Process for producing ethyleneamine

Abstract

The present invention relates to a method for producing ethylenediamine from a mixture comprising water (H2O), ethylenediamine (EDA), and N-methylethylenediamine (NMEDA), the method comprising: (i) providing a feed stream comprising EDA, NMEDA, water, and an additional adjuvant; and (ii) separating water from NMEDA and EDA contained in the feed stream in one or more distillation columns, wherein the water is separated from EDA and NMEDA as a low-boiling fraction. The present invention further relates to the use of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, di-1,2-propylene glycol, tri-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propylene glycol, trimethylolpropane, glycerol, pentaerythritol, or mixtures thereof as a distillation adjuvant for the distillation of mixtures comprising water, ethylenediamine, and N-methylethylenediamine.

Description

Technical Field

[0001] The present invention relates to a process for the production of ethylenediamine (EDA) and the use of certain hydroxyl group-containing compounds as distillation adjuvants for the distillation of mixtures containing water, ethylenediamine and N-methylethylenediamine.

Background Art

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

[0003] Numerous processes for preparing EDA are known (see, for example, Ullmann’s Encyclopedia of Industrial Chemistry, “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) with ammonia to obtain EDA, carbon monoxide (CO) and methylamine can be directly produced by the decomposition reaction of monoethanolamine (decarbonylation). Methylamine can react directly with further monoethanolamine to obtain NMEDA.

[0005] NMEDA can also be formed when AEEA is directly decomposed by decarbonylation to NMEDA in the dimerization of monoethanolamine to aminoethylethanolamine (AEEA).

[0006] NMEDA can also be produced when preparing EDA from C1 units such as hydrogen cyanide and formaldehyde.

[0007] In addition to NMEDA, poly-N-methylated ethylenediamines such as bis(N-methyl-1,2-ethanediamine) can also be formed. However, in terms of quantity, the formation of NMEDA is typically dominant.

[0008] For most industrial applications, the market requires EDA to have a purity of at least 99.5% by weight. Organic by-components including NMEDA may be present in a proportion of 0.5% by weight or less. Furthermore, the water content can be at most 0.5% by weight. More specifically, in many industrial applications, the purity of EDA is defined when the proportion of NMEDA is less than 1000 ppm by weight.

[0009] EDA, depending on its preparation, has more water and / or a content of NMEDA and must be worked up accordingly to obtain EDA that meets the required specifications.

[0010] The problem in the separation of ethylenediamine mixtures is 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, when an azeotrope of EDA and NMEDA is formed, the boiling point difference between NMEDA and EDA may increase, and under the conditions where the corresponding azeotrope is formed, the separation of NMEDA and EDA becomes easier.

[0011] Depending on the amount of NMEDA in the ethylenediamine mixture, various distillation strategies can be adopted for the ethylenediamine mixture containing NMEDA, EDA, and water.

[0012] When the ethylenediamine mixture contains a large amount of NMEDA, NMEDA is usually separated before water is removed.

[0013] European Patent No. 2487151 (DOW) discloses a process for removing alkyl ethylenediamines from ethyleneamine mixtures. A mixture containing ethylenediamine, water and one or more alkyl ethylenediamines is subjected to conditions under which an azeotrope is formed between water and the alkyl ethylenediamine, and the azeotrope of water and NMEDA is separated from the remaining composition. The pressure in the rectification column where the azeotrope of water and the alkyl ethylenediamine is separated is disclosed to be in the range of 1.01 to 2.12 bar, preferably 1.5 to 1.98 bar. In Example 1, the distillation is carried out 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 distillation, the present disclosure does not seem to include further technical information on what means those skilled in the art must consider such that an azeotrope of alkyl ethylenediamine and water is formed.

[0014] A further process for separating NMEDA from EDA and water is disclosed in European Patent No. 2507202 (BASF). This disclosure states that the removal of NMEDA is carried out in a rectification column at a top pressure in the range of 0.01 bar to 4 bar, and the mixture to be distilled contains at least a sufficient amount of water under the condition that H = a*X / Y (where H is the weight fraction of water in the mixture to be distilled, X is the weight fraction of water, Y is the weight fraction of EDA at the azeotropic point of the binary mixture of water and EDA at the column pressure, and a is a real number having a value of 0.9 or more) is satisfied.

[0015] 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 has 50 to 140 theoretical plates. NMEDA is withdrawn at the top of the column, and the azeotrope of EDA / water is withdrawn at the bottom of the column.

[0016] After the removal of NMEDA, or if the NMEDA concentration is low from the beginning, the EDA / water mixture can be separated in various ways.

[0017] German Patent No. 1258413 (DOW) discloses the separation of EDA and water in a single dehydration column operated at a pressure at which the azeotrope of water and EDA is broken, whereby water can be withdrawn at the top of the distillation column and EDA and other amines can be withdrawn from the drain sump.

[0018] Alternatively, EDA and water may be separated in two columns operated at different pressures (two-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).

[0019] U.S. Patent Application Publication No. 2017217874 discloses a separation in which a feed containing NMEDA, EDA and water is first separated for water under high-pressure azeotropic conditions and the NMEDA / EDA mixture obtained at the bottom of the first column is separated in a second column.

[0020] Some patent applications (Chinese Patent No. 105585508 (Sinopec), Chinese Patent No. 105585508 (Sinopec), Chinese Patent No. 105585501 (Sinopec), Chinese Patent No. 104119297 (Xi’an Modern Chemistry Research Institute), Chinese Patent No. 104230850 (Sinopec), Chinese Patent No. 105523943 (Sinopec)) teach the separation of water and ethylenediamine using an entrainer that forms a low-boiling azeotrope with water, such as toluene or xylene.

[0021] 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, which flows countercurrently to the rising azeotropic EDA / water vapor. Due to the contact between the EDA / water and the high-boiling extractant, the EDA is essentially concentrated in the extraction solvent, so essentially pure water is obtained at the top of the column, and a water-depleted mixture of EDA, extraction solvent, and water is obtained at the bottom of the column. According to the present invention, suitable extraction solvents are solvents with a boiling point exceeding 120°C, such as glycols like ethylene glycol (MEG), propylene glycol, and butylene glycol, and polyhydric alcohols like glycerol including glycerin. Other effective solvents are hydroxyamines or alkanolamines such as monoethanolamine (MEOA), diethanolamine (DEOA), triethanolamine (TEOA), and propanolamine.

[0022] 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 of EDA and water is disrupted. In a narrow pressure range, the separation of NMEDA, EDA, and water can be carried out in a single column.

[0023] In U.S. Patent No. 4,032,411 (Berol Kemi AG), the water / EDA mixture is distilled in the presence of a distillation adjuvant. The distillation adjuvant is described as acting as an azeotrope breaker. Thus, in a mixture of water, EDA, and the distillation adjuvant, the azeotrope between water and EDA is broken, so that water can be removed at the top of the column and the mixture of EDA and the distillation adjuvant can be removed at the bottom of the distillation column. The following compounds, namely PIP, DETA, AEEA, AEP, and mixtures thereof, are disclosed as suitable distillation adjuvants. The distillation is carried out at about 1 - 3 bar, and the temperature at the bottom of the distillation column varies between 140 - 210°C. According to the present invention, in order to carry out the distillation under technically appropriate conditions that enable the removal of water from EDA without forming an azeotrope, the weight ratio of the distillation adjuvant to EDA should be in the range of about 2:8 - 9:1, preferably about 4:6 - 8:2. According to the present invention, when preparing EDA with a very low water content of less than 2% by weight, otherwise a very high distillation temperature is required, which may cause decomposition of the amino compound, and since the column requires a large number of theoretical plates, it is preferable to carry out the distillation in multiple distillation columns. Thus, a preferred embodiment of the invention of U.S. Patent No. 4,032,411 includes first removing most of the water present in the aqueous EDA solution by carrying out distillation in the presence of one or more adjuvants, then removing the adjuvant, and finally carrying out vacuum distillation to remove further water.

[0024] Depending on the composition of the ethyleneamine mixture, the separation of components to obtain EDA within specifications can be difficult. When distilling under azeotropic conditions to remove NMEDA, it is necessary to control the ratio of water to NMEDA and EDA to achieve azeotropic conditions. Since the difference in boiling points between NMEDA and EDA, and their corresponding azeotropes, is small, a distillation column with many trays may be required. The use of a coentrainer, distillation adjuvant, or extraction solvent may require the addition of additional components, which may need to be removed from the final product. Distillation under non-azeotropic conditions without adding a coentrainer, adjuvant, or extraction solvent usually requires a high operating pressure in the distillation column.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0025] Accordingly, there is a continuing need for a process that enables the production of EDA within specifications using an economical distillation process having a reasonable number of towers that can be operated at reasonable temperatures and pressures using a reasonable number of trays. 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 an increase in the size of the equipment dimensions for handling the additional components, and the additional components typically need to be separated in additional steps to enable such adjuvants to be reused in the process. Accordingly, it is an object of the present invention to provide a manufacturing process for EDA that uses a reasonable number of distillation towers, towers of reasonable dimensions, and operates such towers under reasonable conditions such as temperature and pressure, where reasonable in the foregoing means finding an appropriate balance among operating expenses, capital expenses, and product quality.

MEANS FOR SOLVING THE PROBLEMS

[0026] 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 comprising EDA, NMEDA, water, and an additional adjuvant; (ii) separating water from NMEDA and EDA contained in the feed stream in one or more distillation towers, wherein the water is separated from EDA and NMEDA as a low-boiling fraction; and achieved by a method comprising.

[0027] The object of the present invention has also been achieved by the use of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, di-1,2-propylene glycol, tri-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propylene glycol, trimethylolpropane, glycerol, pentaerythritol, or mixtures thereof as a distillation adjuvant for the distillation of mixtures containing water, ethylenediamine and N-methylethylenediamine.

[0028] Surprisingly, when separating the feed into fractions according to the invention, it has been found that the downstream separation steps can be adjusted so that the feed can be economically separated into the desired valuable components and the desired valuable components can be obtained in high quality. Furthermore, by separating the feed according to the invention, NMEDA can be efficiently separated from EDA using a reasonable number of columns under reasonable distillation conditions, so that a separation process with balanced and advantageous operating and capital expenditures is obtained.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The following abbreviations are used herein: 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

[0030] Unless otherwise specified, the pressure values are in relation to absolute pressure values.

[0031] As used herein, the term ethyleneamine refers to ethylenediamine (EDA) of the general formula (I): R-CH2-CH2-NH2(i) and its linear homologs, wherein R is a group of the formula -(NH-CH2-CH2) X -NH2, and x is an integer in the range of 1 to 4, preferably 1 to 3, most preferably 1 to 2. Preferably, the reaction product is DETA, TETA, and TEPA, more preferably DETA and TETA, and particularly preferably DETA; General formula (II)

Chemical formula

[0032] Examples of linear ethyleneamines are DETA, TETA, TEPA, and HEPA. Examples of cyclic ethyleneamines are PIP and AEPIP.

[0033] As used herein, the term ethanolamine refers to monoethanolamine (MEOA) of the general formula (III): R-CH2-CH2-OH (III) and its linear homologs, wherein R is a group of the formula -(NH-CH2-CH2) XIt is a -NH2 group, and x is an integer in the range of 1 to 4, preferably 1 to 3, and most preferably 1 to 2.

[0034] Examples of higher linear ethanolamines are AEEA and HEDETA.

[0035] As used herein, the term ethanolamine refers to formula (IV)

Chemical formula

[0036] An example of a cyclic ethanolamine is hydroxyethylpiperazine (HEPIP).

[0037] Step (i): providing a feed stream comprising EDA, NMEDA and water The method according to the present invention includes step (i) of providing a feed stream comprising (i) EDA, NMEDA, water, and an additional adjuvant.

[0038] In a preferred embodiment, in step (i), providing a feed comprising EDA, NMEDA, water and an additional adjuvant comprises: (i-a) performing an EDA preparation process to obtain a product comprising EDA, NMEDA and water; (i-b) A step of removing ammonia and / or hydrogen from the product generated in step (i-a); (i-c) A step of adding an additional adjuvant to the EDA preparation process before, during, or after step (i-a), or after the removal of ammonia and / or hydrogen in step (i-b); It includes.

[0039] Step (i-a): EDA preparation process: The feed provided in step (i) is preferably provided by carrying out an EDA preparation process.

[0040] The EDA preparation process of step (i-a) can be any known process for EDA production, such as the MEOA process, C1-process, EDC process, or MEG process, as described later.

[0041] MEOA process: The reaction between MEOA and ammonia is described, for example, in U.S. Patent No. 2,861,995, German Patent Application Publication No. 1 172 268A, and U.S. Patent No. 3,112,318. An overview of various process variations of the reaction between MEA and ammonia can be found, for example, in PERP Report No. 138, "Alkyl Amines," SRI International, 03 / 1981 (especially pages 81 - 99, 117).

[0042] The reaction between MEOA and ammonia is preferably carried out at 150 - 250 bar and 160 - 210 °C over a transition metal catalyst, or at 1 - 20 bar and 280 - 380 °C over a zeolite catalyst.

[0043] 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.

[0044] Preferred zeolite catalysts are mordenite, faujasite, and chabazite.

[0045] To achieve maximum EDA selectivity, for transition metal catalysts, the molar ratio of ammonia to MEOA is generally 6 - 20, preferably 8 - 15, and for zeolite catalysts, generally 20 - 80, preferably 30 - 50 is used.

[0046] The conversion rate of MEOA is generally maintained at 10% - 80%, preferably 40 - 60%.

[0047] In continuous operation, preferably, a catalyst space velocity in the range of 0.3 - 0.6 kg / (kg·h) (kg MEOA per kg of catalyst per hour) is established.

[0048] To maintain catalyst activity, when using a metal catalyst, it is preferable to additionally supply 0.05 - 0.5 wt% hydrogen (based on the MEOA + NH3 + H2 reaction feed) to the reactor.

[0049] C1 process: The EDA preparation process of step (i - a) can also be a C1 process in which formaldehyde, hydrogen cyanide, ammonia, and hydrogen are converted to EDA.

[0050] For example, U.S. Patent No. 2,519,803A describes a process for preparing EDA by hydrogenation of a partially purified aqueous reaction mixture that results from the amination of formaldehyde cyanohydrin (FACH) and contains aminoacetonitrile as an intermediate. Formaldehyde cyanohydrin can be obtained by the reaction of formaldehyde and hydrogen cyanide. Descriptions of processes for FACH preparation can be found, for example, in Application PCT / EP2008 / 052337, page 26, and International Publication No. 2008 / 104582A1 pamphlet, pages 30 (Variant A) and B)), which are expressly incorporated herein by reference.

[0051] German Patent No. 1 154 121 A relates to a further process for preparing EDA in which hydrogen cyanide, formaldehyde, ammonia and hydrogen reactants are reacted in a "one-pot" process in the presence of a catalyst.

[0052] International Publication No. WO 2008 / 104592 A1 relates to a process for preparing EDA by hydrogenation of aminoacetonitrile. Aminoacetonitrile is typically obtained by the reaction of formaldehyde cyanohydrin and ammonia, and formaldehyde cyanohydrin is generally prepared from hydrogen cyanide and ammonia.

[0053] Preferably, the reaction product containing EDA and NMEDA is prepared by the process described in International Publication No. WO 2008 / 104592 A, which is explicitly incorporated herein by reference.

[0054] 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, the aforementioned PERP report and the documents cited therein.

[0055] MEG process In a particularly preferred embodiment, the feed provided in step (i) is obtained by the conversion of MEG using 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 No. 102190588 and Chinese Patent No. 102233272.

[0056] Preferably, the conversion of MEG using 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. 2007 / 093514 Pamphlet, International Publication No. 2007 / 093552 Pamphlet, International Publication No. 2018 / 224316 Pamphlet, International Publication No. 2018 / 224315 Pamphlet, International Publication No. 2018 / 224321 Pamphlet, International Publication No. 2019 / 081283 Pamphlet, International Publication No. 2019 / 081285 Pamphlet and International Publication No. 2020 / 17085 Pamphlet.

[0057] In a particularly preferred embodiment (MEG process), the feed provided in step (i) is obtained by the conversion of MEG using ammonia in the presence of an amination catalyst and hydrogen.

[0058] The MEG used in this process can be prepared from ethylene obtained from petrochemical processes. For example, generally, ethylene is first oxidized to ethylene oxide and then reacted with water to obtain MEG.

[0059] Alternatively, ethylene oxide can be reacted with carbon dioxide in a process called the omega process to obtain ethylene carbonate, which can then be hydrolyzed with water to obtain MEG. The omega process is characterized by high selectivity for MEG because it forms few by-products such as diethylene glycol and triethylene glycol.

[0060] Alternatively, the ethylene used in the preparation of MEG can also be prepared from renewable raw materials. For example, ethylene can be formed by the dehydration of bioethanol.

[0061] MEG can also be prepared via the syngas route, for example, by oxidatively carbonylating methanol to obtain dimethyl oxalate and then hydrogenating it. Thus, additional possible petrochemical raw materials for MEG preparation are also natural gas or coal.

[0062] Alternatively, MEG obtained by recycling PET by various methods such as glycolysis, methanolysis, hydrolysis, saponification, and pyrolysis may also be used.

[0063] In the MEG process, MEG and optionally additional MEOA are reacted with ammonia. The additional MEOA may be added as an additional free body, but it is preferred to carry out the MEG process without further MEOA.

[0064] The ammonia used may be conventional commercially available ammonia, for example, ammonia having an ammonia content of more than 98% by weight, preferably more than 99% by weight, more preferably more than 99.5% by weight, particularly more than 99.8% by weight.

[0065] The MEG process is preferably carried out in the presence of hydrogen.

[0066] Hydrogen is generally used at technical grade purity. Hydrogen can also be used in the form of a hydrogen-containing gas, that is, by adding nitrogen, helium, neon, argon, or carbon dioxide. The hydrogen-containing gas used may be, for example, reformer off-gas, refinery gas, etc., as long as it does not contain sulfur components such as catalyst poisons of the catalyst used, such as H2S or CO. However, in the process, pure hydrogen or essentially pure hydrogen, 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, particularly more than 99.999% by weight is preferred.

[0067] In the MEG process, MEG is preferably reacted with ammonia and an amination catalyst in the liquid phase.

[0068] Preferred amination catalysts for the MEG process are as follows: - 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. WO 2007 / 093514, - The catalyst containing cobalt, ruthenium, and tin disclosed in International Publication No. WO 2018 / 224316, - The catalyst containing tin and a further active metal disclosed in International Publication No. WO 2018 / 224315, - The impregnated catalyst disclosed in International Publication No. WO 2018 / 224321, or - The rhenium-containing catalyst disclosed in International Publication No. WO 2020 / 017085.

[0069] The above-mentioned documents disclosing suitable catalysts are expressly incorporated by reference. The catalysts disclosed in the examples of the documents referred to above are particularly preferred.

[0070] In this context, "reaction in the liquid phase" means that ethylene glycol is present in the liquid phase and the reaction conditions such as pressure and temperature are adjusted so that it flows around the liquid-phase amination catalyst.

[0071] The reaction of MEG and / or MEOA with ammonia can be carried out continuously or batchwise. A continuous reaction is preferred.

[0072] A reactor suitable for the reaction in the liquid phase is generally a tubular reactor. The catalyst may be arranged as a moving bed or a fixed bed in the tubular reactor.

[0073] In a tubular reactor in which the amination catalyst is arranged in the form of a fixed bed, it is particularly preferred to react MEG and / or MEOA with NH3.

[0074] If the catalyst is arranged in the form of a fixed bed, it may be advantageous for the selectivity of the reaction to "dilute" the catalyst in the reactor by mixing it with an inert random packing. The proportion of the random packing in such a catalyst preparation is 20 to 80 parts by volume, preferably 30 to 60 parts by volume, more preferably 40 to 50 parts by volume. Preferably, the catalyst is not diluted.

[0075] Alternatively, the reaction is preferably carried out in a shell and tube reactor or a single stream plant. In a single stream plant, the tubular reactor in which the reaction is carried out may consist of a plurality of (for example, two or three) individual tubular reactors connected in series. Advantageous options considered here are the intermediate introduction of the feed (containing reactants and / or ammonia and / or H2) and / or the recycle gas and / or the reactor product from the downstream reactor.

[0076] When working in the liquid phase, MEG and / or MEOA + ammonia are preferably passed over the catalyst in an externally heated fixed bed reactor, generally at a pressure of 5 to 35 MPa (50 to 350 bar), 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, especially 160 to 230 °C, and are simultaneously guided in a liquid phase containing hydrogen.

[0077] 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), and particularly preferably 2 to 5 MPa (20 to 50 bar).

[0078] MEG and / or MEA and ammonia are preferably supplied to the reactor in liquid form and contacted with the amination catalyst in liquid form.

[0079] Either the trickle mode or the liquid phase mode is possible.

[0080] Even before the reactants are fed into the reaction vessel, it is advantageous to heat the reactants, preferably to the reaction temperature.

[0081] Ammonia is preferably used in an amount of preferably 0.9 to 100 molar amounts, particularly 1 to 20 molar amounts, based on the MEG or MEA used each time.

[0082] The space velocity per hour of the catalyst is generally in the range of 0.05 to 5.0, preferably 0.1 to 3, more preferably 0.2 to 1 kg (MEG + MEA) per kg of catalyst and per hour.

[0083] In a particularly preferred embodiment, since the conversion of MEG to ethylenediamine (especially EDA) and ethanolamine is incomplete, unreacted MEG remains in the reactor product. 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 acts as a distillation adjuvant, thereby facilitating the separation according to the invention of EDA, NMEDA and water, as described below.

[0084] The conversion of MEG is generally carried out such that the feed supplied to step (ii) contains MEG in the amounts specified below. The degree of conversion can be adjusted by variations in operating parameters such as the reaction temperature, the amount of ammonia added, and the space velocity per hour of the catalyst. Usually, when the space velocity per hour is decreased, the degree of conversion of MEG to MEOA and EDA increases.

[0085] MEG-MEOA combined process: In a preferred embodiment of the present invention, the feed provided in step (i) is: (i) In a first reactor (MEG reactor), ethylene glycol (MEG) is converted using ammonia in the presence of an amination catalyst and hydrogen to obtain a reaction product containing water, ethylenediamine (EDA), monoethanolamine (MEOA), unreacted MEG, and other components having a boiling point higher than that of EDA, and optionally NMEDA. (ii) Separating MEOA from the reaction product obtained in (i); (iii) In a second reactor (MEOA reactor), in the presence of an amination catalyst and hydrogen, converting the MEOA separated in step (ii) using ammonia to obtain a reaction product comprising water, ethylenediamine (EDA), unconverted monoethanolamine (MEOA), and other components having a boiling point higher than EDA, and optionally NMEDA; is obtained by.

[0086] When MEOA in the reactor product of MEG conversion is separated and converted in a separate reactor using an adjusted 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.

[0087] The separation of one or more MEOA fractions can be carried out according to the separation sequence described below.

[0088] In a more preferred embodiment, the MEG - MEOA process (iv) comprises separating MEG from the reaction product obtained in step (i); (v) recycling the MEG separated in step (iv) to step (i). The additional steps include.

[0089] The separation of one or more MEG fractions can be carried out according to the separation sequence described below.

[0090] The reaction products of the MEG reactor and the MEOA reactor are preferably combined in a common work - up section to separate their components. Using a common separation sequence has the advantage of reducing equipment costs and energy requirements.

[0091] Providing the feed in step (i) using the MEG process, separating the produced MEOA, and converting the separated MEOA in a subsequent MEOA process has the advantage that the overall selectivity and yield of EDA can be increased compared to producing the same amount of EDA either in a single MEOA or in a single MEG reactor.

[0092] By operating the MEG reactor and the subsequent MEOA reactor, unconverted MEOA can be efficiently reused.

[0093] Step (i-b): Removal of ammonia and / or hydrogen from the product obtained in step (i-a): The reaction products from the above preparation process generally contain ammonia and hydrogen.

[0094] Before feeding the products of these processes to the separation step (ii), ammonia and / or hydrogen are preferably removed.

[0095] The amount of ammonia in the reaction product 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%.

[0096] The amount of hydrogen in the reaction product is preferably in the range of 0.01 to 20 weight percent, more preferably in the range of 0.05 to 10 weight percent, and most preferably in the range of 0.1 to 5 weight percent.

[0097] Hydrogen and ammonia can be separated from the reaction mixture by methods known to those skilled in the art.

[0098] 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" (or in English "Ammonia Separation - Step 2") of WO 2019 / 081285, or in the section entitled "Ammoniakabtrennung - Stufe 2" (or in English "Ammonia Separation - Step 2") of WO 2019 / 081283. The content of these teachings is incorporated herein by reference.

[0099] Composition of the feed provided in step (i) The feed provided from step (i) contains NMEDA, water and EDA.

[0100] 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.

[0101] 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%.

[0102] Preferably, the feed contains 1 to 30 wt%, more preferably 2.5 to 25 wt%, and most preferably 5 to 20 wt% of water.

[0103] 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.

[0104] 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.

[0105] The feed provided from step (i) preferably contains other ethyleneamines and ethanolamines, particularly ethyleneamines and ethanolamines having a boiling point higher than that of EDA, especially PIP, MEOA, DETA, TETA, AEP, HEPIP, AEEA, and HEDETA. More preferably, the feed provided in step (i) preferably contains MEOA in an amount of 1 to 30 weight percent, more preferably 3 to 25 weight percent, and most preferably 5 to 20 weight percent.

[0106] 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 is preferably in the range of 0.001 to 5 weight percent, more preferably 0.01 to 3 weight percent, and most preferably 0.03 to 2.5 weight percent.

[0107] When the feed provided in step (i) is obtained by the above-described MEG process, the feed (i) provided in step (i) preferably contains 20 to 90 weight percent of MEG, more preferably 25 to 80 weight percent, and even more preferably 30 to 70 weight percent of MEG.

[0108] When the feed provided in step (i) is obtained by the MEG process, the feed preferably also contains 1 to 50 weight percent of MEOA, more preferably 3 to 30 weight percent, and even more preferably 5 to 25 weight percent of MEOA. As described above, the MEG content is preferably adjusted by the conversion degree of MEG in the MEG process.

[0109] In a particularly preferred embodiment, the feed provided in step (i) is: Water: 10 to 20 weight percent; NMEDA: 0.01 to 0.1 weight percent; EDA: 10 to 25 weight percent; PIP: 0.1 to 5 weight percent; MEOA: 10 to 20 weight percent; MEG: 30 to 50 weight percent; DETA 0.1 to 5 weight percent; AEPIP: 0.05 to 0.5 weight percent; AEEA: 0.1 to 5 weight percent; HEPIP: 0.01 to 0.5 weight percent; DEOA: 0.05 to 1 weight percent; TETA: 0.01 to 2 weight percent; HEDETA: 0.01 to 2 weight percent; Others: 0.001 to 5 weight percent including.

[0110] Step (i-c): Addition of additional adjuvant: The term additional adjuvant as used in the context of the present invention refers to an adjuvant that is neither an ethylene amine nor an ethanol amine. In particular, ethylene amines and ethanol amines selected from the group consisting of PIP, DETA, AEEA, AEP and mixtures thereof, as disclosed in U.S. Patent No. 4,032,411 (Berol Kemi AG), are not recognized as additional adjuvants.

[0111] The additional adjuvant is preferably a hydroxyl group-containing compound.

[0112] The additional adjuvant is more preferably: (i) an aliphatic monool, (ii) an aliphatic diol; (iii) an aliphatic triol; and (iv) an aliphatic tetrol a compound or mixture of compounds selected from the group consisting of.

[0113] Surprisingly, the azeotropic mixtures between EDA and water and / or between NMEDA and water can be effectively modified by these additional adjuvants, so that the separation step (ii) can be carried out particularly effectively, especially at a pressure below ambient pressure or moderate sub-atmospheric pressure, which is easier to achieve than the high pressure for destroying the azeotropic mixtures disclosed in German Patent No. 1258413 (DOW) or Pamphlet of International Publication No. 2021 / 115907 (BASF).

[0114] Preferred aliphatic monohydric alcohols are straight-chain or branched-chain alcohols having one hydroxy group containing 5 to 12 carbon atoms.

[0115] Particularly preferred aliphatic monohydric alcohols 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.

[0116] Preferred aliphatic diols are straight-chain or branched-chain aliphatic diols containing 2 to 6 carbon atoms. Particularly 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.

[0117] More preferred diols are ethylene glycol, propylene glycol, and butylene glycol consisting of 2 to 4 ethylene glycol, propylene glycol, or butylene glycol units, for example, 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.

[0118] 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 disrupt or otherwise modify the azeotrope formed between EDA and water.

[0119] Preferred aliphatic triols contain 3 to 6 carbon atoms. Particularly preferred aliphatic triols are glycerin and trimethylolpropane.

[0120] Preferred aliphatic tetrols contain 4 to 6 carbon atoms. Particularly preferred aliphatic tetrols are pentaerythritol, erythritol, or threitol.

[0121] More preferably, the additional adjuvant containing one or more hydroxyl groups has a boiling point higher than the boiling point of EDA or NMEDA but can still be separated from ethylene amines and ethanolamines using reasonable conditions. Such an adjuvant has the advantage that its azeotrope-modifying effect remains effective until NMDEA is effectively separated because it does not evaporate before or together with the separation of NMDEA.

[0122] Also, the additional adjuvant is preferably an aliphatic hydroxyl group-containing compound to avoid discoloration.

[0123] Furthermore, the additional adjuvant is preferably miscible with the product obtained by the EDA preparation process.

[0124] The most preferred additional adjuvants are 1,2 - diol and triethylene glycol (TEG). Particularly preferred 1,2 - diols are MEG, 1,2 - propylene glycol and 1,2 - butylene glycol.

[0125] MEG has the advantage of also being a raw material for EDA production.

[0126] When using MEG as an additional adjuvant, the amount of the additional adjuvant in the feed can be adjusted by controlling the conversion of MEG in the reaction with ammonia as described above.

[0127] TEG preferably has the advantage of being used as a distillation adjuvant for separating DETA from MEOA. The use of TEG has the advantage that not only is TEG used as an adjuvant for DETA / MEOA separation, but also further uses are found in the separation of NMEDA from EDA and water. Thus, only one adjuvant is required for both separations.

[0128] In a preferred embodiment, the additional adjuvant is added after step (i - a). The addition of the adjuvant after step (i - a) has the advantage that the hydroxyl group of the adjuvant is not aminated in step (i - a). This avoids the formation of additional amination products, which are not the ethyleneamines or ethanolamines essentially formed in the EDA preparation process and may need to be separated from the reaction mixture.

[0129] In another preferred embodiment, the additional adjuvant is added before or during step (i-a). This embodiment is particularly preferred when the adjuvant can be further converted to ethanolamine or ethyleneamine specific to the EDA preparation process.

[0130] The amount of the additional adjuvant containing one or more hydroxyl groups in the feed provided in step (i) is preferably such that the molar ratio (n(OH):n(EDA)) of all the hydroxyl groups (n(OH)) present in the feed to the amount of EDA is 0.7:1 or more, preferably 1:1 or more (1 or more:1), more preferably 1.5:1 (1.5 or more:1) or more, even more preferably 2:1 or more (2 or more:1), and most preferably 4:1 or more (4 or more:1).

[0131] When the adjuvant 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 (1 or more:1), more preferably 1.2:1 or more (1.2 or more:1), even more preferably 1.5:1 or more (1.5 or more:1), and most preferably 2:1 or more (2 or more:1).

[0132] The higher the ratio of the OH group to the amine group of EDA, the higher the azeotropic mixture modification effect.

[0133] The amount of the additional adjuvant is preferably determined based on the hydroxyl group concentration or diol concentration and EDA concentration in the feed and adjusted by adding the additional adjuvant.

[0134] When the additional adjuvant is not MEG, the amount of the additional adjuvant is preferably adjusted by adding the additional adjuvant before the separation step (ii), preferably after the removal of ammonia and / or hydrogen, so that the hydroxyl groups of the additional adjuvant are not aminated during the EDA preparation step (i-a).

[0135] When the additional adjuvant is MEG, the amount of the additional adjuvant is preferably adjusted by the conversion degree of MEG using ammonia in the MEG process as described above.

[0136] Separation step (ii): Surprisingly, when providing a feed stream containing EDA, NMEDA and water, the azeotropic mixtures formed between EDA and water and / or between NMEDA and water are disrupted or otherwise modified such that water can be separated from NMEDA and EDA in one or more distillation columns, and it has been found that water is separated from EDA and NMEDA as a low-boiling fraction. Usually, the disruption of the azeotrope formed between EDA and water and / or between NMEDA and water requires distillation at a higher pressure than where the azeotrope is disrupted. The present invention has the advantage that the separation of water from EDA and NMEDA can be carried out at a lower distillation pressure. Compared with the high-pressure separation process, the low-pressure process is more advantageous in terms of OPEX (operating expenses) and CAPEX (capital expenditure).

[0137] The feed supplied in step (i) is preferably 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 ranges from 1:100 to 100:1; c. Fraction C containing water and EDA, where the weight ratio of EDA to water is greater than 5:1 is separated into.

[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. 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.

[0139] 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.

[0140] NMEDA Removal Column - Single Column Setup In a preferred embodiment, the separation in step (ii) is carried out in a simple distillation column (NMEDA removal column) in which fraction A is withdrawn at the top, fraction B is withdrawn as a side fraction, and fraction C is withdrawn at the bottom of the distillation column.

[0141] The separation step (ii) according to the present invention can be carried out in a rectification apparatus, for example, a tray column such as a bubble cap tray column, a sieve tray column, a dual flow tray column, a valve tray column, a baffle tray column, or a column having random packings or structured packings. It is preferable to use an internal structure with low pressure loss in the form of structured packings, for example, sheet metal packings such as Mellapak 250Y or Montz Pak (type B1-250). It is also possible that there are packings with a small specific surface area or increased packing, or it is possible to use woven packings or packings of another shape such as Mellapak 252.Y. The advantage of using such an internal structure is that the pressure loss is low compared to, for example, valve trays, and the specific liquid hold-up is small.

[0142] The internal structure may be arranged on one or more floors.

[0143] Preferably, the rectification column contains structured packings, particularly Mellapak 250.

[0144] The design and layout of the NMEDA removal column are determined by the capacity to be produced. Usually, 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.

[0145] The number of theoretical plates of the NMEDA removal column is generally in the range of 10 to 40, preferably 15 to 35, more preferably 20 to 30.

[0146] In the NMEDA removal column, the energy required for the separation of the feed provided in step (i) 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 tube evaporator, a thin film evaporator or a short path evaporator.

[0147] The feed provided in step (i) containing EDA, NMEDA and water is preferably introduced into the space region of 25% to 75% of the theoretical plates of the NMEDA removal column. For example, the feed may be introduced into the middle section of the column. Preferably, the feed is introduced into 25 to 75% of the theoretical plates, more preferably 30 to 70% of the theoretical plates. For example, if the column has 25 theoretical plates, the feed is preferably introduced between the 10th and 15th plates.

[0148] The NMEDA removal column generally has a condenser, and this condenser is generally operated at a temperature at which the main part of fraction A is condensed at the corresponding top pressure.

[0149] Generally, the operating temperature of the condenser is in the range of 10 to 150 °C, preferably 50 to 140 °C, more preferably 80 to 120 °C.

[0150] Suitable condensers are condensers with cooling coils or helical tubes, jacketed tube condensers, and shell and tube heat exchangers.

[0151] 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 of 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.

[0152] 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.

[0153] In a preferred embodiment, the bottom temperature of the NMEDA removal column is 190 °C or lower, preferably 165 °C or lower, and most preferably 155 °C or lower. When the bottom temperature does not exceed such a value, the EDA loss in fraction A and fraction B can be further reduced.

[0154] 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 possible to use a reboiler with a short residence time, such as a falling film reboiler, a helical tube type reboiler, a thin film reboiler or a short path reboiler.

[0155] Fraction A containing water and NMEDA, in which the weight ratio of water to NMEDA in fraction A is more than 100:1, is preferably withdrawn from the top of the NMEDA removal column. More preferably, the weight ratio of water to NMEDA in fraction A is more than 500:1, even more preferably more than 1000:1, and most preferably more than 2000:1.

[0156] Preferably, fraction A contains 0.1 weight percent or less of NMEDA, more preferably 0.01 weight percent or less, and most preferably 0.001 weight percent or less of NMEDA.

[0157] Preferably, fraction A contains 0.01 weight percent or less of EDA, more preferably 0.001 weight percent or less, and most preferably 0.0001 weight percent or less of EDA.

[0158] Preferably, fraction A contains components having a boiling point higher than that of EDA in an amount of 0.01 percent or less, more preferably 0.001 percent or less, and most preferably 0.0001 percent or less.

[0159] Fraction A may contain some components having a boiling point lower than that of EDA other than water, such as methane or ammonia, in an amount of 0.1 weight percent or less, more preferably 0.08 weight percent or less, and most preferably 0.05 weight percent or less, respectively.

[0160] By removing fraction A with a low content of organic substances, fraction A can be efficiently discarded in a conventional water purification plant or directly reused in a process that requires water or other processes.

[0161] Fraction B, which contains water, NMEDA, and EDA and has a weight ratio of water to NMEDA 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 sufficient to substantially remove all of the NMEDA present in the feed to the NMEDA removal column. Preferably, the weight ratio of the weight 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 even more preferably 600:1 to 1000:1.

[0162] Fraction B is preferably withdrawn from a region between the middle and the top of the column, preferably in the region of 50 to 90 percent of the theoretical plates, more preferably in the region of 55 to 80 percent of the theoretical plates, and most preferably in the region of 60 to 70 percent of the theoretical plates. Preferably, fraction B is withdrawn above the feed to the NMEDA removal column.

[0163] Fraction B typically also includes some EDA, and the weight ratio of N-MEDA 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 N-MEDA, more preferably 20 to 70 weight percent, and even more preferably 30 to 60 weight percent of N-MEDA.

[0165] The removal of fraction B as a sidestream has the advantage that most of the N-MEDA formed in the EDA preparation process can be removed in a small but concentrated stream. Fraction B is preferably sent to incineration, which can efficiently dispose of the unwanted by-product N-MEDA while sacrificing only a very small amount of the valuable product EDA.

[0166] In a preferred embodiment, fraction C withdrawn preferably from the bottom of the N-MEDA removal column has a low water content, which 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 N-MEDA, preferably 0.05 weight percent or less, and more preferably 0.01 weight percent or less of N-MEDA.

[0168] Fraction C preferably contains 1 to 30 weight percent of EDA, preferably 5 to 25 weight percent, and more preferably 7.5 to 15 weight percent of EDA.

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

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

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

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

[0173] Additional Dehydration Column In a particularly preferred embodiment, the fraction C preferably withdrawn from the bottom of the first or second NMEDA removal column has a high water content.

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

[0175] In this embodiment, the subsequent separation step not only enables further reduction of the water content but also further reduction of the NMEDA content, thereby obtaining EDA having an even lower NMDEA content. This ultra-low NMDEA content enables, as further described below, separation of EDA and PIP from high-boiling components, particularly MEOA and MEG, in a single dividing wall column, which will later simplify further work-up of the ethyleneamine mixture.

[0176] In this particularly preferred embodiment, the water content of fraction C ranges from 0.1 to 10 wt%, preferably from 0.5 to 5 wt%.

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

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

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

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

[0181] When the water content of fraction C is within the range described in the particularly preferred embodiment having a higher water content as defined above, fraction C further: - contains EDA, NMEDA, and water, and 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, and most preferably 30:1 to 10:14, a fraction C-1 - It contains EDA and a component preferably having a boiling point higher than that of EDA, and the NMEDA content in fraction C-2 is preferably 0.01 wt% or less, more preferably 0.001 wt% or less, and most preferably 0.0001 wt% or less, and 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 directly reused at the bottom of the NMEDA removal column as a vapor phase 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 in 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 column is usually a tray column, a bubble cap tray column, a sieve tray column, a dual flow tray column, a valve tray column, a baffle tray column or a column with irregular packing or structured packing. It is preferable to use an internal structure with low pressure loss in the form of structured packing, for example, sheet metal packing such as Mellapak 250Y or Montz Pak (type B1-250). It is also possible that there is packing with a small specific surface area or increased packing, or it is possible to use woven packing or packing of another shape such as Mellapak 252.Y. The advantage of using such an internal structure is that, for example, the pressure loss is lower and the specific liquid holdup is smaller compared to a valve tray.

[0186] The internal structure may be arranged on one or more floors.

[0187] Preferably, the removal water removal column contains structured packing, especially Mellapak 250.

[0188] The theoretical number of trays in the residual water removal column 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 removal water 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 possible to use a reboiler with a short residence time, such as a falling film reboiler, a helical tube type reboiler, a thin film reboiler or a short path reboiler.

[0190] Fraction C from the NMEDA removal column is preferably introduced at the top of the residual water removal column. Therefore, preferably, the residual water removal column 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 withdrawn at the top of the column is preferably reused in the sump of the NMEDA removal column through a valve.

[0192] 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 of 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 tower is preferably connected to an evaporator (reboiler) at the bottom of the tower. 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 tube evaporator, a thin film evaporator, or a short path evaporator.

[0195] In a preferred embodiment where MEG is used as the sole additional adjuvant, the preferred composition of fraction C-2 withdrawn at the bottom of the residual water removal tower is: MEG: 20 - 60, preferably 30 - 50 weight percent, and MEOA: 10 - 40, preferably 15 - 25 weight percent, and EDA: 10 - 50, preferably 20 - 40 weight percent, and PIP: 0.1 - 10, preferably 0.5 - 5 weight percent, and DETA: 0.1 - 10, preferably 0.5 - 5 weight percent, and AEEA: 0.1 - 10, preferably 0.5 - 5 weight percent, and DEOA: 0.05 - 2, preferably 0.1 - 1 weight percent, and TETA: 0.01 - 2, preferably 0.05 - 0.5 weight percent, and Water: 0.001 - 0.5, preferably 0.01 - 0.1 weight percent, and NMEDA: 0.005, preferably 0.0005 weight percent and

[0196] Downstream separation and reuse: Fraction C or fraction C-2 can be further separated in a series of downstream separation steps.

[0197] The downstream separation steps are preferably carried out in a conventional tower or a dividing wall column.

[0198] In a particularly preferred separation sequence, fraction C-2 from the bottom of the residual water removal tower is: - fraction D-1 containing EDA, and - fraction D-2 containing PIP, - A fraction D-3 containing components having a boiling point higher than PIP, especially MEOA, MEG, DETA, AEE, DEOA and TETA, and is separated into.

[0199] Preferably, the separation into fraction D-1, fraction D-2 and fraction D-3 is preferably carried out in a single dividing wall column. This dividing wall column may 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 high-boiling ethanolamines and ethyleneamines. The teachings of WO 2005 / 037769 pamphlet are incorporated herein by reference.

[0200] Fraction D-1 preferably contains a water content of 0.1 wt% or less, preferably 0.08 wt% or less, more preferably 0.05 wt% or less.

[0201] Fraction D-1 preferably contains a PIP content of 0.05 wt% or less, more preferably 0.01 wt% or less, still more preferably 0.005 wt% or less.

[0202] Fraction D-1 preferably contains an NMEDA content of 0.05 wt% or less, more preferably 0.001 wt% or less, still more preferably 0.0005 wt% or less.

[0203] Fraction D-2 preferably contains an EDA content of 0.3 wt% or less, more preferably 0.2 wt% or less, still more preferably 0.1 wt% or less.

[0204] Fraction D-2 preferably contains a water content of 0.05 wt% or less, more preferably 0.01 wt% or less, still more preferably 0.005 wt% or less.

[0205] Fraction D-2 preferably contains an NMEDA content of 0.01 wt% or less, more preferably 0.001 wt% or less, and even more preferably 0.0001 wt% or less.

[0206] Fraction D-2 preferably contains an EDA content of 0.1 wt% or less, more preferably 0.05 wt% or less, and even more preferably 0.01 wt% or less.

[0207] 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 sales specifications of ultra-low NMEDA content, thereby reducing capital and operating expenses compared to a conventional setup where the separation of EDA and PIP in a further column follows the EDA / PIP separation column.

[0208] Fraction D-3 is preferably separated in one or more further separation steps into valuable fractions or fractions that can be easily reused in the EDA preparation process. More preferably, fraction D-3 is separated into valuable fractions or fractions that can be provided to an additional MEOA process or MEOA reactor as described above.

[0209] Fraction D-3 preferably further comprises: - Fraction E-1 containing MEOA having a MEG content of preferably 2000 ppm or less, preferably 1500 ppm or less, and more preferably 1000 ppm or less; - Fraction E-2 containing components having a higher boiling point than MEOA, in particular MEG, DETA, AEE, DEOA, and TETA and is separated into.

[0210] This separation step is preferably carried out in a conventional column when preferred.

[0211] Fraction E-1 is preferably fed to the MEOA reactor, and MEOA is converted to ethyleneamine and ethanolamine using ammonia in the presence of an amination catalyst and hydrogen as disclosed in the previous section. The product of the MEOA conversion reactor can be combined with the product of the MEG conversion reactor and separated using the same separation sequence and equipment as also disclosed above.

[0212] Fraction E-2 is preferably: - Fraction F-1 containing MEG and preferably MEOA at 1000 ppm or less, more preferably 800 ppm or less, and 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 are separated.

[0213] This separation step is preferably carried out in a conventional column.

[0214] Fraction F-1 is preferably recycled to the MEG reactor, where MEG is converted to MEOA and ethyleneamine and ethanolamine using ammonia in the presence of hydrogen and an amination catalyst.

[0215] Fraction F-2 is preferably: - Fraction G-1 containing DETA, MEG, and AEPIP, and - Fraction G-2 containing AEEA and HEPIP are separated.

[0216] Fraction G-1 is further: - Fraction H-1 containing MEG, and - Fraction H-2 containing DETA and AEPIP can be separated.

[0217] This separation step is preferably carried out in a conventional column.

[0218] Fraction H-2 is preferably further: - Fraction I-1 containing DETA, and - Fraction I-2 containing DETA and AEPIP and is separated into them.

[0219] Fraction I-1 can be used as a valuable fraction of DETA that meets the sales specifications.

[0220] Fraction I-2 is preferably recycled to the column where Fraction G-1 is separated.

[0221] Fraction G-2 is further separated into: - Fraction J-1 containing AEEA and HEPIP, and - J-2 containing AEEA, DEOA, TETA and HEDETA and can be separated into them.

[0222] This separation step is preferably carried out in a conventional column.

[0223] Fraction J-1 is preferably recycled to the MEOA reactor.

[0224] Fraction J-2 is further separated into: - Fraction K-1 containing AEEA, and - K-2 containing DEOA, TETA and HEDETA and can be separated into them.

[0225] Fraction K-1 can be used as a valuable fraction of AEEA that meets the normal sales specifications of AEEA.

[0226] Fraction K-2 can be used as a mixed fraction for specific applications or can be further separated into a fraction consisting essentially of DEOA, TETA and HEDETA.

[0227] When using one or more of the above-described separation steps, the ethanolamine and ethyleneamine obtained in the EDA preparation process can be separated into a fraction containing a single valuable product such as AEEA, DETA, EDA, and PIP, or a fraction containing an ethanolamine mixture that can be easily reused in an additional MEOA process, particularly in a reactor (MEOA reactor) where MEOA and other alkanolamines are converted to ethyleneamine. The above-described process sequence focuses on obtaining a limited number of valuable products such as AEEA, DETA, EDA, and PIP, and a fraction that can be reused in the EDA preparation process. In this way, a limited number of separation steps are required to prevent losses through unwanted by-products or components.

[0228] In another preferred embodiment, fraction C is further separated into: without further separating fraction C into further fraction C-1 and fraction C-2: - fraction D-1 containing EDA, - fraction D-2 containing EDA, PIP, and MEOA, - fraction D-3 containing MEG, and components having a boiling point higher than MEG, particularly DETA, AEE, DEOA, and TETA and is separated into.

[0229] This separation step is preferably carried out in a conventional column, fraction D-1 is withdrawn as the top product, fraction D-2 is withdrawn as a side draw, and fraction D-3 is withdrawn as the bottom product.

[0230] Fraction D-1 essentially contains EDA and has a water content of 0.2 weight percent or less, preferably 0.15 weight percent or less, more preferably 0.1 weight percent or less.

[0231] The NMEDA content is preferably 0.1 weight percent or less, more preferably 0.08 weight percent or less, and most preferably 0.05 weight percent or less.

[0232] 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, and about 1-5 wt% each of EDA and PIP.

[0233] Fraction D-2 preferably further comprises: - Fraction E-1 containing EDA and PIP, - Fraction E-2 containing MEOA and is separated into.

[0234] This separation step is preferably carried out in a conventional column when preferred.

[0235] Fraction E-1 is preferably further separated into a fraction F-1 containing EDA and a fraction F-2 containing PIP.

[0236] Fraction E-2 is preferably reused in the MEOA process step incorporated into the process.

[0237] Fraction D-3 preferably comprises: - Fraction G-1 containing MEG, - Fraction G-2 containing DETA and components having a boiling point higher than that of DETA and is separated into.

[0238] Fraction G-1 is preferably reused in the MEG process step or used as a scrubbing liquid for washing MEG in the ammonia / hydrogen removal step (i-b) as described above before being reused in the MEG process step.

[0239] Fraction G-2 preferably comprises: - Fraction H-1 containing MEG and DETA, - Fraction H-2 containing AEEA, DEOA and TETA and is separated into.

[0240] This separation step is preferably carried out in a conventional column when preferred.

[0241] Fraction H-1 is preferably recycled to the MEG process.

[0242] Fraction H-2 containing the highest boiling point components is preferably removed from the process and sent to the flare or separated into individual components in a further separation step.

[0243] The separation sequence according to the invention enables the production of EDA with an NMEDA content within the specifications.

[0244] In the separation step of the present invention, the removal of NMEDA and water can be carried out under ambient pressure or slightly below atmospheric pressure conditions, which are easier to implement than the high-pressure separation processes known in the prior art. Therefore, NMEDA and water can be efficiently removed with only a small amount of operating and capital expenditures.

[0245] The separation of the present invention enables a subsequent downstream separation sequence, thereby obtaining fractions with values within the specifications.

[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 in either the MEG process or the MEOA process step.

[0247] The separation step of the present invention enables the design of the entire MEG process, enabling high selectivity and yield of desired valuable products such as EDA, DETA, AEEA, and PIP, while minimizing losses through unwanted by-products.

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

[0249] In a more preferred embodiment, the water content in fraction C is adjusted to a higher level, whereby residual moisture and NMEDA can be removed in a further separation step. Combining the NMEDA removal column and the residual water removal column can obtain an ultra-low water content and / or an ultra-low NMEDA content in EDA. Combining the NMEDA removal column and the residual water removal column also enables the subsequent separation of valuable products EDA and PIP to be carried out in a single dividing wall column, as compared to a two-column setup where EDA and PIP are separated conventionally. The use of a dividing wall column brings further positive effects on capital expenditure and operating expenditure.

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

Example

[0251] This example is based on calculations using a process simulation model.

[0252] The simulation was performed using CHEMASIM (registered trademark). The DIPPR correlation was used for calculating the thermodynamic properties of pure components such as vapor pressure. For the description of the vapor phase, the ideal gas law was used, and the NRTL excess Gibbs energy model was used for the description of the liquid phase. The parameters of the DIPPR correlation and the NRTL model were adjusted according to experimental data. For components without available experimental data, 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 adopted simulation and thermodynamic property models were adjusted to reproduce experimental data and plant data with very high accuracy.

[0253] Example 1: The feed was prepared by a combined MEG / MEOA process.

[0254] After the removal of hydrogen and ammonia, the feed consisted of the following: Water: 15.80 weight percent 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%

[0255] 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.

[0256] 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.

[0257] The NMEDA removal column was equipped with a reboiler and had 28 trays.

[0258] The feed was introduced above tray 12 (counting from the bottom).

[0259] The bottom temperature was 159 °C.

[0260] Fraction A, containing water and 100 ppm by weight of NMEDA (weight ratio of water to NMEDA: approximately 10000:1), weighing 644.26 kg / g, was withdrawn from the top of the column and fed to a condenser operating at 100 °C.

[0261] A condensed stream of 372.12 kg / h was refluxed to the top of the NMEDA removal column, and a stream of 272.13 kg / h was removed.

[0262] Fraction B, consisting of the following and weighing 1.58 kg / h: 40.1 wt% water; 41.8 wt% NMEDA; and 18.1 wt% EDA It was withdrawn as a side draw between stage 17 and stage 18.

[0263] Therefore, the weight ratio of water to NMEDA was about 0.96:1.

[0264] Fraction C of 1847.93 kg / h consisting of the following Water: 1.05 weight percent NMEDA: 0.01 weight percent EDA: 32.40 weight percent PIP: 2.30 weight percent MEOA: 18.55 weight percent MEG: 41.11 weight percent DETA: 1.88 weight percent AEPIP: 0.20 weight percent AEEA: 1.57 weight percent 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 about 30.9 to 1.

[0265] 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.

[0266] Fraction C was introduced above stage 36.

[0267] The residual water removal column was operated at a bottom temperature of 181 °C and a top pressure of 1.3 bar.

[0268] Fraction C-1 of 395.93 kg / h consisting of the following was: Water: 4.86 weight percent NMEDA: 0.028 weight percent EDA: 69.36 weight percent PIP: 2.88 weight percent MEOA: 13.91 weight percent MEG: 8.55 weight percent DETA: 0.24 weight percent AEPIP: 0.03 wt% AEEA: 0.12 wt% It was withdrawn from the top of the residual water removal column. This stream was directly fed to the bottom of the NMEDA removal column in the form of vapor without condensation.

[0269] Fraction C-2 consisting of 1452.00 kg / h from the following: 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% It was withdrawn from the bottom of the residual water removal column and purified in a dividing wall column. A pure EDA fraction containing 500 ppm by weight of water and 2 ppm by weight of NMEDA was obtained.

[0270] Example 2: Providing a feed containing EDA, NMEDA and water The feed was prepared by a combined MEG / MEOA process.

[0271] After removal of hydrogen and ammonia, the feed consisted of the following: Water: 9.03 wt% NMEDA: 0.07 wt% EDA: 7.07 wt% PIP: 0.72 wt% MEOA: 12.96 wt% MEG: 68.82 wt% DETA: 0.72 wt% AEEA: 0.07 wt% TETA: 0.51 wt%

[0272] The molar ratio of MEG to EDA in the feed stream is 9.43 to 1. The molar ratio of hydroxyl groups to EDA was approximately 18.9:1.

[0273] A feed stream of 2459.7 kg / h was fed to the NMEDA removal column, where the feed was separated into fraction A, fraction B, and fraction C.

[0274] The NMEDA removal column was equipped with a reboiler and had 25 trays.

[0275] The feed was introduced above tray 12 (counting from the bottom).

[0276] The bottom temperature was 180 °C.

[0277] Fraction A, containing water and 100 weight ppm of NMEDA (weight ratio of water to NMEDA: approximately 10000:1), weighing 354.15 kg / g, was withdrawn from the top of the column and fed to a condenser operating at 100 °C.

[0278] A condensed stream of 134.79 kg / h was refluxed to the NMEDA removal column, and a stream of 219.36 kg / h was removed.

[0279] Fraction A, containing water and 100 weight ppm of NMEDA, was removed from the top of the column. Thus, the weight ratio of water to NMEDA was approximately 10000:1.

[0280] Fraction B, consisting of the following and weighing 4.35 kg / h: 5.43 weight percent water; 36.9 weight percent NMEDA; and 7.62 weight percent EDA was withdrawn as a side draw between trays 16 and 17.

[0281] Thus, the weight ratio of water to NMEDA was approximately 6.17:1.

[0282] Fraction C, consisting of the following and weighing 2235.92 kg / h 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 was withdrawn from the bottom of the NMEDA removal column. The weight ratio of EDA to water in Fraction C was about 236.5 to 1.

[0283] Fraction C was purified in a distillation column having 60 trays. Fraction C was fed to the column between trays 36 and 37 (counting from the bottom). An overhead fraction composed of 99.80 weight percent EDA, 0.12 weight percent water, 0.03 weight percent NMEDA and 0.05 weight percent PIP was obtained.

[0284] Example 1 shows that commercial grade EDA can be obtained in just one additional distillation step by separating the feed stream from the EDA preparation process into the fractions according to the invention from the NMEDA removal column. The loss of EDA is relatively small and of the same order as the NMEDA present in the feed.

[0285] In Example 2, the moisture concentration at the bottom of the NMEDA removal column is relatively high. Thereby, EDA having an ultra-low NMEDA content can be obtained.

Claims

1. Water (H ２ O) A method for producing ethyleneamine from a mixture containing ethylenediamine (EDA) and N-methylethylenediamine (NMEDA): (i) A step of providing a feed flow containing EDA, NMEDA, water, and additional adjuvants, (ii) A step in which water is separated from the NMEDA and EDA contained in the feed stream in one or more distillation columns, and the water is separated from the EDA and NMEDA as a low boiling fraction. A method that includes this.

2. The method according to claim 1, wherein the additional adjuvant is a compound other than ethanolamine or ethyleneamine.

3. The method according to claim 1 or 2, wherein the additional adjuvant is a compound containing a hydroxyl group.

4. The aforementioned additional adjuvant is: (v) Aliphatic monools, (vi) aliphatic diols; (vii) aliphatic triols; and (viiii) Aliphatic Tetra The method according to claim 1 or 2, selected from the group consisting of the following.

5. The method according to claim 4, wherein the additional adjuvant is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, di-1,2-propylene glycol, tri-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propylene glycol, trimethylolpropane, glycerol, and pentaerythritol.

6. The method according to claim 1 or 2, wherein the additional adjuvant in step (i) is ethylene glycol (MEG), 1,2-propylene glycol, 1,2-butanediol and / or triethylene glycol (TEG).

7. The method according to claim 1 or 2, wherein the amount of additional adjuvant provided in step (i) is adjusted so that the molar ratio of hydroxyl groups in the feed to EDA molecules in the feed is 1 or more:

1.

8. Providing the feed in process (i) means: (i-a) A step of carrying out an EDA preparation process to obtain an output containing EDA, NMEDA, and water; (i-b) A step to remove ammonia and / or hydrogen from the product generated in step (i-a); (i-c) A step of adding the additional adjuvant to the EDA preparation process before, during, or after step (i-a), or after the removal of ammonia and / or hydrogen in step (i-b). The method according to claim 1 or 2, including the method described in claim 1 or 2.

9. In the EDA preparation process of step (i-a), ethylene glycol (MEG) is converted using ammonia in the presence of an amination catalyst and hydrogen. The aforementioned additional adjuvant is MEG. The aforementioned additional adjuvant is added as a free substance in step (i-a). The method according to claim 1 or 2.

10. The method according to claim 9, wherein the conversion of MEG in step (i-a) is carried out such that the feed provided in step (i) contains 30 to 70 weight percent MEG.

11. The method according to claim 1 or 2, wherein the feed provided in step (i) further comprises a component having a higher boiling point than EDA.

12. The method according to claim 11, wherein one of the components having a higher boiling point than EDA is monoethanolamine (MEOA), and the amount of MEOA contained in the feed is 3 to 25 percent by weight.

13. The separation in step (ii) is carried out in one or more distillation columns: a. Fraction A containing water and NMEDA, wherein the weight ratio of water to NMEDA in fraction A is greater than 1000:1; b. Distillate B containing water, NMEDA, and EDA, wherein the weight ratio of water to NMEDA is in the range of 1:1000 to 1000:1; c. A fraction C containing water and EDA, where the weight ratio of EDA to water is greater than 100:

1. The method according to claim 1 or 2, wherein the parts are separated.

14. The method according to claim 13, wherein fraction A is withdrawn at the top, fraction B is withdrawn as an auxiliary fraction, and fraction C is withdrawn at the bottom of the distillation column.

15. The method according to claim 13, wherein the water content of fraction C is in the range of 0.5 to 5 weight percent.

16. The fraction C is: - Fraction C-1 containing EDA, NMEDA, and water, wherein 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 preferably in the range of 100:1 to 1:1, - Fraction C-2 containing EDA and preferably a component having a higher boiling point than EDA, with an NMEDA content of 0.01 weight percent or less. The method according to claim 15, which is separated into

17. Fraction C-2 further: - Fraction D-1 containing EDA, - Fraction D-2 containing PIP, - Fraction D-3 containing components with a higher boiling point than PIP The method according to claim 16, which is separated into

18. The method according to claim 17, wherein the separation of fraction C-2 is carried out in a single partitioned column.

19. The method according to claim 1 or 2, wherein the separation step (ii) is carried out under conditions in which the azeotrope between the EDA and water is broken or otherwise modified so that the water can be separated from the NMEDA and EDA as a low-boiling fraction.

20. The method according to claim 1 or 2, wherein the separation (ii) is performed at a pressure of 3 bar or less.

21. Use of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, di-1,2-propylene glycol, tri-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propylene glycol, trimethylolpropane, glycerol, pentaerythritol, or mixtures thereof as distillation adjuvants for the distillation of a mixture containing water, ethylenediamine, and N-methylethylenediamine.