Method and device for providing and / or storing hydrogen gas

Abstract

A method for providing hydrogen gas comprises the step of reforming an at least partially spent hydrogen carrier medium (H0-LOHC) on a reforming catalyst using steam in a reformer reactor (3) to form an at least partially oxidized hydrogen carrier medium (Oxo-LOHC) while forming hydrogen gas (H2) from the steam.

Description

[0001] Method and device for providing and / or storing hydrogen gas

[0002] This patent application claims priority from German patent application DE 10 2022 210 591.5, the contents of which are incorporated herein by reference.

[0003] The invention relates to a method and a device for providing and / or storing hydrogen gas.

[0004] EP 1 475 349 A2 discloses liquid organic hydrogen carrier media, referred to as LOHCs. LOHCs can be reversibly catalytically hydrogenated and dehydrogenated to chemically bind, i.e., store, and then release hydrogen gas.

[0005] The invention is based on the object of increasing the hydrogen yield, in particular the amount of hydrogen that can be released, using a hydrogen carrier medium, in particular LOHC.

[0006] This object is achieved according to the invention by methods having the features of claims 1 and 8 and by a device having the features of claim 12.

[0007] The core of the invention consists in the at least partial or complete reaction of an at least partially discharged hydrogen carrier medium with water. This reaction is referred to as at least partial reforming of the hydrogen carrier medium. The hydrogen carrier medium is oxidized using the oxygen in the water, and the hydrogen atoms in the water are converted to hydrogen gas. In particular, reforming differs from oxidation, in which the hydrogen carrier medium is reacted with oxygen and undesirable carbon dioxide is formed. A further difference between reforming and reforming is that the reaction is endothermic due to the heat-consuming hydrogen formation. The at least partially discharged hydrogen carrier medium is referred to as H0-LOHC. The reaction takes place over a reforming catalyst and using, in particular in the presence of, steam.It has been found that hydrogen gas is released at least partially from the steam during the reforming reaction. According to the invention, it is therefore possible to release hydrogen gas in conjunction with handling of hydrogen carrier medium that was not previously bound to the hydrogen carrier medium. This allows hydrogen gas to be released additionally, and in particular in addition to the hydrogen previously bound to the hydrogen carrier medium. The overall hydrogen yield is increased. The proportion of the hydrogen carrier medium that is converted in the reforming reaction according to the invention is between 1% and 100%, preferably between 30% and 98%, most suitably between 60% and 95%.

[0008] HO-LOHC has a degree of hydrogenation HG2 which is in particular not more than 60%, in particular not more than 50%, in particular not more than 40%, in particular not more than 30%, in particular not more than 20%, in particular not more than 10%, in particular not more than 5% and in particular not more than

[0009] 1%. HO-LOHC is a liquid that is particularly low in hydrogen. HO-LOHC comprises at least predominantly aromatic compounds. The proportion of aromatic compounds in HO-LOHC is in particular at least 40%, in particular at least 50%, in particular at least 60%, in particular at least 70%, in particular at least 80%, in particular at least 90%, in particular at least

[0010] 95% and in particular at least 99%.

[0011] The reforming reaction takes place in a reforming reactor. HO-LOHC is oxidized in the reforming reaction to form the at least partially oxidized hydrogen carrier medium oxo-LOHC. Oxo-LOHC comprises, in particular, one or more compounds, in particular oxidized and, in particular, oxidized aromatic compounds.

[0012] It is a finding of the invention that HO-LOHC can be oxidized to oxo-LOHC in the presence of steam, with the additional release of hydrogen gas. In particular, this reforming reaction releases one or two hydrogen molecules per oxidized compound of the oxo-LOHC.

[0013] The reforming reaction takes place, in particular, at a first location where there is a demand for energy and / or hydrogen. The first location is low in energy and / or hydrogen. At the first location, hydrogen gas is provided for a hydrogen consumer, in particular a fuel cell and / or a hydrogen burner, and / or for delivery to hydrogen customers. The provided hydrogen can be used as a material in addition to or as an alternative to its energy use, i.e., for generating electrical and / or thermal energy.

[0014] The reforming catalyst comprises a support material to which a catalytically active material, also referred to as reforming catalyst material, is attached and held. The mass fraction of the reforming catalyst material based on the support material is between 0.01% and 100%, in particular between 0.1% and 80%, and in particular between 0.3% and 50%. The support material has pores and is in particular porous. The porous support material has an inner surface of at least 1 m², in particular where the reforming catalyst material is arranged. 2 per gram of catalyst material. The average pore diameter is more than

[0015] 0.5 nm. Metal oxide supports such as aluminum oxide, titanium oxide, cerium oxide, and / or silicon oxide are particularly suitable as porous support materials. Additionally or alternatively, carbon-containing support materials, especially activated carbon, can also be used.

[0016] The reforming catalyst may comprise one or more promoters, in particular alkali salts.

[0017] The reforming catalyst material comprises, in particular, a metal component where the reforming of HO-LOHC and the formation of hydrogen gas from steam takes place. The metal components used are, in particular, iron, antimony, molybdenum, vanadium, cesium, chromium, cerium, manganese, lanthanum, titanium, tungsten, cobalt, copper, platinum, palladium, gold, ruthenium, zinc, tin, germanium, and / or nickel, with iron, nickel, cobalt, manganese, chromium, cerium, copper, gold, palladium, platinum, zinc, and / or tin having proven particularly advantageous.

[0018] It has been recognized that the reforming catalyst is particularly advantageous if it contains metal-oxygen bonds that reversibly release and reabsorb oxygen. The reforming catalyst particularly comprises metal oxide compounds, mixtures of metal oxide compounds, and / or mixed metal oxides. Mixed metal oxides are metal oxides that contain multiple metals, such as aluminum gallium oxide. Various sites in the metal oxide lattice are then occupied by at least one other metal.

[0019] It has been recognized that the reforming catalyst can exist in both an oxidized and a reduced form. During reforming of HO-LOHC, a transition from the oxidized form to the reduced form of the reforming catalyst occurs, with the transfer of oxygen to HO-LOHC. In addition, a transition from the reduced form of the reforming catalyst back to the oxidized form occurs, utilizing the oxygen atom in the steam and forming hydrogen gas. This means that after the reforming reaction, the reforming catalyst remains unchanged in its oxidized form, with the interim reduction being the prerequisite for the oxygen uptake from the steam and thus the release of hydrogen gas.

[0020] According to a first embodiment, the oxidation of the HO-LOHC by means of the oxygen groups on the catalyst and the regeneration of the catalyst by means of steam can take place simultaneously.

[0021] According to a further embodiment, the oxidation and regeneration can also be carried out in stages, i.e., at different times. In particular, the catalyst can be regenerated using steam in the absence of the hydrogen carrier medium. An advantage of this embodiment is the simplified and, in particular, unnecessary separation of oxo-LOHC and unreacted water downstream of the reforming reactor. The conditioning effort is reduced.

[0022] The reforming catalyst differs, particularly with regard to its material composition, from a known dehydrogenation catalyst, which converts an at least partially loaded hydrogen carrier medium Hx-LOHC into the at least partially discharged hydrogen carrier medium HO-LOHC by releasing hydrogen gas. Alternatively, the reforming catalyst can be designed analogously to a known dehydrogenation catalyst and, in particular, comprise a metallic, catalytically active catalyst material mounted on an oxide support material.

[0023] It is also conceivable to combine different types of catalysts.

[0024] The reforming reactor is designed in particular as a flow-through tubular apparatus in which the reforming catalyst is arranged.

[0025] Alternatively, the reforming reactor can also be designed as a classic fixed-bed reactor or as a fluidized-bed reactor.

[0026] The reforming catalyst is, in particular, a solid. The reforming catalyst is, in particular, present in a structured form, in particular in the form of a packed bed and / or in the form of catalytically coated reactor internals in the reforming reactor.

[0027] In the reforming reactor, the reforming catalyst is contacted, either simultaneously or alternately, with HO-LOHC and steam. Oxidized LOHC components and hydrogen gas are formed. Gas-solid contact occurs.

[0028] The reforming reaction is particularly endothermic and occurs under constant heat supply. The reforming reaction takes place in a temperature range between 100 °C and 800 °C, in particular between 170 °C and 650 °C, and especially between 240 °C and 350 °C. The total pressure in the reforming reactor is between 0.1 bar and 30 bar, in particular between 0.5 bar and 18 bar, and especially between 1 bar and 6 bar.

[0029] The temperature of the steam entering the reforming reactor is between 110 °C and 1000 °C, in particular between 200 °C and 800 °C and in particular between 270 °C and 600 °C.

[0030] It is advantageous if the reforming reaction on HO-LOHC is carried out in such a way that less than 20% of the carbon skeleton of HO-LOHC is cleaved, in particular less than 10% and in particular less than 3%. In particular, less than 5% of the carbon contained in HO-LOHC is converted to carbon dioxide by the reforming reactions, in particular less than 3% and in particular less than

[0031] 1%.

[0032] For the reforming reaction, the steam is fed into the reforming reactor, particularly as superheated steam. The superheated steam contains no water droplets and behaves physically like a gas. It is advantageous if at least

[0033] 10% and in particular at least 20% of the heat required for the reforming reaction is supplied with the superheated steam itself. The superheated steam is generated, in particular, by using the hydrogen released in the process for energy recovery and / or by utilizing waste heat generated in the process. In particular, the released hydrogen can be generated by operating a gas turbine, an engine, a hydrogen burner, a hydrogen engine, and / or a high-temperature fuel cell, in particular a solid oxide fuel cell.

[0034] In particular, the mixture leaving the reforming reactor is cooled, and in particular cooled to such an extent that all organic compounds of the mixture, in particular oxo-LOHC and water, condense. The components that remain liquid after condensation can be separated easily and reliably, so that the released hydrogen gas is of high purity, which is in particular at least 80%, in particular at least 90%, in particular at least 95%, in particular at least 99%, and in particular at least 99.9%.

[0035] It is conceivable to further increase the purity of the released hydrogen gas in a purification unit. In particular, purification stages of the hydrogen gas released from dehydrogenation can be used to combine the hydrogen streams from dehydrogenation and reforming in one, particularly joint and final purification stage, i.e., as the last stage in a process chain. A gas scrubber and / or an adsorption unit are particularly suitable for purifying the hydrogen gas. An adsorbent bed or a pressure and / or temperature swing adsorption unit serves as the adsorption unit.

[0036] After condensation, a liquid two-phase mixture is formed, consisting of an aqueous phase and an organic phase. The organic phase comprises oxo-LOHC, which can be advantageously separated from the aqueous phase.

[0037] Particularly advantageous LOHC material systems that can be dehydrogenated from Hx-LOHC to HO-LOHC and reformed from HO-LOHC to Oxo-LOHC using steam in the reforming reaction are summarized below in Table 1, indicating their hydrogen storage capacities. Mixtures of the material systems listed in the table are also possible, and in particular isomers of the LOHC material systems and mixtures of isomers. A theoretical hydrogen storage capacity of d m in mass% as well as a usable volumetric hydrogen storage capacity dv in Wh / 1 as a unit for the energy storage density and a calculated increase in the hydrogen capacity Ad.

[0038] Specifically, the increased hydrogen storage capacity means that with the same amount of Hx-LOHC, a hydrogen consumer can be supplied with hydrogen gas for a longer period of time, and / or a hydrogen-consuming vehicle with the same amount of Hx-LOHC can have a longer range. The increased hydrogen storage capacity increases the technical utility of the LOHC system.

[0039] In particular, it was found that simply reforming HO-LOHC with steam can release comparatively more hydrogen gas than dehydrogenating a comparable Hx-LOHC component to HO-LOHC. In particular, the reaction of one mole of trimethylbenzene with steam during reforming, forming triformylbenzene, produces up to 6 moles of hydrogen.

[0040] A process according to claim 2 enables an advantageous reforming reaction and, in particular, an improved additional release of hydrogen gas from the steam. It has proven advantageous if Hx-LOHC contains at least one cyclohexyl unit and at least one methylene group (-CEE-) or one methyl group (-CEE). Such compounds can be converted by dehydrogenation into corresponding aromatic compounds, which, upon addition of steam and further release of hydrogen gas, are converted into aromatic oxo compounds, in particular aromatic keto compounds, aromatic aldehyde compounds, and / or aromatic keto-aldehyde compounds as oxo-LOHC.

[0041] A process according to claim 3 enables the additional release of hydrogen gas. In particular, it was recognized that a heat source required for the dehydrogenation reaction, and in particular one already provided, can also be used for the reforming reaction. The utilization of this heat source to drive the reforming and dehydrogenation would thus be achieved more efficiently, and in particular, more efficiently than providing several separate heat sources, one for the dehydrogenation and the other for the reforming. The overall efficiency of the process is thus improved.

[0042] A method according to claim 4 enables uncomplicated implementation of the reforming reaction. The starting materials required for the reforming reaction can be fed to the reforming reactor essentially continuously and, in particular, without time control. It is particularly advantageous if HO-LOHC and the steam are fed to the reforming reactor simultaneously, i.e., simultaneously and, in particular, jointly, in particular via a common feed opening. The reforming of the hydrogen carrier medium on the reforming catalyst takes place in the presence of steam. The at least partially oxidized hydrogen carrier medium is oxidized directly by utilizing the oxygen from the steam and forming hydrogen gas.

[0043] Alternatively, HO-LOHC and steam can be fed to the reforming reactor at different times, particularly at different times. In particular, reforming in the reforming reactor takes place in two reaction cycles. In a first reaction cycle, predominantly, and particularly exclusively, HO-LOHC is fed and contacted with the reforming catalyst. The oxygen bound in the catalyst reacts with HO-LOHC to form oxo-LOHC. During the first reaction cycle, the HO-LOHC is oxidized, particularly in the absence of steam. In this first reaction cycle, the reforming catalyst is converted from the oxidized to the reduced form.

[0044] In a subsequent second reaction cycle, predominantly and exclusively hot steam is fed into the reforming reactor and brought into contact with the reforming catalyst. The reforming catalyst is converted from the reduced to the oxidized form, i.e., oxidized, forming hydrogen. Regeneration of the reforming catalyst during the second reaction cycle occurs in the presence of steam. HO-LOHC is not added in the second reaction cycle. In the cycled process, the hydrogen carrier medium is reformed using steam, specifically to regenerate the reforming catalyst. The oxygen bound in the catalyst is used to oxidize the hydrogen carrier medium.

[0045] Additionally, an additional, intermediate reaction cycle is possible, which serves to purge the reforming reactor, in particular exclusively for purging the reforming reactor, so that mixing of the hydrogen carrier medium with the water within the reactor due to remaining residues is minimized and, in particular, eliminated. This results in the advantage of improved purity of the respective products of the individual reaction cycles. Nitrogen or air is used as the purge gas. The process conditions of the individual process stages, in particular temperature and / or pressure, can differ from one another.

[0046] Preferably, the water vapor content in the reforming reactor in the first reaction cycle is below 30% by volume, in particular below

[0047] 15% by volume, especially below 5% by volume.

[0048] Preferably, the content of HO-LOHC in the reforming reactor in the second reaction cycle is below 30% by volume, in particular below

[0049] 15% by volume, especially below 5% by volume. In particular, the reaction conditions for the first and second reaction cycles can be different. For example, the temperature in the second reaction cycle can be set higher than in the first to further increase the yield of hydrogen gas formed.

[0050] It is particularly advantageous if the reaction cycles are carried out alternately and, in particular, at regular intervals. A cycle change occurs, in particular, at time intervals between 2 s and 5 h, in particular between 10 s and 1 h, and in particular between 1 min and 30 min. The reaction cycles can cover the same or different time periods.

[0051] A process according to claim 5 enables an advantageous reforming reaction. At least a stoichiometric amount of steam relative to HO-LOHC ensures advantageous hydrogen gas release. In particular, the molar ratio of steam to the at least partially discharged hydrogen carrier medium HO-LOHC is between 1 and 500, in particular between 1.1 and 100, and in particular between 0.2 and 10.

[0052] A process according to claim 6 enables a targeted reforming reaction. Because the reforming reaction takes place in the absence of molecular oxygen, i.e., the reforming reactor has a molecular oxygen content of less than 10 vol. %, the proportion of hydrogen gas released is further increased because water vapor and HO-LOHC are converted into hydrogen gas and oxo-LOHC in the reforming reactor.

[0053] A process according to claim 7 enables an additional increase in hydrogen yield. In particular, the HO-LOHC produced by dehydrogenation can subsequently be converted in the reforming reactor. Dehydrogenation is carried out, in particular, as a process step preceding the reforming reaction.

[0054] The dehydrogenation reaction takes place in a dehydrogenation reactor in the presence of a dehydrogenation catalyst. The dehydrogenation reaction is endothermic, i.e., it takes place with the addition of heat. The dehydrogenation reactor is, in particular, a tubular reaction apparatus in which the dehydrogenation catalyst is present, in particular, as a structured catalyst. In particular, the dehydrogenation catalyst is arranged in the form of a packed bed and / or in the form of catalytically active reactor internals. At least partially loaded hydrogen carrier medium is fed to the dehydrogenation reactor. The at least partially loaded hydrogen carrier medium is referred to as Hx-LOHC. Hx-LOHC is hydrogen-rich and has a degree of hydrogenation HGi of at least 50%, in particular at least 60%, in particular at least 70%, in particular at least 80%, in particular at least 90%, in particular at least 95%, and in particular at least 99%. In particular, the following applies: HGi > HG2.Hx-LOHC is in particular an alicyclic compound and in particular a liquid.

[0055] By dehydrogenation, Hx-LOHC is converted into the at least partially discharged hydrogen carrier medium HO-LOHC.

[0056] In the process, in particular, a multi-stage, in particular a two-stage, release of hydrogen gas takes place, namely from Hx-LOHC by dehydrogenation to HO-LOHC and by the reforming reaction from steam with reforming of HO-LOHC to Oxo-LOHC.

[0057] Dehydration and reforming can take place simultaneously or sequentially, in particular by temporarily storing Hx-LOHC and / or HO-LOHC in designated storage containers.

[0058] The dehydrogenation catalyst is, in particular, a solid and comprises a catalytically active material, referred to as dehydrogenation catalyst material, which is attached to a support material. The mass fraction of the dehydrogenation catalyst material relative to the support material is between 0.01% and 50%, in particular from 0.1% to 10%, and in particular from 0.3% to 5%. The support material has pores and is, in particular, porous. A porous metal oxide support, in particular aluminum oxide, titanium oxide, cerium oxide, and / or silicon oxide, serves as the support material. Additionally or alternatively, silicon carbide and / or a carbonaceous support material, in particular activated carbon, can also serve as the support material.

[0059] The porous catalyst has an internal surface area of ​​at least 5 m where the dehydrogenation catalyst material is arranged 2per gram of catalyst. The average pore diameter is in particular more than 0.5 nm. The dehydrogenation catalyst material comprises in particular a metal component at which the dehydrogenation reaction takes place. The metal component is in particular platinum and can additionally contain nickel, manganese, cobalt, copper, tin, iron, gallium, palladium, rhodium, rhenium, ruthenium, and / or iridium. Alternatively, nickel, cobalt, copper, iron, gallium, palladium, rhodium, ruthenium, and / or iridium can serve as the metal component.

[0060] The contact of the dehydrogenation catalyst with Hx-LOHC occurs in gas-liquid-solid contact or in gas-solid contact, in which the solid dehydrogenation catalyst is contacted with Hx-LOHC in vaporized form and / or as a liquid.

[0061] The catalytic dehydrogenation reaction in the dehydrogenation reactor is endothermic and occurs in particular under constant heat supply, in particular in a temperature range between 100 °C and 400 °C, in particular between 170 °C and 380 °C, and in particular between 240 °C and 350 °C. The hydrogen partial pressure in the dehydrogenation reactor is in particular between 0.1 bar and 12 bar, in particular between 0.5 bar and 9 bar, and in particular between 1 bar and 6 bar.

[0062] It is advantageous if the mixture leaving the dehydrogenation reactor, i.e., a mixture of released hydrogen gas, HO-LOHC, and small amounts of Hx-LOHC, is cooled. In particular, the mixture is cooled to such an extent that all organic compounds, especially HO-LOHC and Hx-LOHC, condense. The hydrogen formed can be easily and reliably separated with high purity from the liquid components after condensation. The condensed liquid components form, in particular, HO-LOHC.

[0063] Separating the mixture of substances using a membrane, in particular a Pd-Ag membrane, has proven particularly advantageous for separating the mixture of substances in the gaseous state. A separation apparatus in which condensation takes place is then unnecessary. It is also conceivable to combine a separation apparatus with a membrane, in particular by arranging them one after the other. When hydrogen is separated using a membrane, it has been found that the hydrogen gas passes through the membrane very selectively, so that the hydrogen gas can be obtained with very high purity. HO-LOHC and Hx-LOHC, however, cannot pass through the membrane and remain in the membrane retentate. The HO-LOHC and Hx-LOHC separated in this way can be removed from the retentate into a designated storage vessel and / or into the reforming reactor. Other separation processes and / or separation units are also conceivable, in particular gas scrubbers and / or adsorption units.

[0064] A process according to claim 7 comprises dehydrogenating an at least partially loaded hydrogen carrier medium Hx-LOHC, which is carried out in particular before reforming. In particular, the HO-LOHC formed by dehydrogenation is subsequently reformed with steam. The combination of dehydrogenation and reforming results in an overall increased hydrogen release rate. When using benzyltoluene as the hydrogen carrier medium, a theoretical hydrogen release of 10 mol EE per mole of benzyltoluene results, compared to 6 mol EE in the case of pure dehydrogenation of benzyltoluene.

[0065] A hydrogenation process according to claim 8 enables an advantageous conversion of oxo-LOHC to Hx-LOHC. The hydrogenation reaction is in particular exothermic and takes place in particular with the release of heat and at elevated pressure. The hydrogenation process creates the prerequisites for a material cycle, in particular a closed cycle for the hydrogen carrier medium. The hydrogenation takes place at a different time and in particular at a second location, which is in particular spatially distant from the first location. The second location is in particular energy-rich. This means that electrical power is available in abundance and / or under economically favorable conditions at the second location. The second location can also offer advantageous conditions for the use of renewable energy sources, for example for the use of wind power and / or solar power and / or hydropower.In particular, the oxo-LOHC hydrogenated in the hydrogenation reactor is formed according to the invention from HO-LOHC by a reforming reaction. The hydrogenation reaction takes place over a hydrogenation catalyst using hydrogen gas.

[0066] The hydrogenation catalyst comprises a support material to which a catalytically active material, referred to as the hydrogenation catalyst material, is attached and held. The support material has pores and is, in particular, porous. Where the hydrogenation catalyst material is arranged, the support material has an internal surface area of ​​at least 5 m 2 per gram of support material. The average pore diameter is in particular greater than 0.5 nm. The support material is, in particular, a porous metal oxide support, especially titanium oxide, cerium oxide, aluminum oxide, and / or silicon oxide. Additionally or alternatively, carbon-containing support materials are also possible, especially activated carbon.

[0067] The mass fraction of the hydrogenation catalyst material relative to the support material is between 0.01% and 5%, in particular between

[0068] 0.1% to 10% and especially between 0.3% and 5%.

[0069] The hydrogenation catalyst material comprises, in particular, a metal component at which the hydrogenation reaction and water formation take place. Suitable metal components are, in particular, platinum, palladium, nickel, manganese, cobalt, copper, iron, rhodium, ruthenium, and / or iridium, with hydrogenation catalyst materials containing platinum and / or palladium having proven particularly suitable.

[0070] In particular, the hydrogenation catalyst differs from the reforming catalyst. The hydrogenation catalyst can be identical or different from the dehydrogenation catalyst in terms of its material composition.

[0071] The hydrogenation reactor is designed, in particular, as a tubular reaction apparatus. The hydrogenation catalyst in the hydrogenation reactor is present, in particular, in a structured form, in particular in the form of a packed bed and / or in the form of catalytically active reactor internals.

[0072] The contacting of the hydrogenation catalyst in the hydrogenation reactor takes place in gas-liquid-solid contact or in gas-solid contact with the gaseous hydrogen and the reaction mixture, in particular with oxo-LOHC in gaseous or liquid form.

[0073] Hydrogenation takes place in particular in a temperature range between 50 °C and 400 °C, in particular between 100 °C and 370 °C, and in particular between 150 °C and 340 °C. The hydrogen partial pressure in the hydrogenation reactor is between 5 bar and 300 bar, in particular between 7 bar and 180 bar, and in particular between 10 bar and 60 bar. The substances discharged from the hydrogenation reactor form, in particular, a liquid mixture. The mixture is cooled, in particular to such an extent that all organic compounds, in particular Hx-LOHC, and the water formed condense, and the hydrogen, in particular physically dissolved hydrogen, largely outgasses.

[0074] After condensation, a liquid two-phase mixture is formed, comprising an aqueous phase and an organic phase. The organic phase comprises, in particular, Hx-LOHC, which can be advantageously and easily separated from the aqueous phase by phase separation.

[0075] A recycling process according to claim 9 enables an advantageous closed material cycle.

[0076] A recycling process according to claims 10 or 11 ensures the reliable and uncomplicated implementation of the respective process steps, in particular staggered in time and at different, in particular spatially separated, locations. Transport vehicles, in particular transport trucks, transport trains and / or transport ships, can be used to transport the hydrogen carrier medium in the various states, i.e. Hx-LOHC, HO-LOHC and / or Oxo-LOHC. Additionally or alternatively, transport can take place via dedicated lines, so-called pipelines, which can be arranged above ground and / or underground. In particular, an existing pipeline network can be used for this purpose. The hydrogen carrier medium can be fed into or withdrawn from the pipeline network at feed-in and withdrawal stations.

[0077] A device according to claim 12 essentially has the advantages of the method according to the invention, to which reference is hereby made.

[0078] It is advantageous to provide a heat unit that can supply heat to the reforming reactor and / or the dehydrogenation reactor. This simplifies the implementation of the endothermic reactions. It is also possible to provide separate heat units for dehydrogenation and / or reforming, which can be operated independently of each other. This makes it possible to supply heat to the respective reactor in a targeted and time-independent manner.

[0079] A device according to claim 13 ensures the uncomplicated provision of H0-LOHC for subsequent reforming.

[0080] A device according to claim 14 enables a subsequent

[0081] Hydrogenation, wherein the hydrogenation reactor in particular has a feed line for feeding hydrogen gas and / or a discharge line for discharging water and / or LOHC.

[0082] A device according to claim 15 enables an advantageous and in particular fluidically closed circuit arrangement.

[0083] Both the features specified in the patent claims and the features specified in the exemplary embodiments of a device according to the invention are suitable, either individually or in combination with one another, for further developing the subject matter of the invention. The respective combinations of features do not represent any limitation with regard to further developments of the subject matter of the invention, but are essentially merely exemplary in nature.

[0084] Further features, advantages, and details of the invention will become apparent from the following description of an embodiment with reference to the drawings. They show:

[0085] Fig. 1 is a highly schematic representation of a device with hydrogenation reactor, dehydrogenation reactor and reforming reactor in a closed circuit arrangement,

[0086] Fig. 2 is a schematic enlarged view of the dehydrogenation reactor according to Fig. 1 with peripherals,

[0087] Fig. 3 is a representation corresponding to Fig. 2 of the reforming reactor according to Fig. 1 with peripherals, Fig. 4 is a representation corresponding to Fig. 2 of the hydrogenation reactor according to Fig. 1 with peripherals.

[0088] A device 1, shown highly schematically in Fig. 1, serves to provide and store hydrogen gas using a hydrogen carrier medium (LOHC), which is used in various states, in particular at least partially loaded with hydrogen as Hx-LOHC, at least partially discharged as HO-LOHC, and / or at least partially oxidized as Oxo-LOHC. The device 1 comprises a dehydrogenation reactor 2, a reforming reactor 3 fluidically connected thereto, and a hydrogenation reactor 4 fluidically connected thereto. The hydrogenation reactor 4 is in turn fluidically connected to the dehydrogenation reactor 2. The reactors 2, 3, 4 form a fluidically closed circuit arrangement 5.

[0089] In a very simplified manner, the device 1 is operated by feeding Hx-LOHC, according to the illustrated embodiment in the form of perhydrogen-benzyltoluene, to the dehydrogenation reactor 2. A dehydrogenation catalyst is arranged in the dehydrogenation reactor 2, in the presence of which Hx-LOHC is dehydrogenated to HO-LOHC with the release of hydrogen gas H2. According to the illustrated embodiment, HO-LOHC is formed by benzyltoluene. Accordingly, 6 mol of hydrogen gas are released per 1 mol of benzyltoluene. The dehydrogenation reaction in the dehydrogenation reactor 2 is endothermic. A heat flow Q is supplied to the dehydrogenation reactor 2.

[0090] HO-LOHC is fed to reforming reactor 3 and contacted with a reforming catalyst arranged therein. For the reforming reaction, water vapor, in particular at least 2 mol of water vapor per 1 mol of HO-LOHC, as well as heat Q, are also fed to reforming reactor 3. As a result of the reforming reaction, HO-LOHC is converted with water vapor to oxo-LOHC. In addition, hydrogen gas is released from the supplied water vapor, in particular 2 mol of hydrogen gas per 1 mole of converted water vapor.

[0091] Oxo-LOHC is fed to hydrogenation reactor 4, where it is contacted with a hydrogenation catalyst and hydrogenated in the presence of hydrogen gas H2 to form Hx-LOHC. The hydrogenation reaction in hydrogenation reactor 4 is exothermic. Heat is removed from hydrogenation reactor 4 as heat flow Q. Water is produced in hydrogenation reactor 4 during the hydrogenation reaction, which is isolated by phase separation in the cooled state and removed separately. Apparatus 1 is described in more detail below with reference to Figs. 2 to 4.

[0092] Fig. 2 shows a first sub-device, designated as a whole by 6, which comprises the dehydrogenation reactor 2. The first sub-device 6 serves to dehydrogenate Hx-LOHC.

[0093] The first sub-device 6 comprises a first storage container 7 in which Hx-LOHC is stored. In this context, Hx-LOHC comprises the at least partially charged hydrogen carrier medium, whereby at least partially and / or completely discharged forms of the hydrogen carrier medium LOHC can also be stored in the first storage container 7. These other components constitute impurities of the Hx-LOHC.

[0094] The first storage tank 7 is connected to a heat exchanger 10 via a first fluid line 8 and a controllable first conveying unit 9, in particular a liquid pump. For illustrative purposes, only one heat exchanger 10 is shown in Fig. 2. The first sub-device 6 can also comprise multiple heat exchangers 10. In particular, the first storage tank 7 is connected to at least one and in particular multiple heat exchangers.

[0095] The first conveying unit 9 is in particular bidirectional signal communication with a central control unit 11. The signal connection can be wired or wireless, in particular by radio. The signal connection is shown purely symbolically in Fig. 2 by a dashed line 12. The first fluid line 8 connects the first heat exchanger 10 to the dehydrogenation reactor 2. A first heat source 13 is arranged along the fluid flow direction between the first heat exchanger 10 and the dehydrogenation reactor 2. The first heat source 13 is in particular designed to be controllable and is in particular bidirectional signal communication with the control unit 11. The first heat source 13 is in particular an electric heater and in particular connected to a power supply (not shown in detail). The first heat source 13 is optional.

[0096] The dehydrogenation reactor 2 has a dehydrogenation vessel 14 in which at least one dehydrogenation chamber 15 and in particular a plurality of dehydrogenation chambers 15 are arranged. The dehydrogenation catalyst is arranged in each dehydrogenation chamber 15. The dehydrogenation vessel 14 has a longitudinal axis 16, which, according to the illustrated embodiment, is oriented vertically. The longitudinal axis 16 can be inclined relative to the vertical and, in particular, arranged horizontally. The dehydrogenation vessel 14 has a cross-sectional area oriented perpendicular to the longitudinal axis 16, which is designed to be essentially unchanging and, in particular, constant along the longitudinal axis 16.

[0097] The dehydrogenation chambers 15 are particularly tubular and particularly separated from one another. The dehydrogenation chambers 15 are separate and arranged at a distance from one another. In particular, the dehydrogenation chambers 15 are arranged at a distance from one another in a plane perpendicular to the longitudinal axis 16. The dehydrogenation chambers 15 are particularly oriented parallel to the longitudinal axis 16.

[0098] The dehydration chambers 15 are arranged in particular regularly and in particular in a regular grid relative to one another. The dehydration chambers 15 are each formed by a tube. The dehydration chambers 15 are in particular identical and in particular have an outer contour, which is in particular regular, in a plane oriented perpendicular to the longitudinal axis 16. The contour is in particular circular or polygonal, in particular quadrangular, in particular rectangular, square, or hexagonal.

[0099] The dehydration tank 14 has a first end wall 17, shown at the bottom in Fig. 2, and an oppositely arranged second end wall 18, shown at the top in Fig. 2. The end walls 17, 18 define a length L oriented along the longitudinal axis 16. The dehydration chambers 15 extend along the longitudinal axis 16 over at least 50% of the length L, in particular over at least 80% of the length L, and in particular over at least 95% of the length L.

[0100] The first fluid line 8 is connected to the dehydrogenation tank 14 in a lower region of the dehydrogenation tank 14, in particular adjacent to the first end wall 17. The first fluid line 8 is connected to a first distributor element 19, which is arranged in the dehydrogenation tank 14. The first distributor element 19 is fluidly connected to each dehydrogenation chamber 15. A connecting piece (not shown in detail) serves this purpose. The first distributor element 19 enables the uniform distribution of Hx-LOHC into the dehydrogenation chambers 15. The first distributor element 19 is particularly advantageous when the dehydrogenation reactor 2 is arranged with its longitudinal axis 16 transverse to the vertical and in particular horizontally. The first distributor element 19 is also advantageous when the dehydrogenation reactor 2 is oriented vertically and the supply of Hx-LOHC into the dehydrogenation chambers 15, unlike as shown in Fig. 2, takes place from above. In the embodiment shown in Fig.2, the first distributor element 19 can also be omitted.

[0101] Dehydration spaces 20 are formed between the dehydration spaces 15. The dehydration spaces 20 are bounded by the inner surface of the dehydration tank 14 and by the outer surfaces of the dehydration spaces 15 in the radial direction relative to the longitudinal axis 16, as well as by the end walls 17, 18 in the axial direction relative to the longitudinal axis 16.

[0102] A heat transfer fluid supply line 21 and a heat transfer fluid discharge line 22 are connected to the dehydrogenation spaces 20. The heat transfer fluid supply line 21 opens into the dehydrogenation spaces 20 via a jacket surface of the dehydrogenation tank 14. The heat transfer fluid supply line 21 is arranged in an upper region of the dehydrogenation tank 14, in particular adjacent to the second end wall 18. The heat transfer fluid discharge line 22 is correspondingly arranged in a lower region of the dehydrogenation tank 14 and in particular adjacent to the first end wall 17 in a jacket region of the dehydrogenation tank 14. The flow direction of a heat transfer fluid, i.e. from the heat transfer fluid supply line 21 to the heat transfer fluid discharge line 22, is essentially opposite to the flow direction of the Hx-LOHC. Heat transfer takes place in a countercurrent process.

[0103] The dehydrogenation spaces 20 are part of a heating unit, in particular a dehydrogenation heating unit. In particular, the heat transfer fluid discharge line 22 is connected to an external heat source 23, in which the cooled heat transfer fluid, in particular heat transfer oil, can be reheated. The heat transfer fluid is in particular a hot liquid heat transfer oil and can additionally or alternatively comprise condensing vapors and / or hot vapors, in particular gas mixtures containing water vapor. The reheated heat transfer fluid can then be fed back to the dehydrogenation space 20 from the external heat source 23 via the heat transfer fluid supply line 21. In particular, a closed heat transfer fluid circuit is formed. The heat transfer fluid supply line 21 is connected to the external heat source 23. The external heat source 23 is part of the heating unit, in particular the dehydrogenation heating unit.Heat transfer using the cocurrent process is also possible by reversing the flow direction of the heat transfer oil.

[0104] Additionally or alternatively, it is also possible to heat the dehydration spaces 20 and / or the outer wall of the dehydration container 14 separately and in particular electrically, in particular by means of a resistance heater, as a heating unit.

[0105] Opposite the first distribution element 19, the dehydrogenation chambers 15 open into a first collecting element 24, which is arranged on an upper side of the dehydrogenation vessel 14. A second fluid line 25 is connected to the first collecting element 24, which connects the dehydrogenation reactor 2 to a first separation apparatus 26. The first heat exchanger 10 is arranged along the second fluid line 25.

[0106] The first separation apparatus 26 is a gas-liquid separator. The first separation apparatus 26 may have a pressure control valve (not shown in detail) with which a pressure, in particular a reaction pressure, in the dehydrogenation reactor 2 and / or in the first heat exchanger 10 can be adjusted and, in particular, regulated. The reaction pressure in the dehydrogenation reactor 2 is formed, in particular, by hydrogen gas and / or by the vaporous aromatic compounds formed in the dehydrogenation reactor 2. The pressure control valve is in a signal connection, in particular a bidirectional connection, with the control unit 11.

[0107] The first separation apparatus 26 comprises a first separation chamber 27 and a second separation chamber 29 connected thereto by means of a connecting line 28. Alternatively, the first separation apparatus 26 can be designed with only a single separation chamber.

[0108] The two separation chambers 27, 29 are directly connected to one another, particularly in an upper region, via a gas line 30. The gas line 30 enables pressure equalization between the two separation chambers 27, 29. The two separation chambers 27, 29 always maintain the same, particularly identical, fill level of fluid, particularly HO-LOHC. The fill level can be measured using a level sensor 31. The level sensor 31 is in bidirectional signal communication with the control unit 11. According to the illustrated embodiment, the level sensor 31 is arranged on the second separation chamber 29. The level sensor 31 can alternatively or additionally also be arranged on the first separation chamber 27.

[0109] The two chambers 27, 29 are connected to each other like communicating tubes. This means that the liquid phase and the gas phase of the chambers 27, 29 are in contact with each other, i.e., communicate, via the connecting line 28 and the gas line 30. This results in the same pressure and the same fill level in both chambers 27, 29, particularly regardless of the respective design of the separation chambers 27, 29.

[0110] A hydrogen gas discharge line 32 is connected to the first separation chamber 27, along which a cleaning unit, in particular in the form of a filter element 33, in particular an activated carbon filter, is arranged. In addition to or as an alternative to the filter element 33, the cleaning unit can comprise an adsorption unit, in particular for pressure swing adsorption.

[0111] Released, purified hydrogen gas H2 can be provided, in particular, for a utilization unit 34, in particular a fuel cell, via the hydrogen gas discharge line 32. A third fluid line 35 is connected to the second separation chamber 29, along which a controllable second delivery unit 36, in particular a liquid pump, is connected. The second delivery unit 36 ​​is in signal communication, in particular bidirectional, with the control unit 11. The dehydrogenation reactor 2 is fluidly connected to the reforming reactor 3 via the third fluid line 35. For illustrative purposes only, the reforming reactor 3 is shown very schematically in Fig. 2.

[0112] The reforming reactor 3 is explained in more detail below with reference to Fig. 3.

[0113] Fig. 3 shows a sub-device designated overall by 37. The second sub-device 37 serves to reform HO-LOHC in the reforming reactor 3. The second sub-device 37 serves in particular for the further, in particular additional, provision of hydrogen gas, in particular from steam, as part of the reforming reaction in the reforming reactor 3.

[0114] For this purpose, the dehydrogenation reactor 2 is shown purely schematically in Fig. 3 as a source of HO-LOHC. A second storage tank 38 can be arranged between the dehydrogenation reactor 2 and the reforming reactor 3, in particular along the third fluid line 35 and in particular adjacent to the reforming reactor 3, i.e. in particular as a component of the second sub-device 37.

[0115] The third fluid line 35 is connected to the reforming reactor 3 via the second heat exchanger 39 and the second heat source 40. The fluid is conveyed along the third fluid line 35, in particular, by the controllable second conveying unit 36. The second conveying unit 36 ​​can also be arranged in the second sub-device 37 in addition to or as an alternative to the first sub-device 6.

[0116] The second heat source 40 is, in particular, identical to the first heat source 13. HO-LOHC is, in particular, preheated in the second heat exchanger 39 and / or at least partially and, in particular, completely evaporated in the second heat source 40. The second heat source 40 is optional. This means that the HO-LOHC can also be preheated without the second heat source 40.

[0117] The third fluid line 35 opens into a reforming tank 41 of the reforming reactor 3. At least one reforming chamber 42 and in particular a plurality of reforming chambers 42 are arranged in the reforming tank 41. A reforming catalyst is arranged in each of the reforming chambers 42. The reforming tank 41 has a longitudinal axis 43, which, according to the exemplary embodiment shown, is oriented vertically. The longitudinal axis 43 can also be inclined relative to the vertical and, in particular, arranged horizontally. The reforming tank 41 has a cross-sectional area oriented perpendicular to the longitudinal axis 43, which is essentially constant along the longitudinal axis 43. In particular, the cross-sectional area of ​​the reforming tank 41 is constant along the longitudinal axis 43. The reforming chambers 42 are, in particular, tubular and have a regular contour in a plane perpendicular to the longitudinal axis 43.The contour is in particular circular or polygonal, in particular quadrangular, in particular rectangular or square, or hexagonal.

[0118] The reforming chambers 42 are arranged at a distance from one another, in particular in a plane perpendicular to the longitudinal axis 43. The reforming chambers 42 are oriented in particular parallel to the longitudinal axis 43. The reforming chambers 42 are arranged at a distance from one another in the plane perpendicular to the longitudinal axis 43 and in particular in a regular grid.

[0119] The reforming tank 41 has a first end wall 44, which is arranged at the bottom in Fig. 3, and a second end wall 45, which is arranged opposite the first end wall 44 and is shown at the top in Fig. 3.

[0120] The reforming chambers 42 have a length L oriented along the longitudinal axis 43, which is delimited by the two end walls 44, 45. The reforming chambers 42 extend along the longitudinal axis 43 over a large part of the length L of the reforming vessel 41, in particular over at least 50%, in particular over at least 80%, and in particular over at least 95% of the length L.

[0121] The third fluid line 35 is connected to the reforming vessel 41 in a lower region thereof. The third fluid line 35 is connected to a second distributor element 46 arranged in the reforming vessel 41. The second distributor element 46 is connected to each reforming chamber 42 via a connecting piece not shown in detail. The use of the second distributor element is particularly advantageous when the reforming reactor 3 is arranged with its longitudinal axis 43 transverse to the vertical and in particular horizontally. The second distributor element 46 is also advantageous when the reforming reactor 3 is oriented vertically and the HO-LOHC is supplied to the reforming chambers 42 from above. Water, in particular in the form of steam, is supplied to the reforming reactor 3 and in particular to the reforming chambers 42 via the second distributor element 46.The water is supplied to the reforming reactor 3 via the water supply line 47, which opens in particular into the second distribution element 46. The volume flow of the supplied water via the water supply line 44 is controlled via a third delivery unit 48 or via a valve, in particular by means of the control unit 11, which is connected to the third delivery unit 48, in particular via a bidirectional signal connection.

[0122] The water supply line 47 is connected to a steam generator 49, which generates steam, particularly in superheated form and particularly at temperatures above 110°C. The steam generator is, for example, a hydrogen-powered gas turbine, a hydrogen-powered engine, a hydrogen-powered burner, a hydrogen-powered motor, and / or a hydrogen-powered solid oxide fuel cell.

[0123] Reforming spaces 50 are formed between the reforming chambers 42. The contour of the reforming spaces 50 results from the respective outer contour of the reforming chambers 42 and the inner contour of the reforming vessel 41.

[0124] The reforming spaces 50 form a heat exchanger and are in particular part of a heat unit for supplying heat to the reforming reactor 3, in particular to the reforming spaces 42. The heat transfer takes place in particular by means of a heat transfer fluid flowing through the reforming spaces 50, which can be supplied to the reforming space 50 via a heat transfer fluid supply line 51 and removed via a corresponding heat transfer fluid discharge line 52. The heat transfer fluid is in particular a hot material stream, in particular a heat-carrying liquid, in particular heat-carrying oil, and / or a heat-carrying gas. A second external heat source 53 can be connected to the heat transfer fluid discharge line 52 in order to reheat the heat transfer fluid. Accordingly, the second external heat source 53 is connected to the heat transfer fluid supply line 51. With regard to its function, reference is made to the heat exchanger in the dehydrogenation reactor 2 according to Fig.2, which is explained accordingly.

[0125] In the reforming reactor 3, the reforming spaces 50 and / or the outer wall of the reforming vessel 41 can also be heated electrically, in particular via a resistance heater. A second collector element 54, into which all reforming spaces 42 open, is arranged opposite the second distributor element 46. A fourth fluid line 55, which opens into a second separator 56, is connected to the second collector element 54. The second heat exchanger 39 is arranged along the fourth fluid line 55.

[0126] In the second heat exchanger 39, the oxo-LOHC discharged from the reforming reactor 3 is cooled and condensed. The resulting fluid stream is fed to the second separation apparatus 56, which is designed as a gas-liquid separator.

[0127] In particular, the second separating apparatus 56 is identical to the first

[0128] Separation apparatus 26 is designed according to Fig. 2. To avoid repetition, reference is made to the structure and function thereof. The second separation apparatus comprises two separation chambers 57, 58, each directly connected to one another by a connecting line 59 and a gas line 60. The second separation apparatus 56 has at least one level sensor 61.

[0129] A hydrogen gas discharge line 62 and a filter element 63 are connected to the first separation chamber 57. A utilization unit 64 is connected to the hydrogen gas discharge line 62. It is conceivable that the hydrogen gas discharge line 62 leads to the utilization unit 34 according to Fig. 2.

[0130] The second separation chamber 58 is connected to a liquid-liquid separator 66 via a further fluid line 65. In the liquid-liquid separator 66, a liquid two-phase mixture is separated, particularly by gravity, into a water phase and an organic phase. The separated phases can be removed separately from the liquid-liquid separator 66. In particular, the liquid-liquid separator 66 has a lower outlet for removing the denser, aqueous liquid phase via a water discharge line 67 and feeding it to a water purification unit 68. The water purification unit 68 serves to purify the water for subsequent disposal and / or reuse in the process, particularly by recirculation into the steam cycle 49.The liquid-liquid separator 66 has an upper outlet for removing the less dense, organic liquid phase via a fluid line 69 and conveying it into a third storage tank 71 by means of a controllable fourth conveying unit 70. Oxo-LOHC, in particular, is stored in the third storage tank 71.

[0131] The fourth conveyor unit 70 is in, in particular bidirectional, signal connection with the control unit 11. It is conceivable that the second sub-device 37 has a separate control unit, which in turn can then be in, in particular bidirectional, signal connection with the control unit 11 of the first sub-device 6.

[0132] Separate control units are particularly advantageous when the first sub-device 6 and the second sub-device 37 are designed separately from one another and in particular spatially separated from one another.

[0133] The third storage tank 71 is particularly suitable as a transport tank. The third storage tank 71 can be transported, for example, by means of a transport vehicle, in particular a transport truck, a transport train, or a transport ship. The third storage tank 71 also serves as a terminal for feeding the liquid contained therein into a delivery line, in particular into a pipeline network.

[0134] The first sub-device 6 and / or the second sub-device 37 are arranged, in particular, at a first, low-energy location. Energy is required at the first location. The energy is provided by released hydrogen gas, in particular in the utilization units 34 and / or 64.

[0135] Through transport, particularly of oxo-LOHC, to the hydrogenation reactor 4, the hydrogen carrier medium can be recharged with hydrogen. The transport is symbolized in Fig. 3 by a dashed line 72.

[0136] The dehydrogenation reactor 4, which serves to hydrogenate oxo-LOHC, in particular to Hx-LOHC, is explained in more detail below with reference to Fig. 4. Fig. 4 shows a third sub-device 73, in which oxo-LOHC is hydrogenated to Hx-LOHC by adding hydrogen gas and releasing water.

[0137] Oxo-LOHC is stored in a third storage container 71 in the third sub-device 73. In addition to oxo-LOHC, other components, particularly non-oxidized aromatic compounds, that represent impurities with respect to oxo-LOHC may be present in the third storage container 71. The third storage container 71 of the third sub-device 73 can be identical to the third storage container 71 of the second sub-device 37. The two third storage containers 71 can be connected to each other by a transport connection 72.

[0138] The third storage tank 71 is connected to the hydrogenation reactor 4 via another fluid line 74. A third heat exchanger 75 and a third heat source 76, which serves to preheat oxo-LOHC, are arranged along the fluid line 74. A fifth conveying unit 77 is arranged on the fluid line 74 and is in signal communication, particularly bidirectional, with a hydrogenation control unit 78. The signal connection can be wired or wireless, particularly via a radio connection. The signal connection 79 is shown in Fig.

[0139] 4 is symbolized by a dashed line. The hydrogenation control unit 78 can, in particular, be in signal communication with the control unit 11 of the first sub-device 6.

[0140] The hydrogenation reactor 4 has a hydrogenation vessel 80 in which at least one hydrogenation chamber 81 and, in particular, a plurality of hydrogenation chambers 81 are arranged. The hydrogenation vessel 80 has a longitudinal axis 82, which, according to the illustrated embodiment, is oriented vertically. The longitudinal axis 82 can be arranged inclined relative to the vertical. The hydrogenation vessel 80 has a cross-sectional area oriented perpendicular to the longitudinal axis 82, which is designed to be essentially unchanging and, in particular, constant along the longitudinal axis 82.

[0141] The hydrogenation chambers 81 are, in particular, tubular. The hydrogenation chambers 81 have a regular contour in a plane perpendicular to the longitudinal axis 82, which contour is, in particular, circular or polygonal, in particular quadrangular, in particular rectangular or square, or hexagonal. The hydrogenation chambers 81 are, in particular, oriented parallel to the longitudinal axis 82. A hydrogenation catalyst is arranged in each hydrogenation chamber 81. The hydrogenation vessel 80 has a first, upper end wall 83 and an opposite, lower second end wall 84. The hydrogenation vessel 80 has a length L oriented along the longitudinal axis 82, which length is delimited by the end walls 83, 84. The hydrogenation chambers 81 extend over a large part of the length L of the hydrogenation vessel 80, in particular over at least 50%, in particular over at least 80%, in particular over at least 95% of the length L.

[0142] The fluid line 74 is connected to the hydrogenation vessel 80 in an upper region. The fluid line 74 is connected to a third distributor element 85 arranged in the hydrogenation vessel 80. The third distributor element 85 is connected to each hydrogenation chamber 81 via a connecting piece (not shown). The use of the third distributor element 85 is advantageous when the hydrogenation reactor 4 is oriented vertically with its longitudinal axis 82 and the oxo-LOHC is fed into the dehydrogenation chambers 81 from above.

[0143] A hydrogen gas supply line 86 is also connected to the third distributor element 85. The hydrogen gas supply line 86 is a fluid line for supplying pressurized hydrogen at a pressure of

[0144] 5 bar and 300 bar, in particular between 7 bar and 180, and in particular between 10 bar and 60 bar. The volume flow of hydrogen into the third distributor element 85 is regulated via a valve (not shown in detail), which is in particular in a signal connection, in particular bidirectional, with the hydrogenation control unit 87.

[0145] Hydrogenation spaces 87 are formed between the hydrogenation spaces 81 and are arranged at a distance from one another in a plane perpendicular to the longitudinal axis 82. In particular, the hydrogenation spaces 87 are arranged in a regular grid in the plane perpendicular to the longitudinal axis 82. The contour of the hydrogenation spaces 87 results from the inner contour of the hydrogenation vessel 80 and the respective outer contour of the hydrogenation spaces 81. In the axial direction, the hydrogenation spaces 87 are delimited by the two end walls 83, 84. The hydrogenation spaces 87 serve as heat exchangers in that a heat transfer fluid flows through the hydrogenation spaces 87. Accordingly, a heat transfer fluid supply line 88 and a heat transfer fluid discharge line 89 are connected to the hydrogenation spaces 87.A heat sink 90 is connected to the heat transfer fluid discharge line 89, to which the heated heat transfer fluid can release heat and then be fed back to the hydrogenation spaces 87 via the heat transfer fluid supply line 88. A liquid heat transfer oil serves as the heat transfer fluid, in particular.

[0146] Opposite the third distribution element 85, in a lower region of the hydrogenation vessel 80, a third collecting element 91 is arranged, into which the hydrogenation chambers 81 open. A further fluid line 92 is connected to the third collecting element 91, which leads to a third separation apparatus 93. The third heat exchanger 75 is arranged along the fluid line 92 between the hydrogenation reactor 4 and the third separation apparatus 93.

[0147] The third separation apparatus 93 is a gas-liquid separator for separating Hx-LOHC and water from hydrogen gas that outgasses upon cooling. The third separation apparatus 93 may have a pressure control valve (not shown in detail), by means of which a pressure, in particular a reaction pressure, in the hydrogenation reactor 4 and / or in the third heat exchanger 75 can be set and, in particular, regulated, in particular by means of the hydrogenation control unit 78. The reaction pressure in the hydrogenation reactor 4 is formed, in particular, by hydrogen gas and / or by the aromatic and oxidized aromatic compounds present in vapor form in the hydrogenation reactor 4.

[0148] The third separating device 93 is similar in its structure and function to the previously described separating devices 26 and 56. The following description is therefore presented in abbreviated form.

[0149] The third separation apparatus has a first separation chamber 94 and a second separation chamber 95, which are connected to one another by a connecting line 96 and a gas line 97. A level sensor 98 is arranged in the second separation chamber 95. The level sensor has a bidirectional signal connection to the hydrogenation control unit 78. A hydrogen gas discharge line 99 is connected to the first separation chamber 94, via which outgassing hydrogen can be discharged. The hydrogen gas discharge line is connected to a utilization unit 100, which is designed, in particular, separately from the hydrogen utilization units 34, 64. The utilization unit 100 recompresses the outgassed hydrogen, for example, in order to feed it back to the hydrogenation reactor 4 via the hydrogen gas supply line 86.

[0150] Alternatively or additionally, thermal utilization of the outgassed hydrogen, i.e., combustion of the outgassed hydrogen, or venting it into the environment is possible. In the latter case, the hydrogen gas discharge line 99 is connected to a purification unit (not shown), in particular to an activated carbon filter, to remove organic components from the hydrogen gas.

[0151] Additionally or alternatively, a hydrogenation cartridge can be arranged for the utilization and / or removal of physical hydrogen gas in the fluid stream from the reactor. Such a hydrogenation cartridge is known from DE 10 2020 215 444 A1, to which explicit reference is made with regard to the structure and function of the hydrogenation cartridge and, in particular, its arrangement in the system.

[0152] The second separation chamber 95 is connected via a further fluid line 101 to a liquid-liquid separator 102, in which a liquid two-phase mixture is separated, particularly by gravity. The denser, aqueous liquid phase can be removed from the separator 102 in a lower region and fed to a purification unit 104 via the water discharge line 103. After the purification unit 104, the water can be disposed of or reused, for example, as the input stream of a spatially adjacent electrolyzer.

[0153] The separator 102 has an upper outlet for conveying the less dense, organic liquid phase, in particular Hx-LOHC, via a further fluid line 105, along which a fifth controllable conveying unit 106 is arranged. Hx-LOHC is conveyed in particular into a storage / transport container 107, which is connected to the fluid line 105. The fifth conveying unit 106 is designed in particular as a liquid pump. The fifth conveying unit 106 is in particular in a signal connection, in particular bidirectional, with the hydrogenation control unit 78.

[0154] The storage / transport container 107 can be transported from the second location, where the third sub-device 73 is arranged, to the first location, where the first sub-device 6 and / or the second sub-device 37 are arranged. In particular, the storage / transport container 107 can replace and / or supplement the first storage container 7 in Fig. 2. Additionally or alternatively, Hx-LOHC can be transported from the storage / transport container 107 to the first storage container 7 by means of a transport line (not shown), in particular a pipeline network.

[0155] Because the dehydrogenation reactor 2, the reforming reactor 3, and the hydrogenation reactor 4 are each fluidically connected to one another, a closed-loop system is formed. This enables advantageous, particularly reversible, use of the hydrogen carrier medium to store and release energy by chemically binding hydrogen.

[0156] A method for operating the device 1 is explained in more detail below with reference to the figures.

[0157] Hx-LOHC is preheated from the first storage vessel 7 by means of the first heat exchanger 10 and the first heat source 13 and fed to the dehydrogenation reactor 2. From the first distribution element 19, Hx-LOHC is fed to the dehydrogenation chambers 15, where it contacts the dehydrogenation catalyst. Due to the heat supplied to the dehydrogenation chambers 15 from the dehydrogenation interspaces 20, the dehydrogenation reaction can take place. Hx-LOHC is converted into H0-LOHC, and hydrogen gas is released. This fluid mixture is conveyed from the dehydrogenation chambers 15 into the first collection element 24, via the second fluid line 25 through the first heat exchanger 10, and to the first separation apparatus 26. In the first heat exchanger 10, heat is transferred to the fresh Hx-LOHC to be preheated.

[0158] In the first separation apparatus 26, the released hydrogen gas is separated from the HO-LOHC and can be used in the utilization unit 34. HO-LOHC is conveyed from the first sub-device 6 to the second sub-device 37, optionally temporarily stored in a second storage container 38. HO-LOHC is heated in the second heat exchanger 39 and, in particular, at least partially and in particular completely evaporated by means of the second heat source 40 and fed to the second distributor element 46 of the reforming reactor 3. In addition, water, in particular in the form of steam, is fed to the second distributor element 46. The fluid mixture of at least partially evaporated HO-LOHC and steam is conveyed from the second distributor element 46 into the reforming chambers 42, where it comes into contact with the reforming catalyst. The HO-LOHC and steam can be supplied simultaneously or separately.It is essential that the oxygen of the reforming catalyst serves to reform HO-LOHC, and the oxygen of the steam serves to reform the reforming catalyst, particularly subsequently, releasing hydrogen gas. The heat transfer fluid flowing through the reforming interspaces 50 provides the heat required for this. The fluid mixture from the reforming spaces 42, particularly hydrogen gas and oxo-LOHC, is fed from the reforming spaces 42 to the second collection space 54 and from there, via the fourth fluid line 55, via the second heat exchanger 39, in which HO-LOHC is preheated, to the second separation apparatus 56.

[0159] In the second separation apparatus 56, the hydrogen gas additionally released from the steam in the reforming reactor 3 is separated and fed to the utilization unit 64. The liquid-liquid mixture of oxo-LOHC and water is separated in the separator 66, with oxo-LOHC being stored in the third storage tank 71 and transported from the first location of the second sub-device 37 to the second location of the third sub-device 73, i.e., to the hydrogenation reactor 4.

[0160] In the third sub-device 73, oxo-LOHC from the third storage tank 71 is preheated in the third heat exchanger 75 and by means of the third heat source 76 and fed via the fluid line 74 to the third distribution element 85 of the hydrogenation reactor 4. The third heat source 76 is optional. This means that the preheating of the oxo-LOHC can also take place without the third heat source 76. Pressurized hydrogen is also supplied to the third distribution element 85 and, together with oxo-LOHC, is fed to the hydrogenation chambers 81, where it contacts the hydrogenation catalyst. The exothermic hydrogenation reaction takes place in the hydrogenation chambers 81, forming water. The released heat is absorbed by the heat transfer fluid flowing through the hydrogenation spaces 87 and reliably removed from the hydrogenation reactor 4. The heat sink 90 connected to the heat transfer fluid discharge line 89 serves this purpose in particular.

[0161] The water released during the hydrogenation reaction, any physically stored hydrogen gas, and Hx-LOHC are collected from the hydrogenation chambers 81 in the third collection chamber 91 and removed from the hydrogenation reactor 4 via the eighth fluid line 92. Heat is released in the third heat exchanger 75. The outgassed hydrogen can be separated in the third separation apparatus 93 and fed to the utilization unit 100. The liquid-liquid mixture of water and Hx-LOHC is separated in the separator 66. The water thus recovered can be purified in the purification unit 104. Hx-LOHC can be temporarily stored in the storage / transport container 107 and conveyed to the first sub-device 6, in particular to the dehydrogenation reactor 2, for further use.

[0162] This creates a particularly closed cycle of the hydrogen storage medium.

Claims

Patent claims 1. A method for providing hydrogen gas comprising reforming an at least partially discharged hydrogen carrier medium (HO-LOHC) on a reforming catalyst using steam in a reforming reactor (3) to form an at least partially oxidized hydrogen carrier medium (Oxo-LOHC) with formation of hydrogen gas (H2) from the steam.

2. Process according to claim 1, characterized in that the at least partially oxidized hydrogen carrier medium (oxo-LOHC) formed during the reforming comprises at least one aromatic keto compound, at least one aromatic aldehyde compound and / or at least one aromatic keto-aldehyde compound.

3. Process according to one of the preceding claims, characterized in that the reforming takes place with the addition of heat.

4. Process according to one of the preceding claims, characterized in that the at least partially discharged hydrogen carrier medium (HO-LOHC) and the steam are fed to the reforming reactor (3) simultaneously or with a time delay.

5. Process according to one of the preceding claims, characterized in that for the reforming at least a stoichiometric amount of water vapor relative to the at least partially discharged hydrogen carrier medium (HO-LOHC) is present, in particular a superstoichiometric amount of water vapor, wherein in particular the molar ratio of the water vapor to the at least partially discharged hydrogen carrier medium (HO-LOHC) is between 1 and 500, in particular between 1.1 and 100 and in particular between 1.2 and 10.

6. Process according to one of the preceding claims, characterized in that the reforming reactor (3) has a molecular oxygen content of less than 10 vol.%. Process according to one of the preceding claims, characterized by dehydrogenating an at least partially loaded hydrogen carrier medium (Hx-LOHC) on a dehydrogenation catalyst to an at least partially discharged hydrogen carrier medium (H0-LOHC) in a dehydrogenation reactor (2) and thereby releasing hydrogen gas (H2), wherein in particular the hydrogen carrier medium (HO-LOHC) at least partially discharged in the dehydrogenation reactor (2) is subsequently reformed in the reforming reactor (3).A method for storing hydrogen gas, comprising hydrogenating at least partially oxidized hydrogen carrier medium (Oxo-LOHC), which has been produced in particular using a method according to one of the preceding claims, and / or at least partially discharged hydrogen carrier medium (HO-LOHC), which has been produced in particular using a method according to one of the preceding claims, with hydrogen gas over a hydrogenation catalyst to form an at least partially loaded hydrogen carrier medium (Hx-LOHC) in a hydrogenation reactor (4) with the formation of water. A circulation method comprising at least the method steps of claims 1 and 8. A circulation method according to claim 9, characterized by transporting the at least partially oxidized hydrogen carrier medium (Oxo-LOHC) and / or the at least partially discharged hydrogen carrier medium (HO-LOHC) to the hydrogenation reactor (4).A circulation process according to claim 9 or 10, characterized by transporting the at least partially loaded hydrogen carrier medium (Hx-LOHC) to the dehydrogenation reactor (2) and / or to a combination of dehydrogenation reactor (2) and reforming reactor (3). A device for providing hydrogen gas, comprising a reforming reactor (3) with a reforming catalyst for reforming an at least partially discharged hydrogen carrier medium (HO-LOHC) with steam to form an at least partially oxidized hydrogen carrier medium (Oxo-LOHC) and hydrogen gas, wherein a steam supply line (47) for supplying steam is connected to the reforming reactor (3).

13. Device according to claim 12, characterized by a dehydrogenation reactor (2) with a dehydrogenation catalyst for dehydrogenating an at least partially loaded hydrogen carrier medium (Hx-LOHC) to an at least partially discharged hydrogen carrier medium (HO-LOHC) and thereby releasing hydrogen gas (H2), wherein the dehydrogenation reactor (2) is fluidically connected to the reforming reactor (3) for supplying at least partially discharged hydrogen carrier medium (HO-LOHC), in particular by means of a fluid line (25, 35).

14. Device according to claim 12 or 13, characterized by a hydrogenation reactor (4) with a hydrogenation catalyst for hydrogenating at least partially oxidized hydrogen carrier medium (Oxo-LOHC) and / or at least partially discharged hydrogen carrier medium (HO-LOHC) to an at least partially loaded hydrogen carrier medium (Hx-LOHC).

15. Device according to claim 14, characterized in that the hydrogenation reactor (4), the dehydrogenation reactor (2) and the reforming reactor (3) form a fluidically closed circuit arrangement (5) for the hydrogen carrier medium.

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