Process for the preparation of ethanolamines

Abstract

A process for the preparation of ethanolamines comprises the steps of (1) providing an amine-water solution, (2) preheating the amine-water solution in a preheater to form a reactor inlet composition, (3) feeding the reactor inlet composition to the inlet of a plug flow reactor having an inlet and an outlet downstream of the inlet, (4) injecting ethylene oxide into the plug flow reactor at the inlet and / or one or more positions intermediate of the inlet and the outlet thereof to form a reaction mixture, (5) reacting the reaction mixture in the plug flow reactor to form an effluent mixture comprising ethanolamines, and (6) collecting the effluent mixture at the outlet of the plug flow reactor. The process can be readily adapted to changing amine to ethylene oxide ratios, operates efficiently at high amine to ethylene oxide ratios and produces a quality, on-spec product.

Description

[0001] Process for the preparation of ethanolamines

[0002] The present invention relates to a process for the preparation of ethanolamines by reacting an amine-water solution with ethylene oxide.

[0003] Alkanolamines and alkylalkanolamines are a versatile, chemically multifunctional group of chemicals used across a range of applications, including CO2 capture; polyurethane catalysts; paints and coatings; fabric softeners; water treatment and paper manufacturing. Their large-scale production commonly involves alkoxylation of nitrogenous compounds such ammonia or amines with alkylene oxides such as ethylene oxide and propylene oxide.

[0004] Alkoxylation reactions of nitrogenous compounds such as ammonia or amines with alkylene oxides are processes well known in the art and, for example, described in EP 2 651 861 B1.

[0005] M. Frauenkron et al., "Ethanolamines and Propanolamines'', in: Ullmann's Encyclopedia of Industrial Chemistry, DOI: 10.1002 / 14356007. a10_001 describes a batchwise production of alkanolamines. For this purpose, a reaction kettle is filled with amine and water (as a catalyst), heated to the reaction temperature, followed by metering of ethylene oxide. After maintaining the reaction temperature for some time to ensure that the product discharged from the reactor is free of ethylene oxide, the reaction mixture is separated by fractional distillation. Unconverted amine and water are removed as the first fraction and recycled to the subsequent batch. Pure alkanolamines are obtained by distillation under reduced pressure.

[0006] CN 214457699 U provides an ethanolamine production system, including an ethylene oxide metering tank and an ammonia tank both communicated with a mixer through pipelines. A reactor is communicated with the mixer through a pipeline, and a pressure pump is arranged on the pipeline. The system further includes an ammonia still, a dehydration tower and ethanolamine separation towers connected to each other through pipelines.

[0007] CN 214553403 U provides a methylethanolamine production system, which comprises an methylamine tank and a reactor, the methylamine tank being connected to the reactor via a pipeline, and a pressure pump being provided on the pipeline. An ethylene oxide metering tank is connected to the reactor. The system further includes an ammonia evaporation tower, an N-methyl-monoethanolamine tower and an N-methyl- diethanolamine tower.

[0008] The known processes are invariably operated with an excess of amine relative to the ethylene oxide. By controlling the molar ratios at which amine and ethylene oxide are mixed, the content of ethanolamines with multiple ethoxylation can be varied. For example, with a low molar ratio of amine to ethylene oxide a higher content of di- or tri-ethanolamine may be obtained. While at low molar ratios of amine to ethylene oxide conversion of reactants to products is virtually complete, it has been found that at higher molar ratios the reaction can come to a halt before all the ethylene oxide is consumed. This may be attributed to the fact that with a higher volume of amine solution in the reaction mixture the reaction enthalpy released does no longer suffice to increase the temperature of the reaction mixture and thus to activate the reaction to such an extent that the ethylene oxide is completely consumed. Also, the amount of sensible heat lost with the effluent becomes greater.

[0009] Theoretically, the length of the reactor could be increased in order to react to all ethylene oxide. However, this would result in higher capital expenditure (CAPEX) and would therefore be uneconomical. Alternatively, residence time of the reaction mixture could be increased in other ways, for example, by adopting lower volume flows. This, in turn, would also be uneconomical due to the lower space-time yield.

[0010] Accordingly, there is a continuing need for a versatile ethanolamine manufacturing process that can be readily adapted to changing amine to ethylene oxide ratios, operates efficiently at high amine to ethylene oxide ratios and that also produces a quality, on-spec product.

[0011] This object is solved by a process for the preparation of ethanolamines, the process comprising the steps of

[0012] (1) providing an amine-water solution,

[0013] (2) preheating the amine-water solution in a preheater to form a reactor inlet composition,

[0014] (3) feeding the reactor inlet composition to the inlet of a plug flow reactor having an inlet and an outlet downstream of the inlet,

[0015] (4) injecting ethylene oxide into the plug flow reactor at the inlet and / or one or more positions intermediate of the inlet and the outlet thereof to form a reaction mixture,

[0016] (5) reacting the reaction mixture in the plug flow reactor to form an effluent mixture comprising ethanolamines, and

[0017] (6) collecting the effluent mixture at the outlet of the plug flow reactor.

[0018] The amine may be selected from ammonia and alkyl amines. The alkyl amine may be a compound of formula (I)

[0019] HNR1R2

[0020] (I) wherein

[0021] R1is selected from H, Ci-Cs alkyl, and Ci-Cs hydroxyalkyl, and

[0022] R2is selected from Ci-Cs alkyl, and Ci-Cs hydroxyalkyl.

[0023] Preferably, R1is selected from H, C1-C4 alkyl, and C1-C4 hydroxyalkyl, and

[0024] R2is selected from C1-C4 alkyl. For example, the amine may be selected from methylamine and dimethylamine.

[0025] For example, reactions of ammonia with ethylene oxide may yield the following ethanolamines:

[0026] - monoethanolamine (MEOA)

[0027] - diethanolamine (DEOA)

[0028] - triethanolamine (TEOA), collectively referred herein as EOA.

[0029] For example, reactions of primary amines with ethylene oxide may yield the following ethanolamines:

[0030] - monomethylethanolamine (MMEOA, N-methylethanolamine) from methylamine

[0031] For example, reactions of secondary amines with ethylene oxide may yield the following ethanolamines:

[0032] - dimethylethanolamine (DMEOA, N,N-dimethylethanolamine) from dimethylamine

[0033] - methyldiethanolamine (MDEOA, N-methyldiethanolamine) from MMEOA

[0034] - diethylethanolamine (DEEOA, N,N-diethylethanolamine) from diethylamine.

[0035] The alkoxylation reaction is catalyzed by water. To this end, the amine-water solution is fed into the reactor, in which it is reacted with ethylene oxide. As the process of the invention is preferably catalyzed by water only, a heterogeneous catalyst is typically not necessary. Thus, generally and preferably, the lumen of the plug flow reactor, i.e. the internal open space or cavity of the reactor where the reaction occurs, is essentially devoid of a heterogeneous catalyst such as cation exchange resins.

[0036] The amine-water solution may comprise from 20% to 90% by weight of amine and from 10% to 80% by weight of water, preferably from 50% to 90% by weight of amine and 10% to 50% by weight of water, more preferably 70% to 90% by weight of amine and 10% to 30% by weight of water, even more preferably 70% to 85% by weight of amine and from 15% to 30% by weight of water.

[0037] The amine is commonly employed in a 1 to 20-fold molar excess, preferably a 1.5 to 18-fold molar excess, based on the ethylene oxide. The surplus of amine ensures a complete conversion of ethylene oxide and minimizes side product formation. Specifically, preferred molar ratios of amine to ethylene oxide are as follows:

[0038] For the manufacture of MDEOA: 1 .5 to 3;

[0039] For the manufacture of DMEOA: 2 to 6, preferably 4 to 6;

[0040] For the manufacture of EOA: 7 to 18, preferably 10 to 18, more preferred 12 to 18, still more preferred 14 to 17.

[0041] Suitable reaction conditions for the ethoxylation reaction employ pressures in the range of from 8 to 100 bar absolute (bara).

[0042] Specifically, reaction pressure (in bara) is as follows:

[0043] For the manufacture of MDEOA: 8 to 30, preferably 23 to 27;

[0044] For the manufacture of DMEOA: 8 to 30, preferably 23 to 27;

[0045] For the manufacture of EOA: 70 to 100, preferably 80 to 95.

[0046] According to the invention, the amine-water solution is preheated in a preheater to form a reactor inlet composition (see step (2)). Notably, only the amine-water solution is preheated in the preheater, while the ethylene oxide is not preheated in the preheater but is injected into the plug flow reactor at the inlet and / or one or more positions intermediate of the inlet and the outlet thereof (see step (4)). There is no mixing of the amine- water solution and the ethylene oxide upstream of the preheater. Generally, it is advantageous to avoid preheating ethylene oxide outside the reactor as introduction of heat can cause the ethylene oxide to undergo an exothermic polymerization reaction which in turn can result in safety issues which should be avoided. For the same reason, mixing of the amine-water solution and ethylene oxide upstream of the preheater should be avoided as otherwise, an uncontrolled reaction of ethylene oxide with the amine can occur. An efficient reaction control is only possible inside the reactor.

[0047] The preheater may be a heat-exchanger or an electric heater. Preferably, the preheater is a heat-exchanger. The heat-exchanger is not particularly limited, but those characterized by a high heat transfer relative to the heat exchange surface are generally preferred. Hence, the heat-exchanger is preferably selected from a platetype and a tube bundle heat-exchanger. The heating medium used in the heat-exchanger may be selected from steam, hot water, steam condensate, and heat transfer oil.

[0048] Typically, the higher the molar ratio of amine to ethylene oxide, the higher the heat transfer rate in the preheater. The heat transfer rate may be expressed in W (J / s).

[0049] Most preferably, preheating raises the internal energy of the amine-water solution to a level such that upon injection of the ethylene oxide, the ethylene oxide is essentially completely consumed in the reaction and the effluent mixture is essentially free of unreacted ethylene oxide. Herein, "essentially free” denotes that the effluent mixture comprises less than 1000 ppm, preferably less than 500 ppm of unreacted ethylene oxide. Higher residual amounts of EO would result in technical problems in downstream processing as EO is toxic, highly reactive and explosive.

[0050] In the case of the manufacture of EOAs, in especially preferred embodiments, the heat transfer rate provided by the preheater (in kW) per 1 t / h of ammonia-water solution volume flow rate is in the range of from

[0051] - 8 to 45 kWh / t, preferably 10 to 36 kWh / t, more preferably 10 to 35 kWh / t, when the molar ratio of ammonia to ethylene oxide is in the range of from 12 to less than 16

[0052] - 30 to 60 kWh / t, preferably 35 to 50 kWh / t, more preferably 36 to 50 kWh / t, when the molar ratio of ammonia to ethylene oxide is in the range of from 16 to 18.

[0053] Generally, the temperature of the reactor inlet composition is from 60 to 120 °C, preferably 70 to 110°C.

[0054] In the case of the manufacture of EOAs, especially, the temperature of the reactor inlet composition is in the range of from 60 to 120 °C, preferably 60 to 100 °C, when the molar ratio of ammonia to ethylene oxide is in the range of from 12 to less than 16.

[0055] In the case of the manufacture of EOAs, the temperature of the reactor inlet composition may also in the range of from 70 to 120 °C, preferably 70 to 110 °C, when the molar ratio of ammonia to ethylene oxide is in the range of from 16 to 18.

[0056] The amine-water solution and / or the reaction mixture may be heated further in the plug flow reactor, preferably by circulating a heating medium in a heating jacket attached to the plug flow reactor.

[0057] Using the preheater for preheating the amine-water solution is far more efficient than introducing the required heat exclusively via heating jackets in a section of the reactor upstream of the ethylene oxide injection. In a heating jacket of a plug flow reactor, the available heat exchange surface is limited. This would mean that a hotter and therefore more expensive energy carrier medium would have to be used, which in turn would result in high operating costs (OPEX) and would therefore be uneconomical.

[0058] The process of the invention involves a plug flow reactor, preferably a single tube tubular plug flow reactor. The reaction tube preferably has an essentially circular cross-section. The plug flow reactor has a large aspect ratio (ratio of length to internal diameter), preferably of more than 4000. The plug flow reactor enables continuous operation with little back mixing and has high heat exchange efficiency.

[0059] The reactor tube may be, for example, linear, meandering, coiled, or combinations thereof. If coiled, for example, then the reactor is also called "coiled reactor". Preferably, the tubular flow path contains a set of alternating bends or turns forming a meandering pattern between the inlet and the outlet. The reactor tube may proceed from inlet to outlet in a meandering, horizontal run, and then proceed vertically to a further level with another meandering, horizontal run, and this process can be repeated to any height desired. This creates a packed design with layered meandering, horizontal runs.

[0060] The preferred reactor length and internal pipe diameters depend on the ethanolamine prepared. For the production of MDEOA or DMEOA, the length of plug flow reactor is preferably from 400 to 500 m and the internal pipe diameter may be about 50 to 65 mm. The reactors for EOA are preferably from 1500 to 3000 m, for example about 2000 m, long and may have internal pipe diameters in the range of 95 to 115 mm.

[0061] In conjunction with the internal volume of the plug flow reactor and the flow rate of the reaction mixture, the resultant residence time generally is as follows:

[0062] For the manufacture of MDEOA and DMEAO: 1 to 20 min, preferably 1.5 to 15 min, more preferably 2 to 10 min, most preferably 3.5 to 5.5 min.

[0063] For the manufacture of EOAs: 5 to 25 min, preferably 7 to 20 min, more preferably 9 to 15 min, most preferably 12 to 14 min.

[0064] Generally, the residence time (T) can be determined according to the following formula: with

[0065] ^reactor being the volume of the lumen of the plug flow reactor in m3(cubic meters),

[0066] VAbeing the volume flow rate of the reactor inlet composition fed into the plug flow reactor in m3 / min

[0067] (cubic meters per minute), and

[0068] VE0being the volume flow rate of the ethylene oxide injected into the plug flow reactor in m3 / min (cubic meters per minute).

[0069] For the purposes herein and as evident from the above formula, the residence time can be calculated based on the volume flow rate of the starting materials, namely of the reactor inlet composition which is the preheated amine-water solution to be fed into the plug flow reactor according to step (3), and of the ethylene oxide to be injected into the plug flow reactor according to step (4). In other words, the residence time is typically not calculated based on the actual volume flow rate of the reaction mixture. This is because the composition of the reaction mixture changes over the length of the plug flow reactor. Thus, the actual volume flow rate for the reaction mixture cannot be easily determined.

[0070] The volume flow rate can be determined from the mass flow rate of the respective starting material divided through the density (i.e. the volumetric mass density) of the respective starting material for the relevant temperature. In this context, "relevant temperature” denotes the temperature of the respective starting material at the reactor inlet. Suitably, the volume flow rate can be determined by a mass flow meter, e.g. a Coriolis mass flow meter. Generally, such mass flow meters allow for determining both mass flow rate and density.

[0071] Ethylene oxide can be injected at one or more points at the inlet and / or one or more positions intermediate of the inlet and the outlet. Preferably, ethylene oxide is injected at a position close to the inlet. More preferably, ethylene oxide is injected at a position within 30% of the length of the reactor from the inlet. In particular, ethylene oxide is injected at a position within 15% of the length of the reactor from the inlet.

[0072] In the case of DMEOA and MDEOA, it is preferable to inject ethylene oxide at several points distributed over the length of the plug flow reactor. Doing so avoids temperature peaks which may arise from the high reactivity of methylamine and dimethylamine and allows for a better dissipation of the reaction enthalpy.

[0073] In the case of EOA, ethylene oxide can be injected all at once at the inlet or at one position intermediate of the inlet and the outlet. Alternatively, albeit less preferred, EC can be injected at several points distributed over the length of the plug flow reactor.

[0074] The reaction of amine and ethylene oxide is exothermic and cooling of the reaction mixture is necessary to prevent the reaction mixture from becoming too hot. Without sufficient removal of heat, vaporization of EO may occur, leading to a critical increase in pressure in the reactor. Appropriate cooling is applied such that the temperature of the reaction mixture does not exceed 190 °C, preferably the temperature of the reaction mixture does not exceed 170 °C.

[0075] Suitably, the reaction mixture is cooled at least in a section of the plug flow reactor downstream of the ethylene oxide injection. The section in which the reaction mixture is cooled may include the position of the ethylene oxide injection and extend downstream of the ethylene oxide injection. A cooling medium is applied to the outer surface of the section to remove heat conducted by the walls thereof. To this end, the cooling medium may be circulated through a cooling jacket attached to the plug flow reactor.

[0076] Hence, the process preferably comprises a cooling circuit including one or more cooling jackets attached to the plug flow reactor in one or more sections of the plug flow reactor downstream of the ethylene oxide injection, a pump for circulation of a cooling medium and a heat-exchanger. The cooling circuit may further include a cooling medium buffer vessel. In the heat-exchanger, the cooling medium is heat-exchanged against an external coolant such as river water or the like.

[0077] The reactor design may be such as to enable the heat of the exothermic reaction to be integrated with the preheating of the amine-water solution and / or an intermediate heating of the reaction mixture. A heat integration medium absorbs heat as it flows through a cooling jacket in a downstream section. The heat integration medium used in a downstream section of the plug flow reactor may be flowed to a heating jacket in a section of the plug flow reactor upstream to the (first) ethylene oxide injection.

[0078] In an embodiment, the process comprises a heat integration circuit including one or more heat transfer jackets (heat influx jackets) attached to the plug flow reactor for heat removal from the plug flow reactor and heat influx into the heat integration circuit, and one or more heat transfer jackets (heat outflux jackets) attached to the plug flow reactor for heating the amine-water solution and / or reaction mixture flowing in the plug flow reactor and heat outflux out of the heat integration circuit, and a pump for circulation of a heat integration medium. The heat integration circuit may further include a heat integration medium buffer vessel.

[0079] Heat influx jackets may be attached to the plug flow reactor in one or more sections of the plug flow reactor downstream of the ethylene oxide injection, whereas heat outflux jackets may be attached to the plug flow reactor in a section of the plug flow reactor upstream of the ethylene oxide injection.

[0080] Preferably, the process comprises both a cooling circuit and a heat integration circuit. In the section of the plug flow reactor downstream of the ethylene oxide injection, cooling jackets of the cooling circuit may be followed by heat influx jackets of the heat integration circuit, or cooling jackets and heat influx jackets may alternate. In the case of EOA, cooling jackets and heat influx jackets may alternate in the section of the plug flow reactor downstream of the ethylene oxide injection.

[0081] Generally, the reaction mixture is reacted adiabatically in a section of the plug flow reactor adjacent to the reactor outlet, also referred to as "dwell time section” herein.

[0082] More specifically, for the manufacture of MDEOA or DMEAO, cooling jackets preferably account for 50% to 75% of the length of the section of the plug flow reactor downstream of the ethylene oxide injection, with the remainder accounting for a dwell time section.

[0083] For the manufacture of EGAs, alternating cooling jackets of the cooling circuit and heat influx jackets of the heat integration circuit preferably account for 50% to 75% of the length of the section of the plug flow reactor downstream of the ethylene oxide injection, with the remainder accounting for a dwell time section.

[0084] In the case of the manufacture of EGAs, the process preferably does not comprise a step of recycling effluent mixture comprising ethanolamines to the process if the molar ratio of amine to ethylene oxide is in the range of from 12 to less than 16, or from 16 to 18. This is because high molar ratios of amine to ethylene oxide increase the yield towards monoethanolamine (MEGA), relative to diethanolamine (DEOA) and triethanolamine (TEOA). Thus, a recycle of effluent mixture would result in MEGA contained in the effluent mixture to further react with ethylene oxide, in turn decreasing the MEGA yield. As outlined, the alkoxylation reactions yield reaction mixtures comprising unreacted amine, potential side product(s), alkoxylation product, and water used as catalyst. For obtaining the alkoxylation product in essentially pure form, the alkoxylation reaction mixture has to be purified, e.g. by a series of distillations. For separation of compounds by distillation, sufficiently high temperatures are required which may, for example, be provided by electrical heating or medium pressure pressurized steam.

[0085] An especially preferred embodiment refers to the process for the preparation of ethanolamines (EOAs), i.e. to a process in which the amine is ammonia and the ethanolamine is selected from monoethanolamine (MEOA), diethanolamine (DEOA) triethanolamine (TEOA) and, typically, mixtures thereof, wherein step (1) comprises providing an ammonia-water solution, wherein the ammonia-water solution comprises from 20% to 90% by weight of ammonia and 10% to 80% by weight of water, preferably from 50% to 90% by weight of ammonia and 10% to 50% by weight of water, more preferably 70% to 90% by weight of ammonia and 10% to 30% by weight of water, even more preferably 70% to 85% by weight of ammonia and from 15% to 30% by weight of water, and the heat transfer rate provided by the preheater (in kW) per 1 t / h of ammonia-water solution volume flow rate is in the range of from

[0086] - 8 to 45 kWh / t, preferably 10 to 36 kWh / t, more preferably 10 to 35 kWh / t when the molar ratio of ammonia to ethylene oxide is in the range of from 12 to less than 16

[0087] - 30 to 60 kWh / t, preferably 35 to 50 kWh / t, more preferably 36 to 50 kWh / t when the molar ratio of ammonia to ethylene oxide is in the range of from 16 to 18.

[0088] Preferably, in the above embodiment, the temperature of the reactor inlet composition is in the range of from

[0089] - 60 to 120 °C, preferably 60 to 100 °C when the molar ratio of ammonia to ethylene oxide is in the range of from 12 to less than 16

[0090] - 70 to 120 °C, preferably 70 to 110 °C when the molar ratio of ammonia to ethylene oxide is in the range of from 16 to 18.

[0091] Preferably, in the above embodiment, the residence time of the reaction mixture in the plug flow reactor is in the range of from 5 to 25 min, preferably 7 to 20 min, more preferably 9 to 15 min, most preferably 12 to 14 min.

[0092] The invention is illustrated by the appended drawings and the example that follow.

[0093] Fig. 1 shows a plant set-up for carrying out the process of the invention.

[0094] Fig. 2 shows simulated temperature profiles and ethylene oxide concentration profiles over the reactor length.

[0095] As illustrated in Fig. 1, aqueous ammonia from an aqueous ammonia tank (not shown) is fed via pump 1 , heatexchanger 2 and line 3 to plug flow reactor 4. Reactor 4 comprises 23 layers L, designated as layer L1 through L23. Ethylene oxide from an ethylene oxide tank (not shown) is injected via line 5 in the third layer L3 of reactor 4. The mixing ratio between ammonia and the ethylene oxide can be appropriately set since production ratios of monoethanolamine, diethanolamine, and triethanolamine vary depending on the mixing ratio.

[0096] Reactor 4 comprises heat transfer jackets. L4 through L20 are cooled by a cooling circuit and heat integration circuit, respectively, (not shown) whereas L1 through L3 are heated via the heat integration circuit. In L21 to L23 of reactor 4, the reaction mixture is reacted adiabatically.

[0097] A reaction solution, which contains monoethanolamine, diethanolamine, and triethanolamine, as well as ammonia and water, is withdrawn from the reactor outlet via line 6 and forwarded to work up.

[0098] Examples

[0099] Methods

[0100] For simulation calculations, BASF in-house software Chemasim was used; comparable results were obtained using commercially available software such as Aspen Plus (manufacturer: AspenTech, Burlington / Massachusetts, USA) or PRO II (Fullerton, USA). The set of parameters was based on comprehensive measurements, studies on laboratory set-ups and operating data from various plants.

[0101] Example 1

[0102] The process of the invention was simulated with the following conditions:

[0103] - amine-water solution: 15 : 85 (% by weight) H2O : NH3

[0104] - molar ratio of NH3 : ethylene oxide: 16 : 1

[0105] - ethylene oxide volume flow rate: 5.19 t / h

[0106] - amine-water solution flow rate: 37.8 t / h

[0107] The temperature profile (Temperature) and the ethylene oxide concentration profile (xEO) over the reactor length was simulated at heat input of 1250 kW and 1750 kW provided by the preheater. The simulation results are depicted in Fig. 2. At 1750 kW (T_Qpreheat_1750kW; xEO_Qpreheat_1750kW), the reactor inlet composition has a temperature of about 78 °C (reactor length = 0 m). At a preheater output of 1250 kW (T_Qpreheat_1250kW; xEO_Qpheat_1250kW), the reactor inlet composition has a temperature of about 69 °C (0 m). Ethylene oxide (EO) is injected at a reactor length of 160 m. At 1750 kW, EO is essentially fully converted after about 1200 m. At a preheater output of 1250 kW, unreacted EO is still present at the reactor outlet (reactor length = about 1900 m). List of reference signs

[0108] 1 Pump

[0109] 2 Heat-exchanger

[0110] 3 Line

[0111] 4 Plug flow reactor

[0112] 5 Line

[0113] 6 Line

[0114] L1 Layer 1

[0115] L2 Layer 2

[0116] L3 Layer 3

[0117] L4 Layer 4

[0118] L5 Layer 5

[0119] L6 Layer 6

[0120] L7 Layer 7

[0121] L8 Layer 8

[0122] L9 Layer 9

[0123] L10 Layer 10

[0124] L11 Layer 11

[0125] L12 Layer 12

[0126] L13 Layer 13

[0127] L14 Layer 14

[0128] L15 Layer 15

[0129] L16 Layer 16

[0130] L17 Layer 17

[0131] L18 Layer 18

[0132] L19 Layer 19

[0133] L20 Layer 20

[0134] L21 Layer 21

[0135] L22 Layer 22

[0136] L23 Layer 23

Claims

Claims1. A process for the preparation of ethanolamines, the process comprising the steps of(1) providing an amine-water solution,(2) preheating the amine-water solution in a preheater to form a reactor inlet composition,(3) feeding the reactor inlet composition to the inlet of a plug flow reactor having an inlet and an outlet downstream of the inlet,(4) injecting ethylene oxide into the plug flow reactor at the inlet and / or one or more positions intermediate of the inlet and the outlet thereof to form a reaction mixture,(5) reacting the reaction mixture in the plug flow reactor to form an effluent mixture comprising ethanolamines, and(6) collecting the effluent mixture at the outlet of the plug flow reactor.

2. The process of claim 1 , wherein the lumen of the plug flow reactor is essentially devoid of a heterogeneous catalyst.

3. The process of claim 1 or 2, wherein the amine is selected from ammonia, methylamine and dimethyl amine.

4. The process of any one of the preceding claims, wherein the ethanolamine is selected from methyldiethanolamine (MDEOA), dimethylethanolamin (DMEOA), monomethylethanolamine (MMEOA), monoethanolamine (MEOA), diethanolamine (DEOA) and triethanolamine (TEOA).

5. The process of any one of the preceding claims, wherein the amine-water solution comprises from 20% to 90% by weight of amine and 10% to 80% by weight of water.

6. The process of any one of the preceding claims, wherein the amine is ammonia and the molar ratio of amine to ethylene oxide is in the range of 8 to 18.

7. The process of any one of the preceding claims, wherein preheating raises the internal energy of the amine-water solution to a level such that upon injection of the ethylene oxide, the ethylene oxide is essentially completely consumed in the reaction and the effluent mixture is essentially free of unreacted ethylene oxide.

8. The process of any one of the preceding claims, wherein the temperature of the reactor inlet composition is from 60 to 120 °C, preferably 70 to 110 °C.

9. The process of any one of the preceding claims, wherein the reaction mixture is cooled at least in a section of the plug flow reactor downstream of the ethylene oxide injection, preferably by circulating a coolant in a jacket of the plug flow reactor.

10. The process of any one of the preceding claims, wherein the reaction mixture is reacted adiabatically in a section of the plug flow reactor adjacent to the reactor outlet.11 . The process of any one of the preceding claims, wherein the preheater is a heat-exchanger or an electric heater.

12. The process of claim 11, wherein the heat-exchanger is selected from a plate-type and a tube bundle heat-exchanger.

13. The process of any one of the preceding claims, wherein the amine is ammonia, the ethanolamine is selected from monoethanolamine (MEOA), diethanolamine (DEOA) triethanolamine (TEOA), and mixtures thereof, step (1) comprises providing an ammonia-water solution, wherein the ammonia-water solution comprises from 20% to 90% by weight of ammonia and 10% to 80% by weight of water, preferably from 50% to 90% by weight of ammonia and 10% to 50% by weight of water, more preferably 70% to 90% by weight of ammonia and 10% to 30% by weight of water, even more preferably 70% to 85% by weight of ammonia and from 15% to 30% by weight of water, and the heat transfer rate provided by the preheater (in kW) per 1 t / h of ammonia-water solution volume flow rate is in the range of from- 8 to 45 kWh / t, preferably 10 to 36 kWh / t, more preferably 10 to 35 kWh / t when the molar ratio of ammonia to ethylene oxide is in the range of from 12 to less than 16- 30 to 60 kWh / t, preferably 35 to 50 kWh / t, more preferably 36 to 50 kWh / t when the molar ratio of ammonia to ethylene oxide is in the range of from 16 to 18.

14. The process of claim 13, wherein the temperature of the reactor inlet composition is in the range of from- 60 to 120 °C, preferably 60 to 100 °C when the molar ratio of ammonia to ethylene oxide is in the range of from 12 to less than 16- 70 to 120 °C, preferably 70 to 110 °C when the molar ratio of ammonia to ethylene oxide is in the range of from 16 to 18.

15. The process of claim 13 or 14, wherein the residence time of the reaction mixture in the plug flow reactor is in the range of from 5 to 25 min, preferably 7 to 20 min, more preferably 9 to 15 min, most preferably 12 to 14 min.

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