CS206276B1 - Process for processing mother liquor waste from the production of 1,5-endomethylene-3,7-dinitroso-1,3 > 5,7-tetraazacycloctane - Google Patents

Abstract

The invention concerns the processing of mother liquors from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazacyclooctane in such a way that the main products of the processing are an aqueous solution of formaldehyde and crystalline sodium nitrate. For the industrial production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazacyclooctane, also known as N,N-dinitrosopentamethylenetetramine (DNPT), the most advantageous from a technological and economic point of view is the nitration cleavage of hexamethylenetetramine in a weakly acidic medium. The combination of mineral acid and alkali metal nitrites or calcium nitrite is almost exclusively used as a source of nitrosating agent. From the point of view of quality, yield and problems of isolation of N,N-dinitrosopentamethylenetetramine, the most optimal combination of nitric acid and sodium nitrite is in nitrosation cleavage. The by-products of the reaction (mother liquors) in this case are aqueous solutions of sodium nitrate, containing formaldehyde and ammonium ions, but there remains a certain amount of the starting sodium nitrite, taken into the reaction as a buffering and nitrosolysis catalyzing agent. A common case of terminating nitrosolysis is the neutralization of the entire reaction mixture with an alkaline hydroxide, in our case an aqueous solution of sodium hydroxide.

Description

CZECHOSLOVAK SOCIALISTIC DESCRIPTION EXCEEDED R E P 1 B A (19) CERTIFICATE OF CERTIFICATE (61) (23) Show Priority (22) Enrolled 30 03 79 (21) PV 2134-79 Wj 206 276 (11) (Bl) (51) Int. Cl? OJ C 07 C 47 / 04C 01 D 9/00

OFFICE OFFICE

AND DISCOVERIES (40) Published 30 05 80 (45) Published in 10 83 (75)

The inventor of KURAJDA PAVLL Ing., STRÁŽSKE

KOVÁČ JOZEP Lng., VRANOV NAD TOPÍOUPROCHÁZKA BOHUMIL Lng.

KOVÁSOVÁ KLÁRA lng., VRANOV NAD TOPÍOUFRIDRICH FRANTIŠEK lng., MICHALOVCEZEMAN SVATOPLUK lng., MICHALOVCEFILIP BOHUMIL lng. 7-tetraazacycloctane 1

The present invention relates to the treatment of mother liquors from the production of 1,5-endomethylene-3,7-di-nitroso-1,3,5,7-tetraazacycloctane so that the main processing products are aqueous formaldehyde solution and crystalline sodium nitrate.

For the industrial production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7 "tetraazacyclooctane, also known as N, N-dinitrosopentamethylenetetramine (DNPT), the nitration bonding of hexamethylenetetramine is the most advantageous from the aesthetic-economic point of view in a weakly sourced environment. Almost exclusively a combination of mineral acid and alkali metal nitrites or calcium nitrite is used as the nitrosating source. In terms of quality, yield and isolation of N, N-dinitrosopentamethylene-tetramine, the combination of nitric acid and sodium nitrate is the most optimal in nitrosation. The by-products of the reaction (mother liquors) are, in this case, sodium sodium nitrate solutions containing formaldehyde and ammonium ions, but there is still some starting sodium nitrite reacted as buffering anitrozolysis catalysing agent. A common case of ending nitrosolysis is the neutralization of the entire reaction mixture with a mixed alkali hydroxide, in our case an aqueous solution of sodium hydroxide. Here, tangible liquors, including those already mentioned, contain hexamethylenetetremine, polyols (C ^ to g) and other formulating and N-mannose reactants, as well as excess neutralizing agent. The processing of such mother liquors into a sodium nitrate solution & formaldehyde solution deals with CSSR ' s author ' s certificate No. 185 888 and the processing of crystalline sodium nitrate and aqueous formaldehyde in turn into a USSR ' 4424-78).

One of the most important conditions for the isolation of high quality sodium nitrate, most notably the reduction of organic substances in the mother liquors; The content of non-volatile organic fractions can be achieved, inter alia, by adjusting the end of nitrosolysis, as discussed in U.S. Pat. BSSR Author's Certificate No. ......... ............. (PV 66-78). According to the cited author's certificate, N, N-dinitrosopentamethylenetetramine is isolated by filtration of the acidic reaction mixture and neutralized by the filtration filter. In addition to the savings on the neutralizing agent, it is also possible to reduce the consumption of nitric acid in the process of treating the mother liquors in an economically advantageous manner.

SUMMARY OF THE INVENTION The present invention is directed to a process for the treatment of mother liquors from the production of 1,5-endo-methylene-3,7-dinitroso-1,3,5,7-tetraazaoylooctane resulting from the filtration of the acid-hydrolysis mixture containing 1: 1 nitrate, sodium, sodium nitrite, formaldehyde, ammonium ions and, if appropriate, a small amount of organo-impurities which correspond to the next product of the hexamethylenetetramine synthesis. SpSsob consists of five stages - in the first step, the mother liquors, preferably pre-heated to 70 to 95, are charged with 0.50 to 2.75 moles of nitric acid, preferably 0.54 to 2.70 moles of nitric acid. 1 mole of sodium nitrite present, at temperatures of 10 to 150 ° C, preferably at 20 to 139 ° C, at atmospheric pressure of up to 6 MPa, preferably at a pressure of up to 0.52 MPa, and a contact time of 5 to 30 minutes, preferably at a contact time of 10 to 20 minutes. Pre-warming of the mother liquors prior to self-conditioning of the nitric acid may have a beneficial effect on the suppression of formative reactions in thermal exposure! processed by the mother liquors (vi2 examples 1-5). - in the second stage, formaldehyde and a part of the water are distilled from the mother liquors and the pressure is up to 0.60 MPa, preferably at atmospheric pressure up to 0.48 Bft. In view of the further use of the aqueous formaldehyde solution thus obtained, it is preferable to use distillate. in the third stage, the distillation residue is concentrated to a content of 50 to 60% by weight. sodium nitrate, preferably 55.6 to 57.1% by weight; sodium nitrate; Here, waste heat from the pressure distillation of formaldehyde is utilized. in a fourth stage, the concentration of the sodium nitrate solution is adjusted to 57 to 75% by weight, preferably to 66.8 to 67.8% by weight of sodium nitrate by further thickening the evaporator-crystallizer, followed by crystallization of the sodium nitrate by cooling the solution to a temperature of 0 to 30% ° C, preferably by cooling to 10 to 20 ° C. In the fifth stage, separation of the liquid portions from the supersaturation of the fourth stage is effected, preferably, by means of a pulse centrifuge.

When performing the second stage distillation at atmospheric pressure, it can be omitted from the process thirdly.

When the distillation is carried out at a pressure of 0.3 to 0.6 MPa, the waste heat from this operation can be used not only in the third but also in the fourth stage of the process.

Similar to the processing of mother liquors in the sense of CSSR copyright certificate. 185 888 though. ............... (PV 4424-78), the process of this invention allows to obtain sodium nitrate free of sodium nitrite. Other technologies of sodium nitrate production do not allow the product of the above-mentioned quality.

The present invention addresses the environmental issue related to the production of 1,5-endo-methylene-3,7-dinitroso-1,3,5,7-tetraazacycloctane by the evaluation of formaldehyde and the concordance of a substantial portion of sodium nitrate contained in the mother liquors of this production. . EXAMPLE 1 There were mother liquors from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazaoylooctane by nitrosation of hexamethylenetetramine using sodium nitrite and nitric acid containing 0.01% by weight. nitrous acid, 2.48 wt. % of formaldehyde, 0.55 wt. sodium nitrite and 16.38 wt. sodium nitrate. 3000 ml of the mother liquors of this composition were pre-heated to 70 ° C and then 50 ml of 65.2% nitric acid (i.e. 2.706 moles of nitric acid per 1 mol of sodium nitrite) were added to the mixture. The temperature of the mixture reached the boiling point, i.e. 98 ° C. After refluxing for 2 min at reflux, the liquid fractions were distilled off. The distillation was completed, when the amount of distillate was 2560 ml of distillate containing 2.60% by weight. % of formaldehyde and 0.07 wt. formic acid. By quenching the distillation residue from a primary 117.5 ° C to 20 ° C and isolating the fine crystals from the resulting supernatant by filtration through a plug, 440.6 g of a filter cake was obtained which dried at room temperature to give 371 sodium nitrate (ie 66.2). % of the total amount of sodium nitrate), free of sodium nitrite. The acidity of this nitrate, expressed as nitric acid content, was 0.001% by weight, and the organic matter content, represented by the chemical oxygen demand, was max. 1138 mg of oxygen by 1 kg of sodium nitrate.

The mother liquors after crystallization of sodium nitrate were 415 g and contained 0.38 wt. nitric acid and formic acid, 1.37 wt. sugars (C5 to C14) and polyols (C5 to C5)

Cy) expressed as glucose and 47.5 wt. sodium nitrate. 4,206,276 Example 2 Available! The mother liquor, origin and composition were identical to the mother liquors of Example 1. Analogous to this procedure, only 50 ml of 65.2% nitric acid was added to the mother liquors of 20 ° C, and until the mixture was started and the mixture was heated. . After refluxing for 20 minutes, 2590 ml of distillate containing 2.47% by weight of distillate were distilled off from the mixture. % formaldehyde and 0.08 wt. formic acid. By heating the distillation residue to a temperature of 20 ° C, the precipitate resulted in a precipitate from which 444.7 g of filter cake was obtained by filtration. Drying the filter cake at lab. 374 g of nitrous sodium free nitrite, which is 66.6% of the total amount of sodium nitrate, were obtained at a temperature of 0.001% by weight of nitrate. and the content of organic portions presented therein by oxygen oxygen consumption was 3415 mg of oxygen per kg of sodium nitrate.

The mother liquors after crystallization of sodium nitrate were 411 g and contained 0.48 wt. nitric and formic acids, 0.02% w / w to Ογ) and polyols (C ^ to ažγ) expressed as glucose, and 47.26% w / w. sodium nitrate. Example 3 Available! the mother liquors from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazaoyloclotane were nitrosated with hexamethylenetetramine using sodium nitrite and nitric acid containing 0.01 wt. nitrous acid, 0.69 wt. % nitrite sodium, 3.53 wt. % formaldehyde and 15.61 wt. sodium nitrate, 3000 ml of the mother liquors of the above composition were pre-heated to 77 ° C and then 40 ml of 65.2% nitric acid, i.e. 1.715 moles of nitric acid per 1 mol of sodium nitrite, was added. The mixture reached the boiling point (i.e., 99 [deg.] C.) and was maintained under reflux for 20 minutes. Thereafter, 2500 ml of distillate, containing 2.95 wt. % formaldehyde and 0.05 wt. formic acid. Rapid cooling of the distillation residue to 14 ° C resulted in a precipitate from which 438 g of filter cake was obtained by filtration on a filter. Drying of the filter cake at room temperature resulted in 367 g of sodium nitrate, which is 68.7% of the total amount of sodium nitrate. This nitrate was free of sodium nitrite, its acidity, expressed as nitric acid content, was 0.004% by weight, and the organic solution content, presented by chemical oxygen demand, was 2277 mg of oxygen per 1 kg of sodium nitrate. The liquors after crystallization of sodium nitrate were 365 g and contained less than 0.01 wt. nitric acid and formic acid, 1.44 wt. sugars (0 → ^ Ογ), expressed as glucose, and 45.8% by weight of sodium nitrate. 5 208 278 Example 4 Available! the mother liquors, origin and composition were the same as in Example 3 ·

As described in Example 3, only 40 ml of 65.2% nitric acid was added to 21 ° C of the mother liquor before the heating mixture was started. After refluxing the mixture for 20 minutes under reflux, 2552 mL of distillate was distilled, containing 2.81% by weight. % of formaldehyde and 0.03 wt. acid formate. Rapid cooling of the distillation residue to 14 ° C resulted in a suspension from which solids were separated by filtration on a plug. Thus, 449 g of filter cake was obtained, which after drying at room temperature. temperature of 380 g of sodium nitrate was 71.1% of the total amount of sodium nitrate. This sodium nitrate was free of sodium nitrite, its acidity, expressed as nitric acid content, was 0.003% by weight, and the organic matter content, presented as chemical oxygen demand, was 4568 mg of oxygen per 1 kg of sodium nitrate. Twenty minutes of heating the sodium nitrate to a temperature of 245 to 250 ° C, the chemical consumption of 1 kg of said salt decreased to 583 mg of oxygen.

The mother liquors after crystallization of sodium nitrate were 337 g and contained 0.35 wt. nitric acid and formic acid, 1.66 wt. sugars (C ^ to 0?) and polyols (C? to? g), expressed as glucose, and 45.81 wt. sodium nitrate. EXAMPLE 5 Mother liquors from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7, -tetraazacyclooctane by nitrous cleavage of hexamethylenetetramine using sodium nitrite and nitric acid <mother liquors resulted from filtration of the nitrosolysis acid mixture contained 0.017 % wt. nitric acid, 0.71 wt. sodium nitrite, 2.58 wt. % formaldehyde and 15.55 wt. sodium nitrate. To 3000 ml of the mother liquors of the above composition and at 22 DEG C., 13 ml of 65.2% nitric acid, i.e. 0.543 moles of nitric acid per 1 mol of sodium nitrite, was added. After refluxing for 20 minutes, 2600 ml of distillate of 3.08% by weight of distillate were distilled off. % formaldehyde, 0.001 wt. formic acid and 96.919% wt. The rapid cooling of the distillation residue to 18 ° C resulted in a suppression which yielded 511 g of filter cake by filtration on a nut. Drying the filter cake at room temperature gave 435 g of sodium nitrate containing 0.21% by weight. The nitrate acidity of the nitrate, expressed as nitric acid content, was 0.003% by weight. and the content of organic matter, presented as chemical oxygen demand, was 4570 mg of oxygen per 1 kg of sodium nitrate. This sodium nitrate was poorly felt for methylamine.

The mother liquors after crystallization of sodium nitrate (232 g) contained 0.78 wt. formic acid, 2.16 wt. sugars (0 ^ to Ογ) and polyols (Cj to Ογ), expressed as glucose, and 45.69 wt. sodium nitrate. Example 6 3885 kg.h &quot; mother liquors from the production of 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetra-azaoylooctane resulting from the acid filtration; % Wt. nitrous acid, 0.61 wt. sodium nitrite, 2.76 wt. % formaldehyde and 15.32 wt. sodium nitrate, is pre-heated to 87-89 ° C and then referred to the nitrite decomposition reactor. This reactor is fed with 53.7% nitric acid at 40.33 kg.h -1, i.e. 1,001 moles of nitric acid per liter of sodium nitrite. The decomposition is carried out at a temperature of 124 to 126 e0 and a pressure of 0.4 MPa and holds the reactor for 12 minutes. The pressure in the reactor is controlled by the collection of a gaseous effluent (nitrogen, carbon dioxide, and nitric oxide), which, at normal conditions, represents approximately 8.85 m ^ · h · h and a mass of 15.6 kg · h · · · ·

The mother liquors so treated, containing 2.56 wt. % sodium formaldehyde; formic acid are subjected to pressure distillation of formaldehyde at a pressure of 0.4 MPa. The rain liquor is 14.9% aqueous formaldehyde at 604.7 kg.h ". The distillation residue of 3307.3 kg.h &quot; contains 18.88% by weight of sodium nitrate, 0.09% by weight of formic acid, 0.14% by weight of cucumbers (C ^ až ažΟ) and post-lyals. (C %1 formal ?dehy) and 0.21% w / w formaldehyde This distillation residue is fed to a evaporative evaporator in which it is concentrated to 57.1% by weight sodium nitrate by means of waste heat from a pressure distillation. the solution further comprises 0.51% by weight of buffers (C až-C)) and polyols (0j to C až,), 0.1% by weight of formic acid, and 0.14% by weight of formaldehyde.

Said solution, in an amount of 1093.2 kg.h ", is fed to an atmosphere of evaporator-crystallizer, whereby the waste heat from the pressure distillate is concentrated to a content of 66.8% by weight. the sodium nitrate then the heating of the evaporator-crystallizer is stopped and then it is started with slow, programmed cooling of the apparatus contents (with stirring) up to 10 ° C. In the cooling phase, in this stage of processing of the mother liquor, the constriction of the thickening is maintained by incorporating a further evaporator-crystallizer into the line. Resulting of the sodium nitrate supernatant is a liquid sub-layer free of the pulsatile medium. Moisture content and drying yields 389.1 kg.li ’* of sodium nitrate, ie 62.39% of the total sodium nitrite free of sodium nitrite. The acidity of this nitrate, expressed as the nitric acid content, is 0.001% by weight, and the organic drug content presented by the chemical oxygen demand is 590 mg of oxygen per kg of sodium nitrate. From the isolation of sodium nitrate, 544.5 kg.h * of the filtrate containing 43.82 wt. sodium nitrate, 1.32 wt. ω (0 to C?) and polyols (C? to Ογ) and 0.08 wt. formic acid. EXAMPLE 7 4440 kg.h -1 of mother liquors from the manufacture of 1,5-endomethylene-3,3-dinitroso-1,3,5,7-tetraazacyclooctane resulting from the filtration of the acidic nitrosolysis mixture and containing less than 0.001% w / w. nitrous acid, 0.58 wt% sodium nitrite, 2.81 wt% formaldehyde and 15.06 wt% sodium nitrate, is preheated to 93-95 ° C and reported to the nitrite decomposition reactor. 54.8% nitric acid at 43.25 kg.h -1, i.e. 1.008 moles of nitric acid per mole of sodium nitrite, at a temperature of 137-139 ° C and a pressure of 0.52. Reactor pressure is 10 minutes The reactor pressure is controlled by the extraction of gaseous products (nitrogen, carbon dioxide, and nitric oxide) whose volume of 3 -1 -1 under normal conditions is about 10.1 m. kg.h ·

The mother liquors so treated, containing 2.64% formaldehyde, 15.67 wt. sodium nitrate and 1.005 wt. formic acid, pressure distillation at a pressure of 0.48 MPa is applied after cooling to 98-101 ° C. The distillate is 15.6% aqueous formaldehyde in a quantity of 709 kg.h "". The distillation residue, which is 3759.4 kg.h "· 1 · 1, contains 18.62% by weight sodium nitrate, 0.16% wt. % of formaldehyde, 0.18 wt. formic acid and 0.081 wt. polyols (Cg to O?) and sugars (Cg to C?), expressed as glucose.

This distillation residue is concentrated in an atmospheric evaporator using the waste heat of the pressurized distillation to a 55.6% sodium nitrate solution which still contains 0.09% by weight. formaldehyde, 0? 021 wt.%, formic acid and 0.25%? polyols (Cg to Ογ) and echrons (Cg to Ογ). This solution, in an amount of 1259.7 kg.h -1, is fed to an at-phosphorus evaporator-crystallizer, where it is concentrated to a content of 67.8% by weight of nitrate-sodium by means of waste heat from the pressurized distillation. with slow, programmed cooling of the evaporator-crystallizer contents up to 10 DEG C. Concentration of the thickener is ensured as in Example 6. The result of the suppression is the liquid portions of the pulsating centrifuge, thereby returning the filter cake with 2, Drying of this filter cake yields 450.8 kg.h -1 of sodium nitrate, i.e. 64.4% of the total amount of nitrous sodium free sodium nitrite. The acidity of this sodium nitrate, expressed as nitric acid, is 0.002% by weight. and the organic matter content presented by the oxygen chemical consumption is 386 mg of oxygen per kg of sodium nitrate. From the isolation of sodium nitrate 573 kg.h "1 of filtrate with a content of 43.82% by weight of sodium bisulfate, 0.01% by weight of formic acid and 0.85% by weight of polyols (Cg to Ογ) of acucers (Cg to C?), Expressed as glucose.

Claims (2)

DM RE DM El OF THE INVENTION 1. A process for the treatment of mother liquors, omitted from the production of 1,5-endomethylan-3,7-dinitroso-1,3,5,7-tetraazaoyclooctane by nitro-cleavage of hexamethylene-tetramine with sodium nitrite and nitric acid and isolated by filtration of the acid nitrosolysis mixture containing sodium nitrite sodium, formaldehyde, ammonium ions and possibly even small amounts of organo-organic substances correspond to by-products of the synthesis of hexamethylenetetramine, characterized in that it consists of five stages, wherein in the first stage the mother liquors are preferably preheated to a temperature of 70 to 95 ° C; it is treated with nitric acid in an amount of 0.50 to 2.75 moles, preferably 0.54 to 2.70 moles of nitric acid, per mole of sodium nitrite present, at a temperature of 10 to 150 ° C, preferably at a temperature of 20 to 139 ° 0, at atmospheric pressure up to 0.6 MPa, preferably at atmospheric pressure 0.52 MPa, and a contact time of 5 to 30 minutes, preferably In the second step, the formaldehyde is distilled off at a pressure of max. 0.60 MPa, preferably at atmospheric pressure to 0.4S MPa, in the third step the distillation residue is concentrated to a content of 50 to 50 bar. 60 wt. % sodium nitrate, preferably concentrated to a content of 55.6 to 57.1 wt. sodium nitrate, in the fourth step, the sodium nitrate solution concentration is adjusted to 57-75% by weight by further evaporation of the water, preferably it is adjusted to 66.8-67.8% by weight. sodium nitrate with subsequent cooling of the sodium nitrate solution to a temperature of 0 to 30 ° C, preferably by cooling the sodium nitrate solution to a temperature of 10 to 20 ° C, and in the fifth step the sodium nitrate from the resulting suspension is isolated, preferably SPIN. 2. The method for the treatment of mother liquors according to claim 1, characterized in that the third stage can be omitted from the process.