Process for producing 2,3,3,3-tetrafluoropropene
View Patent ↗The present invention relates, in part, to the discovery that the presence of HF in a HCFC-244bb feedstream in a reaction for the preparation of HFO-1234yf results in selectivity changeover from HFO-1234yf to HCFO-1233xf. By substantially removing HF, it is shown that the selectivity to HFO-1234yf via dehydrochlorination of HCFC-244bb is improved.
1. A method for enhancing the selectivity of 2-chloro-1,1,1,2-tetrafluoropropane to 2,3,3,3-tetrafluoropropene in a dehydrochlorination reaction which comprises:
contacting a starting composition comprising 2-chloro-1,1,1,2-tetrahydrofluoropropane with a dehydrochlorination catalyst in a dehydrochlorination reactor that is substantially free of HF such that the amount of HF to the reactor is less than 5000 ppm to produce a final composition comprising 2,3,3,3-tetrafluoropropene.
2. The method of claim 1 , wherein the level of HF within the reactor is less than 500 ppm.
3. The method of claim 1 , wherein the level of HF within the reactor is less than 50 ppm.
4. The method of claim 1 , wherein reducing the HF level of the composition comprises the distilling of the HF, passing the composition through a scrubber, or passing the composition over a solid sorbent.
5. The method of claim 4 , wherein the solid sorbent is selected from the group consisting of alumina, calcium carbonate, sodium carbonate, and sodium aluminate.
6. The process according to claim 1 wherein the dehydrochlorination catalyst is a metal alloy or zero-valent metal.
7. The process according to claim 6 wherein the dehydrochlorination catalyst is Pt, Pd, Rh, Fe, Co, Ni, Cu, Mo, Mn, stainless steel or austenitic-nickel based alloy.
8. The process according to claim 1 conducted at a temperature ranging from about 200° C. to about 800° C.
9. The process according to claim 8 conducted at a temperature ranging from about 300° C. to about 600° C.
10. The process according to claim 9 conducted at temperature ranging from about 400° C. to about 500° C.
11. The process according to claim 1 conducted at a pressure ranging from about 0 to about 300 psig.
12. The process according to claim 11 conducted art a pressure ranging from about 10 to about 100 psig.
13. The process according to claim 12 conducted at a pressure ranging from about 20 to about 70 psig.
14. A process for preparing 2,3,3,3-tetrafluoropropene in a metal dehydrochlorination reactor, said process comprising contacting a starting composition comprising 2-chloro-1,1,1,2-tetrafluoropropane substantially free of HF with a dehydrochlorination catalyst in said reactor, to minimize the tendency of the metal in the reactor to form a hydrofluorination catalyst that catalyzes the formation of 2-chloro-3,3,3-trifluoropropene, said HF being present in amount of less than 5000 ppm.
15. The process according to claim 14 , wherein the HF is present in less than 500 ppm.
16. The process according to claim 15 , wherein the HF is present in less than 50 ppm.
17. The process according to claim 14 wherein the dehydrochlorination catalyst is a metal alloy or zero-valent metal.
18. The process according to claim 17 wherein the dehydrochlorination catalyst is Pt, Pd, Rh, Fe, Co, Ni, Cu, Mo, Mn, stainless steel or austenitic-nickel based alloy.
19. The process according to claim 14 conducted at a temperature ranging from about 200° C. to about 800° C.
20. The process according to claim 19 conducted at a temperature ranging from about 300° C. to about 600° C.
21. The process according to claim 20 conducted at temperature ranging from about 400° C. to about 500° C.
22. The process according to claim 14 conducted at a pressure ranging from about 0 to about 300 psig.
23. The process according to claim 22 conducted at a pressure ranging from about 10 to about 100 psig.
24. The process according to claim 23 conducted at a pressure ranging from about 20 to about 70 psig.