Azeotrope compositions comprising 2,3,3,3-tetrafluoropropene and hydrogen fluoride and uses thereof
View Patent ↗Disclosed herein are azeotrope or near-azeotrope compositions comprising 2,3,3,3-tetrafluoropropene (HFC-1234yf) and hydrogen fluoride (HF). These compositions are useful in processes to produce and purify HFC-1234yf. Additionally, disclosed herein are processes for the manufacture of HFC-1234yf.
1. An azeotrope or near-azeotrope composition comprising from about 64.6 mole percent to about 92.4 mole percent HFC-1234yf and hydrogen fluoride wherein said composition is characterized by a difference between dew point pressure and bubble point pressure that is less than or equal to 3%, based upon bubble point pressure.
2. The azeotrope or near-azeotrope composition of claim 1 comprising from about 64.6 mole percent to about 92.4 mole percent HFC-1234yf and from about 35.4 mole percent to about 7.6 mole percent hydrogen fluoride.
3. The azeotrope or near-azeotrope composition of claim 1 wherein said composition consists essentially of from about 64.6 mole percent to about 92.4 mole percent HFC-1234yf and from about 35.4 mole percent to about 7.6 mole percent hydrogen fluoride, wherein the vapor pressure is from about 23.2 psi (160 kPa) to about 453 psi (3123 kPa) at a temperature of from about −20° C. to about 80° C.
4. The azeotrope composition of claim 1 wherein said composition consists essentially of from about 68.9 mole percent to about 80.7 mole percent HFC-1234yf and from about 31.1 mole percent to about 19.3 mole percent hydrogen fluoride, wherein the vapor pressure is from about 23.2 psi (160 kPa) to about 453 psi (3123 kPa) at a temperature of from about −20° C. to about 80° C.
5. A process for the separation of HFC-1234yf from HFC-245cb comprising:
a) forming a mixture of HFC-1234yf, HFC-245cb, and hydrogen fluoride; and
b) subjecting said mixture to a distillation step from which is formed a column distillate composition comprising an azeotrope or near-azeotrope composition of hydrogen fluoride and HFC-1234yf essentially free of HFC-245cb, wherein said column distillate composition is characterized by a difference between dew point pressure and bubble point pressure that is less than or equal to 3%, based upon bubble point pressure.
6. The process of claim 5 further comprising forming a column-bottoms composition comprising HFC-245cb.
7. The process of claim 6 wherein said column-bottoms composition comprises HFC-245cb essentially free of hydrogen fluoride.
8. The process of claim 5 wherein said mixture of HFC-1234yf, HFC-245cb, and hydrogen fluoride comprises equimolar quantities of each component.
9. The process of claim 5 wherein said mixture of HFC-1234yf, HFC-245cb, and hydrogen fluoride comprises excess HFC-1234yf.
10. A process for the separation of HFC-1234yf from a mixture comprising an azeotrope or near-azeotrope composition of HFC-1234yf and hydrogen fluoride wherein said composition is characterized by a difference between dew point pressure and bubble point pressure that is less than or equal to 3%, based upon bubble point pressure, said process comprising:
a) subjecting said mixture to a first distillation step in which a composition enriched in either (i) hydrogen fluoride or (ii) HFC-1234yf is removed as a first distillate composition with a first bottoms composition being enriched in the other of said components (i) or (ii); and
b) subjecting said first distillate composition to a second distillation step conducted at a different pressure in which the component enriched as first bottoms composition in (a) is removed in a second distillate composition with a second bottoms composition enriched in the same component which was enriched in the first distillate composition
11. The process of claim 10 wherein said first bottoms composition or said second bottoms composition comprises HFC-1234yf essentially free of hydrogen fluoride.
12. The process of claim 10 wherein said second bottoms composition comprises hydrogen fluoride essentially free of HFC-1234yf
13. The process of claim 10 wherein said first distillation step is carried out at a pressure greater than the pressure of the second distillation step.
14. The process of claim 10 wherein said mixture consists essentially of HFC-1234yf in combination with an effective amount of hydrogen fluoride to form an azeotrope or near-azeotrope composition with hydrogen fluoride, said azeotrope or near-azeotrope composition containing from about 64.6 mole percent to about 92.4 mole percent HFC-1234yf.
15. A process for the purification of HFC-1234yf from a mixture of HFC-1234yf, HFC-245cb, and hydrogen fluoride, said process comprising:
a) subjecting said mixture to a first distillation step to form a first distillate comprising an azeotrope or near-azeotrope composition containing HFC-1234yf and hydrogen fluoride, wherein said composition is characterized by a difference between dew point pressure and bubble point pressure that is less than or equal to 3%, based upon bubble point pressure, and a first bottoms comprising HFC-245cb;
b) subjecting said first distillate to a second distillation step from which a composition enriched in either (i) hydrogen fluoride or (ii) HFC-1234yf is removed as a second distillate composition with a second bottoms composition being enriched in the other of said components (i) or (ii); and
c) subjecting said second distillate composition to a third distillation step conducted at a different pressure than the second distillation step in which the component enriched in the second bottoms composition in (b) is removed as a third distillate composition with a third bottoms composition enriched in the same component that was enriched in the second distillate composition.
16. A process to produce HFC-1234yf comprising:
a) feeding HFC-245cb to a reaction zone for dehydrofluorination to form a reaction product composition comprising HFC-1234yf, unreacted HFC-245cb and hydrogen fluoride;
b) subjecting said reaction product composition to a first distillation step to form a first distillate composition comprising an azeotrope or near-azeotrope composition containing HFC-1234yf and hydrogen fluoride, wherein said first distillate composition is characterized by a difference between dew point pressure and bubble point pressure that is less than or equal to 3%, based upon bubble point pressure, and a first bottoms composition comprising HFC-245cb;
c) subjecting said first distillate composition to a second distillation step from which a composition enriched in either (i) hydrogen fluoride or (ii) HFC-1234yf is removed as a second distillate composition with a second bottoms composition being enriched in the other of said components (i) or (ii); and
d) subjecting said second distillate composition to a third distillation step conducted at a different pressure than the second distillation step in which the component enriched in the second bottoms composition in (c) is removed as a third distillate composition with a third bottoms composition enriched in the same component that was enriched in the second distillate composition.
17. The process of claim 16 , further comprising recycling at least some portion of said first bottoms composition to said reaction zone.
18. The process of claim 16 , further comprising recycling at least some portion of said second bottoms composition or said third bottoms composition to said reaction zone.
19. The process of claim 16 , further comprising recovering at least some portion of said second bottoms composition or said third bottoms composition as HFC-1234yf essentially free of HFC-245cb and hydrogen fluoride.
20. The process of claim 16 , further comprising recycling at least some portion of said second bottoms composition or said third bottoms composition to said first distillation step.