Production method of e-1,3,3,3-tetrafluoropropene (hfc-1234ze) by dehydrofluorination processing

Abstract

To provide use of a fluoropropane of CF3CH=CHF as a refrigerant.SOLUTION: The invention provides use, as a refrigerant, of a fluoropropane of formula CF3CH=CHF produced by a production method of the fluoropropane of CF3CH=CHF. The production method comprises contacting a mixture of 1,1,1,3,3-pentafluoropropane and Z-1,3,3,3-tetrafluoropropene in the gas phase with a catalyst comprising at least one catalyst selected from the group consisting of fluorinated Cr2O3 or Cr / Ni on fluoride alumina, in the presence of an oxygen containing gas, to form a mixture comprising Z-1,3,3,3-tetrafluoropropane, E-1,3,3,3-tetrafluoropropene, hydrogen fluoride, and optionally unreacted 1,1,1,3,3-pentafluoropropane, separating the E-1,3,3,3-tetrafluoropropene from the Z-isomer and, if present, any unreacted 1,1,1,3,3-pentafluoropropane, and recovering the Z-1,3,3,3-tetrafluoropropene.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure generally relates to a method for synthesizing fluorinated olefins.

Background Art

[0002] The fluorocarbon industry has been working for the past several decades to find alternative refrigerants for ozone-depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that are being phased out as a result of the Montreal Protocol. Solutions for many applications have been to commercialize hydrofluorocarbon (HFC) compounds for use as refrigerants, solvents, fire extinguishants, blowing agents, and propellants. These new compounds, such as the most widely used HFC refrigerants today, HFC-134a and HFC-125, have an ozone depletion potential of zero and are thus not affected by current regulations that are being phased out as a result of the Montreal Protocol.

[0003] In addition to the problem of ozone depletion, another environmental problem in many of these applications is global warming. Therefore, there is a need for compositions that meet low ozone depletion standards and have a low global warming potential. Certain hydrofluoroolefins are thought to meet both of these goals. Therefore, there is a need for a manufacturing process that provides hydrogenated hydrocarbons and fluoroolefins that do not contain chlorine and similarly have a low global warming potential.

[0004] Both HFC-1234yf (CF3CF=CH2) and HFC-1234ze (CF3CH=CHF), which have zero ozone depletion potential and a low global warming potential, are recognized as potential refrigerants. U.S. Patent Application Publication No. 2006 / 0106263 A1 discloses the production of HFC-1234yf by catalytic gas-phase dehydrofluorination of CF3CF2CH3 or CF3CHFCH2F, and the production of HFC-1234ze (a mixture of the E isomer and the Z isomer) by catalytic gas-phase dehydrofluorination of CF3CH2CHF2.

[0005] The catalytic dehydrofluorination of hydrofluorocarbons to produce hydrofluoroolefins is usually carried out in the gas phase using a dehydrofluorination catalyst. Gas phase dehydrofluorination catalysts are well known in the art. These catalysts include, but are not limited to, alumina, aluminum fluoride, fluorinated alumina, metal compounds on aluminum fluoride, metal compounds on fluorinated alumina; chromium oxide, fluorinated chromium oxide, and cubic chromium trifluoride; magnesium, zinc, and oxides, fluorides, and oxyfluorides of mixtures of magnesium and zinc and / or aluminum; lanthanum oxide and fluorinated lanthanum oxide; carbon, acid-washed carbon, activated carbon, carbonaceous materials of three-dimensional matrices; and metal compounds supported on carbon. The metal compound is an oxide, fluoride, and oxyfluoride of at least one metal selected from the group consisting of sodium, potassium, rubidium, cesium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, chromium, iron, cobalt, rhodium, nickel, copper, zinc, and mixtures thereof. In another method, the dehydrofluorination treatment can be carried out in the liquid phase through reaction with an aqueous or alcoholic solution of a caustic substance such as potassium hydroxide or sodium hydroxide.

[0006] The catalytic dehydrofluorination of HFC-245fa generally produces a mixture of the E isomer and the Z isomer of HFC-1234ze. Depending on the specific catalyst selected, the amount of the Z isomer can vary between 15% and 23%. Also, the dehydrofluorination treatment in the liquid phase using an aqueous solution of a caustic substance or other strong base produces a mixture of both isomers. The ratio of the two isomers varies slightly with temperature, but typically about 13% to 15% of the Z isomer is formed. Since the E isomer is most useful for cooling applications, after separating the E isomer from the Z isomer, the Z isomer is typically either isomerized to the E isomer in a separate step or converted to 245fa by adding hydrogen fluoride. All of these alternative methods require additional steps that increase the cost. Summary of the Invention

Problems to be Solved by the Invention

[0007] There is still a need for a more selective and effective manufacturing process for producing HFC-1234ze and HFC-1234yf.

Means for Solving the Problems

[0008] A method for producing a fluoropropane of the formula CF3CH=CHF, comprising contacting a mixture of 1,1,1,3,3-pentafluoropropane and Z-,1,3,3,3-tetrafluoropropene in the gas phase, optionally in the presence of an oxygen-containing gas, with a catalyst comprising at least one catalyst selected from the group consisting of fluorinated Cr2O3 or Cr / Ni on aluminum fluoride to form a mixture comprising Z-1,3,3,3-tetrafluoropropene, E-1,3,3,3,-tetrafluoropropene, and optionally unreacted 1,1,1,3,3-pentafluoropropane; separating E-1,3,3,3-tetrafluoropropene from the Z isomer and, if present, unreacted 1,1,1,3,3-pentafluoropropane; and recycling said Z-1,3,3,3-tetrafluoropropene and feeding it together with further 1,1,1,3,3-pentafluoropropane to a reactor.

[0009] The above general description and the following description of the "Modes for Carrying Out the Invention" are merely illustrative and explanatory and do not limit the present invention as defined by the appended claims.

Modes for Carrying Out the Invention

[0010] A process for producing a fluoropropane of the formula CF3CH=CHF, comprising contacting a mixture of 1,1,1,3,3-pentafluoropropane and Z-,1,3,3,3-tetrafluoropropene in the gas phase, optionally in the presence of an oxygen-containing gas, with a catalyst comprising at least one catalyst selected from the group consisting of fluorinated Cr2O3 or Cr / Ni on aluminum fluoride, to form a mixture comprising Z-1,3,3,3-tetrafluoropropene, E-1,3,3,3,-tetrafluoropropene, and optionally unreacted 1,1,1,3,3-pentafluoropropane; separating the E-1,3,3,3-tetrafluoropropene from the Z isomer and, if present, unreacted 1,1,1,3,3-pentafluoropropane; and recycling the Z-1,3,3,3-tetrafluoropropene and feeding it back to the reactor together with further 1,1,1,3,3-pentafluoropropane.

[0011] Dehydrofluorination reactions are well known in the art. In particular, the dehydrofluorination of HFC-245fa has been studied. Both gas-phase and liquid-phase methods are well known. 1,3,3,3-Tetrafluoropropene (HFO-1234ze) exists as both a Z isomer and an E isomer with respect to the double bond. In both gas-phase and liquid-phase methods, it is known that a mixture of the Z isomer and the E isomer is produced, but the E isomer predominates. The selectivity in the production of the Z isomer can vary from about 10% to about 23% depending on temperature and catalyst selection. The boiling point of the E isomer at 1 atm is about -19 °C, and the boiling point of the Z isomer is about +9 °C. The E isomer is preferred for many applications. To minimize the yield loss in the form of the usually undesirable Z isomer, it is necessary to add an isomerization step to isomerize the Z isomer to the E isomer or a fluorination step to convert Z-1234ze back to HFC-245fa.

[0012] Numerous aspects and embodiments have been described above, which are merely illustrative and not limiting. After reading this specification, those skilled in the art will understand that other aspects and embodiments are possible without departing from the scope of the present invention.

[0013] Any one or more other features and advantages of the embodiments will become apparent from the following detailed description and the claims.

[0014] Dehydrofluorination is well known in the art and is preferably carried out in the vapor phase. The dehydrofluorination reaction can be carried out in any suitable reaction vessel or reactor, which preferably should be composed of materials resistant to the corrosive action of hydrogen fluoride such as nickel and its alloys such as Hastelloy, Monel, and Inconel, or containers lined with fluoropolymers. These may be a single tube or multiple tubes filled with a dehydrofluorination treatment catalyst.

[0015] Catalysts useful in the process include chromium-based catalysts such as chromium oxyfluoride, which may not be supported or may be supported on a carrier such as activated carbon, graphite, fluorinated graphite, or aluminum fluoride. The chromium catalyst may be used alone or in the presence of a cocatalyst selected from nickel, cobalt, manganese, or zinc salts. In one embodiment, the chromium catalyst is high surface area chromium oxide or chromium / nickel (Cr / Ni / AlF3) on aluminum fluoride, the production of which is reported in European Patent No. 486,333. In another embodiment, the catalyst is a Guignet's green catalyst. The chromium catalyst is preferably activated prior to use by heating the catalyst at 350-400 °C for a predetermined time under a nitrogen flow and then heating the catalyst for a further predetermined time under a flow of HF and nitrogen or air.

[0016] In one embodiment, Guinée green of the fluoride-activated Guinée green catalyst used in the present invention is produced by reacting (bonding) boric acid with an alkali metal dichromate at 500°C to 800°C and then hydrolyzing the reaction product. Therefore, Guinée green contains boron, an alkali metal, and water of hydration. Ordinary alkali metal dichromates are sodium dichromate and / or potassium dichromate. After the reaction, typically, a step of cooling the reaction product in air, a step of pulverizing this solid to produce a powder, and subsequent hydrolysis, filtration, drying, milling, and screening steps follow. Guinée green is bluish green but is mainly known as a green pigment, and thus the green pigment is generally called Guinée green. When used as a catalyst, it is also called Guinée green as disclosed in U.S. Patent No. 3,413,363. U.S. Patent No. 6,034,289 discloses a Cr2O3 catalyst preferably in the alpha form, and Guinée green also has a composition: 79 to 83% Cr2O3, 16 to 18% H2O by weight, 1.5 to 2.7% B2O5 (sentence spanning columns 2 to 3), and is disclosed as a commercially available green pigment that can be converted to the alpha form (column 3, l. 3). U.S. Patent No. 7,985,884 describes the presence of an alkali metal (54.5% Cr, 1.43% B, 3400 ppm Na, and 120 ppm K) in the composition of Guinée green disclosed in Example 1.

[0017] The physical shape of the catalyst is not important and can include, for example, pellets, extrudates, powders, or granules. The fluoride activation of the catalyst is preferably carried out in the final shape of the catalyst.

[0018] In one embodiment, the inventors of the present application have discovered that by feeding a mixture of HFC-245fa and at least about 10 wt% of the Z isomer of HFO-1234ze to a dehydrofluorination reactor in the presence of an oxygen-containing gas, further formation of the Z isomer can be suppressed, so that the HFC-245fa converted by the dehydrofluorination treatment produces substantially only E-HFO-1234ze. When the feed amount is less than about 10%, further formation of Z-1234ze is suppressed to some extent. When the feed amount of Z-1234ze exceeds about 10%, it only results in the presence of additional substances that must be separated and reused. The amount of Z-1234ze required to suppress further formation of the Z isomer product depends to some extent on the conversion rate. At a 245fa conversion rate of 70%, about 10-11% of the Z isomer is required in the feed. At a conversion rate of 80%, about 13% of the Z isomer is required in the feed.

[0019] In one embodiment, the reaction vessel can be maintained at a temperature of 200°C to 375°C. In another embodiment, the reaction vessel can be maintained at a temperature of 250°C to 350°C. In yet another embodiment, the reaction vessel can be maintained at a temperature of 275°C to 325°C.

[0020] The reaction pressure can be a pressure lower than atmospheric pressure, atmospheric pressure, or a pressure higher than atmospheric pressure. In one embodiment, the reaction is carried out at a pressure of 97 kPa to about 689 kPa (14 psig to about 100 psig). In another embodiment, the reaction is carried out at a pressure of 97 kPa to about 414 kPa (14 psig to about 60 psig). In yet another embodiment, the reaction is carried out at a pressure of 276 kPa to about 586 kPa (40 psig to about 85 psig). In yet another embodiment, the reaction is carried out at a pressure of 345 kPa to 517 kPa (50 psig to 75 psig). Generally, the pressure inside the reactor increased above atmospheric pressure acts to increase the contact time of the reactants in this process. As the contact time increases, the degree of conversion in the process inevitably increases, so there is no need to increase the temperature.

[0021] Depending on the temperature and contact time of the reactor, the product mixture of the reactor will contain different amounts of unreacted HFC-245fa. Next, E-1,3,3,3-tetrafluoropropene is separated from Z-1,3,3,3-tetrafluoropropene, hydrogen fluoride, and all unreacted HFC-245fa, and the unreacted HFC-245fa is returned to the reactor together with additional HFC-245fa for reuse. Hydrogen fluoride may be removed by scrubbing by passing the reactor effluent through an aqueous caustic solution, or hydrogen fluoride may be removed by distillation.

[0022] In one embodiment, the feed to the reactor is preheated in a vaporizer to a temperature of about 30 °C to about 100 °C. In another embodiment, the feed to the reactor is preheated in a vaporizer to a temperature of about 30 °C to about 80 °C.

[0023] In some embodiments, an inert diluent gas is used as the carrier gas for the hydrochlorofluoropropane. In one embodiment, the carrier gas is selected from nitrogen, argon, helium, or carbon dioxide.

[0024] As used in this invention, the terms "comprises", "comprising", "includes", "including", "has", "having", or any other variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a list of elements is not necessarily limited to those elements, and may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not an exclusive or. For example, condition A or B is satisfied by any of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0025] The transitional phrase "consisting of" excludes any unspecified element, step, or ingredient. In the context of a claim, such a phrase limits the claim with respect to encompassing materials other than the recited materials, except for impurities normally associated with the materials. When the phrase "consisting of" appears not immediately after the preamble but within a clause of the claim body, this phrase only limits the elements set forth within that clause, and other elements are not excluded from the entire scope of the claim. The transitional phrase "consisting essentially of" is used to define a composition or method that includes, in addition to what is literally disclosed, materials, steps, features, components, or elements, provided that these additionally included materials, steps, features, components, or elements do not substantially affect the basic and novel features (s) of the claimed invention, particularly the mechanism of action for achieving the desired result of any process of the present invention. The term "essentially consisting of" occupies an intermediate position between "comprising" and "consisting of".

[0026] Also, the use of "a" or "an" is employed to describe the elements and components described herein. This is for convenience only and to give a general sense of the scope of the present invention. This description should be construed to include one or at least one, and the singular form also includes the plural form unless it is apparent that it has a different meaning.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, but the preferred methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference in their entirety, unless specifically cited to the contrary. In case of conflict, this specification, including definitions, will control. Further, the materials, methods, and examples are illustrative only and not intended to be limiting.

Examples

[0028] The concepts described in this specification are further illustrated in the following examples, which do not limit the scope of the invention described in the claims.

[0029] (Example 1) Example 1 shows the dehydrofluorination treatment of 245fa passed through Cr2O3 in the presence of Z-HFC-1234ze.

[0030] An Inconel tube (outer diameter 1.3 cm (1 / 2 inch)) was filled with 10 cc (8 grams) of a Cr2O3 catalyst (Johnson Mathey) prepared as follows. Chromium oxide in the form of extrudates was ground and sieved through a 12 / 20 mesh sieve. After filling the reaction tube, the temperature of the catalyst bed was raised to 300 °C and purged with nitrogen (30 cc / min) for 200 minutes. Then the nitrogen flow was reduced to 60 cc / min and HF was fed in at 20 cc / min for 60 minutes. This temperature was raised to 325 °C for 300 minutes. Next, the nitrogen flow was reduced to 30 cc / min and the HF flow was increased to 30 cc / min for 30 minutes. Next, the nitrogen flow was reduced to 12 cc / min and the HF flow was increased to 48 cc / min for 60 minutes. Next, the nitrogen flow was stopped and the HF flow was increased to 48 cc / min for 30 minutes. Then, the temperature of the reactor was reduced to 250 °C for 30 minutes. Thereafter, HF was stopped and the reactor was purged with nitrogen at 30 cc / min. Next, the temperature of the reactor was stabilized at 300 °C, the nitrogen flow was stopped, and either CF3CH2CHF2 or CF3CH2CHF2 with the amount of Z-1234ze varied was fed in at 1.44 mL / hour. The contact time in the reactor was 45 seconds. CF3CH2CHF2 was evaporated at 50 °C. A portion of the reactor effluent was passed through a series of valves and analyzed by GCMS. The amounts of Z-1234ze, 245fa, and E-1234ze are expressed as mole fractions. The results are summarized in Table 1.

[0031] [Table 1]

[0032] (Example 2) Example 2 shows the dehydrofluorination treatment of 245fa passed through Cr2O3 in the presence of Z-HFC-1234ze.

[0033] An Inconel tube (outer diameter 1.3 cm (1 / 2 inch)) was filled with 10 cc (8 grams) of a Cr2O3 catalyst (Geneva green) prepared as follows. The extruded chromium oxide was ground and sieved through a 12 / 20 mesh sieve. After filling the reactor tube, the temperature of the catalyst bed was raised to 300 °C and purged with nitrogen (30 cc / min) for 200 minutes. Then the nitrogen flow was reduced to 60 cc / min and HF was fed in at 20 cc / min for 60 minutes. This temperature was raised to 325 °C for 300 minutes. Next, the nitrogen flow was reduced to 30 cc / min and the HF flow was raised to 30 cc / min for 30 minutes. Next, the nitrogen flow was reduced to 12 cc / min and the HF flow was raised to 48 cc / min for 60 minutes. Next, the nitrogen flow was stopped and the HF flow was raised to 48 cc / min for 30 minutes. Then, the temperature of the reactor was lowered to 250 °C for 30 minutes. Then HF was stopped and the reactor was purged with nitrogen at 30 cc / min. Next, the temperature of the reactor was stabilized at 300 °C, the nitrogen flow was stopped, and either CF3CH2CHF2 or CF3CH2CHF2 with the amount of Z-1234ze varied was fed in at 1.44 mL / hour. The contact time in the reactor was 45 seconds. CF3CH2CHF2 was evaporated at 50 °C. A portion of the reactor effluent was passed through a series of valves and analyzed by GCMS. The amounts of Z-1234ze, 245fa, and E-1234ze are expressed as mole fractions. The results are summarized in Table 2.

[0034] [Table 2]

[0035] (Example 3) Example 3 shows the dehydrofluorination treatment of 245fa passed through Cr2O3 in the presence of Z-HFC-1234ze.

[0036] An Inconel tube (outer diameter 1.3 cm (1 / 2 inch)) was filled with 10 cc (8 grams) of a Cr2O3 catalyst (Johnson Mathey) prepared as follows. The extruded chromium oxide was ground and passed through a 12 / 20 mesh sieve. After filling the reactor tube, the temperature of the catalyst bed was raised to 300 °C and purged with nitrogen (30 cc / min) for 200 minutes. Then the nitrogen flow was reduced to 60 cc / min and HF was fed in at 20 cc / min for 60 minutes. This temperature was raised to 325 °C for 300 minutes. Next, the nitrogen flow was reduced to 30 cc / min and the HF flow was raised to 30 cc / min for 30 minutes. Next, the nitrogen flow was reduced to 12 cc / min and the HF flow was raised to 48 cc / min for 60 minutes. Next, the nitrogen flow was stopped and the HF flow was raised to 48 cc / min for 30 minutes. Then, the temperature of the reactor was lowered to 250 °C for 30 minutes. Thereafter, HF was stopped and the reactor was purged with nitrogen at 30 cc / min. Next, the temperature of the reactor was stabilized at 300 °C, the nitrogen flow was stopped, and either CF3CH2CHF2 or CF3CH2CHF2 with the amount of Z-1234ze varied was fed in at 1.44 mL / hour. The contact time in the reactor was 45 seconds. CF3CH2CHF2 was evaporated at 50 °C. A portion of the reactor effluent was passed through a series of valves and analyzed by GCMS. The amounts of Z-1234ze, 245fa, and E-1234ze are expressed as mole fractions. The results are summarized in Table 3.

[0037] [Table 3]

[0038] (Example 4) Example 4 shows the dehydrofluorination of 245fa passing over Cr2O3 in the presence of Z-HFC-1234ze.

[0039] An Inconel tube (outer diameter 1.3 cm (1 / 2 inch)) was filled with 10 cc (8 grams) of a Cr2O3 catalyst (Newport Cr) prepared as follows. The extruded chromium oxide was ground and passed through a 12 / 20 mesh sieve. After filling the reactor tube, the temperature of the catalyst bed was raised to 300 °C and purged with nitrogen (30 cc / min) for 200 minutes. Then the nitrogen flow was reduced to 60 cc / min and HF was fed in at 20 cc / min for 60 minutes. This temperature was raised to 325 °C for 300 minutes. Next, the nitrogen flow was reduced to 30 cc / min and the HF flow was raised to 30 cc / min for 30 minutes. Next, the nitrogen flow was reduced to 12 cc / min and the HF flow was raised to 48 cc / min for 60 minutes. Next, the nitrogen flow was stopped and the HF flow was raised to 48 cc / min for 30 minutes. Then, the temperature of the reactor was reduced to 250 °C for 30 minutes. Thereafter, HF was stopped and the reactor was purged with nitrogen at 30 cc / min. Next, the temperature of the reactor was stabilized at 300 °C, the nitrogen flow was stopped, and either CF3CH2CHF2 or CF3CH2CHF2 with the amount of Z-1234ze varied was fed in at 1.44 mL / hour. The contact time in the reactor was 45 seconds. CF3CH2CHF2 was evaporated at 50 °C. A portion of the reactor effluent was passed through a series of valves and analyzed by GCMS. The amounts of Z-1234ze, 245fa, and E-1234ze are expressed as mole fractions. The results are summarized in Table 4.

[0040]

Table 4

[0041] (Example 5) Example 4 shows the dehydrofluorination of 245fa passed over aluminum fluoride in the presence of Z-HFC-1234ze.

[0042] An Inconel tube (outer diameter 1.3 cm (1 / 2 inch)) is filled with 10 cc (6.1 grams) of Al2O3 catalyst (purchased from Sigma-Aldrich). The extruded form of Al2O3 is crushed and passed through a 12 / 20 mesh sieve. After filling the reactor tube, the temperature of the catalyst layer is raised to 300 °C and purged with nitrogen (30 cc / min) for 200 minutes. Then the nitrogen flow is reduced to 60 cc / min and HF is fed in at 20 cc / min for 60 minutes. This temperature is raised to 325 °C for 300 minutes. Then the nitrogen flow is reduced to 30 cc / min and the HF flow is raised to 30 cc / min for 30 minutes. Next, the nitrogen flow is reduced to 12 cc / min and the HF flow is raised to 48 cc / min for 60 minutes. Next, the nitrogen flow is stopped and the HF flow is raised to 48 cc / min for 30 minutes. Then, the temperature of the reactor is reduced to 250 °C for 30 minutes. Thereafter, HF is stopped and the reactor is purged with nitrogen at 30 cc / min. Next, the temperature of the reactor is stabilized at 300 °C, the nitrogen flow is stopped, and either CF3CH2CHF2 or CF3CH2CHF2 with a varied amount of Z-1234ze is fed in at 1.44 mL / hour. The contact time in the reactor is 45 seconds. CF3CH2CHF2 is evaporated at 50 °C. A portion of the reactor effluent is passed through a series of valves and analyzed by GCMS. The amounts for Z-1234ze, 245fa, and E-1234ze are expressed as mole fractions. The results are summarized in Table 5.

[0043]

Table 5

[0044] Note that not all of the operations described above in the general description or examples are necessary. In some cases, some of the specific operations may not be necessary, and one or more additional operations may be performed in addition to the operations described above. Further, the order in which the operations are described is not necessarily the order in which they are performed.

[0045] In the above specification, the concept of the present invention has been described with reference to specific embodiments. However, those skilled in the art will understand that various modifications and changes can be made without departing from the scope of the present invention as set forth in the following claims. Therefore, this specification and the figures are to be regarded as illustrative rather than restrictive in nature, and all such modifications are intended to be included within the scope of the present invention.

[0046] Benefits, other advantages, and solutions to problems have been described above in the context of specific embodiments. However, none of these benefits, advantages, problem solutions, and any features that may give rise to or make more apparent any benefit, advantage, or solution are to be construed as essential, necessary, or indispensable features in part or all of the claims.

[0047] For clarity, it should be understood that specific features described herein in the context of separate embodiments may be provided in combination within a single embodiment. Conversely, for brevity, various features described in the context of a single embodiment may also be provided separately or in any sub-combination. Further, references to values recited in ranges include each and every value within that range.

Claims

[Claim 1] A method for selectively producing E-1,3,3,3-tetrafluoropropene, comprising the steps of: a) preheating a reactor feed comprising 92.5-89 wt. % 1,1,1,3,3-pentafluoropropane (HFC-245fa) and 7.5-11 wt. % Z-1,3,3,3-tetrafluoropropene to a temperature range of 30-80° C.; b) Preheated feeds of 0.5-11 wt. % Z-1,3,3,3-tetrafluoropropene and HFC-245fa are reacted in a reactor in the vapor phase at 200-375° C. with Cr 2 O 3 to produce E-1,3,3,3-tetrafluoropropene in a mixture containing Z-1,3,3,3-tetrafluoropropene, hydrogen fluoride, and optionally unreacted 1,1,1,3,3-pentafluoropropane with a selectivity of 94.2% or greater; c) separating the E-1,3,3,3-tetrafluoropropene from the Z isomer and, if present, any unreacted 1,1,1,3,3-pentafluoropropane; d) recovering the E-1,3,3,3-tetrafluoropropene; A method comprising:

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