Method and system for producing synthetic fuels

Abstract

The invention relates to a method for producing synthetic fuels (18), comprising the following steps: carrying out (S10) a CO2-based high-temperature Fischer-Tropsch reaction at a reaction temperature in the range from 250 to 650°C using a reactant stream (12) comprising H2 and CO2 in order to produce a first hydrocarbon stream (14); separating (S20) the first hydrocarbon stream (14) in order to produce a second hydrocarbon stream (16a); hydrogenating (S30) the second hydrocarbon stream (16); fractionating (S40) the hydrogenated second hydrocarbon stream (16b) in order to produce a synthetic fuel (18), in particular kerosene and / or diesel. The invention also relates to a corresponding system (1).

Description

[0001] 2024PF00568

[0002] 1

[0003] Description

[0004] Process and plant for the production of synthetic fuels

[0005] Field of invention

[0006] The present invention relates to a method and a plant for the production of synthetic fuels, in particular sustainable aviation fuel.

[0007] Background of the invention

[0008] Sustainable aviation fuel, or regeneratively produced kerosene, also called Sustainable Aviation Fuel (SAF), is a fuel that is produced using the highest possible use of renewable energies or avoiding climate-damaging emissions as much as possible.

[0009] Known manufacturing processes include, for example, the so-called methanol route or the so-called Fischer-Tropsch route, hereinafter referred to as the "FT route" or "FT synthesis". The FT route is distinguished from the methanol route, for example, by a higher degree of maturity.

[0010] In a non-renewable variant of the FT route, a CO-based synthesis gas, essentially a mixture of CO and H2, is produced by reforming natural gas or coal gasification. FT synthesis initially yields a synthetic oil, also called syncrude, from this synthesis gas, which can then be converted into fuels as target products through refining processes. A disadvantage of this variant is that the carbon is not produced from renewable sources.

[0011] In a conventional regenerative variant of the FT route, so-called regenerative CO2 is first obtained, for example via direct air capture or from biomass. The 2024PF00568

[0012] 2

[0013] CO2 is converted to a CO-rich synthesis gas using a reverse water-gas shift (RWGS) reactor, which is then converted to Syncrude in a conventional FT reactor. A disadvantage of this variant is that the endothermic RWGS reaction in the reactor requires a high energy input at a very high temperature, for example, above 800 °C.

[0014] Summary of the invention

[0015] Starting from the known state of the art, it is an object of the present invention to provide a method for the production of synthetic fuels and a corresponding plant.

[0016] The problem is solved by a method with the features of claim 1. Advantageous further developments result from the dependent claims, the description and the figures.

[0017] Accordingly, a process for the production of synthetic fuels is proposed, comprising the following steps:

[0018] - Performing a CO2-based high-temperature Fischer-Tropsch reaction at a reaction temperature in the range of 250 to 650 °C using a reactant stream comprising H2 and CO2 to generate an initial hydrocarbon stream;

[0019] - Separating the first hydrocarbon stream to generate a second hydrocarbon stream;

[0020] - Hydrogenation of the second hydrocarbon stream;

[0021] - Fractionation of the hydrogenated second hydrocarbon stream to produce a synthetic fuel.

[0022] The fuel to be produced can be, in particular, kerosene, gasoline, and / or diesel. The second hydrocarbon stream can also be referred to as the so-called syncrude.

[0023] Because the Fischer-Tropsch reaction, hereinafter FT reaction, takes place at a reaction temperature in the high-temperature range, i.e., at reaction temperatures in the range of 250 to 2024PF00568

[0024] 3

[0025] At 650 °C, the FT reaction can be CO2-based. This allows the use of a CO2-based or CO2-rich synthesis gas in the reactant stream, which essentially consists of H2 and CO2. In this way, for example, a reverse water-gas shift reaction (RWGS reaction) upstream of the FT reaction, which is conventionally performed endothermically in an RWGS reactor upstream of the FT reactor, can be omitted. Thus, the second hydrocarbon stream, or regenerative syncrude, can be produced with significantly less energy input than in the prior art.

[0026] The reactant stream can be generated using a sustainable CO2 supply process, for example, by utilizing biomass or by a direct air capture process. In this context, the reactant stream is generally understood to be a substance or mixture stream that is provided by a process upstream of the FT reaction and independent of the process disclosed herein. In particular, substances that are fed into or added to the reactant stream from a reaction downstream of the FT reaction during the disclosed process or a corresponding plant would not be considered part of the reactant stream itself. For example, if a certain quantity of CO is fed into the reactant stream during a recycling process from the disclosed process, this specific quantity is not to be attributed to the mixture composition of the reactant stream.

[0027] Furthermore, the reactant stream can consist essentially of H2 and CO2. For example, the reactant stream can consist of at least 75% by volume of H2 and CO2. Alternatively, the reactant stream can consist of at least 80% or 85% by volume of H2 and CO2. For example, the reactant stream can be composed entirely of H2 and CO2. Furthermore, the reactant stream can contain at most 25% by volume of CO. Alternatively, the reactant stream can contain at most 20% or 15% by volume of CO. Thanks to the above exemplary constraints, it can be achieved that the energy input for providing CO as an input material for the present process can be kept at a low level or can be zero. As described above, in the context of this disclosure, an optional recycling of CO is not considered in the specification of the composition of the reactant stream itself.

[0028] Furthermore, the 002 : CO volume ratio in the reactant stream can be in the range of 1 : 0 to 1 : 1. In particular, the 002 : 00 ratio can be l : x, where xj can take any value between 0 and 1. Thus, a tolerance for a certain amount of 00 in the original reactant stream can be granted. In this way, synthesis gas-producing reactions, which may contain 00 as a byproduct, can be upstream of the FT reaction.

[0029] Furthermore, the Fischer-Tropsch reaction can be iron-catalyzed. For example, a corresponding FT reactor can incorporate an iron catalyst. It has been found that at the reported reaction temperature in the range of 250 to 650 °C, the iron-catalyzed FT reaction can catalyze a partial RWGS reaction, so that within a corresponding FT reactor, or during the iron-catalyzed FT reaction, a partial RWGS reaction of the synthesis gas also occurs. In this way, the FT reaction can proceed in a CO₂-based manner, i.e., converting a reactant stream consisting essentially of H₂ and CO₂, or a CO₂-rich reactant stream, to syncrude.

[0030] Furthermore, the reactant stream cannot be provided by means of a reverse water-gas shift reaction. This does not preclude a reverse water-gas shift reaction from occurring during the FT reaction in a corresponding FT reactor, as described above. In this context, "upstream" means that an RWGS reaction would take place in an RWGS reactor separate from the FT reactor, which, according to this disclosed configuration, is exactly 2024PF00568.

[0031] 5 is excluded. Because the reactant current cannot be provided by means of a reverse water-gas shift reaction, a corresponding RWGS reactor upstream of the FT reaction can be saved.

[0032] Furthermore, the above step "separating the first hydrocarbon stream" can be carried out using a 3-phase separator to generate a gas phase stream and a water phase stream. The process can include the following steps:

[0033] - Absorption of oxygenates from the gas phase stream using at least a partial stream of the water phase stream as an absorbent to generate a water-oxygenate stream;

[0034] - Distilling the water-oxygenate stream to produce an oxygenate exhaust stream.

[0035] It was recognized that at the apparently high FT reaction temperature, compared to a low-temperature FT reaction, more oxygenates are formed and can be present in the first hydrocarbon stream. In this context, oxygenates are understood to be organic hydrocarbon compounds containing oxygen atoms, such as alcohols, aldehydes, or ketones. Conventionally, in this technical field, unwanted oxygenates are separated using a fixed-bed reactor filled with an adsorbent.

[0036] Surprisingly, it was found in the course of the present invention that the overall effort required to separate the oxygenates by absorbing the oxygenates from the gas phase stream as described above, using at least a partial stream of the water phase stream as an absorbent, is less than when using the conventional fixed-bed reactor.

[0037] Furthermore, the fact that the water-oxygenate stream can be distilled to produce an oxygenate exhaust stream, can- 2024PF00568

[0038] 6. The oxygenates separated from the gas phase stream can be easily reused in the form of an exhaust gas stream. This allows the overall balance, for example with regard to energy input or the yield of substances used, to be further improved compared to the conventional adsorption process with a fixed-bed reactor.

[0039] According to further training, the procedure can include the following steps:

[0040] - Oligomerization of the gas phase stream using an oligomerization reactor to convert short-chain olefins into longer-chain olefins in the range of C8 to C20;

[0041] - Cooling of the oligomerized gas phase stream;

[0042] - Separation of the cooled gas phase stream into a separator exhaust gas stream and a liquid separator hydrocarbon stream using a 2-phase separator;

[0043] - Merging the separator hydrocarbon stream with the second hydrocarbon stream before the step "Hydrogenating the second hydrocarbon stream".

[0044] In this context, short-chain olefins are understood to be those olefins with a carbon chain length of less than C8. In particular, the short-chain olefins of the gas phase stream may predominantly or essentially have a carbon chain length in the range of C3 to C6.

[0045] The oligomerized gas phase stream can contain, in addition to the longer-chain olefins in the range of C8 to C20, particularly lighter components such as methane, ethane, unreacted ethylene, CO2 and light naphtha as byproducts.

[0046] By using the 2-phase separator, the liquid separator hydrocarbon stream can be separated from the oligomerized and cooled gas phase stream. This allows the liquid separator hydrocarbon stream to be easily fed into the hydrogenation process, enabling its conversion into a fuel within the process cycle. Thus, with minimal equipment, the yield of the input materials can be increased (2024PF00568).

[0047] Furthermore, because the gaseous separator exhaust gas stream can be separated and recycled from the oligomerized and cooled gas phase stream using the 2-phase separator, at least a predominant part of the by-products of the oligomerized gas phase stream can be further utilized in the process cycle in the form of the separator exhaust gas stream.

[0048] Furthermore, the following step can be performed before the above step of "oligomerizing the gas phase stream": separating CO2 from the gas phase stream, in particular by means of a separation device operated with K2CO3 solution. This allows an operator of the process or a corresponding plant to reduce the CO2 concentration in the gas phase stream as needed, especially to improve the operation of the oligomerization reactor.

[0049] Furthermore, the procedure may include the following steps:

[0050] - Utilizing at least one exhaust gas stream to generate a recirculation stream containing CO2 and H2O;

[0051] - Feeding the return current to the reactant current or directly to the CO2-based high-temperature Fischer-Tropsch reaction.

[0052] In particular, at least one exhaust gas stream can be the separator exhaust gas stream and / or the oxygenate exhaust gas stream as described above. Furthermore, the step "fractionating the hydrogenated second hydrocarbon stream" can provide a fractionation exhaust gas stream as a byproduct, which can also be at least one exhaust gas stream.

[0053] By converting at least one exhaust gas stream into the CO2- and H2-rich recirculation stream, which can then be fed either to the reactant stream or directly to the FT reaction, the exhaust gases can be treated in accordance with 2024PF00568

[0054] 8 of a cyclic process via the FT reaction are ultimately converted into a target product, in particular fuel.

[0055] Furthermore, the CO2 separated in the step "separation of CO2 from the gas phase stream" can be fed back into the return stream as a CO2 stream. Alternatively, the CO2 stream can either be fed back into the reactant stream or directly into the FT reaction.

[0056] According to further training, the procedure can include:

[0057] - Autothermal reforming of at least one exhaust gas stream using an upstream pre-reformer, wherein the return stream contains H2, CO, CO2 and H2O. In particular, the H2O contained in the return stream can be removed by cooling and condensation before the step of "supplying the return stream".

[0058] - Partial oxidation of at least one exhaust gas stream using a substoichiometric amount of O₂, wherein the recirculation stream contains H₂, CO, CO₂ and H₂O. In particular, the H₂O contained in the recirculation stream can be removed by cooling and condensation before the step of "introducing the recirculation stream"; and / or

[0059] - Oxy-boiling of at least one exhaust gas stream using a superstoichiometric amount of O2 to effect full oxidation of at least one exhaust gas stream to CO2 and H2O, wherein the H2O contained in the recirculation stream is removed by cooling and condensation before the step "supplying the recirculation stream".

[0060] By means of autothermal reforming, partial oxidation or oxy-boiling of at least one exhaust gas stream, a simple and robust utilization of at least one exhaust gas stream or the separator exhaust gas stream, the oxygenate exhaust gas stream and / or the fractionation exhaust gas stream can be achieved, so that the fuel yield with respect to the substances used can be significantly increased.

[0061] Furthermore, the step “Hydrogenating the second hydrocarbon stream” can be carried out at a temperature in the range of 150 °C up to 2024PF00568

[0062] 9

[0063] Hydrotreating is carried out at 350 °C, particularly 180 °C to 300 °C, with hydrogen and at a pressure in the range of 10 to 100 bar to provide mild hydrotreating. This saturates the olefin components of the second hydrocarbon stream with hydrogen, forming corresponding paraffins. Thanks to mild hydrotreating at the temperatures and pressures described above, hydrogenation can be carried out with significantly less energy input than in conventional processes or plants. Furthermore, mild hydrotreating does not produce any additional unexpected or undesirable byproducts, or at least the risk of such formation is significantly reduced. In particular, only existing compounds in the second hydrocarbon stream are saturated.This means that the cracking required in conventional processes to split longer chains can be avoided, thus also preventing the formation of methane as a byproduct.

[0064] The problem stated above is further solved by a system with the features of claim 11. Accordingly, a system is proposed which is configured to carry out the method described above. The definitions, technical effects, and advantages explained above for the proposed method apply equally to the proposed system, and vice versa.

[0065] The problem stated above is further solved by a system with the features of claim 12. Advantageous further developments are described in the dependent claims, the description, and the figures.

[0066] Accordingly, a plant for the production of synthetic fuels is proposed, comprising:

[0067] - a Fischer-Tropsch reactor, designed to produce a first hydrocarbon stream from a reactant stream comprising H2 and CO2, 2024PF00568

[0068] 10

[0069] - a 3-phase separator, designed to generate a second hydrocarbon stream by separating the first hydrocarbon stream,

[0070] - a hydrogenation unit, set up for hydrogenating the second hydrocarbon stream,

[0071] - a fractionation unit, set up to fractionate the hydrogenated second hydrocarbon stream to produce a synthetic fuel.

[0072] The definitions, technical effects and advantages explained above for the proposed procedure apply equally to the plant proposed here, and vice versa.

[0073] The fuel to be produced can be, in particular, kerosene, gasoline and / or diesel.

[0074] Furthermore, the plant cannot include a reverse water-gas shift reactor unit for providing CO-based synthesis gas. In particular, a separate reverse water-gas shift reactor unit cannot be installed upstream of the Fischer-Tropsch reactor.

[0075] In particular, the FT reaction taking place in the FT reactor can be iron-catalyzed. For example, the FT reactor can have an iron catalyst. Specifically, the FT reactor can be configured for operation at a reaction temperature in the range of 250 to 650 °C. In this way, the FT reactor—as described above in the context of the disclosed process—can catalyze an RWGS partial reaction, so that within the FT reactor, or during the iron-catalyzed FT reaction, an RWGS partial reaction of the synthesis gas or the reactant stream also takes place. In this way, the FT reaction can be CO2-based, i.e., converting a reactant stream consisting essentially of H2 and CO2, or a CO2-rich reactant stream, to Syncrude. 2024PF00568

[0076] 11

[0077] Furthermore, the 3-phase separator can be configured to generate a gas phase stream and a water phase stream. The system can also include an absorption unit configured to generate a water-oxygenate stream using at least a portion of the water phase stream as an absorbent. More precisely, the gas phase stream and the portion of the water phase stream can be fed into the absorption unit, which then provides the water-oxygenate stream at the output. In this way, as explained in the context of the disclosed process, the overall effort required to separate the oxygenates can be significantly reduced compared to conventional systems.

[0078] Brief description of the characters

[0079] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. These show schematically:

[0080] Figure 1 shows a plant and a process for the production of synthetic fuels; and

[0081] Figure 2 shows the process for producing synthetic fuels.

[0082] Detailed description of application examples

[0083] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are designated with identical reference symbols, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.

[0084] Figure 1 shows a plant 1 for the production of synthetic fuels. Furthermore, the steps of the proposed process for the production of synthetic fuels are shown. 2024PF00568

[0085] 12

[0086] Substances in Figure 1 are additionally shown at the corresponding process engineering elements or units with reference symbols. Central steps of the process or units of plant 1 are shown vertically in the center of Figure 1, horizontally from left to right, and with thicker connecting arrows. Selected process steps for the recycling of substances in a small circuit are shown with long dashed lines. Further process steps for the recycling, in particular of exhaust gases, in a larger circuit are shown with short dashed lines.

[0087] In step S5, a reactant stream 12 is initially provided, comprising H2 and CO2. The reactant stream 12 is particularly CO2-rich and can consist essentially of H2 and CO2. For example, the reactant stream can consist of at least 75% by volume of H2 and CO2. The CO2 in the reactant stream can, in particular, be renewable CO2, obtained, for example, via direct air capture or from biomass. The hydrogen H2 in the reactant stream can be electrolysis hydrogen produced using electricity from renewable sources.

[0088] The reactant stream may optionally contain further gases or components in the form of by-products of the upstream processes, in particular CO .

[0089] Following step S5, the reactant stream 12 is fed via a reactant stream line 12a to a Fischer-Tropsch reactor 10, where step S10 takes place, namely the execution of a CO2-based high-temperature Fischer-Tropsch reaction at a reaction temperature in the range of 250 to 650 °C using the reactant stream 12. The FT reaction S10 provides an initial hydrocarbon stream 14, which is subsequently fed to a 3-phase separator 20. The FT reactor 10 has an iron catalyst. In this way, an RWGS reaction is co-catalyzed within the FT reactor 10, so that the plant 1 or the proposed process does not require a pre-treatment step, i.e., from 2024PF00568

[0090] 13. A separate RWGS reactor is not required for the FT reactor 10 to provide CO. Rather, thanks to the proposed arrangement and reaction conditions, CO is generated within the FT reactor 10. Thus, the reactant stream 12 can contain, for example, no CO or only marginal amounts. Alternatively, the reactant stream 12 can contain, for example, up to 40, up to 30, or up to 25 volume percent CO without this being detrimental to the proposed process. For example, a gasifier product mixture comprising H2, CO, and CO2 can form the reactant stream 12 or be fed into the reactant stream 12. Thus, a CO-containing return stream 82, which will be discussed later, can also be fed into the FT reactor 10 or the reactant stream 12.

[0091] Referring again to the central elements of Figure 1, the first hydrocarbon stream 14 is separated S20 by means of the 3-phase separator 20 after the FT reaction S10 to generate a second hydrocarbon stream 16a. The second hydrocarbon stream 16a can also be referred to as the organic liquid phase and consists mainly of hydrocarbons with a chain length of C9-C22 and contains olefins, iso-paraffins and n-paraffins.

[0092] The second hydrocarbon stream 16a is then fed to a hydrogenation unit 30, where step S30 takes place, namely hydrogenation S30 of the second hydrocarbon stream 16a. Hydrogenation S30 can also be described as mild hydrogen hydrotreating and can be carried out at temperatures between 180 and 300 °C and pressures between 10 and 100 bar. In this process, the liquid hydrocarbons of the second hydrocarbon stream 16a are mainly converted into fuels 18 by saturating olefin components with hydrogen to form the corresponding paraffins.

[0093] The hydrogenated second hydrocarbon stream 16b is then fed to a fractionation unit 40, where a step S40 is carried out, namely fractionation S40 of the hydrogenated 2024PF00568

[0094] 14. Second hydrocarbon from stream 16b to produce a synthetic fuel 18. The fuel 18 can be kerosene, a diesel fraction, or naphtha. Besides the fuels 18 as target products, the only non-fuel by-product discharged from fractionation unit 40 is wax. Thus, all hydrocarbons introduced into plant 1 or into the proposed process are converted either into a fuel 18 or into wax. This can be achieved in particular by means of the recycling loops described below.

[0095] In addition to the second hydrocarbon stream 16, a gas phase stream 22 and a water phase stream 24 are also generated by means of the 3-phase separator 20. The water phase stream 24 is fed to a distillation column 52 via a line 24b. A partial stream 25 of the water phase stream 24 is fed to an absorption unit 50, which is also supplied with the gas phase stream 22 from the 3-phase separator 20. The gas phase stream 22 can also be referred to as the gas phase and mainly contains components with a chain length of C1-C8, such as methane, CO2, and short-chain olefins, paraffins, and oxygenates.

[0096] In step S50, oxygenates are absorbed from the gas phase stream 22 in the absorption unit 50 using at least the partial stream 25 of the water phase stream 24 as an absorbent to generate a water-oxygenate stream 26. For this purpose, the partial stream 25 of the water phase stream 24 can be cooled beforehand, for example to temperatures below 40 °C.

[0097] The generated water-oxygenate stream 26 is fed to the distillation column 52, specifically via line 24b, which carries the other part of the water phase stream 24 to the distillation column 52. In distillation column 52, the water-oxygenate stream 26 is distilled in step S52 to generate an oxygenate exhaust stream 28. The 2024PF00568

[0098] The remaining 15 liters of water can be removed from the process.

[0099] The oxygenate exhaust gas stream 28 can also be described as one of several exhaust gas streams that are fed individually or together to an exhaust gas utilization unit 80 via an exhaust gas supply line 80a. The exhaust gas utilization unit 80 utilizes the exhaust gas streams supplied via the exhaust gas supply line 80a to generate a recirculation stream 82 containing CO2 and H2O. The recirculation stream 82 is fed to the reactant stream line 12a via a recirculation line 82a. Alternatively, the recirculation stream 82 can also be fed directly to the FT reactor via the recirculation line 82a. The exhaust gas utilization unit 80 will be discussed again later.

[0100] With regard to the 3-phase separator 20 and the absorption unit 50, the gas phase stream 22 is directed from the absorption unit 50 to a CO2 separation device 55, which can be operated with, for example, a K2CO3 solution. After separating CO2 from the gas phase stream 22, the separated CO2 can be fed back into the return line 82a. In this way, the regeneratively obtained CO2 can be reused in the process, while at the same time the units downstream of the absorption unit 50 can be relieved of the separated CO2.

[0101] The separation device 55 is followed by an oligomerization reactor 60, by which the gas phase stream 22b, 22c is oligomerized in a single step S 60 to convert short-chain olefins into longer-chain olefins in the range of C8 to C20. The gas phase stream 22b, 22c may contain ethylene upstream of the oligomerization reactor 60, which can be oligomerized along with the other olefins. For this purpose, a dimerization reactor for the dimerization of the ethylene can be placed upstream of the oligomerization reactor 60. 2024PF00568

[0102] 16

[0103] Subsequently, in step S 65, the oligomerized gas phase stream 22d is cooled in a cooling unit (without reference symbol). The oligomerized and cooled gas phase stream 22d is then fed to a 2-phase separator 70, so that in step S70 it is separated into a separator exhaust gas stream 23a and a liquid separator hydrocarbon stream 23b.

[0104] Subsequently, in step S72, the liquid separator hydrocarbon stream 23b is combined with the second hydrocarbon stream 16a upstream of the hydrogenation unit 30. In this way, the substances of the separator hydrocarbon stream 23b can be hydrogenated in the hydrogenation unit 30 according to step S30, so that ultimately, thanks to the proposed arrangement, a high proportion of the gas phase stream 22 separated by the 3-phase separator can be converted back into fuel 18 or the only byproduct, wax.

[0105] Furthermore, in step S74, the separator exhaust gas stream 23a generated by means of the 2-phase separator 70 is fed as one of the exhaust gas streams to the exhaust gas supply line 80a or alternatively directly to the exhaust gas utilization unit 80.

[0106] With reference again to the centrally depicted steps or units, the fractionation unit 40 delivers a fractionation exhaust gas stream 40a, which in a step S76 is fed as one of the exhaust gas streams to the exhaust gas supply line 80a or alternatively directly to the exhaust gas utilization unit 80.

[0107] As shown in Figure 1, the exhaust gas recovery unit 80 02 can be supplied with, and optionally, depending on the configuration, with steam. The exhaust gas recovery unit 80 can, for example, be designed as an ATR reactor 80 with an upstream pre-reformer. 2024PF00568

[0108] 17

[0109] Furthermore, the exhaust gas utilization unit 80 can be designed as a POX reactor 80 for partial oxidation, whereby a substoichiometric amount of O2 is supplied.

[0110] Furthermore, the exhaust gas utilization unit 80 can be designed as an oxy-boiler 80 for full oxidation, whereby a superstoichiometric quantity of O2 is supplied.

[0111] In the case of the ATR reactor 80 and the POX reactor 80, the recirculation stream 82 contains H2, CO, O2, and H2O, or consists essentially of these substances. Optionally, in these cases, the H2O contained in the recirculation stream 82 can be removed before the S82 feed step by means of cooling and condensation.

[0112] In the case of the Oxy-Boiler 80, the return stream 82 002 contains, or essentially consists of, H2O. In this case, it is recommended to remove the H2O contained in the return stream 82 before the S82 feed step by means of cooling and condensation.

[0113] Figure 2 shows an embodiment of the process for producing synthetic fuels. The process steps S5, S10, S20, S30, S40, S50, S52, S55, S60, S70, S72, S74, S76, S80 and S82 shown in Figure 2 have been explained in the description of Figure 1. A repetition is omitted here.

[0114] Where applicable, all individual features shown in the exemplary embodiments can be combined and / or exchanged without leaving the scope of the invention.

Claims

2024PF00568 18 Patent claims 1. Method for producing synthetic fuels (18) , comprising the following steps: - Performing (S10) a CO2-based high-temperature Fischer-Tropsch reaction at a reaction temperature in the range of 250 to 650°C using a reactant stream (12) comprising H2 and CO2 to generate a first hydrocarbon stream (14); - Separating (S20) the first hydrocarbon stream (14) to generate a second hydrocarbon stream (16a); - Hydrogenation (S30) of the second hydrocarbon stream (16) ; - Fractionation (S40) of the hydrogenated second hydrocarbon stream (16b) to produce a synthetic fuel (18), in particular kerosene and / or diesel.

2. Method according to claim 1, wherein the reactant stream (12) consists substantially of H2 and CO2, in particular wherein the reactant stream (12) consists of at least 75 volume percent of H2 and CO2, optionally wherein the reactant stream (12) contains at most 25 volume percent CO.

3. Method according to claim 1 or 2, wherein the CO2:CO volume ratio in the reactant stream (12) is in the range of 1:0 to 1:

1.

4. Method according to one of the preceding claims, wherein the Fischer-Tropsch reaction (S10) is iron-catalyzed.

5. Method according to any of the preceding claims, wherein the reactant stream (12) is not provided by means of a reverse water-gas shift reaction.

6. A method according to any of the preceding claims, wherein the step of separating (S20) the first hydrocarbon stream (14) is carried out using a 3-phase separator (20) to generate a gas phase stream (22a) and a water phase stream (24a), and wherein the method comprises: 2024PF00568 19 - Absorption (S50) of oxygenates from the gas phase stream (22a) using at least a partial stream (25) of the water phase stream (24a) as an absorbent to generate a water-oxygenate stream (26); - optional: Distilling (S52) the water-oxygenate stream (26) to produce an oxygenate exhaust stream (28).

7. The method of claim 6, comprising the steps of: - Oligomerization (S60) of the gas phase stream (22b, 22c) using an oligomerization reactor (60) to convert short-chain olefins into longer-chain olefins in the range of C8 to C20; - Cooling (S65) of the oligomerized gas phase stream (22d) ; - Separation (S70) of the cooled gas phase stream (22d) by means of a 2-phase separator (70) into a separator exhaust gas stream (23a) and a liquid separator hydrocarbon stream (23b) ; - Combining (S72) the separator hydrocarbon stream (23b) with the second hydrocarbon stream (16a) prior to hydrogenating (S30) the second hydrocarbon stream (16a) ; - optional: Separation (S55) of CO2 from the gas phase stream (22b) prior to oligomerization (S60), in particular by means of a separation device (55) operated with K2CO3 solution .

8. A method according to any one of the preceding claims, comprising the steps of: - Utilizing (S80) at least one exhaust gas stream (23a, 28, 40a) to generate a recirculation stream (82) containing CO2 and H2O; - Feeding (S82) the return stream (82) to the reactant stream (12) or directly to the CO2-based high-temperature Fischer-Tropsch reaction (S10) .

9. The method of claim 8, wherein the utilization (S80) comprises the steps: - Autothermal reforming (S80) of at least one exhaust gas stream (23a, 28, 40a) using an upstream pre-reformer, wherein the return stream (82) is H2, CO, CO2 and 2024PF00568 20 H2O contains, in particular wherein the H2O contained in the return stream (82) is removed before the supply step (S82) by means of cooling and condensation; - Partial oxidation (S80) of at least one exhaust gas stream (23a, 28, 40a) using a substoichiometric Quantity of O2, wherein the return stream (82) contains H2, CO, CO2 and H2O, in particular wherein the H2O contained in the return stream (82) is removed by cooling and condensation before the supply step (S82); and / or - Oxy-boiling (S80) of the at least one exhaust gas stream (23a, 40a, 28) using a superstoichiometric amount of O2 to effect full oxidation of the at least one exhaust gas stream (23a, 28, 40a) to CO2 and H2O, wherein the H2O contained in the recirculation stream (82) is removed by cooling and condensation before the supply step (S82).

10. Method according to one of the preceding claims, wherein the hydrogenation (S30) of the second hydrocarbon stream (16) is carried out at a temperature in the range of 150°C to 350°C with hydrogen, in particular 180°C to 300°C, and at a pressure in the range of 10 to 100 bar to provide a mild hydrotreating.

11. Plant (1) for the production of synthetic fuels (18) which is equipped to carry out the process according to any one of the preceding claims 1 to 10.

12. Annex (1) for the production of synthetic fuels (18) , comprising: - a Fischer-Tropsch reactor (10) , designed to produce a first hydrocarbon stream (14) from a reactant stream (12) comprising H2 and CO2, - a 3-phase separator (20) , designed to generate a second hydrocarbon stream (16a) by separating the first hydrocarbon stream (14), - a hydrogenation unit (30) , set up for hydrogenating the second hydrocarbon stream (16a) , 2024PF00568 21 - a fractionation unit (40) , set up for fractionating the hydrogenated second hydrocarbon stream (16b) to produce a synthetic fuel (18) , in particular kerosene and / or diesel .

13. Plant (1) according to claim 12, wherein the plant (1) does not have a reverse water-gas shift reactor unit for providing a CO-based synthesis gas, in particular, wherein the Fischer-Tropsch reactor (10) is not preceded by a separate reverse water-gas shift reactor unit.

14. Plant (1) according to claim 12 or 13, wherein the 3-phase separator (20) is configured to generate a gas phase stream (22a) and a water phase stream (24a) and wherein the plant (1) has an absorption unit (50) configured to generate a water-oxygenate stream (26) using at least a partial stream (25) of the water phase stream (24a) as an absorbent.

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