COMPOSITION WITH TETRAFLUORPROPENE

Description

FIELD OF INVENTION

[0001] The present invention relates to a tetrafluoropropene composition characterized in that it comprises, in molar proportions, 1 to 50 ppm of HCC-40, 1 to 50 ppm of HFC-152a, 1 to 50 ppm of HFC-41 and 1 to 50 ppm of HFC-32. TECHNICAL BACKGROUND

[0002] Greenhouse gases are gaseous components that absorb infrared radiation emitted by the Earth's surface, thus contributing to the greenhouse effect. Their increasing concentration in the atmosphere is one of the factors driving global warming.

[0003] The production of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) used in refrigeration and air conditioning systems has been regulated by the Montreal and Kyoto Protocols. There is a need to develop new molecules that are just as effective and, in particular, have the lowest possible global warming potential. This is the case with hydrofluoroolefins, and especially HFO-1234yf, which is a particularly useful compound.

[0004] It is known to produce hydrofluoroolefins or hydrofluorocarbons by fluorinating hydrochloroolefins or hydrochlorocarbons, among other things. This fluorination is generally a catalytic fluorination using hydrofluoric acid as the fluorinating agent.

[0005] The fluorination reaction must generally be carried out at a high temperature (over 300°C), in the gas phase, in the presence of a supported or bulk solid catalyst.

[0006] It is known to provide co-feeding with an oxidizing agent, in particular air, or possibly chlorine, to preserve the life of the catalyst and limit the deposition of coke on its surface during the reaction step.

[0007] US document 8,614,361 describes a process for manufacturing HFO-1234yf by reacting HCFO-1233xf with HF in the presence of a high oxygen content.

[0008] US patent 8,618,338 describes a two-step process for manufacturing fluoroolefin, specifically a first liquid-phase reaction step from 1,1,2,3-tetrachloropropene (HCO-1230xa) to obtain the intermediate HCFO-1233xf and a second gas-phase reaction step from HCFO-1233xf to obtain HFO-1234yf.

[0009] Document WO 2013 / 088195 teaches a process for manufacturing HFO-1234yf in two steps, a first step of gas-phase fluorination of 1,1,1,2,3-pentachloropropane (HCC-240db) and / or 1,1,2,2,3-pentachloropropane (HCC-240aa) to obtain the intermediate HCFO-1233xf, then a second step of gas-phase reaction from HCFO-1233xf to obtain HFO-1234yf.

[0010] Documents WO 2012 / 098421 and WO 2012 / 098422 teach the activation and regeneration of fluorination catalysts.

[0011] Document WO 2013 / 182816 describes a chemical reaction process for the alternating implementation of a catalytic reaction phase and a catalyst regeneration phase in a reactor.

[0012] There is still a need to improve the manufacturing processes of HFO-1234 such as HFO-1234yf, and in particular to produce these compounds with a high yield and in a high degree of purity. SUMMARY OF THE INVENTION

[0013] This disclosure primarily concerns a process for manufacturing tetrafluoropropene, comprising, in an alternating manner: at least one reaction step of a chlorinated compound with hydrofluoric acid in the gas phase, in the presence of a fluorination catalyst, the proportion of oxygen possibly present being less than 0.05 mol.% relative to the chlorinated compound; a regeneration step of the fluorination catalyst by contacting the fluorination catalyst with a regeneration stream comprising an oxidizing agent.

[0014] According to one embodiment, the step of reacting the chlorinated compound with hydrofluoric acid is carried out essentially in the absence of oxygen, and preferably essentially in the absence of any oxidizing agent.

[0015] According to one embodiment, the regeneration stream contains at least 1 mol.% of oxygen relative to the total regeneration stream.

[0016] According to one embodiment, the step of reacting the chlorinated compound with hydrofluoric acid is carried out in a single reactor, separately in time from the step of regenerating the fluorination catalyst.

[0017] According to one embodiment, the step of reacting the chlorinated compound with hydrofluoric acid is carried out in at least one first reactor, simultaneously with the implementation of the step of regenerating the fluorination catalyst in at least one second reactor.

[0018] According to one embodiment, tetrafluoropropene is 2,3,3,3-tetrafluoropropene.

[0019] According to one embodiment, tetrafluoropropene is 1,3,3,3-tetrafluoropropene.

[0020] According to one embodiment, the chlorinated compound is chosen from tetrachloropropenes, chlorotrifluoropropenes, pentachloropropanes and mixtures thereof.

[0021] According to one embodiment, the chlorinated compound is 2-chloro-3,3,3-trifluoropropene, and the tetrafluoropropene is 2,3,3,3-tetrafluoropropene.

[0022] According to one embodiment, the chlorinated compound is 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane, and the tetrafluoropropene is 2,3,3,3-tetrafluoropropene.

[0023] According to one embodiment, the chlorinated compound is 1-chloro-3,3,3-trifluoropropene, and the tetrafluoropropene is 1,3,3,3-tetrafluoropropene.

[0024] According to one embodiment, the process comprises: a preliminary manufacturing step of the chlorinated compound, which is preferably a preliminary reaction step of a preliminary compound with gas-phase hydrofluoric acid, in the presence of a preliminary fluorination catalyst, the proportion of oxygen possibly present being less than 0.05 mol.% relative to the preliminary compound.

[0025] According to one embodiment, the preliminary reaction step is carried out alternately with: a regeneration step of the preliminary fluorination catalyst by contacting the preliminary fluorination catalyst with a regeneration stream comprising an oxidizing agent.

[0026] According to one embodiment, the preliminary compound is 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane, the chlorinated compound is 1-chloro-3,3,3-trifluoropropene and the tetrafluoropropene is 2,3,3,3-tetrafluoropropene.

[0027] According to one embodiment, the process comprises: the collection of a product stream at the end of the preliminary reaction step; the separation of the product stream into a first stream comprising hydrochloric acid and tetrafluoropropene and a second stream comprising hydrofluoric acid and the chlorinated compound; the use of said second stream to carry out the reaction step of the chlorinated compound with hydrofluoric acid; and optionally, the collection of a product stream at the end of the reaction step of the chlorinated compound with hydrofluoric acid, and the recycling thereof to the preliminary reaction step.

[0028] This disclosure also relates to a tetrafluoropropene manufacturing facility, comprising at least one gas-phase fluorination reactor including a fluorination catalyst bed, said gas-phase fluorination reactor being configured to be fed alternately by: a reaction flow feed system comprising a chlorinated compound and hydrofluoric acid, the proportion of oxygen possibly present in this reaction flow being less than 0.05 mol.% relative to the chlorinated compound; and a regeneration flow feed system comprising an oxidizing agent.

[0029] According to one embodiment, the reaction flow is essentially devoid of oxygen, and preferably of any oxidizing agent.

[0030] According to one embodiment, the regeneration stream contains at least 1 mol.% of oxygen relative to the total regeneration stream.

[0031] According to one embodiment, the installation comprises a single reactor configured to be fed alternately by the reaction flow feed system and the regeneration flow feed system.

[0032] According to one embodiment, the installation comprises a plurality of reactors, each configured to be fed alternately by a reaction flow feed system and a regeneration flow feed system.

[0033] According to one embodiment, the installation is configured such that when one reactor is fed by the reaction flow feeding system, another reactor is fed by the regeneration flow feeding system.

[0034] According to one embodiment, the installation is configured such that: the reaction flow feed system feeds the bottom reactor and the regeneration flow feed system feeds the bottom reactor; or the reaction flow feed system feeds the bottom reactor and the regeneration flow feed system feeds the top reactor; or the reaction flow feed system feeds the top reactor and the regeneration flow feed system feeds the bottom reactor; or the reaction flow feed system feeds the top reactor and the regeneration flow feed system feeds the top reactor.

[0035] According to one embodiment: Tetrafluoropropene is 2,3,3,3-tetrafluoropropene; or tetrafluoropropene is 1,3,3,3-tetrafluoropropene.

[0036] According to one embodiment, the chlorinated compound is selected from tetrachloropropenes, chlorotrifluoropropenes, pentachloropropanes and mixtures thereof; and preferably: the chlorinated compound is 2-chloro-3,3,3-trifluoropropene and the tetrafluoropropene is 2,3,3,3-tetrafluoropropene; or the chlorinated compound is 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane, and the tetrafluoropropene is 2,3,3,3-tetrafluoropropene; or the chlorinated compound is 1-chloro-3,3,3-trifluoropropene, and the tetrafluoropropene is 1,3,3,3-tetrafluoropropene.

[0037] According to one embodiment, the installation comprises: at least one chlorinated compound manufacturing unit, which preferably is at least one preliminary fluorination reactor; configured to be fed by: a reaction media feeding system comprising a preliminary compound and hydrofluoric acid, the proportion of oxygen possibly present in this reaction stream being less than 0.05 mol.% relative to the preliminary compound.

[0038] According to one embodiment, the preliminary fluorination reactor is also configured to be fed by a regeneration flow feed system comprising an oxidizing agent.

[0039] According to one embodiment, the preliminary compound is 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane, the chlorinated compound is 1-chloro-3,3,3-trifluoropropene and the tetrafluoropropene is 2,3,3,3-tetrafluoropropene.

[0040] According to one embodiment, the installation comprises: at least one first catalytic fluorination reactor; at least one second catalytic fluorination reactor; a product stream collection system connected to the outlet of the first catalytic fluorination reactor; a separation unit fed by the product stream collection system; a first collection line and a second collection line connected to the outlet of the separation unit, the first collection line being configured to carry a stream comprising hydrochloric acid and tetrafluoropropene and the second collection line being configured to carry a stream comprising hydrofluoric acid and the chlorinated compound; an intermediate collection system connected to the outlet of the second reactor; a first reaction medium supply system configured to supply the first reactor, the latter being itself supplied by the intermediate collection system;a second reaction medium feed system configured to feed the second reactor, which is itself fed by the second collection line; a regeneration flow feed system configured to feed the first reactor and / or the second reactor; and a regeneration gas flow collection system.

[0041] According to one embodiment, the installation includes at least two second reactors configured such that when one of these reactors is fed by the second reaction flow feed system, the other reactor is fed by the regeneration flow feed system.

[0042] According to one embodiment, the installation comprises at least two first reactors and two second reactors configured such that when one of the first reactors and one of the second reactors are respectively fed by the first reaction flow feed system and the second reaction flow feed system, the other first reactor and the other second reactor are fed by the regeneration flow feed system; and which, preferably, is configured such that the same regeneration flow from the regeneration flow feed system passes successively through the first reactor and then the second reactor, or passes successively through the second reactor and then the first reactor.

[0043] According to one embodiment, the installation includes a single second reactor, configured to be fed sequentially either by the second reaction flow feed system or by the regeneration flow feed system.

[0044] According to one embodiment, the installation comprises a single first reactor and a single second reactor, configured to be fed sequentially either by the second reaction flow feed system or by the regeneration flow feed system; and which, preferably, is configured such that the same regeneration flow from the regeneration flow feed system passes successively through the first reactor and then the second reactor, or passes successively through the second reactor and then the first reactor.

[0045] The invention also relates to a tetrafluoropropene composition characterized in that it comprises, in molar proportions, 1 to 50 ppm of HCC-40, 1 to 50 ppm of HFC-152a, 1 to 50 ppm of HFC-41 and 1 to 50 ppm of HFC-32.

[0046] The present invention overcomes the drawbacks of the prior art. In particular, this disclosure provides a high-yield process for manufacturing HFO-1234 (and especially HFO-1234yf) that delivers the desired product in a high degree of purity.

[0047] This is achieved through the discovery by the present inventors that certain fluorination reaction steps can be carried out essentially in the absence of an oxidizing agent such as oxygen, without the lifetime of the fluorination catalyst being visibly affected over a given period, provided that intermediate regeneration steps are provided.

[0048] The resulting advantage is the production of a higher-purity HFO-1234 gas stream, obtained essentially in the absence of oxygen during the reaction. The content of carbon oxides and compounds containing one or two carbon atoms is significantly reduced compared to the prior art. Downstream processing and final purification of the desired product are thus simplified, guaranteeing a final product preferably with a purity greater than or equal to 98%, advantageously greater than or equal to 99%, and very advantageously greater than or equal to 99.8% by weight. The co-produced hydrochloric acid is also more readily utilized. BRIEF DESCRIPTION OF THE FIGURES

[0049] THE figures 1a and 1b schematically represent an embodiment of an installation with a single catalytic fluorination reactor, in two different operating configurations. figures 2a and 2bschematically represent an embodiment of an installation with two catalytic fluorination reactors, in two different operating configurations. figure 3 This schematically represents an embodiment of an installation with three catalytic fluorination reactors, in a specific operating configuration. figures 4a and 4b schematically represent an embodiment of an installation with a single catalytic fluorination reactor, in two different operating configurations. figures 5a and 5b schematically represent an embodiment of an installation with two catalytic fluorination reactors, in two different operating configurations. figure 6 This schematically represents an embodiment of an installation with three catalytic fluorination reactors, in a specific operating configuration. figures 7 to 11schematically represent methods of implementing installations for the production of HFO-1234yf in two stages. DESCRIPTION OF METHODS OF IMPLEMENTING THE INVENTION

[0050] The invention is now described in more detail and in a non-limiting manner in the following description.

[0051] Unless otherwise stated, the percentages and proportions indicated are in mass values.

[0052] This disclosure describes the production of HFO-1234 by gas-phase catalytic fluorination; this catalytic fluorination is, according to the invention, alternated with the regeneration of the fluorination catalyst. In some embodiments, the invention provides for the production of HFO-1234 in several fluorination steps. Fluoride reaction to obtain HFO-1234

[0053] This disclosure provides for at least one fluorination step, enabling the production of HFO-1234 from a chlorinated compound.

[0054] HFO-1234 can be in particular HFO-1234yf or HFO-1234ze (1,3,3,3-tetrafluoropropene), and this in cis or trans form or in a mixture of cis and trans forms.

[0055] By "chlorinated compound", We are talking about an organic compound comprising one or more chlorine atoms. This compound preferably comprises 3 carbon atoms.

[0056] This chlorinated compound is preferably a propane or a propene having substituents selected from F, Cl, I and Br (preferably from F and Cl), and comprising at least one Cl substituent.

[0057] It is understood that by " chlorinated compound We also hear about mixtures of compounds.

[0058] Preferably, the chlorinated compound is a tetrachloropropene, a chlorotrifluoropropene, a pentachloropropane or a mixture thereof.

[0059] In one embodiment, the chlorinated compound is 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), to produce HFO-1234yf.

[0060] In another embodiment, the chlorinated compound is 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), to produce HFO-1234ze.

[0061] In another embodiment, the chlorinated compound is 1,1,1,2,3-pentachloropropane (HCC-240db), or 1,1,2,2,3-pentachloropropane (HCC-240aa), or a mixture of the two, to produce HFO-1234yf.

[0062] According to yet another embodiment, the chlorinated compound is 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db), to produce HFO-1234yf.

[0063] According to yet another embodiment, the chlorinated compound is 1,1,2,3-tetrachloropropene (HCO-1230xa), or 2,3,3,3-tetrachloropropene (HCO-1230xf), or a mixture of these two compounds, to produce HFO-1234yf.

[0064] The conversion of the chlorinated compound to HFO-1234 can be a direct conversion or an indirect conversion (i.e. involving an intermediate product).

[0065] The fluorination of the chlorinated compound to HFO-1234 is carried out in one or more gas-phase fluorination reactors comprising a fluorination catalyst bed.

[0066] The catalyst used may, for example, be based on a metal containing a transition metal oxide, a derivative, a halide, or an oxyhalide of such a metal. Examples include FeCl₃, chromium oxyfluoride, chromium oxides (possibly subjected to fluorination treatments), chromium fluorides, and mixtures thereof. Other possible catalysts include carbon-supported catalysts, antimony-based catalysts, and aluminum-based catalysts (e.g., AlF₃ and Al₂O₃, aluminum oxyfluoride, and aluminum fluoride).

[0067] In general, one can use a chromium oxyfluoride, an aluminum fluoride or oxyfluoride, or a supported or unsupported catalyst containing a metal such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge, Sn, Pb, Mg, Sb.

[0068] Reference can be made in this regard to document WO 2007 / 079431 (on p.7, I.1-5 and 28-32), to document EP 939071 (paragraph

[0022] ), to document WO 2008 / 054781 (on p.9 I.22-p.10 I.34), and to document WO 2008 / 040969 (claim 1), to which express reference is made.

[0069] The catalyst is more particularly preferred to be chromium-based and it is more specifically a mixed catalyst including chromium.

[0070] According to one embodiment, a mixed catalyst comprising chromium and nickel is used. The Cr / Ni molar ratio (based on the metallic element) is generally from 0.5 to 5, for example from 0.7 to 2, for example about 1. The catalyst may contain from 0.5 to 20 wt% of chromium, and from 0.5 to 20 wt% of nickel, preferably from 2 to 10 wt% of each.

[0071] The metal can be present in its metallic form or as a derivative, for example an oxide, halide, or oxyhalide. These derivatives are preferably obtained by catalytic activation of the metal.

[0072] The support is preferably made of aluminum, for example alumina, activated alumina or aluminum derivatives, such as aluminum halides and aluminum oxyhalides, for example described in US document 4,902,838, or obtained by the activation process described above.

[0073] The catalyst may comprise chromium and nickel in an activated or non-activated form, on a support that has been subjected to activation or not.

[0074] Reference can be made to document WO 2009 / 118628 (particularly p.4, I.30-p.7 I.16), to which express reference is made here.

[0075] Another preferred embodiment is based on a mixed catalyst containing chromium and at least one element chosen from Mg and Zn. The atomic ratio of Mg or Zn / Cr is preferably from 0.01 to 5.

[0076] Before use, the catalyst is preferably activated with air, oxygen or chlorine and / or with HF.

[0077] For example, the catalyst is preferably activated with air or oxygen and HF at a temperature of 100 to 500°C, preferably 250 to 500°C and more particularly 300 to 400°C. The activation time is preferably 1 to 200 h and more particularly 1 to 50 h.

[0078] This activation can be followed by a final fluorination activation step in the presence of an oxidizing agent, HF and organic compounds.

[0079] The molar ratio of HF to organic compounds is preferably from 2 to 40 and the molar ratio of oxidizing agent to organic compounds is preferably from 0.04 to 25. The final activation temperature is preferably from 300 to 400°C and its duration is preferably from 6 to 100 h.

[0080] The gas-phase fluorination reaction can be carried out: with an HF / chlorinated compound molar ratio of 1:1 to 150:1, preferably 3:1 to 100:1 and more particularly preferred 5:1 to 50:1; with a contact time of 1 to 100 s, preferably 1 to 50 s and more particularly 2 to 40 s (catalyst volume divided by the total incoming flux, adjusted for operating temperature and pressure); at an absolute pressure of 0.1 to 50 bar, preferably 0.3 to 15 bar; at a temperature (catalyst bed temperature) of 100 to 500°C, preferably 200 to 450°C, and more particularly 250 to 400°C.

[0081] The flux composing the reaction medium may include, in addition to HF and the chlorinated compound, additional compounds, including other halohydrocarbons or halohydroolefins.

[0082] The duration of the reaction stage is typically 10 to 2000 hours, preferably 50 to 500 hours and more particularly preferred 70 to 300 hours.

[0083] The proportion of oxygen possibly present in the reaction medium is less than 0.05 mol% relative to the chlorinated compound, preferably even less than 0.02 mol% or less than 0.01 mol%. Traces of oxygen may be present, but preferably the fluorination step is carried out essentially in the absence of oxygen, or in the total absence of oxygen.

[0084] Preferably, the proportion of any oxidizing agent (such as oxygen and chlorine) that may be present in the reaction medium is less than 0.05 mol% relative to the chlorinated compound, preferably even less than 0.02 mol% or less than 0.01 mol%. Traces of oxidizing agent may be present, but preferably the step is carried out essentially in the absence of oxidizing agent, or in the total absence of oxidizing agent.

[0085] The product stream from the fluorination step of the chlorinated compound to HFO-1234 can undergo appropriate treatments (distillation, washing, etc.) to recover the purified HFO-1234 and separate it from other compounds present (HCl, unreacted HF, unreacted chlorinated compound, other organics). One or more streams can be recycled.

[0086] HCl in particular can be purified according to the process described in application no. FR 13 / 61736, to which express reference is made. Catalyst regeneration

[0087] In each reactor used for the implementation of the fluorination of the chlorinated compound to HFO-1234, said fluorination may be alternated with phases of catalyst regeneration, in the presence of oxygen.

[0088] For example, we can switch from the reaction phase to the regeneration phase when the conversion of the chlorinated compound falls below a predetermined threshold, for example 50%.

[0089] If necessary, a transition period is first carried out to decompress the reaction gas phase. This may be followed by a purging phase using an inert gas or by vacuuming the system to completely remove any remaining reactants.

[0090] The regeneration stream preferably contains at least 1 mol% total oxygen. This may be pure air, but the stream may also contain an inert gas useful for ensuring some dilution, for example nitrogen, argon, helium, or hydrofluoric acid in proportions ranging from 0 to 95%, preferably from 5 to 85%, and more particularly preferably from 10 to 80%. The flow rate of the regeneration stream is preferably kept sufficiently high to avoid external diffusion regimes.

[0091] The temperature at the regeneration stage is, for example, from 100 to 500°C, preferably from 200 to 450°C, and more particularly preferred from 250 to 400°C. It can be practical to carry out the regeneration at the same temperature as the reaction.

[0092] The pressure at the regeneration stage is, for example, atmospheric pressure at 15 bar absolute. It is preferably approximately equal to atmospheric pressure.

[0093] The duration of the regeneration stage is typically 10 to 2000 hours, preferably 50 to 500 hours and more particularly preferred 70 to 300 hours.

[0094] Regeneration can be carried out in co-current or counter-current flow relative to the direction of flow used during the reaction period.

[0095] This regeneration step allows the catalyst to recover its initial activity. Several cycles can thus be linked together without significantly altering the catalyst's activity, thereby increasing its lifespan.

[0096] At the end of the regeneration stage, the reactor can be evacuated to remove the inert gases and oxygen introduced, prior to the reintroduction of organics. Installations for carrying out the fluoridation step described above

[0097] The fluorination step described above can be implemented with a single reactor. In this case, the reactor is operated alternately in reaction and regeneration modes. Production is then discontinuous.

[0098] Alternatively, the fluorination step described above can be implemented with a plurality of reactors, for example two, three, or more than three reactors. In this case, it is possible to operate at least one reactor in reaction mode while at least one other is operating in regeneration mode, and thus potentially ensure continuous production.

[0099] By referring to figures 1a and 1b , An embodiment with a single reactor is described.

[0100] The installation then includes a reactor 10, which can be supplied either by a reaction flow supply system 2a, or by a regeneration flow supply system 2b.

[0101] At the outlet of reactor 10 are connected both a product flow collection system 3a and a gas flow collection system from regeneration 3b.

[0102] By " power supply system And " collection system ", we mean a single course or a set of several courses.

[0103] An inlet valve system 20 and an outlet valve system 30 are provided to allow switching between the respective supply and collection systems.

[0104] During the reaction step ( figure 1a ),The inlet valve system 20 is positioned so that reactor 10 is fed by the reaction flow feed system 2a; and the outlet valve system 30 is positioned so that reactor 10 feeds the product flow collection system 3a, which directs the product flow to downstream production gas treatment units.

[0105] During the regeneration stage ( figure 1b ), The inlet valve system 20 is positioned so that reactor 10 is fed by the regeneration flow supply system 2b; and the outlet valve system 30 is positioned so that reactor 10 feeds the regeneration gas flow collection system 3b, which directs the regeneration gas flow to downstream gas treatment units.

[0106] Reactor 10 alternates between periods of production and regeneration in a sequential manner. Production is discontinuous.

[0107] By referring to figures 2a and 2b , An embodiment with two reactors is now described.

[0108] In a first configuration ( figure 2a ), The reaction step is carried out in a first reactor 10 and the regeneration step is carried out in a second reactor 11. In a second configuration ( figure 2b ), The reaction step is carried out in the second reactor 11 and the regeneration step is carried out in the first reactor 10. In this way, production is continuous.

[0109] Each reactor 10, 11 is equipped with a respective inlet valve system 20, 21 and an outlet valve system 30, 31 to allow switching between configurations. The reaction feed system 2a, the regeneration feed system 2b, the product feed system 3a, and the regeneration gas feed system 3b can be common to both reactors 10, 11, as illustrated, or separate systems can be provided for each reactor 10, 11.

[0110] By referring to the figure 3 , An embodiment with three reactors is now described.

[0111] In the illustrated configuration, the reaction stage is carried out in a first reactor 10, a second reactor 11 is on standby, and the regeneration stage is carried out in a third reactor 12. The standby stage is a state in which the reactor has been regenerated and is ready to restart the reaction. In other configurations not illustrated, the states of reactors 10, 11, and 12 are switched. In this way, continuous production can be ensured.

[0112] Each reactor 10, 11, 12 is equipped with a respective inlet valve system 20, 21, 22 and an respective outlet valve system 30, 31, 32 to allow switching between configurations. The reaction feed system 2a, the regeneration feed system 2b, the product feed system 3a, and the regeneration gas feed system 3b can be common to all three reactors 10, 11, 12 as illustrated, or separate systems can be provided for each reactor 10, 11, 12.

[0113] In the modes of embodiment of figures 1a, 1b, 2a, 2b And 3 , the flows in the reactors are directed in the same direction for fluoridation and for regeneration.

[0114] Depending on the variant, the flows in the reactors can be directed in opposite directions between fluoridation and regeneration.

[0115] Thus, in figures 4a and 4b is shown an embodiment with a single reactor 10, which is analogous to the embodiment of figures 1a and 1b , The difference is that the flows are reversed between fluorination and regeneration. For example, if the reaction feed system 2a feeds reactor 10 from the bottom, then the regeneration feed system 2b feeds reactor 10 from the top (or vice versa). Similarly, if the product feed collection system 3a is connected to the top of reactor 10, then the regeneration gas feed collection system 3b is connected to the bottom of reactor 10 (or vice versa).

[0116] Similarly, in figures 5a and 5b is shown an embodiment with two reactors 10, 11, which is analogous to the embodiment of figures 2a and 2b ,The difference is that the flows are reversed between fluorination and regeneration. For example, if the reaction feed system 2a feeds reactors 10 and 11 from the bottom, then the regeneration feed system 2b feeds reactors 10 and 11 from the top (or vice versa). Similarly, if the product feed collection system 3a is connected to the top of reactors 10 and 11, then the regeneration gas feed collection system 3b is connected to the bottom of reactors 10 and 11 (or vice versa).

[0117] Similarly, in figure 6 is shown an embodiment with three reactors 10, 11, 12, which is analogous to the embodiment of the figure 3 ,The difference is that the flows are reversed between fluorination and regeneration. For example, if the reaction feed system 2a feeds reactors 10, 11, and 12 from the bottom, then the regeneration feed system 2b feeds reactors 10, 11, and 12 from the top (or vice versa). Similarly, if the product feed collection system 3a is connected to the top of reactors 10, 11, and 12, then the regeneration gas feed collection system 3b is connected to the bottom of reactors 10, 11, and 12 (or vice versa). Multi-step processes

[0118] In some embodiments, the present disclosure provides for several successive reaction steps, preferably: first a preliminary step of manufacturing the chlorinated compound mentioned above; then the step of fluorinating the chlorinated compound to HFO-1234.

[0119] Preferably, the preliminary step is itself a fluoridation step.

[0120] In this case, this step converts a preliminary compound into the chlorinated compound mentioned above. In such a case, it should be noted that the chlorinated compound contains at least one fluorine atom (since it originates from a fluorination step) as well as at least one chlorine atom (since it is subsequently subjected to the fluorination step described above to yield HFO-1234).

[0121] THE "preliminary compound" advantageously is an organic compound (preferably with 3 carbon atoms) that includes at least two chlorine atoms (and includes more chlorine atoms than the "chlorinated compound" ) .

[0122] The preliminary compound may preferably be a propane or a propene having substituents selected from F, Cl, I and Br (preferably from F and Cl), and comprising at least two Cl substituents. A propane is particularly preferred.

[0123] It is understood that by "preliminary compound"We also hear about mixtures of compounds.

[0124] According to a preferred embodiment, the preliminary compound is HCC-240db or HCC-240aa, or a mixture of the two, and the chlorinated compound is HCFO-1233xf, to produce HFO-1234yf.

[0125] According to yet another embodiment, the preliminary compound is HCFC-243db, and the chlorinated compound is HCFO-1233xf, to produce HFO-1234yf.

[0126] According to yet another embodiment, the preliminary compound is HCO-1230xa or HCO-1230xf or a mixture of these two compounds, and the chlorinated compound is HCFO-1233xf, to produce HFO-1234yf.

[0127] The conversion of the preliminary compound into the chlorinated compound can be a direct conversion or an indirect conversion (i.e. involving an intermediate product).

[0128] It is possible to fluorinate the preliminary compound to a chlorinated compound in the liquid phase. However, it is preferable to perform fluorination in the gas phase, in the presence of a fluorination catalyst. This process can be carried out in one or more fluorination reactors in series or in parallel.

[0129] The fluorination catalyst can be of the same type as described above for the fluorination of the chlorinated compound to HFO-1234. The above description concerning catalyst activation also applies.

[0130] The gas-phase fluorination reaction of the preliminary compound to a chlorinated compound can notably be carried out: with an HF / organic molar ratio of 3:1 to 100:1, preferably 5:1 to 50:1 (the term " organic"designates the set of compounds in the reaction medium containing one or more carbon atoms); at an absolute pressure of 0.1 to 50 bar, preferably 0.3 to 15 bar; with a contact time of 1 to 100 s, preferably 1 to 50 s and more particularly 2 to 40 s (catalytic converter volume divided by the total incoming flux, adjusted for operating temperature and pressure); at a temperature (catalyst bed temperature) of 100 to 500°C, preferably 200 to 450°C, and more particularly 250 to 400°C.

[0131] The flux comprising the reaction medium may include, in addition to HF and the preliminary compound, additional compounds, notably other halohydrocarbons or halohydroolefins. The flux may, for example, already contain a fraction of HFO-1234.

[0132] According to a preferred embodiment, there is no or essentially no oxygen (and possibly no or essentially no other oxidizing agent) in the reaction medium.

[0133] Thus, the presence of oxygen or oxidizing agent is also avoided in the subsequent fluoridation step, without having to perform an intermediate separation of an oxygen or oxidizing agent stream.

[0134] The duration of the reaction step of the preliminary compound into the chlorinated compound is typically 10 to 2000 hours, preferably 50 to 500 hours and more particularly preferred 70 to 300 hours.

[0135] At the end of this reaction step, a stream of products is collected which includes in particular chlorinated compound, unreacted preliminary compound, HF, HCl, possibly HFO-1234, and possibly secondary products such as in particular 1,1,1,2,2-pentafluoropropane (HFC-245cb).

[0136] This product stream can then directly feed the fluorination step of the chlorinated compound into HFO-1234yf, described above.

[0137] Alternatively, this product stream can be separated, for example by distillation, to provide, for instance, a first stream comprising HCl and possibly HFO-1234, and a second stream comprising HF and the chlorinated compound. Distillation can, for example, be carried out at a temperature of -90 to 150°C, preferably -85 to 100°C, and at a pressure of 0.1 to 50 bar abs, preferably 0.3 to 5 bar abs.

[0138] The first stream can be directed to an acid production unit to produce HCl and HFO-1234. The HFO-1234 and intermediate products can be recovered by known means such as extraction, washing, decantation and preferably distillation.

[0139] It should be noted that at least one of the two fluorination steps described above is alternated with a reactor regeneration step using an oxidizing agent flow, as described above in connection with the fluorination of the chlorinated compound to HFO-1234. The above description therefore applies by analogy (including that relating to the different possible installations illustrated in the figures 1a to 6 ) : either to regeneration alternating with fluorination of the preliminary compound to a chlorinated compound; or to regeneration alternating with fluorination of the chlorinated compound to HFO-1234; or both to regeneration alternating with fluorination of the preliminary compound to a chlorinated compound and to regeneration alternating with fluorination of the chlorinated compound to HFO-1234.

[0140] Depending on the reaction conditions and the nature of the catalyst, the tendency of the catalyst to deactivate may be different, hence these various possible scenarios. Two-step manufacturing processes for HFO-1234yf

[0141] Various embodiments relating to the two-step production of HFO-1234yf from HCC-240db are now described (it being understood that HCC-240aa or a mixture of the two can also be used instead): a first step of converting HCC-240db into HCFO-1233xf, then a second step of converting HCFO-1233xf into HFO-1234yf, implemented in successive reactors.

[0142] By referring to the figure 7 , According to one embodiment, an installation may thus include a first fluorination reactor 40 for carrying out the preparation step of HCFO-1233xf. It is understood that a plurality of reactors, operating in series and / or in parallel, may also be used instead.

[0143] This first fluorination reactor 40 is supplied by a first feed system 39 in reaction medium (comprising HF and HCC-240db).

[0144] At the outlet of the first fluorination reactor 40, there is a product stream collection system 41, which feeds a separation unit 42. This separation unit 42 can be, in particular, a distillation unit as described above.

[0145] At the outlet of the separation unit 42, a first collection line 43 and a second collection line 44 are provided. The first collection line 43 is configured to carry a flow including HCl and HFO-1234yf, and the second collection line 44 is configured to carry a flow including HF and HCFO-1233xf.

[0146] The first collection line 43 supplies additional processing units (not shown), which may include an acid production unit, while the second collection line 44 provides recycling to at least one second gas-phase fluorination reactor 48, which is used for the fluorination of HCFO-1233xf to HFO-1234yf. This second collection line 44 can therefore also be described as a recycling line. This second reactor 48 is fed by a second reaction feed system 46, which itself is fed by the second collection line 44 on the one hand and by an HF feed system 45 on the other.

[0147] An intermediate collection system 47 is connected to the outlet of the second reactor 48. This in turn supplies the first feed system 39 with reaction medium of the first reactor 40. A supply of HCC-240db is ensured by an HCC-240db feed system 38.

[0148] Preferably, in this installation and throughout all fluoridation steps, the proportion of oxygen potentially present in the streams is less than 0.05 mol% relative to the major organic compound, preferably even less than 0.02 mol% or less than 0.01 mol%. Traces of oxygen may be present, but preferably the entire fluoridation process of HCC-240db to HFO-1234yf is carried out essentially in the absence of oxygen, or in the total absence of oxygen.

[0149] Preferably, the proportion of any oxidizing agent (such as oxygen and chlorine) that may be present in the reaction medium is less than 0.05 mol% relative to the major organic compound, preferably even less than 0.02 mol% or less than 0.01 mol%. Traces of oxidizing agent may be present, but preferably the entire process of fluorinating HCC-240db to HFO-1234yf is carried out essentially in the absence of oxidizing agent, or in the total absence of oxidizing agent.

[0150] Catalyst regeneration is planned, alternating with fluorination. This can involve either the first reactor 40, the second reactor 48, or both reactors 40 and 48. Regeneration is carried out as described above, using a flow of oxidizing agent. The means necessary for regeneration are not shown in the diagram. figure 7 but are similar to those described above.

[0151] In figure 8 A variant is illustrated. This is identical to the method of implementation of the figure 7 The difference is that, instead of a single second reactor 48, two second reactors 48a and 48b are planned. These are configured to operate alternately in fluoridation mode and regeneration mode, as described above in connection with the figures 2a and 2a .

[0152] Thus, by controlling an inlet valve system 20, 21 and an outlet valve system 30, 31, we ensure that: in one phase, one of the second reactors 48a operates in fluorination mode, i.e. is supplied by the second feed system 46 with reaction medium and supplies the intermediate collection system 47; while the other of the second reactors 48b operates in regeneration mode, i.e. is supplied by a regeneration flow feed system 49 and itself supplies a regeneration gas flow collection system 50; in another phase, the configurations of the two reactors 48a, 48b are reversed.

[0153] It should be noted that, on the figure 8 , We have depicted a regeneration occurring in the same direction as fluoridation. However, the flows can also be reversed, as described in connection with the figures 5a and 5b .

[0154] In figure 9 Another variant is illustrated. This one is identical to the method of implementation of the figure 8The difference is that not only are two secondary reactors 48a and 48b planned, but also, instead of a single primary reactor, two primary reactors 40a and 40b. These are configured to operate alternately in fluoridation and regeneration modes, as described above in connection with the figures 2a and 2b .

[0155] In the first phase, illustrated in the figure, the second reaction medium feed system 46 supplies one of the two second reactors 48a. The intermediate collection system 47 is connected to the outlet of this second reactor 48a, allowing the collection of an intermediate product stream. This stream feeds the first reaction medium feed system 39 (which also includes the HCC-240db feed system 38), which in turn feeds one of the two first reactors 40a.

[0156] The product flow collection system 41 is connected to the outlet of this first reactor 40a.

[0157] Preferably, the regeneration flow supply system 49 simultaneously supplies the other second reactor 48b. An intermediate regeneration gas flow collection system 52 is connected to the outlet of this second reactor 48b and supplies the inlet of the other first reactor 40b. The intermediate regeneration gas flow collection system 50 is connected to the outlet of this first reactor 40b.

[0158] Alternatively, an intermediate supply of additional regeneration flow can be provided between the two reactors 48b and 40b. Alternatively still, regeneration can be provided by independent flows from these two reactors 48b and 40b.

[0159] Alternatively, regeneration can be planned with flows in the opposite direction to those of fluoridation, according to the principles of figures 5a and 5b .

[0160] In a second, unillustrated phase, the fluorination and regeneration configurations are reversed between the reactors.

[0161] The transition from one configuration to another is ensured by means of a set of valves: in the illustrated example, these are inlet valves 20, 21 which are located upstream of the second reactors 48a, 48b, outlet valves which are located downstream of the first reactors 40a, 40b, and finally an HCC-240db valve 51 located at the level of the HCC-240db supply system 38.

[0162] In Figure 10 Another variant is illustrated. This one is analogous to the method of implementation of the figure 7 . In this variant, sequential regeneration with respect to fluoridation (and not simultaneous) is planned, on only one of the two reactors, namely the second reactor 48.

[0163] For this purpose, the regeneration flow supply system 49 is connected to the inlet of the second reactor 48 and the regeneration gas flow collection system 50 is connected to the outlet of the second reactor 48. An inlet valve system 20 and an outlet valve system 30 allow the second reactor 48 to be switched between fluorination and regeneration.

[0164] It should be noted that the fluxes in fluoridation and regeneration can be in the same direction or in opposite directions.

[0165] It should also be noted that the same means can also be provided to ensure regeneration at the level of the first reactor 40, either in addition to, or as a replacement for, the means of regeneration of the second reactor 48.

[0166] In figure 11 Another variant is illustrated. This one is analogous to the method of implementation of the figure 7 .In this variant, sequential regeneration with respect to fluoridation is planned (and not simultaneous), on both reactors at the same time, namely the first reactor 40 and the second reactor 48.

[0167] For this purpose, the regeneration flow supply system 49 is connected to the inlet of the second reactor 48 and the regeneration gas flow collection system 50 to the outlet of the first reactor 40. An inlet valve system 20 and an outlet valve system 30 allow the reactors 40, 48 to be switched over either into fluorination or regeneration.

[0168] It should be noted that the fluxes in fluoridation and regeneration can be in the same direction or in opposite directions.

[0169] Everything described here regarding the two-step preparation of HFO-1234yf can be analogously applied by replacing HCC-240db with another starting material (and replacing HCFO-1233xf with another chlorinated compound). Similarly, what has been described here can be applied analogously to the preparation of other HFO-1234 compounds.

[0170] Another possible implementation of this disclosure is to: on the one hand, produce chlorinated compound from the preliminary compound (e.g., HCFO-1233xf from HCC-240db or similar); and on the other hand, produce HFO-1234 from the chlorinated compound (e.g., HFO-1234yf from HCFO-1233xf); and do so independently and separately, for example, by isolating, storing and / or transporting the chlorinated compound between the two steps; and by performing the alternating regeneration according to this disclosure on the first step or the second step or both, independently. Products obtained

[0171] The consequence of the absence or near absence of oxygen during the reaction phase is a decrease in the level of impurities resulting from combustion or molecular degradation reactions. These impurities include carbon oxides or dioxides, as well as molecules containing fewer carbon atoms than the initial chlorinated product.

[0172] Thus, the process described in this disclosure yields a stream of HFO-1234 (and in particular HFO-1234yf) containing less chloromethane (HCC-40) and 1,1-difluoroethane (HFC-152a) than in the prior art. These compounds form an azeotrope with HFO-1234yf, making them difficult to purify.

[0173] The process described in this disclosure also yields a stream of HFO-1234 (and in particular HFO-1234yf) containing less fluoromethane (HFC-41) and difluoromethane (HFC-32) than in the prior art. These compounds are known to be extremely flammable.

[0174] The molar proportion of each of these compounds in the HFO-1234 stream is therefore preferably less than 100 ppm, and more particularly less than 50 ppm.

[0175] According to one embodiment of the process of this disclosure, this stream contains HFO-1234 (preferably HFO-1234yf) as well as 1 to 50 ppm of HCC-40, 1 to 50 ppm of HFC-152a, 1 to 50 ppm of HFC-41 and 1 to 50 ppm of HFC-32.

[0176] According to one embodiment, this flux is essentially devoid of, and preferably is devoid of, HCC-40.

[0177] According to one embodiment, this flux is essentially devoid of, and preferably is devoid of, HFC-152a.

[0178] According to one embodiment, this flux is essentially devoid of, and preferably is devoid of, HFC-41.

[0179] According to one embodiment, this flux is essentially devoid of, and preferably is devoid of, HFC-32.

[0180] According to one embodiment, this flux contains at least 98% of HFO-1234, preferably at least 99%, and in particular at least 99.5% or even at least 99.8% by weight.

[0181] The HFO-1234 flux considered is either the flux obtained at the outlet of the fluorination reactor of the chlorinated compound to HFO-1234 (flux taken from the product flux collection system 3a in the figures), or the flux obtained at the outlet of the separation unit (flux taken from the first collection line 43 in the figures), or the flux obtained later still after separation of HFO-1234 and hydrochloric acid.

[0182] Furthermore, the absence or near absence of oxygen also allows for the production of a higher purity hydrochloric acid stream, facilitating its valorization. Thus, the hydrochloric acid stream recovered after separation from HFO-1234 is preferably free (or essentially free) of trifluoroacetic acid, COF2, or COFCl. EXAMPLES

[0183] The following examples illustrate the invention without limiting it.

[0184] We have a gas phase fluorination reactor equipped with an HF feed, a fresh organic product feed, a feed available for co-feeding another gaseous compound and a feed line from the recycling of unconverted reagents.

[0185] The gas stream from this reactor is directed to a cooled, double-jacketed duct that cools and partially condenses the reaction products before they are introduced into the distillation column. The partially condensed stream is then fed into a 1.5 m high distillation column packed with Sulzer-type metal packing, which facilitates heat exchange between the rising gas stream and the descending liquid reflux. The distillation column is equipped with a boiler at the bottom and a condenser at the top. This separation unit separates the top stream, which consists mainly of the desired product (HFO-1234yf) and the byproduct HCl. Varying amounts of the byproduct HFC-245cb are also present. The bottom stream consists mainly of HF and unconverted reactant (HCFO-1233xf), as well as the byproduct HFC-245cb resulting from the addition of HF to HFO-1234yf.This stream at the bottom of the column is then recycled to the gas-phase reactor. Traces of impurities are present in each of the streams.

[0186] 180 mL of chromium-based bulk catalyst are introduced into the Inconel reactor. It is first subjected to a drying period under 50 L / h of nitrogen at atmospheric pressure and 275°C overnight. Then, while maintaining the nitrogen supply and still at 275°C, a flow of HF is gradually added until a flow rate of 1 mol / h is achieved. This treatment is maintained overnight. The nitrogen is then switched off and the furnace temperature increased to 350°C. The treatment under pure HF is also maintained overnight. Finally, a treatment under 5 L / h of air is applied for at least 24 h.

[0187] Following the catalyst activation treatment, HCFO-1233xf and HF reagents are introduced into the recycling loop to fill this section of the system, maintaining a molar ratio of 25 between hydrofluoric acid and organic acid. Start-up is initiated by feeding the liquid from the recycling loop to the gas-phase reactor (a preheater ensures the prior vaporization of the reagents). The system then gradually equilibrates, with unconverted reagents being recycled, products formed being removed and collected from the system, and fresh reagents being continuously fed to precisely compensate for the amount of product removed. The liquid level in the distillation column thus remains constant.

[0188] The catalyst's conversion rate changes over time and gradually decreases. When conversion falls below 50%, the catalyst undergoes an air regeneration treatment. This treatment fully restores the catalyst's initial activity.

[0189] The conversion is calculated from the molar content of HCFO-1233xf measured at the reactor inlet (sum of recycling and fresh organic streams) and the HCFO-1233xf content measured at the reactor outlet. Example 1 - catalytic results in the presence of air

[0190] An experiment was conducted under the following operating conditions: the catalyst was freshly regenerated, the molar ratio of HF to organics was 25, the gas-phase contact time was 15 seconds, the temperature was 350°C, and 10 mol% oxygen was added relative to the sum of the introduced organics. The conversion of HCFO-1233xf over time is given in Table 1 below. During this experiment, the gas stream exiting the top of the distillation column was analyzed by gas chromatography. The analysis is reported in Table 2 below (value as % GC area). Example 2 - catalytic results without air

[0191] The implementation method from Example 1 is repeated, but without the addition of further oxygen to the gas phase. The results obtained for the conversion over time are given in Table 1 below. The analysis of the gas flow exiting the distillation column is reported in Table 2 below (value as a percentage of GC area). Carbon oxides and C1 and C2 impurities have significantly decreased. The purity of the sum of the desired product HFO-1234yf and the recyclable by-product HFC-245cb increases. Table 1 Example 1 Example 2 Time (h) Conversion of HCFO-1233xf (%) Time (h) Conversion of HCFO-1233xf (%) 4 78,6 15 77,6 8 77,4 19 78,5 12 76,3 24 77,8 16 77,2 27 78,3 21 78,7 31 76,9 28 76,2 35 74,5 32 76,8 39 72,8 36 76,9 43 71,7 40 75,9 48 72,7 48 75,6 51 72,9 52 73,4 55 73,2 60 73,4 59 73,6 64 72,1 63 74,1 71 70,2 71 70,9 80 67,8 82 70,9 84 65,0 86 69,4 Table 2 Product detected Example 1 Example 2 CO 3,2 0,22 CO2 1,39 0,04 F23 0,13 Nd F41 0,06 Nd F32 0,03 Nd F125 0,17 Nd Trifluoropropyne 0,08 0,02 F143a 0,36 0,04 F1234yf + 245cb 93,19 98,03 F40 0,26 Nd F152a 0,02 Nd F1234zeE 1,10 1,62 F 1233xf 0,01 Nd Nd: not detected

Claims

1. Composition comprising tetrafluoropropene, characterized in that it comprises, in molar proportions, from 1 to 50 ppm of HCC-40, from 1 to 50 ppm of HFC-152a, from 1 to 50 ppm of HFC-41 and from 1 to 50 ppm of HFC-32.