WO2018178553A1 - Method for recovering hydrofluoric acid - Google Patents

Method for recovering hydrofluoric acid Download PDF

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Publication number
WO2018178553A1
WO2018178553A1 PCT/FR2018/050733 FR2018050733W WO2018178553A1 WO 2018178553 A1 WO2018178553 A1 WO 2018178553A1 FR 2018050733 W FR2018050733 W FR 2018050733W WO 2018178553 A1 WO2018178553 A1 WO 2018178553A1
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stream
hydrofluoric acid
compound
weight
phase
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PCT/FR2018/050733
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French (fr)
Inventor
Dominique Deur-Bert
Laurent Wendlinger
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Arkema France
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Publication of WO2018178553A1 publication Critical patent/WO2018178553A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/19—Fluorine; Hydrogen fluoride
    • C01B7/191—Hydrogen fluoride
    • C01B7/195—Separation; Purification

Definitions

  • the present invention relates to a process for recovering hydrofluoric acid.
  • the present invention relates to a process for recovering hydrofluoric acid from a process for preparing a fluorinated compound.
  • the recovery of the hydrofluoric acid is generally carried out by decantation in the presence or absence of a solvent.
  • WO 2011/110889 may be mentioned where the separation between the hydrofluoric acid and the fluorinated compound is carried out by decantation.
  • WO 2008/008519 also discloses a process for separating hydrofluoric acid and a fluoroolefin in the presence of an extractant. The operational cost related to the use of an extractant and its subsequent purification is too important to be implemented industrially.
  • hydrofluoric acid and a fluorinated compound can be improved to optimize the yield of hydrofluoric acid recovered and minimize operational costs.
  • the present invention aims to overcome the drawbacks identified in the prior art.
  • the present process for recovering hydrofluoric acid comprises the steps of: i) contacting a first stream comprising a hydrocarbon compound A having at least one fluorine atom and hydrofluoric acid, preferably in gaseous form, with an aqueous solution of hydrofluoric acid with a concentration of greater than 40% by weight to form a second diphasic stream comprising compound A and hydrofluoric acid, ii) storing said second diphasic current in a buffer tank, said second two-phase current consisting of a liquid phase and a gaseous phase,
  • the method comprises the steps:
  • step iv) neutralizing said third stream obtained in step iii) with an aqueous alkaline solution to form a neutralized stream
  • step iv) drying said neutralized stream obtained in step iv) on molecular sieve.
  • the fourth stream is recycled to step ii).
  • said two-phase current consists of a gaseous phase comprising compound A and a liquid phase comprising hydrofluoric acid and less than 5% by weight of compound A based on the total weight of said liquid phase.
  • the aqueous hydrofluoric acid solution used in step i) is at a temperature of between 0 and 30 ° C. before being brought into contact with said first stream.
  • the liquid phase resulting from mixing said liquid phase of said second two-phase stream and the fourth stream is distilled to form a stream C, preferably at the top of the distillation column, comprising hydrofluoric acid containing less 500 ppm of water and a stream D, preferably at the bottom of the distillation column, comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight.
  • the liquid phase resulting from mixing said liquid phase of said second two-phase current and the fourth current is recycled to step i).
  • a part of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is distilled to form a stream C comprising hydrofluoric acid containing less than 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution of concentration less than 50% by weight, as mentioned above, and a part of the liquid phase resulting from the mixing of said liquid phase of said second stream diphasic and fourth stream is recycled to step i). This can be done simultaneously.
  • At least 50%, more preferably at least 60%, in particular at least 70%, more particularly at least 80%, preferably at least 90% by weight of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is recycled to step i); and less than 50%, preferably less than 40%, more preferably less than 30%, in particular less than 20%, more particularly less than 10% by weight is distilled to form a stream C comprising hydrofluoric acid containing less 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight.
  • the third stream comprises less than 5% by weight of hydrofluoric acid based on the total weight of said third stream.
  • said absorption column used in step iii) comprises at least one absorption stage.
  • the ratio between the flow rate of the aqueous flow supplying the absorption column in step iii) and the quantity of hydrofluoric acid in the said first flow expressed in kg / h is between 0.05 and 1.22, preferably between 0.33 and 0.54.
  • said first stream is derived from the contacting between a compound B and hydrofluoric acid, said compound B having a number of fluorine atoms lower than that of the compound A.
  • the process according to the present invention makes it possible to recover compound A in a low hydrofluoric acid content, or even free of hydrofluoric acid.
  • the present process allows recovery and recovery of hydrofluoric acid used in excess in the reaction between the compound B and HF.
  • hydrofluoric acid having a very low water content is recovered by the present process and can be reused to produce compound A.
  • Fig. 1 schematically represents a process for recovering hydrofluoric acid according to a particular embodiment of the present invention.
  • Fig. 2 schematically shows a process for recovering hydrofluoric acid according to another particular embodiment of the present invention. Detailed description of the invention
  • the present invention relates to a process for recovering hydrofluoric acid.
  • the method comprises the steps of:
  • a first stream comprising a hydrocarbon compound A having at least one fluorine atom and hydrofluoric acid, preferably in gaseous form, with an aqueous solution of hydrofluoric acid of concentration greater than 40% by weight; weight for forming a second diphasic current comprising compound A and hydrofluoric acid, ii) storing said second diphasic current in a buffer tank, said second two-phase current consisting of a liquid phase and a gaseous phase,
  • the hydrocarbon compound A can contain from one to twelve carbon atoms, preferably from one to six carbon atoms, in particular the hydrocarbon compound A contains three carbon atoms.
  • the hydrocarbon compound A is of the formula C h H a Br b Cl c F d, wherein h is an integer between 1 and 6, a is an integer between 0 and 13, b is an integer between 0 and 4, c is an integer between 0 and 13, d is an integer between 1 and 14, and the sum of a, b, c and d is 2h + 2; or of general formula C p H e Br f Cl g F h , where p is an integer between 2 and 6, e is an integer between 0 and 11, f is an integer between 0 and 2, g is an integer between 0 and 11, h is an integer between 1 and 12, and the sum of e, f, g and h is 2p.
  • the hydrocarbon compound A is of the general formula C h H a Cl c F d , where h is an integer between 2 and 4, a is an integer between 0 and 9, c is an integer between 0 and 9, d is an integer between 1 and 10, and the sum of a, c and d is equal to 2h + 2; or of general formula C p H e Cl g F h , where p is an integer between 2 and 4, e is an integer between 0 and 7, g is an integer between 0 and 7, h is an integer between 1 and 8, and the sum of e, f, g and h is equal to 2p.
  • CF 3 CCI CH 2 or HCFO-1233xf
  • 1,1,1,2,2-pentafluoropropane CF 3 CF 2 CH 3 or HFC-245cb
  • CF 3 CF CH 2 or HFO
  • the aqueous hydrofluoric acid solution used in step i) is of concentration greater than 40% by weight.
  • the hydrofluoric acid aqueous solution is of concentration greater than 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52% 53% 54% 55% 56% 57% 58% 59% 60% 61% 62% 63% 64% 65% 66% 67% 68% 69 % 70% 71% 72% 73% 74% 75% 76% 77% 78% 79% 80% 81% 82% 83% 84% 85% 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% by weight.
  • the aqueous solution of hydrofluoric acid is of concentration greater than or equal to 50% by weight, or greater than or equal to 60% by weight or greater than or equal to 70% by weight.
  • the aqueous solution of hydrofluoric acid may be between any of the values mentioned above.
  • the hydrofluoric acid aqueous solution may be between 45% and 95% by weight, between 50% and 90% by weight, between 55% and 85% by weight, between 60% by weight and 80% by weight or between 65% by weight and 75% by weight.
  • Step i) of the present process allows formation of said second diphasic stream comprising compound A and hydrofluoric acid.
  • Said two-phase current consists of a gas phase G1 and a liquid phase.
  • the gas phase G 1 may comprise the compound A.
  • the gaseous phase G 1 may comprise hydrofluoric acid.
  • the content thereof is generally low, preferably less than 5% by weight based on the total weight of said gaseous phase, in particular less than 2% by weight based on the total weight of said gaseous phase, more particularly less than 1% by weight based on the total weight of said gaseous phase.
  • Said gaseous phase G 1 may also comprise hydrocarbon compounds different from compound A. These hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A. These hydrocarbon compounds may be of formula ChH a Cl c Fd or of formula C p H e Cl g Fh as defined above.
  • the liquid phase of said two-phase stream may comprise hydrofluoric acid.
  • Said liquid phase may optionally comprise a small amount of compound A, preferably said liquid phase may comprise a content of compound A less than 5% by weight based on the total weight of said liquid phase, in particular less than 1% by weight on base of the total weight of said liquid phase, more particularly less than 5000 ppm by weight based on the total weight of said liquid phase, preferably less than 1000 ppm by weight based on the total weight of said liquid phase, in a more preferred manner less than 500 ppm by weight, particularly preferably less than 100 ppm based on the total weight of said liquid phase.
  • Said liquid phase may also comprise hydrocarbon compounds different from compound A.
  • said liquid phase may comprise a content of compounds organic less than 5% by weight based on the total weight of said liquid phase, in particular less than 1% by weight based on the total weight of said liquid phase, more particularly less than 5000 ppm by weight based on the total weight of said liquid phase, preferably less than 1000 ppm by weight based on the total weight of said liquid phase, more preferably less than 500 ppm by weight, particularly preferably less than 100 ppm based on the total weight of said liquid phase .
  • organic compounds refers to compound A and to the hydrocarbon compounds of formula ChH a Cl c Fd or of formula CpHeClgFh possibly present in said liquid phase.
  • concentration of hydrofluoric acid in said liquid phase of said second diphasic current is greater than the concentration of said aqueous hydrofluoric acid solution used in step i).
  • Said liquid phase of said second two-phase current may have a hydrofluoric acid concentration greater than 41% by weight based on the total weight of said liquid phase of said second two-phase current.
  • said liquid phase of said second two-phase current may have a hydrofluoric acid concentration greater than 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%. %, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85% , 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% by weight based on the total weight of said liquid phase of said second two-phase current.
  • said liquid phase of said second two-phase stream may have a hydrofluoric acid concentration of between 45% and 95% by weight, between 50% and 90% by weight, between 55% and 85% by weight, and between 60% by weight. weight and 80% by weight or between 65% by weight and 75% by weight while being greater than the concentration of said aqueous hydrofluoric acid solution used in step (i).
  • the aqueous hydrofluoric acid solution used in step i) is at a temperature of between -20 ° C. and 80 ° C. before being brought into contact with said first stream, advantageously between -15 ° C. and 70 ° C. C, preferably between -10 ° C and 60 ° C, more preferably between -5 ° C and 50 ° C, in particular between -5 ° C and 40 ° C, more particularly between 0 ° C and 30 ° C, preferred way between 0 ° C and 20 ° C.
  • the temperature of the hydrofluoric acid aqueous solution used in step (i), before it is brought into contact with said first stream can be 0 ° C., 1 ° C., 2 ° C, 3 ° C, 4 ° C, 5 ° C, 6 ° C, 7 ° C, 8 ° C, 9 ° C, 10 ° C, 11 ° C, 12 ° C, 13 ° C, 14 ° C 15 ° C 16 C 17 C 18 C 19 C 20 C 21 C 22 C 23 C 24 C 25 C 26 C 27 ° C, 28 ° C, 29 ° C or 30 ° C.
  • the implementation of said aqueous solution of hydrofluoric acid at the temperatures mentioned above is intended to control the exothermicity occurring during the contacting thereof with said first stream.
  • step ii) of the method according to the present invention implements the storage of said second two-phase current in a buffer tank, said second two-phase current consisting of said liquid phase and of said gaseous phase as described herein. -above.
  • step iii) of the method according to the present invention implements, the passage of said gas phase G1 of said second two-phase current in an absorption column supplied countercurrently with an aqueous stream to form a third stream, preferably gaseous, comprising compound A and a fourth stream, preferably liquid, comprising hydrofluoric acid.
  • the flow rate of the aqueous stream used in step iii) is determined as a function of the amount of hydrofluoric acid contained in said first stream.
  • the ratio between the flow rate of the aqueous flow, expressed in kg / h, feeding the absorption column in step iii) and the amount of hydrofluoric acid in said first flow expressed in kg / h is 0.05. at 1.22.
  • the ratio between the flow rate of the aqueous flow supplying the absorption column in step iii) and the quantity of hydrofluoric acid in the said first flow expressed in kg / h may be 0.11 to 1.00, preferably from 0.18 to 0.82, more preferably from 0.25 to 0.67, in particular from 0.33 to 0.54.
  • the ratio between the flow of the aqueous stream feeding the column in step (iii) and the amount of hydrofluoric acid in said first stream expressed in kg / h may be 0.25, 0.26, 0.27, 0.28, 0.29, 0.
  • An additional aqueous stream corresponding to the vaporized water fraction at the top of said absorption column may also supply said column.
  • the aqueous stream as described above is different from said additional aqueous stream linked to the vaporized water fraction at the top of the column and does not include it.
  • said absorption column implemented in step iii) comprises at least one absorption stage.
  • said absorption column implemented in step iii) comprises at least two absorption stages.
  • said absorption column implemented in step iii) comprises at least three absorption stages.
  • Said absorption column implemented in step iii) can thus comprise two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen or fifteen absorption stages.
  • an absorption column having at least one absorption stage advantageously at least two absorption stages, preferably at least three absorption stages, makes it possible to obtain a third stream having a low content. in hydrofluoric acid.
  • said third stream comprises less than 1000 ppm of hydrofluoric acid by weight based on the total weight of said third stream, preferably less than 900 ppm of hydrofluoric acid, more preferably less than 800 ppm of hydrofluoric acid, in particular less 700 ppm of hydrofluoric acid, more particularly less than 600 ppm of hydrofluoric acid, preferably less than 500 ppm of hydrofluoric acid, even more preferred less than 400 ppm of hydrofluoric acid, preferably less favored 300 ppm of hydrofluoric acid, particularly preferably less than 200 ppm of hydrofluoric acid, more particularly preferred less than 100 ppm of hydrofluoric acid.
  • said third stream may have a hydrofluoric acid content of between 1 and 200 ppm, between 5 and 190 ppm, between 10 and 180 ppm, between 15 and 170 ppm, between 20 and 160 ppm, between 25 and 150 ppm or between 30 and 140 ppm by weight based on the total weight of said third stream.
  • Said third stream may have a hydrofluoric acid content of less than 100 ppm, advantageously less than 75 ppm, preferably less than 50 ppm, more preferably less than 30 ppm. ppm, in particular less than 15 ppm, more particularly less than 10 ppm by weight based on the total weight of said third stream.
  • At least 80% by weight of the hydrofluoric acid optionally present in said gas phase of said second two-phase current is absorbed by the first absorption stage of said absorption column, in particular at least 85% by weight of the hydrofluoric acid optionally present in said gas phase of said second two-phase current is absorbed by the first absorption stage of said absorption column, more particularly at least 90% by weight of the hydrofluoric acid possibly present in said gaseous phase of said second two-phase current is absorbed by the first absorption stage of said absorption column.
  • said aqueous stream can be introduced at least at the head of the absorption column.
  • the temperature at the top of said absorption column is from 20 ° C to 70 ° C, preferably from 30 ° C to 50 ° C.
  • said fourth stream is in the form of an aqueous solution of hydrofluoric acid.
  • said fourth stream is a hydrofluoric acid solution with a concentration of less than 30% by weight based on the total weight of said fourth stream.
  • said fourth stream is a hydrofluoric acid solution of concentration less than 25% by weight based on the total weight of said fourth stream.
  • said fourth stream is a solution of hydrofluoric acid with a concentration of between 5 and 25% by weight based on the total weight of said fourth stream, more particularly between 10 and 20% by weight based on the total weight of said fourth stream.
  • said fourth stream is recycled to step (ii).
  • the fourth stream is thus mixed with the liquid phase of said second two-phase stream.
  • said method also comprises the steps of: iv) neutralizing said third stream obtained in step iii) with an aqueous alkaline solution to form a neutralized stream, and
  • step iv) drying said neutralized stream obtained in step iv) on molecular sieve.
  • said aqueous alkaline solution may be an aqueous solution of hydroxide of an alkali metal or alkaline earth metal.
  • the aqueous alkaline solution may be an aqueous solution of sodium hydroxide, potassium hydroxide, calcium hydroxide or magnesium hydroxide or a mixture thereof.
  • said aqueous alkaline solution has a concentration of between 5 and 50% by weight based on the total weight of said alkaline aqueous solution.
  • said alkaline aqueous solution has a concentration of at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%.
  • Said neutralized stream formed in step iv) preferably comprises compound A as described above.
  • the hydrofluoric acid content in said neutralized stream is lower than the hydrofluoric acid content of said third stream prior to its neutralization.
  • Said neutralized stream may optionally comprise other hydrocarbon compounds. These hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A.
  • Said neutralized stream formed in step (iv) may also contain water.
  • Said neutralized stream formed in step iv) can thus be dried in step v) of the present process.
  • said neutralized stream formed in step iv) is dried on molecular sieve.
  • said neutralized stream formed in step iv) is dried on 3A molecular sieve, such as siliporite.
  • Stage v) of the present process allows the formation of a neutralized and dried stream E comprising said compound A and optionally hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A.
  • Said stream E can then be compressed and liquefied at a pressure of at most 8 bara to form a compressed stream F in which compound A and optionally hydrocarbon compounds can be by-products or impurities obtained in the preparation or production of said compound A are in liquid form.
  • the liquid phase resulting from the mixing of said liquid phase of said second two-phase current with said fourth current is recycled in step i).
  • the liquid phase resulting from the mixing of said liquid phase of said second diphasic current with said fourth stream may be a concentration of hydrofluoric acid greater than 41% by weight based on the total weight of said liquid phase resulting from the mixing of said liquid phase of said second two-phase current with said fourth current.
  • said liquid phase resulting from mixing said liquid phase of said second two-phase current with said fourth stream may have a hydrofluoric acid concentration greater than 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 66% 67% 68% 69% 70% 71% 72% 73% 74% 75% 76% 77% 78% 79% 80% 81% 82 %, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% by weight based on the total weight of said phase liquid resulting from mixing said liquid phase of said second two-phase current with said fourth stream.
  • said liquid phase resulting from the mixing of said liquid phase of said second two-phase stream with said fourth stream may be a concentration of hydrofluoric acid of between 45% and 95% by weight, between 50% and 90% by weight, between 55% and 95% by weight. % and 85% by weight, between 60% by weight and 80% by weight or between 65% by weight and 75% by weight based on the total weight of said liquid phase resulting from the mixing of said liquid phase of said second two-phase current with said fourth current.
  • the liquid phase resulting from mixing said liquid phase of said second two-phase stream with said fourth stream is distilled to form a stream C, preferably at the top of the distillation column, in particular the stream is a stream gaseous.
  • said stream C comprises hydrofluoric acid containing less than 3000 ppm of water, preferably less than 2000 ppm of water, more preferably less than 1000 ppm of water, in particular less than 500 ppm of water, more particularly less than 200 ppm water, preferably less than 100 ppm water, more preferably less than 50 ppm water based on the total weight of the current C.
  • Said current C can also include less than 50 ppm of hydrochloric acid, advantageously less than 45 ppm of hydrochloric acid, preferably less than 40 ppm of hydrochloric acid, more preferably less than 35 ppm of hydrochloric acid, in particular less than 30 ppm of hydrochloric acid, more particularly less than 20 ppm of hydrochloric acid based on the total weight of the current C.
  • Said stream C may also comprise less than 50 ppm of organic compounds, advantageously less than 45 ppm of organic compounds, preferably less than 40 ppm of organic compounds.
  • An organic compound is a compound comprising at least one carbon atom.
  • the temperature at the bottom of the distillation column may be at a temperature of 80 ° C to 150 ° C, preferably 110 ° C and 130 ° C.
  • the temperature at the top of the distillation column may be between 10 and 60 ° C., preferably between 20 and 50 ° C.
  • the distillation of the liquid phase resulting from the mixing of said liquid phase of said second two-phase stream with said fourth stream forms a stream D, preferably at the bottom of the distillation column, comprising hydrofluoric acid in the form of a solution. aqueous concentration of less than 50% by weight.
  • the current D can be liquid.
  • said stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight, 49% by weight, 48% by weight, 47% by weight, 46% by weight, 45% by weight. weight, 44% by weight, 43% by weight, 42% by weight based on the total weight of said stream D.
  • said stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration greater than 20% by weight based on the total weight of said stream D.
  • said stream D comprising hydrofluoric acid in the form of an aqueous solution of higher concentration 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight based on the total weight of said stream D.
  • Said aqueous solution obtained in the stream D can be marketed or destroyed by neutralization.
  • a part of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is distilled to form a stream C comprising hydrofluoric acid containing less than 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution of concentration less than 50% by weight, as mentioned above, and a part of the liquid phase resulting from the mixing of said liquid phase of said second stream diphasic and fourth stream is recycled to step i). This can be done alternately or simultaneously.
  • a portion of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is distilled and simultaneously a portion of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth current is recycled in step i).
  • second diphasic current and the fourth current is recycled to step i); and less than 50%, preferably less than 40%, more preferably less than 30%, in particular less than 20%, more particularly less than 10% by weight is distilled to form a stream C comprising hydrofluoric acid containing less than 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight. weight.
  • said first stream is derived from the contacting between a compound B and hydrofluoric acid, said compound B having a number of fluorine atoms lower than that of the compound A.
  • the hydrocarbon compound B can contain from one to twelve carbon atoms, preferably from one to six carbon atoms, in particular the hydrocarbon compound B contains three carbon atoms.
  • the hydrocarbon compound B is of the general formula ChH to BrbCl c Fd, where h is an integer between 1 and 6, a is an integer between 0 and 13, b is an integer between 0 and 4, c is an integer between 1 and 14, d is an integer between 0 and 13, and the sum of a, b, c and d is 2h + 2; or of general formula C p H e BrfCl g Fh, where p is an integer between 2 and 6, e is an integer between 0 and 12, f is an integer between 0 and 2, g is an integer between 0 and 12, h is an integer between 0 and 11, and the sum of e, f, g and h is equal to 2p.
  • the hydrocarbon compound B is of the general formula ChH a Cl c Fd, where h is an integer between 2 and 4, a is an integer between 0 and 9, c is an integer between 1 and 9, d is an integer between 0 and 9, and the sum of a, c and d is equal to 2h + 2; or of general formula C p H e Cl g Fh, where p is an integer between 2 and 4, e is an integer between 0 and 8 g is an integer between 0 and 8, h is an integer between 0 and 7, and the sum of e, f, g and h is equal to 2p.
  • said compound B can be 1, 1,2-trichloroethane (CHCl 2 CH 2 Cl or HCC-140),
  • said compound B may be 1,1,1,2,3-pentachloropropane (CCI3CHCICH2Cl or HCC-240db), 1, 1,2,2,3-pentachloropropane (CHCl 2 CCI 2 CH 2 CI or HCC-240aa ), 1,1,1,2,2-pentachloropropane (CCI3CCI2CH3 or HCC-240ab), 1, 1, 1,3,3-pentachloropropane (CCI3CH2CHCl2 or HCC-240fa) or 1,1,2-trichloroethane (CHCl 2 CH 2 CI or HCC-140), 1,2-dichloro-3,3,3-trifluoropropane (CF3CHCICH2Cl or HCFC-243db) or a mixture thereof.
  • CCI3CHCICH2Cl or HCC-240db 1,1,2,2,3-pentachloropropane
  • CHCl 2 CCI 2 CH 2 CI or HCC-240aa
  • CF 3 CCI CH 2 or HCFO-12
  • the compound B has the formula CH ( n + 2 ) (X) m -
  • compound B is selected from the group consisting of 2-chloro-3,3,3-trifluoro-1-propene (H FCO-1233xf), 1,1,1,2,3-pentachloropropane (HCC-240db) , 1,2-dichloro-3,3,3-trifluoropropane, 1,1,2,3-tetrachloro-1-propene (HCO-1230xa), 2,3,3,3-tetrachloro-1-propene (HCO- 1230xf), 1,1,1,2,2-pentachloropropane, or mixtures thereof, for the production of 2,3,3,3-tetrafluoropropene (HFO-1234yf).
  • H FCO-1233xf 2-chloro-3,3,3-trifluoro-1-propene
  • HCC-240db 1,1,1,2,3-pentachloropropane
  • HCO-1230xa 1,1,2,3-tetrachloro-1-propene
  • the contacting between compound B and hydrofluoric acid to produce compound A can be carried out in a reactor.
  • the contacting between compound B and hydrofluoric acid is carried out in the gas phase.
  • the contacting between compound B and hydrofluoric acid is carried out in the presence or absence of a catalyst.
  • the contacting between compound B and hydrofluoric acid can be carried out according to the following operating conditions:
  • an HF / hydrocarbon compound molar ratio between 1: 1 and 150: 1, preferably between 2: 1 and 125: 1, more preferably between 3: 1 and 100: 1;
  • a contact time between 1 and 100 s, preferably between 2 and 75 s, in particular between 3 and 50 s; a pressure between atmospheric pressure and 20 bara, preferably between 2 and 18 bara, more preferably between 3 and 15 bara;
  • a temperature between 200 and 450 ° C, preferably between 250 and 400 ° C, more preferably between 280 ° C and 380 ° C.
  • the contacting can be carried out over a period of between 10 and 8000 h, preferably between 50 and 5000 h, more preferably between 70 and 1000 h.
  • An oxidant such as oxygen or chlorine, can be added during the process.
  • the molar ratio of the oxidant to the hydrocarbon compound may be between 0.005 and 2, preferably between 0.01 and 1.5.
  • the oxidant may be pure oxygen, air or a mixture of oxygen and nitrogen.
  • the contacting between compound B and hydrofluoric acid may be carried out in the presence of a catalyst based on a metal comprising a metal oxide of transition or a derivative or a halide or an oxyhalide of such a metal.
  • a catalyst based on a metal comprising a metal oxide of transition or a derivative or a halide or an oxyhalide of such a metal.
  • Mention may be made, for example, of FeC, chromium oxyfluoride, chromium oxides (optionally subjected to fluorination treatments), chromium fluorides and mixtures thereof.
  • Other possible catalysts are carbon supported catalysts, antimony catalysts, aluminum catalysts (for example AI F3 and Al2O3, alumina oxyfluoride and alumina fluoride).
  • a chromium oxyfluoride a fluoride or an aluminum oxyfluoride, or a supported or non-supported catalyst containing a metal such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge or Sn. Pb, Mg, Sb.
  • a metal such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge or Sn. Pb, Mg, Sb.
  • the catalyst is more preferably based on chromium and it is more particularly a mixed catalyst comprising chromium.
  • a mixed catalyst comprising chrome and nickel.
  • the molar ratio Cr / Ni (based on the metal element) is generally 0.5 to 5, for example 0.7 to 2, for example about 1.
  • the catalyst may contain from 0.5 to 20% by weight of nickel.
  • the metal may be present in metallic form or in the form of a derivative, for example an oxide, halide or oxyhalide. These derivatives are preferably obtained by activation of the catalytic metal.
  • the support is preferably made of aluminum, for example alumina, activated alumina or aluminum derivatives, such as aluminum halides and aluminum oxyhalides, for example described in US 4,902,838, or obtained by the activation method described above.
  • the catalyst may comprise chromium and nickel in an activated or non-activated form, on a support which has been subjected to activation or not.
  • WO 2009/118628 especially at p.4, l.30-p.7 1.16
  • Another preferred embodiment is based on a mixed catalyst containing chromium, preferably in oxide or oxyfluoride form, and at least one co-catalyst chosen from the salts of Co, Mn, Mg and Zn, preferably Zn .
  • Said cocatalyst is preferably present in a content of 1 to 10% by weight based on the weight of the catalyst.
  • the catalyst is preferably activated with air, oxygen or chlorine and / or with HF.
  • the catalyst is preferably subjected to activation with air or oxygen and HF at a temperature of 100 to 500 ° C, preferably 250 to 500 ° C and more preferably 300 to 500 ° C. at 400 ° C.
  • the activation time is preferably from 1 to 200 hours and more particularly from 1 to 50 hours. This activation may be followed by a final fluorination activation step in the presence of an oxidizing agent, HF and organic compounds.
  • the molar ratio of HF / organic compounds is preferably from 2 to 40 and the molar ratio of oxidation agent / organic compounds is preferably from 0.04 to 25.
  • the temperature of the final activation is preferably from 300 to 400 ° C. C and its duration preferably from 6 to 100 h.
  • the contacting between compound B and hydrofluoric acid can be carried out with a HF / compound of formula (I) molar ratio of 3: 1 at 150: 1, and preferably at a temperature of from 200 to 450 ° C, and preferably from 300 to 430 ° C.
  • FIG. 1 schematically shows a method according to a particular embodiment of the present invention.
  • the first stream 1 comprises the compound A, for example 2,3,3,3-tetrafluoropropene, and feeds a device 2 in which it is brought into contact with a solution of hydrofluoric acid or a solution of hydrofluoric acid derived from the pipe 20 having a concentration ranging from 65 to 75% by weight.
  • the device 2 may for example be a hydrolaver.
  • the contacting between the hydrofluoric acid solution or a solution of hydrofluoric acid resulting from the pipe 20 and the first stream 1 generates the formation of a two-phase current which is conveyed to a storage device 4 via the pipe 13.
  • the storage device 4 makes it possible to separate the two-phase current into a gaseous phase and a liquid phase.
  • the gaseous phase G1 of said two-phase current is conveyed via line 14 to the absorption column 3 comprising three absorption stages 21a, 21b and 21c.
  • the column 3 is also fed by an aqueous stream 7.
  • the aqueous stream 7 feeds the absorption column 3 at the head of the absorption column 7, that is to say above the three absorption stages 21a-21c.
  • the gas stream 7 can feed the absorption column 3 above each of the absorption stages 21a-21c.
  • a gaseous stream comprising compound A is extracted at the top of absorption column 3 through line 16 to supply a neutralization device 5.
  • the gaseous stream extracted at the top of absorption column 3 corresponds to said third stream according to the present invention.
  • an aqueous solution of hydrofluoric acid corresponding to said fourth stream is recycled to storage device 4 via line 15.
  • the third stream is neutralized in the neutralization device with an alkaline solution of 20% NaOH.
  • the alkaline solution 8 feeds the neutralization device 5 through line 19.
  • the neutralized stream is discharged through line 17 and recovered at 10 to be dried on 3A molecular sieve.
  • the neutralized and dried stream corresponds to the stream E according to the present process. This can be compressed and liquefied at a pressure of at most 8 bara.
  • a spent alkaline solution 9 may be removed from the neutralization device 5 to be either recycled via the lines 18 and 19 or discharged via the line 18 for further processing.
  • the liquid phase resulting from the mixing of the liquid phase of the two-phase current and the fourth current stored in the storage device 4 is conveyed to a distillation column 6 via the pump 22 and the pipe 23 to form the stream C recovered at the top of the column 11 and the stream D recovered at the bottom of the distillation column 12.
  • the pump 22 can also be configured to convey the liquid phase resulting from mixing the liquid phase of the two-phase current and the fourth current stored in the storage device 4 to the device 2 via the pipe 20. This is represented in FIG. 2.
  • the pump 22 is thus configured to allow the supply of the distillation column 11 and the device 2 alternately, simultaneously, preferably simultaneously.
  • the present method makes it possible to recover the hydrofluoric acid present in a gaseous stream, in particular by using an absorption column, thus making it possible to purify said gaseous flow.
  • the present method makes it possible, in a particular embodiment, to couple a hydrofluoric acid absorption device with a hydrofluoric acid distillation device to produce anhydrous or substantially anhydrous hydrofluoric acid, ie current C, as explained above.
  • This makes it possible to maximize the reuse of hydrofluoric acid in the form of anhydrous or substantially anhydrous hydrofluoric acid in a fluorination reaction, for example of a compound B as explained above.
  • the present process also makes it possible to obtain anhydrous or substantially anhydrous hydrofluoric acid containing at most traces of hydrochloric acid or of organic compounds.
  • a first stream comprising 93.27% by weight of compound A and 6.73% by weight of hydrofluoric acid is contacted with an aqueous hydrofluoric aid solution having a concentration of 67% by weight.
  • the gaseous phase of the two-phase current produced feeds an absorption column comprising two stages.
  • the third current as described in the present application is recovered at the top of the absorption column.
  • the fourth stream as described in the present application is recovered at the bottom of the absorption column. The latter is distilled to allow the production of a gaseous stream comprising 99.92% by weight of hydrofluoric acid.
  • Table 1 below details the contents of various compounds at different stages of the present process.
  • the numbers mentioned in the table correspond to the flows / currents described with reference to FIGS. 1 and 2.
  • Example 1 is reproduced with a column with three absorption stages.
  • Table 2 below details the contents of various compounds at different stages of the present process. The numbers mentioned in the table correspond to the flows / currents described with reference to FIGS. 1 and 2.

Abstract

The present invention concerns a method for recovering hydrofluoric acid comprising the steps of i) bringing a first flow, comprising a hydrocarbon compound A having at least one fluorine atom and hydrofluoric acid, preferably in gas form, into contact with an aqueous solution of hydrofluoric acid with a concentration greater than 40% by weight in order to form a second two-phase flow comprising the compound A and hydrofluoric acid, ii) storing said second two-phase flow in a buffer tank, said second two-phase flow consisting of a liquid phase and a gas phase, iii) passing said gas phase G1 of said second two-phase flow into an absorption column fed in countercurrent with an aqueous stream in order to form a third flow comprising the compound A and a fourth flow comprising hydrofluoric acid.

Description

Procédé de récupération d'acide fluorhydrique  Hydrofluoric acid recovery process
Domaine technique de l'invention Technical field of the invention
La présente invention concerne un procédé de récupération d'acide fluorhydrique. En particulier, la présente invention se rapporte à un procédé de récupération d'acide fluorhydrique issu d'un procédé de préparation d'un composé fluoré.  The present invention relates to a process for recovering hydrofluoric acid. In particular, the present invention relates to a process for recovering hydrofluoric acid from a process for preparing a fluorinated compound.
Arrière-plan technologique de l'invention Technological background of the invention
La fluoration de composé hydrocarbure en présence d'acide fluorhydrique est connu. On peut citer notamment les demandes WO 2012/098420 et WO 2013/088195 qui concernent la fluoration du 1,1,1,2,3-pentachloropropane et/ou 1,1,2,2,3-pentachloropropane en présence d'acide fluorhydrique pour produire du 2,3,3,3-tetrafluoropropène.  The fluorination of hydrocarbon compound in the presence of hydrofluoric acid is known. Applications WO 2012/098420 and WO 2013/088195 relating to the fluorination of 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane in the presence of acid can be cited in particular. hydrofluoric acid to produce 2,3,3,3-tetrafluoropropene.
La formation d'un azéotrope entre l'acide fluorhydrique et certains gaz fluorés est décrites dans l'art. Les procédés de production de gaz fluorés doivent mettre en œuvre des techniques de récupération de cet acide fluorhydrique entraîné sous une forme azéotropique, de façon à améliorer le rendement en HF.  The formation of an azeotrope between hydrofluoric acid and certain fluorinated gases is described in the art. The processes for producing fluorinated gases must implement techniques for recovering this hydrofluoric acid entrained in azeotropic form, so as to improve the HF yield.
La récupération de l'acide fluorhydrique est généralement effectuée par décantation en présence ou non d'un solvant. On peut citer par exemple WO 2011/110889 où la séparation entre l'acide fluorhydrique et le composé fluoré est effectuée par décantation. On connaît également par WO 2008/008519 un procédé de séparation entre l'acide fluorhydrique et une fluorooléfine en présence d'un extractant. Le coût opérationnel lié à l'utilisation d'un extractant et à sa purification ultérieure est trop important pour être mis en œuvre industriellement.  The recovery of the hydrofluoric acid is generally carried out by decantation in the presence or absence of a solvent. For example, WO 2011/110889 may be mentioned where the separation between the hydrofluoric acid and the fluorinated compound is carried out by decantation. WO 2008/008519 also discloses a process for separating hydrofluoric acid and a fluoroolefin in the presence of an extractant. The operational cost related to the use of an extractant and its subsequent purification is too important to be implemented industrially.
La séparation entre l'acide fluorhydrique et un composé fluoré peut être améliorée afin d'optimiser le rendement d'acide fluorhydrique récupéré et de minimiser les coûts opérationnels.  The separation between hydrofluoric acid and a fluorinated compound can be improved to optimize the yield of hydrofluoric acid recovered and minimize operational costs.
Résumé de l'invention Summary of the invention
La présente invention a pour but de palier les inconvénients identifiés dans l'art antérieur. Le présent procédé de récupération d'acide fluorhydrique comprend les étapes de : i) mise en contact d'un premier courant comprenant un composé hydrocarbure A ayant au moins un atome de fluor et de l'acide fluorhydrique, de préférence sous forme gazeuse, avec une solution aqueuse d'acide fluorhydrique de concentration supérieure à 40 % en poids pour former un second courant diphasique comprenant le composé A et l'acide fluorhydrique, ii) stockage dudit second courant diphasique dans un réservoir tampon, ledit second courant diphasique étant constitué d'une phase liquide et d'une phase gazeuse, The present invention aims to overcome the drawbacks identified in the prior art. The present process for recovering hydrofluoric acid comprises the steps of: i) contacting a first stream comprising a hydrocarbon compound A having at least one fluorine atom and hydrofluoric acid, preferably in gaseous form, with an aqueous solution of hydrofluoric acid with a concentration of greater than 40% by weight to form a second diphasic stream comprising compound A and hydrofluoric acid, ii) storing said second diphasic current in a buffer tank, said second two-phase current consisting of a liquid phase and a gaseous phase,
iii) passage de ladite phase gazeuse Gl dudit second courant diphasique dans une colonne d'absorption alimenté à contre-courant par un flux aqueux pour former un troisième courant comprenant le composé A et un quatrième courant comprenant l'acide fluorhydrique.  iii) passing said gaseous phase G1 of said second diphasic stream into an absorption column fed countercurrently with an aqueous stream to form a third stream comprising compound A and a fourth stream comprising hydrofluoric acid.
Selon un mode de réalisation préféré, le procédé comprend les étapes :  According to a preferred embodiment, the method comprises the steps:
iv) neutralisation dudit troisième courant obtenu à l'étape iii) par une solution aqueuse alcaline pour former un courant neutralisé, et  iv) neutralizing said third stream obtained in step iii) with an aqueous alkaline solution to form a neutralized stream, and
v) séchage dudit courant neutralisé obtenu à l'étape iv) sur tamis moléculaire.  v) drying said neutralized stream obtained in step iv) on molecular sieve.
Selon un mode de réalisation préféré, le quatrième courant est recyclé à l'étape ii). According to a preferred embodiment, the fourth stream is recycled to step ii).
Selon un mode de réalisation préféré, ledit courant diphasique consiste en une phase gazeuse comprenant le composé A et une phase liquide comprenant de l'acide fluorhydrique et moins de 5% en poids de composé A sur base du poids total de ladite phase liquide. According to a preferred embodiment, said two-phase current consists of a gaseous phase comprising compound A and a liquid phase comprising hydrofluoric acid and less than 5% by weight of compound A based on the total weight of said liquid phase.
Selon un mode de réalisation préféré, la solution aqueuse d'acide fluorhydrique utilisé à l'étape i) est à une température comprise entre 0 à 30°C avant sa mise en contact avec ledit premier courant.  According to a preferred embodiment, the aqueous hydrofluoric acid solution used in step i) is at a temperature of between 0 and 30 ° C. before being brought into contact with said first stream.
Selon un mode de réalisation préféré, la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est distillée pour former un courant C, de préférence en tête de colonne de distillation, comprenant de l'acide fluorhydrique contenant moins de 500 ppm d'eau et un courant D, de préférence en pied de colonne de distillation, comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids.  According to a preferred embodiment, the liquid phase resulting from mixing said liquid phase of said second two-phase stream and the fourth stream is distilled to form a stream C, preferably at the top of the distillation column, comprising hydrofluoric acid containing less 500 ppm of water and a stream D, preferably at the bottom of the distillation column, comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight.
Selon un autre mode de réalisation préféré, la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i).  According to another preferred embodiment, the liquid phase resulting from mixing said liquid phase of said second two-phase current and the fourth current is recycled to step i).
Selon un autre mode de réalisation préféré, une partie de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est distillée pour former un courant C comprenant de l'acide fluorhydrique contenant moins de 500 ppm d'eau et un courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids, tel que mentionné ci-dessus, et une partie de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i). Ceci peut être effectué simultanément. De préférence, au moins 50%, plus préférentiellement au moins 60%, en particulier au moins 70%, plus particulièrement au moins 80%, de manière privilégiée au moins 90% en poids de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i) ; et moins de 50%, de préférence moins de 40%, plus préférentiellement moins de 30%, en particulier moins de 20%, plus particulièrement moins de 10% en poids est distillée pour former un courant C comprenant de l'acide fluorhydrique contenant moins de 500 ppm d'eau et un courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids. According to another preferred embodiment, a part of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is distilled to form a stream C comprising hydrofluoric acid containing less than 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution of concentration less than 50% by weight, as mentioned above, and a part of the liquid phase resulting from the mixing of said liquid phase of said second stream diphasic and fourth stream is recycled to step i). This can be done simultaneously. Preferably, at least 50%, more preferably at least 60%, in particular at least 70%, more particularly at least 80%, preferably at least 90% by weight of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is recycled to step i); and less than 50%, preferably less than 40%, more preferably less than 30%, in particular less than 20%, more particularly less than 10% by weight is distilled to form a stream C comprising hydrofluoric acid containing less 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight.
Selon un mode de réalisation préféré, le troisième courant comprend moins de 5% en poids d'acide fluorhydrique sur base du poids total dudit troisième courant.  According to a preferred embodiment, the third stream comprises less than 5% by weight of hydrofluoric acid based on the total weight of said third stream.
Selon un mode de réalisation préféré, ladite colonne d'absorption utilisée à l'étape iii) comprend au moins un étage d'absorption.  According to a preferred embodiment, said absorption column used in step iii) comprises at least one absorption stage.
Selon un mode de réalisation préféré, le rapport entre le débit du flux aqueux alimentant la colonne d'absorption à l'étape iii) et la quantité d'acide fluorhydrique dans ledit premier courant exprimée en kg/h est compris entre 0,05 et 1,22, de préférence entre 0,33 et 0,54.  According to a preferred embodiment, the ratio between the flow rate of the aqueous flow supplying the absorption column in step iii) and the quantity of hydrofluoric acid in the said first flow expressed in kg / h is between 0.05 and 1.22, preferably between 0.33 and 0.54.
Selon un mode de réalisation préféré, ledit premier courant est issu de la mise en contact entre un composé B et de l'acide fluorhydrique, ledit composé B ayant un nombre d'atomes de fluor inférieur à celui du composé A.  According to a preferred embodiment, said first stream is derived from the contacting between a compound B and hydrofluoric acid, said compound B having a number of fluorine atoms lower than that of the compound A.
Selon un mode de réalisation préféré, le composé B est de formule CH(n+2)(X)m- CHp(X)(n+i)-CX(3+p-m) où X représente indépendamment F ou Cl ; n, m, p sont indépendamment les uns des autres 0 ou 1 avec (n+m) = 0 ou 1, (n+p) = 0 ou 1 et (m-p) = 0 ou 1, au moins un X étant Cl ; et le composé A est le 2,3,3,3-tetrafluoropropène. According to a preferred embodiment, compound B is of the formula CH ( n + 2) (X) m-CH p (X) (n + 1) -CX (3 + pm) where X independently represents F or Cl; n, m, p are independently of one another 0 or 1 with (n + m) = 0 or 1, (n + p) = 0 or 1 and (mp) = 0 or 1, at least one X being Cl; and compound A is 2,3,3,3-tetrafluoropropene.
Le procédé selon la présente invention permet de récupérer le composé A en une teneur en acide fluorhydrique faible voire dépourvu d'acide fluorhydrique. En outre, le présent procédé permet la récupération et la valorisation de l'acide fluorhydrique utilisé en excès dans la réaction entre le composé B et HF. De préférence, de l'acide fluorhydrique ayant une très faible teneur en eau est récupéré grâce au présent procédé et peut être réutilisé pour produire le composé A.  The process according to the present invention makes it possible to recover compound A in a low hydrofluoric acid content, or even free of hydrofluoric acid. In addition, the present process allows recovery and recovery of hydrofluoric acid used in excess in the reaction between the compound B and HF. Preferably, hydrofluoric acid having a very low water content is recovered by the present process and can be reused to produce compound A.
Brève description des figures Brief description of the figures
La Fig. 1 représente schématiquement un procédé de récupération d'acide fluorhydrique selon un mode de réalisation particulier de la présente invention.  Fig. 1 schematically represents a process for recovering hydrofluoric acid according to a particular embodiment of the present invention.
La Fig. 2 représente schématiquement un procédé de récupération d'acide fluorhydrique selon un autre mode de réalisation particulier de la présente invention. Description détaillée de l'invention Fig. 2 schematically shows a process for recovering hydrofluoric acid according to another particular embodiment of the present invention. Detailed description of the invention
La présente invention concerne un procédé de récupération d'acide fluorhydrique. Ledit procédé comprend les étapes de :  The present invention relates to a process for recovering hydrofluoric acid. The method comprises the steps of:
i) mise en contact d'un premier courant comprenant un composé hydrocarbure A ayant au moins un atome de fluor et de l'acide fluorhydrique, de préférence sous forme gazeuse, avec une solution aqueuse d'acide fluorhydrique de concentration supérieure à 40 % en poids pour former un second courant diphasique comprenant le composé A et de l'acide fluorhydrique, ii) stockage dudit second courant diphasique dans un réservoir tampon, ledit second courant diphasique étant constitué d'une phase liquide et d'une phase gazeuse,  i) contacting a first stream comprising a hydrocarbon compound A having at least one fluorine atom and hydrofluoric acid, preferably in gaseous form, with an aqueous solution of hydrofluoric acid of concentration greater than 40% by weight; weight for forming a second diphasic current comprising compound A and hydrofluoric acid, ii) storing said second diphasic current in a buffer tank, said second two-phase current consisting of a liquid phase and a gaseous phase,
iii) passage de ladite phase gazeuse Gl dudit second courant diphasique dans une colonne d'absorption alimenté à contre-courant par un flux aqueux pour former un troisième courant comprenant le composé A et un quatrième courant comprenant l'acide fluorhydrique.  iii) passing said gaseous phase G1 of said second diphasic stream into an absorption column fed countercurrently with an aqueous stream to form a third stream comprising compound A and a fourth stream comprising hydrofluoric acid.
Selon un mode de réalisation préféré, le composé hydrocarbure A peut contenir de un à douze atomes de carbone, de préférence de un à six atomes de carbone, en particulier le composé hydrocarbure A contient trois atomes de carbone. De préférence, le composé hydrocarbure A est de formule générale ChHaBrbClcFd, où h est un entier entre 1 et 6, a est un entier entre 0 et 13, b est un entier entre 0 et 4, c est un entier entre 0 et 13, d est un entier entre 1 et 14, et la somme de a, b, c et d est égale à 2h+2 ; ou de formule générale CpHeBrfClgFh, où p est un entier entre 2 et 6, e est un entier entre 0 et 11, f est un entier entre 0 et 2, g est un entier entre 0 et 11, h est un entier entre 1 et 12, et la somme de e, f, g et h est égale à 2p. According to a preferred embodiment, the hydrocarbon compound A can contain from one to twelve carbon atoms, preferably from one to six carbon atoms, in particular the hydrocarbon compound A contains three carbon atoms. Preferably, the hydrocarbon compound A is of the formula C h H a Br b Cl c F d, wherein h is an integer between 1 and 6, a is an integer between 0 and 13, b is an integer between 0 and 4, c is an integer between 0 and 13, d is an integer between 1 and 14, and the sum of a, b, c and d is 2h + 2; or of general formula C p H e Br f Cl g F h , where p is an integer between 2 and 6, e is an integer between 0 and 11, f is an integer between 0 and 2, g is an integer between 0 and 11, h is an integer between 1 and 12, and the sum of e, f, g and h is 2p.
De préférence, le composé hydrocarbure A est de formule générale ChHaClcFd, où h est un entier entre 2 et 4, a est un entier entre 0 et 9, c est un entier entre 0 et 9, d est un entier entre 1 et 10, et la somme de a, c et d est égal à 2h+2 ; ou de formule générale CpHeClgFh, où p est un entier entre 2 et 4, e est un entier entre 0 et 7, g est un entier entre 0 et 7, h est un entier entre 1 et 8, et la somme de e, f, g et h est égal à 2p. Preferably, the hydrocarbon compound A is of the general formula C h H a Cl c F d , where h is an integer between 2 and 4, a is an integer between 0 and 9, c is an integer between 0 and 9, d is an integer between 1 and 10, and the sum of a, c and d is equal to 2h + 2; or of general formula C p H e Cl g F h , where p is an integer between 2 and 4, e is an integer between 0 and 7, g is an integer between 0 and 7, h is an integer between 1 and 8, and the sum of e, f, g and h is equal to 2p.
En particulier, le composé A peut être l-chloro-2,2-difluoroéthane (CH2CICF2H ou HCFC- 142), l,l,3-trichloro-l,2,2,3,3-pentafluoropropane (CCI2FCF2CCI F2 ou CFC-215ca), 1,3-dichloro- 1,1,2,2,3,3-hexafluoropropane (CCI F2CF2CCI F2 ou CFC-216ca), l-chloro-1,1,3,3,3- pentafluoropropane (CF3CH2CCI F2 ou HCFC-235fa), 1,1,1,3,3,3-hexafluoropropane (CF3CH2CF3 ou HFC-236fa), 1,1,1,3,3-pentafluoropropane (CH F2CH2CF3 ou HFC-245fa), l-chloro-3,3,3- trifluoro-l-propène (CHCI=CHCF3 ou HCFO-1233zd), 1,3,3,3-tétrafluoropropène (CHF=CHCF3 ou HFO-1234ze), 1,1,1,3,3,3-hexachlorodifluoropropane (CF3CCI2CF3 ou CFC-212ca), 2-chloro- 1,1,1,2,3,3,3-heptafluoropropane (CF3CCI FCF3 ou CFC-217ba), 1,1,1,2,2,3,3-heptafluoropropane (CF3CF2CH F2 ou HFC-227ca), 2-chloro-3,3,3-trifluoro-l-propène (CF3CCI=CH2 ou HCFO-1233xf), l,2-dichloro-3,3,3-trifluoropropane (CF3CHCICH2CI ou HCFC-243db), 2,3,3,3-tétrafluoropropène (CF3CF=CH2 ou HFO-1234yf), 1,1,1,2,2-pentafluoropropane (CF3CF2CH3 ou HFC-245cb). Plus particulièrement, le composé A peut-être 2-chloro-3,3,3-trifluoro-l-propène (CF3CCI=CH2 ou HCFO-1233xf), 1,1,1,2,2-pentafluoropropane (CF3CF2CH3 ou HFC-245cb), 2,3,3,3- tétrafluoropropène (CF3CF=CH2 ou HFO-1234yf), 1,3,3,3-tétrafluoropropène (CF3CH=CHF ou HFO-1234ze), l,2-dichloro-3,3,3-trifluoropropane (CF3CHCICH2CI ou HCFC-243db) ou 1-chloro- 2,2-difluoroéthane (CH2CICF2H ou HCFC-142). In particular, the compound A can be 1-chloro-2,2-difluoroethane (CH 2 ClF 2 H or HCFC-142), 1,1,3-trichloro-1,2,2,3,3-pentafluoropropane (CCl 2 CFF 2 CCI F 2 or CFC- 215ca), 1,3-dichloro-1,1,2,2,3,3-hexafluoropropane (CCI F2CF2CCI F2 or CFC-216ca), 1-chloro-1,1,3,3,3-pentafluoropropane (CF3CH2CCI F2 or HCFC-235fa), 1,1,1,3,3,3-hexafluoropropane (CF3CH2CF3 or HFC-236fa), 1,1,1,3,3-pentafluoropropane (CHF2CH2CF3 or HFC-245fa), 1-chloro -3,3,3-trifluoro-1-propene (CHCI = CHCF 3 or HCFO-1233zd), 1,3,3,3-tetrafluoropropene (CHF = CHCF 3 or HFO-1234ze), 1,1,1,3 , 3,3-hexachlorodifluoropropane (CF3CCI2CF3 or CFC-212ca), 2-chloro 1,1,1,2,3,3,3-heptafluoropropane (CF3CCI FCF3 or CFC-217ba), 1,1,1,2,2,3,3-heptafluoropropane (CF3CF2CH F2 or HFC-227ca), 2- chloro-3,3,3-trifluoro-1-propene (CF 3 CCI = CH 2 or HCFO-1233xf), 1,2-dichloro-3,3,3-trifluoropropane (CF3CHCICH2Cl or HCFC-243db), 2,3 , 3,3-tetrafluoropropene (CF 3 CF = CH 2 or HFO-1234yf), 1,1,1,2,2-pentafluoropropane (CF 3 CF 2 CH 3 or HFC-245cb). More particularly, compound A may be 2-chloro-3,3,3-trifluoro-1-propene (CF 3 CCI = CH 2 or HCFO-1233xf), 1,1,1,2,2-pentafluoropropane (CF 3 CF 2 CH 3 or HFC-245cb), 2,3,3,3-tetrafluoropropene (CF 3 CF = CH 2 or HFO-1234yf), 1,3,3,3-tetrafluoropropene (CF 3 CH = CHF or HFO-1234ze ), 1,2-dichloro-3,3,3-trifluoropropane (CF 3 CHCl 3 Cl 2 or HCFC-243db) or 1-chloro-2,2-difluoroethane (CH 2 CICF 2 H or HCFC-142).
De préférence, la solution aqueuse d'acide fluorhydrique utilisée à l'étape i) est de concentration supérieure à 40% en poids. En particulier, la solution aqueuse d'acide fluorhydrique est de concentration supérieure à 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% ou 95% en poids. Plus particulièrement, la solution aqueuse d'acide fluorhydrique est de concentration supérieure ou égale à 50% en poids, ou supérieure ou égale 60% en poids ou supérieure ou égale à 70% en poids.  Preferably, the aqueous hydrofluoric acid solution used in step i) is of concentration greater than 40% by weight. In particular, the hydrofluoric acid aqueous solution is of concentration greater than 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52% 53% 54% 55% 56% 57% 58% 59% 60% 61% 62% 63% 64% 65% 66% 67% 68% 69 % 70% 71% 72% 73% 74% 75% 76% 77% 78% 79% 80% 81% 82% 83% 84% 85% 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% by weight. More particularly, the aqueous solution of hydrofluoric acid is of concentration greater than or equal to 50% by weight, or greater than or equal to 60% by weight or greater than or equal to 70% by weight.
Plus particulièrement, la solution aqueuse d'acide fluorhydrique peut être comprise entre l'une quelconque des valeurs mentionnées ci-dessus. Ainsi, la solution aqueuse d'acide fluorhydrique peut être comprise entre 45% et 95% en poids, entre 50% et 90% en poids, entre 55% et 85% en poids, entre 60% en poids et 80% en poids ou entre 65% en poids et 75% en poids.  More particularly, the aqueous solution of hydrofluoric acid may be between any of the values mentioned above. Thus, the hydrofluoric acid aqueous solution may be between 45% and 95% by weight, between 50% and 90% by weight, between 55% and 85% by weight, between 60% by weight and 80% by weight or between 65% by weight and 75% by weight.
L'étape i) du présent procédé permet la formation dudit second courant diphasique comprenant le composé A et de l'acide fluorhydrique. Ledit courant diphasique consiste en une phase gazeuse Gl et une phase liquide. La phase gazeuse Gl peut comprendre le composé A. Optionnellement, la phase gazeuse Gl peut comprendre de l'acide fluorhydrique. Lorsque la phase gazeuse Gl comprend de l'acide fluorhydrique, la teneur de celui-ci est généralement faible, de préférence inférieure à 5% en poids sur base du poids total de ladite phase gazeuse, en particulier inférieure à 2% en poids sur base du poids total de ladite phase gazeuse, plus particulièrement inférieure à 1% en poids sur base du poids total de ladite phase gazeuse. Ladite phase gazeuse Gl peut également comprenant des composés hydrocarbures différents du composé A. Ces composés hydrocarbures peuvent être des produits secondaires ou des impuretés obtenus lors de la préparation ou la production dudit composé A. Ces composés hydrocarbures peuvent être de formule ChHaClcFd ou de formule CpHeClgFh tels que définis ci- dessus. Step i) of the present process allows formation of said second diphasic stream comprising compound A and hydrofluoric acid. Said two-phase current consists of a gas phase G1 and a liquid phase. The gas phase G 1 may comprise the compound A. Optionally, the gaseous phase G 1 may comprise hydrofluoric acid. When the gas phase G 1 comprises hydrofluoric acid, the content thereof is generally low, preferably less than 5% by weight based on the total weight of said gaseous phase, in particular less than 2% by weight based on the total weight of said gaseous phase, more particularly less than 1% by weight based on the total weight of said gaseous phase. Said gaseous phase G 1 may also comprise hydrocarbon compounds different from compound A. These hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A. These hydrocarbon compounds may be of formula ChH a Cl c Fd or of formula C p H e Cl g Fh as defined above.
La phase liquide dudit courant diphasique peut comprendre de l'acide fluorhydrique. Ladite phase liquide peut comprendre optionnellement une faible quantité de composé A, de préférence ladite phase liquide peut comprendre une teneur en composé A inférieure à 5% en poids sur base du poids total de ladite phase liquide, en particulier inférieure à 1% en poids sur base du poids total de ladite phase liquide, plus particulièrement inférieure à 5000 ppm en poids sur base du poids total de ladite phase liquide, de manière privilégiée inférieure à 1000 ppm en poids sur base du poids total de ladite phase liquide, de manière plus privilégiée inférieure à 500 ppm en poids, de manière particulièrement privilégiée inférieure à 100 ppm sur base du poids total de ladite phase liquide. Ladite phase liquide peut également comprenant des composés hydrocarbures différents du composé A. Ces composés hydrocarbures peuvent être des produits secondaires ou des impuretés obtenus lors de la préparation ou la production dudit composé A. Dans ce cas, ladite phase liquide peut comprendre une teneur en composés organiques inférieure à 5% en poids sur base du poids total de ladite phase liquide, en particulier inférieure à 1% en poids sur base du poids total de ladite phase liquide, plus particulièrement inférieure à 5000 ppm en poids sur base du poids total de ladite phase liquide, de manière privilégiée inférieure à 1000 ppm en poids sur base du poids total de ladite phase liquide, de manière plus privilégiée inférieure à 500 ppm en poids, de manière particulièrement privilégiée inférieure à 100 ppm sur base du poids total de ladite phase liquide. Le terme « composés organiques » se réfère au composé A et aux composés hydrocarbures de formule ChHaClcFd ou de formule CpHeClgFh éventuellement présents dans ladite phase liquide. De préférence, la concentration en acide fluorhydrique dans ladite phase liquide dudit second courant diphasique est supérieure à la concentration de ladite solution aqueuse d'acide fluorhydrique utilisée à l'étape i). Ladite phase liquide dudit second courant diphasique peut être avoir une concentration en acide fluorhydrique supérieure à 41% en poids sur base du poids total de ladite phase liquide dudit second courant diphasique. Avantageusement, ladite phase liquide dudit second courant diphasique peut être avoir une concentration en acide fluorhydrique supérieure à 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% ou 95% en poids sur base du poids total de ladite phase liquide dudit second courant diphasique. De préférence, ladite phase liquide dudit second courant diphasique peut être avoir une concentration en acide fluorhydrique comprise entre 45% et 95% en poids, entre 50% et 90% en poids, entre 55% et 85% en poids, entre 60% en poids et 80% en poids ou entre 65% en poids et 75% en poids tout en étant supérieure à la concentration de ladite solution aqueuse d'acide fluorhydrique utilisée à l'étape (i). The liquid phase of said two-phase stream may comprise hydrofluoric acid. Said liquid phase may optionally comprise a small amount of compound A, preferably said liquid phase may comprise a content of compound A less than 5% by weight based on the total weight of said liquid phase, in particular less than 1% by weight on base of the total weight of said liquid phase, more particularly less than 5000 ppm by weight based on the total weight of said liquid phase, preferably less than 1000 ppm by weight based on the total weight of said liquid phase, in a more preferred manner less than 500 ppm by weight, particularly preferably less than 100 ppm based on the total weight of said liquid phase. Said liquid phase may also comprise hydrocarbon compounds different from compound A. These hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A. In this case, said liquid phase may comprise a content of compounds organic less than 5% by weight based on the total weight of said liquid phase, in particular less than 1% by weight based on the total weight of said liquid phase, more particularly less than 5000 ppm by weight based on the total weight of said liquid phase, preferably less than 1000 ppm by weight based on the total weight of said liquid phase, more preferably less than 500 ppm by weight, particularly preferably less than 100 ppm based on the total weight of said liquid phase . The term "organic compounds" refers to compound A and to the hydrocarbon compounds of formula ChH a Cl c Fd or of formula CpHeClgFh possibly present in said liquid phase. Preferably, the concentration of hydrofluoric acid in said liquid phase of said second diphasic current is greater than the concentration of said aqueous hydrofluoric acid solution used in step i). Said liquid phase of said second two-phase current may have a hydrofluoric acid concentration greater than 41% by weight based on the total weight of said liquid phase of said second two-phase current. Advantageously, said liquid phase of said second two-phase current may have a hydrofluoric acid concentration greater than 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%. %, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85% , 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% by weight based on the total weight of said liquid phase of said second two-phase current. Preferably, said liquid phase of said second two-phase stream may have a hydrofluoric acid concentration of between 45% and 95% by weight, between 50% and 90% by weight, between 55% and 85% by weight, and between 60% by weight. weight and 80% by weight or between 65% by weight and 75% by weight while being greater than the concentration of said aqueous hydrofluoric acid solution used in step (i).
De préférence, la solution aqueuse d'acide fluorhydrique utilisé à l'étape i) est à une température comprise entre -20°C à 80°C avant sa mise en contact avec ledit premier courant, avantageusement entre -15°C et 70°C, de préférence entre -10°C et 60°C, plus préférentiellement entre -5°C et 50°C, en particulier entre -5°C et 40°C, plus particulièrement entre 0°C et 30°C, de manière privilégiée entre 0°C et 20°C. Ainsi, dans un mode de réalisation particulièrement préféré, la température de la solution aqueuse d'acide fluorhydrique utilisé à l'étape (i), avant sa mise en contact avec ledit premier courant, peut être de 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C ou 30°C. La mise en œuvre de ladite solution aqueuse d'acide fluorhydrique aux températures mentionnées ci-dessus a pour but de contrôler l'exothermicité survenant lors de la mise en contact de celle-ci avec ledit premier courant.  Preferably, the aqueous hydrofluoric acid solution used in step i) is at a temperature of between -20 ° C. and 80 ° C. before being brought into contact with said first stream, advantageously between -15 ° C. and 70 ° C. C, preferably between -10 ° C and 60 ° C, more preferably between -5 ° C and 50 ° C, in particular between -5 ° C and 40 ° C, more particularly between 0 ° C and 30 ° C, preferred way between 0 ° C and 20 ° C. Thus, in a particularly preferred embodiment, the temperature of the hydrofluoric acid aqueous solution used in step (i), before it is brought into contact with said first stream, can be 0 ° C., 1 ° C., 2 ° C, 3 ° C, 4 ° C, 5 ° C, 6 ° C, 7 ° C, 8 ° C, 9 ° C, 10 ° C, 11 ° C, 12 ° C, 13 ° C, 14 ° C 15 ° C 16 C 17 C 18 C 19 C 20 C 21 C 22 C 23 C 24 C 25 C 26 C 27 ° C, 28 ° C, 29 ° C or 30 ° C. The implementation of said aqueous solution of hydrofluoric acid at the temperatures mentioned above is intended to control the exothermicity occurring during the contacting thereof with said first stream.
Comme mentionné ci-dessus, l'étape ii) du procédé selon la présente invention met en œuvre le stockage dudit second courant diphasique dans un réservoir tampon, ledit second courant diphasique étant constitué de ladite phase liquide et de ladite phase gazeuse telle que décrit ci-dessus.  As mentioned above, step ii) of the method according to the present invention implements the storage of said second two-phase current in a buffer tank, said second two-phase current consisting of said liquid phase and of said gaseous phase as described herein. -above.
Comme mentionné ci-dessus, l'étape iii) du procédé selon la présente invention met en œuvre, le passage de ladite phase gazeuse Gl dudit second courant diphasique dans une colonne d'absorption alimenté à contre-courant par un flux aqueux pour former un troisième courant, de préférence gazeux, comprenant le composé A et un quatrième courant, de préférence liquide, comprenant l'acide fluorhydrique.  As mentioned above, step iii) of the method according to the present invention implements, the passage of said gas phase G1 of said second two-phase current in an absorption column supplied countercurrently with an aqueous stream to form a third stream, preferably gaseous, comprising compound A and a fourth stream, preferably liquid, comprising hydrofluoric acid.
De préférence, le débit du flux aqueux utilisé à l'étape iii) est déterminé en fonction de la quantité d'acide fluorhydrique contenue dans ledit premier courant. Ainsi, le rapport entre le débit du flux aqueux, exprimé en kg/h, alimentant la colonne d'absorption à l'étape iii) et la quantité d'acide fluorhydrique dans ledit premier courant exprimée en kg/h est de 0,05 à 1,22. Avantageusement, le rapport entre le débit du flux aqueux alimentant la colonne d'absorption à l'étape iii) et la quantité d'acide fluorhydrique dans ledit premier courant exprimée en kg/h peut être de 0,11 à 1,00, de préférence de 0,18 à 0,82, plus préférentiellement de 0,25 à 0,67, en particulier de 0,33 à 0,54. Ainsi le rapport entre le débit du flux aqueux alimentant la colonne d'absorption à l'étape (iii) et la quantité d'acide fluorhydrique dans ledit premier courant exprimée en kg/h peut être de 0,25, 0,26, 0,27, 0,28, 0,29, 0,30, 0,31, 0,32, 0,33, 0,34, 0,35, 0,36, 0,37, 0,38, 0,39, 0,40, 0,41, 0,42, 0,43, 0,44, 0,45, 0,46, 0,47, 0,48, 0,49, 0,50, 0,51, 0,52, 0,53, 0,54, 0,55, 0,56, 0,57, 0,58, 0,59, 0,60, 0,61, 0,62, 0,63, 0,64, 0,65, 0,66, 0,67, 0,68, 0,69 ou 0,70. Preferably, the flow rate of the aqueous stream used in step iii) is determined as a function of the amount of hydrofluoric acid contained in said first stream. Thus, the ratio between the flow rate of the aqueous flow, expressed in kg / h, feeding the absorption column in step iii) and the amount of hydrofluoric acid in said first flow expressed in kg / h is 0.05. at 1.22. Advantageously, the ratio between the flow rate of the aqueous flow supplying the absorption column in step iii) and the quantity of hydrofluoric acid in the said first flow expressed in kg / h may be 0.11 to 1.00, preferably from 0.18 to 0.82, more preferably from 0.25 to 0.67, in particular from 0.33 to 0.54. Thus the ratio between the flow of the aqueous stream feeding the column in step (iii) and the amount of hydrofluoric acid in said first stream expressed in kg / h may be 0.25, 0.26, 0.27, 0.28, 0.29, 0. , 30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42 , 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0 , 55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67 , 0.68, 0.69 or 0.70.
Un courant aqueux supplémentaire correspondant à la fraction d'eau vaporisée en tête de ladite colonne d'absorption peut également alimenter ladite colonne. Le flux aqueux tel que décrit ci-dessus est différent dudit courant aqueux supplémentaire lié à la fraction d'eau vaporisée en tête de la colonne et ne l'englobe pas.  An additional aqueous stream corresponding to the vaporized water fraction at the top of said absorption column may also supply said column. The aqueous stream as described above is different from said additional aqueous stream linked to the vaporized water fraction at the top of the column and does not include it.
Selon un mode de réalisation préféré, ladite colonne d'absorption mise en œuvre à l'étape iii) comprend au moins un étage d'absorption. Avantageusement, ladite colonne d'absorption mise en œuvre à l'étape iii) comprend au moins deux étages d'absorption. De préférence, ladite colonne d'absorption mise en œuvre à l'étape iii) comprend au moins trois étages d'absorption. Ladite colonne d'absorption mise en œuvre à l'étape iii) peut ainsi comprendre deux, trois, quatre, cinq, six, sept, huit, neuf, dix, onze, douze, treize, quatorze ou quinze étages d'absorption.  According to a preferred embodiment, said absorption column implemented in step iii) comprises at least one absorption stage. Advantageously, said absorption column implemented in step iii) comprises at least two absorption stages. Preferably, said absorption column implemented in step iii) comprises at least three absorption stages. Said absorption column implemented in step iii) can thus comprise two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen or fifteen absorption stages.
La mise en œuvre d'une colonne d'absorption ayant au moins un étage d'absorption, avantageusement au moins deux étages d'absorption, de préférence au moins trois étages d'absorption, permet d'obtenir un troisième courant ayant une faible teneur en acide fluorhydrique. Avantageusement, ledit troisième courant comprend moins de 1000 ppm d'acide fluorhydrique en poids sur base du poids total dudit troisième courant, de préférence moins de 900 ppm d'acide fluorhydrique, plus préférentiellement moins de 800 ppm d'acide fluorhydrique, en particulier moins de 700 ppm d'acide fluorhydrique, plus particulièrement moins de 600 ppm d'acide fluorhydrique, de manière privilégiée moins de 500 ppm d'acide fluorhydrique, de manière encore plus privilégiée moins de 400 ppm d'acide fluorhydrique, de manière préférentiellement privilégiée moins de 300 ppm d'acide fluorhydrique, de manière particulièrement privilégiée moins de 200 ppm d'acide fluorhydrique, de manière plus particulièrement privilégiée moins de 100 ppm d'acide fluorhydrique. Ainsi, ledit troisième courant peut avoir une teneur en acide fluorhydrique comprise entre 1 et 200 ppm, entre 5 et 190 ppm, entre 10 et 180 ppm, entre 15 et 170 ppm, entre 20 et 160 ppm, entre 25 et 150 ppm ou entre 30 et 140 ppm en poids sur base du poids total dudit troisième courant. Ledit troisième courant peut avoir une teneur en acide fluorhydrique inférieure à 100 ppm, avantageusement inférieure à 75 ppm, de préférence inférieure à 50 ppm, plus préférentiellement inférieure à 30 ppm, en particulier inférieure à 15 ppm, plus particulièrement inférieure à 10 ppm en poids sur base du poids total dudit troisième courant. The implementation of an absorption column having at least one absorption stage, advantageously at least two absorption stages, preferably at least three absorption stages, makes it possible to obtain a third stream having a low content. in hydrofluoric acid. Advantageously, said third stream comprises less than 1000 ppm of hydrofluoric acid by weight based on the total weight of said third stream, preferably less than 900 ppm of hydrofluoric acid, more preferably less than 800 ppm of hydrofluoric acid, in particular less 700 ppm of hydrofluoric acid, more particularly less than 600 ppm of hydrofluoric acid, preferably less than 500 ppm of hydrofluoric acid, even more preferred less than 400 ppm of hydrofluoric acid, preferably less favored 300 ppm of hydrofluoric acid, particularly preferably less than 200 ppm of hydrofluoric acid, more particularly preferred less than 100 ppm of hydrofluoric acid. Thus, said third stream may have a hydrofluoric acid content of between 1 and 200 ppm, between 5 and 190 ppm, between 10 and 180 ppm, between 15 and 170 ppm, between 20 and 160 ppm, between 25 and 150 ppm or between 30 and 140 ppm by weight based on the total weight of said third stream. Said third stream may have a hydrofluoric acid content of less than 100 ppm, advantageously less than 75 ppm, preferably less than 50 ppm, more preferably less than 30 ppm. ppm, in particular less than 15 ppm, more particularly less than 10 ppm by weight based on the total weight of said third stream.
De préférence, au moins 80% en poids de l'acide fluorhydrique éventuellement présent dans ladite phase gazeuse dudit second courant diphasique est absorbé par le premier étage d'absorption de ladite colonne d'absorption, en particulier au moins 85% en poids de l'acide fluorhydrique éventuellement présent dans ladite phase gazeuse dudit second courant diphasique est absorbé par le premier étage d'absorption de ladite colonne d'absorption, plus particulièrement au moins 90% en poids de l'acide fluorhydrique éventuellement présent dans ladite phase gazeuse dudit second courant diphasique est absorbé par le premier étage d'absorption de ladite colonne d'absorption.  Preferably, at least 80% by weight of the hydrofluoric acid optionally present in said gas phase of said second two-phase current is absorbed by the first absorption stage of said absorption column, in particular at least 85% by weight of the hydrofluoric acid optionally present in said gas phase of said second two-phase current is absorbed by the first absorption stage of said absorption column, more particularly at least 90% by weight of the hydrofluoric acid possibly present in said gaseous phase of said second two-phase current is absorbed by the first absorption stage of said absorption column.
De préférence, ledit flux aqueux peut être introduit au moins au niveau de la tête de la colonne d'absorption.  Preferably, said aqueous stream can be introduced at least at the head of the absorption column.
De préférence, la température en tête de ladite colonne d'absorption est de 20°C à 70°C, de préférence de 30°C à 50°C.  Preferably, the temperature at the top of said absorption column is from 20 ° C to 70 ° C, preferably from 30 ° C to 50 ° C.
Selon un mode de réalisation préféré, ledit quatrième courant est sous la forme d'une solution aqueuse d'acide fluorhydrique. Avantageusement, ledit quatrième courant est une solution d'acide fluorhydrique de concentration inférieure à 30% en poids sur base du poids total dudit quatrième courant. De préférence, ledit quatrième courant est une solution d'acide fluorhydrique de concentration inférieure à 25% en poids sur base du poids total dudit quatrième courant. En particulier, ledit quatrième courant est une solution d'acide fluorhydrique de concentration comprise entre 5 et 25% en poids sur base du poids total dudit quatrième courant, plus particulièrement, entre 10 et 20% en poids sur base du poids total dudit quatrième courant.  According to a preferred embodiment, said fourth stream is in the form of an aqueous solution of hydrofluoric acid. Advantageously, said fourth stream is a hydrofluoric acid solution with a concentration of less than 30% by weight based on the total weight of said fourth stream. Preferably, said fourth stream is a hydrofluoric acid solution of concentration less than 25% by weight based on the total weight of said fourth stream. In particular, said fourth stream is a solution of hydrofluoric acid with a concentration of between 5 and 25% by weight based on the total weight of said fourth stream, more particularly between 10 and 20% by weight based on the total weight of said fourth stream. .
Selon un mode de réalisation préféré, ledit quatrième courant est recyclé à l'étape (ii). Le quatrième courant est ainsi mélangé à la phase liquide dudit second courant diphasique.  According to a preferred embodiment, said fourth stream is recycled to step (ii). The fourth stream is thus mixed with the liquid phase of said second two-phase stream.
Selon un mode de réalisation préféré, ledit procédé comprend également les étapes de : iv) neutralisation dudit troisième courant obtenu à l'étape iii) par une solution aqueuse alcaline pour former un courant neutralisé, et  According to a preferred embodiment, said method also comprises the steps of: iv) neutralizing said third stream obtained in step iii) with an aqueous alkaline solution to form a neutralized stream, and
v) séchage dudit courant neutralisé obtenu à l'étape iv) sur tamis moléculaire.  v) drying said neutralized stream obtained in step iv) on molecular sieve.
Selon un mode de réalisation préféré, ladite solution aqueuse alcaline peut être une solution aqueuse d'hydroxyde d'un métal alcalin ou alcalino-terreux. La solution aqueuse alcaline peut être une solution aqueuse d'hydroxyde de sodium, d'hydroxyde de potassium, d'hydroxyde de calcium ou d'hydroxyde de magnésium ou un mélange de ceux-ci. De préférence, ladite solution aqueuse alcaline présente une concentration comprise entre 5 et 50% en poids sur base du poids total de ladite solution aqueuse alcaline. Avantageusement, ladite solution aqueuse alcaline présente une concentration d'au moins 5%, d'au moins 6%, d'au moins 7%, d'au moins 8%, d'au moins 9%, d'au moins 10%, d'au moins 11%, d'au moins 12%, d'au moins 13%, d'au moins 14%, d'au moins 15%, d'au moins 16% ou d'au moins 17% en poids sur base du poids total de ladite solution aqueuse alcaline ; et d'au plus 50%, d'au plus 48%, d'au plus 46%, d'au plus 44%, d'au plus 42%, d'au plus 40%, d'au plus 38%, d'au plus 36%, d'au plus 34%, d'au plus 32%, d'au plus 30%, d'au plus 28%, d'au plus 26%, d'au plus 24%, d'au plus 22% en poids sur base du poids total de ladite solution aqueuse alcaline. According to a preferred embodiment, said aqueous alkaline solution may be an aqueous solution of hydroxide of an alkali metal or alkaline earth metal. The aqueous alkaline solution may be an aqueous solution of sodium hydroxide, potassium hydroxide, calcium hydroxide or magnesium hydroxide or a mixture thereof. Of preferably, said aqueous alkaline solution has a concentration of between 5 and 50% by weight based on the total weight of said alkaline aqueous solution. Advantageously, said alkaline aqueous solution has a concentration of at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%. at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16% or at least weight based on the total weight of said alkaline aqueous solution; and not more than 50%, not more than 48%, not more than 46%, not more than 44%, not more than 42%, not more than 40%, not more than 38%, not more than 36%, not more than 34%, not more than 32%, not more than 30%, not more than 28%, not more than 26%, not more than 24%, at most 22% by weight based on the total weight of said alkaline aqueous solution.
Ledit courant neutralisé formé à l'étape iv) comprend de préférence le composé A tel que décrit ci-dessus. La teneur en acide fluorhydrique dans ledit courant neutralisé est inférieure à la teneur en acide fluorhydrique dudit troisième courant, avant sa neutralisation. Ledit courant neutralisé peut éventuellement comprendre d'autres composés hydrocarbures. Ces composés hydrocarbures peuvent être des produits secondaires ou des impuretés obtenus lors de la préparation ou la production dudit composé A. Ledit courant neutralisé formé à l'étape (iv) peut également contenir de l'eau.  Said neutralized stream formed in step iv) preferably comprises compound A as described above. The hydrofluoric acid content in said neutralized stream is lower than the hydrofluoric acid content of said third stream prior to its neutralization. Said neutralized stream may optionally comprise other hydrocarbon compounds. These hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A. Said neutralized stream formed in step (iv) may also contain water.
Ledit courant neutralisé formé à l'étape iv) peut ainsi être séché à l'étape v) du présent procédé. De préférence, ledit courant neutralisé formé à l'étape iv) est séché sur tamis moléculaire. Par exemple, ledit courant neutralisé formé à l'étape iv) est séché sur tamis moléculaire de 3A, tel que la siliporite.  Said neutralized stream formed in step iv) can thus be dried in step v) of the present process. Preferably, said neutralized stream formed in step iv) is dried on molecular sieve. For example, said neutralized stream formed in step iv) is dried on 3A molecular sieve, such as siliporite.
L'étape v) du présent procédé permet la formation d'un courant neutralisé et séché E comprenant ledit composé A et optionnellement des composés hydrocarbures peuvent être des produits secondaires ou des impuretés obtenus lors de la préparation ou la production dudit composé A. Ledit courant E peut ensuite être comprimé et liquéfié à une pression d'au plus 8 bara pour former un courant F comprimé dans lequel le composé A et optionnellement des composés hydrocarbures peuvent être des produits secondaires ou des impuretés obtenus lors de la préparation ou la production dudit composé A sont sous forme liquide.  Stage v) of the present process allows the formation of a neutralized and dried stream E comprising said compound A and optionally hydrocarbon compounds may be by-products or impurities obtained during the preparation or production of said compound A. Said stream E can then be compressed and liquefied at a pressure of at most 8 bara to form a compressed stream F in which compound A and optionally hydrocarbon compounds can be by-products or impurities obtained in the preparation or production of said compound A are in liquid form.
Selon un mode de réalisation préféré, la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant est recyclée à l'étape i). La phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant peut être avoir une concentration en acide fluorhydrique supérieure à 41% en poids sur base du poids total de ladite phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant. Avantageusement, ladite phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant peut avoir une concentration en acide fluorhydrique supérieure à 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% ou 95% en poids sur base du poids total de ladite phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant. De préférence, ladite phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant peut être avoir une concentration en acide fluorhydrique comprise entre 45% et 95% en poids, entre 50% et 90% en poids, entre 55% et 85% en poids, entre 60% en poids et 80% en poids ou entre 65% en poids et 75% en poids sur base du poids total de ladite phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant. According to a preferred embodiment, the liquid phase resulting from the mixing of said liquid phase of said second two-phase current with said fourth current is recycled in step i). The liquid phase resulting from the mixing of said liquid phase of said second diphasic current with said fourth stream may be a concentration of hydrofluoric acid greater than 41% by weight based on the total weight of said liquid phase resulting from the mixing of said liquid phase of said second two-phase current with said fourth current. Advantageously, said liquid phase resulting from mixing said liquid phase of said second two-phase current with said fourth stream may have a hydrofluoric acid concentration greater than 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 66% 67% 68% 69% 70% 71% 72% 73% 74% 75% 76% 77% 78% 79% 80% 81% 82 %, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% by weight based on the total weight of said phase liquid resulting from mixing said liquid phase of said second two-phase current with said fourth stream. Preferably, said liquid phase resulting from the mixing of said liquid phase of said second two-phase stream with said fourth stream may be a concentration of hydrofluoric acid of between 45% and 95% by weight, between 50% and 90% by weight, between 55% and 95% by weight. % and 85% by weight, between 60% by weight and 80% by weight or between 65% by weight and 75% by weight based on the total weight of said liquid phase resulting from the mixing of said liquid phase of said second two-phase current with said fourth current.
Selon un autre mode de réalisation préféré, la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant est distillé pour former un courant C, de préférence en tête de colonne de distillation, en particulier le courant est un courant gazeux. Avantageusement, ledit courant C comprend de l'acide fluorhydrique contenant moins de 3000 ppm d'eau, de préférence moins de 2000 ppm d'eau, plus préférentiellement moins de 1000 ppm d'eau, en particulier moins de 500 ppm d'eau, plus particulièrement moins de 200 ppm d'eau, de manière privilégiée moins de 100 ppm d'eau, de manière plus privilégiée moins de 50 ppm d'eau sur base du poids total du courant C. Ledit courant C peut comprendre également moins de 50 ppm d'acide chlorhydrique, avantageusement moins de 45 ppm d'acide chlorhydrique, de préférence moins de 40 ppm d'acide chlorhydrique, plus préférentiellement moins de 35 ppm d'acide chlorhydrique, en particulier moins de 30 ppm d'acide chlorhydrique, plus particulièrement moins de 20 ppm d'acide chlorhydrique sur base du poids total du courant C. Ledit courant C peut comprendre également moins de 50 ppm de composés organiques, avantageusement moins de 45 ppm de composés organiques, de préférence moins de 40 ppm de composés organiques, plus préférentiellement moins de 35 ppm de composés organiques, en particulier moins de 30 ppm de composés organiques, plus particulièrement moins de 20 ppm de composés organiques sur base du poids total du courant C. Un composé organique est un composé comprenant au moins un atome de carbone. La température en pied de colonne de distillation peut être à une température de 80°C à 150°C, de préférence de 110°C et 130°C. La température en tête de colonne de distillation peut être comprise entre 10 et 60°C, de préférence entre 20 et 50°C. According to another preferred embodiment, the liquid phase resulting from mixing said liquid phase of said second two-phase stream with said fourth stream is distilled to form a stream C, preferably at the top of the distillation column, in particular the stream is a stream gaseous. Advantageously, said stream C comprises hydrofluoric acid containing less than 3000 ppm of water, preferably less than 2000 ppm of water, more preferably less than 1000 ppm of water, in particular less than 500 ppm of water, more particularly less than 200 ppm water, preferably less than 100 ppm water, more preferably less than 50 ppm water based on the total weight of the current C. Said current C can also include less than 50 ppm of hydrochloric acid, advantageously less than 45 ppm of hydrochloric acid, preferably less than 40 ppm of hydrochloric acid, more preferably less than 35 ppm of hydrochloric acid, in particular less than 30 ppm of hydrochloric acid, more particularly less than 20 ppm of hydrochloric acid based on the total weight of the current C. Said stream C may also comprise less than 50 ppm of organic compounds, advantageously less than 45 ppm of organic compounds, preferably less than 40 ppm of organic compounds. ppm of organic compounds, more preferably less than 35 ppm of organic compounds, in particular less than 30 ppm of organic compounds, more particularly less than 20 ppm of organic compounds based on the total weight of stream C. An organic compound is a compound comprising at least one carbon atom. The temperature at the bottom of the distillation column may be at a temperature of 80 ° C to 150 ° C, preferably 110 ° C and 130 ° C. The temperature at the top of the distillation column may be between 10 and 60 ° C., preferably between 20 and 50 ° C.
En outre, la distillation de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique avec ledit quatrième courant forme un courant D, de préférence en pied de colonne de distillation, comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids. En particulier, le courant D peut être liquide. Avantageusement, ledit courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids, 49% en poids, 48% en poids, 47% en poids, 46% en poids, 45% en poids, 44% en poids, 43% en poids, 42% en poids sur base du poids total dudit courant D. De préférence, ledit courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration supérieure à 20% en poids sur base du poids total dudit courant D. En particulier, ledit courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration supérieure 21% en poids, 22% en poids, 23% en poids, 24% en poids, 25% en poids, 26% en poids, 27% en poids, 28% en poids, 29% en poids, 30% en poids, 31% en poids, 32% en poids, 33% en poids, 34% en poids, 35% en poids sur base du poids total dudit courant D. Ladite solution aqueuse obtenue dans le courant D peut être commercialisée ou détruite par neutralisation.  In addition, the distillation of the liquid phase resulting from the mixing of said liquid phase of said second two-phase stream with said fourth stream forms a stream D, preferably at the bottom of the distillation column, comprising hydrofluoric acid in the form of a solution. aqueous concentration of less than 50% by weight. In particular, the current D can be liquid. Advantageously, said stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight, 49% by weight, 48% by weight, 47% by weight, 46% by weight, 45% by weight. weight, 44% by weight, 43% by weight, 42% by weight based on the total weight of said stream D. Preferably, said stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration greater than 20% by weight based on the total weight of said stream D. In particular, said stream D comprising hydrofluoric acid in the form of an aqueous solution of higher concentration 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight based on the total weight of said stream D. Said aqueous solution obtained in the stream D can be marketed or destroyed by neutralization.
Selon un autre mode de réalisation préféré, une partie de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est distillée pour former un courant C comprenant de l'acide fluorhydrique contenant moins de 500 ppm d'eau et un courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids, tel que mentionné ci-dessus, et une partie de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i). Ceci peut être effectué de manière alternée ou simultanée. De préférence, une partie de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est distillée et simultanément une partie de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i).  According to another preferred embodiment, a part of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is distilled to form a stream C comprising hydrofluoric acid containing less than 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution of concentration less than 50% by weight, as mentioned above, and a part of the liquid phase resulting from the mixing of said liquid phase of said second stream diphasic and fourth stream is recycled to step i). This can be done alternately or simultaneously. Preferably, a portion of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth stream is distilled and simultaneously a portion of the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth current is recycled in step i).
De préférence, au moins 50%, plus préférentiellement au moins 60%, en particulier au moins 70%, plus particulièrement au moins 80%, de manière privilégiée au moins 90% en poids de la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i) ; et moins de 50%, de préférence moins de 40%, plus préférentiellement moins de 30%, en particulier moins de 20%, plus particulièrement moins de 10% en poids est distillée pour former un courant C comprenant de l'acide fluorhydrique contenant moins de 500 ppm d'eau et un courant D comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids. Preferably, at least 50%, more preferably at least 60%, in particular at least 70%, more particularly at least 80%, preferably at least 90% by weight of the liquid phase resulting from the mixing of said liquid phase of said liquid phase. second diphasic current and the fourth current is recycled to step i); and less than 50%, preferably less than 40%, more preferably less than 30%, in particular less than 20%, more particularly less than 10% by weight is distilled to form a stream C comprising hydrofluoric acid containing less than 500 ppm of water and a stream D comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% by weight. weight.
Selon un mode de réalisation préféré, ledit premier courant est issu de la mise en contact entre un composé B et de l'acide fluorhydrique, ledit composé B ayant un nombre d'atomes de fluor inférieur à celui du composé A.  According to a preferred embodiment, said first stream is derived from the contacting between a compound B and hydrofluoric acid, said compound B having a number of fluorine atoms lower than that of the compound A.
Selon un mode de réalisation préféré, le composé hydrocarbure B peut contenir de un à douze atomes de carbone, de préférence de un à six atomes de carbone, en particulier le composé hydrocarbure B contient trois atomes de carbone. De préférence, le composé hydrocarbure B est de formule générale ChHaBrbClcFd, où h est un entier entre 1 et 6, a est un entier entre 0 et 13, b est un entier entre 0 et 4, c est un entier entre 1 et 14, d est un entier entre 0 et 13, et la somme de a, b, c et d est égale à 2h+2 ; ou de formule générale CpHeBrfClgFh, où p est un entier entre 2 et 6, e est un entier entre 0 et 12, f est un entier entre 0 et 2, g est un entier entre 0 et 12, h est un entier entre 0 et 11, et la somme de e, f, g et h est égale à 2p. According to a preferred embodiment, the hydrocarbon compound B can contain from one to twelve carbon atoms, preferably from one to six carbon atoms, in particular the hydrocarbon compound B contains three carbon atoms. Preferably, the hydrocarbon compound B is of the general formula ChH to BrbCl c Fd, where h is an integer between 1 and 6, a is an integer between 0 and 13, b is an integer between 0 and 4, c is an integer between 1 and 14, d is an integer between 0 and 13, and the sum of a, b, c and d is 2h + 2; or of general formula C p H e BrfCl g Fh, where p is an integer between 2 and 6, e is an integer between 0 and 12, f is an integer between 0 and 2, g is an integer between 0 and 12, h is an integer between 0 and 11, and the sum of e, f, g and h is equal to 2p.
De préférence, le composé hydrocarbure B est de formule générale ChHaClcFd, où h est un entier entre 2 et 4, a est un entier entre 0 et 9, c est un entier entre 1 et 9, d est un entier entre 0 et 9, et la somme de a, c et d est égal à 2h+2 ; ou de formule générale CpHeClgFh, où p est un entier entre 2 et 4, e est un entier entre 0 et 8 g est un entier entre 0 et 8, h est un entier entre 0 et 7, et la somme de e, f, g et h est égal à 2p. Preferably, the hydrocarbon compound B is of the general formula ChH a Cl c Fd, where h is an integer between 2 and 4, a is an integer between 0 and 9, c is an integer between 1 and 9, d is an integer between 0 and 9, and the sum of a, c and d is equal to 2h + 2; or of general formula C p H e Cl g Fh, where p is an integer between 2 and 4, e is an integer between 0 and 8 g is an integer between 0 and 8, h is an integer between 0 and 7, and the sum of e, f, g and h is equal to 2p.
Par exemple, ledit composé B peut être 1, 1,2-trichloroéthane (CHCI2CH2CI ou HCC-140),For example, said compound B can be 1, 1,2-trichloroethane (CHCl 2 CH 2 Cl or HCC-140),
1, 1,1,3,3,3-hexachlorodifluoropropane (CCI3CF2CCI3 ou CFC-212ca), 1, 1,1,3,3,3- hexachloropropane (CCI3CH2CCI3 ou HCC-230fa), 1, 1,1,3,3-pentachloropropane (CCI3CH2CHCI2 ou HCC-240fa), 2,2,3-trichloro-l, l, l,3,3-pentafluoropropane (CF3CCI2CCI F2 ou CFC-215aa), 1,3- dichloro-l,2,2,3,3-pentafluoropropane (CCI F2CF2CHCI F ou HCFC-225cb), 1, 1, 1,2,3- pentachloropropane (CCI3CHCICH2CI ou HCC-240db), 1, 1,2,2,3-pentachloropropane (CHCI2CCI2CH2CI ou HCC-240aa) ou 1, 1, 1,3,3-pentachloropropane (CCI3CH2CHCI2 ou HCC-240fa), l,2-dichloro-3,3,3-trifluoropropane (CF3CHCICH2CI ou HCFC-243db) ou un mélange de ceux-ci. En particulier, ledit composé B peut être 1, 1,1,2,3-pentachloropropane (CCI3CHCICH2CI ou HCC- 240db), 1, 1,2,2,3-pentachloropropane (CHCI2CCI2CH2CI ou HCC-240aa), 1,1, 1,2,2- pentachloropropane (CCI3CCI2CH3 ou HCC-240ab), 1, 1, 1,3,3-pentachloropropane (CCI3CH2CHCI2 ou HCC-240fa) ou 1,1,2-trichloroéthane (CHCI2CH2CI ou HCC-140), l,2-dichloro-3,3,3- trifluoropropane (CF3CHCICH2CI ou HCFC-243db) ou un mélange de ceux-ci. Ledit composé B peut également être 1,2-dichloroéthylène (CHCI=CCIH ou HCO-1130) l,l,2-trichloro-3,3,3-trifluoro-l-propène (CCl2=CCICF3 ou CFC-1213xa), l'hexafluoropropène (CF3CF=CF2 ou CFC-1216yc), 1,1,3,3,3-pentafluoropropène (CF3CH=CF2 ou HFO-1225zc), 1,3,3,3- tétrafluoropropène (CF3CH=CHF ou HFO-1234ze), 2-chloro-3,3,3-trifluoro-l-propène (CF3CCI=CH2 ou HCFO-1233xf), 1,1,2,3-tétrachloro-l-propène (CCI2=CCICH2CI ou HCO-1230xa), 2,3,3,3-tétrachloro-l-propène (CCl3CCI=CH2 ou HCO-1230xf), l-chloro-3,3,3-trifluoro-l-propène (CF3CH=CHCI ou HCFO-1233zd), 1,1,3,3-tétrachloro-l-propène (CCI2=CHCHCI2 ou HCO-1230za) ou 1,3,3,3-tétrachloroprop-l-ène (CCl3CH=CHCI ou HCO-1230zd) ou un mélange de ceux-ci. En particulier, ledit composé B peut être 2-chloro-3,3,3-trifluoro-l-propène (CF3CCI=CH2 ou HCFO- 1233xf), 1,1,2,3-tétrachloro-l-propène (CCI2=CCICH2CI ou HCO-1230xa), 2,3,3,3-tétrachloro-l- propène (CCI3CI=CH2 ou HCO-1230xf), l-chloro-3,3,3-trifluoro-l-propène (CF3CH=CHCI ou HCFO- 1233zd), 1,1,3,3-tétrachloro-l-propène (CCI2=CHCHCI2 ou HCO-1230za), 1,3,3,3- tétrachloroprop-l-ène (CCI3CH=CHCI ou HCO-1230zd) ou 1,2-dichloroéthylène (CHCI=CCIH ou HCO-1130) ou un mélange de ceux-ci. 1, 1,1,3,3,3-hexachlorodifluoropropane (CCI3CF2CCI3 or CFC-212ca), 1, 1,1,3,3,3-hexachloropropane (CCI3CH2CCI3 or HCC-230fa), 1, 1,1,3, 3-pentachloropropane (CCI3CH2CHCl2 or HCC-240fa), 2,2,3-trichloro-1,1,3,3-pentafluoropropane (CF3CCI2CCI F2 or CFC-215aa), 1,3-dichloro-1,2,2 , 3,3-pentafluoropropane (CCI F 2 CF 2 CHCl 3 F or HCFC-225cb), 1, 1, 1,2,3-pentachloropropane (CCI 3 CHCICH 2 Cl or HCC-240db), 1, 1,2,2,3-pentachloropropane (CHCI2CCI2CH2CI or HCC-240aa) or 1, 1, 1,3,3-pentachloropropane (CCI 3 CH 2 CHCl 2 or HCC-240fa), l, 2-dichloro-3,3,3-trifluoropropane (HCFC or CF3CHCICH2CI 243db) or a mixture thereof. In particular, said compound B may be 1,1,1,2,3-pentachloropropane (CCI3CHCICH2Cl or HCC-240db), 1, 1,2,2,3-pentachloropropane (CHCl 2 CCI 2 CH 2 CI or HCC-240aa ), 1,1,1,2,2-pentachloropropane (CCI3CCI2CH3 or HCC-240ab), 1, 1, 1,3,3-pentachloropropane (CCI3CH2CHCl2 or HCC-240fa) or 1,1,2-trichloroethane (CHCl 2 CH 2 CI or HCC-140), 1,2-dichloro-3,3,3-trifluoropropane (CF3CHCICH2Cl or HCFC-243db) or a mixture thereof. Said compound B can also be 1,2-dichloroethylene (CHCl = CClH or HCO-1130) 1,1,2-trichloro-3,3,3-trifluoro-1-propene (CCl2 = CCICF3 or CFC-1213xa), l hexafluoropropene (CF 3 CF = CF 2 or CFC-1216yc), 1,1,3,3,3-pentafluoropropene (CF 3 CH = CF 2 or HFO-1225zc), 1,3,3,3-tetrafluoropropene (CF 3 CH = CHF or HFO-1234ze), 2-chloro-3,3,3-trifluoro-1-propene (CF 3 CCI = CH 2 or HCFO-1233xf), 1,1,2,3-tetrachloro-1- propene (CCI 2 = CCICH 2 CI or HCO-1230xa), 2,3,3,3-tetrachloro-1-propene (CCl3CCI = CH 2 or HCO-1230xf), 1-chloro-3,3,3-trifluoro- 1-propene (CF 3 CH = CHCl or HCFO-1233zd), 1,1,3,3-tetrachloro-1-propene (CCI 2 = CHCHCl 2 or HCO-1230za) or 1,3,3,3-tetrachloropropene 1-ene (CCl3CH = CHCl or HCO-1230zd) or a mixture thereof. In particular, said compound B can be 2-chloro-3,3,3-trifluoro-1-propene (CF 3 CCI = CH 2 or HCFO-1233xf), 1,1,2,3-tetrachloro-1-propene ( CCI 2 = CCICH 2 CI or HCO-1230xa), 2,3,3,3-tetrachloro-1-propene (CCl 3 CI = CH 2 or HCO-1230xf), 1-chloro-3,3,3-trifluoro- l-propene (CF 3 CH = CHCl or HCFO- 1233zd), 1,1,3,3-tetrachloro-l-propene (CCI 2 = CHCHCI 2 or HCO-1230za), 1,3,3,3 tétrachloroprop- 1-ene (CCl 3 CH = CHCl or HCO-1230zd) or 1,2-dichloroethylene (CHCl = CClH or HCO-1130) or a mixture thereof.
Selon un mode de réalisation préféré, le composé B est de formule CH(n+2)(X)m-According to a preferred embodiment, the compound B has the formula CH ( n + 2 ) (X) m -
CHp(X)(n+i)-CX(3+p-m) où X représente indépendamment F ou Cl ; n, m, p sont indépendamment les uns des autres 0 ou 1 avec (n+m) = 0 ou 1, (n+p) = 0 ou 1 et (m-p) = 0 ou 1, au moins un X étant Cl ; et le composé A est le 2,3,3,3-tetrafluoropropène. Préférentiellement, le composé B est choisi dans le groupe constitué du 2-chloro-3,3,3-trifluoro-l-propène (H FCO-1233xf), 1,1,1,2,3- pentachloropropane (HCC-240db), l,2-dichloro-3,3,3-trifluoropropane, 1,1,2,3-tétrachloro-l- propène (HCO-1230xa), 2,3,3,3-tétrachloro-l-propène (HCO-1230xf), 1,1,1,2,2- pentachloropropane, ou leurs mélanges, pour la production du 2,3,3,3-tétrafluoropropène (HFO-1234yf). CHp (X) (n + 1) -CX ( 3 + p- m) wherein X is independently F or Cl; n, m, p are independently of one another 0 or 1 with (n + m) = 0 or 1, (n + p) = 0 or 1 and (mp) = 0 or 1, at least one X being Cl; and compound A is 2,3,3,3-tetrafluoropropene. Preferably, compound B is selected from the group consisting of 2-chloro-3,3,3-trifluoro-1-propene (H FCO-1233xf), 1,1,1,2,3-pentachloropropane (HCC-240db) , 1,2-dichloro-3,3,3-trifluoropropane, 1,1,2,3-tetrachloro-1-propene (HCO-1230xa), 2,3,3,3-tetrachloro-1-propene (HCO- 1230xf), 1,1,1,2,2-pentachloropropane, or mixtures thereof, for the production of 2,3,3,3-tetrafluoropropene (HFO-1234yf).
La mise en contact entre le composé B et l'acide fluorhydrique pour produire le composé A peut être effectuée dans un réacteur. De préférence, la mise en contact entre le composé B et l'acide fluorhydrique est effectuée en phase gazeuse. La mise en contact entre le composé B et l'acide fluorhydrique est effectuée en présence ou non d'un catalyseur.  The contacting between compound B and hydrofluoric acid to produce compound A can be carried out in a reactor. Preferably, the contacting between compound B and hydrofluoric acid is carried out in the gas phase. The contacting between compound B and hydrofluoric acid is carried out in the presence or absence of a catalyst.
Selon un mode de réalisation préféré, la mise en contact entre le composé B et l'acide fluorhydrique peut être effectuée suivant les conditions opératoires suivantes :  According to a preferred embodiment, the contacting between compound B and hydrofluoric acid can be carried out according to the following operating conditions:
- un rapport molaire HF/composé hydrocarbure entre 1:1 et 150:1, de préférence entre 2:1 et 125:1, plus préférentiellement entre 3:1 et 100:1 ; an HF / hydrocarbon compound molar ratio between 1: 1 and 150: 1, preferably between 2: 1 and 125: 1, more preferably between 3: 1 and 100: 1;
un temps de contact entre 1 et 100 s, de préférence entre 2 et 75 s, en particulier entre 3 et 50 s ; une pression entre la pression atmosphérique et 20 bara, de préférence entre 2 et 18 bara, plus préférentiellement entre 3 et 15 bara ; a contact time between 1 and 100 s, preferably between 2 and 75 s, in particular between 3 and 50 s; a pressure between atmospheric pressure and 20 bara, preferably between 2 and 18 bara, more preferably between 3 and 15 bara;
une température entre 200 et 450°C, de préférence entre 250 et 400°C, plus préférentiellement entre 280°C et 380°C.  a temperature between 200 and 450 ° C, preferably between 250 and 400 ° C, more preferably between 280 ° C and 380 ° C.
La mise en contact peut être effectuée sur une durée comprise entre 10 et 8000 h, de préférence entre 50 et 5000 h, plus préférentiellement entre 70 et 1000 h.  The contacting can be carried out over a period of between 10 and 8000 h, preferably between 50 and 5000 h, more preferably between 70 and 1000 h.
On peut ajouter un oxydant, comme l'oxygène ou le chlore, en cours de procédé. Le rapport molaire de l'oxydant sur le composé hydrocarbure peut être entre 0,005 et 2, de préférence entre 0,01 et 1,5. L'oxydant peut être de l'oxygène pur, de l'air ou un mélange d'oxygène et d'azote.  An oxidant, such as oxygen or chlorine, can be added during the process. The molar ratio of the oxidant to the hydrocarbon compound may be between 0.005 and 2, preferably between 0.01 and 1.5. The oxidant may be pure oxygen, air or a mixture of oxygen and nitrogen.
Lorsqu'elle est réalisée en phase gazeuse et en présence de catalyseur, la mise en contact entre le composé B et l'acide fluorhydrique peut être mise en œuvre en présence d'un catalyseur à base d'un métal comprenant un oxyde de métal de transition ou un dérivé ou un halogénure ou un oxyhalogénure d'un tel métal. On peut citer par exemple FeC , l'oxyfluorure de chrome, les oxydes de chrome (éventuellement soumis à des traitements de fluoration), les fluorures de chrome et leurs mélanges. D'autres catalyseurs possibles sont les catalyseurs supportés sur du carbone, les catalyseurs à base d'antimoine, les catalyseurs à base d'aluminium (par exemple AI F3 et AI2O3, l'oxyfluorure d'alumine et le fluorure d'alumine). On peut utiliser en général un oxyfluorure de chrome, un fluorure ou un oxyfluorure d'aluminium, ou un catalyseur supporté ou non contenant un métal tel que Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge, Sn, Pb, Mg, Sb. On peut faire référence à cet égard au document WO 2007/079431 (en p.7, 1.1-5 et 28-32), au document EP 939071 (paragraphe [0022]), au document WO 2008/054781 (en p.9 l.22-p.l0 1.34), et au document WO 2008/040969 (revendication 1), auxquels il est fait expressément référence. Le catalyseur est de manière plus particulièrement préférée à base de chrome et il s'agit plus particulièrement d'un catalyseur mixte comprenant du chrome .Selon un mode de réalisation, on utilise pour l'une quelconque des étapes de réaction un catalyseur mixte comprenant du chrome et du nickel. Le rapport molaire Cr / Ni (sur la base de l'élément métallique) est généralement de 0,5 à 5, par exemple de 0,7 à 2, par exemple d'environ 1. Le catalyseur peut contenir de 0,5 à 20 % en poids de nickel. Le métal peut être présent sous forme métallique ou sous forme de dérivé, par exemple un oxyde, halogénure ou oxyhalogénure. Ces dérivés sont de préférence obtenus par activation du métal catalytique. Le support est de préférence constitué avec de l'aluminium, par exemple de l'alumine, de l'alumine activée ou des dérivés d'aluminium, tels que les halogénures d'aluminium et les oxyhalogénures d'aluminium, par exemple décrits dans le document US 4,902,838, ou obtenus par le procédé d'activation décrit ci-dessus. Le catalyseur peut comprendre du chrome et du nickel sous une forme activée ou non, sur un support qui a été soumis à une activation ou non. On peut se reporter au document WO 2009/118628 (notamment en p.4, l.30-p.7 1.16), auquel il est fait expressément référence ici. Un autre mode de réalisation préféré repose sur un catalyseur mixte contenant du chrome, de préférence sous forme d'oxyde ou d'oxyfluorure, et au moins un co-catalyseur choisi parmi les sels de Co, Mn, Mg et Zn, de préférence Zn. Ledit co-catalyseur est de préférence présent dans une teneur de 1 à 10% en poids sur base du poids du catalyseur. Avant son utilisation, le catalyseur est de préférence soumis à une activation avec de l'air, de l'oxygène ou du chlore et/ou avec de l'HF. Par exemple, le catalyseur est de préférence soumis à une activation avec de l'air ou de l'oxygène et de l'HF à une température de 100 à 500°C, de préférence de 250 à 500°C et plus particulièrement de 300 à 400°C. La durée d'activation est de préférence de 1 à 200 h et plus particulièrement de 1 à 50 h. Cette activation peut être suivie d'une étape d'activation de fluoration finale en présence d'un agent d'oxydation, d'HF et de composés organiques. Le rapport molaire HF / composés organiques est de préférence de 2 à 40 et le rapport molaire agent d'oxydation / composés organiques est de préférence de 0,04 à 25. La température de l'activation finale est de préférence de 300 à 400°C et sa durée de préférence de 6 à 100 h. When it is carried out in the gaseous phase and in the presence of a catalyst, the contacting between compound B and hydrofluoric acid may be carried out in the presence of a catalyst based on a metal comprising a metal oxide of transition or a derivative or a halide or an oxyhalide of such a metal. Mention may be made, for example, of FeC, chromium oxyfluoride, chromium oxides (optionally subjected to fluorination treatments), chromium fluorides and mixtures thereof. Other possible catalysts are carbon supported catalysts, antimony catalysts, aluminum catalysts (for example AI F3 and Al2O3, alumina oxyfluoride and alumina fluoride). It is generally possible to use a chromium oxyfluoride, a fluoride or an aluminum oxyfluoride, or a supported or non-supported catalyst containing a metal such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge or Sn. Pb, Mg, Sb. Reference can be made in this regard to document WO 2007/079431 (at p.7, 1.1-5 and 28-32), EP 939071 (paragraph [0022]), WO 2008/054781 (at p.9). l.22-p.l0 1.34), and WO 2008/040969 (claim 1), to which reference is expressly made. The catalyst is more preferably based on chromium and it is more particularly a mixed catalyst comprising chromium. According to one embodiment, for any one of the reaction steps a mixed catalyst comprising chrome and nickel. The molar ratio Cr / Ni (based on the metal element) is generally 0.5 to 5, for example 0.7 to 2, for example about 1. The catalyst may contain from 0.5 to 20% by weight of nickel. The metal may be present in metallic form or in the form of a derivative, for example an oxide, halide or oxyhalide. These derivatives are preferably obtained by activation of the catalytic metal. The support is preferably made of aluminum, for example alumina, activated alumina or aluminum derivatives, such as aluminum halides and aluminum oxyhalides, for example described in US 4,902,838, or obtained by the activation method described above. The catalyst may comprise chromium and nickel in an activated or non-activated form, on a support which has been subjected to activation or not. Reference can be made to WO 2009/118628 (especially at p.4, l.30-p.7 1.16), which is expressly referred to herein. Another preferred embodiment is based on a mixed catalyst containing chromium, preferably in oxide or oxyfluoride form, and at least one co-catalyst chosen from the salts of Co, Mn, Mg and Zn, preferably Zn . Said cocatalyst is preferably present in a content of 1 to 10% by weight based on the weight of the catalyst. Prior to use, the catalyst is preferably activated with air, oxygen or chlorine and / or with HF. For example, the catalyst is preferably subjected to activation with air or oxygen and HF at a temperature of 100 to 500 ° C, preferably 250 to 500 ° C and more preferably 300 to 500 ° C. at 400 ° C. The activation time is preferably from 1 to 200 hours and more particularly from 1 to 50 hours. This activation may be followed by a final fluorination activation step in the presence of an oxidizing agent, HF and organic compounds. The molar ratio of HF / organic compounds is preferably from 2 to 40 and the molar ratio of oxidation agent / organic compounds is preferably from 0.04 to 25. The temperature of the final activation is preferably from 300 to 400 ° C. C and its duration preferably from 6 to 100 h.
Lorsqu'elle est réalisée en phase gazeuse et en l'absence de catalyseur, la mise en contact entre le composé B et l'acide fluorhydrique peut être mise en œuvre avec un ratio molaire HF/composé de formule (I) de 3 :1 à 150 :1, et de préférence à une température de 200 à 450°C, et de préférence de 300 à 430°C.  When it is carried out in the gaseous phase and in the absence of a catalyst, the contacting between compound B and hydrofluoric acid can be carried out with a HF / compound of formula (I) molar ratio of 3: 1 at 150: 1, and preferably at a temperature of from 200 to 450 ° C, and preferably from 300 to 430 ° C.
La figure 1 représente schématiquement un procédé selon un mode de réalisation particulier de la présente invention. Le premier courant 1 comprend le composé A, par exemple 2,3,3,3-tetrafluoropropène, et alimente un dispositif 2 dans lequel il est mis en contact avec une solution d'acide fluorhydrique ou une solution d'acide fluorhydrique issue de la conduite 20 ayant une concentration variant entre 65 et 75% en poids. Le dispositif 2 peut être par exemple un hydrolaveur. La mise en contact entre la solution d'acide fluorhydrique ou une solution d'acide fluorhydrique issue de la conduite 20 et le premier courant 1 génère la formation d'un courant diphasique qui est acheminé vers un dispositif de stockage 4 par la conduite 13. Le dispositif de stockage 4 permet de séparer le courant diphasique en une phase gazeuse et une phase liquide. La phase gazeuse Gl dudit courant diphasique est acheminée par la conduite 14 vers la colonne d'absorption 3 comprenant 3 étages d'absorption 21a, 21b et 21c. La colonne d'absorption 3 est également alimentée par un flux aqueux 7. Dans ce mode de réalisation, le flux aqueux 7 alimente la colonne d'absorption 3 en tête de colonne d'absorption 7, c'est-à-dire au-dessus des trois étages d'absorption 21a-21c. Alternativement, le flux gazeux 7 peut alimenter la colonne d'absorption 3 au-dessus de chacun des étages d'absorption 21a-21c. Un courant gazeux comprenant le composé A est extrait en tête de colonne d'absorption 3 par la conduite 16 pour alimenter un dispositif de neutralisation 5. Le courant gazeux extrait en tête de colonne d'absorption 3 correspond audit troisième courant selon la présente invention. En outre, en pied de colonne d'absorption 7, une solution aqueuse d'acide fluorhydrique correspondant audit quatrième courant est recyclée vers le dispositif de stockage 4 par la conduite 15. Figure 1 schematically shows a method according to a particular embodiment of the present invention. The first stream 1 comprises the compound A, for example 2,3,3,3-tetrafluoropropene, and feeds a device 2 in which it is brought into contact with a solution of hydrofluoric acid or a solution of hydrofluoric acid derived from the pipe 20 having a concentration ranging from 65 to 75% by weight. The device 2 may for example be a hydrolaver. The contacting between the hydrofluoric acid solution or a solution of hydrofluoric acid resulting from the pipe 20 and the first stream 1 generates the formation of a two-phase current which is conveyed to a storage device 4 via the pipe 13. The storage device 4 makes it possible to separate the two-phase current into a gaseous phase and a liquid phase. The gaseous phase G1 of said two-phase current is conveyed via line 14 to the absorption column 3 comprising three absorption stages 21a, 21b and 21c. The column 3 is also fed by an aqueous stream 7. In this embodiment, the aqueous stream 7 feeds the absorption column 3 at the head of the absorption column 7, that is to say above the three absorption stages 21a-21c. Alternatively, the gas stream 7 can feed the absorption column 3 above each of the absorption stages 21a-21c. A gaseous stream comprising compound A is extracted at the top of absorption column 3 through line 16 to supply a neutralization device 5. The gaseous stream extracted at the top of absorption column 3 corresponds to said third stream according to the present invention. In addition, at the bottom of absorption column 7, an aqueous solution of hydrofluoric acid corresponding to said fourth stream is recycled to storage device 4 via line 15.
Le troisième courant est neutralisé dans le dispositif de neutralisation 5 par une solution alcaline de NaOH à 20%. La solution alcaline 8 alimente le dispositif de neutralisation 5 par l'intermédiaire de la conduite 19. Le courant neutralisé est évacué par la conduite 17 et récupéré en 10 pour être séché sur tamis moléculaire de 3A. Le courant neutralisé et séché correspond au courant E selon le présent procédé. Celui-ci peut donc être comprimé et liquéfié à une pression d'au plus 8 bara. Une solution alcaline usée 9 peut être extraite du dispositif de neutralisation 5 pour être soit recyclée via les conduites 18 et 19 ou évacuée via la conduite 18 pour traitement ultérieur.  The third stream is neutralized in the neutralization device with an alkaline solution of 20% NaOH. The alkaline solution 8 feeds the neutralization device 5 through line 19. The neutralized stream is discharged through line 17 and recovered at 10 to be dried on 3A molecular sieve. The neutralized and dried stream corresponds to the stream E according to the present process. This can be compressed and liquefied at a pressure of at most 8 bara. A spent alkaline solution 9 may be removed from the neutralization device 5 to be either recycled via the lines 18 and 19 or discharged via the line 18 for further processing.
La phase liquide résultant du mélange de la phase liquide du courant diphasique et du quatrième courant stockée dans le dispositif de stockage 4 est acheminée vers une colonne de distillation 6 via la pompe 22 et la conduite 23 pour former le courant C récupéré en tête de colonne de distillation 11 et le courant D récupéré en pied de colonne de distillation 12.  The liquid phase resulting from the mixing of the liquid phase of the two-phase current and the fourth current stored in the storage device 4 is conveyed to a distillation column 6 via the pump 22 and the pipe 23 to form the stream C recovered at the top of the column 11 and the stream D recovered at the bottom of the distillation column 12.
La pompe 22 peut également être configurée pour acheminer la phase liquide résultant du mélange de la phase liquide du courant diphasique et du quatrième courant stockée dans le dispositif de stockage 4 vers le dispositif 2 via la conduite 20. Ceci est représenté à la Figure 2. La pompe 22 est ainsi configurée pour permettre l'alimentation de la colonne de distillation 11 et le dispositif 2 de manière alternée, de manière simultanée, de préférence de manière simultanée.  The pump 22 can also be configured to convey the liquid phase resulting from mixing the liquid phase of the two-phase current and the fourth current stored in the storage device 4 to the device 2 via the pipe 20. This is represented in FIG. 2. The pump 22 is thus configured to allow the supply of the distillation column 11 and the device 2 alternately, simultaneously, preferably simultaneously.
Le présent procédé permet de récupérer l'acide fluorhydrique présent dans un flux gazeux via notamment l'utilisation d'une colonne d'absorption, permettant ainsi de purifier ledit flux gazeux. En outre, le présent procédé permet dans un mode de réalisation particulier de coupler un dispositif d'absorption d'acide fluorhydrique avec un dispositif de distillation d'acide fluorhydrique pour produire de l'acide fluorhydrique anhydre ou substantiellement anhydre, i.e. courant C, tel qu'expliqué ci-dessus. Ceci permet de maximiser la réutilisation de l'acide fluorhydrique sous forme d'acide fluorhydrique anhydre ou substantiellement anhydre dans une réaction de fluoration, par exemple d'un composé B tel qu'expliqué ci-dessus. Le présent procédé permet en outre d'obtenir de l'acide fluorhydrique anhydre ou substantiellement anhydre contenant au plus des traces d'acide chlorhydrique ou de composés organiques. The present method makes it possible to recover the hydrofluoric acid present in a gaseous stream, in particular by using an absorption column, thus making it possible to purify said gaseous flow. In addition, the present method makes it possible, in a particular embodiment, to couple a hydrofluoric acid absorption device with a hydrofluoric acid distillation device to produce anhydrous or substantially anhydrous hydrofluoric acid, ie current C, as explained above. This makes it possible to maximize the reuse of hydrofluoric acid in the form of anhydrous or substantially anhydrous hydrofluoric acid in a fluorination reaction, for example of a compound B as explained above. The present process also makes it possible to obtain anhydrous or substantially anhydrous hydrofluoric acid containing at most traces of hydrochloric acid or of organic compounds.
Exemple 1 Example 1
Un premier courant comprenant 93,27 % en poids de composé A et 6,73% en poids d'acide fluorhydrique est mis en contact avec une solution aqueuse d'aide fluorhydrique ayant une concentration de 67% en poids. La phase gazeuse du courant diphasique produit alimente une colonne d'absorption comprenant deux étages. Le troisième courant tel que décrit dans la présente demande est récupéré en tête de colonne d'absorption. Le quatrième courant tel que décrit dans la présente demande est récupéré en pied de colonne d'absorption. Ce dernier est distillé pour permettre la production d'un courant gazeux comprenant 99,92% en poids d'acide fluorhydrique. A first stream comprising 93.27% by weight of compound A and 6.73% by weight of hydrofluoric acid is contacted with an aqueous hydrofluoric aid solution having a concentration of 67% by weight. The gaseous phase of the two-phase current produced feeds an absorption column comprising two stages. The third current as described in the present application is recovered at the top of the absorption column. The fourth stream as described in the present application is recovered at the bottom of the absorption column. The latter is distilled to allow the production of a gaseous stream comprising 99.92% by weight of hydrofluoric acid.
Le tableau 1 ci-dessous détaille les teneurs en différents composés à différentes étapes du présent procédé. Les numéros mentionnés dans le tableau correspondent aux flux/courants décrits en relation avec les figures 1 et 2.  Table 1 below details the contents of various compounds at different stages of the present process. The numbers mentioned in the table correspond to the flows / currents described with reference to FIGS. 1 and 2.
Tableau 1 Table 1
Figure imgf000019_0001
Figure imgf000019_0001
Exemple 2 Example 2
L'exemple 1 est reproduit avec une colonne à trois étages d'absorption. Le tableau 2 ci- dessous détaille les teneurs en différents composés à différentes étapes du présent procédé. Les numéros mentionnés dans le tableau correspondent aux flux/courants décrits en relation avec les figures 1 et 2.  Example 1 is reproduced with a column with three absorption stages. Table 2 below details the contents of various compounds at different stages of the present process. The numbers mentioned in the table correspond to the flows / currents described with reference to FIGS. 1 and 2.
Tableau 2 Composition Table 2 Composition
1 20 7 16 23 11 12 massique %  1 20 7 16 23 11 12 mass%
Composé A 93,27 0,04 0,00 99,38 0,04 0,08 Traces Compound A 93.27 0.04 0.00 99.38 0.04 0.08 Traces
HF 6,73 68,55 0,00 7 ppm 68,55 99,92 38,63HF 6.73 68.55 0.00 7 ppm 68.55 99.92 38.63
H20 0,00 31,41 100,00 0,62 31,41 Traces 61,37 H20 0.00 31.41 100.00 0.62 31.41 Traces 61.37
Les exemples ci-dessus démontrent que le présente procédé permet de récupérer un courant gazeux du composé comprenant une très faible teneur en HF mais permet également de récupérer de l'acide fluorhydrique anhydre. The above examples demonstrate that the present process makes it possible to recover a gaseous stream of the compound comprising a very low content of HF but also makes it possible to recover anhydrous hydrofluoric acid.

Claims

Revendications claims
1. Procédé de récupération d'acide fluorhydrique comprenant les étapes de : A process for recovering hydrofluoric acid comprising the steps of:
i) mise en contact d'un premier courant comprenant un composé hydrocarbure A ayant au moins un atome de fluor et de l'acide fluorhydrique, de préférence sous forme gazeuse, avec une solution aqueuse d'acide fluorhydrique de concentration supérieure à 40 % en poids pour former un second courant diphasique comprenant le composé A et l'acide fluorhydrique, ii) stockage dudit second courant diphasique dans un réservoir tampon, ledit second courant diphasique étant constitué d'une phase liquide et d'une phase gazeuse Gl, i) contacting a first stream comprising a hydrocarbon compound A having at least one fluorine atom and hydrofluoric acid, preferably in gaseous form, with an aqueous solution of hydrofluoric acid of concentration greater than 40% by weight; weight for forming a second two-phase current comprising compound A and hydrofluoric acid, ii) storing said second two-phase current in a buffer tank, said second two-phase current consisting of a liquid phase and a gas phase G1,
iii) passage de ladite phase gazeuse Gl dudit second courant diphasique dans une colonne d'absorption alimenté à contre-courant par un flux aqueux pour former un troisième courant comprenant le composé A et un quatrième courant comprenant l'acide fluorhydrique. iii) passing said gaseous phase G1 of said second diphasic stream into an absorption column fed countercurrently with an aqueous stream to form a third stream comprising compound A and a fourth stream comprising hydrofluoric acid.
2. Procédé selon la revendication 1 caractérisé en ce qu'il comprend les étapes : 2. Method according to claim 1 characterized in that it comprises the steps:
iv) neutralisation dudit troisième courant obtenu à l'étape iii) par une solution aqueuse alcaline pour former un courant neutralisé, et iv) neutralizing said third stream obtained in step iii) with an aqueous alkaline solution to form a neutralized stream, and
v) séchage dudit courant neutralisé obtenu à l'étape iv) sur tamis moléculaire. v) drying said neutralized stream obtained in step iv) on molecular sieve.
3. Procédé selon la revendication 1 ou la revendication 2 caractérisé en ce que le quatrième courant est recyclé à l'étape ii). 3. Method according to claim 1 or claim 2 characterized in that the fourth stream is recycled to step ii).
4. Procédé selon l'une quelconque des revendications 1 à 3 caractérisé en ce que ledit courant diphasique consiste en une phase gazeuse Gl comprenant le composé A et une phase liquide comprenant de l'acide fluorhydrique et moins de 5% en poids de composé A sur base du poids total de ladite phase liquide. 4. Method according to any one of claims 1 to 3 characterized in that said two-phase current consists of a gas phase G1 comprising compound A and a liquid phase comprising hydrofluoric acid and less than 5% by weight of compound A based on the total weight of said liquid phase.
5. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que la solution aqueuse d'acide fluorhydrique utilisé à l'étape i) est à une température comprise entre 0 à 30°C avant sa mise en contact avec ledit premier courant. 5. Method according to any one of the preceding claims, characterized in that the aqueous hydrofluoric acid solution used in step i) is at a temperature between 0 and 30 ° C before being brought into contact with said first stream.
6. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est distillée pour former un courant C, de préférence en tête de colonne de distillation, comprenant de l'acide fluorhydrique contenant moins de 500 ppm d'eau et un courant D, de préférence en pied de colonne de distillation, comprenant de l'acide fluorhydrique sous forme d'une solution aqueuse de concentration inférieure à 50% en poids. 6. Method according to any one of the preceding claims characterized in that the liquid phase resulting from mixing said liquid phase of said second two-phase current and the fourth stream is distilled to form a stream C, preferably at the column head distillation composition, comprising hydrofluoric acid containing less than 500 ppm of water and a stream D, preferably at the bottom of the distillation column, comprising hydrofluoric acid in the form of an aqueous solution with a concentration of less than 50% in weight.
7. Procédé selon l'une quelconque des revendications précédentes 1 à 5 caractérisé en ce que la phase liquide résultant du mélange de ladite phase liquide dudit second courant diphasique et du quatrième courant est recyclée à l'étape i). 7. Method according to any one of the preceding claims 1 to 5 characterized in that the liquid phase resulting from the mixing of said liquid phase of said second two-phase current and the fourth current is recycled to step i).
8. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le troisième courant comprend moins de 5% en poids d'acide fluorhydrique sur base du poids total dudit troisième courant. 8. Method according to any one of the preceding claims characterized in that the third stream comprises less than 5% by weight of hydrofluoric acid based on the total weight of said third stream.
9. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que ladite colonne d'absorption utilisée à l'étape iii) comprend au moins un étage d'absorption. 9. Method according to any one of the preceding claims characterized in that said absorption column used in step iii) comprises at least one absorption stage.
10. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le rapport entre le débit exprimé en kg/h du flux aqueux alimentant la colonne d'absorption à l'étape iii) et la quantité d'acide fluorhydrique dans ledit premier courant exprimée en kg/h est compris entre 0,25 et 1,22, de préférence entre 0,33 et 0,54. 10. Process according to any one of the preceding claims, characterized in that the ratio between the flow rate expressed in kg / h of the aqueous flow feeding the absorption column in step iii) and the quantity of hydrofluoric acid in said first current expressed in kg / h is between 0.25 and 1.22, preferably between 0.33 and 0.54.
11. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que ledit premier courant est issu de la mise en contact entre un composé B et de l'acide fluorhydrique, ledit composé B ayant un nombre d'atomes de fluor inférieur à celui du composé A. 11. Method according to any one of the preceding claims, characterized in that said first stream is derived from the contacting between a compound B and hydrofluoric acid, said compound B having a number of fluorine atoms lower than that compound A.
12. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le composé B est de formule CH )(X)m-CHp(X)(n+i)-CX +p-m) où X représente indépendamment F ou Cl ; n, m, p sont indépendamment les uns des autres 0 ou 1 avec (n+m) = 0 ou 1, (n+p) = 0 ou 1 et (m-p) = 0 ou 1, au moins un X étant Cl ; et le composé A est le 2,3,3,3-tetrafluoropropène. 12. Process according to any one of the preceding claims, characterized in that the compound B is of formula CH) (X) m-CHp (X) (n + 1) -CX + p- m ) where X represents independently F or Cl; n, m, p are independently of one another 0 or 1 with (n + m) = 0 or 1, (n + p) = 0 or 1 and (mp) = 0 or 1, at least one X being Cl; and compound A is 2,3,3,3-tetrafluoropropene.
PCT/FR2018/050733 2017-03-28 2018-03-27 Method for recovering hydrofluoric acid WO2018178553A1 (en)

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