US3607041A

US3607041A - Hydrazine

Info

Publication number: US3607041A
Application number: US765598A
Authority: US
Inventors: Stephen Robert Mercer Ellis; Brian John Needham
Original assignee: Fisons Industrial Chemicals Ltd
Current assignee: Fisons Industrial Chemicals Ltd
Priority date: 1967-10-12
Filing date: 1968-10-07
Publication date: 1971-09-21
Anticipated expiration: 1988-09-21
Also published as: GB1211547A; JPS4948640B1; DE1801912A1

Abstract

HYDRAZINE IS PREPARED FROM KETAZINES BY FEEDING A KETAZINE AND WATER TO A FRACTIONATING COLUMN WHEREIN THE KETAZINE IS MISCIBLE WITH WATER TO ONLY A LIMITED EXTENT. THE COLUMN IS OPERATED AT ELEVATED TEMPERATURE AND AT SUPERATMOSPHERIC PRESSURE AND HAS A ZONE IN THE VICINITY OF THE POINT OF INTRODUCTION OF THE MATERIALS WHEREIN THE RESIDENCE TIME IS RELATIVELY LARGE IN THIS ZONE AS COMPARED WITH THE REMAINDER OF THE COLUMN. AN AQUEOUS SOLUTION OF HYDRAZINE IS REMOVED AS BOTTOMS.

Description

United States Patent [56] References Cited UNITED STATES PATENTS 3,189,411 6/1965 Kohnen et a1 23/190 3,151,046 9/1964 Larson 202/158 Primary Examiner-Earl C. Thomas Assistant Examiner-Hoke S. Miller Attorney-Richard P. Crowley ABSTRACT: Hydrazine is prepared from ketazines by feeding a ketazine and water to a fractionating column wherein the ketazine is miscible with water to only a limited extent. The column is operated at elevated temperature and at superatmospheric pressure and has a zone in the vicinity of the point of introduction of the materials wherein the residence time is relatively large in this zone as compared with the remainder of the column. An aqueous solution of hydrazine is removed as bottoms.

PATENTED SEP21 IHYI INVENTORS STEPILBQ ROBERT MERCER ELLIS BRIAN JOHN NEEDHAM 1 ATTORNEY HYDRAZHNE The present invention relates to a process for preparing hydrazine from ketazines which are miscible with water only to a limited extent.

it is possible to form hydrazine by hydrolysis of water-soluble acetone azine in aqueous solution at elevated temperature and ressures, the hydrolysis being conveniently effected on the trays of a fractioning column operated under pressure. Upon hydrolysis of ketazines, hydrazone and ketone are formed and hydrazine may be obtained by disproportionation of the hydrazone to hydrazine and the azine. The hydrolysis step involves handling a two-phase liquid system where the ketazines are miscible with water only to a limited extent and surprisingly it has been found possible to handle such a twophase liquid system if the residence time of the mixture which is fed to the column is relatively long in a zone in the vicinity of the point of feed of the mixture to the column prepared with the residence times in similar lengths of other parts of the column.

Accordingly the present invention is for a process for preparing hydrazine which comprises feeding a ketazine which is miscible with water only to a limited extent, such as methyl ethyl ketazine, and water to a distillation column operated at an elevated temperature and at a superatmospheric pressure, a zone in the vicinity of the point of feed of the ketazine to the column having plates so designed that the residence time thereof is relatively long compared with the re sidence times of plates or packing equivalent thereto outside this zone in other parts of the column and recovering an aqueous solution of hydrazine as bottoms.

Preferably 1 to 4 parts by weight of water are fed to the column for every part by weight of ketazine.

In the zone in the vicinity of the ketazine feed, the ketazine is hydrolized to hydrazone, the presence of which increases the solubility of the ketazine thereby increasing its rate of hydrolysis. Below this zone hydrazone is disproportionated to azine and hydrazine, the azine being returned to the zone in the vicinity of the ketazine/water feed and hydrazine being recovered from the sump. In the zone above the ketazine/water feed zone unhydrolysed ketazine is condensed and returned to the ketazine/water feed zone and ketone/water is distilled off.

The present invention is also for a fractionating column wherein trays in the vicinity of the feed inlet(s) to the column, have a greater residence time than each of the trays or packing equivalent thereto in the remainder of the column.

It is preferred to operate the column at a temperature in the range 150 to 200 C. and at a pressure in the range 2 to 25 atmospheres above atmospheric pressure.

in operating the process of the present invention the ketazine is converted to the ketone and hydrazine the ketone being removed as distillate and hydrazine being removed as bottoms.

The ketazine and water may be fed to the distillation column at the same point or at different points. If the feeds are at different points the ketazine is preferably fed at a point below that at which the water is fed to the column. 1f the ketazine and water are fed at the same point they may be mixed before feeding. Preferably the feeds are heated before being fed to the column for example to a temperature in the range 60 to 160 C.

Suitably the zone in the vicinity of the point of feed of the ketazine to the column is equivalent to 2-7 theoretical trays, preferably 3-5 theoretical plates, the zone below the ketazine feed zone is equivalent to 3-15 theoretical plates, preferably 5-10 theoretical plates, and the zone above the ketazine feed zone is equivalent to 3-15 theoretical plates preferably 5-12 theoretical plates. Desirably the zone in the vicinity of the point of feed of the ketazine to the column contains 2-6 actual high-residence-type trays having an overall residence time of 3-15 minutes. Preferably the zone in the vicinity of the point of feed of ketazine contains two or three highresidence-type trays immediately below the point of feed and one or two highresidence-type trays immediately above the point of feed.

residence time. Ketazine and water are fed to column 1 through line 4 and ketone and water are removed through line 5. l-lydrazine and water are removed from the sump through line 6.

The following example is given to illustrate the process of the present invention.

EXAMPLE A column 9 inches in diameter was packed with knitmesh except for the middle section which consisted of three high-residence-type trays. The liquid holdup of each of these high 'high-residence-type trays was approximately 250 cubic inches.

The column was operated at a reflux ratio of 4:1 a pressure of pounds per square inch gauge and a sump temperature of 180 C. Methyl ethyl ketone azine (43.5 pounds per hour) and water (1 11 pounds per hour) were heated to C. and fed to the middle plate of the hydrolysis section. Methyl ethyl ketone (44.1 pounds per hour), water (14.9 pounds per hour) and methyl ethyl ketone azine (0.6 pounds per hour) were removed from the top of the column whilst hydrazine (9.80 pounds per hour), water (85.4 pounds per hour) and methyl ethyl ketone (0.11 pounds per hour) were continuously withdrawn from the sump.

We claim:

11. A process for the preparation of hydrazine by the fractional distillation of a ketazine at an elevated temperature and at a superatmospheric pressure sufficient to hydrolyze the ketazine in a hydrolyzing zone, which process comprises;

a. feeding water and the ketazine which forms a two-phase liquid system into a hydrolyzing zone, the hydrolyzing zone characterized in that the residence time of the ketazine and water is relatively long compared with the residence times outside of the hydrolyzing zone;

b. hydrolyzing the ketazine in the hydrolyzing zone to hydrazone, the presence of which hydrazone increases the solubility of the ketazine in said zone, thereby increas ing its rate of hydrolysis in the hydrolyzing zone;

0. fractionating the hydrazone so formed in a zone below the hydrolyzing zone to azine and hydrazine; and

d. recovering an aqueous solution of hydrazine.

2. The process as claimed in claim 11 which includes operating at a temperature in the range 150 to 200 C.

3. The process as claimed in claim 1 which includes maintaining a pressure in the range of 2 to 25 atmospheres.

4. The process as claimed in claim 1 which includes feeding the ketazine and water at separate points, the ketazine feed point being below the water feed point.

5. The process as claimed in claim 1 which includes mixing the water and the ketazine before being fed to the hydrolyzing zone.

6. The process as claimed in claim 1 which includes heating the water and the ketazine before being fed to the hydrolyzing zone.

7. The process as claimed in claim 6 which includes heating the water and the ketazine to a temperature in the range 60 to C.

8. The process as claimed in claim 1 wherein the zone in the vicinity of the point of feed of the ketazine is equivalent to about 2-7 theoretical plates and the zones above and below the ketazine feed zone are each equivalent to about 3-15 theoretical plates.

9. The process as claimed in claim 1 wherein the zone at the point of feed of the ketazine contains 2-3 high-residence-type trays immediately below the point of feed and 1-2 high-residence-type trays immediately above the point of feed.

10. The process as claimed in claim 1 which includes providing a relatively long residence time in the hydrolyzing zone for the feed stream by a plurality of distillation trays in the hydrolyzing zone with relatively high weirs in respect to distillationtrays outside of the zone having relatively low want.

11. The process as claimed in claim 1 which includes providing a plurality of high liquid-residence fractionating trays in the hydrolyzing zone and packing material in the other zones.

12. The process as claimed in claim 1 which includes feeding about 1 to 4 parts by weight of water for every part by weight of the ketazine.

13. The process as claimed in claim 1 which includes recovering a ketone, and recovering the unhydrolyzed ketazine from the zone above the hydrolyzing zone, condensing the ketazine so recovered and returning the ketazine to the hydrolyzing zone.

14. A process for the preparation of hydrazine by the fractional distillation of methylethyl ketazine in a distillation column in a hydrolyzing zone, which process comprises:

a. feeding methylethyl ketazine and water in a ratio of about 1 to ,4 parts of water for every part of methylethyl ketazine into a hydrolyzing zone located intermediate in a distillation column, the hydrolyzing zone so designed that the residence time of the ketazine is relatively long compared with the residence times of the ketazine above and below the zone, the water and ketazine heated to a temperature in the range of about 60 to 160 C., the process operated at a temperature in the range of to 200 C., and a pressure of about 2 to 25 atmospheres;

b. hydrolyzing the methylethyl ketazine in the hydrolyzing zone to methylethyl hydrazone, the presence of which hydrazone increases the solubility of the methylethyl ketazine in the zone;

c. fractionating the methylethyl hydrazone to the azine and hydrazine;

d. recovering an aqueous solution of hydrazine; and

e. distilling off and recovering methylethyl ketone.

15. The process as claimed in claim 14 which includes feed ing thereof the methylethyl ketazine and water into the hydrolyzingzone at separate points, the methylethyl ketazine feed point being below the water feed point.

16. The process as claimed in claim 14 which includes mixing the water and methylethyl ketazine before being fed to the hydrolyzing zone.

17. The process as claimed in claim 14 which includes providing a plurality of high-liquid-residence fractionating trays in the hydrolyzing zone and packing material in the other zones.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 s 607 s 04] Dated September 2] 9 1 97] Inventor) Stephen Robert Mercer E1 1 is and Brian John Needham It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, identification of the serial number --App1n. No. 765,598-- has been omitted; line 8, "Laughborough" shouid read --Loughborough--.

Signed and sealed this lLpth day of March 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

2. The process as claimed in claim 1 which includes operating at a temperature in The range 150* to 200* C.
3. The process as claimed in claim 1 which includes maintaining a pressure in the range of 2 to 25 atmospheres.
4. The process as claimed in claim 1 which includes feeding the ketazine and water at separate points, the ketazine feed point being below the water feed point.
5. The process as claimed in claim 1 which includes mixing the water and the ketazine before being fed to the hydrolyzing zone.
6. The process as claimed in claim 1 which includes heating the water and the ketazine before being fed to the hydrolyzing zone.
7. The process as claimed in claim 6 which includes heating the water and the ketazine to a temperature in the range 60* to 160* C.
8. The process as claimed in claim 1 wherein the zone in the vicinity of the point of feed of the ketazine is equivalent to about 2-7 theoretical plates and the zones above and below the ketazine feed zone are each equivalent to about 3-15 theoretical plates.
9. The process as claimed in claim 1 wherein the zone at the point of feed of the ketazine contains 2-3 high-residence-type trays immediately below the point of feed and 1-2 high-residence-type trays immediately above the point of feed.
10. The process as claimed in claim 1 which includes providing a relatively long residence time in the hydrolyzing zone for the feed stream by a plurality of distillation trays in the hydrolyzing zone with relatively high weirs in respect to distillation trays outside of the zone having relatively low weirs.
11. The process as claimed in claim 1 which includes providing a plurality of high liquid-residence fractionating trays in the hydrolyzing zone and packing material in the other zones.
12. The process as claimed in claim 1 which includes feeding about 1 to 4 parts by weight of water for every part by weight of the ketazine.
13. The process as claimed in claim 1 which includes recovering a ketone, and recovering the unhydrolyzed ketazine from the zone above the hydrolyzing zone, condensing the ketazine so recovered and returning the ketazine to the hydrolyzing zone.
14. A process for the preparation of hydrazine by the fractional distillation of methylethyl ketazine in a distillation column in a hydrolyzing zone, which process comprises: a. feeding methylethyl ketazine and water in a ratio of about 1 to 4 parts of water for every part of methylethyl ketazine into a hydrolyzing zone located intermediate in a distillation column, the hydrolyzing zone so designed that the residence time of the ketazine is relatively long compared with the residence times of the ketazine above and below the zone, the water and ketazine heated to a temperature in the range of about 60 to 160* C., the process operated at a temperature in the range of 150* to 200* C., and a pressure of about 2 to 25 atmospheres; b. hydrolyzing the methylethyl ketazine in the hydrolyzing zone to methylethyl hydrazone, the presence of which hydrazone increases the solubility of the methylethyl ketazine in the zone; c. fractionating the methylethyl hydrazone to the azine and hydrazine; d. recovering an aqueous solution of hydrazine; and e. distilling off and recovering methylethyl ketone.
15. The process as claimed in claim 14 which includes feeding thereof the methylethyl ketazine and water into the hydrolyzing zone at separate points, the methylethyl ketazine feed point being below the water feed point.
16. The process as claimed in claim 14 which includes mixing the water and methylethyl ketazine before being fed to the hydrolyzing zone.
17. The process as claimed in claim 14 which includes providing a plurality of high-liquid-residence fractionating trays in the hydrolyzing zone and packing material in the other zones.