EP4352032A1 - Method for producing trifluoroethylene and recycling the chlorotrifluoroethylene stream - Google Patents

Method for producing trifluoroethylene and recycling the chlorotrifluoroethylene stream

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Publication number
EP4352032A1
EP4352032A1 EP22735012.1A EP22735012A EP4352032A1 EP 4352032 A1 EP4352032 A1 EP 4352032A1 EP 22735012 A EP22735012 A EP 22735012A EP 4352032 A1 EP4352032 A1 EP 4352032A1
Authority
EP
European Patent Office
Prior art keywords
stream
chlorotrifluoroethylene
trifluoroethane
catalyst
trifluoroethylene
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22735012.1A
Other languages
German (de)
French (fr)
Inventor
Alexandre CAMBRODON
Cédric LAVY
Thierry Lannuzel
Philippe Leduc
Kevin HISLER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Arkema France SA
Original Assignee
Arkema France SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Arkema France SA filed Critical Arkema France SA
Publication of EP4352032A1 publication Critical patent/EP4352032A1/en
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/23—Preparation of halogenated hydrocarbons by dehalogenation

Definitions

  • the present invention relates to a process for the production of hydrofluoroolefins.
  • the present invention relates to a process for the production of trifluoroethylene (VF3) by hydrogenolysis of chlorotrifluoroethylene.
  • VF3 trifluoroethylene
  • Fluorinated olefins such as VF3, are known and are used as monomers or comonomers for the manufacture of fluorocarbon polymers having remarkable characteristics, in particular excellent chemical behavior and good heat resistance.
  • Trifluoroethylene is a gas under normal conditions of pressure and temperature. The main risks associated with the use of this product concern its flammability, its propensity for self-polymerization when it is not stabilized, its explosiveness due to its chemical instability and its supposed sensitivity to peroxidation, by analogy with other halogenated olefins. Trifluoroethylene has the particularity of being extremely flammable, with a lower explosive limit (LEL) of approximately 10% and an upper explosive limit (UEL) of approximately 30%. The major danger, however, is associated with the propensity of VF3 to decompose violently and explosively under certain pressure conditions in the presence of an energy source, even in the absence of oxygen.
  • LEL lower explosive limit
  • UEL upper explosive limit
  • CTFE chlorotrifluoroethylene
  • WO 2013/128102 discloses a process for producing trifluoroethylene by hydrogenolysis of CTFE in the gas phase and in the presence of a catalyst based on a group VIII metal at atmospheric pressure and at low temperatures.
  • the present invention relates to a process for producing trifluoroethylene in a reactor provided with a fixed catalytic bed comprising a catalyst, said process comprising the steps of: a) reaction of chlorotrifluoroethylene with hydrogen in the presence of the catalyst and in the gas phase to produce a stream A comprising trifluoroethylene; b) treatment of said stream A under conditions sufficient to produce a stream DI comprising 1,1,2-trifluoroethane in a content of less than 15% by weight based on the total weight of said stream D1, c) recycling of stream D1 to step a).
  • stream A also comprises, in addition to trifluoroethylene, unreacted chlorotrifluoroethylene and 1,1,2-trifluoroethane.
  • stream D1 also comprises chlorotrifluoroethylene in a mass content greater than 60% by weight based on the total weight of said stream D1.
  • stream D1 is in the form of an azeotropic or quasi-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
  • stream A comprises trifluoroethylene, chlorotrifluoroethylene and 1,1,2-trifluoroethane and step b) comprises the steps of: bl) purification of said stream A comprising trifluoroethylene, chlorotrifluoroethylene and 1, 1,2-trifluoroethane to form a C1 stream comprising trifluoroethylene and a C2 stream comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane; b2) purification of stream C2 to produce said stream D1 and a stream D2 comprising 1,1,2-trifluoroethane.
  • stage b2) is carried out by distillation at a pressure below 8 bara, preferably below 6 bara.
  • stage b2) is carried out by distillation, and the temperature at the top of the distillation column is below 40°C.
  • said catalyst is a catalyst based on a metal from columns 8 to 10 of the periodic table of the elements, preferably deposited on a support, in particular an aluminum-based support.
  • the catalyst comprises palladium supported on alpha alumina.
  • the chlorotrifluoroethylene and the hydrogen are in anhydrous form.
  • the present invention relates to a process for the production of trifluoroethylene comprising a reaction step of hydrogenolysis of chlorotrifluoroethylene (CTFE) with hydrogen in the gaseous phase and preferably in the presence of a catalyst.
  • CFE chlorotrifluoroethylene
  • the method according to the invention described in the present application is implemented continuously.
  • the hydrogen is in anhydrous form.
  • the chlorotrifluoroethylene is in anhydrous form.
  • anhydrous refers to a mass water content of 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 under consideration.
  • the catalyst is based on a metal from columns 8 to 10 of the periodic table of elements.
  • the catalyst is based on a metal selected from the group consisting of Pd, Pt, Rh, and Ru; preferably palladium.
  • the catalyst is supported.
  • the support is preferably selected from the group consisting of activated carbon, an aluminum-based support, calcium carbonate, and graphite.
  • the support is based on aluminium.
  • the support is alumina.
  • the alumina may be alpha alumina.
  • the alumina comprises at least 90% alpha alumina. It has been observed that the conversion of the hydrogenolysis reaction is improved when the alumina is an alpha alumina.
  • the catalyst is more particularly palladium supported on alumina, advantageously palladium supported on an alumina comprising at least 90% alpha alumina, preferably palladium supported on an alpha alumina.
  • the palladium represents from 0.01% to 5% by weight based on the total weight of the catalyst, preferably from 0.1% to 2% by weight based on the total weight of the catalyst.
  • said catalyst comprises from 0.01% to 5% by weight of palladium supported on alumina, preferably the alumina comprises at least 90% alpha alumina, more preferably the alumina is an alpha alumina.
  • Said catalyst is preferably activated before its use in step a).
  • the activation of the catalyst is carried out at high temperature and in the presence of a reducing agent.
  • the reducing agent is chosen from the group consisting of hydrogen, carbon monoxide, nitrogen monoxide, formaldehyde, C1-C6 alkanes and Ci-Cio hydrohalocarbons, or a mixture thereof; preferably hydrogen or a C1-C10 hydrohalocarbon, or a mixture thereof; in particular hydrogen, chlorotrifluoroethylene, trifluoroethylene, chlorotrifluoroethane, trifluoroethane or difluoroethane or a mixture thereof.
  • the activation of the catalyst is carried out at a temperature comprised between 100°C and 400°C, in particular at a temperature comprised between 150°C and 350°C.
  • Said catalyst used in the present process can be regenerated.
  • This regeneration step can be implemented in a catalyst bed temperature range of between 90°C and 450°C.
  • the regeneration step is carried out in the presence of hydrogen.
  • the implementation of the regeneration step makes it possible to improve the yield of the reaction with respect to the initial yield before regeneration.
  • the regeneration step can be carried out at a catalyst bed temperature of 90°C to 300°C, preferably at a catalyst bed temperature of 90°C to 250°C, more preferably from 90°C to 200°C, in particular from 90°C to 175°C, more particularly at a temperature of the catalytic bed from 90°C to 150°C.
  • the implementation of 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. allows the desorption of compounds harmful to the activity of the catalyst and/or to limit phase transitions modifying the structure of the catalyst.
  • the regeneration step can be implemented at a temperature of the catalytic bed greater than 200° C., advantageously greater than 230° C., preferably greater than 250° C., in particular greater than 300 °C.
  • the regeneration step can be implemented periodically depending on the productivity or the conversion obtained in step a).
  • the regeneration stage can advantageously be implemented at a temperature of the catalytic bed of between 200° C. and 300° C., preferably between 205° C. and 295° C., more preferably between 210° C. and 290° C., in particularly between 215°C and 290°C, more particularly between 220°C and 285°C, preferably between 225°C and 280°C, more preferably between 230°C and 280°C.
  • 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 present process.
  • the present invention comprises, as mentioned above, a reaction step of hydrogenolysis of chlorotrifluoroethylene (CTFE) with hydrogen to produce a stream comprising trifluoroethylene.
  • the hydrogenolysis step is carried out in the presence of a catalyst and in the gas phase.
  • the hydrogenolysis step is carried out in the presence of a previously activated catalyst and in the gas phase.
  • the hydrogenolysis step consists of simultaneously introducing hydrogen, the CTFE and optionally an inert gas, such as nitrogen, in the gas phase and in the presence of said catalyst, preferably activated.
  • said step a) is carried out at a fixed catalyst bed temperature of between 50°C and 250°C.
  • Said step a) can be implemented at a temperature of the fixed catalytic bed of 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, in particular between 50°C and 200°C.
  • Said step a) can also be implemented at a fixed catalytic bed temperature of 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, in particular between 100°C and 250°C, more particularly between 120°C and 250°C.
  • Said step a) can also be implemented at a fixed catalytic bed temperature of 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, in particular between 100°C and 200°C, more particularly between 100°C and 180°C, preferably between 100°C and 160°C, particularly preferably between 120°C C and 160°C.
  • a fixed catalytic bed temperature of 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, in particular between 100°C and 200°C, more particularly between 100°C and 180°C, preferably between 100°C and 160°C, particularly preferably between 120°C C and 160°C.
  • the H2/CTFE molar ratio is between 0.5/1 to 2/1 and preferably between 1/1 to 1.2/1. If an inert gas such as nitrogen is present in step a), the nitrogen/hh molar ratio is between 0/1 to 2/1 and preferably between 0/1 to 1/1.
  • Step a) is preferably implemented at a pressure of 0.05 MPa to 1.1 MPa, more preferably from 0.05 MPa to 0.5 MPa, in particular at atmospheric pressure.
  • the contact time calculated as being the ratio between the volume, in liters, of catalyst and the total flow rate of the gaseous mixture, in normal liters per second, at the inlet of the reactor, is between 1 and 60 seconds, preferably between 5 and 45 seconds, in particular between 10 and 30 seconds, more particularly between 15 and 25 seconds.
  • the hydrogenolysis step (step a)) of the present process results in the production of a stream A comprising the trifluoroethylene.
  • Said stream A may also comprise unreacted hydrogen and unreacted chlorotrifluoroethylene.
  • Stream A may also include 1,1,2-trifluoroethane as by-products of the hydrogenolysis reaction.
  • Stream A can also comprise HCl or HF or a mixture of the two.
  • said stream A can also comprise 1,1-difluoroethane.
  • step b) comprises the steps of: bl) purification of said stream A comprising trifluoroethylene, chlorotrifluoroethylene and 1,1,2-trifluoroethane to form a stream C1 comprising trifluoroethylene and a stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane; b2) purification of stream C2 to produce said stream DI and a stream D2 comprising 1,1,2-trifluoroethane.
  • Said stream C1 comprising trifluoroethylene may also contain small amounts of chlorotrifluoroethylene and 1,1,2-trifluoroethane.
  • the mass content of chlorotrifluoroethylene in the stream Cl is less than 10%, preferably less than 5%, in particular less than 1% by weight based on the total weight of the stream Cl.
  • the mass content of 1 ,1,2-trifluoroethane in stream Cl is less than 10%, preferably less than 5%, in particular less than 1% by weight based on the total weight of stream Cl.
  • the purification thereof may comprise a plurality of steps.
  • steps i) and ii) below can be implemented to eliminate them.
  • step iii) below can be implemented.
  • step b1) of the present process may comprise the steps of: i) elimination of HF and/or HCl from said stream A recovered in step a) to form a gas mixture B; ii) Drying of mixture B from step i); iii) Treatment of stream B dried in step ii) to remove hydrogen and optionally inert gases and form a gas stream C; iv) Distillation of said stream C to form a stream C1 comprising trifluoroethylene and a stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
  • stream A is recovered at the reactor outlet in gaseous form.
  • stream A is first of all treated to remove HCl and HF.
  • Stream A is passed through water in a wash column followed by a wash with a dilute base such as NaOH or KOH.
  • the rest of the gas mixture made up of the unconverted reactants (H2 and CTFE), the dilution nitrogen (if present), the trifluoroethylene of the 1,1,2-trifluoroethane which form the gas mixture B, is directed to a dryer to remove traces of washing water.
  • the drying can be carried out using products such as sodium or magnesium calcium sulphate, calcium chloride, potassium carbonate, silica gel (silicagel) or zeolites.
  • a molecular sieve such as siliporite is used for drying.
  • Stream B thus dried is subjected to a stage of separation of hydrogen and inerts from the rest of the other products present in mixture B, by absorption/desorption in the presence of an alcohol containing 1 to 4 carbon atoms and preferably ethanol, at atmospheric pressure and at a temperature below room temperature, preferably below 10°C and even more preferably at a temperature of -25°C, for absorption.
  • the absorption of the organics is carried out in a countercurrent column with ethanol cooled to -25°C. The flow rate of ethanol is adjusted according to the flow rate of organics to be absorbed.
  • the organics are then recovered in the form of a gas mixture C, by heating the ethanol to its boiling point (desorption), to then be distilled.
  • the mixture C is then purified, preferably distilled, to form a stream C1 comprising trifluoroethylene and a stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
  • Stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane is recovered at the bottom of the column.
  • Streams A, B, C and C2 may also contain 1,1-difluoroethane.
  • step b2) makes it possible to produce said stream DI and a stream D2 comprising 1,1,2-trifluoroethane.
  • said stream DI comprises 1,1,2-trifluoroethane in a mass content of less than 15% based on the total weight of stream D1.
  • Said DI stream comprises, in addition to 1,1,2-trifluoroethane, chlorotrifluoroethylene and optionally 1,1-difluoroethane.
  • step b2) of the present process is carried out by distillation.
  • stream D1 is recovered at the top of the distillation column.
  • Stream D2 is recovered at the bottom of the distillation column.
  • Step b2) is preferably implemented so as to obtain a stream D1 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane in which the mass content of 1,1,2-trifluoroethane is less than 15% based on the weight total of said stream, preferably wherein the mass content of 1,1,2-trifluoroethane is from 0.01% to 15% based on the total weight of said stream.
  • said stream D1 comprises a mass content of 1,1,2-trifluoroethane of less than 10% based on the total weight of said stream D1, in particular from 0.01% to 10% of 1,1,2-trifluoroethane on based on the total weight of said stream D1.
  • said stream D1 comprises a mass content of chlorotrifluoroethylene greater than 60%, advantageously greater than 70%, preferably greater than 80%, more preferably greater than 85%, in particular greater than 90% based on the total weight of said stream D1.
  • step b2) is carried out by distillation at a pressure of less than 8 bara, preferably less than 6 bara. More preferably, step b2) is implemented at a pressure of 1 to 6 bara.
  • stage b2) is carried out by distillation, and the temperature at the top of the distillation column is below 40° C.; in particular the temperature at the head of the distillation column is between -40° C. and 40° C.; more particularly the temperature at the top of the distillation column is between -35°C and 30°C.
  • the DI stream is preferably in the form of an azeotropic or quasi-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
  • the DI stream as described in the present application is recycled to step a) of the present process.
  • the steps of the present method are repeated.
  • a fresh CTFE stream is mixed with the DI stream after it is recycled to maintain the proper CTFE/H2 ratio.
  • the catalyst thus charged was then activated in the following manner: the reaction tube was placed in a tube furnace and was fed with a flow of hydrogen (from 0.05 to 0.1 moles per gram of catalyst). The catalytic bed is heated to a temperature of 200° C. to 250° C. with a temperature gradient of 0.2° C./min. After this activation period, the tube was cooled to ambient temperature then was insulated to then be installed on a hydrogenolysis test bench.
  • test benches are used in parallel, each comprising a reactor prepared as described above.
  • the four benches were fed with 1 mol/h of starting composition and 1 mol/h of hydrogen in anhydrous form.
  • the temperature of the jacket of the reactor is 25°C.
  • the contact time calculated as being the ratio between the volume in liters of catalyst and the sum of the flow rates of the reactants in normal liters per second, was of the order of 22 seconds. Tests are carried out using different starting compositions.
  • Comparative Example 1 was implemented from chlorotrifluoroethylene.
  • Example 2 according to the invention was implemented from the chlorotrifluoroethylene used in the comparative example to which was added 1,1,2-trifluoroethane (3.9%).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The present invention relates to a method for producing trifluoroethylene in a reactor equipped with a fixed catalyst bed comprising a catalyst, said method comprising the steps of: a) reacting the chlorotrifluoroethylene with hydrogen in the presence of the catalyst and in the aqueous phase to produce a stream A comprising trifluoroethylene; b) treating said stream A under conditions which are sufficient to produce a stream D1 comprising 1,1,2-trifluoroethane in a content of less than 15% by weight on the basis of the total weight of said stream D1, c) recycling the stream D1 to step a).

Description

Procédé de production du trifluoroéthylène et recyclage du flux de chlorotrifluoroéthylène Trifluoroethylene production process and recycling of the chlorotrifluoroethylene stream
Domaine technique Technical area
La présente invention concerne un procédé de production d'hydrofluorooléfines. En particulier, la présente invention concerne un procédé de production du trifluoroéthylène (VF3) par hydrogénolyse du chlorotrifluoroéthylène. The present invention relates to a process for the production of hydrofluoroolefins. In particular, the present invention relates to a process for the production of trifluoroethylene (VF3) by hydrogenolysis of chlorotrifluoroethylene.
Arrière-plan technologique de l'invention Technological background of the invention
Les oléfines fluorées, comme le VF3, sont connues et sont utilisées comme monomères ou co- monomères pour la fabrication de polymères fluorocarbonés présentant des caractéristiques remarquables, en particulier une excellente tenue chimique et une bonne résistance thermique. Le trifluoroéthylène est un gaz dans les conditions normales de pression et de température. Les principaux risques liés à l'utilisation de ce produit concernent son inflammabilité, sa propension à l'auto-polymérisation lorsqu'il n'est pas stabilisé, son explosivité due à son instabilité chimique et sa supposée sensibilité à la peroxydation, par analogie avec d'autres oléfines halogénées. Le trifluoroéthylène présente la particularité d'être extrêmement inflammable, avec une limite inférieure d'explosivité (LIE) d'environ 10% et une limite supérieure d'explosivité (LSE) d'environ 30%. Le danger majeur est cependant associé à la propension du VF3 à se décomposer violemment et de façon explosive dans certaines conditions de pression en présence d'une source d'énergie, même en l'absence d'oxygène. Fluorinated olefins, such as VF3, are known and are used as monomers or comonomers for the manufacture of fluorocarbon polymers having remarkable characteristics, in particular excellent chemical behavior and good heat resistance. Trifluoroethylene is a gas under normal conditions of pressure and temperature. The main risks associated with the use of this product concern its flammability, its propensity for self-polymerization when it is not stabilized, its explosiveness due to its chemical instability and its supposed sensitivity to peroxidation, by analogy with other halogenated olefins. Trifluoroethylene has the particularity of being extremely flammable, with a lower explosive limit (LEL) of approximately 10% and an upper explosive limit (UEL) of approximately 30%. The major danger, however, is associated with the propensity of VF3 to decompose violently and explosively under certain pressure conditions in the presence of an energy source, even in the absence of oxygen.
Compte tenu des principaux risques ci-dessus, la synthèse ainsi que le stockage du VF3 posent des problèmes particuliers et imposent tout au long de ces processus des règles strictes de sécurité. Une voie connue de préparation du trifluoroéthylène utilise comme produits de départ le chlorotrifluoroéthylène (CTFE) et l'hydrogène en présence d'un catalyseur et en phase gazeuse. On connaît par WO 2013/128102 un procédé de production du trifluoroéthylène par hydrogénolyse du CTFE en phase gazeuse et en présence d'un catalyseur à base d'un métal du groupe VIII à pression atmosphérique et à des températures peu élevées. Given the main risks above, the synthesis as well as the storage of VF 3 pose particular problems and impose strict safety rules throughout these processes. A known way of preparing trifluoroethylene uses as starting materials chlorotrifluoroethylene (CTFE) and hydrogen in the presence of a catalyst and in the gas phase. WO 2013/128102 discloses a process for producing trifluoroethylene by hydrogenolysis of CTFE in the gas phase and in the presence of a catalyst based on a group VIII metal at atmospheric pressure and at low temperatures.
Résumé de l'invention Selon un premier aspect, la présente invention concerne un procédé de production du trifluoroéthylène dans un réacteur muni d'un lit catalytique fixe comprenant un catalyseur, ledit procédé comprenant les étapes de : a) réaction du chlorotrifluoroéthylène avec de l'hydrogène en présence du catalyseur et en phase gazeuse pour produire un courant A comprenant du trifluoroéthylène ; b) traitement dudit courant A dans des conditions suffisantes pour produire un courant DI comprenant du 1,1,2-trifluoroéthane dans une teneur inférieure à 15% en poids sur base du poids total dudit courant Dl, c) recyclage du courant Dl à l'étape a). Summary of the Invention According to a first aspect, the present invention relates to a process for producing trifluoroethylene in a reactor provided with a fixed catalytic bed comprising a catalyst, said process comprising the steps of: a) reaction of chlorotrifluoroethylene with hydrogen in the presence of the catalyst and in the gas phase to produce a stream A comprising trifluoroethylene; b) treatment of said stream A under conditions sufficient to produce a stream DI comprising 1,1,2-trifluoroethane in a content of less than 15% by weight based on the total weight of said stream D1, c) recycling of stream D1 to step a).
Selon un mode de réalisation préféré, le courant A comprend également, outre le trifluoroéthylène, du chlorotrifluoroéthylène n'ayant pas réagi et 1,1,2-trifluoroéthane. According to a preferred embodiment, stream A also comprises, in addition to trifluoroethylene, unreacted chlorotrifluoroethylene and 1,1,2-trifluoroethane.
Selon un mode de réalisation préféré, le courant Dl comprend également du chlorotrifluoroéthylène dans une teneur massique supérieure à 60% en poids sur base du poids total dudit courant Dl. According to a preferred embodiment, stream D1 also comprises chlorotrifluoroethylene in a mass content greater than 60% by weight based on the total weight of said stream D1.
Selon un mode de réalisation préféré, le courant Dl est sous la forme d'une composition azéotropique ou quasi-azéotropique comprenant chlorotrifluoroéthylène et 1,1,2- trifluoroéthane. According to a preferred embodiment, stream D1 is in the form of an azeotropic or quasi-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
La présence et la formation d'un azéotrope ou d'un quasi-azéotrope entre le chlorotrifluoroéthylène et le 1,1,2-trifluoroéthane a été identifié. L'existence d'un azéotrope complique le processus de purification du trifluoroéthylène et en particulier le processus de recyclage du chlorotrifluoroéthylène. Cependant, il a été observé de manière surprenante que le recyclage d'une partie de l'azéotrope n'était pas néfaste à la production du trifluoroéthylène. En effet, il a été observé que le rendement de la réaction d'hydrogénolyse n'était pas impacté par une teneur de 1,1,2-trifluoroéthane inférieure à 15% dans le flux de recyclage. Ainsi, il n'est pas nécessaire d'éliminer totalement le 1,1,2-trifluoroéthane du flux de recyclage. Ceci permet de simplifier les opérations de purification du flux de recyclage et représente donc un gain économique important. The presence and formation of an azeotrope or quasi-azeotrope between chlorotrifluoroethylene and 1,1,2-trifluoroethane has been identified. The existence of an azeotrope complicates the trifluoroethylene purification process and in particular the chlorotrifluoroethylene recycling process. However, it was surprisingly observed that the recycling of part of the azeotrope was not detrimental to the production of trifluoroethylene. Indeed, it was observed that the yield of the hydrogenolysis reaction was not impacted by a content of 1,1,2-trifluoroethane of less than 15% in the recycle stream. Thus, it is not necessary to totally eliminate the 1,1,2-trifluoroethane from the recycle stream. This makes it possible to simplify the purification operations of the recycling flow and therefore represents a significant economic gain.
Selon un mode de réalisation préféré, le courant A comprend du trifluoroéthylène, du chlorotrifluoroéthylène et 1,1,2-trifluoroéthane et l'étape b) comprend les étapes de : bl) purification dudit courant A comprenant du trifluoroéthylène, du chlorotrifluoroéthylène et 1,1,2-trifluoroéthane pour former un courant Cl comprenant du trifluoroéthylène et un courant C2 comprenant chlorotrifluoroéthylène et 1,1,2-trifluoroéthane ; b2) purification du courant C2 pour produire ledit courant Dl et un courant D2 comprenant du 1,1,2-trifluoroéthane. Selon un mode de réalisation préféré, l'étape b2) est mise en oeuvre par distillation à une pression inférieure à 8 bara, de préférence inférieure à 6 bara. According to a preferred embodiment, stream A comprises trifluoroethylene, chlorotrifluoroethylene and 1,1,2-trifluoroethane and step b) comprises the steps of: bl) purification of said stream A comprising trifluoroethylene, chlorotrifluoroethylene and 1, 1,2-trifluoroethane to form a C1 stream comprising trifluoroethylene and a C2 stream comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane; b2) purification of stream C2 to produce said stream D1 and a stream D2 comprising 1,1,2-trifluoroethane. According to a preferred embodiment, stage b2) is carried out by distillation at a pressure below 8 bara, preferably below 6 bara.
Selon un mode de réalisation préféré, l'étape b2) est mise en oeuvre par distillation, et la température en tête de colonne de distillation est inférieure à 40°C. According to a preferred embodiment, stage b2) is carried out by distillation, and the temperature at the top of the distillation column is below 40°C.
Selon un mode de réalisation préféré, ledit catalyseur est un catalyseur à base d'un métal des colonnes 8 à 10 du tableau périodique des éléments, de préférence déposé sur un support, en particulier un support à base d'aluminium. According to a preferred embodiment, said catalyst is a catalyst based on a metal from columns 8 to 10 of the periodic table of the elements, preferably deposited on a support, in particular an aluminum-based support.
Selon un mode de réalisation préféré, le catalyseur comprend du palladium supporté sur de l'alumine alpha. According to a preferred embodiment, the catalyst comprises palladium supported on alpha alumina.
Selon un mode de réalisation préféré, le chlorotrifluoroéthylène et l'hydrogène sont sous forme anhydre. According to a preferred embodiment, the chlorotrifluoroethylene and the hydrogen are in anhydrous form.
Description détaillée de l'invention Detailed description of the invention
La présente invention se rapporte à un procédé de production du trifluoroéthylène comprenant une étape de réaction d'hydrogénolyse du chlorotrifluoroéthylène (CTFE) avec de l'hydrogène en phase gazeuse et de préférence en présence d'un catalyseur. The present invention relates to a process for the production of trifluoroethylene comprising a reaction step of hydrogenolysis of chlorotrifluoroethylene (CTFE) with hydrogen in the gaseous phase and preferably in the presence of a catalyst.
Selon un mode de réalisation préféré, le procédé selon l'invention décrit dans la présente demande est mis en oeuvre en continu. According to a preferred embodiment, the method according to the invention described in the present application is implemented continuously.
Selon un mode de réalisation préféré, dans le procédé décrit dans la présente demande, l'hydrogène est sous forme anhydre. According to a preferred embodiment, in the process described in the present application, the hydrogen is in anhydrous form.
Selon un mode de réalisation préféré, dans le procédé décrit dans la présente demande, le chlorotrifluoroéthylène est sous forme anhydre. According to a preferred embodiment, in the process described in the present application, the chlorotrifluoroethylene is in anhydrous form.
La mise en oeuvre des procédés selon l'invention en présence d'hydrogène et/ou du chlorotrifluoroéthylène anhydre permet d'augmenter efficacement la durée de vie du catalyseur et ainsi la productivité globale du procédé. Le terme anhydre se réfère à une teneur massique en eau inférieure à 1000 ppm, avantageusement 500 ppm, de préférence inférieure à 200 ppm, en particulier inférieure à 100 ppm sur base du poids total du composé considéré. The implementation of the processes according to the invention in the presence of hydrogen and/or anhydrous chlorotrifluoroethylene makes it possible to effectively increase the lifetime of the catalyst and thus the overall productivity of the process. The term anhydrous refers to a mass water content of 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 under consideration.
Catalyseur Catalyst
De préférence, le catalyseur est à base d'un métal des colonnes 8 à 10 du tableau périodique des éléments. En particulier, le catalyseur est à base d'un métal sélectionné parmi le groupe consistant en Pd, Pt, Rh, et Ru ; de préférence palladium. De préférence, le catalyseur est supporté. Le support est de préférence sélectionné parmi le groupe consistant en le charbon actif, un support à base d'aluminium, le carbonate de calcium, et le graphite. De préférence, le support est à base d'aluminium. En particulier, le support est de l'alumine. L'alumine peut être de l'alumine alpha. De préférence, l'alumine comprend au moins 90% d'alumine alpha. Il a été observé que la conversion de la réaction d'hydrogénolyse était améliorée lorsque l'alumine est une alumine alpha. Ainsi, le catalyseur est plus particulièrement du palladium supporté sur alumine, avantageusement du palladium supporté sur une alumine comprenant au moins 90% d'alumine alpha, de préférence du palladium supporté sur une alumine alpha. Preferably, the catalyst is based on a metal from columns 8 to 10 of the periodic table of elements. In particular, the catalyst is based on a metal selected from the group consisting of Pd, Pt, Rh, and Ru; preferably palladium. Preferably, the catalyst is supported. The support is preferably selected from the group consisting of activated carbon, an aluminum-based support, calcium carbonate, and graphite. Preferably, the support is based on aluminium. In particular, the support is alumina. The alumina may be alpha alumina. Preferably, the alumina comprises at least 90% alpha alumina. It has been observed that the conversion of the hydrogenolysis reaction is improved when the alumina is an alpha alumina. Thus, the catalyst is more particularly palladium supported on alumina, advantageously palladium supported on an alumina comprising at least 90% alpha alumina, preferably palladium supported on an alpha alumina.
De préférence, le palladium représente de 0,01% à 5% en poids sur base du poids total du catalyseur, de préférence de 0,1% à 2% en poids sur base du poids total du catalyseur. Preferably, the palladium represents from 0.01% to 5% by weight based on the total weight of the catalyst, preferably from 0.1% to 2% by weight based on the total weight of the catalyst.
En particulier, ledit catalyseur comprend de 0,01% à 5% en poids de palladium supporté sur alumine, de préférence l'alumine comprend au moins 90% d'alumine alpha, plus préférentiellement l'alumine est une alumine alpha. In particular, said catalyst comprises from 0.01% to 5% by weight of palladium supported on alumina, preferably the alumina comprises at least 90% alpha alumina, more preferably the alumina is an alpha alumina.
Activation du catalyseur Activation of the catalyst
Ledit catalyseur est de préférence activé avant son utilisation à l'étape a). De préférence, l'activation du catalyseur est mise en oeuvre à haute température et en présence d'un agent réducteur. Selon un mode de réalisation particulier, l'agent réducteur est choisi dans le groupe constitué par l'hydrogène, le monoxyde de carbone, le monoxyde d'azote, le formaldéhyde, les alcanes en C1-C6 et les hydrohalocarbures en Ci-Cio, ou un mélange de ceux-ci ; de préférence l'hydrogène ou un hydrohalocarbure en Ci-Cio, ou un mélange de ceux-ci ; en particulier l'hydrogène, chlorotrifluoroéthylène, trifluoroéthylène, chlorotrifluoroéthane, trifluoroéthane ou difluoroéthane ou un mélange de ceux-ci. De préférence, l'activation du catalyseur est mise en oeuvre à une température comprise entre 100°C et 400°C, en particulier à une température comprise entre 150°C et 350°C. Said catalyst is preferably activated before its use in step a). Preferably, the activation of the catalyst is carried out at high temperature and in the presence of a reducing agent. According to a particular embodiment, the reducing agent is chosen from the group consisting of hydrogen, carbon monoxide, nitrogen monoxide, formaldehyde, C1-C6 alkanes and Ci-Cio hydrohalocarbons, or a mixture thereof; preferably hydrogen or a C1-C10 hydrohalocarbon, or a mixture thereof; in particular hydrogen, chlorotrifluoroethylene, trifluoroethylene, chlorotrifluoroethane, trifluoroethane or difluoroethane or a mixture thereof. Preferably, the activation of the catalyst is carried out at a temperature comprised between 100°C and 400°C, in particular at a temperature comprised between 150°C and 350°C.
Régénération du catalyseur Catalyst regeneration
Ledit catalyseur utilisé dans le présent procédé peut être régénéré. Cette étape de régénération peut être mise en oeuvre dans une gamme de température du lit catalytique comprise entre 90°C et 450°C. De préférence, l'étape de régénération est mise en oeuvre en présence d'hydrogène. La mise en oeuvre de l'étape de régénération permet d'améliorer le rendement de la réaction par rapport au rendement initial avant régénération. Selon un mode de réalisation préféré, l'étape de régénération peut être mise en oeuvre à une température du lit catalytique de 90°C à 300°C, de préférence à une température du lit catalytique de 90°C à 250°C, plus préférentiellement de 90°C à 200°C, en particulier de 90°C à 175°C, plus particulièrement à une température du lit catalytique de 90°C à 150°C. En particulier, la mise en oeuvre de l'étape de régénération à une température basse, par exemple de 90°C à 200°C ou de 90°C à 175°C ou de 90°C à 150°C permet la désorption de composés néfastes à l'activité du catalyseur et/ou de limiter des transitions de phase modifiant la structure du catalyseur. Said catalyst used in the present process can be regenerated. This regeneration step can be implemented in a catalyst bed temperature range of between 90°C and 450°C. Preferably, the regeneration step is carried out in the presence of hydrogen. The implementation of the regeneration step makes it possible to improve the yield of the reaction with respect to the initial yield before regeneration. According to a preferred embodiment, the regeneration step can be carried out at a catalyst bed temperature of 90°C to 300°C, preferably at a catalyst bed temperature of 90°C to 250°C, more preferably from 90°C to 200°C, in particular from 90°C to 175°C, more particularly at a temperature of the catalytic bed from 90°C to 150°C. In particular, the implementation of 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. allows the desorption of compounds harmful to the activity of the catalyst and/or to limit phase transitions modifying the structure of the catalyst.
Selon un autre mode de réalisation préféré, l'étape de régénération peut être mise en oeuvre à une température du lit catalytique supérieure à 200°C, avantageusement supérieure à 230°C, de préférence supérieure à 250°C, en particulier supérieure à 300°C. L'étape de régénération peut être mise en oeuvre périodiquement en fonction de la productivité ou de la conversion obtenue à l'étape a). L'étape de régénération peut être mise en oeuvre avantageusement à une température du lit catalytique comprise entre 200°C et 300°C, de préférence entre 205°C et 295°C, plus préférentiellement entre 210°C et 290°C, en particulier entre 215°C et 290°C, plus particulièrement entre 220°C et 285°C, de manière privilégiée entre 225°C et 280°C, de manière plus privilégiée entre 230°C et 280°C. Alternativement, l'étape de régénération peut être mise en oeuvre à une température comprise entre 300°C et 450°C, de préférence entre 300°C et 400°C. Le catalyseur régénéré peut être réutilisé à l'étape a) du présent procédé. According to another preferred embodiment, the regeneration step can be implemented at a temperature of the catalytic bed greater than 200° C., advantageously greater than 230° C., preferably greater than 250° C., in particular greater than 300 °C. The regeneration step can be implemented periodically depending on the productivity or the conversion obtained in step a). The regeneration stage can advantageously be implemented at a temperature of the catalytic bed of between 200° C. and 300° C., preferably between 205° C. and 295° C., more preferably between 210° C. and 290° C., in particularly between 215°C and 290°C, more particularly between 220°C and 285°C, preferably between 225°C and 280°C, more preferably 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 present process.
Réaction d'hydrogénolyse Hydrogenolysis reaction
La présente invention comprend, comme mentionné ci-dessus, une étape de réaction d'hydrogénolyse du chlorotrifluoroéthylène (CTFE) avec de l'hydrogène pour produire un courant comprenant du trifluoroéthylène. L'étape d'hydrogénolyse est mise en oeuvre en présence d'un catalyseur et en phase gazeuse. De préférence, l'étape d'hydrogénolyse est mise en oeuvre en présence d'un catalyseur préalablement activé et en phase gazeuse. L'étape d'hydrogénolyse consiste à introduire simultanément de l'hydrogène, le CTFE et optionnellement un gaz inerte, comme l'azote, en phase gazeuse et en présence dudit catalyseur, de préférence activé. The present invention comprises, as mentioned above, a reaction step of hydrogenolysis of chlorotrifluoroethylene (CTFE) with hydrogen to produce a stream comprising trifluoroethylene. The hydrogenolysis step is carried out in the presence of a catalyst and in the gas phase. Preferably, the hydrogenolysis step is carried out in the presence of a previously activated catalyst and in the gas phase. The hydrogenolysis step consists of simultaneously introducing hydrogen, the CTFE and optionally an inert gas, such as nitrogen, in the gas phase and in the presence of said catalyst, preferably activated.
De préférence, ladite étape a) est mise en oeuvre à une température du lit catalytique fixe comprise entre 50°C et 250°C. Ladite étape a) peut être mise en oeuvre à une température du lit catalytique fixe comprise entre 50°C et 240°C, avantageusement entre 50°C et 230°C, de préférence entre 50°C et 220°C, plus préférentiellement entre 50°C et 210°C, en particulier entre 50°C et 200°C. Ladite étape a) peut également être mise en œuvre à une température du lit catalytique fixe comprise entre 60°C et 250°C, avantageusement entre 70°C et 250°C, de préférence entre 80°C et 250°C, plus préférentiellement entre 90°C et 250°C, en particulier entre 100°C et 250°C, plus particulièrement entre 120°C et 250°C. Ladite étape a) peut également être mise en œuvre à une température du lit catalytique fixe comprise entre 60°C et 240°C, avantageusement entre 70°C et 230°C, de préférence entre 80°C et 220°C, plus préférentiellement entre 90°C et 210°C, en particulier entre 100°C et 200°C, plus particulièrement entre 100°C et 180°C, de manière privilégiée entre 100°C et 160°C, de manière particulièrement préférée entre 120°C et 160°C. Preferably, said step a) is carried out at a fixed catalyst bed temperature of between 50°C and 250°C. Said step a) can be implemented at a temperature of the fixed catalytic bed of 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, in particular between 50°C and 200°C. Said step a) can also be implemented at a fixed catalytic bed temperature of 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, in particular between 100°C and 250°C, more particularly between 120°C and 250°C. Said step a) can also be implemented at a fixed catalytic bed temperature of 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, in particular between 100°C and 200°C, more particularly between 100°C and 180°C, preferably between 100°C and 160°C, particularly preferably between 120°C C and 160°C.
Le rapport molaire H2/CTFE est compris entre 0,5/1 à 2/1 et de préférence compris entre 1/1 à 1,2/1. Si un gaz inerte comme de l'azote est présent à l'étape a), le rapport molaire azote/hh est compris entre 0/1 à 2/1 et de préférence compris entre 0/1 à 1/1. The H2/CTFE molar ratio is between 0.5/1 to 2/1 and preferably between 1/1 to 1.2/1. If an inert gas such as nitrogen is present in step a), the nitrogen/hh molar ratio is between 0/1 to 2/1 and preferably between 0/1 to 1/1.
L'étape a) est de préférence mise en œuvre à une pression de 0,05 MPa à 1,1 MPa, plus préférentiellement de 0,05 Mpa à 0,5 MPa, en particulier à pression atmosphérique. Step a) is preferably implemented at a pressure of 0.05 MPa to 1.1 MPa, more preferably from 0.05 MPa to 0.5 MPa, in particular at atmospheric pressure.
Le temps de contact calculé comme étant le rapport entre le volume, en litre, de catalyseur et le débit total du mélange gazeux, en normaux litres par seconde, à l'entrée du réacteur, est compris entre 1 et 60 secondes, de préférence entre 5 et 45 secondes, en particulier entre 10 et 30 secondes, plus particulièrement entre 15 et 25 secondes. The contact time calculated as being the ratio between the volume, in liters, of catalyst and the total flow rate of the gaseous mixture, in normal liters per second, at the inlet of the reactor, is between 1 and 60 seconds, preferably between 5 and 45 seconds, in particular between 10 and 30 seconds, more particularly between 15 and 25 seconds.
Traitement du flux de réaction Reaction Flow Processing
L'étape d'hydrogénolyse (étape a)) du présent procédé aboutit à la production d'un courant A comprenant le trifluoroéthylène. Ledit courant A peut également comprendre de l'hydrogène n'ayant pas réagi et du chlorotrifluoroéthylène n'ayant pas réagi. Le courant A peut également comprendre du 1,1,2-trifluoroéthane comme sous-produits de la réaction d'hydrogénolyse. Le courant A peut comprendre également du HCl ou du HF ou un mélange des deux. Optionnellement, ledit courant A peut également comprendre du 1,1-difluoroéthane. The hydrogenolysis step (step a)) of the present process results in the production of a stream A comprising the trifluoroethylene. Said stream A may also comprise unreacted hydrogen and unreacted chlorotrifluoroethylene. Stream A may also include 1,1,2-trifluoroethane as by-products of the hydrogenolysis reaction. Stream A can also comprise HCl or HF or a mixture of the two. Optionally, said stream A can also comprise 1,1-difluoroethane.
Comme mentionné ci-dessus, l'étape b) comprend les étapes de : bl) purification dudit courant A comprenant du trifluoroéthylène, du chlorotrifluoroéthylène et 1,1,2-trifluoroéthane pour former un courant Cl comprenant du trifluoroéthylène et un courant C2 comprenant chlorotrifluoroéthylène et 1,1,2- trifluoroéthane ; b2) purification du courant C2 pour produire ledit courant DI et un courant D2 comprenant du 1,1,2-trifluoroéthane. Ledit courant Cl comprenant du trifluoroéthylène peut également contenir de faibles quantités de chlorotrifluoroéthylène et de 1,1,2-trifluoroéthane. De préférence, la teneur massique en chlorotrifluoroéthylène dans le courant Cl est inférieure à 10%, de préférence inférieure à 5%, en particulier inférieure à 1% en poids sur base du poids total du courant Cl. De préférence, la teneur massique en 1,1,2-trifluoroéthane dans le courant Cl est inférieure à 10%, de préférence inférieure à 5%, en particulier inférieure à 1% en poids sur base du poids total du courant Cl. As mentioned above, step b) comprises the steps of: bl) purification of said stream A comprising trifluoroethylene, chlorotrifluoroethylene and 1,1,2-trifluoroethane to form a stream C1 comprising trifluoroethylene and a stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane; b2) purification of stream C2 to produce said stream DI and a stream D2 comprising 1,1,2-trifluoroethane. Said stream C1 comprising trifluoroethylene may also contain small amounts of chlorotrifluoroethylene and 1,1,2-trifluoroethane. Preferably, the mass content of chlorotrifluoroethylene in the stream Cl is less than 10%, preferably less than 5%, in particular less than 1% by weight based on the total weight of the stream Cl. Preferably, the mass content of 1 ,1,2-trifluoroethane in stream Cl is less than 10%, preferably less than 5%, in particular less than 1% by weight based on the total weight of stream Cl.
En fonction de la composition dudit courant A, la purification de celui-ci (étape bl)) peut comprendre une pluralité d'étapes. Ainsi, si ledit courant A comprend des composés acides tels que HF ou HCl, les étapes i) et ii) ci-dessous peuvent être mises en oeuvre pour les éliminer.Depending on the composition of said stream A, the purification thereof (step b1)) may comprise a plurality of steps. Thus, if said stream A comprises acid compounds such as HF or HCl, steps i) and ii) below can be implemented to eliminate them.
Si ledit courant A comprend de l'hydrogène et éventuellement des gaz inertes, l'étape iii) ci- dessous peut être mise en oeuvre. If said stream A comprises hydrogen and optionally inert gases, step iii) below can be implemented.
Selon un mode de réalisation particulier, l'étape bl) du présent procédé peut comprendre les étapes de : i) Elimination de HF et/ou HCl dudit courant A récupéré à l'étape a) pour former un mélange gazeux B ; ii) Séchage du mélange B issu de l'étape i) ; iii) Traitement du courant B séché à l'étape ii) pour éliminer l'hydrogène et optionnellement des gaz inertes et former un courant gazeux C ; iv) Distillation dudit courant C pour former un courant Cl comprenant du trifluoroéthylène et un courant C2 comprenant du chlorotrifluoroéthylène et 1,1,2- trifluoroéthane. According to a particular embodiment, step b1) of the present process may comprise the steps of: i) elimination of HF and/or HCl from said stream A recovered in step a) to form a gas mixture B; ii) Drying of mixture B from step i); iii) Treatment of stream B dried in step ii) to remove hydrogen and optionally inert gases and form a gas stream C; iv) Distillation of said stream C to form a stream C1 comprising trifluoroethylene and a stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
Le paragraphe ci-dessous détaille les étapes i) à iv). The paragraph below details steps i) to iv).
Le courant A est récupéré en sortie de réacteur sous forme gazeuse. De préférence, en sortie du réacteur d'hydrogénolyse, le courant A est tout d'abord traité pour éliminer HCl et HF. Le courant A est passé dans de l'eau dans une colonne de lavage puis par un lavage avec une base diluée telle que NaOH ou KOH. Le reste du mélange gazeux, constitué des réactifs non convertis (H2 et CTFE), de l'azote de dilution (si présent), du trifluoroéthylène du 1,1,2-trifluoroéthane qui forment le mélange gazeux B, est dirigé vers un sécheur afin d'éliminer les traces d'eau de lavage. Le séchage peut être réalisé à l'aide de produits tels que le sulfate de calcium de sodium ou de magnésium, le chlorure de calcium, le carbonate de potassium, le gel de silice (silicagel) ou les zéolites. Dans un mode de réalisation, on utilise pour le séchage un tamis moléculaire (zéolite) tel que la siliporite. Le flux B ainsi séché est soumis à une étape de séparation de l'hydrogène et des inertes du reste des autres produits présents dans le mélange B, par absorption/désorption en présence d'un alcool comportant de 1 à 4 atomes de carbone et de préférence l'éthanol, à pression atmosphérique et à une température inférieure à la température ambiante, de préférence inférieure à 10°C et de manière encore plus préférée à une température de -25°C, pour l'absorption. Dans un mode de réalisation, l'absorption des organiques est réalisée dans une colonne à contre-courant avec de l'éthanol refroidi à -25°C. Le débit d'éthanol est réglé en fonction du débit d'organiques à absorber. L'hydrogène et les gaz inertes, insolubles dans l'éthanol à cette température, sont éliminés en tête de colonne d'absorption. Les organiques sont ensuite récupérés sous forme d'un mélange gazeux C, par chauffage de l'éthanol à son point d'ébullition (désorption), pour être ensuite distillés. Le mélange C est ensuite purifié, de préférence distillé, pour former un courant Cl comprenant du trifluoroéthylène et un courant C2 comprenant chlorotrifluoroéthylène et 1,1,2-trifluoroéthane. Le courant C2 comprenant chlorotrifluoroéthylène et 1,1,2-trifluoroéthane est récupéré en pied de colonne. Les courants A, B, C et C2 peuvent également contenir du 1,1-difluoroéthane.Current A is recovered at the reactor outlet in gaseous form. Preferably, at the outlet of the hydrogenolysis reactor, stream A is first of all treated to remove HCl and HF. Stream A is passed through water in a wash column followed by a wash with a dilute base such as NaOH or KOH. The rest of the gas mixture, made up of the unconverted reactants (H2 and CTFE), the dilution nitrogen (if present), the trifluoroethylene of the 1,1,2-trifluoroethane which form the gas mixture B, is directed to a dryer to remove traces of washing water. The drying can be carried out using products such as sodium or magnesium calcium sulphate, calcium chloride, potassium carbonate, silica gel (silicagel) or zeolites. In one embodiment, a molecular sieve (zeolite) such as siliporite is used for drying. Stream B thus dried is subjected to a stage of separation of hydrogen and inerts from the rest of the other products present in mixture B, by absorption/desorption in the presence of an alcohol containing 1 to 4 carbon atoms and preferably ethanol, at atmospheric pressure and at a temperature below room temperature, preferably below 10°C and even more preferably at a temperature of -25°C, for absorption. In one embodiment, the absorption of the organics is carried out in a countercurrent column with ethanol cooled to -25°C. The flow rate of ethanol is adjusted according to the flow rate of organics to be absorbed. Hydrogen and inert gases, insoluble in ethanol at this temperature, are eliminated at the top of the absorption column. The organics are then recovered in the form of a gas mixture C, by heating the ethanol to its boiling point (desorption), to then be distilled. The mixture C is then purified, preferably distilled, to form a stream C1 comprising trifluoroethylene and a stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane. Stream C2 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane is recovered at the bottom of the column. Streams A, B, C and C2 may also contain 1,1-difluoroethane.
La purification dudit mélange C2 (étape b2)) permet de produire ledit courant DI et un courant D2 comprenant du 1,1,2-trifluoroéthane. Comme mentionné ci-dessus, ledit courant DI comprend du 1,1,2-trifluoroéthane dans une teneur massique inférieur à 15% sur base du poids total du courant Dl. Ledit courant DI comprend, outre le 1,1,2-trifluoroéthane, du chlorotrifluoroéthylène et optionnellement du 1,1-difluoroéthane. De préférence, l'étape b2) du présent procédé est mise en oeuvre par distillation. Ainsi, le courant Dl est récupéré en tête de colonne de distillation. Le courant D2 est quant à lui récupéré en pied de colonne de distillation. The purification of said mixture C2 (step b2)) makes it possible to produce said stream DI and a stream D2 comprising 1,1,2-trifluoroethane. As mentioned above, said stream DI comprises 1,1,2-trifluoroethane in a mass content of less than 15% based on the total weight of stream D1. Said DI stream comprises, in addition to 1,1,2-trifluoroethane, chlorotrifluoroethylene and optionally 1,1-difluoroethane. Preferably, step b2) of the present process is carried out by distillation. Thus, stream D1 is recovered at the top of the distillation column. Stream D2 is recovered at the bottom of the distillation column.
L'étape b2) est de préférence mise en oeuvre de sorte à obtenir un courant Dl comprenant chlorotrifluoroéthylène et 1,1,2-trifluoroéthane dans lequel la teneur massique en 1,1,2- trifluoroéthane est inférieure à 15% sur base du poids total dudit courant, de préférence dans lequel la teneur massique en 1,1,2-trifluoroéthane est de 0,01% à 15% sur base du poids total dudit courant. Plus préférentiellement, ledit courant Dl comprend une teneur massique en 1,1,2-trifluoroéthane inférieure à 10% sur base du poids total dudit courant Dl, en particulier de 0,01% à 10% de 1,1,2-trifluoroéthane sur base du poids total dudit courant Dl. Step b2) is preferably implemented so as to obtain a stream D1 comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane in which the mass content of 1,1,2-trifluoroethane is less than 15% based on the weight total of said stream, preferably wherein the mass content of 1,1,2-trifluoroethane is from 0.01% to 15% based on the total weight of said stream. More preferably, said stream D1 comprises a mass content of 1,1,2-trifluoroethane of less than 10% based on the total weight of said stream D1, in particular from 0.01% to 10% of 1,1,2-trifluoroethane on based on the total weight of said stream D1.
Selon un mode de réalisation préféré, ledit courant Dl comprend une teneur massique en chlorotrifluoroéthylène supérieure à 60%, avantageusement supérieure à 70%, de préférence supérieure à 80%, plus préférentiellement supérieure à 85%, en particulier supérieure à 90% sur base du poids total dudit courant Dl. De préférence, l'étape b2) est mise en œuvre par distillation à une pression inférieure à 8 bara, de préférence inférieure à 6 bara. Plus préférentiellement, l'étape b2) est mise en œuvre à une pression de 1 à 6 bara. According to a preferred embodiment, said stream D1 comprises a mass content of chlorotrifluoroethylene greater than 60%, advantageously greater than 70%, preferably greater than 80%, more preferably greater than 85%, in particular greater than 90% based on the total weight of said stream D1. Preferably, step b2) is carried out by distillation at a pressure of less than 8 bara, preferably less than 6 bara. More preferably, step b2) is implemented at a pressure of 1 to 6 bara.
De préférence, l'étape b2) est mise en œuvre par distillation, et la température en tête de colonne de distillation est inférieure à 40°C ; en particulier la température en tête de colonne de distillation est comprise entre -40°C et 40°C ; plus particulièrement la température en tête de colonne de distillation est comprise entre -35°C et 30°C. Preferably, stage b2) is carried out by distillation, and the temperature at the top of the distillation column is below 40° C.; in particular the temperature at the head of the distillation column is between -40° C. and 40° C.; more particularly the temperature at the top of the distillation column is between -35°C and 30°C.
Dans ces conditions opératoires, le courant DI est de préférence sous la forme d'une composition azéotropique ou quasi-azéotropique comprenant chlorotrifluoroéthylène et 1,1,2- trifluoroéthane. Under these operating conditions, the DI stream is preferably in the form of an azeotropic or quasi-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
Le courant DI tel que décrit dans la présente demande est recyclé à l'étape a) du présent procédé. Les étapes du présent procédé sont répétées. Un courant de CTFE frais est mélangé au courant DI après son recyclage pour maintenir le ratio CTFE/H2 adéquat. The DI stream as described in the present application is recycled to step a) of the present process. The steps of the present method are repeated. A fresh CTFE stream is mixed with the DI stream after it is recycled to maintain the proper CTFE/H2 ratio.
Exemple Example
Dans un réacteur tubulaire constitué d'un tube inox d'une longueur de 1200 mm sur un diamètre de 25 mm, et équipé d'une double enveloppe, on a introduit 25 cm3 de catalyseur (0,2% de palladium supporté sur alumine alpha). Le catalyseur ainsi chargé a été ensuite activé de la manière suivante : le tube réactionnel a été placé dans un four tubulaire et a été alimenté par un flux d'hydrogène (de 0,05 à 0,1 moles par gramme de catalyseur). Le lit catalytique est chauffé à une température de 200°C à 250°C avec un gradient de température de 0,2°C/min. Après cette période d'activation, le tube a été refroidi à température ambiante puis a été isolé pour être ensuite installer sur un banc de test d'hydrogénolyse. 25 cm 3 of catalyst (0.2% palladium supported on alumina alpha). The catalyst thus charged was then activated in the following manner: the reaction tube was placed in a tube furnace and was fed with a flow of hydrogen (from 0.05 to 0.1 moles per gram of catalyst). The catalytic bed is heated to a temperature of 200° C. to 250° C. with a temperature gradient of 0.2° C./min. After this activation period, the tube was cooled to ambient temperature then was insulated to then be installed on a hydrogenolysis test bench.
On utilise 4 bancs de test en parallèle comprenant chacun un réacteur préparé comme décrit ci- dessus. On a alimenté les quatre bancs avec 1 mol/h de composition de départ et 1 mol/h d'hydrogène sous forme anhydre. La température de la double enveloppe du réacteur est de 25°C. Le temps de contact, calculé comme étant le rapport entre le volume en litre de catalyseur et la somme des débits des réactifs en normaux litres par secondes, était de l'ordre de 22 secondes. Des essais sont réalisés à partir de différentes compositions de départ. L'exemple 1 comparatif a été mis en œuvre à partir de chlorotrifluoroéthylène. L'exemple 2 selon l'invention a été mis en œuvre à partir du chlorotrifluoroéthylène utilisé à l'exemple comparatif auquel a été ajouté du 1,1,2-trifluoroéthane (3,9%). Les résultats sont repris dans le tableau 1 ci-dessous : [Tableau 1] La productivité mentionnée correspond à la somme des productivités obtenues pour l'ensemble des quatre bancs d'hydrogénolyse. Comme on peut le constater, la productivité en trifluoroéthylène est améliorée significativement en partant de la composition selon l'invention par rapport à une composition de chlorotrifluoroéthylène sans les composés additionnels. 4 test benches are used in parallel, each comprising a reactor prepared as described above. The four benches were fed with 1 mol/h of starting composition and 1 mol/h of hydrogen in anhydrous form. The temperature of the jacket of the reactor is 25°C. The contact time, calculated as being the ratio between the volume in liters of catalyst and the sum of the flow rates of the reactants in normal liters per second, was of the order of 22 seconds. Tests are carried out using different starting compositions. Comparative Example 1 was implemented from chlorotrifluoroethylene. Example 2 according to the invention was implemented from the chlorotrifluoroethylene used in the comparative example to which was added 1,1,2-trifluoroethane (3.9%). The results are shown in Table 1 below: [Table 1] The productivity mentioned corresponds to the sum of the productivities obtained for all of the four hydrogenolysis benches. As can be seen, the trifluoroethylene productivity is significantly improved starting from the composition according to the invention compared with a composition of chlorotrifluoroethylene without the additional compounds.

Claims

Revendications Claims
1. Procédé de production du trifluoroéthylène dans un réacteur muni d'un lit catalytique fixe comprenant un catalyseur, ledit procédé comprenant les étapes de : a) réaction du chlorotrifluoroéthylène avec de l'hydrogène en présence du catalyseur et en phase gazeuse pour produire un courant A comprenant du trifluoroéthylène ; b) traitement dudit courant A dans des conditions suffisantes pour produire un courant Dl comprenant du 1,1,2-trifluoroéthane dans une teneur inférieure à 15% en poids sur base du poids total dudit courant Dl, c) recyclage du courant Dl à l'étape a). 1. Process for producing trifluoroethylene in a reactor equipped with a fixed catalytic bed comprising a catalyst, said process comprising the steps of: a) reacting chlorotrifluoroethylene with hydrogen in the presence of the catalyst and in the gas phase to produce a current A comprising trifluoroethylene; b) treatment of said stream A under conditions sufficient to produce a stream D1 comprising 1,1,2-trifluoroethane in a content of less than 15% by weight based on the total weight of said stream D1, c) recycling of stream D1 to step a).
2. Procédé selon la revendication précédente caractérisé en ce que le courant A comprend également, outre le trifluoroéthylène, du chlorotrifluoroéthylène n'ayant pas réagi et 1,1,2-trifluoroéthane. 2. Process according to the preceding claim, characterized in that stream A also comprises, in addition to trifluoroethylene, unreacted chlorotrifluoroethylene and 1,1,2-trifluoroethane.
3. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le courant DI comprend également du chlorotrifluoroéthylène dans une teneur massique supérieure à 60% en poids sur base du poids total dudit courant Dl. 3. Method according to any one of the preceding claims, characterized in that the stream DI also comprises chlorotrifluoroethylene in a mass content greater than 60% by weight based on the total weight of said stream D1.
4. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le courant Dl est sous la forme d'une composition azéotropique ou quasi-azéotropique comprenant chlorotrifluoroéthylène et 1,1,2-trifluoroéthane. 4. Process according to any one of the preceding claims, characterized in that the stream D1 is in the form of an azeotropic or quasi-azeotropic composition comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane.
5. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le courant A comprend du trifluoroéthylène, du chlorotrifluoroéthylène et 1,1,2- trifluoroéthane et l'étape b) comprend les étapes de : bl) purification dudit courant A comprenant du trifluoroéthylène, du chlorotrifluoroéthylène et 1,1,2-trifluoroéthane pour former un courant Cl comprenant du trifluoroéthylène et un courant C2 comprenant chlorotrifluoroéthylène et 1,1,2- trifluoroéthane ; b2) purification du courant C2 pour produire ledit courant Dl et un courant D2 comprenant du 1,1,2-trifluoroéthane. 5. Process according to any one of the preceding claims, characterized in that stream A comprises trifluoroethylene, chlorotrifluoroethylene and 1,1,2-trifluoroethane and step b) comprises the steps of: bl) purification of said stream A comprising trifluoroethylene, chlorotrifluoroethylene and 1,1,2-trifluoroethane to form a C1 stream comprising trifluoroethylene and a C2 stream comprising chlorotrifluoroethylene and 1,1,2-trifluoroethane; b2) purification of stream C2 to produce said stream D1 and a stream D2 comprising 1,1,2-trifluoroethane.
6. Procédé selon la revendication précédente caractérisé en ce que l'étape b2) est mise en oeuvre par distillation à une pression inférieure à 8 bara, de préférence inférieure à 6 bara. 6. Method according to the preceding claim, characterized in that step b2) is carried out by distillation at a pressure of less than 8 bara, preferably less than 6 bara.
7. Procédé selon l'une quelconque des revendications précédentes 5 ou 6 caractérisé en ce que l'étape b2) est mise en oeuvre par distillation, et la température en tête de colonne de distillation est inférieure à 40°C. 7. Process according to any one of the preceding claims 5 or 6, characterized in that step b2) is carried out by distillation, and the temperature at the top of the distillation column is less than 40°C.
8. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que ledit catalyseur est un catalyseur à base d'un métal des colonnes 8 à 10 du tableau périodique des éléments, de préférence déposé sur un support, en particulier un support à base d'aluminium. 8. Process according to any one of the preceding claims, characterized in that the said catalyst is a catalyst based on a metal from columns 8 to 10 of the periodic table of the elements, preferably deposited on a support, in particular a support based of aluminium.
9. Procédé selon la revendication précédente caractérisé en ce que le catalyseur comprend du palladium supporté sur de l'alumine alpha. 9. Process according to the preceding claim, characterized in that the catalyst comprises palladium supported on alpha alumina.
10. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le chlorotrifluoroéthylène et l'hydrogène sont sous forme anhydre. 10. Process according to any one of the preceding claims, characterized in that the chlorotrifluoroethylene and the hydrogen are in anhydrous form.
EP22735012.1A 2021-06-07 2022-06-03 Method for producing trifluoroethylene and recycling the chlorotrifluoroethylene stream Pending EP4352032A1 (en)

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