Process for the production of ethylene amines

Abstract

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

Description

[0001] The present invention relates to a process for producing ethylenediamine (EDA) and to the use of certain hydroxyl-containing compounds as distillation aids for the distillation of a mixture comprising water, ethylenediamine and N-methylethylenediamine.

[0002] Ethylenediamine is primarily used as an intermediate for the production of bleach activators, crop protection agents, pharmaceuticals, lubricants, textile resins, polyamides, papermaking aids, gasoline additives and many other substances.

[0003] There are many known methods for preparing EDA (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 produce EDA, the degradation reaction of monoethanolamine can directly produce carbon monoxide (CO) and methylamine (decarbonylation). Methylamine can in turn directly react with further monoethanolamine to produce NMEDA.

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

[0006] NMEDA can also be formed in the preparation of EDA from C1 units such as hydrogen cyanide and formaldehyde.

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

[0008] For most industrial applications, the market requires an EDA purity of at least 99.5% by weight. Organic secondary components including NMEDA may be present in a proportion of no more than 0.5% by weight. In addition, the water content may not exceed 0.5% by weight. More particularly, in many industrial applications, a purity of EDA is specified in which the proportion of NMEDA is less than 1000 ppm by weight.

[0009] EDA which, as a result of its preparation, has a higher water and / or NMEDA content must be worked up accordingly in order to obtain EDA with the desired specifications.

[0010] A challenge encountered in the separation of ethyleneamine mixtures is that EDA and water, as well as NMEDA and water, form azeotropes. Azeotropic mixtures cannot be separated by conventional distillation. On the other hand, the formation of azeotropic hydrates of EDA and NMEDA can enhance the boiling point difference between NMEDA and EDA, making the separation of NMEDA and EDA less difficult under the conditions of their corresponding hydrate formation.

[0011] Depending on the amount of NMEDA in the ethylenediamine mixture, different distillation strategies can be employed for the ethyleneamine mixture comprising NMEDA, EDA and water.

[0012] If the ethylenediamine mixture contains significant amounts of NMEDA, the NMEDA is usually separated prior to removing the water.

[0013] EP2487151 (Dow) discloses a process for removing alkylethyleneamines from an ethyleneamine mixture, wherein a mixture consisting of ethylenediamine, water and one or more alkylethylenediamines is subjected to conditions such that an azeotrope is formed between water and the alkylethyleneamines, and the azeotrope of water and NMEDA is separated from the remaining composition. It is disclosed that the pressure in the rectification column in which the azeotrope of water and alkylethylenediamines 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 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 about the distillation, the disclosure does not seem to contain any further technical information about what measures a person skilled in the art must take to form an azeotrope of alkylethyleneamines and water.

[0014] Another method for separating NMEDA from EDA and water is disclosed in EP2507202 (BASF). This disclosure teaches that the removal of NMEDA is carried out in a distillation column at a column top pressure in the range of 0.01 bar to 4 bar and that the mixture to be distilled contains an amount of water at least sufficient to satisfy the condition H=a*X / Y, where H is the weight proportion of water in the mixture to be distilled, X is the weight proportion of water at the azeotropic point of the binary mixture of water and EDA at the column pressure in question, Y is the weight proportion of EDA at the azeotropic point, and a is a real number having a value of 0.9 or more.

[0015] In WO 2019 / 081284 (BASF), a process for separating NMEDA from EDA and water is disclosed, wherein the NMEDA separation column is operated at a bottom temperature of 155° C. and below, and wherein the NMEDA separation column comprises 50 to 140 theoretical plates. NMEDA is discharged at the top of the column and an azeotropic mixture of EDA / water is discharged at the bottom of the column.

[0016] After removal of NMEDA or if the NMEDA concentration is lower to begin with, the EDA / water mixture can be separated in different ways.

[0017] DE 1258413 (Dow) discloses the separation of EDA and water in a single dehydration column operated at a pressure at which the azeotrope between water and EDA is broken, allowing water to be removed at the top of the distillation column and EDA and other amines to be removed from a storage tank.

[0018] Alternatively, EDA and water can be separated in two columns operating at different pressures (dual pressure distillation or pressure swing distillation) (see Fulgueras, AM, Poudel, J., Kim, DS et al. Korean J. Chem. Eng. (2016) 33: 46. https: / / doi.org / 10.1007 / s11814-015-0100-4).

[0019] US2017217874 discloses separating a feed comprising NMEDA, EDA and water by first separating water under high pressure and non-azeotropic conditions and separating the NMEDA / EDA mixture obtained at the bottom of the first column in a second column.

[0020] Several patent applications (CN105585508 (Sinopec), CN105585508 (Sinopec), CN105585501 (Sinopec), CN105585501 (Sinopec), CN104119297 (Xi'an Modern Chemistry Research Institute), CN104230850 (Sinopec), CN105523943 (Sinopec)) teach the use of entrainers (such as toluene or xylene) that form low-boiling azeotropes with water to separate water and ethylenediamine.

[0021] US3055809 (Jefferson Chemicals) discloses the distillation of an EDA / water mixture under azeotropic conditions. The water / EDA mixture is fed into the middle of a distillation column. A high boiling point extraction solvent is fed into the top of the distillation column where it flows in countercurrent to the rising azeotropic EDA / water vapor. By contacting the EDA / water with the high boiling point extractant, the EDA is substantially enriched in the extraction solvent so that substantially 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 having a boiling point above 120°C, such as polyols, including glycols (such as ethylene glycol (MEG), propylene glycol and butanediol) and glycerol (such as glycerol). Other effective solvents are hydroxylamines or alkanolamines, such as monoethanolamine (MEOA), diethanolamine (DEOA), triethanolamine (TEOA) and propanolamine.

[0022] WO2021 / 115907 (BASF) discloses distilling NMEDA, water and EDA in a single distillation column at a pressure where the azeotrope between EDA and water is destroyed. Within a narrow pressure range, the separation of NMEDA, EDA and water can be carried out in a single column.

[0023] In US4032411 (Berol Kemi), a water / EDA mixture is distilled in the presence of a distillation auxiliary. The distillation auxiliary is described as acting as an azeotrope breaker. Thus, in a mixture of water, EDA and distillation auxiliary, the azeotrope between water and EDA is broken, so that water can be taken off at the top of the column and a mixture of EDA and distillation auxiliary can be taken off at the bottom of the distillation column. The following compounds are disclosed as suitable distillation auxiliary agents: PIP, DETA, AEEA, AEP and mixtures thereof. The distillation is carried out at about 1 to 3 bar, wherein the temperature at the bottom of the distillation column varies between 140°C and 210°C. According to the invention, in order for the distillation to be carried out under technically appropriate conditions to allow the removal of water from EDA without forming an azeotrope, the weight ratio between the distillation auxiliary and EDA should be in the range of about 2:8 to 9:1, preferably about 4:6 to 8:2. According to the invention, when preparing EDA with a very low water content of less than 2% by weight, it is preferred to carry out the distillation in more than one distillation column, because otherwise very high distillation temperatures would be required, which could lead to decomposition of the amino compound and the column would require a large number of theoretical plates. Therefore, a preferred embodiment of the invention of US 4032411 comprises the steps of first removing most of the water present in the aqueous EDA solution by distillation in the presence of one or more auxiliary agents, then removing the auxiliary agents and finally carrying out a vacuum distillation to remove additional water.

[0024] Depending on the composition of the ethyleneamine mixture, it may be challenging to separate the components to obtain EDA within specifications. When distilling under azeotropic conditions to remove NMEDA, the ratio of water to NMEDA and EDA needs to be controlled 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 entrainers, distillation aids, or extraction solvents may require the addition of additional components, which may need to be removed from the final product. Distillation under non-azeotropic conditions without the addition of entrainers, adjuvants, or extraction solvents generally requires high operating pressures for the distillation column.

[0025] Therefore, there is a continuing need for a method that allows the use of an economical distillation process to manufacture within-specification EDA, which has a reasonable number of towers and in which these towers can be operated with a reasonable number of trays and at reasonable temperatures and pressures. There is also a continuing need for such a method in which components that are not generated or converted in the process itself are avoided. The use of such additional components requires that the equipment be sized larger to handle these additional components, and these additional components generally need to be separated in additional steps to allow such adjuvants to be recycled into the process. Therefore, an object of the present invention is to provide a method for producing EDA, which uses a reasonable number of distillation towers, reasonably sizes the towers and operates such towers under reasonable conditions (such as temperature and pressure), wherein with respect to the foregoing, reasonably means finding a suitable balance between operating expenses, capital expenditures and product quality.

[0026] The object of the present invention is achieved by the following items

[0027] A process for producing ethyleneamines from a mixture comprising water (HO), ethylenediamine (EDA) and N-methylethylenediamine (NMEDA), the process comprising the steps of:

[0028] (i) providing a feed stream comprising EDA, NMEDA, water and additional adjuvants,

[0029] (ii) separating water from NMEDA and EDA contained in the feed stream in one or more distillation columns, wherein water is separated from EDA and NMEDA as a low boiling fraction.

[0030] The object of the present invention is also achieved by the following items:

[0031] Use of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,2-butylene glycol, 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 aids for the distillation of a mixture comprising water, ethylenediamine and N-methylethylenediamine.

[0032] Surprisingly, it was found that when the feed is separated into fractions according to the invention, the downstream separation steps can be tailored to allow the feed to be separated economically into the desired valuable components and to be obtained in high quality. Furthermore, it was found that separating the feed according to the invention allows NMEDA to be effectively separated from EDA under reasonable distillation conditions using a reasonable number of columns, so that a separation process with a good balance and favorable operating and capital expenditures is obtained.

[0033] The following abbreviations are used in this article:

[0034] AEEA: aminoethylethanolamine

[0035] AEP: aminoethylpiperazine

[0036] DEOA: Diethanolamine

[0037] DETA: Diethylenetriamine

[0038] EDA: Ethylenediamine

[0039] EDC: Ethylene dichloride

[0040] HEDETA: Hydroxyethyldiethyltriamine

[0041] HEPIP: Hydroxyethylpiperazine

[0042] HPA: Heavy Polyamine

[0043] MEOA: Monoethanolamine

[0044] MEG: Monoethylene glycol

[0045] NMEDA: N-Methylethylenediamine

[0046] PEHA: Pentaethylenehexamine

[0047] PIP: Piperazine

[0048] TEPA: Tetraethylenepentamine

[0049] TETA: triethylenetetramine

[0050] Unless otherwise stated, pressure values ​​relate to absolute pressure values.

[0051] As used herein, the term ethyleneamine includes ethylenediamine (EDA) and its linear homologues having the general formula (I):

[0052] R-CH 2 -CH 2 -NH 2 (I)

[0053] Wherein R is a 2 -CH 2 ) X -NH 2 wherein 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 comprises DETA, TETA and TEPA, more preferably DETA and TETA and especially preferably DETA; and

[0054] The cyclic component has the general formula (II):

[0055]

[0056] Where R 1 and R 2 independently or simultaneously H or having the formula -(CH 2 -CH 2 -NH) X -CH 2 -CH 2 -NH 2 wherein X is an integer in the range of 0 to 4, preferably 0 to 4 and more preferably 1 to 2.

[0057] Examples of linear ethyleneamines are DETA, TETA, TEPA and HEPA.

[0058] Examples of cyclic ethyleneamines are PIP and AEPIP.

[0059] The term ethanolamine as used herein includes monoethanolamine (MEOA) and its linear homologues having the general formula (III):

[0060] R-CH 2 -CH 2 -OH(III)

[0061] Wherein R is a 2 -CH 2 ) X -NH 2 wherein x is an integer in the range of 1 to 4, preferably 1 to 3 and most preferably 1 to 2.

[0062] Examples of higher linear ethanolamines are AEEA, HEDETA.

[0063] The term ethanolamine as used herein also includes cyclic ethanolamines having formula (IV)

[0064]

[0065] Where R 1 is a compound having the formula –(CH 2 -CH 2 -NH) X -CH 2 -CH 2 -OH, wherein x is an integer in the range of 0 to 4, preferably 0 to 3 and more preferably 1 to 2, and

[0066] R 2 independently or simultaneously H; or having the formula -(CH 2 -CH 2 -NH) X -CH 2 -CH 2 -OH, wherein x is an integer in the range of 0 to 4, preferably 0 to 3 and more preferably 1 to 2; or a group having the formula -(CH 2 -CH 2 -NH) X -CH 2 -CH 2 -NH 2 wherein x is an integer in the range of 0 to 4, preferably 0 to 3 and more preferably 1 to 2.

[0067] An example of a cyclic ethanolamine is hydroxyethylpiperazine (HEPIP).

[0068] Step (i): Providing a feed stream comprising EDA, NMEDA and water:

[0069] The process according to the invention comprises a step (i) of providing a feed stream comprising EDA, NMEDA, water and additional adjuvants.

[0070] In a preferred embodiment, providing a feed comprising EDA, NMEDA, water and additional adjuvants in step (i) comprises the following steps:

[0071] (ia) performing an EDA preparation process to obtain an output comprising EDA, NMEDA and water; and

[0072] (ib) removing ammonia and / or hydrogen from the output produced in step (ia); and

[0073] (ic) adding additional auxiliary agents to the EDA preparation process before, during or after step (ia) or after the removal of ammonia and / or hydrogen in step (ib).

[0074] Step (ia): EDA preparation method:

[0075] The feed provided in step (i) is preferably provided by carrying out an EDA preparation process.

[0076] The EDA preparation method of step (ia) can be any known method for making EDA, such as the MEOA method, the C1 method, the EDC method or the MEG method, as described below.

[0077] MEOA Method:

[0078] The reaction of MEOA and ammonia is described, for example, in US Pat. No. 2,861,995, DE-A-1 172 268 and US Pat. No. 3,112,318. An overview of various process variants for 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).

[0079] The reaction of MEOA with ammonia is preferably carried out in a fixed bed reactor over a transition metal catalyst at 150-250 bar and 160-210° C. or over a zeolite catalyst at 1-20 bar and 280-380° C.

[0080] The transition metal catalyst preferably used comprises an oxidic support (e.g. Al 2 O 3 、TiO 2 、ZrO 2 、SiO 2 ) on Ni, Co, Cu, Ru, Re, Rh, Pd or Pt or a mixture of two or more of these metals.

[0081] Preferred zeolite catalysts are mordenite, faujasite and chabazite.

[0082] To achieve maximum EDA selectivity, a molar ratio of ammonia to MEOA of 6-20, preferably 8-15, is typically employed for transition metal catalysis and 20-80, preferably 30-50 for zeolite catalysis.

[0083] The MEOA conversion is generally maintained between 10% and 80%, preferably 40%-60%.

[0084] In continuous operation, preferably a catalyst space velocity in the range of 0.3 to 0.6 kg / (kg*h) (kg MEOA per kg catalyst per hour) is established.

[0085] In order to maintain the catalyst activity, when a metal catalyst is used, it is preferred to additionally add 0.05 wt % to 0.5 wt % (based on MEOA+NH 3 +H 2 Hydrogen (reaction input amount) is fed into the reactor.

[0086] C1 method:

[0087] The process for the preparation of EDA in step (ia) may also be a C1 process, in which formaldehyde, hydrogen cyanide, ammonia and hydrogen are converted into EDA.

[0088] For example, US-A 2 519 803 describes a process for preparing EDA by hydrogenation of a partially purified aqueous reaction mixture which is produced by the amination of formaldehyde cyanohydrin (FACH) and contains aminoacetonitrile as an intermediate. Formaldehyde cyanohydrin can in turn be obtained by reaction of formaldehyde with hydrogen cyanide. A description of the process for preparing FACH can be found, for example, in the application PCT / EP2008 / 052337, page 26, and in the application WO-A1-2008 / 104582, page 30 (variants A) and B), which are explicitly mentioned here.

[0089] DE-A 1 154 121 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.

[0090] WO-A1-2008 / 104592 relates to a process for preparing EDA by hydrogenation of aminoacetonitrile. Aminoacetonitrile is typically obtained by reaction of formaldehyde cyanohydrin with ammonia, wherein formaldehyde cyanohydrin is in turn usually prepared from hydrogen cyanide and ammonia.

[0091] Preferably, the reaction output comprising EDA and NMEDA is prepared by the process described in WO-A-2008 / 104592, which is expressly mentioned herewith.

[0092] EDC Method:

[0093] EDA can also be prepared by reaction of ethylene dichloride with ammonia (EDC process). The reaction of EDC with ammonia is described, for example, in EP 2346809, the above-mentioned PERP report and the references cited therein.

[0094] MEG Methods

[0095] In a particularly preferred embodiment, the feed to be provided in step (i) is obtained by converting MEG with ammonia in the presence of an amination catalyst and hydrogen. The reaction of MEG with ammonia can be carried out in liquid phase or gas phase. Gas phase reactions are disclosed in, for example, CN 102190588 and CN 102233272.

[0096] Preferably, the conversion of MEG with ammonia is carried out in the liquid phase according to US 4,111,840, US 3,137,730, DE 1 72 268, WO 2007 / 093514, WO2007 / 093552, WO2018 / 224316, WO2018 / 224315, WO2018 / 224321, WO2019 / 081283, WO2019 / 081285 and WO2020 / 17085.

[0097] In a particularly preferred embodiment (MEG process), the feed to be provided in step (i) is obtained by converting MEG with ammonia in the presence of an amination catalyst and hydrogen.

[0098] The MEG used in the process can be produced from ethylene available from petrochemical processes. For example, generally speaking, ethylene is oxidized to ethylene oxide in a first stage, which is then reacted with water to produce MEG.

[0099] Alternatively, ethylene oxide can be reacted with carbon dioxide in the so-called ω process to produce ethylene carbonate, which can then be hydrolyzed with water to produce MEG. The ω process is characterized by a higher selectivity to MEG, since less by-products, such as diethylene glycol and triethylene glycol, are formed.

[0100] The ethylene used in the production of MEG may alternatively be produced from renewable raw materials. For example, ethylene may be formed by dehydrating bioethanol.

[0101] MEG can also be produced via the synthesis gas route, for example by oxidative carbonylation of methanol to produce dimethyl oxalate and subsequent hydrogenation thereof.Another possible petrochemical feedstock for the production of MEG is therefore also natural gas or coal.

[0102] In addition, MEG obtained from recycling of PET by various methods such as glycolysis, methanolysis, hydrolysis, saponification, and pyrolysis may be used.

[0103] In the MEG process, MEG and optionally additional MEOA are reacted with ammonia.Although additional MEOA can be added as an additional educt, the MEG process is preferably carried out without additional MEOA.

[0104] The ammonia used may be conventional commercially available ammonia, for example ammonia having an ammonia content of greater than 98% by weight, preferably greater than 99% by weight, preferably greater than 99.5% by weight, in particular greater than 99.8% by weight.

[0105] The MEG process is preferably carried out in the presence of hydrogen.

[0106] The hydrogen is usually used in technical purity. The hydrogen can also be used in the form of a hydrogen-containing gas, i.e. with the addition of other inert gases, such as nitrogen, helium, neon, argon or carbon dioxide. The hydrogen-containing gas used may be, for example, reformer offgas, refinery gas, etc., if and as long as these gases do not contain any catalyst poisons for the catalyst used, for example sulfur components, such as H 2 S or CO. However, preference is given to using pure or substantially pure hydrogen in the process, for example hydrogen having a hydrogen content of greater than 99% by weight, preferably a hydrogen content of greater than 99.9% by weight, more preferably a hydrogen content of greater than 99.99% by weight, in particular a hydrogen content of greater than 99.999% by weight.

[0107] In the MEG process, MEG is preferably reacted with ammonia and an amination catalyst in the liquid phase.

[0108] Preferred amination catalysts for use in the MEG process are:

[0109] - the nickel-rhenium catalyst disclosed in US Pat. No. 4,111,840,

[0110] - the nickel-copper catalyst disclosed in US 3,137,730,

[0111] - the ruthenium-cobalt catalyst disclosed in WO 2007093514,

[0112] - a catalyst comprising cobalt, ruthenium and tin as disclosed in WO 2018224316,

[0113] - a catalyst comprising tin and another active metal as disclosed in WO 2018224315,

[0114] - the impregnated catalyst disclosed in WO 2018224321, or

[0115] - A catalyst comprising rhenium as disclosed in WO202017085.

[0116] The documents cited above disclosing suitable catalysts are incorporated by reference. The catalysts disclosed in the examples of the above documents are particularly preferred.

[0117] In the context of the present invention, "reacting in the liquid phase" means adjusting the reaction conditions (such as pressure and temperature) so that the ethylene glycol is present in the liquid phase and flows in liquid form around the amination catalyst.

[0118] The reaction of MEG and / or MEOA with ammonia can be carried out continuously or batchwise. Continuous reaction is preferred.

[0119] Suitable reactors for reactions in the liquid phase are generally tubular reactors. The catalyst can be arranged as a moving bed or as a fixed bed in the tubular reactor.

[0120] It is particularly preferred to combine MEG and / or MEOA with NH 3 The reaction takes place in a tubular reactor in which the amination catalyst is arranged in the form of a fixed bed.

[0121] If the catalyst is arranged in the form of a fixed bed, it may be advantageous for the selectivity of the reaction to "dilute" (so to speak) the catalysts in the reactor by mixing them with inert bulk fillers. The proportion of bulk fillers in such catalyst preparations may be 20 to 80 parts by volume, preferably 30 to 60 parts by volume and more preferably 40 to 50 parts by volume. Preferably, the catalyst is not diluted.

[0122] Alternatively, the reaction is advantageously carried out in a shell-and-tube reactor or in a single-flow device. In a single-flow device, the tubular reactor in which the reaction is carried out may consist of a plurality of (e.g. two or three) separate tubular reactors connected in series. Here, a possible and advantageous option is to introduce the feed (comprising the reactants and / or ammonia and / or H 2 ) and / or cycle gas and / or reactor output from a downstream reactor.

[0123] When working in the liquid phase, MEG and / or MEOA are added with ammonia (including hydrogen) while being introduced over the catalyst in the liquid phase, typically in a preferably externally heated fixed bed reactor at a pressure of typically 5 to 35 MPa (50-350 mbar), preferably 5 to 30 MPa, more preferably 15 to 28 MPa and a temperature of typically 80° C. to 350° C., in particular 100° C. to 300° C., preferably 120° C. to 270° C., more preferably 130° C. to 250° C. and especially 160° C. to 230° C.

[0124] 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 especially preferably 2 to 5 MPa (20 to 50 bar).

[0125] MEG and / or MEA and ammonia are preferably supplied to the reactor in liquid form and contacted with the amination catalyst in liquid form.

[0126] Both trickle mode or liquid phase mode are possible.

[0127] It is advantageous to heat the reactants (preferably to the reaction temperature) even before supplying them to the reaction vessel.

[0128] Ammonia is preferably used in a 0.9- to 100-fold molar amount, in particular in a 1- to 20-fold molar amount, based in each case on the MEG or MEA used.

[0129] The hourly space velocity 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) / kg catalyst · hour.

[0130] In particularly preferred embodiments, the conversion of MEG to ethyleneamines (particularly EDA) and ethanolamines is incomplete, so that unconverted MEG remains in the reactor effluent. MEG conversion is typically in the range of 5% to 80%, preferably 10% to 70%, more preferably 30% to 50%. Incomplete conversion of MEG has the advantage that unconverted MEG can act as a distillation aid that aids in the separation of EDA, NMEDA and water of the present invention, and as described below.

[0131] The conversion of MEG is generally carried out in such a way that the feed provided to step (ii) comprises the amount of MEG specified below. The degree of conversion can be adjusted by varying operating parameters such as reaction temperature, the amount of ammonia added and the catalyst hourly space velocity. Reducing the hourly space velocity generally increases the degree of conversion of MEG to MEOA and EDA.

[0132] Combined MEG-MEOA method:

[0133] In a preferred embodiment of the present invention, the feed provided in step (i) is obtained by:

[0134] (i) in a first reactor (MEG reactor), converting ethylene glycol (MEG) with ammonia in the presence of an amination catalyst and hydrogen to obtain a reaction effluent comprising water, ethylenediamine (EDA), monoethanolamine (MEOA), unconverted MEG and other components having a boiling point higher than EDA and optionally NMEDA, and

[0135] (ii) separating MEOA from the reaction effluent obtained in (i), and

[0136] (iii) in a second reactor (MEOA reactor), converting the MEOA separated in step (ii) with ammonia in the presence of an amination catalyst and hydrogen to obtain a reaction effluent comprising water, ethylenediamine (EDA), unconverted monoethanolamine (MEOA) and other components having a boiling point higher than EDA and optionally NMEDA.

[0137] When MEOA in the reactor effluent of the MEG conversion is separated and converted in a separate reactor with a tailored catalyst under adjusted process conditions, the overall yield and selectivity towards EDA are improved.The MEOA conversion step is preferably carried out under the conditions described above for the MEOA process.

[0138] The separation of one or more MEOA fractions may be performed according to the separation sequence described below.

[0139] In a more preferred embodiment, the MEG-MEOA process comprises the following additional steps:

[0140] (iv) separating MEG from the reaction effluent obtained in step (i); and

[0141] (v) recycling the MEG separated in step (iv) to step (i).

[0142] The separation of one or more MEG fractions may be performed according to the separation sequence described below.

[0143] The reaction effluent of the MEG reactor and the effluent of the MEOA reactor are preferably combined in order to separate their components in a common work-up stage.The use of a common separation train has the advantage of reducing equipment costs and energy requirements.

[0144] Using a MEG process to provide the feed in step (i) and 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 in a single MEOA or single MEG reactor.

[0145] Operating a MEG reactor and a subsequent MEOA reactor allows for efficient recycle of unconverted MEOA.

[0146] Step (ib): Removing ammonia and / or hydrogen from the output obtained in step (ia):

[0147] The reaction effluent from the above-described preparation process generally comprises ammonia and hydrogen.

[0148] Before the output from these processes is fed to the separation step (ii), ammonia and / or hydrogen is preferably removed.

[0149] The amount of ammonia in the reaction output is typically in the range of 30 to 90 wt%, more preferably in the range of 40 to 85 wt%, and most preferably in the range of 50 to 80 wt%.

[0150] The amount of hydrogen in the reaction effluent is preferably in the range of 0.01 to 20% by weight, more preferably 0.05 to 10% by weight and most preferably 0.1 to 5% by weight.

[0151] The hydrogen and ammonia can be separated from the reaction mixture by methods known to those skilled in the art.

[0152] In a particularly preferred embodiment, the removal of ammonia and / or hydrogen is carried out according to the method disclosed in WO 2019081285 in the section entitled "Ammoniakabtrennung-Stufe 2" (or "Ammonia Separation-Step 2" in English) or in WO 2019 / 081283 also in the section entitled "Ammoniakabtrennung-Stufe 2" (or "Ammonia Separation-Step 2" in English). The contents of these teachings are hereby incorporated by reference.

[0153] The composition of the feed provided in step (i)

[0154] The feed provided by step (i) comprises NMEDA, water and EDA.

[0155] Preferably, the feed comprises 0.001 to 1 wt %, more preferably 0.01 to 0.5 wt % and most preferably 0.02 to 0.1 wt % NMEDA.

[0156] 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%.

[0157] Preferably, the feed comprises 1 to 30 wt %, more preferably 2.5 to 25 wt % and most preferably 5 to 20 wt % water.

[0158] The feed provided by step (i) preferably comprises 0.1 wt% or less, more preferably 0.01 wt% or less and most preferably 0.001 wt% or less of ammonia.

[0159] The feed provided to step (ii) preferably comprises 0.1 wt% or less, more preferably 0.01 wt% or less and most preferably 0.001 wt% or less hydrogen.

[0160] The feed provided from step (i) preferably comprises other ethyleneamines and ethanolamines, especially ethyleneamines and ethanolamines having a boiling point higher than EDA, in particular PIP, MEOA, DETA, TETA, AEP, HEPIP, AEEA and HEDETA. More preferably, the feed provided in step (i) comprises MEOA, preferably in an amount of 1 to 30 wt%, more preferably 3 to 25 wt% and most preferably 5 to 20 wt%.

[0161] Preferably, the feed provided in step (i) comprises one or more ethyleneamines or ethanolamines having a boiling point higher than 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 wt%, more preferably 0.01 to 3 wt% and more preferably 0.03 to 2.5 wt%.

[0162] When the feed to be provided in step (i) is obtained by the above-mentioned MEG process, the feed (i) provided in step (i) preferably comprises 20 to 90 wt% MEG, more preferably 25 to 80 wt% and more preferably 30 to 70 wt% MEG.

[0163] When the feed provided in step (i) is obtained by a MEG process, the feed preferably also comprises 1 to 50 wt% MEOA, more preferably 3 to 30 wt% and more preferably 5 to 25 wt% MEOA. As stated above, the MEG content is preferably adjusted by the degree of conversion of MEG in the MEG process.

[0164] In a particularly preferred embodiment, the feed provided in step (i) comprises:

[0165] Water: 10 to 20% by weight;

[0166] NMEDA: 0.01 to 0.1 wt. %;

[0167]

[0168] Step (ic): Addition of additional auxiliary agents:

[0169] The term additional adjuvant as used in the context of the present invention refers to an adjuvant which is not ethyleneamine or ethanolamine. In particular, ethyleneamine and ethanolamine selected from the group consisting of PIP, DETA, AEEA, AEP and mixtures thereof as disclosed in US 4032411 (Berol Kemi Company) are disclaimed as additional adjuvants.

[0170] The additional adjuvants are preferably hydroxyl-containing compounds.

[0171] The additional adjuvant is more preferably a compound or a mixture of compounds selected from the group consisting of:

[0172] (i) aliphatic monoalcohols,

[0173] (ii) aliphatic diols;

[0174] (iii) aliphatic triols; and

[0175] (iv) Aliphatic tetraols.

[0176] Surprisingly, it has been found that the azeotropes between EDA and water and / or NMEDA and water are effectively modified by these additional auxiliary agents, so that the separation step (ii) can be carried out in a particularly efficient manner, in particular at ambient pressure or moderately below atmospheric pressure, which are easier to achieve than the high pressures disclosed in DE 1258413 (Dow) or WO2021 / 115907 (BASF) for otherwise breaking the azeotrope.

[0177] Preferred aliphatic monoalcohols are linear or branched alcohols having one hydroxyl group containing from 5 to 12 carbon atoms.

[0178] Particularly preferred aliphatic monoalcohols 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.

[0179] 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-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol and 1,6-hexanediol.

[0180] Further preferred diols are ethylene glycol, propylene glycol and butanediol composed of 2 to 4 ethylene glycol, propylene glycol or butanediol 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.

[0181] The most preferred aliphatic diols are 1,2-diols, particularly ethylene glycol, 1,2-propylene glycol, and 1,2-butanediol.It is believed that compounds having vicinal hydroxyl groups may interact particularly well with EDA to break or otherwise modify the azeotrope formed between EDA and water.

[0182] Preferred aliphatic triols contain 3 to 6 carbon atoms. Particularly preferred aliphatic triols are glycerol and trimethylolpropane.

[0183] Preferred aliphatic tetrols contain 4 to 6 carbon atoms. Particularly preferred aliphatic tetrols are pentaerythritol, erythritol or threitol.

[0184] More preferably, the additional adjuvant containing one or more hydroxyl groups is a compound that has a boiling point higher than that of EDA or NMEDA, but can still be separated from the ethyleneamines and ethanolamines using reasonable conditions. This has the advantage that such adjuvants are not evaporated before or during the separation of NMDEA or EDA, so that their azeotrope-modifying effect remains effective until the NMDEA is effectively separated.

[0185] Furthermore, it is preferred that the additional adjuvant is an aliphatic hydroxyl-containing compound in order to avoid discoloration.

[0186] Furthermore, it is preferred that the additional auxiliary agent is miscible with the output obtained by the EDA preparation process.

[0187] The most preferred additional adjuvants are 1,2 diols and triethylene glycol (TEG). Particularly preferred 1,2-diols are MEG, 1,2 propanediol and 1,2 butanediol.

[0188] MEG has the following advantages: It is also a raw material for producing EDA.

[0189] When MEG is used as additional adjuvant, the amount of additional adjuvant in the feed can be adjusted as stated above by controlling the conversion of MEG in its reaction with ammonia.

[0190] TEG has the advantage of being preferably used as a distillation auxiliary for the separation of DETA from MEOA. The use of TEG has the advantage that TEG can be used not only as an auxiliary for the DETA / MEOA separation, but can also find additional use in the separation of NMEDA from EDA and water. Thus, only one auxiliary is required for both separations.

[0191] In a preferred embodiment, the additional auxiliary agent is added after step (ia). Adding the auxiliary agent after step (ia) has the advantage that the hydroxyl groups of the auxiliary agent are not aminated in step (ia). This avoids the formation of additional aminated products, which may need to be separated from the reaction mixture because they are not ethyleneamines or ethanolamines inherently formed in the EDA preparation process.

[0192] In another preferred embodiment, additional auxiliary agent is added before or during step (ia). This embodiment is particularly preferred when the auxiliary agent can also be converted into ethanolamine or ethyleneamine inherent to the EDA preparation process.

[0193] The amount of additional auxiliary agent comprising one or more hydroxyl groups in the feed provided in step (i) is preferably adjusted in such a way that the molar ratio of all 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 (1 or more:1), more preferably 1.5:1 or more (1.5 or more:1), even more preferably 2:1 or more (2 or more:1) and most preferably 4:1 or more (4 or more:1).

[0194] If the adjuvant is an aliphatic diol, especially a 1,2-diol such as MEG, the molar ratio of diol to EDA is preferably 1:1 or greater (1 or greater:1), more preferably 1.2:1 or greater (1.2 or greater:1), even more preferably 1.5:1 or greater (1.5 or greater:1) and most preferably 2:1 or greater (2 or greater:1).

[0195] The higher the ratio of OH-groups to amine groups of the EDA, the higher the azeotrope modification effect.

[0196] The amount of additional adjuvant is preferably adjusted by determining the hydroxyl concentration or diol concentration and the EDA concentration in the feed and adding the additional adjuvant.

[0197] In case the additional auxiliary agent is not MEG, the amount of the additional auxiliary agent is preferably adjusted by adding the additional auxiliary agent before separation step (ii) and preferably after removal of ammonia and / or hydrogen so that the hydroxyl groups of the additional auxiliary agent are not aminated during EDA preparation step (ia).

[0198] When the additional adjuvant is MEG, the amount of additional adjuvant is preferably adjusted via the degree of conversion of MEG with ammonia in the MEG process, as described above.

[0199] Separation step (ii):

[0200] Surprisingly, it was found that when a feed stream comprising EDA, NMEDA and water is provided, the azeotrope formed between EDA and water and / or NMEDA and water is broken or otherwise modified so that water can be separated from NMEDA and EDA in one or more distillation columns, wherein water is separated from EDA and NMEDA as a low boiling fraction. Typically, the destruction of the azeotropic mixture formed between EDA and water and / or NMEDA and water requires distillation at a higher pressure that destroys the azeotropic mixture. The present invention has the following benefits: the separation of water from EDA and NMEDA can be performed at a lower distillation pressure. Compared with high pressure separation methods, low pressure methods are more advantageous in OPEX (operating expenditure) and CAPEX (capital expenditure).

[0201] In step (ii) the feed provided in step (i) is preferably separated into:

[0202] a. a fraction A comprising water and NMEDA, wherein the weight ratio of water to NMEDA in fraction A is greater than 100:1;

[0203] b. a fraction B comprising water, NMEDA and EDA, wherein the weight ratio of water to NMEDA is in the range of 1:100 to 100:1; and

[0204] c. Fraction C comprising water and EDA, wherein the weight ratio of EDA to water is greater than 5:1.

[0205] Preferably, 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, 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.

[0206] 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 less, preferably 160°C or less and most preferably 155°C or less.

[0207] NMEDA Removal Tower - One Tower Setup

[0208] In a preferred embodiment, the separation in step (ii) is carried out in a distillation column (NMEDA removal column) in which fraction A is taken off at the top, fraction B is taken off as a side draw and fraction C is taken off at the bottom of the distillation column.

[0209] The separation step (ii) according to the invention can be carried out in a rectification apparatus, such as a plate column, such as a bubble cap tray column, a sieve plate column, a dual-flow plate column, a valve column, a baffle column or a column with random packing or structured packing. Preference is given to using internals with a low pressure drop, such as structured packing, for example in the form of sheet metal packing, such as Mellapak 250Y or Montz Pak (type B1-250). Packings with a lower or increased specific surface area may also be present, or fabric packings or packings with another geometry, such as Mellapak 252.Y, may be used. The advantages of using such internals are, for example, a low pressure drop and a low specific liquid holdup compared to valve trays.

[0210] The internals may be arranged in one or more beds.

[0211] Preferably, the distillation column comprises structured packing, in particular Mellapak 250.

[0212] The design and layout of the NMEDA removal column is determined by the production capacity. Typically, the NMEDA removal column has a diameter of 0.5 to 2.5 m, preferably 0.8 to 2 m and most preferably 1 to 1.5 m and a bed height of 5 to 20 m, preferably 7 to 15 m and most preferably 8 to 12 m.

[0213] The number of theoretical plates in the NMEDA removal column is generally in the range of 10 to 40, preferably 15 to 35 and more preferably 20 to 30.

[0214] The energy required for 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, 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 can be used.

[0215] The feed comprising EDA, NMEDA and water provided in step (i) is preferably introduced in a spatial 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 and 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 plates 10 and 15.

[0216] The NMEDA removal column generally has a condenser which is generally operated at a temperature such that a significant portion of fraction A condenses at the corresponding column top pressure.

[0217] Generally, the operating temperature of the condenser is in the range of 10°C to 150°C, preferably 50°C to 140°C and more preferably 80°C to 120°C.

[0218] Suitable condensers are condensers with cooling coils or tube spirals, jacketed tube condensers and shell and tube heat exchangers.

[0219] As previously stated, 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 bottom pressure in the NMEDA removal column is

[0220] The pressure is preferably 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.

[0221] The NMEDA removal column may be operated at a column bottom temperature of 80°C to 220°C, more preferably 100°C to 200°C, and more preferably 130°C to 190°C.

[0222] 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 values, the EDA loss in fractions A and B can be further reduced.

[0223] The energy required to vaporize 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, 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 may be used.

[0224] Fraction A comprising water and NMEDA, wherein 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 or more and most preferably greater than 2000:1.

[0225] Preferably, fraction A comprises 0.1 wt% or less NMEDA, more preferably 0.01 wt% or less and most preferably 0.001 wt% or less NMEDA.

[0226] Preferably, fraction A contains 0.01 wt% or less EDA, more preferably 0.001 wt% or less and most preferably 0.0001 wt% or less EDA.

[0227] Preferably, fraction A contains 0.01% or less, more preferably 0.001 or less and most preferably 0.0001 or less of components having a boiling point higher than EDA.

[0228] Fraction A may contain some components (except water) having a boiling point lower than that of EDA, such as methane or ammonia, each in an amount of 0.1 wt% or less, more preferably 0.08 wt% or less and most preferably 0.05 wt% or less.

[0229] Removal of fraction A having a low organic content allows efficient disposal of fraction A in conventional water purification plants, or direct recirculation to this or other processes requiring water.

[0230] Fraction B comprising water, NMEDA and EDA, wherein the weight ratio of water to NMEDA is in the range of 1:100 to 100:1, preferably 1:50 to 50:1 and more preferably 1:10 to 10:1 and most preferably 1:3 to 3:1, is preferably discharged from the NMEDA removal column as a side stream. The amount of fraction B discharged as a side draw is relatively small to avoid EDA losses, but large enough to remove substantially all of the amount of 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 withdrawn 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.

[0231] Fraction B is preferably withdrawn in the region between the middle and the top of the column, preferably in the region between 50% and 90% of theoretical plates, more preferably from 55% to 80% of theoretical plates and most preferably from 60% to 70% of theoretical plates. Preferably, fraction B is withdrawn above the feed to the NMEDA removal column.

[0232] Fraction B typically also contains some EDA, with the weight ratio of NMEDA to EDA preferably ranging 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.

[0233] Preferably, fraction B comprises 10 to 75 wt.-% NMEDA, more preferably 20 to 70 wt.-% and even more preferably 30 to 60 wt.-% NMEDA.

[0234] The removal of fraction B as a side stream 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 to incineration, thereby allowing efficient disposal of the unwanted by-product NMEDA while sacrificing only negligible amounts of the valuable product EDA.

[0235] In a preferred embodiment, fraction C, preferably taken from the bottom of the NMEDA removal column, has a low water content, which generally meets 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.

[0236] Fraction C preferably contains 0.1 wt% or less NMEDA, preferably 0.05 wt% or less and more preferably 0.01 wt% or less NMEDA.

[0237] Fraction C preferably comprises 1 to 30% by weight, preferably 5 to 25% by weight and more preferably 7.5 to 15% by weight of EDA.

[0238] In this embodiment, fraction C preferably comprises components having a boiling point higher than that of EDA, in particular:

[0239] 1 to 50 wt%, preferably 5 to 30 wt% and more preferably 10 to 20 wt% MEOA;

[0240] 40 to 95 wt%, preferably 50 to 90 wt% and more preferably 60 to 80 wt% MEG.

[0241] In this preferred embodiment, fraction C preferably further comprises one or more ethyleneamines or ethanolamines selected from the group consisting of PIP, DETA, AEEA, DEOA, HEPIP, HEDETA and TETA, each in an amount preferably of 0.01 to 2 wt.-%, more preferably 0.02 to 1 wt.-% and most preferably 0.03 to 0.7 wt.-%.

[0242] In a preferred embodiment, when MEG is used as the only additional auxiliary agent, the preferred composition of fraction C taken off at the bottom of the NMEDA removal column comprises:

[0243] MEG: 60 to 80% by weight

[0244] MEOA: 10 to 20% by weight

[0245] EDA: 5 to 15% by weight

[0246] PIP: 0.5 to 2% by weight

[0247] DETA: 0.1 to 2% by weight

[0248] AEEA: 0.01 to 1% by weight

[0249] DEOA: 0.01 to 0.5 wt %,

[0250] TETA: 0.1 to 2% by weight

[0251] Water: 0.001 to 0.5% by weight

[0252] Others: 0.001 to 5% by weight.

[0253] NMEDA Removal Tower - Two Tower Setup

[0254] Instead of using a single NMEDA removal column, separation step (ii) can be carried out in two NMEDA removal columns. In the first column, fraction A is separated, preferably at the top of the first NMEDA removal column, and fractions B and C are taken off jointly at the bottom of the first NMEDA removal column. Thus, the common fractions B and C are further separated in a second NMEDA removal column, in which fraction B is preferably taken off at the top and fraction C is taken off at the bottom.

[0255] Additional dehydration tower

[0256] In particularly preferred embodiments, fraction C taken off from the bottom of the first or second NMEDA removal column preferably has a higher water content.

[0257] The higher water content is preferably reduced in a subsequent separation step, most preferably in a further distillation column (residual water removal column).

[0258] In this example, the subsequent separation step not only allows a further reduction in the water content, but also enables a further reduction in the NMEDA content, thereby allowing EDA to be obtained with a still lower NMDEA content. This ultra-low NMDEA content allows for subsequent simplification of the further processing of the ethyleneamine mixture by being able to separate EDA, PIP from higher boiling components (particularly MEOA and MEG) in a single dividing wall column, as further set out below.

[0259] In this particularly preferred embodiment, the water content in fraction C is in the range from 0.1 to 10% by weight and preferably from 0.5 to 5% by weight.

[0260] In this particularly preferred embodiment, fraction C preferably comprises components having a boiling point higher than EDA, in particular:

[0261] 10 to 70 wt. %, preferably 20 to 60 wt. % and more preferably 35 to 55 wt. % EDA;

[0262] 1 to 50 wt%, preferably 5 to 30 wt% and more preferably 10 to 20 wt% MEOA;

[0263] 5 to 60 wt%, preferably 10 to 50 wt% and more preferably 20 to 40 wt% MEG.

[0264] In this particularly preferred embodiment, fraction C preferably further comprises one or more ethyleneamines or ethanolamines selected from the group consisting of PIP, DETA, AEEA, HEDETA, HEPIP, DEOA and TETA, each in an amount preferably of 0.01 to 2 wt.-%, more preferably of 0.02 to 1.5 wt.-% and most preferably of 0.05 to 1 wt.-%.

[0265] In a preferred embodiment of this particularly preferred embodiment, MEG is used as the only additional auxiliary agent.

[0266] In this case, the preferred composition of fraction C taken off at the bottom of the NMEDA removal column is:

[0267] MEG: 20 to 40% by weight

[0268] MEOA: 10 to 25% by weight

[0269] EDA: 30 to 60% by weight

[0270] PIP: 0.5 to 5% by weight

[0271] DETA: 0.1 to 3% by weight

[0272] AEEA: 0.01 to 0.5 wt %,

[0273] DEOA: 0.01 to 0.5 wt %,

[0274] TETA: 0.1 to 2% by weight

[0275] Water: 0.5 to 5% by weight

[0276] Others: 0.001 to 5% by weight.

[0277] When the water content of fraction C is within the range stated in the particularly preferred embodiments with a higher water content (as indicated above), fraction C is additionally separated into:

[0278] a fraction C-1 comprising EDA, NMEDA and water, wherein the weight ratio of EDA to water is in the range of 1:5 to 5:1, preferably 1:3 to 3:1 and 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; and

[0279] - Fraction C-2 comprising EDA and preferably components having a boiling point higher than EDA, and wherein the NMEDA content is preferably 0.01 wt% or less, more preferably 0.001 wt% and most preferably 0.0001 wt% or less.

[0280] As previously described, when fraction C is further separated into fractions C-1 and C-2, EDA having an ultra-low NMEDA content can be obtained.

[0281] In a preferred embodiment, fraction C-1 is preferably recycled directly as vapor 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, thereby reducing the energy requirement at the reboiler of the first column.

[0282] 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).

[0283] The residual water removal column is typically a plate column, a bubble cap tray column, a sieve plate column, a dual-flow plate column, a valve column, a baffle column or a column with random packing or structured packing. Preference is given to using internals with a low pressure drop, such as structured packing, for example in the form of sheet metal packing, such as Mellapak 250Y or Montz Pak (type B1-250). Packings with a lower or increased specific surface area may also be present, or fabric packings or packings with another geometry, such as Mellapak 252.Y, may be used. The advantages of using such internals are, for example, a low pressure drop and a low specific liquid holdup compared to a valve tray.

[0284] The internals may be arranged in one or more beds.

[0285] Preferably, the residual water removal column comprises structured packing, in particular Mellapak 250.

[0286] The number of theoretical plates in the residual water removal column is generally in the range of 15 to 70, preferably 20 to 50 and more preferably 30 to 40.

[0287] The energy required for separation of the feed provided in step (i) in the residual 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, 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 can be used.

[0288] Fraction C from the NMEDA removal column is preferably introduced at the top of the residual water removal column, so that preferably the residual water removal column is designed with only a stripping section.

[0289] In a preferred embodiment, the residual water removal column does not have a condenser, and the uncondensed vapor taken off the top of the column is preferably recycled to the sump of the NMEDA removal column (preferably through a valve).

[0290] 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.

[0291] The residual water removal column is preferably operated at a column bottom temperature of 140°C to 230°C, more preferably 150°C to 210°C, and more preferably 170°C to 190°C.

[0292] 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, 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 can be used.

[0293] In a preferred embodiment, in which MEG is used as the only auxiliary agent, the composition of the fraction C-2 taken off at the bottom of the residual water removal column comprises:

[0294] MEG: 20 to 60, preferably 30 to 50% by weight

[0295] MEOA: 10 to 40, preferably 15 to 25% by weight

[0296] EDA: 10 to 50, preferably 20 to 40% by weight

[0297] PIP: 0.1 to 10, preferably 0.5 to 5% by weight

[0298] DETA: 0.1 to 10, preferably 0.5 to 5% by weight

[0299] AEEA: 0.1 to 10, preferably 0.5 to 5% by weight

[0300] DEOA: 0.05 to 2, preferably 0.1 to 1% by weight

[0301] TETA: 0.01 to 2, preferably 0.05 to 0.5% by weight

[0302] Water: 0.001 to 0.5, preferably 0.01 to 0.1% by weight

[0303] NMEDA: 0.005, preferably 0.0005 wt% or less.

[0304] Downstream separation and recirculation:

[0305] Fraction C or C-2 can be further separated in a series of downstream separation steps.

[0306] The downstream separation step is preferably carried out in a conventional column or a dividing wall column.

[0307] In a particularly preferred separation sequence, fraction C-2 from the bottom of the residual water removal column is separated into:

[0308] - fraction D-1, which contains EDA; and

[0309] - fraction D-2, which contains PIP; and

[0310] - Fraction D-3, which comprises components having a higher boiling point than PIP, in particular MEOA, MEG, DETA, AEE, DEOA and TETA.

[0311] 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 teaching of WO 2005 / 037769, which discloses a dividing wall column in which EDA and PIP can be separated from other high-boiling ethanolamines and ethyleneamines. The teaching content of WO 2005 / 037769 is hereby incorporated by reference.

[0312] Fraction D-1 preferably comprises a water content of 0.1 wt% or less, preferably 0.08 wt% or less and more preferably 0.05 wt% or less.

[0313] Fraction D-1 preferably contains a PIP content of 0.05 wt.% or less, preferably 0.01 wt.% or less and more preferably 0.005 wt.% or less.

[0314] Fraction D-1 preferably comprises an NMEDA content of 0.05 wt.-% or less, preferably 0.001 wt.-% or less and more preferably 0.0005 wt.-% or less.

[0315] Fraction D-2 preferably comprises an EDA content of 0.3 wt.-% or less, preferably 0.2 wt.-% or less and more preferably 0.1 wt.-% or less.

[0316] Fraction D-2 preferably comprises a water content of 0.05 wt% or less, preferably 0.01 wt% or less and more preferably 0.005 wt% or less.

[0317] Fraction D-2 preferably comprises an NMEDA content of 0.01 wt.-% or less, preferably 0.001 wt.-% or less and more preferably 0.0001 wt.-% or less.

[0318] Fraction D-2 preferably comprises an EDA content of 0.1 wt.-% or less, more preferably 0.05 wt.-% or less and most preferably 0.01 wt.-% or less.

[0319] This particularly preferred separation sequence, in which fraction C-2 is separated in a single dividing wall column, enables the production of EDA and PIP that meet sales specifications with an ultra-low NMEDA content, which reduces investment and operating costs compared to the conventional arrangement of an EDA / PIP separation column followed by separation of EDA and PIP in a further column.

[0320] Fraction D-3 is preferably separated in one or more further separation steps into valuable fractions or fractions which can be easily recycled to the EDA preparation process. More preferably, fraction D-3 is separated into valuable fractions or fractions which can be provided to an additional MEOA process or MEOA reactor as described above.

[0321] Fraction D-3 is preferably further separated into:

[0322] a fraction E-1 comprising MEOA having a MEG content of preferably 2000 ppm or less, preferably 1500 ppm or less and more preferably 1000 ppm or less; and

[0323] - Fraction E-2, which comprises components having a boiling point higher than MEOA, in particular MEG, DETA, AEE, DEOA and TETA.

[0324] This separation step is preferably carried out in a conventional column.

[0325] Preferably fraction E-1 is fed to a MEOA reactor where MEOA is converted to ethyleneamines and ethanolamines with ammonia in the presence of an amination catalyst and hydrogen, as disclosed in the previous section. The effluent of the MEOA conversion reactor can be combined with the effluent of the MEG conversion reactor and separated using the same separation sequence and facilities as disclosed above.

[0326] Fraction E-2 is preferably separated into:

[0327] - a fraction F-1 comprising MEG and preferably 1000 ppm or less, more preferably 800 ppm or less and most preferably 600 ppm or less of MEOA; and

[0328] - Fraction F-2, which comprises components having a higher boiling point than MEG, in particular DETA, AEE, DEOA and TETA.

[0329] This separation step is preferably carried out in a conventional column.

[0330] Fraction F-1 is preferably recycled to the MEG reactor, in which MEG is converted into MEOA and ethyleneamines and ethanolamines with ammonia in the presence of hydrogen and an amination catalyst.

[0331] Preferably fraction F-2 is separated into:

[0332] - Fraction G-1, which contains DETA, MEG and AEPIP; and

[0333] - Fraction G-2, which contains AEEA and HEPIP.

[0334] Fraction G-1 can be further separated into:

[0335] - fraction H-1, which comprises MEG;

[0336] - Fraction H-2, which contains DETA and AEPIP.

[0337] This separation step is preferably carried out in a conventional column.

[0338] Fraction H-2 is preferably further separated into:

[0339] - fraction I-1, which contains DETA; and

[0340] - Fraction 1-2, which contains DETA and AEPIP.

[0341] Fraction I-1 can be used as a valuable fraction of DETA meeting marketing specifications.

[0342] Fraction I-2 is preferably recycled into the column in which the separation of fraction G-1 was carried out.

[0343] Fraction G-2 can be further separated into:

[0344] - Fraction J-1, which contains AEEA and HEPIP;

[0345] - Fraction J-2, which contains AEEA, DEOA, TETA and HEDETA.

[0346] This separation step is preferably carried out in a conventional column.

[0347] Fraction J-1 is preferably recycled to the MEOA reactor.

[0348] Fraction J-2 can be further separated into:

[0349] - fraction K-1, which contains AEEA; and

[0350] - Fraction K-2, which comprises DEOA, TETA and HEDETA.

[0351] Fraction K-1 can be used as a valuable AEEA fraction meeting the usual sales specifications for AEEA.

[0352] Fraction K-2 can be used as a mixed fraction for certain applications, or it can be further separated into fractions consisting essentially of DEOA, TETA and HEDETA.

[0353] When one or more of the above separation steps are used, the ethanolamines and ethyleneamines obtained in the EDA production process can be separated into fractions containing single valuable products (such as AEEA, DETA, EDA and PIP); or into fractions containing a mixture of ethanolamines, which fractions can be easily recycled to the additional MEOA process, especially to the reactor (MEOA reactor) in which MEOA and other alkanolamines are converted into ethyleneamines. The above process sequence focuses on obtaining a limited number of valuable products (such as AEEA, DETA, EDA and PIP), and a fraction that can be recycled to the EDA production process. In this way, a limited number of separation steps are required to prevent losses through undesirable by-products or components.

[0354] In another preferred embodiment, fraction C is further separated into:

[0355] - fraction D-1, which contains EDA;

[0356] - fraction D-2, which contains EDA, PIP and MEOA; and

[0357] - Fraction D-3, which comprises MEG and components having a higher boiling point than MEG, in particular DETA, AEE, DEOA and TETA.

[0358] This separation step is preferably carried out in a conventional column, in which fraction D-1 is taken off as top product, fraction D-2 as side draw and fraction D-3 as bottom product.

[0359] Fraction D-1 substantially comprises EDA and a water content of preferably 0.2 wt% or less, more preferably 0.15 wt% or less and most preferably 0.1 wt% or less.

[0360] 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.

[0361] Fraction D-2 preferably contains 80 wt% or more MEOA, more preferably 85 or more and most preferably 90 wt% or more MEOA, and about 1 to 5 wt% each of EDA and PIP.

[0362] Fraction D-2 is preferably further separated into:

[0363] - fraction E-1, which contains EDA and PIP; and

[0364] - Fraction E-2, which comprises MEOA.

[0365] This separation step is preferably carried out in a conventional column.

[0366] Preferably, fraction E-1 is further separated into fraction F-1 comprising EDA and fraction F-2 comprising PIP.

[0367] Fraction E-2 is preferably recycled to the MEOA process step which is integrated into the process.

[0368] Fraction D-3 is preferably separated into:

[0369] - fraction G-1, which comprises MEG; and

[0370] - Fraction G-2, which comprises DETA and components having a boiling point higher than DETA.

[0371] Fraction G-1 is preferably recycled to the MEG process step or used as scrubbing liquid to scrub MEG in the ammonia / hydrogen removal step (ib) as described above and then recycled to the MEG process step.

[0372] Fraction G-2 is preferably separated into:

[0373] - fraction H-1, which comprises MEG and DETA; and

[0374] - Fraction H-2, which contains AEEA, DEOA and TETA.

[0375] This separation step is preferably carried out in a conventional column.

[0376] Fraction H-1 is preferably recycled into the MEG process.

[0377] The fraction H-2 comprising the highest-boiling components is preferably removed from the process and sent to the combustion plant or separated into its individual components in a further separation step.

[0378] The separation sequence according to the invention allows the production of EDA with an NMEDA content within specifications.

[0379] The separation step of the present invention allows for efficient removal of NMEDA and water, thereby requiring low operating and capital expenditures, since the removal of NMEDA and water can be performed at ambient or slightly subatmospheric pressure conditions, which are easier to implement than high pressure separation processes known in the prior art.

[0380] The separation according to the invention allows subsequent downstream separation sequences by which valuable fractions within specifications can be obtained.

[0381] The separation according to the invention also allows the separation of MEOA and MEG which can be recycled to the EDA preparation process or reactor, ie the MEG process or MEOA process step.

[0382] The separation step of the present invention further allows an overall MEG process to be designed therearound which achieves high selectivity and yield of desired valuable products such as EDA, DETA, AEEA and PIP while minimizing losses through undesirable by-products.

[0383] In a preferred embodiment, separation of water and NMEDA to within specification levels can be performed in a single column, which is particularly economical in terms of reducing capital expenditures.

[0384] In a further preferred embodiment, the water content in fraction C is adjusted to a higher level, which allows the removal of residual water and NMEDA in a further separation step. When an NMEDA removal column is combined with a residual water removal column, ultra-low water and / or NMEDA content in EDA can be obtained. The combination of an NMEDA removal column with a residual water removal column also allows the subsequent separation of the valuable products EDA and PIP in a single dividing wall column, compared to the conventional double-column arrangement for separating EDA and PIP. The use of a dividing wall column has an additional positive impact on capital and operating expenditures.

[0385] The benefits of the present invention are demonstrated by the following examples:

[0386] Examples:

[0387] The examples are based on calculations performed using a process simulation model.

[0388] Already used Simulations were performed. In order to calculate the thermodynamic properties of the pure components (like vapor pressure), the DIPPR correlation has been used. For the description of the phase equilibrium, the ideal gas law is used to describe the vapor phase, and the NRTL excess Gibbs energy model is used to describe the liquid phase. The parameters of the DIPPR correlation and the parameters of the NRTL model are adjusted for the experimental data. For components for which no experimental data are available, the UNIFAC group contribution method is used to describe the liquid phase in the liquid phase equilibrium calculation. The distillation column has been modeled and calculated using the equilibrium plate model. The simulation and thermodynamic property models adopted have been adjusted to reproduce the experimental and device data with very good accuracy.

[0389] Example 1:

[0390] The feed was prepared in a combined MEG / MEOA process.

[0391] After removal of hydrogen and ammonia, the feed comprises:

[0392] Water: 15.80% by weight

[0393] NMEDA: 0.04 wt%

[0394] EDA: 18.81 wt%

[0395] PIP: 1.81 wt%

[0396] MEOA: 16.67 wt%

[0397] MEG: 42.07 wt%

[0398] DETA: 1.96 wt%

[0399] AEPIP: 0.21 wt%

[0400] AEEA: 1.65 wt%

[0401] 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.

[0402] 1725.72 kg / h of the feed stream was fed to the NMEDA removal column, where it was separated into fraction A, fraction B and fraction C.

[0403] The NMEDA-removal column was equipped with a reboiler and had 28 trays.

[0404] The feed was introduced above the 12th tray (counted from the bottom).

[0405] The bottom temperature was 159°C.

[0406] 644.26 kg / g of fraction A containing water and 100 wtppm of NMEDA (weight ratio of water to NMEDA: about 10000:1) was taken out from the top of the column and fed to a condenser operated at 100°C.

[0407] 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 withdrawn.

[0408] Between the 17th and 18th trays, 1.58 kg / h of fraction B was taken off as a side draw, which fraction contained:

[0409] 40.1% by weight of water;

[0410] 41.8 wt% NMEDA; and

[0411] 18.1 wt% EDA.

[0412] Therefore, the weight ratio of water to NMEDA was approximately 0.96:1.

[0413] 1847.93 kg / h of fraction C are taken from the bottom of the NMEDA removal column, which fraction contains:

[0414] Water: 1.05% by weight

[0415] NMEDA: 0.01 wt%

[0416] EDA: 32.40 wt%

[0417] PIP: 2.30 wt%

[0418] MEOA: 18.55 wt%

[0419] MEG: 41.11 wt%

[0420] DETA: 1.88 wt%

[0421] AEPIP: 0.20 wt%

[0422] AEEA: 1.57 wt%

[0423] And it is fed to another residual water removal column. The weight ratio of EDA to water in fraction C is about 30.9 to 1.

[0424] In a residual water removal column equipped with a reboiler and having 36 trays, fraction C was further separated into fraction C-1 and fraction C-2.

[0425] Fraction C was introduced above the 36th plate.

[0426] The residual water removal column was operated at a column bottom temperature of 181° C. and a column top pressure of 1.3 bar.

[0427] 395.93 kg / h of fraction C-1 is taken out from the top of the residual water removal tower, and the fraction contains:

[0428] Water: 4.86% by weight

[0429] NMEDA: 0.028 wt%

[0430] EDA: 69.36 wt%

[0431] PIP: 2.88 wt%

[0432] MEOA: 13.91 wt%

[0433] MEG: 8.55 wt%

[0434] DETA: 0.24 wt%

[0435] AEPIP: 0.03 wt%

[0436] AEEA: 0.12 wt%

[0437] This stream is fed directly as a vapor to the bottom of the NMEDA removal column without condensation.

[0438] 1452.00 kg / h of fraction C-2 is taken out from the bottom of the residual water removal column, and the fraction contains:

[0439] Water: 0.01% by weight

[0440] NMEDA: 0.00009 wt%

[0441] EDA: 22.32 wt%

[0442] PIP: 2.15 wt%

[0443] MEOA: 19.80 wt%

[0444] MEG: 49.99 wt%

[0445] DETA: 2.33 wt%

[0446] AEPIP: 0.25 wt%

[0447] AEEA: 1.97 wt%

[0448] This was purified in a dividing wall column to obtain a pure EDA fraction comprising 500 wt ppm of water and 2 wt ppm of NMEDA.

[0449] Example 2: Providing a feed comprising EDA, NMEDA and water

[0450] The feed was prepared in a combined MEG / MEOA process.

[0451] After removal of hydrogen and ammonia, the feed comprises:

[0452] Water: 9.03% by weight

[0453] NMEDA: 0.07 wt%

[0454] EDA: 7.07 wt%

[0455] PIP: 0.72 wt%

[0456] MEOA: 12.96 wt%

[0457] MEG: 68.82 wt%

[0458] DETA: 0.72 wt%

[0459] AEEA: 0.07 wt%

[0460] TETA: 0.51 wt%

[0461] 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.

[0462] 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.

[0463] The NMEDA-removal column was equipped with a reboiler and had 25 trays.

[0464] The feed was introduced above the 12th tray (counted from the bottom).

[0465] The bottom temperature was 180°C.

[0466] 354.15 kg / g of fraction A containing water and 100 wtppm of NMEDA (weight ratio of water to NMEDA: about 10000:1) was taken out from the top of the column and fed to a condenser operated at 100°C.

[0467] A condensed stream of 134.79 kg / h was refluxed to the top of the NMEDA removal column, and a stream of 219.36 kg / h was withdrawn.

[0468] From the top of the column, fraction A comprising water and 100 ppm by weight of NMEDA was taken. The weight ratio of water to NMEDA was therefore approximately 10,000:1.

[0469] Between the 16th and 17th trays, 4.35 kg / h of fraction B were taken as a side draw, which fraction contained:

[0470] 5.43 wt% water;

[0471] 36.9 wt% NMEDA; and

[0472] 7.62 wt% EDA.

[0473] Therefore, the weight ratio of water to NMEDA was approximately 6.17:1.

[0474] From the bottom of the NMEDA removal column, 2235.92 kg / h of fraction C are taken, which comprises:

[0475] Water: 1.05% by weight

[0476] NMEDA: 0.002 wt%

[0477] EDA: 7.76 wt%

[0478] PIP: 0.79 wt%

[0479] MEOA: 14.26 wt%

[0480] MEG: 75.71 wt%

[0481] DETA: 0.79 wt%

[0482] AEEA: 0.04 wt%

[0483] TETA: 0.56 wt%

[0484] The weight ratio of EDA to water in Fraction C was approximately 236.5 to 1.

[0485] Fraction C was purified in a distillation column with 60 plates. Fraction C was fed into the column between the 36th and 37th plates (counted from the bottom). A top fraction was obtained containing 99.80% by weight of EDA, 0.12% by weight of water, 0.03% by weight of NMEDA and 0.05% by weight of PIP.

[0486] Example 1 shows that by separating the feed stream from the EDA production process from the NMEDA removal column into fractions according to the invention, technical-grade EDA can be obtained in only one additional distillation step. The loss of EDA is relatively small and is in the same order of magnitude as the NMEDA present in the feed.

[0487] In Example 2, the water concentration in the bottom of the NMEDA removal column is relatively high. This allows obtaining EDA with ultra-low NMEDA content.

Claims

1. A process for producing ethyleneamines from a mixture comprising water (HO), ethylenediamine (EDA) and N-methylethylenediamine (NMEDA), the process comprising the steps of: (i) providing a feed stream comprising EDA, NMEDA, water and additional adjuvants, (ii) separating water from NMEDA and EDA contained in the feed stream in one or more distillation columns, wherein water is separated from EDA and NMEDA as a low boiling fraction.

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

3. The method according to at least one of claims 1 to 2, wherein: The additional adjuvant is a hydroxyl-containing compound.

4. The method according to at least one of claims 1 to 3, wherein: The additional adjuvant is selected from the group consisting of: (v) aliphatic monoalcohols, (vi) aliphatic diols; (vii) aliphatic triols; and (viii) Aliphatic tetraols.

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-butylene glycol, 1,2-butylene glycol, 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 at least one of claims 1 to 5, wherein: The additional auxiliary agent provided in step (i) is ethylene glycol (MEG), 1,2-propylene glycol, 1,2-butylene glycol and / or triethylene glycol (TEG).

7. The method according to at least one of claims 1 to 7, wherein: The amount of additional auxiliary agent provided in step (i) is adjusted so that the molar ratio of hydroxyl groups in the feed to EDA molecules in the feed is 1:1 or more.

8. The method according to at least one of claims 1 to 7, wherein: Providing the feed in step (i) comprises the following steps: (ia) performing an EDA preparation process to obtain an output comprising EDA, NMEDA and water; (ib) removing ammonia and / or hydrogen from the output produced in step (ia); and (ic) adding the additional auxiliary agent to the EDA preparation process before, during or after step (ia) or after the removal of ammonia and / or hydrogen in step (ib).

9. The method according to at least one of claims 1 to 8, wherein: The EDA preparation process in step (ia) is a process in which ethylene glycol (MEG) is converted with ammonia in the presence of an amination catalyst and hydrogen, and wherein the additional adjuvant is MEG, and The additional auxiliary agent is added as an educt in step (ia).

10. The method according to claim 9, wherein: The conversion of MEG in step (ia) is carried out in such a way that the feed provided in step (i) comprises 30 to 70% by weight of MEG.

11. The method according to at least one of claims 1 to 10, wherein: The feed provided in step (i) additionally comprises components having a boiling point higher 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 wherein the amount of MEOA contained in the feed is 3 to 25 wt%.

13. The method according to at least one of claims 1 to 12, wherein: The separation in step (ii) is carried out in one or more distillation columns to separate: a. a fraction A comprising water and NMEDA, wherein the weight ratio of water to NMEDA in fraction A is greater than 1000:1; b. a fraction B comprising water, NMEDA and EDA, wherein the weight ratio of water to NMEDA is in the range of 1:1000 to 1000:1; and c. Fraction C comprising water and EDA, wherein the weight ratio of EDA to water is higher than 100:

1.

14. The method according to claim 13, wherein: Fraction A is taken off at the top, fraction B as a side draw and fraction C at the bottom of the distillation column.

15. The method according to at least one of claims 13 to 14, wherein: The water content in fraction C is in the range from 0.5 to 5% by weight.

16. The method according to claim 15, wherein: Fraction C was separated into: a fraction C-1 comprising 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; and - A fraction C-2 comprising EDA and preferably a component having a boiling point higher than EDA, and wherein the NMEDA content is 0.01% by weight or less.

17. The method according to claim 16, wherein: This fraction C-2 is further separated into: - fraction D-1, which contains EDA; - fraction D-2, which contains PIP; and - Fraction D-3, which comprises components having a boiling point higher than PIP.

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

19. The method according to at least one of claims 1 to 18, wherein: This separation step (ii) is carried out under conditions in which the azeotrope between EDA and water is broken or otherwise modified so that water can be separated from NMEDA and EDA as a low boiling fraction.

20. The method according to at least one of claims 1 to 19, wherein: The separation (ii) is carried out at a pressure of 3 bar or less.

21. Use of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,2-butylene glycol, 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 aid for the distillation of a mixture comprising water, ethylenediamine and N-methylethylenediamine.

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