ENHANCED Co-SOEC FTR HYBRID SYSTEM

Abstract

The present invention relates to a Co-SOEC FTR hybrid system that combines a Co-SOEC and a Fischer-Tropsch reactor, effectively converts CO₂ into CO through the recirculation of unreacted fuel and synthesis gas pretreatment reaction, and increases the selectivity of sustainable aviation fuel (e-SAF) by satisfying the stoichiometric requirements of the FT synthesis reaction, while increasing the production of sustainable aviation fuel (e-SAF) by utilizing hydrogen captured from the tail gas.

Description

Technology Field

[0001] The present invention relates to an improved Co-SOEC FTR hybrid system, and more specifically, to a technology proposed to solve the problem of low yield of the final product, e-SAF, caused by the inclusion of large amounts of unreacted H2O and CO2 in the synthesis gas supplied to the FTR due to the low carbon monoxide conversion rate of the Co-SOEC when producing e-SAF by linking a solid oxide co-electrolyte (Co-SOEC) and a Fischer-Tropsch reactor (FTR). Background Technology

[0002] As of 2011, the aviation sector accounts for 3.5% of the radiative forcing attributable to human activity, and as the demand for air transport increases in the future, the aviation sector's contribution to global warming is also expected to increase.

[0003] The International Air Transport Association (IATA) has proposed the concept of Sustainable Aviation Fuel (SAF) to replace current aviation fuels that rely on fossil fuels. SAF must possess chemical composition and physical properties nearly identical to existing jet fuels, allowing it to be blended without modifying aircraft or engines.

[0004] Meanwhile, e-Fuel is an abbreviation for electricity-based fuel and refers to a carbon-neutral fuel synthesized from green hydrogen. Since carbon-neutral fuels are generally hydrocarbon-based fuels, they emit carbon dioxide during combustion; however, because carbon dioxide is captured from flue gas or the atmosphere during the production process, net emissions are close to zero from a life cycle assessment perspective. In this sense, e-Fuel is also referred to as green synthetic fuel.

[0005] The term 'e-fuel' is used in two main senses. First, it refers to the concept of synthetic fuels produced from green hydrogen and captured carbon dioxide, specifically Fischer-Tropsch fuels (FT fuels) that replace fossil fuels. Second, it refers to the concept of energy carriers that store renewable energy in the form of matter through water electrolysis, encompassing green hydrogen and various substances derived from it; specifically, examples include hydrocarbon fuels, green hydrogen itself, or green synthetic fuels.

[0006] A representative example of e-Fuel in the first sense is synthetic petroleum, which is also referred to by other names such as Syncrude or Sustainable Aviation Fuel (SAF).

[0007] One of the technologies for producing synthetic petroleum is a hybrid system combining a co-electrolysis SOEC (or Co-SOEC) and a Fischer-Tropsch reactor (FTR).

[0008] Hydrogen and carbon monoxide must be supplied to the Fischer-Tropsch reactor, where carbon monoxide is generated as carbon dioxide is electrochemically decomposed in a high-temperature and high-pressure environment in the upstream solid-electrolyte co-electrolyte cell.

[0009] However, since the conversion rate of carbon dioxide to carbon monoxide in solid-state electrolytic cells is not actually high (50–60%), a significant amount of unreacted carbon dioxide is supplied to the Fischer-Tropsch reactor. The Fischer-Tropsch reactor synthesizes hydrocarbon fuels through the reaction of hydrogen (H2) and carbon monoxide (CO). Since carbon dioxide (CO2) does not directly contribute to the reaction, the higher the amount of carbon dioxide (CO2) included, the lower the overall reaction efficiency. Furthermore, problems such as reactant dilution, reduced catalyst activity, additional energy consumption, and increased burden on the purification process may occur.

[0010] Korean Patent Publication No. 10-2024-0139080 (prior art) discloses a process technology for producing low-carbon intensive sustainable aviation fuel (SAF).

[0011] The prior art increases hydrocarbon production efficiency by producing an RWGS product stream through a reverse water-gas shift reactor (RWGS reactor) containing hydrogen and carbon monoxide, but it has a problem in that the overall utilization efficiency of carbon and hydrogen elements is reduced because it cannot effectively recover or recycle by-products generated in the chemical reaction, namely unreacted CO₂ and hydrogen (H₂). In addition, there is a limitation in that the composition of the generated syngas is not optimized, resulting in low selectivity in the hydrocarbon synthesis process and an increase in unnecessary side reactions, which leads to a decrease in the final fuel yield. Prior art literature

[0012] Republic of Korea Published Patent Application No. 10-2024-0139080 (September 20, 2024) The problem to be solved

[0013] The problem that the present invention aims to solve is to provide an improved Co-SOEC FTR hybrid system capable of achieving maximum aviation fuel production efficiency relative to the same input, and an aviation fuel production process using the same, by presenting appropriate treatment methods for carbon dioxide that does not participate in the reaction process of the FTR and for unreacted hydrogen and carbon monoxide contained in the output of the FTR in a hybrid system linked with Co-SOEC and FTR. means of solving the problem

[0014] To solve the presented problem, the present invention provides, as an embodiment, an improved Co-SOEC FTR hybrid system comprising: a solid oxide co-electrolyzer (Co-SOEC) that produces synthesis gas containing hydrogen and carbon monoxide by electrolyzing water and carbon dioxide; a synthesis gas treatment reactor that removes unreacted carbon dioxide contained in the synthesis gas produced by the co-electrolyzer; a Fischer-Tropsch reactor that produces hydrocarbon synthetic crude oil using the synthesis gas containing hydrogen and carbon monoxide output from the synthesis gas treatment reactor; a fuel separator that produces sustainable aviation fuel (e-SAF) by reacting the hydrocarbons of the synthetic crude oil produced in the Fischer-Tropsch reactor; and a heater that generates heat using the tail gas of the fuel separator as fuel and recirculates it to the fuel separator.

[0015] In another embodiment, at least 40% of the tail gas of the fuel separator may be recirculated to the Fischer-Tropsch reactor.

[0016] In another embodiment, at least some of the unreacted carbon dioxide in the synthesis gas treatment reactor may be recycled as an input to the solid oxide co-electrolyte cell.

[0017] In another embodiment, the fuel separator may further include a hydrogen separator and a pressure swing adsorber (PSA) that captures hydrogen from the tail gas of the hydrogen separator, and the captured hydrogen may be recirculated to the hydrogen separator.

[0018] In another embodiment, the system may further include a reverse water gas shift reactor (RWGS) that receives a tail gas containing hydrogen, unreacted carbon dioxide, and carbon monoxide from the synthesis gas treatment reactor and catalyzes the reaction between hydrogen and carbon dioxide to produce carbon monoxide, and the produced carbon monoxide and hydrogen may be recirculated to the Fischer-Tropsch reactor. Effects of the invention

[0019] According to an embodiment of the present invention, by linking a Co-SOEC with a Fischer-Tropsch reactor and effectively converting CO₂ into CO through the recirculation of unreacted fuel and the synthesis gas pretreatment reaction, and satisfying the stoichiometric requirements of the FT synthesis reaction, the selectivity of sustainable aviation fuel (e-SAF) can be increased, and the production volume of sustainable aviation fuel (e-SAF) can be increased by utilizing hydrogen captured from the tail gas. Brief explanation of the drawing

[0020] FIG. 1 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 1 of the present invention. FIG. 2 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 2 of the present invention. FIG. 3 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 3 of the present invention. FIG. 4 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 4 of the present invention. FIG. 5 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 5 of the present invention. Specific details for implementing the invention

[0021] Several embodiments of the present invention will be described in detail below with reference to the drawings. However, this is not intended to limit the present invention to any specific embodiment, and it should be understood that all transformations, equivalents, and substitutions including the technical concept of the present invention are included within the scope of the present invention.

[0022] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0023] Where in this specification it is stated that one component “have” or “comprise” a sub-component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0024] In this specification, the term “connect” may mean that two components are directly connected, but is not necessarily limited thereto, and may also mean that they are connected via one or more other components positioned between the components.

[0025] <Example 1>

[0026] FIG. 1 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 1 of the present invention.

[0027] As shown in FIG. 1, the hybrid system of Example 1 includes a solid oxide co-electrolyzer (110), a synthesis gas treatment reactor (120), a Fischer-Tropsch reactor (130), a fuel separator (140), and a heater (150).

[0028] A solid oxide electrolysis cell (110) (Carbon Monoxide Solid Oxide Electrolysis Cell, Co-SOEC) produces synthesis gas containing hydrogen, oxygen, and carbon monoxide by electrolyzing water and carbon dioxide with supplied power.

[0029] When current is supplied from outside the solid oxide electrolytic cell (110), water and carbon dioxide are electrolyzed into hydrogen (H2), oxygen (O2), and carbon monoxide (CO), respectively, at the reaction interface inside the fuel electrode, and oxygen ions move to the air electrode through the electrolyte.

[0030] Specifically, carbon dioxide receives electrons and decomposes into CO and oxygen ions (O²), and the oxygen ions (O²) are released as oxygen gas (O₂), generating electrons. Then, water moves through the electrolyte to produce hydrogen (H₂), and the oxygen ions (O²) generated in this process move to the air electrode and are released as oxygen gas (O₂). For reference, some of the oxygen gas may be supplied to the synthesis gas treatment reactor (120).

[0031] The reaction equation for the hydrogen conversion of water in the solid oxide co-electrolyte (110) is the same as Chemical Formula 1.

[0032] [Chemical Formula 1]

[0033] H2O + 2e - = H2 + O 2-

[0034] The reaction equation for the conversion of carbon dioxide to carbon monoxide in a solid oxide co-electrolyte is given by Chemical Formula 2.

[0035] [Chemical Formula 2]

[0036] CO2 + 2e - = CO + O 2-

[0037] Co-electrolysis using a solid oxide electrolyte occurs at a high temperature of 600-1000 ℃ and requires a large amount of heat, especially since water, which is one of the fuels, must be heated into high-temperature steam. Accordingly, the solid oxide co-electrolysis cell (110) of Example 1 may receive the heat required for the co-electrolysis reaction and the vaporization of water primarily from a Fischer-Tropsch reactor (130).

[0038] In this case, according to Example 1, the solid oxide co-electrolyte cell (110) does not need to be equipped with a separate device for heat supply, so the system construction cost can be reduced while the energy utilization efficiency can be increased.

[0039] The syngas treatment reactor (120) is a device that performs purification or conversion of syngas and removes unreacted carbon dioxide contained in the syngas output from the co-electrolyte (110).

[0040] The synthesis gas produced in the solid oxide electrolytic cell (110) consists mainly of hydrogen (H₂) and carbon monoxide (CO), but CO₂ that did not completely react during the electrolysis process may remain. If this unreacted carbon dioxide is not removed or converted into carbon monoxide, it may have an adverse effect on subsequent processes (e.g., Fischer-Tropsch reactor (130)).

[0041] For example, a synthesis gas treatment reactor (120) can capture carbon dioxide using any one of the processes of pressure swing adsorption (PSA), absorption tower (Amine Scrubbing), and membrane separation.

[0042] When the synthesis gas treatment reactor (120) captures carbon dioxide through pressure swing adsorption (PSA), an adsorbent (e.g., zeolite, activated carbon, etc.) can selectively capture carbon dioxide under high pressure conditions, and impurities including moisture can be removed using an adsorbent such as zeolite or silica gel.

[0043] The Fischer-Tropsch reactor (130) (Fischer-Tropsch Reactor, FTR) produces hydrocarbon synthetic crude oil (Syncrude) using a catalytic reaction with synthetic gas in which the ratio of hydrogen to carbon monoxide is controlled, output from the synthetic gas treatment reactor (120).

[0044] For example, carbon monoxide and hydrogen react on the catalyst surface to form hydrocarbons (C n H 2 n+2 It produces ). At this time, by-products such as water (H₂O) and carbon dioxide (CO₂) may also be generated during the reaction process.

[0045] The Fischer-Tropsch catalytic reaction is as shown in Chemical Formula 3 below.

[0046] [Chemical Formula 3]

[0047] CO + 2H2 → -(CH2)- + H2O

[0048] The Fischer-Tropsch reactor (130) creates an environment with a temperature of 200 to 350°C and a pressure of 10 to 35 bar. Cobalt or iron, etc., can be used as a catalyst, and liquid synthetic crude oil and water are produced through the reaction process.

[0049] In Fischer-Tropsch catalytic reactions, the number of carbon atoms in the resulting hydrocarbons varies depending on the reaction temperature and the catalyst. For example, reacting with a low-temperature cobalt catalyst produces synthetic crude oil with a high number of carbon atoms, while reacting with a high-temperature iron catalyst produces synthetic crude oil with a low number of carbon atoms.

[0050] Light hydrocarbons (e.g., gasoline) produced through a low-temperature cobalt catalyst in a Fischer-Tropsch reactor (130) can be used directly, but heavy hydrocarbons (high-molecular hydrocarbons, e.g., wax) reacted in a high-temperature iron catalyst produce sustainable aviation fuel (e-SAF) through an additional process (e.g., hydrocracking).

[0051] The fuel separator (140) hydrocracking the hydrocarbons of synthetic crude oil produced in the Fischer-Tropsch reactor (130) to produce sustainable aviation fuel (e-SAF).

[0052] The fuel separator (140) may adopt a hydrocracker. Although a hydrocracker is described below as an example of the fuel separator (140), it is not necessarily limited to this, and a hydroreating unit may be adopted instead of a hydrocracker. For reference, a hydroreating unit is a device that processes synthetic crude oil together with hydrogen to remove impurities such as sulfur and nitrogen and improve the quality of the fuel.

[0053] The fuel separator (140) converts heavy hydrocarbons into light hydrocarbons using hydrogen (H₂) at high temperature and high pressure.

[0054] The reaction equation of the fuel separator (140) is the same as chemical formula 4.

[0055] [Chemical Formula 4]

[0056] C n H m + H2→C x H y + C z H w

[0057] C n H m : Heavy hydrocarbons

[0058] H2: Hydrogen that reacts in high-temperature and high-pressure environments

[0059] C x H y , C z H w : Light hydrocarbons (aviation fuel, etc.)

[0060] The fuel separator (140) operates at high temperature (300–450°C) and high pressure (30–200 bar), and hydrocarbons are converted into low-molecular-weight molecules as their molecular structure breaks down at high pressure and temperature. That is, hydrogen reacts with a catalyst at high temperature and high pressure to break hydrocarbon bonds, thereby converting heavy hydrocarbons (wax and heavy oil, etc.) into light hydrocarbons (gasoline, diesel, aviation fuel).

[0061] For example, the fuel separator (140) separates hydrocarbons according to differences in boiling points, separating the light components into gasoline (Gasoline), the medium components into diesel, and the heavy components into aviation fuel (e-SAF).

[0062] The heater (150) generates heat using the tail gas of the fuel separator (140) as fuel and supplies it to the fuel separator (140).

[0063] For example, after aviation fuel is produced in a fuel separator (140), a tail gas containing some unreacted hydrogen and unreacted hydrocarbons (CO, CH₄, etc.) and light hydrocarbons is produced as a byproduct.

[0064] The heater (150) produces heat using this tail gas as fuel, and the fuel separator (140) that receives the heat uses the heat provided through the heater (150) to maintain and promote the hydrogenation reaction, as the hydrogenation reaction proceeds in a high temperature and high pressure environment.

[0065] <Example 2>

[0066] Example 2 relates to a technique for recirculating the tail gas of the fuel separator (140) in Example 1.

[0067] FIG. 2 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 2 of the present invention.

[0068] As shown in FIG. 2, the hybrid system of Example 2 includes a solid oxide co-electrolyzer (210), a synthesis gas treatment reactor (220), a Fischer-Tropsch reactor (230), a fuel generator (240), and a heater (250).

[0069] The solid oxide co-electrolyzer (210), synthesis gas treatment reactor (220), Fischer-Tropsch reactor (230), fuel generator (240), and heater (250) of Example 2 are basically the same as the solid oxide co-electrolyzer (110), synthesis gas treatment reactor (120), Fischer-Tropsch reactor (130), fuel generator (140), and heater (150) of Example 1, so a redundant description is omitted.

[0070] After aviation fuel is produced in the fuel generator (240), a tail gas containing unreacted hydrogen and unreacted hydrocarbons (CO, CH₄, etc.) and light hydrocarbons is produced as a byproduct.

[0071] For example, light hydrocarbons (C1–C4) have low boiling points and exist in a gaseous state, while some heavy hydrocarbons remain without being completely decomposed.

[0072] At least a portion of the tail gas from the fuel separator (240) is recirculated to the Fischer-Tropsch reactor (230). Preferably, the amount of tail gas recirculated from the fuel separator (240) to the Fischer-Tropsch reactor (230) may be at least 40% to increase reaction efficiency. The remaining tail gas from the fuel separator (240) is supplied to the heater (250).

[0073] In the Fischer-Tropsch reactor (230), the ratio of hydrogen to carbon monoxide is very important, so the insufficient hydrogen and carbon monoxide can be supplemented through the tail gas of the fuel separator (240) to improve reaction efficiency.

[0074] In addition, carbon monoxide (CO) and light hydrocarbons (C1–C4) contained in the tail gas of the fuel separator (240) may be fed back to the Fischer-Tropsch reactor (230) to allow additional hydrocarbon synthesis reactions to proceed inside the Fischer-Tropsch reactor (230) to produce more synthetic crude oil.

[0075] <Example 3>

[0076] Example 3 relates to a technique for recirculating the tail gas of a synthesis gas treatment reactor (120) in Example 1 or Example 2, or in Examples 1 and 2.

[0077] FIG. 3 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 3 of the present invention.

[0078] As shown in FIG. 3, the hybrid system of Example 3 includes a solid oxide co-electrolyzer (310), a synthesis gas treatment reactor (320), a Fischer-Tropsch reactor (330), a fuel separator (340), and a heater (350).

[0079] The solid oxide co-electrolyzer (310), synthesis gas treatment reactor (320), Fischer-Tropsch reactor (330), fuel separator (340), and heater (350) of Example 3 are basically the same as the solid oxide co-electrolyzer (110), synthesis gas treatment reactor (120), Fischer-Tropsch reactor (130), fuel separator (140), and heater (150) of Example 1, so a redundant description is omitted.

[0080] The byproducts of the synthesis gas treatment reactor (320) may include unreacted carbon dioxide, unreacted hydrogen, unreacted carbon monoxide, etc.

[0081] The synthesis gas treatment reactor (320) captures carbon dioxide using one of the following by-products: pressure swing adsorption (PSA) reaction, amine scrubbing, or membrane separation, and the captured carbon dioxide is recirculated to the solid oxide electrolytic cell (310) containing the tail gas.

[0082] In the pressure swing adsorption method, an adsorbent (e.g., zeolite, activated carbon, etc.) selectively captures carbon dioxide under high pressure conditions.

[0083] In the absorption tower method (Amine Scrubbing), an amine solution such as MEA (Monoethanolamine) or DEA (Diethanolamine) chemically binds to carbon dioxide to capture it. Then, the solution is heated to release the carbon dioxide.

[0084] Membrane separation selectively separates gases by utilizing the difference in permeation rates of carbon dioxide, hydrogen, and carbon monoxide.

[0085] In this way, a portion of the carbon dioxide captured from the byproduct of the synthesis gas treatment reactor (320) is recycled to the solid oxide co-electrolysis cell (310), and the production of synthesis gas can be increased by electrolyzing the supplied carbon dioxide to produce carbon monoxide.

[0086] Meanwhile, the synthesis gas treatment reactor (320) may not directly capture carbon dioxide from the byproduct, but may capture carbon dioxide through a separately provided pressure swing adsorber (PSA).

[0087] <Example 4>

[0088] Example 4 relates to a technique for separating hydrogen from the tail gas of a fuel separator in at least one of Examples 1 to 3 and recirculating it to a fuel separator (140).

[0089] FIG. 4 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 4 of the present invention.

[0090] As shown in FIG. 4, the hybrid system of Example 4 includes a solid oxide co-electrolyzer (410), a synthesis gas treatment reactor (420), a Fischer-Tropsch reactor (430), a fuel separator (440), a heater (450), and a pressure swing adsorber (441).

[0091] The solid oxide co-electrolyzer (410), synthesis gas treatment reactor (420), Fischer-Tropsch reactor (430), fuel separator (440), and heater (450) of Example 4 are basically the same as the solid oxide co-electrolyzer (110), synthesis gas treatment reactor (120), Fischer-Tropsch reactor (130), fuel separator (140), and heater (150) of Example 1, so a redundant description is omitted.

[0092] The main byproducts of the fuel separator (140) may include unreacted hydrogen (or excess hydrogen), unreacted hydrocarbons (methane (CH4), ethane (C2H6), etc.) and some light hydrocarbons.

[0093] The pressure swing adsorber (441) is positioned at the rear end of the fuel separator (440) and captures hydrogen from the tail gas of the fuel separator (440).

[0094] The pressure swing adsorber (441) selectively captures carbon dioxide using an adsorbent (e.g., zeolite, activated carbon, etc.) under high pressure conditions.

[0095] For example, the pressure swing adsorber (441) selectively adsorbs hydrogen through an adsorbent from the tail gas of the supplied fuel separator (440) and discharges the remaining gas (e.g., light hydrocarbons).

[0096] The hydrogen captured in the pressure swing adsorber (441) is recirculated to the fuel separator (440).

[0097] The fuel separator (140) uses the hydrogen collected and recirculated from the pressure swing adsorber (441) for hydrocracking, that is, converting high-molecular-weight hydrocarbons into light-weight hydrocarbons.

[0098] <Example 5>

[0099] Example 5 relates to a technique for recirculating hydrogen and carbon monoxide from the tail gas of a synthesis gas treatment reactor to a Fischer-Tropsch reactor in at least one of Examples 1 to 4.

[0100] FIG. 5 is a configuration diagram of an improved Co-SOEC FTR hybrid system according to Example 5 of the present invention.

[0101] As shown in FIG. 5, the hybrid system of Example 5 includes a solid oxide co-electrolyzer (510), a synthesis gas treatment reactor (520), a Fischer-Tropsch reactor (530), a fuel separator (540), a heater (550), and a reverse water-gas conversion reactor (560).

[0102] The solid oxide co-electrolyzer (510), synthesis gas treatment reactor (520), Fischer-Tropsch reactor (530), fuel separator (540), and heater (550) of Example 5 are basically the same as the solid oxide co-electrolyzer (110), synthesis gas treatment reactor (120), Fischer-Tropsch reactor (130), fuel separator (140), and heater (150) of Example 1, so a redundant description is omitted.

[0103] The reverse water gas shift reactor (560) (RWGS) receives tail gas containing carbon dioxide, carbon monoxide, and hydrogen from the syngas treatment reactor (520). For reference, the syngas treatment reactor (520) can supply captured carbon dioxide to the reverse water gas shift reactor (560) as described above in Example 1.

[0104] Additionally, the gases mainly processed in the synthesis gas treatment reactor (520) are carbon monoxide and hydrogen, and some carbon dioxide, hydrogen, and carbon monoxide remain in an unreacted state and can be supplied to the reverse water gas conversion reactor (560) as tail gas.

[0105] The reverse water-gas conversion reactor (560) catalytically reacts hydrogen and carbon dioxide to produce carbon monoxide and water vapor.

[0106] The catalytic reaction of the reverse water-gas shift reactor (560) is as shown in Chemical Formula 5 below.

[0107] [Chemical Formula 5]

[0108] CO2 + H2 = CO + H2O

[0109] In the Pistropsch reactor (530), it is important that hydrogen and carbon monoxide are supplied in an optimal ratio (e.g., 2:1), but the synthesis gas produced directly from the solid oxide co-electrolyte cell (510) may not have the correct ratio of hydrogen to carbon monoxide.

[0110] By converting carbon dioxide into carbon monoxide and supplying it to the Fischer-Tropsch reactor (530) using the reverse water-gas conversion reactor (560), the Fischer-Tropsch reactor (130) can adjust the ratio of hydrogen to carbon monoxide, so that the Fischer-Tropsch reactor (530) can secure a high hydrocarbon yield. For reference, a small amount of oxygen supplied from the solid oxide co-electrolyzer (510) to the synthesis gas treatment reactor (520) may act as an oxidizing agent that promotes the reaction when reacting according to the above chemical formula 5.

[0111] Additionally, hydrogen contained in the tail gas of the synthesis gas treatment reactor (520) is consumed to convert carbon dioxide into carbon monoxide in the reverse water gas conversion reactor (560), and the generated carbon monoxide and unreacted hydrogen are recycled back to the Fischer-Tropsch reactor (530).

[0112] Meanwhile, the reaction in the reverse water-gas conversion reactor (560) proceeds efficiently at a high temperature.

[0113] For example, at high temperatures, the reverse water-gas shift reaction, which is an endothermic reaction, occurs more actively, whereas at low temperatures, the water-gas shift and methane reactions, which are exothermic reactions, become active. For this reason, in order to increase carbon monoxide selectivity, it is desirable to operate the reverse water-gas shift reactor (560) at a high temperature.

[0114] A heat supply is required to maintain the temperature of the reverse water-gas conversion reactor (560) appropriately. The reverse water-gas conversion reactor (560) can receive heat from a heater (550) that generates heat using the tail gas of the fuel separator (540) as fuel.

[0115] Although the present invention has been described above with reference to several embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0116] 110: Solid oxide electrolytic cell 120: Syngas treatment reactor 130: Fischer-Tropsch reactor 140: Fuel separator 150: Heater

Claims

Claim 1 An improved Co-SOEC FTR hybrid system comprising: a solid oxide co-electrolyzer (Co-SOEC) that electrolyzes water and carbon dioxide to produce synthesis gas containing hydrogen and carbon monoxide; a synthesis gas treatment reactor that removes unreacted carbon dioxide contained in the synthesis gas produced by the co-electrolyzer; a Fischer-Tropsch reactor that produces hydrocarbon synthetic crude oil using the synthesis gas containing hydrogen and carbon monoxide output from the synthesis gas treatment reactor; a fuel separator that reacts the hydrocarbons of the synthetic crude oil produced in the Fischer-Tropsch reactor to produce sustainable aviation fuel (e-SAF); and a heater that generates heat using the tail gas of the fuel separator as fuel and recirculates it to the fuel separator. Claim 2 An improved Co-SOEC FTR hybrid system according to claim 1, characterized in that at least 40% of the tail gas of the fuel separator is recirculated to the Fischer-Tropsch reactor. Claim 3 An improved Co-SOEC FTR hybrid system according to claim 1, characterized in that at least a portion of the unreacted carbon dioxide in the synthesis gas treatment reactor is recirculated as an input to the solid oxide co-electrolyte cell. Claim 4 An improved Co-SOEC FTR hybrid system according to claim 1, wherein the fuel separator includes a hydrogen separator and further includes a pressure swing adsorber (PSA) for capturing hydrogen from the tail gas of the hydrogen separator, and the captured hydrogen is recirculated to the hydrogen separator. Claim 5 A Co-SOEC FTR hybrid system according to claim 1, further comprising a reverse water gas shift reactor (RWGS) that receives a tail gas containing hydrogen, unreacted carbon dioxide, and carbon monoxide from the synthesis gas treatment reactor and catalytically reacts the hydrogen and carbon dioxide to produce carbon monoxide, wherein the produced carbon monoxide and hydrogen are recirculated to the Fischer-Tropsch reactor.

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