System and process for producing synthetic fuels

Abstract

The present invention relates to a system and a process for producing synthetic fuels that are characterized in that they allow a load-flexible mode of operation when using fluctuating energy sources.

Description

[0001] DESCRIPTION

[0002] Plant and process for the production of synthetic fuels

[0003] The present invention relates to a plant and a method for producing synthetic fuels, which are characterized by the possibility of load-flexible operation using fluctuating energy sources.

[0004] Increasing global warming is having far-reaching impacts on people and the environment. The main driving force of global warming is the greenhouse effect, which is based on the fact that short-wave radiation from the sun penetrates the Earth's atmosphere largely unhindered. A significant proportion of the reflected infrared radiation that is not absorbed by the Earth's surface can no longer leave the Earth's atmosphere but is absorbed by greenhouse gases in the Earth's atmosphere. Many of the greenhouse gases are natural components of the Earth's atmosphere. However, since industrialization, the concentration of some of the gases has risen sharply. This particularly applies to human-caused emissions of carbon dioxide (CO2), which is increasingly accumulating in the Earth's atmosphere. Other greenhouse gases are emitted by humans in far smaller quantities. Although methane is 25 times more potent as a greenhouse gas, its approximately 100% carbon dioxide (CO2) is the most potent greenhouse gas.12.4 years, a significantly shorter lifespan than CO2 in the atmosphere. Nitrous oxide (N2O) is also a long-lived greenhouse gas that accumulates in the atmosphere over decades and centuries. In view of the far-reaching consequences of ongoing global warming, decisive action must be taken to limit the increase in the earth's average temperature as quickly and significantly as possible. To achieve this goal, 197 countries committed themselves at the 2015 UN Climate Change Conference in Paris to limit global warming to well below 2°C and, if possible, to 1.5°C, and to achieving greenhouse gas neutrality worldwide by the second half of the century at the latest. In order to achieve the set climate targets, the consumption of fossil fuels must be significantly reduced.

[0005] Anthropogenic CCL emissions account for approximately 3% of total annual CO2 emissions. The traffic and transport sector is responsible for approximately a quarter of global anthropogenic CCL emissions, with global aviation accounting for approximately 3.5%. To make traffic and transport sustainable and as climate-neutral as possible, the goal of using CO2 as an important carbon source for the production of sustainably produced synthetic fuels (e-fuels) has been pursued for years. In the so-called Power-to-X (PtX) or Power-to-Liquid (PtL) processes, the greenhouse gas CO2 is converted with hydrogen to form energy-rich hydrocarbon compounds that can be used as synthetic fuels.Due to its high chemical stability and low reactivity, CO2 must first be converted into CO for many applications, which can then be processed into valuable products in subsequent reaction steps (e.g., methanol synthesis, Fischer-Tropsch reaction, carbonylation, etc.). However, the number of industrially interesting CO2 activation reactions is limited by thermodynamic and technical considerations. One way to convert CO2 to CO is via the reverse water-gas shift reaction (RWGS). In this reaction, CO2 and H2 are catalytically converted to CO and H2O. Its counterpart, the water-gas shift reaction (WGS), has been intensively researched because it represents a relevant side reaction in important large-scale industrial processes (steam reforming, methanol synthesis, syngas conditioning, etc.).The conversion of existing value chains to new raw materials has also led to an increase in research and development activities in RWGS in recent years. RWGS has been demonstrated on a pilot scale, and several projects are planning the construction and commissioning of an RWGS reactor in connection with the production of e-fuels. The limited interest in RWGS to date is primarily due to the thermodynamically based, severe limitations on the achievable CO2 conversion (50-60%) and the selectivity to CO. The RWGS reaction is mildly endothermic and subject to a thermodynamic equilibrium that only allows relevant CO concentrations in the product stream at very high operating temperatures above 800 °C. The required high temperatures lead to high energy costs and also pose particular challenges for plant design, as standard metallic materials cannot generally be used in this case.Furthermore, excessively low reaction temperatures promote undesirable methane formation. Therefore, RWGS automatically involves complex downstream processing of the product mixture and high recycle rates of the remaining CO2.

[0006] A particular challenge in the production of synthetic fuels using PtX or PtL processes is that the electrical energy sourced from the grid can be subject to significant price fluctuations and / or the availability of electrical energy generated from renewable energy sources is subject to significant weather-related, daily, and seasonal fluctuations. Wind and solar energy are the fastest-growing and most cost-effective sources of electricity generation. The provision of renewable electricity from wind and solar energy inevitably leads to periods of high and low energy availability. This fluctuation includes both short-term (hourly / daily) and long-term (seasonal) components. In the production of synthetic fuels from CO2, H2O, and electricity from renewable energy sources, energy costs account for the largest share of production costs.To maximize the profitability of a production plant or to enable operation at sites directly connected to renewable energy generation, varying availability and the associated price must be taken into account. State-of-the-art technology uses batteries as energy storage devices and tanks for short-term hydrogen storage. Calculations show that by flexibly adapting plant load to the availability of renewable electricity, a significant amount of storage capacity can be saved, thus reducing production costs by 20–35% (Chao Chen and Aidong Yang, "Power-to-methanol: The role of process flexibility in the integration of variable renewable energy into chemical production," Energy Conversion and Management, 2021, Vol. 228, 113673).The most efficient and economical operation of a plant for the production of synthetic fuels using fluctuating energy sources therefore requires the possibility of carrying out the production process in a load-flexible manner on the one hand and, on the other hand, of being able to store excess hydrogen over a longer period of time and at the same time efficiently in times of high energy availability in order to be able to use this hydrogen to continue operating the plant in times of low energy availability.

[0007] The systems and methods known from the prior art cannot meet these requirements. The present invention therefore aims to overcome the disadvantages of the systems and methods known from the prior art.

[0008] The present invention solves the underlying problem, in particular through the subject matter of the independent claims. The plant according to the invention for producing synthetic hydrocarbons is superior to the prior art, in particular in that its design enables load-flexible operation and, associated with it, continuous operation depending on fluctuating energy sources. This opens up new production sites, as well as greater profitability through the utilization of a higher proportion of inexpensive and, in particular, renewable energy. The invention particularly relates to a plant for producing synthetic fuels, comprising: at least one energy source, at least one hydrogen source, at least one carbon dioxide source, at least one hydrogen buffer storage device with a sensor system for determining the fill level, at least one reactor system for releasing and storing hydrogen,comprising i) at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers, ii) at least one storage unit for hydrogenated hydrogen carriers with a sensor system for determining the fill level, and iii) at least one storage unit for dehydrogenated hydrogen carriers with a sensor system for determining the fill level, at least one unit for producing synthesis gas, comprising at least one reactor for the reverse water gas shift reaction in the chemical looping process (RWGS-CL), at least one Fischer-Tropsch reactor, and at least one process control system, wherein the at least one reactor system for releasing and storing hydrogen and the at least one unit for producing synthesis gas are connected to the hydrogen buffer storage, wherein a thermal coupling exists between the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers and the at least one Fischer-Tropsch reactor,and wherein the process control system is designed and configured such that the amount of hydrogen provided by the hydrogen source and the fill levels of the at least one hydrogen buffer storage, the at least one storage for hydrogenated hydrogen carriers, and the at least one storage for dehydrogenated hydrogen carriers are continuously recorded, and that the mass flow of hydrogen into the at least one unit for producing synthesis gas and into the at least one reactor system for storing hydrogen can be regulated depending on the amount of hydrogen provided by the hydrogen source and the fill levels of the at least one hydrogen buffer storage, the at least one storage for hydrogenated hydrogen carriers, and the at least one storage for dehydrogenated hydrogen carriers.

[0009] The plant according to the invention comprises a combination of a storage facility for the long-term (seasonal) storage of hydrogen in the form of hydrogenated hydrogen carriers and a particularly load-flexible two-stage hydrocarbon synthesis process, which are connected by an adaptively controlled hydrogen buffer storage facility. The exceptional load flexibility of the hydrocarbon synthesis in the plant according to the invention is ensured in particular by a novel coupling of the load-flexible synthesis gas production with a Fischer-Tropsch reactor. The special design of the synthesis gas production in the RWGS-CL process, with spatially or temporally separated partial reactions, contributes to load flexibility through its discontinuous or semi-continuous operation.Furthermore, this method achieves a particularly high CCL conversion, which significantly reduces the interdependence of synthesis gas and hydrocarbon production and enables new degrees of freedom and flexibility in the process control of the entire plant. Furthermore, the plant according to the invention is characterized by the fact that the energy released during hydrocarbon production in the Fischer-Tropsch reactor can be used for the storage and release of hydrogen through thermal coupling with the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers.

[0010] The operation of the system according to the invention is characterized by its efficient implementation in the face of fluctuating energy input, such as occurs when using renewable energy sources. The system is designed so that the required energy can be obtained either exclusively from renewable energy sources, such as wind turbines and photovoltaic systems, and / or from the power grid. The fluctuation in available energy can therefore be caused by fluctuating output from renewable energy sources or by price-dependent grid energy purchases.

[0011] In a preferred embodiment of the present invention, the at least one energy source is a fluctuating energy source, preferably a renewable energy source. Preferably, the at least one energy source, in particular the fluctuating energy source, preferably the renewable energy source, is selected from solar energy, wind energy, bioenergy, geothermal energy, hydropower, wave energy, nuclear energy, fusion energy, and industrial, commercial, or municipal waste heat.

[0012] Preferably, the at least one energy source, in particular the fluctuating energy source, preferably the renewable energy source, is a decentralized power generation plant.

[0013] According to a further embodiment of the present invention, the at least one energy source, in particular the fluctuating energy source, preferably the renewable energy source, is a power collection device for the purchase of energy from a central power generation plant.

[0014] Accordingly, it can be provided according to the invention that the energy source is a power generation plant of the plant according to the invention itself, preferably a decentralized power generation plant, in particular a wind turbine and / or a photovoltaic plant.

[0015] According to the invention, it can also be provided that the at least one energy source of the system is a power collection device, preferably a system for obtaining energy, preferably renewable energy, from the power grid. According to this embodiment of the present invention, the power generation system itself is not part of the system.

[0016] According to a further preferred embodiment of the present invention, it can also be provided that the at least one energy source of the system, in particular the fluctuating energy source, preferably the renewable energy source, comprises a power generation system, preferably a decentralized power generation system, in particular a wind turbine and / or a photovoltaic system, and additionally has a power collection device, preferably a system for the procurement of energy, preferably renewable energy, from a central power generation system, preferably from the power grid.

[0017] In a preferred embodiment of the present invention, the plant for producing synthetic fuels comprises an energy storage device, in particular at least one accumulator. Preferably, the at least one energy source of the plant is connected to at least one energy storage device, in particular to at least one accumulator.

[0018] Especially when operating the system without a connection to the power grid, intermediate storage of electricity in a suitable energy storage system may be necessary. The capacity of the energy storage system should be adapted to the prevailing energy profile in order to bridge the expected longest period without energy availability. However, due to the high cost of energy storage systems, the capacity should be kept as low as possible.

[0019] According to a preferred embodiment of the present invention, the at least one hydrogen source of the plant is at least one electrolyzer.

[0020] Preferably, the at least one electrolyzer is selected from the group consisting of alkaline electrolyzers, proton exchange membrane electrolyzers (PEM), anion exchange membrane electrolyzers (AEM), high-temperature electrolyzers (HTEL), in particular solid oxide electrolyzers (SOEC), chloralki electrolyzers, E-TAC electrolyzers.

[0021] Particularly preferably, the at least one electrolyzer is a PEM electrolyzer. This is characterized by short start-up times from cold and warm standby modes and reliable operation in the partial load range. In a preferred embodiment, the at least one electrolyzer is operated with energy from the at least one energy source, in particular the at least one fluctuating energy source, particularly preferably the at least one renewable energy source, and, if necessary, is additionally supplied with energy from at least one energy storage device.

[0022] According to a further preferred embodiment of the present invention, the at least one hydrogen source of the plant is hydrogen from thermocatalytic processes. Preferably, the at least one hydrogen source is a conventional thermochemical hydrogen production process, in particular steam or dry reforming, partial oxidation, autothermal reforming, shift reaction, pyrolysis, or gasification. In a further preferred embodiment, the at least one hydrogen source is an unconventional thermochemical hydrogen production process, in particular selected from plasma cracking (Kvserner process), thermal dissociation, thermochemical cycle processes, and metal oxide processes.

[0023] According to the invention, it can also be provided that the at least one hydrogen source of the plant is hydrogen from a biocatalytic or bioelectrocatalytic process, in particular hydrogen from fermentation, oxygenic or anoxygenic photosynthesis.

[0024] In a further preferred embodiment, the at least one hydrogen source of the plant is hydrogen from photocatalytic or photoelectrocatalytic processes.

[0025] Preferably, the at least one hydrogen source of the plant may be hydrogen from the discharge / dehydrogenation of hydrogen carriers, such as liquid organic hydrogen carriers (LOHC), ammonia, methanol or metal hydrides.

[0026] According to a preferred embodiment, the carbon dioxide source is selected from anthropospheric, atmospheric, lithospheric and hydrospheric carbon dioxide sources.

[0027] The carbon dioxide source is preferably selected from anthropospheric carbon dioxide sources, in particular from carbon dioxide sources from industrial, commercial or municipal production processes, such as biogas production by gasification, anaerobic fermentation, pyrolysis, hydrothermal liquefaction, fermentation, hydrolysis, transesterification, sugar-to-hydrocarbon reforming (DSHC), as well as exhaust gases from cement production, exhaust gases from steel production, exhaust gases from conventional chemical processes, as well as exhaust gases from beverage and food production and agriculture, from carbon dioxide sources from industrial, commercial or municipal heat or power generation, such as the paper, pulp and wood industries, biomass combustion, biomass-driven cogeneration processes, geothermal processes, or from carbon dioxide sources from industrial, commercial or municipal waste utilization, such as waste incineration, incineration of sewage sludge, combustion of fermentation gases.

[0028] In a particularly preferred embodiment, the carbon dioxide source is selected from atmospheric carbon dioxide sources, in particular the carbon dioxide source is carbon dioxide from direct air capture (DAC) from the ambient air, exhaust air, or room air.

[0029] Preferably, the carbon dioxide source is selected from lithospheric carbon dioxide sources, in particular the carbon dioxide source is carbon dioxide from geological sources, such as gas springs, thermal springs, geysers, and volcanoes.

[0030] According to a further preferred embodiment of the present invention, the carbon dioxide source is selected from hydrospheric carbon dioxide sources, in particular the carbon dioxide source is carbon dioxide from seas and lakes.

[0031] In a particularly preferred embodiment, the plant according to the invention comprises a device for concentrating, purifying, and / or compressing carbon dioxide from the carbon dioxide source. Particularly preferably, there is a thermal coupling between the one device for concentrating, purifying, and / or compressing carbon dioxide and the at least one Fischer-Tropsch reactor.

[0032] In a preferred embodiment of the present invention, the at least one hydrogen buffer storage device is a storage device for gaseous hydrogen.

[0033] Preferably, the at least one hydrogen buffer storage has a capacity calculated from i) time-dependent energy availability, in particular the longest expected period without energy supply, ii) minimum utilization of the system required for stable operation, and iii) speed of load change.

[0034] In a particularly preferred embodiment, the sensor system for determining the fill level of the hydrogen buffer storage is a pressure sensor, in particular a pressure gauge. According to the invention, the fill level of the hydrogen buffer storage determined by the sensor system is continuously transmitted to the plant's process control system and recorded by it.

[0035] According to the invention, the at least one hydrogen buffer storage unit is connected to the at least one hydrogen source, preferably the at least one electrolyzer, to the at least one reactor system for releasing and storing hydrogen, and to the at least one unit for producing synthesis gas. In a further preferred embodiment, it can be provided that the at least one hydrogen buffer storage unit is additionally connected to a device for adjusting the synthesis gas flow or to the pipeline upstream of the Fischer-Tropsch reactor. In this way, hydrogen from the hydrogen buffer storage unit can be used to adjust a suitable synthesis gas composition for the production of synthetic hydrocarbon compounds in the Fischer-Tropsch reactor.

[0036] The at least one hydrogen buffer storage unit forms the central hub for the mass flow of hydrogen from the at least one hydrogen source into the at least one unit for producing synthesis gas and / or into or out of the at least one reactor system for releasing and storing hydrogen. The mass flows are preferably adaptively controlled by the plant's process control system depending on the amount of hydrogen provided by the hydrogen source and the fill levels of the at least one hydrogen buffer storage unit, the at least one storage unit for hydrogenated hydrogen carriers, and the at least one storage unit for dehydrogenated hydrogen carriers.For example, if the fill level of the at least one hydrogen buffer storage exceeds an upper limit, the at least one unit for producing synthesis gas and the at least one reactor system for releasing and storing hydrogen are supplied with hydrogen (hydrogen storage through the hydrogenation of hydrogen carriers). If the fill level falls below this upper limit, only, or at least largely, the at least one unit for producing synthesis gas is supplied with hydrogen.If the upper limit is undershot and an insufficient amount of hydrogen is provided by the at least one hydrogen source, or if the fill level of the hydrogen buffer storage falls below a lower limit for a certain period of time, hydrogen is released from hydrogenated hydrogen carriers in the at least one storage for hydrogenated hydrogen carriers in the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers (hydrogen release through the dehydrogenation of hydrogen carriers). The hydrogen released from the hydrogenated hydrogen carriers can either initially be fed into the at least one hydrogen buffer storage or directly into the at least one unit for producing synthesis gas. The respective upper and lower limits of the fill levels can be set to statistically determined values ​​(e.g.to 80% of the maximum value for the upper limit and 20% above the required minimum value for the lower limit) or depending on the expected availability of energy and / or hydrogen (e.g., based on weather forecasts, electricity / hydrogen cost forecasts, etc.). The upper limit must be compatible with the required minimum pressure for the hydrogenation of dehydrogenated hydrogen carriers in the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers.

[0037] Particularly preferably, the adaptive regulation of the mass flow of hydrogen is valve-controlled by the process control system.

[0038] However, hydrogen buffer storage is not suitable for long-term, especially seasonal, storage of gaseous hydrogen, as the required capacities would entail very high investment costs, and pressure tanks would be subject to high leakage rates, thus making efficient, long-term storage difficult overall. However, storing hydrogen in a reversibly chemically bound form, particularly in the form of liquid hydrogen carriers or metal hydrides, is well suited for this application over periods of several weeks to several months.

[0039] According to the invention, the plant for producing synthetic fuels has at least one reactor system for releasing and storing hydrogen, comprising i) at least one reactor for hydrogenating and dehydrogenating hydrogen carriers, ii) at least one storage device for hydrogenated hydrogen carriers with a sensor system for determining the fill level, and iii) at least one storage device for dehydrogenated hydrogen carriers with a sensor system for determining the fill level.

[0040] In a particularly preferred embodiment of the present invention, the hydrogenation and dehydrogenation of hydrogen carriers take place in the same reactor.

[0041] Preferably, the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers comprises a catalyst which, depending on the reaction conditions, can catalyze both the hydrogenation and the dehydrogenation of hydrogen carriers.

[0042] The catalyst is particularly preferably a metal catalyst, preferably a noble metal catalyst, with one or more metals selected from the group consisting of transition groups 8, 9, 10, preferably from the group consisting of Pt, Ru, Rh, Pd and Ni, and wherein the metal, in particular the noble metal, is preferably deposited in an egg-shell structure on a porous metal oxide, preferably on Al2O3, SiCl or TiCh.

[0043] To store excess hydrogen in the at least one reactor system for releasing and storing hydrogen, the gaseous hydrogen is brought into contact with a catalyst and a dehydrogenated hydrogen carrier at elevated pressure, preferably at 1 to 8 MPa (10 to 80 bar), and at a hydrogenation temperature of preferably 150 to 310 °C in the at least one reactor for hydrogenating and dehydrogenating hydrogen carriers. Once the reaction has been initiated, the exothermic hydrogenation reaction provides sufficient heat for the required temperature level. The hydrogenated hydrogen carriers are then transferred to the at least one storage facility for hydrogenated hydrogen carriers and stored therein.For the release of hydrogen from hydrogenated hydrogen carriers, the reversibly chemically bound hydrogen is released from the stored hydrogenated hydrogen carriers by a dehydrogenation reaction on a catalyst at low pressure, preferably at 0.1 to 0.5 MPa (1 to 5 bar), and an elevated temperature of preferably 260 to 320 °C.

[0044] According to the invention, the at least one reactor system for releasing and storing hydrogen comprises, in addition to the at least one reactor for hydrogenating and dehydrogenating hydrogen carriers, at least one storage device for hydrogenated hydrogen carriers with a sensor system for determining the fill level and at least one storage device for dehydrogenated hydrogen carriers with a sensor system for determining the fill level, wherein the at least two storage devices enable separate storage of hydrogenated and dehydrogenated hydrogen carriers.

[0045] Preferably, the at least one storage for hydrogenated hydrogen carriers and the at least one storage for dehydrogenated hydrogen carriers are each connected to the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers via at least one line, preferably via at least two lines, particularly preferably via an inlet and an outlet each.

[0046] According to the invention, a thermal coupling exists between the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers and the at least one Fischer-Tropsch reactor of the plant. In a particularly preferred embodiment of the present invention, the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers has at least one heat exchanger. The at least one heat exchanger is preferably connected to the overall plant in such a way that the heat required for the dehydrogenation reaction (hydrogen release) can be provided at least partially from the waste heat from the overall plant, in particular from the Fischer-Tropsch reactor. The thermal coupling can significantly reduce storage costs and losses.

[0047] Preferably, the hydrogen carrier is a gaseous, liquid or solid hydrogen carrier.

[0048] In a particularly preferred embodiment of the present invention, the hydrogen carrier is a liquid or solid hydrogen carrier, particularly preferably a liquid hydrogen carrier.

[0049] Preferably, the hydrogen carrier is selected from the group consisting of methanol, ammonia, toluene / methylcyclohexane (TOL / MCH), benzene / cyclohexane (BZ / CHE), N-ethylcarbazole (NEC), dibenzyltoluene (DBT), benzyltoluene (BT), naphthalene / decalin (NAP), azaborines, and metal hydrides, in particular magnesium hydride (MgEE), sodium aluminum hydride (NaAlEE), lithium aluminum hydride (LiAlEL), lithium hydride (LiH), lanthanum nickel hydride (LaNisEfc), titanium iron hydride (TiFeEL), ammonia borane / borazane, palladium hydride.

[0050] The hydrogen carrier is particularly preferably a liquid hydrogen carrier, in particular a liquid organic hydrogen carrier (LOHC). In a preferred embodiment, the liquid organic hydrogen carrier (LOHC) is selected from the group consisting of toluene / methylcyclohexane (TOL / MCH), benzene (BZ), N-ethylcarbazole (NEC), dibenzyltoluene (DBT), benzyltoluene (BT), naphthalene / decalin (NAP), and azaborines.

[0051] In a particularly preferred embodiment, the liquid hydrogen carrier, in particular the liquid organic hydrogen carrier (LOHC), has a hydrogen storage capacity of at least 2 wt.%, preferably at least 2.5 wt.%, preferably at least 3 wt.%, preferably at least 3.5 wt.%, preferably at least 4 wt.%, preferably at least 4.5 wt.%, preferably at least 5 wt.%, preferably at least 5.5 wt.%, preferably at least 6 wt.%, preferably at least 6.5 wt.%, preferably at least 7 wt.%.

[0052] According to a preferred embodiment of the present invention, the liquid hydrogen carrier, in particular the liquid organic hydrogen carrier (LOHC), has a hydrogen storage capacity of at most 20 wt.%, preferably at most 18 wt.%, preferably at most 16 wt.%, preferably at most 15 wt.%, preferably at most 14 wt.%, preferably at most 13 wt.%, preferably at most 12 wt.%, preferably at most 11 wt.%, preferably at most 10 wt.%, preferably at most 9.5 wt.%, preferably at most 9 wt.%, preferably at most 8.5 wt.%, preferably at most 8 wt.%, preferably at most

[0053] 7.5 wt.%, preferably at most 7 wt.%.

[0054] Preferably, the liquid hydrogen carrier, in particular the liquid organic hydrogen carrier (LOHC), has a hydrogen storage capacity of 2 to 20 wt.%, preferably

[0055] 2.5 to 18 wt.%, preferably 3 to 16 wt.%, preferably 3.5 to 15 wt.%, preferably 4 to 14 wt.%, preferably 4.5 to 13 wt.%, preferably 5 to 12 wt.%, preferably 5.5 to 11 wt.%, preferably 6 to 10 wt.%, preferably 6.5 to 9 wt.%, preferably 7 to 9 wt.%.

[0056] In a preferred embodiment, the liquid hydrogen carrier, in particular the liquid organic hydrogen carrier (LOHC), at a reaction pressure of 1 to 8 MPa (10 to 80 bar) has a hydrogenation temperature of at most 350 °C, preferably at most 325 °C, preferably 300 °C, preferably at most 275 °C, preferably at most 250 °C, preferably at most 225 °C, preferably at most 200 °C, preferably at most 180 °C, preferably at most 160 °C, preferably at most 150 °C.

[0057] The liquid hydrogen carrier, in particular the liquid organic hydrogen carrier (LOHC), preferably has a dehydrogenation temperature of at most 350 °C, preferably at most 340 °C, preferably at most 330 °C, preferably at most 320 °C, preferably at most 310 °C, preferably at most 300 °C, preferably at most 290 °C, preferably at most 280 °C, preferably at most 270 °C, preferably at most 260 °C, at a reaction pressure of 0.1 to 0.5 MPa (1 to 5 bar).

[0058] In a particularly preferred embodiment of the present invention, the at least one storage device for hydrogenated hydrogen carriers and / or the at least one storage device for dehydrogenated hydrogen carriers have at least one connection for the removal and / or supply of hydrogen carriers.

[0059] A particular advantage of using liquid hydrogen carriers, especially liquid organic hydrogen carriers (LOHC), is the ability to extract hydrogenated or dehydrogenated hydrogen carriers from or add them to storage facilities as needed, using the existing infrastructure for liquid fuels, for example, by delivery or collection by tanker trucks. Synthesis gas is preferably produced in the at least one reactor for the reverse water-gas shift reaction in the chemical looping process (RWGS-CL) in two partial reactions (oxidation and reduction) using an oxygen storage material (OSM).

[0060] In a preferred embodiment of the present invention, the oxygen storage material (OSM) is in the form of a reducible oxide.

[0061] Particularly preferably, the oxygen storage material (OSM) is at least one reducible oxide of a metal or a mixture of several metals, in particular at least one reducible oxide of a metal or a mixture of several metals selected from Fe, Zr, Ce, Ni, Co, Zn, and In.

[0062] In a preferred embodiment, the oxygen storage material (OSM) is at least one perovskite.

[0063] Particularly preferably, the reducible oxide, in particular the perovskite, is applied to a high-surface area support, in particular to a metal oxide selected from Al2O3, SiO2, TiO2. The support particularly preferably has a surface area of ​​at least 100 m 2 / g, preferably at least 200 m 2 / g, preferably at least 300 m 2 / g, preferably at least 400 m 2 / g, preferably at least 500 m 2 / g, preferably at least 600 m 2 / g, preferably at least 700 m 2 / g, preferably at least 800 m 2 / g, preferably at least 900 m 2 / g, preferably at least 1000 m 2 / G.

[0064] In a further embodiment, the reducible oxide, in particular the perovskite, particularly preferably the reducible oxide, in particular perovskite, applied to a high-surface area support, is additionally promoted with further (transition) metals.

[0065] During the oxidation of the oxygen storage material (OSM), the CO2 from the at least one carbon dioxide source is converted into CO. In a second step, the oxygen storage material (OSM) is reduced / regenerated by converting H2 to H2O. Both reactions proceed at similar temperatures in the range of 400 to 900 °C, preferably 425 to 800 °C, particularly preferably 450 to 650 °C. The reaction pressure is preferably 0.1 to 3 MPa (1 to 30 bar), preferably 0.5 to 2.5 MPa (5 to 25 bar), preferably 0.75 to 2 MPa (7.5 to 20 bar).

[0066] In a preferred embodiment of the present invention, the oxidation and reduction in the at least one RWGS-CL reactor proceed spatially or temporally separated from one another. The time of the change from CCh feed (oxidation) to H2 feed (reduction) is preferably determined by a fixed period of time or a fixed feed volume of the respective gas and / or is dependent on measured CO2 / CO / H2O / H2 concentrations and / or dependent on measurements of the temperature in the reactor.

[0067] Preferably, the at least one unit for producing synthesis gas comprises at least one RWGS-CL reactor in which the oxidation and reduction take place at different times. If oxidation and reduction are separated in time, an RWGS-CL reactor is used in which the two partial reactions (oxidation and reduction) take place one after the other. Thus, according to this embodiment, the production of CO takes place discontinuously. It can be provided that the at least one unit for producing synthesis gas additionally has a downstream intermediate storage facility for the synthesis gas produced in the at least one RWGS-CL reactor.

[0068] In a further preferred embodiment of the present invention, the at least one unit for producing synthesis gas comprises at least two RWGS-CL reactors, preferably exactly two RWGS-CL reactors, in which reduction and oxidation take place spatially separated from one another. In the case of spatial separation of oxidation and reduction, two or more RWGS-CL reactors are used, in which both partial reactions (oxidation and reduction) take place in parallel. In a particularly preferred embodiment, the number of RWGS-CL reactors is limited to two. Preferably, the oxygen storage material (OSM) and the reaction conditions are selected such that the regeneration / reduction of the oxygen storage material (OSM) with H2 (reduction reaction) in the first RWGS-CL reactor takes place at least as quickly or faster than the oxidation of the oxygen storage material (OSM) with CO2 (oxidation reaction) in the second RWGS-CL reactor.Such a reaction regime advantageously allows for a (semi-)continuous production of CO. As a result, the buffer volume of an optional downstream intermediate storage facility in the at least one unit for producing synthesis gas can be made smaller, or an intermediate storage facility can be omitted altogether.

[0069] Discontinuous or semi-continuous reaction control advantageously enables load-flexible operation of syngas production, as a defined H2 / CO2 ratio does not have to be maintained at all times, as is the case when both reactions occur simultaneously in a single reactor. In the event of a hydrogen shortage or a sudden drop in reaction temperature, the regeneration of the oxygen storage material (OSM) slows down, which can be more easily compensated for by adjusting the time before switching the gas supply. In contrast to conventional process control, a shortage of hydrogen supply or a reduction in the total volume flow leads to significantly less coking. Furthermore, the formation of undesirable byproducts of syngas production, particularly methane, is almost completely avoided, regardless of fluctuating reaction temperatures.

[0070] Preferably, the product mixture obtained in the at least one unit for producing synthesis gas, in particular the synthesis gas, has an H2 / CO ratio of < 2.4, preferably < 2.2, preferably < 2, preferably < 1.9, preferably < 1.8, preferably < 1.7, preferably < 1.6.

[0071] According to a preferred embodiment, a hydrogen / water (H2 / H2O) stream and a separate carbon monoxide / carbon dioxide (CO / CO2) stream are generated in the at least one unit for producing synthesis gas.

[0072] In a preferred embodiment of the present invention, the plant for producing synthetic fuels comprises a device for condensing water from the synthesis gas stream, in particular from the hydrogen / water (H2 / H2O) stream. Particularly preferably, the device for condensing water from the synthesis gas stream, in particular from the hydrogen / water (H2 / H2O) stream, is arranged between the at least one unit for producing synthesis gas and the at least one Fischer-Tropsch reactor. In the device for condensing water, the resulting process water is condensed and separated by cooling the synthesis gas stream, in particular the hydrogen / water (H2 / H2O) stream.In the case of separation of the partial reactions (oxidation and reduction) in synthesis gas production, i.e., in the production of a hydrogen / water (H2 / H2O) stream and a separate carbon monoxide / carbon dioxide (CO / CO2) stream, only the hydrogen / water (H2 / H2O) stream is fed to the device for condensing water, so that an H2 stream is obtained.

[0073] In a preferred embodiment, the plant for producing synthetic fuels additionally comprises a separate device for adjusting the synthesis gas flow. According to this embodiment, the synthesis gas produced in the at least one synthesis gas production unit is mixed, if required, with additional hydrogen from the hydrogen buffer storage in the device for adjusting the synthesis gas flow to obtain an H2 / CO ratio of 1.4 to 2.2, preferably 1.6 to 2.0, corresponding to the synthesis requirement of the Fischer-Tropsch reactor.In the case of spatial separation of the partial reactions (oxidation and reduction) in synthesis gas production, i.e., in the generation of a hydrogen / water (H2 / H2O) stream and a separate carbon monoxide / carbon dioxide (CO / CO2) stream, followed by condensation and separation of water from the hydrogen / water (H2 / H2O) stream, the resulting hydrogen (H2) stream and the carbon monoxide / carbon dioxide (CO / CO2) stream are mixed together in the device for adjusting the synthesis gas stream in the desired ratio, preferably to an H2 / CO ratio of 1.4 to 2.2, preferably 1.6 to 2.0. If necessary, additional hydrogen can be added from the hydrogen buffer storage.In the case of the temporal separation of the partial reactions (oxidation and reduction) in synthesis gas production, the device for adjusting the synthesis gas flow can be the intermediate storage for discontinuously occurring synthesis gas.

[0074] In a further preferred embodiment of the present invention, the synthesis gas stream is adjusted with an H2 / CO ratio of 1.4 to 2.2, preferably 1.6 to 2.0, from the individual partial streams directly in the pipeline system.

[0075] For load-flexible operation with high CO2 conversions and decoupling of synthesis gas production in the at least one unit for producing synthesis gas and the production of synthetic hydrocarbon compounds in the Fischer-Tropsch reactor, the unconverted synthesis gas from the Fischer-Tropsch reactor can additionally be added.

[0076] To produce a synthesis gas with the required H2 / CO ratio, preferably with an H2 / CO ratio of 1.4 to 2.2, preferably 1.6 to 2.0, for the Fischer-Tropsch reactor from the individual substreams, the composition of the synthesis gas is measured online and the mass flows are controlled accordingly by the process control system. The synthesis gas flow can be adjusted by mixing the gas streams either in a separate device for adjusting the synthesis gas flow or directly in the piping system.

[0077] According to a preferred embodiment of the present invention, the at least one Fischer-Tropsch reactor of the plant is a fixed-bed reactor, a microstructured reactor, or a slurry bubble column reactor. Microstructured reactors and slurry bubble column reactors are particularly suitable for load-flexible operation due to their good heat distribution. Slurry bubble column reactors are particularly preferred due to further process-related advantages, such as high catalyst utilization, low pressure drop, and cost-effective construction. Cobalt-based catalysts are particularly suitable for the production of synthetic hydrocarbon compounds, especially liquid synthetic hydrocarbon compounds for use as fuels.

[0078] The heat generated during the production of synthetic hydrocarbon compounds in the Fischer-Tropsch reactor is preferably dissipated by a heat transfer medium via built-in cooling loops. For load-flexible operation with a slurry bubble column reactor, the cooling loops and the geometry of the gas inlet into the reactor are preferably selected to ensure operation with favorable bubble flow, minimal catalyst deposition on the internals, and low catalyst attrition over a wide flow rate range.

[0079] According to the invention, there is a thermal coupling between the at least one Fischer-Tropsch reactor and the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers, so that the heat generated in the Fischer-Tropsch reaction can be used in the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers.

[0080] The plant according to the invention for producing synthetic fuels preferably comprises a heat conduction system. The heat conduction system is preferably a steam network. Particularly preferably, the thermal coupling between the at least one Fischer-Tropsch reactor and the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers takes place via the plant's heat conduction system. In a preferred embodiment of the present invention, further heat-generating or heat-consuming components of the plant are connected to the heat conduction system. Preferably, any heat required for the separation / concentration and purification of carbon dioxide from the carbon dioxide source is provided at least partially via the plant's heat conduction system.

[0081] The hydrocarbon compounds produced from synthesis gas in the Fischer-Tropsch reactor include Fischer-Tropsch wax, Fischer-Tropsch oil, and gaseous hydrocarbon compounds. Process water is also produced. In a preferred embodiment, the plant according to the invention can comprise at least one unit for separating and / or processing the individual components of the product mixture from the Fischer-Tropsch process. Preferably, the Fischer-Tropsch wax and the Fischer-Tropsch oil are removed from the plant or fed to downstream processing steps, in particular subjected to at least one processing step selected from hydrocracking, hydrotreating, isomerization, distillation, and / or purification.

[0082] If downstream processing takes place on-site and a slurry process is used for the Fischer-Tropsch reaction, it is advantageous to use a downstream processing technology that allows for the management of catalyst residues without negatively impacting the performance or longevity of the downstream process. Furthermore, it is advantageous to feed the hydrogen required in downstream processing from the hydrogen buffer storage and / or the reactor system for hydrogen release and storage.

[0083] Due to their liquid form, the energy stored in the resulting hydrocarbon compounds from this step of the value chain can be transported and stored cost-effectively under simple conditions (normal pressure and normal temperature).

[0084] In addition to gaseous hydrocarbon compounds, particularly methane (CH4), the gaseous reaction products generally contain unconverted synthesis gas. This can either be removed from the plant, fed into energy generation through combustion or oxidation using fuel cells, recycled to the synthesis gas production process, optionally after an additional oxidation step, or preferably, as described above, fed into the device for adjusting the synthesis gas flow or the piping system leading to the Fischer-Tropsch reactor, or directly into the Fischer-Tropsch reactor.

[0085] The present invention further relates to a process for producing synthetic fuels, comprising the steps: a) providing electrical energy, water, and carbon dioxide, b) electrolyzing the water using the electrical energy provided in step a) to obtain hydrogen, c) storing the hydrogen produced in step b) in a hydrogen buffer storage, d) reacting hydrogen from the hydrogen buffer storage with the carbon dioxide provided in step a) in a unit for producing synthesis gas by means of a reverse water-gas shift reaction in the chemical looping process (RWGS-CL) to obtain a hydrogen / water (H2 / H2O) stream and a carbon monoxide / carbon dioxide (CO / CO2) stream, e) separating water from the H2 / H2O stream to obtain an H2 stream, f) producing synthesis gas by combining the CO / CCh stream from step d) and the H2 stream from step e),g) converting the synthesis gas obtained in step f) in a Fischer-Tropsch process to obtain synthetic hydrocarbon compounds, wherein the hydrogen buffer storage is connected to a reactor system for releasing and storing hydrogen, comprising i) at least one reactor for hydrogenating and dehydrogenating hydrogen carriers, ii) at least one storage for hydrogenated hydrogen carriers, and iii) at least one storage for dehydrogenated hydrogen carriers, wherein the fill levels of the hydrogen buffer storage, the at least one storage for hydrogenated hydrogen carriers, the at least one storage for dehydrogenated hydrogen carriers, and the amount of hydrogen produced in step b) are continuously recorded by sensors, wherein the hydrogen produced in step b) is continuously controlled by process control depending on the fill levels of the hydrogen buffer storage, the at least one storage for hydrogenated hydrogen carriers,of the at least one storage for dehydrogenated hydrogen carriers, and of the amount of hydrogen produced in step b) is fed to the unit for producing synthesis gas and / or is stored in the reactor system for releasing and storing hydrogen in the form of hydrogenated hydrogen carriers, or additional hydrogen is released from hydrogenated hydrogen carriers to be fed to the unit for producing synthesis gas, and wherein heat released in the Fischer-Tropsch process in step e) in the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers is used for the storage and release of hydrogen from hydrogen carriers.

[0086] In a preferred embodiment of the present invention, the hydrogen carrier is a liquid hydrogen carrier, particularly preferably a liquid organic hydrogen carrier (LOHC).

[0087] Preferably, the synthesis gas produced in step f) has an H2 / CO ratio of < 2.4, preferably < 2.2, preferably < 2, preferably < 1.9, preferably < 1.8, preferably < 1.7, preferably < 1.6.

[0088] In a further preferred embodiment of the present invention, the synthesis gas produced in step f) has an H2 / CO ratio of > 1.0, preferably > 1.2, preferably > 1.4, preferably > 1.5, preferably > 1.6, preferably > 1.7, preferably > 1.8, preferably > 1.9, preferably > 2.0.

[0089] Particularly preferably, the synthesis gas produced in step f) has an H2 / CO ratio of 1.4 to 2.2, preferably 1.6 to 2.0.

[0090] According to the invention, it can be provided that the synthetic hydrocarbon compounds obtained in step g) are subjected in a further step h) to at least one processing method selected from the group consisting of hydrocracking, hydrotreating, isomerization, distillation and purification.

[0091] In a preferred embodiment of the present invention, the synthetic hydrocarbon compounds obtained in step g), preferably the synthetic hydrocarbon compounds obtained after step h), have a proportion of Cs to C16 compounds of at least 20% by weight, preferably at least 25% by weight, preferably at least 30% by weight, preferably at least 35% by weight, preferably at least 40% by weight, preferably at least 45% by weight, preferably at least 50% by weight, preferably at least 55% by weight, preferably at least 60% by weight, preferably at least 65% by weight, preferably at least 70% by weight, preferably at least 75% by weight, preferably at least 80% by weight, preferably at least 85% by weight, preferably at least 90% by weight, preferably at least 95% by weight, preferably at least 96% by weight, preferably at least 97% by weight, preferably at least 98% by weight, preferably at least 99% by weight.

[0092] According to a preferred embodiment of the present invention, the synthetic hydrocarbon compounds obtained in step g), preferably the synthetic hydrocarbon compounds obtained after step h), have a proportion of compounds with < Cs of at most 20 wt.%, preferably at most 18 wt.%, preferably at most 16 wt.%, preferably at most 14 wt.%, preferably at most 12 wt.%, preferably at most 10 wt.%.

[0093] %, preferably at most 9 wt.%, preferably at most 8 wt.%, preferably at most 7 wt.%

[0094] %, preferably at most 6 wt.%, preferably at most 5 wt.%, preferably at most 4 wt.-

[0095] %, preferably at most 3 wt.%, preferably at most 2 wt.%, preferably at most 1 wt.-

[0096] %, on.

[0097] Preferably, the synthetic hydrocarbon compounds obtained in step g), preferably the synthetic hydrocarbon compounds obtained after step h), have a proportion of compounds with > Ci6 of at most 20 wt.%, preferably at most 18 wt.%, preferably at most 16 wt.%, preferably at most 14 wt.%, preferably at most 12 wt.%, preferably at most 10 wt.%, preferably at most 9 wt.%, preferably at most 8 wt.%, preferably at most 7 wt.%, preferably at most 6 wt.%, preferably at most 5 wt.%, preferably at most 4 wt.%, preferably at most 3 wt.%, preferably at most 2 wt.%, preferably at most 1 wt.%.

[0098] The present invention further relates to a fuel, in particular an aviation fuel, comprising synthetic hydrocarbon compounds which can be produced, in particular produced, by the process according to the invention.

[0099] The embodiments described and statements made in connection with the plant according to the invention for producing synthetic fuels also relate, mutatis mutandis, to the process according to the invention for producing synthetic fuels and vice versa.

[0100] Further embodiments of the present invention emerge from the subclaims.

[0101] In the context of the present invention, the term "energy source" refers to an energy carrier or converter that serves to generate useful energy. In the context of the present invention, a "fluctuating energy source" is understood to be an energy source that provides useful energy in a volatile manner over time and / or in terms of quantity, and in particular does not guarantee a continuous provision of useful energy over time and / or in terms of quantity. This means that the provision of useful energy is subject to temporal and / or quantitative fluctuations. The fluctuation can be caused either by the type of energy source itself, for example by the use of renewable energy sources such as wind power and solar energy, or by other factors, in particular economic factors, such as price fluctuations on the electricity market, in particular on the electricity market for energy from renewable energy sources.

[0102] In the context of the present invention, the term “process control system” refers to a measurement and control system for the detection, control and adaptive regulation of process flows and operating conditions in process engineering plants.The "process control system" serves in particular for the continuous recording and processing of information which is conveyed by the sensors of the plant, in particular the quantity of hydrogen provided by the hydrogen source of the plant according to the invention and the fill levels of the at least one hydrogen buffer storage, the at least one storage for dehydrogenated hydrogen carriers and the at least one storage for hydrogenated hydrogen carriers, in order to adaptively control the mass flow of hydrogen as a function of the quantity of available and required hydrogen as well as of the determined fill levels of the storage to the individual components of the plant, thereby enabling load-flexible operation of the plant using a fluctuating energy supply.

[0103] In the context of the present invention, "continuously detecting" means that a continuous detection takes place. According to the invention, the detection can take place during operation of the system at regular or irregular times, in particular at regular or irregular time intervals. In a preferred embodiment of the present invention, the detection takes place continuously and at all times during operation.

[0104] According to the invention, the term "fill level" refers to the loading state of a storage device in relation to its maximum loading capacity. The "fill level" of a storage device with liquid hydrogen storage materials, in particular liquid hydrogen carriers, can be determined, for example, via the relationship between the height of the liquid surface and the maximum height of the liquid in the storage device. For gaseous storage devices, a pressure measurement can preferably be carried out in order to calculate the fill level using the real gas law. For solid hydrogen storage materials, in particular absorption storage devices such as metal hydrides, the "fill level" can be estimated, for example, via changes in the equilibrium conditions (gas pressure / temperature) or via the material properties, such as the volume expansion behavior of metal hydrides.Another possibility for determining the “filling level” or the loading state of a storage facility with solid hydrogen storage materials is to carry out a balancing of the inlet and outlet volume flow of hydrogen when loading the storage facility and / or the outlet volume flow of hydrogen when discharging the storage facility.

[0105] In the context of the present invention, the terms "comprising" and "having" are understood to mean that, in addition to the elements explicitly covered by these terms, further, not explicitly mentioned elements can be added. In the context of the present invention, these terms are also understood to mean that only the explicitly mentioned elements are covered and no further elements are present. In this particular embodiment, the meaning of the terms "comprising" and "having" is synonymous with the term "consisting of". Furthermore, the terms "comprising" and "having" also encompass compositions which, in addition to the explicitly mentioned elements, also contain further elements not mentioned, which, however, are of a functionally and qualitatively subordinate nature. In this embodiment, the terms "comprising" and "having" are synonymous with the term "consisting essentially of".

[0106] In the context of the present invention, the term "and / or" means that all members of a group linked by the term "and / or" are disclosed both alternatively to one another and cumulatively among themselves in any combination. For the expression "A, B and / or C," this means that the following disclosure content is to be understood: a) A or B or C or b) (A and B) or c) (A and C) or d) (B and C) or e) (A and B and C).

[0107] The present invention is illustrated below using exemplary figures. The inventive concept is not limited to these embodiments.

[0108] Figure 1 schematically shows a plant (100) according to the invention for producing synthetic fuels. The plant (100) shown comprises at least one energy source (1), in particular a fluctuating energy source, preferably a renewable energy source, the energy of which is used by the at least one hydrogen source (3), in particular an electrolyzer, to provide molecular hydrogen. The hydrogen is then stored in a hydrogen buffer storage (4) with a sensor system for determining the fill level. The process control system (11) of the plant (100) records information about the amount of hydrogen provided by the hydrogen source (3), about the fill level of the hydrogen buffer storage (4), and about the fill levels of the storages for hydrogenated hydrogen carriers (5.2) and dehydrogenated hydrogen carriers (5.3) and regulates the mass flow of hydrogen into the synthesis gas production unit (7) and into the hydrogen release and storage reactor system (5). If the fill level of the hydrogen buffer storage (4) reaches a predefined upper limit, at least a portion of the hydrogen provided by the hydrogen source (3) is fed from the hydrogen buffer storage (4) into the hydrogen release and storage reactor system (5). In the hydrogen carrier hydrogenation and dehydrogenation reactor (5.1), dehydrogenated hydrogen carriers from the dehydrogenated hydrogen carrier storage (5.3) are hydrogenated. The resulting hydrogenated hydrogen carriers are subsequently stored in the hydrogenated hydrogen carrier storage (5.2).If the fill level of the hydrogen buffer storage (4) reaches a certain lower limit and / or the amount of hydrogen provided by the hydrogen source (3) is low, additional hydrogen can be provided in the reactor for the hydrogenation and dehydrogenation of hydrogen carriers (5.1) by dehydrogenating hydrogenated hydrogen carriers from the storage for hydrogenated hydrogen carriers (5.2). The resulting dehydrogenated hydrogen carriers are then transferred to the storage for dehydrogenated hydrogen carriers (5.3). To obtain synthesis gas, the hydrogen stream and a carbon dioxide stream obtained from the carbon dioxide source (6) are fed into a unit for producing synthesis gas (7). The unit comprises at least one reactor for the backward water gas shift reaction in the chemical looping process (RWGS-CL), in which the oxidation and reduction take place temporally or spatially separated from one another.Thus, in the synthesis gas production unit (7), a CO / CO2 stream and a separate H2 / H2O stream are preferably produced. The streams are then mixed together in a suitable ratio, and if necessary, additional hydrogen is added from the hydrogen buffer storage (4) to produce a synthesis gas stream with a desired CO / H2 ratio for the subsequent synthesis of synthetic products.

[0109] Hydrocarbon compounds are obtained in the Fischer-Tropsch reactor (10) of the plant. The reaction heat generated during the exothermic synthesis of synthetic hydrocarbon compounds from synthesis gas in the Fischer-Tropsch reactor (10) can be utilized, among other things, for the dehydrogenation of hydrogenated hydrogen carriers by thermal coupling between the Fischer-Tropsch reactor (10) and the reactor for the hydrogenation and dehydrogenation of hydrogen carriers (5.1), preferably via a heat conduction system.

[0110] Figure 2 schematically shows a preferred embodiment of the plant (100) according to the invention for producing synthetic fuels from Figure 1. In this embodiment, the plant additionally comprises an energy storage device (2) arranged between the energy source (1) and the at least one hydrogen source (3), in particular the at least one electrolyzer. Furthermore, the plant according to Figure 2 has a device for condensing water from the synthesis gas stream (8), in which process water is separated from the H2 / H2O stream by condensation in order to obtain an H2 stream. In a specific device for adjusting the synthesis gas stream (9), the CO / CO2 stream from the unit for producing synthesis gas (7) and the H2 stream are mixed with one another.According to the invention, it can be provided that additional hydrogen from the hydrogen buffer storage (4) as well as gaseous reaction products, in particular methane (CH4), and unreacted CO, CO2 and H2 from the Fischer-Tropsch reactor (10) are also introduced into the device for adjusting the synthesis gas flow (9) in order to adjust the desired synthesis gas composition and increase the reaction yield.

[0111] List of reference symbols:

[0112] 1 energy source

[0113] 2 energy storage units

[0114] 3 Hydrogen source

[0115] 4 hydrogen buffer storage

[0116] 5 Reactor system for the release and storage of hydrogen

[0117] 5.1 Reactor for hydrogenation and dehydrogenation of hydrogen carriers

[0118] 5.2 Storage for hydrogenated hydrogen carriers

[0119] 5.3 Storage for dehydrated hydrogen carriers

[0120] 6 Carbon dioxide source

[0121] 7 Synthesis gas production unit

[0122] 8 Device for condensing water from the synthesis gas stream Device for adjusting the synthesis gas stream Fi scher-T rop sch reactor Process control system Plant for the production of synthetic fuels

Claims

CLAIMS 1. Plant (100) for producing synthetic fuels, comprising: at least one energy source (1), at least one hydrogen source (3), preferably at least one electrolyzer, at least one carbon dioxide source (6), at least one hydrogen buffer storage (4) with a sensor system for determining the fill level, at least one reactor system for releasing and storing hydrogen (5), comprising i) at least one reactor for hydrogenating and dehydrogenating hydrogen carriers (5.1), ii) at least one storage for hydrogenated hydrogen carriers (5.2) with a sensor system for determining the fill level, and iii) at least one storage for dehydrogenated hydrogen carriers (5.3) with a sensor system for determining the fill level, at least one unit for producing synthesis gas (7), comprising at least one reactor for the backward water gas shift reaction in the chemical looping process (RWGS-CL), at least one Fischer-Tropsch reactor (10), and at least one process control system (11), wherein the at least one reactor system for the release and storage of hydrogen. (5) and the at least one unit for producing synthesis gas (7) are connected to the hydrogen buffer storage (4), wherein a thermal coupling exists between the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers (5.1) and the at least one Fischer-Tropsch reactor (10), and wherein the process control system (11) is designed and configured such that the amount of hydrogen provided by the hydrogen source (3) and the fill levels of the at least one hydrogen buffer storage (4), the at least one storage for hydrogenated hydrogen carriers (5.2) and the at least one storage for dehydrogenated hydrogen carriers (5.3) are continuously recorded and that the mass flow of hydrogen into the at least one unit for producing synthesis gas (7) and into the at least one reactor system for storing hydrogen (5) can be regulated as a function of the amount of hydrogen provided by the hydrogen source (3) and of the fill levels of the at least one hydrogen buffer storage (4), the at least one storage for hydrogenated hydrogen carriers (5.2) and the at least one storage for dehydrogenated hydrogen carriers (5.3).

2. Plant according to claim 1, wherein the energy source (1) is a fluctuating energy source, in particular a renewable energy source, preferably an energy source using wind and / or solar energy.

3. Plant according to claim 1 or 2, wherein the hydrogen source (3) is selected from the group consisting of alkaline electrolyzers, proton exchange membrane electrolyzers (PEM), anion exchange membrane electrolyzers (AEM), high-temperature electrolyzers (HTEL), in particular solid oxide electrolyzers (SOEC), chloralki electrolyzers and E-TAC electrolyzers.

4. System according to one of the preceding claims, wherein the at least one energy source (1) is connected to at least one energy storage device (2), in particular to at least one accumulator.

5. Plant according to one of the preceding claims, wherein the carbon dioxide source (6) is selected from anthropospheric, atmospheric, lithospheric and hydrospheric carbon dioxide sources.

6. Plant according to one of the preceding claims, wherein the at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers (5.1) comprises a catalyst which catalyses both the hydrogenation and the dehydrogenation of hydrogen carriers.

7. Plant according to one of the preceding claims, wherein the hydrogen carrier is a liquid organic hydrogen carrier (LOHC).

8. Plant according to one of the preceding claims, wherein the at least one unit for producing synthesis gas (7) comprises at least one oxygen storage material (OSM).

9. Plant according to one of the preceding claims, wherein the at least one unit for producing synthesis gas (7) comprises an RWGS-CL reactor in which the reduction and oxidation take place at different times from one another.

10. Plant according to one of claims 1 to 8, wherein the at least one unit for producing synthesis gas (7) comprises at least two RWGS-CL reactors in which reduction and oxidation take place spatially separated from one another.

11. Plant according to one of the preceding claims, wherein the at least one unit for producing synthesis gas (7) produces a hydrogen / water (H2 / H2O) stream and a separate carbon monoxide / carbon dioxide (CO / CO2) stream.

12. A process for producing synthetic fuels, comprising the steps of: a) providing electrical energy, water, and carbon dioxide, b) electrolyzing the water using the electrical energy provided in step a) to obtain hydrogen, c) storing the hydrogen produced in step b) in a hydrogen buffer storage (4), d) reacting hydrogen from the hydrogen buffer storage (4) with the carbon dioxide provided in step a) in a unit for producing synthesis gas (7) by means of a reverse water-gas shift reaction in the chemical looping process (RWGS-CL) to obtain a hydrogen / water (H2 / H2O) stream and a carbon monoxide / carbon dioxide (CO / CO2) stream, e) separating water from the H2 / H2O stream to obtain an H2 stream, f) producing synthesis gas by combining the CO / CCh stream from step d) and the H2 stream from step e),g) converting the synthesis gas obtained in step f) in a Fischer-Tropsch process to obtain synthetic hydrocarbon compounds, wherein the hydrogen buffer storage (4) is provided with a reactor system for releasing and storing hydrogen (5), comprising i) at least one reactor for the hydrogenation and dehydrogenation of hydrogen carriers (5.1), ii) at least one storage for hydrogenated hydrogen carriers (5.2), iii) at least one storage for dehydrogenated hydrogen carriers (5.3), wherein the fill levels of the hydrogen buffer storage (4), the at least one storage for hydrogenated hydrogen carriers (5.2), the at least one storage for dehydrogenated hydrogen carriers (5.3), and the amount of hydrogen produced in step b) are continuously recorded by sensors, wherein the hydrogen produced in step b) is supplied to the reactor by continuous process control as a function of the fill levels of the hydrogen buffer storage (4), the at least one storage for hydrogenated hydrogen carriers (5.2), the at least one storage for dehydrogenated hydrogen carriers (5.3), and from the amount of hydrogen produced in step b) is fed to the unit for producing synthesis gas (7) and / or is stored in the reactor system for releasing and storing hydrogen (5), in the form of hydrogenated hydrogen carriers, or additional hydrogen is released from hydrogenated hydrogen carriers to be fed to the unit for producing synthesis gas (7), and wherein in the Fischer-Tropsch process in step e) heat released in the at least one reactor for hydrogenation and dehydrogenation of hydrogen carriers (5.1) is used for the storage and release of hydrogen from hydrogen carriers.

13. The method of claim 12, wherein the hydrogen carrier is a liquid organic hydrogen carrier (LOHC).

14. The process according to claim 12 or 13, wherein the synthesis gas produced in step f) has an H2 / CO ratio of 1.4 to 2.2, preferably 1.6 to 2.

0.

15. The process according to any one of claims 12 to 14, wherein the synthetic hydrocarbon compounds obtained in step g) are subjected in a further step h) to at least one processing method selected from the group consisting of hydrocracking, hydrotreating, isomerization, distillation and purification.

16. Fuel, in particular aviation fuel, comprising synthetic Hydrocarbon compounds prepared by a process according to any one of claims 12 to 15.

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