Method of hydrodechlorination to produce dihydrofluorinated olefins

Abstract

Disclosed herein is a process for the preparation of fluorine-containing olefins comprising contacting a chlorofluoroalkene with hydrogen in the presence of a catalyst at a temperature sufficient to cause replacement of the chlorine substituents with hydrogen. Also disclosed is a catalyst composition for the hydrodechlorination of chlorofluoroalkenes comprising copper metal deposited on a support.

What is claimed is: 
     
       1. A process for the preparation of fluorine-containing olefins comprising contacting a chlorofluoroalkene having the formula R f CCl═CClR f  wherein each R f  is a perfluoroalkyl group independently selected from the group consisting of CF 3 , C 2 F 5 , n-C 3 F 7 , i-C 3 F 7 , n-C 4 F 9 , i-C 4 F 9  and t-C 4 F 9 , and wherein one of the R f  groups may be F with hydrogen in the presence of a catalyst at a temperature sufficient to cause replacement of the chlorine substituents of the chlorofluoroalkene with hydrogen to produce a product mixture comprising a fluorine-containing olefin having the formula E- or Z—R 1 CH═CHR 2 , and optionally, a chlorofluoroolefin having the formula E- or Z—R 1 CCl═CHR 2 , wherein each of R 1  and R 2  are, perfluoroalkyl groups independently selected from the group consisting of CF 3 , C 2 F 5 , n-C 3 F 7 , i-C 3 F 7 , n-C 4 F 9 , i-C 4 F 9  and t-C 4 F 9 , and wherein R 2  may be F, wherein the catalyst selected from the group consisting of copper on carbon, copper on calcium fluoride, palladium on barium sulfate, palladium/barium chloride on alumina, Lindlar catalyst (palladium on CaCO 3 , poisoned with lead), palladium on calcium fluoride poisoned with lead, copper and nickel on carbon, nickel on carbon, nickel on calcium fluoride, copper/nickel/chromium on calcium fluoride and unsupported alloys of copper and nickel. 
     
     
       2. The process of  claim 1  wherein said catalyst is selected from the group consisting of copper on carbon, copper on calcium fluoride, palladium on barium sulfate, palladium/barium chloride on alumina, Lindlar catalyst (palladium on CaCO 3 , poisoned with lead), palladium on calcium fluoride poisoned with lead, copper and nickel on carbon, nickel on carbon, nickel on calcium fluoride, copper/nickel/chromium on calcium fluoride and unsupported alloys of copper and nickel. 
     
     
       3. The process of  claim 1  wherein the said catalyst is selected from the group consisting of copper on carbon, copper on calcium fluoride, copper and nickel on carbon, nickel on carbon, copper/nickel/chromium on calcium fluoride and unsupported alloys of copper and nickel. 
     
     
       4. The process of  claim 1  wherein each R f  is CF 3 . 
     
     
       5. The process of  claim 1  wherein each R f  is n-C 3 F 7 . 
     
     
       6. The process of  claim 1  wherein each of R 1  and R 2  is CF 3 . 
     
     
       7. The process of  claim 1  wherein each of R 1  and R 2  is n-C 3 F 7 . 
     
     
       8. The process of  claim 1  wherein the process is conducted at a temperature of from about 200° C. to about 450° C. 
     
     
       9. The process of  claim 1  wherein the ratio of hydrogen to chlorofluoroalkene is from about 1:1 to about 10:1. 
     
     
       10. The process of  claim 1  wherein the ratio of hydrogen to chlorofluoroalkene is from about 1:1 to about 7.5:1. 
     
     
       11. The process of  claim 3  wherein the molar ratio of copper:nickel:chromium in the copper/nickel/chromium on calcium fluoride catalyst is about 0 to about 1 copper:about 0.5 to about 3.0 nickel, and about 0 to about 2 chromium. 
     
     
       12. The process of  claim 3  wherein the amount of copper on carbon or calcium fluoride is from about 1% to about 25% by weight. 
     
     
       13. The process of  claim 3  wherein the amount of copper on carbon or calcium fluoride is from about 5% to about 25% by weight. 
     
     
       14. The process of claim 1, wherein each R f  is CF 3  and the product mixture further comprises E and/or Z-2-chloro-1,1,1,4,4,4-hexafluoro-2-butene. 
     
     
       15. The process of claim 1, wherein each R f  is CF 3  and the product mixture further comprises Z-2-chloro-1,1,1,4,4,4-hexafluoro-2-butene.