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. These reactions are carried out in gas phase and generate impurities that must be therefore 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 accumulate in the reactor 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 these compositions form azeotropes or azeotrope-like, the distillation are not an efficient process. extractive distillation methods have been described.

Is known from EP 0864554 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 higher boiling point than 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 selected from hydrocarbons, alcohols, chlorocarbons having a boiling point between 10 ° C and 120 ° C. is also known from US2015 / 291490 a method for separating 2,3,3,3-tetrafluoro-1-propene and methyl chloride (40).

As mentioned in WO 98/19982, the selection of the extracting agent can be complex depending on the products to be separated. 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 the production of 2,3,3,3-tetrafluoro-l-propene with improved purity.

According to a first aspect, the present invention provides a method for purifying the

2,3,3,3-tetrafluoro-l-propene (1234yf) from a first composition comprising 2,3,3,3-tetrafluoro-l-propene and chloromethane (40), said method comprising the steps of a) contacting said first composition with at least one organic extractant to form a second composition; b) extractive distillation of said second composition to form: i) a third composition comprising said organic extractant and methyl chloride (40); and

ii) a stream comprising 2,3,3,3-tetrafluoro-l-propene (1234yf), c) recovering and separating said third composition, preferably by distillation, to form a stream comprising said organic extractant and a stream comprising methyl chloride (40); preferably the stream comprising said organic extractant is recycled to step a).

Preferably, the stream comprising 2,3,3,3-tetrafluoro-l-propene formed in step b) is recovered. This current can possibly be purified to a purity suitable for specific business requirements.

According to a preferred embodiment, said first composition, said second composition and said third composition also include trans-1,3,3,3-tetrafluoro-l-propene (1234ze-E); step c) being the recovery and separation of said third composition, preferably by distillation, to form firstly a stream comprising said organic extractant and also a stream comprising methyl chloride (40) and trans -l, 3,3,3-tetrafluoro-l-propene (1234ze-E).

According to a preferred embodiment, said organic extractant is a solvent selected from the group consisting of hydrocarbons, hydrohalocarbure, alcohol, ketone, amine, ester, ether, aldehyde, nitrile, carbonate, thioalkyl, amide and heterocycle; or the organic extractant is difluorodiethylsilane or triethylfiuorosilane; preferably from the group consisting of ketone, amine, ester, ether, alcohol, and heterocycle aldehyde.

According to a preferred embodiment, said organic extractant may have a boiling point between 10 and 150 ° C.

According to a preferred embodiment, said organic extractant has 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,

IP is the saturation vapor pressure of 2,3,3,3-tetrafluoro-l-propene,

Y2, s represents the coefficient of activity of chloromethane (40) in said organic extractant at infinite dilution,

P2 represents the saturation vapor pressure of methyl chloride (40);

advantageously 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 to 2.0.

According to a preferred embodiment, said organic extractant has 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 chloromethane (40); advantageously C2 absorption capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.50, more preferably greater than or equal to 0.60, in particular greater than or equal to 0.70, more particularly greater than or equal to 0.80.

According to a preferred embodiment, said organic extractant may be selected so as to also have a separation factor and a particular absorption capacity vis-à-vis the trans-l, 3,3,3-tetrafluoro- l-propene (1234ze-E). This may allow to promote the separation of 2,3,3,3-tetrafluoro-l-propene (1234yf) and trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) if the is present in said first composition to be purified. Thus, said organic extractant has 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,

IP is 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 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;

and preferably said organic extractant has 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 the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); advantageously C2 absorption capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.50, more preferably greater than or equal to 0.60, in particular greater than or equal to 0.70, more particularly greater than or equal to 0.80.

According to a preferred embodiment, said first composition is an azeotropic composition or quasi-azeotropic comprising 2,3,3,3-tetrafluoro-l-propene, methyl chloride (40) and trans-l, 3,3,3-tetrafluoro- l-propene (1234ze-E).

Selon un mode de réalisation préféré, ledit agent d'extraction organique est choisi parmi le groupe consistant methylformate, -methoxy-l-propene, ethoxy-ethene, propanone, methylacetate, isobutanal, isopropylformate, ethylacetate, butanone, n-propylformate, 1,2-dimethoxyethane, isopropylacetate, l-methoxy-2-propanamine, 2-methoxyethanamine, 2-methylbutanal, tert-butylacetate, ethylpropionate, dioxane, 3-pentanone, 2-pentanone, 2-methoxy-lpropanamine, trimethoxymethane, 1,3-dioxane, 3,3-dimethyl-2-butanone, 2-ethoxyethanamine, sec-butylacetate, n-methyl-l,2-ethanediamine, 4-methyl-2-pentanone, 1,2-diaminoethane, butyronitrile, l-methoxy2-propanol, 1,2-propanediamine, 2,6-dimethyl-5-heptenal, l-(dimethylamino)-2-propanol, diethylcarbonate, n-butylacetate, 2-hexanone, n-ethylethylenediamine, 5-hexen-2-one, 2-methylpyridine, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal, 2-(dimethylamino)-ethanol, 2-methylpyrazine, 2-ethoxy-l-propanol, 1,3-propanediamine, valeronitrile, 2,6-dimethylpyridine, 4-methyl-2-hexanone, l-methoxy-2-acetoxypropane, 4-methylpyridine, 2,6-dimethylmorpholine, methylhexanoate, 2-propoxyethanol, l-propoxy-2-propanol ; avantageusement methylformate, ethoxy-ethene, propanone, methylacetate, isobutanal, isopropylformate, ethylacetate, butanone, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 3-pentanone, 2-pentanone, 1,3-dioxane, 3,3-dimethyl-2-butanone, sec-butylacetate, 4-methyl-2-pentanone, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, diethylcarbonate, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; de préférence methylformate, propanone, butanone, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec-butylacetate, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; en particulier methylformate, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec-butylacetate, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal.

According to a preferred embodiment, the stream comprising 2,3,3,3-tetrafluoro-l-propene formed in step b) is recovered and is devoid of chloromethane (40). The term

"Free" means that the stream comprising 2,3,3,3-tetrafluoro-l-propene comprises less than 50 ppm, preferably less than 20 ppm, preferably less than 10 ppm of the compound in question based on the total weight of the stream .

According to a preferred embodiment, the method may also comprise prior to step a) the steps of:

i ') implementation or providing a composition comprising 2,3,3,3-tetrafluoro-l- propene, impurities having a lower boiling point than the boiling point of 2,3,3,3 tetrafluoro-l-propene, methyl chloride (40) and optionally the heavy impurities and / or trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); Any implementation or providing a composition comprising 2,3,3,3-tetrafluoro-l-propene, impurities having a lower boiling point than the boiling point of 2,3,3,3-tetrafluoro -l-propene, chloromethane (40), trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) and optionally the heavy impurities;

ii ') distillation of said composition of step i) to remove the top of column impurities having a boiling point below the boiling point of tetrafluoro-l-propene and 2,3,3,3 form a first stream comprising 2,3,3,3-tetrafluoro-l- propene, chloromethane (40), and optionally or not heavy impurities and / or trans-l, 3,3,3-tetrafluoro-l-propene (1234ze- E), recovered at the bottom of distillation column; Any distillation of said composition of step i) to remove the top of column impurities having a boiling point below the boiling point of 2,3,3,3-tetrafluoro-l-propene and forming a first stream comprising 2,3,3,3-tetrafluoro-l-propene, chloromethane (40), trans-l, 3,3,3-tetrafluoro-l- propene (1234ze-E) and optionally or not heavy impurities recovered at the bottom of distillation column;

iii ') optionally or not, distilling said first stream recovered at the bottom of distillation column in step ii') to retrieve the column head a second stream comprising 2,3,3,3-tetrafluoro-l-propene, chloromethane (40) and optionally or not trans-3,3,3-tetrafluoro-l-propene (1234ze-E); and at the bottom of distillation column a stream comprising the heavy impurities; preferably the second stream comprises 2,3,3,3-tetrafluoro-l-propene, methyl chloride (40) and trans- 1,3,3,3-tetrafluoro-l-propene (1234ze-E);

said first stream recovered in step ii ') or said second stream recovered in step iii') corresponds to said first composition used in step a).

According to a second aspect of the present invention, a method of production and purification of 2,3,3,3-tetrafluoro-l-propene is provided. Said method comprises the steps of:

A) fluorination in the presence of a catalyst a 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 Y 3-n) CH p Xi- 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;

B) recovering a stream comprising 2,3,3,3-tetrafluoro-l-propene, methyl chloride (40) and optionally or not trans-3,3,3-tetrafluoro-l-propene (1234ze-E );

C) implementation of the purification process of the 2,3,3,3-tetrafluoro-l-propene according to the present invention from the stream recovered in step B).

According to a third aspect, the present invention provides a composition comprising 2,3,3,3-tetrafluoropropene, an organic extraction agent, methyl chloride (40) and trans-1,3,3,3-tetrafluoro-l-propene (1234ze-E); said organic extractant having a separation factor If 2 greater than 1.6, 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-tetrafluoropropene in said organic extractant at infinite dilution, PI represents the saturation vapor pressure of 2,3,3,3-tetrafluoropropene, y2, s represents the coefficient of activity of chloromethane (40) in said organic extractant at infinite dilution, P2 represents the saturation vapor pressure of methyl chloride (40); and preferably said organic extractant has a capacity of absorption C2, s greater than 0.8, said absorptive capacity is calculated by the formula C2, s = l / (y2, s) wherein y2, s is the activity coefficient of methyl chloride (40) in said organic extractant at infinite dilution; and a separation factor If 2 greater than 1.6, said separation factor is calculated by the formula Si, 2 = (yi, s * PI) / (y2, s * P2) wherein yi, s represents the coefficient of 2,3,3,3-tetrafluoropropene activity in said organic extractant at infinite dilution, PI represents the saturation vapor pressure of 2,3,3,3-tetrafluoropropene, y2, s represents the coefficient of activity 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 the trans-1,3,3,3 -tetrafluoro-l-propene (1234ze-E); and preferably said organic extractant has a C2 absorbency, s greater than 0.8, 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 extractant organic at infinite dilution.

Selon un mode de réalisation préféré, dans ladite composition, l'agent d'extraction organique est sélectionné parmi le groupe consistant en methylformate, ethoxy-ethene, propanone, methylacetate, isobutanal, isopropylformate, ethylacetate, butanone, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 3-pentanone, 2-pentanone, 1,3-dioxane, 3,3-dimethyl-2-butanone, sec-butylacetate, 4-methyl-2-pentanone, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, diethylcarbonate, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; de préférence methylformate, propanone, butanone, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec-butylacetate, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; en particulier methylformate, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec-butylacetate, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal.

According to a preferred embodiment, said composition comprises between 75 and 99.99% by weight of 2,3,3,3-tetrafluoro-l-propene, 0.01 to 25% by weight of trans-1,3, 3,3-tetrafluoro-l-propene (1234ze-E), and less than 1% by weight of methyl chloride (40) based on the total weight of the composition.

BRIEF DESCRIPTION OF FIGURES

Figs la-c show schematically a device for implementing a process for purifying 2,3,3,3-tetrafluoro-l-propene according to a particular embodiment of the present invention.

2 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.

Detailed Description of the Invention

The term "hydrocarbon" as used herein refers to linear or branched alkane compounds C1-C20, C3-C20 cycloalkane, alkene, C2-C20, C3-C20 cycloalkene, arene C6-C18. For example, the alkane term refers to compounds of formula C n H 2n + 2 wherein n is between 1 and 20. The term alkane C1-C20 includes, for example pentane, hexane, heptane, octane, nonane, decane or isomers thereof. The term alkene, C2-C20 refers to hydrocarbon compounds containing one or more double carbon-carbon bonds and having 2 to 20 carbon atoms. The term cycloalkane C3-C20 refers to a saturated hydrocarbon ring having 3 to 20 carbon atoms. The term C6-C18 refers to cyclic and aromatic hydrocarbon compounds having 6 to 18 carbon atoms. Cycloalkene term C3-C20 refers to cyclic hydrocarbon compounds containing from 3 to 20 carbon atoms and comprising one or more double carbon-carbon bonds.

The term "alkyl" means a monovalent radical derived from an alkane, linear or branched, comprising 1 to 20 carbon atoms. The term "cycloalkyl" means a monovalent radical derived from a cycloalkane having 3 to 20 carbon atoms. The term "aryl" means a monovalent radical derived from an arene having 6 to 18 carbon atoms. The term "alkenyl" denotes a monovalent radical of 2 to 20 carbon atoms and at least one carbon-carbon double bond. The term "alkynyl" refers to a monovalent radical of 2 to 20 carbon atoms and at least one carbon-carbon triple bond. The term "halogen" refers to a group F, Cl, Br or -I. The term "cycloalkenyl" refers to a monovalent radical derived from a cycloalkene having 3 to 20 carbons. The alkyl substituents C1-C20 alkenyl, C2-C20 alkynyl, C2-C20, C3-C20 cycloalkenyl, C3-C20, C6-C18 may be substituted or not by one or more -OH, halogen, -N is C (0) b , -C (0) NR a R b , -CN, -N0 2 , -NR a R b , -OR a , -SR a , -C0 2 R a , -OC (0) OR a , -OC (0) R a , -C (0) H, -C (0) R a wherein R a and R b are independently of each other hydrogen, C 1 -C C20 unsubstituted alkenyl, unsubstituted C2-C20 alkynyl unsubstituted C2-C20 cycloalkyl, unsubstituted C3-C20 cycloalkenyl, unsubstituted C3-C20 aryl, C6-C18 unsubstituted. In the substituents -NR a R b , -NR a C (0) R b , -C (0) NR a R b , R a and R b may form with the nitrogen atom or with the functional group to which they are attached, a saturated or unsaturated, aromatic or nonaromatic, comprising from 4 to 10 ring members.

The term "hydrohalocarbures" refers to compounds of the formula R a X where R a is selected from C1-C20 alkenyl, C2-C20 alkynyl, C2-C20, C3-C20 cycloalkenyl, C3- C20, C6-C18 and X represents a chlorine, fluorine, bromine or iodine. The alkyl substituents C1-C20 alkenyl, C2-C20 alkynyl, C2-C20, C3-C20 cycloalkenyl, C3-C20, C6-C18 may be substituted or not by one or more -OH, halogen, -NR a C (0) R b , -C (0) NR a R b -CN, -N0 2 , -NR a R b , -OR a , -

SR a , -C0 2 R a , -OC (0) OR a , -OC (0) R a , -C (0) H, -C (0) R a wherein R a and R b are as defined above.

The term "alcohol" refers to hydrocarbons or hydrohalocarbures as defined above wherein at least one hydrogen atom is replaced with a hydroxyl group -OH.

The term "ketone" refers to hydrocarbons comprising at least one or more carbonyl functional groups R c -C (0) -R d wherein R c and R d are independently from each other alkyl, C1- C20 alkenyl, C2-C20 alkynyl, C2-C20, C3-C20 cycloalkenyl, C3-C20, C6-C18 and may be substituted or not by one or more -OH, halogen, -NR a C (0) R b , -C (0) NR a R b -CN, -N0 2 , -NR a R b , -OR a , -SR a , -C0 2 R a , -OC (0) OR a , -OC (0) R a , -C (0) H, -C (0) R a wherein R a and R b are as defined above, R c and R d may be linked together to form with the carbonyl group to which they are attached a cyclic ketone having 4 to 10 ring members, preferably from 4 to 7 members. The cyclic ketone may also comprise one or more double carbon-carbon bonds. The cyclic ketone may also be unsubstituted or substituted with one or more substituents as defined above.

The term "amino" refers to hydrocarbons comprising at least one or more amine functional groups -NR C R C wherein R c and R d are as defined above, R c and R d may be linked together to form with the nitrogen atom to which they are attached an aromatic or nonaromatic heterocycle containing from 4 to 10 ring members.

The term "esters" refers to compounds of the formula R c -C (0) -0-R d wherein R c and R d are as defined above, R c and R d may be linked together to form with the ester group a ring comprising from 4 to 20 carbon atoms.

The term "ether" refers to compounds of the formula R c -0-R d wherein R c and R d are as defined above, R c and R d may be linked together to form with the atom oxygen which they are attached a heterocycle containing 4 to 20 carbon atoms.

The term "aldehyde" refers to compounds comprising at least one or more functional groups -C (0) -H.

The term "nitrile" refers to compounds comprising at least one or more functional groups -CN.

The term "carbonate" refers to compounds of the formula R c -0-C (0) -0-R d wherein R c and R d are as defined above.

The term "thioalkyl" relates to compounds of formula c S d in which R c and R d are as defined above.

The term "amide" refers to compounds of the formula R c C (0) NR e R d wherein R c and R d are as defined above, R e is defined as R c ; R c and R d may be linked together to form with the amide group -C (0) N to which they are attached a cyclic amide containing from 4 to 10 ring members, preferably from 4 to 7 members. The cyclic amide can also include one or more double carbon-carbon bonds. The cyclic amide can also be unsubstituted or substituted with one or more substituents as defined above.

The term "heterocycle" refers to a carbocycle containing from 4 to 10 ring members of which at least one of the ring members is a heteroatom selected from the group consisting of O, S, P and N. The heterocyclic ring may comprise one or more carbon double bond atoms or one or more double carbon-heteroatom bond or one or more double hetero atom-hetero atom bond. Preferably, the heterocycle may comprise 1, 2, 3, 4 or 5 heteroatoms as defined above. In particular, the heterocycle may comprise 1, 2 or 3 heteroatoms selected from oxygen, nitrogen or sulfur. Preferably, the heterocycle may be a carbon ring comprising 4 to 6-membered ring including 1, 2 or 3 ring members are heteroatoms selected from O or N. The heterocycle may be unsubstituted or substituted by one or more substituents selected from -OH , halogen, -NR a C (0) R b , -C (0) NR a R b -CN, -N0 2 , -NR a R b , -OR a , -SR a , -C0 2 R a , - OC (0) OR a , -OC (0) R a , -C (0) H, -C (0) R a wherein R a and R b are as defined above.

The term "azeotropic composition" refers to a liquid mixture of two or more compounds that behave as a single substance, and which boils at fixed temperature keeping an identical composition in liquid phase to the gas phase. The term "quasi-azeotropic composition" refers to a liquid mixture of two or more compounds having a constant boiling or which tends not to split when subjected to boiling or evaporation. The term "organic extractant" refers to a compound having at least one carbon atom.

According to a first aspect, the invention relates to a process for purifying 2,3,3,3-tetrafluoro-l-propene (1234yf). The purification process is performed from a first composition comprising 2,3,3,3-tetrafluoro-l-propene and methyl chloride (40).

Preferably, said method comprises the steps of:

a) contacting said first composition with at least one organic extractant to form a second composition;

b) extractive distillation of said second composition to form:

i) a third composition comprising said organic extractant and methyl chloride (40); and

ii) a stream comprising 2,3,3,3-tetrafluoro-l-propene, c) recovering and separating said third composition, preferably by distillation, to form a stream comprising said organic extractant and a stream comprising chloromethane (40).

According to a preferred embodiment, the stream comprising said organic extractant is recycled to step a) of this method.

According to a preferred embodiment, said first composition may comprise trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E). Whereby said second composition may comprise trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E). Said third composition may thus comprise trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E). Advantageously, step c) of this method can consist in the recovery and separation of said third composition, preferably by distillation, to form firstly a stream comprising said organic extractant and secondly a current comprising methyl chloride (40) and trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E).

Thus the present process may be a purification process of the 2,3,3,3-tetrafluoro-l-propene (1234yf) from a first composition comprising 2,3,3,3-tetrafluoro-l-propene, chloromethane (40) and trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E), said method comprising the steps of:

a) contacting said first composition with at least one organic extractant to form a second composition; b) extractive distillation of said second composition to form: i) a third composition comprising said organic extractant, trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) and methyl chloride (40) ; and

ii) a stream comprising 2,3,3,3-tetrafluoro-l-propene (1234yf), c) recovering and separating said third composition, preferably by distillation, to form firstly a stream comprising said agent organic extractant and also a stream comprising methyl chloride (40) and trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); of

Preferably the stream comprising said organic extractant is recycled to step a).

Said first composition may comprise between 75 and 99.99% by weight of 2,3,3,3-tetrafluoro-l-propene based on the total weight of the first composition, preferably between 80 and 99.9% by weight, preferably between 85 and 99.8% and in particular between 90 and 99.5% by weight of 2,3,3,3-tetrafluoro-l-propene based on the total weight of the first composition.

When it contains, said first composition may comprise less than 1% by weight of methyl chloride (40) based on the total weight of the first composition, advantageously between 1 and 5000 ppm by weight, preferably between 1 and 2000 ppm and in particular between 10 and 1500 ppm by weight of methyl chloride (40) based on the total weight of the first composition.

When it contains, said first composition may comprise between 0.01 and 25% by weight trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) based on the total weight of the first composition , advantageously between 0.1 and 20% by weight, preferably between 0.2 and 15% by weight, in particular between 0.5 and 10% by weight, more particularly between 3 and 10% by weight trans-l, 3,3,3 tetrafluoro-l-propene (1234ze-E) based on the total weight of the first composition.

According to a preferred embodiment, said organic extractant may be one solvent selected from the group consisting of hydrocarbons, hydrohalocarbure, alcohol, ketone, amine, ester, ether, aldehyde, nitrile, carbonate, thioalkyl, amide and heterocycle. Alternatively, the organic extractant may be difluorodiethylsilane or triethylfiuorosilane. Preferably, said organic extractant may be selected from the group consisting of ketone, amine, ester, ether, alcohol, and heterocycle aldehyde. Preferably, the heterocycle may be a carbon ring comprising 4 to 6-membered ring including 1, 2 or 3 ring members are heteroatoms selected from N or O, preferably O.

When the first composition contains the trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E), the organic extractant may be selected to allow separation between the latter and 2,3 , 3,3-tetrafluoro-l-propene (1234yf). Thus, the present method may permit separation between firstly the 2,3,3,3-tetrafluoro-l-propene (1234yf) and secondly chloromethane (40) and the trans-3,3 , 3-tetrafluoro-l-propene (1234ze-E).

Preferably the hydrocarbons are selected from the group consisting of 2,2-dimethylbutane, 3-methylpentane, 2,4-dimethylpentane, cyclohexane, cyclohexene, methylcyclohexane, 2,4,4-trimethyl-l-pentene, 2,2, 4-trimethyl-2-pentene, 1-

methylcyclohexene, toluène, 2,3-dimethylhexane, ethylcyclohexane, ethylbenzene, 1,4-dimethylbenzene, 1,3-dimethylbenzene, 1,2,3-trimethylcyclohexane, 1,2-dimethylbenzene, styrene.

Preferably, the hydrohalocarbures are selected from the group consisting of chloroethane, bromofluoromethane, l-bromo-l, 2-difluoroethylene, trichlorofluoromethane 1-chloro-l, l-difluoropropane, l, l, l-trifluoro-2-bromoethane, l, l-dichloro-2,2,2-trifluoroethane, l, 2-dichloro-l, l, 2-trifluoroethane, 1,1-dichloroethylene, 2-chloro-2-fluoropropane, 1-chloro-2,2 difluoroethane, 2-chloropropane, bromoethane, 2-chloro-l, l, l, 3,3-pentafluoropropane, 1-chloro-l, 2,2-trifluoropropane, iodomethane, 3-chloropropene, 3-chloro-l, l, l-trifluoropropane, l, l, l-trichloro-2,2,2-trifluoroethane, l, 2-dichloro-l, 2-difluoroethane, 1,1,2-trichloro-l, 2,2-trifluoroethane, l, 2-dichloro-l, l, 3,3,3-pentafluoropropane, l-chloro-1,2,2,3-tetrafluoropropane, 2-chloro-2-methylpropane, 3-chloro-l, l, l, 3- tetrafluoropropane, 2-chloro-1,1,1,3-tetrafluoropropane, l, 3-dichloro-l, l, 2,3,3-pentafluoropropane, l, 2-dichloro-3,3,3-trifluoropropene, l, 3-dichloro-l, l, 2,2,3-pentafluoropropane, 2,2-dichloro-1,1,3-tetrafluorop ropane, l-chloro-2,2-difluoropropane, 1,1-dichloroethane, 2-bromopropane, 1,1-dichloro-2,2-difluoroethane, 2,2-dichloro-l, 1,3,3-tetrafluoropropane, 2,3-dichloro-l, 1,1,2-tetrafluoropropane, l, l-dichloro-l, 2,2,3-tetrafluoropropane, 1,3-dichloro-l, 1,2,2-tetrafluoropropane, l, l, l-trichloro-2,2-difluoroethane, l, 2-dichloro-l, 2,3,3-tetrafluoropropane, chlorobromomethane, 2-chlorobutane, l, 3-dichloro-l, l, 3,3-tetrafluoropropane, l, 3-dichloro-l, 2,2,3-tetrafluoropropane, l, 2-dichloro-l, l, 2,3-tetrafluoropropane, 3-bromopropene, 2,3-dichloro-l, l, 3- tetrafluoropropane, l, l-dichloro-2-fluoroethane, 1-bromopropane, l, l-difluoro-l, 2,2-trichloroethane, l, l, 2-trichloro-l, 2-difluoroethane, iodoethane, 2-bromo- 2-methylpropane, 1,2-dichloro-l-fluoroethane, 1,1,1-trichloroethane, l-chloro-3-fluoropropane, 2,3-dichloro-l, 1,1-trifluoropropane, tetrachloromethane, 1-chlorobutane, l, 3-dichloro-l, l, 2-trifluoropropane, l, l-dichloro-2,2,3-trifluoropropane, l, 3,3-trichloro-l, 2,2-tetrafluoropropane, 2-chloro- 2-methylbutane, 1,2-dichloroethane, l, l, l-trichloro-2,2,3,3-tetrafluoropropane, l, l, 3-trichloro-2,2,3-tetrafluoropropane, l, 3- dichloro-2,2-trifluoropropane, trichloroethene, 1,1-dichloropropane, l, 2-dichloro-2-fluoropropane, 2-iodopropane, dichlorobromomethane, 2-bromobutane, 2,2-difluorotetrachloroethane, l, l, 2, 2-tetrachloro-l, 2-difluoro-ethane, 1-fluorohexane, 1,3-dichloro-l, 2,3-trifluoropropane, 2,3-dichloro-l-propene, 3-chloropentane, trichloroacetaldehyde, isoamylchloride, l, l, l-trichloro-2,2,3-trifluoropropane, l-chloro-4-fluorobutane, l-bromo-3-fluoropropane, 1-bromobutane, l, l, 2-trichloro-2-fluoroethane, 1-

iodopropane, l,l,3-trichloro-l,2,2-trifluoropropane, l,l,3-trichloro-2,2,3-trifluoropropane, cis-1,3-dichloropropene, 2,2-dichlorobutane, bromotrichloromethane, l,l,l,2-tetrachloro-2-fluoroethane, l-bromo-2-chloroethane, 2-bromo-2-methyl butane, trans-l,3-dichloropropene, 2-fluorotoluene, 1,1,2-trichloroethane, l,l,l-trichloro-3-fluoropropane, 3,3,3-trichloro-l-propene, l-chloro-3,3-dimethyl butane, l,l,l,2-tetrachloro-3,3,3-trifluoropropane, 2-bromopentane, trichloroacetylchloride, 2,3-dichlorobutane, l,l,3,3-tetrachloro-l,2,2-trifluoropropane, l,l,l,3-tetrachloro-2,2,3-trifluoropropane, l-bromo-3-methylbutane, 1,3-dichloro-trans-2-butene, 1,3-dichloropropane, tetrachloroethene, 1,2-dibromo-l-fluoroethane, 1,2,2-trichloropropane, 1,2-dichlorobutane, l,2,2,3-tetrachloro-3,3-difluoropropane, 2,3-dichloro-2-methylbutane, 1-bromopentane, l,2-dichloro-2-butene, 1-iodobutane, 1,2-dibromoethane, chlorobenzene, 1,1,2-trichloropropane, 1,3-dichlorobutane, pentachlorofluoroethane, 1,2-dibromopropane, 1,2,3-trichloropropene, l-chloro-3-bromopropane, 1,1,3,3-tetrachloro-l-fluoropropane, l,l,2,2,3-pentchloro-3,3-difluoropropane, 1,1,2,2-tetrachloroethane, 1,2-dichloropentane, tribromomethane.

Preferably, the alcohols are selected from the group consisting of 2,2,2-trifluoroethanol, l, l, l-trifluoro-2-propanol, tert-butanol, 2,2-difluoroethanol, 2-allyloxyethanol, 2-methyl- 2-butanol, 2,2,3,3-tetraflouro-l-propanol, 2,2-dimethyl-l-propanol,

1- methoxy2-propanol, l-(dimethylamino)-2-propanol, 3-methyl-3-pentanol, l-chloro-2-methyl- 2- propanol, 4,4,4-trifluorobutanol, 3-fluoropropanol, 2-chloroethanol, 2-methoxyl-propanol, 1-ethoxy-2-propanol, 4-methyl-2-pentanol, 1,2-octanediol, 2-chloro-l-propanol, 2- (dimethylamino)-ethanol, 3-hexanol, 2-hexanol, 2-ethoxy-l-propanol, 3,3,4,4,5,5,6,6-octafluoro-l-pentanol, 2,3-dimethylbutanol, 2-ethyl-l-butanol, 2-methyl-l-pentanol, 2-propoxyethanol, l-propoxy-2-propanol, 2-aminophenol.

Preferably, the ketones are selected from the group consisting propanone, butanone, 3-pentanone, 2-pentanone, 3,3-dimethyl-2-butanone, 4-methyl-2-pentanone, 2-hexanone, 5-hexen- 2-one, 4-methyl-2-hexanone.

De préférence, les aminés sont sélectionnées parmi le groupe consistant en Ethylamine, isopropylamine, ethylmethylamine, 2-amino-2-methylpropane, n-propylamine, isopropylmethylamine, diethylamine, 2-butanamine, n-methylpropylamine, 1-butylamine, diisopropylamine, 3-methyl-2-butanamine, 3-pentylamine, n-methylbutylamine, l-methoxy-2-propanamine, 2-methoxyethanamine, 2-methoxy-lpropanamine, n-pentylamine, n-methylhydroxylamine, dipropylamine, 2-ethoxyethanamine, n-methyl-l,2-ethanediamine, pyridine, 1,2-diaminoethane, 1,2-propanediamine, 2-ethylbutylamine, n-ethylethylenediamine,

1.1- diethoxy-n,n-dimethylmethanamine, 2-methylpyridine, 4-methyl-2-hexanamine, hexylamine, cyclohexylamine, n-ethyl-2-dimethylaminoethylamine, 1,3-propanediamine, 2-heptanamine, η,η-diethylethylenediamine, 2,6-dimethylpyridine, 4-methylpyridine, η,η'-diethyl-l,2-ethanediamine, dimethylethanolamine.

claims

A process for purifying 2,3,3,3-tetrafluoro-l-propene (1234yf) from a first composition comprising 2,3,3,3-tetrafluoro-l-propene and chloromethane (40), said method comprising the steps of:

a) contacting said first composition with at least one organic extractant to form a second composition; b) extractive distillation of said second composition to form: i) a third composition comprising said organic extractant and methyl chloride (40); and

ii) a stream comprising 2,3,3,3-tetrafluoro-l-propene (1234yf), c) recovering and separating said third composition, preferably by distillation, to form a stream comprising said organic extractant and a stream comprising methyl chloride (40); preferably the stream comprising said organic extractant is recycled to step a).

Method according to the preceding claim characterized in that said first composition, said second composition and said third composition also include trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); step c) being the recovery and separation of said third composition, preferably by distillation, to form firstly a stream comprising said organic extractant and also a stream comprising methyl chloride (40) and trans - 1,3,3,3-tetrafluoro-l-propene (1234ze-E).

The method of any one of the preceding claims, characterized in that said organic extractant is a solvent selected from the group consisting of hydrocarbons, hydrohalocarbure, alcohol, ketone, amine, ester, ether, aldehyde, nitrile, carbonate, thioalkyl, amide and heterocycle; or the organic extractant is difluorodiethylsilane or triethylfiuorosilane; preferably from the group consisting of ketone, amine, ester, ether, alcohol, and heterocycle aldehyde.

A method according to any preceding claim characterized in that the organic extractant has a boiling point between 10 and 150 ° C.

A method according to any preceding claim characterized in that said organic extractant has 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,

IP is the saturation vapor pressure of 2,3,3,3-tetrafluoro-l-propene,

Y2, s represents the coefficient of activity of chloromethane (40) in said organic extractant at infinite dilution,

P2 represents the saturation vapor pressure of methyl chloride (40);

advantageously 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 to 2.0.

A method according to any preceding claim characterized in that said organic extractant has a C2 absorbency, 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 chloromethane (40);

advantageously C2 absorption capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.50, more preferably greater than or equal to 0.60, in particular greater than or equal to 0.70, more particularly greater than or equal to 0.80.

A method according to any preceding claim characterized in that said organic extractant has 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,

IP is 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 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; and preferably said organic extractant has 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); advantageously C2 absorption capacity, s is greater than or equal to 0.40, preferably greater than or equal to 0.50, more preferably greater than or equal to 0.60, in particular greater than or equal to 0.70, more particularly greater than or equal to 0.80.

A method according to any preceding claim characterized in that said first composition is an azeotropic composition or quasi-azeotropic comprising 2,3,3,3-tetrafluoro-l-propene, methyl chloride (40) and trans-1,3, 3,3-tetrafluoro-l-propene (1234ze-E).

Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que ledit agent d'extraction organique est choisi parmi le groupe consistant methylformate, 2-methoxy-l-propene, ethoxy-ethene, propanone, methylacetate, isobutanal, isopropylformate, ethylacetate, butanone, n-propylformate, 1,2-dimethoxyethane, isopropylacetate, l-methoxy-2-propanamine, 2-methoxyethanamine, 2-methylbutanal, tert-butylacetate, ethylpropionate, dioxane, 3-pentanone, 2-pentanone, 2-methoxy-lpropanamine, trimethoxymethane, 1,3-dioxane, 3,3-dimethyl-2-butanone, 2-ethoxyethanamine, sec-butylacetate, n-methyl-l,2-ethanediamine, 4-methyl-2-pentanone, 1,2-diaminoethane, butyronitrile, l-methoxy2-propanol, 1,2-propanediamine, 2,6-dimethyl-5-heptenal, l-(dimethylamino)-2-propanol, diethylcarbonate, n-butylacetate, 2-hexanone, n-ethylethylenediamine, 5-hexen-2-one, 2-methylpyridine, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal, 2-(dimethylamino)-ethanol, 2-methylpyrazine, 2-ethoxy-l-propanol, 1,3-propanediamine, valeronitrile, 2,6-dimethylpyridine, 4-methyl-2-hexanone, 1-methoxy-2-acetoxypropane, 4-methylpyridine, 2,6-dimethylmorpholine, methylhexanoate, 2-propoxyethanol, l-propoxy-2-propanol ; avantageusement methylformate, ethoxy-

ethene, propanone, methylacetate, isobutanal, isopropylformate, ethylacetate, butanone, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 3- pentanone, 2-pentanone, 1,3-dioxane, 3,3-dimethyl-2-butanone, sec-butylacetate, 4- methyl-2-pentanone, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, diethylcarbonate, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; de préférence methylformate, propanone, butanone, isopropylacetate, 2- methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec-butylacetate, 1,2- diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n-butylacetate, 2- methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; en particulier methylformate, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec- butylacetate, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n- butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal.

10. The method of any one of the preceding claims characterized in that it comprises, prior to step a) the steps of:

i ') implementation or providing a composition comprising 2,3,3,3-tetrafluoro-l- propene, impurities having a lower boiling point than the boiling point of 2,3,3,3 tetrafluoro-l-propene, methyl chloride (40) and optionally the heavy impurities and / or trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); Any implementation or providing a composition comprising 2,3,3,3-tetrafluoro-l-propene, impurities having a lower boiling point than the boiling point of 2,3,3,3-tetrafluoro -l-propene, chloromethane (40), trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E) and optionally the heavy impurities;

ii ') distillation of said composition of step i) to remove the top of column impurities having a boiling point below the boiling point of tetrafluoro-l-propene and 2,3,3,3 form a first stream comprising 2,3,3,3-tetrafluoro-l- propene, chloromethane (40), and optionally or not heavy impurities and / or trans-l, 3,3,3-tetrafluoro-l-propene (1234ze- E), recovered at the bottom of distillation column; Any distillation of said composition of step i) to remove the top of column impurities having a boiling point below the boiling point of 2,3,3,3-tetrafluoro-l-propene and forming a first stream comprising 2,3,3,3-tetrafluoro-l-propene, chloromethane (40), trans-l, 3,3,3-tetrafluoro-l-

propene (1234ze-E) and optionally or non-heavy impurities, recovered at the bottom of distillation column;

iii ') optionally or not, distilling said first stream recovered at the bottom of distillation column in step ii') to retrieve the column head a second stream comprising 2,3,3,3-tetrafluoro-l-propene, chloromethane (40) and optionally or not trans-3,3,3-tetrafluoro-l-propene (1234ze-E); and at the bottom of distillation column a stream comprising the heavy impurities; preferably the second stream comprises 2,3,3,3-tetrafluoro-l-propene, methyl chloride (40) and trans- 1,3,3,3-tetrafluoro-l-propene (1234ze-E);

said first stream recovered in step ii ') or said second stream recovered in step iii') corresponds to said first composition used in step a).

11. A process for production and purification of 2,3,3,3-tetrafluoro-l-propene comprising the steps of:

A) fluorination in the presence of a catalyst of a compound of formula (I) CX (Y) 2-CX (Y) m - CHmXY wherein 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;

B) recovering a stream comprising 2,3,3,3-tetrafluoro-l-propene, methyl chloride (40) and optionally or not trans-3,3,3-tetrafluoro-l-propene (1234ze-E );

C) implementing the method according to any one of claims 1 to 10 from the stream recovered in step B).

12. A composition comprising 2,3,3,3-tetrafluoropropene, an organic extraction agent, methyl chloride (40) and trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E); said organic extractant having a separation factor If 2 greater than 1.6, 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-tetrafluoropropene in said organic extractant at infinite dilution, PI represents the saturation vapor pressure of 2,3,3,3-tetrafluoropropene, y2, s represents the coefficient of activity of chloromethane (40) in said organic extractant at infinite dilution, P2 represents the saturation vapor pressure of methyl chloride (40); and preferably said organic extractant has a capacity of absorption C2, s greater than 0.8, said absorptive capacity is calculated by the formula C2, s = l / (y2, s) wherein y2, s is the activity coefficient of methyl chloride (40) in said organic extractant at infinite dilution; and

a separation factor If 2 greater than 1.6, 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-tetrafluoropropene in said organic extractant at infinite dilution, PI represents the saturation vapor pressure of 2,3,3,3-tetrafluoropropene, Y2, s represents the coefficient of activity trans-l, 3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic extractant at infinite dilution, P2 represents the saturation vapor pressure of the trans-3,3,3 tetrafluoro-l-propene (1234ze-E); and preferably said organic extractant has a capacity of absorption C2, s greater than 0.8, said absorptive capacity is calculated by the formula C2, s = l / (y2, s) wherein y2, s is the activity coefficient of the trans- 1,3,3,3-tetrafluoro-l-propene (1234ze-E) in said organic extractant at infinite dilution.

13. Composition selon la revendication précédente caractérisée en ce que l'agent d'extraction organique est sélectionné parmi le groupe consistant en methylformate, ethoxy-ethene, propanone, methylacetate, isobutanal, isopropylformate, ethylacetate, butanone, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 3- pentanone, 2-pentanone, 1,3-dioxane, 3,3-dimethyl-2-butanone, sec-butylacetate, 4- methyl-2-pentanone, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, diethylcarbonate, n-butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; de préférence methylformate, propanone, butanone, isopropylacetate, 2- methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec-butylacetate, 1,2- diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n-butylacetate, 2- methoxyl-propanol, l-ethoxy-2-propanol, hexanal ; en particulier methylformate, isopropylacetate, 2-methoxyethanamine, tert-butylacetate, dioxane, 1,3-dioxane, sec- butylacetate, 1,2-diaminoethane, l-methoxy2-propanol, 1,2-propanediamine, n- butylacetate, 2-methoxyl-propanol, l-ethoxy-2-propanol, hexanal.

14. The composition of claims 12 or 13 characterized in that it comprises between 75 and 99.99% by weight of 2,3,3,3-tetrafluoro-l-propene, 0.01 to 25% by weight trans-l, 3,3,3-tetrafluoro-l-propene (1234ze-E), and less than 1% by weight of methyl chloride (40) based on the total weight of the composition.