Process for the production of anhydrous hydrazine and device for its implementation
View Patent ↗The present invention relates to a process for preparing anhydrous hydrazine. The process can include distilling an unconcentrated aqueous hydrazine solution into a starting binary solution, distilling the starting binary solution at a pressure where a concentration of hydrazine in the binary solution is greater than a concentration of an azeotrope at the distillation pressure, and recovering the anhydrous hydrazine.
1. A process for the preparation of anhydrous hydrazine comprising:
(i) first distilling an unconcentrated aqueous hydrazine solution to provide a starting binary solution with increased hydrazine concentration;
(ii) second distilling the starting binary solution at a distillation pressure between 50-400 mbar such that the concentration of hydrazine in a hydrazine-water azeotrope at the distillation pressure is less than the concentration of hydrazine in the binary solution from (i), wherein the second distilling is conducted with a top temperature corresponding to the boiling point of anhydrous hydrazine at the distillation pressure and a bottom temperature corresponding to the boiling point of the hydrazine-water azeotrope at the distillation pressure; and
(iii) recovering the anhydrous hydrazine.
2. A process according to claim 1 , wherein the concentration of hydrazine in the starting binary solution from the first distilling is at least 68%, at 1 bar.
3. A process according to claim 1 , wherein the second distilling is carried out at a distillation pressure of 50-150 mbar.
4. A process according to claim 1 , wherein the second distilling provides a bottom product of a hydrazine-water azeotrope and this azeotrope is recovered and recycled into the unconcentrated aqueous hydrazine solution used in the first distilling.
5. A process according to claim 1 , wherein the first distilling is at a distillation pressure greater than 400 mbar.
6. A process according to claim 1 , wherein the anhydrous hydrazine is recovered at the top of a column for the second distilling.
7. A process according to claim 1 , wherein the first and second distillings are conducted in the absence of a third substance which alters the hydrazine-water azeotrope concentrations.
8. A process for the preparation of anhydrous hydrazine comprising:
(i) first distilling an unconcentrated aqueous hydrazine solution to provide a starting binary solution with a hydrazine concentration of less than 70%, at 1 bar,
(ii) second distilling the starting binary solution at a distillation pressure between 5-400 mbar such that the concentration of hydrazine in a hydrazine-water azeotrope at the distillation pressure is less than the concentration of hydrazine in the binary solution from (i), wherein the second distilling is conducted with a top temperature corresponding to the boiling point of anhydrous hydrazine at the distillation pressure and a bottom temperature corresponding to the boiling point of the hydrazine-water azeotrope at the distillation pressure; and
(iii) recovering the anhydrous hydrazine.
9. A process according to claim 8 , wherein the concentration of hydrazine in the starting binary solution is at least 68% but less than 70%, at 1 bar.
10. A process according to claim 8 , wherein the second distilling is carried out at a distillation pressure of 50-150 mbar.
11. A process according to claim 8 , wherein the second distilling provides a bottom product of a hydrazine-water azeotrope and this azeotrope is recovered and recycled into the unconcentrated aqueous hydrazine solution used in the first distilling.
12. A process according to claim 8 , wherein the anhydrous hydrazine is recovered at the top of a column for the second distilling.
13. A process according to claim 8 , wherein the first distilling is at a distillation pressure greater than 400 mbar.
14. A process according to claim 8 , wherein the first and second distillings are conducted in the absence of a third substance which alters the hydrazine-water azeotrope concentrations.
15. A process for the preparation of anhydrous hydrazine comprising:
(i) first distilling an unconcentrated aqueous hydrazine solution to provide a starting binary solution with a hydrazine concentration of at least 68% and less than 70%, at 1 bar;
(ii) second distilling the starting binary solution at a distillation pressure between 50-400 mbar such that the concentration of hydrazine in a hydrazine-water azeotrope at the distillation pressure is less than the concentration of hydrazine in the binary solution from (i), wherein the second distilling is conducted with a top temperature corresponding to the boiling point of anhydrous hydrazine at the distillation pressure and a bottom temperature corresponding to the boiling point of the hydrazine-water azeotrope at the distillation pressure; and
(iii) recovering the anhydrous hydrazine.
16. The process according to claim 15 , wherein the second distilling provides a bottom product of a hydrazine-water azeotrope and this azeotrope is recovered and recycled into the unconcentrated aqueous hydrazine solution used in the first distilling.
17. A process according to claim 15 , wherein the anhydrous hydrazine is recovered at the top of a column for the second distilling.
18. A process according to claim 15 , wherein the first distilling is at a distillation pressure greater than 400 mbar.
19. A process according to claim 15 , wherein the first and second distillings are conducted in the absence of a third substance which alters the hydrazine-water azeotrope concentrations.