DD149794A1 - METHOD FOR SEPARATING HYDRAZINE - Google Patents

Abstract

The invention relates to a process for the separation of hydrazine from aqueous solutions by adsorption. It relates in particular to a process for the preparation of hydrazine-free solutions by using ion exchangers. The object of the invention is to remove the hydrazine contained in the distillates obtained during the work-up of the reaction product of the synthesis of hydrazine and thus to avoid decomposition of the by-product sodium hypochlorite on the return of the hydrazine-free solution to the reaction stage. The ion exchangers loaded with hydrazine are acid-treated Regen. The resulting hydrazine salts are immediately usable.

Description

21 9 550

Leuna works »waiter Ulbricht" Leuna, 26. 02. 1930

DI.R / Ry

L.P. 79101

Title of the invention

Process for the separation of hydrazine

Field of application of the invention

The invention can be used in the preparation and concentration of hydrazine-containing solutions by processes based on a reaction of ammonia and sodium hypochlorite.

Characteristic of the known technical solutions

It is known that mixtures of hydrazine, ammonia, sodium chlorite and water are worked up by distillation with the aim to produce highly concentrated hydrazine-water solutions (US-PS 2,935,451, DR-PS 767 296). The resulting distillates contain despite high separation costs shares of hydrazine. The partial recycling of the distillates to the reaction stage for the purpose of dilution of the reaction products is effected by equation

+ 2 NaOd> 2 NaCl + 2 H ₂ O + H ₂

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a decomposition of the feedstock LS sodium hydrochlorite, resulting in a yield reduction. It is also known that a hydrazine-free water can be recycled to the reaction stage, if the hydrazine is previously destroyed by means of oxidizing agent (JP-PS 174 801, JP-PS 174 802).

Object of the invention

The aim of the invention is to remove and recover the hydrazine contained in the distillates, to reduce the effort for the separation by distillation and to achieve an increase in the hydrazine yield.

Explanation of the essence of the invention

The object of the invention is to remove the hydrazine contained in the distillates obtained in the work-up of the reaction product of the synthesis of hydrazine, in order to avoid decomposition of the sodium hypochlorite feedstock when recycled to the reaction stage.

The object is achieved in that from the hydrazine-containing solutions, the hydrazine is removed by means of absorbents, the resulting hydrazine water is used to dilute the reaction products and are removed by regenerating the hydrazine-loaded adsorbents with acid salts formed for further technical use. :

Preferably, ion exchangers are used as adsorbents. ^; '

It is expedient if the resulting hydrazine-free solution is recycled to the reaction stage for dilution of the hydrazine synthesis by-products.

Sulfuric acid is used primarily for regeneration.

_3_ 219 550

Adsorption takes place in selective separation columns, which are operated periodically in the following stages:

Charging the separating column with hydrazine-containing aqueous solution until the beginning of the hydrazine breakthrough, which can be determined by conductivity measurement or ρH value measurement.

Regeneration of the hydrazine-loaded adsorbent with acid, primarily with 10% sulfuric acid;

Rinsing the separation column with condensate,

embodiment

The following example is intended to further illustrate the invention without, however, limiting it.

An aqueous solution of 0.1 % by mass of hydrazine and 99 % by mass of water was passed through a separating column at a rate of 50 parts by volume of solution per part by volume of ion exchange bed. The separation column was filled with cation exchanger.

At the exit of the ion exchange column, hydrazine-free water was withdrawn at the beginning of the adsorption process. The end of the separation process was reached when the hydrazine content of the exiting water was greater than 0.001 % by mass . The ion exchanger was regenerated with 1500 g of 10% sulfuric acid per liter of ion exchanger.

The resulting Hydraζinsulfat was removed with distilled water at a temperature of 343 K from the separation column.

Claims (4)

_ 2t 9 550 Inventions claim A process for the separation of hydrazine from aqueous solutions, characterized in that the hydrazine is removed from the hydrazine solutions by means of adsorbents, the resulting hydrazine-free water is used to dilute the reaction products and the salts formed by regeneration of the hydrazine-loaded adsorbents with acids for further technical use · 2. Method according to item 1, characterized in that ion exchangers are used as adsorbents. 3 · Method according to item 1 and 2, characterized in that the resulting hydrazine-free solution is recycled to the dilution of the Hydrazinsyntheseeinsatzprodükte in the reaction stage. 4 · Method according to item 1 to 3, characterized in that the regeneration is carried out with sulfuric acid.