Method for purifying 1-chloro-3,3,3-trifluoropropene
The present invention relates to a process for purifying 1-chloro-3,3,3-trifluoropropene comprising the steps of: a) providing a stream comprising 1-chloro-3,3,3-trifluoropropene and at least one compound of formula HX wherein X is F or Cl; b) bringing the stream from step a) into contact with a solution A comprising at least one sulfite salt of formula Y n+ m SO 3 wherein Y is an alkali or alkaline-earth metal, n=1 or 2, and m=2 when n=1 or m=1 when n=2; in order to form a neutralized stream A1 comprising 1-chloro-3,3,3-trifluoropropene.
1. A process for purifying 1-chloro-3,3,3-trifluoropropene comprising the steps of:
a) providing a stream comprising 1-chloro-3,3,3-trifluoropropene and at least one compound of formula HX wherein X is F or Cl;
b) bringing the stream from step a) into contact with a solution A comprising at least one alkali metal hydroxide or one alkaline-earth metal hydroxide and at least one sulfite salt of formula Y n+ m SO 3 wherein Y is an alkali or alkaline-earth metal, n=1 or 2, and m=2 when n=1 or m=1 when n=2; in order to form a neutralized stream A1 comprising 1-chloro-3,3,3-trifluoropropene.
2. The process as claimed in claim 1 , wherein said at least one sulfite salt is selected from the group consisting of Na 2 SO 3 , K 2 SO 3 , Li 2 SO 3 , CaSO 3 and MgSO 3 or a mixture thereof.
3. The process as claimed in claim 1 , wherein said at least one sulfite salt is Na 2 SO 3 or K 2 SO 3 or a mixture of both.
4. The process as claimed in claim 1 , wherein said solution A comprises at least one alkali metal hydroxide.
5. The process as claimed in claim 1 , wherein said solution A of step b) comprises NaOH and Na 2 SO 3 .
6. The process as claimed in claim 1 , wherein said solution A of step b) is an aqueous solution.
7. The process as claimed in claim 1 , wherein the content of said at least one sulfite salt is between 2 and 25% by weight based on the total weight of said solution A.
8. The process as claimed in claim 1 , wherein step b) is carried out at a temperature of 10° C. to 70° C.
9. The process as claimed in claim 1 , wherein the content of alkali metal hydroxide or alkaline-earth metal hydroxide is between 2 and 25% by weight based on the total weight of said solution A.
10. The process as claimed in claim 1 , wherein step b) is carried out with an aqueous solution A comprising from 3 to 10% of Na 2 SO 3 and from 3 to 10% NaOH; and at a temperature of from 20° C. to 60° C.
11. The process as claimed in claim 1 , wherein, in the stream provided in step a), the molar ratio between the trans isomer and the cis isomer of 1-chloro-3,3,3-trifluoropropene is from 2:1 to 50:1.
12. A process for producing 1-chloro-3,3,3-trifluoropropene comprising the steps of:
i. bringing hydrofluoric acid (HF) into contact, in a reactor, with a starting composition comprising at least one chlorinated compound selected from the group consisting of 1,1,3,3-tetrachloropropene, 1,3,3,3-tetrachloropropene and a mixture of the two, to obtain a stream B comprising 1-chloro-3,3,3-trifluoropropene, HF and/or HCl;
ii. carrying out the process for purifying 1-chloro-3,3,3-trifluoropropene according to claim 1 using a stream comprising 1-chloro-3,3,3-trifluoropropene, HF and/or HCl.