Process for producing ethyleneamine

Abstract

The present invention relates to a method for producing ethyleneamines from a mixture containing water (H2O), ethylenediamine (EDA), and N-methylethylenediamine (NMEDA), comprising: (i) providing a feed stream containing EDA, NMEDA, and water; and (ii) separating the feed stream provided in step (i) in one or more distillation columns into a. fraction A containing water and NMEDA, wherein the weight ratio of water to NMEDA in fraction A is greater than 100:1; b. fraction B containing water, NMEDA, and EDA, wherein the weight ratio of water to NMEDA is in the range of 1:100 to 100:1; and c. fraction C containing water and EDA, wherein the weight ratio of EDA to water is greater than 5:1).

Description

Technical Field

[0001] The present invention relates to a process for the production of ethylenediamine (EDA).

Background Art

[0002] Ethylenediamine is mainly used as an intermediate for the production of bleach activators, crop protection agents, pharmaceuticals, lubricants, fiber processing resins, polyamides, paper-making aids, gasoline additives and many other substances.

[0003] There are a number of known processes for preparing EDA (see, for example, Ullmann’s Encyclopedia of Industrial Cemistry, “Amines Aliphatic”, section 8.1.1. DOI: 10.1002 / 1436007.a02_001).

[0004] In the preparation of ethylenediamine, N-methylethylenediamine (NMEDA) can be formed by side reactions. For example, in the reaction of monoethanolamine (MEA) and ammonia to obtain EDA, the decomposition reaction of monoethanolamine can directly produce carbon monoxide (CO) and methylamine (decarbonylation). Methylamine can, in turn, react directly with further monoethanolamine to give NMEDA.

[0005] NMEDA can also occur in the dimerization of monoethanolamine to aminoethanolamine (AEEA), in which case AEEA decomposes directly by decarbonylation to NMEDA. NMEDA can also occur in the preparation of EDA from C1 units such as hydrogen cyanide and formaldehyde.

[0006] In addition to NMEDA, other poly-N-methylated ethylenediamines, such as bis(N-methyl-1,2-ethanediamine), can also occur. However, from the perspective of quantity, the formation of NMEDA is typically dominant.

[0007] For most industrial applications, the market requires a purity of at least 99.5 wt% EDA. A second organic component, such as NMEDA, may be present in a proportion of 0.5 wt% or less. Further, the water content may be 0.5 wt% or less. More particularly, in many industrial applications, the purity of EDA is defined such that the proportion of NMEDA is less than 1000 wt ppm.

[0008] As a result of its preparation, EDA with a higher water and / or NMEDA content must accordingly be worked up in order to obtain EDA with the required specifications.

[0009] The problems encountered in the separation of ethyleneamine mixtures are that EDA and water as well as NMEDA and water form azeotropic mixtures. Azeotropic mixtures cannot be separated by conventional distillation. On the other hand, the formation of the azeotropic hydrates of EDA and NMEDA can increase the boiling point difference between NMEDA and EDA and make the separation of NMEDA and EDA not difficult under the conditions where their corresponding hydrates occur.

[0010] Depending on the amount of NMEDA in the ethylenediamine mixture, different distillation strategies can be used for an ethylenediamine mixture containing NMEDA, EDA and water.

[0011] If the ethylenediamine mixture contains a large amount of NMEDA, the NMEDA is usually separated before the water is removed.

[0012] European Patent No. 2487151 (DOW) discloses a process for the drastic reduction of alkyl ethylenediamines from an ethyleneamine mixture, in which a mixture consisting of ethylenediamine, water, and one or more alkyl ethylenediamines is subjected to conditions such that an azeotropic mixture is formed between water and the alkyl ethylenediamine, and the azeotropic mixture of water and NMEDA is separated from the remaining composition. It is disclosed that the pressure of the rectification column in which the azeotropic mixture of water and the alkyl ethylenediamine is separated is in the range of 1.01 to 2.12 bar, preferably 1.5 to 1.98 bar. In Example 1, the distillation is achieved at a top pressure of 1.634 bar, a top temperature of 115 °C, and a bottom temperature of 176 °C. Apart from these technical details regarding the distillation, this disclosure does not seem to contain any further technical information regarding the means that those skilled in the art must consider so that an azeotropic mixture of alkyl ethylenediamine and water is formed.

[0013] A further process for separating NMEDA from EDA and water is disclosed in European Patent No. 2507202 (BASF). This disclosure teaches that the removal of NMEDA is achieved in a rectification column at a top pressure in the range of 0.01 bar to 4 bar, and that the mixture to be distilled contains at least an amount of water sufficient for condition H = a*X / Y to be satisfied, where H is the weight fraction of water in the mixture to be distilled, X is the weight fraction of water at the azeotropic point of the two-phase mixture of water and EDA, Y is the weight fraction of EDA, and a is a real number having a value of 0.9 or more.

[0014] International Publication No. 2019 / 081284 pamphlet (BASF) discloses a process for separating NMEDA from EDA and water, in which the NMEDA separation column is operated at a bottom temperature of 155 °C or lower, and the NMEDA separation column contains 50 to 140 theoretical plates. NMEDA is withdrawn at the top of the column, and the azeotropic mixture of EDA / water is withdrawn at the bottom of the column.

[0015] After the removal of NMEDA or when the NMEDA concentration is low from the start, the EDA / water mixture can be separated in different ways.

[0016] German Patent No. 1258413 (DOW) discloses the separation of EDA and water in a single dehydration column that is operated at a pressure at which the azeotrope between water and EDA is broken, so that water can be withdrawn at the top of the distillation column and EDA and other amines are withdrawn from the water sump.

[0017] Alternatively, EDA and water can also be separated in two columns operated at different pressures (dual-pressure distillation or pressure-swing distillation) (see Fulgueras, A.M., Poudel, J., Kim, D.S. et al. Korean J. Chem. Eng. (2016) 33:46. https: / / doi.org / 10.1007 / s11814-015-0100-4).

[0018] Several patent applications (Chinese Patent Application Publication No. 105585508 (Sinopec), Chinese Patent Application Publication No. 105585508 (Sinopec), Chinese Patent Application Publication No. 105585501 (Sinopec), Chinese Patent Application Publication No. 105585501 (Sinopec), Chinese Patent Application Publication No. 104119297 (Xi’an Modern Chemistry Research Institute), Chinese Patent Application Publication No. 104230850 (Sinopec), Chinese Patent Application Publication No. 105523943 (Sinopec)) teach the separation of water and ethylenediamine using entrainers that form low-boiling azeotropes with water, such as toluene or xylene.

[0019] U.S. Patent No. 3,055,809 (Jefferson Chemicals) discloses the distillation of an EDA / water mixture under azeotropic conditions. The water / EDA mixture is fed into the middle of a rectification column. A high-boiling extraction solvent is fed to the top of the distillation column, where it flows countercurrently to the rising azeotropic EDA / water vapor. By contact of the EDA / water with the high-boiling extractant, the EDA is essentially enriched in the extraction solvent such that essentially pure water is obtained at the top of the column and a water-depleted mixture of EDA, the extraction solvent and water is obtained at the bottom of the column. According to this invention, suitable extraction solvents are solvents having a boiling point above 120°C, such as polyhydric alcohols including glycols such as ethylene glycol (MEG), propylene glycol and butylene glycol and glycerols such as glycerin. Other effective solvents are hydroxyamines, namely alkanolamines such as monoethanolamine (MEOA), diethanolamine (DEOA), triethylamine (TEOA) and propanolamine.

[0020] International Publication No. 2021 / 115907 pamphlet (BASF) discloses the distillation of NMEDA, water and EDA in a single distillation column at a pressure at which the azeotropic mixture between EDA and water is broken. In a narrow pressure range, the separation of NMEDA, EDA and water can be carried out in a single column.

[0021] In U.S. Patent No. 4,032,411 (Berol Kemi AG), the water / EDA mixture is distilled in the presence of a distillation aid. The distillation aid is described as functioning as an azeotrope breaker. Thus, in the mixture of water, EDA, and the distillation aid, the azeotrope between water and EDA is broken so that water can be removed overhead and the mixture of EDA and the distillation aid can be removed at the bottom of the distillation column. The following compounds: PIP, DETA, AEEA, AEP, and mixtures thereof are disclosed as suitable distillation aids. The distillation is carried out at a pressure of about 1 to 3 bar at a bottom temperature of the distillation column that varies from 140 to 210 °C. According to the present invention, the weight ratio between the distillation aid and EDA should be in the range of about 2:8 to 9:1, preferably about 4:6 to 8:2, so that the distillation is carried out under technically appropriate conditions that enable the removal of water from EDA without the formation of an azeotrope. According to the present invention, when preparing EDA having a very low water content of less than 2% by weight, otherwise a very high distillation temperature would be required, which could lead to the decomposition of the amino compound, and the column would require a large number of theoretical plates, so it is preferred to carry out the distillation in two or more distillation columns. Thus, a preferred embodiment of the invention of U.S. Patent No. 4,032,411 includes the steps of first removing the major part of the water present in the aqueous EDA solution by carrying out distillation in the presence of one or more aids, subsequently removing the aid, and finally carrying out vacuum distillation to remove additional water.

[0022] Depending on the composition of the ethyleneamine mixture, the separation of the components to obtain EDDA within specifications is difficult but rewarding. When distilling under azeotropic conditions to remove NMEDA, the ratio of water to NMEDA and EDA needs to be controlled to achieve azeotropic conditions. Due to the small difference in boiling points between NMEDA and EDA and their corresponding azeotropes, a distillation column with many trays may be required. The use of entrainers, distillation aids, or extraction solvents may require the addition of additional components that may need to be removed from the final product. Distillation under non-azeotropic conditions without the addition of entrainers, aids, or extraction solvents usually requires a high operating pressure of the distillation column.

Summary of the Invention

Problems to be Solved by the Invention

[0023] Therefore, there is a continuing need for a process for the production of EDA within specifications using an economical distillation process having a reasonable number of columns, which columns can be operated with a reasonable number of trays and at reasonable temperatures and pressures. There is also a continuing need for a process that avoids components that are not generated or converted within the process itself. The use of such additional components requires larger sizing of the equipment to handle the additional components, and the additional components typically need to be separated in additional steps to enable recycling of such adjuvants to the process. The object of the present invention is, therefore, to provide a production process for EDA using a reasonable number of distillation columns, rationally sized columns, and operation of such columns under reasonable conditions such as temperature and pressure, which process, with respect to the means described above, finds a suitable balance between operating costs, capital investment, and product quality.

Means for Solving the Problems

[0024] The object of the present invention is a method for producing ethylenediamine from a mixture containing water (H2O), ethylenediamine (EDA) and N-methylethylenediamine (NMEDA), comprising: (i) providing a feed stream containing EDA, NMEDA and water; (ii) subjecting the feed stream provided in step (i) to one or more distillation columns to a. fraction A containing water and NMEDA, wherein the weight ratio of water to NMEDA in fraction A is greater than 100:1; b. fraction B containing water, NMEDA and EDA, wherein the weight ratio of water to NMEDA is in the range of 1:100 to 100:1; and c. fraction C containing water and EDA, wherein the weight ratio of EDA to water is greater than 5:1 It was achieved by a method including the step of separating into.

[0025] Surprisingly, when separating the feed into the fractions according to the invention, the downstream separation step can be adjusted to enable an economic separation of the feed into the desired valuable components and to obtain the desired valuable components in high quality. Furthermore, it has been found that an efficient recycling of materials can be achieved in the separation of the feed into the fractions according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The following abbreviations are used in this specification: AEEA: Aminoethylethanolamine AEP: Aminoethylpiperazine DEOA: Diethanolamine DETA: Diethylenetriamine EDA: Ethylenediamine EDC: Ethylene dichloride HEDETA: Hydroxyethyldiethylenetriamine HEPIP: Hydroxyethylpiperazine HPA: Heavy polyamine MEOA: Monoethanolamine MEG: Monoethylene glycol NMEDA: N-Methylethylenediamine PEHA: Pentaethylenehexamine PIP: Piperazine TEPA: Tetraethylenepentamine TETA: Triethylenetetramine

[0027] Unless otherwise specified, pressure figures relate to absolute pressure figures.

[0028] The term ethyleneamine as used in this specification refers to ethylenediamine (EDA) and the general formula (I): R-CH2-CH2-NH2 (I) [wherein, R is the formula -(NH-CH2-CH2) X-NH2 (where x is an integer in the range of 1 to 4, preferably 1 to 3, and most preferably 1 to 2). Preferably, the reaction output contains DETA, TETA, and TEPA, more preferably DETA and TETA, and most preferably DETA] its linear homologues; and General formula (II):

Chemical formula

[0029] Examples of linear ethyleneamines are DETA, TETA, TEPA, and HEPA.

[0030] Examples of cyclic ethyleneamines are PIP and AEPIP.

[0031] As used herein, the term ethanolamine refers to monoethanolamine (MEOA) and the general formula (III): R-CH2-CH2-OH (III) [wherein R is a group of the formula -(NH-CH2-CH2) X -NH2 (where x is an integer in the range of 1 to 4, preferably 1 to 3, and most preferably 1 to 2) and includes its linear homologues.

[0032] Examples of higher linear ethanolamines are AEEA and HEDETA.

[0033] As used herein, the term ethanolamine as such refers to formula (IV)

Chemical formula

[0034] An example of the cyclic ethanolamine is hydroxyethylpiperazine (HEPIP).

[0035] Step (i): Providing a feed stream containing EDA, NMEDA and water: The method according to the invention includes step (i) of providing a feed stream containing EDA, NMEDA and water.

[0036] In a preferred embodiment, the provision of the feed containing EDA, NMEDA and water in step (i) is: (i-a) performing an EDA preparation process to obtain an output containing EDA, NMEDA and water; (i-b) removing ammonia and / or hydrogen from the output generated in step (i-a); (i-c) optionally adding additional adjuvants and.

[0037] Step (i-a): EDA preparation process: The feed provided in step (i) is preferably provided by subjecting an EDA preparation process to jealousy.

[0038] The EDA preparation process in step (i-a) can be any known manufacturing process of EDA, such as the MEOA process, C1-process, EDC process, or MEG process, as follows.

[0039] MEOA process: The reaction of MEOA with ammonia is described, for example, in U.S. Patent No. 2,861,995, German Patent Application Publication No. A-1172268, and U.S. Patent No. 3,112,318. An overview of various process variations of the reaction of MEA with ammonia can be found, for example, in PERP Report No. 138, "Alkyl-Amines", SRI International, 03 / 1981 (especially pages 81-99, 117).

[0040] The reaction of MEOA with ammonia is preferably carried out in a fixed-bed reactor on a transition metal catalyst at 150-250 bar and 160-210 °C, or on a zeolite catalyst at 1-20 bar and 280-380 °C.

[0041] The preferably used transition metal catalysts include Ni, Co, Cu, Ru, Re, Rh, Pd, or Pt on an oxide support (e.g., Al2O3, TiO2, ZrO2, SiO2), or a mixture of two or more of these metals.

[0042] Preferred zeolite catalysts are mordenite, faujasite, and chabazite.

[0043] To achieve the maximum EDA selectivity, a molar ratio of ammonia to MEOA of 6-20, preferably 8-15, is generally used for the transition metal catalyst, and a molar ratio of generally 20-80, preferably 30-50, is used for the zeolite catalyst.

[0044] The MEOA conversion rate is generally maintained at 10%-80%, preferably 40-60%.

[0045] In continuous operation, preferably, a catalyst space velocity in the range of 0.3 to 0.6 kg / (kg·h) (kg of MEOA per kg of catalyst per hour) is established.

[0046] When a metal catalyst is used to maintain catalyst activity, it is preferable to further supply 0.05 to 0.5 wt% (based on the MEOA + NH3 + H2 reaction input) of hydrogen into the reactor.

[0047] C1 process: The EDA preparation process in step (i-a) can also be a C1 process in which formaldehyde, hydrogen cyanide, ammonia, and hydrogen are converted to EDA.

[0048] For example, U.S. Patent No. 2,519,803 describes a process for preparing EDA by hydrogenation of a partially purified aqueous reaction mixture containing aminoacetonitrile resulting from the amination of formaldehyde cyanohydrin (FACH) and as an intermediate. Formaldehyde cyanohydrin can be obtained, in turn, by the reaction of formaldehyde and hydrogen cyanide. The process description for the preparation of FACH can be found, for example, in Application PCT / EP2008 / 052337, page 26, and International Publication No. A1-2008 / 104582 pamphlet, page 30 (Variants A) and B)), which are hereby expressly incorporated by reference.

[0049] German Patent Application Publication No. A1154121 relates to a further process for preparing EDA in which hydrogen cyanide, formaldehyde, ammonia, and hydrogen reactants are reacted in the presence of a catalyst in a "one-pot" process.

[0050] International Publication No. A1-2008 / 104592 pamphlet relates to a process for preparing EDA by hydrogenation of aminoacetonitrile. Aminoacetonitrile is typically obtained by the reaction of formaldehyde cyanohydrin and ammonia, where formaldehyde cyanohydrin is generally prepared in turn from hydrogen cyanide and ammonia.

[0051] Preferably, the reaction output containing EDA and NMEDA is prepared by the process described in International Publication No. A-2008 / 104592 pamphlet, which is hereby expressly incorporated by reference herein.

[0052] EDC process: EDA can also be prepared by the reaction of ethylene dichloride and ammonia (EDC process). The reaction of EDC and ammonia is described, for example, in European Patent No. 2346809 specification, in the above-mentioned PERP Report and in the references cited therein.

[0053] MEG process In a particularly preferred embodiment, the feed provided in step (i) is obtained by the conversion of MEG with ammonia in the presence of an amination catalyst and hydrogen. The reaction of MEG and ammonia can be carried out in the liquid phase or the gas phase. The gas-phase reaction is disclosed, for example, in Chinese Patent Application Publication No. 102190588 specification and Chinese Patent Application Publication No. 102233272 specification.

[0054] Preferably, the conversion of MEG with ammonia is carried out in the liquid phase according to U.S. Patent No. 4,111,840, U.S. Patent No. 3,137,730, German Patent No. 1 72 268, International Publication No. WO 2007 / 093514, International Publication No. WO 2007 / 093552, International Publication No. WO 2018 / 224316, International Publication No. WO 2018 / 224315, International Publication No. WO 2018 / 224321, International Publication No. WO 2019 / 081283, International Publication No. WO 2019 / 081285 and International Publication No. WO 2020 / 17085, which are hereby expressly incorporated by reference.

[0055] In a particularly preferred embodiment (MEG process), the feed provided in step (i) is obtained by the conversion of MEG with ammonia in the presence of an amination catalyst and hydrogen.

[0056] The MEG used in this process can be prepared from ethylene obtainable from petrochemical processes. For example, generally, ethylene is oxidized to ethylene oxide in a first step, which is then reacted with water to give MEG.

[0057] Ethylene oxide can alternatively also be reacted with carbon dioxide in a process called the omega process to give ethylene carbonate, which can be hydrolyzed with water to give MEG. The omega process is characterized by a higher selectivity for MEG since fewer by-products such as di- and triethylene glycol are formed.

[0058] The ethylene used for the preparation of MEG can alternatively also be prepared from renewable raw materials. For example, ethylene can be formed by dehydration from bioethanol.

[0059] MEG can also be prepared by the synthesis gas route, for example, by the oxidative carbonylation of methanol to obtain dimethyl oxalate and subsequent hydrogenation thereof. Thus, additional possible petrochemical raw materials for the preparation of MEG are also natural gas or coal.

[0060] MEG obtained from the recycling of PET by various methods such as glycolysis, methanolysis, hydrolysis, saponification, and pyrolysis can also be used.

[0061] In the MEG process, MEG and optionally additional MEOA are reacted with ammonia. Although additional MEOA can be added as an additional free entity, it is preferred to carry out the MEG process without additional MEOA.

[0062] The ammonia used can be conventional commercially available ammonia, for example, ammonia with an ammonia content of more than 98% by weight, preferably more than 99% by weight, preferably more than 99.5% by weight, especially more than 99.8% by weight.

[0063] The MEG process is preferably carried out in the presence of hydrogen.

[0064] Hydrogen is generally used in industrial grade purity. Hydrogen can also be used in the form of a hydrogen-containing gas, that is, by adding other inert gases such as nitrogen, helium, neon, argon, or carbon dioxide. The hydrogen-containing gas used can be, for example, reformer offgas, refinery gas, etc., provided that these gases do not contain any catalyst poisons for the catalyst used, such as sulfur components like H2S or CO. However, it is preferred to use pure hydrogen or essentially pure hydrogen in this process, for example, hydrogen having a hydrogen content of more than 99% by weight, preferably more than 99.9% by weight, more preferably more than 99.99% by weight, especially more than 99.999% by weight.

[0065] In the MEG process, MEG is preferably reacted with ammonia and an amination catalyst in the liquid phase.

[0066] Preferred amination catalysts for the MEG process are - the nickel-rhenium catalyst disclosed in U.S. Patent No. 4,111,840, - the nickel-copper catalyst disclosed in U.S. Patent No. 3,137,730, - the ruthenium-cobalt catalyst disclosed in International Publication No. 2007 / 093514 pamphlet, - the catalyst containing cobalt, ruthenium and tin disclosed in International Publication No. 2018 / 224316 pamphlet, - the catalyst containing tin and a further active metal disclosed in International Publication No. 2018 / 224315 pamphlet, - the impregnated catalyst disclosed in International Publication No. 2018 / 224321 pamphlet, or - the rhenium-containing catalyst disclosed in International Publication No. 2020 / 017085 pamphlet and they are hereby expressly incorporated by reference into this specification. The catalysts disclosed in the examples of the above-referenced documents are particularly preferred.

[0067] In the present situation, "reaction in the liquid phase" means that the reaction conditions, such as pressure and temperature, are adjusted so that ethylene glycol is present in the liquid phase and flows around the amination catalyst in liquid form.

[0068] The reaction of MEG and / or MEOA with ammonia can be carried out continuously or batchwise. A continuous reaction is preferred.

[0069] A suitable reactor for the reaction in the liquid phase is generally a tubular reactor. The catalyst can be arranged as a moving bed or a solid bed in the tubular reactor.

[0070] It is particularly preferred to react MEG and / or MEOA with NH3 in a tubular reactor in which the amination catalyst is arranged in the form of a fixed bed.

[0071] When the catalyst is arranged in the form of a fixed bed, mixing the catalyst in the reactor with an inert random packing, so to speak, "diluting" it can be advantageous for the selectivity of the reaction. The proportion of random packing in such catalyst preparation can be 20 to 80, preferably 30 to 60, more preferably 40 to 50 parts by volume. Preferably, the catalyst is not diluted.

[0072] Alternatively, the reaction is preferably carried out in a shell and tube reactor or in a single stream plant. In a single stream plant, the tubular reactor in which the reaction is carried out can consist of a series connection of a plurality of (for example, two or three) individual tubular reactors. Possible and advantageous options here are the intermediate introduction of the feed (reactant and / or ammonia and / or H2) and / or the recycle gas and / or the reactor output from the downstream reactor.

[0073] When working in the liquid phase, MEG and / or MEOA plus ammonia are generally at a pressure of 5 to 35 MPa (50 to 350 mbar), preferably 5 to 30 MPa, more preferably 15 to 28 MPa, and generally at a temperature of 80 to 350 °C, especially 100 to 300 °C, preferably 120 to 270 °C, more preferably 130 to 250 °C, particularly 160 to 230 °C. Typically, preferably in an externally heated fixed bed reactor, they are simultaneously introduced in the liquid phase onto the catalyst, containing hydrogen.

[0074] The hydrogen partial pressure is preferably 0.25 to 20 MPa (2.5 to 200 bar), more preferably 0.5 to 15 MPa (5 to 150 bar), even more preferably 1 to 10 MPa (10 to 100 bar), particularly preferably 2 to 5 MPa (20 to 50 bar).

[0075] MEG and / or MEA and ammonia are preferably fed to the reactor in liquid form and brought into contact with the amination catalyst in liquid form.

[0076] Either dripping mode or liquid phase mode is possible.

[0077] It is advantageous to heat the reactants to the reaction temperature, preferably even before they are fed into the reaction vessel.

[0078] Ammonia is preferably used in a molar amount of 0.90 to 100 times, especially 1.0 to 20 times the molar amount, based on the MEG or MEA used in each case.

[0079] The catalyst space velocity is generally in the range of 0.05 to 5.0, preferably 0.1 to, more preferably 0.2 to 1 kg (MEG + MEA) per kg of catalyst per hour.

[0080] In a particularly preferred embodiment, the conversion of MEG to ethylenediamine, especially EDA, and ethanolamine is incomplete such that unreacted MEG remains in the reactor effluent. The MEG conversion rate is generally in the range of 5 to 80%, preferably 10 to 70%, more preferably 30 to 50%. The incomplete conversion of MEG has the advantage that the unreacted MEG can facilitate the separation of the present invention of EDA, NMEDA and water and function as a distillation aid as described below.

[0081] The conversion of MEG is generally carried out in such a way that the feed provided in step (ii) contains MEG in the amounts specified below. The degree of conversion can be adjusted by changes in operating parameters such as the temperature of the reaction, the amount of ammonia added and the catalyst space velocity. A decrease in the space velocity usually increases the degree of conversion of MEG to MEOA and EDA.

[0082] Composite MEG - MEOA process: In a preferred embodiment of the present invention, the feed provided in step (i) is (i) Convert ethylene glycol (MEG) to ammonia in the presence of an amination catalyst and hydrogen in a first reactor (MEG reactor) to obtain a reaction effluent containing water, ethylenediamine (EDA), monoethanolamine (MEOA), unconverted MEG and other components having a boiling point higher than EDA and optionally NMEDA; (ii) Separating MEOA from the reaction effluent obtained in (i); (iii) Converting the MEOA separated in step (ii) to ammonia in the presence of an amination catalyst and hydrogen in a second reactor (MEOA reactor) to obtain a reaction effluent containing water, ethylenediamine (EDA), unconverted monoethanolamine (MEOA) and other components having a boiling point higher than EDA and optionally NMEDA; It is obtained by:

[0083] When MEOA in the reactor effluent of MEG conversion is separated and converted in a separate reactor using a tailored catalyst under adjusted process conditions, the overall yield and selectivity to EDA are improved. The MEOA conversion step is preferably carried out under the conditions described above for the MEOA process.

[0084] Separation of one or more MEO fractions can be carried out according to the following separation sequence.

[0085] In a more preferred embodiment, the MEG-MEOA process (iv) Separating MEG from the reaction effluent obtained in step (i); (v) Recycling the MEG separated in step (iv) to step (i) including the additional steps of:

[0086] Separation of one or more MEG fractions can be carried out according to the following separation sequence.

[0087] The reaction effluent of the MEG reactor and the effluent of the MEOA reactor are preferably combined to separate their components in a common work-up section. The use of a common separation sequence has the advantage of reducing equipment costs and energy requirements.

[0088] The provision of the feed in step (i) using the MEG process and the separation of the produced MEOA and the subsequent conversion of the separated MEOA in the MEOA process have the advantage of increasing the overall selectivity and yield of EDA compared to producing the same amount of EDA in either a single MEOA reactor or a single MEG reactor.

[0089] The operation of the MEG reactor and the subsequent MEOA reactor allows for efficient recycling of unconverted MEOA.

[0090] Step (i-b): Removal of ammonia and / or hydrogen from the output obtained in step (i-a): The reaction effluent from the above preparation process generally contains ammonia and hydrogen.

[0091] Before feeding the output from these processes to the separation step (ii), ammonia and / or hydrogen are preferably removed.

[0092] The amount of ammonia in the reaction output is typically in the range of 30 wt% to 90 wt%, more preferably in the range of 40 wt% to 85 wt%, and most preferably in the range of 50 wt% to 80 wt%.

[0093] The amount of hydrogen in the reaction effluent is preferably in the range of 0.01 to 20 wt%, more preferably in the range of 0.05 to 10 wt%, and most preferably in the range of 0.1 to 5 wt%.

[0094] Hydrogen and ammonia can be separated from the reaction mixture by methods known to those skilled in the art.

[0095] In a particularly preferred embodiment, the removal of ammonia and / or hydrogen is carried out according to the process disclosed in the section entitled "Ammoniakabtrennung-Stufe 2" (i.e., "Ammonia Separation-Step 2" in English) in WO 2019 / 081285 pamphlet, or in the section entitled "Ammoniakabtrennung-Stufe 2" (i.e., "Ammonia Separation-Step 2" in English) in WO 2019 / 081283 pamphlet, which are hereby expressly incorporated by reference into this specification.

[0096] The composition of the feed provided in step (i) The feed provided from step (i) contains NMEDA, water and EDA.

[0097] Preferably, the feed contains 0.001 to 1 wt%, more preferably 0.01 to 0.5 wt%, and most preferably 0.02 to 0.1 wt% of NMEDA.

[0098] The amount of EDA in the feed is preferably 1 to 30 wt%, more preferably 3 to 25 wt%, and most preferably 5 to 20 wt%.

[0099] Preferably, the feed contains 1 to 30 wt%, more preferably 2.5 to 25 wt%, and most preferably 5 to 20 wt% of water.

[0100] The feed provided from step (i) preferably contains 0.1 wt% or less, more preferably 0.01 wt% or less, and most preferably 0.001 wt% or less of ammonia.

[0101] The feed provided in step (ii) preferably contains 0.1 wt% or less, more preferably 0.01 wt% or less, and most preferably 0.001 wt% or less of hydrogen.

[0102] The feed provided from step (i) preferably contains other ethyleneamines and ethanolamines, especially ethyleneamines and ethanolamines having a boiling point higher than that of EDA, particularly PIP, MEOA, DETA, TETA, AEP, HEPIP, AEEA and HEDETA. More preferably, the feed provided in step (i) contains MEOA in an amount of preferably 1 to 30% by weight, more preferably 3 to 25% by weight, most preferably 5 to 20% by weight.

[0103] Preferably, the feed provided in step (i) contains one or more ethyleneamines or ethanolamines having a boiling point higher than that of EDA selected from the group consisting of PIP, DETA, AEPIP, HEPIP, AEEA, DEOA, TETA and HEDETA. The concentration of each selected ethyleneamine or ethanolamine is preferably in the range of 0.001 to 5% by weight, more preferably 0.01 to 3% by weight, more preferably 0.03 to 2.5% by weight.

[0104] When the feed provided in step (i) is obtained by the above MEG process, the feed (i) provided in step (i) preferably contains 20 to 90% by weight of MEG, more preferably 25 to 80% by weight, more preferably 30 to 70% by weight of MEG.

[0105] When the feed provided in step (i) is obtained by the MEG process, the feed preferably also contains 1 to 50% by weight of MEOA, more preferably 3 to 30% by weight, more preferably 5 to 25% by weight of MEOA.

[0106] As shown above, the MEG content is preferably adjusted by the conversion degree of MEG in the MEG process.

[0107] In a particularly preferred embodiment, the feed provided in step (i) is Water: 10 - 20% by weight; NMEDA: 0.01 - 0.1% by weight; EDA: 10 - 25% by weight; PIP: 0.1 - 5% by weight; MEOA: 10 - 20% by weight; MEG: 30 - 50% by weight; DETA: 0.1 - 5% by weight; AEPIP: 0.05 - 0.5% by weight; AEEA: 0.1 - 5% by weight; HEPIP: 0.01 - 0.5% by weight; DEOA: 0.05 - 1% by weight; TETA: 0.01 - 2% by weight; HEDETA: 0.01 - 2% by weight; Others: 0.001 - 5% by weight and contains

[0108] Step (i - c): Optional addition of additional adjuvants: As follows, the separation step (ii) is preferably carried out under conditions such that the formation of the azeotropic mixture between EDA and water and / or between NMEDA and water is broken, impaired, or otherwise corrected in such a way that water can be separated from EDA and / or NMEDA as a low - boiling fraction. Further, as follows, the formation of the azeotropic mixture can be corrected by carrying out the separation step (ii) under a high pressure such that the azeotropic mixture between EDA and water, such as the pressure applied in German Patent No. 1258413 (DOW) or International Publication No. 2021 / 115907 pamphlet (BASF), is broken.

[0109] Alternatively, the formation of an azeotropic mixture between EDA and water can be modified if the feed provided in step (i) contains an auxiliary agent selected from the group consisting of certain ethylene amines and ethanol amines, in particular PIP, DETA, AEEA, AEP and mixtures thereof as disclosed in US Patent No. 4,032,411 (Berol Kemi AG).

[0110] Within the framework of the present invention, it has now been found that the formation of an azeotropic mixture can be efficiently broken, impaired or otherwise modified in the manner indicated above if the feed provided in step (i) contains one or more additional auxiliary agents.

[0111] The term additional auxiliary agent, when used in the context of the present invention, refers to an auxiliary agent that is not claimed as an additional auxiliary agent and is not an ethylene amine or ethanol amine, in particular not an ethylene amine and ethanol amine selected from the group consisting of PIP, DETA, AEEA, AEP and mixtures thereof as disclosed in US Patent No. 4,032,411 (Berol Kemi AG).

[0112] The additional auxiliary agent is preferably a hydroxyl group-containing compound.

[0113] The additional auxiliary agent is more preferably (i) an aliphatic monool, (ii) an aliphatic diol; (iii) an aliphatic triol; and (iv) an aliphatic tetrol selected from the group consisting of compounds, or mixtures of compounds.

[0114] Surprisingly, the azeotropic mixtures between EDA and water and / or between NMEDA and water can be effectively modified by these additional adjuvants such that the separation step (ii) can be carried out under ambient pressure or a pressure slightly below atmospheric pressure, which is easier to achieve than the high pressures for breaking the azeotropic mixtures disclosed in German Patent No. 1258413 (DOW) or International Publication No. 2021 / 115907 Pamphlet (BASF) in another way.

[0115] Preferred aliphatic monools are linear or branched alcohols having one hydroxyl group and containing 5 to 12 carbon atoms.

[0116] Particularly preferred aliphatic monools are 1-pentanol, 3-methyl-1-butanol, 2,2-dimethyl-1-propanol, cyclopentanol, 1-hexanol, cyclohexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol and 1-dodecanol.

[0117] Preferred aliphatic diols are linear or branched aliphatic diols containing 2 to 6 carbon atoms. In particular, preferred aliphatic diols are ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol.

[0118] More preferred diols are ethylene glycols, propylene glycols, and butylene glycols consisting of 2 to 4 ethylene glycol, propylene glycol, or butylene glycol units, such as diethylene glycol, triethylene glycol, di-1,2-propylene glycol, tri-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propylene glycol, di-1,4-butanediol, tri-1,4-butanediol, di-1,2-butanediol, tri-1,2-butanediol, di-1,3-butanediol, and tri-1,3-butanediol.

[0119] The most preferred aliphatic diols are 1,2-diols, especially ethylene glycol, 1,2-propylene glycol, and 1,2-butanediol. Compounds having vicinal hydroxyl groups are thought to interact particularly well with EDA and to be able to modify in another way the azeotropic mixture formed between EDA and water.

[0120] Preferred aliphatic triols contain 3 to 6 carbon atoms. Particularly preferred aliphatic triols are glycerin and trimethylolpropane.

[0121] Preferred aliphatic tetraols contain 4 to 6 carbon atoms. Particularly preferred aliphatic tetraols are pentaerythritol, erythritol, or threitol.

[0122] More preferably, the additional adjuvant containing one or more hydroxyl groups has a boiling point higher than that of EDA or NMEDA, but is a compound that can still be separated from ethyleneamine and ethanolamine using reasonable conditions. This has the advantage that such adjuvants do not evaporate before or together with the separation of NMDEA or EDA, so that their azeotropic mixture modification effect remains effective until NMEDA is effectively separated.

[0123] Furthermore, the additional auxiliary agent is preferably an aliphatic hydroxyl group-containing compound for avoiding discoloration.

[0124] Furthermore, the additional auxiliary agent is preferably miscible with the output obtained by the EDA preparation process.

[0125] The amount of the additional auxiliary agent containing one or more hydroxyl groups in the feed provided in step (i) is preferably adjusted in such a way that the molar ratio of the total hydroxyl groups (n(OH)) present in the feed to the amount of EDA (n(OH):n(EDA)) is 0.7:1 or more, preferably 1:1 or more, more preferably 1.5:1 or more, even more preferably 2:1 or more, and most preferably 4:1 or more.

[0126] When the auxiliary agent is an aliphatic diol, particularly a 1,2-diol such as MEG, the molar ratio of the diol to EDA is preferably 1:1 or more, more preferably 1.2:1 or more, even more preferably 1.5:1 or more, and most preferably 2:1 or more. The higher the ratio of the OH group to the amine group of EDA, the higher the azeotropic mixture correction effect.

[0127] The amount of the additional auxiliary agent is preferably adjusted by measuring the hydroxyl group concentration or diol concentration and the EDA concentration in the feed and adding the additional auxiliary agent.

[0128] When the additional auxiliary agent is not MEG, the amount of the additional auxiliary agent is preferably adjusted by adding the additional auxiliary agent before the separation step (ii) and preferably after the removal of ammonia and / or hydrogen, so that the hydroxyl groups of the additional auxiliary agent are not aminated during the EDA adjustment step (i-a).

[0129] When the additional auxiliary agent is MEG, the amount of the additional auxiliary agent is preferably adjusted by the conversion degree of MEG with ammonia in the MEG process as described above.

[0130] The most preferred additional adjuvants are 1,2 - diols and triethylene glycol (TEG). Particularly preferred 1,2 - diols are MEG, 1,2 - propylene glycol and 1,2 - butylene glycol. MEG has the advantage of also being a raw material for the production of EDA. When MEG is used as an additional adjuvant, the amount of the additional adjuvant in the feed can be adjusted by controlling the conversion rate of MEG in the reaction of MEG with ammonia as shown above.

[0131] TEG has the advantage of being preferably used as a distillation adjuvant for separating DETA from MEOA. The use of TEG has the advantage that TEG can be used not only as an adjuvant for DETA / MEOA separation, but also finds additional use in the separation of NMEDA from EDA and water. Thus, only one adjuvant is required for both separations.

[0132] Separation step (ii): The feed provided in step (i) is, in step (ii): a. Fraction A containing water and NMEDA, where the weight ratio of water to NMEDA in fraction A is greater than 100:1; b. Fraction B containing water, NMEDA and EDA, where the weight ratio of water to NMEDA is in the range of 1:100 to 100:1; and c. Fraction C containing water and EDA, where the weight ratio of EDA to water is greater than 5:1 is separated into.

[0133] As described above, separation step (ii) is preferably carried out under conditions such that the formation of azeotropic mixtures between EDA and water and / or between NMEDA and water is broken, impaired or otherwise corrected in such a way that water can be separated from EDA and / or NMEDA as a low - boiling fraction.

[0134] As an alternative, the formation of the azeotrope can be corrected by carrying out the separation step (ii) under a high pressure at which the azeotrope between EDA and water is broken, such as the pressure applied in German Patent No. 1258413 (DOW) or International Publication No. 2021 / 115907 pamphlet (BASF). Such a pressure is preferably in the range of 4 bar or more, more preferably 4.5 bar or more, and most preferably 5 bar or more. In a particularly preferred embodiment, the separation step is carried out at a pressure in the range of 5 to 7.5 bar, more preferably 5.1 to 7.0 bar, more preferably 5.2 to 6.5 bar, and most preferably 5.5 to 6.0 bar.

[0135] Alternatively, the formation of the azeotrope between EDA and water can be corrected when the feed provided in step (i) contains an auxiliary agent selected from the group consisting of specific ethyleneamines and ethanolamines, in particular PIP, DETA, AEEA, AEP and mixtures thereof, as disclosed in US Patent No. 4032411 (Berol Kemi AG).

[0136] In a particularly preferred embodiment, the formation of the azeotrope is corrected by providing a feed in step (i) containing one or more of the additional auxiliary agents as specified above.

[0137] In a particularly preferred embodiment of the present invention, the separation step (ii) is carried out at a pressure lower than that normally required to break the EDA-water azeotrope described in German Patent No. 1258413 or International Publication No. 2021 / 115907 pamphlet. This has the advantage that the operating costs and equipment investment for separation carried out under low to medium pressure are considerably lower than those for distillation carried out at high pressure.

[0138] Preferably, the separation step (ii) is carried out at a pressure of 4 bar or less, more preferably 3 bar or less, even more preferably 2 bar or less, and most preferably 1.5 bar or less.

[0139] More preferably, the separation step (ii) is carried out at a pressure in the range of 50 mbar to 4 bar, more preferably 200 mbar to 3 bar, and most preferably 670 mbar to 1.5 bar.

[0140] Preferably, the pressure is maintained in a range such that the bottom temperature of the first column in which step (ii) is carried out is 165 °C or lower, preferably 160 °C or lower, and most preferably 155 °C or lower.

[0141] NMEDA Removal Column - 1 Column Setup In a preferred embodiment, the separation in step (ii) is carried out in one distillation column (NMEDA removal column) where fraction A is withdrawn at the top of the distillation column, fraction B is withdrawn as a side fraction, and fraction C is withdrawn at the bottom.

[0142] The separation step (ii) according to the present invention can be carried out in a rectification apparatus such as a tray column, for example, a bubble cap tray column, a perforated plate column, a dual flow tray column, a valve tray column, a baffle tray column, etc., or a column having random packing or structured packing. It is preferable to use internal structures with low pressure drop, such as structured packing in the form of, for example, sheet metal packing like Mellapak 250 Y or Montz Pak (type B1 - 250). It is also possible for there to be packing with a lower or increased specific surface area, or it is possible to use packing with another surface shape such as cloth packing or Mellapak 252.Y. The advantages of using such internal structures are, for example, lower pressure drop and lower specific liquid hold - up compared to valve trays. In a preferred embodiment, the NMEDA removal column is a dividing wall column.

[0143] The internal structures can be arranged in one or more beds.

[0144] Preferably, the rectification column includes structured packing, particularly Mellapak 250.

[0145] The design and layout of the NMEDA removal column are determined by the capacity to be produced. Typically, the NMEDA removal column has a diameter of 0.5 to 2.5 m, preferably 0.8 to 2 m, most preferably 1 to 1.5 m and a bed height of 5 to 20 m, preferably 7 to 15 m, most preferably 8 to 12 m.

[0146] The number of theoretical plates of the NMEDA removal column generally ranges from 10 to 40, preferably from 15 to 35, more preferably from 20 to 30.

[0147] The energy required for the separation of the feed provided in step (i) in the NMEDA removal column is typically introduced by an evaporator at the bottom of the column. This evaporator is typically a natural circulation evaporator or a forced circulation evaporator. Alternatively, it is also possible to use an evaporator with a short residence time, such as a falling film evaporator, a helical coil evaporator, a wiped film evaporator, or a short path evaporator.

[0148] The feed provided in step (i) containing EDA, NMEDA and water is preferably introduced in the space region between 25% and 75% of the theoretical plates of the NMEDA removal column. For example, the feed can be introduced into the middle section of the column. Preferably, the feed is preferably introduced between 25% and 75% of the theoretical plates, more preferably between 30% and 70% of the theoretical plates. For example, if the column has 25 theoretical plates, the feed is preferably introduced between stages 10 and 15.

[0149] The NMEDA removal column generally has a condenser which is generally operated at a temperature at which the major part of fraction A condenses at the corresponding top pressure.

[0150] Generally, the operating temperature of the condenser ranges from 10 to 150 °C, preferably from 50 to 140 °C, more preferably from 80 to 120 °C.

[0151] Suitable condensers are condensers with cooling coils or helical tubes, jacketed tube condensers and shell and tube heat exchangers.

[0152] As described above, the top pressure of the NMEDA removal column is preferably 4 bar or less, more preferably 3 bar or less, even more preferably 2 bar or less, and most preferably 1.5 bar or less. The preferred range of the top pressure in the NMEDA removal column is in the range of 50 mbar to 4 bar, more preferably 200 mbar to 3 bar, and most preferably 670 mbar to 1.5 bar.

[0153] The NMEDA removal column can be operated at a bottom temperature of 80 to 220 °C, more preferably 100 to 200 °C, and even more preferably 130 to 190 °C.

[0154] In a preferred embodiment, the bottom temperature of the NMEDA removal column is 190 °C or less, preferably 165 °C or less, and most preferably 155 °C or less. When the bottom temperature does not exceed such a value, the EDA loss in fractions A and B can be further reduced.

[0155] The energy required for the evaporation of the feed provided in step (i) in the NMEDA removal column is typically introduced by a reboiler at the bottom of the column. This reboiler is typically a natural circulation reboiler or a forced circulation reboiler. Alternatively, it is also possible to use a reboiler with a short residence time, such as a falling film reboiler, a spiral tube reboiler, a wiped film reboiler, or a short path reboiler.

[0156] Fraction A containing water and NMEDA (where the weight ratio of water to NMEDA in fraction A is greater than 100:1) is preferably withdrawn at the top of the NMEDA removal column. More preferably, the weight ratio of water to NMEDA in fraction A is greater than 500:1, even more preferably greater than 1000:1, and most preferably greater than 2000:1.

[0157] Preferably, fraction A contains NMEDA at 0.1 wt% or less, more preferably 0.01 wt% or less, and most preferably 0.001 wt% or less.

[0158] Preferably, fraction A contains EDA at 0.01 wt% or less, more preferably 0.001 wt% or less, and most preferably 0.0001 wt% or less.

[0159] Preferably, fraction A contains components having a boiling point higher than that of EDA at 0.01% or less, more preferably 0.001% or less, and most preferably 0.0001% or less. Fraction A may contain some components having a boiling point lower than that of EDA other than water, such as methane or ammonia, in amounts of 0.1 wt% or less, more preferably 0.08 wt% or less, and most preferably 0.05 wt% or less, respectively.

[0160] Removal of fraction A with a low content of organic compounds enables efficient disposal of fraction A in a conventional water purification plant or direct recycling to this process or other processes where water is required.

[0161] Fraction B containing water, NMEDA, and EDA (where the weight ratio of water to NMEDA is in the range of 1:100 to 100:1, preferably 1:50 to 50:1, more preferably 1:10 to 10:1, and most preferably 1:3 to 3:1) is preferably withdrawn as a side stream from the NMEDA removal column. The amount of fraction B withdrawn as a side draw is relatively small to avoid EDA loss, but is large enough to substantially remove all of the NMEDA present in the feed to the NMEDA removal column. Preferably, the weight ratio of the feed stream to the NMEDA removal column to the weight of the side draw removed from the NMEDA removal column is in the range of 300:1 to 1500:1, more preferably 400:1 to 1200:1, and more preferably 600:1 to 1000:1.

[0162] Fraction B is preferably taken out in the area between the middle and the top of the column, preferably in the area between 50 percent and 90 percent of the theoretical stages, more preferably in the area between 55 percent and 80 percent of the theoretical stages, and most preferably in the area between 60 percent and 70 percent of the theoretical stages. Preferably, fraction B is taken out above the supply to the NMEDA removal column.

[0163] Fraction B typically also contains some EDA, whereby the weight ratio of NMEDA to EDA is preferably from 0.1:1 to 5:1, more preferably from 1:1 to 4:1, and most preferably from 1.5:1 to 3:1.

[0164] Preferably, fraction B contains 10 to 75 weight percent of NMEDA, more preferably 20 to 70, and even more preferably 30 to 60 weight percent of NMEDA.

[0165] The removal of fraction B as a sidestream has the advantage that most of the NMEDA formed in the EDA preparation process can be removed in a small but concentrated stream. Fraction B is preferably sent for incineration, which sacrifices only a negligible amount of the valuable product EDA while enabling the efficient disposal of the unwanted by-product NMEDA.

[0166] In a preferred embodiment, fraction C, preferably taken out from the bottom of the NMEDA removal column, has a low water content that usually meets the sales specifications. In this embodiment, the weight ratio of EDA to water is greater than 100:1, preferably greater than 200:1, and more preferably greater than 300:1.

[0167] Fraction C preferably contains 0.1 weight percent or less of NMEDA, preferably 0.05 weight percent or less, and more preferably 0.01 weight percent or less of NMEDA.

[0168] Fraction C preferably contains 1 to 30 wt%, preferably 5 to 25 wt%, more preferably 7.5 to 15 wt% of EDA.

[0169] In this embodiment, fraction C preferably has a boiling point higher than that of EDA, in particular: 1 to 50 wt%, preferably 5 to 30 wt%, more preferably 10 to 20 wt% of MEOA; 40 to 95 wt%, preferably 50 to 90 wt%, more preferably 60 to 80 wt% of MEG and contains.

[0170] In this preferred embodiment, fraction C preferably also contains one or more of ethylene amines or ethanol amines selected from the group consisting of PIP, DETA, AEEA, DEOA, HEPIP, HEDETA and TETA, in amounts of preferably 0.01 to 2 wt%, more preferably 0.02 to 1 wt%, most preferably 0.03 to 0.7 wt% respectively.

[0171] In a preferred embodiment, when MEG is used as the only additional auxiliary agent, the preferred composition of fraction C taken out at the bottom of the NMEDA removal column is MEG: 60 to 80 wt%, MEOA: 10 to 20 wt%, EDA: 5 to 15 wt%, PIP: 0.5 to 2 wt%, DETA: 0.1 to 2 wt%, AEEA: 0.01 to 1 wt%, DEOA: 0.01 to 0.5 wt%, TETA: 0.1 to 2 wt%, Water: 0.001 to 0.5 wt%, Others: 0.001 to 5 wt% is.

[0172] NMEDA Removal Tower - 2 Tower Setup Instead of using a single NMEDA removal tower, the separation step (ii) may be carried out in two NMEDA removal towers. In the first tower, fraction A is preferably separated at the top of the first NMEDA removal tower, and fractions B and C are removed together at the bottom of the first NMEDA removal tower. Thus, the combined fractions B and C are further separated, preferably in a second NMEDA removal tower where fraction B is removed at the top of the tower and fraction C is withdrawn at the bottom of the tower.

[0173] Additional dehydration tower In a particularly preferred embodiment, fraction C, preferably withdrawn from the bottom of the first or second NMEDA removal tower, has a higher water content.

[0174] The higher water content is preferably reduced, most preferably in another distillation tower (residual water removal tower), in a subsequent separation step.

[0175] In this embodiment, the subsequent separation step not only allows for a further reduction in water content, but it also allows for a further reduction in NMEDA content, which enables the obtaining of EDA with an even lower NMEDA content. This ultra - low NMDEA content allows for the subsequent purification in the further work - up of the ethylene amine mixture by being able to separate EDA, PIP from the high - boiling components, especially MEOA and MEG, in a single dividing wall column as further shown below.

[0176] In this particularly preferred embodiment, the water content in fraction C is in the range of 0.1 - 10 wt%, preferably 0.5 - 5 wt%.

[0177] In this particularly preferred embodiment, fraction C preferably has a higher boiling point than EDA, especially: 10 - 70 wt%, preferably 20 - 60 wt%, more preferably 35 - 55 wt% of EDA; 1 to 50 weight percent, preferably 5 to 30 weight percent, more preferably 10 to 20 weight percent of MEOA; 5 to 60 weight percent, preferably 10 to 50 weight percent, more preferably 20 to 40 weight percent of MEG is included.

[0178] In this particularly preferred embodiment, fraction C preferably further comprises one or more of ethyleneamines or ethanolamines selected from the group consisting of PIP, DETA, AEEA, HEDETA, HEPIP, DEOA and TETA, each in an amount of 0.01 to 2 weight percent, more preferably 0.02 to 1.5 weight percent, most preferably 0.05 to 1 weight percent.

[0179] In a preferred embodiment of this particularly preferred embodiment, MEG is used as the only additional auxiliary agent.

[0180] In this case, the preferred composition of fraction C withdrawn at the bottom of the NMEDA removal column is MEG: 20 to 40 weight percent, MEOA: 10 to 25 weight percent, EDA: 30 to 60 weight percent, PIP: 0.5 to 5 weight percent, DETA: 0.1 to 3 weight percent, AEEA: 0.01 to 0.5 weight percent, DEOA: 0.01 to 0.5 weight percent, TETA: 0.1 to 2 weight percent, Water: 0.5 to 5 weight percent, Others: 0.001 to 5 weight percent is.

[0181] If the water content of fraction C is in the range shown in the particularly preferred embodiment having a higher water content as specified above, fraction C further - Fraction C-1 containing EDA, NMEDA and water (where the weight ratio of EDA to water is in the range of 1:5 to 5:1, preferably 1:3 to 3:1, more preferably 1:2 to 2:1, and the weight ratio of NMEDA to EDA is preferably in the range of 100:1 to 1:1, more preferably 50:1 to 5:1, most preferably 30:1 to 10:14), and - Fraction C-2 containing EDA and a component having a boiling point higher than that of EDA preferably (wherein the NMEDA content is preferably 0.01 wt% or less, more preferably 0.001 wt% or less, most preferably 0.0001 wt% or less). It is separated into.

[0182] As described above, when fraction C is further separated into fractions C-1 and C-2, EDA with an ultra-low NMEDA content can be obtained.

[0183] In a preferred embodiment, fraction C-1 is preferably recycled directly as a gas phase to the bottom of the NMEDA removal column without condensation. This has the advantage that the energy required for separation in the second column is used in the first column, reducing the energy requirement for the reboiler of the first column.

[0184] The separation of fraction C into fractions C-1 and C-2 is preferably carried out in a conventional distillation column (residual water removal column).

[0185] The residual water removal tower is usually a tray tower, a bubble cap tray tower, a perforated plate tower, a dual flow tray tower, a valve tray tower, a baffle tray tower, or a tower with random packing or structured packing. It is preferable to use internal structures with low pressure drop, such as structured packing in the form of, for example, sheet metal packing like Mellapak 250Y or Montz Pak (type B1-250). It is also possible for there to be packing with a lower or increased specific surface area, or it is possible to use other shaped packings such as cloth packing or Mellapak 252.Y. The advantages of using such internal structures are, for example, lower pressure drop and lower specific liquid hold-up compared to valve trays.

[0186] The internal structure can be arranged in one or more beds.

[0187] Preferably, the residual water removal tower includes structured packing, particularly Mellapak 250.

[0188] The number of theoretical plates of the residual water removal tower is generally in the range of 15 to 70, preferably 20 to 50, more preferably 30 to 40.

[0189] The energy required for the separation of the feed provided in step (i) in the residual water removal tower is typically introduced by a reboiler at the bottom of the tower. This reboiler is typically a natural circulation reboiler or a forced circulation reboiler. Alternatively, it is also possible to use reboilers with short residence times, such as falling film reboilers, spiral tube reboilers, wiped film reboilers, or short path reboilers.

[0190] Fraction C from the NMEDA removal tower is preferably introduced at the top of the residual water removal tower, and as a result, preferably the residual water removal tower is designed to have only a stripping section.

[0191] In a preferred embodiment, the residual water removal column does not have a condenser, and the uncondensed vapor taken out at the top of the column is preferably recycled, preferably through a valve, to the water sump of the NMEDA removal column.

[0192] The top pressure of the residual water removal column is preferably 4 bar or less, more preferably 3 bar or less, even more preferably 2 bar or less, and most preferably 1.5 bar or less. The preferred range of the top pressure in the residual water removal column is in the range of 100 mbar to 3 bar, more preferably 500 mbar to 2 bar, and most preferably 800 mbar to 1.5 bar.

[0193] The residual water removal column is preferably operated at a bottom temperature of 140 to 230 °C, more preferably 150 to 210 °C, and even more preferably 170 to 190 °C.

[0194] The residual water removal column is preferably connected to an evaporator (reboiler) at the bottom of the column. This evaporator is typically a natural circulation evaporator or a forced circulation evaporator. Alternatively, it is also possible to use an evaporator with a short residence time, such as a falling film evaporator, a spiral tube evaporator, a wiped film evaporator, or a short path evaporator.

[0195] In a preferred embodiment where MEG is used as the only auxiliary agent, the composition of fraction C-2 taken out at the bottom of the residual water removal column is MEG: 20 to 60, preferably 30 to 50 wt%, MEOA: 10 to 40, preferably 15 to 25 wt%, EDA: 10 to 50, preferably 20 to 40 wt%, PIP: 0.1 to 10, preferably 0.5 to 5 wt%, DETA: 0.1 to 10, preferably 0.5 to 5 wt%, AEEA: 0.1 to 10, preferably 0.5 to 5 wt%, DEOA: 0.05 to 2, preferably 0.1 to 1 wt%, TETA: 0.01 to 2, preferably 0.05 to 0.5 weight percent, Water: 0.001 to 0.5, preferably 0.01 to 0.1 weight percent, NMEDA: 0.005, preferably 0.0005 weight percent or less contain.

[0196] Downstream separation and recycling Fraction C or C-2 can be further separated in a sequence of downstream separation steps. The downstream separation step is preferably carried out in a conventional column or a dividing wall column.

[0197] In a particularly preferred separation sequence, fraction C-2 from the bottom of the residual water removal column - Fraction D-1 containing EDA and - Fraction D-2 containing PIP and - Components having a boiling point higher than PIP, particularly fraction D-3 containing MEOA, MEG, DETA, AEE, DEOA and TETA is separated into.

[0198] Preferably, the separation into fractions D-1, D-2 and D-3 is preferably carried out in a single dividing wall column. The dividing wall column can be designed according to the teachings of WO 2005 / 037769 pamphlet, which discloses a dividing wall column capable of separating EDA and PIP from other higher boiling ethanolamines and ethyleneamines.

[0199] Fraction D-1 preferably contains a water content of 0.1 weight percent or less, preferably 0.08 weight percent or less, more preferably 0.05 weight percent or less.

[0200] Fraction D-1 preferably contains a PIP content of 0.05 weight percent or less, preferably 0.01 weight percent or less, more preferably 0.005 weight percent or less.

[0201] Fraction D-1 preferably contains an NMEDA content of 0.05 wt% or less, preferably 0.001 wt% or less, more preferably 0.0005 wt% or less.

[0202] Fraction D-2 preferably contains an EDA content of 0.3 wt% or less, preferably 0.2 wt% or less, more preferably 0.1 wt% or less.

[0203] Fraction D-2 preferably contains a water content of 0.05 wt% or less, preferably 0.01 wt% or less, more preferably 0.005 wt% or less.

[0204] Fraction D-2 preferably contains an NMEDA content of 0.01 wt% or less, preferably 0.001 wt% or less, more preferably 0.0001 wt% or less.

[0205] Fraction D-2 preferably contains an EDA content of 0.1 wt% or less, more preferably 0.05 wt% or less, most preferably 0.01 wt% or less.

[0206] This particularly preferred separation sequence, in which fraction C-2 is separated in a single dividing wall column, enables the preparation of EDA and PIP that meet the ultra-low NMEDA content sales specifications, reducing the investment and operating costs compared to the conventional setup of the EDA / PIP separation column and subsequent separation of EDA and PIP in further columns.

[0207] Fraction D-3 is preferably separated in one or more further separation steps into a value fraction or a fraction that can be easily recycled to the EDA preparation process. More preferably, fraction D-3 is separated into a value fraction or a fraction that can be provided to an additional MEOA process or MEOA reactor as described above.

[0208] Fraction D-3 is preferably further - Fraction E-1 containing MEOA with a MEG content of preferably 2000 ppm or less, preferably 1500 ppm or less, more preferably 1000 ppm or less; and - Fraction E-2 containing components having a boiling point higher than that of MEOA, particularly MEG, DETA, AEE, DEOA and TETA is separated into.

[0209] This separation step is preferably carried out in a conventional column.

[0210] Fraction E-1 is preferably fed to a MEOA reactor, in which MEOA is converted to ethyleneamine and ethanolamine with ammonia in the presence of an amination catalyst and hydrogen as disclosed in the preceding section. The effluent from the MEOA-conversion reactor can be combined with the effluent from the MEG-conversion reactor and separated using the same separation sequence and equipment as also disclosed above.

[0211] Fraction E-2 is preferably - Fraction F-1 containing MEG and preferably MEOA of 1000 ppm or less, more preferably 800 ppm or less, most preferably 600 ppm or less, and - Fraction F-2 containing components having a boiling point higher than that of MEG, particularly DETA, AEE, DEOA and TETA is separated into.

[0212] This separation step is preferably carried out in a conventional column.

[0213] Fraction F-1 is preferably recycled to a MEG reactor in which MEG is converted to MEOA, ethyleneamine and ethanolamine with ammonia in the presence of hydrogen and an amination catalyst.

[0214] Fraction F-2 is preferably - Fraction G-1 containing DETA, MEG and AEPIP, and - Fraction G-2 containing AEEA and HEPIP are separated into.

[0215] Fraction G-1 can be further separated into - Fraction H-1 containing MEG, - Fraction H-2 containing DETA and AEPIP .

[0216] This separation step is preferably carried out in a conventional column.

[0217] Fraction H-2 is preferably further separated into - Fraction I-1 containing DETA, and - Fraction I-2 containing DETA and AEPIP are separated into.

[0218] Fraction I-1 can be used as the value fraction of DETA that meets the sales standard.

[0219] Fraction I-2 is preferably recycled to the column where the separation of fraction G-1 is carried out.

[0220] Fraction G-2 can be further separated into - Fraction J-1 containing AEEA and HEPIP, - Fraction J-2 containing AEEA, DEOA, TETA and HEDETA .

[0221] This separation step is preferably carried out in a conventional column.

[0222] Fraction J-1 is preferably recycled to the MEOA reactor.

[0223] Fraction J-2 can be further separated into - Fraction K-1 containing AEEA, and - Fraction K-2 containing DEOA, TETA and HEDETA can be separated into.

[0224] Fraction K-1 can be used as a value fraction for AEEA that meets the normal sales specifications of AEEA.

[0225] Fraction K-2 can be used as a mixed fraction for specific applications, or it can be further separated into a fraction consisting essentially of DEOA, TETA and HEDETA.

[0226] When using one or more of the above separation steps, the ethanolamine and ethyleneamine obtained in the EDA preparation process are separated into a fraction containing a single value product such as AEEA, DETA, EDA and PIP or a fraction containing a mixture of ethanolamines, which can be easily recycled to an additional MEOA process, especially to a reactor (MEOA reactor) where MEOA and other ethanolamines are converted to ethyleneamine. The above process sequence focuses on obtaining a limited number of value products such as AEEA, DETA, EDA and PIP, and fractions that can be recycled to the EDA preparation process. In this way, a limited number of separation steps are required to prevent losses due to unwanted by-products or components.

[0227] In another preferred embodiment, fraction C, without further separating fraction C into additional fractions C-1 and C-2, - Fraction D-1 containing EDA, - Fraction D-2 containing EDA, PIP and MEOA, and - Fraction D-3 containing MEG and components having a boiling point higher than MEG, especially DETA, AEE, DEOA and TETA is separated into.

[0228] This separation step is preferably carried out in a conventional column in which fraction D-1 is taken as the top product, fraction D-2 is taken as the side draw, and fraction D-3 is taken as the bottom product.

[0229] Fraction D-1 essentially contains EDA and preferably has a water content of 0.2 wt% or less, more preferably 0.15 wt% or less, and most preferably 0.1 wt% or less.

[0230] The NMEDA content is preferably 0.1 wt% or less, more preferably 0.08 wt% or less, and most preferably 0.05 wt% or less.

[0231] Fraction D-2 preferably contains 80 wt% or more of MEOA, more preferably 85 wt% or more, and most preferably 90 wt% or more of MEOA, as well as about 1-5 wt% of each of EDA and PIP.

[0232] Fraction D-2 preferably further - fraction E-1 containing EDA and PIP, and - fraction E-2 containing MEOA is separated into.

[0233] This separation step is preferably carried out in a conventional column.

[0234] Fraction E-1 is preferably further separated into fraction F-1 containing EDA and fraction F-2 containing PIP.

[0235] Fraction E-2 is preferably recycled to the MEOA process step integrated into this process.

[0236] Fraction D-3 is preferably - Fraction G-1 containing MEG, and - Fraction G-2 containing DETA and components having a boiling point higher than DETA are separated into.

[0237] Fraction G-1 is preferably recycled to the MEG process step or used as a scrubbing liquid to wash out MEG in the ammonia / hydrogen removal step (i-b) as described above before being recycled to the MEG process step.

[0238] Fraction G-2 is preferably - Fraction H-1 containing MEG and DETA, and - Fraction H-2 containing AEEA, DEOA and TETA are separated into.

[0239] This separation step is preferably carried out in a conventional column.

[0240] Fraction H-1 is preferably recycled to the MEG process.

[0241] Fraction H-2, which contains the highest boiling point components, is preferably either removed from the process, sent to the flare, or separated into its individual components in a further separation step.

[0242] The separation sequence according to the invention enables the production of EDA having an NMEDA content within specifications.

[0243] The separation step of the present invention enables the efficient removal of NMEDA and water, which requires low operating and investment costs.

[0244] In a preferred embodiment, the removal of NMEDA and water can be carried out at ambient conditions or conditions slightly below atmospheric values, which is easier to implement than the high-pressure separation processes known in the prior art.

[0245] The separation of the present invention enables subsequent downstream separation sequences, thereby obtaining an in-specification fraction.

[0246] The separation of the present invention also enables the separation of MEOA and MEG, which can be recycled to either the EDA preparation process or the reactor, either in the MEG process or in the MEOA process step.

[0247] The separation step of the present invention further enables the design of the overall MEG process around it, which enables a high selectivity and yield of desired value products such as EDA, DETA, AEEA, and PIP while minimizing losses due to undesirable by-products.

[0248] In a preferred embodiment, the separation of water and NMEDA to the in-specification level can be carried out in a single column, which is particularly economical with respect to reducing capital investment.

[0249] In an even more preferred embodiment, the water content in fraction C is adjusted to a higher level that enables the removal of residual water and NMEDA in a further separation step. When the NMEDA removal column is combined with the residual water removal column, an ultra-low water and / or NMEDA content in EDA can be obtained. The combination of the NMEDA removal column and the residual water removal column also enables the subsequent separation of the value products EDA and PIP in a single dividing wall column, as compared to a two-column setup where EDA and PIP are separated by conventional methods. The use of the dividing wall column has an additional positive effect on capital investment and operating costs.

[0250] The advantages of the present invention are demonstrated by the following examples.

Examples

[0251] This example is based on calculations performed using a process simulation model. The simulation was carried out using CHEMASIM (registered trademark). For the calculation of the thermodynamic properties of pure components, such as vapor pressure, the DIPPR correlation was used. Regarding the description of phase equilibrium, the ideal gas law was used to describe the gas phase, and the NRTL excess Gibbs energy model was used for the description of the liquid phase. The parameters of the DIPPR correlation and the parameters of the NRTL model were adjusted to fit the experimental data. For components for which experimental data were not available, the UNIFAC group contribution method was used for the description of the liquid phase in the phase equilibrium calculation. The distillation column was modeled and calculated using an equilibrium stage model. The simulation and thermodynamic property models used were adjusted to reproduce the experimental data and plant data with very good accuracy.

[0252] Example 1: The feed was prepared in a combined MEG / MEOA process. After the removal of hydrogen and ammonia, the feed was Water: 15.80 wt% NMEDA: 0.04 wt% EDA: 18.81 wt% PIP: 1.81 wt% MEOA: 16.67 wt% MEG: 42.07 wt% DETA: 1.96 wt% AEPIP: 0.21 wt% AEEA: 1.65 wt% and contained.

[0253] The molar ratio of MEG to EDA in the feed stream was 2.17 to 1. The molar ratio of hydroxyl groups to EDA was approximately 6:1. A feed stream of 1725.72 kg / h was fed to the NMEDA removal column, where it was separated into fraction A, fraction B, and fraction C. The NMEDA removal column was equipped with a reboiler and had 28 trays. The feed was introduced above stage 12 (counting from the bottom of the column). The bottom temperature of the column was 159 °C.

[0254] A fraction A of 644.26 kg / g containing water and 100 ppm by weight of NMEDA (weight ratio of water to NMEDA: approximately 10,000:1) was withdrawn from the top of the column and fed to a condenser operated at 100 °C. A condensate stream of 372.12 kg / h was countercurrent to the top of the NMEDA removal column, and a stream of 272.13 kg / h was removed.

[0255] 40.1 wt% water 41.8 wt% NMEDA 18.1 wt% EDA A fraction B of 1.58 kg / h containing the above was withdrawn as a side draw between stages 17 and 18. Thus, the weight ratio of water to NMEDA was approximately 0.96:1.

[0256] Water: 1.05 wt% NMEDA: 0.01 wt% EDA: 32.40 wt% PIP: 2.30 wt% MEOA: 18.55 wt% MEG: 41.11 wt% DETA: 1.88 wt% AEPIP: 0.20 wt% AEEA: 1.57 wt% A fraction C of 1847.93 kg / h containing the above was withdrawn from the bottom of the NMEDA removal column and fed to an additional residual water removal column. The weight ratio of EDA to water in fraction C was approximately 30.9:1.

[0257] Fraction C was further separated into fraction C-1 and fraction C-2 in a residual water removal column equipped with a reboiler and having 36 stages. Fraction C was introduced above stage 36. The residual water removal column was operated at a bottom temperature of 181 °C and a top pressure of 1.3 bar.

[0258] Water: 4.86 wt% NMEDA: 0.028 wt% EDA: 69.36 wt% PIP: 2.88 wt% MEOA: 13.91 wt% MEG: 8.55 wt% DETA: 0.24 wt% AEPIP: 0.03 wt% AEEA: 0.12 wt% 395.93 kg / h of fraction C-1 containing the above was taken out from the top of the residual water removal column. This stream was directly fed in the form of vapor without condensation to the bottom of the NMEDA removal column.

[0259] Water: 0.01 wt% NMEDA: 0.00009 wt% EDA: 22.32 wt% PIP: 2.15 wt% MEOA: 19.80 wt% MEG: 49.99 wt% DETA: 2.33 wt% AEPIP: 0.25 wt% AEEA: 1.97 wt% 1452.00 kg / h of fraction C-2 containing the above was taken out from the bottom of the residual water removal column and purified in a dividing wall column. A pure EDA fraction containing 500 weight ppm of water and 2 weight ppm of NMEDA was obtained.

[0260] Example 2: Provision of a feed containing EDA, NMEDA and water The feed was prepared by a combined MEG / MEOA process. After removal of hydrogen and ammonia, the feed was Water: 9.03 weight percent NMEDA: 0.07 weight percent EDA: 7.07 weight percent PIP: 0.72 weight percent MEOA: 12.96 weight percent MEG: 68.82 weight percent DETA: 0.72 weight percent AEEA: 0.07 weight percent TETA: 0.51 weight percent contained

[0261] The molar ratio of MEG to EDA in the feed stream was 9.43 to 1. The molar ratio of hydroxyl groups to EDA was approximately 18.9:1. A feed stream of 2459.7 kg / h was fed to the NMEDA removal column, and the feed was separated in this column into fraction A, fraction B, and fraction C. The NMEDA removal column was equipped with a reboiler and had 25 trays. The feed was introduced above tray 12 (counting from the bottom of the column). The bottom temperature of the column was 180 °C.

[0262] Fraction A, containing water and 100 weight ppm of NMEDA (weight ratio of water to NMEDA: approximately 10000:1), of 354.15 kg / g was withdrawn from the top of the column and fed to a condenser operated at 100 °C. A condensate stream of 134.79 kg / h was counter-currently fed to the top of the NMEDA removal column, and a stream of 219.36 kg / h was withdrawn. Fraction A, containing water and 100 weight ppm of NMEDA, was withdrawn from the top of the column. Thus, the weight ratio of water to NMEDA was approximately 10000:1.

[0263] 5.43 weight percent water 36.9 weight percent NMEDA 7.62 weight percent EDA A 4.35 kg / h fraction B containing [the relevant components] was withdrawn as a side draw between stages 16 and 17. Thus, the weight ratio of water to NMEDA was approximately 6.17:1.

[0264] Water: 1.05 weight percent NMEDA: 0.002 weight percent EDA: 7.76 weight percent PIP: 0.79 weight percent MEOA: 14.26 weight percent MEG: 75.71 weight percent DETA: 0.79 weight percent AEEA: 0.04 weight percent TETA: 0.56 weight percent A 2235.92 kg / h fraction C containing [the relevant components] was withdrawn from the bottom of the NMEDA removal column. The weight ratio of EDA to water in fraction C was approximately 236.5 to 1.

[0265] Fraction C was purified in a 60 - stage distillation column. Fraction C was fed to the column between stages 36 and 37 (counting from the bottom). An overhead fraction containing 99.80 weight percent EDA, 0.12 weight percent water, 0.03 weight percent NMEDA, and 0.05 weight percent PIP was obtained.

[0266] Example 1 shows that by separating the feed stream from the EDA preparation process into three fractions according to the present invention from the NMEDA removal column, commercial - grade EDA can be obtained in just one additional distillation step. The loss of EDA is relatively small and is of the same order of magnitude as the NMEDA present in the feed.

[0267] In Example 2, the water content at the bottom of the NMEDA removal column is relatively higher. This enables the obtaining of EDA with an ultra - low NMEDA content.

Claims

1. Water (H ２ O), a method for producing ethyleneamine from a mixture containing ethylenediamine (EDA) and N-methylethylenediamine (NMEDA): (i) the step of providing a supply stream containing EDA, NMEDA and water; (ii) The feed stream provided in step (i) in one or more distillation columns a. Fraction A containing water and NMEDA (where the weight ratio of water to NMEDA in Fraction A is greater than 100:1); b. Fraction B containing water, NMEDA, and EDA (where the weight ratio of water to NMEDA is in the range of 1:100 to 100:1); and c. Fraction C containing water and EDA (where the water content in Fraction C is in the range of 0.1 to 10 weight percent). The steps to separate into; (iii) Fraction C, - Fraction C-1 containing EDA, NMEDA, and water (where the weight ratio of EDA to water is in the range of 1:5 to 5:1, and the weight ratio of NMEDA to EDA is in the range of 100:1 to 1:1), and - Fraction C-2 containing EDA and preferably a component having a higher boiling point than EDA (the NMEDA content therein is 0.01 weight percent or less) The steps to separate into A method that includes this.

2. The method according to claim 1, wherein the feed comprising EDA, NMEDA, and water comprises 1 to 30 weight percent of EDA, 1 to 30 weight percent of water, and 0.001 to 1 weight percent of NMEDA.

3. The method according to claim 1, wherein the feed provided in step (i) further comprises a component having a higher boiling point than EDA.

4. The method according to claim 3, wherein one of the components having a higher boiling point than EDA is monoethanolamine (MEOA).

5. The provision of supplies in step (i) is (i-a) A step of carrying out an EDA preparation process to obtain an output containing EDA, NMEDA and water, (i-b) a step of removing ammonia and / or hydrogen from the output generated in step (i-a); (i-c) The step of optionally adding an additional auxiliary agent The method according to claim 1, including the method described in claim 1.

6. The method according to claim 5, wherein the EDA preparation process in step (i-a) is a process in which monoethylene glycol (MEG) is converted with ammonia in the presence of an amination catalyst and hydrogen.

7. The method according to claim 1, wherein the separation step (ii) is carried out under conditions in which the azeotrope between EDA and water is broken, impaired or otherwise modified so that fraction A can be separated from NMEDA as a low boiling fraction.

8. The method according to claim 7, wherein the separation (ii) is carried out at a pressure lower than the pressure required to break down the EDA-water azeotrope.

9. The method of claim 8, wherein the supply provided in step (i) comprises an additional auxiliary agent.

10. The method according to claim 9, wherein the additional auxiliary agent is a compound other than ethanolamine or ethyleneamine.

11. The method according to claim 10, wherein the additional auxiliary agent is a hydroxyl group-containing compound.

12. The aforementioned additional auxiliary agent is (i) Aliphatic monools, (ii) Aliphatic diols; (iii) aliphatic triols; and (iv) aliphatic tetraol The method according to claim 11, selected from the group consisting of the following.

13. The method according to claim 12, wherein the additional auxiliary agent provided in step (i) is an aliphatic diol selected from the group consisting of ethylene glycol, 1,2-propylene glycol, and 1,2-butanediol.

14. The method according to claim 11, wherein the amount of additional auxiliaries provided in step (i) is adjusted such that the molar ratio of hydroxyl groups present in the feed to EDA molecules present in the feed is 1:1 or greater.

15. The method according to claim 13, wherein the additional auxiliary agent is MEG.

16. The method according to claim 15, wherein the molar ratio of MEG to EDA is 1:1 or greater.

17. The method according to claim 1, wherein the separation in step (ii) is carried out in a single distillation column in which fraction A is withdrawn at the top of the column, fraction B is withdrawn as a side fraction, and fraction C is withdrawn at the bottom of the column.

18. The method according to claim 17, wherein the temperature at the bottom of the tower is 160°C or less.

19. The aforementioned fraction C-2 is further, - Fraction D-1 containing EDA, - Fraction D-2 including PIP, and - Fraction D-3 containing components with a higher boiling point than PIP, particularly MEOA, MEG, DETA, AEE, DEOA, and TETA. The method according to claim 1, wherein the separation is performed.

20. The method according to claim 19, wherein the separation of fraction C-2 is carried out in a single divided wall tower.