Method and apparatus for multi-zone reverse water gas shift conversion

Abstract

The invention relates to a process and an apparatus for producing synthesis gas by converting a feedstock containing CO2, wherein CO2 (4) is treated with H2 (5) in a RWGS reaction unit (6) to produce a RWGS gas (7), said RWGS reaction unit comprising: a heating zone (A) for heating CO2 and / or H2 and producing CO2 and H2 heated to at least 800°C; a distribution zone (B) for distributing a mixture comprising heated CO2 and H2 to a reaction zone (C); and a reaction zone (C) comprising a catalytic bed for converting CO2 and H2 into CO and H2O to produce synthesis gas.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for producing a synthesis gas (“synthesis gas”) mainly comprising carbon monoxide (CO) and optionally containing hydrogen (H2) by reacting a feed stream comprising carbon dioxide (CO2) and optionally carbon monoxide with a feed stream comprising hydrogen.

[0002] The syngas can then be used to produce very high-quality alcohols (essentially free of sulfur, aromatics, or nitrogen), especially methanol, or alkanes, such as synthetic fuels, i.e., gasoline, kerosene, gas oil, and / or other hydrocarbon products, such as naphtha, or lubricant base oils. Existing technology

[0003] The conversion of a mixture of carbon dioxide and hydrogen into syngas containing carbon monoxide and optionally H2 using the reverse water-gas shift (RWGS) process is known to those skilled in the art. During the RWGS reaction, carbon dioxide reacts with hydrogen to produce carbon monoxide and water. A mixture of carbon monoxide and hydrogen can be obtained by operating with excess hydrogen or by adding additional hydrogen at the reactor outlet so that, after water condensation, a mixture containing carbon monoxide, hydrogen, and optionally unconverted carbon dioxide is obtained.

[0004] The reverse water-gas shift reaction is a reversible and endothermic reaction that is accelerated at high temperatures. At thermodynamic equilibrium, the carbon dioxide conversion rate can reach 60% to 80% at temperatures between 800°C and 1000°C, depending on the pressure and H2 / CO2 ratio. Hydrogen can also react with carbon dioxide and / or carbon monoxide to form methane. These reactions are exothermic and therefore do not dominate at high temperatures, but are accelerated by high hydrogen partial pressures. These reactions, leading to methane formation, consume large amounts of hydrogen. When the goal is to produce syngas for synthetic fuels or methanol, it is desirable to limit the amount of methane present in the syngas to maximize the amount of liquid hydrocarbons synthesized. Therefore, selectivity for carbon monoxide is an important aspect of limiting methane formation and thus directing the consumed hydrogen towards carbon monoxide formation to maximize the production of liquid hydrocarbons.

[0005] Vazquez et al., in their paper *Journal of CO2 Utilization* 28 (2018), pp. 235-246, describe an RWGS unit associated with a Fischer-Tropsch synthesis unit. The CO2 source supplied to the RWGS unit is CO2 captured from the air. Hydrogen supplied to the RWGS unit is generated by the electrolysis of water and supplemental hydrogen stored in a gas cylinder. The hydrogen and CO2 are mixed and then preheated to 450°C before entering the RWGS reactor. The RWGS reactor contains a monolithic metal feedstock coated with a catalytic phase made of a noble metal. The reactor is externally heated to a maximum temperature of 850°C by an electric furnace system. The reactor is sized to accommodate a flow rate of 2 NL / min or 0.12 Nm. 3 The existing technology provides a CO2 flow rate of [value missing] / h and a diameter of 20 mm. This technology cannot design industrial-scale RWGS units capable of handling at least [value missing] Nm³ / h. 3 Larger diameter RWGS units with a gas flow rate of / h. Furthermore, when the CO2 and hydrogen mixture is heated to between 450°C and 850°C, products such as methane and CO are formed in the RWGS reactor, creating conditions favorable for metal dust corrosion. Invention Overview Against this background, the first objective of this specification is to overcome the problems of the prior art and to provide a method and apparatus for producing syngas from carbon dioxide and hydrogen, which can improve the quality of the produced syngas. The method and apparatus according to the invention can in particular reduce the amount of methane present in the syngas and limit metal dust formation. The apparatus and method according to the invention can also avoid catalyst fluidization in the catalytic bed of the reaction zone and improve conversion by ensuring a uniform concentration distribution.

[0007] According to the first aspect, the above-mentioned objective and other advantages are achieved by a method for producing counter-current gas shift gas via the conversion of a feedstock containing carbon dioxide, said method using an apparatus comprising the following elements: - A reverse-flow gas shift reaction unit adapted to process a carbon dioxide stream with a hydrogen stream and produce a reverse-flow gas shift gas (compared to a mixture of carbon dioxide and hydrogen streams) containing (enriched) carbon monoxide and water, the reverse-flow gas shift reaction unit comprising three successive zones with different functions: - Heating zone; - A distribution zone adapted to distribute a mixture comprising a heated carbon dioxide stream and a heated hydrogen stream into / into the reaction zone; and - A reaction zone comprising at least one catalytic bed adapted to convert at least a portion of carbon dioxide and hydrogen into carbon monoxide and water to produce reverse water gas shift gas. The method includes one of the following steps: - Heating a carbon dioxide stream and / or a hydrogen stream in a heating zone to produce: a heated carbon dioxide stream having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher (e.g., 1000°C or higher), and / or a heated hydrogen stream having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher (e.g., 1000°C or higher), provided that the carbon dioxide stream and the hydrogen stream are heated separately; or - A preheated mixture of carbon dioxide and hydrogen streams is heated in a heating zone to produce a heated mixture with a target temperature of 800°C or higher, preferably 900°C or higher, and preferably 950°C or higher (e.g., 1000°C or higher), provided that the temperature of the preheated mixture (i.e., before being heated in the heating zone) is at least 700°C.

[0008] According to one or more embodiments, the distribution zone is adapted to uniformly distribute a mixture comprising a heated carbon dioxide stream and a heated hydrogen stream into the reaction zone in terms of gas velocity (uniform distribution of the velocity vector over the flow area of ​​the reactor).

[0009] According to one or more embodiments, a preheated mixture of carbon dioxide and hydrogen streams is heated in a heating zone, the temperature of the preheated mixture being greater than or equal to 800°C, and a heated mixture having a target temperature of greater than or equal to 900°C, preferably greater than or equal to 950°C (e.g., greater than or equal to 1000°C) is produced.

[0010] According to one or more implementation schemes, electricity is used to supply the necessary heat energy to the reverse water gas conversion reaction unit.

[0011] According to one or more embodiments, the temperature of the carbon dioxide feed stream is between 700°C and 900°C, preferably between 760°C and 860°C. According to one or more embodiments, the temperature of the carbon dioxide feed stream is greater than or equal to 800°C.

[0012] According to one or more embodiments, the temperature of the hydrogen feed stream is between 700°C and 900°C, preferably between 760°C and 860°C. According to one or more embodiments, the temperature of the hydrogen feed stream is greater than or equal to 800°C.

[0013] According to one or more implementation schemes, the method includes: - The carbon dioxide source and / or hydrogen source are separately heated by heat exchange with the reverse water gas shift gas in the heat exchange section to produce a preheated carbon dioxide stream with a target temperature of 300°C or higher, preferably 400°C, preferably 500°C, preferably 600°C, preferably 700°C, preferably 750°C, and / or a preheated hydrogen stream with a target temperature of 300°C or higher, preferably 400°C, preferably 500°C, preferably 600°C, preferably 700°C, preferably 750°C.

[0014] According to one or more embodiments, the initial temperature of the carbon dioxide source is less than 300°C, preferably less than 250°C, more preferably less than 200°C, and / or the initial temperature of the hydrogen source is less than 300°C, preferably less than 200°C, more preferably less than 150°C.

[0015] According to one or more embodiments, the heating zone is adapted to mix a carbon dioxide stream with a hydrogen stream to produce a preheated mixture having a temperature of at least 700°C, preferably at least 800°C.

[0016] According to one or more embodiments, the distribution zone is adapted to mix a heated / preheated carbon dioxide stream with a heated hydrogen stream, or to mix a heated / preheated hydrogen stream with a heated carbon dioxide stream, to produce a heated mixture, and to feed the heated mixture into the reaction zone.

[0017] According to one or more embodiments, the heating zone is adapted to heat the CO-containing stream before or after mixing with the carbon dioxide stream and / or hydrogen stream, or the dispensing zone is adapted to mix the CO-containing stream with the heated carbon dioxide stream and / or the heated hydrogen stream or directly with the heated mixture.

[0018] According to one or more embodiments, the distribution zone includes at least a first chamber, the lower part of which is a cylinder having a height H-1 and a diameter D-1, containing at least one internal component adapted to uniformly circulate the gas at a velocity U-1 before it enters the reaction zone.

[0019] According to one or more implementation schemes, the first chamber of the allocation area is characterized by: - H-1 / D-1 is between 0.6 and 2.0, preferably between 1.0 and 1.6; - U-1 is between 1.0 m / s and 5.5 m / s, preferably between 3 m / s and 5 m / s; - There exists an inert solid particle layer exhibiting a minimum fluidization velocity Umf (predetermined), wherein the maximum gas velocity Umax at the surface of the inert solid particle layer is less than Umf.

[0020] According to one or more embodiments, the first chamber includes an upper part with a conical cross section such that the material flow inlet diameter Da-1 is adapted to the diameter D-1 of the lower part of the first chamber, Da-1 being smaller than D-1, wherein the cone is characterized in that the angle α relative to the material flow circulation direction Z (e.g., the vertical direction) is between 30° and 80°, preferably between 40° and 70°.

[0021] According to one or more embodiments, the distribution area performs a mixing function and includes a second chamber, the lower part of which is a basic cylinder with a height H-2 and a diameter D-2. The second chamber is located (directly) upstream of the first chamber. The carbon dioxide stream and the hydrogen stream enter the upper part of the second chamber through separate inlet pipes with diameters D-3 and D-4, respectively. The CO2 stream circulates at a speed U-3 and the hydrogen stream circulates at a speed U-4.

[0022] According to one or more implementation schemes, the allocation area is characterized by: - H-1 / D-1 is between 0.6 and 2.0, preferably between 1.0 and 1.6; - H-2 / D-2 is between 2.4 and 10, preferably between 4 and 8; - D-1 / D-2 is between 2.5 and 8.0, preferably between 2.5 and 5.0; - D-3 / D-4 is between 0.4 and 1.2, preferably between 0.6 and 1.1; - U-1 is between 1.0 m / s and 5.5 m / s, preferably between 3 m / s and 5 m / s; - U-3 is between 10 m / s and 60 m / s, preferably between 15 m / s and 55 m / s; - U-4 is between 20 m / s and 120 m / s, preferably between 40 m / s and 100 m / s; - There exists an inert solid particle layer exhibiting a minimum fluidization velocity Umf, wherein the maximum gas velocity Umax at the surface of the inert solid particle layer is less than Umf.

[0023] According to one or more embodiments, the inlet pipes for the carbon dioxide and hydrogen feed streams are inclined relative to the feed stream circulation direction Z.

[0024] According to one or more implementation schemes, the reaction zone is used under the following operating conditions: - at 2000 NL / kg cata / h to 40,000 NL / kgcata Gas space velocity at the reactor inlet between / h; - Catalysts based on elements Ni, Cu, Fe, Co, or noble metals such as Pt, Pd, Ru, Ag, and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises, for example, a support based on alumina, silica, silica-alumina, or siliceous alumina.

[0025] According to one or more embodiments, the catalyst is in the form of a ring or cylinder. Advantageously, the RWGS reaction unit comprises a catalytic bed capable of achieving a carbon dioxide conversion rate of at least 60%, preferably at least 65%, and more preferably at least 67%.

[0026] According to one or more embodiments, the heating zone, the dispensing zone and / or the reaction zone are adapted to be used at a pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, and more preferably between 0.1 MPa and 3.5 MPa.

[0027] According to the second aspect, the above-mentioned objectives and other advantages are achieved by an apparatus for producing countercurrent gas shift gas via the conversion of a feedstock containing carbon dioxide, said apparatus comprising a countercurrent gas shift reaction unit adapted to process a carbon dioxide feedstock with a hydrogen feedstock and produce (compared to a mixture of carbon dioxide and hydrogen feedstocks) a countercurrent gas shift gas containing (enriched) carbon monoxide and water, said countercurrent gas shift reaction unit comprising three successive zones with different functions: - A heating zone adapted to: heat a carbon dioxide stream and / or a hydrogen stream to produce: a heated carbon dioxide stream having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher (e.g., 1000°C or higher), and / or a heated hydrogen stream having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher (e.g., 1000°C or higher), provided that the carbon dioxide stream and the hydrogen stream are heated separately; or heat a preheated mixture of the carbon dioxide stream and the hydrogen stream to produce a heated mixture having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher (e.g., 1000°C or higher), provided that the temperature of the preheated mixture (i.e., before being heated by the heating zone) is at least 700°C. - A distribution zone adapted to distribute a mixture comprising a heated carbon dioxide stream and a heated hydrogen stream into / into the reaction zone; and - A reaction zone comprising at least one catalytic bed adapted to convert at least a portion of carbon dioxide and hydrogen into carbon monoxide and water to produce reverse water gas shift gas.

[0028] The embodiments of the methods and apparatus according to the foregoing aspects, as well as other features and advantages, will become apparent when reading the following description, which is provided only as a non-limiting example and with reference to the accompanying drawings. Brief description of the attached diagram Figure 1 The schematic diagram shows the apparatus according to the invention, which includes a heating zone A, a dispensing zone B, and a reaction zone C.

[0030] Figure 2 Schematic illustration of heat exchange section 3 Figure 1 device Figure 3 Schematic display based on Figure 2 The device, wherein heating zone A comprises two separate heating sections A1 and A2.

[0031] Figure 4 This schematic diagram illustrates the basis for handling a feed stream containing CO. Figure 2 The device.

[0032] Figure 5 This schematic diagram illustrates the basis for handling a feed stream containing CO. Figure 3 The device.

[0033] Figure 6 The distribution area B of the device according to the invention is schematically shown.

[0034] Description of the implementation plan Embodiments of the method according to the first aspect and the apparatus according to the second aspect will now be described in detail. Numerous specific details are disclosed in the following detailed description to provide a more thorough understanding of the method and the apparatus. However, it will be apparent to those skilled in the art that the method and the apparatus can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0035] In this specification, the term "comprising" is synonymous with "including" and "containing" (meaning the same) and is inclusive or open-ended, not excluding other elements not specified. Note that the verb "comprising" includes the exclusive and closed term "consisting of." Furthermore, in this specification, an effluent that substantially or solely comprises compound A corresponds to an effluent containing at least 95% by weight, preferably at least 98% by weight, and most preferably at least 99% by weight of compound A. In this specification, gas velocity refers to surface gas velocity.

[0036] This invention can be defined as a method and apparatus comprising a series of elements or operations to produce syngas, primarily composed of carbon monoxide (CO), via the conversion of carbon dioxide (CO2) in the presence of hydrogen (H2). In particular, the method and apparatus for producing syngas from carbon dioxide and hydrogen can guarantee the quality of the produced syngas. The method and apparatus according to the invention can especially reduce the amount of methane present in the syngas.

[0037] The methods and apparatus according to the invention are characterized in particular by the use of and inclusion of a reverse water gas shift (RWGS) unit and optionally one or more feed / effluent heat exchanger assemblies.

[0038] The required carbon dioxide can be supplied by a unit for separating a stream containing carbon dioxide (e.g., flue gas) or a unit for capturing carbon dioxide (e.g., carbon dioxide present in the air).

[0039] The hydrogen required for carbon dioxide conversion can be produced by a water electrolysis unit, the water of which can be derived from the effluent of the RWGS reactor and optionally from downstream units (e.g., Fischer-Tropsch (FT) or alcohol synthesis units). Preferably, using a water electrolysis unit to treat the water produced by the RWGS reactor also minimizes the environmental impact of the method. Therefore, the method according to the invention does not require an external supply of hydrogen, such as hydrogen produced by steam reforming of natural gas. The electrolyzer can preferably be operated with low-carbon electricity (e.g., solar or wind power, or even nuclear power), which helps to ensure a low environmental impact of the syngas and the hydrocarbons subsequently produced from it. Furthermore, the water used for hydrogen production can be derived at least partially from the recycling of water produced by the RWGS reaction, which has the advantage of limiting the external supply of water.

[0040] refer to Figure 1 According to the first and second aspects, the method and apparatus for producing syngas according to the invention use / include a reverse water gas shift reaction unit 6 (RWGS reaction unit), which is adapted to process a carbon dioxide stream 4 with a hydrogen stream 5 and produce an RWGS gas 7 containing carbon monoxide and water, particularly enriched with carbon monoxide and water compared to a mixture of carbon dioxide stream 4 and hydrogen stream 5, said reverse water gas shift reaction unit 6 comprising three successive zones with different functions: - Heating zone A; - Distribution zone B, adapted to distribute a mixture comprising a heated carbon dioxide stream and a heated hydrogen stream into, preferably uniformly in terms of gas velocity (uniform distribution of velocity vectors over the flow area of ​​the reactor) reaction zone C; and - Reaction zone C, which contains at least one catalytic bed adapted to convert at least a portion of carbon dioxide and hydrogen into carbon monoxide and water.

[0041] According to the present invention, heating zone A is adapted during the method to: - Heating carbon dioxide stream 4 and / or hydrogen stream 5 to produce a heated carbon dioxide stream having a target temperature of 800°C or higher, preferably 900°C or higher, more preferably 950°C (e.g., 1000°C or higher), and / or a heated hydrogen stream having a target temperature of 800°C or higher, preferably 900°C or higher, more preferably 950°C (e.g., 1000°C or higher), provided that carbon dioxide stream 4 and hydrogen stream 5 are heated separately; or - The preheated mixture of carbon dioxide stream 4 and hydrogen stream 5 is heated to produce a heated mixture with a target temperature of 800°C or higher, preferably 900°C or higher, and preferably 950°C or higher (e.g., 1000°C or higher), provided that the temperature of the preheated mixture (i.e., before being heated in heating zone A) is at least 700°C.

[0042] Preferably, when the preheated mixture of carbon dioxide stream 4 and hydrogen stream 5 is heated in heating zone A, the temperature of the preheated mixture is greater than or equal to 800°C, and a heated mixture with a target temperature of greater than or equal to 900°C, preferably greater than or equal to 950°C (e.g., greater than or equal to 1000°C) is produced.

[0043] The applicant has discovered that methane is formed when a mixture containing carbon dioxide and hydrogen is heated. Methane formation is promoted at temperatures below 700°C and catalyzed by nickel, a metallurgical material. Furthermore, the presence of methane in the temperature range of 400°C to 800°C induces metal dusting corrosion—for example, the degradation of iron- or nickel-based metal alloys into metal dust. Specifically, metal dusting is a significant localized loss of thickness, widespread or in the form of pitting corrosion, which leads to metal decomposition due to carbon diffusion into the metal by forming metal particles (dust) and carbides or coke on the surface.

[0044] The applicant has also discovered that the distribution zone B allows for the avoidance of catalyst fluidization in the catalyst bed of the reaction zone and improves conversion by ensuring a uniform distribution of concentration.

[0045] According to one or more embodiments, electricity, such as low-carbon electricity (e.g., solar or wind power, or even nuclear power), is used to supply the necessary thermal energy to the RWGS reaction unit 6, for example, to the heating zone A. The thermal energy can be supplied via resistors located in the area where the thermal energy needs to be supplied. Advantageously, the resistors can be in contact with or not in direct contact with the flow of gas circulating in that area. The metallurgy of the area in question can be adapted to the nature and temperature of the gaseous flow passing through said area.

[0046] According to one or more embodiments, the temperature of the carbon dioxide feed stream 4 (entering the RWGS reaction unit 6) is between 700°C and 900°C, preferably between 760°C and 860°C. According to one or more embodiments, the temperature of the carbon dioxide feed stream 4 (entering the RWGS reaction unit 6) is greater than or equal to 800°C.

[0047] According to one or more embodiments, the temperature of the hydrogen feed stream 5 (entering the RWGS reaction unit 6) is between 700°C and 900°C, preferably between 760°C and 860°C. According to one or more embodiments, the temperature of the hydrogen feed stream 5 (entering the RWGS reaction unit 6) is greater than or equal to 800°C.

[0048] Furthermore, heating zone A may optionally have the additional function of ensuring the mixing of reactants, i.e., the mixing of carbon dioxide stream 4 and hydrogen stream 5, to homogenize the concentration. According to one or more embodiments, heating zone A is adapted to mix carbon dioxide stream 4 and hydrogen stream 5 to produce a preheated mixture having a temperature of at least 700°C, and preferably at least 800°C, wherein carbon dioxide stream 4 and hydrogen stream 5 are preheated separately.

[0049] According to one or more embodiments, the target temperature of the heated carbon dioxide stream is between 800°C and 1100°C, preferably between 880°C and 1050°C, more preferably between 930°C and 1050°C, more preferably between 950°C and 1050°C, or between 980°C and 1050°C.

[0050] According to one or more embodiments, the target temperature of the heated hydrogen feed stream is between 800°C and 1100°C, preferably between 880°C and 1050°C, more preferably between 930°C and 1050°C, more preferably between 950°C and 1050°C, or between 980°C and 1050°C.

[0051] According to one or more embodiments, the target temperature of the heated mixture is between 800°C and 1200°C, preferably between 900°C and 1100°C, more preferably between 950°C and 1050°C, or between 980°C and 1050°C.

[0052] refer to Figure 2According to one or more embodiments, the method for producing syngas according to the invention uses an optional heat exchange section 3, which is adapted to separately heat carbon dioxide source 1 and / or hydrogen source 2 by heat exchange with reverse water-gas shift gas 7 (RWGS gas), and produce a preheated carbon dioxide stream 4 having a target temperature of greater than or equal to 300°C, preferably greater than or equal to 400°C, preferably greater than or equal to 500°C, preferably greater than or equal to 600°C, preferably greater than or equal to 700°C, preferably greater than or equal to 750°C, and / or a preheated hydrogen stream 5 having a target temperature of greater than or equal to 300°C, preferably greater than or equal to 400°C, preferably greater than or equal to 500°C, preferably greater than or equal to 600°C, preferably greater than or equal to 700°C, preferably greater than or equal to 750°C. Preferably, the heat exchange section 3 is arranged directly downstream of the RWGS reaction unit 6 (e.g., at the outlet).

[0053] According to one or more embodiments, the initial temperature of the carbon dioxide source 1 (e.g., upon entering the heat exchange section 3) is less than 300°C, preferably less than 250°C, and more preferably less than 200°C. According to one or more embodiments, the initial temperature of the carbon dioxide source 1 is between -50°C and 300°C, preferably between 0°C and 250°C, and more preferably between 0°C and 200°C.

[0054] According to one or more embodiments, the initial temperature of the hydrogen source 2 (e.g., when entering the heat exchange section 3) is less than 300°C, preferably less than 200°C, and more preferably less than 150°C. According to one or more embodiments, the initial temperature of the hydrogen source 2 is between 10°C and 300°C, preferably between 10°C and 200°C, and more preferably between 10°C and 150°C.

[0055] According to one or more embodiments, optional heat exchange section 3 includes one or more heat exchangers (e.g., a set of heat exchangers) adapted to separately heat each stream by heat exchange with RWGS gas 7, for example directly at the outlet of RWGS reaction unit 6, and produce cooled RWGS gas 8. According to one or more embodiments, the at least one heat exchanger is adapted to heat carbon dioxide source 1 and hydrogen source 2 in parallel. For example, RWGS gas 7 can be split into two streams, one stream heating carbon dioxide source 1 via one or more heat exchangers, and the other stream heating hydrogen source 2 via another one or more heat exchangers. According to one or more embodiments, the at least one heat exchanger includes at least one multiservice heat exchanger, i.e., heat exchangers adapted to heat at least two separate fluids in parallel. According to one or more embodiments, the at least one heat exchanger is adapted to heat carbon dioxide source 1 and hydrogen source 2 in series, for example, RWGS gas 7 heating carbon dioxide source 1 via one or more heat exchangers and then heating hydrogen source 2, or heating hydrogen source 2 and then heating carbon dioxide source 1. According to one or more embodiments, the at least one heat exchanger includes at least one plate heat exchanger or shell-and-tube heat exchanger.

[0056] According to one or more embodiments, the temperature of the RWGS gas 7 as it exits the RWGS reaction unit 6 (e.g., below the target temperature of the heated mixture containing the carbon dioxide and hydrogen streams) is at least 700°C, preferably at least 750°C, very preferably at least 800°C, for example, between 800°C and 1050°C, preferably between 800°C and 1000°C, and most preferably between 800°C and 900°C. According to one or more embodiments, the temperature difference between the heated mixture on one hand and the RWGS gas 7 on the other hand is at least 10°C, preferably at least 40°C, very preferably at least 50°C, for example, between 50°C and 200°C, preferably between 60°C and 195°C, and most preferably between 80°C and 190°C. It should be recognized that the temperature of the gas entering the RWGS reaction unit 6 is greater than the temperature of the RWGS gas 7.

[0057] It should be understood in this application that although carbon dioxide source 1 and / or hydrogen source 2 are preferably preheated by RWGS gas 7 produced by RWGS reaction unit 6, carbon dioxide source 1 and / or hydrogen source 2 can be preheated by any means known to those skilled in the art. For example, according to one or more embodiments, the method for producing syngas according to the invention uses at least one heating system, such as a furnace (not shown in the figures), adapted to separately heat carbon dioxide source 1 and / or hydrogen source 2, and produce a preheated carbon dioxide stream 4 having a target temperature greater than or equal to 700°C, preferably greater than or equal to 750°C, and / or a preheated hydrogen stream 5 having a target temperature greater than or equal to 700°C, preferably greater than or equal to 750°C. Preferably, this heating system is arranged directly upstream of RWGS reaction unit 6 (e.g., at the inlet).

[0058] According to one or more embodiments, the heating system is at least partially powered by electricity. According to one or more embodiments, the heating system is at least partially powered by fuel. According to one or more embodiments, the heating system is powered by a mixture of electricity and fuel. Preferably, the heating system is substantially or entirely powered by electricity.

[0059] Advantageously, existing electric furnace or electric heating system technology makes it possible to achieve preheating temperatures. According to one or more embodiments, the electric heating system is tubular (technology), with each stream of material to be heated circulating in one or more tubes, which can be heated by a resistor system or by impedance. According to one or more embodiments, the electric heating system consists of resistors immersed in the stream of material to be heated. According to one or more embodiments, heat energy is supplied by impedance, and each stream then circulates in one or more metal tubes. According to one or more other embodiments, heat energy is supplied by means of resistors, which may be immersed in the stream (which circulates in one or more tubes made of a material adapted to the chemical composition and temperature of the stream), or may not be in direct contact, and the stream then circulates in the metal tubes. The metallurgy of the metal tubes can be adapted to the properties of the stream of material to be heated and the target temperature.

[0060] In the case of a furnace that is at least partially powered by fuel, it is preferable to supply the furnace with an oxygen source (air and / or oxygen generated by the electrolyzer) and at least one of the following fuels: - Gaseous hydrocarbon effluents (“exhaust gases”), such as effluents from the FT unit processing RWGS gas 7 or from units that hydrocracking, hydrotreating, or hydroisomerizing alkanes produced by the FT unit, or effluents from methanol synthesis units; and / or - Hydrogen gas, for example, produced by an electrolyzer.

[0061] According to one or more embodiments, the hydrocarbon exhaust gas contains at least one of the following components: unconverted RWGS gas 7, carbon dioxide, gaseous hydrocarbons such as C1-C4 alkanes, C2-C4 olefins, and / or C1-C3 oxygenated compounds. According to one or more embodiments, when the hydrocarbon exhaust gas is supplied to the furnace, the furnace is a partial oxidation unit, which specifically enables the production of an effluent rich in carbon monoxide, preferably consisting substantially of carbon monoxide, and possibly containing carbon dioxide, hydrogen, and water.

[0062] refer to Figure 3 According to one or more embodiments, heating zone A comprises two separate heating sections A1 and A2 (i.e., no flow from one section to the other), section A1 being adapted to increase the temperature of the carbon dioxide-rich feed stream 4, and section A2 being adapted to increase the temperature of the hydrogen feed stream 5. According to one or more embodiments, heating zone A is adapted to separately heat the carbon dioxide feed stream 4 and the hydrogen feed stream 5, and to separately feed the heated carbon dioxide feed stream 4 and the heated hydrogen feed stream 5 into distribution zone B.

[0063] Distribution zone B may optionally have the additional function of ensuring the mixing of reactants, i.e., the mixing of a heated carbon dioxide stream with a heated / preheated hydrogen stream, or the mixing of a heated hydrogen stream with a heated / preheated carbon dioxide stream, to homogenize the concentration. According to one or more embodiments, distribution zone B is adapted to mix the heated carbon dioxide stream with the heated hydrogen stream to produce a heated mixture, uniformly distribute the heated mixture in terms of gas velocity, and feed the heated mixture into reaction zone C. Advantageously, by mixing the thus heated / preheated carbon dioxide stream and hydrogen stream to form a heated mixture with a target temperature of at least 800°C, methane production and metal dust formation are further limited.

[0064] According to one or more embodiments, the RWGS conversion reaction unit 6 is adapted to process a feed stream 9 containing CO. (Reference) Figure 4 According to one or more embodiments, heating zone A is adapted to heat the CO-containing stream 9 before or after mixing it with the carbon dioxide stream 4 and the hydrogen stream 5. Alternatively, according to one or more embodiments, distribution zone B is adapted to mix the CO-containing stream 9 (see dashed arrow) with a heated mixture containing the carbon dioxide stream and the hydrogen stream, and then uniformly distribute the new heated mixture (containing CO2, CO and H2) into reaction zone C in terms of gas velocity.

[0065] refer to Figure 5 According to one or more embodiments, section A1 of heating zone A is suitable for: - Heat the CO-containing feed stream 9 and mix the CO-containing feed stream 9 with the carbon dioxide feed stream 4, or - Heat the carbon dioxide stream 4 and mix the carbon dioxide stream 4 with the CO-containing stream 9, or - Mix the carbon dioxide stream 4 with the CO-containing stream 9 and heat the CO-CO2 mixture.

[0066] Alternatively, according to one or more embodiments, distribution zone B is adapted to mix a CO-containing stream 9 (see dashed arrow) with a heated carbon dioxide stream and (then) also with a heated hydrogen stream, and then uniformly distribute the new heated mixture (containing CO2, CO and H2) into reaction zone C in terms of gas velocity.

[0067] According to one or more embodiments, heating zone A is adapted to circulate carbon dioxide stream 4 and / or hydrogen stream 5 at a Reynolds number greater than 3000.

[0068] refer to Figure 6 According to one or more embodiments, uniform distribution of the heated mixture in distribution zone B in terms of gas velocity is achieved by a first chamber B1, the lower part of which (the downstream portion relative to the circulation direction of the heated mixture) is a basic cylinder with a height H-1 and a diameter D-1, containing at least one internal component suitable for uniformizing the gas velocity before the gas enters reaction zone C, such as at least one layer of inert solid particles (grading) such as ceramic particles, and / or elements, such as packing elements. The surface gas velocity in the first chamber B1 is U-1. Preferably, when using at least one grading layer, the maximum gas velocity Umax at the surface of the grading is less than the minimum fluidization velocity Umf of the grading, Umf being a characteristic of the grading known to those skilled in the art, and U-1 is less than Umax. According to one or more embodiments, distribution zone B is characterized in that: - H-1 is between 0.1 m and 20 m, preferably between 0.5 m and 13 m; - D-1 is between 0.2 m and 10 m, preferably between 0.5 m and 8 m; - H-1 / D-1 is between 0.6 and 2.0, preferably between 1.0 and 1.6; - U-1 is between 1.0 m / s and 5.5 m / s, preferably between 3 m / s and 5 m / s; - Umax / Umf is less than 1.

[0069] Optionally, the first chamber B1 includes an upper portion of a conical cross-section (upstream of the circulation direction of the heated mixture from heating zone A) such that the (smaller) feed inlet diameter Da-1 is adapted to the (larger) diameter D-1 of the lower portion of the first chamber. Preferably, the cone is characterized by an angle α (relative to the circulation direction Z of the heated mixture, i.e., substantially relative to the vertical direction) between 30° and 80°, preferably between 40° and 70°.

[0070] According to one or more embodiments, in the distribution zone B, where mixing of reactants is ensured, it comprises a second chamber B2 having a height H-2 and a diameter D-2, at least its lower portion (downstream of the circulation direction of the feed streams to be mixed from heating zone A) being substantially cylindrical (with a diameter D-2), and the second chamber B2 being located (directly) upstream of the first chamber B1. Heated / preheated carbon dioxide and heated / preheated hydrogen feed streams enter the upper portion of the second chamber B2 (upstream of the circulation direction of the feed streams to be mixed) via separate inlet pipes B3 and B4 with diameters D-3 and D-4, respectively, with the CO2 feed stream circulating at a surface velocity U-3 and the hydrogen feed stream circulating at a surface velocity U-4. According to one or more embodiments, the diameter D-2 corresponds to the diameter Da-1. According to one or more embodiments, the upper portion of chamber B2 is adapted to ensure connection with the inlet pipes B3 and B4 of the carbon dioxide and hydrogen feed streams. According to one or more embodiments, the inlet pipes B3 and B4 for the carbon dioxide and hydrogen feed streams are inclined relative to the feed stream circulation direction Z, preferably at an angle β between 10° and 90°, and more preferably between 20° and 60°, relative to the feed stream circulation direction Z.

[0071] According to one or more implementation schemes, allocation area B is characterized by: - H-1 is between 0.1 m and 20 m, preferably between 0.5 m and 13 m; - D-1 is between 0.2 m and 10 m, preferably between 0.5 m and 8 m; - H-2 is between 0.05 m and 30 m, preferably between 0.4 m and 18 m; - D-2 is between 0.04 m and 4 m, preferably between 0.1 m and 3 m; - D-3 is between 0.04 m and 1.9 m, preferably between 0.05 m and 1.3 m; - D-4 is between 0.04 m and 1.6 m, preferably between 0.05 m and 1.2 m; - H-1 / D-1 is between 0.6 and 2.0, preferably between 1.0 and 1.6; - H-2 / D-2 is between 2.4 and 8, preferably between 4 and 6; - D-1 / D-2 is between 2.5 and 8.0, preferably between 2.5 and 5.0; - D-3 / D-4 is between 0.4 and 1.2, preferably between 0.6 and 1.1; - U-3 is between 10 m / s and 60 m / s, preferably between 15 m / s and 55 m / s; - U-4 is between 20 m / s and 120 m / s, preferably between 40 m / s and 100 m / s; - U-1 is between 1.0 m / s and 5.5 m / s, preferably between 3 m / s and 5 m / s; - Umax / Umf is less than 1.

[0072] Advantageously, homogenizing the gas velocity prevents catalyst fluidization in the catalytic bed of reaction zone C, while ensuring a uniform distribution of gas velocity and concentration. Homogenization of the gas velocity field is characterized by a homogenization index lU-v greater than 95%, preferably greater than 97%, and more preferably greater than 98%. Homogenization of the concentration is characterized by a homogenization index lU-c greater than 95%, preferably greater than 97%, more preferably greater than 98%, and more preferably greater than 99%.

[0073] According to one or more embodiments, reaction zone C is suitable for use under the following operating conditions: - at 2000 NL / kg cata / h to 40,000 NL / kg cata Gas space velocity at the reactor inlet between / h; - Catalysts based on elements Ni, Cu, Fe, Co, or noble metals such as Pt, Pd, Ru, Ag, and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises, for example, a support based on alumina, silica, silica-alumina, or siliceous alumina. According to one or more embodiments, the catalyst is in ring or cylindrical form. Advantageously, the RWGS reaction unit 6 comprises a catalytic bed capable of achieving a carbon dioxide conversion rate of at least 60%, preferably at least 65%, and most preferably at least 67%.

[0074] According to one or more embodiments, the heating zone A, the distribution zone B and / or the reaction zone C are adapted to be used at a pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, and more preferably between 0.1 MPa and 3.5 MPa.

[0075] According to one or more embodiments, heating zone A, distribution zone B, and / or reaction zone C form an adiabatic reactor. Advantageously, low or even no heat loss in the adiabatic reactor is ensured by any insulation means known to those skilled in the art. For example, the adiabatic reactor can be insulated externally via the metal walls of the adiabatic reactor, and in this case, the metal walls are made of metallurgically resistant to temperature and gases containing CO, hydrogen, and water, and may be covered with a coating that resists coking and metal dusting (e.g., a <1 mm layer based on Al, Cr, or Si, which is subsequently oxidized in situ to form an Al2O3 layer). For example, the adiabatic reactor can also be insulated internally via the metal walls of the adiabatic reactor using one or more insulating materials.

[0076] According to one or more embodiments, the amount of hydrogen at the inlet of RWGS reaction unit 6 is adjusted such that the H2 / CO molar ratio at the outlet of RWGS reaction unit 6 is compatible with the requirements of the downstream FT unit (not shown in the figures) or alcohol synthesis unit (not shown in the figures). According to one or more embodiments, the amount of hydrogen at the inlet of RWGS reaction unit 6 is controlled such that the H2 / CO molar ratio in the RWGS gas 7 at the outlet of RWGS reaction unit 6 is between 0.5 and 4, preferably between 1 and 3, and more preferably between 1.5 and 2.5.

[0077] According to one or more embodiments, a portion of the hydrogen required for FT synthesis or alcohol synthesis can be supplied downstream of RWGS reaction unit 6, for example, by mixing a supplementary hydrogen source with RWGS gas 7 or cooled RWGS gas 8, respectively, upstream or downstream of heat exchange section 3. For example, hydrogen can be added downstream of a water separation unit (defined below) suitable for separating water contained in RWGS gas 7 or cooled RWGS gas 8. Preferably, hydrogen is added upstream of the reaction unit producing alkanes (FT synthesis) or alcohols.

[0078] According to one or more embodiments, RWGS gas 7 or cooled RWGS gas 8, preferably cooled RWGS gas 8, is fed into a water separation unit (not shown in the figures) to at least partially or completely separate the water present in the RWGS gas and produce water-lean RWGS gas. Advantageously, the water-lean RWGS gas essentially contains carbon monoxide, optionally (residual) carbon dioxide, and optionally hydrogen (when hydrogen is in excess). For example, the RWGS gas can be cooled to a condensation temperature to condense the water present in the RWGS gas.

[0079] According to one or more embodiments, a water electrolysis unit (not shown in the figures) at least partially treats water separated from water-poor RWGS gas and / or from the effluent of downstream units (e.g., for the production of alkanes or alcohols) to at least partially produce hydrogen source 2. The water electrolysis unit may optionally treat a portion or all of the water from the makeup line.

[0080] According to one or more embodiments, the water electrolysis unit includes at least one alkaline electrolyzer. Other electrolyzer technologies can be used in the water electrolysis unit, such as proton exchange membrane (PEM) electrolysis, solid oxide electrolysis (SOE) electrolysis, or anion exchange membrane (AEM) electrolysis. Operating conditions (temperature, pressure, electrolyte, electrode and diaphragm / membrane properties) are therefore specific to each technology.

[0081] According to one or more embodiments, the water electrolysis unit comprises at least one reactor used under at least one of the following operating conditions: Alkaline electrolytic cell: - At temperatures between 60°C and 90°C - The pressure is between 0.1 MPa and 20 MPa, preferably between 0.1 MPa and 4 MPa. - Electrolytes containing KOH - Electrodes containing metal alloys, - A membrane containing asbestos, polytetrafluoroethylene and / or nickel oxide; Proton exchange membrane (PEM) electrolyzer: - At temperatures between 50°C and 80°C - Pressure between 0.1 MPa and 20 MPa, preferably between 1.8 MPa and 5.5 MPa. - Electrolytes containing polymer membranes, - Electrodes containing metal alloys; Solid oxide electrolyzer (SOE): - At temperatures between 800℃ and 900℃ - The pressure is between 0.1 MPa and 2 MPa, preferably between 0.1 MPa and 0.5 MPa. - Electrolytes containing ceramic (e.g., perovskite) membranes, - Electrodes containing metal alloys; Anion exchange membrane (AEM) electrolyzer: - At temperatures between 50°C and 70°C - The pressure is between 0.1 MPa and 20 MPa, preferably between 0.1 MPa and 3.5 MPa. - Electrolytes containing polymer membranes, - Electrodes containing metal alloys.

[0082] According to one or more embodiments, the hydrogen source 2 generated by the water electrolysis unit contains between 99.5% by weight and 99.999% by weight of hydrogen (after drying).

[0083] According to one or more embodiments, carbon dioxide source 1 is purified before being introduced into RWGS reaction unit 6. According to one or more embodiments, carbon dioxide source 1 is purified in heat exchange section 3. Carbon dioxide source 1 may also be purified before or after being introduced into heat exchange section 3. However, when using a furnace, carbon dioxide source 1 is preferably purified before being introduced into the furnace.

[0084] According to one or more embodiments, the RWGS gas 7 is purified upstream or downstream of a water separation unit, for example, arranged between the RWGS reaction unit 6 and the alkane or alcohol synthesis reaction unit, before being introduced into the alkane or alcohol synthesis reaction unit. According to one or more embodiments, the water effluent recovered by separation from the RWGS gas 7 is purified before being introduced into a water electrolysis unit.

[0085] The effluent purification process aims to remove at least some of the sulfur and nitrogen compounds, halogens, heavy metals, and transition metals. The main techniques used for gas purification are adsorption, absorption, and catalytic reactions. Example

[0086] Examples 1A to 1E in Table 1 below are embodiments of a method for producing syngas according to the present invention, which uses a counter-current water gas shift reaction unit (6) comprising three successive zones with different functions: - Heating zone (A), which is used to heat the preheated carbon dioxide stream (4) and the preheated hydrogen stream (5) to produce a mixture containing carbon dioxide and hydrogen heated to a temperature of 1000°C. - A distribution zone (B) adapted to uniformly distribute the mixture into the reaction zone (C) in terms of gas velocity; and - Reaction zone (C), which contains a catalytic bed suitable for converting at least a portion of carbon dioxide and hydrogen into carbon monoxide and water.

[0087] Specifically, Examples 1D and 1E in Table 1 are given to illustrate examples of how the parameters of the distribution zone B can be improved to improve the gas velocity homogenization standard.

[0088] - Example 1D: Example 1A with grading, improving gas velocity uniformity; - Example 1E: Example 1B with graded materials, improving gas velocity uniformity; - Example 1D: H-1 / D-1 is an example 1C within the preferred range, reducing fluidization problems in graded materials; Table 1 Example 1A 1B 1C 1D 1E <![CDATA[Q (m 3 / h)]]> 45000 135000 45000 45000 135000 U-1 (m / s) 4.0 4.0 4.0 4.0 4.0 H-1 / D-1 1.00 0.89 0.50 1.00 0.89 Graded ingredients none none yes yes yes Umax / Umf N / A N / A 1.03 0.87 0.75 IU-v (%) 88.7 92.2 98.8 99.3 99.0

[0089] Examples 2A to 2H in Table 2 below are embodiments of the method for producing syngas according to the present invention, which uses a counter-current water gas shift reaction unit (6) containing three successive zones with different functions: - Heating zone (A), which is used to heat the preheated carbon dioxide stream (4) and the preheated hydrogen stream (5) to produce a carbon dioxide stream heated to a temperature of 1000°C and a hydrogen stream heated to a temperature of 1000°C. - A distribution zone (B) adapted to mix the heated carbon dioxide stream with the heated hydrogen stream and to uniformly distribute the mixture in terms of gas velocity into the reaction zone (C); and - Reaction zone (C), which contains a catalytic bed suitable for converting at least a portion of carbon dioxide and hydrogen into carbon monoxide and water.

[0090] Specifically, Examples 2F, 2G, and 2H in Table 2 are given to illustrate examples of distribution zone B parameters that can improve the concentration and gas velocity homogenization criteria.

[0091] - Example 2F: Example 2A with graded materials, improving gas velocity uniformity; - Example 2G: Example 2B with graded materials, improving gas velocity uniformity; - Example 2H: H-1 / D-1 is an example 2C within the preferred range, reducing fluidization problems of graded materials; - Example 2F: H-2 / D-2 and D-1 / D-2 are within the preferred range of Example 2D, reducing fluidization problems of graded materials and improving concentration and gas velocity uniformity; - Example 2H: D-3 / D-4 is an example 2E within the preferred range, which reduces fluidization problems of graded materials and improves the uniformity of concentration and gas velocity.

[0092] Table 2 Example 2A 2B 2C 2D 2E 2F 2G 2H <![CDATA[Q (m 3 / h)]]> 45000 135000 45000 45000 45000 45000 135000 45000 U-1 (m / s) 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 U-4 (m / s) 50 100 100 50 100 50 100 100 H-1 / D-1 1.00 0.89 0.50 1.00 1.00 1.00 0.89 1.00 H-2 / D-2 4.4 4.4 4.4 1.9 4.4 4.4 4.4 4.4 D-1 / D-2 3.3 3.4 3.3 1.4 3.3 3.3 3.4 3.3 D-3 / D-4 0.5 1.0 1.0 0.5 1.4 0.5 1.0 1.0 Graded ingredients none none yes yes yes yes yes yes Umax / Umf N / A N / A 1.03 1.50 1.06 0.87 0.75 0.87 IU-v (%) 88.7 92.2 98.8 99.1 94.7 99.3 99.0 99.6 IU-c (%) 99.1 99.0 98.6 99.2 93.4 99.5 99.1 99.5

Claims

1. A method for producing counter-current gas shift gas via the conversion of a carbon dioxide-containing feedstock, using an apparatus comprising the following elements: - A reverse-flow gas shift reaction unit (6) adapted to process a carbon dioxide stream (4) with a hydrogen stream (5) and produce a reverse-flow gas shift gas (7) containing carbon monoxide and water, the reverse-flow gas shift reaction unit (6) comprising three successive zones with different functions: • Heating zone (A); • Distribution zone (B), adapted to distribute a mixture comprising a heated carbon dioxide stream and a heated hydrogen stream to the reaction zone (C); and • Reaction zone (C) containing at least one catalyst bed adapted to convert at least a portion of carbon dioxide and hydrogen into carbon monoxide and water to produce reverse water gas shift gas (7); The method includes one of the following steps: - The carbon dioxide stream (4) and / or the hydrogen stream (5) are heated in the heating zone (A) to produce: a heated carbon dioxide stream having a target temperature greater than or equal to 800°C, preferably greater than or equal to 900°C, preferably greater than or equal to 950°C, and / or a heated hydrogen stream having a target temperature greater than or equal to 800°C, preferably greater than or equal to 900°C, preferably greater than or equal to 950°C, provided that the carbon dioxide stream (4) and the hydrogen stream (5) are heated separately; or - The preheated mixture of carbon dioxide stream (4) and hydrogen stream (5) is heated in the heating zone (A) to produce a heated mixture having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher, provided that the temperature of the preheated mixture is at least 700°C.

2. The method according to claim 1, wherein a preheated mixture of carbon dioxide stream (4) and hydrogen stream (5) is heated in the heating zone (A), the temperature of the preheated mixture being greater than or equal to 800°C, and a heated mixture having a target temperature of greater than or equal to 900°C, preferably greater than or equal to 950°C, is produced.

3. The method according to claim 1 or claim 2, comprising: - The carbon dioxide source (1) and / or hydrogen source (2) are heated separately by heat exchange with the reverse water gas shift gas (7) in the heat exchange section (3) to produce a preheated carbon dioxide stream (4) with a target temperature of greater than or equal to 300°C, preferably greater than or equal to 400°C, preferably greater than or equal to 500°C, preferably greater than or equal to 600°C, preferably greater than or equal to 700°C, preferably greater than or equal to 750°C, and / or a preheated hydrogen stream (5) with a target temperature of greater than or equal to 300°C, preferably greater than or equal to 400°C, preferably greater than or equal to 500°C, preferably greater than or equal to 600°C, preferably greater than or equal to 700°C, preferably greater than or equal to 750°C.

4. The method according to any one of the preceding claims, wherein the heating zone (A) is adapted to mix the carbon dioxide stream (4) with the hydrogen stream (5) to produce a preheated mixture having a temperature of at least 700°C, and preferably at least 800°C.

5. The method according to any one of claims 1 to 3, wherein the distribution zone (B) is adapted to mix the heated carbon dioxide stream with the heated hydrogen stream, or to mix the heated hydrogen stream with the heated carbon dioxide stream, to produce a heated mixture, and to feed the heated mixture into the reaction zone (C).

6. The method according to any one of the preceding claims, wherein the heating zone (A) is adapted to heat the CO-containing stream (9) before or after mixing with the carbon dioxide stream (4) and / or the hydrogen stream (5), or wherein the dispensing zone (B) is adapted to mix the CO-containing stream (9) with the heated carbon dioxide stream and / or the heated hydrogen stream or directly with the heated mixture.

7. The method according to any one of the preceding claims, wherein the distribution zone (B) comprises at least a first chamber (B1) having a lower portion that is cylindrical with a height H-1 and a diameter D-1, and contains at least one internal component adapted to uniformly velocity of the gas before it enters the reaction zone (C), the gas circulating at a velocity U-1.

8. The method according to claim 7, wherein the first chamber (B1) of the distribution area (B) is characterized in that: - H-1 / D-1 is between 0.6 and 2.0, preferably between 1.0 and 1.6; - U-1 is between 1.0 m / s and 5.5 m / s, preferably between 3 m / s and 5 m / s; - There exists an inert solid particle layer exhibiting a minimum fluidization velocity Umf, wherein the maximum gas velocity Umax at the surface of the inert solid particle layer is less than Umf.

9. The method according to claim 7 or claim 8, wherein the first chamber (B1) comprises an upper portion of a conical cross-section such that the material flow inlet diameter Da-1 is adapted to the diameter D-1 of the lower portion of the first chamber (B1), Da-1 being smaller than D-1, wherein the cone is characterized in that the angle α relative to the material flow circulation direction Z is between 30° and 80°, preferably between 40° and 70°.

10. The method according to any one of claims 7 to 9, wherein the dispensing zone (B) performs a mixing function and includes a second chamber (B2) having a lower portion that is a basic cylinder having a height H-2 and a diameter D-2, the second chamber (B2) being located upstream of the first chamber (B1), wherein a carbon dioxide stream and a hydrogen stream enter the upper portion of the second chamber (B2) through separate inlet pipes (B3, B4) with diameters D-3 and D-4, respectively, the CO2 stream circulating at a speed U-3 and the hydrogen stream circulating at a speed U-4.

11. The method according to claim 10, wherein the allocation region (B) is characterized in that: - H-1 / D-1 is between 0.6 and 2.0, preferably between 1.0 and 1.6; - H-2 / D-2 is between 2.4 and 10, preferably between 4 and 8; - D-1 / D-2 is between 2.5 and 8.0, preferably between 2.5 and 5.0; - D-3 / D-4 is between 0.4 and 1.2, preferably between 0.6 and 1.1; - U-1 is between 1.0 m / s and 5.5 m / s, preferably between 3 m / s and 5 m / s; - U-3 is between 10 m / s and 60 m / s, preferably between 15 m / s and 55 m / s; - U-4 is between 20 m / s and 120 m / s, preferably between 40 m / s and 100 m / s; - There exists an inert solid particle layer exhibiting a minimum fluidization velocity Umf, wherein the maximum gas velocity Umax at the surface of the inert solid particle layer is less than Umf.

12. The method according to claim 10 or claim 11, wherein the inlet pipes (B3, B4) of the carbon dioxide stream and the hydrogen stream are inclined relative to the stream circulation direction Z.

13. The method according to any one of the preceding claims, wherein the reaction zone (C) is operated under the following conditions: - at 2000 NL / kg cata / h to 40,000 NL / kg cata Gas space velocity at the reactor inlet between / h; Catalysts based on elements Ni, Cu, Fe, Co or noble metals such as Pt, Pd, Ru, Ag and Au.

14. The method according to any one of the preceding claims, wherein electricity is used to supply the necessary thermal energy to the reverse water gas conversion reaction unit (6).

15. An apparatus for producing countercurrent gas shift gas via the conversion of a feedstock containing carbon dioxide, comprising the following components: - A reverse-flow gas shift reaction unit (6) adapted to process a carbon dioxide stream (4) with a hydrogen stream (5) and produce a reverse-flow gas shift gas (7) containing carbon monoxide and water, the reverse-flow gas shift reaction unit (6) comprising three successive zones with different functions: - Heating zone (A), which is suitable for: Heating the carbon dioxide stream (4) and / or the hydrogen stream (5) to produce: a heated carbon dioxide stream having a target temperature greater than or equal to 800°C, preferably greater than or equal to 900°C, preferably greater than or equal to 950°C, and / or a heated hydrogen stream having a target temperature greater than or equal to 800°C, preferably greater than or equal to 900°C, preferably greater than or equal to 950°C, provided that the carbon dioxide stream (4) and the hydrogen stream (5) are heated separately; or • The preheated mixture of carbon dioxide stream (4) and hydrogen stream (5) is heated to produce a heated mixture having a target temperature of 800°C or higher, preferably 900°C or higher, preferably 950°C or higher, provided that the temperature of the preheated mixture is at least 700°C. - Distribution zone (B), adapted to distribute a mixture comprising a heated carbon dioxide stream and a heated hydrogen stream to the reaction zone (C); and - Reaction zone (C) comprising at least one catalyst bed adapted to convert at least a portion of carbon dioxide and hydrogen into carbon monoxide and water to produce reverse water gas shift gas (7).

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