Process for the manufacture of fluorinated olefins

Abstract

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.

What is claimed is: 
     
         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 unsubstituted or halogen substituted methyl or ethyl radical;    each R 2  is independently H, Cl, F, I, Br or unsubstituted 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. 
     
     
         9 . 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 in a hydrogenation reactor to produce an intermediate stream comprising 1,1,1,2,3-pentafluoropropane;   b. dehydrofluorinating said 1,1,1,2,3-pentafluoropropane in a dehydrofluorination reactor to produce a product stream comprising 1,1,1,2-tetrafluoropropene.   
     
     
         10 . The method of  claim 9  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. 
     
     
         11 . The method of  claim 10  wherein said intermediate stream further comprises 1,1,1,2,3,3-hexafluoropropane. 
     
     
         12 . The method of  claim 11  wherein said intermediate stream is separated into an intermediate recycle stream rich in 1,1,1,2,3,3-hexafluoropropane 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. 
     
     
         13 . The method of  claim 11  further comprising:
 c. dehydrofluorinating said 1,1,1,2,3,3-hexafluoropropane in said dehydrofluorination reactor to form 1,1,1,2,3-pentafluoropropene. 
 
     
     
         14 . The method of  claim 13  wherein at least a portion of said 1,1,1,2,3-pentafluoropropene is recycled and is introduced at step (a) wherein at least a portion of said recycled 1,1,1,2,3-pentafluoropropene is hydrogenated to form 1,1,1,2,3-pentafluoropropane. 
     
     
         15 . The method of  claim 13  wherein steps (b) and (c) are performed concurrently in the dehydrofluorination reactor, and said product stream further comprises said 1,1,1,2,3-pentafluoropropene. 
     
     
         16 . The method of  claim 15  wherein said product stream is separated into a final product stream rich in said 1,1,1,2-tetrafluoropropene and a product recycle stream rich in said 1,1,1,2,3-pentafluoropropene, and introducing said product recycle stream into the hydrogenation reactor, wherein at least a portion of said 1,1,1,2,3-pentafluoropropene is hydrogenated to form a portion of said intermediate stream. 
     
     
         17 . The method of  claim 16  wherein said intermediate stream is separated into an intermediate recycle stream rich in 1,1,1,2,3,3-hexafluoropropane 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. 
     
     
         18 . A system for producing at least one fluorinated olefin comprising:
 a. a hydrogenation reactor;   b. a starting material feed stream fluidly connected to said hydrogenation reactor, wherein said starting material feed stream comprises hexafluoropropylene;   c. one or more intermediate streams fluidly connected to said hydrogenation reactor;   d. a first separator fluidly connected to said one or more intermediate streams;   e. one or more post separator streams fluidly connected to said first separator;   f. optionally, a first recycle stream fluidly connected to said first separator and said hydrogenation reactor;   g. a dehydrohalogenation reactor fluidly connected to at least one of said post separator streams;   h. a product stream fluidly connected to said dehydrohalogenation reactor;   i. a second separator fluidly connected to said product stream;   j. a second recycle stream fluidly connected to said second separator and said hydrogenation reactor; and   k. a final product stream fluidly connected to said second separator, wherein said final product stream is rich in 1,1,1,2-tetrafluoropropene or 1,1,1,2,3-pentafluoropropene.   
     
     
         19 . The system of  claim 18  wherein said final product stream is rich in 1,1,1,2-tetrafluoropropene and said second recycle stream is rich in said 1,1,1,2,3-pentafluoropropene.