A method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245CB) in a 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)) production process, including catalyst adjustment, temperature reduction, and shortening of contact time. The method comprises defluoridating 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 reducing the formation of HFC-245cb by incorporating a modified catalyst, using a lower temperature for defluoridation, or shortening the contact time for defluoridation.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to U.S. Patent Application No. 18 / 660,212, filed on 9 May 2024, asserting the benefit under Section 119(e) of U.S. Provisional Patent Application No. 63 / 466,119, filed on 12 May 2023, both of which are incorporated herein by reference in their entirety.

[0002] (Field of invention) This disclosure relates to a process for producing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), and more specifically, to a method for reducing the generation of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in an HFO-1234ze(E) production process. [Background technology]

[0003] Chlorofluorocarbons (CFCs), such as trichlorofluoromethane and dichlorodifluoromethane, are used as refrigerants, blowing agents, and diluents for gas sterilization. In recent years, there has been widespread concern that certain chlorofluorocarbons may be harmful to the Earth's ozone layer. As a result, there is a global effort to use halocarbons that contain fewer or no chlorine substituents. Therefore, the production of hydrofluorocarbons, or compounds containing only carbon, hydrogen, and fluorine, is of increasing interest in providing environmentally desirable products for use as solvents, blowing agents, refrigerants, cleaning agents, aerosol propellants, heat transfer fluids, dielectrics, fire extinguishing compositions, and power cycle working fluids. In this regard, trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) is a compound that has the potential to be used as a zero-ozone depletion potential (ODP) and low global warming potential (GWP) refrigerant, blowing agent, aerosol propellant, solvent, etc., as well as a fluorinated monomer.

[0004] Methods for producing HFO-1234ze(E) have occasionally been found to be uneconomical in terms of product yield due to impurities present in the HFO-1234ze(E) product stream. Certain applications, such as medical propellants, require extremely high purity HFO-1234ze(E). Among other impurities, it has been noted that significant amounts of 1,1,1,2,2-pentafluoropropane (HFC-245cb) can 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) production process. [Overview of the project]

[0005] 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 may be made without significant structural damage to existing HFO-1234ze(E) process reactors, and may eliminate the need to subject the crude HFO-1234ze(E) product stream to costly and time-consuming separation.

[0006] In one embodiment, the present disclosure is a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process, wherein 1,1,1,3,3-pentafluoropropane (HFC-245fa) is dehydrofluorinated with a catalyst mixture to produce 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 (hydrogen The present invention provides a method comprising producing a product mixture containing a fluoride (HF), wherein the catalyst mixture contains 10% to 90% by weight of a modified catalyst, based on the total weight of the catalyst mixture, which has an operating time of 20 to 500 days in the HFO-1234ze(E) production process.

[0007] In another form, the present disclosure provides a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process, 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.

[0008] In another form, the present disclosure provides a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process, comprising dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the contact time in the dehydrofluorination step is 1 second to 40 seconds. [Brief explanation of the drawing]

[0009] By considering the attached drawings and referring to the following description of embodiments of the present disclosure, the above and other characteristics of the present disclosure, as well as the ways in which they are achieved, will become clearer, and the present disclosure itself will be better understood. [Figure 1] This is a process flow diagram of the HFO-1234ze(E) manufacturing process.

[0010] The illustrations provided herein illustrate embodiments of the disclosure and should not be construed as limiting the scope of the disclosure in any way. [Modes for carrying out the invention]

[0011] I. Definition As a non-restrictive example, an example of a particular embodiment of this disclosure is given below.

[0012] As used herein, the term "HFO-1234ze(E)" refers to the trans isomer of 1,3,3,3-tetrafluoropropene.

[0013] The term "HFO-1234ze(Z)" refers to the cis isomer of 1,3,3,3-tetrafluoropropene.

[0014] The term "HFC-245cb" refers to 1,1,1,2,2-pentafluoropropane.

[0015] The term "HFC-245fa" refers to 1,1,1,3,3-pentafluoropropane.

[0016] As used herein, the term “fresh catalyst” refers to a catalyst that has zero operating hours in the HFO-1234ze(E) manufacturing process, i.e., an “unused” catalyst.

[0017] As used herein, the term “modified catalyst” refers to a catalyst having at least one day (24 hours) of operating time.

[0018] II. Integrated process for the generation of HFO-1234ze(E) The process for producing HFO-1234ze(E) is described in detail in U.S. Patent Application Publication No. 7638660(B2), which is incorporated in its entirety by reference.

[0019] This process can include the following steps. (a) 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); (b) Optionally, recovering hydrogen fluoride from the result of step (a); (c) Optionally, isomerizing at least a portion of cis - 1,3,3,3 - tetrafluoropropene to trans - 1,3,3,3 - tetrafluoropropene; (d) Recovering the reaction product mixture and recycling it back to the dehydrofluorination step; and (e) Optionally, recovering trans - 1,3,3,3 - tetrafluoropropene from the product mixture by distillation.

[0020] Referring to FIG. 1, which shows an exemplary flow diagram for the production of HFO - 1234ze(E), in the first step, an HFC - 245fa feed 110 is provided. The HFC - 245fa feed is then pre - heated and reacted in a reaction step 120. In the reaction step 120, HFC - 245fa is dehydrofluorinated by catalytic conversion of HFC - 245fa to produce 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 can be purified in a product purification step 140. The purified HFO - 1234ze can be stored in step 150. Optionally, a mixture of HFO - 1234ze(Z) and HFC - 245fa recovered as a distillate may be recycled to the reaction step 120 via a recycle stream 160.

[0021] Generally, the dehydrofluorination reaction is well-known in the art. Preferably, the dehydrofluorination of HFC-245fa is carried out in the gas phase, more preferably in a fixed-bed reactor in the gas phase. The dehydrofluorination reaction can be carried out in any suitable reaction vessel or reactor, but preferably should be constructed from a material resistant to the corrosive action of hydrogen fluoride, such as nickel and its alloys (including Hastelloy, Inconel, Incoloy, and Monel), or a container lined with a fluoropolymer. These may be a single pipe or a plurality of tubes filled with a dehydrofluorination catalyst which may be one or more of a bulk or supported fluorinated metal oxide, a bulk or supported metal halide, and a carbon-supported transition metal, metal oxide and halide.

[0022] Suitable catalysts include, but are not limited to, fluorinated chromia (fluorinated Cr2O3), fluorinated alumina (fluorinated Al2O3), fluorine-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.

[0023] For example, suitable catalysts may include chromium oxide, chromium oxyfluoride, and chromium halide. Chromium oxide may include amorphous chromium oxide (Cr2O3), crystalline chromium oxide, and combinations thereof. Chromium oxyfluoride may include freshly amorphous chromium oxide (Cr2O3) pretreated with HF, freshly crystalline chromium oxide (Cr2O3) pretreated with HF, amorphous chromium oxyfluoride (CrO x F y (where x may be greater than 0 but less than 1.5, and y may be greater than 0 but less than 3)), crystalline chromium oxyfluoride (CrO x F y (where x may be greater than 0 but less than 1.5, and y may be greater than 0 but less than 3)), and combinations thereof. In one embodiment, the catalyst is amorphous chromium oxyfluoride (CrOx F y (In the formula, x may be greater than 0 but less than 1.5, and y may be greater than 0 but less than 3.)) Examples of chromium halides 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).

[0024] Other suitable catalysts include chromium-based accelerating catalysts, which are chromium-based and contain a certain amount of at least one co-catalyst selected from Ni, Zn, Co, Mn, Mg, or mixtures thereof. The amount of co-catalyst may be 0.1% to 20% by weight based on the total weight of the catalyst, more specifically, it may be present in amounts as small as 0.1%, 0.5%, 1.0% or 1.5% by weight based on the total weight of the catalyst, or in amounts as large as 2.0%, 3.0% or 4.0% or 5.0% or 6.0% by weight, or in any range using any two of the aforementioned values ​​as endpoints. One suitable chromium-accelerating catalyst is a zinc / chromia catalyst based on chromia and containing a certain amount of zinc as a co-catalyst, such as the JM 62-3M catalyst available from Johnson Matthey. Before use, the catalyst may be fluorinated using anhydrous HF under conditions effective for converting a portion of the metal oxide to the corresponding metal fluoride.

[0025] The above chromium-based catalyst may also be a low-chromium(VI) catalyst having a total chromium(VI) content of 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 oxide in the chromium oxide catalyst.

[0026] In addition to 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, fluorinated alumina, fluorinated iron oxide, fluorinated magnesium oxide, fluorinated nickel oxide, fluorinated cobalt oxide, titanium fluoride, molybdenum fluoride, aluminum oxyfluoride, and combinations thereof. Before use, the catalyst containing the metal oxide is fluorinated using anhydrous HF under conditions effective in converting a portion of the metal oxide to the corresponding metal fluoride.

[0027] HFC-245fa is introduced into the reactor in either its pure form, its impure form, or with an optional inert gas diluent such as nitrogen or argon. In a preferred embodiment of the present invention, HFC-245fa is pre-vaporized or preheated before entering the reactor. Alternatively, HFC-245fa is vaporized within the reactor. A useful reaction temperature may be in the range of about 100°C to about 600°C. A preferred temperature may be in the range of about 150°C to about 450°C, and a more preferred temperature may be in the range of about 200°C to about 350°C. The reaction may be carried out under atmospheric pressure, overpressure, or vacuum. The vacuum pressure can be about 5 Torr to about 760 Torr. The contact time between HFC-245fa and the catalyst may be in the range of about 0.5 seconds to about 120 seconds, but longer or shorter times may be used.

[0028] In preferred embodiments, the process flow is either downward or upward through the catalyst bed. After prolonged use with the catalyst remaining in the reactor, it may also be beneficial to periodically regenerate the catalyst. Catalyst regeneration can be achieved, for example, by passing air, or air diluted with nitrogen, over the catalyst at a temperature of about 100°C to about 400°C, preferably about 200°C to about 375°C, by any means known in the art, for a period of about 0.5 hours to about 3 days. This is followed by either an HF treatment at a temperature of about 25°C to about 400°C, preferably about 200°C to about 350°C, for fluorinated metal oxide catalysts and metal fluoride catalysts, or an H2 treatment at a temperature of about 100°C to about 400°C, preferably about 200°C to about 350°C, for carbon-supported transition metal catalysts.

[0029] In alternative embodiments of the present invention, the dehydrofluoridation of HFC-245fa can also be achieved by reacting it with a strong caustic solution containing, but not limited to, KOH, NaOH, Ca(OH)2, and CaO at a high temperature. In this case, the caustic strength of the caustic solution is about 2% to about 100% by weight, more preferably about 5% to about 90% by weight, and most preferably about 10% to about 80% by weight. The reaction may be carried out at a temperature of about 20°C to about 100°C, more preferably about 30°C to about 90°C, and most preferably about 40°C to about 80°C. As described above, the reaction may be carried out under atmospheric pressure, overpressure, or vacuum. The vacuum pressure can be about 5 Torr to about 760 Torr. In addition, a solvent may be optionally used to help dissolve the organic compound in the caustic solution. This optional step may be carried out using a solvent that is well known in the art for this purpose.

[0030] The recovery of hydrogen fluoride is carried out by passing the composition obtained from the dehydrofluoridation reaction through a sulfuric acid extractor to remove the hydrogen fluoride, then desorbing the extracted hydrogen fluoride from the sulfuric acid, and subsequently distilling the desorbed hydrogen fluoride. Separation may also be carried out by adding sulfuric acid to the mixture while the mixture is in either a liquid or gaseous state. The typical weight ratio of sulfuric acid to hydrogen fluoride is in the range of about 0.1:1 to about 100:1. Alternatively, one may start with a liquid mixture of fluorocarbon and hydrogen fluoride, and then add sulfuric acid to the mixture.

[0031] 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 from 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%.

[0032] In preferred embodiments, 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 more preferably in the range of about 2:1 to about 50:1. Preferably, the reaction is 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 usually carried out at standard atmospheric pressure, however, higher or lower pressure conditions may be used by those skilled in the art. When sulfuric acid is added to the mixture of fluorocarbon and HF, two phases are rapidly formed.

[0033] An upper phase rich in fluorocarbons and a lower phase rich in HF / sulfuric acid are formed. The term "rich in" means that the phase contains more than 50% of the indicated component, preferably more than 80% of the indicated component. The extraction efficiency of fluorocarbons can be in the range of about 90% to about 99%.

[0034] After phase separation, the fluorocarbon-rich upper phase is removed from the hydrogen fluoride and sulfuric acid-rich lower phase. This can be done by decanting, siphoning, distillation, or other techniques well known in the art. Optionally, fluorocarbon extraction may be repeated by adding more sulfuric acid to the removed lower phase. An extraction efficiency of approximately 92% can be obtained in one step when the weight ratio of sulfuric acid to hydrogen fluoride is approximately 2.25:1. Preferably, the hydrogen fluoride and sulfuric acid are then separated. HF can be recovered from sulfuric acid by taking advantage of the low solubility of HF in sulfuric acid at high temperatures. For example, at 140°C, only 4g of HF will dissolve 100% in sulfuric acid. To recover HF, the HF / sulfuric acid solution can be heated to 250°C. The HF and sulfuric acid can then be recycled. That is, the HF may be recycled to a preceding reaction for the formation of HFC-245fa, and the sulfuric acid may be recycled for use in further extraction steps.

[0035] In another embodiment of the present invention, the recovery of hydrogen fluoride from a mixture of fluorocarbon and hydrogen fluoride may be carried out in the gas phase by a continuous process of introducing a flow of sulfuric acid into the flow of fluorocarbon and hydrogen fluoride. This may be carried out in a standard scrubbing tower by flowing the sulfuric acid flow countercurrently to the flow of fluorocarbon and hydrogen fluoride. Sulfuric acid extraction is described, for example, in U.S. Patent No. 5,895,639, which is incorporated herein by reference.

[0036] Alternatively, HF can be recovered or removed by using water or a caustic scrubber, or by contact with a metal salt. When using a water extractor, the technique is similar to that of sulfuric acid. When using caustic acid, 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 as is or 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 / aqueous solution, thereby recovering anhydrous HF.

[0037] Trans-1,3,3,3-tetrafluoropropene can be recovered from the unreacted starting materials and by-products including cis-1,3,3,3-tetrafluoropropene, as well as a reaction product mixture consisting of any by-products 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 by-products is passed through a distillation column. For example, distillation may be carried out in a standard distillation column at atmospheric pressure, ultra-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 in the distillation column essentially determines the distillation operating temperature. Trans-1,3,3,3-tetrafluoropropene has a boiling point of about -19°C, cis-1,3,3,3-tetrafluoropropene has a boiling point of about 9°C, and HFC-245fa has a boiling point of about 15°C. Trans-1,3,3,3-tetrafluoropropene 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. One or more distillation columns may be used. The distillate portion contains substantially all of the trans-1,3,3,3-tetrafluoropropene. The bottom stream of the distillation column contains cis-1,3,3,3-tetrafluoropropene, HFC-245fa, and any other impurities such as HFC-1233zdE / Z, CFC-113, and various dimers and trimers. The bottom flow can optionally be further distilled using another distillation column to recover a recyclable flow containing HFC-245fa, HFO-1234zeZ, and HCFO-1233zdE / Z for recirculation, and remove undesirable impurities including CFC-113 and various dimers and trimers.

[0038] Next, 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)). The flow 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 supplied to an isomerization reactor containing a suitable isomerization catalyst (e.g., bulk or supported fluorinated metal oxide, bulk or supported metal fluoride, carbon-supported transition metal, etc.) for converting the majority of HFO-1234ze(Z) to HFO-1234ze(E). The isomerization reaction may be carried out in any suitable reaction vessel or reactor, but preferably it should be constructed from a vessel lined with corrosion-resistant material, such as nickel and its alloys including Hastelloy, Inconel, Incoloy, and Monel, or a fluoropolymer. These may be a single pipe or multiple tubes filled with an isomerization catalyst, which may be a fluorinated metal oxide, a metal fluoride, or a carbon-supported transition metal. Preferred catalysts are exclusively fluorinated chromia, chromium fluoride, fluorinated ZnO-Cr2O3, fluorinated alumina, aluminum fluoride, and carbon-supported cobalt. Useful reaction temperatures may range from about 25°C to about 450°C. Preferred temperatures may range from about 50°C to about 350°C, and more preferred temperatures may range from about 75°C to about 250°C. The reaction may be carried out under atmospheric pressure, overpressure, or vacuum. The vacuum pressure may range from about 5 Torr to about 760 Torr. The contact time between cis-1,3,3,3-tetrafluoropropene and the catalyst may range from approximately 0.5 seconds to approximately 120 seconds, however, longer or shorter times can be used. In a preferred scenario, the HFO-1234ze(Z) isomerization reaction and the HFC-245fa defluoride hydrogenation reaction are carried out in the same reactor loaded with a fluorinated chromia catalyst or a fluorinated ZnO-Cr2O3 catalyst.

[0039] In the following alternative embodiments of the present invention, the HFC-245fa defluoride-hydrogenation reactor and the HFO-1234ze(Z) isomerization reactor may be combined or independent. The isolation of HFO-1234ze(E) may occur after or before the isomerization reaction of HFO-1234ze(Z).

[0040] Alternative 1: (1) A combined reaction of dehydrofluorination of HFC-245fa and isomerization of HFO-1234ze(Z) in a single reaction vessel. (2) Optional HF recovery. (3) Isolation of HFO-1234ze(E). Optionally, the remaining mixture is returned to step 1 and recycled. (4) Selective distillation of the recirculated mixture to remove high-boiling components such as HCFC-113 and HCFO-1233zd.

[0041] Alternative 2: (1) Catalytic dehydrofluorination of HFC-245fa into a composition containing HFO-1234ze(Z). (2) Optional HF recovery. (3) Isolation of HFO-1234ze(E) supplied to the distillation column from the outlet flow of (2). The product HFO-1234ze(E) is isolated as a distillate from the remainder of the mixture, namely HFO-1234ze(Z), unreacted HFC-245fa and other small amounts of by-products. The residual HF / HCl present in the distillate is removed, followed by an acid removal step. The bottom flow from the distillation of (3) is split into two flows, supplied to steps (4) and (1), respectively. Optionally, after step (3), further distillation is carried out using another distillation column. In this distillation column, the mixture of HFO-1234ze(Z) and HFC-245fa is recovered as a distillate, which is then supplied to step (4). The bottom flow from this second distillation column is optionally returned to step (1) and recycled. (4) Catalytic isomerization of HFO-1234ze(Z).

[0042] The HFO-1234ze(Z) / HFC-245fa mixture from step (3) is fed into an isomerization reactor containing an isomerization catalyst suitable for converting the majority of HFO-1234ze(Z) to HFO-1234ze(E). The effluent from the catalytic reactor in step (4) is fed into step (3) for the isolation of HFO-1234ze(E).

[0043] Alternative 3: (1) Catalytic dehydrofluorination of 245fa to transformer / HFO-1234ze(Z). (2) Optional HF recovery. (3) Isolation of HFO-1234ze(E) (4) Catalytic isomerization of HFO-1234ze(Z), wherein a mixture containing HFO-1234ze(Z) and 245fa from step (3) is supplied to an isomerization reactor containing a suitable isomerization catalyst for converting the majority of HFO-1234ze(Z) to HFO-1234ze(E). (5) The effluent from step (4) is fed into the distillation column for isolation of HFO-1234ze(E). The product HFO-1234ze(E) is isolated as a distillate from the remainder of the mixture, namely HFO-1234ze(Z), unreacted 245fa and other small amounts of by-products. The bottom flow from the distillation in (5) is returned to step (1) and recycled.

[0044] During the production of HFO-1234ze(E), undesirable impurities such as HFC-245cb may be generated. Section III below discusses methods for reducing the generation of HFC-245cb.

[0045] III. Methods to reduce the generation of HFC-245cb 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.

[0046] [ka]

[0047] The formation of HFC-245cb is problematic because it forms a light-boiling azeotrope with the desired product, HFO-1234ze(E).

[0048] Currently, there is a need for very high-purity HFO-1234ze(E) for medical propellants such as those used in inhalers. The demand for producing high-purity HFO-1234ze(E) can be met by several methods. The crude product stream containing HFO-1234ze(E) can be purified via distillation or other separation methods to remove HFC-245cb. While these separations are effective, they introduce complexity, cost, and additional time into the manufacturing process. Alternatively, the manufacturing process may be modified to prevent or mitigate the reaction that initially forms HFC-245cb.

[0049] This disclosure seeks to reduce the generation of HFC-245cb in the HFO-1234ze(E) process by modifying the catalyst, lowering the temperature, and shortening the contact time. These methods are designed to prevent the generation of high levels of HFC-245cb in the reactor so that subsequent separation is either more efficient or not required at all.

[0050] A. Catalyst adjustment In the HFO-1234ze(E) process outlined in Section II, the catalyst may be replaced periodically due to either loss of activity (i.e., low conversion to 245fa, or the high reactor temperature required for proper 245fa conversion) or the need to perform internal inspections of the reactor.

[0051] Catalyst renewal has been found to cause a spike in the formation of HFC-245cb impurities. HFC-245cb formation can reach as high as 1000 ppm when the entire batch of fresh catalyst is introduced into the reactor. While not theoretically bound, the conversion of 245fa to 245cb is thought to occur through several steps: CF3CH2CHF2(245fa) → CF3CH=CHF+HF, CF3CH=CHF → CF3CCH+HF, CF3CCH+HF → CF3CF=CH2, CF3CF=CH2+HF → CF3CF2CH3(245cb). Undesirable 245cb formation can be reduced by using a modified catalyst (i.e., a catalyst with lower activity).

[0052] The prepared catalyst may be the same catalyst used in the HFO-1234ze(E) production process as described in Section II, but which has already been used for several days, preferably more than 50 days. In practice, a mixture of fresh and prepared catalysts can be added to the reactor to achieve the desired 245cb impurity level in the 1234zeE product. These catalysts include any known dehydrofluoridation catalysts, which may be one or more of the following: bulk or supported fluorinated metal oxides, bulk or supported metal halides, and carbon-supported transition metals, metal oxides, and halides. Suitable catalysts include, non-exclusively, fluorinated chromia (fluorinated Cr2O3), fluorinated alumina (fluorinated Al2O3), fluorinated 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, and Pd / C.

[0053] A specially formulated catalyst suitable for reducing HFC-245cb generation can be used in as little 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, 260 days, 270 days, 2 The operating time may be 80, 300, 310, 320, 330, 340, 350, 360 days, or up to 370, 380, 390, 400, 410, 420, 430, 440, 450, 454, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600 days, or any range encompassed by any two of the aforementioned values ​​as endpoints. For example, a catalyst may have an operating time of 20-500 days, 50-500 days, or 300-500 days.

[0054] Catalyst mixtures containing a prepared catalyst blended with fresh catalyst may also be useful in reducing the generation of HFC-245cb. The mixture may contain fresh catalyst in any range encompassed by any two of the aforementioned endpoints, based on the total weight of the catalyst mixture, ranging from a minimum of 5% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, or a maximum of 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight, or any range encompassed by any two of the aforementioned values ​​as endpoints. For example, the catalyst mixture may contain 10% to 90% by weight of fresh catalyst. The catalyst mixture may also contain, based on the total weight of the catalyst mixture, a modified catalyst in any range encompassed by any two of the aforementioned values ​​as endpoints, with a minimum of 5% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, or a maximum of 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight. For example, the catalyst mixture may contain 10% by weight to 90% by weight of modified catalyst, or 50% by weight of modified catalyst.

[0055] By using the catalyst preparation method described, the amount of HFC-245cb in the product mixture may be at least 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 at most 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 any range encompassed by any two of the aforementioned values ​​as endpoints. For example, the amount of HFC-245cb in the 1234zeE product can range from 0.1 ppm to 100 ppm.

[0056] B. Reactor temperature It has also been found that changes in reactor temperature can affect the production of HFC-245cb. Slightly lowering the reactor operating temperature can result in a significant reduction in HFC-245cb levels, while maintaining a minimally impactful HFO-1234ze(E) yield.

[0057] The defluoride-hydrogenation reactor can be heated by any means known in the art. For example, an electric heating element, hot oil, or molten salt may be used.

[0058] To reduce the formation of HFC-245cb, the reactor temperature may be maintained within a range encompassing any two of the aforementioned values ​​as endpoints, or a minimum of 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 a maximum of 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. For example, the reactor temperature may be between 10°C and 310°C or between 288°C and 310°C.

[0059] By using the temperature control method described, the amount of HFC-245cb in the product mixture may be at least 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 at most 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 any range encompassed by any two of the aforementioned values ​​as endpoints. For example, the amount of HFC-245cb in the product mixture may be between 0.1 ppm and 100 ppm.

[0060] C. Contact time It has also been found that changes in the contact time between reactants in the HFO-1234ze(E) process may affect the formation of HFC-245cb. Reducing the contact time during the defluoridation process may lead to a reduction in the formation of HFC-245cb.

[0061] Contact time can be reduced by various means, including operating at lower pressures for gas-phase reactions (i.e., lower gas density), operating with less catalyst in the reactor, operating at high feed rates of either fresh HFC-245fa or recirculated material, operating with low single-pass conversion of HFC-245fa to provide a high feed rate of recirculated material, adding diluents to the reactor feed material, increasing the temperature (i.e., lower gas density), or adding inert solids to the reactor to effectively reduce catalyst volume.

[0062] To reduce the generation of HFC-245cb, the contact time can be reduced to a minimum of 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 encompassed by any two of the aforementioned values ​​as endpoints. For example, the contact time may be between 1 and 40 seconds, or between 1 and 20 seconds.

[0063] By using the contact time reduction method described, the amount of HFC-245cb in the product mixture may be at least 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 at most 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 any range encompassed by any two of the aforementioned values ​​as endpoints. For example, the amount of HFC-245cb in the product mixture may be between 0.1 ppm and 100 ppm.

[0064] 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)) production process comprises dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the catalyst mixture contains 10% to 90% by weight of the catalyst, based on the total weight of the catalyst mixture, having an operating time of 50 to 500 days in the HFO-1234ze(E) production process.

[0065] 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)) production process comprises dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the catalyst mixture contains about 50% by weight of a catalyst having an operating time of 300 to 500 days in the HFO-1234ze(E) production process.

[0066] 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)) production process comprises dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the catalyst mixture comprises a dehydrofluorination catalyst selected from the group consisting of fluorinated metal oxides, metal halides, and carbon-supported transition metals.

[0067] 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)) production process includes dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), followed by a distillation step to recover trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) from the product mixture.

[0068] 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)) production process includes dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is 0.1 ppm to 100 ppm.

[0069] 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)) production process includes dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), 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 by an electric heating element, hot oil, or molten salt.

[0070] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process includes dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the contact time is 1 to 20 seconds, and the dehydrofluorination step is carried out at a temperature of 288°C to 310°C.

[0071] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process involves dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and cis-1,3,3,3-tetrafluoropropane (HFC-1234ze(E)). The process involves generating a product mixture containing ruolopropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and hydrogen fluoride (HF), wherein the contact time is 1 to 20 seconds, and the dehydrofluorination step is carried out at a temperature of 288°C to 310°C, and further comprising recovering trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) from the product mixture by distillation.

[0072] In some embodiments, a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process involves dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with a catalyst mixture to produce trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and cis-1,3 The process involves producing a product mixture containing ,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and hydrogen fluoride (HF), with a contact time of 1 to 20 seconds, and the dehydrofluorination step being carried out at a temperature of 288°C to 310°C, with the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture being 0.1 ppm to 100 ppm. [Examples]

[0073] Through the examples, data points related to HFC-245cb, reactor operating time, temperature, and contact time were determined as follows. 245cb data: Measured by GC in the distillate of the product column sent to the product storage tank. The product column purifies HFO-1234ze(E) and sends HFO-1234ze(Z) and HFC-245fa back to the reactor.

[0074] Operating time data: The number of days that fresh HFC-245fa is supplied to the process.

[0075] Reactor temperature: Due to the endothermic reaction of HFC-245fa to HFO-1234ze(E) and HF, there is a gradient across the reactor, so this is an approximate average reactor temperature.

[0076] Contact time: Calculated by dividing the catalyst volume by the volumetric flow rate of the process flow to the reactor. The catalyst volume is a known number based on the reactor design. The volumetric flow rate is based on the density calculated using the ideal gas law and the measured process feed rate to the reactor (i.e., fresh HFC-245fa + recirculation).

[0077] Example 1: Preparation of catalyst Example 1 demonstrates the effect of catalyst adjustment on HFC-245cb generation in the HFO-1234ze(E) process. When the entire batch of fresh fluorinated Cr2O3 catalyst was introduced into the reactor, HFC-245cb impurities were found to be generated at levels up to 1000 ppm. Typical catalyst adjustment curves are shown in Table 1 below. For the data in Tables 1 and 2, the reactor was operated at a temperature of 300–320°C and a pressure of 5–15 psig. The total catalyst volume in the reactor system was 150–175 ft. 3 The total supply rate to the reactor system was 2,000 to 10,000 lb / hour.

[0078] [Table 1]

[0079] To confirm the effect of catalyst conditioning on HFC-245cb production, a mixture of 50% old fluorinated Cr2O3 catalyst (having a production time of over 300 days) and 50% fresh fluorinated Cr2O3 catalyst was used in an HFO-1234ze(E) process reactor. The results are summarized in Table 2 below.

[0080] [Table 2]

[0081] The results in Tables 1 and 2 show that by using the conditioned catalyst, the production level of HFC-245cb is initially reduced and helps to keep the HFC-245cb level low as the reactor operates and the catalyst degrades.

[0082] Example 2: Reactor Temperature Example 2 demonstrates the effect of a decrease in reactor temperature on HFC-245cb production. The results are summarized in Figure 3. For the data in Table 3, the reactor was operating at a pressure of 5 - 15 psig. The total catalyst volume of the reactor system was 300 - 350 ft 3 and the total feed rate to the reactor system was 4,000 - 15,000 lb / hr.

[0083] [Table 3]

[0084] The results in Table 3 show that a decrease in reactor temperature correlates with an improvement in HFC-245cb production.

[0085] Example 3: Contact Time Example 3 demonstrates the effect of shortening the contact time of the process materials with the reactor catalyst on HFC-245cb production. The results are summarized in Figure 4. For the data in Table 4, the reactor was operating at a temperature of 300 - 305 °C and a pressure of 5 - 15 psig. The total catalyst volume of the reactor system was 150 - 350 ft 3The total supply rate to the reactor system was 2,000–15,000 lb / hour. The contact time was shortened by taking one of the two reactors out of operation and running it at a higher reactor supply rate.

[0086] [Table 4]

[0087] The results in Table 4 show that shortening the catalyst contact time correlates with improved HFC-245cb generation.

[0088] It should be understood that the foregoing description is merely illustrative of the present disclosure. Various alternative and modified forms can be devised by those skilled in the art without departing from the present disclosure. Accordingly, the present disclosure is intended to encompass all such alternative forms, modifications, and variations that fall within the scope of the appended claims.

[0089] manner Embodiment 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)) production process, wherein 1,1,1,3,3-pentafluoropropane (HFC-245fa) is defluorinated with a catalyst mixture to produce trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), The method comprises producing a product mixture containing 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 contains 10% to 90% by weight of a modified catalyst, based on the total weight of the catalyst mixture, which has an operating time of 20 to 500 days in the HFO-1234ze(E) production process.

[0090] Embodiment 2 is a catalyst mixture, based on the total weight of the catalyst mixture,

[0091]

number

[0092] Embodiment 3 is the method according to Embodiment 1 or Embodiment 2, wherein the catalyst mixture comprises 50% by weight of a modified catalyst having an operating time of 300 to 500 days in the HFO-1234ze(E) production process.

[0093] Embodiment 4 is the method according to any one of Embodiments 1 to 3, wherein the catalyst mixture comprises a dehydrofluorination catalyst selected from the group consisting of fluorinated metal oxides, metal halides, and carbon-supported transition metals.

[0094] Embodiment 5 is the method according to any one of Embodiments 1 to 4, further comprising recovering trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) from the product mixture by distillation.

[0095] Embodiment 6 is the method according to any one of Embodiments 1 to 5, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is 0.1 ppm to 100 ppm.

[0096] Embodiment 7 is a method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in a trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) production process, comprising dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the dehydrofluorination step is carried out at a temperature of 10°C to 310°C.

[0097] Embodiment 8 is the method according to Embodiment 7, wherein the dehydrofluorination process is carried out at a temperature of 288°C to 310°C.

[0098] Embodiment 9 is the method according to Embodiment 7 or Embodiment 8, wherein the temperature of the dehydrofluoridation process is maintained by an electric heating element, hot oil, or molten salt.

[0099] Embodiment 10 further comprises supplying a reaction mixture containing 1,1,1,3,3-pentafluoropropane (HFC-245fa) to a dehydrofluorination reaction, wherein the reaction mixture is at a temperature of 288°C to 310°C, and is the method according to any one of Embodiments 7 to 9.

[0100] Embodiment 11 is the method according to Embodiment 10, wherein the temperature of the reaction mixture is maintained by an electric heating element, hot oil, or molten salt.

[0101] Embodiment 12 is a method according to any one of Embodiments 7 to 11, further comprising recovering trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) from the product mixture by distillation.

[0102] Embodiment 13 is the method according to any one of Embodiments 7 to 12, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is 0.1 ppm to 100 ppm.

[0103] Embodiment 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)) production process, comprising dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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), wherein the contact time in the dehydrofluorination step is 1 second to 40 seconds.

[0104] Embodiment 15 is the method according to Embodiment 14, wherein the contact time is 1 second to 20 seconds.

[0105] Embodiment 16 is the method according to Embodiment 14 or Embodiment 15, wherein the dehydrofluorination process is carried out at a temperature of 288°C to 310°C.

[0106] Embodiment 17 is a method according to any one of Embodiments 14 to 16, further comprising recovering trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) from the product mixture by distillation.

[0107] Embodiment 18 is the method according to any one of Embodiments 15 to 17, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the product mixture is 0.1 ppm to 100 ppm.

[0108] Embodiment 19 is a composition comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) produced by the process described in any one of Embodiments 1 to 18.

[0109] Embodiment 20 is the composition according to Embodiment 19, wherein the amount of 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the composition is 0.1 ppm to 100 ppm.

[0110] Embodiment 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 the trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, The process involves dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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). A method wherein the catalyst mixture comprises 10% to 90% by weight of a modified catalyst, based on the total weight of the catalyst mixture, having an operating time of 20 to 500 days in the HFO-1234ze(E) production process.

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

3. The method according to claim 1, wherein the catalyst mixture comprises 50% by weight of a prepared catalyst having an operating time of 300 to 500 days in the HFO-1234ze(E) production 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 0.1 ppm to 100 ppm.

5. A method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, The process involves dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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). A method in which the dehydrofluoridation process is carried out at a temperature of 10°C to 310°C.

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

7. The method according to claim 5, further comprising supplying a reaction mixture containing 1,1,1,3,3-pentafluoropropane (HFC-245fa) to a dehydrofluoride reaction, wherein the reaction 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 0.1 ppm to 100 ppm.

9. A method for reducing 1,1,1,2,2-pentafluoropropane (HFC-245cb) in the trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) manufacturing process, The process involves dehydrofluorinating 1,1,1,3,3-pentafluoropropane (HFC-245fa) with 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). A method in which the contact time in the dehydrofluoridation process is 1 second to 40 seconds.

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

11. The method according to claim 9, wherein the dehydrofluorination step is carried out at a temperature of 288°C to 310°C.

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

13. A composition comprising trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) produced by the process described in 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 0.1 ppm to 100 ppm.

15. A composition, Trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and, cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)) and, 1,1,1,2,2-pentafluoropropane (HFC-245cb) in concentrations of 0.1 ppm to 100 ppm, A composition comprising hydrogen fluoride (HF).

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