Method for producing and purifying 2,3,3,3-tetrafluoro-1-propene

1. A process for purifying 2,3,3,3-tetrafluoro-1-propene (1234yf) using a first composition comprising 2,3,3,3-tetrafluoro-1-propene, 1,1,1,2,2-pentafluoropropane (245cb) and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), said process comprising:

a) placing said first composition in contact with at least one organic extracting agent to form a second composition;

b) distilling said second composition by extractive distillation to form:

i. a third composition comprising said organic extracting agent and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); and

ii. a stream comprising 2,3,3,3-tetrafluoro-1-propene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb); and

c) recovering and separating said third composition to form a stream comprising said organic extracting agent and a stream comprising trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

2. The process as claimed in claim 1 , further comprising recovering said stream ii) comprising 2,3,3,3-tetrafluoro-1-propene and 1,1,1,2,2-pentafluoropropane (245cb) obtained in step b), and distilling said stream to form a stream A comprising 2,3,3,3-tetrafluoro-1-propene and a stream B comprising 1,1,1,2,2-pentafluoropropane (245cb).

3. The process as claimed in claim 1 , wherein said first composition also comprises at least one of the compounds selected from the group consisting of chloromethane (40), 1,1-difluoroethane (152a), 1,1,1,2-tetrafluoroethane (134a), chloropentafluoroethane (115), trans-1,2,3,3,3-pentafluoropropene (1225ye-E), cis-1,2,3,3,3-pentafluoropropene (1225ye-Z) and 3,3,3-trifluoropropene (1243zf).

4. The process as claimed in claim 3 , wherein said at least one of the compounds selected from the group consisting of chloromethane (40), 1,1-difluoroethane (152a), 1,1,1,2-tetrafluoroethane (134a), chloropentafluoroethane (115), trans-1,2,3,3,3-pentafluoropropene (1225ye-E), cis-1,2,3,3,3-pentafluoropropene (1225ye-Z) and 3,3,3-trifluoropropene (1243zf) is also contained in said second and third compositions; and step c) of the process comprises recovering and separating said third composition to form a stream comprising said organic extracting agent and another stream comprising trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and said at least one of the compounds selected from the group consisting of chloromethane (40), 1,1-difluoroethane (152a), 1,1,1,2-tetrafluoroethane (134a), chloropentafluoroethane (115), trans-1,2,3,3,3-pentafluoropropene (1225ye-E), cis-1,2,3,3,3-pentafluoropropene (1225ye-Z) and 3 , 3 , 3 -trifluoropropene (1243zf).

5. The process as claimed in claim 1 , wherein said organic extracting agent comprises a solvent selected from the group consisting of halohydrocarbon, alcohol, ketone, amine, ester, ether, aldehyde, nitrile, carbonate, thioalkyl, amide and heterocycle; or the organic extracting agent comprises triethylfluorosilane.

6. The process as claimed in claim 1 , wherein said organic extracting agent has a separation factor S 1,2 of greater than or equal to 1.1, said separation factor being calculated by the formula S 1,2 =(γ 1,S *P1)/(γ 2,S *P2) wherein

γ 1,S represents the activity coefficient of 2,3,3,3-tetrafluoro-1-propene in said organic extracting agent at infinite dilution;

P1 represents the saturating vapor pressure of 2,3,3,3-tetrafluoro-1-propene;

γ 2,S represents the activity coefficient of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic extracting agent at infinite dilution; and

P2 represents the saturating vapor pressure of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

7. The process as claimed in claim 1 , wherein said organic extracting agent has a separation factor S 1,2 of greater than or equal to 1.1, said separation factor being calculated by the formula S 1,2 =(γ 1,S *P1)/(γ 2,S *P2) wherein

γ 1,S represents the activity coefficient of 1,1,1,2,2-pentafluoropropane (245cb) in said organic extracting agent at infinite dilution;

P1 represents the saturating vapor pressure of 1,1,1,2,2-pentafluoropropane (245cb);

γ 2,S represents the activity coefficient of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic extracting agent at infinite dilution; and

P2 represents the saturating vapor pressure of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

8. The process as claimed in claim 1 , wherein said organic extracting agent has an absorption capacity C 2,S of greater than or equal to 0.20, said absorption capacity being calculated by the formula C 2,S =1/(γ 2,S ) wherein γ 2,S represents the activity coefficient of said at least one compound consisting of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic extracting agent at infinite dilution.

9. The process as claimed in claim 1 , wherein said organic extracting agent is selected from the group consisting of ethylamine, isopropylamine, diethyl ether, n-propylamine, diethylamine, propanone, methyl acetate, butanone, diethoxymethane, isopropyl acetate, 3 -pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane, 1,1-diethoxyethane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate, 1,2-diaminoethane, 1-methoxy-2-propanol, 1,2-propanediamine, n-butyl acetate, 2-methoxy-1-propanol and hexanal.

10. The process as claimed in claim 1 , wherein the stream ii) comprising 2,3,3,3-tetrafluoro-1-propene and 1,1,1,2,2-pentafluoropropane (245cb) formed in step b) is recovered and is free of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

11. The process as claimed in claim 1 , further comprising, prior to step a):

i′) using a composition comprising 2,3,3,3-tetrafluoro-1-propene, impurities with a boiling point below the boiling point of 2,3,3,3-tetrafluoro-1-propene, 1,1,1,2,2-pentafluoropropane (245cb), and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), optionally at least one compound selected from the group consisting of chloromethane (40), 1,1-difluoroethane (152a), 1,1,1,2-tetrafluoroethane (134a), chloropentafluoroethane (115), trans-1,2,3,3,3-pentafluoropropene (1225ye-E), cis-1,2,3,3,3-pentafluoropropene (1225ye-Z), 3,3,3-trifluoropropene (1243zf), and optionally heavy impurities;

ii′) distilling said composition from step i) to remove, at the top of the column, impurities with a boiling point below the boiling point of 2,3,3,3-tetrafluoro-1-propene and to form a first stream comprising 2,3,3,3-tetrafluoro-1-propene, 1,1,1,2,2-pentafluoropropane (245cb) and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), optionally at least one compound selected from the group consisting of chloromethane (40), 1,1-difluoroethane (152a), 1,1,1,2-tetrafluoroethane (134a), chloropentafluoroethane (115), trans-1,2,3,3,3-pentafluoropropene (1225ye-E), cis-1,2,3,3,3-pentafluoropropene (1225ye-Z), 3,3,3-trifluoropropene (1243zf), and optionally heavy impurities, recovered at the bottom of the distillation column; and

iii′) optionally, distilling said first stream recovered at the bottom of the distillation column in step ii′) to recover, at the top of the column, a second stream comprising 2,3,3,3-tetrafluoro-1-propene, 1,1,1,2,2-pentafluoropropane (245cb) and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), and optionally at least one compound selected from the group consisting of chloromethane (40), 1,1-difluoroethane (152a), 1,1,1,2-tetrafluoroethane (134a), chloropentafluoroethane (115), trans-1,2,3,3,3-pentafluoropropene (1225ye-E), cis-1,2,3,3,3-pentafluoropropene (1225ye-Z) and 3,3,3-trifluoropropene (1243zf), and, at the bottom of the distillation column, a stream comprising the heavy impurities;

wherein said first stream recovered in step ii′) or said second stream recovered in step iii′) corresponding to said first composition used in step a).

12. A process for producing and purifying 2,3,3,3-tetrafluoro-1-propene, comprising:

A) fluorination in the presence of a catalyst for a compound of formula (I) CX(Y) 2 —CX(Y) m —CH m XY wherein X and Y independently represent a hydrogen, fluorine or chlorine atom and m =0 or 1; and/or catalytic fluorination in the presence of a catalyst for a compound of formula (CX n Y 3−n )CH p X 1−p CH 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-1-propene, 1,1,1,2,2-pentafluoropropane (245cb), and trans-1,3,3,3-tetrafluoro-1-propene (1234ze E); and

C) purifying 2,3,3,3-tetrafluoro-1-propene as claimed in claim 1 using the stream recovered in step B).

13. A composition comprising 2,3,3,3-tetrafluoropropene, 1,1,1,2,2-pentafluoropropane (245cb), trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and an organic extracting agent with a separation factor S 1,2 of greater than or equal to 1.60, said separation factor being calculated by the formula S 1,2 =(γ 1,S *P1)/(γ 2 ,S*P2) wherein γ 1,S represents the activity coefficient of 2,3,3,3-tetrafluoropropene in said organic extracting agent at infinite dilution, P1 represents the saturating vapor pressure of 2,3,3,3-tetrafluoropropene, γ 2,S represents the activity coefficient of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic extracting agent at infinite dilution, and P2 represents the saturating vapor pressure of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), wherein the composition is free of HF.

14. The composition as claimed in claim 13 , wherein the organic extracting agent is selected from the group consisting of ethylamine, isopropylamine, diethyl ether, n-propylamine, diethylamine, propanone, methyl acetate, butanone, diethoxymethane, isopropyl acetate, 3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane, 1,1-diethoxyethane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate, 1,2-diaminoethane, 1-methoxy-2-propanol, 1,2-propanediamine, n-butyl acetate, 2-methoxy- 1-propanol and hexanal.