFC-C318)
13. The method according to claim 8, wherein the liquid is recovered substantially without impurities.
Or the method of 13. 19. The perfluorocyclobutane (PFC-C318)
14. The process according to claim 8, 10, 12, or 13, characterized in that it is recovered containing less than 10 parts per million of impurities.