Method for reducing 1, 1, 1, 2, 2-pentafluoropropane (HFC-245cb) in process for producing trans-1, 3, 3, 3-tetrafluoropropene (HFO-1234ze (E))

Abstract

A method for reducing 1, 1, 1, 2, 2-pentafluoropropane (HFC-245cb) in a trans-1, 3, 3, 3-tetrafluoropropene (HFO-1234ze (E)) manufacturing process includes catalyst conditioning, temperature reduction, and contact time reduction. In one embodiment, a process includes dehydrofluorinating 1, 1, 1, 3, 3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce a product mixture having HFO-1234ze (E) and HFC-245cb, and incorporating a conditioned catalyst, using a lower dehydrofluorinating temperature, or reducing the contact time of dehydrofluorinating to reduce formation of HFC-245cb.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 660,212, filed May 9, 2024, and U.S. Provisional Application No. 63 / 466,119, filed May 12, 2023, pursuant to 35 USC 119(e), both of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a process for manufacturing trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)), and more particularly to a method for reducing the generation of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the HFO-1234ze(E) manufacturing process. Background Technology

[0004] Chlorofluorocarbons (CFCs) such as trichlorofluoromethane and dichlorodifluoromethane have been used as refrigerants, foaming agents, and diluents for gas sterilization. In recent years, there has been widespread concern that some CFCs may be harmful to the Earth's ozone layer. Therefore, there is a global effort to use halogenated hydrocarbons containing fewer or no chlorine substituents. Consequently, the preparation of hydrofluorocarbons (or compounds containing only carbon, hydrogen, and fluorine) has been a subject of interest, aiming to provide ideal products for use as solvents, foaming agents, refrigerants, cleaning agents, aerosol propellants, heat transfer media, dielectrics, fire extinguishing compositions, and power circulation working fluids. In this regard, trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)) is a compound with the potential to be used as a refrigerant, foaming agent, aerosol propellant, solvent, etc., with zero ozone depletion potential (ODP) and low global warming potential (GWP), and also as a fluorinated monomer.

[0005] It has been determined that methods for producing HFO-1234ze(E) are sometimes uneconomical relative to their product yield due to impurities in the HFO-1234ze(E) product stream. Certain applications, such as medical propellants, require HFO-1234ze(E) of extremely high purity. It has been noted that, among other impurities, significant amounts of 1,1,1,2,2-pentafluoropropane (HFC-245cb) may be generated along with the desired product. Therefore, this disclosure provides an integrated process for reducing the generation of HFC-245cb in the HFO-1234ze(E) manufacturing process. Summary of the Invention

[0006] This disclosure is based on the finding that certain modifications to the HFO-1234ze(E) process can significantly reduce the generation of HFC-245cb. Advantageously, these modifications can be made without significantly altering the structure of the existing HFO-1234ze(E) process reactor and eliminate the need for expensive and time-consuming separation of the crude HFO-1234ze(E) product stream.

[0007] In one form of this disclosure, a method is provided for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), the method comprising: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product containing trans-1,3,3,3-tetrafluoropropene (HFO- The product mixture comprises 1234ze(E)), cis-1,3,3,3-tetrafluoropropylene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein, based on the total weight of the catalyst mixture, the catalyst mixture contains 10% to 90% by weight of a regulated catalyst having an operating time of 20 to 500 days in the HFO-1234ze(E) manufacturing process.

[0008] In another form of this disclosure, a method is provided for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, the method comprising: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the dehydrofluorination step is carried out at a temperature of 10°C to 310°C.

[0009] In another form of this disclosure, a method is provided for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, the method comprising: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the contact time in the dehydrofluorination step is from 1 second to 40 seconds. Attached Figure Description

[0010] The above and other features of this disclosure, as well as the ways in which they are implemented, will become more apparent and the disclosure itself will be better understood by referring to the following description of embodiments of this disclosure in conjunction with the accompanying drawings.

[0011] Figure 1 This is a process flow diagram of the manufacturing process of HFO-1234ze(E).

[0012] The examples presented herein illustrate embodiments of this disclosure, and such examples should not be construed as limiting the scope of this disclosure in any way. Detailed Implementation

[0013] I. Definition

[0014] By way of non-limiting example, some embodiments of this disclosure are given below.

[0015] As used herein, the term “HFO-1234ze(E)” refers to the trans isomer of 1,3,3,3-tetrafluoropropylene.

[0016] The term "HFO-1234ze(Z)" refers to the cis isomer of 1,3,3,3-tetrafluoropropylene.

[0017] The term "HFC-245cb" refers to 1,1,1,2,2-pentafluoropropane.

[0018] The term "HFC-245fa" refers to 1,1,1,3,3-pentafluoropropane.

[0019] As used herein, the term “fresh catalyst” refers to a catalyst with 0 days of operating time in the HFO-1234ze(E) manufacturing process, i.e., an “unused” catalyst.

[0020] As used herein, the term “tuned catalyst” refers to a catalyst having an operating time of at least one day (24 hours).

[0021] II. An integrated method for generating HFO-1234ze(E)

[0022] US7638660B2 describes in detail a method for generating HFO-1234ze(E), the entire contents of which are incorporated herein by reference.

[0023] The method may include the following steps:

[0024] (a) Dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF).

[0025] (b) Optionally, recover hydrogen fluoride from the product of step (a);

[0026] (c) Optionally isomerize at least a portion of cis-1,3,3,3-tetrafluoropropene to trans-1,3,3,3-tetrafluoropropene;

[0027] (d) Recover the reaction product mixture and recycle it back to the defluorination step; and

[0028] (e) Optionally, trans-1,3,3,3-tetrafluoropropylene is recovered from the product mixture by distillation.

[0029] refer to Figure 1 The diagram illustrates an exemplary flow chart for producing HFO-1234ze(E), in which HFC-245fa feed 110 is provided in a first step. The HFC-245fa feed is then preheated and reacted in reaction step 120. In reaction step 120, HFC-245fa is dehydrofluorinated via catalytic conversion, resulting in a product stream comprising cis-1,3,3,3-tetrafluoropropene, trans-1,3,3,3-tetrafluoropropene, and hydrogen fluoride. Optionally, hydrogen fluoride may be recovered from the product stream in an acid removal step 130. After acid removal, the reaction product may be purified in a product purification step 140. The purified HFO-1234ze may be stored in step 150. Optionally, a mixture of HFO-1234ze(Z) and HFC-245fa recovered as distillate may be recycled back to reaction step 120 via a recycling stream 160.

[0030] Generally, defluorination reactions are well known in the art. Preferably, the defluorination of HFC-245fa is carried out in the gas phase, and more preferably in a fixed-bed reactor in the gas phase. The defluorination reaction can be carried out in any suitable reaction vessel or reactor, but it should preferably be made of a material resistant to the corrosive effects of hydrogen fluoride (such as nickel and its alloys, including Hastelloy, ferrochrome, Incoloy, and Monel) or a vessel lined with a fluoropolymer. These can be a single pipe or multiple pipes filled with a defluorination catalyst, which can be one or more of the following: fluorinated metal oxides in bulk or supported form, metal halides in bulk or supported form, and carbon-supported transition metals, metal oxides, and halides.

[0031] Suitable catalysts include, but are not exclusively limited to, fluorinated chromium oxide (fluorinated Cr2O3), fluorinated aluminum oxide (fluorinated Al2O3), fluorinated mixed metal oxides (e.g., ZnO-Cr2O3), metal fluorides (e.g., CrF3, AlF3), and carbon-supported transition metals (zero oxidation state) such as Fe / C, Co / C, Ni / C, Pd / C.

[0032] For example, other suitable catalysts may include chromium oxides, chromium fluoride oxides, and chromium halides. Chromium oxides may include amorphous chromium oxide (Cr₂O₃), crystalline chromium oxide, and combinations thereof. Chromium fluoride oxides may include fresh amorphous chromium oxide (Cr₂O₃) pretreated with HF, fresh crystalline chromium oxide (Cr₂O₃) pretreated with HF, and amorphous chromium fluoride oxide (CrO₂). x F y Where x can be greater than 0 but less than 1.5, and y can be greater than 0 but less than 3), crystalline chromium fluoride (CrO) x F y (where x can be greater than 0 but less than 1.5, and y can be greater than 0 but less than 3) and a combination of the aforementioned substances. In one embodiment, the catalyst is amorphous chromium fluoride oxide (CrO). x F y Where x can be greater than 0 but less than 1.5, and y can be greater than 0 but less than 3. Chromium halides may include chromium trifluoride (CrF3), chromium trichloride (CrCl3), chromium triiodide (CrI3), and chromium tribromide (CrBr3), as well as combinations thereof. In one embodiment, the catalyst is chromium trifluoride (CrF3).

[0033] Other suitable catalysts include promoted chromium-based catalysts, which are based on chromium and contain an amount of at least one co-catalyst selected from Ni, Zn, Co, Mn, Mg, or mixtures thereof. The amount of co-catalyst can range from 0.1 wt% to 20 wt% based on the total weight of the catalyst, and more particularly, can be present in amounts as low as 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, or as high as 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, or in any range using any two of the foregoing values ​​as endpoints. A suitable promoted chromium catalyst is a zinc / chromium oxide catalyst, which is based on chromium oxide and contains an amount of zinc as a co-catalyst, for example, the JM 62-3M catalyst available from Johnson Matthey. Prior to use, the catalyst can be fluorinated using anhydrous HF under conditions that effectively convert a portion of the metal oxide into the corresponding metal fluoride.

[0034] The chromium-based catalysts described above can also be low-chromium (VI) catalysts, with the total chromium oxide (VI) content being about 5,000 ppm or less, about 2,000 ppm or less, about 1,000 ppm or less, about 500 ppm or less, about 250 ppm or less, or about 100 ppm or less, based on the total chromium oxides in the chromium oxide catalyst.

[0035] Besides chromium-based catalysts, other suitable catalysts include alumina, iron oxide, magnesium oxide, zinc oxide, nickel oxide, cobalt oxide, aluminum fluoride, or metal fluorides, such as iron fluoride, magnesium fluoride, zinc fluoride, nickel fluoride, cobalt fluoride, aluminum fluoride, iron fluoride, magnesium fluoride, nickel fluoride, cobalt fluoride, titanium fluoride, molybdenum fluoride, aluminum fluoride, and combinations thereof. Before use, the catalyst containing metal oxides is fluorinated using anhydrous HF under conditions that effectively convert a portion of the metal oxide into the corresponding metal fluoride.

[0036] HFC-245fa is introduced into the reactor in pure form, impure form, or with an optional inert gas diluent such as nitrogen or argon. In a preferred embodiment of the invention, HFC-245fa is pre-vaporized or preheated before entering the reactor. Alternatively, HFC-245fa is vaporized within the reactor. The available reaction temperature can range from about 100°C to about 600°C. A preferred temperature range is from about 150°C to about 450°C, and a more preferred temperature range is from about 200°C to about 350°C. The reaction can be carried out at atmospheric pressure, extra-atmospheric pressure, or under vacuum. The vacuum pressure can be from about 5 Torr to about 760 Torr. The contact time between HFC-245fa and the catalyst can range from about 0.5 seconds to about 120 seconds, however, longer or shorter times can also be used.

[0037] In a preferred embodiment, the process flow passes through the catalyst bed in a downward or upward direction. Periodic regeneration of the catalyst after prolonged use, while it remains in place in the reactor, can also be advantageous. Catalyst regeneration can be achieved by any method known in the art (e.g., by passing air or nitrogen-diluted air through the catalyst at a temperature of about 100°C to about 400°C, preferably about 200°C to about 375°C, for about 0.5 hours to about 3 days). Subsequently, for fluorinated metal oxide catalysts and metal fluoride catalysts, HF treatment is performed at a temperature of about 25°C to about 400°C, preferably about 200°C to about 350°C, or for carbon-supported transition metal catalysts, H2 treatment is performed at a temperature of about 100°C to about 400°C, preferably about 200°C to about 350°C.

[0038] In an alternative embodiment of the invention, the defluorination of HFC-245fa can also be achieved by reacting it with a strong caustic alkali solution, including but not limited to KOH, NaOH, Ca(OH)2, and CaO, at an elevated temperature. In this case, the caustic alkali concentration of the caustic alkali solution is from about 2% to about 100% by weight, more preferably from about 5% to about 90% by weight, and most preferably from about 10% to about 80% by weight. The reaction can be carried out at a temperature of about 20°C to about 100°C, more preferably from about 30°C to about 90°C, and most preferably from about 40°C to about 80°C. As mentioned above, the reaction can be carried out at atmospheric pressure, extra-atmospheric pressure, or vacuum. The vacuum pressure can be from about 5 Torr to about 760 Torr. Furthermore, a solvent can optionally be used to help dissolve the organic compound in the caustic alkali solution. This optional step can be carried out using solvents well known in the art for the purposes described above.

[0039] Hydrogen fluoride recovery is carried out by passing the composition obtained from the defluorination reaction through a sulfuric acid extractor to remove the hydrogen fluoride, followed by desorption of the extracted hydrogen fluoride from the sulfuric acid, and then distillation of the desorbed hydrogen fluoride. When the mixture is in a liquid or gaseous state, separation can be achieved by adding sulfuric acid to the mixture. The typical molar ratio of sulfuric acid to hydrogen fluoride is in the range of about 0.1:1 to about 100:1. It can be started with a liquid mixture of fluorocarbons and hydrogen fluoride, and then sulfuric acid is added to the mixture.

[0040] The amount of sulfuric acid required for separation depends on the amount of HF present in the system. The minimum practical amount of sulfuric acid can be determined based on the solubility of HF in 100% sulfuric acid as a function of temperature. For example, at 30°C, approximately 34g of HF will dissolve in 100g of 100% sulfuric acid. However, at 100°C, only approximately 10g of HF will dissolve in 100% sulfuric acid. Preferably, the sulfuric acid used in this invention has a purity of approximately 50% to 100%.

[0041] In a preferred embodiment, the weight ratio of sulfuric acid to hydrogen fluoride is in the range of about 0.1:1 to about 1000:1. More preferably, the weight ratio is in the range of about 1:1 to about 100:1, and most preferably about 2:1 to about 50:1. Preferably, the reaction can be carried out at a temperature of about 0°C to about 100°C, more preferably about 0°C to about 40°C, and most preferably about 20°C to about 40°C. Extraction is typically carried out at standard atmospheric pressure; however, those skilled in the art can use higher or lower pressure conditions. When sulfuric acid is added to the mixture of fluorocarbon and HF, two phases are rapidly formed.

[0042] A fluorocarbon-rich upper phase and an HF / sulfuric acid-rich lower phase are formed. The term "rich" means that the phase contains more than 50% of the specified component in the phase, and preferably more than 80% of the specified component in the phase. The extraction efficiency of the fluorocarbons can range from about 90% to about 99%.

[0043] Following phase separation, the fluorocarbon-rich upper phase is removed from the lower phase, which is rich in hydrogen fluoride and sulfuric acid. This can be accomplished by decantation, siphoning, distillation, or other techniques known in the art. Fluorocarbon extraction can optionally be repeated by adding more sulfuric acid to the removed lower phase. With a sulfuric acid to hydrogen fluoride weight ratio of about 2.25:1, an extraction efficiency of about 92% can be obtained in one step. Preferably, hydrogen fluoride and sulfuric acid are subsequently separated. HF can be recovered from sulfuric acid due to its low solubility in sulfuric acid at high temperatures. For example, at 140°C, only 4 g of HF will dissolve in 100% sulfuric acid. The HF / sulfuric acid solution can be heated up to 250°C to recover HF. HF and sulfuric acid can then be recycled. That is, HF can be recycled to the prior reaction for the formation of HFC-245fa, and sulfuric acid can be recycled for further extraction steps.

[0044] In another embodiment of the invention, the recovery of hydrogen fluoride from a mixture of fluorocarbons and hydrogen fluoride can be carried out in the gas phase via a continuous process of introducing a sulfuric acid stream into the fluorocarbon and hydrogen fluoride streams. This can be performed in a standard scrubbing tower by causing the sulfuric acid stream to flow countercurrently with the fluorocarbon and hydrogen fluoride streams. Sulfuric acid extraction is described, for example, in U.S. Patent No. 5,895,639, which is incorporated herein by reference.

[0045] Alternatively, HF can be recovered or removed by using a water or caustic alkali scrubber, or by contact with a metal salt. When using a water extractor, the technique is similar to that used with sulfuric acid. When using a caustic alkali, HF is removed from the system as a fluoride salt in an aqueous solution. When using a metal salt (e.g., potassium fluoride or sodium fluoride), it can be used alone or in combination with water. When using a metal salt, HF can be recovered. HF can also be recovered by adsorption in water followed by azeotropic distillation of the HF / water solution to recover anhydrous HF.

[0046] Trans-1,3,3,3-tetrafluoropropene can be recovered from a mixture of reaction products consisting of unreacted starting materials and byproducts, including cis-1,3,3,3-tetrafluoropropene and any byproducts and / or starting materials, by any means known in the art, such as extraction and preferably distillation. The mixture of trans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene, unreacted HFC-245fa, and any byproducts is passed through a distillation column. For example, distillation can preferably be carried out in a standard distillation column at atmospheric pressure, extra-atmospheric pressure, or vacuum. Preferably, the pressure is less than about 300 psig, more preferably less than about 150 psig, and most preferably less than 100 psig. The pressure of the distillation column inherently determines the distillation operating temperature. The boiling point of trans-1,3,3,3-tetrafluoropropylene is about -19°C; the boiling point of cis-1,3,3,3-tetrafluoropropylene is about 9°C; and the boiling point of HFC-245fa is about 15°C. Trans-1,3,3,3-tetrafluoropropylene can be recovered as a distillate by operating a distillation column at about -10°C to about 90°C, preferably about 0°C to about 80°C. Single or multiple distillation columns can be used. The distillate portion essentially contains all of the trans-1,3,3,3-tetrafluoropropylene. The bottom stream from the distillation column contains cis-1,3,3,3-tetrafluoropropylene HFC-245fa, as well as any other impurities (such as HFC-1233zdE / Z, CFC-113, and various dimers and trimers). The bottom stream can optionally be further distilled using another distillation column to recover a recyclable stream containing HFC-245fa, HFO-1234zeZ, and HCFO-1233zdE / Z for recycling, and to remove unwanted impurities (including CFC-113 and various dimers and trimers).

[0047] Then, at least a portion of cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)) is isomerized to trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)). A stream of cis-1,3,3,3-tetrafluoropropene or a mixture thereof with trans-1,3,3,3-tetrafluoropropene and / or 1,1,1,3,3-pentafluoropropane is fed into an isomerization reactor containing a suitable isomerization catalyst (e.g., in bulk or supported form of a fluorinated metal oxide, in bulk or supported form of a metal fluoride, carbon-supported transition metal, etc.) to convert most of HFO-1234ze(Z) to HFO-1234ze(E). The isomerization reaction can be carried out in any suitable reaction vessel or reactor, but it should preferably be constructed of corrosion-resistant materials such as nickel and its alloys, including Hastelloy, ferrochrome, Incoloy, and Monel, or a vessel lined with a fluoropolymer. These reaction vessels or reactors can be a single pipe or multiple pipes filled with an isomerization catalyst, which can be a fluorinated metal oxide, a metal fluoride, or a carbon-supported transition metal. Suitable catalysts non-exclusively include fluorinated chromium oxide, chromium fluoride, fluorinated ZnO-Cr2O3, fluorinated aluminum oxide, aluminum fluoride, and carbon-supported cobalt. Available reaction temperatures can range from about 25°C to about 450°C. Preferred temperatures are in the range from about 50°C to about 350°C, and more preferably from about 75°C to about 250°C. The reaction can be carried out at atmospheric pressure, extra-atmospheric pressure, or under vacuum. Vacuum pressure can be from about 5 Torr to about 760 Torr. The contact time between cis-1,3,3,3-tetrafluoropropylene and the catalyst can range from about 0.5 seconds to about 120 seconds, however, longer or shorter times can also be used. In a preferred embodiment, the HFO-1234ze(Z) isomerization reaction and the HFC-245fa defluorination reaction are carried out in the same reactor packed with a fluorinated chromium oxide catalyst or a fluorinated ZnO-Cr2O3 catalyst.

[0048] In the following alternative embodiments of the invention, the HFC-245fa defluorination reactor and the HFO-1234ze(Z) isomerization reactor can be combined or separate. HFO-1234ze(E) separation can occur after or before the HFO-1234ze(Z) isomerization reaction.

[0049] Alternative Option 1 :

[0050] (1) Combined reaction of HFC-245fa defluorination and HFO-1234ze(Z) isomerization in a reaction vessel.

[0051] (2) Optional HF recovery.

[0052] (3) Separation of HFO-1234ze(E). Optionally, the remaining mixture is recycled back to step 1.

[0053] (4) Optional distillation and recycling of the mixture to remove high-boiling-point components, such as HCFC-113 and HCFO-1233zd.

[0054] Alternative Option 2:

[0055] (1) The HFC-245fa is catalytically defluorinated to form a composition containing HFO-1234ze(Z).

[0056] (2) Optional HF recovery.

[0057] (3) Separation of HFO-1234ze(E), wherein the effluent stream from (2) is fed into a distillation column. The product HFO-1234ze(E) is separated as distillate from the remainder of the mixture (i.e., HFO-1234ze(Z), unreacted HFC-245fa, and other minor byproducts). The residual HF / HCl present in the distillate is removed, followed by an acid removal step. The bottom stream from the distillation in (3) is split into two streams and fed to steps (4) and (1), respectively. Optionally, after step (3), further distillation is performed using another distillation column. In this distillation column, the mixture of HFO-1234ze(Z) and HFC-245fa is recovered as distillate and then fed to step (4). The bottom stream from this second distillation column is optionally recycled back to step (1).

[0058] (4) Catalytic isomerization of HFO-1234ze(Z).

[0059] The mixture of HFO-1234ze(Z) / HFC-245fa from step (3) is fed into an isomerization reactor containing a suitable isomerization catalyst to convert most of the HFO-1234ze(Z) to HFO-1234ze(E). The effluent from the catalytic reactor in step (4) is fed into step (3) for HFO-1234ze(E) segregation.

[0060] Alternative Solution 3 :

[0061] (1) 245fa is catalytically defluorinated to trans / HFO-1234ze(Z).

[0062] (2) Optional HF recovery.

[0063] (3) Separation of HFO-1234ze(E)

[0064] (4) Catalytic isomerization of HFO-1234ze(Z), wherein a mixture from step (3) comprising HFO-1234ze(Z) and 245fa is fed into an isomerization reactor containing a suitable isomerization catalyst to convert most of HFO-1234ze(Z) into HFO-1234ze(E).

[0065] (5) Separation of HFO-1234ze(E), wherein the effluent from step (4) is fed into a distillation column. The product HFO-1234ze(E) is separated as distillate from the remainder of the mixture (i.e., HFO-1234ze(Z), unreacted 245fa, and other minor byproducts). The bottom stream from the distillation in (5) is recycled back to step (1).

[0066] During the manufacture of HFO-1234ze(E), undesirable impurities (such as HFC-245cb) may be generated. Methods for reducing the generation of HFC-245cb are discussed in Section III below.

[0067] III. Methods for reducing the generation of HFC-245cb

[0068] HFC-245cb is a hydrofluorocarbon produced as an impurity in the HFO-1234ze(E) manufacturing process. It is an isomer of the starting material HFC-245fa, as shown below.

[0069]

[0070] The formation of HFC-245cb is problematic because it forms a low-boiling-point azeotrope with the desired product HFO-1234ze(E).

[0071] Currently, there is a need for very high-purity HFO-1234ze(E) for medical propellants, such as those used in inhalers. Several methods can be used to meet the requirement of producing high-purity HFO-1234ze(E). Crude product streams containing HFO-1234ze(E) can be purified by distillation or other separation methods to remove HFC-245cb. While these separations are effective, they introduce complexity, cost, and increased time into the manufacturing process. Alternatively, the manufacturing process can be modified to prevent or mitigate the initial reaction that forms HFC-245cb.

[0072] This disclosure envisions three methods for reducing the generation of HFC-245cb in the HFO-1234ze(E) process: catalyst conditioning, temperature reduction, and contact time reduction. These methods are designed to preemptively prevent the formation of high levels of HFC-245cb in the reactor, making subsequent separation more efficient or unnecessary altogether.

[0073] A. Catalyst regulation

[0074] In the HFO-1234ze(E) process outlined in Part II, the catalyst may be replaced periodically due to activity loss (i.e., low conversion of 245fa or high reactor temperature required for sufficient 245fa conversion) or the need for internal reactor inspections.

[0075] It has been found that catalyst renewal produces spikes in the generation of HFC-245cb impurities. When the entire batch of fresh catalyst is introduced into the reactor, HFC-245cb production can reach levels as high as 1000 ppm. Unbound from theoretical constraints, the conversion of 245fa to 245cb is believed to occur via a series of steps: CF3CH2CHF2 (245fa) CF3CH=CHF+ HF, CF3CH=CHF CF3CCH + HF, CF3CCH + HF CF3CF=CH2, CF3CF=CH2 + HF CF3CF2CH3 (245cb). The formation of unwanted 245cb can be reduced by using a modified catalyst (i.e., a catalyst with lower activity).

[0076] The conditioned catalyst can be the same catalyst used in the HFO-1234ze(E) manufacturing process as described in Part II, but has been used for several days, preferably more than 50 days. During implementation, a mixture of fresh and conditioned catalysts can be added to the reactor to achieve the desired 245cb impurity content in the 1234zeE product. These catalysts include any known defluorination catalyst, which can be one or more of the following: fluorinated metal oxides in bulk or supported form, metal halides in bulk or supported form, and carbon-supported transition metals, metal oxides, and halides. Suitable catalysts non-exclusively include fluorinated chromium oxide (fluorinated Cr2O3), fluorinated aluminum oxide (fluorinated Al2O3), fluorinated mixed metal oxides (e.g., ZnO-Cr2O3), metal fluorides (e.g., CrF3, AlF3), and carbon-supported transition metals (zero oxidation state) such as Fe / C, Co / C, Ni / C, Pd / C.

[0077] Regulated catalysts suitable for reducing HFC-245cb generation are available with durations as low as 1 day, 5 days, 10 days, 12 days, 15 days, 20 days, 25 days, 28 days, 30 days, 35 days, 45 days, 50 days, 52 days, 55 days, 60 days, 65 days, 70 days, 75 days, 85 days, 90 days, 95 days, 96 days, 100 days, 110 days, 120 days, 130 days, 140 days, 150 days, 160 days, 170 days, 180 days, 190 days, 200 days, 210 days, 220 days, 225 days, 230 days, 240 days, 250 days, and 260 days. Operating times of 270 days, 280 days, 300 days, 310 days, 320 days, 330 days, 340 days, 350 days, 360 days, or up to 370 days, 380 days, 390 days, 400 days, 410 days, 420 days, 430 days, 440 days, 450 days, 454 days, 460 days, 470 days, 480 days, 490 days, 500 days, 510 days, 520 days, 530 days, 540 days, 550 days, 560 days, 570 days, 580 days, 590 days, 600 days, or any range covered by any two of the aforementioned values ​​as endpoints. For example, a catalyst may have an operating time of 20 to 500 days, 50 to 500 days, or 300 to 500 days.

[0078] Catalyst mixtures containing conditioned catalyst blended with fresh catalyst can also be used to reduce the formation of HFC-245cb. Based on the total weight of the catalyst mixture, the mixture may contain as low as 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or as high as 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or any amount of fresh catalyst within any range covered by any two of the aforementioned values ​​as endpoints. For example, the catalyst mixture may contain 10 wt% to 90 wt% fresh catalyst. Based on the total weight of the catalyst mixture, the catalyst mixture may also contain as low as 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or as high as 50 wt%, or 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or any range within any two of the aforementioned values ​​as endpoints, or amounts of regulated catalyst. For example, the catalyst mixture may contain 10 wt% to 90 wt% of regulated catalyst, or 50 wt% of regulated catalyst.

[0079] By employing the described catalyst conditioning method, the amount of HFC-245cb in the product mixture can be as low as 0 ppm, 0.001 ppm, 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, or as high as 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm, 95 ppm, 100 ppm, 105 ppm, 110 ppm, 115 ppm, 120 ppm, 125 ppm, 130 ppm, 140 ppm, 145 ppm, 150 ppm, or within any range covered by any two of the aforementioned values ​​as endpoints. For example, the amount of HFC-245cb in the 1234zeE product can be from 0.1 ppm to 100 ppm.

[0080] B. Reactor temperature

[0081] It was also found that changes in reactor temperature can affect the production of HFC-245cb. A slight decrease in reactor operating temperature can lead to a significant decrease in HFC-245cb content, while having the least impact on the yield of HFO-1234ze(E).

[0082] The defluorination reactor can be heated by any means known in the art. For example, electric heating elements, hot oil, or molten salt can be used.

[0083] To reduce the formation of HFC-245cb, the reactor temperature can be maintained as low as 10°C, 38°C, 93°C, 149°C, 204°C, 232°C, 260°C, 263°C, 266°C, 271°C, 274°C, 277°C, 279°C, 282°C, 285°C, 288°C, or as high as 291°C, 293°C, 296°C, 299°C, 302°C, 304°C, 307°C, 310°C, 313°C, 316°C, 318°C, 321°C, 324°C, 327°C, 329°C, 332°C, 335°C, 338°C, 341°C, 343°C, or within any range covered by any two of the aforementioned values ​​as endpoints. For example, the reactor temperature can be from 10°C to 310°C or from 288°C to 310°C.

[0084] By employing the described temperature control method, the amount of HFC-245cb in the product mixture can be as low as 0 ppm, 0.001 ppm, 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, or as high as 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm, 95 ppm, 100 ppm, 105 ppm, 110 ppm, 115 ppm, 120 ppm, 125 ppm, 130 ppm, 140 ppm, 145 ppm, 150 ppm, or within any range covered by any two of the aforementioned values ​​as endpoints. For example, the amount of HFC-245cb in the product mixture can be from 0.1 ppm to 100 ppm.

[0085] C. Contact time

[0086] It has also been found that altering the contact time between reactants in the HFO-1234ze(E) process can affect the generation of HFC-245cb. Reducing the contact time during the defluorination step leads to a decrease in the generation of HFC-245cb.

[0087] Contact time can be reduced in several ways, including operating at lower pressures (i.e., lower gas densities) for gas-phase reactions, operating with less catalyst in the reactor, operating at high feed rates of fresh HFC-245fa or recycled material, operating with low single-pass conversion of HFC-245fa to provide recycled material at high feed rates, adding diluents to the reactor feed, increasing the temperature (i.e., lower gas densities), or adding inert solids to the reactor to effectively reduce catalyst volume.

[0088] To reduce the generation of HFC-245cb, the contact time can be reduced to as low as 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, 13 seconds, 14 seconds, 15 seconds, 16 seconds, 17 seconds, 18 seconds, 19 seconds, 20 seconds, 21 seconds, 22 seconds, 23 seconds, 24 seconds, 25 seconds, 26 seconds, 27 seconds, 28 seconds, 29 seconds, 30 seconds, 31 seconds, 32 seconds, 33 seconds, 34 seconds, 35 seconds, 36 seconds, 37 seconds, 38 seconds, 39 seconds, 40 seconds, 41 seconds, 42 seconds, 43 seconds, 44 seconds, 45 seconds, 46 seconds, 47 seconds, 48 ​​seconds, 49 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, or any range covered by any two of the aforementioned values ​​as endpoints. For example, the contact time can be from 1 second to 40 seconds, or from 1 second to 20 seconds.

[0089] By employing the described contact time reduction method, the amount of HFC-245cb in the product mixture can be as low as 0 ppm, 0.001 ppm, 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, or as high as 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm, 95 ppm, 100 ppm, 105 ppm, 110 ppm, 115 ppm, 120 ppm, 125 ppm, 130 ppm, 140 ppm, 145 ppm, 150 ppm, or within any range covered by any two of the aforementioned values ​​as endpoints. For example, the amount of HFC-245cb in the product mixture can be from 0.1 ppm to 100 ppm.

[0090] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein, based on the total weight of the catalyst mixture, the catalyst mixture comprises 10% to 90% by weight of a catalyst having an operating time of 50 to 500 days in the HFO-1234ze(E) manufacturing process.

[0091] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the catalyst mixture comprises about 50% by weight of a catalyst having an operating time of 300 to 500 days in the HFO-1234ze(E) manufacturing process.

[0092] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the catalyst mixture comprises a dehydrofluorinating catalyst selected from the group consisting of fluorinated metal oxides, metal halides, and carbon-supported transition metals.

[0093] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropane (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropane (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropane (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), followed by a distillation step to recover trans-1,3,3,3-tetrafluoropropane (HFO-1234ze(E)) from the product mixture.

[0094] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

[0095] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the dehydrofluorination step is carried out at a temperature of 288°C to 310°C, and the temperature of the dehydrofluorination step is maintained using an electric heating element, hot oil, or molten salt.

[0096] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the contact time is from 1 second to 20 seconds and the dehydrofluorination step is carried out at a temperature of 288°C to 310°C.

[0097] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product containing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and cis- A product mixture of 1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the contact time is from 1 to 20 seconds and the defluorination step is carried out at a temperature of 288°C to 310°C, and the method further comprises: recovering trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) from the product mixture by distillation.

[0098] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) includes: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) using a catalyst mixture to produce a product containing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and cis-... A product mixture of -1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the contact time is from 1 second to 20 seconds and the defluorination step is carried out at a temperature of 288°C to 310°C, and the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

[0099] Example

[0100] Throughout this embodiment, the data points for HFC-245cb, reactor run time, temperature, and contact time were determined as follows:

[0101] 245cb data The product column distillate was measured by GC and directed to the product storage tank. HFO-1234ze(E) was purified in the product column, and HFO-1234ze(Z) and HFC-245fa were sent back to the reactor.

[0102] runtime data The number of days it takes for fresh HFC-245fa to be fed into this process.

[0103] Reactor temperature The approximate average reactor temperature is due to the gradient existing in the reactor caused by the endothermic reaction of HFC-245fa to HFO-1234ze(E) and HF.

[0104] Contact time The calculation is the catalyst volume divided by the volumetric flow rate of the process flow into the reactor. The catalyst volume is a known value based on the reactor design. The volumetric flow rate is based on the density calculated using the ideal gas law and the measured reactor process feed rate (i.e., fresh HFC-245fa + recycle).

[0105] Example 1: Catalyst Adjustment

[0106] Example 1 demonstrates the effect of catalyst conditioning on HFC-245cb production in the HFO-1234ze(E) process. It was found that when a full batch of fresh fluorinated Cr2O3 catalyst was introduced into the reactor, HFC-245cb impurities were generated at concentrations up to 1000 ppm. Typical catalyst conditioning profiles are listed in Table 1 below. For the data in Tables 1 and 2, the reactor was operated at temperatures ranging from 300°C to 320°C and pressures ranging from 5 psig to 15 psig. The total catalyst volume of the reactor system was 150 ft. 3 up to 175ft 3 The total feed rate of the reactor system is 2,000 lb / hr to 10,000 lb / hr.

[0107] Table 1

[0108] The effect of fresh catalyst degradation on HFC-245cb production

[0109]

[0110] To determine the effect of catalyst regulation on HFC-245cb production, a mixture of 50% used fluorinated Cr2O3 catalyst (with a start-up time exceeding 300 days) and 50% fresh fluorinated Cr2O3 catalyst was used in the HFO-1234ze(E) process reactor. The results are summarized in Table 2 below.

[0111] Table 2

[0112] The effect of 50 / 50 used and fresh catalysts on HFC-245cb

[0113]

[0114] The results in Tables 1 and 2 show that the use of the regulated catalyst reduced the amount of HFC-245cb produced from the outset and helped to keep the HFC-245cb content low during reactor operation and catalyst degradation.

[0115] Example 2: Reactor Temperature

[0116] Example 2 demonstrates the effect of reducing reactor temperature on the production of HFC-245cb. The results are summarized in Table 3. For the data in Table 3, the reactor was operated at pressures ranging from 5 psig to 15 psig. The total catalyst volume of the reactor system was 300 ft. 3 up to 350ft 3 The total feed rate of the reactor system is 4,000 lb / hr to 15,000 lb / hr.

[0117] Table 3

[0118] The effect of temperature on HFC-245cb

[0119]

[0120] The results in Table 3 indicate that decreasing the reactor temperature is associated with an increase in the production of HFC-245cb.

[0121] Example 3: Contact Time

[0122] Example 3 demonstrates the effect of reducing the contact time between the process material and the reactor catalyst on the production of HFC-245cb. The results are summarized in Table 4. For the data in Table 4, the reactor was operated at temperatures ranging from 300°C to 305°C and pressures ranging from 5 psig to 15 psig. The total catalyst volume of the reactor system was 150 ft. 3 up to 350ft 3 The total feed rate of the reactor system is 2,000 lb / hr to 15,000 lb / hr. Contact time is reduced by removing one of the two reactors from use and operating at a high reactor feed rate.

[0123] Table 4

[0124] The effect of contact time on HFC-245cb

[0125]

[0126] The results in Table 4 indicate that reducing catalyst contact time is associated with increased HFC-245cb production.

[0127] It should be understood that the above description is merely illustrative of this disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from this disclosure. Therefore, this disclosure is intended to cover all such alternatives, modifications, and variations that fall within the scope of the appended claims.

[0128] aspect

[0129] Aspect 1 is a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, the method comprising: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein, based on the total weight of the catalyst mixture, the catalyst mixture comprises 10% by weight to 90% by weight of a regulated catalyst having an operating time of 20 days to 500 days in the HFO-1234ze(E) manufacturing process.

[0130] Aspect 2 is the method according to aspect 1, wherein, based on the total weight of the catalyst mixture, the catalyst mixture contains 10% to 90% by weight of a regulated catalyst having an operating time of 50 to 500 days in the HFO-1234ze€ manufacturing process.

[0131] Aspect 3 is the method according to aspect 1 or aspect 2, wherein the catalyst mixture comprises 50% by weight of a conditioned catalyst having an operating time of 300 to 500 days in the HFO-1234ze(E) manufacturing process.

[0132] Aspect 4 is the method according to any one of Aspects 1 to 3, wherein the catalyst mixture comprises a defluorination catalyst selected from the group consisting of: fluorinated metal oxides, metal halides, and carbon-supported transition metals.

[0133] Aspect 5 is the method according to any one of Aspects 1 to 4, the method further comprising: recovering trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)) from the product mixture by distillation.

[0134] Aspect 6 is the method according to any one of Aspects 1 to 5, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

[0135] Aspect 7 is a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), the method comprising: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the dehydrofluorination step is carried out at a temperature of 10°C to 310°C.

[0136] Aspect 8 is the method according to aspect 7, wherein the defluorination step is carried out at a temperature of 288°C to 310°C.

[0137] Aspect 9 is the method according to aspect 7 or aspect 8, wherein the temperature of the defluorination step is maintained by an electric heating element, hot oil or molten salt.

[0138] Aspect 10 is a method according to any one of aspects 7 to 9, the method further comprising: feeding a reactant mixture containing 1,1,1,3,3-pentafluoropropane (HFC-245fa) into a defluorination reaction, wherein the reactant mixture is at a temperature of 288°C to 310°C.

[0139] Aspect 11 is the method according to aspect 10, wherein the temperature of the reactant mixture is maintained by an electric heating element, hot oil or molten salt.

[0140] Aspect 12 is the method according to any one of aspects 7 to 11, the method further comprising: recovering trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)) from the product mixture by distillation.

[0141] Aspect 13 is the method according to any one of Aspects 7 to 12, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

[0142] Aspect 14 is a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, the method comprising: dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce a product mixture comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb) and hydrogen fluoride (HF), wherein the contact time in the dehydrofluorination step is from 1 second to 40 seconds.

[0143] Aspect 15 is the method according to aspect 14, wherein the contact time is from 1 second to 20 seconds.

[0144] Aspect 16 is the method according to aspect 14 or aspect 15, wherein the defluorination step is carried out at a temperature of 288°C to 310°C.

[0145] Aspect 17 is the method according to any one of aspects 14 to 16, the method further comprising: recovering trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)) from the product mixture by distillation.

[0146] Aspect 18 is the method according to any one of aspects 15 to 17, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

[0147] Aspect 19 is a composition comprising trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)) produced by a process according to any one of aspects 1 to 18.

[0148] Aspect 20 is the composition according to aspect 19, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the composition is from 0.1 ppm to 100 ppm.

[0149] Aspect 21 is a composition comprising: trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)); cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)); 0.1 ppm to 100 ppm of 1,1,1,2,2-pentafluoropropane (HFC-245cb); and hydrogen fluoride (HF).

Claims

1. A method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)), the method comprising: Dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was performed using a catalyst mixture to produce a product mixture containing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and hydrogen fluoride (HF). Based on the total weight of the catalyst mixture, the catalyst mixture contains 10% to 90% by weight of a regulated catalyst having an operating time of 20 to 500 days in the HFO-1234ze(E) manufacturing process.

2. The method of claim 1, wherein, based on the total weight of the catalyst mixture, the catalyst mixture comprises 10% to 90% by weight of a conditioned catalyst having an operating time of 50 to 500 days in the HFO-1234ze(E) manufacturing process.

3. The method according to claim 1, wherein the catalyst mixture comprises 50% by weight of a conditioned catalyst having an operating time of 300 to 500 days in the HFO-1234ze(E) manufacturing process.

4. The method according to claim 1, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

5. A method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)), the method comprising: Dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was performed using a catalyst mixture to produce a product mixture containing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and hydrogen fluoride (HF). The defluorination step is carried out at a temperature of 10°C to 310°C.

6. The method according to claim 5, wherein the defluorination step is performed at a temperature of 288°C to 310°C.

7. The method according to claim 5, further comprising: A reactant mixture containing 1,1,1,3,3-pentafluoropropane (HFC-245fa) is fed into a defluorination reaction, wherein the reactant mixture is at a temperature of 288°C to 310°C.

8. The method according to claim 5, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

9. A method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a process for manufacturing trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)), the method comprising: Dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was performed using a catalyst mixture to produce a product mixture containing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and hydrogen fluoride (HF). The contact time in the defluorination step is 1 to 40 seconds.

10. The method of claim 9, wherein the contact time is from 1 second to 20 seconds.

11. The method of claim 9, wherein the defluorination step is performed at a temperature of 288°C to 310°C.

12. The method of claim 9, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is from 0.1 ppm to 100 ppm.

13. A composition comprising trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)) prepared by the process according to claim 1.

14. The composition according to claim 13, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the composition is from 0.1 ppm to 100 ppm.

15. A composition comprising: trans-1,3,3,3-tetrafluoropropylene (HFO-1234ze(E)); cis-1,3,3,3-tetrafluoropropylene (HFO-1234ze(Z)); 1,1,1,2,2-pentafluoropropane (HFC-245cb) from 0.1 ppm to 100 ppm; and Hydrogen fluoride (HF).

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