Improved process for preparing hydrazine hydrate with pyrazoline recycling

Patent metadata

Field	Value
Publication number	US-2022227627-A1
Application number	US-202017611443-A
Country	US
Kind code	A1
Filing date	May 12, 2020
Priority date	May 16, 2019
Publication date	Jul 21, 2022
Grant date	—

Abstract

The present invention relates to an improved process for preparing hydrazine hydrate from the azine of methyl ethyl ketone obtained from methyl ethyl ketone by oxidizing ammonia with hydrogen peroxide in the presence of an activator, characterized in that it comprises a step of recycling the pyrazoline-class heterocycles purge.

First claim

1 . A process for preparing hydrazine hydrate, comprising the following steps:
(a) reacting ammonia, hydrogen peroxide and methyl ethyl ketone in the presence of a solution comprising at least one activator to form an azine; (b) treating the reaction mixture from step (a) to isolate:
the aqueous phase comprising the activator(s); and
the organic phase comprising the resulting azine and optionally the unreacted methyl ethyl ketone;
(c) optionally recycling the aqueous phase to step (a) after optional treatment; (d) washing the organic phase; (e) distilling the washed organic phase to recover the azine; (f) hydrolyzing the azine to give hydrazine hydrate and regenerate methyl ethyl ketone, with pyrazoline-class heterocycles being purged; (g) optionally recycling the methyl ethyl ketone obtained in step (f) to step (a); and (h) recycling the pyrazoline-class heterocycles purge obtained in step (f) to one at least of steps (a), (b), (c), (d) or (g).

2 . The process as claimed in claim 1 , wherein the pyrazoline-class heterocycles purge obtained in step (f) is recycled to one at least of steps (c), (d) or (g).

3 . The process as claimed in claim 1 , wherein the pyrazoline-class heterocycles purge obtained in step (f) is recycled to the organic phase washing step (d).

4 . The process as claimed in claim 3 , wherein the pyrazoline-class heterocycles purge is sufficient to perform said organic phase washing, without addition of water.

5 . The process as claimed in claim 1 , wherein the pyrazoline-class heterocycles purge is carried out by withdrawal.

6 . The process as claimed in claim 1 , wherein the recycling step (h) is carried out continuously.

7 . The process as claimed in claim 1 , wherein the pyrazoline-class heterocycles are 3,5-diethyl-5-methylpyrazoline and 3,4,5-trimethyl-5-ethylpyrazoline.

8 . The process as claimed in claim 1 , wherein the azine hydrolysis and methyl ethyl ketone regeneration step (f) is performed in a packed or tray distillation column.

9 . The process as claimed in claim 8 , wherein the amount of pyrazoline-class heterocycles is not more than 5% by weight relative to the total weight of the liquid phase on the trays of the column or in the parts of the hydrolysis column at which said amount is at its maximum.

10 . The process as claimed in claim 1 , wherein said activator is acetamide.

Assignees

• Arkema France

Inventors

• Sage Jean-Marc

Classifications

• C01B21/16 Primary

  Hydrazine; Salts thereof · CPC title

• C07C45/42

  by hydrolysis · CPC title

• Y02P20/10

  Process efficiency · CPC title