Compositions and methods for purifying cfc-113 by adsorption

Abstract

The invention is entitled "Compositions and methods for purifying CFC-113 by adsorption." A method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) is disclosed, the method comprising providing an untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). The untreated composition is treated with an adsorbent to form a treated composition, wherein the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) is less than 93% of the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition based on a 24 hour treatment time.

Description

[0001] This application claims the benefit of U.S. Application No. 62 / 937,120, filed November 18, 2019. The disclosure of 62 / 937,120 is incorporated herein by reference. TECHNICAL FIELD

[0002] The present invention relates to a process for separating CFC-113 and CFC-113a. BACKGROUND

[0003] Compositions used as refrigerants desirably exhibit similar properties at both the evaporator and compressor of a refrigeration system. One technique to obtain uniform properties is to use a single substance as the refrigerant, however the synthesis of refrigerants often results in a mixture of isomers. The synthesis of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) also results in the formation of the structural isomer 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). In numerous conventional synthesis schemes, these structural isomers are separated by distillation based on the boiling point difference of the structural isomers. In the case of (CFC-113) and (CFC-113a), the boiling points of these compounds differ by only 1.3 degrees Celsius, making it difficult to separate them by distillation.

[0004] 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) is also used as a precursor for the synthesis of chlorotrifluoroethylene (CTFE) by reaction with hydrogen (H2) or various metals such as zinc. If 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) is also present in the reaction, it will be converted to 1,1-dichloro-2,2-difluoroethylene (CFC-1112a) and 2-chloro-1,1-difluoroethylene (CFC-1122), which are undesirable in combination with chlorotrifluoroethylene (CTFE). It is difficult to separate 1,1-dichloro-2,2-difluoroethylene (CFC-1112a) and 2-chloro-1,1-difluoroethylene (CFC-1122) from chlorotrifluoroethylene (CTFE) by distillation.

[0005] There is a desire in the art for a more facile and more efficient process for separating (CFC-113) and (CFC-113a). SUMMARY

[0006] In one exemplary embodiment, a method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) includes providing an untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). The method also includes contacting the untreated composition with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), thereby forming a treated composition. The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is reduced by more than 7% over a 24 hour contact time, based on the concentration of said 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition.

[0007] In another exemplary embodiment, a method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) includes providing an untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). The method also includes contacting the untreated composition with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), thereby forming a treated composition. The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is reduced by more than 10% over a 1 week contact time, based on the concentration of said 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition.

[0008] The present invention includes the following aspects and embodiments:

[0009] In one embodiment, disclosed herein is a method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). The method includes providing an untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), and contacting the untreated composition with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), thereby forming a treated composition. The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is reduced by more than 7% based on the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a).

[0010] According to any of the above embodiments, also disclosed herein is a method wherein the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than about 0.1 wt.%.

[0011] According to any of the above embodiments, also disclosed herein is a method wherein the selective adsorbent comprises carbon.

[0012] According to any of the above embodiments, also disclosed herein is a method wherein the selective adsorbent comprises nickel or copper.

[0013] According to any of the above embodiments, also disclosed herein is a method further comprising treating the selective adsorbent with hydrogen gas prior to contacting the untreated composition.

[0014] According to any of the above embodiments, also disclosed herein is a method wherein the amount of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) plus 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition is at least 98 wt.% based on the total weight of the untreated composition.

[0015] According to any of the above embodiments, also disclosed herein is a method wherein the contacting of the untreated composition with the adsorbent is for a contact time of 24 hours.

[0016] According to any of the above embodiments, also disclosed herein is a composition formed by any of the above methods.

[0017] In one embodiment, disclosed herein is a method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). The method includes providing an untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), and contacting the untreated composition with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), thereby forming a treated composition. The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is reduced by more than about 7%, more than about 8%, and in some cases more than about 10%, based on the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition, over a contact time of about 30 minutes to about 1 week.

[0018] According to any of the above embodiments, also disclosed herein is a method wherein the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than about 0.1 wt.%.

[0019] According to any of the above embodiments, also disclosed herein is a method wherein the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than 0.05 wt.%.

[0020] According to any of the above embodiments, also disclosed is the use of the CFC-113 containing composition of the present invention in the production of CTFE.

[0021] Embodiments of the present disclosure can be used alone or in combination with each other. Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiments thereof, exemplifying the principles of the invention. DETAILED DESCRIPTION

[0022] The present invention provides a method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) by liquid phase adsorption.

[0023] The ability of an adsorbent to interact with the species of a mixture is related to the surface energy of that adsorbent. Separation via adsorption relies on differences in the interactions between the surface groups of the adsorbent and the components of the composition being contacted.

[0024] 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2- trifluoroethane (CFC-113a) have the same chemical formula and are structural isomers of each other. Mixtures of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) can be separated by partitioning 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) onto a selective adsorbent while 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) remains in the mobile liquid phase. The ability of the selective adsorbent to bind (CFC-113a) in the (CFC-113) / (CFC-113a) mixture depends on the material of the adsorbent surface and the surface groups.

[0025] In some embodiments, the selective adsorbent treatment reduces the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) / 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) mixture by at least 7% based on the concentration of (CFC-113a) prior to treatment.

[0026] In some embodiments, the weight ratio of selective adsorbent to 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) / 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) untreated composition is at least 1:30, at least 1:25, at least 1:20, at least 1:15, at least 1:10, at least 1:5, at least 1:3, at least 1:2, less than 1:1, and combinations and subcombinations thereof.

[0027] In some embodiments, the temperature for selective adsorption is greater than about 0°C to about 45°C (Celsius), about 5°C to about 40°C, and in some cases greater than about 10°C to about 35°C.

[0028] In some embodiments, the pressure for selective adsorption is variable and is generally atmospheric pressure, and in some cases sub-atmospheric to atmospheric pressure.

[0029] In some embodiments, the surface of the adsorbent can include a metal. In some embodiments, the surface of the adsorbent can include a transition metal. In some embodiments, the surface of the adsorbent can include nickel or copper. In some embodiments, the adsorbent can include activated carbon. In some embodiments, the adsorbent can include nickel on carbon (Ni / C) or copper on carbon (Cu / C). The amount of metal loading can range from about 2 wt% to about 25 wt%, from about 5 wt% to 20 wt%, and in some cases from about 10 wt% to 15 wt% of the adsorbent.

[0030] The surface of the adsorbent can be treated to impart additional functional groups to the surface of the adsorbent. In some embodiments, the surface treatment can include exposure to hydrogen gas (H2). In some embodiments, the activated carbon can be dried at high temperature under a nitrogen (N2) atmosphere. In some embodiments, the surface treatment can be performed at high temperature. In some embodiments, the surface treatment can be performed at a temperature of at least 100 °C, at least 150 °C, at least 200 °C, at least 250 °C, less than 350 °C, less than 300 °C, less than 260 °C, and combinations and subranges thereof. The surface treatment can be performed prior to the initial contact between the adsorbent and the composition. The surface treatment can also be performed during regeneration of the adsorbent. In some embodiments, the adsorbent is subjected to surface treatment prior to initial use of the adsorbent and during regeneration.

[0031] The particle size of the adsorbent can range from about 4 mesh to about 20 mesh, from about 6 mesh to about 16 mesh, and in some cases from about 7 mesh to about 14 mesh. The surface area and pore size of the adsorbent particles can be tailored using conventional methods known in the art of adsorbents.

[0032] In some embodiments, treatment of an untreated composition of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) based on a contact time of about 30 minutes can reduce the concentration of (CFC-113a) in the treated composition to less than 93%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% of the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition.

[0033] In some embodiments, treating an untreated composition of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) can reduce the concentration of (CFC-113a) in the treated composition to less than 93%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, or 7% of the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition, based on the contact time of one week.

[0034] In some embodiments, the concentration of (CFC-113a) in the treated composition can be reduced to less than 0.10 wt%, less than 0.05 wt%, 0.01 wt%, and subranges of the untreated composition, based on the total amount of (CFC-113) and (CFC-113a) in the untreated composition.

[0035] The treatment of the untreated composition can be performed in a batch or continuous process. In some embodiments, the untreated composition can be contacted with the adsorbent in a batch process. In one embodiment, the batch process is performed in a glass or metal lined reaction vessel.

[0036] In some embodiments, the treatment of the untreated composition can be performed in a continuous process. In some embodiments, the untreated composition can be contacted with the adsorbent in a fluidized bed reactor. In some embodiments, the untreated composition can be contacted with the adsorbent in a fixed bed reactor.

[0037] In some embodiments, the contact time for removing CFC-113a from a CFC-113 containing composition can range from about 30 minutes to about 1 week, from about 60 minutes to about 4 days, and in some cases, from about 90 minutes to about 1 day.

[0038] The CFC-113 containing compositions produced by the present application can be used as precursors for the production of CTFE. Examples of processes for converting the CFC-113 of the present application to CTFE are disclosed by US 20100036178 Al (e.g., converting 113 to CTFE by reaction with a reactive metal such as Zn) and US 10696613 Bl (e.g., converting 113 to CTFE by gas phase dechlorination with H2 in the presence of a catalyst). The resulting CTFE containing compositions can be converted to copolymers, for example, using the methods disclosed in US 20150094428 Al (e.g., using CTFE as a monomer to make copolymers). The disclosures of the above patents and patent applications are incorporated herein by reference.

[0039] The following examples are provided to illustrate certain embodiments of the present application and should not limit the scope of the claims appended hereto.

[0040] Embodiments

[0041] General procedure for the adsorption of (CFC-113a) from (CFC-113) liquid phase in Examples 1-7.

[0042] Prior to use, molecular sieves 13X, BPL carbon and dry Calgon Sulfusorb were dried at 250 °C overnight. Prior to use, H2activated Calgon SULFUSORB and BASF E474 TR (Ru, 1 / 8" pellets) were treated with H2at 250 °C for three hours.

[0043] Prior to use, CFC-113 feedstock was dried with 3 angstrom molecular sieves. The CFC-113 feedstock was mixed with the adsorbent in a glass bottle at room temperature. The glass bottle was sealed with a cap and the glass bottle was shaken for about 5 minutes. The shaken mixture was allowed to stand at room temperature for the time period specified in Table 1. The resulting material was analyzed using a gas chromatograph (GC) with a flame ionization detector (FID). The concentration of CFC-113a in the feedstock and the treated material is shown in Table 1 below.

[0044] Table 1

[0045]

[0046]

[0047] In the above examples of the application, treatment of compositions containing both (CFC-113) and (CFC-113a) resulted in a decrease in the concentration of (CFC-113a) in the resulting treated sample. Pretreatment of microporous metal adsorbents such as nickel with a reducing atmosphere resulted in improved selectivity of the adsorbent for (CFC-113a).

[0048] Further, in the above examples, an increase in adsorbent loading resulted in an increase in the decrease in the resulting (CFC-113a) concentration that was greater than the change in weight ratio.

[0049] While the application has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from the central scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this application, but that the application will include all embodiments falling within the scope of the appended claims.

Claims

1. A method for separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), the method comprising: An untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) is provided; The untreated composition is contacted with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) to form a treated composition, wherein the selective adsorbent is carbon-supported copper (Cu / C) and the amount of metal loading is in the range of 5% to 20% by weight of the adsorbent. The selective adsorbent is present in a weight ratio of at least 1:5 to the untreated composition of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) / 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), and the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is reduced by more than 7% based on the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) during a 24-hour contact period; and The adsorbent is treated with hydrogen gas before contacting the untreated composition.

2. The method according to claim 1: The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than 0.1% by weight.

3. The method according to claim 2: The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than 0.05% by weight.

4. The method according to claim 1: Based on the total weight of the untreated composition, the amount of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) plus 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition is at least 98 by weight.

5. The method according to claim 1: The contact time between the untreated composition and the adsorbent is at least 30 minutes.

6. A method for separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), the method comprising: An untreated composition comprising 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) is provided; The untreated composition is contacted with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) to form a treated composition, wherein the selective adsorbent is carbon-supported copper (Cu / C) and the amount of metal loading is in the range of 5% to 20% by weight of the adsorbent, and wherein the adsorbent is treated with hydrogen before contacting the untreated composition; The selective adsorbent is present in a weight ratio of at least 1:20 to the untreated composition of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) / 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a), and the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is reduced by more than 10% based on the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition during a one-week contact period.

7. The method according to claim 6: The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than 0.1% by weight.

8. The method according to claim 7: The concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the treated composition is less than 0.05% by weight.

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