A method for producing higher hydrocarbons with a low carbon footprint

Abstract

1. A method for producing higher hydrocarbons in a Fischer-Tropsch (FT) reactor by recycling an FT tail gas, the method comprising: feeding a dry synthesis gas to the FT reactor to form liquefied hydrocarbons and an FT tail gas, the dry synthesis gas being obtained by a reverse water-gas shift (RWGS) reaction of a CO stream with an H stream, and / or co-electrolysis of a CO stream with an HO stream, and plasma-based treatment of the FT tail gas.

Description

[Technical Field]

[0001] The present invention relates generally to the field of power-to-liquids or gas-to-liquids e-fuel plant applications, such as, for example, the production of higher hydrocarbons for the production of synthetic liquid fuels. [Background technology]

[0002] Reducing greenhouse gas emissions, especially CO2 emissions in the transportation sector, is one of the greatest challenges today. While alternatives to fuel consumption exist for the short-distance road transport sector, there are still sectors, such as long-distance road transport, shipping, and aviation, where liquid fuels are still needed on a large scale without viable alternatives, and therefore it is of great importance to develop alternative methods of fuel production with a lower carbon footprint.

[0003] The Fischer-Tropsch (FT) reaction is a well-known process for producing higher hydrocarbons from CO and H, also known as synthesis gas, in the presence of a catalyst. Synthesis gas can generally be obtained from the valorization of biomass, methane, or CO, for example, through steam reforming, partial oxidation, reverse water gas shift (RWGS), co-electrolysis, or autothermal reforming reactions. Among all synthesis gas production processes known in the art, some are non-neutral in terms of carbon footprint, while others require additional purification steps. Indeed, depending on the feedstock and reaction conditions, each synthesis gas synthesis route results in a different composition of synthesis gas, both in terms of the H / CO ratio and in terms of other components or by-products that may be formed during the reaction. However, FT products are sensitive to the composition of the synthesis gas. For example, when synthesis gas is produced by gasification of biomass, a purification step of the synthesis gas is generally required before using the synthesis gas in the FT reaction. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to produce high quality and valuable higher hydrocarbons with a reduced carbon footprint. Such higher hydrocarbons can be advantageously used as fuels in sectors such as the aviation and transport sectors. It is therefore an object of the present invention to propose an improved, efficient and sustainable FT process that is optimized to produce valuable products, preferably valuable liquid fuels, which FT process aims at an overall reduction of the carbon footprint. [Means for solving the problem]

[0005] To this end, the present invention provides a method for producing higher hydrocarbons by recycling and valorizing Fischer-Tropsch (FT) tail-gas in a FT reactor, comprising: feeding the dry synthesis gas into an FT reactor to form liquefied hydrocarbons and FT tail gas; Equipped with A method is proposed in which dry synthesis gas is obtained by RWGS reaction of a CO2 stream and an H2 stream and / or by co-electrolysis of a CO2 stream and an H2O stream, and by plasma-based treatment of the FT tail gas.

[0006] The FT process converts syngas (CO + H) into higher hydrocarbons and other (undesirable) components such as lower or gaseous hydrocarbons and water. When CO and H are the key resources for the production of liquid fuel in the FT reaction, the process is called a syngas-to-liquids process. When renewable electrical energy is used to generate syngas via this route, the process is also called an e-fuel production process. In an e-fuel plant, there can be several possibilities to utilize electrical energy for the production of syngas. For example, CO can be obtained by direct air capture using electrical energy, H can be produced by electrolysis, and syngas can be directly produced by co-electrolysis or reverse water-gas shift reaction using electrical energy.

[0007] An FT reactor generally operates in the presence of a catalyst for converting syngas. During the FT reaction, a mixture of liquefied hydrocarbons is formed and separated as FT synthetic crude oil. On the other hand, a mixture of lower hydrocarbons (<C6) and other gaseous components such as H2O, CO2, N2, which are inert to the FT reaction, and unreacted CO and H2 forms a gas phase and is often referred to as FT exhaust gas. The mixture of higher hydrocarbon fractions of the FT reaction is generally upgraded in an upgrading unit or product work-up unit including a final step of distillation to produce the desired liquid fuel.

[0008] According to the present invention, higher hydrocarbons refer to the fraction of hydrocarbons produced during the FT reaction having a number of carbon atoms greater than 6. In other words, higher hydrocarbons refer to hydrocarbons having a long chain in the range of C6 - C100, and higher hydrocarbons can be liquid under normal temperature and pressure conditions (NTP, 20 °C, 1 atm), and / or can be solid such as wax. During the FT reaction, a non-condensable fraction or lower fraction (having a carbon chain with up to 5 carbon atoms) is also produced and is referred to in the present invention as lower hydrocarbons or lower fraction. Other gases or unreacted gases such as CO2, N2, oxygenates, and unreacted syngas (CO, H2) are referred to herein as FT exhaust gas. Further, "dry syngas" refers to syngas comprising less than 5 volume% H2O, preferably less than about 3 volume%, more preferably less than 1 volume% H2O.

[0009] The FT product is usually separated into two streams, a stream of higher hydrocarbons that will undergo further processing such as separation and / or upgrading in the future, and a stream of lower (gaseous) fractions, i.e., the above-mentioned FT exhaust gas.

[0010] Downstream of the FT unit, an upgrading and distillation unit is generally installed to produce the desired fraction(s) of hydrocarbons from the stream of higher hydrocarbons, and the above-mentioned fraction(s) can be fuels such as kerosene, naphtha, diesel oil, gasoline.

[0011] Conventionally, synthesis gas can be obtained by various reforming reactions. Advantageously, synthesis gas can be obtained from a CO source. In that case, two main routes are essentially available for converting CO to synthesis gas. One of them is the reverse water-gas shift reaction (RWGS), which converts CO to CO and water in the presence of a large excess of H. The RWGS reaction is the reverse process of the chemical equilibrium water-gas shift reaction, in which CO and H are produced from CO and H2O. With the idea of ​​reducing the carbon footprint of industrial processes and using anthropogenic CO, the WGS reaction can be driven toward the consumption of CO to form CO, and this reaction is called the RWGS reaction. To reverse the WGS reaction, a large excess of H is preferred.

[0012] Alternatively, CO and HO can be converted to synthesis gas (CO+H) by co-electrolysis. As known to those skilled in the art, co-electrolysis (also a co-electrolysis process) is carried out in a co-electrolyzer reactor in the presence of the CO and HO streams to be electrolyzed. FT flue gas can also be processed in a co-electrolyzer combined with a classical catalytic reformer to form synthesis gas.

[0013] The conversion of CO2 to synthesis gas by RWGS reactions or co-electrolysis may represent a viable route to actually convert CO2 to CO. Since CO2 is already present in the atmosphere or emitted through various industrial processes and transportation, using this CO2 represents a good way to reduce greenhouse gas emissions by converting it into a valuable gas for the production of liquid fuels, thereby reducing the overall carbon footprint of the process itself and downstream processes that use said fuels.

[0014] According to the present invention, plasma-based processing refers to reactions occurring in the plasma state of materials in a plasma-based reactor. Several reactions, including but not limited to steam methane reforming, dry reforming, partial oxidation, autothermal reforming, and reverse water gas shift reaction, can occur in a plasma-based reactor, and depending on the reactants present, the maximum amount of gas entering the plasma-based reactor can be converted to syngas. In an embodiment, plasma-based processing is performed in a plasma-based reactor in which syngas is generated primarily from FT exhaust gas and, optionally, a moderator stream. A moderator according to the present invention is an additional gas stream that can be injected into the plasma-based reactor to control or drive the formation and composition of the syngas formed in the plasma-based reactor. The moderator can be CO2, H2, HO, O2, or a mixture thereof.

[0015] In a further embodiment, the plasma-based process is integrated into a unit equipped with CO and H inlets to generate the RWGS reaction in a plasma-based reactor, a so-called plasma-based RWGS reactor. Thus, in a plasma-based RWGS reactor, the predominant reaction occurring within the plasma-based reactor as defined above is the RWGS reaction with the further addition of CO and H. Thus, in a plasma-based RWGS reactor, synthesis gas is primarily produced from the CO, H, and FT tail gas streams. Furthermore, optional modifiers can be added to the plasma-based RWGS reactor if further control of the synthesis gas composition is desired or required.

[0016] In this context, the expression "hot syngas" refers to the syngas formed during the reforming process, i.e., the plasma-based treatment and / or the co-electrolysis and / or the RWGS reaction. In other words, hot syngas refers to the syngas discharged from the RWGS reactor, and / or the co-electrolyzer reactor, and / or the plasma-based reactor, and / or the plasma-based RWGS reactor. The expression "cooled syngas" refers to the syngas after treatment in the cooling step. The expression "dry syngas" refers to the syngas sent to the FT reactor. Unless otherwise indicated, when the term "syngas" is used alone in this specification, it can refer to hot syngas, cooled syngas, and / or dry syngas.

[0017] The FT reaction produces higher hydrocarbons, such as crude liquid fuels, which can be upgraded in an upgrading / distillation process to obtain pure higher hydrocarbons or a defined fraction as synthetic fuels having a desired carbon chain composition, density, and / or viscosity. Advantageously, the higher hydrocarbons from the FT reactor are further fed to a downstream separation step, such as a distillation unit, to obtain one or more defined fractions of higher hydrocarbons and a separation / distillation waste fraction. The separation / distillation waste fraction is also advantageously treated by the plasma-based treatment described above in a plasma-based reactor and / or a plasma-based RWGS reactor. The distillation waste fraction generally consists of undesired components recovered during the upgrading / distillation step and is advantageously recycled to the plasma-based reactor for plasma-based treatment.

[0018] The one or more defined fractions of higher hydrocarbons, also referred to as defined fractions, refer to the desired compounds recovered after a separation process, such as after distillation or upgrading. The defined fractions generally account for about 65% by volume, preferably more than about 75% by volume, of the higher hydrocarbon fraction before separation / distillation, the proportion depending, inter alia, on the FT reaction conditions. Among the defined fractions, gasoline, kerosene, and / or diesel are particularly preferred. Further defined fractions may be, for example, paraffin / wax or other oxygenated hydrocarbon fractions.

[0019] In embodiments, production in the FT reactor can be advantageously controlled to more specifically / predominantly produce certain defined fractions. One way to control the reaction in the FT reactor is to control the composition of the dry syngas entering the FT unit. As already mentioned above, the expression "dry syngas" as used herein refers to the syngas entering the FT reactor and generally refers to a syngas with very little water, i.e., less than about 5% by volume, preferably less than about 3% by volume, and more preferably less than about 1% by volume of H2O. In embodiments where fuel fractions such as gasoline, kerosene, and / or diesel are preferred, the dry syngas may have a H2 / CO ratio of about 1.70 / 1 to about 2.50 / 1, preferably about 1.80 / 1 to about 2.30 / 1, and more preferably about 1.90 / 1 to about 2.10 / 1. The composition of the dry syngas, more specifically the H / CO ratio, can be controlled by, for example, adding a conditioning stream comprising CO, and / or H, and / or HO and / or O to the plasma-based treatment of the FT flue gas, and / or by, for example, controlling the flow of CO and / or H fed to the RWGS reaction, and / or by, for example, controlling the flow of CO and / or HO and / or FT flue gas fed to the co-electrolyzer, and / or by, for example, mixing an additional flow of H into the hot, cooled, or dry syngas. The H / CO ratio herein refers to the molar ratio of H to the molar ratio of CO in the dry syngas. Because the composition of higher hydrocarbons produced by the FT reaction depends on the H / CO ratio of the syngas, it is highly advantageous to monitor and control this ratio via conditioning streams located at various locations in the fuel plant. In embodiments, the ratio can be controlled by injecting a conditioning stream into the plasma-based treatment, thereby controlling the plasma-based treatment reaction according to the composition of the gas entering the plasma-based treatment. This control allows further optimizing the reforming reaction conditions and achieving good conversion of undesired components into syngas, thereby obtaining an ideal high-temperature syngas composition.

[0020] In the present invention, the dry synthesis gas is partially formed by the plasma-based treatment of the FT flue gas, and may advantageously also comprise a separation / distillation waste fraction. The conditioning stream added to the plasma-based treatment of the FT flue gas allows for better control and optimization of the conversion of the FT flue gas to synthesis gas in the plasma-based treatment, thereby forming a synthesis gas comprising mainly CO and H2 and additional components. Further components, as defined herein, may be undesirable or inert to the FT reaction, may result from an incomplete reaction, or may be by-products in the RWGS reaction, and / or the co-electrolyzer, and / or the plasma-based treatment. The additional components may be, for example, lower hydrocarbons, N2, CO2, HO, etc.

[0021] Gases other than CO and H2 present in the FT flue gas can react specifically with the conditioning stream to obtain the desired synthesis gas. Furthermore, the composition of the conditioning stream can be advantageously adjusted depending on the FT flue gas composition to optimize the conversion. The conditioning stream can control the conversion of the FT flue gas to synthesis gas, thereby not only obtaining a minimum concentration of further components in the synthesis gas, but also advantageously control the resulting H2 / CO ratio in the synthesis gas, for example by adding a controlled excess of H2 in a plasma-based process.

[0022] In the prior art, FT exhaust gases are generally vented to avoid the undesirable accumulation of unwanted components. Indeed, when FT exhaust gases are continuously reinjected into the FT reaction loop, inert or undesirable components tend to accumulate in the loop, thereby reducing the efficiency of syngas conversion to liquid fuel and increasing the volumetric flow rate processed in the process. Advantageously, the use of plasma-based treatment of FT exhaust gases can significantly reduce the proportion of undesirable compounds that accumulate in the loop, while allowing for further control of the reforming of the FT exhaust gas. That said, even when FT exhaust gases are recycled in plasma-based treatments as proposed herein, it may still be necessary to vent the undesirable gases or reuse them elsewhere, such as as fuel gas. In fact, in the plasma-based process, different reactions such as, but not limited to, steam methane reforming, dry reforming, partial oxidation, autothermal reforming, and reverse water gas shift reaction can occur, allowing the maximum amount of gas entering the plasma-based process to be converted into synthesis gas; therefore, the FT exhaust gas entering the plasma-based reactor can be advantageously converted into high-temperature synthesis gas, and only a small amount of FT exhaust gas remains unconverted in the high-temperature synthesis gas.

[0023] According to the present invention, a portion of the dry syngas going to the FT reactor is formed by the RWGS reaction, which converts CO and H to CO and H0, and / or by co-electrolysis, which converts CO and H0 to CO and H. Control of the dry syngas composition can be achieved at various stages of dry syngas formation. When dry syngas is produced by co-electrolysis, the composition of the dry syngas can be controlled by adjusting the CO and H0 inlet. It is also possible to control and adjust the composition of the dry syngas by adjusting the H / CO molar ratio by controlling the flow of CO and / or H into the RWGS reaction. The RWGS reaction converts CO and H to CO and H0, and by adding excess H, the reaction equilibrium can be shifted toward higher conversion to CO. Advantageously, the unreacted excess H can be used to optimize and fine-tune the H / CO ratio of the resulting high-temperature syngas. If H2 is added upstream of the RWGS reactor, it needs to be heated before injection, either to pass through the RWGS reactor or within the reactor itself. In embodiments, the H2 stream is mixed into a hot syngas stream and / or mixed into a cooled syngas stream and / or mixed into a dry syngas stream.

[0024] Advantageously, when H2 is added to the cooled syngas and / or dry syngas, i.e., downstream of the cooling step, it is not necessary to first heat the H2, thereby saving heating energy. Furthermore, H2 can also be introduced into the plasma-based reactor and / or the plasma-based RWGS reactor and / or the hot syngas exiting the RWGS reactor. Because the plasma-based processing and RWGS reactions occur at high temperatures above about 1250°C, the H2 added to the hot syngas stream will cool the hot syngas stream to the desired temperature, thereby quenching the reforming reaction to obtain the desired syngas composition and temperature. This allows for a reduction in the energy consumption of the overall process, as the H2 acts as a cooler, thus saving energy losses that may occur during cooling. In other words, when the H2 stream is mixed with the hot syngas downstream of the plasma-based reactor, not only does it not need to be heated to a high temperature in advance, but the H2 added downstream can also be used to quench the hot syngas produced in the plasma-based reactor, both of which are highly beneficial in terms of energy savings.

[0025] The composition of the resulting dry syngas entering the FT reactor influences the performance of the FT reaction and / or the composition of the resulting hydrocarbons, therefore controlling and adjusting the gas composition using a tuning stream is a simple yet powerful feature, allowing to obtain an optimized dry syngas mixture for the FT reaction according to the desired defined fractions.

[0026] Advantageously, the additional components (as defined above) in the dry syngas, i.e., the syngas entering the FT reactor, represent less than about 50% by volume of the dry syngas, preferably less than about 35% by volume, e.g., less than about 30% by volume, more preferably less than about 25% by volume, e.g., less than about 20% by volume, and even more preferably less than about 15% by volume. Water can be an inhibitor of the reaction, while CO2 and lower hydrocarbons such as methane and other gases are inert to the FT reaction. A further advantage is that the FT reaction can be further optimized by controlling the total concentration of such components entering the FT reactor. Such components can be removed from the FT tail gas when recycled. However, in the present invention, the FT tail gas is treated with a high-temperature plasma to enable more efficient recycling of the FT tail gas into the process, and the plasma-based treatment can be further optimized by the addition of the aforementioned conditioning streams to obtain a dry syngas suitable for the desired operation of the FT reaction. These parameters significantly affect the carbon conversion yield of the overall process, reducing CO2 and other tail gas emissions and providing significant benefits in terms of the overall carbon footprint.

[0027] Because the FT reaction and resulting FT products depend on the H / CO ratio, the FT conversion of syngas to higher hydrocarbons is also affected by the presence of additional components in the dry syngas that may be inhibitors of the reaction or inert to the reaction. Because HO is a reaction product of the FT reaction, it will generally act as an inhibitor of the FT reaction. Therefore, it is advantageous to reduce its amount in the dry syngas. Thus, dry syngas, as defined herein, preferably means that the syngas has an HO concentration of less than about 5% by volume, preferably less than about 3% by volume, and more preferably less than about 1% by volume of HO.

[0028] The FT reaction can be operated at temperatures between 330 and 370°C, commonly referred to as High Temperature FT (HTFT). HTFT provides products in the naphtha range containing linear and branched olefins with high aromatic and oxygenate content. When FT operates at temperatures between 210 and 260°C, the process is referred to as Low Temperature FT (LTFT), and syngas is converted to linear long-chain paraffins and light olefins, methane, petroleum gas, naphtha, kerosene, and wax. In embodiments, the FT reactor, which can be either HTFT or LTFT, can generally be operated at temperatures between about 180°C and about 350°C, preferably between about 200°C and about 230°C. Furthermore, the FT reactor is advantageously operated at pressures between about 5 and about 60 barg, preferably between about 10 and about 50 barg, more preferably between about 20 and about 45 barg, and even more preferably between 20 and 30 barg. Furthermore, the FT reactor preferably uses a catalyst, such as, for example, one or more cobalt and / or iron catalyst compounds. The FT reaction conditions are preferably optimized to (preferentially) obtain the desired defined fraction(s). When the FT reactor operates at the lowest temperature, about 180°C to about 200°C, longer hydrocarbon chains, such as paraffins and / or olefin derivatives, can generally be obtained. At the preferred temperature of about 200°C to about 230°C, the higher hydrocarbons primarily produced after the upgrading step can advantageously be kerosene, diesel, or other higher hydrocarbons. The selectivity of the FT synthesis can also be controlled by the choice of catalyst.

[0029] In embodiments, the H stream is generated by electrolysis, and / or the CO stream is recovered from direct air capture, flue gases, and / or other industrial exhaust gases, preferably from direct air capture. This process consumes CO, which may be obtained as a product or by-product from various industrial processes, preferably from sources such as biomass or direct air capture, thus significantly reducing the carbon footprint of the process and, consequently, the hydrocarbon product. One advantage of using CO as a starting material for liquid fuel production is that CO, an important major greenhouse gas emitted primarily from oil refineries, power plants, steel production, cement plants, and transportation, can be reused as a valuable starting material for producing liquid fuels with an overall nearly carbon-neutral footprint. Thus, CO is not considered a waste product, but rather a valuable carbon source for the production of liquid fuels. Higher hydrocarbons obtained by this process can be used as fuels for transportation, e.g., aviation. Such recycling of CO2 emissions could lead to the production and use of greener liquid fuels, leading to a significant reduction in atmospheric CO2 and even a neutral carbon footprint, thus helping to achieve the Paris Agreement on greenhouse gas emissions.

[0030] Control and optimization of plasma-based processes can be advantageous in optimizing the recycling of FT exhaust gases. In embodiments, the plasma-based process is plasma-facilitated at temperatures above about 1000°C, preferably above about 1250°C, more preferably above about 1500°C, even more preferably above about 2000°C, such as above about 2500°C, above about 3000°C, or above about 4000°C, even up to 5000°C or higher, and / or at pressures below about 45 barg, such as below 40 or 30 barg, preferably below about 20 or 15 barg, more preferably below 10 barg, such as below 7.5 barg, even more preferably below 5 barg. The plasma-based processing unit may include any suitable means for generating plasma for performing the plasma-based processing. In embodiments, the plasma-based processing unit may include one or more plasma torches, preferably electrode-based plasma torches and / or electrodeless plasma torches that ignite transfer and / or non-transfer arcs. The one or more plasma torches may include a direct current plasma torch, an alternating current plasma torch, a three-phase alternating current plasma torch, or a combination thereof. The plasma torches may have a total power of about 1 to about 20 MW, preferably about 3 to about 15 MW, and more preferably about 5 to about 10 MW. The electrodeless plasma torch may include an induction-ignition plasma torch, a microwave plasma torch, a radio frequency plasma torch, or a combination thereof.

[0031] Considering the reduction of CO2 emissions, and more generally, the emission of gases produced during industrial processes, the precise control of syngas production in plasma-based processes is an advantage. One advantage of plasma-based processes is that they enable high CO2 conversion rates compared to traditional thermal / thermal catalytic processes such as reverse water-gas shift (RIWS) and dry reforming of hydrocarbons with CO2. The CO2 referred to here can be CO2 present in the FT flue gas or CO2 from a conditioning stream. Another advantage of plasma-based processes is that they convert additional components present in the FT flue gas into syngas without the need for a catalyst. Several reforming reactions can occur in plasma-based processes, including, but not limited to, steam methane reforming, dry reforming of hydrocarbons with CO2, partial oxidation, autothermal reforming, and (reverse) water-gas shift reforming, which can result in higher conversion rates and lower concentrations of additional components in the resulting syngas. In some embodiments, the FT flue gas can be completely recycled; in other embodiments, the FT flue gas can be partially recycled and partially vented or utilized elsewhere.

[0032] In an embodiment, the present invention also describes a method in which an RWGS reaction is carried out in an RWGS reactor to produce a first stream of hot syngas, the first stream of hot syngas is processed in a first quench / cooling / heat recovery unit to form a first stream of cooled syngas, plasma-based treatment of the FT tail gas is carried out in a plasma-based reactor to produce a second stream of hot syngas, the second stream of hot syngas is processed in a second quench / cooling / heat recovery unit to form a second stream of cooled syngas, and the first and second streams of cooled syngas are dried, optionally compressed, and mixed in a drying / mixing unit to obtain a dry syngas. Advantageously, the desired H / CO ratio of the resulting second stream of hot syngas is fixed in the quench / cooling / heat recovery unit, thus avoiding reverse reactions that may occur at low temperatures during the cooling step and result in lower syngas quality for the FT reaction to form the second stream of cooled syngas. The quenching / cooling / heat recovery step may include a quenching / cooling step in which the hot syngas is cooled to a temperature of about 400 to about 500°C, and a further heat recovery step, for example via a heat exchanger, in which the syngas heat is transferred to another fluid / stream, allowing the syngas to reach a temperature of preferably about 20°C to about 80°C.

[0033] The first stream of hot syngas from the RWGS reactor is also quenched and cooled to obtain a first stream of cooled syngas that is advantageously mixed with the second stream of cooled syngas from the plasma-based process. The RWGS reaction is carried out in an RWGS reactor operating at a temperature of about 750°C to about 1200°C, preferably about 800°C to about 1000°C, more preferably 850°C to about 950°C, at a pressure of about 1 to about 40 bar, preferably about 3 to about 30 bar, more preferably about 5 to about 15 bar, and / or in the presence of a catalyst. In embodiments, upon exiting the plasma-based process, the second stream of hot syngas has a temperature of greater than 900°C to about 2000°C, or even greater than about 2000°C, and the second stream of cooled syngas advantageously has a temperature of less than about 500°C, preferably about 400°C to about 500°C, more preferably less than about 400°C. In an embodiment, upon exiting the RWGS reactor, the first hot syngas stream has a temperature of about 800°C to about 1500°C, preferably about 900°C to 1200°C, more preferably about 800°C to about 1100°C, and even more preferably about 800°C to about 950°C, and the first stream of cooled syngas advantageously has a temperature below about 500°C, preferably below about 400°C, and more preferably below about 80°C. To quench the reaction and fix the syngas composition, a conditioning stream of H2 can be added to the first and / or second streams of hot syngas. The resulting cooled syngas is preferably dried to remove water formed during the previous reaction, resulting in a dry syngas suitable for the FT reaction. In this step, a further stream of H2 can be advantageously added to adjust the final H2 / CO ratio of the resulting dry syngas before entering the FT reactor. Another advantage of the continuous cooling / drying steps is the control of the temperature of the resulting dry syngas, which will enter the FT reactor at a defined reaction temperature. Another advantage is that the vapor formed during the cooling / drying step can further be used as a source of HO for the electrolytic generation of H, thereby recycling and minimizing the net HO required for the process by closing the loop on H production, which is an advantage from the perspective of process sustainability.

[0034] In an embodiment, the present invention describes a method in which co-electrolysis is performed in a co-electrolyzer reactor to produce a first stream of hot syngas, the first stream of hot syngas is processed in a first quench / cooling / heat recovery unit to form a first stream of cooled syngas, plasma-based treatment of the FT tail gas is performed in a plasma-based reactor to produce a second stream of hot syngas, the second stream of hot syngas is processed in a second quench / cooling / heat recovery unit to form a second stream of cooled syngas, and the first and second streams of cooled syngas are dried and preferably mixed in a drying / compression / mixing unit to obtain a dry syngas. Advantageously, a stream of H2 can be added to the second stream of hot syngas to quench the reaction and fix the syngas composition. The stream of H2 can also be mixed with the first stream of cooled syngas or with the dry syngas.

[0035] In another embodiment, the present invention describes a method in which the RWGS reaction and plasma-based treatment are carried out in a plasma-based RWGS reactor to form a high-temperature syngas synthesis stream, and the combined high-temperature syngas stream is processed in a combined quench / cooling / heat recovery unit to obtain a dry syngas. The plasma-based RWGS reactor refers to a reforming unit in which the RWGS reaction to convert CO to CO is carried out under plasma-based conditions at temperatures above about 1250°C, preferably above about 1500°C, or even higher, as described above. At these conditions, CO conversion is optimized and H inlet is reduced. The RWGS reaction requires a high excess of H to efficiently convert CO. The high temperatures in the plasma-based RWGS reactor allow for the conversion of CO with high conversion yields without the need for additional H. These reaction conditions offer the potential to convert CO to CO with good conversion yields, reduce H consumption, thereby reducing H production and the overall energy required to produce the final liquid fuel. Another advantage of the high-temperature conditions and plasma-based RWGS reactor is that the reaction occurs far beyond the thermodynamic equilibrium for converting CO2 to syngas, advantageously reducing excess H2 input and eliminating the need for a catalyst in the RWGS reaction. Furthermore, recycling FT flue gas to the plasma-based RWGS reactor also reduces the concentration of H2 needed to run the RWGS reaction, thereby reducing the power consumption demand when H2 is generated on-site. The reduced H2 production and utilization is also beneficial from the perspective of the sustainability of the overall process. Another advantage of using plasma-based processing as a reforming unit is the high conversion rate of hydrocarbons and other gases and additional components from FT flue gas and stillage gas to syngas, which can then be recycled within the FT loop. Near-complete conversion of additional components, such as CO2 and lower hydrocarbons, reduces the concentration of these components that may accumulate in the recycle loop, thereby reducing the amount of gas emitted compared to a conventional reformed FT flue gas recycle loop.

[0036] In an embodiment, a flow of H2 is added into the combined flow of hot syngas to quench and fix the syngas composition, i.e., H2 / CO ratio.

[0037] In another embodiment, the present invention describes a method in which plasma-based treatment of FT exhaust gas is performed in a plasma-based reactor to produce a second stream of hot syngas, the second stream of hot syngas is mixed with CO and H streams to form a third stream of hot syngas, the third stream of hot gas is treated in a RWGS reactor to form a fourth stream of hot syngas, and the fourth stream of hot syngas is cooled and dried in a quench / cooling / heat recovery / drying unit to form a dry syngas stream. The second stream of hot syngas exiting the plasma-based reactor has a temperature greater than about 1250°C, preferably greater than about 1500°C, and more preferably greater than about 1750°C. This hot syngas is mixed with CO and H streams before being subjected to the RWGS reaction. Depending on the temperature and flow rate of the second stream of hot syngas and the desired flow rate of the third stream of hot syngas, an additional heating step may be provided either before or within the RWGS reactor to reach the desired temperature required for the RWGS reaction. Advantageously, if during the mixing step of the CO and H streams with the second stream of hot synthesis gas, the resulting gas mixture is heated to a temperature above about 900°C, preferably above about 950°C, then no additional heating step is required. The third stream of hot synthesis gas is further sent to the RWGS reactor at a relatively high temperature, thereby limiting the heating energy required to heat the gases to carry out the RWGS reaction. Advantageously, this will simplify the process and improve the energy efficiency of the overall process. Furthermore, this will reduce the carbon footprint as the FT tail gas is efficiently utilized in the process of producing liquid fuels.

[0038] Advantageously, a flow of H2 is added to the flow of dry synthesis gas.

[0039] In a further embodiment, the hot syngas streams are compressed after being processed in a quench / cooling / heat recovery unit before being mixed together. Additionally, the dry syngas can be compressed after drying / mixing and before being processed in the FT reactor. The compression step is performed in a compressor unit as needed, i.e., when there is a pressure difference between the streams.

[0040] Heat from the hot syngas can also be advantageously recovered in a heat recovery unit during cooling, and said recovered heat can be further used to heat the inlet FT tail gas entering the plasma-based reactor, and / or to heat the inlet gas of the RWGS reactor, and / or to heat the dry syngas before entering the FT reactor.

[0041] The heat generated during quenching can be used for the production of steam which can be further used in the electrolyzer unit to produce H2 and / or synthesis gas.

[0042] In a further embodiment, the first and / or second streams of hot syngas, and / or the combined stream of hot syngas, and / or the first and / or second streams of cooled syngas, and / or the combined stream of cooled syngas, and / or the dry syngas stream are compressed in a compression unit, preferably the first and / or second streams of cooled syngas, and / or the cooled syngas stream, more preferably the dry syngas. The hot syngas formed in the RWGS reactor and / or the co-electrolyzer reactor and / or the plasma-based reactor and / or the plasma-based RWGS reactor generally have different pressures when leaving each reactor. Advantageously, a compression step can be implemented to adjust the pressure of the syngas before the next step. The compression can be implemented in a combined quench / cooling / heat recovery unit and / or in a separate unit. The compression is preferably implemented after the heat recovery step, more preferably after the drying step. However, the compression step can be implemented at different stages of the process, which can be selected by a person skilled in the art to optimize the process.

[0043] "About" in this context means that a given numerical value covers a range of values ​​from -10% to +10% of that numerical value, preferably from -5% to +5% of that numerical value, or even from -2.5% to +2.5% of that numerical value. [Brief explanation of the drawings]

[0044] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Figure 1] FIG. 1 is a schematic diagram of a first embodiment. [Figure 2] FIG. 10 is a schematic diagram of a second embodiment. [Figure 3] FIG. 10 is a schematic diagram of a third embodiment. [Figure 4] FIG. 10 is a schematic diagram of a fourth embodiment.

[0045] Further details and advantages of the invention will become apparent from the following detailed description of some non-limiting embodiments, with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION

[0046] FIG. 1 shows a fuel plant installation including a reverse water gas shift reactor (RWGS) 11 into which H, generated, for example, by H2O electrolysis or other sources, and CO, for example, from direct air recovery or other sources, are introduced via streams A20 and A31, respectively. The RWGS reactor operates at a temperature greater than approximately 850°C and is electrically or otherwise heated to heat the feed gas, or an electric heater is coupled to the RWGS. The first hot syngas S1b produced in the RWGS reactor 11 contains primarily CO and H2 gas. Small amounts of H2O and CO2 are also present. The first hot syngas S1b is further cooled in a quench / cooling / heat recovery unit 21 to produce a first cooled syngas S2b. The quench / cooling / heat recovery unit 21 may include a heat recovery unit or a process gas boiler or other setup to utilize the sensible heat of the syngas from unit 21. This recovered heat can be used to heat inlet streams A10 and / or A20 and / or A70 and / or S3, or for other purposes such as generating steam for an electrolyzer or elsewhere.

[0047] In parallel, the FT tail gas A70 exiting the FT reactor 40 is sent to the plasma-based reactor 10 to be converted into a second stream of high-temperature syngas S1a. In a preferred embodiment, an adjustment stream (CO2, H2, O2, HO, CO, hydrocarbon gases) A10 is injected into the plasma-based treatment reactor 10 to adjust the gas concentration and the final composition of the high-temperature syngas S1a. A gas detection probe (not shown) can be placed upstream and / or downstream of the plasma-based treatment reactor 10 to control the gas composition to better adjust the final dry syngas composition depending on the gas composition entering the plasma-based treatment reactor 10. The reactor 10 generally operates at a temperature above about 1500°C and a pressure below about 45 barg, preferably below about 10 barg, and the resulting high-temperature syngas is further rapidly cooled / quenched in the quench / cooling / heat recovery unit 20 to avoid the activation of reverse reactions during the cooling process. Quench / cooling / heat recovery unit 20 may include a heat recovery unit to utilize the sensible heat of the syngas coming from unit 20. This recovered heat can be used to heat inlet streams A10 and / or A20 and / or A70 and / or S3, or for some other purpose such as generating steam for electrolysis or elsewhere.

[0048] The resulting cooled syngas streams S2a and S2b from units 20 and 21 are dried and mixed in drying / mixing unit 30 to provide dry syngas S3. A compression step (not shown) may be required for either S2a and / or S2b, as well as after drying / mixing unit 30, depending on the pressure differential between S2a, S2b and the pressure required for FT reactor unit 40.

[0049] In a preferred embodiment, the dry syngas S3 has a gas composition with a molar ratio of H2 / CO between 1.90 / 1 and 2.10 / 1, with additional components CO2, N2, and lower hydrocarbons inert to the FT reaction representing less than 35 vol.% of the total composition of the dry syngas S3. Furthermore, the amount of H2O is preferably less than 1 vol.% to optimize the FT reaction. To adjust the final H2 / CO ratio of the dry syngas S3, additional stream A31 of H2 can be injected into the mixing unit 30 and / or streams S2b and / or S2a and / or S3 before injection into the FT reactor unit 40. Controlling the H2 content by adding stream A31 directly to the mixing unit 30 and / or the cooled syngas S2b and / or S2a and / or the dry syngas S3 avoids heating the H2 at high temperatures, thereby reducing the energy required to operate the e-fuel plant. Stream A31 can also be used to control the pressure of the cooled and dry syngas.

[0050] Dry syngas stream S3 is further injected into FT reactor unit 40, which preferably operates at a temperature of 200-230°C and a pressure of 20-30 barg using cobalt or iron as the bed catalyst. The resulting stream is split into streams A50 and A70. Stream A50, containing higher hydrocarbons, i.e., liquid hydrocarbons, wax, and other oxygenated components, is further processed in an upgrading / distillation unit to obtain a defined fraction of higher hydrocarbons, stream A60. FT tail gas stream A70, containing unreacted components of dry syngas S3 and additional components resulting from the FT reaction, e.g., C1-C5 hydrocarbons and water, is recycled back to plasma-based treatment reactor 10. Furthermore, the stillage gas, stream A80, exiting upgrading / distillation unit 50 and comprising primarily CO2, CO, H2, H2O, hydrocarbons, and N2, is recycled back to plasma-based treatment reactor 10.

[0051] In a preferred embodiment, the defined higher hydrocarbon stream A60 produced in unit 50 is kerosene, and naphtha is formed as a by-product. In other embodiments, diesel oil can be recovered, and other components such as paraffins or oxygenated compounds can also be recovered depending on the parameters of the FT reactor 40 and / or unit 50.

[0052] In addition, the condensate / vapor produced in unit 21, i.e., stream A40, can be used as a source for the production of H2 by electrolysis (not shown).

[0053] The FT process converts syngas into hydrocarbons. Usually, heavy hydrocarbons are taken out as wax and condensate, but unreacted syngas (CO + H2), and components inert to the FT process such as lower hydrocarbons (<C5), CO2, N2 leave the FT process together with the exhaust gas, also known as FT exhaust gas A70. If the FT exhaust gas is recycled to the FT process, H2 and CO serve the role of the FT reaction, but hydrocarbons, like CO2, are components inert to FT and accumulate over time. Therefore, it is necessary to remove it from the loop by either discharging the FT exhaust gas directly to the atmosphere or using it as fuel somewhere within the industrial plant. However, discharging or otherwise using the FT exhaust gas elsewhere as fuel reduces the product and carbon yields, as well as the energy efficiency of the e-fuel plant. The same applies to the distillation waste gas.

[0054] However, in the present process, the FT flue gas and stillage gas are sent to a plasma-based reactor 10 for conversion to synthesis gas, which can be further recycled in the FT process. The plasma-based treatment allows for the conversion of most of the hydrocarbons, CO2, and HO contained in the FT flue gas and stillage gas to synthesis gas, thereby eliminating the need to vent additional components in each loop and significantly reducing the amount of additional components returned to the FT reactor. However, some additional components may not be converted to synthesis gas and may accumulate in the loop, so additional components may be vented if necessary (not shown). Nevertheless, by using impurity-free feed gases A20, A30, and A10, such as N2, a nearly closed loop of FT flue gas can be obtained without the need to vent or remove inert gases from the loop.

[0055] One advantage of the present method is that all of the undesired fractions of the distillation unit, i.e. the distillation gases that are not recovered as defined fractions, can be recycled back into synthesis gas by means of the plasma reactor.

[0056] One of the other advantages of the present method is that plasma allows for a high conversion of hydrocarbons and CO2 from the FT exhaust gas compared to conventional catalytic reforming. This significantly reduces the remaining unconverted hydrocarbons and CO2 in the produced synthesis gas. Therefore, the fraction of inert components that goes to the FT process by recycling the FT exhaust gas is reduced compared to conventional catalytic reforming. This increases the FT throughput.

[0057] Another important advantage of the present invention is that electricity is used as the energy source for recycling the FT flue gas and distillate gas. Considering that green electricity is provided for this purpose, the CO₂ footprint of the process can be significantly reduced while enabling higher product yields and greater energy efficiency compared to conventional reforming processes. When FT flue gas reforming is performed using a conventional reformer, such as a partial oxidation reformer or autothermal reformer, oxygen is typically injected to convert hydrocarbons to synthesis gas. This results in the consumption of H₂, which reacts with O₂ to form H₂O. This side reaction results in the loss of H₂ and the undesirable formation of H₂O. However, in the present invention, O₂ injection is limited, so the FT flue gas is reformed with a relatively low conversion rate of H₂ to H₂O. This minimizes the H₂ requirement for the overall process. Assuming that H₂ is generated by an electrolyzer for the fuel plant, the present invention saves energy by minimizing the H₂ requirement for e-fuel production. Therefore, the overall process is energy efficient. Although O2 supply has been proposed as a possibility for adjusting the synthesis gas composition when very large amounts of hydrocarbons are present, in the current setup the O2 demand, and therefore the H2 losses in the reaction with oxygen, are always low compared to conventional catalytic partial oxidation or autothermal reforming. Figure 2 shows a second embodiment, which differs from Figure 1 only in the way in which a first stream of hot synthesis gas S1a is produced. In this embodiment, the first stream of hot synthesis gas is produced in a co-electrolyzer reactor 11a, which is fed with a CO2 stream A20 and an HO stream A30. Advantageously, the FT tail gas A70 can also be injected into the co-electrolyzer reactor 11a, which can be combined with a classical catalyst-based reformer (not shown).

[0058] Figure 3 shows a third embodiment, which differs from Figure 1 in the way dry syngas S3 is produced. Dry syngas is produced from an integrated plasma-based RWGS reactor 110, where plasma-based treatment and RWGS reaction are combined within the unit 110.

[0059] The plasma-based RWGS reactor 110 is supplied with H stream A31, CO stream A20, and streams A70 and A80 from the FT reactor 140 and the distillation / upgrading unit 150, respectively, as recycle gases. Optionally, adjustment stream A10 can be added as reactants (comprising HO and / or CO and / or O and / or hydrocarbons) to adjust the amount of gas to obtain a combined high-temperature synthesis gas S1, with the remaining amount of CO and hydrocarbons being less than 40% by volume, preferably less than 25% by volume, more preferably less than 15% by volume of the total amount of synthesis gas S1 components.

[0060] In a conventional RWGS reactor operating at 1000°C, the conversion of CO to CO is driven by the amount of H inside the reactor. Therefore, a large amount of H is required to obtain a syngas with high CO conversion and H and CO at a molar ratio of 1.90 / 1 to 2.10 / 1 required for the FT reaction. In the embodiment shown in Figure 2, the RWGS reaction occurs in a plasma reactor at temperatures above 1250°C. At these reaction conditions, the RWGS reaction requires a low H content and no catalyst is required to convert CO. Other reactions, such as methane reforming and partial oxidation, also occur in plasma conditions. One advantage of this plasma-based RWGS reactor 110 is that the amount of H required for the RWGS reaction, i.e., the conversion of H + CO to H + CO, is less than that of a conventional RWGS reaction, significantly reducing H consumption and thus reducing H production by electrolysis and, therefore, energy savings. Since the syngas is to be further used in the FT reactor 140, the resulting combined hot syngas S1 is cooled in a cooling / quench unit 120 to quench the reaction and obtain a cooled syngas S2 with the desired H2 / CO ratio and temperature. The quench / cooling / heat recovery unit 120 may include a heat recovery unit to utilize the sensible heat of the syngas coming from unit 110. This recovered heat can be used to heat inlet streams A10, A20, A31, A70, A80 and / or for some other purpose, such as generating steam for electrolysis or elsewhere. Stream S2 is further sent to a drying unit 130 to form a dried syngas S3. If the pressure of stream S2 is not suitable for the FT reactor 140, a compression step (not shown) can be realized after the drying unit 130.

[0061] The H2 content of the resulting dry syngas S3 may need to be adjusted to a H2 / CO molar ratio of 2.1 / 1 to 2.35 / 1. This can be done by feeding H2 (A31) to unit 110 along with heated H2 at high temperature, or preferably by adding H2 directly downstream of reactor 110 or after the quench / cooling / heat recovery unit 120 for streams S2 and / or S3. This allows the H2 stream to be added at a low temperature without the need to heat H2 at high temperature. This may further improve the energy efficiency of the process. A compression step may be required in unit 130 if there is a pressure difference compared to the syngas coming from unit 120 and the requirements of the FT reactor 140. The condensate / vapor A40 produced during the cooling and drying process in units 120 and / or 130 can be recovered and used to generate H2 by electrolysis (not shown). The stream exiting the FT reactor 140 is then split into streams A50 and A70. Higher hydrocarbon stream A50 is sent to upgrading / distillation unit 150 to produce a defined fraction of higher hydrocarbons A60. FT tail gas stream A70 and stillage gas stream A80 from unit 150 are reintroduced into plasma-based RWGS reactor 110 for recycling.

[0062] 4 shows another embodiment in which a second stream of hot syngas S1a formed in the plasma-based reactor 310 is sent to a mixing unit 330 upstream of the RWGS reactor 311. The mixing unit 330 is further supplied with CO2, stream A20, from direct air recovery or another source, and H2, stream A31. One advantage of this embodiment is that the second stream of hot syngas S1a exits the plasma-based treatment unit 310 at a temperature greater than 1000°C. This hot syngas S1a is mixed with streams A20 and A31 and exits the mixing unit 330 as a third stream of hot syngas S4a. Depending on the temperature and flow rate of S1a and the desired flow rate of S4a, an additional heating step may be implemented before or within the RWGS reactor 311 to meet the thermal requirements of the RWGS reactor 311. Advantageously, if the temperatures of S1a, A20, and A31 are sufficient to ensure heating of S4a to a temperature that meets the necessary heat demands of the RWGS reactor 311, i.e., above about 900°C, preferably above about 950°C, no additional heating step is required. S4a is further sent to the RWGS reactor 311 to produce a fourth stream of hot syngas S4b. Because S4a enters the RWGS reactor 311 at a high temperature, the energy required by the heating unit 311 is reduced compared to conventional RWGS reactors. The resulting hot syngas S4b is further quenched / cooled in the quench / cooling / heat recovery unit 320 to produce dry syngas S3. Condensed vapor stream A40 can be recovered. Additionally, heat recovery can be used to heat the inlet gases A20 and A31 of the RWGS reactor 311 and the FT exhaust gas stream A70 of the plasma-based reactor 310, reducing the overall energy supply. Dry synthesis gas S3 is further sent to FT unit 340 which forms liquefied hydrocarbon stream A50 and FT tail gas A70. Liquefied hydrocarbon A50 is further processed in upgrading / distillation unit 350 which forms liquid fuel A60 and stillage gas A80. Streams A70 and A80 are returned to plasma-based treatment unit 310. Compression steps (not shown) of streams S1a, S4a, S4b, S3 can be performed to adjust the pressure of the streams as needed.Additionally, a stream of H2, namely A31, can be mixed into stream S3 to adjust the H2 / CO ratio of S3. [Explanation of symbols]

[0063] 10. Plasma-based reactors 11 RWGS reactor 11a Co-electrolyzer reactor 20 Quenching / Cooling / Heat Recovery Unit 21 Quenching / cooling / heat recovery unit 30 Drying / Mixing Unit 40 FT Reactor 50 Upgrade / Distillation Unit 110 Plasma-based RWGS reactor unit 120 Quenching / Cooling / Heat Recovery Unit 130 Drying Unit 310 Plasma-based reactor 311 RWGS reactor 320 Quenching / Cooling / Heat Recovery / Drying Unit 330 Mixing Unit 340 FT Reactor 350 Upgrade / Distillation Unit A10 Adjusted flow A20 CO2 flow A30 H2O flow A31 H2 flow A40 Steam condensate A41 Steam condensate A50 Higher hydrocarbons A60 Defined hydrocarbon fractions A70 FT exhaust gas A80 Distillation waste gas S1a Second stream of hot synthesis gas S1b First stream of hot synthesis gas S2a Second stream of cooled syngas S2b First stream of cooled synthesis gas S1 High temperature synthesis gas combined flow S2 Cooled Syngas S3 Dry Syngas S4a Third stream of hot synthesis gas S4b Fourth stream of hot synthesis gas

Claims

1. 1. A method for producing higher hydrocarbons in a Fischer-Tropsch (FT) reactor by recycling FT tail gas, comprising: feeding dry synthesis gas to the FT reactor to form higher hydrocarbons and the FT tail gas as a by-product; Including, The dry synthesis gas is ２ Flow and H ２ a reverse water gas shift (RWGS) reaction with a stream of CO ２ Flow and H ２ The dry synthesis gas obtained by co-electrolysis with a stream of O and plasma-based treatment of the FT tail gas and fed to the FT reactor contains less than 5% by volume of H. ２ O, and the higher hydrocarbons are hydrocarbons having chains ranging from C6 to C100.

2. The method of claim 1 , wherein the FT exhaust gas is treated with co-electrolysis.

3. 3. The method of claim 1 or 2, wherein the higher hydrocarbons are fed to a distillation unit to obtain one or more defined fractions of higher hydrocarbons and a distillation waste fraction, the distillation waste fraction being treated by the plasma-based treatment.

4. The dry synthesis gas is H 2 O 3 in a ratio of 1.70 / 1 to about 2.50 / 1, preferably 1.80 / 1 to 2.30 / 1, more preferably 1.90 / 1 to 2.10 / 1. ２ / CO ratio, ２ / CO ratio is CO ２ , and / or H ２ , and / or H ２ O and / or O ２ and / or by adding a conditioning stream comprising CO to the plasma-based treatment of the FT exhaust gas. ２ and / or H ２ and / or by controlling the flow of CO supplied to the co-electrolysis ２ and / or H ２ By controlling the flow of O and / or the FT exhaust gas, and / or H ２ 4. The method according to claim 1, wherein the dry synthesis gas is mixed with an additional flow of

5. 5. The method according to claim 1, wherein the further components in the dry syngas represent less than 50% by volume of the dry syngas, preferably less than 35% by volume, more preferably less than 25% by volume, and even more preferably less than 15% by volume.

6. The dry synthesis gas fed to the FT reactor contains less than 3 vol. %, preferably less than 1 vol. % H ２ The method of claim 1 , further comprising:

7. 7. The process according to any one of claims 1 to 6, wherein the FT reactor is operated at a temperature of from 180°C to 350°C, preferably from 200°C to 230°C, and / or at a pressure of from 5 to 60 barg, preferably from 10 to 50 barg, more preferably from 20 to 30 barg, using cobalt and / or iron as catalyst.

8. The H ２ The CO stream is generated by electrolysis and / or ２ 8. The method according to any one of claims 1 to 7, wherein the stream is recovered from direct air recovery, flue gases and / or other industrial exhaust gases, preferably from direct air recovery.

9. 9. The method according to any one of claims 1 to 8, wherein the plasma-based treatment is operated with a plasma at a temperature above 1000°C, preferably above 1250°C, more preferably above 1500°C, even more preferably above 2000°C, and at a pressure below 45 barg, preferably below 20 barg, more preferably below 5 barg.

10. 10. The method of claim 1, wherein the RWGS reaction takes place in a RWGS reactor to produce a first stream of hot syngas, the first stream of hot syngas is processed in a first quench / cooling / heat recovery unit to form a first stream of cooled syngas, plasma-based treatment of the FT tail gas takes place in a plasma-based reactor to produce a second stream of hot syngas, the second stream of hot syngas is processed in a second quench / cooling / heat recovery unit to form a second stream of cooled syngas, and the first and second streams of cooled syngas are dried and preferably mixed in a drying / mixing unit to obtain the dry syngas.

11. 10. The method of claim 1, wherein the co-electrolysis reaction takes place in a co-electrolysis reactor to produce a first stream of hot syngas, the first stream of hot syngas is processed in a first quench / cooling / heat recovery unit to form a first stream of cooled syngas, plasma-based treatment of the FT tail gas takes place in a plasma-based reactor to produce a second stream of hot syngas, the second stream of hot syngas is processed in a second quench / cooling / heat recovery unit to form a second stream of cooled syngas, and the first and second streams of cooled syngas are dried and preferably mixed in a drying / mixing unit to obtain the dry syngas.

12. H ２ is mixed with the second stream of hot syngas and / or mixed with the first stream of cooled syngas or mixed with the dry syngas.

13. The RWGS reaction and the plasma-based treatment are ２ and / or CO ２ 10. The method according to any one of claims 1 to 9, wherein the method is carried out in a plasma-based RWGS reactor to which a stream of FT tail gas and / or a stream of stillage gas is fed and which forms a combined stream of hot syngas, which combined stream of hot syngas is treated in a combined quench / cooling / heat recovery unit to obtain the cooled syngas.

14. The H ２ To control the H / CO ratio, ２ 14. The method of claim 13, wherein a stream of:

15. Plasma-based treatment of the FT exhaust gas is performed in a plasma-based reactor to produce a second stream of hot syngas, and the second stream of hot syngas is treated with a CO 2 -based reactor to form a third stream of hot syngas. ２ and H ２ 10. The method of claim 1, wherein the third stream of hot syngas is mixed with the first stream of hot syngas in a RWGS reactor to form a fourth stream of hot syngas, and the fourth stream of hot syngas is cooled and dried in a quench / cooling / heat recovery / drying unit to form a dry syngas stream.

16. H ２ 16. The method of claim 15, wherein a stream of is added to the stream of dry syngas.

17. 17. The method according to any one of claims 1 to 16, wherein heat from the hot syngas is recovered in a heat recovery unit during cooling, and the recovered heat is further utilized to heat the FT tail gas at the inlet of the plasma-based reactor and / or the gas at the inlet of the RWGS reactor and / or the dry syngas.

18. 18. The method according to any one of claims 1 to 17, wherein the first and / or second stream of hot syngas, and / or the combined stream of hot syngas, and / or the first and / or second stream of cooled syngas, and / or the cooled syngas stream, and / or the dry syngas stream are compressed in a compression unit, preferably the first and / or second stream of cooled syngas, and / or the cooled syngas stream, more preferably the dry syngas, are compressed in a compression unit.

19. 19. The method of any one of claims 1 to 18, wherein the heat generated during quenching is utilized for the production of steam.

20. 20. The method of any one of claims 1 to 19, wherein steam generated from the heat recovery unit is utilized in the co-electrolysis for the production of hydrogen and / or synthesis gas.

21. 21. The method of any one of claims 1 to 20, wherein the plasma-based processing unit comprises one or more plasma torches, preferably electrode-based or electrodeless plasma torches, selected from induction-ignition plasma torches, microwave plasma torches, or combinations thereof.

22. 22. The method of claim 21, wherein a transfer and / or non-transfer arc is used to facilitate the plasma-based process.

23. 22. The method of claim 21, wherein the one or more plasma torches comprise a DC plasma torch and / or an AC plasma torch and / or a three-phase AC plasma torch, and the plasma torches preferably have a total power of 1 to 20 MW, more preferably 3 to 15 MW, and even more preferably 5 to 10 MW.

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