DE1020007B - Process for concentrating aqueous hydrazine - Google Patents

Description

GERMAN

The invention relates to a method for concentrating aqueous hydrazine and is an improvement on the in of the main patent application O 2192 IV a / 12 i.

The concentration of aqueous hydrazine is carried out here by a process in which hydrazine with a as Dehydrating agent acting oxide or hydroxide in an amount of at least 1 mole of the oxide or Hydroxyds per mole of water to be removed in the presence of saturated aliphatic hydrocarbons or Naphthenes is distilled and in the distillate the hydrazine is mechanically removed from the hydrocarbons or naphthenes is separated.

The main patent application describes that saturated hydrocarbons or naphthenes boiling between 90 and 150 ° C. are particularly suitable for this purpose. It has now been found that hydrocarbons with a boiling point of up to 175 ° C. at atmospheric pressure can be used successfully even in smaller amounts without reaching a distillation temperature at atmospheric pressure at which there is a risk of hydrazine decomposition. Even if hydrocarbons boiling between 150 and 175 ^° C. are distilled over in a smaller amount due to their lower vapor pressure, this amount is sufficient to avoid violent decomposition of the hydrazine in the presence of an electric arc or the like. When the mixture is distilled, the distillate consists essentially of the anhydrous hydrazine and the hydrocarbons or naphthenes. Since the liquid hydrocarbons or naphthenes do not mix with the hydrazine, two layers form in the distillate, so that the hydrocarbon layer can simply be poured off and water-containing hydrazine can be used for further concentration.

It has been found that the hydrazine solution can be safely distilled at atmospheric pressure because the hydrazine passes in the presence of the hydrocarbon at a lower temperature and because the amount of the hydrocarbon evaporating with the hydrazine is sufficient to avoid violent decomposition of the hydrazine and thus the risk of explosion to reduce. For this purpose, all saturated aliphatic hydrocarbons or naphthenes which ^{boil between 150 and 175 °} C. at normal pressure can be used. Examples are: η-decane, 2-methylnonane, 2,7-dimethyloctane, 2,3,6-trimethylheptane, etc. Mixtures of these hydrocarbons can just as well be used. Finally, it is possible to use mixtures of such saturated hydrocarbons which are available on the market and which boil ^{between 150 and 175 ° C. at atmospheric pressure.}

It is also possible to use mixtures of saturated hydrocarbons obtained by fractionating raw mineral processes for concentration
aqueous hydrazine

Addition to patent application O2192IVa / 12i
(Interpretation document 1 016 687)

Applicant:

Olin Mathieson Chemical Corporation,
East Alton, 111. (V. St. A.)

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau,

and Dipl.-Ing. K. Grentzenberg, Munich 27,

Pienzenauerstr, 2, patent attorneys

Oscar J. Swenson and Don W. Ryker,

East Alton, 111. (V. St. Α.),
have been named as inventors

oils are obtained and boil ^{between 150 and 175 0 C.} These fractions can contain very small amounts of unsaturated aromatics, which are permitted in these amounts. In general, however, unsaturated aromatic hydrocarbons are unsuitable because they will react with the hydrazine. This reaction usually results in the hydrogenation of the aromatic hydrocarbon with a loss of hydrazine. If, for economic reasons, a saturated hydrocarbon is used which contains considerable amounts of unsaturated compounds and the yield of practically anhydrous hydrazine is not important, then, of course, contaminated saturated hydrocarbons can also be used.

Hydrocarbons boiling significantly above 175 ^° C. are unsuitable for the present purpose because their vapor pressure is too low and the amount transferred is too small to prevent the decomposition of the hydrazine. Of course, lesser amounts of such higher boiling hydrocarbons can be present in the hydrocarbon mixtures used here.

The amount of hydrocarbon carried over with the hydrazine will of course vary with the particular hydrocarbon used; however, the preferred ^{hydrocarbons boiling between 150 and 175 °} C. are transferred in such an amount that decomposition of the accompanying hydrazine is avoided. The following table shows the

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first column shows suitable hydrocarbons and their approximate boiling temperatures; the second column shows the mean boiling point of the mixture during the distillation of the hydrazine when a mixture of aqueous hydrazine, sodium hydroxide and the hydrocarbon is distilled at atmospheric pressure; the third column shows the minimum mole percent of the hydrocarbon in a mixture of hydrocarbon vapor and hydrazine vapor sufficient to prevent mass decomposition of the hydrazine; and in the fourth column, the mole percent hydrocarbon in the mixture of substantially anhydrous hydrazine and hydrocarbon vapors that actually migrate at atmospheric pressure. This results in z. B. that the minimum allowable dimension for dean is 9.6 ⁰ I ₀ ; As can be seen, the amount of decane actually transferred, namely 15.5%, is sufficient to prevent the decomposition of the hydrazine.

The amount of sodium hydroxide monohydrate removed from the system depends on the amount of water with the aqueous Hydrazine solution reaches the column. This sodium hydroxide monohydrate can turn into sodium hydroxide dewatered in order to then get back into the column and in this way close the circuit. The following example illustrates the invention.

Tabel

Boil Medium
Boil Hydrocarbon Coals temperature temperature
of Hydrazine hydrogen of
Coals Mixture Steam generator in the distillate water ⁰ C Permissible
Minimum Mole percent fabric Amount of C. Coals 25th 108 hydrogen 15.5 150.7 109.5 Mole percent n-nonane. 174.0 11.0 η dean .. 9.6

example

There were added 500 parts by weight of an aqueous 54.5 ° / ₀ hydrazine-containing solution in a suitable distillation apparatus with 523 parts by weight of 97 ° / ,, strength Natriumhydroxyds and 200 parts by weight of decane. The molar ratio of sodium hydroxide to water was about 1: 1. The mixture was then quickly heated to boiling temperature, approximately 108 ^° C., and the distillation was ^{carried out up to HO °} C., practically all of the hydrazine passing over into the distillate. A certain amount of the hydrocarbon remained in the column throughout the distillation. The practically anhydrous hydrazine was poured off from the hydrocarbon in the distillate. Get were 95 ° / ₀ of the original hydrazine in a concentration of 95.5% ·

Instead of using an excess of liquid carbon To enter column, as described in the example above, you can also get as much hydrocarbon vapor Bring it into the column so that self-decomposition of the hydrazine vapor is avoided. The application however, excess hydrocarbon is preferred. There should be a certain amount of the hydrocarbon be present in the column throughout the distillation.

This method of producing practically water-If an electric arc is produced by a vapor-free hydrazine from dilute aqueous hydrazine

Mixture of hydrazine and a 35 solution is safe and economical.

below the amount of hydrocarbons indicated in the table, column 3, was carried out a violent explosion. It was found that the ratio of hydrocarbon transited to practically anhydrous hydrazine during the distillation in all cases for each hydrocarbon approximately

remains constant.
Since the hydrocarbon, the hydrazine and the

Sodium hydroxide monohydrate are practically present in the column as separate liquid layers and since the hydrazine and hydrocarbon also separate in the distillate, the process is for one suitable for uninterrupted operation. For this you can z. B.

the dilute aqueous hydrazine, sodium hydroxide and hydrocarbon continuously to the column give while sodium hydroxide monohydrate continuously out of the column and the hydrocarbon and the hydrazine can also be obtained separately from the distillate. The one coming from the distillate Hydrocarbons can be continuously returned to the column for further use.

You can also use sodium hydroxide to dissolve the sodium hydroxide monohydrate from the column enrich and then this solution back into the column

Claims (1)

PATENT CLAIM: Process for concentrating aqueous hydrazine, further development of the process according to patent application O 2192 IVa / 12i, in which the hydrazine with an oxide acting as a dehydrating agent or Hydroxide in an amount of at least 1 mole of the oxide or hydroxide per mole to be removed Water is distilled in the presence of saturated aliphatic hydrocarbons or naphthenes and the hydrazine is mechanically separated from the hydrocarbons or naphthenes in the distillate, characterized by the use of saturated aliphatic, a boiling point at atmospheric pressure from 150 to 175 ° C having hydrocarbons or naphthenes. give together with hydrous hydrazine. The from 60 pp. 50 and 111 ff. Considered publications: Belgian Patent No. 496 059; Gmelin, manual of the inorganic. Chemie, 8th edition, 1936, volume "Ammoniak *, p. 547; L. F. Audrieth and Ogg, Betty Ackerson, The Chemistry of Hydrazine, New York and London, 1951, © 709 807/261 11:57