Plant and process for recovery of hydrogen and noble gas from a gas mixture

Abstract

The present invention relates to a plant for separation of hydrogen and a noble gas and / or for recovery of hydrogen and a noble gas from a supplied gas mixture, wherein the noble gas is especially argon or helium, comprising a separation means in the form of an LOHC hydrogenation means (3) which comprises at least one LOHC hydrogenation unit (3a) and is configured for chemically bonding hydrogen present in the gas mixture to dehydrogenated LOHC (liquid organic hydrogen carrier) and separating LOHC hydrogenated in this way from the remaining hydrogen-poor gas mixture and discharging said LOHC from the LOHC hydrogenation means (3).

Description

[0001] DESCRIPTION

[0002] Plant and process for recovering hydrogen and noble gas from a gas mixture

[0003] The present invention relates to a system for separating hydrogen and a noble gas and / or for recovering both hydrogen and a noble gas from a supplied gas mixture, wherein the noble gas is in particular argon or helium, with a separation device designed as an LOHC hydrogenation device, which has at least one LOHC hydrogenation unit and is configured to chemically bind hydrogen contained in the gas mixture to dehydrated LOHC (Liquid Organic Hydrogen Carrier) and thus separate hydrogenated LOHC from the remaining hydrogen-poor gas mixture and to remove it from the LOHC hydrogenation device.

[0004] Furthermore, the invention relates to a method for separating hydrogen and a noble gas and / or for recovering both hydrogen and a noble gas from a supplied gas mixture, wherein the noble gas is in particular argon or helium, in which the gas mixture is subjected to LOHC hydrogenation in an LOHC hydrogenation device in order to chemically bind hydrogen contained in the gas mixture to dehydrated LOHC and thus separate hydrogenated LOHC from the remaining hydrogen-poor gas mixture and remove it from the LOHC hydrogenation device.

[0005] In various metallurgical applications, hydrogen is used to create a reductive atmosphere. In particular, hydrogen is used as a deoxidizing agent in annealing furnaces to remove oxygen from the atmosphere, thus creating a controlled environment that prevents or at least reduces the formation of oxides on the surface of the materials being annealed, thereby optimizing the annealing process for various materials. Therefore, a hydrogen atmosphere is useful for annealing hard alloys, ceramic materials, magnetic materials, and rare refractory metals.

[0006] It is known to combine other gases such as nitrogen and argon with hydrogen to create specific atmospheres for various annealing processes. For example, by adding argon (Ar) as an inert gas, the hydrogen content or partial pressure of hydrogen in the protective atmosphere can be precisely controlled. Typical hydrogen-rich gases used in annealing furnaces have a composition of 40 to 98 mol% hydrogen and, in addition to hydrogen and argon, also contain traces of nitrogen (N₂), carbon monoxide (CO), carbon dioxide (CO₂), water (H₂O), hydrogen sulfide (H₂S), and other impurities.

[0007] The hydrogen used to create a specific atmosphere in annealing furnaces, as well as the argon used as an inert gas, are not consumed or only consumed to a small extent during the annealing process and are often subsequently used for thermal energy recovery or in a combined heat and power plant (CHP). To recover the hydrogen from these annealing furnaces instead of using it for thermal energy recovery, the gas from the furnace can be compressed and then purified using pressure swing adsorption (PSA), which removes all components from the gas except for the hydrogen itself.

[0008] Separation using PSA has the disadvantage that argon cannot be recovered, or only with very high effort. Furthermore, argon adsorbs relatively poorly under the technical conditions, which results in very large adsorption beds.

[0009] However, the recovery of argon is desirable, as it is required to create the protective atmosphere during the annealing process, and thus recovery makes the process more cost-effective, especially since argon is very expensive.

[0010] US Patent 2021 / 0188630 A1 discloses a generic system for purifying hydrogen. This system comprises a source for the gas to be purified, a compressor for compressing the gas, and a reactor that can be filled with a dehydrated LOHC material via an LOHC source. The gas to be purified is fed into the reactor, which is filled with the dehydrated LOHC material, where hydrogen contained in the gas mixture is chemically bound to the LOHC and thus separated from the remaining gas mixture.

[0011] DE 10 2015 219 306 A1 discloses a reactor for loading and / or unloading LOHC with hydrogen.

[0012] The existing systems have proven their worth in practice. However, efforts are focused on further optimizing the processes.

[0013] The object of the present invention is to create an optimized system and an optimized process of the type mentioned above, which makes it possible to separate hydrogen and a noble gas from each other or to recover both hydrogen and a noble gas from a gas mixture, wherein the noble gas is in particular argon or helium.According to the invention, this problem is solved in a system for the separation of hydrogen and noble gas of the type mentioned above by providing an LOHC dehydrogenation unit with at least one LOHC dehydrogenation unit, which is connected to the LOHC hydrogenation unit and is designed to dehydrogenate hydrogenated LOHC supplied to it by the LOHC hydrogenation unit, releasing hydrogen, and by thermally coupling the LOHC hydrogenation unit and the LOHC dehydrogenation unit in such a way that the waste heat, in particular the latent heat of the hydrogenation reaction, is used in the LOHC hydrogenation unit to carry out the dehydrogenation reaction in the LOHC dehydrogenation unit.

[0014] In a process of the type mentioned at the outset, the invention is solved by supplying hydrogenated and separated LOHC in the LOHC hydrogenation unit to an LOHC dehydrogenation unit and dehydrogenating it there with the release of hydrogen, and by using the waste heat, in particular the latent heat of the hydrogenation reaction, to carry out the dehydrogenation reaction in the LOHC dehydrogenation unit.

[0015] The invention is based on the concept of separating hydrogen from a noble gas or from a gas mixture containing a noble gas by chemically binding the hydrogen to the dehydrated LOHC (Liquid Organic Hydrogen Carrier), thereby hydrogenating the LOHC. The hydrogenated LOHC is then separated from the remaining gas, which is hydrogen-depleted and thus low in hydrogen but rich in noble gas, and fed to the LOHC dehydration unit. There, the LOHC is dehydrated. The hydrogen released during dehydration is removed from the LOHC dehydration unit and can be stored as desired or reintroduced elsewhere or as fuel.

[0016] According to the invention, the heat released during dehydration is used to carry out the dehydration reaction in the LOHC dehydration device, thereby enabling the LOHC hydrogenation process and thus the separation of hydrogen into noble gas to be carried out in an energy-efficient manner.

[0017] According to one embodiment of the invention, the LOHC dehydration unit is connected to the LOHC hydrogenation unit in order to recycle dehydrated LOHC at the LOHC hydrogenation unit. Preferably, heat exchangers are provided to preheat the hydrogenated LOHC stream entering the LOHC dehydration unit using the waste heat from the dehydrated LOHC stream leaving the LOHC dehydration unit.

[0018] This design creates a closed loop through which hydrogen can be separated in a more or less closed cycle optimized with regard to energy consumption. In particular, the efficient separation of gas and noble gas is possible. The process according to the invention is particularly suitable if the supplied gas mixture contains at least 5 vol% hydrogen, in particular at least 10 vol% hydrogen, and preferably at least 20 vol% hydrogen, and / or the supplied gas mixture contains at least 3 vol% of the noble gas, in particular at least 10 vol% of the noble gas, and preferably at least 20 vol% of the noble gas.In principle, the LOHC hydrogenation device can comprise a single LOHC hydrogenation unit configured such that the hydrogenation reaction takes place at a temperature in the range of 280 °C to 350 °C, particularly up to 320 °C, and a pressure of 5 bar to 30 bar, preferably a pressure of 10 bar to 30 bar. Thus, the hydrogenation reaction in the LOHC hydrogenation unit occurs at a comparatively high temperature of up to 350 °C.

[0019] Depending on the reaction temperature, the H₂ partial pressure must be selected, with suitable pressures in the range of 5 to 30 bar, particularly 10 to 30 bar. For example, the LOHC system benzyltoluene / perhydrobenzyltoluene can be used. To separate the hydrogenated LOHC or LOHC mixture from the remaining hydrogen-depleted gas mixture, i.e., the H₂-depleted gas phase, the LOHC and the gas mixture are preferably cooled, and then the pressure of the hydrogenated LOHC is reduced. The hydrogenated LOHC is then directed to a separator to remove physically dissolved gases. This offgas can be returned to the feed gas stream.

[0020] According to an alternative embodiment of the present invention, the LOHC hydrogenation device comprises at least two, in particular exactly two, LOHC hydrogenation units connected in series to be successively flowed through by the supplied gas mixture and to chemically bind the hydrogen contained therein to dehydrated LOHC, wherein the second LOHC hydrogenation unit, through which the gas mixture flows last, is designed to separate the hydrogenated LOHC from the remaining hydrogen-deficient gas mixture and to discharge it from the LOHC hydrogenation device. Thus, in the process according to the invention, the LOHC hydrogenation is carried out in several, in particular exactly two, LOHC hydrogenation units connected in series within the LOHC hydrogenation device.In the first LOHC hydrogenation unit, a portion of the LOHC is hydrogenated, and the gas mixture containing hydrogenated and unhydrogenated LOHC is fed to the subsequent hydrogenation unit(s), where the LOHC is further hydrogenated. Finally, the hydrogenated LOHC is separated from the remaining hydrogen-poor gas mixture in the last hydrogenation unit.

[0021] In a further embodiment of this configuration, the LOHC hydrogenation unit is designed such that the hydrogenation reaction takes place in the first LOHC hydrogenation unit at a higher temperature than in the second LOHC hydrogenation unit, wherein, in particular, the hydrogenation reaction in the first LOHC hydrogenation unit takes place at a temperature in the range of 280°C to 350°C, preferably up to 320°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and wherein, in particular, the hydrogenation reaction in the second LOHC hydrogenation unit takes place at a temperature in the range of 100°C to 270°C, preferably 200°C to 250°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and / or wherein, in particular, the hydrogenation reactions in the two LOHC hydrogenation units take place at the same pressure.

[0022] The process according to the invention is characterized in this embodiment by the fact that the hydrogenation reaction in the first LOHC hydrogenation unit takes place at a higher temperature than in the second LOHC hydrogenation unit, wherein, in particular, the hydrogenation reaction in the first LOHC hydrogenation unit takes place at a temperature in the range of 280°C to 350°C, preferably up to 320°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and wherein, in particular, the hydrogenation reaction in the second LOHC hydrogenation unit takes place at a temperature of 100°C to 270°C, preferably 200°C to 250°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and / or wherein, in particular, the hydrogenation reactions take place at the same pressure.

[0023] In this embodiment, hydrogenation takes place in the LOHC hydrogenation units at decreasing temperatures. Based on the preceding example, the hydrogenation reaction in the first LOHC hydrogenation unit occurs at a temperature in the range of 280 °C to 350 °C, particularly up to 320 °C, while the LOHC hydrogenation in the second LOHC hydrogenation unit takes place at a temperature in the range of 230 °C. This is done to achieve a further reduction of hydrogen in the gas mixture at a low partial pressure of hydrogen, thus reducing the amount of hydrogen leaving the hydrogenation unit with the noble gas stream (degree of hydrogenation, doh, increases). The hydrogenation reactions in both LOHC hydrogenation units can take place at the same pressure if the pressure losses in the LOHC hydrogenation units are neglected.

[0024] In an embodiment of the invention, the LOHC dehydration device can have a single LOHC dehydration unit configured such that the dehydration reaction takes place at a temperature that is lower, in particular at least 5°C lower, than the temperature at which the hydrogenation reaction takes place in the single or the first LOHC hydrogenation unit, wherein the temperature is in particular at least 280°C and preferably at least 290°C, and that the dehydration reaction takes place at a pressure that is lower than the pressure at which the hydrogenation reaction takes place in the single or the first LOHC hydrogenation unit, wherein the pressure is preferably in the range of 1 to 5 bar.

[0025] Alternatively, the LOHC dehydrogenation device may be provided to have at least two, in particular exactly two, LOHC dehydrogenation units connected in series in order to be successively flowed through by the hydrogenated LOHC supplied by the LOHC hydrogenation device and to dehydrogenate it with the release of hydrogen, wherein, in particular, the LOHC dehydrogenation unit last through which the LOHC flowed is connected to the LOHC hydrogenation device in order to recycle dehydrogenated LOHC to the LOHC hydrogenation device.

[0026] Advantageously, the LOHC dehydrogenation device is designed such that the dehydrogenation reaction in the first LOHC dehydrogenation unit, i.e., the one through which the LOHC first flows, takes place at a temperature that is lower, in particular at least 5°C lower, than the temperature at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit, wherein the temperature is in particular at least 280°C and preferably at least 290°C, and that the dehydrogenation reaction takes place at a pressure that is lower than the pressure at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit, wherein the pressure is preferably in the range of 1 to 5 bar.

[0027] In the process according to the invention, a portion of the LOHC is dehydrated in the first LOHC dehydration unit, and the gas mixture containing hydrogenated and unhydrogenated LOHC is fed to the further dehydration unit(s), where the LOHC is further dehydrated, wherein, in particular, dehydrated LOHC is recycled from the last dehydration unit to the hydrogenation unit, and preferably the waste heat from the LOHC stream leaving the last dehydration unit is used to preheat the LOHC stream entering the first dehydration unit.

[0028] For heat integration, the outgoing LOHC stream from the second LOHC dehydration unit is used to warm the stream entering the first LOHC dehydration unit.

[0029] According to a preferred embodiment of the system according to the invention, the LOHC hydrogenation unit and the LOHC dehydrogenation unit are thermally coupled such that the waste heat, in particular latent heat, of the hydrogenation reaction in the single or first LOHC hydrogenation unit is used to carry out the dehydrogenation reaction in the single or first LOHC dehydrogenation unit. Preferably, the single or first hydrogenation unit and the single or first dehydrogenation unit form a single structural unit, for example, in the form of a shell-and-tube reactor or a catalytically coated heat exchanger, in particular a plate heat exchanger, in which LOHC is hydrogenated on one side and dehydrogenated on the other.

[0030] In this embodiment, only a portion of the hydrogen is released in the first dehydrogenation unit. The waste heat from the LOHC hydrogenation system, and in particular from the first LOHC hydrogenation unit, can be used for this purpose. Technically, a hydrogenation / dehydrogenation reactor can be provided, for example, a shell-and-tube reactor, in which LOHC is hydrogenated on one side and dehydrogenated on the other. Alternatively, a catalytically coated heat exchanger can be used, such as a catalytically coated plate heat exchanger, in which LOHC is hydrogenated on one side and dehydrogenated on the other. In principle, it is also possible to provide two separate reactors connected via a heat transfer medium and thus thermally coupled. Suitable heat transfer media include, for example, thermal oil or a steam-to-water heat exchanger.

[0031] In the second LOHC dehydration unit, the LOHC is further dehydrated at higher temperatures. This requires an external heat source. For example, a hydrogen-containing partial stream from the current process can be oxidized and the heat generated utilized. Alternatively, heating with electric current from the LOHC is possible.

[0032] Accordingly, the process according to the invention is characterized in that the waste heat, in particular the latent heat of the hydrogenation reaction in the single or in the first LOHC hydrogenation unit, is used to carry out the dehydrogenation reaction in the single or the first LOHC dehydrogenation unit, wherein, in particular, the single or first hydrogenation unit forms a structural unit with the single or first dehydrogenation unit, preferably in the form of a tube bundle reactor or a catalytically coated heat exchanger, in particular a plate heat exchanger, in which LOHC is hydrogenated on one side and LOHC is dehydrogenated on the other side.

[0033] The system according to the invention can have a compression device on the inlet side, which is designed to compress a supplied gas mixture, in particular to a pressure of 10 to 60 bar, preferably to a pressure of 15 to 30 bar. The compression usually takes place in several stages with intermediate cooling and optionally condensation / separation of water.

[0034] According to a further aspect of the present invention, the system according to the invention can have an adsorptive separation device which is upstream of the LOHC hydrogenation device and is designed to separate components from the gas mixture which are not desired for the LOHC hydrogenation by adsorption from the gas mixture, or that it has an adsorptive separation device which is downstream of the LOHC hydrogenation device and is designed to remove LOHC components from the hydrogen-poor gas mixture by adsorption.

[0035] According to a further embodiment of the invention, hydrogen released by LOHC dehydrogenation and discharged from the LOHC dehydrogenation unit is compressed before further use, particularly before storage. It may be advantageous to purify the hydrogen before or after compression and thus remove impurities. In this case, a compressor is connected to a hydrogen outlet of the LOHC dehydrogenation unit to compress a hydrogen-rich gas stream exiting the LOHC dehydrogenation unit. For hydrogen purification, a purification device, for example in the form of an adsorptive separation device, can be provided between the LOHC dehydrogenation unit and the compressor or downstream thereof.

[0036] In a preferred embodiment of the system according to the invention, it has an adsorptive separation device which is upstream of the LOHC hydrogenation device and is designed to separate components from the gas mixture that are not desired for LOHC hydrogenation by adsorption from the gas mixture, or that it has an adsorptive separation device which is downstream of the LOHC hydrogenation device and is designed to remove LOHC components from the hydrogen-poor gas mixture by adsorption.

[0037] According to one embodiment of this system, adsorptive separation is achieved through pressure swing adsorption (PSA). Accordingly, the adsorptive separation device is designed as, or incorporates, a PSA unit. The PSA unit can be filled with layers of different adsorbents to reduce the total amount of adsorbent required. Typically, various zeolites with different pore diameters, silica, and activated carbons are used as adsorbents.

[0038] In the case of using a PSA device, the hydrogen and noble gas-rich gas mixture - i.e., the Fh / Ar mixture - will leave the PSA device at approximately the PSA inlet pressure.

[0039] Alternatively / additionally, the adsorptive separation unit can include or be formed by a temperature swing adsorption (TSA) unit, in which the adsorptive separation is carried out by temperature swing adsorption. Here, in addition to an optional pressure swing, the temperature is also increased during desorption, which further reduces the loading. For this purpose, a gas, preferably a portion of the hydrogen gas obtained in the LOHC dehydrogenation unit, is heated to 100 to 400°C, preferably to 150 to 300°C, and passed through the clean beds during desorption to heat them and further reduce the partial pressure. The adsorptive separation unit can also include or consist of a spent bed (adsorptive guard bed). The installation of a spent bed is advantageous if the supplied gas mixture, i.e., the feed gas stream, contains very few components other than hydrogen and argon.This is usually the case when the impurities in the argon / hydrogen mixture or the noble gas / hydrogen mixture are below 1 mol% and preferably below 0.5 mol%.

[0040] In a further embodiment of the invention, it is provided that after the LOHC hydrogenation, the hydrogen-deficient gas mixture is purified in order to separate any remaining hydrogen. This purification preferably takes place between the LOHC hydrogenation and before an absorptive separation of the gas mixture.

[0041] For this purpose, a corresponding purification device is provided downstream of the LOHC hydrogenation device, which is designed to separate hydrogen that is still contained in the hydrogen-poor gas mixture obtained by treating the gas mixture in the LOHC hydrogenation device from the gas mixture; the purification device is then preferably provided in the flow direction of the gas mixture between the LOHC hydrogenation device and the absorptive separation device.

[0042] To reduce the hydrogen molar fraction in the noble gas, the noble gas can, for example, be freed from hydrogen oxidatively. For this purpose, a purification device is provided, which is designed to remove hydrogen from the noble gas oxidatively and which, in particular, includes a catalyst, preferably a noble metal-based catalyst. Accordingly, the oxidative removal of hydrogen from the noble gas—especially on the retentate side of the membrane—is carried out by the targeted addition of oxygen and the reaction on a catalyst.

[0043] The noble gas (argon) must then be dried again. A suitable drying unit is provided for this purpose. The oxygen required for oxidation can be obtained from water electrolysis or from an air separation unit. In the latter case, the argon can remain in the oxygen.

[0044] To avoid the technically complex stoichiometric addition of oxygen, a changeover bed can be used. In one operating mode, a catalytically active material is oxidized, particularly by air, and in another operating mode, the oxygen from this material is used to oxidize hydrogen from the hydrogen- and noble gas-rich gas mixture.

[0045] Alternatively, hydrogen can be removed from the noble gas by using a membrane designed to separate the hydrogen and the recovered noble gas. Accordingly, the purification device of the system according to the invention includes a membrane designed to separate the hydrogen and the recovered noble gas.

[0046] In a further embodiment of this design, it is provided that a portion of the noble gas from the retentate side of the membrane is used as a noble gas sweep on the permeate side of the membrane.

[0047] Furthermore, the permeate of the membrane can be recycled to the compression device and / or a TSA device in which step b) is carried out, for which purpose in the system according to the invention the permeate side of the membrane is connected to the compression device and / or a TSA device of the adsorptive separation device in order to recycle the permeate of the membrane, i.e. hydrogen-rich gas, to the compression device and / or to the TSA device.

[0048] The following are exemplary embodiments of a system according to the invention for recovering hydrogen and noble gas from a gas mixture, with reference to the accompanying drawing. The drawing shows

[0049] Figure 1 shows a schematic representation of an embodiment of the system according to the first aspect of the present invention.

[0050] Figure 2 shows a first embodiment of a system according to the second aspect of the present invention in schematic representation,

[0051] Figure 3 shows a second embodiment of a system according to the second aspect of the present invention in schematic representation.

[0052] Figure 4 shows a third embodiment of a system according to the second aspect of the present invention in schematic representation.

[0053] Figure 5 shows a circuit diagram for a two-stage LOHC hydrogenation followed by a two-stage LOHC dehydrogenation in two LOHC hydrogenation reactors and two

[0054] LOHC dehydrogenation reactors, and Figure 6 shows the operating points of the LOHC hydrogenation reactors and the LOHC dehydrogenation reactors from Figure 5 for the example of using the LOHC system benzyltoluene / perhydro benzyltoluene.

[0055] Figure 1 shows an embodiment of a plant according to the invention for producing hydrogen and a noble gas – here argon – from a gas mixture according to the first aspect of the present invention. The supplied gas mixture contains at least 5 vol% hydrogen, in particular at least 10 vol% hydrogen and preferably at least 20 vol% hydrogen, as well as at least 3 vol% of the noble gas, in particular at least 10 vol% of the noble gas and preferably at least 20 vol% of the noble gas.

[0056] The system comprises a compression device 1, which is configured to compress a supplied gas mixture, i.e., a feed gas stream, to a predetermined pressure. The system further comprises an adsorptive separation device 2, which is downstream of and connected to the compression device 1. In the present embodiment, the adsorptive separation device 2 is configured as a PSA device, which is designed to adsorb from the supplied gas mixture all components that are detrimental to exclusive LOHC hydrogenation, thus obtaining a hydrogen- and noble gas-rich gas mixture.

[0057] Furthermore, the system includes a separation device in the form of an LOHC hydrogenation unit 3, which is connected to an outlet of the adsorptive separation unit 2 for the hydrogen- and noble gas-rich gas mixture. The LOHC hydrogenation unit 3 is designed to chemically bind hydrogen contained in the hydrogen- and noble gas-rich gas mixture to dehydrated LOHC and to separate the hydrogenated LOHC in this way from the remaining hydrogen-poor gas mixture, consisting mainly of argon as well as residual hydrogen and impurities, and to discharge it from the LOHC hydrogenation unit 3.

[0058] The system further comprises a purification unit 4, which is connected to an outlet of the LOHC hydrogenation unit 3 for the noble gas obtained as a result of the LOHC hydrogenation and is designed to purify the supplied noble gas and, in particular, to remove any remaining hydrogen contained therein. Furthermore, an LOHC dehydrogenation unit 5 of the system is connected to an LOHC outlet of the LOHC hydrogenation unit 3. This unit is designed to dehydrogenate the LOHC hydrogenated and separated in the LOHC hydrogenation unit 3 and thereby release hydrogen, which is then routed from the LOHC dehydrogenation unit 5 for further use.

[0059] An LOHC outlet of the LOHC dehydrogenation unit 5 is connected to an LOHC inlet of the LOHC hydrogenation unit 3 to recycle dehydrogenated - i.e. unloaded - LOHC material to the LOHC hydrogenation unit.

[0060] Not shown in the drawing is the provision of heat exchangers to preheat the hydrogenated LOHC stream entering the LOHC dehydrogenation unit 5 using the waste heat from the LOHC stream leaving the LOHC dehydrogenation unit 5.

[0061] A purification unit 6 is connected to a hydrogen outlet of the LOHC dehydrogenation unit 5 in order to purify the hydrogen released by the LOHC dehydrogenation, particularly by absorption. It is not shown in detail that a compressor is provided upstream of the purification unit 6 to compress the hydrogen stream leaving the LOHC dehydrogenation unit 5 for subsequent storage.

[0062] During operation, the feed gas stream is compressed in the compression unit 1 to the inlet pressure of the adsorptive separation unit 2, i.e., the PSA unit, which is 10 to 60 bar, preferably 15 to 30 bar. In the PSA unit, all components that are detrimental to the subsequent LOHC hydrogenation are separated from the feed gas stream. The PSA offgas, which contains the adsorbed components of the feed gas stream, is removed from the adsorptive separation unit 2 and fed to a combined heat and power plant 7.

[0063] The hydrogen- and noble gas-rich gas mixture obtained after adsorptive separation, i.e., the hydrogen / argon mixture, is fed to the LOHC hydrogenation unit 3, where the hydrogen binds to dehydrogenated LOHC. The hydrogenated LOHC is then fed to the LOHC dehydrogenation unit 5 and dehydrogenated there, releasing hydrogen.

[0064] Dehydrated, i.e., unloaded, LOHC is then recycled to the LOHC hydrogenation unit 3.

[0065] The hydrogen released by dehydration in the LOHC dehydration unit 5 is removed from the LOHC dehydration unit 5, compressed in the compressor and purified in the cleaning unit 6 in order to store it, for example, in a tank system.

[0066] The noble gas remaining in the LOHC hydrogenation unit 3 after the LOHC hydrogenation - argon - is fed to the purification unit 4 in order to remove or at least reduce any remaining molar fraction of hydrogen contained therein.

[0067] Figure 2 shows an embodiment of a plant according to the invention for producing hydrogen and noble gas – here argon – from a gas mixture according to the second aspect of the present invention. This plant differs from the plant described above according to the first aspect of the present invention in that the LOHC hydrogenation unit 3 is not located downstream of the adsorptive separation unit 2, but is provided between the compression unit 1 and the adsorptive separation unit 2.

[0068] Specifically, the system comprises a compression device 1, which is configured to compress a supplied gas mixture, i.e., a feed gas stream, to a predetermined pressure. The system further comprises a separation device in the form of an LOHC hydrogenation unit 3, which is connected to the compression device 1 and configured to chemically bind hydrogen contained in the supplied gas mixture to dehydrated LOHC, thereby separating the hydrogenated LOHC from the remaining hydrogen-poor gas mixture and removing it from the LOHC hydrogenation unit.

[0069] The system further comprises an adsorptive separation device 2, which is connected to an outlet of the LOHC hydrogenation device 3 for the remaining gas mixture and is designed to remove LOHC components from the hydrogen-deficient gas mixture by absorption, thereby obtaining a gas that consists exclusively of argon, with the exception of residual hydrogen and other impurities. In the present embodiment, the adsorptive separation device 2 is designed as a PSA device. The system also includes a purification device 4, which is connected to an outlet of the adsorptive separation device 2 for the noble gas and is designed to purify the supplied noble gas and, in particular, to remove any remaining hydrogen contained therein.

[0070] A LOHC dehydrogenation unit 5 of the system is connected to an LOHC outlet of the LOHC hydrogenation unit 3. The dehydrogenation unit 5 is configured to re-dehydrogenate the LOHC hydrogenated in the LOHC hydrogenation unit 3, releasing hydrogen. A LOHC outlet of the LOHC dehydrogenation unit 5 is connected to an LOHC inlet of the LOHC hydrogenation unit 3 to recycle dehydrogenated—i.e., unloaded—LOHC material to the LOHC hydrogenation unit 3. A heat exchanger may also be provided to preheat the hydrogenated LOHC stream entering the LOHC dehydrogenation unit 5 using the latent heat of the LOHC stream leaving the LOHC dehydrogenation unit 5.

[0071] A purification unit 6 is connected to a hydrogen outlet of the LOHC dehydrogenation unit 5. This purification unit is designed to purify the hydrogen released during the LOHC dehydrogenation process. It is not shown in detail here that a compressor is provided upstream of the purification unit to compress the hydrogen stream exiting the LOHC dehydrogenation unit 5 for subsequent storage.

[0072] During operation, the feed gas stream is compressed in the compression unit 1 to the pressure of 10 bar for the hydrogenation reaction, which is then increased to 30 bar. The compressed gas mixture is fed to the LOHC hydrogenation unit 3, where the hydrogen is chemically bound to dehydrogenated LOHC. The hydrogenated LOHC in this way—i.e., the loaded LOHC—is fed to the LOHC dehydrogenation unit 5 and dehydrogenated there, with the addition of hydrogen. The dehydrogenated, i.e., unloaded, LOHC is then recycled back to the LOHC hydrogenation unit 3. The hydrogen released by the dehydrogenation in the LOHC dehydrogenation unit 5 is removed from the LOHC dehydrogenation unit 5, compressed in the compressor, and purified in the cleaning unit 6 for storage, e.g., in a tank system.

[0073] The hydrogen-depleted (i.e., hydrogen-poor) gas mixture, after treatment in the LOHC hydrogenation unit 3, is passed to the absorptive separation unit 2, where any remaining LOHC impurities are removed. Subsequently, the gas mixture is treated in the purification unit 4 as already described, in order to purify the obtained noble gas and, in particular, to remove any remaining hydrogen.

[0074] Figure 3 shows a specific embodiment of the system depicted in Figure 2. In this embodiment, the purification unit 4 has a membrane to separate hydrogen and argon. The membrane can be a low-temperature membrane, e.g., a polymer-based membrane or a palladium membrane. The membrane is designed such that hydrogen deflates through the membrane significantly faster than argon. As can be seen in Figure 3, the purification unit 4 is configured such that a portion of the argon product is used as feed at the membrane of the purification unit 4. The resulting hydrogen / argon stream, as permeate of the membrane on the purification unit 4, is recycled to the compression unit 1, where the hydrogen and argon are largely recovered. For this purpose, the permeate side of the membrane is connected to the compression unit 1 via a return line 8.

[0075] Figure 4 shows a system according to the second aspect of the present invention, as explained with reference to Figure 2. In this embodiment, the purification device 4 is designed as an oxidative purification device for the oxidative removal of hydrogen from the noble gas. For this purpose, it includes a catalyst, in particular a noble metal-based catalyst. The oxidative removal of hydrogen from the noble gas is achieved by the targeted addition of oxygen (O₂) according to the reaction H₂ + I / 2 O₂ = H₂O. Subsequently, the argon must be dried again, for which a drying device (not shown) is provided. The oxygen can be obtained from water electrolysis or from an air separation unit.

[0076] Figure 5 shows a circuit consisting of an LOHC hydrogenation unit 3 followed by an LOHC dehydrogenation unit 5. As can be clearly seen in Figure 5, the LOHC hydrogenation unit 3 has two LOHC hydrogenation units 3a, 3b, which are also called LOHC hydrogenation reactors and are connected in series so that they are sequentially flowed through by a supplied gas mixture to chemically bind the H2 contained in the gas mixture to dehydrogenated LOHC.

[0077] In the first LOHC hydrogenation unit 3a, the hydrogenation reaction takes place at a temperature in the range of 280 °C to 350 °C, preferably up to 320 °C. The partial pressure of H₂ is selected depending on the reaction temperature, with suitable pressures between 5 and 30 bar, preferably between 10 and 30 bar. In the first LOHC hydrogenation unit 3a, only a portion of the hydrogen contained in the gas mixture is chemically bound to dehydrated LOHC. The remaining gas mixture, depleted of H₂ or low in hydrogen, is fed together with the LOHC to the second LOHC hydrogenation unit 3b, where the gas mixture is further hydrogenated and thus becomes even lower in hydrogen.The hydrogenation reaction takes place in the second LOHC hydrogenation unit 3b at lower temperatures than in the first LOHC hydrogenation unit 3a, for example at a temperature in the range of 230 °C to 270 °C, in order to achieve a further depletion of hydrogen in the gas mixture at low residual partial pressure of hydrogen, so that little hydrogen is contained in the hydrogen-poor gas mixture and leaves the second LOHC hydrogenation unit 3b.

[0078] The hydrogenated LOHC is then separated from the hydrogen-depleted gas phase. This can be achieved by cooling the LOHC and the hydrogen-depleted gas mixture, thus reducing the amount of LOHC vapor in the gas phase. The pressure of the hydrogenated LOHC is then reduced, and the LOHC is directed to a separator to remove physically dissolved gases. This off-gas can be returned to the compression unit 1.

[0079] The hydrogenated or loaded LOHC is fed via an LOHC outlet from the second LOHC hydrogenation unit 3a to the first LOHC dehydrogenation unit 5a for dehydrogenation. LOHC dehydrogenation takes place at low pressures, for example, between 1 bar and 5 bar. In the first LOHC dehydrogenation unit 5a, only a portion of the hydrogen is released. Waste heat from the first LOHC hydrogenation unit 3a is used for this purpose. This can be achieved in a reactor, such as a tube bundle reactor, where LOHC is hydrogenated on one side and dehydrogenated on the other. The hydrogen gas released in the first LOHC dehydrogenation unit 5a, as well as the still hydrogenated or already dehydrogenated LOHC, are fed into the second LOHC dehydrogenation unit 5b, where the LOHC is further dehydrogenated at higher temperatures. An external heat source is used for this. The dehydrogenated, i.e.,Unloaded LOHC is recycled via an LOHC outlet of the second LOHC dehydrogenation unit 5b to the first LOHC hydrogenation unit 3a of the LOHC hydrogenation system 3 for reuse. The LOHC stream exiting the second LOHC dehydrogenation unit 5b can be used to preheat the gas mixture supplied to the first LOHC hydrogenation unit 3a for hydrogenation. The hydrogen released during hydrogenation exits the second LOHC dehydrogenation unit 5b for further use.

[0080] Figure 6 (derived from the original graphic Rüde, Timo, et al. "Benzyltoluene / perhydro benzyltoluene-pushing the performance limits of pure hydrocarbon liquid organic hydrogen carrier (LOHC) systems." Sustainable Energy & Fuels 6.6 (2022): 1541-1553) shows the operating point of the first LOHC hydrogenation unit 3a, the operating range of the second LOHC hydrogenation unit 3b, and the operating points of the LOHC dehydrogenation units 5a, 5b from Figure 5 for the example of using the benzyltoluene / perhydro benzyltoluene LOHC system. The operating range for the second LOHC hydrogenation unit 3b can in principle also be extended to temperatures in the range of 50 °C to 250 °C, preferably 80 °C to 150 °C, in order to allow lower H2 partial pressures at the outlet of the second LOHC hydrogenation unit 3b for the gas mixture.

[0081] The use of other LOHC systems is also possible. In principle, the method is applicable to all reversibly hydrogenatable and dehydrogenatable liquid organic compounds and their use as LOHC systems whose hydrogenation-dehydrogenation equilibria exhibit a pronounced pressure and temperature dependence. Suitable examples of such LOHC systems are corresponding pairs of aromatic and alicyclic compounds, heteroaromatic and heteroalicyclic compounds, and pairs of ketones and their corresponding secondary alcohols. Pairs of aromatic ketones and alicyclic secondary alcohols are also suitable.

[0082] Reference symbol list

[0083] 1. Compression device 2. Adsorptive separation device

[0084] 3 LOHC hydrogenation unit

[0085] 3a first LOHC hydrogenation unit

[0086] 3b second LOHC hydrogenation unit

[0087] 4. Purification unit 5. LOHC dehydrogenation unit

[0088] 5a first LOHC dehydrogenation unit

[0089] 5b second LOHC dehydration unit

[0090] 6 Cleaning equipment

[0091] 7 Combined heat and power plant 8 Return line

Claims

REQUIREMENTS 1. A system for separating hydrogen and a noble gas and / or for recovering both hydrogen and a noble gas from a supplied gas mixture, wherein the noble gas is in particular argon or helium, comprising a separation device designed as an LOHC hydrogenation unit (3), which has at least one LOHC hydrogenation unit (3a) and is configured to chemically bind hydrogen contained in the gas mixture to dehydrated LOHC (Liquid Organic Hydrogen Carrier) and thus separate hydrogenated LOHC from the remaining hydrogen-poor gas mixture and discharge it from the LOHC hydrogenation unit (3), characterized in that an LOHC dehydrogenation unit (5) with at least one LOHC dehydrogenation unit is provided, which is connected to the LOHC hydrogenation unit (3) and is configured to dehydrogenate hydrogenated LOHC supplied to it by the LOHC hydrogenation unit (3) with the release of hydrogen.and that the LOHC hydrogenation unit (3) and the LOHC dehydrogenation unit (5) are thermally coupled to each other in such a way that the waste heat, in particular the latent heat of the hydrogenation reaction, is used in the LOHC hydrogenation unit (3) to carry out the dehydrogenation reaction in the LOHC dehydrogenation unit (5).

2. Plant according to claim 1, characterized in that the LOHC hydrogenation device (3) has a single LOHC hydrogenation unit which is designed such that the hydrogenation reaction takes place at a temperature in the range of 280°C to 350°C, preferably up to 320°C, and a pressure of 5 to 30 bar, preferably a pressure of 10 to 30 bar.

3. Plant according to claim 1, characterized in that the LOHC hydrogenation device (3) comprises at least two, in particular exactly two, LOHC hydrogenation units (3a, 3b) which are connected in series in order to be successively flowed through by the supplied gas mixture and to chemically bind hydrogen contained therein to dehydrated LOHC, wherein the second LOHC hydrogenation unit (3a) through which the gas mixture flows last is designed to separate hydrogenated LOHC from the remaining hydrogen-poor gas mixture and to remove it from the LOHC hydrogenation device (3).

4. The apparatus according to claim 3, characterized in that the LOHC hydrogenation unit (3) is configured such that the hydrogenation reaction in the first LOHC hydrogenation unit (3a) takes place at a higher temperature than in the second LOHC hydrogenation unit (3b), wherein, in particular, the hydrogenation reaction in the first LOHC hydrogenation unit (3a) takes place at a temperature in the range of 280°C to 350°C, preferably up to 320°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and wherein, in particular, the hydrogenation reaction in the second LOHC hydrogenation unit (3b) takes place at a temperature in the range of 100°C to 270°C, preferably 200°C to 250°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and / or wherein, in particular, the hydrogenation reactions in the two LOHC hydrogenation units (3a, 3b) take place at the same pressure.

5. Plant according to one of the preceding claims, characterized in that the LOHC dehydrogenation device (5) is connected to the LOHC hydrogenation device (3) in order to recycle dehydrogenated LOHC to the LOHC hydrogenation device (3), wherein, in particular, Heat exchanger means are provided to preheat the hydrogenated LOHC stream entering the LOHC dehydrogenation device (5) by means of the waste heat from the dehydrogenated LOHC stream leaving the LOHC dehydrogenation device (5).

6. A system according to one of the preceding claims, characterized in that the LOHC dehydrogenation device (5) comprises a single LOHC dehydrogenation unit configured such that the dehydrogenation reaction takes place at a temperature that is lower, in particular at least 5°C lower, than the temperature at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit (3a), wherein the temperature is in particular at least 280°C and preferably at least 290°C, and that the dehydrogenation reaction takes place at a pressure that is lower than the pressure at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit (3a), wherein the pressure is preferably in the range of 1 to 5 bar.

7. Plant according to one of claims 1 to 5, characterized in that the LOHC dehydrogenation device (5) has at least two, in particular exactly two, LOHC dehydrogenation units (5a, 5b) which are connected in series in order to be successively flowed through by the hydrogenated LOHC supplied by the LOHC hydrogenation device (3) and to dehydrogenate it with the release of hydrogen, wherein, in particular, the LOHC dehydrogenation unit (5b) through which the LOHC flowed last is connected to the LOHC hydrogenation device (3) in order to recycle dehydrogenated LOHC to the LOHC hydrogenation device (3).

8. Plant according to claim 7, characterized in that the LOHC dehydrogenation device (5) is designed such that the dehydrogenation reaction takes place in the first, i.e. in the one first through which the LOHC flows. LOHC dehydrogenation unit (5a) takes place at a temperature that is lower, in particular at least 5°C lower, than the temperature at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit (3a), wherein the temperature is in particular at least 280°C and preferably at least 290°C, and that the dehydrogenation reaction takes place at a pressure that is lower than the pressure at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit (3a), wherein the pressure is preferably in the range of 1 to 5 bar.

9. System according to claim 7 or 8, characterized in that the second LOHC dehydration unit (5b) is configured such that the dehydration reaction takes place at a pressure of 1 to 5 bar, in particular at the same pressure as the dehydration reaction in the first LOHC dehydration unit (5a), and / or that the dehydration reaction in the second LOHC dehydration unit (5b) takes place at a higher temperature, in particular at a temperature of at least 300°C, preferably at least 320°C, than in the first LOHC dehydration unit (5a).

10. Plant according to one of claims 6 to 9, characterized in that the LOHC hydrogenation unit (3) and the LOHC dehydrogenation unit (5) are thermally coupled to each other in such a way that the waste heat, in particular the latent heat of the hydrogenation reaction in the single or first LOHC hydrogenation unit (3a), is used to carry out the dehydrogenation reaction in the single or first LOHC dehydrogenation unit (5a), wherein, in particular, the single or first hydrogenation unit (3a) and the single or first dehydrogenation unit (5a) form a structural unit, preferably in the form of a tube bundle reactor or a catalytically coated heat exchanger, in particular a plate heat exchanger. exchangers, form, in which LOHC is hydrogenated on one side and LOHC is dehydrogenated on the other side.

11. Plant according to one of the preceding claims, characterized in that a compressor is connected to a hydrogen outlet of the LOHC dehydrogenation device (5) in order to compress a hydrogen-rich gas stream leaving the LOHC dehydrogenation device (5).

12. System according to claim 11, characterized in that a cleaning device is provided between the LOHC dehydrogenation device (5) and the compressor or downstream of the compressor in order to clean the hydrogen-rich gas stream leaving the LOHC dehydrogenation device (5) before entering the compressor or after leaving it, in particular by adsorptive means.

13. Plant according to one of the preceding claims, characterized in that it has a compression device (1) on the inlet side, which is designed to compress a supplied gas mixture, in particular to a pressure of 10 to 60 bar, preferably to a pressure of 15 to 30 bar.

14. Plant according to one of the preceding claims, characterized in that it has an adsorptive separation device (2) which is upstream of the LOHC hydrogenation device and is configured to separate components from the gas mixture that are not desired for LOHC hydrogenation by adsorption from the gas mixture, or that it has an adsorptive separation device (2) which is downstream of the LOHC hydrogenation device and is configured to to remove LOHC components from the hydrogen-poor gas mixture by adsorption.

15. System according to claim 14, characterized in that the adsorptive separation device (2) is designed as a PSA device or has one and / or that the adsorptive separation device (2) has a TSA device or is formed by one and / or that the adsorptive separation device (2) has a consumable bed or is formed therefrom.

16. Plant according to one of the preceding claims, characterized in that a purification device (4) is provided downstream of the LOHC hydrogenation device (3), which is designed to separate hydrogen that is still contained in the hydrogen-poor gas mixture obtained by the treatment of the gas mixture in the LOHC hydrogenation device (3) from the gas mixture.

17. Plant according to claim 16 and according to claim 14 or 15, characterized in that the purification device (4) is provided in the flow direction of the gas mixture between the LOHC hydrogenation device (3) and the adsorptive separation device (2).

18. Plant according to claim 16 or 17, characterized in that the purification device (4) is designed to oxidatively remove hydrogen from the noble gas, wherein it in particular comprises a catalyst, preferably a noble metal-based catalyst.

19. Plant according to claim 16 or 17, characterized in that the purification device (4) has a membrane designed to separate hydrogen from the noble gas.

20. Plant according to claim 19, characterized in that the purification device (4) is designed such that a portion of the noble gas from the retentate side of the membrane is applied as a noble gas sweep to the permeate side of the membrane.

21. System according to claim 19 or 20, characterized in that the permeate side of the membrane is connected to the compression device (1) and / or a TSA device of the adsorptive separation device (2) in order to recycle the permeate of the membrane, i.e. hydrogen-rich gas, to the compression device (1) and / or to the TSA device.

22. A process for separating hydrogen and a noble gas and / or for recovering both hydrogen and a noble gas from a supplied gas mixture, wherein the noble gas is in particular argon or helium, in which the gas mixture is subjected to LOHC hydrogenation in an LOHC hydrogenation unit (3) in order to chemically bind hydrogen contained in the gas mixture to dehydrated LOHC and thus separate hydrogenated LOHC from the remaining hydrogen-poor gas mixture and discharge it from the LOHC hydrogenation unit, characterized in that hydrogenated and separated LOHC in the LOHC hydrogenation unit (3) is supplied to an LOHC dehydration unit (5) and dehydrated there with the release of hydrogen, and that the waste heat,in particular the latent heat of the hydrogenation reaction in the single or first LOHC hydrogenation unit (3) is used to carry out the dehydrogenation reaction in the LOHC dehydrogenation unit (5).

23. The method of claim 22, characterized in that the LOHC hydrogenation is carried out in a single LOHC hydrogenation unit of the LOHC hydrogenation device (3) takes place, and the hydrogenation reaction is carried out at a temperature in the range of 280 °C to 350 °C, preferably up to 320 °C, and at a pressure of 5 bar to 30 bar, preferably at a pressure of 10 bar to 30 bar.

24. Method according to claim 22, characterized in that the LOHC hydrogenation is carried out in several, in particular exactly two, LOHC hydrogenation units (3a, 3b) of the LOHC hydrogenation device (3) through which the gas mixture flows in series, wherein in the first LOHC hydrogenation unit (3a) a portion of the LOHC is hydrogenated, the gas mixture with hydrogenated and unhydrogenated LOHC is supplied to the further hydrogenation unit(s) (3b), where the LOHC is further hydrogenated and hydrogenated LOHC is separated from the remaining hydrogen-poor gas mixture in the LOHC hydrogenation unit (3b) through which the gas mixture last flows.

25. The method according to claim 24, characterized in that the hydrogenation reaction in the first LOHC hydrogenation unit (3a) takes place at a higher temperature than in the second LOHC hydrogenation unit (3b), wherein, in particular, the hydrogenation reaction in the first LOHC hydrogenation unit (3a) takes place at a temperature in the range of 280°C to 350°C, preferably up to 320°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and wherein, in particular, the hydrogenation reaction in the second LOHC hydrogenation unit (3b) takes place at a temperature of 100°C to 270°C, preferably 200°C to 250°C, and at a pressure of 5 to 30 bar, preferably at a pressure of 10 to 30 bar, and / or wherein, in particular, the hydrogenation reactions take place at the same pressure.

26. A method according to one of claims 22 to 25, characterized in that dehydrated LOHC is transferred to the LOHC dehydration device (5). LOHC hydrogenation unit (3) is recycled, wherein, in particular, the hydrogenated LOHC stream entering the LOHC dehydrogenation unit (5) is preheated by the waste heat of the dehydrogenated LOHC stream leaving the LOHC dehydrogenation unit (5).

27. A method according to any one of claims 22 to 26, characterized in that the dehydration is carried out in a single LOHC dehydration unit of the LOHC dehydration device (5), wherein the dehydration reaction takes place at a temperature that is lower, in particular at least 5°C lower, than the temperature at which the hydrogenation reaction takes place in the single or the first LOHC hydrogenation unit (3a), wherein the temperature is in particular at least 280°C and preferably at least 290°C, and that the dehydration reaction takes place at a pressure that is lower than the pressure at which the hydrogenation reaction takes place in the single or the first LOHC hydrogenation unit (3a), wherein the pressure is preferably in the range of 1 to 5 bar.

28. A method according to claim 22 or 26, characterized in that the LOHC dehydrogenation is carried out in at least two, in particular exactly two, LOHC dehydrogenation units (5a, 5b) of the LOHC dehydrogenation device (5) through which the hydrogenated LOHC flows in series, wherein in the first LOHC dehydrogenation unit (5a) a portion of the LOHC is dehydrogenated, and the gas mixture containing hydrogenated and unhydrogenated LOHC is supplied to the further dehydrogenation unit(s) (5b), where the LOHC is further dehydrogenated, wherein, in particular, dehydrogenated LOHC is recycled from the last dehydrogenation unit (5b) to the hydrogenation device (3) and preferably the waste heat of the LOHC stream leaving the last dehydrogenation unit (5b) is used to preheat the LOHC stream entering the first dehydrogenation unit (5a).

29. Method according to claim 28, characterized in that the dehydration reaction takes place in the first LOHC dehydration unit (5a), i.e., in the LOHC dehydration unit through which the LOHC first flows, at a temperature that is lower, in particular at least 5°C lower, than the temperature at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit (3a), wherein the temperature is in particular at least 280°C and preferably at least 290°C, and that the dehydration reaction takes place at a pressure that is lower than the pressure at which the hydrogenation reaction takes place in the single or first LOHC hydrogenation unit (3a), wherein the pressure is preferably in the range of 1 to 5 bar.

30. Method according to claim 28 or 29, characterized in that the dehydration reaction in the second LOHC dehydration unit (5b) takes place at a pressure of 1 bar to 5 bar, in particular at the same pressure as the dehydration reaction in the first LOHC dehydration unit (5a), and that the dehydration reaction takes place and / or at a higher temperature, in particular at a temperature of at least 300°C, preferably at least 320°C, than in the first LOHC dehydration unit (5a).

31. Method according to one of claims 22 to 30, characterized in that the single or first hydrogenation unit (3a) with the single or first dehydrogenation unit (5a) forms a structural unit preferably in the form of a tube bundle reactor or a catalytically coated heat exchanger, in particular a plate heat exchanger, in which LOHC is hydrogenated on one side and LOHC is dehydrogenated on the other side.

32. A method according to any one of claims 22 to 31, characterized in that hydrogen released by LOHC dehydrogenation is removed before for further use, in particular before storage, is compressed, wherein, in particular, the hydrogen is preferably purified absorptively before compression.

33. Method according to one of claims 22 to 32, characterized in that the gas mixture is compressed to a pressure of 10 to 60 bar, preferably 15 to 30 bar, before the separation of the gas mixture.

34. A method according to one of claims 22 to 33, characterized in that the gas mixture is subjected to absorptive separation before the LOHC hydrogenation is carried out in order to separate components that are not desired for the LOHC hydrogenation from the gas mixture by absorption, or is subjected to absorptive separation after the LOHC hydrogenation is carried out in order to remove LOHC components from the hydrogen-poor gas mixture by absorption.

35. Method according to claim 34, characterized in that the gas mixture is subjected to a pressure swing adsorption (PSA) process, and / or that the gas mixture is subjected to a temperature swing adsorption (TSA) process, and / or that the adsorptive separation takes place in a consumption bed.

36. Method according to one of claims 22 to 35, characterized in that after carrying out the LOHC hydrogenation, the hydrogen-poor gas mixture is purified in order to separate any hydrogen still contained therein.

37. Method according to one of claims 36 to 35, characterized in that the purification takes place between the LOHC hydrogenation and before an absorptive separation of the gas mixture.

38. Method according to claim 36 or 37, characterized in that hydrogen is removed oxidatively during purification.

39. Method according to claim 36 or 37, characterized in that hydrogen is removed from the noble gas during purification by using a membrane.

40. Method according to claim 39, characterized in that a portion of the noble gas from the retentate side of the membrane is applied as a noble gas sweep to the parmeate side of the membrane.

41. Method according to claim 39 or 40, characterized in that the permeate of the membrane is recycled to the supplied gas mixtures.

42. Method according to one of claims 22 to 41, characterized in that the supplied gas mixture contains at least 5 vol% hydrogen, in particular at least 10 vol% hydrogen and preferably at least 20 vol% hydrogen.

43. Method according to one of claims 22 to 42, characterized in that the supplied gas mixture contains at least 3 vol% of the noble gas, in particular at least 10 vol% of the noble gas and preferably at least 20 vol% of the noble gas.

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