The invention relates to a process for purifying 2,3,3,3-tetrafluoro-l-propene. In addition, the invention also relates to a process for production and purification of 2,3,3,3-tetrafluoro-l-propene.

BACKGROUND OF THE INVENTION

Hydrofluorocarbons (HFCs) and particularly hydrofluoroolefins (HFOs), such as 2,3,3,3-tetrafluoro-l-propene (HFO-1234yf) are compounds known for their properties of refrigerants and heat transfer fluids, fire extinguishing, propellants, foaming agents, blowing agents, gaseous dielectrics, polymerization medium or monomer, fluid media, abrasives agents, drying agents and fluids for energy production unit. The HFO have been identified as desirable alternatives to HCFCs due to their low values ​​ODP (Ozone Depletion Potential and potential to deplete the ozone layer) and GWP (Global Warming Potential or GWP).

Most manufacturing processes hydrofluoroolefins use a fluorination reaction and / or dehydrohalogenation. This type of reaction is carried out in the gas phase and generates impurities that must therefore be removed to obtain the desired compound in sufficient purity for the intended applications.

For example, in the context of the production of 2,3,3,3-tetrafluoro-l-propene (HFO-1234yf), the presence of impurities such as l-chloro-3,3,3-trifluoro-l propene (1233zd), 1,3,3,3-tetrafluoro-l-propene (1234ze), and 1,1,1,3,3-pentafluoropropane (245fa) are observed. These impurities are isomers of the major components to be obtained by the method for producing 2,3,3,3-tetrafluoro-l-propene addition thereto, ie 2-chloro-3,3,3-trifluoro-l- propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb). Given the respective boiling points of l-chloro-3,3,3-trifluoro-l-propene (1233zd), 1,3,3,3-tetrafluoro-l-propene (1234ze) and 1,1, 1,3,3-pentafluoropropane (245fa), they can build up in the reaction loop and thus prevent the formation of products of interest.

Purification of this type of reaction may be effected by various techniques known to the prior art, such as e.g. distillation. However, when the compounds to be purified have boiling points too close or when they form azeotropes or azeotrope-like compositions, distillation is not an efficient process. extractive distillation methods have been described.

by EP 0864554 discloses a method for purifying a mixture comprising

1,1,1,3,3-pentafluoropropane (245fa) and l-chloro-3,3,3-trifluoro-trans-l-propene (1233zd) by distillation in the presence of a solvent having a boiling point that of 1-chloro-3,3,3-trifluoro-trans-l-propene.

by WO 03/068716 discloses a method of recovering pentafluoroethane from a mixture comprising pentafluoroethane and chloropentafluoroethane by distillation in the presence of hexafluoropropene.

is also known from WO 98/19982 a method for purifying 1,1-difluoroethane by extractive distillation. The method comprises contacting an extraction agent with a mixture of 1,1-difluoroethane and vinyl chloride. The extraction agent is selected from hydrocarbons, alcohols, chlorocarbons having a boiling point between 10 ° C and

120 ° C. As mentioned in WO 98/19982, the selection of the extracting agent can be complex depending on the products to be separated. Is known from WO 2013/088195 a process for preparing 2,3,3,3-tetrafluoropropene from 1,1,1,2,3-pentachloropropane and / or

1,1,2,2,3-pentachloropropane. There is therefore still a need for the implementation of a particular method for purifying 2,3,3,3-tetrafluoro-l-propene.

Summary of the Invention

In a method for producing 2,3,3,3-tetrafluoro-l-propene, the choice of specific operational conditions may favor the presence of certain impurities or isomers thereof. The presence of impurities such as 1,3,3,3-tetrafluoro-l-propene (1234ze) may be seen as that of l-chloro-3,3,3-trifluoro-l-propene (1233zd), and 1,1,1,3,3-pentafluoropropane (245fa). These impurities can originate from side reactions induced by compounds produced as an intermediate during the production of 2,3,3,3-tetrafluoro-l-propene, and may have physical properties such as their removal may be complex. The present invention enables notably the production of 2,3,3,3-tetrafluoro-l-propene with improved purity.

According to a first aspect, the invention provides a process for production and purification of 2,3,3,3-tetrafluoropropene (1234yf) implemented from a starting composition comprising at least one compound of the formula CX (Y ) 2 CX (Y) m -CH m XY (I) wherein X and Y are independently H, F, or Cl and m = 0 or 1; and / or in the presence of a fluorination

catalyst of a compound of formula (CX n Y 3-n) CHpXi pCH- m X 2-m (II) wherein X is independently of each other Cl, F, I or Br; Y is independently of each other H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1 or 2; and p is 0 or 1;

said method comprising the steps of:

a) contacting, in the presence of a catalyst, the starting composition with HF to produce a composition A comprising HCl, a portion of unreacted HF, 2,3,3,3-tetrafluoropropene (1234yf) , intermediates B consisting of 2-chloro-3,3,3-trifluoropropene (1233xf), 1,1,1,2,2-pentafluoropropane (245cb) and C-products consisting of El-chloro-3, 3,3-trifluoro-l-propene (1233zdE), trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and 1,1,1,3,3-pentafluoropropane (245fa);

b) recovering said composition A and purification, preferably distillation thereof to form and recover a first stream, preferably a gas comprising HCl, 2,3,3,3-tetrafluoropropene (1234yf), some of the goods intermediate B and part of the C-products; and a current, preferably liquid Ll comprising a portion of the HF unreacted, a portion of the intermediate products B and part of the C-products; c) purification of said first stream to form a stream comprising a portion of said portion of the intermediate products B and Part C side products and recycling thereof to step a).

According to a preferred embodiment, said first stream is a gas stream Gl purified by the following steps:

bl) distillation Gl gas stream to recover a Gla stream comprising HCl, advantageously in the distillation column, and a Glb stream comprising 2,3,3,3-tetrafluoropropene (1234yf), said part of the intermediate products B and said part of the side products C, preferably at the bottom of distillation column;

b2) distilling said stream Glb obtained in step bl) to form a Glc stream comprising 2,3,3,3-tetrafluoropropene (1234yf), a portion of said portion of the intermediate products B and a portion of said portion byproducts C, advantageously in the distillation column, and a Gld stream comprising a portion of said portion of the intermediate products B and a portion of said portion of C-products, preferably at the bottom of distillation column, preferably Gld stream is recycled in step a).

Preferably, the Glc stream formed in step b2) may include 2,3,3,3-tetrafluoropropene (1234yf), 1,1,1,2,2-pentafluoropropane (245cb) and trans-3,3 , 3-tetrafluoro-1-propene (1234zeE). Preferably, the Gld stream formed in step b2) may include 1,1,1,2,2-pentafluoropropane (245cb), trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE), 2 chloro-3,3,3-trifluoropropene (1233xf). In particular, the content of 1,1,1,2,2-pentafluoropropane (245cb) is greater in the Gld current in the current Ic.

According to a preferred embodiment, the method comprises a step b3), subsequent to step b2), wherein Glc stream obtained in step b2) comprises 2,3,3,3-tetrafluoropropene (1234yf), 1 , 1,1,2,2-pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-1-propene (1234zeE); Glc and said stream is distilled to form a Gle stream comprising 2,3,3,3-tetrafluoropropene (1234yf) and a Gif stream comprising 1,1,1,2,2-pentafluoropropane (245cb) and trans-3, 3,3-tetrafluoro-l-propene (1234zeE). Preferably, the Gle stream comprising 2,3,3,3-tetrafluoropropene (1234yf) can be subjected to further purification steps to obtain a sufficient purity for its commercialization.

According to a preferred embodiment, the Gif stream obtained in step b3) is separated by extractive distillation.

According to a particular embodiment, the Gif stream obtained in step b3) is separated by extractive distillation using the steps:

b4) contacting said stream Gif obtained in step b3) with an organic extraction agent to form a Glg current, and

b5) current Glg extractive distillation to form a stream comprising GLH 1,1,1,2,2- pentafluoropropane (245cb), advantageously in the distillation column, and a stream comprising Gli trans-3,3,3 -tetrafluoro-l-propene (1234zeE) and said organic extractant, preferably at the bottom of distillation column.

Preferably, the Gli stream comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant is separated by distillation to form a glj stream comprising said organic extractant and Glk stream comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE). The current glj comprising said organic extractant may be recycled to the step b4). The current Glk comprising trans-1,3,3,3-tetrafluoro-l-propene (1234zeE) may be either purified or disposed of by incineration.

Preferably, the GLH stream comprising 1,1,1,2,2-pentafluoropropane (245cb), preferably free of trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE), is recycled to the step a).

Alternatively, the method comprises a step b3), subsequent to step b2), wherein Glc stream obtained in step b2) comprises 2,3,3,3-tetrafluoropropene (1234yf), 1,1,1 , 2,2-pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE); Glc and said stream is distilled to form a stream Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb) and Gif stream comprising trans-3 , 3,3-tetrafluoro-l-propene (1234zeE). Said current Glc is distilled by extractive distillation to form said current Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb); and said Gif stream comprising trans-1,3,3,3-tetrafluoro-l-propene (1234zeE). Thus, the current Ic is distilled by extractive distillation according to the steps of:

b4 ') contacting said stream Glc obtained in step b2) with an organic extraction agent to form a stream Glg', and

b5 ') of the extractive distillation stream Glg' to form a stream Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb), preferably at the column top of distillation, and a current GLH 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant, preferably at the bottom of distillation column.

Preferably, the current Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and

1,1,1,2,2-pentafluoropropane (245cb) can be subjected to subsequent purification steps. Thus, 2,3,3,3-tetrafluoropropene (1234yf) can be separated, preferably by distillation 1,1,1,2,2-pentafluoropropane (245cb) to form a stream comprising 2,3,3,3 -tétrafluoropropène (1234yf) and a current Gli 'comprising 1,1,1,2,2-pentafluoropropane (245cb), said current Gli' being recycled to step a). 2,3,3,3-tetrafluoropropene (1234yf) may also be subjected to further purification steps to obtain a sufficient purity for its commercialization.

Preferably, the current GLH 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant is separated by distillation to form a stream glj' comprising said organic extractant and a current Glk 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE). The current glj 'comprising said organic extractant may be recycled to step b4'). The current Glk 'comprising trans-1,3,3,3-tetrafluoro-l-propene (1234zeE) may be either purified or disposed of by incineration.

According to another preferred embodiment, said liquid stream Ll comprises, besides the unreacted HF, or all of the intermediate products B and C or all of the byproducts; and all or part of this stream Ll is carried at low temperature, preferably between -50 ° C and 15 ° C, preferably between -30 ° C to 0 ° C, to form a first phase comprising a portion Lia HF n ' unreacted and a second phase comprising said Llb intermediate products B and C said byproducts; optionally or not, said Gld stream formed in step b2) is mixed with the liquid stream Ll before the latter is brought to low temperatures.

Preferably, said liquid stream Ll comprises part of the intermediate products B and C or all of the byproducts and part of the liquid stream Ll is carried at low temperature, preferably between -50 ° C and 20 ° C, to form a Lia first phase comprising a portion of the HF unreacted Llb and a second phase comprising said intermediate products B and C said byproducts; optionally or not, said Gld stream formed in step b2) is mixed with the liquid stream Ll before the latter is brought to low temperatures.

Preferably, said first phase Lia is recycled to step a).

According to a preferred embodiment, said second phase Llb is distilled to recover a Lie stream comprising 1,1,1,2,2-pentafluoropropane (245cb) and trans-1,3,3,3-tetrafluoro-l-propene ( 1234zeE), advantageously in the distillation column, and a Lld stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf), El-chloro-3,3,3-trifluoro-1-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa); advantageously at the bottom of distillation column, preferably said current Lie is recycled to step a).

According to a preferred embodiment, said Lld stream is separated to form a stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf) and a stream comprising El-chloro-3,3,3-trifluoro -l-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa).

According to a preferred embodiment, the separation of said current Lld is carried out by extractive distillation.

According to a particular embodiment, the extractive distillation of said current Lld comprises the steps of:

- contacting said stream Lld with an organic extraction agent to form a composition Lie, and

- extractive distillation Liga LLF composition to form a stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf), preferably at the column top of

distillation, and a stream comprising LLG El-chloro-3,3,3-trifluoro-l-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa) and said organic extractant, preferably in the bottom of distillation column.

Preferably, the LLG stream is then distilled to form a Llh stream comprising said organic extractant and a stream comprising Lli El-chloro-3,3,3-trifluoro-l-propene (1233zdE) and 1.1 , 1,3,3-pentafluoropropane (245fa). The current Llh may be recycled to be contacted with a Lld stream to form a composition Lie. The current Lli comprising El-chloro-3,3,3-trifluoro-l-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa) can be purified either be destroyed by incineration.

Preferably, the LLF stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf), preferably free of 1,1,1,3,3-pentafluoropropane (245fa) and El-chloro- 3,3,3-trifluoro-1-propene (1233zdE) is recycled to step a).

According to a preferred embodiment, the present invention enables recycling to step a) one or more streams lacking one or more secondary products C.

Brief Description of Drawings

1 schematically shows a device implementing a method for producing 2,3,3,3-tetrafluoro-l-propene according to a particular embodiment of the present invention.

Figures 2 and 3 show schematically a device embodying the purification of 2-3,3,3-tetrafluoro-l-propene according to a particular embodiment of the present invention.

Detailed Description of the Invention

The present invention allows the production and purification of 2,3,3,3-tetrafluoropropene (1234yf). According to a first aspect of the present invention, a method of production and purification of 2,3,3,3-tetrafluoropropene (1234yf) is provided. Said method is implemented from a starting composition comprising at least one compound of the formula CX (Y) 2-CX (Y) m -CH m XY (I) wherein X and Y are independently H, F, or Cl and m = 0 or 1; and / or fluorination in the presence of a catalyst of a compound of formula (CX n Y3- n ) CHpXi pCH- m X 2-m (II) wherein X is independently of each other Cl, F, I or Br; Y is independently of each other H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1 or 2; and p is O or 1.

Preferably, said method comprises the steps of:

a) contacting, in the presence of a catalyst, the starting composition with HF to produce a composition A comprising 2,3,3,3-tetrafluoropropene (1234yf), intermediates B consisting of 2-chloro-3 , 3,3-trifluoropropene (1233xf), 1, 1, 1,2,2-pentafluoropropane (245cb) and by-products consisting of C l-chloro-3,3,3-trifluoro-l-propene (1233zd) , 1,3,3,3-tetrafluoro-l- propene (1234ze) and 1, 1, 1,3,3-pentafluoropropane (245fa);

b) recovering said composition A and purification thereof to form and recover a first stream comprising 2,3,3,3-tetrafluoropropene (1234yf) and one or more stream comprising 2-chloro-3,3,3-trifluoropropene (1233xf) and / or

1, 1,1,2,2-pentafluoropropane (245cb) ;

c) recycling to step a) said one or more stream comprising 2-chloro-3,3,3-trifluoropropene (1233xf) and / or 1, 1,1,2,2-pentafluoropropane (245cb).

Preferably, the content of at least one of C-products in said one or more streams recycled to step a) may be less than the latter in said composition A.

The content of any secondary products C can be reduced in one or more or all of said one or more streams recycled to step a). Preferably, said content of at least one of C-products in said one or more streams recycled to step a) may be reduced by 20%, 30%, 40%, 50%, 60%, 70%, 80% , 90%, 95% or 98% with respect to said content of the same at least one of C-products in said composition A. Thus, the content of Al-chloro-3,3,3-trifluoro-l-propene (1233zdE ) into said one or more streams recycled to step a) may be reduced by 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98% compared with the content of Al-chloro-3,3,3-trifluoro-l-propene (1233zdE) in said composition A. in another embodiment, the content of trans-l, 3,3,3-tetrafluoro-l- propene (1234zeE) in said one or more streams recycled to step a) may be reduced by 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98% with respect to the content of trans-1,3,3,3-tetrafluoro-l-propene (1234zeE) in said composition A. in another embodiment, the content of 1, 1, 1.3 , 3-pentafluoropropane (245fa) in said one or more streams recycled to step a) may be reduced by 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98% compared with the content of 1, 1,1,3,3-pentafluoropropane (245fa) in said composition A. the contents are expressed by weight.

Said one or more streams recycled to step a) may be devoid of one or more by-products C. The term "free" means that the considered stream comprising less than 50 ppm, preferably less than 20 ppm, preferably less 10 ppm of the compound in question based on the total weight of said stream.

According to a preferred embodiment, the composition A further comprises HCl, a portion of HF. Preferably, purifying said composition A performed in step b) comprises distillation of said composition A for recovering distillation column head a Gl gaseous stream comprising HCl and 2,3,3,3-tetrafluoropropene (1234yf) ; and at the bottom of distillation column a liquid stream Ll comprising said part HF. Or all of the intermediate products B and C or all of the byproducts may be present in said gas stream Gl and / or in said liquid stream Ll.

Preferably, all or part of 1,1,1,2,2-pentafluoropropane (245cb) may be contained in said gas stream Gl. All or part of 1,1,1,2,2-pentafluoropropane (245cb) may also be contained in said liquid stream Ll.

Preferably, all or part of the trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) may be contained in said gas stream Gl. All or part of the trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) may also be contained in said liquid stream Ll.

Preferably, all or part of 2-chloro-3,3,3-trifluoropropene (1233xf) may be contained in said gas stream Gl. All or part of 2-chloro-3,3,3-trifluoropropene (1233xf) may also be contained in said liquid stream Ll. Privileged manner, 2-chloro-3,3,3-trifluoropropene (1233xf) is contained in said liquid stream Ll, preferably 70%, 75%, 80%, 85% or 90% of 2-chloro-3,3 , 3-trifluoropropene (1233xf) is contained in said liquid stream Ll relative to said Gl gas stream.

Preferably, all or part of the El-chloro-3,3,3-trifluoro-l-propene (1233zdE) may be contained in said gas stream Gl. All or part of the El-chloro-3,3,3-trifluoro-l-propene (1233zdE) may also be contained in said liquid stream Ll. Privileged manner, the El-chloro-3,3,3-trifluoro-l-propene (1233zdE) is contained in said liquid stream Ll, preferably 70%, 75%, 80%, 85%, 90% or 95% of l-chloro-3,3,3-trifluoro-l-propene (1233zd) is contained in said liquid stream Ll relative to said Gl gas stream.

Preferably, all or part of 1,1,1,3,3-pentafluoropropane (245fa) may be contained in said gas stream Gl. All or part of 1,1,1,3,3-pentafluoropropane (245fa) can also be contained in said liquid stream Ll. Privileged manner, 1,1,1,3,3-pentafluoropropane (245fa) is contained in said liquid stream Ll, preferably 70%, 75%, 80%, 85%, 90% or 95% 1,1, 1,3,3-pentafluoropropane (245fa) is contained in said liquid stream Ll relative to said Gl gas stream.

According to a preferred embodiment, said Gl gas stream comprises a portion of the intermediate products B and part of the C-products Gl and said gas stream is purified by the steps of:

bl) distillation Gl gas stream to recover a Gla stream comprising HCl, advantageously in the distillation column, and a Glb stream comprising 2,3,3,3-tetrafluoropropene (1234yf), said part of the intermediate products B and said part of the side products C, preferably at the bottom of distillation column;

b2) distilling said stream Glb obtained in step bl) to form a Glc stream comprising 2,3,3,3-tetrafluoropropene (1234yf), a portion of said portion of the intermediate products B and a portion of said portion byproducts C, advantageously in the distillation column, and a Gld stream comprising a portion of said portion of the intermediate products B and a portion of said portion of C-products, preferably at the bottom of distillation column.

Preferably, the Glc stream formed in step b2) may include 2,3,3,3-tetrafluoropropene (1234yf), 1, 1, 1,2,2-pentafluoropropane (245cb) and 1,3,3,3 -tetrafluoro-l-propene (1234ze). Preferably, the Gld stream formed in step b2) can comprise 1, 1,1,2,2-pentafluoropropane (245cb), trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE), 2 chloro-3,3,3-trifluoropropene (1233xf) and optionally or non-El-chloro-3,3,3-trifluoro-l-propene (1233zdE) and 1, 1, 1,3,3-pentafluoropropane (245fa) . In particular, the content of 1, 1,1,2,2-pentafluoropropane (245cb) is greater in the Gld current in the current Ic. The current Gld may contain 55%, 60%, 65%, 70%, 75%, 78% or 80% of 1, 1, 1,2,2-pentafluoropropane (245cb) based on the total content of 1, 1 , 1,2,2-pentafluoropropane (245cb) in Gld Glc and current.

Gld the stream can be recycled to step a) of this method. The current Gld may be one of said one or more streams recycled to step a) (step c) of the present process.

Thus, the present method may be a method of production and purification of 2,3,3,3-tetrafluoropropene (1234yf) implemented from a starting composition comprising at least one compound of formula (I) CX ( Y) 2 CX (Y) m -CH m XY where X and Y independently represent a hydrogen, fluorine or chlorine and m = 0 or 1; and / or fluorination in the presence of a catalyst of a compound of formula (CXnY3-n) CHpXi pCH- m X 2-m (II) wherein X is independently of each other Cl, F, I or Br; Y is independently of each other H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1 or 2; and p is 0 or 1; said method comprising the steps of:

a) contacting, in the presence of a catalyst, the starting composition with HF to produce a composition A comprising HCl, a portion of unreacted HF, 2,3,3,3-tetrafluoropropene (1234yf) , intermediates B consisting of 2-chloro-3,3,3-trifluoropropene (1233xf), 1,1,1,2,2-pentafluoropropane (245cb) and C-products consisting of El-chloro-3, 3,3-trifluoro-l-propene (1233zdE), trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and 1,1,1,3,3-pentafluoropropane (245fa);

b) recovering said composition A and distillation thereof to form and recovering the distillation column head a Gl gaseous stream comprising HCl and 2,3,3,3-tetrafluoropropene (1234yf), a portion of the intermediate products B and a portion of the C-products; and at the bottom of distillation column a liquid stream Ll comprising said part of the unreacted HF, part of the intermediate products B and part of the C-products; Gl said gas stream being purified by the following steps:

bl) distillation Gl gas stream to recover a Gla stream comprising HCl and a Glb stream comprising 2,3,3,3-tetrafluoropropene (1234yf), said part of the intermediate products B and C of said part-products;

b2) distilling said stream Glb obtained in step bl) to form a Glc stream comprising 2,3,3,3-tetrafluoropropene (1234yf), a portion of said portion of the intermediate products B and a portion of said portion byproducts C and a Gld stream comprising a portion of said portion of the intermediate products B and a portion of said portion of C-products,

c) recycling to step a) of the current Gld,

preferably, the content of at least one of C-products in the Gld current being less than the latter in said composition A.

According to a preferred embodiment, the method comprises a step b3), subsequent to step b2), wherein Glc stream obtained in step b2) comprises 2,3,3,3-tetrafluoropropene (1234yf), 1 , 1,1,2,2-pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-1-propene (1234zeE); Glc and said stream is distilled to form a stream comprising Gle

2,3,3,3-tetrafluoropropene (1234yf) and a Gif stream comprising 1, 1,1,2,2-pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) .

The current Gif obtained in step b3) may be separated by extractive distillation.

According to a particular embodiment, the Gif stream obtained in step b3) is separated by extractive distillation using the steps:

b4) contacting said stream Gif obtained in step b3) with an organic extraction agent to form a Glg current, and

b5) current Glg extractive distillation to form a GLH stream comprising 1, 1, 1,2,2-pentafluoropropane (245cb), advantageously in the distillation column, and a Gli composition comprising trans-l, 3,3,3 -tetrafluoro-l-propene (1234zeE) and said organic extractant, preferably at the bottom of distillation column. Preferably, the Gli stream comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant is separated by distillation to form a glj stream comprising said organic extractant and Glk stream comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE). The current glj comprising said organic extractant may be recycled to the step b4). The current Glk comprising trans-1,3,3,3-tetrafluoro-l-propene (1234zeE) may be either purified or disposed of by incineration.

According to a preferred embodiment, said organic extractant is a solvent selected from the group consisting hydrohalocarbure, alcohol, ketone, amine, ester, ether, aldehyde, nitrile, carbonate, thioalkyl, amide, heterocycle. Advantageously, the said organic extractant is a solvent selected from the group consisting of alcohol, ketone, amine, ester and heterocycle. According to a preferred embodiment, said organic extractant has a boiling point between 10 and 150 ° C.

Preferably, said extracting agent can have a separation factor If two greater than or equal to 1.1, said separation factor is calculated by the formula Si, 2 = (yi, s * PI) / (y2, s * P2) wherein

yi, s represents the coefficient of activity of 1,1,1,2,2-pentafluoropropane in said organic extractant at infinite dilution,

IP is the saturated vapor pressure of 1,1, 1,2,2-pentafluoropropane,

Y2, s is the activity coefficient of said trans-l, 3,3,3-tetrafluoro-l-propene

(1234zeE) in said organic extractant at infinite dilution,

P2 represents the saturation vapor pressure of said trans-l, 3,3,3-tetrafluoro-l-propene

(1234zeE) ;

preferably, the separation factor is greater than or equal to 1.2, preferably greater than or equal to 1.4, more preferably greater than or equal to 1.6, in particular greater than or equal to 1.8, greater than or equal 2.0.

The saturated vapor pressure is considered to a temperature of 25 ° C.

Preferably, said organic extractant may have a separation efficiency

C2, s greater than or equal to 0.20, said separation capacity is calculated by the formula C2, s = l / (Y2, s) wherein y2, s is the activity coefficient of said trans-3,3 , 3-tetrafluoro-l-propene (1234zeE) in said organic extractant at infinite dilution;

advantageously C2 separation capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.60, more preferably greater than or equal to 0.80, in particular greater than or equal to 1.0.

Preferably, said organic extractant may have a separation factor If two greater than or equal to 1.5 and a C2 absorbency, s greater than or equal to 0.6 and being selected from the group consisting of ethylamine , acetaldehyde, isopropylamine, methyl formate, diethyl ether, 1,2-epoxypropane, ethylmethylamine, dimethoxymethane, 2-amino-2-methylpropane, methylcyclopropylether, n-propylamine, isopropylmethylamine, 2-ethoxy-propane, methyl-t-butylether, diethylamine, propanone , methylacetate, 4-methoxy-2-methyl-2-butanethiol, 2-butanamine, n-methylpropylamine, isobutanal, tetrahydrofuran, isopropylformate, diisopropyl ether, 2-ethoxy-2-methyl-propane, 1-butylamine, ethylacetate, butanone, n -propylformate, 2-ethoxy-butane, l-methoxy-2-methyl-butane, 2,2-dimethoxypropane, l-ethoxy-2-methylpropane, diisopropylamine, 1,2-dimethoxyethane, 3-methyl-2-butanamine, diethoxymethane , isopropylacetate, di-n-propyl ether, 3-pentylamine, n-methylbutylamine, 1-ethoxybuta not, l-methoxy-2-propanamine, 2-methylbutanal, 2-methoxyethanamine, tert-butyl acetate, propionitrile, 2-allyloxyethanol, 1-methoxy-pentane, ethylpropionate, 1,2-dimethoxypropane, dioxane, 3-pentanone, 1, 1-diethoxyethane, 2-pentanone, 2-methoxy-lpropanamine, trimethoxymethane, n-pentylamine, 3,3-dimethyl-2-butanone, 1,3-dioxane, piperidine, dipropylamine, 2-ethoxyethanamine, sec-butyl acetate, n- methyl-l, 2-ethanediamine, 2,2-diethoxypropane, pyridine, 4-methyl-2-pentanone, 1,2-diaminoethane, butyronitrile, sec-butyl tert-butyl ether, l-methoxy-2-propanol, 1,2- propanediamine, 2,6-dimethyl-5-heptenal, l- (dimethylamino) -2-propanol, 3-methyl-3-pentanol, 1,1-diethoxypropane, 2-ethylbutylamine, diethyl carbonate, n-butylacetate, 2-hexanone, n-ethylethylenediamine, 5-hexen-2-one, 2-methylpyridine, 2-methoxyl-propanol, hexanal, l-ethoxy-2-propanol, 4-methyl-2-hexanamine, hexylamine, methoxycyclohexane, 2-

(Dimethylamino) ethanol, cyclohexylamine, n-ethyl-2-dimethylaminoethylamine, ethoxyethanol, 2-methylpyrazine, 2-ethoxy-l-propanol, 1-methylpiperazine, 1,3-propanediamine, di-n-butylether, valeronitrile, 2- heptanamine, 1-ethoxy-hexane, n, n-diethylethylenediamine, 2,6-dimethylpyridine, 4-methyl-2-hexanone, 1,1,1-triethoxyethane, 1-methoxy-2-acetoxypropane, 4-methylpyridine, n, n'-diethyl-l, 2-ethanediamine, 2,6-dimethylmorpholine, methylhexanoate, 2-Propoxyethanol, l-propoxy-2-propanol. Advantageously, said organic extractant may have a separation factor If two greater than or equal to 1.8 and / or a C2 absorbency, s greater than or equal to 0.8; and being selected from the group consisting of ethylamine, isopropylamine, ethylmethylamine, 2-amino-2-methylpropane, n-propylamine, isopropylmethylamine, diethylamine, propanone, 2-butanamine, n-methylpropylamine, tetrahydrofuran, 1-butylamine, ethylacetate, butanone, 1,2-dimethoxyethane, 3-methyl-2-butanamine, 3-pentylamine, n-methylbutylamine, 1-methoxy-2-propanamine, 2-methoxyethanamine, ethylpropionate, dioxane, 3-pentanone, 2-pentanone, 2-methoxy- lpropanamine, trimethoxymethane, n-pentylamine, 3,3-dimethyl-2-butanone, 1,3-dioxane, piperidine, 2-ethoxyethanamine, n-methyl-l, 2-ethanediamine, 1,2-diaminoethane, butyronitrile, l- methoxy-2-propanol, 1,2-propanediamine, l- (dimethylamino) -2-propanol, 2-ethylbutylamine, diethyl carbonate, n-butylacetate, 2-hexanone, n-ethylethylenediamine, 2-methoxyl-propanol, 1-ethoxy 2- propanol, 4-methyl-2-hexanamine, hexylamine, methoxycyclohexane, 2- (dimethylamino) ethanol, cyclohexylamine, n-ethyl-2-dimethylaminoethylamine, 2-ethoxy-l-propano l, 1-methylpiperazine, 1,3-propanediamine, valeronitrile, 2-heptanamine, η, η-diethylethylenediamine, 4-methyl-2-hexanone, l-methoxy-2-acetoxypropane, 4-methylpyridine, N, N'-diethyl -l, 2-ethanediamine, 2,6-dimethylmorpholine, methylhexanoate, 2-Propoxyethanol, l-propoxy-2-propanol. Preferably, said organic extractant may have a separation factor If two greater than or equal to 1.9 and / or a C2 absorbency, s greater than or equal to 0.9 and being selected from the group consisting as ethylamine, isopropylamine, ethylmethylamine, 2-amino-2-methylpropane, n-propylamine, isopropylmethylamine, diethylamine, propanone, 2-butanamine, n-methylpropylamine, tetrahydrofuran, 1-butylamine, ethylacetate, butanone, 1,2-dimethoxyethane, 3 -methyl-2-butanamine, 3-pentylamine, n-methylbutylamine, l-methoxy-2-propanamine, 2-methoxyethanamine, ethylpropionate, dioxane, 3-pentanone, 2-pentanone, 2-methoxy-lpropanamine, n-pentylamine, 3 , 3-dimethyl-2-butanone, 1,3-dioxane, piperidine, 2-ethoxyethanamine, n-methyl-l, 2-ethanediamine, 1,2-diaminoethane, 1,2-propanediamine, 1- (dimethylamino) -2 propanol, 2-ethylbutylamine, n-butylacetate, 2-hexanone, n-

ethylethylenediamine, l-ethoxy-2-propanol, 4-methyl-2-hexanamine, hexylamine, 2-(dimethylamino)-ethanol, cyclohexylamine, n-ethyl-2-dimethylaminoethylamine, 2-ethoxy-l-propanol, 1-methylpiperazine, 1,3-propanediamine, 2-heptanamine, n,n-diethylethylenediamine, l-methoxy-2-acetoxypropane, 4-methylpyridine, n,n'-diethyl-l,2-ethanediamine, 2,6-dimethylmorpholine, methylhexanoate, l-propoxy-2-propanol. Plus particulièrement, ledit agent d'extraction organique est choisi parmi le groupe consistant en éthylamine, isopropylamine, n-propylamine, diethylamine, propanone, tetrahydrofurane, ethylacetate, butanone, 3-pentylamine, 2-methoxyethanamine, dioxane, 3-pentanone, 2-pentanone, n-pentylamine, 1,3-dioxane, 1,2-diaminoethane, 1,2-propanediamine, 2-methoxyethanol, n-butylacetate, l-ethoxy-2-propanol.

GLH said stream comprising 1, 1, 1,2,2-pentafluoropropane (245cb) can be recycled to step a) of this method. GLH said stream comprising 1, 1,1,2,2-pentafluoropropane (245cb) may be one of said one or more streams recycled to step a) of the present process (step c)).

As explained above, the Gli stream comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant is distilled to separate the organic extractant of the trans-l , 3,3,3-tetrafluoro-l-propene (1234zeE), preferably said organic extractant thus separated is recycled to the step b4). The trans-1,3,3,3-tetrafluoro-l-propene (1234zeE) can be incinerated or purified for further use or to be sold.

The current Gle can be purified, for example by extractive distillation to remove the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) may be present. In this case, said organic extractant is a solvent selected from the group consisting of hydrocarbon, hydrohalocarbure, alcohol, ketone, amine, ester, ether, aldehyde, nitrile, carbonate, thioalkyl, amide and heterocycle; or said organic extractant is difluorodiethylsilane, triethylfiuorosilane or perfluorobutanoic acid; preferably from the group consisting of amino, ether, ketone, ester, alcohol, aldehyde, heterocyclic ring. The boiling point of said organic extractant may be between 10 and 150 ° C. Said organic extractant may have a separation factor If two greater than or equal to 1.1, said separation factor is calculated by the formula Si, 2 = (yi, s * PI) / (y2, s * P2 ) wherein yi, s is the activity coefficient of 2,3,3,3-tetrafluoro-l-propene in said organic extractant at infinite dilution, PI represents the saturation vapor pressure of 2,3,3 , 3-tetrafluoro-l-propene, y2, s is the activity coefficient of the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E), in said organic extractant at infinite dilution , P2 represents the saturation vapor pressure of said

at least one of the compounds consisting of trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); preferably, the separation factor is greater than or equal to 1.2, preferably greater than or equal to 1.4, more preferably greater than or equal to 1.6, in particular greater than or equal to 1.8, greater than or equal 2.0. Said organic extractant may have an absorption capacity C2, s greater than or equal to 0.20, said absorptive capacity is calculated by the formula C2, s = l / (y2, s) wherein y2, s is the activity coefficient of trans-1,3,3,3-tetrafluoro-l-propene (1234ze-E) in said organic extractant at infinite dilution; advantageously C2 absorption capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.60, more preferably greater than or equal to 0.80, in particular greater than or equal to 1.0. Advantageously, said organic extractant may be ethylamine, isopropylamine, diethyl ether, ethoxy-ethene, dimethoxymethane, n-propylamine, methyl-t-butylether, diethylamine, propanone, methylacetate, isobutanal, tetrahydrofuran, isopropylformate, diisopropyl ether, 2-ethoxy 2-methyl-propane, ethylacetate, butanone, diethoxymethane, isopropylacetate, 3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane, 3-pentanone, 1,1-diethoxyethane, 2-pentanone, trimethoxymethane, n-pentylamine, 1, 3-dioxane, 3,3-dimethyl-2-butanone, sec-butyl acetate, 4-methyl-2-pentanone, 1,2-diaminoethane, l-methoxy-2-propanol, diethyl carbonate, n-butyl acetate, l-ethoxy-2- propanol, hexanal; preferably said organic extractant is selected from the group consisting of ethylamine, isopropylamine, diethyl ether, dimethoxymethane, n-propylamine, diethylamine,, diisopropyl ether, 2-ethoxy-2-methyl-propane, butanone, diethoxymethane, isopropylacetate, 3- pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate, 1,2-diaminoethane, l-methoxy-2-propanol, n-butyl acetate, 1-ethoxy-2- propanol, hexanal; preferably said organic extractant is selected from the group consisting of ethylamine, isopropylamine, diethyl ether, dimethoxymethane, n-propylamine, diethylamine, diisopropyl ether, 2-ethoxy-2-methyl-propane, diethoxymethane, isopropylacetate, 3-pentylamine, 2 -methoxyethanamine, tert-butyl acetate, dioxane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate, 1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate, l-ethoxy-2-propanol, hexanal .

Alternatively, as mentioned above, the method comprises a step b3), subsequent to step b2), wherein Glc stream obtained in step b2) comprises 2,3,3,3-tetrafluoropropene (1234yf) , 1,1,1,2,2-pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-1-propene (1234zeE); Glc and said stream is distilled to form a stream Gle 'comprising

2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb) and Gif stream comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) . Thus, the current Ic can be distilled by extractive distillation according to the steps of:

b4 ') contacting said stream Glc obtained in step b2) with an organic extraction agent to form a stream Glg', and

b5 ') of the extractive distillation stream Glg' to form the flow Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb), preferably at the column top of distillation, and the current GLH 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant, preferably at the bottom of distillation column.

According to a preferred embodiment, said organic extractant may have a separation factor If two greater than or equal to 1.1, said separation factor is calculated by the formula Si, 2 = (yi, s * PI) / (y2, s * P2) wherein yi, s represents the coefficient of activity of 2,3,3,3-tetrafluoro-l-propene in said organic extractant at infinite dilution, PI represents the vapor pressure saturating 2,3,3,3-tetrafluoro-l-propene, y2, s represents the coefficient of activity of the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) in said agent organic extraction at infinite dilution, P2 represents the saturation vapor pressure of the trans-1,3,3,3-tetrafluoro-l-propene (1234ze-E); preferably, the separation factor is greater than or equal to 1.2, preferably greater than or equal to 1.4, more preferably greater than or equal to 1.6, in particular greater than or equal to 1.8. In this embodiment, said organic extractant may also have a separation factor If two greater than or equal to 1.1, said separation factor is calculated by the formula Si, 2 = (yi, s * PI) / (y2, s * P2) wherein yi, s is the activity coefficient of 1,1,1,2,2-pentafluoropropane (245cb) in said organic extractant at infinite dilution, PI is the pressure saturated vapor 1,1,1,2,2-pentafluoropropane (245cb), y2, s is the activity coefficient of trans-1,3,3,3-tetrafluoro-l-propene (1234ze-E) in said organic extractant at infinite dilution, P2 represents the saturation vapor pressure of the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); preferably, the separation factor is greater than or equal to 1.2, preferably greater than or equal to 1.4, more preferably greater than or equal to 1.6, in particular greater than or equal to 1.8, greater than or equal 2.0. In this preferred embodiment, said organic extractant can have an absorbent capacity C2, s greater than or equal to 0.20, said absorptive capacity is calculated by the formula C2, s = l / (y2, s) wherein y2, s represents the coefficient of activity of said at least one of the compounds consisting of trans-1,3,3,3-tetrafluoro-l-propene (1234ze-E) in said organic extractant in dilution infinite, preferably y2, s represents the coefficient of activity of said at least one of the compounds consisting of trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E), in said organic extractant in infinite dilution; advantageously C2 absorption capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.60, more preferably greater than or equal to 0.80, in particular greater than or equal to 1.0. Thus, in this preferred embodiment, said organic extractant may be ethylamine, isopropylamine, diethyl ether, ethylmethylamine, 2-amino-2-methylpropane, n-propylamine, isopropylmethylamine, 2-ethoxy-propane, methyl-t-butylether , diethylamine, propanone, methyl acetate, 2-butanamine, n-methylpropylamine, isobutanal, tetrahydrofuran, 1-butylamine, ethylacetate, butanone, n-propylformate, 2,2-dimethoxypropane, l-ethoxy-2-methylpropane, 1,2-dimethoxyethane , 3-methyl-2-butanamine, diethoxymethane, isopropylacetate, 3-pentylamine, n-methylbutylamine, 1-ethoxybutane, l-methoxy-2-propanamine, 2-methylbutanal, 2-methoxyethanamine, tert-butyl acetate, 1-methoxy-pentane , ethylpropionate, 1,2-dimethoxypropane, dioxane, 3-pentanone, 1,1-diethoxyethane, 2-pentanone, 2-methoxy-lpropanamine, trimethoxymethane, n-pentylamine, 3,3-dimethyl-2-butanone, 1.3 -dioxane, piperidine, 2-ethoxyethanamine, sec-butyl acetate, n-methyl-l, 2-ethanediamine, 2,2-diethoxypropane, 4-methyl-2-penta none, 1,2-diaminoethane, butyronitrile, l-methoxy-2-propanol, 1,2-propanediamine, 2,6-dimethyl-5-heptenal, l- (dimethylamino) -2-propanol, 1,1-diethoxypropane, 2- ethylbutylamine, diethyl carbonate, n-butylacetate, 2-hexanone, n-ethylethylenediamine, 5-hexen-2-one, 2-methylpyridine, 2-methoxyl-propanol, hexanal; preferably, ethylamine, isopropylamine, diethyl ether, n-propylamine, diethylamine, propanone, methyl acetate, butanone, diethoxymethane, isopropylacetate, 3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane, 1,1-diethoxyethane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate, 1,2-diaminoethane, l-methoxy-2-propanol, 1,2-propanediamine, n-butylacetate, 2-methoxy-l-propanol, hexanal; preferably, ethylamine, isopropylamine, diethyl ether, n-propylamine, diethylamine, diethoxymethane, isopropylacetate, 3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane, 1,1-diethoxyethane, trimethoxymethane, n-pentylamine, 1,3-dioxane , sec-butyl acetate, 1,2-diaminoethane, l-methoxy-2-propanol, 1,2-propanediamine, n-butylacetate, 2-methoxy-l-propanol, hexanal.

Preferably, the current Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb) can be subjected to subsequent purification steps. Thus, 2,3,3,3-tetrafluoropropene (1234yf) can be separated, preferably by distillation 1,1,1,2,2-pentafluoropropane (245cb) to form a stream comprising 2,3,3,3 -tétrafluoropropène (1234yf) and a current Gli 'comprising 1,1,1,2,2-pentafluoropropane (245cb), said current Gli' being recycled to step a). 2,3,3,3-tetrafluoropropene (1234yf) may also be subjected to further purification steps to obtain a sufficient purity for its commercialization. For example, it may be purified, for example by extractive distillation to remove the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) may be present.

Preferably, the current GLH 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant is separated by distillation to form a stream glj' comprising said organic extractant and a current Glk 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE). The current glj 'comprising said organic extractant may be recycled to step b4'). The current Glk 'comprising trans-1,3,3,3-tetrafluoro-l-propene (1234zeE) may be either purified or disposed of by incineration.

If the gas stream comprises Gl optionally after distillation of the HF, the latter may be contained in said Glb current and Glc. Thus, prior to the step b3), the unreacted HF contained in the current Ic can be removed from said current Glc. Removal of THF can be carried out by a series of absorption thereof in an aqueous medium phase. The current Ic may then be neutralized in the presence of a base, e.g. an alkali metal hydroxide or alkaline earth metal, then dried, for example over a molecular sieve to remove possibly traces of water. Optionally or not, if the Glc stream comprises impurities having a lower boiling point than that of 2,3,3,3-tetrafluoro-l-propene, these can be removed by distillation. Said impurities having a lower boiling point than that of 2,3,3,3-tetrafluoro-l-propene may be trifluoromethane (F23), monofluoromethane (F41), difluoromethane (F32), pentafluoroethane (F125), 1.1 , 1-trifluoroethane (F143a), trifluoropropyne or 1-chloro-pentafluoroethane (F115); and these can be recovered by distillation of column top. The stream recovered at the bottom of distillation column can then be used as described above for the Glc stream in step b) and subsequent steps.

According to another preferred embodiment, said liquid stream Ll comprises all or part of the intermediates B and C or all of the byproducts; and all or part of this stream Ll is carried at low temperature, preferably between -50 ° C and 20 ° C, to form a first phase comprising a portion Lia HF unreacted and a second phase comprising said intermediates Llb B and C. said byproducts Thus, said liquid stream Ll may comprise a portion of the intermediate products B and part of the C-products; and all or part of this stream Ll is carried at low temperature, preferably between -50 ° C and 20 ° C, to form a first phase comprising a portion Lia HF unreacted and a second phase comprising said intermediates Llb B and said second product C. Advantageously, said low temperature is between - 50 ° C and 15 ° C, preferably between -40 ° C and 10 ° C, especially between -30 ° C and 0 ° C. This step can be carried out continuously or discontinuously.

claims.
A process for production and purification of 2,3,3,3-tetrafluoropropene (1234yf) implemented from a starting composition comprising at least one compound of formula (I) CX (Y) 2-CX (Y) m -CH m XY where X and Y independently represent a hydrogen, fluorine or chlorine and m = 0 or 1; and / or fluorination in the presence of a catalyst of a compound of formula (CX n Y 3-n) CHpXi pCH- m X 2-m (II) wherein X is independently of each other Cl, F, I or Br; Y is independently of each other H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1 or 2; and p is 0 or 1; said method comprising the steps of:

a) contacting, in the presence of a catalyst, the starting composition with HF to produce a composition A comprising HCl, a portion of unreacted HF, 2,3,3,3-tetrafluoropropene (1234yf) , intermediates B consisting of 2-chloro-3,3,3-trifluoropropene (1233xf), 1, 1, 1,2,2-pentafluoropropane (245cb) and C-products consisting of El-chloro-3, 3,3-trifluoro-l-propene (1233zdE), trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and 1, 1, 1,3,3-pentafluoropropane (245fa);

b) recovering said composition A and purification, preferably distillation thereof to form and recover a first stream, preferably a gas comprising HCl, 2,3,3,3-tetrafluoropropene (1234yf), some of the goods intermediate B and part of the C-products; and a current, preferably liquid Ll comprising a portion of the HF unreacted, a portion of the intermediate products B and part of the C-products;

c) purification of said first stream to form a stream comprising a portion of said portion of the intermediate products B and a portion of said portion of C-products and recycling thereof to step a).

A method according to any preceding claim characterized in that said first stream is a gas stream Gl purified by the following steps:

bl) distillation Gl gas stream to recover a Gla stream comprising HCl, advantageously in the distillation column, and a Glb stream comprising 2,3,3,3-tetrafluoropropene (1234yf), said part of the intermediate products B and

said part of the side products C, preferably at the bottom of distillation column;

b2) distilling said stream Glb obtained in step bl) to form a Glc stream comprising 2,3,3,3-tetrafluoropropene (1234yf), a portion of said portion of the intermediate products B and a portion of said portion byproducts C, advantageously in the distillation column, and a Gld stream comprising a portion of said portion of the intermediate products B and a portion of said portion of C-products, preferably at the bottom of distillation column, preferably Gld stream is recycled in step a).

A method according to any one of claims 3, characterized in that the method comprises a step b3), subsequent to step b2), wherein Glc stream obtained in step b2) comprises 2,3,3,3 tetrafluoropropene (1234yf), 1,1,1,2,2- pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE); Glc and said stream is distilled to form a stream comprising 2,3,3,3-tetrafluoropropene Gle (1234yf) and a stream comprising Gif 1,1,1,2,2- pentafluoropropane (245cb) and trans-3, 3,3-tetrafluoro-l-propene (1234zeE).

Method according to the preceding claim characterized in that the Gif stream obtained in step b3) is separated by extractive distillation.

Method according to the preceding claim characterized in that the Gif stream obtained in step b3) is separated by extractive distillation using the steps:

b4) contacting said stream Gif obtained in step b3) with an organic extraction agent to form a Glg current, and

b5) current Glg extractive distillation to form a stream comprising GLH 1,1,1,2,2- pentafluoropropane (245cb), advantageously in the distillation column, and a stream comprising Gli trans-3,3,3 -tetrafluoro-l-propene (1234zeE) and said organic extractant, preferably at the bottom of distillation column.

6. Method according to the preceding claim characterized in that the GLH stream comprising 1,1,1,2,2-pentafluoropropane (245cb), preferably free of trans-1,3,3,3-tetrafluoro-l-propene ( 1234zeE) is recycled to step a).

A method according to any one of claims 1 or 2 characterized in that the method comprises a step b3), subsequent to step b2), wherein Glc stream obtained in step b2) comprises 2,3,3 , 3-tetrafluoropropene (1234yf), 1,1,1,2,2- pentafluoropropane (245cb) and trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE); Glc and said stream is distilled to form a current Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb) and Gif stream comprising trans-3 , 3,3-tetrafluoro-l-propene (1234zeE).

Method according to the preceding claim characterized in that the current Ic is distilled by extractive distillation according to the steps of:

b4 ') contacting said stream Glc obtained in step b2) with an organic extraction agent to form a stream Glg', and

b5 ') of the extractive distillation stream Glg' to form the flow Gle 'comprising 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb), preferably at the column top of distillation, and the current GLH 'comprising trans-l, 3,3,3-tetrafluoro-l-propene (1234zeE) and said organic extractant, preferably at the bottom of distillation column.

9. A method according to any preceding claim characterized in that said liquid stream Ll comprises part of the intermediate products B and C or all of the byproducts and part of the liquid stream Ll is carried at low temperature, preferably between -50 ° C and 20 ° C, to form a first phase comprising a portion Lia HF unreacted Llb and a second phase comprising said intermediate products B and C said byproducts; optionally or not, said Gld stream formed in step b2) is mixed with the liquid stream Ll before the latter is brought to low temperatures.

10. Method according to the preceding claim characterized in that said first phase Lia is recycled to step a).

11. The method of claim 9 or 10 characterized in that said second phase Llb is distilled to recover a Lie stream comprising 1,1,1,2,2-pentafluoropropane (245cb) and trans-3,3,3 tetrafluoro-l-propene (1234zeE), advantageously in the distillation column, and a Lld stream comprising 2-chloro-3,3,3-trifluoro-l-

propene (1233xf), El-chloro-3,3,3-trifluoro-l-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa); advantageously at the bottom of distillation column, preferably said current Lie is recycled to step a).

12. Method according to the preceding claim characterized in that said Lld stream is separated to form a stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf) and a stream comprising El-chloro-3,3 , 3-trifluoro-l-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa).

13. Method according to the preceding claim characterized in that separation of said current Lld is carried out by extractive distillation.

14. Method according to the preceding claim characterized in that the extractive distillation of said current Lld comprises the steps of:

- contacting said stream Lld with an organic extraction agent to form a composition Lie, and

- extractive distillation Liga LLF composition to form a stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf), advantageously in the distillation column, and a stream comprising LLG El-chloro-3 , 3,3-trifluoro-l-propene (1233zdE) and 1,1,1,3,3-pentafluoropropane (245fa) and said organic extractant, preferably at the bottom of distillation column.

15. Method according to the preceding claim characterized in that the LLF stream comprising 2-chloro-3,3,3-trifluoro-l-propene (1233xf), preferably devoid of El-chloro-3,3,3-trifluoro- l-propene (1233zdE) and / or 1,1,1,3,3-pentafluoropropane (245fa) is recycled to step a).