CS199090B1 - Treatment of mother liquor from the production of 1,5-endomethylen-3,7-dinitriso-1,3,5,7-tetraazacyclooctane - Google Patents

Description

The present invention relates to the treatment of mother liquors from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazacyclooctane so that, after removal of the nitrite present, the free formaldehyde contained in these wastes is converted to a non-volatile organic substance.

For the industrial production of 1,5-aminomethylene-3,7-dinitroso-1,3,5,7-tetraazacycloctoctan, also known as Ν, Ν-dinitrosopentamethylenetetramine, the nitrosative cleavage of hexamethylenetetramine is the most economically economically advantageous. In this connection, the combination of a mineral acid and an alkali metal nitrite or calcium nitrite is used almost exclusively as the nitrosating agent source.

The by-products remaining in the reaction mixture after product isolation (i.e. in mother liquors) are primarily inorganic acid salts, formaldehyde, ammonium ions, and there is also some excess nitrite, taken into reaction as a buffering and catalysing additive. If the nitrosation cleavage of hexamethylenetetramine is terminated by neutralizing the entire reaction mixture with an alkaline hydroxide, then the mother liquors also contain hexamethylenetetramine, a smaller amount of polyol and other products of formation and H-Mannich condensations. The polyols and the sum of the corresponding N-Mannich bases are, to a small extent, introduced into the reaction mixture even when the concentrated reaction mixtures are applied by ammoniacalization of aqueous formaldehyde instead of crystalline hexamethylenetetramine.

188090

The scientific literature still lacks data on the use of mother liquor type mixtures from the production of N, t-dinitrosopentamethylenetetramine. In the field of patent literature, a method for oxidizing the organic fractions of these mother liquors to obtain a solution of pure inorganic salt (PV 831-76) has been described, the method of removal to formaldehyde and the acid-hydrolyzable fraction and the vast majority of free formaldehyde 77), and the use of treated mother liquors containing nitrates as the inorganic product as urea solvents for the production of fertilizers based on urea ammonium nitrate complex (PV 6275-77).

In view of the quality, yield and isolation issues of N, N-dinitrosopentamethylenetetramine, nitric acid and alkali metal or calcium nitrite nitrite as the source of the nitrosating agent are most preferred in nitrosating cleavage of hexamethylenetetramine. Here, by-products of nitrosolysis are the respective inorganic nitrates and some of the nitrite starting material. Upon removal of nitrite by means of sulfuric acid, a mixture comprising alkali metal nitrate or calcium nitrate and formaldehyde results, and a small amount of polyol or chink type substances, respectively, may be present. niohium-derived carboxylic acids.

Nitrite is removed from the mother liquor by acidifying it to a pH of 2 to 0 and subsequent thermal exposure. The hexamethylenetetramine present is also aidolysis to formaldehyde and ammonium ions; some of the ionic ions pass by reaction with nitrite anions, resp. nitric acid, to nitrogen and water (Monatsh. Chem. 1953.84. 820; Japan. Kokai 74 110,148).

The free formaldehyde in the mother liquors thus treated can then be converted either to hexamethylene tetramine or to polyols and the corresponding substance. Conversion of formaldehyde to hexamethylenetetramine can advantageously be realized in the technical practice by ammoniaization of the treated mother liquor either with ammonia gas or an aqueous solution thereof, or by displacement of ammonia from ammonium nitrate with a stronger hydroxide. The conversion of formaldehyde to polyols and the uterine of the corresponding substance, i.e., the formaldehyde formation reaction, is most readily at temperatures above 70 ° C under catalysis of calcium oxide and calcium oxide, respectively. its monohydrate. In the formation reaction, conducted at pH 7.5 to 12, the reaction takes place (when the formaldehyde disappears from the mixture) and dehydrogen addition is formed, which is accompanied by browning of the reaction mixture. For this reason, it is advisable to adjust the pH to 7 to 3 at the end of the reaction. The acidification of the mixture after the formation reaction also has the advantage that even a small amount of hexamethylenetetramine and / or hexamethylenetetramine is formed. of other N-Manniohe bases during this reaction, it is possible to acidolyz to the corresponding aldehyde and ammonium ions.

The organic portions of the mother liquor thus treated are no longer volatile (except for traces of formaldehyde resulting from the decomposition of hexamethylenetetramine after the formation reaction) so that the mother liquors can be concentrated to the required nitrate concentration without resulting in toxic distillate. When distilling the aqueous fraction of mother liquor, it is advisable to add some antifoams to them, but when using a film evaporator, an antifoam is not necessary.

Due to the biological harmlessness of the polyol, the concentrated mother liquors containing nitrates as an inorganic component can be used, for example, as fertilizers.

The treatment of mother liquors according to the invention has not been described so far in either the scientific or patent literature. It solves the environmental problem in relation to the production of N, N-dinitrosopentamethylenetetramine by treating the mother liquor within the meaning of this invention with a mixture. free of toxic formaldehyde and toxic nitrite, which is, for example, a potential fertilizer.

Example 1

A mixture of mother liquors from the production of Ν, din-dinitrosopentamethylenetetramine using nitric acid and calcium nitrite and nitric acid and sodium nitrite was used. 1000 ml of this mixture contained:

0.43 g of calcium hydroxide,

71,60 g calcium nitrate,

68,52 g sodium nitrate,

4.21 g calcium nitrite,

4.74 g sodium nitrite,

12.40 g hexamethylenetetramine,

18.48 g of formaldehyde.

The chemical oxygen demand was 46,901 mg oxygen per 1000 ml. To 660 liters of this liquor was added 50 kg of ammonium nitrate, after dissolution the pH of the mixture was adjusted to 1 with 20.6% nitric acid. The mixture was then heated to 95 ° C for 30 minutes. After this time, when the escape of gaseous fumes from the reaction mixture almost ceased, the solution was cooled to 75 ° C and after addition of 75 ml of ethylene oxide polycondensate (TPD-10-271-66, manufacturer CHPWP Novaks) was a solid calcium oxide monohydrate. The pH of the mixture was adjusted to 10. Vacuum concentration (at a vacuum of 5.9-10.7 to 6.7.10 Pa) of the mother liquors so treated was made to 43% of the original volume. The distillate showed a pH > 9 and a chemical oxygen demand = 0 mg oxygen per 1000 ml.

1000 grams of thickened mother liquor, having a pH of předchozí 6.7 and a density at 20 ºC of 1,330 g.cm ^-1 without prior treatment, had a composition of:

11,35% sodium nitrate,

16.66% calcium nitrate,

4.86% ammonium nitrate,

2.75% hexamethylenetetramine,

0,80% polyol,

63.58% water.

The chemical oxygen demand per 1000 g was 39.2 g oxygen.

198 OSO

Example 2

The mother liquors from the production of N, l-dinitrosopentamstylenetetramine were used using nitric acid and sodium nitrite, containing in 1000 ml:

1.76 g sodium hydroxide,

21.66 g of sodium nitrite,

3.52 g of hexamethylenestramine,

15.44 g formaldehyde,

176.08 g of salts.

Chemical oxygen demand <= 25 250 mg oxygen per 1000 ml.

12 kg of ammonium nitrate was added to 500 l of this liquor and the pH of the mixture was adjusted to 0 with 54.1% nitric acid. After heating at 95 DEG-102 DEG C. for thirty minutes, 1000 ml of the treated mother liquor contained 164.09 g of sodium nitrate and oxygen consumption was 20,841 mg per 1000 ml.

After cooling to 80 ° C, the pH of these mother liquors was adjusted to 8.5 with solid calcium oxide monohydrate and after addition of 75 ml of ethylene oxide polycondensate (TPD-10-271-66) defoamer and agitation for 10 minutes at 80-85 ° C. The mixture was adjusted to 7.3 with 65% nitric acid. The mixture was then concentrated to a volume of 200 L under a vacuum of 5.5 to 6.0 bar. The distillate showed a pH of 6.4 and a chemical oxygen demand = 0 mg of oxygen per 1000 ml.

The mother liquors thus treated had a pH of &lt; 6.9 and a density at 20 ° C of &lt; 1.280 g.cm &lt; -1 &gt;

23.86% sodium nitrate,

5.09% calcium nitrate,

0,25% ammonium nitrate,

2.15% polyol

68.65% water.

The chemical oxygen demand, based on 1000 g, was 25.05 g oxygen.

Example 3

The concentrated mother liquors of Example 2 were concentrated to 62.67% of the original weight in a rotary evaporator under a vacuum of 5.0-10 to 5.10 bar. The distillate showed a pH of ,36.3 and no chemical oxygen consumption. The composition of the mother liquors thus treated in the prooenteoh was:

38.07% sodium nitrate,

8,12% calcium nitrate,

0.40% ammonium nitrate, 3.43% polyol,

49.98% water.

The chemical oxygen demand, based on 1000 g, was 40 g oxygen. The mixture thus concentrated

AND

OSO at normal temperature was a sodium nitrate suspension.

Example 4

Mother liquors from the production of N, N-dinitrosopentamethylenetetramine using nitric acid and sodium nitrite, partially diluted with the washing waters of this production, whose 1000 ml contained:

1.24 g of sodium hydroxide,

7.55 g sodium nitrite,

2.72 g of hexamethylenetetramine,

11.73 g formaldehyde,

111.23 g of salts.

Chemical oxygen demand = 26,453 mg oxygen per 1000 ml.

16000 ml of the liquor of this composition was acidified with 65% nitric acid to pH &gt; 2 and then heated to 90-95 ° C for 10 minutes. After cooling to 72 ° C, the pH of the mixture was adjusted to 12 with anhydrous calcium oxide. After stirring for 25 minutes at 73-76 ° C, the free formaldehyde disappeared from the mixture and the pH of the mixture was adjusted to 4.8-5 with ca 65% , 2. The reaction mixture was then concentrated to a volume of 4000 ml under a vacuum of 6.7 mmHg. The distillate had a pH of 5.5 and its chemical oxygen demand was 1611 mg oxygen per 1000 ml.

The distillation residue had a pH of 5,5 5.5, chemical oxygen demand «56 112 mg of oxygen per 1000 ml, total nitrogen content = 68.19 gl ^-1 , ammoniacal nitrogen content = 1.37 gl ^1, and 0.155 moles of calcium nitrate in 1000 ml. The density of the concentrated mother liquor at 20 ° C was 1.29 g.om ³ .

Example 5

The mother liquors treated according to Example 4 were concentrated to 65.41% of the original weight on a rotary evaporator under a vacuum of 4.8 to 5.0.10 Pa. The distillate showed a pH of 6.1 and no chemical oxygen demand. The composition of the residue, which was a saturated solution of sodium and calcium nitrate, expressed as a percentage by mass, at 85 ° C was:

43,92% sodium nitrate,

3.12% calcium nitrate, 0.93% ammonium nitrate, 1.02% polyol,

50.83% water.

The chemical oxygen demand, based on 1000 g, was 67 g oxygen. Density of lye at o

° C (suspension) = 1.58 gm

Claims (1)

SUBJECT OF THE INVENTION Process for treating mother liquors resulting from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazaeyclooktane by nitrosation of hexamethylenetetramine with nitric acid and an alkali metal or calcium nitrite, characterized in that the mother liquor lyes, containing inorganic nitrates, inorganic nitrites, formaldehyde and optionally hexamethylenetetramine, are acidified to pH 2 to 0 with nitric acid and, preferably in the presence of ammonium nitrate, up to 75.7 g of this nitrate per liter of caustic solution, 110 ° C, preferably 90 to 102 ° C, and at a reaction time of 10 to 30 minutes to an aqueous solution of nitrate and formaldehyde, the pH of which is adjusted to 7 to 12, preferably 8.5 to 12 by the action of calcium oxide or its hydrate. , and the subsequent formation reaction is conducted at 20 to 100 ° C, preferably at 72 to 85 ° C, after which the solution is acidified with acid. with a nitric acid line to a pH of up to 3, preferably 7.3 to 4.8, and subsequent concentration, preferably by vacuum distillation under a vacuum of 4.8-10.7 to 6.7.10 Pa, to at least 43% of the original volume.