Hydrogenation process and reaction system therefor

Abstract

In a first aspect, the present invention relates to a hydrogenation process for hydrogenating a compound, the hydrogenation process comprising reacting the compound in a liquid medium with hydrogen in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst, the process comprising: (i) transferring at least a portion of the thermal energy generated in the reaction vessel to a cooling medium, a cooling medium stream CMS1, preferably a cooling medium stream CMS1, obtaining a cooling medium stream CMS2 having an increased thermal energy content compared to CMS1; and (ii) transferring at least a portion of the thermal energy contained in the cooling medium stream CMS2 to the heat transfer medium stream HTMS1 in the heat pump HP, thereby obtaining a heat transfer medium stream HTMS2 having an increased thermal energy content compared to HTMS1. A second aspect of the invention relates to a reaction system for hydrogenating a compound, preferably for converting a compound having at least one nitro group into a corresponding compound having at least one amino group by hydrogenation.

Description

[0001] In a first aspect, the present invention relates to a hydrogenation process for hydrogenating a compound, the hydrogenation process comprising reacting the compound with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst, the process comprising: (i) transferring at least a portion of the heat energy generated in the reaction vessel to a cooling medium, preferably a cooling medium stream CMS1, to obtain a cooling medium stream CMS2 having an increased heat energy content compared to CMS1; and (ii) transferring at least a portion of the heat energy contained in the cooling medium stream CMS2 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2 having an increased heat energy content compared to HTMS1. A second aspect of the present invention relates to a reaction system for hydrogenating a compound, preferably for converting a compound having at least one nitro group into a corresponding compound having at least one amino group by hydrogenation.

[0002] Hydrogenation is a reaction used in many application areas. The reaction is characterized by the use of hydrogen, which serves as a reducing agent for the substrate, and usually additionally a catalyst is used. Common reactants used in hydrogenation reactions are, for example, olefins, alkynes, aldehydes, ketones, esters, carboxylic acids, and compounds having nitro groups. Starting from the compound having a nitro group, dinitrotoluene is commonly used in hydrogenation reactions because the corresponding reaction product toluenediamine is a precursor of toluene diisocyanate, which in turn is a relevant isocyanate monomer in the preparation of polyurethanes.

[0003] In the prior art, toluenediamine is prepared by hydrogenation of dinitrotoluene, where the reaction is strongly exothermic and releases a large amount of heat energy. This reaction heat must be removed, otherwise the reaction cannot be carried out in a controlled manner for an extended period of time. A commonly used device for removing the reaction heat is a cooling system, which typically uses water as the cooling medium. In one or more cooling coils, the reaction heat is removed, and then, for example, the cooling medium is disposed of because the cooling water is ultimately discharged into the water. Especially nowadays, there is an overall demand for energy-efficient systems, that is, systems that can use the generated energy for meaningful purposes without wasting it. Since steam, especially water steam, is an effective energy carrier used in many industrial processes, it is possible to consider transferring the reaction heat of the hydrogenation reaction to steam.

[0004] Reactor settings for the hydrogenation of dinitrotoluene are described in the art. For example, WO 00 / 30743A1 discloses a reactor with a cylindrical configuration for continuously conducting solid-gas-liquid, liquid-liquid, or gas-liquid reactions. The reactor has downwardly directed jet nozzles arranged in the upper reactor region, through which starting materials and reaction mixtures are fed, and preferably has an outlet in the lower reactor region, through which the jet nozzles are fed. A continuous method for conducting gas-liquid or gas-liquid-solid reactions in this reactor is further described.

[0005] WO 00 / 35852A1 relates to a method for preparing amines by hydrogenating nitro compounds, which is characterized in that the hydrogenation is carried out in a vertical reactor with a length greater than the diameter. The reactor has downwardly directed jet nozzles arranged in the upper region of the reactor, through which feed materials and reaction mixtures are fed, and has an outlet at any point in the reactor, through which the reaction mixture is fed back into the reactor in an external circuit.

[0006] However, the reaction temperature in most existing reactor settings is not high enough to be effectively used, for example, to generate steam of a higher grade that can be economically utilized.

[0007] Therefore, the fundamental problem of the present invention is to provide a method that overcomes the deficiencies of the prior art, in particular, to provide a method and reaction system for more effectively recovering reaction heat from hydrogenation, for example, by providing steam of a sufficiently high grade.

[0008] First aspect - Hydrogenation method

[0009] In a first aspect, the present invention relates to a hydrogenation method for hydrogenating a compound, which includes reacting the compound with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst. The method includes

[0010] (i) transferring at least a part of the thermal energy generated in the reaction vessel to a cooling medium, preferably the cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased thermal energy content compared to CMS1;

[0011] (ii) transferring at least a part of the thermal energy contained in the cooling medium stream CMS2 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

[0012] In some preferred embodiments, the hydrogenation process is a process for hydrogenating a compound having at least one nitro group to the corresponding compound having at least one amino group, the process comprising reacting the compound having at least one nitro group with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst.

[0013] As indicated in further detail below, the hydrogenation process allows for a favorable energy balance since at least 20% of the heat energy generated in the reaction vessel is transferred to the heat transfer medium via a cooling medium and a heat pump. In embodiments where the heat pump is an absorption heat pump, preferably a class II absorption heat pump, between 20% and 50% of the heat energy generated in the reaction vessel is transferred to the heat transfer medium via a cooling medium and a heat pump. In an alternative embodiment where the heat pump is a compression heat pump, preferably a steam-generating compression heat pump (steam generator), between 20% and 100%, preferably between 70% and 100%, of the heat energy generated in the reaction vessel is transferred to the heat transfer medium via a cooling medium and a heat pump.

[0014] Heat pump

[0015] In some preferred embodiments of the hydrogenation process, the heat pump of (ii) is an absorption heat pump (preferably a class II absorption heat pump), or a compression heat pump, and more preferably the heat pump of (ii) is a class II absorption heat pump.

[0016] Absorption heat pump

[0017] Absorption heat pumps offer the opportunity to upgrade low- or medium-temperature heat sources to useful temperature levels. Thus, absorption heat pumps use low- or medium-temperature heat sources as driving heat sources and utilize the effect of heat absorption to increase the temperature level. In the field of absorption heat pumps, there are Type-I heat pumps and Type-II heat pumps, with the latter also being known as absorption heat transformers. In Type-I heat pumps, the condenser temperature is higher than the evaporator temperature. The absorption heat pump extracts the heat of waste heat and outputs a medium-temperature heating medium (preferably water) that is higher than the waste heat. Typically, the heating medium is heated to a temperature range that is 30°C to 60°C higher than the waste heat temperature, or a heating medium with a temperature in the range of 60°C to 95°C is provided. In Type-II heat pumps, the condenser temperature is lower than the evaporator temperature. The Type-II absorption heat pump intelligently uses the heat of medium-temperature waste heat and outputs a high-temperature heat medium (preferably steam) that is 25°C to 50°C higher than the medium-temperature waste heat. The absorption heat pump converts the heating medium (preferably water) into steam and provides steam with a temperature higher than 100°C. Thus, the Type-II absorption heat pump upgrades a portion of the heat from the heat source to a higher temperature level as useful heat while discharging the remaining low-temperature heat to a radiator (such as ambient air, cooling water). It is possible to upgrade up to 50% of the available waste heat. The absorption heat pump includes one or more stages, with more than one stage being used to achieve a wider temperature range. To obtain a greater temperature lift (>50K), a heat pump with a higher number of stages must be used. As the temperature lift increases, the amount of energy that can be upgraded decreases. For example, for a much higher temperature lift, a three-stage water / LiBr absorption heat pump can be used to achieve a temperature lift of up to 145K by upgrading approximately 20% of the available waste heat.

[0018] Absorption heat pumps are based on the use of a pair of working fluids. One working fluid serves as the refrigerant and the other as the solvent. The refrigerant must always have a higher vapor pressure since when the refrigerant is discharged in the generator, the solvent should remain in the liquid phase. Possible working fluid pairs are: water / lithium bromide (LiBr) (water as the refrigerant), ammonia / water (ammonia as the refrigerant), ammonia / lithium nitrate (LiNO3), and ammonia / sodium thiocyanate, ammonia / ionic liquid, water / ionic liquid, methanol or ethanol / ionic liquid, and trifluoroethanol / tetraethylene glycol dimethyl ether. In the context of the present invention, preferably, class II absorption heat pumps use a working fluid pair of water and LiBr, where water acts as the refrigerant. The operating principle of the absorption heat converter is that the driving heat flow (in the current case, the thermal energy from the cooling medium stream CMS2 (or CMS4, or the combined stream of CSM2 and CSM5, see further details below)) is absorbed in the generator and the evaporator, and then the cooling medium stream CMS3 with a reduced thermal energy content compared to CMS2 leaves the generator. The refrigerant evaporates at an elevated pressure in the evaporator and is then fed to the absorber, where the refrigerant is absorbed by the solvent. The resulting mixture expands via a throttle valve and is fed to the generator. There, the solvent is discharged at a lower pressure by the driving heat. The solvent is restored to an increased pressure via a pump and fed to the absorber. In many cases, it is preheated via a heat exchanger by the heat of the mixed stream leaving the absorber. The discharged refrigerant is fed to the condenser. There, due to the low pressure, it condenses at a significantly lower temperature. Then, the liquid refrigerant is restored to a higher pressure via a second pump and fed to the evaporator. The available heat supplied by the heat converter is the heat of solution of the refrigerant in the solvent released in the absorber, which is transferred to the heat transfer medium stream HTMS1, thereby obtaining the heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

[0019] Compression heat pump

[0020] Compression heat pumps offer the opportunity to upgrade low or medium temperature heat sources to useful temperature levels. Compression heat pumps thus use mechanical work as the driving source to raise the temperature level. (Electrically driven) Compression pumps operate with a closed refrigerant circuit, where the refrigerant is selected from the group consisting of: ammonia, water, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroolefins, hydrochlorofluoroolefins, hydrocarbons, perfluoro(2-methyl-3-pentanone), and mixtures of two or more thereof. Gaseous refrigerants are also suitable, such as carbon dioxide or other gases. Suitable refrigerants are known to the person skilled in the art and are disclosed, for example, in: C. Arpagaus et al. (C. Arpagaus et al., Energy 152 (2018), pages 985 to 1010). In the case of liquid refrigerants, the initial liquid refrigerant enters the evaporator. In the region of the evaporator, the pressure is kept low by the compressor, typically at a pressure in the range of 0 bar to 30 bar, such that the refrigerant boils and thus evaporates. During this process, the refrigerant cools due to the required heat of vaporization. Since the evaporator is designed as a heat exchanger, i.e., it allows the refrigerant to exchange heat with an external medium (here the warm cooling medium flow CMS2 (or CMS4, or the combined flow of CSM2 and CSM5, details are further described below)), the thermal energy (heat) now flows from the cooling medium flow CMS2 into the refrigerant, which significantly reduces the cooling of the refrigerant and promotes further evaporation. The cooling medium flow CMS3 with a reduced thermal energy content compared to CMS2 then leaves the region of the evaporator. The evaporated refrigerant is initially slightly colder than the cooling medium flow CMS2 (cold in the range of 2 K to 40 K, preferably in the range of 5 K to 20 K). The refrigerant then passes through a compressor (e.g., a screw compressor, a scroll compressor, a piston compressor, or a turbo compressor), which brings the refrigerant to a much higher pressure, typically a pressure in the range of 1 bar to 100 bar, which also causes the temperature of the refrigerant to rise. The refrigerant is then forced to condense again in a second heat exchanger (condenser). There, the refrigerant releases thermal energy (mainly the heat of condensation) at a higher temperature, which is transferred to the heat transfer medium flow HTMS1, thereby obtaining a heat transfer medium flow HTMS2, which has an increased thermal energy content compared to HTMS1. Despite the higher temperature in the condenser, condensation is possible due to the increased pressure of the compressor. The condensed refrigerant is depressurized by an expansion valve and sent back to the evaporator as a liquid refrigerant. In the case of gaseous refrigerants, the same principle applies, but only with the increase or decrease of the temperature of the gaseous refrigerant without changing the state of aggregation. In the gaseous case, the gas-cooled refrigerant is depressurized by an expansion valve or an expansion turbine and sent back to the evaporator as a partially or fully supercritical medium (e.g., a gas such as carbon dioxide).

[0021] For completeness, it must be noted that in this text, the pressure indicated by "barg" is related to the gauge pressure. Since the gauge pressure is measured relative to the ambient pressure, each pressure value (or range) indicated by barg is equal to the absolute pressure minus the atmospheric pressure. "bara" means the absolute pressure in bar.

[0022] The heat pump is characterized by its coefficient of performance (COP) and its quality grade eta.

[0023] The COP is calculated based on Equation (I)

[0024] COP = Q / W (I)

[0025] where "Q" is the heat transferred to the heat transfer medium (available heat: HTMS2 – HTMS1), and "W" is the work of the compressor (consumed work, electrical energy) or the driving heat.

[0026] The quality grade eta is calculated based on Equation (II)

[0027] eta = COP HP / COP 卡诺 (II),

[0028] where COP HP is the coefficient of performance of the heat pump, and COP 卡诺 is the ideal coefficient of performance calculated based on the Carnot process.

[0029] The method of the present invention is capable of achieving a COP in the range of 1 to 8, preferably in the range of 1.2 to 7.5 HP , and a quality grade eta in the range of 30% to 65%, depending on the type of compressor used (piston compressor, screw compressor, turbo compressor).

[0030] Heat transfer medium

[0031] In some embodiments of the hydrogenation method, the heat transfer medium comprises water, preferably at least 90% by weight, more preferably at least 95% by weight, even more preferably at least 99% by weight, of the heat transfer medium being water, each based on the total weight of the heat transfer medium being 100% by weight. In some embodiments of the hydrogenation method, at least 90% by weight of the heat transfer medium stream HTMS1 is liquid, and at least 90% by weight of the heat transfer medium stream HTMS2 is gaseous (H2O 气态, water vapor). The temperature T1 of the heat transfer medium stream HTMS1 entering the heat pump HP is preferably in the range of >0°C to 140°C, more preferably in the range of 20°C to 140°C, and even more preferably in the range of 90°C to 120°C. HTMS1 has a pressure p1, which is ≥p2, where the value of p1 and the absolute value of the difference between p1 and p2 depend on the reaction equipment, the setting and layout of the pipelines, etc., which are familiar to those skilled in the art.

[0032] In some embodiments of the hydrogenation process, the heat transfer medium stream HTMS2 has a pressure p2 in the range of 0 barg to 20 barg, preferably in the range of 0.1 barg to 10 barg. The heat transfer medium stream HTMS2 preferably has a temperature T2, which is equal to or greater than the temperature of the heat transfer medium at the boiling point under the pressure p2 (T BP ).

[0033] In some embodiments of the hydrogenation process, the heat transfer medium stream HTMS2 having a pressure p2 is preferably compressed by mechanical compression to obtain a heat transfer medium stream HTMS2-1 having an increased pressure p 2-1 compared to p2, where p 2-1 is preferably a pressure in the range of 3 barg to 40 barg. The heat transfer medium stream HTMS2-1 preferably has a temperature T 2-1 , which is > = the temperature of the heat transfer medium at the boiling point under the pressure p 2-1 +3K (T BP ).

[0034] Especially if the heat transfer medium stream HTMS2 has a low pressure, for example, it is a water vapor stream having a pressure p2 in the range of 0 barg to 8 barg, it is advantageous to compress it by an additional mechanical steam compressor to pressurize the steam to a pressure p 2-1 in the range of p1 + 4 barg to 40 barg. Even though the additional mechanical compression requires additional power input, the overall energy balance is still favorable.

[0035] In some preferred embodiments, each of HTMS2 and / or HTMS2-1 is partially or fully used for heating during the reaction process, including reaching and / or maintaining the temperature required for the reaction in the reaction vessel, and / or for heating in another process, which is preferably a process before or after the preparation of a compound having at least one amino group, more preferably a subsequent process in which a compound having at least one amino group is converted into a compound having at least one isocyanate group, or a previous process in which a compound containing at least one nitro group is generated. In addition, the generated steam can be used for heating in the steam network of other production plants, or can be sold to a third party.

[0036] Cooling medium

[0037] In some embodiments of the hydrogenation process, the cooling medium is selected from the group consisting of water, air, solvents, and mixtures of two or more thereof, wherein the cooling medium preferably contains water, preferably at least 90 wt%, more preferably at least 95 wt%, more preferably at least 99 wt% of the heat transfer medium is water, each based on the total weight of the cooling medium being 100 wt%. In the context of the cooling medium, the solvent means any solvent having the same boiling conditions, in particular the same boiling point, as the solvent used in the reaction mixture, where "same" includes a deviation of ±5%. For example, if a C1 to C6 monohydric alcohol (especially ethanol and / or propanol, preferably isopropanol) is used as the solvent in the reaction mixture, the solvent having the same boiling conditions means a solvent having a boiling point in the range of 78°C to 86°C at 1013 mbar.

[0038] Heat exchanger - (main) cooling system

[0039] In some embodiments of the hydrogenation process, in (i) at least a part of the thermal energy generated in the reaction vessel is transferred to the cooling medium stream CMS1 by using a cooling system, which includes a heat exchanger arranged inside the reaction vessel or at least partially surrounding the reaction vessel and a circulation line for introducing CMS1 into the heat exchanger and for removing CMS2 from the heat exchanger. A heat exchanger is a device for transferring thermal energy from one material stream to another. Although direct exchangers are known to those skilled in the art, the heat exchanger in the context of the present invention is preferably a heat exchanger in which the material streams do not directly contact each other but are spatially separated, such that only the exchange of thermal energy is possible. Heat exchangers are generally known, and a suitable heat exchanger for arranging inside the reaction vessel can be, for example, a tube through which the cooling medium stream flows, the direction of which is preferably parallel to the reactor wall, a plate heat exchanger preferably extending parallel to the reactor wall can be used, or a double-lined tube "tube-in-tube" closed at the bottom, so-called field tube can also be used. For any heat exchanger including at least two spatially separated but thermally contacting compartments, which material stream flows through which compartment or in which compartment is interchangeable.

[0040] In some embodiments of the hydrogenation process, in (ii) at least a part of the thermal energy contained in the cooling medium stream CMS2 is transferred to the heat transfer medium stream HTMS1 in the heat pump HP, such that a cooling medium stream CMS3 is obtained in (ii), which has the same or higher thermal energy content as CMS1, wherein preferably, CMS3 is reintroduced into the cooling system and the heat exchanger as CMS1 or at least as a part thereof, respectively.

[0041] In some embodiments of the hydrogenation process, the heat exchanger is selected from the group consisting of: shell and tube heat exchangers, plate heat exchangers, field tube heat exchangers, and coil heat exchangers.

[0042] Reaction vessel

[0043] In some embodiments of the hydrogenation process, the reaction vessel is a reactor selected from the group consisting of: (multi)tubular reactors, stirred tank reactors, and loop reactors, wherein the reaction vessel is preferably a loop reactor. Regarding the combination of the heat exchanger and the reaction vessel, those skilled in the art know that a specific heat exchanger is mainly suitable for a specific reactor type. For example, for a loop reactor, in some preferred embodiments, a heat exchanger located in the reaction vessel, such as a shell and tube heat exchanger, is used.

[0044] In some preferred embodiments, the reaction vessel is a loop reactor. The loop reactor is preferably a vertical reactor, preferably a cylindrical reactor. The loop reactor has a downward-facing jet nozzle disposed in the upper region of the reactor, through which the starting materials and reaction mixture are fed, and at any desired point in the reactor, preferably in the lower region, has an outlet through which the reaction mixture is fed back to the jet nozzle in an external circuit by means of a conveying device (preferably a pump), and has a flow reversal in the lower region of the reactor. In the case of withdrawing the reaction mixture in the upper region of the reactor, the flow reversal and thus the formation of an internal loop flow can be achieved by the impact of the injected reaction mixture on the reactor bottom. In the case of preferably withdrawing the reaction mixture in the lower region of the reactor, the flow reversal is achieved by internals, in particular baffles perpendicular to the reactor wall. The reactor contains one or more mixing chambers, which are preferably formed by cylindrical insertion tubes and are arranged in the reactor parallel to the reactor wall. The jet nozzle can be designed as a single-component or two-component nozzle. In the case of a single-component nozzle, only the liquid reaction mixture is injected through the nozzle, and (gaseous) hydrogen is fed into the reactor at any other desired point, but preferably at a point within the reaction mixture. Suitable designs of loop reactors are known and are described, for example, in WO 00 / 30743A1, WO 00 / 35852A1 or WO 2014 / 108352 A1. In some preferred embodiments, the loop reactor includes a heat exchanger, preferably a heat exchanger located within the reactor. More preferably, the heat exchanger equipped with suitable pipelines for introducing and removing a cooling medium flow includes one or more preferably double-lined tubes (field tubes), which are preferably arranged in the reactor substantially parallel to the reactor wall. "Substantially parallel" means that the tubes are arranged at an angle of ±30°, preferably ±20°, more preferably ±10° relative to the reactor wall. The cooling medium flow flows within the field tubes, which are surrounded by the reaction mixture in the reactor on their outer side; a suitable arrangement is shown in Figure 1 WO 00 / 35852A1. In some alternative embodiments, the reaction takes place in a tube while the cooling medium flow surrounds the tube; suitable arrangements are described and shown in WO 2014 / 108352 A1.

[0045] The product, i.e., the compound having at least one amino group, is discharged from the system continuously or discontinuously, preferably continuously, at any desired point, but preferably at a point in the lower region of the reactor substrate, or is discharged particularly from the outer loop through a catalyst separation unit or without a catalyst separation unit. The separation unit can be a gravity separator (e.g., a settler), a suitable filter (e.g., a cross-flow filter), or a centrifuge. The catalyst can be separated from the product, and then the catalyst can be fed back into the reactor system or discharged from the reactor system. The product is preferably discharged while retaining the catalyst. The product can then be purified by conventional and known methods, such as by distillation or extraction.

[0046] Loop reactor + Improving heat pump efficiency by raising temperature (series arrangement)

[0047] In some embodiments of the hydrogenation process, if the reaction vessel is a loop reactor, the process comprises:

[0048] (i.1) Transfer at least a portion of the heat energy generated in the reaction vessel to a cooling medium, preferably the cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased heat energy content compared to CMS1;

[0049] (ii.a) Feed CSM2 to a heat exchanger installed in the circulation loop of the loop reactor, thereby transferring another portion of the heat energy generated in the reaction vessel to CMS2 and obtaining a cooling medium stream CMS4, which has an increased heat energy content compared to CMS2;

[0050] (ii.b) Transfer at least a portion of the heat energy contained in the cooling medium stream CMS4 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased heat energy content compared to HTMS1.

[0051] Preferably, in (ii), a cooling medium stream CMS3 is obtained, which has the same or higher heat energy content as CMS1, wherein preferably, CMS3 is reintroduced into the cooling system and the heat exchanger as CMS1 or at least as a part thereof, respectively.

[0052] Loop reactor + Improving heat pump efficiency by raising temperature (parallel arrangement)

[0053] In some embodiments of the hydrogenation process, if the reaction vessel is a loop reactor, the process comprises:

[0054] (i) Transfer at least a portion of the heat energy generated in the reaction vessel to a cooling medium, preferably the cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased heat energy content compared to CMS1;

[0055] (ii) Send a portion (CMS3a) of the cooling medium stream CMS3 obtained from the heat pump PH to a heat exchanger installed in the circulation loop of the loop reactor, thereby transferring a portion of the thermal energy generated in the reaction vessel to this portion CMS3a of the cooling medium stream and obtaining a partial cooling medium stream CMS5, which has an increased thermal energy content compared to CMS3;

[0056] (iii) Combine the partial cooling medium stream CMS5 with the cooling medium stream CMS2 obtained in (i),

[0057] thereby obtaining a combined cooling medium stream CMS2+CMS5;

[0058] (iv) Feed the combined cooling medium stream CMS2+CMS5 into the heat pump HP; and transfer at least a portion of the thermal energy contained in the combined cooling medium stream CMS2+CMS5 to the heat transfer medium stream HTMS1 in the heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

[0059] It should be understood that at the start of the method, after step (i), at least a portion of the thermal energy contained in the cooling medium stream CMS2 (i.e., without adding CMS5) is transferred to the heat transfer medium stream HTMS1 in the heat pump HP, thereby obtaining a heat transfer medium stream HTMS2 and obtaining a cooling medium stream CMS3, which has an increased thermal energy content compared to HTMS1 and a decreased thermal energy content compared to CMS2; subsequently, when the method has progressed, only the mixture of CMS2 and CMS5 is fed into the heat pump HP.

[0060] In some embodiments of the hydrogenation method, another portion (CMS3b) of CMS3 is reintroduced into the cooling system and the heat exchanger separately as CMS1 or at least as a part thereof.

[0061] Temperature

[0062] In some embodiments of the hydrogenation method, the cooling medium stream CMS2 or CMS4 or the combined stream of CSM2 and CSM5 entering the heat pump HP has a temperature in the range of 55°C to 150°C, and the cooling medium stream CMS3 leaving the heat pump HP has a temperature in the range of 30°C to 125°C.

[0063] Energy balance

[0064] In some embodiments of the hydrogenation process, at least 20% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via a cooling medium and a heat pump, preferably to the heat transfer medium streams HTMS1 and HTMS2 respectively.

[0065] In some embodiments of the hydrogenation process in which the heat pump is an absorption heat pump, preferably a type II absorption heat pump, 20% to 50% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via a cooling medium and a heat pump, preferably to the heat transfer medium streams HTMS1 and HTMS2 respectively.

[0066] In some embodiments of the hydrogenation process in which the heat pump is a compression heat pump, preferably a steam-generating compression heat pump (steam generator), 20% to 100%, preferably 70% to 100%, of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via a cooling medium and a heat pump, preferably to the heat transfer medium streams HTMS1 and HTMS2 respectively.

[0067] In some embodiments of the hydrogenation process in which the heat transfer medium stream HTMS2 is water vapor (H2O 气态 ), the ratio of the amount of steam generated in tons to the amount of thermal energy generated in the reaction vessel in MW (MW 热 ) is in the range of 0.3 t 蒸汽 / MW 热 to 7.0 t 蒸汽 / MW 热 ).

[0068] In some embodiments of the hydrogenation process in which the heat pump is an absorption heat pump, preferably a type II absorption heat pump, the ratio of the amount of steam generated in tons to the thermal energy generated in the reaction vessel in MW is in the range of 0.3 t 蒸汽 / MW 热 to 0.7 t 蒸汽 / MW 热 , preferably in the range of 0.35 t 蒸汽 / MW 热 to 0.6 t 蒸汽 / MW 热 .

[0069] In some embodiments of the hydrogenation process in which the heat pump is a compression heat pump, preferably a steam-generating compression heat pump, the ratio of the amount of steam generated in tons to the thermal energy generated in the reaction vessel in MW is in the range of 1.5 t 蒸汽 / MW 热 to 7 t 蒸汽 / MW 热 , preferably in the range of 1.7 t 蒸汽 / MW热 to 5.5 t 蒸汽 / MW 热 range.

[0070] In some embodiments of the hydrogenation process in which the heat transfer medium stream HTMS2 is water vapor (H2O 气态 ), the ratio of the electrical power demand in MW el to the amount of steam produced in tons is in the range of 0.002 MW el / t 蒸汽 to 0.55 MW el / t 蒸汽 , preferably 0.003 MW el / t 蒸汽 to 0.5 MW el / t 蒸汽 range.

[0071] In some embodiments of the hydrogenation process in which the heat pump is an absorption heat pump, preferably a type II absorption heat pump, the ratio of the electrical power demand in MW el to the amount of steam produced in tons is in the range of 0.002 MW el / t 蒸汽 to 0.025 MW el / t 蒸汽 , preferably 0.003 MW el / t 蒸汽 to 0.02 MW el / t 蒸汽 range.

[0072] In some embodiments of the hydrogenation process in which the heat pump is a compression heat pump, preferably a compression heat pump for generating steam, the ratio of the electrical power demand in MW el to the amount of steam produced in tons is in the range of 0.025 MW el / t 蒸汽 to 0.55 MW el / t 蒸汽 , preferably 0.05 MW el / t 蒸汽 to 0.5 MW el / t 蒸汽 range.

[0073] Compound to be hydrogenated

[0074] The compound to be hydrogenated is preferably a compound having at least one nitro group. In some embodiments of the hydrogenation process, the compound having at least one nitro group (also referred to as a "nitro compound") is preferably an organic compound having at least one nitro group, preferably selected from the group consisting of nitro alcohols, nitro aromatic compounds, and mixtures of nitro alcohols and nitro aromatic compounds.

[0075] The nitro compound is preferably an organic compound having at least one nitro group, preferably selected from the group consisting of nitro alcohols, nitroaromatic compounds, and mixtures of nitro alcohols and nitroaromatic compounds. In a preferred embodiment, the nitro compound for hydrogenation is a nitroaromatic compound, preferably selected from the group consisting of: mononitroaromatic compounds, dinitroaromatic compounds, polynitroaromatic compounds, and mixtures of two or more of them. A "mononitroaromatic compound" is an aromatic compound having only one nitro group as a substituent. A "dinitroaromatic" is an aromatic compound having two nitro groups as substituents. A "polynitroaromatic compound" in the context of the present invention is an aromatic compound having at least three nitro groups. In some preferred embodiments, the compound having at least one nitro group is selected from the group consisting of: mononitroaromatic compounds, dinitroaromatic compounds, and mixtures of mononitroaromatic compounds and dinitroaromatic compounds. Preferably, the compound having at least one nitro group contains at least a dinitroaromatic compound. The mononitroaromatic compound is preferably an aromatic compound having from 6 to 18 carbon atoms in the range and one nitro group as a substituent. In some preferred embodiments, the mononitroaromatic compound is selected from the group consisting of: mononitrotoluene, halogen derivatives of mononitrotoluene, mononitrobenzene, halogen derivatives of mononitrobenzene, mononitroxylene, mononitronaphthalene, nitroaniline, and mixtures of two or more of them. Preferably, the mononitroaromatic compound is selected from the group consisting of: nitrobenzene, o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, 1,2-dimethyl-3-nitrobenzene, 1,2-dimethyl-4-nitrobenzene, 1,4-dimethyl-2-nitrobenzene, 1,3-dimethyl-2-nitrobenzene, 2,4-dimethyl-1-nitrobenzene, 1,3-dimethyl-5-nitrobenzene, 1-nitronaphthalene, 2-nitronaphthalene, o-chloronitrobenzene, m-chloronitrobenzene, p-chloronitrobenzene, 1,2-dichloro-4-nitrobenzene, 1,4-dichloro-2-nitrobenzene, 2,4-dichloro-1-nitrobenzene, 1,2-dichloro-3-nitrobenzene, 4-chloro-2-nitrotoluene, 4-chloro-3-nitrotoluene, 2-chloro-4-nitrotoluene, 2-chloro-6-nitrotoluene, o-nitroaniline, m-nitroaniline, p-nitroaniline, and mixtures of two or more of them.In some preferred embodiments, the mononitroaromatic compound is selected from the group consisting of: mononitrobenzene, halogenated mononitrobenzene, mononitrotoluene, and mixtures of two or more thereof, more preferably selected from the group consisting of: nitrobenzene, o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, 1,2-dimethyl-3-nitrobenzene, 1,2-dimethyl-4-nitrobenzene, 1,4-dimethyl-2-nitrobenzene, 1,3-dimethyl-2-nitrobenzene, 2,4-dimethyl-1-nitrobenzene, 1,2-dichloro-4-nitrobenzene, 1,4-dichloro-2-nitrobenzene, 2,4-dichloro-1-nitrobenzene, 1,2-dichloro-3-nitrobenzene, and mixtures of two or more thereof, more preferably selected from the group consisting of: o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, and mixtures of two or more thereof. The dinitroaromatic compound is preferably an aromatic compound having from 6 to 18 carbon atoms. Preferably, the dinitroaromatic compound is selected from the group consisting of: dinitrotoluene, halides of dinitrotoluene dinitrobenzene, halides of dinitrobenzene, dinitronaphthalene, and mixtures of two or more thereof. In some preferred embodiments, the dinitroaromatic compound is selected from the group consisting of: 1,2-dinitrobenzene, 1,3-dinitrobenzene, 1,4-dinitrobenzene, 2,3-dinitrotoluene, 2,4-dinitrotoluene, 3,4-dinitrotoluene, 3,5-dinitrotoluene, 2,6-dinitrotoluene, 3,6-dinitrotoluene, and mixtures of two or more thereof, more preferably selected from the group consisting of: 2,3-dinitrotoluene, 2,4-dinitrotoluene, 3,4-dinitrotoluene, 3,5-dinitrotoluene, 2,6-dinitrotoluene, 3,6-dinitrotoluene, and mixtures of two or more thereof.

[0076] In some preferred embodiments of the hydrogenation process, the compound having at least one nitro group comprises 2,4-dinitrotoluene, 2,6-dinitrotoluene, or a mixture of 2,4-dinitrotoluene and 2,6-dinitrotoluene. In some preferred embodiments, the compound having at least one nitro group comprises 2,4-dinitrotoluene, 2,6-dinitrotoluene, or a mixture of 2,4-dinitrotoluene and 2,6-dinitrotoluene. Industrial mixtures containing 2,4-dinitrotoluene and 2,6-dinitrotoluene are also suitable, wherein these mixtures preferably contain at least 55 wt% of 2,4-dinitrotoluene and at most 35 wt% of 2,6-dinitrotoluene, wherein based on the total mixture being 100 wt%, the proportion of ortho-dinitrotoluene is preferably at most 5 wt%, and the proportions of 2,5-dinitrotoluene and 3,5-dinitrotoluene are preferably at most 1.5 wt%.

[0077] The above nitroalcohols and nitroaromatic compounds are commercially available. In addition, the nitroalcohols and nitroaromatic compounds used can be obtained by chemical synthesis. For example, dinitrotoluene can be obtained by nitration of toluene. The reaction products thus formed usually contain not only the desired nitro compounds but also many impurities.

[0078] If the above mixture is used, the weight ratio of the amine compound to water is preferably in the range of 10:1 to 1:10, more preferably in the range of 8:1 to 1:5, and particularly preferably in the range of 4:1 to 1:3. And the weight ratio of the amine / water mixture to the C1-C6 monohydric alcohol is preferably from 1000:1 to 1:1, more preferably from 500:1 to 2.5:1, and particularly preferably from 50:1 to 5:1.

[0079] In the context of the process according to the invention, the amounts of the alcohol solvent (i.e., C1-C6 monohydric alcohol) and the catalyst reactivation additive used are not limited in any particular way and can be freely selected as required.

[0080] Furthermore, the process according to the invention for hydrogenating a nitro compound to the corresponding amine can be carried out in the absence of a solvent. In this procedure, the work-up of the reaction mixture after hydrogenation is simplified, and furthermore side reactions with the solvent are completely suppressed.

[0081] Hydrogen (H2)

[0082] Any gas containing free hydrogen and not containing harmful amounts of catalyst poisons (such as CO) can be used as the hydrogenation gas. For example, reformer off-gas or a mixture of hydrogen with nitrogen and / or carbon monoxide can be used. Preferably, pure hydrogen (i.e., hydrogen with a purity of at least 90%) is used as the hydrogenation gas, or a mixture of hydrogen and an inert gas (preferably nitrogen) can be used as the hydrogenation gas, wherein at least 90% by weight of the mixture consists of hydrogen and nitrogen, and the total weight of the mixture is 100% by weight.

[0083] Solvent

[0084] The conversion of a compound having at least one nitro group to the corresponding compound having at least one amino group (in the reactor) is carried out in a liquid medium, preferably in a solution or suspension, which solution or suspension contains water and optionally one or more C1-C6 monohydric alcohols. Preferably, the C1-C6 monohydric alcohol is selected from the group consisting of C1-C5 monohydric alcohols, more preferably selected from the group consisting of methanol, ethanol, propanol (including n-propanol and isopropanol) and mixtures of two or three of them, and more preferably the solvent contains at least isopropanol. In some embodiments, a catalyst reactivation additive is used, preferably selected from the group consisting of aprotic solvents, more preferably selected from the group consisting of DMF, dioxane, THF or mixtures of two or more of them.

[0085] Reaction conditions

[0086] The reactor operates at a pressure in the range of 5 bar to 100 bar, preferably in the range of 10 bar to 50 bar, more preferably in the range of 15 bar to 40 bar, and even more preferably in the range of 20 bar to 30 bar, and the reaction mixture in the reactor has a temperature in the range of 50 °C to 200 °C, preferably in the range of 60 °C to 180 °C, more preferably in the range of 70 °C to 150 °C.

[0087] Catalyst

[0088] The catalyst used in the reaction is preferably a hydrogenation catalyst. Suitable hydrogenation catalysts are known per se for aromatic nitro compounds. Homogeneous and / or heterogeneous catalysts can be used, with heterogeneous catalysts preferably being used. The heterogeneous catalyst is employed in particulate form and suspended in the reaction suspension. Suitable catalysts are metals from subgroup VIII of the periodic table, which are preferably supported on a carrier material (such as activated carbon or oxides of aluminum, silicon, or other materials). Raney nickel and / or supported catalysts based on nickel, copper, palladium, and / or platinum are preferred. Suitable hydrogenation catalysts are known, for example, from WO 00 / 35852 A1 or WO 2005 / 037768 A1. Based on the weight of the reaction mixture being 100% by weight, the hydrogenation catalyst is preferably used in an amount of 0.01% to 10% by weight, preferably 0.1% to 5% by weight, and particularly preferably 0.2% to 2% by weight.

[0089] Second aspect - Reaction system for hydrogenation

[0090] A second aspect of the present invention relates to a reaction system for hydrogenating a compound, preferably for converting a compound having at least one nitro group into the corresponding compound having at least one amino group by hydrogenation, the reaction system comprising:

[0091] (a) A reactor having:

[0092] (a.1) Equipment for feeding gaseous and liquid materials into the reactor;

[0093] (a.2) Equipment for mixing in the reactor,

[0094] (a.3) An outlet for removing the reaction mixture from the reactor;

[0095] (a.4) At least one inlet for reintroducing the reaction mixture;

[0096] (a.5) A circuit pipeline that is fluidly connected to the outlet (a.3) and the inlet (a.4) outside the reactor, and the circuit pipeline is capable of taking out the reaction mixture from the reactor via the outlet (a.3) and reintroducing the reaction mixture into the reactor via the inlet (a.4);

[0097] (a.6) At least one heat exchanger arranged in the reactor, outside the reactor, or in the circuit pipeline (a.5), wherein the heat exchanger has at least one inlet (a.6.1) for feeding a cooling medium into the heat exchanger and at least one outlet (a.6.2) for removing the cooling medium from the heat exchanger;

[0098] (b) A heat pump, which includes:

[0099] (b.1) At least one inlet (b.1.1) for feeding a cooling medium into the heat pump and at least one outlet (b.1.2) for removing the cooling medium from the heat pump;

[0100] (b.2) At least one inlet (b.2.1) for feeding a heat transfer medium flow into the heat pump and at least one outlet (b.2.2) for removing the heat transfer medium flow from the heat pump;

[0101] wherein the heat pump is constructed to allow heat energy to be transferred from the cooling medium flow to the heat transfer medium flow;

[0102] (c) A pipeline that is fluidly connected to at least one heat exchanger (a.6) and the heat pump (b), and the pipeline is constructed and arranged to

[0103] (c.1) Allow the cooling medium flow from at least one outlet (a.6.2) of the heat exchanger to be transferred into the inlet (b.1.1) of the heat pump, and reintroduce the cooling medium flow from at least one outlet (b.1.2) into at least one inlet (a.6.1), the at least one outlet for removing the cooling medium from the heat pump, and the at least one inlet for feeding the cooling medium into the heat exchanger; and

[0104] (c.2) Allow the heat transfer medium flow to be introduced into at least one inlet (b.2.1) of the heat pump and allow the heat transfer medium flow to be removed from at least one outlet (b.2.2) of the heat pump, the at least one inlet for feeding the heat transfer medium flow into the heat pump, and the at least one outlet for removing the heat transfer medium flow from the heat pump.

[0105] In some preferred embodiments of the reaction system, the heat pump (b) is an absorption heat pump (preferably a type II absorption heat pump), or a compression heat pump, and more preferably the heat pump of (b) is a type II absorption heat pump.

[0106] In some preferred embodiments of the reaction system, the reactor (a) is selected from the group consisting of (multi-)tubular reactors, stirred tank reactors, and loop reactors, where the reactor is preferably a loop reactor.

[0107] All details, embodiments, and preferred embodiments disclosed above in the part related to the first aspect also apply to the reaction system, i.e., the second aspect of the present invention.

[0108] The present invention is further illustrated by the following examples and combinations of examples, as indicated by their respective dependencies and cross-references. In particular, it should be noted that in each case where a range of embodiments is mentioned, for example, in the context of terms such as "…… according to any one of embodiments 1 to 4", each embodiment within that range is clearly disclosed to the person skilled in the art, i.e., the wording of the term should be understood by the person skilled in the art as being synonymous with "…… according to any one of embodiments 1, 2, 3, and 4".

[0109] 1. A hydrogenation method for hydrogenating a compound, the hydrogenation method comprising reacting the compound with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst, the method comprising

[0110] (i) transferring at least a portion of the thermal energy generated in the reaction vessel to a cooling medium, preferably the cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased thermal energy content compared to CMS1;

[0111] (ii) transferring at least a portion of the thermal energy contained in the cooling medium stream CMS2 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

[0112] 2. The hydrogenation method according to embodiment 1, wherein the hydrogenation method is a method of hydrogenating a compound having at least one nitro group into a corresponding compound having at least one amino group, the method comprising reacting the compound having at least one nitro group with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst.

[0113] 3. The hydrogenation method according to embodiment 1 or 2, wherein the heat pump in (ii) is an absorption heat pump, preferably a type II absorption heat pump, or a compression heat pump, and more preferably the heat pump in (ii) is a type II absorption heat pump.

[0114] 4. The hydrogenation method according to any one of embodiments 1 to 3, wherein the heat transfer medium comprises water, preferably at least 90% by weight, more preferably at least 95% by weight, more preferably at least 99% by weight of the heat transfer medium is water, each based on the total weight of the heat transfer medium being 100% by weight.

[0115] 5. The hydrogenation method according to embodiment 4, wherein at least 90% by weight of the heat transfer medium stream HTMS1 is in the liquid state, and at least 90% by weight of the heat transfer medium stream HTMS2 is in the gaseous state (H2O 气态 , steam).

[0116] 6. The hydrogenation method according to any one of embodiments 1 to 5, wherein the heat transfer medium stream HTMS2 has a pressure p2 in the range of 0 barg to 20 barg, preferably in the range of 0.1 barg to 10 barg.

[0117] 7. The hydrogenation method according to any one of embodiments 1 to 6, wherein preferably the heat transfer medium stream HTMS2 having the pressure p2 is compressed by mechanical compression to obtain a heat transfer medium stream HTMS2-1 having an increased pressure p 2-1 compared to p2, wherein p 2-1 is preferably a pressure in the range of 3 barg to 40 barg.

[0118] 8. The hydrogenation method according to any one of embodiments 1 to 7, wherein the cooling medium is selected from the group consisting of water, air, solvents, and mixtures of two or more thereof, wherein the cooling medium preferably comprises water, preferably at least 90% by weight, more preferably at least 95% by weight, more preferably at least 99% by weight of the heat transfer medium is water, each based on the total weight of the cooling medium being 100% by weight.

[0119] 9. The hydrogenation method according to any one of embodiments 1 to 8, wherein at least a part of the thermal energy generated in the reaction vessel in (i) is transferred to the cooling medium stream CMS1 by using a cooling system, the cooling system comprising a heat exchanger arranged inside the reaction vessel or at least partially surrounding the reaction vessel and a circulation pipeline for introducing CMS1 into the heat exchanger and for removing CMS2 from the heat exchanger.

[0120] 10. The hydrogenation method according to embodiment 9, wherein at least a part of the thermal energy contained in the cooling medium stream CMS2 in (ii) is transferred to the heat transfer medium stream HTMS1 in the heat pump HP, such that a cooling medium stream CMS3 is obtained in (ii), the CMS3 having the same or higher thermal energy content as CMS1, wherein preferably, CMS3 is reintroduced into the cooling system and the heat exchanger as CMS1 or at least as a part thereof, respectively.

[0121] 11. The hydrogenation method according to embodiment 9 or 10, wherein the heat exchanger is selected from the group consisting of: shell and tube heat exchanger, plate heat exchanger, field tube heat exchanger and coil heat exchanger.

[0122] 12. The hydrogenation method according to any one of embodiments 1 to 11, wherein the reaction vessel is a reactor selected from the group consisting of: (multi) tubular reactor, stirred tank reactor and loop reactor, and preferably the reaction vessel is a loop reactor.

[0123] 13. The hydrogenation method according to embodiment 12, wherein for the reaction vessel being a loop reactor, the method comprises:

[0124] (i.1) Transfer at least a part of the thermal energy generated in the reaction vessel to a cooling medium, preferably the cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased thermal energy content compared to CMS1;

[0125] (ii.a) Feed CSM2 to a heat exchanger installed in the circulation loop of the loop reactor, thereby transferring another part of the thermal energy generated in the reaction vessel to CMS2 and obtaining a cooling medium stream CMS4, which has an increased thermal energy content compared to CMS2;

[0126] (ii.b) Transfer at least a part of the thermal energy contained in the cooling medium stream CMS4 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

[0127] 14. The hydrogenation method according to embodiment 13, wherein in (ii), a cooling medium stream CMS3 is obtained, which has the same or higher thermal energy content as CMS1, and preferably, CMS3 is reintroduced into the cooling system and the heat exchanger as CMS1 or at least as a part of it, respectively.

[0128] 15. The hydrogenation method according to embodiment 12, wherein for the reaction vessel being a loop reactor, the method comprises:

[0129] (i) Transfer at least a part of the thermal energy generated in the reaction vessel to a cooling medium, preferably the cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased thermal energy content compared to CMS1;

[0130] (ii) A part (CMS3a) of the cooling medium stream CMS3 obtained from a heat pump PH

[0131] Sent to a heat exchanger in the circulation loop of the loop reactor, thereby transferring a part of the thermal energy generated in the reaction vessel to this part CMS3a of the cooling medium flow and obtaining a partial cooling medium flow CMS5, which has an increased thermal energy content compared to CMS3;

[0132] (iii) Combining the partial cooling medium flow CMS5 with the cooling medium flow CMS2 obtained in (i), thereby obtaining a combined cooling medium flow CMS2+CMS5;

[0133] (iv) Feeding the combined cooling medium flow CMS2+CMS5 into the heat pump HP; and

[0134] Transferring at least a part of the thermal energy contained in the combined cooling medium flow CMS2+CMS5 to the heat transfer medium flow HTMS1 in the heat pump HP, thereby obtaining a heat transfer medium flow HTMS2, which has an increased thermal energy content compared to HTMS1.

[0135] 16. The hydrogenation method according to embodiment 15, wherein another part (CMS3b) of CMS3 is reintroduced into the cooling system and the heat exchanger respectively as CMS1 or at least as a part thereof.

[0136] 17. The hydrogenation method according to any one of embodiments 1 to 16, wherein the cooling medium flow CMS2 or CMS4 or the combined flow of CSM2 and CSM5 entering the heat pump HP has a temperature in the range of 55°C to 150°C, and the cooling medium flow CMS3 leaving the heat pump HP has a temperature in the range of 30°C to 125°C.

[0137] 18. The hydrogenation method according to any one of embodiments 1 to 7, wherein at least 20% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via the cooling medium and the heat pump, preferably to the heat transfer medium flow HTMS1 and the heat transfer medium flow HTMS2 respectively.

[0138] 19. The hydrogenation method according to embodiment 18, wherein in the case where the heat pump is an absorption heat pump, preferably a type II absorption heat pump, 20% to 50% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via the cooling medium and the heat pump, preferably to the heat transfer medium flow HTMS1 and the heat transfer medium flow HTMS2 respectively.

[0139] 20. The hydrogenation method according to embodiment 18, wherein in the case where the heat pump is a compression heat pump, preferably a steam-generating compression heat pump (steam generator), 20% to 100%, preferably 70% to 100% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via the cooling medium and the heat pump, preferably to the heat transfer medium stream HTMS1 and the heat transfer medium stream HTMS2 respectively.

[0140] 21. The hydrogenation method according to any one of embodiments 1 to 20, wherein in the case where the heat transfer medium stream HTMS2 is water vapor (H2O 气态 ), the ratio of the amount of steam generated in tons to the amount of thermal energy generated in the reaction vessel in MW is in the range of 0.3 t 蒸汽 / MW 热 to 7.0 t 蒸汽 / MW 热 range.

[0141] 22. The hydrogenation method according to embodiment 21, wherein in the case where the heat pump is an absorption heat pump, preferably a type II absorption heat pump, the ratio of the amount of steam generated in tons to the

[0142] amount of thermal energy generated in the reaction vessel in MW is in the range of 0.3 t 蒸汽 / MW 热 to

[0143] 0.7 t 蒸汽 / MW 热 range, preferably in the range of 0.35 t 蒸汽 / MW 热 to 0.6 t 蒸汽 / MW 热 range.

[0144] 23. The hydrogenation method according to embodiment 21, wherein in the case where the heat pump is a compression heat pump, preferably a steam-generating compression heat pump, the ratio of the amount of steam generated in tons to the amount of thermal energy generated in the reaction vessel in MW is in the range of 1.5 t 蒸汽 / MW 热 to 7 t 蒸汽 / MW 热 range, preferably in the range of 1.7 t 蒸汽 / MW 热 to 5.5 t 蒸汽 / MW 热 range.

[0145] 24. The hydrogenation method according to any one of embodiments 1 to 23, wherein in the case where the heat transfer medium stream HTMS2 is water vapor (H2O 气态) In the case of, the ratio of the power demand in MW el to the amount of steam generated in tons is from 0.002 MW el / t 蒸汽 to 0.55 MW el / t 蒸汽 , preferably from 0.003 MW el / t 蒸汽 to 0.5 MW el / t 蒸汽 and within the range.

[0146] 25. The hydrogenation method according to embodiment 21, wherein in the case where the heat pump is an absorption heat pump, preferably a type II absorption heat pump, the ratio of the power demand in MW el to the amount of steam generated in tons is from 0.002 MW el / t 蒸汽 to 0.025 MW el / t 蒸汽 , preferably from 0.003 MW el / t 蒸汽 to 0.02 MW el / t 蒸汽 and within the range.

[0147] 26. The hydrogenation method according to embodiment 21, wherein in the case where the heat pump is a compression heat pump, preferably a compression heat pump for generating steam, the ratio of the power demand in MW el to the amount of steam generated in tons is from 0.025 MW el / t 蒸汽 to 0.55 MW el / t 蒸汽 , preferably from 0.05 MW el / t 蒸汽 to 0.5 MW el / t 蒸汽 and within the range.

[0148] 27. The hydrogenation method according to any one of embodiments 1 to 26, wherein the compound having at least one nitro group (also referred to as "nitro compound") is preferably an organic compound having at least one nitro group, preferably selected from the group consisting of nitro alcohols, nitro aromatic compounds, and mixtures of nitro alcohols and nitro aromatic compounds.

[0149] 28. The hydrogenation method according to embodiment 27, wherein the compound having at least one nitro group includes 2,4-dinitrotoluene, 2,6-dinitrotoluene, or a mixture of 2,4-dinitrotoluene and 2,6-dinitrotoluene.

[0150] 29. A reaction system for hydrogenating a compound, preferably for converting a compound having at least one nitro group into the corresponding compound having at least one amino group by hydrogenation, the

[0151] reaction system comprising:

[0152] (a) A reactor having:

[0153] (a.1) Equipment for feeding gaseous and liquid materials into the reactor;

[0154] (a.2) Equipment for mixing in the reactor,

[0155] (a.3) An outlet for removing the reaction mixture from the reactor;

[0156] (a.4) At least one inlet for reintroducing the reaction mixture;

[0157] (a.5) A loop pipeline that is fluidly connected to the outlet (a.3) and the inlet (a.4) outside the reactor, and the loop pipeline is capable of removing the reaction mixture from the reactor via the outlet

[0158] (a.3) and reintroducing the reaction mixture into the reactor via the inlet (a.4);

[0159] (a.6) At least one heat exchanger arranged inside the reactor, outside the reactor, or in the loop pipeline (a.5), wherein the heat exchanger has at least one inlet (a.6.1) for feeding a cooling medium into the heat exchanger and at least one outlet (a.6.2) for removing the cooling medium from the heat exchanger;

[0160] (b) A heat pump comprising:

[0161] (b.1) At least one inlet for feeding a cooling medium into the heat pump

[0162] (b.1.1), and at least one outlet (b.1.2) for removing the cooling medium from the heat pump;

[0163] (b.2) At least one inlet for feeding a heat transfer medium flow into the heat pump

[0164] (b.2.1), and at least one outlet (b.2.2) for removing the heat transfer medium flow from the heat pump;

[0165] wherein the heat pump is constructed to allow heat energy to be transferred from the cooling medium flow to the heat transfer medium flow;

[0166] (c) A pipeline, which is fluidly connected to at least one heat exchanger (a.6) and the heat pump (b), and the pipeline is constructed and arranged to

[0167] (c.1) allow the flow of the cooling medium from the at least one outlet (a.6.2) of the heat exchanger to be transferred into the inlet (b.1.1) of the heat pump, and reintroduce the flow of the cooling medium from the at least one outlet (b.1.2) into the at least one inlet (a.6.1), the at least one outlet being for removing the cooling medium from the heat pump, and the at least one inlet being for feeding the cooling medium into the heat exchanger; and

[0168] (c.2) to allow the introduction of the heat transfer medium flow into the at least one inlet

[0169] (b.2.1) of the heat pump, and allow the removal of the heat transfer medium flow from the at least one outlet (b.2.2) of the heat pump, the at least one inlet being for feeding the heat transfer medium flow into the heat pump, and the at least one outlet being for removing the heat transfer medium flow of the heat pump.

[0170] 30. The reaction system according to embodiment 29, wherein the heat pump (b) is an absorption heat pump, preferably a class II absorption heat pump, or a compression heat pump, and more preferably the heat pump of (b) is a class II absorption heat pump.

[0171] 31. The reaction system according to embodiment 29 or 30, wherein the reactor (a) is selected from the group consisting of (multi)-tubular reactors, stirred tank reactors, and loop reactors, and preferably the reactor is a loop reactor.

[0172] The present invention is further illustrated by the following reference examples, comparative examples, and examples. Examples

[0173] Simulation

[0174] All simulations were performed using the process simulation software ASPEN PLUS TM v.11 or in combination with Excel-based estimation calculations with a specified quality grade, and were carried out using FluidExl (LiblF97, IAPWS-IF97) based on KCE ThermoFluidProperties. The components used in the process simulation and their characteristics were taken from the ASPEN PLUS TM v.11 PURE32 database.

[0175] Definitions, abbreviations

[0176] The pressure indicated by "barg" is related to gauge pressure. Since gauge pressure is measured relative to ambient pressure, each pressure value (or range) indicated by barg is equal to the absolute pressure minus the atmospheric pressure. "bara" means absolute pressure in bar.

[0177] Comparative Example 1: Hydrogenation of dinitrotoluene using a loop of main cooling medium and a loop of secondary cooling medium

[0178] The hydrogenation of dinitrotoluene (a mixture containing approximately 80 wt% 2,4-dinitrotoluene and approximately 20 wt% 2,6-dinitrotoluene) to toluenediamine is carried out in a hydrogenation reactor, which is a loop reactor. To ensure good mixing, the reactor contents, i.e., the hydrogenation bath, which consists mainly of water, solvent, solid catalyst, the reactant dinitrotoluene, and the product toluenediamine, are pumped through an external loop. The reaction heat in the reactor is removed from the hydrogenation bath through a main cooling medium loop containing the main cooling medium. The warm main cooling medium is cooled down through a secondary cooling loop, which is operated with a second cooling medium (such as river water or an air cooler), and then the cold main cooling medium is sent back to the reactor.

[0179] The heat energy released from the reaction (which must be absorbed by the cooling medium) is 40 MW.

[0180] Example 1: Hydrogenation of dinitrotoluene using a loop of main cooling medium and a heat pump (type II absorption heat pump)

[0181] The hydrogenation of dinitrotoluene is carried out as in Comparative Example 1. Contrary to Comparative Example 1, the main cooling medium loop is not operated - this setup is shown in Figure 1 Instead, a heat pump (heat exchanger unit) located in the main cooling loop is used to (at least partially) recover the reaction heat from the main cooling medium, i.e., the heat energy initially transferred to the main cooling medium. The reaction heat of the hydrogenation reaction heats up the main cooling medium. Then the warm main cooling medium flow is used in the heat pump to generate steam from boiling water. Thereby, the main cooling medium is cooled down and sent back to the reactor as cold main cooling medium steam. A backup cooling system is installed in the main cooling loop to remove the reaction heat in case the heat pump is shut down and to provide support during startup or shutdown of the reactor system.

[0182] An absorption heat pump, namely a so-called Type II, is used. Thus, the absorption heat is used to generate steam. The desorption energy is used for the cooling of the main cooling medium. Preferably, a LiBr-water mixture is used as the heat transfer medium in the absorption heat pump.

[0183] The pressure of the generated steam is between 0 barg and 20 barg. Approximately 20% to 50% of the heat of the exothermic hydrogenation reaction is transferred to the steam. The power consumption is low, and the cooling water demand can be reduced by approximately 30% compared to the cooling water demand of Comparative Example 1.

[0184] The energy balance according to Example 1 is as follows:

[0185] t 蒸汽 / MW 热 : 0.3 - 0.7

[0186] kW el / t 蒸汽 : 2 - 25

[0187] MW 冷却 / MW 热 : 0.4 - 0.8

[0188] “t 蒸汽 ” means the amount of steam generated in tons, “MW 热 ” means the energy in MW, i.e., the amount of heat energy generated by the reaction, “kW el ” means the power demand required for the overall reaction including the heat pump in kW, “MW 冷却 ” means the cooling energy demand in MW.

[0189] Example 2: Hydrogenation of dinitrotoluene using a loop of main cooling medium and a heat pump (compression heat pump)

[0190] The hydrogenation of dinitrotoluene was carried out as in Comparative Example 1. Contrary to Comparative Example 1, the main cooling medium loop was not operated. Instead, the heat pump (heat exchanger unit) located in the main cooling loop was used to recover (at least partially) the reaction heat from the main cooling medium, i.e., the heat energy initially transferred to the main cooling medium - the setup is shown in Figure 1 . The reaction heat of the hydrogenation reaction heats up the main cooling medium. Then the warm main cooling medium stream is used in the heat pump to generate steam from boiling water, thereby generating a heating medium stream HTMS2. Thus, the main cooling medium is cooled down and sent back to the reactor as a cold main cooling medium steam - the temperature of this cooling medium stream CMS1 returning to the reactor is also referred to as the “waste heat temperature return”. A standby cooling system is installed in the main cooling loop to remove the reaction heat in case the heat pump is shut down and to provide support during the startup or shutdown of the reactor system.

[0191] A so - called Class I compression heat pump is used to generate steam. The evaporation of the solvent / heat transfer medium is used to cool the main cooling medium. After the gaseous solvent / heat transfer medium is compressed, the condensation of the medium at a higher pressure is used for steam generation.

[0192] Experiments were simulated with different waste heat temperature return values of CSM1 and different pressures of the generated steam of HTMS2 between 1 barg and 40 barg. More than 90% of the thermal reaction heat of the hydrogenation MW 热 is transferred to the steam. The amount of the required electric power MW el is high and the cooling water demand is low. The outlet temperature returning from the HP to the reactor is between 30 °C and 100 °C.

[0193] The energy balance according to Example 2 is:

[0194] t 蒸汽 / MW 热 :1.5-7

[0195] t 蒸汽 / (MW 热 +MW el ): 1-2

[0196] MW el / t 蒸汽 : 0.025-0.55

[0197] Details of the simulation :

[0198] Compressor type: turbo compressor

[0199] Heat pump quality grade (eta=COP HP / COP 卡诺 ): 55%

[0200] Superheat of steam: 10K

[0201] Boiler feed temperature: 95℃

[0202] “COP” means coefficient of performance calculated based on the equation COP=Q / W, where “Q” is the heat transferred to the heat transfer medium (available heat: HTMS2-HTMS1), and “W” is the work (consumed work, electrical energy) or driving heat of the compressor.

[0203] COP HP : Coefficient of performance of heat pump

[0204] COP 卡诺： Ideal performance coefficient calculated based on Carnot process

[0205] About COP HP MW el / t 蒸汽 ,t 蒸汽 / MW 热 and t 蒸汽 / (MW el +MW 热 ) and the obtained values ​​are shown in Table 1 below:

[0206] Table 1

[0207] Parameters and obtained values

[0208]

[0209]

[0210] Example 3: Hydrogenation using a loop of main cooling medium and a heat pump (type II absorption heat pump) plus a mechanical vapor compressor Dinitrotoluene

[0211] Hydrogenation of dinitrotoluene is carried out as in Example 1, where only low-pressure steam (pressure 0 barg to 8 barg) is generated. In addition to Example 1, compression is carried out by an additional mechanical steam compressor to pressurize the steam to a pressure between 4 barg and 40 barg - this setup is shown in Figure 2 . Compared with Example 1, an additional power input is required. The additional power requirement compared with Example 1 is MW el,MC / t 蒸汽 : 0.025 - 0.3.

[0212] Example 4: Hydrogenation of dinitro Toluene using a loop of main cooling medium and a heat pump (compression heat pump) plus a mechanical vapor compressor

[0213] Hydrogenation of dinitrotoluene is carried out as in Example 2, where only low-pressure steam (pressure 0 barg to 8 barg) is generated. In addition to Example 2, compression is carried out by an additional mechanical steam compressor to pressurize the steam to a pressure between 4 barg and 40 barg - this setup is shown in Figure 2 . Compared with Example 2, an additional power input is required. The additional power requirement compared with Example 2 is MW el,MC / t 蒸汽 : 0.025 - 0.3.

[0214] Details of the simulation :

[0215] Type of compressor: Turbine compressor

[0216] Heat pump quality grade (eta = COP HP / COP 卡诺 ): 55%

[0217] MC efficiency (isentropic line): 75%

[0218] Injection pump efficiency: 90%

[0219] Superheat of steam: 10 K

[0220] Cooker feed temperature: 95 °C

[0221] The parameters and the resulting values are shown in Table 2 below:

[0222] Table 2

[0223] Parameters and obtained values

[0224] Description of the Drawings

[0225] Figure 1 Shows the setup with a main cooling medium circuit and a heat pump HP as used in Example 1 and Example 2 (Example 1: Class II absorption heat pump, Example 2: Class I compression heat pump). The hydrogenation of dinitrotoluene to toluenediamine is carried out in the hydrogenation reactor R. The hydrogenation bath, mainly composed of water, solvent, solid catalyst, reactants and products, is pumped through the external circuit 1. To remove the reaction heat released from the reaction inside the reactor R, a main cooling medium circuit including the circuit line 2, the circuit line 3 and a heat exchanger (not shown) located in the reactor is used. The warm main cooling medium flow CMS2 from the reactor arrives at the heat pump HP through the circuit line 2, where steam is generated by the heat transfer medium flow HTMS1 (here boiling water) arriving at the heat pump HP through the boiling water feed line 4. The heat transfer medium flow HTMS2 (here water vapor) with an increased heat energy content compared to HTMS1 generated in the heat pump HP leaves through the line 5. Due to the heat release in the heat pump HP, the main cooling medium is cooled down and sent back to the reactor as the cold cooling medium flow CMS1 through the line 3. A standby cooling system BCS including a heat exchanger is installed in the main cooling circuit to remove the reaction heat in case the heat pump HP is shut down and to provide support during the startup or shutdown of the reactor system.

[0226] Figure 2Shows the setup with a main cooling medium circuit and a heat pump HP as used in Example 3 and Example 4 (Example 3: Class II absorption heat pump + mechanical vapor compressor, Example 2: Class I compression heat pump + mechanical vapor compressor). The hydrogenation of dinitrotoluene to toluenediamine is carried out in the hydrogenation reactor R. The hydrogenation bath mainly composed of water, solid catalyst, reactants and products is pumped through the external circuit 1. To remove the reaction heat released from the reaction inside the reactor R, a main cooling medium circuit including circuit line 2, circuit line 3 and a heat exchanger (not shown) located in the reactor is used. The warm main cooling medium flow CMS2 from the reactor through circuit line 2 reaches the heat pump HP, where steam is generated by the heat transfer medium flow HTMS1 (here boiling water) reaching the heat pump HP through the boiling water feed line 4. The heat transfer medium flow HTMS2 (here steam) with an increased thermal energy content compared to HTMS1 generated in the heat pump HP leaves through line 5. Then HTMS2 enters the mechanical vapor compressor MSC, where the pressure of HTMS2 is increased, such that the heat transfer medium flow HTMS2-1 with an increased pressure compared to HTMS2 leaves the MSC via line 6. Due to the heat release in the heat pump HP, the main cooling medium is cooled down and sent back to the reactor as the cold cooling medium flow CMS1 through line 3. A standby cooling system BCS including a heat exchanger is installed in the main cooling circuit to remove the reaction heat in case the heat pump HP is shut down and to provide support during the startup or shutdown of the reactor system.

[0227] Figure 3A series arrangement for increasing the efficiency of a heat pump HP by raising the temperature by means of a main coolant circuit and the heat pump HP is shown. The hydrogenation of dinitrotoluene to toluenediamine is carried out in a hydrogenation reactor R. A hydrogenation bath mainly composed of water, a solvent, a solid catalyst, reactants and products is pumped through an external circuit 1. In order to remove the reaction heat released from the reaction inside the reactor R, a main coolant circuit including a circuit line 2, a circuit line 2a and a circuit line 3 and a heat exchanger (not shown) located in the reactor and serving as an additional heat exchanger HE is used. The warm main coolant flow CMS2 from the reactor via the circuit line 2 reaches the additional heat exchanger HE installed in the external circuit 1 of the hydrogenation bath. The warm main coolant absorbs more heat in the HE, and subsequently an even warmer main coolant flow CMS4 flows into the heat pump HP via the line 2a. In the heat pump HP, a heat transfer medium flow HTMS2 (here steam) is generated from a heat transfer medium flow HTMS1 (here boiling water) reaching the heat pump HP via a boiling water feed line 4. The heat transfer medium flow HTMS2 (here water vapor) with an increased heat energy content compared to HTMS1 generated in the heat pump HP leaves via the line 5. Due to the heat release in the heat pump HP, the main coolant is cooled down and sent back to the reactor as a cold coolant flow CMS1 via the line 3. A standby cooling system BCS including a heat exchanger is installed in the main cooling circuit to remove the reaction heat in the case of the heat pump HP being switched off and to provide support during startup or shutdown of the reactor system.

[0228] Figure 4A parallel arrangement is shown for increasing the efficiency of a heat pump HP by raising the temperature using a main cooling medium circuit and the heat pump HP. The hydrogenation of dinitrotoluene to toluenediamine is carried out in a hydrogenation reactor R. A hydrogenation bath mainly composed of water, a solvent, a solid catalyst, reactants and products is pumped through an external circuit 1. To remove the reaction heat released from the reaction inside the reactor R, a main cooling medium circuit is used, which includes circuit lines 2, 3, 3a and 3b and a heat exchanger (not shown) located in the reactor as an additional heat exchanger HE. The cold cooling medium flow CMS1 from the heat pump HP is split into two flows, where the first part is sent directly back to the reaction through line 3, while the second part is sent through line 3a to the additional heat exchanger HE installed in the external circuit 1 of the hydrogenation bath. The warm main cooling medium absorbs more heat in HE, and then the relatively warm main cooling medium flow CMS5 flows through line 3b and mixes with the warm main cooling medium CMS2. The mixed flow of CMS2 and CMS5 flows into the heat pump HP. In the heat pump HP, a heat transfer medium flow HTMS2 (here steam) is generated from a heat transfer medium flow HTMS1 (here boiling water) that reaches the heat pump HP through a boiling water feed line 4. The heat transfer medium flow HTMS2 (here water vapor) with an increased thermal energy content compared to HTMS1 generated in the heat pump HP leaves through line 5. Due to the heat release in the heat pump HP, the main cooling medium flow CMS1 is cooled down and sent back to the reactor as a cold cooling medium flow through line 3 and sent back to the additional heat exchanger HE through line 3b. A standby cooling system BCS including a heat exchanger is installed in the main cooling circuit to remove the reaction heat in case the heat pump HP is shut down and to provide support during the start-up or shutdown of the reactor system.

[0229] Cited literature

[0230] WO 00 / 30743 A1

[0231] WO 00 / 35852 A1

[0232] C. Arpagaus et al., Energy 152 (2018), pp. 985 to 1010

[0233] WO 2014 / 108352 A1

Claims

1. A hydrogenation method for a compound, the hydrogenation method comprising reacting the compound with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst, the method comprising (i) transferring at least a part of the heat energy generated in the reaction vessel to a cooling medium, preferably a cooling medium stream CMS1, to obtain a cooling medium stream CMS2, the CMS2 having an increased heat energy content compared to CMS1; (ii) transferring at least a part of the heat energy contained in the cooling medium stream CMS2 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, the HTMS2 having an increased heat energy content compared to HTMS1.

2. The hydrogenation method according to claim 1, wherein the hydrogenation method is a method for hydrogenating a compound having at least one nitro group into a corresponding compound having at least one amino group, the method comprising reacting the compound having at least one nitro group with hydrogen in a liquid medium in a reaction vessel in the presence of a heterogeneous hydrogenation catalyst.

3. The hydrogenation method according to claim 1 or 2, wherein the heat pump in (ii) is an absorption heat pump, preferably a type II absorption heat pump, or a compression heat pump, more preferably the heat pump in (ii) is a type II absorption heat pump.

4. The hydrogenation method according to any one of claims 1 to 3, wherein the heat transfer medium contains water, preferably at least 90% by weight, more preferably at least 95% by weight, more preferably at least 99% by weight of the heat transfer medium is water, each based on the total weight of the heat transfer medium being 100% by weight.

5. The hydrogenation method according to any one of claims 1 to 4, wherein the heat transfer medium stream HTMS2 has a pressure p2 in the range of 0 barg to 20 barg, preferably in the range of 0.1 barg to 10 barg.

6. The hydrogenation process according to any one of claims 1 to 5, wherein preferably the heat transfer medium stream HTMS2 having a pressure p2 is compressed by mechanical compression to obtain a heat transfer medium stream HTMS2-1 having an increased pressure p compared to p2, where p 2-1 is preferably a pressure in the range of 3 barg to 40 barg. 2-1 ​ 7. The hydrogenation method according to any one of claims 1 to 6, wherein in (i) transferring at least a part of the heat energy generated in the reaction vessel to the cooling medium stream CMS1 is carried out by using a cooling system, the cooling system comprising a heat exchanger arranged in the reaction vessel or at least partially surrounding the reaction vessel and a circulation pipeline for introducing CMS1 into the heat exchanger and for removing CMS2 from the heat exchanger; wherein preferably, in (ii) transferring at least a part of the heat energy contained in the cooling medium stream CMS2 to the heat transfer medium stream HTMS1 in the heat pump HP such that a cooling medium stream CMS3 is obtained in (ii), the CMS3 having the same or higher heat energy content as CMS1, wherein preferably, CMS3 is reintroduced into the cooling system and the heat exchanger as CMS1 or at least as a part thereof, respectively.

8. The hydrogenation method according to any one of claims 1 to 7, wherein the reaction vessel is a reactor selected from the group consisting of: (multi)tubular reactor, stirred tank reactor and loop reactor, wherein the reaction vessel is preferably a loop reactor.

9. The hydrogenation process according to claim 8, wherein for the reaction vessel being a loop reactor, the process comprises: (i.1) transferring at least a portion of the thermal energy generated in the reaction vessel to a cooling medium, preferably cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased thermal energy content compared to CMS1; (ii.a) feeding CSM2 to a heat exchanger installed in the circulation loop of the loop reactor, thereby transferring another portion of the thermal energy generated in the reaction vessel to CMS2 and obtaining a cooling medium stream CMS4, which has an increased thermal energy content compared to CMS2; (ii.b) transferring at least a portion of the thermal energy contained in the cooling medium stream CMS4 to a heat transfer medium stream HTMS1 in a heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

10. The hydrogenation process according to claim 8, wherein for the reaction vessel being a loop reactor, the process comprises: (i) transferring at least a portion of the thermal energy generated in the reaction vessel to a cooling medium, preferably cooling medium stream CMS1, to obtain a cooling medium stream CMS2, which has an increased thermal energy content compared to CMS1; (ii) sending a portion (CMS3a) of the cooling medium stream CMS3 obtained from a heat pump PH to a heat exchanger installed in the circulation loop of the loop reactor, thereby transferring a portion of the thermal energy generated in the reaction vessel to the portion CMS3a of the cooling medium stream and obtaining a partial cooling medium stream CMS5, which has an increased thermal energy content compared to CMS3; (iii) combining the partial cooling medium stream CMS5 with the cooling medium stream CMS2 obtained in (i), thereby obtaining a combined cooling medium stream CMS2+CMS5; (iv) feeding the combined cooling medium stream CMS2+CMS5 to the heat pump HP; and transferring at least a portion of the thermal energy contained in the combined cooling medium stream CMS2+CMS5 to a heat transfer medium stream HTMS1 in the heat pump HP, thereby obtaining a heat transfer medium stream HTMS2, which has an increased thermal energy content compared to HTMS1.

11. The hydrogenation process according to any one of claims 1 to 10, wherein at least 20% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via the cooling medium and the heat pump, preferably to the heat transfer medium stream HTMS1 and the heat transfer medium stream HTMS2 respectively.

12. The hydrogenation process according to claim 11, wherein in the case where the heat pump is an absorption heat pump, preferably a type II absorption heat pump, 20% to 50% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via the cooling medium and the heat pump, preferably to the heat transfer medium stream HTMS1 and the heat transfer medium stream HTMS2 respectively.

13. The hydrogenation method according to claim 11, wherein in the case where the heat pump is a compression heat pump, preferably a compression heat pump that generates steam (steam generator), 20% to 100%, preferably 70% to 100% of the thermal energy generated in the reaction vessel is transferred to the heat transfer medium via the cooling medium and the heat pump, preferably to the heat transfer medium stream HTMS1 and the heat transfer medium stream HTMS2 respectively.

14. A reaction system for hydrogenating a compound, preferably for converting a compound having at least one nitro group into the corresponding compound having at least one amino group by hydrogenation, the reaction system comprising: (a) A reactor having: (a.1) Equipment for feeding gaseous and liquid materials into the reactor; (a.2) Equipment for mixing in the reactor; (a.3) An outlet for removing the reaction mixture from the reactor; (a.4) At least one inlet for reintroducing the reaction mixture; (a.5) A loop pipeline fluidly connected to the outlet (a.3) and the inlet (a.4) outside the reactor, the loop pipeline being capable of removing the reaction mixture from the reactor via the outlet (a.3) and reintroducing the reaction mixture into the reactor via the inlet (a.4); (a.6) At least one heat exchanger arranged in the reactor, outside the reactor or in the loop pipeline (a.5), wherein the heat exchanger has at least one inlet (a.6.1) for feeding a cooling medium into the heat exchanger and at least one outlet (a.6.2) for removing the cooling medium from the heat exchanger; (b) A heat pump, the heat pump comprising: (b.1) At least one inlet (b.1.1) for feeding a cooling medium into the heat pump, and at least one outlet (b.1.2) for removing the cooling medium from the heat pump; (b.2) At least one inlet (b.2.1) for feeding a heat transfer medium stream into the heat pump, and at least one outlet (b.2.2) for removing the heat transfer medium stream from the heat pump; wherein the heat pump is constructed to allow thermal energy to be transferred from the cooling medium stream to the heat transfer medium stream; (c) A pipeline fluidly connected to the at least one heat exchanger (a.6) and the heat pump (b), the pipeline being constructed and arranged to (c.1) Allow the cooling medium stream from the at least one outlet (a.6.2) of the heat exchanger to be transferred into the inlet (b.1.1) of the heat pump, and reintroduce the cooling medium stream from the at least one outlet (b.1.2) into the at least one inlet (a.6.1), the at least one outlet for removing the cooling medium from the heat pump, the at least one inlet for feeding the cooling medium into the heat exchanger; and (c.2) allows a heat transfer medium flow to be introduced into the at least one inlet (b.2.1) of the heat pump and allows the heat transfer medium flow to be removed from the at least one outlet (b.2.2) of the heat pump, the at least one inlet being for feeding the heat transfer medium flow into the heat pump and the at least one outlet being for removing the heat transfer medium flow of the heat pump.

15. The reaction system according to claim 14, wherein the heat pump (b) is an absorption heat pump, preferably a class II absorption heat pump, or a compression heat pump, and more preferably the heat pump of (b) is a class II absorption heat pump.

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