Method for purifying chlorotrifluoroethylene through extraction and distillation

Abstract

The present invention relates to a process for purifying chlorotrifluoroethylene (CTFE) from a first composition comprising chlorotrifluoroethylene and 1, 1, 2-trifluoroethane (143), said process comprising the steps of: a) extractive distillation of said first composition in the presence of at least one organic extractant to form i) a second composition comprising said organic extractant and 1, 1, 2-trifluoroethane; and ii) a first stream comprising chlorotrifluoroethylene, and b) recovering and separating the second composition to form a second stream comprising the organic extractant and a third stream comprising 1, 1, 2-trifluoroethane; preferably, the second stream is recycled to step a).

Description

Technical Field

[0001] The present invention relates to methods for producing and purifying hydrofluoroolefins. In particular, the present invention relates to a method for purifying chlorotrifluoroethylene. The present invention also relates to a method for producing trifluoroethylene (VF3) by hydrodechlorination of chlorotrifluoroethylene. Background Art

[0002] Fluoroolefins, such as VF3, are known and are used as monomers or comonomers for manufacturing fluorohydrocarbon polymers having notable characteristics, in particular excellent chemical resistance and good heat resistance.

[0003] Trifluoroethylene is a gas under standard pressure and temperature conditions. The main risks associated with the use of this product relate to its flammability, its tendency to self-polymerize when unstable, its explosiveness due to its chemical instability, and its supposed sensitivity to peroxidation similar to other haloolefins. Trifluoroethylene has the specific characteristic of being extremely flammable, with a lower explosive limit (LEL) of about 10% and an upper explosive limit (UEL) of about 30%. However, the main hazard is related to the tendency of VF3 to decompose violently and explosively under certain pressure conditions in the presence of energy, even in the absence of oxygen.

[0004] Given the above main risks, the synthesis and storage of VF3 pose specific problems, and strict safety rules are imposed throughout these processes. Known routes for preparing trifluoroethylene use chlorotrifluoroethylene (CTFE) and hydrogen as starting materials in the presence of a catalyst and in the gas phase. A method for producing trifluoroethylene by hydrodechlorination of CTFE in the gas phase and in the presence of a catalyst based on a metal from Group VIII at atmospheric pressure and relatively low temperature is known from WO 2013 / 128102. It is known from the patent application PCT / FR2022 / 051054 that the reaction produces a reaction stream that contains, in addition to trifluoroethylene and unreacted chlorotrifluoroethylene, 1,1,2-trifluoroethane. Chlorotrifluoroethylene and 1,1,2-trifluoroethane form an azeotrope under certain conditions. Therefore, it proves to be complex to recover chlorotrifluoroethylene of high purity for recycling. Thus, a method for purifying chlorotrifluoroethylene is needed. Summary of the Invention

[0005] According to a first aspect, the present invention provides a method for purifying chlorotrifluoroethylene (CTFE) from a first composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane (143), the method comprising the following steps:

[0006] a) Extractive distilling the first composition in the presence of at least one organic extractant to form

[0007] i) a second composition comprising the organic extractant and 1,1,2-trifluoroethane; and

[0008] ii) a first stream comprising chlorotrifluoroethylene; and

[0009] b) recovering and separating said second composition to form a second stream comprising said organic extractant and a third stream comprising 1,1,2-trifluoroethane; preferably, recycling said second stream to step a).

[0010] According to a preferred embodiment, the organic extractant has a flash point above 13 °C.

[0011] According to a preferred embodiment, the organic extractant is a compound comprising from 2 to 12 carbon atoms.

[0012] According to a preferred embodiment, the organic extractant has a molecular weight of less than 200 g.mol -1 -1.

[0013] According to a preferred embodiment, the organic extractant has a separation factor S 1,2 which is given by the formula S 1,2 = (γ 1,S ) / (γ 2,S ) where:[[]]

[0014] γ 1,S represents the activity coefficient of chlorotrifluoroethylene in the organic extractant at infinite dilution,

[0015] γ 2,S represents the activity coefficient of 1,1,2-trifluoroethane in the organic extractant at infinite dilution,

[0016] Advantageously, the separation factor S 1,2 is greater than or equal to 2.1, preferably greater than or equal to 2.2, more preferably greater than or equal to 2.3, especially greater than or equal to 2.4, and more especially greater than or equal to 2.5.

[0017] According to a preferred embodiment, the organic extractant has an absorption capacity C 2,S which is given by the formula C 2,S = 1 / (γ 2,S ) where γ 2,S represents the activity coefficient of 1,1,2-trifluoroethane in the organic extractant at infinite dilution.

[0018] According to a preferred embodiment, the first composition is an azeotropic or near-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.

[0019] According to a preferred embodiment, the organic extractant has a melting point below 0 °C.

[0020] According to a preferred embodiment, step b) is carried out at a pressure of 1 - 10 bara, preferably 1 - 7 bara.

[0021] According to a preferred embodiment, the organic extractant is selected from β-propiolactone, γ-butyrolactone, 1-hydroxy-2-propanone, acetonylacetone, trimethyl phosphate, acetylacetone, propylene carbonate, dimethyl malonate, ethyl acetoacetate, 1,2-ethylene glycol diacetate, (ethylene) glycol, ethyl oxalate, 1-methyl ethyl 3-oxobutyrate, ethylene glycol monomethyl ether acetate, dimethyl maleate, triethyl phosphate, triethylene glycol, diethyl malonate, furfural, diethylene glycol, tert-butyl acetoacetate, ethyl succinate, 1,3-propanediol, cyclopentanone, propylene glycol, 1-cyclopropyl ethanone, 2-methoxyethanol, 2,3-pentanedione, tripropylene glycol, cyclohexanone, diethyl carbonate, 1,3-butanediol, 3-methoxy-1-butanol, 4-methyl-3-penten-2-one, 1-methoxy-2-propanol, phenyl acetate, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 2,3-hexanedione, 3,4-hexanedione, citral, 1,5-pentanediol, diethylene glycol monobutyl ether, 4-phenyl-2-butanone, ethanol, n-butyl acetate, 4-methyl-2-pentanone, 3-hexanone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethylcyclohexanone and ethyl benzoate.

[0022] According to another aspect, the present invention provides a process for producing trifluoroethylene in a reactor equipped with a fixed catalytic bed containing a catalyst, the process comprising the following steps:

[0023] A’) Reacting chlorotrifluoroethylene with hydrogen in the presence of a catalyst and in the gas phase to produce a stream A containing trifluoroethylene, unreacted chlorotrifluoroethylene and 1,1,2-trifluoroethane;

[0024] B’) Purifying the stream A to form a stream B1 containing trifluoroethylene and a stream B2 containing chlorotrifluoroethylene and 1,1,2-trifluoroethane,

[0025] C’) Using the stream B2 in the purification process according to the present invention. Detailed Description

[0026] Process for purifying CTFE

[0027] According to a first aspect of the present invention, there is provided a method for purifying chlorotrifluoroethylene (CTFE). In particular, the present invention allows the separation of chlorotrifluoroethylene from 1,1,2-trifluoroethane (143). A mixture of chlorotrifluoroethylene and 1,1,2-trifluoroethane is obtained during the process for producing trifluoroethylene. Chlorotrifluoroethylene and 1,1,2-trifluoroethane are usually obtained in the form of an azeotropic composition depending on the operating conditions. In order to recover chlorotrifluoroethylene, the components of the azeotropic composition must be separated. The applicant has surprisingly found an organic extractant capable of separating chlorotrifluoroethylene and 1,1,2-trifluoroethane by extractive distillation.

[0028] The purification method comprises the following steps:

[0029] a) subjecting the first composition to extractive distillation in the presence of at least one organic extractant to form

[0030] i) a second composition comprising the organic extractant and 1,1,2-trifluoroethane; and

[0031] ii) a first stream comprising chlorotrifluoroethylene;

[0032] b) recovering and separating the second composition to form a second stream comprising the organic extractant and a third stream comprising 1,1,2-trifluoroethane; preferably, recycling the second stream to step a).

[0033] According to a preferred embodiment, the first composition comprises at least 50% by weight of chlorotrifluoroethylene, advantageously at least 60% by weight of chlorotrifluoroethylene, preferably at least 70% by weight of chlorotrifluoroethylene, especially at least 80% by weight of chlorotrifluoroethylene, based on the total weight of the first composition.

[0034] According to a preferred embodiment, the first composition comprises not more than 30% by weight of 1,1,2-trifluoroethane, advantageously not more than 25% by weight of 1,1,2-trifluoroethane, preferably not more than 20% by weight of 1,1,2-trifluoroethane, especially not more than 15% by weight of 1,1,2-trifluoroethane, based on the total weight of the first composition.

[0035] According to a preferred embodiment, the first composition is an azeotropic or pseudo-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.

[0036] Advantageously, the first composition is azeotropic and comprises from 80% to 99.99% by weight of chlorotrifluoroethylene, based on the total weight of the composition. Preferably, the first composition is azeotropic and comprises from 85% to 99.99% by weight of chlorotrifluoroethylene, based on the total weight of the composition. In particular, the first composition is azeotropic and comprises from 90% to 99.99% by weight of chlorotrifluoroethylene, based on the total weight of the composition.

[0037] Advantageously, the first composition is azeotropic and comprises from 0.01% to 20% by weight of 1,1,2-trifluoroethane, based on the total weight of the composition. Preferably, the first composition is azeotropic and comprises from 0.01% to 15% by weight of 1,1,2-trifluoroethane, based on the total weight of the composition. In particular, the first composition is azeotropic and comprises from 0.01% to 10% by weight of 1,1,2-trifluoroethane, based on the total weight of the composition.

[0038] Preferably, the first composition is azeotropic and has a boiling point between -40°C and 40°C, more preferably between -35°C and 25°C. In particular, the first composition is azeotropic and has a boiling point between -40°C and 40°C at a pressure between 0.5 bara and 8 bara. More particularly, the first composition is azeotropic and has a boiling point between -35°C and 25°C at a pressure between 1 bara and 6 bara.

[0039] Accordingly, the first composition is azeotropic and may comprise from 80% to 99.99% by weight of chlorotrifluoroethylene and from 0.01% to 20% by weight of 1,1,2-trifluoroethane, based on the total weight of the composition, and has a boiling point between -40°C and 40°C at a pressure between 0.5 bara and 8 bara. Advantageously, the first composition is azeotropic and comprises from 85% to 99.99% by weight of chlorotrifluoroethylene and from 0.01% to 15% by weight of 1,1,2-trifluoroethane; and has a boiling point between -40°C and 40°C at a pressure between 0.5 bara and 8 bara. More particularly, the first composition is azeotropic and comprises from 90% to 99.99% by weight of chlorotrifluoroethylene and from 0.01% to 10% by weight of 1,1,2-trifluoroethane, and has a boiling point between -30°C and 25°C at a pressure between 1 bara and 6 bara.

[0040] According to a preferred embodiment, the organic extractant is a solvent selected from hydrocarbons, halogenated hydrocarbons, alcohols, ketones, amines, esters, ethers, aldehydes, acids, nitriles, carbonates, thioalkyls, amides, heterocycles, sulfates and phosphates. Advantageously, the organic extractant is a solvent selected from alcohols, ketones, phosphates, esters and ethers.

[0041] As used herein, the term "hydrocarbon" refers to straight-chain or branched C1-C 20 alkanes, C3-C 20 cycloalkanes, C5-C 20 alkenes, C5-C 20 cycloalkenes or C6-C 18 aromatic compounds. For example, the term "alkane" refers to a compound of the formula C n H 2n+2 where n is between 1 and 20. The term "C1-C 20 alkane" includes, for example, pentane, hexane, heptane, octane, nonane and decane, or their isomers. The term "C5-C 20 alkene" refers to a hydrocarbon-based compound containing one or more carbon-carbon double bonds and containing 5 to 20 carbon atoms. The term "C3-C 20 cycloalkane" refers to a saturated hydrocarbon-based ring containing 3 to 20 carbon atoms. The term "C6-C 18 aryl" refers to a cyclic and aromatic hydrocarbon-based compound containing 6 to 18 carbon atoms. The term "C5-C 20 cycloalkene" refers to a cyclic hydrocarbon-based compound containing 5 to 20 carbon atoms and containing one or more carbon-carbon double bonds.

[0042] The term "alkyl" denotes a monovalent group derived from a straight-chain or branched alkane and containing 1 to 20 carbon atoms. The term "cycloalkyl" denotes a monovalent group derived from a cycloalkane and containing 3 to 20 carbon atoms. The term "aryl" denotes a monovalent group derived from an aromatic hydrocarbon and containing 6 to 18 carbon atoms. The term "alkenyl" denotes a monovalent group having 2 to 20 carbon atoms and at least one carbon-carbon double bond. The term "alkynyl" denotes a monovalent group having 2 to 20 carbon atoms and at least one carbon-carbon triple bond. The term "halogen" refers to a -F, -Cl, -Br or -I group. The term "cycloalkenyl" refers to a monovalent group derived from a cycloalkene containing 3 to 20 carbon atoms. C1-C 20 alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl, C3-C 20 cycloalkyl, C3-C 20 cycloalkenyl and C6-C 18 aryl substituents may optionally be substituted with one or more -OH, halogen, -NR a C(O)R b 、-C(O)NR aR b 、 -CN, -NO2, -NR a R b 、 -OR a 、 -SR a 、 CO2R a 、 -OC(O)OR a 、 -OC(O)R a 、 -C(O)H or -C(O)R a substituted by substituents, where R a and R b are each independently hydrogen, unsubstituted C1-C 20 alkyl, unsubstituted C2-C 20 alkenyl, unsubstituted C2-C 20 alkynyl, unsubstituted C3-C 20 cycloalkyl, unsubstituted C3-C 20 cycloalkenyl or unsubstituted C6-C 18 aryl. In the substituent -NR a R b R a and R b may form a saturated or unsaturated, aromatic or non-aromatic 5- to 10-membered heterocycle with the nitrogen atom to which they are attached.

[0043] The term "halohydrocarbon" refers to a compound of the formula R a X, where R a is selected from C1-C 20 alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl, C3-C 20 cycloalkyl, C3-C 20 cycloalkenyl and C6-C 18 aryl, and X represents a chlorine, fluorine, bromine or iodine atom. The C1-C 20 alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl, C3-C 20 cycloalkyl, C3-C 20 cycloalkenyl and C6-C 18 aryl substituents may be unsubstituted or substituted by one or more -OH, halogen, -NR a C(O)R b 、 C(O)NR a R b -CN, -NO2, -NR a R b 、 -OR a 、 -SR a 、 -CO2R a 、 -OC(O)ORa 、 -OC(O)R a 、 -C(O)H, -C(O)R a substituted with substituents, where R a and R b are as defined above.

[0044] The term "alcohol" refers to a hydrocarbon or halogenated hydrocarbon as defined above in which at least one hydrogen atom is replaced by a hydroxyl group -OH.

[0045] The term "ketone" refers to a hydrocarbon containing at least one or more carbonyl functional groups R c -C(O)-R d where R c and R d are independently of each other C1-C 20 alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl, C3-C 20 cycloalkyl, C3-C 20 cycloalkenyl or C6-C 18 aryl, and may be unsubstituted or substituted by one or more substituents selected from -OH, halogen, -NR a C(O)R b 、 -C(O)NR a R b 、 -CN, -NO2, -NR a R b 、 -OR a 、 -SR a 、 -CO2R a 、 -OC(O)OR a 、 -OC(O)R a 、 -C(O)H and -C(O)R a where R a and R b are as defined above, R c and R d may be linked together to form a 4- to 10-membered and preferably 4- to 7-membered cyclic ketone with the carbonyl group to which they are attached. The cyclic ketone may also contain one or more carbon-carbon double bonds. The cyclic ketone may also be unsubstituted or substituted by one or more substituents as defined above.

[0046] The term "amine" refers to a hydrocarbon containing at least one or more amine functional groups -NR c R d where R c and R d are as defined above, R c and R d may be linked together to form a 4- to 10-membered aromatic or non-aromatic heterocycle with the nitrogen atom to which they are attached.

[0047] The term "ester" refers to a compound of the formula R c -C(O)-O-R d wherein R c and R d are as defined above, and R c and R d may be linked together to form a ring containing 4 to 20 carbon atoms with the ester group.

[0048] The term "ether" refers to a compound of the formula R c -O-R d wherein R c and R d are as defined above, and R c and R d may be linked together to form a heterocyclic ring containing 4 to 20 carbon atoms with the oxygen atom to which they are attached.

[0049] The term "aldehyde" refers to a compound containing at least one or more -C(O)-H functional groups.

[0050] The term "nitrile" refers to a compound containing at least one or more -CN functional groups.

[0051] The term "carbonate" refers to a compound of the formula R c -O-C(O)-O-R d wherein R c and R d are as defined above.

[0052] The term "thioalkyl" refers to a compound of the formula R c SR d wherein R c and R d are as defined above.

[0053] The term "phosphate ester" refers to a compound of the formula P(OR c )3, wherein R c is independently as defined above for each substituent.

[0054] The term "sulfate ester" refers to a compound of the formula SO2(OR c )2, wherein R c is independently as defined above for each substituent.

[0055] The term "acid" refers to a compound of the formula R c -CO2H, wherein R c is as defined above.

[0056] The term "amide" relates to a compound of the formula R c C(O)NRe R d compounds, wherein R c and R d are as defined above, and R e has the same definition as R c and R c and R d may be linked together with the amide group -C(O)N- to which they are attached to form a 4- to 10-membered and preferably 4- to 7-membered cyclic amide. The cyclic amide may also contain one or more carbon-carbon double bonds. The cyclic amide may also be unsubstituted or substituted with one or more substituents as defined above.

[0057] The term "heterocycle" means a 4- to 10-membered carbocyclic ring in which at least one ring member is a heteroatom selected from O, S, P, and N. The heterocycle may contain one or more carbon-carbon double bonds or one or more carbon-heteroatom double bonds or one or more heteroatom-heteroatom double bonds. Preferably, the heterocycle may contain 1, 2, 3, 4, or 5 heteroatoms as defined above. In particular, the heterocycle may contain 1, 2, or 3 heteroatoms selected from oxygen, nitrogen, and sulfur. Preferably, the heterocycle may be a 4- to 6-membered carbocyclic ring in which 1, 2, or 3 ring members are heteroatoms selected from O and N. The heterocycle may be unsubstituted or substituted with one or more substituents selected from -OH, halogen, -NR a C(O)R b 、-C(O)NR a R b 、-CN、-NO2、-NR a R b 、-OR a 、-SR a 、-CO2R a 、-OC(O)OR a 、-OC(O)R a 、-C(O)H and -C(O)R a wherein R a and R b are as defined above.

[0058] The term "azeotropic composition" means a liquid mixture of two or more compounds that behaves like a single substance and that boils at a fixed temperature, maintaining the same composition in the liquid phase as in the gas phase. The term "quasi-azeotropic composition" means a liquid mixture of two or more compounds that has a constant boiling point or a tendency not to fractionate when subjected to boiling or evaporation.

[0059] The term "organic extractant" refers to a compound containing at least one carbon atom.

[0060] According to a preferred embodiment, the organic extractant is a compound containing 2 to 12 carbon atoms, advantageously 2 to 11 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 9 carbon atoms, especially 2 to 8 carbon atoms.

[0061] The organic extractant preferably has a molecular weight of less than 200 g.mol -1 , advantageously less than 190 g.mol -1 , preferably less than 180 g.mol -1 , more preferably less than 170 g.mol -1 , especially less than 160 g.mol -1 .

[0062] According to a preferred embodiment, the melting point of the organic extractant is below 50 °C, advantageously below 40 °C, preferably below 30 °C, more preferably below 20 °C, especially below 10 °C, more especially below 0 °C.

[0063] According to a preferred embodiment, the organic extractant has a separation factor S greater than or equal to 2.0 1,2 , the separation factor being calculated by the formula S 1,2 = (γ 1,S ) / (γ 2,S ), where:

[0064] γ 1,S represents the activity coefficient of chlorotrifluoroethylene in the organic extractant at infinite dilution,

[0065] γ 2,S represents the activity coefficient of 1,1,2-trifluoroethane in the organic extractant at infinite dilution,

[0066] Advantageously, the separation factor S 1,2 is greater than or equal to 2.1, preferably greater than or equal to 2.2, more preferably greater than or equal to 2.3, especially greater than or equal to 2.4, more especially greater than or equal to 2.5.

[0067] According to a preferred embodiment, the organic extractant is selected from ethyl chloroacetate, ethyl mercaptoacetate, phenyl acetate, n-butyl acetate, β-phenethyl acetate, sec-butyl acetate, methyl dichloroacetate, isoamyl acetate, n-amyl acetate, propargyl alcohol, 3-butyn-1-ol, 2-butyn-1-ol, 3-butyn-2-ol, ethanol, 2-propanol, α-methylcyclopropanemethanol, glyceraldehyde, 2,4-hexadienal, 3-phenyl-2-propenal, benzaldehyde, 4-methylbenzaldehyde, hexanal, heptanal, 3-butenoic acid, propionic acid, 4-pentenoic acid, 5-hexenoic acid, isobutyric acid, butyric acid, 4-ethylnitrobenzene, 1,4-dimethyl-2-nitrobenzene, dimethylformamide, N,N-dimethylacetamide, methylformamide, N,N-dimethylpropanamide, N,N-dimethylbutyramide, N-butylethylamide, N-nitrosodimethylamine, 1-methylimidazole, N-(2-aminoethyl)-1,2-ethanediamine, tetramethylurea, 3,3'-iminodipropylamine, 2,2-diethoxyethylamine, tetraethylenepentamine, furfurylamine, N,N-dimethyl-1,3-benzenediamine, 4-morpholinopropylamine, 3-chloroaniline, acetic anhydride, propionic anhydride, isobutyric anhydride, butyric anhydride, nitromethane, nitroethane, 1,3-dioxane, 4-methyl-1,3-dioxane, β-propiolactone, γ-butyrolactone, dimethyl malonate, ethyl acetoacetate, 1,2-ethylene diacetate, methyl cyanoacetate, 2-propenyl 3-oxobutanoate, dimethyl glutarate, ethyl oxalate, methyl ethyl 3-oxobutanoate, ethylene glycol monomethyl ether acetate, dimethyl maleate, ethyl cyanoacetate, ethyl methyl succinate, diethyl malonate, methyl 2-hydroxypropionate, tert-butyl acetoacetate, ethyl succinate, ethyl chloroacetate, allylidene diacetate, diethyl adipate, ethyl phenylacetate, benzyl acetate, dibutyl (Z)-2-butenedioate, 2-methylpropyl acetate, 2-propenyl butyrate, methyl benzoate, tetramethyl silicate, butyl 2-acrylate, 2-methylpropyl acrylate, amyl formate, cyclohexyl acetate, ethyl 3-methylbutyrate, ethyl benzoate, methyl hexanoate, diethylene glycol dimethyl ether, bis(2-chloroethyl) ether, crotyl glycol ether, ethylene glycol monobenzyl ether, diethylene glycol monobutyl ether, 2-chloroethyl ethyl ether, diethylene glycol dibutyl ether, benzyl methyl ether, isoamyl formate, 2,5,8,11-tetraoxadodecane, methyl thiocyanate, ethyl thiocyanate, ethyl isothiocyanate, 1-hydroxy-2-propanone, acetonylacetone, acetylacetone, 2-oxepanone, chloroacetone, N-methyl-2-pyrrolidone, 5-ethyldihydro-2(3H)-furanone, 1-bromo-2-propanone, 5-methyl-2-(3H)-furanone, 2-cyclohexen-1-one, 1-(4-methoxyphenyl)-2-propanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, 4-methylene-2-oxetanone, 1-cyclopropylethanone, 1-phenyl-2-propanone, 2,3-Pentanedione, isophorone, cyclohexanone, 2-methylcyclopentanone, 4-methyl-3-penten-2-one, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 2,3-hexanedione, 3,4-hexanedione, 4-phenyl-2-butanone, 2-hexanone, 1-(3,4-dimethylphenyl)ethanone, 4-methyl-2-pentanone, 3-hexanone, 4-fluorobenzophenone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethylcyclohexanone, 2-heptanone, 2,4-dimethyl-3-pentanone, 2,2-dimethyl-3-pentanone, 3-heptanone, 4-heptanone, 2-octanone, 2-methyl-1-phenyl-1-propanone, (ethylthio)acetic acid, 1,3-propanedithiol, 1,2-ethanedithiol, 1,3-dithiolane, 1,4-butanedithiol, glutaronitrile, 2-methylglutaronitrile, hydroxyacetonitrile, 3-chloropropionitrile, 2-hydroxypropionitrile, dimethylaminopropionitrile, (E)-2-butenenitrile, 3-butenenitrile, butyronitrile, 2-hydroxy-2-methylpropionitrile, valeronitrile, phenylacetonitrile, hexanenitrile, phenylpropionitrile, benzonitrile, heptanenitrile, 3-methylbenzonitrile, 2-methylbenzonitrile, octanenitrile, 3-fluorobenzonitrile, nonanenitrile, trimethyl phosphate, propylene carbonate, tetramethyl orthocarbonate, triethyl phosphate, dimethyl sulfate, tris(2-butoxyethyl) phosphate, diethyl sulfate, diethyl carbonate, 2-(2-ethoxyethoxy)ethyl acetate, 2-ethoxyethyl acetate, 2-(2-butoxyethoxy)ethyl acetate, 2-butoxyethyl acetate, furfural, diethylene glycol monoethyl ether, 2-methoxyethanol, 2-(2-butoxyethoxy)ethoxyethanol, 3-methoxy-1-butanol, 1-methoxy-2-propanol, ethoxyethanol, 2-furanmethanol, tetrahydro-2H-pyran-2-methanol, 3-methoxyphenol, 1-propoxy-2-propanol, difluoroacetic acid, 2-fluoroethanol, 2-bromoethyl acetate, 2-chloroethanol, chlorosulfonic acid, 2,2-difluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 2-chloropropionic acid, 1-chloro-2-methyl-2-propanol, 2,2'-oxybis(2,1-ethanediol) bisethanol, 2,2'-bis(methylimino)ethanol, 2-(2-methoxyethoxy)ethanol, 2-bromoethanol, 3-chloro-1-propanol, 1,3-dichloro-2-propanol, ethylidene cyanohydrin, 2-nitroethanol, 2-nitro-1-butanol, 2-amino-1-butanol, 3-pyridinemethanol, 2-(ethylamino)ethanol, 2-(dimethylamino)ethanol, 3-(dimethylamino)-1-propanol, 1-(dimethylamino)-2-propanol, divinyl sulfone, 2,2'-thiobisethanol, 2-(ethylthio)ethanol, (ethylene) glycol, triethylene glycol, diethylene glycol, 1,3-propanediol, propylene glycol, tripropylene glycol, 1,5-pentanediol, 2-methyl-2,4-Pentanediol, 2-ethoxyethyl acrylate, ethyl butyrate, propyl propionate, ethyl valerate, n-butyl propionate, n-propyl butyrate, isobutyl propionate, isopropyl butyrate, diacetoxydimethylsilane, (3-chloropropyl)trimethoxysilane, triethoxysilane, methylhydrazine, pyridazine, 2-methylpyridine 1-oxide, 1-piperidinecarboxaldehyde, (chloromethyl)oxirane, dimethylcarbamoyl chloride, 4-pyridinecarboxaldehyde, 2-nitropropane, 1-acetylpiperidine, 1-nitropropane, 4-methoxybenzaldehyde, 1,1'-oxybis(2-ethoxy)ethane, trimethyl phosphite, tetrahydrofurfuryl alcohol, 4-(2-hydroxyethyl)morpholine, 1,3-butanediol, 1,2-ethanediol dinitrate, 3-oxiranyl-7-oxabicyclo[4.1.0]heptane, dibutyl oxalate, morpholine, ((1,1-dimethylethoxy)methyl)oxirane, 1,4-oxathiane, dimethoxytetrahydrofuran, triethyl orthoformate, 3-chloropropionyl chloride, citral, pyrrole, allyl acrylate, 3-methoxyaniline, 2-methylpyrazine, methylaminoacetaldehyde dimethyl acetal, (c-chloroethoxy)ethane, butyl lactate, nitrocyclohexane, 4-fluorobenzaldehyde, methoxyacetyl chloride, 2-propen-1-ol, 2-ethylbutyraldehyde, 2-fluorobenzaldehyde, 1,6-heptadiyne, 2-nitrotoluene, methyl 2-chloroacrylate, 2-furancarbonyl chloride, salicylaldehyde, 4,5-dihydro-2-methylthiazole, 1,4-difluoro-2-nitrobenzene, benzisoxazole, thiazole, m-fluoroaniline, 1,4-dichloro-2-butyne, aniline, p-fluoroaniline, 1-methyl-1H-pyrrole, pyridine, 2,4-dimethylbenzaldehyde, methacryl alcohol, 2,3-dichlorobutane, chloroacetyl chloride, 1,3-dichloropropane, 1,5-dichloropentane, 2,6-dimethylmorpholine, myristicin, 2,3-dimethylpyrazine, 2-butanone oxime, 2-ethylnitrobenzene.,

[0068] Advantageously, the organic extractant is selected from phenyl acetate, n-butyl acetate, β-phenethyl acetate, sec-butyl acetate, isoamyl acetate, n-amyl acetate, ethanol, 2-propanol, α-methylcyclopropanemethanol, dimethylformamide, N,N-dimethylacetamide, methylformamide, N,N-dimethylpropanamide, N,N-dimethylbutyramide, N-butylacetamide, 1,3-dioxane, 4-methyl-1,3-dioxane, β-propiolactone, γ-butyrolactone, dimethyl malonate, ethyl acetoacetate, 1,2-ethylene diacetate, methyl cyanoacetate, 2-propenyl 3-oxobutanoate, dimethyl glutarate, ethyl oxalate, ethyl methyl 3-oxobutanoate, ethylene glycol monomethyl ether acetate, dimethyl maleate, ethyl cyanoacetate, ethyl methyl succinate, diethyl malonate, methyl 2-hydroxypropanoate, tert-butyl acetoacetate, ethyl succinate, ethyl chloroacetate, allylidene diacetate, diethyl adipate, ethyl phenylacetate, benzyl acetate, dibutyl (Z)-2-butenedioate, 2-methylpropyl acetate, 2-propenyl butanoate, methyl benzoate, tetramethyl silicate, butyl 2-propenoate, 2-methylpropyl acrylate, amyl formate, cyclohexyl acetate, ethyl 3-methylbutanoate, ethyl benzoate, methyl hexanoate, diethylene glycol dimethyl ether, bis(2-chloroethyl) ether, crotyl glycol ether, ethylene glycol monobutyl ether, 2-chloroethyl ethyl ether, diethylene glycol dibutyl ether, benzyl methyl ether, isoamyl formate, 2,5,8,11-tetraoxadodecane, acetonylacetone, acetylacetone, 2-oxepanone, chloroacetone, N-methyl-2-pyrrolidone, 5-ethyldihydro-2(3H)-furanone, 1-bromo-2-propanone, 5-methyl-2(3H)-furanone, 2-cyclohexen-1-one, 1-(4-methoxyphenyl)-2-propanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, 4-methylene-2-oxetanone, 1-cyclopropylethanone, 1-phenyl-2-propanone, 2,3-pentanedione, isophorone, cyclohexanone, 2-methylcyclopentanone, 4-methyl-3-penten-2-one, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 2,3-hexanedione, 3,4-hexanedione, 4-phenyl-2-butanone, 2-hexanone, 1-(3,4-dimethylphenyl)ethanone, 4-methyl-2-pentanone, 3-hexanone, 4-fluoroacetophenone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethylcyclohexanone, 2-heptanone, 2,4-dimethyl-3-pentanone, 2,2-dimethyl-3-pentanone, 3-heptanone, 4-heptanone, 2-octanone, 2-methyl-1-phenyl-1-propanone, glutaronitrile, 2-methylglutaronitrile, hydroxyacetonitrile, 2-hydroxypropanenitrile, dimethylaminopropionitrile, (E)-2-butenenitrile, 3-butenenitrile, butyronitrile, 2-hydroxy-2-methylpropanenitrile, valeronitrile, phenylacetonitrile, hexanenitrile, heptanenitrile, octanenitrile, 3-fluorobenzonitrile, nonanenitrile, trimethyl phosphate, propylene carbonate, tetramethyl orthocarbonate, triethyl phosphate, dimethyl sulfate, tris(2-butoxyethyl) phosphate, diethyl sulfate, diethyl carbonate, 2-(2-ethoxyethoxy)ethyl acetate, 2-ethoxyethyl acetate, 2-(2-butoxyethoxy)ethyl acetate, 2-butoxyethyl acetate, furfural, diethylene glycol monoethyl ether, 2-methoxyethanol, 2-(2-butoxyethoxy)ethoxyethanol, 3-methoxy-1-butanol, 1-methoxy-2-propanol, ethoxyethanol, 2-furanmethanol, tetrahydro-2H-pyran-2-methanol, 3-methoxyphenol, 1-propoxy-2-propanol, 2,2'-oxybis(2,1-ethanediyl) bisethanol, 2,2'-bis(methylimino)ethanol, 2-(2-methoxyethoxy)ethanol, (ethylene) glycol, triethylene glycol, diethylene glycol, 1,3-propanediol, propylene glycol, tripropylene glycol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethoxyethyl acrylate, ethyl butyrate, propyl propionate, ethyl valerate, n-butyl propionate, n-butyl butyrate, isobutyl propionate, isopropyl butyrate, 1,1'-bis(2-ethoxy)ethane, trimethyl phosphite, tetrahydrofurfuryl alcohol, 4-(2-hydroxyethyl)morpholine, 1,3-butanediol, 1,2-ethylene glycol dinitrate, 3-oxiranyl-7-oxabicyclo[4.1.0]heptane, dibutyl oxalate, morpholine, ((1,1-dimethylethoxy)methyl)oxirane, dimethoxytetrahydrofuran, triethyl orthoformate, citral, allyl acrylate, butyl lactate, nitrocyclohexane, 2-propen-1-ol, methallyl alcohol, 2,6-dimethylmorpholine, 2-butanone oxime.,

[0069] Preferably, the organic extractant is selected from phenyl acetate, n-butyl acetate, β-phenethyl acetate, sec-butyl acetate, isoamyl acetate, n-amyl acetate, ethanol, 2-propanol, α-methylcyclopropanemethanol, dimethylformamide, N,N-dimethylacetamide, methylformamide, N,N-dimethylpropanamide, N,N-dimethylbutyramide, N-butylacetamide, 1,3-dioxane, 4-methyl-1,3-dioxane, β-propiolactone, γ-butyrolactone, dimethyl malonate, ethyl acetoacetate, 1,2-ethanediol diacetate, methyl cyanoacetate, 2-propenyl 3-oxobutanoate, dimethyl glutarate, ethyl oxalate, methyl ethyl 3-oxobutanoate, ethylene glycol monomethyl ether acetate, dimethyl maleate, ethyl cyanoacetate, ethyl methyl succinate, diethyl malonate, methyl 2-hydroxypropanoate, tert-butyl acetoacetate, ethyl succinate, allylidene diacetate, diethyl adipate, ethyl phenylacetate, benzyl acetate, dibutyl (Z)-2-butenedioate, 2-methylpropyl acetate, tetramethyl silicate, butyl 2-propenoate, 2-methylpropyl acrylate, amyl formate, cyclohexyl acetate, ethyl 3-methylbutanoate, methyl hexanoate, diethylene glycol dimethyl ether, crotyl glycol ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, isoamyl formate, 2,5,8,11-tetraoxadodecane, 1-hydroxy-2-propanone, acetonylacetone, acetylacetone, 2-oxepanone, N-methyl-2-pyrrolidone, 5-ethyldihydro-2(3H)-furanone, 5-methyl-2(3H)-furanone, 2-cyclohexen-1-one, 1-(4-methoxyphenyl)-2-propanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, 4-methylene-2-oxetanone, 1-cyclopropylethanone, 2,3-pentanedione, isophorone, cyclohexanone, 2-methylcyclopentanone, 4-methyl-3-penten-2-one, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 2,3-hexanedione, 3,4-hexanedione, 4-phenyl-2-butanone, 2-hexanone, 4-methyl-2-pentanone, 3-hexanone, 4-fluorobenzophenone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethylcyclohexanone, 2-heptanone, 2,4-dimethyl-3-pentanone, 2,2-dimethyl-3-pentanone, 3-heptanone, 4-heptanone, 2-octanone, 2-methyl-1-phenyl-1-propanone, glutaronitrile, 2-methylglutaronitrile, hydroxyacetonitrile, 2-hydroxypropanenitrile, dimethylaminopropionitrile, (E)-2-butenenitrile, 3-butenenitrile, butyronitrile, 2-hydroxy-2-methylpropanenitrile, valeronitrile, phenylacetonitrile, hexanenitrile, heptanenitrile, octanenitrile, nonanenitrile, trimethyl phosphate, propylene carbonate, tetramethyl orthocarbonate, triethyl phosphate, tris(2-butoxyethyl) phosphate, diethyl carbonate, 2-(2-ethoxyethoxy)ethyl acetate, 2-ethoxyethyl acetate, 2-(2-butoxyethoxy)ethyl acetate, 2-butoxyethyl acetate, furfural, diethylene glycol monoethyl ether, 2-methoxyethanol, 2-(2-butoxyethoxy)ethoxyethanol, 3-methoxy-1-butanol, 1-methoxy-2-propanol, ethoxyethanol, 2-furanmethanol, tetrahydro-2H-pyran-2-methanol, 3-methoxyphenol, 1-propoxy-2-propanol, 2,2'-oxybis(2,1-ethanediyl) bisethanol, 2-(2-methoxyethoxy)ethanol, (ethylene) glycol, triethylene glycol, diethylene glycol, 1,3-propanediol, propylene glycol, tripropylene glycol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethoxyethyl acrylate, ethyl butyrate, propyl propionate, ethyl valerate, n-butyl propionate, n-propyl butyrate, isobutyl propionate, isopropyl butyrate, 1,1'-oxybis(2-ethoxy)ethane, tetrahydrofurfuryl alcohol, 4-(2-hydroxyethyl)morpholine, 1,3-butanediol, 1,2-ethanediol dinitrate, 3-oxiranyl-7-oxabicyclo[4.1.0]heptane, dibutyl oxalate, ((1,1-dimethylethoxy)methyl)oxirane, dimethoxytetrahydrofuran, triethyl orthoformate, citral, allyl acrylate, butyl lactate, 2-propen-1-ol, methallyl alcohol, 2-butanone oxime.,

[0070] More preferably, the organic extractant is selected from β-propiolactone, γ-butyrolactone, 1-hydroxy-2-propanone, acetonylacetone, trimethyl phosphate, acetylacetone, propylene carbonate, dimethyl malonate, ethyl acetoacetate, 1,2-ethylene diacetate, (ethylene) glycol, ethyl oxalate, 1-methyl ethyl 3-oxobutyrate, ethylene glycol monomethyl ether acetate, dimethyl maleate, triethyl phosphate, triethylene glycol, diethyl malonate, furfural, diethylene glycol, tert-butyl acetoacetate, ethyl succinate, 1,3-propanediol, cyclopentanone, propylene glycol, 1-cyclopropyl ethanone, 2-methoxyethanol, 2,3-pentanedione, tripropylene glycol, cyclohexanone, diethyl carbonate, 1,3-butanediol, 3-methoxy-1-butanol, 4-methyl-3-penten-2-one, 1-methoxy-2-propanol, phenyl acetate, cycloheptanone, 3-methyl cyclohexanone, 4-methyl cyclohexanone, 2,3-hexanedione, 3,4-hexanedione, citral, 1,5-pentanediol, diethylene glycol monobutyl ether, 4-phenyl-2-butanone, ethanol, n-butyl acetate, 4-methyl-2-pentanone, 3-hexanone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethyl cyclohexanone and ethyl benzoate.

[0071] In particular, the organic extractant is selected from trimethyl phosphate, ethyl acetoacetate, (ethylene) glycol, ethyl oxalate, triethylene glycol, diethyl malonate, diethylene glycol, 1,3-propanediol, propylene glycol, 2-methoxyethanol, ethanol and ethyl benzoate.

[0072] According to a preferred embodiment, step b) is carried out at a pressure between 1 and 10 bara, preferably between 1 - 7 bara.

[0073] According to a preferred embodiment, the melting point of the organic extractant is below 0 °C, advantageously below -5 °C, preferably below -10 °C, especially below -20 °C.

[0074] According to a preferred embodiment, when step b) is carried out at a pressure of 3 to 6 bara, the organic extractant has a melting point below 0 °C. This makes it possible to avoid solidification of the extractant at the top of the distillation column. In this preferred embodiment, the organic extractant is as described above.

[0075] According to another preferred embodiment, when step b) is carried out at a pressure of 1 to 3 bara, the melting point of the organic extractant is below -10 °C, preferably below -20 °C, particularly below -40 °C.According to this another embodiment, the organic extractant is preferably selected from β-propiolactone, γ-butyrolactone, 1-hydroxy-2-propanone, trimethyl phosphate, acetylacetone, propylene carbonate, dimethyl malonate, ethyl acetoacetate, 1,2-ethanediol diacetate, (ethylene) glycol, ethyl oxalate, 1-methyl ethyl 3-oxobutyrate, ethylene glycol monomethyl ether acetate, dimethyl maleate, triethyl phosphate, diethyl malonate, furfural, diethylene glycol, tert-butyl acetoacetate, ethyl succinate, 1,3-propanediol, cyclopentanone, propylene glycol, 1-cyclopropyl ethanone, 2-methoxyethanol, 2,3-pentanedione, tripropylene glycol, cyclohexanone, diethyl carbonate, 1,3-butanediol, 3-methoxy-1-butanol, 4-methyl-3-penten-2-one, 1-methoxy-2-propanol, phenyl acetate, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 2,3-hexanedione, 3,4-hexanedione, citral, 1,5-pentanediol, diethylene glycol monobutyl ether, 4-phenyl-2-butanone, ethanol, n-butyl acetate, 4-methyl-2-pentanone, 3-hexanone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethylcyclohexanone and ethyl benzoate; preferably, the organic extractant is selected from β-propiolactone, γ-butyrolactone, trimethyl phosphate, acetylacetone, propylene carbonate, dimethyl malonate, ethyl acetoacetate, 1,2-ethanediol diacetate, ethyl oxalate, 1-methyl ethyl 3-oxobutyrate, ethylene glycol monomethyl ether acetate, triethyl phosphate, diethyl malonate, furfural, tert-butyl acetoacetate, ethyl succinate, 1,3-propanediol, cyclopentanone, propylene glycol, 1-cyclopropyl ethanone, 2-methoxyethanol, 2,3-pentanedione, tripropylene glycol, cyclohexanone, diethyl carbonate, 1,3-butanediol, 3-methoxy-1-butanol, 4-methyl-3-penten-2-one, 1-methoxy-2-propanol, phenyl acetate, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 2,3-hexanedione, diethylene glycol monobutyl ether, ethanol, n-butyl acetate, 4-methyl-2-pentanone, 3-hexanone, 4,4-dimethyl-2-pentanone, 5-methyl-2-hexanone, 2,2-dimethylcyclohexanone and ethyl benzoate; particularly, the organic extractant is selected from γ-butyrolactone, trimethyl phosphate, propylene carbonate, dimethyl malonate, ethyl acetoacetate, ethyl oxalate, ethylene glycol monomethyl ether acetate, triethyl phosphate, diethyl malonate, cyclopentanone, propylene glycol, 1-cyclopropyl ethanone, 2-methoxyethanol, 2,3-pentanedione, diethyl carbonate, 1,3-butanediol, 3-methoxy-1-butanol, 4-methyl-3-penten-2-one, 1-methoxy-2-propanol, 3-methylcyclohexanone, 4-methylcyclohexanone, diethylene glycol monobutyl ether, ethanol, n-butyl acetate, 4-methyl-2-pentanone, 3-hexanone, 4,4-dimethyl-2-pentanone and 5-methyl-2-hexanone.

[0076] Process for producing trifluoroethylene

[0077] According to a second aspect of the present invention, there is provided a process for producing trifluoroethylene. The process is carried out in a reactor equipped with a fixed catalytic bed containing a catalyst.

[0078] The process comprises the following steps:

[0079] A’) Reacting chlorotrifluoroethylene with hydrogen in the presence of a catalyst and in the gas phase to produce a stream A comprising trifluoroethylene, unreacted chlorotrifluoroethylene and 1,1,2-trifluoroethane;

[0080] B’) Purifying the stream A to form a stream B1 comprising trifluoroethylene and a stream B2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane,

[0081] C’) Using the stream B2 in the purification process according to the present invention.

[0082] According to a preferred embodiment, the process is carried out continuously. According to a preferred embodiment, the hydrogen is in anhydrous form. According to a preferred embodiment, the chlorotrifluoroethylene is in anhydrous form. Carrying out the process according to the present invention in the presence of anhydrous hydrogen and / or chlorotrifluoroethylene makes it possible to effectively increase the lifetime of the catalyst and thus increase the overall productivity of the process. The term "anhydrous" means that the mass content of water is less than 1000 ppm, advantageously 500 ppm, preferably less than 200 ppm, in particular less than 100 ppm, based on the total weight of the compound considered.

[0083] Catalyst

[0084] Preferably, the catalyst is based on a metal of columns 8-10 of the Periodic Table. In particular, the catalyst is based on a metal selected from Pd, Pt, Rh and Ru; preferably palladium.

[0085] Preferably, the catalyst is supported. The support is preferably selected from activated carbon, aluminium-based supports, calcium carbonate and graphite. Preferably, the support is based on aluminium. In particular, the support is alumina. The alumina may be α-alumina. Preferably, the alumina contains at least 90% α-alumina. It has been observed that the conversion of the hydrogenolysis reaction is improved when the alumina is α-alumina. Thus, the catalyst is more particularly palladium supported on alumina, advantageously palladium supported on alumina containing at least 90% α-alumina, preferably palladium supported on α-alumina.

[0086] Preferably, the palladium represents from 0.01% to 5% by weight, preferably from 0.1% to 2% by weight, based on the total weight of the catalyst.

[0087] In particular, the catalyst comprises 0.01 wt% to 5 wt% of palladium supported on alumina; preferably, the alumina comprises at least 90% of α-alumina; more preferably, the alumina is α-alumina.

[0088] Activation of the catalyst

[0089] The catalyst is preferably activated before being used in step A’). Preferably, the activation of the catalyst is carried out at a high temperature and in the presence of a reducing agent, an inert gas or a mixture thereof.

[0090] According to a particular embodiment, the reducing agent is selected from hydrogen, carbon monoxide, nitric oxide, formaldehyde, C1-C6 alkanes and C1-C 10 halohydrocarbons, or a mixture thereof; preferably hydrogen or C1-C 10 halohydrocarbons or a mixture thereof; in particular hydrogen, chlorotrifluoroethylene, trifluoroethylene, chlorotrifluoroethane, trifluoroethane or difluoroethane, or a mixture thereof.

[0091] The inert gas may be nitrogen or argon, preferably nitrogen.

[0092] Preferably, the activation of the catalyst is carried out at a temperature between 100 °C and 400 °C, in particular at a temperature between 150 °C and 350 °C. In particular, the activation of the catalyst is carried out at a temperature between 100 °C and 400 °C, in particular at a temperature between 150 °C and 350 °C, in the presence of hydrogen as the reducing agent.

[0093] Preferably, the temperature of the catalytic bed is increased from a temperature T1 to a temperature T2 during activation. In particular, the temperature of the catalytic bed is increased from the temperature T1 to a temperature T2 greater than T1 with a temperature gradient of less than 0.5 °C / min. The applied temperature gradient enables prevention of premature degradation of the catalyst and thus better yields or better productivity of the hydrogenolysis reaction can be achieved. In particular, the temperature is increased with a temperature gradient of less than 0.45 °C / min or less than 0.40 °C / min, or less than 0.35 °C / min, or less than 0.30 °C / min, or less than 0.25 °C / min, or less than 0.20 °C / min, or less than 0.15 °C / min, or less than 0.10 °C / min, or less than 0.05 °C / min. The temperature T1 is the initial temperature of the activation step. This temperature T1 can be room temperature. Alternatively, the temperature T1 can be between 0 °C and 150 °C, advantageously between 0 °C and 120 °C, preferably between 0 °C and 100 °C, more preferably between 10 °C and 100 °C, in particular between 20 °C and 100 °C, more particularly between 20 °C and 75 °C, advantageously between 20 °C and 50 °C. The temperature T2 represents the temperature to be reached during the activation phase. The temperature T2 is advantageously between 150 °C and 400 °C, preferably between 155 °C and 375 °C, more preferably between 160 °C and 350 °C, in particular between 165 °C and 325 °C, more particularly between 170 °C and 320 °C, advantageously between 175 °C and 310 °C, more advantageously between 180 °C and 300 °C. According to a preferred embodiment, the temperature T2 is advantageously between 185 °C and 290 °C, preferably between 190 °C and 280 °C, more preferably between 195 °C and 270 °C, in particular between 200 °C and 260 °C. The temperature T2 can be maintained for 5 min to 200 h, preferably 10 min to 100 h, in particular 15 min to 75 h, more particularly 30 min to 50 h, advantageously 1 h to 25 h. The temperature T2 can be maintained for 5 min to 24 h, preferably 10 min to 20 h, in particular 15 min to 15 h, more particularly 30 min to 10 h, advantageously 1 h to 10 h.

[0094] Preferably, the gas stream used during the activation step does not contain any oxygen. Preferably, the activation step can be carried out with an amount of reducing agent greater than 0.01 mol / g catalyst, preferably greater than 0.05 mol / g catalyst. In particular, the activation step can be carried out with an amount of reducing agent of 0.01 to 10 mol / g catalyst, preferably 0.05 to 5 mol / g catalyst.

[0095] According to another embodiment, during the activation step, the temperature of the catalytic bed is increased from temperature T1 to temperature T2 in a stabilization phase. The activation of the catalyst during the stabilization phase enables the efficiency of the catalyst to be increased. The application of the stabilization phase enables the degradation of the catalyst to be prevented. It has also been observed that if the temperature increase between the stabilization phases is gradual and relatively slow compared to the conventional conditions for activating the catalyst, the properties of the catalyst are further improved. Thus, preferably, in the activation step, between two stabilization phases, the temperature is increased with a temperature gradient of less than 0.5 °C / min. The temperature gradient applied between two stabilization phases enables premature degradation of the catalyst to be prevented and thus a better yield or productivity of the hydrogenolysis reaction to be achieved. In particular, the temperature is increased with a temperature gradient of less than 0.45 °C / min or less than 0.40 °C / min, or less than 0.35 °C / min, or less than 0.30 °C / min, or less than 0.25 °C / min, or less than 0.20 °C / min, or less than 0.15 °C / min, or less than 0.10 °C / min, or less than 0.05 °C / min. Temperature T1 is the initial temperature of the activation step. This temperature T1 can be room temperature. Alternatively, temperature T1 can be between 0 °C and 150 °C, advantageously between 0 °C and 120 °C, preferably between 0 °C and 100 °C, more preferably between 10 °C and 100 °C, particularly between 20 °C and 100 °C, more particularly between 20 °C and 75 °C, advantageously between 20 °C and 50 °C. Temperature T2 represents the temperature to be reached during the activation phase. Temperature T2 is advantageously between 150 °C and 400 °C, preferably between 155 °C and 375 °C, more preferably between 160 °C and 350 °C, particularly between 165 °C and 325 °C, more particularly between 170 °C and 320 °C, advantageously between 175 °C and 310 °C, more advantageously between 180 °C and 300 °C. According to a preferred embodiment, temperature T2 is advantageously between 185 °C and 290 °C, preferably between 190 °C and 280 °C, more preferably between 195 °C and 270 °C, particularly between 200 °C and 260 °C. Temperature T2 can be maintained for 5 min to 200 h, preferably 10 min to 100 h, particularly 15 min to 75 h, more particularly 30 min to 50 h, advantageously 1 h to 25 h. Temperature T2 can be maintained for 5 min to 24 h, preferably 10 min to 20 h, particularly 15 min to 15 h, more particularly 30 min to 10 h, advantageously 1 h to 10 h. The step i') of activating the catalyst comprises at least one stabilization phase between temperature T1 and temperature T2. The step i') of activating the catalyst can include several stabilization phases between temperature T1 and temperature T2. Preferably, the activation step includes at least one stabilization phase at a temperature T1a between 90 °C and 120 °C. The presence of the stabilization phase between 90 °C and 120 °C should be conducive to increasing the lifespan of the catalyst.The activation step may also include one or more stabilization stages between temperature T1 and T1a and / or between temperature T1a and T2. Preferably, each stabilization stage between temperature T1 and temperature T2 may last between 5 min and 200 h, preferably between 10 min and 100 h, particularly between 15 min and 75 h, more particularly between 30 min and 50 h. In particular, each stabilization stage between temperature T1 and temperature T2 may last between 5 min and 24 h, preferably between 10 min and 20 h, particularly between 15 min and 15 h, more particularly between 30 min and 10 h. In particular, the stabilization stage at temperature T1a may last from 5 min to 200 h, preferably from 10 min to 100 h, particularly from 15 min to 75 h, more particularly from 30 min to 50 h. Advantageously, the stabilization stage at temperature T1a may last from 5 min to 24 h, preferably from 10 min to 20 h, particularly from 15 min to 15 h, more particularly from 30 min to 10 h.

[0096] The gas stream used during the activation step may vary over time. For example, the gas stream may contain an inert gas between two stabilization stages and, for example, a reducing agent between two other stabilization stages. In particular, when the activation step is carried out between temperature T1 and T1a, the gas stream contains an inert gas, and when the activation step is carried out between temperature T1a and T2, the gas stream contains a reducing agent, preferably hydrogen or a C1-C 10 halohydrocarbon as defined above. Thus, the gas stream used during the activation step is changed during the stabilization stage applied at temperature T1a. Alternatively, throughout the activation step, the gas stream may contain a reducing agent, such as hydrogen or a C1-C 10 halohydrocarbon, optionally mixed with an inert gas such as nitrogen. It has been observed that using a reducing agent such as hydrogen or a C1-C 10 halohydrocarbon, optionally mixed with an inert gas such as nitrogen, during the temperature increase between temperature T1a and temperature T2 of the said stabilization stage represents an additional advantage in terms of productivity. As described above, temperature T2 is maintained for a certain time. During this stabilization stage at temperature T2, the gas stream may be changed. Thus, during the stabilization stage at temperature T2, the gas stream may contain hydrogen or a C1-C 10 halohydrocarbon; in particular, during the stabilization stage at temperature T2, the gas stream may contain hydrogen, chlorotrifluoroethylene, trifluoroethane, trifluoroethylene, chlorotrifluoroethane or difluoroethane. Preferably, the activation step may be carried out with an amount of reducing agent greater than 0.01 mol / g catalyst, preferably greater than 0.05 mol / g catalyst. In particular, the activation step may be carried out with an amount of reducing agent from 0.01 to 10 mol / g catalyst, preferably from 0.05 to 5 mol / g catalyst.

[0097] According to another embodiment, the activation step comprises contacting the catalyst with a gas stream comprising chlorotrifluoroethylene and optionally hydrogen. It has been observed that chlorotrifluoroethylene (CTFE) enables the activation of the catalyst, especially when only hydrogen is present. This enables the improvement of the process for producing trifluoroethylene. Activation in the presence of CTFE enables the activation of the catalyst at a lower temperature and thus provides a less energy-intensive process. The process is further simplified since the reducing agent is also one of the reagents in the subsequent reaction during activation. Preferably, in this embodiment, the activation step is carried out at a temperature T2' of less than 100 °C. This temperature T2' can be reached starting from the temperature T1' using a low temperature gradient. Thus, during the activation step, the temperature of the catalyst bed rises from the temperature T1' to a temperature T2' higher than T1'; the temperature of the catalyst bed preferably rises from the temperature T1' to a temperature T2' higher than T1' with a temperature gradient of less than 0.5 °C / min. The applied temperature gradient prevents premature degradation of the catalyst and thus enables a better yield or better productivity of the hydrogenolysis reaction. In particular, the temperature rises with a temperature gradient of less than 0.45 °C / min or less than 0.40 °C / min, or less than 0.35 °C / min, or less than 0.30 °C / min, or less than 0.25 °C / min, or less than 0.20 °C / min, or less than 0.15 °C / min, or less than 0.10 °C / min, or less than 0.05 °C / min.

[0098] Preferably, the temperature of the catalyst bed is increased by increasing the contact time, which is calculated as the ratio of the volume of the catalyst (in liters) at the reactor inlet to the total flow rate of the gas stream (in standard liters per second). The contact time is between 1 and 60 seconds, preferably between 5 and 45 seconds, especially between 10 and 30 seconds, more especially between 15 and 25 seconds. The temperature T1' can be between 0 °C and 50 °C, advantageously between 10 °C and 50 °C, preferably between 20 °C and 50 °C. Preferably, the temperature T2' is lower than the temperature T3 at which step A') is carried out. The temperature T3 is preferably between 100 °C and 180 °C, more preferably between 100 °C and 160 °C, especially between 120 °C and 160 °C.

[0099] Regeneration of the catalyst

[0100] The catalyst used in the process of the present invention can be regenerated. This regeneration step can be carried out in the temperature range of the catalyst bed between 90 °C and 450 °C. Preferably, the regeneration step is carried out in the presence of hydrogen. Carrying out the regeneration step enables the improvement of the yield of the reaction compared to the initial yield before regeneration.

[0101] According to a preferred embodiment, the regeneration step can be carried out at a catalytic bed temperature of from 90 °C to 300 °C, preferably at a catalytic bed temperature of from 90 °C to 250 °C, more preferably at a catalytic bed temperature of from 90 °C to 200 °C, especially at a catalytic bed temperature of from 90 °C to 175 °C, more especially at a catalytic bed temperature of from 90 °C to 150 °C. In particular, carrying out the regeneration step at a low temperature (for example from 90 °C to 200 °C or from 90 °C to 175 °C or from 90 °C to 150 °C) makes it possible to desorb the compounds harmful to the catalyst activity and / or makes it possible to limit the phase transitions that modify the catalyst structure.

[0102] According to another preferred embodiment, the regeneration step can be carried out at a catalytic bed temperature of greater than 200 °C, advantageously greater than 230 °C, preferably greater than 250 °C, especially greater than 300 °C. The regeneration step can be carried out regularly according to the productivity or conversion obtained in step a). The regeneration step can advantageously be carried out at a catalytic bed temperature between 200 °C and 300 °C, preferably between 205 °C and 295 °C, more preferably between 210 °C and 290 °C, especially between 215 °C and 290 °C, more especially between 220 °C and 285 °C, advantageously between 225 °C and 280 °C, more advantageously between 230 °C and 280 °C. Alternatively, the regeneration step can be carried out at a temperature between 300 °C and 450 °C, preferably between 300 °C and 400 °C. The regenerated catalyst can be reused in step A') of the process of the invention.

[0103] Hydrodechlorination reaction

[0104] As described above, the process comprises a step of hydrodechlorination of chlorotrifluoroethylene with hydrogen to produce a stream containing trifluoroethylene. The hydrodechlorination step is carried out in the presence of a catalyst and in the gas phase. Preferably, the hydrodechlorination step is carried out in the presence of a pre-activated catalyst and in the gas phase. The hydrodechlorination step comprises introducing hydrogen, CTFE and optionally an inert gas, such as nitrogen, simultaneously in the gas phase and in the presence of said catalyst (which is preferably activated).

[0105] Preferably, step A') is carried out at a fixed catalyst bed temperature between 50 °C and 250 °C. Step A') can be carried out at a fixed catalyst bed temperature between 50 °C and 240 °C, advantageously between 50 °C and 230 °C, preferably between 50 °C and 220 °C, more preferably between 50 °C and 210 °C, especially between 50 °C and 200 °C. Step A') can also be carried out at a fixed catalyst bed temperature between 60 °C and 250 °C, advantageously between 70 °C and 250 °C, preferably between 80 °C and 250 °C, more preferably between 90 °C and 250 °C, especially between 100 °C and 250 °C, more especially between 120 °C and 250 °C. Step A') can also be carried out at a fixed catalyst bed temperature between 60 °C and 240 °C, advantageously between 70 °C and 230 °C, preferably between 80 °C and 220 °C, more preferably between 90 °C and 210 °C, especially between 100 °C and 200 °C, more especially between 100 °C and 180 °C, advantageously between 100 °C and 160 °C, particularly preferably between 120 °C and 160 °C.

[0106] The H2 / CTFE molar ratio is between 0.5 / 1 and 2 / 1 and preferably between 1 / 1 and 1.2 / 1. If an inert gas, such as nitrogen, is present in step A'), the nitrogen / H2 molar ratio is from 0 / 1 to 2 / 1, preferably 0 / 1 to 1 / 1.

[0107] Step A') is preferably carried out at a pressure of 0.05 MPa to 1.1 MPa, more preferably 0.05 MPa to 0.5 MPa, especially at atmospheric pressure.

[0108] The contact time at the reactor inlet (calculated as the ratio of the volume of the catalyst (in liters) to the total flow rate of the gas mixture (in standard liters per second)) is between 1 and 60 seconds, preferably between 5 and 45 seconds, especially between 10 and 30 seconds, more especially between 15 and 25 seconds.

[0109] Examples

[0110] Method for selecting an organic extractant

[0111] The selection of the organic extractant is determined by using the Cosmo-RS model implemented in the Cosmotherm software. For the binary pair of this selection, the separation factor of each solvent studied is calculated by the following equation:

[0112] S 1,2 =(γ 1,S ) / (γ 2,S ) where

[0113] γ 1,S represents the activity coefficient of the first compound 1 at infinite dilution in the organic extractant considered,

[0114] γ 2,S represents the activity coefficient at infinite dilution of the second compound 2 of the binary pair in the organic extractant under consideration,

[0115] The absorption capacity of each of the solvents studied and of the binary pair (1, 2) under consideration was also calculated. The absorption capacity is given by the formula C 2,S = 1 / (γ 2,S ), where γ 2,S represents the activity coefficient at infinite dilution of the second compound of the binary pair under consideration in the organic extractant studied.

[0116] The calculations were repeated for each of the organic extractants studied. The minimum separation factor and the absorption capacity values were determined in order to allow for sufficient separation between the first and second compounds of the binary pair (1, 2) under consideration.

[0117] Example 1

[0118] In this example, the separation between chlorotrifluoroethylene (CTFE) and 1,1,2-trifluoroethane was considered. An organic extractant with a separation factor S 1,2 greater than 2 is capable of separating a mixture comprising chlorotrifluoroethylene (CTFE) and 1,1,2-trifluoroethane.

[0119] [Table 1]

[0120] Table 1 - Capability and separation factor of organic extractants

[0121]

[0122]

[0123]

[0124] The results were confirmed using a mixture comprising 90 - 95 wt% chlorotrifluoroethylene and 5 - 10 wt% 1,1,2-trifluoroethane relative to the total weight of the mixture. This was distilled at 1 bara using one of the following extractants: ethylene glycol, 1,3-propanediol, propylene glycol or ethanol. The mixture to be separated was introduced into a distillation column at atmospheric pressure. The extractant was continuously introduced at the top of the distillation column. Chlorotrifluoroethylene was collected at the top of the distillation column. 1,1,2-Trifluoroethane and the extractant were collected from the bottom of the distillation column.

Claims

1. A method for purifying chlorotrifluoroethylene (CTFE) from a first composition comprising chlorotrifluoroethylene and 1,1,1,2 - tetrafluoroethane (143), the method comprising the following steps: a) Extractively distilling the first composition in the presence of at least one organic extractant to form i) a second composition comprising the organic extractant and 1,1,2 - trifluoroethane; and ii) a first stream comprising chlorotrifluoroethylene; b) Collecting and separating the second composition to form a second stream comprising the organic extractant and a third stream comprising 1,1,2 - trifluoroethane; preferably, recycling the second stream to step a).

2. The method according to the preceding claim, characterized in that The organic extractant has a flash point above 13 °C.

3. The method according to any one of the preceding claims, characterized in that The organic extractant is a compound containing 2 to 12 carbon atoms.

4. The method according to any one of the preceding claims, characterized in that The organic extractant has a molecular weight of less than 200 g.mol -1 -1.

5. The method according to any one of the preceding claims, characterized in that The organic extractant has a separation factor S greater than or equal to 2.0 1,2 , and the separation factor is calculated by the following formula: S 1,2 = (γ 1,S ) / (γ 2,S ), where: γ 1,S represents the activity coefficient of chlorotrifluoroethylene in the organic extractant at infinite dilution, γ 2,S represents the activity coefficient of 1,1,2-trifluoroethane in the organic extractant at infinite dilution, Advantageously, the separation factor S 1,2 is greater than or equal to 2.1, preferably greater than or equal to 2.2, more preferably greater than or equal to 2.3, especially greater than or equal to 2.4, and even more especially greater than or equal to 2.

5.

6. The method according to any one of the preceding claims, characterized in that The organic extractant has an absorption capacity C greater than or equal to 0.20 2,S , and the absorption capacity is calculated by the following formula: C 2,S = 1 / (γ 2,S ), where γ 2,S represents the activity coefficient of 1,1,2-trifluoroethane in the organic extractant at infinite dilution.

7. The method according to any one of the preceding claims, characterized in that The first composition is an azeotropic or quasi - azeotropic composition comprising chlorotrifluoroethylene and 1,1,2 - trifluoroethane.

8. The method according to any one of the preceding claims, characterized in that The organic extractant has a melting point below 0 °C.

9. The method according to any one of the preceding claims, characterized in that Step b) is carried out at a pressure between 1 and 10 bara, preferably 1 - 7 bara.

10. The method according to any one of the preceding claims, characterized in that The organic extractant is selected from H2O, β - propiolactone, γ - butyrolactone, 1 - hydroxy - 2 - acetone, acetylacetone acetone, trimethyl phosphate, acetylacetone, propylene carbonate, dimethyl malonate, ethyl acetoacetate, 1,2 - ethylene glycol diacetate, ethylene glycol, ethyl oxalate, 1 - methyl ethyl 3 - oxobutyrate, ethylene glycol monomethyl ether acetate, dimethyl maleate, triethyl phosphate, triethylene glycol, diethyl malonate, furfural, diethylene glycol, tert - butyl acetoacetate, ethyl succinate, 1,3 - propanediol, cyclopentanone, propylene glycol, 1 - cyclopropyl ethanone, 2 - methoxyethanol, 2,3 - pentanedione, tripropylene glycol, cyclohexanone, diethyl carbonate, 1,3 - butanediol, 3 - methoxy - 1 - butanol, 4 - methyl - 3 - penten - 2 - one, 1 - methoxy - 2 - propanol, phenyl acetate, cycloheptanone, 3 - methylcyclohexanone, 4 - methylcyclohexanone, 2,3 - hexanedione, 3,4 - hexanedione, citral, 1,5 - pentanediol, diethylene glycol monobutyl ether, 4 - phenyl - 2 - butanone, ethanol, n - butyl acetate, 4 - methyl - 2 - pentanone, 3 - hexanone, 4,4 - dimethyl - 2 - pentanone, 5 - methyl - 2 - hexanone, 2,2 - dimethylcyclohexanone and ethyl benzoate.

11. A method for producing trifluoroethylene in a reactor equipped with a fixed catalytic bed containing a catalyst, the method comprising the following steps: A’) Reacting chlorotrifluoroethylene with hydrogen in the presence of a catalyst and in the gas phase to produce a stream A comprising trifluoroethylene, unreacted chlorotrifluoroethylene and 1,1,2 - trifluoroethane; B’) Purifying the stream A to form a stream B1 comprising trifluoroethylene and a stream B2 comprising chlorotrifluoroethylene and 1,1,2 - trifluoroethane; C’) Using the stream B2 in the purification method according to any one of the preceding claims 1 to 10.

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