Process for continuous catalytic hydrogenation of MDA

Abstract

A process for the continuous catalytic hydrogenation of MDA, in particular an apparatus and a process for the hydrogenation of methylenediphenylamine (MDA) with a hydrogen donor, in which at least one (first) main reactor comprises a first flow path for the passage of a substance mixture through the fixed catalyst filler and a further flow path, a heat exchanger for influencing the temperature level in the first flow path is incorporated in the further flow path, and wherein the further flow path is a closed medium circulation system of a heat transfer medium, and a medium circulation system which extends outside the catalyst filler of the at least one main reactor at least over one section for indirect heat transfer, in which a heat exchanger is incorporated. The apparatus and process are improved in terms of product conversion and energy efficiency.

Description

Technical Field

[0001] The present invention relates to an apparatus and method for the continuous catalytic hydrogenation of MDA, particularly for the production of methylene bis(cyclohexylamine), especially for example 4,4'-diaminodicyclohexylmethane (PACM). Background Technology

[0002] Methods for hydrogenating organic compounds, especially for hydrogenating aromatic compounds into corresponding cyclohexane derivatives, are known in the art.

[0003] Methylenebis(cyclohexylamine) is an alicyclic amine that exists as a solid or liquid under standard conditions (SATP) and is typically produced by the liquid-phase hydrogenation of MDA. The acronym MDA was historically introduced as an abbreviation for a mixture of products formed in the reaction of aniline and formaldehyde that primarily contained "methylene diphenylamine" (diaminodiphenylmethane), and it is also used to describe the products of this process now produced on an industrial scale. The product of the hydrogenation reaction, primarily containing methylenebis(cyclohexylamine), is therefore often also referred to as H12MDA.

[0004] Due to its production method, MDA is typically a mixture of different diaminodiphenylmethanes. It is primarily composed of 4,4'-diaminodiphenylmethane. However, 2,4' and 2,2' isomers may also be present. MDA may also contain reaction products with three or more aromatic rings formed in the reaction of aniline and formaldehyde, particularly those with three or more phenyl rings. These reaction products with three or more aromatic rings are also known as polynuclear compounds.

[0005] Due to the high proportion of 4,4'-diaminodiphenylmethane in the MDA used, commercially available methylene bis(cyclohexylamine) is primarily composed of 4,4'-diaminodicyclohexylmethane or bis(p-aminocyclohexyl)methane. Since the corresponding 2,4'- and 2,2'-diaminophenylmethane isomers may be present in the MDA, 2,4'-diaminodicyclohexylmethane and 2,2'-diaminodicyclohexylmethane may also be present in methylene bis(cyclohexylamine). Furthermore, hydrogenated MDA may contain (possibly partially) hydrogenated polynuclear compounds in addition to methylene bis(cyclohexylamine).

[0006] US 5,578,546 A discloses a method for producing methylenebis(cyclohexylamine), first described in 1947 and scaled up for industrial use in 1965. The hydrogenation of MDA is highly exothermic. For example, WO 2010 / 069484 A1 indicates a reaction enthalpy of -1600 kJ / mol.

[0007] As a result of hydrogenation, various diastereomers are formed according to the method. Here, the product 4,4'-diaminodicyclohexylmethane (PACM), derived from 4,4'-diaminodiphenylmethane, can exist in trans / trans, cis / cis, and cis / trans isomer forms, and is therefore typically a mixture of these isomers in different proportions. Here, the melting point of the compound increases with increasing trans / trans content. Therefore, the application areas differ significantly depending on the isomer content: the quality of methylene bis(cyclohexylamine) with low trans / trans content (e.g., 10-30 wt%) is used in the field of amine and isocyanate crosslinking agents, especially in the field of two-component resins, while the quality with high trans / trans content (e.g., ≥48 wt%) is mainly used as a modifier in polyamide compounds. The production of the product with low trans / trans content is precisely a challenge because, as described in US 3,636,108A, the thermodynamic equilibrium is in the region with significantly higher trans / trans content (up to 51.2%). Furthermore, US2,606,925 A indicates that subsequent heat treatment over a longer period can shift the equilibrium toward a higher proportion of trans / trans isomers.

[0008] The composition of the hydrogenation product also depends on the composition of the MDA used: MDA is typically used in grades from MDA50 to MDA100, where the number between 50 and 100 indicates the diaminodiphenylmethane content in the MDA mixture. MDA50, as explained above, is an MDA grade containing approximately 50% by weight of diaminodiphenylmethane and 50% by weight of polynuclear compounds due to process-related reasons. Depending on the number of aromatic nuclei present, the various polynuclear compounds can be referred to as trinuclear compounds, tetranuclear compounds, etc. MDA50 is the grade produced in the highest quantities and is primarily further processed into methylene dicyclohexyl diisocyanate (MDI). MDA100 is pure MDA or diaminodiphenylmethane without polynuclear compounds. MDA85 or MDA90 are other commercially available grades of medium purity. If the purity of the MDA grade is mentioned in a patent specification relating to a method for producing methylene bis(cyclohexylamine), it is usually MDA100 (e.g., CN 110204447B). In contrast, US2005 / 261525 A1 preferably emphasizes the hydrogenation of MDA50. As shown in US2004 / 162409 A1, the hydrogenated oligoamines obtained here as high-boiling-point substances are suitable as crosslinking agents with particularly low vapor pressures for a range of special applications.

[0009] The content of hydrogenated polynuclear compounds in the products (possibly partially) decreases in the order of reactants MDA50, MDA85, MDA90, and MDA100, because the content of polynuclear compounds decreases from MDA50 to MDA100.

[0010] WO 2009 / 153123 A1 discloses a continuous method and reactor for hydrogenating organic compounds in a multiphase, multi-stage system in the presence of a homogeneous or multiphase catalyst. The proposed catalysts particularly include noble metals such as platinum, palladium, ruthenium, and rhodium, or other transition metals such as molybdenum, tungsten, and chromium. The multiphase catalyst may be arranged on a support material such as carbon, alumina, silica, zirconium dioxide, zeolite, aluminosilicate, or a mixture of these support materials. In this method, aromatic compounds containing amino substituents, such as MDA, polymeric MDA, aniline, 2,4-diaminotoluene, 2,6-diaminotoluene, o-phenylenediamine, etc., are preferably used as the substrate. The multiphase catalyst is used in suspension.

[0011] DE 19533718 A1 discloses a method for hydrogenating an aromatic compound in which at least one amino group is bonded to an aromatic core. For this purpose, a heterogeneous catalyst containing ruthenium and optionally at least one metal from subgroups I, VII, or VIII can be used. The support material used is, for example, alumina, silica, titanium dioxide, or zirconium dioxide, preferably alumina or zirconium dioxide. Only catalysts containing ruthenium on alumina, rather than zirconium oxide, support material are given as examples.

[0012] EP 1337331 A1 discloses a method for the catalytic hydrogenation of aromatic or heteroaromatic amines, wherein ruthenium acts as the active metal, and the catalyst contains at least one additional metal of subgroup I, VII, or VIII, which is applied to a support material. Aromatic compounds used herein particularly include 4,4'-MDA and its isomers. EP 0111238 A1 also discloses a method for the catalytic hydrogenation of 4,4'-MDA, characterized by hydrogenation in the presence of supported ruthenium in the presence of alkali metal nitrates and sulfates and alkaline earth metal nitrates. A similar method is disclosed in EP 1366812 A1, wherein the support materials mentioned particularly include alumina, silicon oxide, titanium oxide, and zirconium oxide.

[0013] DE 101 19 135A1 discloses an apparatus and method for producing diaminodicyclohexylmethane (PACM) having a proportion of 17% to 24% trans,trans-4,4'-diaminodicyclohexylmethane, wherein this is achieved by hydrogenating diaminodiphenylmethane (MDA) in the presence of a powdered catalyst. Hydrogenation is carried out in a continuously operating suspension reactor, particularly in a cascade of multiple suspension reactors connected in series, to achieve an MDA conversion of at least 95% based on the amount of MDA used.

[0014] EP 1 519 912 B1 discloses an apparatus and method for producing 4,4'-diaminodicyclohexylmethane (4,4'-HMDA), wherein catalytic hydrogenation with improved selectivity for 4,4'-MDA is achieved by means of a mixture of substances comprising 4,4'-diaminodiphenylmethane (4,4'-MDA) as a major component and its mono-N-methyl derivative as a by-component, in the presence of a heterogeneous hydrogenation catalyst, at a temperature of 50 to 220 °C and a hydrogen pressure of 1 to 30 MPa. To this end, EP 1 519912 B1 suggests ending hydrogenation before achieving a conversion of 4,4'-MDA to 4,4'-HMDA of 99%, particularly in the range of 90% to 98.9%.

[0015] WO 2011 / 003899 A1 and WO 2009 / 090179 A1 disclose further methods for hydrogenating organic compounds. A method for hydrogenating aromatic amines with hydrogen gas in the presence of a Ru catalyst, particularly containing a zirconium oxide support material, is disclosed herein.

[0016] Finally, EP 2 883 863 B1 discloses a method and apparatus for hydrogenating 4,4'-methylenediphenylamine (MDA) and / or polymeric MDA with hydrogen in the presence of a catalyst. The catalyst proposed herein is ruthenium applied to a zirconia support material. Regarding the reactor, EP 2 883 863 B1 refers to the reactor or reactor concept of WO 2008 / 015135A1. WO 2008 / 015135A1 discloses a continuous method and apparatus for hydrogenating diisononyl phthalate to diisononyl cyclohexane-1,2-dicarboxylate (DINCH), wherein DINP is hydrogenated with hydrogen as a mixture in an organic solvent at a pressure of up to 325 bar. A series connection of two fixed-bed reactors is proposed herein, each reactor having a stationary fixed bed. To dissipate the heat of reaction from the two reactors, it is proposed to recirculate the sub-feed stream of the mixture downstream of the second fixed-bed reactor and thereby cool it. A similar reactor concept for a series fixed-bed reactor for hydrogenation is also known from EP 1 566 372 B1.

[0017] The drawback of this concept is that the cyclical guidance of the product stream may lead to an increase in the formation of unwanted byproducts and a reduction in the plant's production capacity, which in turn increases the energy costs of recycling and cooling the recirculated stream and makes the plant and method very energy-intensive to operate overall.

[0018] As explained, the demand for PACMs with varying proportions of their respective isomers depends on the intended use or subsequent products. For example, PACMs with low trans / trans content of 10% to 30% by weight are preferred in the field of amine and isocyanate crosslinking agents, particularly in the formulation of two-component resins, while PACMs with high trans / trans content exceeding 48% by weight are primarily used as modifiers in polyamide compounds. The weight percentages mentioned here are based on the PACM isomer mixture itself. The production of products with low trans / trans content is precisely a technological challenge, as thermodynamic equilibrium exists in the region of significantly higher trans / trans content, up to 51.2% by weight, as described in US 3,636,108 A. Furthermore, it is known from US 2,606,925 A that subsequent heat treatment for extended periods can shift the balance of PACM isomers toward higher proportions of trans / trans isomers. Summary of the Invention

[0019] Therefore, one object of the present invention is to provide an improved apparatus and an improved method that improves product conversion and energy efficiency, and particularly enables the production of a corresponding proportion of isomers defined in a mixture of isomers.

[0020] According to the present invention, the objective is achieved by the apparatus according to claim 1 and the method according to claim 16.

[0021] This article provides an apparatus for the continuous catalytic hydrogenation of methylene diphenylamine (MDA; reactant 1) using a hydrogen donor (reactant 2), particularly a gaseous hydrogen donor, preferably hydrogen (H2), comprising a reactant conditioning unit (104), a reactor unit (102), and a separation unit (106), wherein...

[0022] - The conditioning unit includes a (feed) line for reactant 1, reactant 2 and at least one solvent, at least one heat exchanger in at least one (feed) line, and at least one mixer for mixing the reactants and / or at least one reactant with at least one solvent.

[0023] - The reactor unit includes at least one fixed-bed reactor as a main reactor with a fixed catalyst packing, wherein the at least one main reactor includes a first flow path for supplying a mixture of substances through the fixed catalyst packing, wherein the at least one main reactor is incorporated into a further flow path, and wherein a heat exchanger for influencing the temperature level in the first flow path is incorporated into the further flow path.

[0024] -The separation unit includes at least

[0025] - A first separation stage, comprising at least one device for separating and removing solvent, wherein the at least one device is connected downstream to at least one condenser via at least one (top) pipeline, and

[0026] - A second separation stage, comprising at least one device for separating at least one reactant and / or at least one byproduct from the product, wherein said at least one device is connected downstream to at least one condenser via at least one (top) line, wherein

[0027] The additional flow path is a closed-loop circulation system of heat transfer medium, which extends at least in one section outside the catalyst packing of the at least one main reactor for indirect heat transfer, wherein a heat exchanger is incorporated into the circulation system.

[0028] The additional flow path is connected in such a way as to other pipelines of the device, especially the pipelines of the reactor unit, that no reactants or mixtures of substances can flow into it during normal operation.

[0029] By utilizing this alternative flow path in a closed-circuit system, in which a pump is advantageously incorporated as a delivery device, it is possible to achieve a significant performance improvement compared to WO 2008 / 015135 A1. Furthermore, surprisingly, a trans / trans ratio of 22% by weight in the product was achieved through quasi-isothermal operation of the main reactor.

[0030] This apparatus is preferably used for the continuous catalytic production of methylenebis(cyclohexylamine) of formula (I) as a product, especially for the production of 4,4'-diaminodicyclohexylmethane (PACM).

[0031]

[0032] In a further embodiment of the apparatus, it may be advantageous for the reactor unit to include a first main reactor and at least one additional downstream reactor in series.

[0033] The downstream reactor is advantageously connected in series with the main reactor and has a fixed catalyst that is physically identical or substantially identical to the catalyst in the main reactor. The amount and spatial arrangement of the fixed catalyst, as well as the flow path of the material within the downstream reactor, are chosen such that a molar conversion of up to 20%, advantageously up to 15%, and ideally up to 10% of MDA is achieved, wherein the reaction is considered complete at 100% molar MDA conversion. The downstream reactor is advantageously operated as an adiabatic reactor, and in a further embodiment of the apparatus, it may be advantageous to arrange at least one heat exchanger in the pipeline between the at least one main reactor and the downstream reactor.

[0034] Over time, catalyst activity decreases until replacement or regeneration is required. To address this, the operating temperature is increased in parallel by controlling the cooling loop, specifically through a small degree of cooling via a heat exchanger integrated into the cooling loop, to maintain the overall conversion and selectivity at a substantially constant level. This results in a shift in the isomer ratio toward higher trans / trans content in the product. It has proven highly advantageous here that the feed temperature to the downstream reactor can be autonomously controlled, particularly synchronously, using an upstream heat exchanger. Thus, as the operating temperature of the main reactor rises during the catalyst's lifetime, the feed temperature in the downstream reactor's mass stream is reduced.

[0035] With the aid of a separate post-reactor, especially an adiabatic post-reactor, the method and apparatus can be optimized for control, thereby enabling selectivity due to the difference in inlet temperature between the post-reactor and the main reactor (outlet). Typically, the inlet temperature of the post-reactor can be provided at the same or slightly lower temperature, which can be up to 30°C lower than the outlet temperature of the main reactor. Therefore, at least temporarily, a temperature increase of 20°C to 40°C, typically 20°C to 30°C, is permissible in the (adiabatic) post-reactor, and thus the desired product quality (isomer ratio) can be selectively adjusted. In this way, a very low and very precise trans / trans isomer ratio can be established in the isomer mixture. The main reactor can be operated at the lowest possible temperature level to achieve a trans / trans ratio of approximately 13% to 20% wt% in the material stream (main reactor outlet), of approximately 13% wt% in the case of new or regenerated catalysts, and 20% wt% in the case of catalysts that have been used for a long time (shortly before replacement / regeneration). Depending on the stage of the main reactor, it may be meaningful, at least temporarily, if the inlet temperature of the downstream reactor is 5 to 20°C higher than that of the main reactor.

[0036] Although the main reactor is referred to as “isothermal” in this paper, this ideal state is only achieved to a limited extent in industrial applications. As a result, due to incomplete heat dissipation, a temperature gradient of approximately 5 to 10 °C is formed within the main reactor in the radial direction and in the flow direction.

[0037] The downstream reactor is fed at a slightly higher temperature via an upstream heat exchanger, allowing the desired residual reaction and isomer transformation to occur, resulting in, for example, a final desired trans / trans ratio of 17% to 23% by weight. The downstream reactor, with its weakly exothermic residual reaction, operates in a substantially adiabatic manner, but this should not be understood in an ideal sense.

[0038] From time point t0 (the start of the method after catalyst renewal or regeneration) to time point t4 (the end of the method as determined by catalyst renewal or regeneration), the operating temperature of the main reactor can be increased, and the temperature of the material stream at the inlet (feed) of the downstream reactor can be maintained or decreased. Advantageously, the apparatus is designed to continuously and / or gradually increase or decrease the temperature.

[0039] The main reactor operates isothermally or substantially isothermally, and the downstream reactor operates adiabatally or substantially adiabaticly. At time point t0, i.e., at the start of the method, the catalyst in the downstream reactor, in addition to the main reactor, may have already been renewed or regenerated. Advantageously, the regeneration cycle of the downstream reactor is determined autonomously and independently of the main reactor, especially when the aforementioned interaction between the two reactors is no longer able to produce the desired low trans / trans ratio in the PACM.

[0040] The liquid material stream from the depressurized separation tank (hereinafter referred to as the separation tank (also called a flash vessel in some cases)) is guided via pipeline to the first separation column within the first separation stage of the separation unit. The separation tank is characterized by the separation of the incoming material stream into a vapor phase (solvent-rich) and a liquid phase (solvent-lean) through depressurization (pressure reduction), both of which are present in the separation tank during normal operation. The separation tank may additionally have, or be connected to, a bottom feed circulation system with an integrated heat exchanger to increase the separable vapor fraction beyond a pressure-determined fraction by heating the liquid phase. Furthermore, the separation tank may contain internal components or bulk packing to specifically prevent the entrainment of droplets that are not solvent-lean or only partially solvent-lean. Advantageously, in one embodiment of the apparatus, a pressure control unit may be provided in the pipeline from the separation tank to the first column. This allows the reactor unit to operate at a first high-pressure level and the first separation stage of the separation unit to operate at a second lower pressure level. Therefore, in this document, the separation tank (flash vessel) refers to a device in which phase separation is essentially caused by depressurization. In contrast, a separation tower in this paper refers to a device in which separation into a vapor phase and a liquid phase occurs primarily by supplying energy, particularly by incorporating a top circulation system, in which at least a portion of the condensed liquid is guided back into the tower at the top.

[0041] Advantageously, the mixing unit is formed in two parts and includes, for example, a mixing device and a gas saturator. The mixing device can be a dynamic or static mixer, particularly suitable for the close bonding of MDA (reactant 1) with the solvent. The gas saturator can be, in particular, a small tower or tank, with suitable internal components to ensure that the H2 gas supplied under high pressure is strongly dissolved in the MDA / solvent stream and / or uniformly distributed before entering the main reactor. The H2 gas pressure is advantageously between 70 bar and 100 bar.

[0042] The terms "immobilized catalyst packing" or "immobilized catalyst" refer to any form of localized catalyst that does not flow or move with the mass stream, such as, in particular, a catalyst bed (granular or coated support) or a fixed internal structure coated with catalyst material. Advantageous internal structures with catalyst coatings can be, for example, grids, plates, or other types arranged in the main reactor.

[0043] In this document, "XY unit" and / or "XY stage" always refer to at least one corresponding device, apparatus, etc., included in the corresponding unit or stage. This refers, for example, to a mixing unit / stage that includes the at least one mixer / mixing device.

[0044] Unless otherwise explicitly stated otherwise, “heat exchange” or “heat exchanger” in this document always refers to indirect heat exchange and the corresponding design with enclosed material and medium guiding lines.

[0045] The "condensing unit" of the first separation stage refers to a single heat exchanger or a group of heat exchangers used for at least partial condensation and / or cooling of the low-boiling fractions discharged via the top line. The "condensing unit" as referred to herein does not need to be a (closed) structural unit. Therefore, in some cases, the terms "condensing unit" and "single heat exchanger" are used synonymously. A "condenser" refers to a heat exchanger that has a cooling effect on a (steam) line and is intended to at least partially condense the vapor in the corresponding line. However, such a name should not be interpreted restrictively, as all media streams, reactant streams, and material streams are considered in the current relevant context of EK, such that, for example, a condenser can act as a heat source for coupled downstream heat exchangers. Therefore, the final understanding of the meaning must always be derived from the respective textual context.

[0046] A stage specifically designated as the “first separation stage” is provided, with corresponding equipment and piping, for the (specifically) separation of the solvent from the product-rich material stream, and advantageously, for its return to the reactor unit and / or conditioning unit for use. The first separation stage is defined such that at least 80%, ideally at least 90%, of the solvent is separated. Similarly, a stage designated as the “second separation stage” is meant to be defined, with corresponding equipment and piping to guide the separation of the product from byproducts and reactants, particularly MDA, and to purify the product. In this case, the first and second separation stages may not be completely strictly separated, and there may be overlapping areas or transitional areas where both the solvent and at least one byproduct or at least one reactant are separated from the product. In this context, where the product may be, in particular, PACM, “separation to remove solvent” and “separation of at least one reactant and / or at least one byproduct from the product” in the first separation stage mean that this separation does not imply an absolute boundary between separation stages, but rather “substantially” involves only one or more of the mentioned substances in each case.

[0047] In this document, the term "reactant mixture" refers to the mixture of substances present upon entry into the (first) main reactor, i.e., a mixture of all reactants, solvents, additives, etc. The mixture of substances flowing in any degree of reaction or subsequent purification within and downstream of said at least one reactor is referred to as a "substance stream" or "substance mixture," wherein in some cases adjectives such as "product-rich" or "solvent-rich" are added. However, the material composition of the substance stream at each location in the apparatus is also readily apparent to those skilled in the art from that location in the apparatus and the upstream apparatus components, particularly the process technology equipment of the apparatus. Pure substances, such as the product PACM, and byproducts LB and HB are individually named and identified. "LB" here stands for "low-boiling substance," a valuable mixture of substances that is separately separated from the substance stream and product and has a low boiling point of approximately 240°C to 290°C. Similarly, "HB" stands for "high-boiling substance," a valuable mixture of substances that is separately separated from the substance stream and product and has a high boiling point of >350°C.

[0048] This document specifically claims an apparatus and method for the production of methylenebis(cyclohexylamine) as a product, particularly 4,4'-diaminodicyclohexylmethane (PACM), by the catalytic hydrogenation of methylene diphenylamine. Here, the main product is PACM, obtained by the hydrogenation of 4,4'-diaminodiphenylmethane (4,4'-MDA; the main component of reactant 1), particularly having the aforementioned low trans / trans isomer ratio. Therefore, this apparatus and method are particularly suitable for and adapted for the production of 4,4'-diaminodicyclohexylmethane (PACM) by the continuous catalytic hydrogenation of 4,4'-diaminodiphenylmethane (4,4'-MDA). The additional components of MDA, 2,4'-MDA and 2,2'-MDA, are converted to the reaction product in parallel, at least in small proportions, where these are generally retained in the product mixture. Furthermore, other byproducts can advantageously be purified and separated by this method or apparatus in a second separation stage of a separation unit, particularly in at least one separation column. These are secondary (valuable) products, which are basically described and meant in this document as high-boiling-point (HB) and low-boiling-point (LB) products.

[0049] The solvent is advantageously selected from the group consisting of cyclohexane, dioxane, tetrahydrofuran (THF), cyclohexylamine, dicyclohexylamine, methanol, ethanol, isopropanol, n-butanol, 2-butanol, 2-methoxy-2-methylpropane (MTBE), or methylcyclohexane or mixtures thereof. Advantageously, the solvent, especially THF, is supplied in excess to the MDA such that the mass flow ratio of the solvent, especially THF, to the MDA at the inlet of the main reactor is advantageously in the range of 1.0 to 8.0, particularly in the range of 2.0 to 7.5.

[0050] This paper describes different forms of energy coupling and heat transfer, which are defined as follows:

[0051] In general, it may be advantageous that the first separation stage of the separation unit includes at least one separation tank connected via pipeline to the main reactor, the downstream reactor, or the last main reactor in the flow direction, wherein the separation tank includes a top outlet, a bottom / feed outlet, and a heatable feed recirculation system with at least one heat exchanger, wherein the at least one condensation unit is incorporated into the (top) pipeline connected to the top outlet. Furthermore, a collection container, and / or a connection unit / node having / introducing a (return) pipeline for solvent, may be located downstream of the condensation unit.

[0052] The material stream from the separator is guided via a (feed) line to the first separation column in the second separation stage of the separation unit. Advantageously, in one embodiment of the apparatus, a pressure control unit may be provided in the (feed) line from the separator to the first column. This allows the reactor unit to operate at a first high-pressure level and the first separation stage of the separation unit to operate at a second lower pressure level.

[0053] A potentially advantageous design would be to provide at least one EK that incorporates at least one of the following heat exchangers:

[0054] -The at least one condenser in the first separation stage, particularly the condenser in the (top) line of the separation tank,

[0055] -The at least one condenser in the second separation stage, particularly the condenser of the separation tower in the second separation stage,

[0056] - The at least one heat exchanger of the media circulation system of the at least one main reactor.

[0057] Energy coupling (EK) here refers to integrated energy coupling or direct energy coupling, where

[0058] i) Integrated EK refers to integrated energy coupling, which is further subdivided into

[0059] a. Material-based energy coupling (integrated material-based EK) in which at least two material flows are integrated in indirect heat exchange within a heat exchanger, i.e., the structure is integrated in a single heat exchanger (device). This means that, in the case of previously providing two heat exchangers, the two heat transfer functions of the structural unit (heat exchanger) are integrated.

[0060] b. The integration of at least two heat exchange media in the heat exchanger in indirect heat exchange with media-based energy coupling (integrated media-based EK) means that the structure is integrated in a single heat exchanger (device);

[0061] ii) Direct EK (Direct Energy Coupling), also known as series EK, refers to the interconnection of at least two structurally separate heat exchangers, which is further subdivided into:

[0062] a. A series integrated heat exchanger (EK), wherein the material stream (integrated material-based EK) or medium stream (integrated medium-based EK) from the first heat exchanger is further conveyed to a downstream second heat exchanger for use in the next integrated EK, so that each acts on a different material stream or a different medium stream.

[0063] b. A series of "material-based EKs" in which the material stream from the first heat exchanger is further conveyed to a downstream second heat exchanger to act on (different) medium streams and / or

[0064] c. A series of “medium-based EKs” in which the medium flow from the first heat exchanger is further conveyed to a second downstream heat exchanger so that each acts on a (different) material flow.

[0065] In any case, EK in this document does not refer to a (commonly) single heat exchanger without further (thermal) connections, in which heating or cooling by (only) one heat exchange medium is also (only) one reactant stream or material stream. Furthermore, in this context, "another material stream" refers to a material stream at a different device location, with a different material composition, and / or at a different temperature level, while "another medium stream" should be understood similarly.

[0066] In an advantageous variant of this embodiment of the device, the device (100) may include at least one of two heat exchangers interconnected in series to form an integrated material base EK, wherein the material flow from the first heat exchanger in the integrated material base EK is further conveyed in the series interconnection to a second downstream heat exchanger for use in another integrated material base EK.

[0067] In a further advantageous embodiment of the device, it may be that at least one heat exchange loop takes the form of a direct EK (series EK), wherein at least two heat exchangers are combined for series material-based or medium-based EK. The heat exchange loop is advantageously a closed loop. Generally, it may be advantageous, in the case of EK and the loop as EK, to provide heat exchangers as on-demand or controlled heat exchangers with particularly independent coolant or heat sources, so as to ensure overall open-loop and closed-loop control of the thermodynamic energy of the device and to achieve additional degrees of freedom in control technology. These on-demand or controlled heat exchangers, especially in the case of integrated material-based EK, are generally significantly smaller in construction than previously integrated heat exchangers that have been omitted according to integrated material-based EK.

[0068] In a further advantageous embodiment of the device, it may be that at least one of the following pipelines is incorporated as a heat source for the integrated material-based EK into the condenser within the (top) pipeline of the separator tank:

[0069] i) The (feed) line leading to the main reactor,

[0070] ii) The feed line (116) leading to the post-reactor,

[0071] iii) The feed line to the first separation tower, wherein the pressure control unit is located in the feed line upstream of the condenser.

[0072] iv) At least one additional heat exchanger of material-based EK for integration is incorporated in the condenser downstream of the pipeline junction according to i), ii) or iii) and upstream of the collection container.

[0073] In a further advantageous embodiment of the apparatus, the apparatus may comprise a medium-based EK connected in series as a loop having multiple pipeline sections, wherein at least the following devices and / or pipelines are incorporated: a collection container downstream of the separator, a (top) pipeline as a pipeline section, particularly the first pipeline section, and a (feed) pipeline leading to the separator as another pipeline section, particularly the last pipeline section. In this embodiment, the solvent, as a heat exchange fluid, flows through the (heat exchange) loop, and the first flow path of the main reactor is a pipeline section of this loop. Naming the pipeline section as the first or last pipeline section indicates the flow direction in the loop but is not intended to constitute any further limitation.

[0074] In a variation of this embodiment of the apparatus, the feed line from the condenser to the first separation tower of the first separation stage may be integrated into the heat exchanger loop within the top line of the separation tank for use with the integrated material base EK, wherein the top line acts as the heat source for the feed line. It is particularly advantageous to locate the pressure control unit in the feed line upstream of the condenser.

[0075] In a further advantageous embodiment of the apparatus, the media circulation system of the main reactor may serve as a heat source by incorporating the (feed) line of the first separation tower into a heat exchanger for EK. Here, a pressure control unit is located in the (bottom) line upstream of the heat exchanger in the media circulation system. Therefore, the temperature in the (feed) line leading to the first separation tower is at a very advantageous level, allowing the downstream heat exchanger to absorb a correspondingly large amount of heat at an advantageously low temperature level.

[0076] In this text, multiple nouns enclosed in parentheses are frequently used, such as (feed) line, (bottom) line, (top) line, etc. The nouns in parentheses are used to explain and facilitate linguistic understanding of their meaning, but should not constitute a limitation, as, for example, the (top) line of a container constitutes, for example, the (feed) line connected to the corresponding container downstream. Furthermore, "flow path," "material flow," "medium flow," and "reactant flow" are used in some cases as synonyms for the relevant pipeline, especially for describing the device, associated equipment, components, and elements, and their arrangement. Similarly, EK always refers to the corresponding equipment, such as heat exchangers, condensers, etc.

[0077] In a further advantageous embodiment of the apparatus, at least one of the following pipelines can be designed as an integrated heat source for the material-based EK into the condenser of the separation tower in the corresponding (top) pipeline of the second separation stage:

[0078] i) The (feed) line leading to the main reactor,

[0079] ii) The (feed) line leading to the post-reactor,

[0080] iii) The (feed) line to the first separation tower of the first separation stage, wherein the pressure control unit is located in the (feed) line upstream of the condenser of the respective separation tower.

[0081] In an advantageous embodiment of this device, the media pipeline may be:

[0082] i) At least one of the following heat exchangers leading from the condenser of the separation tank in the separation unit, which serves as a heat source, to the reactor unit or conditioning unit:

[0083] - Heat exchangers in the (feed) lines leading to the main reactor and / or in equipment located upstream of the main reactor, especially mixers or saturators.

[0084] - Heat exchangers and / or in the (feed) line leading to the downstream reactor

[0085] - Heat exchangers in the (feed) line leading to the first separation tower of the separation unit, and at least two of these heat exchangers operating as direct EK can be connected in parallel with each other;

[0086] ii) From the (cooling) heat exchanger of the reactor, which serves as a heat source, to at least one of the following heat exchangers:

[0087] - Heat exchangers in the (feed) lines leading to the main reactor and / or in equipment located upstream of the main reactor, especially mixers or saturators.

[0088] - Heat exchangers in the (feed) line leading to the first separation tower of the separation unit, wherein at least two of these heat exchangers operating as direct EK can be connected in parallel with each other; and / or

[0089] iii) A heat exchanger (for cooling) in the top circulation system of the separation unit leads to at least one downstream (for heating) heat exchanger in the feed or bottom circulation system of the separation unit, especially

[0090] - The heat exchanger in the (feed) line from the heat exchanger of the second separation stage to the heat exchanger in the first separation stage.

[0091] -The heat exchanger in the top loop of the separation column, which serves as a heat source for separating the first product, especially product PACM, leads to the (feed) line of the first separation column.

[0092] - A heat exchanger in the top loop of the separation tower, which serves as a heat source, leads to the bottom feed circulation system of the separation tank.

[0093] In this article, "medium pipeline" refers to a pipeline in which a heat exchange fluid, which is neither a mixture of reactants nor a mixture of substances, flows. Typically, the heat exchange fluid is water, steam, brine, or oil. "Medium loop" should be understood similarly in this article.

[0094] In a further embodiment of the apparatus, it may be advantageous that the separation unit in the first separation stage includes at least one pressure control unit and a separation tank in the (feed) line leading to the separation tank, the separation tank having a condensation unit for the solvent. Advantageously, the solvent (return) line can be led from the first separation stage (particularly the collection container) to the conditioning unit.

[0095] The liquid material stream from the separator is guided via a (feed) line to the first separation column in the first separation stage of the separation unit. Advantageously, in one embodiment of the apparatus, a pressure control unit may be provided in the (feed) line from the separator to the first column. In this way, the reactor unit can operate at a first high-pressure level, and the first separation column of the first separation stage can operate at a second lower pressure level, wherein the separator can operate at an intermediate level.

[0096] Furthermore, it may be advantageous to provide a heat exchanger upstream of the first separation tower, particularly downstream of the pressure control unit, or between the pressure control unit and the first separation tower. In an advantageous embodiment, a media line is provided to interconnect the (feed) heat exchanger of the downstream reactor or the condenser in the top loop of the separation tank with the (feed) heat exchanger of the first separation tower in a series media base EK.

[0097] In the first step, via direct energy input, such as superheated steam, the material stream from the main reactor (feed to the first separation tower) can be heated by approximately 5 to 20°C in a (feed inflow) heat exchanger downstream of the upstream pressure control unit, with an inlet-side temperature level of approximately 85 to 95°C. The outflowing heating medium, a vapor-condensate mixture, can be directed downstream of the series-coupled (feed inflow) heat exchanger of the subsequent reactor. The advantage of this approach is that the first separation tower also has a bottom feed circulation system and an integrated (bottom feed) heat exchanger, which can meet the full energy requirements of the first separation tower if needed. Therefore, this coupling allows for optimal energy exchange with the downstream (feed inflow) heat exchanger (series-coupled media base EK) of the subsequent reactor, while as an energy saving, the remaining energy can flow back to the first separation tower.

[0098] In a particularly advantageous embodiment, energy coupling is provided to operate the condenser downstream of the separator, the condenser of the separator in the second separation stage, or the (circulating feed) heat exchanger in the media circulation system of the at least one main reactor interconnected in heat exchange with the (feed) heat exchanger of the first separator. Energy coupling can be achieved through conduction of the media and series interconnection of the respective heat exchangers, or through integrated energy coupling in a (structurally) single heat exchanger. If spatially feasible within the device, integrated energy coupling has the advantage that only the temperature gradient for heat transfer needs to be overcome. Thus, parallel heating of the (feed) material stream upstream of the first separator in the first separation stage, having a temperature level of approximately 85 to 95°C downstream of the upstream pressure control unit in the (feed) line, is possible via energy transfer.

[0099] As the main reactor operates at rising temperatures to compensate for declining catalyst activity, it can release increasing energy in parallel to the feed stream upstream of the first separation tower. Consequently, the energy demand in the bottom loop or the heat exchanger incorporated into the first separation tower also decreases continuously.

[0100] In one embodiment of the apparatus, it may be advantageous that the reactor unit comprises a first main reactor and at least one downstream post-reactor connected in series. A particular advantage of the inlet-side temperature control of the post-reactor and its material stream is that, due to a higher inlet temperature than that of the main reactor, the selectivity for controlling the isomer ratio can be optimized in this way.

[0101] Advantageously, the post-reactor is also a fixed-bed reactor, or a reactor with a fixed catalyst, such as a catalyst bed or internal components coated with a catalyst.

[0102] Advantageously, the fixed catalyst contains ruthenium, either already doped with ruthenium or formed from ruthenium. In an advantageous variant of the process, particularly to achieve a low trans / trans isomer ratio in the isomer mixture, the main reactor is operated at a temperature of 90 to 140 °C, ideally 95 to 135 °C.

[0103] It has been found particularly advantageous that the catalyst mass ratio in the main reactor to the downstream reactor is in the range of 1.2 to 2, preferably 1.3 to 1.4, and ideally 1.35. It has been surprisingly found that by simply regulating the highly exothermic reaction at the start of the reaction in the main reactor using a strong cooling loop, and by adjusting only the feed temperature at the inlet of the downstream reactor to achieve a moderate temperature increase of approximately 30 to 35°C from inlet to outlet in the downstream reactor, as already stated, there is only a limited and easily reproducible effect on the trans / trans isomer ratio in the material stream or product.

[0104] Perhaps particularly advantageous is that the main reactor is a fixed-bed reactor, which includes

[0105] - For the first flow path of reactant mixtures or substance mixtures, and

[0106] - An additional (closed) flow path, namely the medium circulation system for heat exchange, wherein two heat exchangers for indirect heat exchange are incorporated into the second flow path:

[0107] - The (main) heat exchanger operates as a cooler, and

[0108] - A (secondary) heat exchanger that operates as a heater.

[0109] It has been found to be very effective and advantageous to operate the same additional flow path or media circulation system with the aid of a (secondary) heat exchanger to prepare and start up the main reactor and to cool the main reaction during the production operation of the main reactor with the aid of a (main) heat exchanger.

[0110] In a further embodiment of the device, it may be advantageous to

[0111] The reactor unit includes another main reactor in the form of a fixed-bed reactor, which includes

[0112] -The first flow path for the mixture of substances, and

[0113] - An additional (closed) flow path, namely a (cooling) medium circulation system for heat exchange, wherein valve units are provided upstream of the two main reactors in the (feed) line, thereby allowing the volumetric flow rate of the reactant mixture to be divisible, conductable, and / or fully switchable between the first and other main reactors, wherein the two main reactors are (in a thermal conduction manner).

[0114] - Each is connected to a heat exchanger or

[0115] - Commonly connected to a heat exchanger

[0116] This forms the other (closed) flow path.

[0117] In this case, the two main reactors connected in series are identical or substantially identical in design. In particular, the dimensions and / or internal components of the two main reactors are designed to accommodate or contain the same or substantially the same mass and / or volume of catalyst.

[0118] The advantage of these two main reactors is that further thermal decoupling of the highly exothermic first reaction stage, the moderately exothermic second reaction stage, and the lowly exothermic post-reaction stage is possible. A further advantage is that, with the same plant capacity, each main reactor has a smaller size, thus allowing for easier and more uniform thermal control. Simultaneously, the plant capacity is increased because the unit does not need to be completely shut down during maintenance, such as catalyst replacement. For this purpose, the two main reactors are interconnected using pipeline technology in a manner that allows the mixture of substances to flow individually through each main reactor while bypassing the corresponding other main reactor (bypass 1).

[0119] Hydrogenation under significant cooling in a (isothermal) main reactor can significantly limit temperature-induced isomerization. In a (adiabatic) post-reactor, a sufficiently high temperature level is established, specifically through heat exchange, in the incoming material stream, and thus allows isomerization to deliver just the required trans / trans ratio in the product. In a purely isothermal operation with a single main reactor without a post-reactor, excessively low trans / trans ratios and high proportions of unconverted MDA are initially obtained. By allowing the possibility of targeted adiabatic hydrogenation of the material stream, temperature evolution in the post-reactor can be advantageously controlled, and thus isomerization controlled.

[0120] In a further improved variant, the pipeline interconnection technology allows the downstream reactor to be bypassed (bypass 2) even when at least one main reactor is operating, but particularly when two main reactors are operating in series. In the bypass 2 interconnection variant, the downstream reactor, acting as the second main reactor through which fluid flows in the flow direction, at least temporarily assumes the function of the downstream reactor, allowing the unit to operate with little or no reduction in production capacity and / or changes in product quality, especially changes in the proportions of isomers in the isomer mixture.

[0121] In a further embodiment of the apparatus, it may be advantageous to arrange at least one common heat exchanger in the pipeline between the at least one main reactor and the second main reactor. This common heat exchanger is positioned in the central branch of the two coolant circulation systems. The routing and interconnection of the pipelines here ensure that, downstream of the common heat exchanger, the cooling medium is first introduced into the first of the two main reactors, where a more exothermic reaction takes place. The heated cooling medium is then supplied via pipeline to the downstream second main reactor to apply a different feed temperature to the latter than that to the first main reactor.

[0122] The advantage lies in the surprising observation that very precise control, particularly in the first highly exothermic reaction stage, is crucial for product quality, thus eliminating the construction work and control technical complexities involved in a separate, completely independent second cooling loop. Another reason is that complete reaction can be ensured and controlled, especially by controlling the feed temperature of the downstream reactor connected in series downstream of the two main reactors; in particular, the desired low trans / trans isomer ratio can be established.

[0123] In a variant of the device with improved controllability, it may be possible to place a heat exchanger (aftercooler) that can be switched and controlled as needed in a corresponding (cross) line of the cooling loop used to connect the coolant outlet of the first main reactor to the coolant inlet of the second main reactor.

[0124] The bottom recirculation system of the separator operates at a temperature of 130°C to 150°C, ideally 135°C to 145°C. A significant advantage of the separator, which is very simple in construction and control technology, is that by reducing the pressure, the boiling point temperature of the mixture is also lowered, so heating in the separator only needs to reach this lowered boiling point temperature. Furthermore, with this measure, approximately 90% of the solvent, especially THF, present in the reactant mixture can be separated and removed. This eliminates the need for a top loop or return stream in the column. The material stream continuing to be fed to the first separation column therefore advantageously has a residual solvent concentration of only about 20% to 40% by weight, ideally 25% to 35% by weight. Therefore, the first separation column can have a smaller construction design and can operate more energy-efficiently due to the lower mass of the material stream.

[0125] In this way, the temperature of the material stream can be reduced more quickly, thus preventing or reducing any increase in the trans / trans isomer ratio of the products in the material stream, especially PACM products.

[0126] Connect the solvent transfer (return) line to the conditioning unit and / or at least one suitable collection tank.

[0127] Finally, in an advantageous embodiment of the device, at least one heat exchange loop can be included in the form of a series-integrated material-based EK having multiple pipeline sections, wherein at least the following devices and heat exchangers are combined and connected via at least one pipeline section.

[0128] i) As a heat exchanger and as a heat source for the heat exchange circuit

[0129] -In the heat exchanger of the medium circulation system in the main reactor, or

[0130] - In the (top) pipeline of the separator, each of the (top) heat exchangers is integrated with at least one of the following pipelines, which serves as a heat sink in the heat exchange loop and conducts the flow of reactants or materials, in a material-based EK:

[0131] a) The (feed) pipeline downstream of the pressure control unit leading to the first separation tower.

[0132] b) The (feed) line leading to the downstream reactor, especially on the suction side of the pump integrated into it.

[0133] c) The (feed) line upstream of the reactor, especially the mixing vessel upstream of it, or the (return) line upstream of the mixer leading to the conditioning unit.

[0134] ii) As equipment, at least a main reactor, especially the main reactor and the downstream reactor, at least one separation tank, at least one collection vessel for the first separation stage, and wherein

[0135] iii) The following pipelines are integrated as pipeline sections of this loop:

[0136] a) The (first) pipeline section corresponding to the (top) pipeline of the at least one separation tank and / or

[0137] b) The (final) pipeline section corresponding to the (feed) pipeline leading to at least one collection tank in the second separation stage.

[0138] The present invention further includes a method for the continuous catalytic hydrogenation of methylene diphenylamine (MDA; reactant 1) using a hydrogen donor (reactant 2), particularly a gaseous hydrogen donor, preferably hydrogen (H2), wherein production is carried out by means of an industrial plant, wherein the plant is designed according to at least one of the embodiments and variants described herein, and wherein the main reactor operates at a temperature in the range of 80°C to 150°C.

[0139] In a favorable implementation, energy coupling (EK) is used:

[0140] i) The condenser of the separation unit, in this case the condenser in the top loop of the separation tank, serves as the heat source for at least one heat exchanger of the reactor unit, conditioning unit and / or separation unit, transferring energy within the range of available heat, particularly in the range of 20% to 40%, by means of an integrated EK or a direct EK.

[0141] ii) The heat exchanger of the (cooling) medium circulation system of the main reactor of the reactor unit serves as the heat source for at least one heat exchanger of the reactor unit, conditioning unit, and / or separation unit, transferring energy in the range of 5% to 30% of the available heat via integrated EK or direct EK; particularly in the range of 10% to 20%, and / or

[0142] iii) The heat exchangers of the separation unit transfer energy between each other via integrated EK or direct EK in the range of 5% to 100% of the available heat, especially in the range of 30% to 90%.

[0143] In a further embodiment of the method, it may be advantageous to provide at least one post-reactor containing a fixed catalyst, in addition to the at least one main reactor, wherein the at least one main reactor and the at least one post-reactor operate at the same or substantially the same pressure.

[0144] In a further embodiment of the method, it may be advantageous to have the temperature of the reactant stream at the inlet of the main reactor be 90 to 140°C, ideally 100 to 135°C.

[0145] In a preferred embodiment of this method, the continuous catalytic production of methylenebis(cyclohexylamine), particularly 4,4'-diaminodicyclohexylmethane (PACM), is achieved, preferably 4,4'-diaminodicyclohexylmethane (PACM) with a low trans / trans isomer ratio. In a preferred variation of the method, the continuous catalytic production of methylenebis(cyclohexylamine), particularly PACM, of formula (I) is achieved.

[0146]

[0147] In a further embodiment of the method, a further advantage is that the at least one main reactor operates at a pressure in the range of 60 to 120 bar, ideally in the range of 70 to 100 bar. In a further advantageous embodiment, the pressure in the main reactor may be 80 to 90 bar. Particularly preferred is a pressure of approximately 85 to 95 bar.

[0148] In a further embodiment of the method, a further advantage may be that, from time point t0 (the start of the method after catalyst renewal or regeneration) to time point t4 (the end of the method as determined by catalyst renewal or regeneration), the operating temperature of the main reactor is increased, and the temperature of the material flow at the inlet (feed) of the downstream reactor is maintained or decreased, wherein the increase or decrease in temperature is linear and / or gradual.

[0149] The aforementioned device variants thus enable the method (method sequence) to achieve a low trans / trans ratio of 17% to 25% by weight in PACM over time.

[0150] In a further embodiment of the method, a further advantage may be that the MDA (reactant 1) comprises a mixture of at least two isomers: 4,4'MDA, 2,4'MDA, and 2,2'MDA. The MDA (reactant 1) is advantageously a mixture comprising the monomers 4,4'MDA, 2,4'MDA, and 2,2'MDA, wherein the proportion of 4,4'MDA is advantageously in the range of 75 to 98 mol%, preferably 85 to 95 mol%, ideally about 90 mol%. The proportion of 2,4'MDA in the reactant mixture is advantageously 7 to 15 mol%, preferably 8 to 12 mol%, ideally 9 to 10 mol%.

[0151] Ideally, the proportion of 4,4' PACM (trans / trans PACM) is in the range of 15% to 30% by weight, ideally 16% to 25% by weight.

[0152] Overall, it is advantageous that the reaction steps in the main reactor are carried out isothermally or substantially isothermally, while the reaction steps in the subsequent reactors are carried out adiabatally or substantially adiabatously. At time point t0, i.e., at the start of the method, the catalyst in the subsequent reactors, in addition to the main reactor, may also be in the form of renewal or regeneration. Advantageously, the regeneration cycle of the subsequent reactors is determined autonomously and independently of the main reactor, especially when the aforementioned interactions between the reactants in the two reactors are no longer able to produce the desired low trans / trans ratio in the PACM.

[0153] In an advantageous embodiment of the method, the temperature of the reactant stream at the inlet of the main reactor may be 90 to 140°C, ideally 100 to 135°C, and preferably 105 to 115°C.

[0154] In a further advantageous embodiment of the method, the pressure in the main reactor may be 70 to 100 bar, ideally 80 to 90 bar.

[0155] In a further advantageous embodiment of the method, the temperature at the inlet of the main reactor may substantially correspond to the temperature at the inlet of the downstream reactor, where “substantially” means a range or difference of + / -10°C, and / or the pressure at the inlet of the main reactor may substantially correspond to the pressure at the inlet of the downstream reactor, where “substantially” means a range or difference of + / -5 bar.

[0156] In summary, all aspects, advantages, and implementations related to or in connection with the apparatus should also apply equally or similarly to the method, and vice versa, unless otherwise stated and / or there is a technical impossibility related to a similar application.

[0157] The solution according to the present invention will now be described in detail with reference to the embodiments. Attached Figure Description

[0158] The attached diagram shows:

[0159] Figure 1 The apparatus is shown as a process flow diagram.

[0160] Figure 2 A first embodiment of the device having a first direct EK is shown.

[0161] Figure 3 A second embodiment of the device with another direct EK is shown.

[0162] Figure 4 A first embodiment of the reactor unit is shown.

[0163] Figure 5 A second embodiment of the reactor unit is shown.

[0164] Figure 6 A third embodiment of the device is shown, having another direct EK as an integrated material-based EK.

[0165] Figure 7 A fourth embodiment of the device is shown, having another direct EK as an integrated material-based EK.

[0166] Figure 8 A fifth embodiment of the device is shown, having another direct EK as an integrated material-based EK.

[0167] Figure 9 A sixth embodiment of the device is shown, having another direct EK as an integrated material-based EK, which has series interconnections and loop guidance.

[0168] Figure 10 A seventh embodiment of the device is shown, having a circuit for further conduction of the medium.

[0169] Figure 11 Showing alternatives Figure 10 The eighth embodiment of the device is a circuit for further conducting the medium.

[0170] Figure 1 This apparatus 100 shows a continuous production of 4,4'-diaminodicyclohexylmethane (PACM) by catalytic hydrogenation of methylene diphenylamine (MDA; reactant 1), particularly 4,4'-diaminodiphenylmethane, using a hydrogen donor (reactant 2), wherein the hydrogen donor is supplied in the form of gaseous hydrogen (H2). The apparatus 100 includes a reactant conditioning unit 104, a reactor unit 102, and a separation unit 106.

[0171] Conditioning unit 104, outlined by a dashed line, includes feed lines for reactant 1, hydrogen (reactant 2), and solvent. Furthermore, the conditioning unit includes a compressor unit 150, the compressor mentioned below in the hydrogen supply line 151, and a mixer 152 in the lines supplying the solvent and reactant 1. A pump 156 and a heat exchanger 158 are additionally provided in the line 153 supplying the mixture of reactant 1 and solvent. Lines 151 and 152 lead to a mixing vessel 154 located upstream of the main reactor 200. The mixing vessel 154 is used for thorough mixing of the reactants, and its discharge forms the feed to the main reactor 200.

[0172] Reactor unit 102 is outlined by a dashed line and essentially includes a main reactor 200, a cooling circuit 500, a post-reactor 210, and a heat exchanger 206 in the feed line of the post-reactor 210. The cooling circuit 500 incorporates a pump 204 and the heat exchanger 202, wherein the circulating coolant in the main reactor 200 flows around a carrier element filled with catalyst material. In the illustrated example, the flow direction toward the carrier element filled with catalyst material is a co-current flow. The post-reactor 210 is connected via line 211 to separation unit 106, i.e., its first separation stage.

[0173] The heat exchanger 202 in the cooling circuit 500 is shown as an air-cooled heat exchanger 202, but it can also be alternatively designed to control the temperature of the cooling medium in the cooling circuit 500 in indirect heat exchange, for example, by means of a flowing cooling medium, such as oil, water, or brine. In a variant of the device not shown, the cooling circuit 500 also incorporates a similar... Figure 5 and 6 The heat exchangers 208 and 209 in the middle. Figure 5 and 6Heat exchangers 208 and 209 operate with a heating medium and are used in the start-up step of the main reactor 200 to regulate the temperature of the main reactor 200 to approximately 80 to 100°C, ideally to 85 to 95°C. In an example of the apparatus and method shown, where the objective is to achieve the smallest possible trans / trans isomer ratio of approximately 17% to 23% by weight, the main reactor 200, filled with fresh or regenerated catalyst, is preheated to approximately 90°C by means of heat exchanger 208. The main reactor 200 operates at a pressure of 87 to 88 bar.

[0174] Separation unit 106, outlined by dashed lines, includes multiple separation devices for separating the solvent, particularly in the first separation stage, and the PACM product, particularly in the second separation stage, from the remaining reactants and byproducts. The first separation stage (not shown) includes a separation tank 300 connected to a bottom feed circulation system incorporating a heat exchanger 302 and a pump 306. The top outlet of separation tank 300 is connected to a heat exchanger 304, i.e., a condenser, downstream of which a solvent collection container 310 is provided. Approximately 80% of the solvent (here, THF) is condensed using heat exchanger 304 (condenser) and can be collected or returned. During the flash evaporation stage, the heat exchanger 302 in the bottom feed circulation system of separation tank 300 requires approximately 1400 kW of energy.

[0175] Condenser 304 is shown as a heat exchanger in the design of an air-cooled device, but it can also be alternatively designed, for example, by means of a flowing cooling medium, such as cooling water or a medium suitable for thermal integration, to at least partially condense and cool a material stream that begins as a vapor in indirect heat exchange.

[0176] The energy amounts mentioned in this article are calculated for the plant production capacity of the PACM product in the mentioned synthesis reaction, which is approximately 3.37 t / h, and the byproduct outputs of approximately 0.4 t / h of HB and approximately 0.05 t / h of LB. The THF to MDA mass flow rate ratio is 4.2 to 4.5.

[0177] Furthermore, the first separation stage of separation unit 106 for further separation and solvent removal includes a first separation tower 320 and a second separation tower 330, wherein the second separation tower 330 is in the form of a stripping tower. For this purpose, nitrogen (N2) is advantageously used as the stripping medium, flowing countercurrently through the tower relative to the material stream. A solvent-lean material stream can be transferred to the first separation tower 320 via line 161 by means of a pump 306 located at the bottom outlet of the separator 300. A pressure control unit 222 is provided in line 161 and, in the illustrated example, is designed as a controllable valve. As shown, the material stream is introduced into the first separation tower 320 via a central inlet. As an optional embodiment, an additional (inflow) heat exchanger 327 (shown by dashed lines) is provided upstream of the first separation tower 320, constituting a possible option for heating the first separation tower 320.

[0178] In the first separation tower 320, the solvent concentration is reduced from 30% by weight in the feed (through the product-rich material stream from line 161) to approximately 2% by weight of residual solvent.

[0179] The first separation tower 320, equipped with (structured) packing material, is connected to a bottom circulation system incorporating a heat exchanger 322 and a pump 326. Furthermore, a top circulation system is provided at the top of the first separation tower 320, incorporating a heat exchanger 324 designed as a condenser. Two discharge lines for the solvent-rich material stream exit from the top circulation system, with one of the discharge lines leading to the top discharge line of the downstream separation tower 330 (stripping tower).

[0180] Specifically, the solvent separated in the first separation stage can be guided via line 311 to a collection tank (not shown) and / or a mixer 152 of the conditioning unit 104. A pressure control unit 220, designed as a controllable valve in this embodiment, is provided in line 211 from the post-reactor 210 to the separation tank 300.

[0181] A product-rich stream with approximately 2% by weight of residual solvent (THF) is directed from the bottom outlet of the first separation column 320 via line 321 to the top of the second column 330 (stripping column). A heat exchanger 328 is incorporated in line 321. The second column 330 has at least one internal packing, with a gas feed line, particularly an inert gas (stripping gas), positioned below the packing so that the introduced product-rich stream flows through the second column 330 countercurrently to the stripping gas and further deplete the solvent. In the illustrated embodiment, nitrogen (N2) is used as the stripping gas. Solvent-rich vapor is introduced into the condenser 334 via the top outlet and is fed into the condenser 334 together with the vapor stream from the top outlet of the first separation column 320 and introduced into the top discharge line of the second separation column 330. The solvent stream condensed in the heat exchanger 334 is sent to the recovery unit 104, where the non-condensable portion is discharged from the heat exchanger 334 and, for example, is completely thermally oxidized.

[0182] The product-rich material stream is fed from the bottom outlet of the second separation tower 330 via a pipeline 331 connected to a pump 336 into the third separation tower 340. The second separation stage 106B of the separation unit 106 is specifically used to separate the by-products LB and / or HB from the PACM product.

[0183] The second separation stage (106B) basically comprises three separation towers, with the third separation tower 340, which is the first tower of the second separation stage, being centrally fed with the material stream. The third separation tower is connected to a bottom circulation system incorporating a heat exchanger 342 and a pump 346. The product-rich material stream is directed from the bottom effluent to the fourth separation tower 350 via line 341. Furthermore, the third separation tower 340 is connected to a top circulation system incorporating a heat exchanger 344. The condensed LB is drawn from this top circulation system as a first byproduct.

[0184] The product-rich material stream is centrally fed into the fourth separation tower 350 via line 341. The fourth separation tower 350 is connected to a bottom circulation system incorporating a heat exchanger 352 and a pump 356. Furthermore, the fourth separation tower 350 is connected to a top circulation system incorporating a heat exchanger 354 in the form of a condenser. The product-rich material stream is discharged from the top circulation system as condensate via a top discharge line. In this case, according to the illustrated example, uncondensed vapor and / or gas streams are introduced into the top discharge line of the downstream fifth separation tower 360. Subsequently, the product is further condensed and discharged via another heat exchanger 364 (condenser). A material stream with low product content is discharged via line 351 through the bottom discharge line of the fourth separation tower 350 and introduced into the top of the fifth separation tower 360. This material stream is highly enriched with HB, the second byproduct. The fifth separation tower 360 is connected to a bottom circulation system incorporating a heat exchanger 362 and a pump 366. Furthermore, the separation tower 360 has a top outlet leading to the aforementioned heat exchanger 364 in the form of a condenser. In this condenser 364, another product-rich material stream is condensed and discharged as condensate, while the non-condensable portion is discharged as a gas. The latter can then be completely oxidized.

[0185] Regarding the material flow, reactor unit 102 operates at a first high-pressure level of approximately 60 to 120 bar, the first separation stage 106A of separation unit 106 operates at a second low-pressure level of 4 to 12 bar, and the first separation tower 320 and the second separation tower 330 operate at a third slightly higher pressure level of 1.05 to 2.5 bar. In the example shown, the first pressure level is 80 to 90 bar, the second pressure level is 4.5 to 7.5 bar, and the third pressure level is 1.1 to 1.2 bar.

[0186] Direct temperature control of the main reactor 200 via a cooling loop 500 connected in series with the uncooled post-reactor 210 has surprisingly proven to be a reduced energy requirement and a simplified, more stable process control scheme compared to existing technologies. Without being bound by any particular interpretation, this success can be seen in the fact that the cooling loop 500 only needs to be specifically designed for the very vigorous initial reaction to remove the exothermic heat of reaction, while the still significant post-reaction is only regulated by the upstream heat exchanger 206 via the feed temperature. Since the reaction in the post-reactor 210 has been highly attenuated, the material stream is only heated to approximately 5 to 15°C and can be discharged into the separator 300 without any problems at this level.

[0187] Generally, the accompanying drawings illustrate internal components of equipment such as reactors, separation towers, and containers, including packing materials, separation planes, and support elements, using appropriate symbols. These represent respective advantageous embodiments regarding quantity, type, and / or relative position with respect to the corresponding feed or discharge lines. For example, the illustration of the first separation tower 320 thus indicates that, advantageously, the (feed) material flow is introduced via line 161 such that, in each case, at least one (theoretical) separation plane exists between the top circulation system and the bottom circulation system. The specific type and / or number of separation planes are known to those skilled in the art and can be modified or provided in an appropriate manner.

[0188] Figure 2 This illustrates a first embodiment of direct EK, wherein device 100 corresponds to Figure 1 The device is shown in dashed lines 230, 232, and 234, indicating the medium lines through which the heated medium from heat exchanger 304 (condenser) located in (top) line 163 of separator 300 is directly and further conveyed as a heating medium to other downstream heat exchangers 158, 206, and 327. The three medium lines 230, 232, and 234, and their associated directly further conveyed medium lines, can be provided individually or jointly. Heat exchangers 158, 206, and 327 are thus connected in parallel, with all three heat exchangers acting as the heat source for condenser 304. The medium flowing to condenser 304, in this case water, exits device 100 downstream of the three heat exchangers 158, 206, and 327.

[0189] Figure 3 This illustrates another embodiment of direct EK, which serves as a series dielectric-based EK, wherein device 100 substantially corresponds to Figure 1 and 2 Similar to Figure 2Heat exchanger 304 serves as a heat source, connected to heat exchanger 158 in the feed of main reactor 200 and heat exchanger 327 in feed line 161 of first separation tower 320. Heat exchangers 158 and 327 are connected to condenser 304 in series via medium line EK and are connected in parallel to each other. Furthermore, heat exchanger 322, supplied with, for example, superheated steam, is connected via medium line 238 to heat exchanger 206 in downstream reactor 210 via medium conduction. The effluent condensate or water-steam mixture exits heat exchanger 322 at a temperature above 170°C and acts as an energy source for heat exchanger 206 via direct further energy / medium conduction, thus eliminating the need for additional energy consumption in heat exchanger 206. Media line 236 shows the media connection between the heat exchanger 354 of the fourth separation tower 350 and the second (bottom) heat exchanger 302B connected in parallel with the first heat exchanger 302A for the steam feed. This redundant design, with two bottom heat exchangers 302A and 302B in the bottom circuit of the separator 300, reduces the energy requirement by approximately 35%.

[0190] exist Figure 3 In the illustrated embodiment, heat exchanger 304 (condenser), serving as a heat source, is directly connected via a media line, i.e., in series, to heat exchangers 158, 206, and 327, which operate as heat sinks. In this case, the integrated heat sinks are heat exchanger 327 in the feed line 161 of the first separation tower 320, heat exchanger 206 in the feed inlet of the downstream reactor 210, and heat exchanger 158 in the feed line 153 upstream of the main reactor 200. This possible option of direct thermal coupling via a media line is shown. Figure 3 The box below mark A. As described above, for example, according to... Figure 2 Compared to incorporating a heat sink into the distributor circuit 570, this selective direct interconnection as a direct EK via the medium line and heat distribution from the condenser 304 results in an efficiency increase of 30% to 50%.

[0191] Unless otherwise stated, “increased efficiency” in this document means lower energy consumption. The reference point is obvious from the context and may be based on the device, separately described segments of the device, or improved equipment, such as by integrating two heat exchangers into a single heat exchanger.

[0192] Figure 4 This shows an improved variant of reactor unit 102. Two main reactors 200, 201 are here interchangeably connected in series with each other. Figure 4Some valves / valve units that can be controlled via open-loop and / or closed-loop control are shown; others can be provided by those skilled in the art as needed to ensure the safe operation of the two main reactors 200, 201. The two main reactors 200, 201 are each integrated into cooling circuits 500, 501, thereby maintaining the fixed-bed reactors 200, 201 at permissible cooling reaction temperatures under their respective conditions. In the interconnection of the main reactors 200, 201 shown and indicated by solid lines, fluid first flows into the first main reactor 200 via line 110 from mixing vessel 154, and the first part of the reaction occurs in this main reactor 200. Downstream, the mixture is introduced into the top of the second main reactor 201 via a lower outlet and line 112, and exits via a bottom outlet and line 115 into a common line 116 as feed into a common downstream reactor 210. The common line 116 is integrated with a heat exchanger 206, thereby ensuring the required temperature level in the downstream reactor 210. The flow sequence through the two main reactors can also be reversed, proceeding from main reactor 201 to main reactor 200. For this purpose, in a similar manner, the fluid first flows through line 111 to main reactor 201, where line 110 leading to the top of main reactor 200 is closed. The mixture exits this fixed-bed reactor via a bottom outlet and (intermediate) line 113, which connects to the top of main reactor 200, where line 115 is closed. Finally, the mixture exits main reactor 200 via a bottom outlet and line 114, which similarly leads to a common line 116 and from there to the downstream reactor 210. Lines 502 and 503 branch off from each of the two cooling circuits 500 and 501, respectively, and are guided through a respective vessel 212 and 213, which act as pressure balancing vessels, and further to the chimney and / or the complete oxidation unit. Piping and valve / valve units are provided and designed such that each of the main reactors 200, 201 can operate independently and the material flow can completely bypass the corresponding other main reactor. The flow direction of the two cooling loops 500, 501 is indicated by arrows, wherein the two cooling loops 500, 501 are advantageously designed to be identical or substantially identical, since the two main reactors 200, 201 operate alternately as the first or second main reactor relative to the flow direction of the reactant flow or material flow.

[0193] However, cooling circuits 500 and 501 are designed and controllable to meet autonomous cooling power or cooling function in each case, according to process-related requirements, particularly product management and / or product quality. This specifically relates to the volumetric flow rate of the cooling medium per unit time and / or the corresponding temperature level or permissible heating of the cooling medium. Furthermore, there are direct options for thermal integration of cooling circuits 500 and 501 with other unit sections or heat exchangers, where heat exchangers 202 and 203 act as heat sources by receiving reaction heat, thereby reducing the overall energy consumption of the unit or method used to produce PACM.

[0194] Figure 4 The optional pipeline 117 is also shown as a dashed line (bypass 2), which can bypass the downstream reactor 210—if, for example, it needs maintenance and / or catalyst refill. In this case, the temperature of the second main reactor is controlled, at least in the direction of material flow, to ensure complete reaction at the desired product quality, particularly the desired proportions of the respective isomers. Pipeline branches of 117 can be provided upstream or downstream of heat exchanger 206 in the flow direction; it is advantageous to provide them upstream of heat exchanger 206 so that they can be bypassed if necessary, and necessary maintenance operations can be performed while the unit is running. Furthermore, there is a direct possibility of thermal integration of cooling circuits 500, 501 with other unit sections or heat exchangers, where heat exchangers 202, 203 act as heat sources by receiving the heat of reaction, thereby reducing the overall energy consumption of the unit or method for producing PACM.

[0195] In operation of the main reactor 201 shown on the right side of the image, flow can bypass the main reactor 200 via pipelines 111, 115, and 116. In operation of the main reactor 200 shown on the left side of the image, flow can bypass the main reactor 201 via pipelines 110, 114, and 116, so that in each case there is no flow through the (crossing) pipelines 112 and 113 between the two main reactors 200 and 201. Pump 205 is installed in pipeline 116.

[0196] In the illustrated apparatus variant, heat exchangers 208 and 209 are optionally incorporated into the cooling circuits 500 and 501. These operate with a heating medium, particularly steam, and are used to preheat the main reactor 200 to the reaction temperature of the respective main reactor 200 or 201 during the start-up phase. This preheating level is approximately 80 to 100°C, ideally 85 to 95°C. In the illustrated apparatus and method examples, such as... Figure 1As has been explained, in order to achieve the smallest possible trans / trans isomer ratio of approximately 17% to 23% by weight, it is advantageous to preheat the newly filled catalyst main reactors 200, 201 to a temperature of approximately 90°C by means of their respective heat exchangers 208, 209, or to preheat the respective newly filled catalyst main reactors 200, 201 accordingly.

[0197] Preheating to a typical 85 to 95°C allows the reaction to begin immediately with the catalyst of the present invention, with little or no recycling of the mixture of materials used in the method until the desired reaction temperature is reached.

[0198] like Figure 8 The variants of the switchable main reactors 200, 201 shown are based on Figure 7 The variation differs in that the cooling circuit 500 of the first main reactor 200 is also connected in series with the cooling circuit of the second main reactor 201. In this case, only one (cooling) heat exchanger 202 and only one pump 204 are provided for this common cooling and media circulation system, so the flow rate through the common (central) pipeline branch 508 in the two cooling circuits 500, 501 is generally constant and only in one direction, regardless of the interconnection of the two main reactors 200, 201. Of course, the "central" pipeline branch does not actually need to be located between the two main reactors 200, 201 here. This variation is shown in solid lines, in which the reactant mixture is first supplied to the first main reactor 200 (left side) via pipeline 110, and the introduction of (cooling medium) downstream of the heat exchanger 202 and pump 204 is also first achieved via this main reactor 200. Pipelines that do not guide the medium or guide the mixture of substances in this interconnection are shown in dashed lines. In these variations, it is also possible that the mixture of substances and / or (cooling) medium completely bypass the corresponding other main reactor. Therefore, for example, during the filling of one of the two main reactors 200, 201, the corresponding other main reactor can continue to operate at maximum production capacity. The bypass of the material flow or the corresponding main reactor 200, 201 is similar to... Figure 7 The conclusion is as follows.

[0199] In the illustrated exemplary interconnection, fluid flows through a central pipeline branch 508 and heat exchanger 202, and is directed in parallel via pipeline 504 into the media space of the first main reactor 200, where pipeline 505 from the second main reactor 201 to the common pipeline node is blocked. The medium exits the first main reactor 202 at a low outlet via pipeline 506 and is directed to the high inlet (cross pipeline) into the media space of the second reactor 201. The medium also flows in parallel through the media space of the second main reactor 201 and exits at a low outlet via pipeline 509, whereby a branch flows back into the central pipeline branch 508, thus allowing for re-circulation through the loop. Similarly, when pipeline 504 is blocked, fluid first flows through the main reactor 201 shown on the right via pipeline 505. The medium then exits the media space of the second main reactor 201 via pipeline 509 and is directed at the high inlet into the media space of the other main reactor 200. The outlet of the medium space at the low point leads to pipeline 506, and from there it branches into the central pipeline branch 508.

[0200] A particular advantage of the switchable main reactors 200 and 201 is that the main reactor through which the fluid first passes operates at a higher temperature without significantly affecting (i.e., increasing) the possibility of the trans / trans isomer ratio, since the catalyst has already been partially depleted and deactivated. In parallel, a more significantly heated cooling medium is generated in the respective (circulating feed) heat exchangers 202 and 203 of the main reactors 200 and 201 through which the fluid first passes. Due to the higher temperature, this hotter heat exchange medium can be better used in the unit for the integrated media base EK and / or for conventional heat exchange with the reactant feed stream.

[0201] Similar to Figure 4 , Figure 5 The optional pipeline 117 is shown in the middle with a dashed line (bypass 2), which allows it to bypass the downstream reactor 210, wherein pipeline 117 branches downstream of the (feed) heat exchanger 206 of the downstream reactor 210.

[0202] Figure 5 A variation of the device (dashed line) is also shown, in which, for greater control safety or greater freedom in temperature management, switchable and controllable heat exchangers 203 (feed coolers) are arranged as needed in the corresponding (cross) lines 504 and 505 of the cooling circuits 500 and 501. In the illustrated embodiment, the two heat exchangers 202 are connected in series because no heating occurs at the installation location of the heat exchangers 202 via the corresponding inactive (cross) line, in the illustrated example, line 505. In an advantageous variation, the cooling medium lines or cooling medium circuits of the heat exchangers 202 can operate in a side flow or via a secondary or auxiliary circuit using a pump 204.

[0203] A significant advantage of this side-flow or secondary / auxiliary loop of coolant via heat exchanger 203 is that this additional cooling output only needs to be called upon as needed, and with low complexity, a high degree of closed-loop temperature control can be achieved as needed in the corresponding second of the two series-connected main reactors.

[0204] Figure 6 This illustrates a third embodiment of the device having another direct EK, as an example. Figure 1 An improved variant of the device variant shown. In the illustrated embodiment, a total of three heat exchangers are shown in an integrated material base EK. For reference Figure 1 In the figures, the " / " symbol is generally used for heat exchangers in integrated media-based EKs or integrated material-based EKs, such as condenser 304 / 158, meaning that at least a portion of the heat transfer from the previous two heat exchangers is now achieved in a single heat exchanger. The order of the reference numerals in the figures has no further significance here. Figure 6 In this example, the complete temperature rise of the material stream in (feed) line 153 is achieved, while the cooling of the material stream in line 163 may be incomplete; therefore, a heat exchanger 228 is provided as at least an optional post-condenser. This (on-demand) heat exchanger 228 downstream of condenser 304 in lines 163 and 162 can be a smaller design due to its relatively small cooling capacity. Ideally, complete heat exchange between the two material streams takes place in a single heat exchanger within an integrated material base EK. In this case, line 163 generally refers to the entire line from separator 300 to collection container 310, and line 162 refers to the section of line between condenser 304 and collection container 310.

[0205] As another integrated material-based EK, the material flow in the (top) line 347 of the third separation tower 340 is coupled to the material flow in the (feed) line 161 of the first separation tower 320 in heat exchangers 327 / 344. Similar to the variant described above, a much smaller (top) condenser 344.1 is provided at the top of the third tower 340 to ensure the necessary vapor condensation at the top of the separation tower 340. A third integrated material-based EK is implemented between the material flow in the (top) line 357 of the fourth separation tower 350 and the material flow in the (feed) line 116 of the subsequent reactor 210. This third integrated material-based EK is implemented in heat exchangers 206 / 354. The temperature level changes in the corresponding material flows proceed similarly as described above. In a similar manner to the material base EK of the second integration, a much smaller (top) condenser 354.1 is provided at the top of the fourth column 340 in the return stream to ensure, persistently or as needed, the necessary vapor condensation at the top of the separation column 350.

[0206] Figure 7 Another direct EK of the display device 100, wherein the material flow of the (top) line 163 of the separator 300 is coupled by heat exchange in the condenser 304, which is an integrated material base EK, to the material flow from the (bottom) outlet of the separator 300 via line 161. Figure 1 Unlike other systems, pressure control unit 222 is positioned upstream of condenser 304 in line 161 to control the required temperature gradient in the feed material stream to condenser 304 by depressurization. A connection downstream of condenser 304 links line 161 to the first separation tower 320. Downstream of condenser 304, a (top) line 163 connects to collection container 310. Similar to... Figure 6 Pressure control unit 227 and / or switchable heat exchanger 228 may optionally be located in (top) line 163 to ensure complete condensation of the vapor phase in lines 162, 163 upstream of collection container 310.

[0207] In this embodiment, a loop 260 can be formed for the heat exchange material stream, comprising several pipeline sections 260.n, and integrating the mixer 152, main reactor 200, post-reactor 210, and separator 300 into this heat exchange material stream or reactant stream. Furthermore, as one of the pipeline sections 260.n, a (top) pipeline 163, a (feed) pipeline 162, a (return) pipeline 311, and a (feed) pipeline 116 are integrated. The heat exchange material stream or reactant stream used is a solvent or the solvent portion of the corresponding stream.

[0208] According to the above Figure 2 Compared to incorporating a heat sink into the distributor circuit 570, this direct interconnection of the material flow and the heat distribution from the condenser 304 as an EK results in an efficiency increase of 30% to 50%.

[0209] and Figure 7 Unlike the implementation plan, Figure 8 Another EK of the display device 100, wherein the material flow in the (bottom material) line of the separation tank 300 or the (feed) line 161 of the first separation tower 320 is coupled by heat exchange to the (circulating material) heat exchanger 202 in the coolant circulation system 500 of the reactor 200. Figure 1 Different, and similar Figure 6 and Figure 7 In one embodiment, a pressure control unit 222 is positioned in line 161 upstream of the (circulating feed) heat exchanger 202 to control the required temperature gradient in the feed stream to the condenser 304 by depressurization. Line 161 is connected downstream of the (circulating feed) heat exchanger 202 to the first separation tower 320.

[0210] Figure 9 Another direct EK of the display device 100, wherein, similar to according to Figure 7 In this variant, the material flow from the (top) line 163 of the separator 300 is coupled via heat exchange in a condenser 304, which is an integrated material-based EK, to the material flow from the (bottom) outlet of the separator 300 via line 161. Upstream of the condenser 304, a pressure control unit 222 is located in line 161 to allow for pressure relief control of the desired temperature gradient in the input material flow to the condenser 304. Downstream of the condenser 304, line 161 is connected to the first separation tower 320. Downstream of the condenser 304, the (top) line 163 is connected to the collection container 310. A pressure control unit 227 and / or a switchable heat exchanger 228 may optionally be located in the (top) line 163 to ensure complete condensation of the vapor phase in lines 162, 163 upstream of the collection container 310. However, unlike... Figure 7 The (top) line 163 is not directly connected downstream to the collection container 310 via the (feed) line 162. Heat exchangers 304 / 327 are connected in series as an integrated material base EK to the (feed) line 116 of the heat exchangers 206, 304, or the post-reactor 210, which act as heat sinks, and are also connected downstream in series to heat exchangers 158 / 304 as an integrated material base EK, with the discharge line branch corresponding to the (feed) line 162 of the collection container 310. This energy interconnection for further conduction and distribution of heat energy is also shown in this variant as a heat exchange loop 260, where, for ease of understanding, the line segments 260.n of loop 260 are sequentially numbered 260.1 to 260.13. The return line 311 corresponds to line branch 260.6 and conducts the thermally conductive solvent (in this case, for example, THF) from the first separation stage 106A back to the processing unit 104. If necessary, the advantageous collection or storage tank of conditioning unit 104 may optionally be incorporated into heat exchange circuit 260.

[0211] In this embodiment, a loop 260 can be formed for the heat exchange material stream, comprising several pipeline sections 260.n, and integrating a mixer 152, a main reactor 200, a post-reactor 210, and a separator 300 into the heat exchange material stream or reactant stream. Furthermore, as one of the pipeline sections 260.n, a (top) pipeline 163, a (feed) pipeline 162, a (return) pipeline 311, and a (feed) pipeline 116 are integrated. The heat exchange material stream or reactant stream used is a solvent or the solvent portion of the corresponding stream.

[0212] It has been found that the integration of the inlet and integrated material base EK upstream of the first separation tower 320 into the heat exchanger 327 is particularly surprising and advantageous because, according to the pressure control unit 222, the separation tower can operate at a very low pressure level of approximately 1.1 bar to 2 bar in line 161, thus resulting in a very low temperature level of the material flow to the heat exchanger 327, approximately 90°C. This makes it possible to absorb a relatively large amount of heat in the energy coupling and save cooling power; furthermore, the energy demand of the bottom loop of the first separation tower 320 is almost linear. In the case of the integrated material base EK, it is possible to save, for example, based on the total energy demand of the second separation tower 320.

[0213] - Approximately 31% in heat exchangers 327 / 344

[0214] - Approximately 62% in heat exchangers 327 / 354

[0215] - Approximately 21% in condensers 327 / 304, and / or

[0216] - Approximately 12% in (circulating feed) heat exchangers 327 / 202.

[0217] Figure 10 Display similar to Figure 2 , 3 This is a variant implementation or variation. In this case, the heat loop 240 is designed for the series interconnection of heat exchangers of the integrated medium-based EK. In this case, the condenser 304 acts as the central heat source, and the (feed) heat exchanger 327 in (feed) line 311, the (feed) heat exchanger 206 in (feed) line 116, and the heat exchanger 158 in (feed) line 153 are connected via n line segments 240.n. For example, the heat exchange medium used is water circulating in line segment 240.n. The line segments of heat exchange loop 240 and the line segments of the aforementioned heat exchange loops 250 and 260 are characterized in that the temperature level and / or pressure level in the nth line segment is different from that in line segment n-1 (upstream) and / or line segment n+1 (downstream). In the embodiments and variations shown herein, the pipeline sections shown and / or illustrated are given as examples, and other pipeline sections can be provided based on their respective requirements, especially when additional heat exchangers are similarly incorporated into the heat exchange loops 240, 250, 260 as heat sinks and / or as heat sources.

[0218] In this variant of the illustrated device 100, in pipeline sections 240.4, 240.5, a pressure control unit 244 and a heat exchanger 246 operating as a heat sink are arranged upstream of the condenser 304 to ensure the required cooling / condensing power of the condenser 304.

[0219] at last, Figure 11 The embodiments correspond to the basic design of the embodiments. Figure 10 Unlike the previous method, the condenser 304 downstream of the separator 310 does not serve as the central heat source for the heat exchange loop 240; instead, it is the (circulating feed) heat exchanger 202 of the reactor 200. Similarly, the pressure control unit 244 and the heat exchanger 246, which functions as a (cooling) heat sink, are arranged upstream of the (circulating feed) heat exchanger 202 in the transition section from pipeline section 240.4 to the final pipeline section 240.5 to ensure the required cooling power of the (circulating feed) heat exchanger 202 and thus enable optimal control of the reactor 200.

[0220] A significant advantage of the (distributor) loop 240 is that a central steam loop is formed, so steam can be centrally generated, for example, in the condenser 304, and distributed to all heat exchangers operating as consumable devices (heat sinks), rather than directly interconnecting heat sources and heat sinks. Furthermore, if needed (e.g., during startup), the distributor loop, as the central steam loop, can be supplied at least temporarily by means of an alternative heat source or steam source.

[0221] This document primarily describes the (feed) heat exchanger 206, which is shown in some cases in the EK, where it primarily functions as a heat sink, meaning the material stream conducted within it is heated. Due to the dependent operating mode of the downstream reactor 210, adapted to the main reactors 200, 201, cooling of the material stream in the (feed) line 116 upstream of the downstream reactor 210 may be necessary, at least temporarily and particularly persistently, as approximately 10% to 20% of the conversion occurs in the (adiabatic) downstream reactor, such that the material stream is heated to approximately 140°C at the outlet. Therefore, embodiments and variations of the apparatus and methods described herein can provide an EK adapted for cooling (with the heat exchanger 206 operating as a heat source). Alternatively or additionally, auxiliary cooling can be provided by a modified or additional EK.

[0222] In general, many conventional open-loop and closed-loop control elements known to those skilled in the art and necessary or desirable for advantageous methodologies, such as sensors (flow, temperature, pressure, etc.), displays, regulating and control elements (especially valves, additional pumps, compressors), collection containers, etc., are not shown, and may be supplemented as needed. In particular, when referring to “one” pump or “one” compressor, this also means a conventional redundant design from at least two parallel units, especially two parallel pumps or two parallel compressors. In a similar manner, “one heat exchanger” should not be construed as limiting, and for the corresponding local heat exchange function, it also refers to the arrangement of heat exchangers connected in series or in parallel, including redundant heat exchangers, which here does not imply interconnection with at least one other heat exchanger and locally different heat exchange functions.

[0223] Unless otherwise stated, all heat exchangers and condensers are designed in principle to allow indirect heat transfer without physical mixing of reactants, products, byproducts and / or solvents with the (heating / cooling) medium (such as gas, steam, water, oil, brine, etc.).

[0224] Even if components such as valves, pressure control units, and isolators are shown individually or separately in this document for the sake of simplicity, and are not mentioned separately in some cases, this should not be interpreted in a restrictive manner; rather, those skilled in the art can combine two or more of these components in a valve unit or control unit as needed, or instead provide a multi-way valve.

[0225] Because EK's media flow, reactant flow, and material flow are taken into account, the terms "upstream" or "downstream" can only be interpreted from their respective contexts.

[0226] The terms “bottom effluent,” “bottom output,” “bottom discharge,” or “bottom discharge” are used synonymously in some cases, and similarly, the terms “top effluent,” “output,” “discharge,” or “outlet” are also used synonymously in some cases.

[0227] Furthermore, the phrase "heat exchanger operating as a condenser" should be interpreted broadly, and also refers to the incomplete condensation or cooling of the supplied material stream. Therefore, "heat exchanger operating as a condenser" is sometimes also synonymously named "condenser".

[0228] The term "bottom pump" refers to a pump incorporated into the bottom circulation system of equipment (separation tower, container, etc.) and / or a pump downstream of the bottom outlet of the equipment, providing it for conveying the liquid material stream.

[0229] In addition to the examples shown in this paper, it has been found to be generally surprisingly advantageous and effective to provide an infeed heat exchanger in the feed line of the first separation tower of the first separation stage downstream of the depressurization unit, and this is advantageously provided in EK, especially in integrated EK.

[0230] In all embodiments and variations of this apparatus and method, it is generally likely that the second separation tower 340 and the third separation tower 350 are implemented as a single tower, particularly as a partition wall tower (not shown). In this case, the separation function of the second separation tower 340 and the third separation tower 350 can advantageously be implemented at least partially, ideally entirely, by means of a partition wall tower (not shown) as known, for example, from documents EP012 62 88B1 or EP 012 23 67A2.

[0231] In summary, the apparatus and method according to the invention can achieve great energy advantages, namely, the ability to significantly reduce the energy flow supplied from the outside, and in particular, to save a large amount of (external) heating steam.

Claims

1. An apparatus (100) for the catalytic hydrogenation of methylenediphenylamine (MDA; reactant 1) using a hydrogen donor (reactant 2), particularly a gaseous hydrogen donor, preferably hydrogen (H2). It includes a reactant conditioning unit (104), a reactor unit (102), and a separation unit (106), wherein - The conditioning unit (104) includes a (feed) line for reactant 1, reactant 2 and at least one solvent, at least one heat exchanger (158) in at least one (feed) line, and at least one mixer (152) for mixing the reactant and / or at least one reactant with at least one solvent. - The reactor unit (102) includes at least one fixed-bed reactor as a main reactor (200, 201) with a fixed catalyst packing, wherein the at least one (first) main reactor (200, 201) includes - For supplying the mixture of substances through the fixed catalyst packing, and -Other flow paths, and The additional flow path is incorporated with a heat exchanger (202) for influencing the temperature level in the first flow path; -The separation unit (106) includes at least - A first separation stage (106A) comprising at least one device (300, 320) for separating and removing solvent, wherein the at least one device (300, 320) is downstream connected to at least one condenser (304) via at least one (top) line (163), and - A second separation stage (106B) comprising at least one device (340, 350, 360) for separating at least one reactant and / or at least one byproduct from the product, wherein said at least one device (340, 350, 360) is downstream connected to at least one condenser (344, 354) via at least one (top) line. Its features The additional flow path is a closed medium circulation system (500) for heat transfer medium, which extends at least in one section outside the catalyst packing of the at least one main reactor (200) for indirect heat transfer, wherein a heat exchanger (202) is incorporated in the medium circulation system (500).

2. The apparatus according to any one of the preceding claims, characterized in that... The reactor unit (102) includes at least one downstream reactor (210) connected in series downstream of the at least one main reactor (200), wherein the at least one main reactor (200) and the at least one downstream reactor (210) are connected via a pipeline (116), particularly a pipeline (116) incorporating a heat exchanger (206).

3. The apparatus according to claim 1 or 2, characterized in that... Provide at least one energy coupling (EK) incorporating at least one of the following heat exchangers: -The at least one condenser (304) of the first separation stage (106A), -The at least one condenser (344, 354) of the second separation stage (106B), -The at least one heat exchanger (202) of the medium circulation system (500), And the EK mentioned therein refers to the following meanings: i) Material-based energy coupling (integrated material-based EK) in indirect heat exchange of at least two material streams in a heat exchanger; ii) At least two heat exchange media are integrated in the heat exchanger in indirect heat exchange with media-based energy coupling (integrated media-based EK); iii) Series interconnection of two heat exchangers in dielectric-based energy coupling (series dielectric-based EK), where - In the series interconnection of the first heat exchanger with the first material stream in an integrated media base EK or more generally EK, the (heat exchange) medium is further conveyed to a second downstream heat exchanger for use with another integrated media base EK or more generally EK of another material stream.

4. The apparatus according to claim 3, characterized in that... The device (100) includes the following: iv) At least one of the two heat exchangers is interconnected in series to form an integrated material base EK (referred to as "tandem integrated material base EK"), wherein the material flow from the first heat exchanger in the integrated material base EK is further conveyed in the tandem interconnect to a second downstream heat exchanger for use in another integrated material base EK.

5. The apparatus according to claim 3 or 4, characterized in that... According to iii), at least one tandem dielectric base energy coupling or according to iv), a tandem integrated dielectric base EK is designed as a loop, especially as a closed loop.

6. The apparatus according to any one of claims 3 to 5, characterized in that... At least one of the following pipelines is incorporated into the condenser (304) of the (top) pipeline (163) of the separator (300) as a heat source for the integrated material-based EK: i) The (feed) line (153) leading to the main reactor (200), ii) The feed line (116) leading to the post-reactor (210), iii) A feed line (161) leading to the first separation tower (320), wherein a pressure control unit (222) is located in the feed line (161) upstream of the condenser (304). iv) At least one additional heat exchanger of material-based EK for integration is incorporated in the condenser (304) downstream of the pipeline junction according to i), ii) or iii) and upstream of the collection container (310).

7. The apparatus according to any one of the preceding claims, characterized in that... The device (100) comprises a medium base EK in series as a loop (260) having multiple pipeline sections (260.n), wherein at least the following devices and / or pipelines are incorporated: a collection container (310) downstream of the separator (300), a (top) pipeline (163) as a pipeline section (260.1), particularly the first pipeline section (260.1), and a (feed) pipeline (162) leading to the separator (310) as another pipeline section (260.5), particularly the last pipeline section (260.5).

8. The apparatus according to claim 7, characterized in that... The condenser (304) of claim 6 (alternative iii) is in an integrated material base EK and incorporated into the circuit (260).

9. The apparatus according to any one of claims 3 to 8, characterized in that... The medium circulation system (500) of the main reactor (200) is integrated into the heat exchanger (202) as a heat source together with the (feed) line (161) leading to the first separation tower (320) to form EK, wherein the pressure control unit (222) is located in the (bottom) line (161) upstream of the heat exchanger (202).

10. The apparatus according to any one of claims 3 to 9, characterized in that... At least one of the following pipelines is incorporated as a heat source for the integrated material-based EK into the condenser (344, 354) of the separation tower (340, 350) of the second separation stage (106B) in the corresponding (top) pipelines (234, 236): i) The (feed) line (153) leading to the main reactor (200), ii) The feed line (116) leading to the post-reactor (210), iii) A feed line (161) leading to the first separation tower (320) of the first separation stage (106B), wherein a pressure control unit (222) is located in the feed line (161) upstream of the condenser (344, 354) of the respective separation tower (340, 350).

11. The apparatus according to any one of the preceding claims, characterized in that... At least one direct medium line (230, 232, 234) is provided between the heat exchangers for direct energy coupling (direct EK): i) The condenser (304) of the separation unit (106) serves as a heat source for at least one heat exchanger of the reactor unit (102), the conditioning unit (104), and / or the separation unit (106). ii) A heat exchanger (202) of a media circulation system (500) leading to the main reactor (200) of reactor unit (102), which serves as a heat source for at least one heat exchanger of reactor unit (102), conditioning unit (104), and / or separation unit (106). and / or iii) Heat exchangers between reactor unit (102), conditioning unit (104) and / or separation unit (106), one above the other.

12. The apparatus according to claim 11, characterized in that... Media lines for direct EK: i) A heat exchanger from the condenser (304) of the separation tank (300) of the separation unit (106) as a heat source to at least one of the following heat exchangers in the reactor unit (102), the conditioning unit (104), or the separation unit (106): -In the heat exchanger (158) in the (feed) line (153) leading to the main reactor (200) and / or in the equipment (152, 154) located upstream of the main reactor (200), especially the mixer (152) or saturator (154), -In the heat exchanger (206) in the (feed) line (116) leading to the post-reactor (210) and / or - A heat exchanger (327) in the (feed) line leading to the first separation tower of the separation unit, wherein at least two of the heat exchangers (158, 206, 327) may be connected in parallel with each other; ii) A heat exchanger (202) serving as a heat source in the reactor (200) provides access to at least one of the following heat exchangers: -In the heat exchanger (158) in the (feed) line (153) leading to the main reactor (200) and / or in the equipment (152, 154) located upstream of the main reactor (200), especially the mixer (152) or saturator (154), - A heat exchanger (327) in the (feed) line (161) leading to the first separation tower (320) of the separation unit (106), wherein at least two of the heat exchangers (158, 206, 327) may be connected in parallel with each other; and / or iii) A heat exchanger (for cooling) in one of the top circulation systems of the separation tower of the separation unit (106) leads to at least one downstream (for heating) heat exchanger in the feed or bottom circulation system of the equipment of the separation unit (106), especially -From the heat exchangers (344, 354) of the separation towers (340, 350) to -The heat exchanger (327) in the (feed) line (161) leading to the first separation tower (320), - A heat exchanger (302) in the bottom circulation system of the separation tank (300) from the condenser (344, 354) in the top loop of the separation tower (340, 350) which serves as a heat source.

13. The apparatus according to any one of the preceding claims, characterized in that... The separation unit (106) in the first separation stage (106A) includes at least one pressure control unit (220) and a condensation unit (304) for solvent in the (feed) line (211) leading to the separation tank (300), wherein the (return) line (311) for solvent is led from the at least one condensation unit (304) of the first separation stage (106A) to the conditioning unit (104).

14. The apparatus according to any one of the preceding claims, characterized in that... The reactor unit includes another main reactor (201) in the form of a fixed-bed reactor, which includes -The first flow path for the reaction mixture, and -As an additional flow path for the medium circulation system (501) used for heat exchange medium, Furthermore, the valve unit provided in the (feed) line upstream of the two main reactors (200, 201) allows the volumetric flow rate of the reactant mixture to be divisible, conductable, and / or fully switchable between the first main reactor (200) and the other main reactor (201) by means of the valve unit, and wherein... Two main reactors (200, 201) -Each is connected to a heat exchanger (202, 203) or -With shared heat exchanger (203) It is connected using an alternative flow path (medium circulation system).

15. The apparatus according to any one of the preceding claims, characterized in that... The material-based EK comprises at least one heat exchange loop (250, 260) in the form of a series-integrated system of multiple pipeline sections (250.1…250.10; 260.1…260.13), wherein at least the following devices and heat exchangers are incorporated and connected via at least one pipeline section (250.1…250.10; 260.1…260.13). i) As a heat exchanger and as a heat source for heat exchange loops (250, 260) -The (circulating feed) heat exchanger (202) of the main reactor (200, 201), or - In the (top) pipeline (163) of the separator (300), the (top) heat exchanger (304 / 327) is integrated with at least one of the following pipelines that conduct reactant or material flow as heat sinks in the heat exchange loop (250, 260) on an integrated material base EK: a) The (feed) line (161) downstream of the pressure control unit (222) leading to the first separation tower (320), b) The feed line (116) leading to the downstream reactor (210), particularly on the suction side of the pump (205) into which it is incorporated. c) The (feed) line (153) upstream of the reactor (200), especially the mixing vessel (154) located upstream thereupon, or the (return) line (311) upstream of the mixer (152) leading to the conditioning unit (104); ii) As equipment, at least a main reactor (200), particularly the main reactor (200) and the downstream reactor (210), at least one separation tank (300), at least one collection vessel (310) of the first separation stage (106A), and wherein iii) The following pipeline sections are integrated as part of the loop (250, 260): a) The (first) pipeline section (250.1, 260.1) corresponding to the (top) pipeline (163) of the at least one separation tank (300) and / or b) The (final) pipeline section (250.12, 260.5) corresponding to the (feed) pipeline (162) leading to the at least one collection tank (310).

16. A method for the catalytic hydrogenation of methylenediphenylamine (MDA; reactant 1) using a hydrogen donor (reactant 2), particularly a gaseous hydrogen donor, preferably hydrogen (H2), wherein the production process is carried out using an industrial unit (100). Its features The apparatus (100) is designed according to at least one of the preceding apparatus claims, wherein the main reactor (200) operates at a temperature in the range of 80°C to 150°C, particularly isothermal operation, and wherein EK is used: i) By means of integrated energy coupling (integrated EK) or direct energy coupling (direct EK), energy is transferred from the condenser (304) of the separation unit (106) as a heat source for at least one heat exchanger of the reactor unit (102), the conditioning unit (104) and / or the separation unit (106) in the range of 5% to 100% of the available heat, especially in the range of 20% to 40%; ii) The heat exchanger (202) of the media circulation system of the main reactor (200) of reactor unit (102) transfers energy as a heat source for at least one heat exchanger of reactor unit (102), conditioning unit (104) and / or separation unit (106) in the range of 5% to 30% of the available heat, particularly in the range of 10% to 20%, via integrated EK or direct EK, and / or iii) The heat exchangers of the separation unit (106) transfer energy between each other via integrated EK or direct EK in the range of 5% to 100% of the available heat, especially in the range of 30% to 90%.

17. The method according to claim 16, characterized in that... The temperature of the reactant flow at the inlet of the main reactors (200, 201) is 90 to 140°C, ideally 100 to 135°C.

18. The method according to any one of the preceding claims, characterized in that... It is carried out continuously and catalytically for the production of methylenebis(cyclohexylamine), especially for the production of 4,4'-diaminodicyclohexylmethane (PACM), preferably 4,4'-diaminodicyclohexylmethane (PACM) with a low trans / trans isomer ratio.

19. The method according to any one of the preceding claims, characterized in that... The at least one main reactor (200) operates at a pressure in the range of 60 bar to 120 bar, ideally in the range of 70 to 110 bar.

20. The method according to any one of the preceding claims, characterized in that... In addition to the at least one main reactor (200), at least one post-reactor (210) containing a fixed catalyst is provided, wherein the at least one main reactor (200) and the at least one post-reactor (210) operate at the same or substantially the same pressure.

21. The method according to any one of the preceding claims, characterized in that... From time point t0, i.e., the start of the method after catalyst renewal or regeneration, until time point t4, i.e., the end of the method determined by catalyst renewal or regeneration, the operating temperature of the main reactor (200) is increased, and the temperature of the material flow at the inlet (feed) of the downstream reactor (210) is maintained or decreased, wherein the increase or decrease in temperature is linear and / or gradual.

22. The method according to any one of the preceding claims, characterized in that... The MDA (reactant 1) comprises a mixture of the following monomers: 4,4'MDA, 2,4'MDA and 2,2'MDA, wherein the proportion of 4,4'MDA is advantageously in the range of 75 to 98 mol%, ideally in the range of 85 to 95 mol%.

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