Method for separating nitrogen isotopes

Abstract

The invention relates to technology for obtaining concentrated nitrogen isotopes using physicochemical methods, and is applicable in the field of nuclear engineering, as well as in biology, medicine and agriculture. A method for separating nitrogen isotopes is carried out by chemical isotope exchange using ammonia as the working substance. Furthermore, nitrogen isotope separation is carried out in a two-phase "gas-liquid" system with a gas phase containing one or several polyols and / or alkanolamines which form complex compounds with ammonia. The result is an increase in the efficiency of the nitrogen isotope separation process.

Description

[0001] A method for separating nitrogen isotopes.

[0002] The invention relates to the field of chemical technology, namely to the production of concentrated nitrogen isotopes by physicochemical methods, and can be used in nuclear power engineering, as well as in biology, medicine and agriculture.

[0003] Currently, the concept of a closed nuclear fuel cycle (CNFC) has been formed in the nuclear power industry, which involves the use of mixed uranium-plutonium nitride fuel for fast neutron reactors. The implementation of CNFC will significantly reduce the production of radioactive waste and use depleted uranium, accumulated in large quantities at nuclear industry enterprises, as a fuel component. However, nitrogen of natural isotopic composition, which is part of such fuel, consists of more than 99.6 mol. % of the isotope nitrogen-14 ( 14N), which significantly absorbs neutrons to form radioactive isotopes of tritium and carbon-14. At the same time, nitrogen-15 ( 15N), which is contained in the natural isotopic mixture at 0.366 mol.%, practically does not absorb neutrons, therefore the fuel based on it will be characterized by a lower unproductive consumption of neutrons and a much lower production of biologically hazardous tritium and carbon-14. The isolation of nitrogen-15 from the natural isotopic mixture in concentrated form is a very complex task, especially if it is necessary to create the production of nitrogen-15 with a concentration of up to 90 mol.% and more in quantities of about a ton per year. The proposed method for separating isotopes, in which isotopic enrichment in nitrogen-15 is carried out due to the reaction of chemical isotope exchange in systems with polyhydric alcohols (polyols) and / or amino alcohols, and the working substance is ammonia, will allow solving the above problems with maximum efficiency, with minimal costs of reagents, energy and with a minimum amount of waste generated.Physical methods of isotope separation, such as gas centrifugal and laser, are unsuitable for organizing tonnage production of nitrogen-15 due to low productivity and very high costs per unit of separation work. More effective physical and chemical methods that have found application in the separation of nitrogen isotopes can be divided into four groups, according to the type of working substances used in the separation mass-exchange columns.

[0004] The nitric acid or Nitrox method of separating nitrogen isotopes is known and has received the widest distribution. This method is based on chemical isotope exchange between nitric acid in the liquid phase and a gaseous mixture of nitrogen monoxide and dioxide according to reactions (1-2).

[0005] High values ​​of the single-stage nitrogen isotope separation factor in this system (up to 1.055) and good process kinetics allow efficient isotope separation in columns of relatively small height and diameter. The main problem with the Nitrox method is the need to spend large amounts of sulfur dioxide for the complete conversion of nitric acid leaving the isotope exchange column into nitrogen oxides, which are returned to the column via reaction (3).

[0006] The consumption of sulfur dioxide can be up to 50 tons per 1 kg of produced highly enriched nitrogen-15. At the same time, an equivalent amount of sulfuric acid is formed as waste, which requires disposal. In this regard, the Nitrox method in its classical form is practically impossible to use for tonnage production of nitrogen-15.

[0007] To return sulfur dioxide to the nitrogen reduction cycle, it was proposed to thermally decompose sulfuric acid into its components (RO131314. Axente DA, Balla A.S., Marcu M.S., Gergely §. Method and plant for producing the isotope by isotopic exchange in NO x -HNO3system. Published 30.08.2016. IPC BO1D 59 / 32).

[0008] The disadvantages of the method are that such an approach requires multiple heating and cooling of corrosive environments to clean sulfur dioxide from other decomposition products, which will lead to high energy costs, and such a process will not proceed to the end. Also known is a method for implementing the Nitrox method, in which, to eliminate chemical circulation of flows, a two-temperature exchange is carried out between nitric acid with a concentration above 40% and nitrogen oxides in the temperature range from - (50 - 47) to + (47 - 50) °C (author's certificate SU 786102 A1 RF, Vetsko V.M., Gorshkov V.I., Egiazarov A.S. et al., priority 03.04.1979, published 27.01.1995). This option would require a significant increase in the size and metal content of the isotope separation equipment, so it is also not suitable for obtaining tonnage quantities of nitrogen-15.

[0009] Low-temperature rectification of nitrogen monoxide (up to 1.03) is characterized by high values ​​of the single-stage nitrogen isotope separation factor. One of the implementation options for this method of obtaining nitrogen-15 includes automatic control of the hydrodynamics of the column for obtaining the target component (patent RU 2299090 C2, Borman V.D., Vetsko V.M., Golyshev V.G. et al., priority 12.01.2005, published 20.06.2006). The production of nitrogen-15 using this technology is associated with high costs of cryogenic agent, with the explosion hazard of the process and the risk of catastrophic freezing of nitrogen monoxide in the column, which has very close melting (-163.6 °C) and boiling (-151.7 °C) temperatures. The organization of tonnage production of nitrogen-15 for nitride fuel of fast reactors by this method is also complicated by the need to use large quantities of toxic, corrosive nitrogen monoxide and the disposal of its waste, depleted in nitrogen-15.

[0010] Very attractive for obtaining tonnage quantities of the nitrogen-15 isotope are processes using molecular nitrogen N2 as a working substance, which is its safest form: non-toxic, chemically inert, and also the cheapest and most accessible. To separate nitrogen isotopes, a process of its low-temperature rectification at temperatures from -210 °C (triple point) to -147 °C (critical point) can be used. The process of obtaining nitrogen-15 can be implemented by low-temperature distillation of nitrogen containing trace amounts of oxygen and argon, in a cascade of columns, in which the argon-oxygen mixture is discharged from the bottom of the final column, and liquid nitrogen enriched in nitrogen-15 is withdrawn from an intermediate point of the final column (patent EP2191885 (A1), filed on 12.09.2008, published on 02.06.2010).Unfortunately, this process is characterized by very low isotope separation factors (about 1.004), which makes it very energy-intensive and inefficient. It is possible to increase the nitrogen isotope separation factors and avoid low temperatures by using chemical isotope exchange between gaseous molecular nitrogen and solutions in which it is present in the form of complexes with some transition metals (patent RU 2583808 C1, Semenov A. A., Skupov M. V., Lizunov A. V. et al., priority 18.02.2015, published 10.05.2016). But this method, as well as all those using molecular nitrogen N2 as a working substance, cannot be used directly to obtain nitrogen-15 with a concentration above 50%, since in the natural isotopic mixture almost all nitrogen-15 is present in the form of very strong molecules of mixed isotopic composition. 15 N 14 N. To obtain molecules from them 15N2 requires the use of additional complex and energy-intensive operations of homomolecular isotope exchange, which significantly reduces the efficiency of such methods of separating nitrogen isotopes.

[0011] The closest to the claimed variant are the methods of separating nitrogen isotopes in systems in which the working substance is ammonia. Ammonia is the largest-tonnage nitrogen compound, it is cheap, easy to handle and environmentally friendly. Since the ammonia molecule contains only one nitrogen atom, ammonia, when used as a working substance for separating isotopes, unlike the previous case, does not require a homomolecular isotope exchange reaction. Ammonia is capable of entering into a reversible reaction of forming complexes with some organic compounds. If such a reaction is accompanied by an isotope effect, then it can potentially be used to separate nitrogen isotopes, while the phase flows can be reversed thermally by sorbing ammonia with a cooled complexing agent at the bottom of the column and releasing ammonia from the complex during heating in its upper part.

[0012] The system "ammonia - ammonia complex with pentanol" was chosen as a prototype (Naing Zo E. Cherednichenko S.A., Khoroshilov A.V. Isotopic equilibrium in the system ammonia - a complex compound of ammonia with pentanol-1. Advances in chemistry and chemical technology: Collection of scientific papers - Vol. XXVI, No. 7 (136). - Moscow: D.I. Mendeleyev University of Chemical Technology). Pentanol-1 has a fairly high boiling point (136-138 °C), therefore it allows achieving a more complete decomposition of the complex with ammonia than in the case of light alcohols. The value of the single nitrogen isotope separation factor in this system at a temperature of 293 K was 1.0095. The residual concentration of ammonia in pentanol-1 after desorption was 0.3 μg / cm 3 The proposed method allows obtaining nitrogen-15 with a molar concentration of 30-50% with a product loss rate of (5-10)%, respectively.

[0013] Obtaining more concentrated nitrogen-15 will result in increased product losses and a significant reduction in the efficiency of the separation process, which is the main disadvantage of this method of nitrogen isotope separation. An additional disadvantage of this system is the low volume concentration of ammonia in pentanol-1 at saturation (0.286 mol ammonia per mole of alcohol or 2.63 mol / L at 20 °C). Obtaining a product with a concentration of 90% nitrogen-15 from nitrogen of natural isotopic composition in a column will require at least 870 theoretical stages.

[0014] Thus, all previously known systems for separating nitrogen isotopes in systems with ammonia and thermal circulation of flows were characterized by either low isotope effects and low loading of the complexing agent, or the absence of complete circulation of flows during thermal decomposition of the complex.

[0015] The task was to find such liquid reagents that would combine high ammonia loading during complex formation with a high isotope effect for nitrogen and the possibility of complete desorption of ammonia. The most effective such reagents were compounds containing two or more hydroxyl groups (polyalcohols), as well as compounds from the amino alcohol class due to their high capacity for ammonia and high boiling point.

[0016] The technical result is a method for obtaining highly concentrated nitrogen-15 by separating nitrogen isotopes in a new system with chemical isotope exchange between gaseous ammonia and a liquid phase containing a complex of ammonia with one or more polyhydric alcohols and / or amino alcohols, which makes it possible to increase the efficiency of the process many times over.

[0017] The technical result is achieved in a method for separating nitrogen isotopes by chemical isotope exchange with ammonia as a working substance, wherein the separation of nitrogen isotopes is carried out in a two-phase “gas-liquid” system with a liquid phase containing one or more polyhydric alcohols and / or amino alcohols that form complex compounds with ammonia.

[0018] Polyhydric alcohols from the following series are used: ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin and amino alcohols from the following series: monoethanolamine, diethanolamine, triethanolamine or mixtures containing the above substances.

[0019] Chemical isotope exchange between gaseous ammonia and a liquid phase containing dissolved ammonia is carried out in a column-type countercurrent mass exchange separation unit filled with packing.

[0020] In the lower part of the separation counter-current mass exchange unit of the column type, the liquid phase is heated until the ammonia is completely removed from it, after which the liquid phase, purified from ammonia, is sent to the upper part of the unit for irrigation, and the released gaseous ammonia is returned to the lower part of the unit in counter-current with respect to the liquid phase.

[0021] The figure shows a basic diagram of the process of separating nitrogen isotopes in a column-type counter-current mass exchange separation unit with ammonia as the working substance.

[0022] The installation operates as follows. The flow of gaseous ammonia 3 in the separation column 2 is fed countercurrently to the liquid phase 4, containing ammonia dissolved in it in the form of a complex compound. The separation column 2 is filled with packing, on which a multi-stage mass exchange between the liquid and gaseous phases occurs, due to which the concentration of nitrogen-15 in the liquid phase occurs. The maximum concentration of the heavy nitrogen isotope is achieved at the bottom of the column. From the bottom of the separation column 2, the liquid phase 4 saturated with ammonia is fed to the heated desorber 6, in which the thermal decomposition of liquid complex compounds of ammonia and its release in gaseous form occurs. The liquid phase 5, purified from ammonia in the thermal desorber 6, is fed to the upper part of the unit, to the cooled absorber 1, where the ammonia exiting from the top of the separation column 2 is absorbed by the liquid phase, forming complex compounds.The product in the form of ammonia enriched in nitrogen-15 is collected in the lower part of the separation column, at the outlet of gaseous ammonia from thermal desorber 6. The feed flow of the separation unit with ammonia of natural isotopic composition is fed to the middle part of the separation column 2, and the waste (nitrogen-14) is removed in its upper part. Thermal energy +Q is consumed for the thermal decomposition of complex compounds of ammonia in desorber 6, and heat removal -Q must be carried out in absorber 1.

[0023] A comparison of the properties of the proposed reagents (complexing agents) in comparison with n-pentanol is given in the table.

[0024] Table. Properties of reagents that form complex compounds with ammonia

[0025] All newly proposed complexing agents, in addition to high boiling points, also have high densities and a higher specific content of hydroxyl groups in the molecule than pentanol and other alcohols containing one hydroxyl group, which significantly increases their capacity during ammonia sorption.

[0026] According to the claimed invention, the separation of nitrogen isotopes occurs in a two-phase "gas-liquid" system with one or more polyhydric alcohols and / or amino alcohols, and the working substance is ammonia. In this case, polyhydric alcohols and / or amino alcohols act in the system with chemical isotope exchange as a complexing agent, reversibly binding ammonia according to reaction (4), which is accompanied by an isotope effect.

[0027] 15 NH 3 (газ) + 14 NH3-R(OH) n (ж) ↔ 14 NH 3 (газ) + 15 NH3-R(OH) n (ж) (4)

[0028] In reaction (4), the following alcohols and amino alcohols act as ammonia complexing agents: ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin, monoethanolamine, diethanolamine, triethanolamine or mixtures containing these substances. To increase the single separation effect, chemical isotope exchange between gaseous ammonia and the liquid "ammonia-alcohol" complex is carried out in a countercurrent mass-exchange separation unit of a column type filled with packing. In this case, thermal circulation of phase flows is used in the separation unit of a column type. To do this, the liquid phase leaving the lower part of the column is heated until the ammonia is completely removed from it, after which the purified complexing agent (alcohol and / or amino alcohol) is sent to the upper part of the separation unit for irrigation, and the released gaseous ammonia is fed to the lower part of the column in countercurrent to the liquid phase.The reaction of chemical isotope exchange in the system is carried out in the temperature range from -32 to 50 °C (241-323 K) at an ammonia pressure from 133 to 1 - 10. 5 Pa. The decomposition of the complex with ammonia is carried out thermally, by heating it to a temperature of 50-300°C at a pressure of 133 to 1 • 10 5 Pa.

[0029] The invention is illustrated by the following specific examples.

[0030] Example 1. Ethylene glycol is brought into multistage countercurrent contact with ammonia in a packed column at atmospheric pressure and 20 °C (single isotope separation factor α=1.012, ammonia capacity 12.6 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 197.3 °C. The residual concentration of ammonia in the liquid after desorption is 0.15 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 670 theoretical stages.

[0031] Example 2. Ethylene glycol is brought into contact with ammonia at atmospheric pressure and 0 °C (α=1.015, ammonia capacity 23.4 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 197.3 °C. The residual concentration of ammonia in the liquid after desorption is 0.15 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 530 theoretical stages.

[0032] Example 3. Ethylene glycol is brought into contact with ammonia at atmospheric pressure and -32 °C (α=1.02, ammonia capacity 33.6 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 197.3 °C. The residual concentration of ammonia in the liquid after desorption is 0.15 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 405 theoretical stages.

[0033] Example 4. 1,2-Propylene glycol is brought into contact with ammonia at atmospheric pressure and 20 °C (α=1.011, ammonia capacity 7.5 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 184.7 °C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 720 theoretical stages.

[0034] Example 5. 1,2-Propylene glycol is brought into contact with ammonia at atmospheric pressure and 0°C (α=1.014, ammonia capacity 17.02 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 184.7 °C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 575 theoretical stages.

[0035] Example 6. 1,3-Propylene glycol is brought into contact with ammonia at 20°C (oc=1.011, ammonia capacity 10 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 214°C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm. 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 715 theoretical stages.

[0036] Example 7. Glycerol is brought into contact with ammonia at atmospheric pressure and 20°C (α=1.013, ammonia capacity 33.07 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 250°C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 605 theoretical stages.

[0037] Example 8. Monoethanolamine is brought into contact with ammonia at atmospheric pressure and 20°C (α=1.010, ammonia capacity 3.6 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 160°C. The residual concentration of ammonia in the liquid after desorption is 0.28 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 783 theoretical stages.

[0038] Example 9. Diethanolamine is brought into contact with ammonia at atmospheric pressure and 20°C (α=1.011, ammonia capacity 4.7 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 270°C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 725 theoretical stages.

[0039] Example 10. Triethanolamine is brought into contact with ammonia at atmospheric pressure and 20°C (α=1.012, ammonia capacity 5.8 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 325°C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm. 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 654 theoretical stages.

[0040] Example 11. A mixture of 10% by weight of glycerol with ethylene glycol is brought into contact with ammonia at atmospheric pressure and 20°C (α=1.013, ammonia capacity 5.8 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 200°C. The residual concentration of ammonia in the liquid after desorption is 0.1 μg / cm. 3 The production of a product with a concentration of 90% nitrogen-15 from nitrogen of natural isotopic composition occurs in a column with 605 theoretical stages.

[0041] Example 12. Pentanol-1 containing 0.001 wt. % monoethanolamine is brought into multistage countercurrent contact with ammonia in a packed column at atmospheric pressure and 20 °C (single isotope separation factor α = 1.00952, ammonia capacity 2.67 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 140 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.29 μg / cm 3 . The product with a concentration of 90% nitrogen-15 is obtained in a column with 850 theoretical stages. Example 13. Pentanol-1 containing 30 wt. % ethylene glycol is brought into multistage countercurrent contact with ammonia in a packed column at atmospheric pressure and 20 °C (single isotope separation factor α = 1.010, ammonia capacity 5.6 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 160 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.26 μg / cm 3The product with a concentration of 90% nitrogen-15 is obtained in a column with 780 theoretical stages.

[0042] Example 14. Pentanol-1 containing 1.0 wt. % 1 ,2-propylene glycol is brought into multistage countercurrent contact with ammonia in a packed column at atmospheric pressure and 20 °C (single isotope separation factor α = 1.00955, ammonia capacity 2.68 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 145 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.28 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 830 theoretical stages.

[0043] Example 15. Pentanol-1 containing 5.0 wt. % 1,3-propylene glycol is brought into multistage countercurrent contact with ammonia in a packed column at atmospheric pressure and 20 °C (single isotope separation factor α = 1.0096, ammonia capacity 2.9 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 150 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.27 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 810 theoretical stages.

[0044] Example 16. Ethylene glycol containing 0.1 wt. % glycerol is brought into contact with ammonia at atmospheric pressure and 0 °C (α=1.015, ammonia capacity 24.0 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 200 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.14 μg / cm 3. The product with a concentration of 90% nitrogen-15 is obtained in a column with 525 theoretical stages. Example 17. Ethylene glycol containing 0.1 wt. % diethanolamine is brought into contact with ammonia at atmospheric pressure and -32 °C (α=1.02, ammonia capacity 33.7 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 200 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.15 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 400 theoretical stages.

[0045] Example 18. 1 ,2-Propylene glycol containing 0.1 wt. % triethanolamine is brought into contact with ammonia at atmospheric pressure and 20 °C (α=1.011, ammonia capacity 7.5 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 190 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.11 μg / cm 3The product with a concentration of 90% nitrogen-15 is obtained in a column with 710 theoretical stages.

[0046] Example 19. 1 ,2-Propylene glycol containing 0.01 wt. % 1,3-propylene glycol is brought into contact with ammonia at atmospheric pressure and 0°C (α=1.014, ammonia capacity 17.0 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 185°C. The residual concentration of ammonia in the liquid after thermal desorption is 0.1 μg / cm 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 570 theoretical stages.

[0047] Example 20. 1,3-Propyl glycol containing 0.001 wt. % glycerol is brought into contact with ammonia at 20°C (α= 1.011, ammonia capacity 10 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 215°C. The residual concentration of ammonia in the liquid after thermal desorption is 0.1 μg / cm 3The product with a concentration of 90% nitrogen-15 is obtained in a column with 710 theoretical stages.

[0048] Example 21. Glycerol containing 0.001 wt. % triethanolamine is brought into contact with ammonia at atmospheric pressure and 20°C (α=1.013, ammonia capacity 33.2 mol / L). The complex is decomposed at atmospheric pressure at a temperature of 260°C. The residual concentration of ammonia in the liquid after thermal desorption is 0.1 μg / cm. 3 The product with a concentration of 90% nitrogen-15 is obtained in a column with 610 theoretical stages.

[0049] Example 22. Pentanol-1, containing 30 wt. % ethylene glycol and 0.1 wt. % glycerol, is brought into contact with ammonia at atmospheric pressure and 20 °C (α = 1.0105, ammonia capacity 2.7 mol / l). The complex is decomposed at atmospheric pressure at a temperature of 165 °C. The residual concentration of ammonia in the liquid after thermal desorption is 0.25 μg / cm 3The production of a product with a concentration of 90% nitrogen-15 from nitrogen of natural isotopic composition occurs in a column with 750 theoretical stages.

Claims

Invention formula 1. A method for separating nitrogen isotopes by chemical isotope exchange with ammonia as the working substance, characterized in that the separation of nitrogen isotopes is carried out in a two-phase “gas-liquid” system with a liquid phase containing one or more polyhydric alcohols and / or amino alcohols that form complex compounds with ammonia.

2. The method according to claim 1, characterized in that polyhydric alcohols from the series are used: ethylene glycol, 1,2-propylene glycol, 1,3-propyl ene glycol, glycerin and amino alcohols from the series: monoethanolamine, diethanolamine, triethanolamine or mixtures containing the above substances.

3. The method according to claim 1, characterized in that the chemical isotope exchange between gaseous ammonia and the liquid phase containing dissolved ammonia is carried out in a separating counter-current mass exchange unit of a column type filled with packing.

4. The method according to paragraph 3, characterized in that in the lower part of the separation countercurrent mass exchange unit of the column type, the liquid phase is heated until the ammonia is completely removed from it, after which the liquid phase purified from ammonia is sent to the upper part of the unit for irrigation, and the released gaseous ammonia is returned to the lower part of the unit in countercurrent with respect to the liquid phase.

Images