Process for the manufacture of fluorinated olefins
View Patent ↗A method for producing 1,1,1,2-tetrafluoropropene and/or 1,1,1,2,3-pentafluoropropene using a single set of four unit operations, the unit operations being (1) hydrogenation of a starting material comprising hexafluoropropene and optionally recycled 1,1,1,2,3-pentafluoropropene; (2) separation of the desired intermediate hydrofluoroalkane, such as 1,1,1,2,3,3-hexafluoropropane and/or 1,1,1,2,3-pentafluoropropane; (3) dehydrofluorination of the intermediate hydrofluoroalkane to produce the desired 1,1,1,2-tetrafluoropropene and/or 1,1,1,2,3-pentafluoropropene, followed by another separation to isolate the desired product and, optionally, recycle of the 1,1,1,2,3-pentafluoropropene.
1. A method for producing 1,1,1,2-tetrafluoropropene comprising:
a. hydrogenating a starting material stream comprising hexafluoropropylene by contacting said starting material stream with a reducing agent to produce an intermediate stream comprising 1,1,1,2,3-pentafluoropropane and 1,1,1,2,3,3-hexafluoropropane;
b. dehydrofluorinating said 1,1,1,2,3-pentafluoropropane and at least a portion of said 1,1,1,2,3,3-hexafluoropropane reactor to produce a product stream comprising 1,1,1,2-tetrafluoropropene and 1,1,1,2,3-pentafluoropropene;
c. separating at least a portion of said 1,1,1,2,3-pentafluoropropene from said 1,1,1,2-tetrafluoropropene to produce a recycle stream rich in 1,1,1,2,3-pentafluoropropene and a final product stream rich in said 1,1,1,2-tetrafluoropropene; and
d. introducing said recycle stream to step (a), wherein at least a portion of said 1,1,1,2,3-pentafluoropropene is hydrogenated to form a portion of said 1,1,1,2,3-pentafluoropropane.
2. The method of claim 1 wherein at least a portion of said hexafluoropropylene reacts with said reducing agent to produce 1,1,1,2,3,3-hexafluoropropane and at least a portion of said 1,1,1,2,3,3-hexafluoropropane reacts with said reducing agent to produce at least a portion of said 1,1,1,2,3-pentafluoropropane.
3. The method of claim 1 wherein at least a portion of said 1,1,1,2,3,3-hexafluoropropane of said intermediate stream is separated into an intermediate recycle stream and said intermediate recycle stream is introduced into the hydrogenation reactor wherein at least a portion of said recycled 1,1,1,2,3,3-hexafluoropropane is hydrogenated to form 1,1,1,2,3-pentafluoropropane.
4. The method of claim 1 wherein the dehydrofluorination 1,1,1,2,3-pentafluoropropane and at least a portion of said 1,1,1,2,3,3-hexafluoropropane are performed concurrently.