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 at least one fluorinated olefin comprising:
a. hydrogenating a starting material stream comprising at least one alkene according to Formula (I):
(CX n Y 3−n )(CR 1 a R 2 b ) z CX═CH m X 2−m (I)
by contacting said starting material with a reducing agent to produce an intermediate product stream comprising at least one alkane according to Formula (II):
(CX n Y 3−n )(CR 1 a R 2 b ) z CHXCH m+1 X 2−m (II)
where:
each X is independently Cl, F, I or Br, provided that at least two Xs are F;
each Y is independently H, Cl, F, I or Br;
each R 1 is independently H, Cl, F, I, Br or unsubstitued or halogen substituted methyl or ethyl radical;
each R 2 is independently H, Cl, F, I, Br or unsubstitued or halogen substituted methyl or ethyl radical;
n is 1, 2 or 3;
a and b are each 0, 1 or 2, provided that a+b =2;
m is 0, 1 or 2; and
z is 0, 1, 2 or 3;
b. optionally, separating said intermediate product stream into a plurality of stream, said plurality of intermediate product streams comprising two or more stream selected from the group consisting of a first stream rich in at least a first alkane according to Formula II, a seconds stream rich in at least a second alkane according to Formula II, and an alkane recycle stream;
c. dehydrofluorinating at least a portion of said intermediate process stream from step (a) or said plurality of intermediate process streams of step (b) to produce an alkene product stream comprising 1,1,1,2,3-pentafluoropropene and at least one additional alkene having a lower degree of fluorine substitution compared to the degree of fluorination of the compound of formula (I);
d. separating at least a portion of said 1,1,1,2,3-pentafluoropropene from said alkene product stream to produce a recycle stream rich in 1,1,1,2,3-pentafluoropropene and a final product stream rich in said additional alkene; and
e. introducing said recycle stream at said step (a), wherein at least a portion of said 1,1,1,2,3-pentafluoropropene is hydrogenated to form a portion of said intermediate product stream.
2. The method of claim 1 wherein said additional alkene is a compound according to formula (III):
(CX n Y 3−n )(CR 1 a R 2 b ) Z CX═CH m+1 X 1−m (III)
where each n is the same value as in formula (I) and m is 0 or 1.
3. The method of claim 2 wherein Z is 0.
4. The method of claim 3 wherein m is 0 or 1.
5. The method of claim 4 wherein said n is 3.
6. The method of claim 5 wherein X is F.
7. The method of claim 1 wherein said reducing agent is H 2 .
8. The method of claim 1 wherein said starting material stream comprises hexafluoropropylene and said additional alkene is 1,1,1,2-tetrafluoropropene.