Conversion of CO2 and H2 to Syngas

Abstract

The present invention relates to A reverse water gas shift (RWGS) section, a first hydrogen-containing feed to the RWGS section and a second carbon dioxide-containing feed to the RWGS section; or a combined feed to the e-RWGS section comprising hydrogen and carbon dioxide; A reverse water gas shift (RWGS) section, including: a water removal section downstream of said RWGS section; a compressor downstream of the water removal section; and a cryogenic CO2 separation section downstream of said compressor; A plant comprising: the RWGS section is configured to convert the first feed and the second feed, or the combined feed, into a first syngas stream and to supply the first syngas stream to the water removal section; the water removal section is configured to remove water from the first syngas stream to produce a dehydrated syngas stream and a water condensate; the compressor is positioned to compress the dehydrated syngas stream to produce a compressed syngas stream; the cryogenic CO2 separation section is configured to separate the compressed syngas stream into a CO2-depleted syngas stream and a CO2-rich condensate; The plant has means for recycling at least a portion of the CO2-rich condensate to the RWGS section or to the feed to the RWGS section; and The RWGS section is an electrically heated RWGS (e-RWGS) section. Regarding the plant.

Description

[Technical field]

[0001] The present invention relates to a syngas production plant that includes efficient use of various streams, particularly carbon dioxide. A method for producing a syngas stream is also provided. The plant and method of the present invention provide an overall better utilization of carbon dioxide. [Background technology]

[0002] Carbon capture and utilization (CCU) is gaining greater significance in light of the rise in atmospheric CO2 since the Industrial Revolution. In one method of utilizing CO2, CO2 and H2 can be converted into synthesis gas (a gas rich in CO and H2), which can be further converted into valuable products such as alcohols (including methanol), fuels (e.g., gasoline, jet fuel, kerosene, and / or diesel produced by the Fischer-Tropsch (FT) process), and / or olefins.

[0003] Existing technology has primarily focused on stand-alone reverse water gas shift (RWGS) processes to convert CO2 and H2 into synthesis gas. The synthesis gas can then be converted into valuable products in downstream processes as described above. The reverse water gas shift reaction proceeds according to the following reactions: CO2(g)+H2(g) <-> CO(g)+H2O(g) (1) The RWGS reaction (1) is endothermic and requires a large energy input for the desired conversion. To make the process economically viable, high temperatures are required to obtain sufficient conversion of carbon dioxide to carbon monoxide. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Cybulski, A., and Moulijn, JA, Structured catalysts and reactors, Marcel Dekker, Inc, New York, 1998, Chapter 3 [Non-Patent Document 2] Studies in Surface Science and Catalysis,Vol.152 [Non-Patent Document 3] Synthesis gas production for FT synthesis”; Chapter 4,p.258-352,2004 Summary of the Invention

[0005] The present invention relates to - a reverse water gas shift (RWGS) section, - a first hydrogen-containing feed to the RWGS section and a second carbon dioxide-containing feed to the RWGS section; or - a combined feed comprising hydrogen and carbon dioxide to the RWGS section; A reverse water gas shift (RWGS) section including - a water removal section downstream of the RWGS section, - a compressor downstream of the water removal section, and - A cryogenic CO2 separation section downstream of the compressor; A plant comprising: the RWGS section is configured to convert the first feed and the second feed, or the combined feed, into a first syngas stream and to supply the first syngas stream to a water removal section; the water removal section is configured to remove water from the first syngas stream to produce a dehydrated syngas stream and a water condensate; the dehydrated syngas is compressed in a compressor to form a compressed syngas stream, the cryogenic CO2 separation section being arranged to separate the compressed syngas stream into a CO2-depleted syngas stream and a CO2-rich condensate; The plant has means for recycling at least a portion of the CO2-rich condensate to the RWGS section or to the feed to the RWGS section; and The RWGS section is an electrically heated RWGS (e-RWGS) section. The plant is provided.

[0006] In the reverse water gas shift (RWGS) process step, the resulting product syngas inevitably contains a certain level of CO due to the thermodynamics of the reaction. The inclusion of CO in the syngas is undesirable as it acts as an inert reactant in several downstream synthesis processes, thus reducing the overall process economy. The present invention is based on the recognition that subjecting the syngas from the RWGS step to a cryogenic CO separation step entails a number of advantages.

[0007] Firstly, the cryogenic CO2 separation unit operates at high pressure, which may be at the same level or higher than the pressure of the RWGS section, meaning that the cryogenic CO2 separation section offers the possibility to recycle the CO2 separated therein to the RWGS section without the need for a compressor, thereby making such recycling of CO2 economically beneficial.

[0008] Secondly, the high pressure of the cryogenic CO2 separation unit offers the possibility to provide CO2-depleted syngas at high pressure for downstream synthesis, e.g. for Fischer-Tropsch reactions and for direct use of the CO, again eliminating the need for a separate compressor.

[0009] Third, the use of a cryogenic CO2 separation unit in combination with the RWGS section allows for higher levels of CO2 reduction in the RWGS section and therefore offers the possibility to operate the RWGS section at conditions not selected to minimize CO2 levels in the syngas product.

[0010] Furthermore, the use of an electrically heated RWGS (e-RWGS) in combination with the use of a cryogenic CO2 separation section in the plant of the present invention, and the recycling of CO2 from the former section to the latter section, entails the following advantages: Firstly, the plant offered the possibility to convert a very increased amount of CO2 supplied to the plant as feed and even all of the CO2 to CO in the CO2-depleted syngas product stream in the overall plant configuration scheme. As a result, the present invention allows very high hydrogen and CO2 feed utilization efficiencies and does not produce CO2 waste products.

[0011] Second, in plants including conventional combustion-heated RWGS sections, the RWGS section is heated with a hydrocarbon fuel, e.g., relatively light hydrocarbons recycled from a downstream Fischer-Tropsch unit. The plant of the present invention offers the possibility of avoiding CO2 emissions from the plant by avoiding the need to use hydrocarbon fuel to heat the RWGS section. In contrast, the eRWGS section of the present invention can be run using only sustainable electricity, thus avoiding CO2 emissions entirely.

[0012] Finally, the present invention offers the possibility to produce syngas for downstream synthesis steps at very low levels of CO2.

[0013] The plant effectively uses a variety of streams, particularly CO2. A method for producing a syngas product stream using the plant described above is also provided.

[0014] Therefore, the present invention further comprises: - providing a plant as defined in any of the preceding claims, - feeding a first hydrogen-containing feed to a RWGS section and a second carbon dioxide-containing feed to a RWGS section or feeding said combined feed comprising hydrogen and carbon dioxide to an e-RWGS section, - removing water from the first syngas stream in a water removal section to produce a dehydrated syngas stream and a water condensate; - separating the dehydrated syngas stream in a cryogenic CO2 separation section into a CO2-depleted syngas stream and a CO2-rich condensate; and - recycling at least a portion of the CO2-rich condensate to the RWGS section or to the feed to the RWGS section, The present invention provides a method comprising:

[0015] Further details of the technology are provided in the accompanying claims, figures and examples.

[0016] The technology is illustrated by the following schematic illustration. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 shows a first embodiment of a plant according to the invention. [Diagram 2] A second embodiment of the plant of the invention is shown in Figure 2. DETAILED DESCRIPTION Unless otherwise specified, all percentages given for gas contents are by volume.

[0018] Carbon capture and utilization has been gaining greater interest over the years. The proposed layout provides a solution for utilization of CO2 in the presence of H2 for the production of syngas, which can then be converted into valuable products such as syngas-derived liquid fuels, also known as synthetic fuels. For the conversion of CO2 and H2 feed to syngas, primarily an electrically heated RWGS (e-RWGS) section is used.

[0019] In this technology, the carbon dioxide and hydrogen feeds are mainly processed in the e-RWGS section.

[0020] The term "synthesis gas" is meant to refer to a gas that includes hydrogen, carbon monoxide, and carbon dioxide, as well as small amounts of other gases, such as argon, nitrogen, methane, and the like.

[0021] In one embodiment, the plant comprises: - a first hydrogen-bearing feed to the e-RWGS section; and - A second CO2-bearing feed to the e-RWGS section; Includes.

[0022] As an alternative to a separate first feed and a separate second feed, the plant may include a combined feed comprising hydrogen and carbon dioxide to the e-RWGS section.

[0023] The e-RWGS section is positioned to convert at least a portion of the first feed and at least a portion of the second feed, or at least a portion of the composite feed, into a first syngas stream.

[0024] In one aspect, a first hydrogen-containing feed to the e-RWGS section and a second carbon dioxide-containing feed to the e-RWGS section are arranged to be mixed to provide a composite feed provided to the e-RWGS section.

[0025] The first syngas stream suitably has the following composition (by volume): - 40-70% H2 (dry condition), - 10-40% CO (dry condition), - 2-20% CO2 (dry conditions).

[0026] The first syngas stream may additionally contain other components, such as methane, water vapor, and / or nitrogen.

[0027] first supply A first hydrogen-containing feed is subjected to the syngas stage (A). Suitably, the first feed consists essentially of hydrogen. The first feed of hydrogen is suitably "hydrogen-rich"; this means that the majority of the feed is hydrogen, i.e. more than 75%, such as more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of the feed is hydrogen. One source of the first feed of hydrogen can be one or more electrolysis units. Besides hydrogen, the first feed may contain, for example, water vapor, nitrogen, argon, carbon monoxide, carbon dioxide, and / or hydrocarbons. In some cases, a small content of oxygen, typically less than 100 ppm oxygen, may be present in the feed. The first feed suitably contains only a small amount of hydrocarbons, such as less than 5% hydrocarbons or less than 3% hydrocarbons or less than 1% hydrocarbons.

[0028] In one embodiment, the first feed is provided, at least in part, from an electrolysis unit, such as alkaline electrolysis, proton exchange membrane and / or solid oxide cell electrolysis.

[0029] second feed A second carbon dioxide-containing feed is provided to the syngas stage (A). Suitably, the second feed consists essentially of CO2. The second feed of CO2 is suitably "CO2-rich"; this means that the major part of this feed is CO2; i.e. more than 75%, such as more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of this feed is CO2. One source of the second feed of carbon dioxide can be one or more exhaust streams from one or more chemical plants. One source of the second feed of carbon dioxide can also be carbon dioxide captured from one or more process streams or atmospheric air. One other source of the second feed can be CO2 captured or recovered from flue gas, for example from flue gas from a combustion-fired heater, a steam reformer and / or a power plant. The second feed may contain, in addition to CO2, for example, water vapor, oxygen, nitrogen, oxygenates, amines, ammonia, carbon monoxide, and / or hydrocarbons. The second feed suitably contains only small amounts of hydrocarbons, for example less than 5% hydrocarbons, or less than 3% hydrocarbons, or less than 1% hydrocarbons.

[0030] The second carbon dioxide-containing feed may alternatively or additionally be a stream comprising CO and CO2, which is discharged from an electrolysis section arranged to convert a feed of CO2 to a stream comprising CO and CO2.

[0031] In one particular aspect, a portion of the CO2 stream is fed directly to the RWGS section as a second carbon dioxide-containing feed, while another portion of this CO2 stream is fed to the electrolysis section where it is converted to a stream comprising CO and CO2. The stream comprising CO and CO2 may then be fed to the RWGS section.

[0032] composite feed As an alternative to separate first and second feeds, the plant may include a combined feed comprising hydrogen and carbon dioxide to the e-RWGS section, typically with a hydrogen content of between 40% and 80%, preferably between 50% and 70%.

[0033] Typically, the carbon dioxide content of the composite feed is between 15% and 50%, preferably between 20% and 40%. Typically, the carbon monoxide content of the composite feed is between 0% and 10%. Typically, the hydrogen to carbon dioxide ratio in the composite feed is between 1 and 5, preferably between 2 and 4.

[0034] Besides hydrogen and carbon dioxide, the composite feed may comprise, for example, water vapor, nitrogen, argon, carbon monoxide, and / or hydrocarbons. The composite feed suitably comprises only small amounts of hydrocarbons, for example less than 5% hydrocarbons, or less than 3% hydrocarbons, or less than 1% hydrocarbons.

[0035] A portion of the composite feed may be produced by co-electrolysis of a water / steam feed and a CO2 feed.

[0036] third supply A third hydrocarbon-containing feed external to the plant can be fed to the RWGS section and / or the reforming section. The third feed may additionally contain CO2 and / or CO and / or H2 and / or steam and / or other components, such as nitrogen and / or argon. Suitably, the third feed consists essentially of hydrocarbons or of a mixture of hydrocarbons and steam. The third feed of hydrocarbons is suitably "hydrocarbon-rich", meaning that the major part of this feed is hydrocarbons; i.e. more than 25%, more than 50%, such as more than 75%, such as more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of this feed is hydrocarbons. The concentration of hydrocarbons in this third feed is determined before the addition of steam (i.e. determined as "dry concentration").

[0037] An example of such a third feed may be a natural gas stream external to the plant. In one aspect, the third feed comprises one or more hydrocarbons selected from methane, ethane, propane, or butanes.

[0038] The source of the third hydrocarbon-containing stream is external to the plant. By "external to the plant" stream is meant that the stream is not a recycle stream from the synthesis stage of the plant (or a recycle stream that has been further processed or converted). Possible sources of the third hydrocarbon-containing feed external to the plant include natural gas, LPG, refinery off-gas, naphtha, and renewables, although other possibilities are possible.

[0039] RWGS reaction The production of undesirable by-products, such as methane, occurs according to one or both of the following methanation reactions: CO(g)+3H2(g) <-> CH4(g)+H2O(g) (2) CO2(g)+4H2(g) <-> CH4(g)+2H2O(g) (3) In the following, the term "selective RWGS" means that only the reverse water gas shift reaction occurs on the catalyst or in the reactor, whereas "non-selective RWGS" means that other reactions, such as one or more of the above-mentioned methanation reactions (including reverse methanation), occur in addition to the reverse water gas shift.

[0040] In one embodiment, the catalytically active material catalyzes selective RWGS. In an alternative embodiment, the catalytically active material catalyzes non-selective RWGS.

[0041] e-RWGS Section In the plant of the present invention, the RWGS section is an electrically heated reverse water gas shift (e-RWGS) section. The electrically heated reverse water gas shift (e-RWGS) uses an electrically resistively heated reactor to perform a more efficient reverse water gas shift process and greatly reduce or preferably avoid the use of fossil fuels as a heat source.

[0042] In the present invention, an e-RWGS section is used to carry out the reverse water gas shift reaction between CO2 and H2. In a first embodiment, the e-RWGS section suitably comprises: - a structured catalyst comprising a macrostructure of an electrically conductive material capable of catalyzing both a reverse water gas shift reaction and a methanation reaction; wherein said structured catalyst comprises a macrostructure of an electrically conductive material, said macrostructure supporting a ceramic coating, wherein said ceramic coating supports a catalytically active material (for selective e-RWGS); - a pressure shell containing the structured catalyst; wherein the pressure shell includes an inlet for introducing the feed and an outlet for discharging a syngas product; wherein the inlet is positioned such that the feed enters the structured catalyst at a first end of the structured catalyst and the syngas product exits the structured catalyst from a second end of the structured catalyst; - a thermal insulation layer between the structured catalyst and the pressure shell; and - at least two conductors electrically connected to the structured catalyst and to a power supply located outside the pressure shell; wherein the power supply is dimensioned to heat at least a portion of the structured catalyst to a temperature of at least 500°C by passing an electric current through the macrostructure of electrically conductive material; the at least two conductors are connected to the structured catalyst at a location on the structured catalyst closer to the first end of the structured catalyst than to the second end of the structured catalyst; and the structured catalyst is configured to pass electric current from one conductor substantially to the second end of the structured catalyst and back to a second of the at least two conductors; and the structured catalyst has an electrically insulating portion positioned to pass electric current from one conductor closer to the first end of the structured catalyst than to the second end of the structured catalyst to the second end of the structured catalyst and back to a second conductor closer to the first end of the structured catalyst than to the second end of the structured catalyst; Includes.

[0043] In a second aspect, the e-RWGS section suitably comprises: - a structured catalyst comprising a macrostructure of an electrically conductive material capable of catalyzing both the reverse water gas shift reaction and the methanation reaction; wherein said structured catalyst comprises a macrostructure of an electrically conductive material, said macrostructure supporting a ceramic coating, wherein said ceramic coating supports a catalytically active material (for non-selective e-RWGS); - Optionally, a top layer disposed on top of the structured catalyst, comprising a pellet catalyst (for non-selective e-RWGS) capable of catalyzing both methanation and reverse water gas shift reactions; - Optionally, a bottom layer disposed on the lower surface of the structured catalyst, comprising a pellet catalyst (for non-selective e-RWGS) capable of catalyzing both methanation and reverse water gas shift reactions; - a pressure shell containing the structured catalyst; wherein the pressure shell includes an inlet for introducing the feed and an outlet for discharging a syngas product; wherein the inlet is positioned such that the feed enters the structured catalyst at a first end of the structured catalyst and the syngas product exits the structured catalyst from a second end of the structured catalyst; - a thermal insulation layer between the structured catalyst and the pressure shell; and - at least two conductors electrically connected to the structured catalyst and to a power supply located outside the pressure shell; wherein the power supply is dimensioned to heat at least a portion of the structured catalyst to a temperature of at least 500°C by passing an electric current through the macrostructure of electrically conductive material; the at least two conductors are connected to the structured catalyst at a location on the structured catalyst closer to the first end of the structured catalyst than to the second end of the structured catalyst; and the structured catalyst is configured to pass electric current from one conductor substantially to the second end of the structured catalyst and back to a second of the at least two conductors; and the structured catalyst has an electrically insulating portion positioned to pass electric current from one conductor closer to the first end of the structured catalyst than to the second end of the structured catalyst to the second end of the structured catalyst and back to a second conductor closer to the first end of the structured catalyst than to the second end of the structured catalyst; Includes.

[0044] The pressure shell suitably has a design pressure between 2 and 30 bar. The pressure shell may have a design pressure between 30 and 200 bar. The at least two conductors typically penetrate the pressure shell in a fitting, such that the at least two conductors are electrically insulated from the pressure shell. The pressure shell further comprises one or more inlets near or in combination with at least one fitting to allow cooling gas to flow within the pressure shell, over, around, adjacent to or within at least one conductor. The outlet temperature of e-RWGS section (I) is suitably 900°C or higher, preferably 1000°C or higher, even more preferably 1100°C or higher.

[0045] In one embodiment of the plant of the present invention, the e-RWGS section comprises a structured catalyst comprising macrostructures of electrically conductive material capable of catalyzing both the reverse water gas shift reaction and the methanation reaction.

[0046] In the case of non-selective e-RWGS, methanation via reactions (2) and / or (3) occurs in addition to the RWGS reaction. This has the advantage that the concentration of carbon monoxide inside the reactor is lower than when only reverse water gas shift occurs. This is especially important in the low to medium temperature range up to about 600-800°C. In this temperature range, the possibility of carbon formation or metal dusting is present or is much greater with selective RWGS catalysts than with non-selective catalysts.

[0047] In one embodiment, methanation reaction(s) also occur at and near the inlet of the reactor. However, at a given temperature (which depends on the feed gas composition, pressure, catalyst activity, degree of heat input, and other factors), the reverse of the methanation reaction is thermodynamically favored. In other words, in an initial portion of the RWGS reactor, methane forms, and in a second portion downstream of this first portion, methane is consumed according to the reverse of reactions (2) and / or (3).

[0048] In one embodiment of the eRWGS reactor of the present invention, the eRWGS reactor comprises a structured catalyst having a first reaction zone located proximate a first end of the structured catalyst, where the first reaction zone has an exothermic reaction throughout, and a second reaction zone located proximate a second end of the structured catalyst, where the second reaction zone has an endothermic reaction throughout. Preferably, the first reaction zone extends between the first 5% and the first 60% of the length of the total reaction zone in the reactor, where reaction zone is understood to be the volume of the reactor system that catalyzes the methanation and reverse water gas shift reactions, evaluated along the flow path through the catalyst zone.

[0049] The combined activity for both water gas shift and methanation in the eRWGS reactor of the present invention causes the reaction scheme within the reactor to start as exothermic in the initial part of the reactor system and end as endothermic towards the outlet of the reactor system. This is in accordance with the following general heat balance of a plug flow reactor system, where the reaction heat (Q r ) Regarding: F.C. pm dT / dV=Q add +Q r =Q add +Σ(-Δ r H i )·(-r i ) where F is the flow rate of the process gas and C pm is the heat capacity, V is the volume of the reaction zone, T is the temperature, and Q add is the energy supply / removal from the surroundings, and Q r is the energy supply / removal associated with a chemical reaction, given as the sum of all chemical reactions facilitated in the volume and calculated as the product of the reaction enthalpy and the reaction rate of a given reaction.

[0050] In one embodiment when using a non-selective RWGS reactor, the methane concentration by volume in the gas leaving the e-RWGS reactor is less than 6%, for example less than 4% or preferably less than 3%. The high product gas temperature ensures that the final syngas product has a low methane concentration, although the methane concentration will peak somewhere along the reaction zone. Therefore, this reactor configuration can be operated with no or small amounts of methane in the feed and only traces of methane in the product gas, but with a higher methane concentration peak in the reaction zone than in the feed and / or product gas. Since methane does not serve as a reactant in downstream syntheses such as methanol or Fischer-Tropsch, it is often advantageous to have as low a concentration of methane in the synthesis gas as possible.

[0051] In one embodiment, the methane concentration in the e-RWGS is greater than both the concentration in the inlet gas to the e-RWGS section and the concentration in the outlet gas from the e-RWGS section.

[0052] The e-RWGS section includes one or more e-RWGS reactors, and in one embodiment consists of a single e-RWGS reactor, in which the methane concentration at (at least one) location within the reactor may be greater than the methane concentration in both the reactor feed gas and the reactor outlet gas.

[0053] The low concentration of methane can be achieved by the high temperature outside the e-RWGS reactor. The high temperature has the added advantage of a higher conversion of CO2 to CO. In one embodiment, the outlet temperature of the gas from the e-RWGS reactor is above 900°C, such as above 1000°C or even above 1050°C. One advantage of the proposed reactor is that higher temperatures can be achieved than are typically possible with externally fired heated reactors.

[0054] Another way to have a low concentration at the outlet of the e-RWGS reactor is to have a low to medium pressure between 5 and 20 bar or between 8 and 12 bar. In this embodiment, the gas leaving the e-RWGS section is typically cooled and the water is (partially) removed by condensation followed by compression to the pressure desired for the downstream application.

[0055] In one embodiment, there may be a reactor upstream of the e-RWGS section. This reactor may be adiabatic or cooled, and the catalyst is typically pellet-based. Part or all of the first feed, or all of the second feed, is guided to this reactor, where the RWGS and methanation reactions (1-3) take place. The outlet temperature from this reactor typically ranges between 400°C and 700°C. The effluent from this reactor (optionally after cooling and condensation of some of the H2O produced) is fed to the e-RWGS section. This has the advantage that the amount of CO2 in the effluent from the e-RWGS section is lower.

[0056] In one specific embodiment, the gas containing carbon monoxide, carbon dioxide, hydrogen and methane is combined with a third feed containing hydrocarbons (e.g., tail gas or light end hydrocarbons) to the e-RWGS section. Alternatively, the third feed is composed exclusively of the gas containing carbon monoxide, carbon dioxide, hydrogen and methane. One example can be tail gas from a Fischer-Tropsch synthesis section. Such a gas can be, for example, 10-30% CO, 20-70% CO2, 10-30% H2, 5-25% CH4, 0.2~10% other hydrocarbons, may include.

[0057] Such a stream can be added directly to the e-RWGS section. Alternatively, the stream is first passed through a water gas shift reactor with water vapor (the reverse of reaction 1 above): CO+H2O <-> H2+CO2(6) This reduces the CO concentration at the inlet to the e-RWGS section, thus reducing the likelihood of carbon formation.

[0058] The effluent from the water gas shift reactor can also be directed to another reactor (higher hydrocarbon removal reactor). This higher hydrocarbon removal reactor may be adiabatic or cooled, and the catalyst is typically pellet-based. In this higher hydrocarbon removal reactor, the RWGS reaction (1) (or the shift reaction (6)) and the methanation reaction (2-3) or the reverse methanation reaction (which depends on the gas composition, temperature and pressure) take place. In addition, steam reforming of higher hydrocarbons can take place in this reactor: C n H m +nH2O → nCO+(m / 2+n)H2(7) The reactor conditions are preferably adjusted to convert more than 90%, such as more than 95%, of the non-methane hydrocarbons present in the feed mixture. The removal or substantial reduction of non-methane hydrocarbons has the advantage that the risk of carbon formation during the e-RWGS reaction(s) in the e-RWGS section is significantly reduced.

[0059] The outlet temperature from this higher hydrocarbon removal reactor typically ranges between 400° C. and 700° C. The effluent from this reactor (optionally after cooling and condensation of some of the H2O produced) is fed to the e-RWGS section. This has the advantage that the amount of CO2 in the effluent from the e-RWGS section is lower. The effluent may be mixed with the first and second feeds before being fed to the e-RWGS section.

[0060] The e-RWGS reactor may further include an inner tube in heat exchange relationship with, but electrically insulated from, the structured catalyst, the inner tube adapted to remove product gas from the structured catalyst such that gas flowing through the inner tube is in heat exchange relationship with gas flowing over the structured catalyst. The connection between the structured catalyst and the at least two conductors can be a mechanical connection, a welded connection, a brazed connection, or a combination thereof.

[0061] The electrically conductive material suitably comprises a 3D printed or extruded or sintered macrostructure, said macrostructure supporting a ceramic coating, said ceramic coating supporting a catalytically active material. The structured catalyst may comprise an array of macrostructures electrically connected to each other. The macrostructure may have a plurality of parallel flow paths, a plurality of non-parallel flow paths, and / or a plurality of labyrinth-like flow paths. The reactor typically comprises a bed of a second catalyst material within the pressure shell and upstream of the structured catalyst.

[0062] In one aspect, the e-RWGS reactor further comprises a catalytic material in the form of catalytic pellets, extrudates or granules loaded into the channels of said macrostructure. The e-RWGS reactor may further comprise a control system arranged to control the power supply to ensure that the temperature of the gas exiting the pressure shell is within a predetermined range and / or to ensure that the conversion of the feed gas is within a predetermined range.

[0063] As used herein, the term "macrostructure" is intended to refer to a structure large enough to be visible to the naked eye without the use of a magnifying device. The dimensions of the macrostructure are typically in the centimeter or even meter range. The dimensions of the macrostructure are advantageously made to at least partially correspond to the internal dimensions of the pressure shell, thus leaving space for the thermal insulation layer and the conductors.

[0064] The ceramic coating, with or without the catalytically active material, may be applied directly to the metal surface by washcoating. Washcoating of metal surfaces is a well-known process and is described, for example, in Cybulski, A., and Moulijn, JA, Structured catalysts and reactors, Marcel Dekker, Inc, New York, 1998, Chapter 3, and references cited therein. The ceramic coating may be applied to the surface of the macrostructure and then the catalytically active material is applied, or alternatively, a ceramic coating containing the catalytically active material is applied to the macrostructure.

[0065] Preferably, the macrostructure is produced by extruding a mixture of powdered metal particles and a binder into an extruded structure and then sintering the extruded structure to provide a material with a high geometric surface area per unit volume. A ceramic coating, which may include a catalytically active material, is provided on the macrostructure before the second sintering in an oxidizing atmosphere in order to form a chemical bond between the ceramic coating and the macrostructure. Alternatively, the catalytically active material may be impregnated on the ceramic coating after the second sintering. When a chemical bond is formed between the ceramic coating and the macrostructure, a particularly high thermal conduction between the electrically heated macrostructure and the catalytically active material carried on the ceramic coating is possible, providing a close, almost direct contact between the heat source and the catalytically active material of the macrostructure. The close proximity of the heat source and the catalytically active material results in an efficient heat transfer, and as a result, the macrostructure can be heated very efficiently. Therefore, a small reforming reactor device is possible in terms of gas processing per unit volume of the reforming reactor device, and therefore the reforming reactor containing the macrostructure can be small. The reforming reactor of the present invention does not require a furnace, which significantly reduces the size of the electrically heated reforming reactor.

[0066] Preferably, the conductor is made of a different material than the macrostructure. The conductor can be made of, for example, iron, nickel, aluminum, copper, silver or alloys thereof. The ceramic coating is an electrically insulating material and typically has a thickness in the range of about 100 μm, for example in the range of 10-500 μm. In addition, catalysts may be placed in the pressure shell and in the flow paths within the macrostructure, around the macrostructure, or upstream and / or downstream of the macrostructure to support the catalytic function of the macrostructure.

[0067] In an e-RWGS reactor, the structured catalyst in the reactor system may have a ratio between the area equivalent diameter of the horizontal cross section of the structured catalyst and the height of the structured catalyst in the range of 0.1 to 2.0.

[0068] Preferably, the macrostructure comprises Fe, Ni, Cu, Co, Cr, Al, Si or alloys thereof. Such alloys may comprise other elements such as Mn, Y, Zr, C, Co, Mo or combinations thereof. Preferably, the catalytically active material is a particle having a size between 5 nm and 250 nm. The catalytically active material may comprise, for example, copper, nickel, ruthenium, rhodium, iridium, platinum, cobalt or combinations thereof. Thus, one possible catalytically active material is a combination of nickel and rhodium, and another combination of nickel and iridium. The ceramic coating may be, for example, an oxide comprising Al, Zr, Mg, Ce and / or Ca. Exemplary coatings are calcium aluminate or magnesium aluminum spinel. Such ceramic coatings may further comprise other elements such as La, Y, Ti, K or combinations thereof.

[0069] In one aspect of the plant, the ratio of moles of carbon in a third feed comprising hydrocarbons to the moles of carbon in the CO2 in the second feed, preferably when the third feed is external to the plant, is less than 0.3, preferably less than 0.25, more preferably less than 0.20, or even less than 0.10.

[0070] The use of an e-RWGS section (compared to a conventional fuel-fired RWGS section) allows for the production of product gas with a lower CO2 content, which is desirable for some applications, e.g., FT synthesis or methanol synthesis, since the high temperature at which the e-RWGS operates ensures a high conversion of CO2 to CO.

[0071] Water Separation Section In one embodiment, the water removal section is selected from the group consisting of a flash separation unit, a pressure swing adsorption (PSA) unit, a temperature swing adsorption (TSA) unit, or a combination thereof.

[0072] In one embodiment, the water separation section of the plant is a flash separation unit, which is often preceded by a suitable temperature reduction device. Brush separation refers to a phase separation unit in which a stream is separated into liquid and vapor phases near or at thermodynamic phase equilibrium at a given temperature.

[0073] In one embodiment, the water separation section of the plant is a pressure swing adsorption unit (PSA unit) or a temperature swing adsorption unit (TSA unit). Swing adsorption refers to a unit for adsorbing selected compounds. In this type of equipment, a dynamic equilibrium is established between the adsorption and desorption of gas molecules on the adsorbent material. The adsorption of gas molecules can be caused by steric, kinetic or equilibrium effects. The exact mechanism is determined by the adsorbent used, and the equilibrium saturation depends on the temperature and pressure. Typically, the adsorbent is treated in a gas mixture until near saturation of the heaviest compounds and then requires regeneration. This regeneration can be done by changing the pressure or temperature. In practice, this means that a process with at least two units is used, i.e., first saturating the adsorbent at high pressure or low temperature in one unit, then changing the unit where the adsorbed molecules are desorbed from the same unit by lowering the pressure or increasing the temperature. If the unit operates at varying pressures it is referred to as a pressure swing adsorption unit, and if the unit operates at varying temperatures it is referred to as a temperature swing adsorption unit.

[0074] Cryogenic CO2 Separation Section Cryogenic separation typically utilizes phase changes of different chemical species in a gas to separate individual components (i.e., CO2) from a gas mixture by controlling the temperature, typically occurring below -50°C. Such cryogenic separation units typically include an initial cooling stage of synthesis gas followed by a cryogenic flash separation unit to separate liquid condensate from the gas phase. Cooling for the first cooling stage can be provided by the resulting products from the cryogenic flash separation unit, possibly in combination with other coolants. Optionally, one or more of the products from the CO2 removal unit may be expanded to some extent to produce cooler process gas for this cooling stage. Cryogenic separation of CO2 needs to be facilitated at elevated pressures, at least above the triple point of CO2, to condense CO2. Therefore, a suitable pressure regime is at least 5 bar above the triple point, where the elevated pressure provides an enhanced liquid yield.

[0075] In one embodiment of the invention, the cryogenic CO2 separation section is operated at a temperature of about -30° C. to -80° C. In one embodiment of the invention, the amount of CO2 condensed in the cryogenic separation is increased by lowering the operating temperature.

[0076] In one embodiment, the cryogenic CO2 separation section includes a cooling unit followed by a flash separation unit and then a heating unit. In one embodiment, the cryogenic CO2 separation section includes a gas dryer unit. Preferably, the gas dryer unit is the first unit of the cryogenic CO2 separation section.

[0077] Compressor In one embodiment of the plant of the invention, the means for recycling at least a portion of the CO2-rich condensate does not include a compressor for compressing this CO2-rich condensate.

[0078] In one embodiment of the invention, the plant does not include a compressor downstream of the cryogenic CO2 separation section.

[0079] Synthesis Stage In one embodiment of the invention, the plant comprises a synthesis stage downstream of the cryogenic CO2 separation section arranged to feed a CO2-depleted syngas to the synthesis stage. Suitably, the synthesis stage is arranged to convert said CO2-depleted syngas stream to at least a hydrocarbon product stream and optionally a hydrocarbon-containing off-gas stream.

[0080] In one embodiment of the invention, the synthesis stage comprises a synthetic fuel synthesis section, an alcohol synthesis section or an olefin synthesis section.

[0081] Examples of synthetic fuel end products are diesel fuel, jet fuel and gasoline.

[0082] In one embodiment of the invention, in which the synthesis stage comprises a synthetic fuel synthesis section, the synthesis stage further comprises a Fischer-Tropsch (FT) section upstream of the synthetic fuel synthesis section.

[0083] The synthesis section may include other process units, such as compressors, heat exchangers, separators, and the like.

[0084] Suitably the syngas stream at the inlet to said synthesis stage has a hydrogen / carbon monoxide ratio in the range from 1.00 to 4.00, preferably from 1.50 to 3.00, more preferably from 1.50 to 2.10.

[0085] In one embodiment, the H2 / CO ratio in the CO2-depleted syngas stream is between approximately 0.5 and 4.5.

[0086] In particular, the synthesis stage may include a Fischer-Tropsch (FT) stage arranged to convert the syngas stream to at least a hydrocarbon product stream and a hydrocarbon-containing off-gas stream in the form of a FT off-gas stream. In this respect, at least a portion of the hydrocarbon-containing off-gas stream may be recycled to the RWGS section as the third hydrocarbon-containing feed or in addition to the third hydrocarbon-containing feed. This increases the overall carbon efficiency. In one embodiment, the plant includes a compressor for compressing the FT off-gas that is recycled to the RWGS section.

[0087] In another aspect, the synthesis stage includes a methanol synthesis stage configured to provide at least a methanol product stream.

[0088] Additionally, the ratio of H2:CO2 provided to the plant inlet may be between 1.0 and 9.0, preferably between 2.5 and 8.0, and more preferably between 3.0 and 7.0.

[0089] The hydrogen feed may be arranged to be combined with the CO2-depleted syngas stream upstream of the synthesis stage, allowing the H2:CO2 ratio to be adjusted as required.

[0090] Modification Section The syngas stage of the present invention may advantageously comprise one or more additional sections in addition to the e-RWGS described above.

[0091] In one aspect, the plant may include a reforming section disposed in parallel with the e-RWGS section, wherein the plant includes a third hydrocarbon-containing feed to the reforming section and the reforming section is configured to convert at least a portion of the third feed to a second syngas stream.

[0092] The second syngas stream may have the following composition (by volume): - 40~70% H2 (dry condition) - 10-30% CO (dry condition) - 2-20% CO2 (dry condition) - 0.5-5% CH4 In this aspect, a first syngas stream from the e-RWGS section is arranged to be combined with a second syngas stream from the reforming section to provide a combined syngas stream, which is arranged to be fed to a synthesis stage.

[0093] According to this aspect, the reforming section may be selected from the group consisting of an autothermal reforming (ATR) section, a steam methane reforming (SMR) section and an electrically heated steam methane reforming (e-SMR) section.

[0094] In one aspect, the reforming section is an autothermal reforming (ATR) section. In this aspect, the plant further comprises a fourth steam-containing feed, and optionally a fifth oxygen-containing feed, to the autothermal reforming (ATR) section (IIa). The fourth steam-containing feed is also required when the reforming section is an SMR or e-SMR.

[0095] In another aspect, the reforming section is an electrically heated steam methane reforming (e-SMR) section. In this aspect, the plant does not include an oxygenated feed to the electrically heated steam methane reforming (e-SMR) section. In this aspect, the overall CO2 production from the plant can be reduced.

[0096] In one aspect, at least a portion of the second carbon dioxide-containing feed is fed to a reforming section.

[0097] The third hydrocarbon-containing feed may be a natural gas feed.

[0098] In one aspect, the plant may include an autothermal reforming (ATR) section including one or more autothermal reactors (ATR), where the first, second, third and fourth feeds are fed to the ATR section. Alternatively, at least a portion of the composite feed may be fed to the ATR section. Some or all of the third feed may be desulfurized and pre-reformed. All feeds are preheated as required. An important part of the ATR section is the ATR reactor. The ATR reactor typically includes a burner, a combustion chamber and a catalyst bed, which are housed in a lined, heat-resistant pressure shell. In the ATR reactor, partial combustion of the hydrocarbon-containing feed with substoichiometric oxygen is followed by steam reforming of the partially burned hydrocarbon feed stream in a fixed bed of steam reforming catalyst. Steam reforming also occurs to some extent in the fuel chamber due to its high temperature. The steam reforming reaction is accompanied by a water gas shift reaction. Typically, the gas is at or near equilibrium with respect to the steam reforming and water gas shift reactions at the outlet of the reactor.

[0099] Typically, the effluent gas from an ATR reactor has a temperature of 900-1100° C. The effluent gas usually contains H2, CO, CO2 and water vapor. Other components such as methane, nitrogen and argon may also be present, often in small amounts. The operating pressure of the ATR reactor is between 5 and 100 bar, more preferably between 15 and 60 bar.

[0100] The syngas stream from the ATR is cooled in a cooling train, which typically includes a waste heat boiler(s) (WHB) and one or more additional heat exchangers. The cooling medium in the WHB is (boiler feed) water, which is evaporated to steam. The syngas stream is further cooled to below its cloud point, for example by preheating the plant and / or by partial preheating of one or more feed streams and cooling in an air cooler and / or water cooler. The condensed HO is removed as a process condensate in a separator to provide a syngas stream with low HO content, which is sent to the synthesis stage.

[0101] The "ATR section" may be a partial oxidation "POX" section. The POX section is similar to the ATR section, except that the ATR reactor is replaced with a POX reactor. The POX reactor generally includes a burner and a combustion chamber, which are housed in a lined, heat-resistant pressure shell.

[0102] The ATR section can also be a catalytic partial oxidation (cPOX) section.

[0103] In one embodiment, the e-RWGS section is followed by a reforming section, which suitably comprises an autothermal reformer (ATR). An ATR reactor typically comprises a burner, a combustion chamber, and a catalyst bed, which are housed in a lined, heat-resistant pressure shell. In an ATR reactor, partial combustion of a hydrocarbon-containing feed with substoichiometric oxygen is followed by steam reforming of this partially burned hydrocarbon feed stream in a fixed bed of steam reforming catalyst. Steam reforming also occurs to some extent in the combustion chamber due to its high temperature. The steam reforming reaction is accompanied by a water gas shift reaction. Typically, the gas is in equilibrium or near equilibrium with respect to the steam reforming and water gas shift reactions at the outlet of the reactor. Further details and detailed explanations of ATR can be found in the prior art, such as "Studies in Surface Science and Catalysis, Vol. 152" (Non-Patent Document 2), "Synthesis gas production for FT synthesis"; Chapter 4, p. 258-352, 2004 (Non-Patent Document 3)".

[0104] In this case, the outlet gas from the e-RWGS reactor is directed to an autothermal reformer. In this embodiment, the outlet gas from the e-RWGS reactor is reacted with an oxidant to produce a final synthesis gas. The final synthesis gas in this embodiment typically has a temperature above 950°C, such as above 1020°C, or 1050°C or higher. In this particular embodiment, the outlet temperature from the e-RWGS reactor is typically between 600°C and 900°C, such as between 700°C and 850°C. In this embodiment, the e-RWGS reactor may be selective or, preferably, non-selective. In one embodiment, a hydrocarbon-containing feed gas is added to the outlet gas from the e-RWGS reactor upstream of the autothermal reactor. This can be, for example, tail gas from a downstream Fischer-Tropsch synthesis unit.

[0105] In embodiments with an ATR after the non-selective RWGS reactor, the methane concentration leaving the RWGS reactor is preferably small, e.g., less than 20% or preferably less than 12%. A relatively low concentration has the advantage that less oxidant is required in the autothermal reactor.

[0106] In embodiments with an ATR after the RWGS reactor, the gas leaving the RWGS reactor is preferably not cooled (except for heat losses due to mixing with other streams). Cooling the gas would increase the oxygen consumption in the ATR.

[0107] An advantage of the embodiment with an ATR is that the power required for the e-RWGS reactor is reduced due to the relatively low outlet temperature. In one embodiment, some or all of the oxygen generated by the electrolysis of water vapor to produce hydrogen for the e-RWGS reactor is used in the autothermal reactor.

[0108] The oxidant for an autothermal reformer may be oxygen, air, or a mixture of air and oxygen, or an oxidant containing more than 80% oxygen, for example more than 90% oxygen. The oxidant may also contain other components such as water vapor, nitrogen and / or argon. Typically, the oxidant in this case contains 5-20% water vapor.

[0109] Electrolysis Section A sixth hydrogen feed may be arranged to be combined with the first syngas stream upstream of the synthesis gas, allowing the required H2:CO2 ratio to be adjusted as required.

[0110] In one embodiment, the plant further comprises an electrolysis section arranged to convert water or steam into at least a hydrogen stream and an oxygen stream, and at least a portion of said hydrogen stream from the electrolysis section is arranged to be fed to the RWGS section as said first feed. Additionally, at least a portion of the hydrogen stream from the electrolysis section may be included as a sixth hydrogen feed. Some or all of the water or steam fed to the electrolysis section may be from the RWGS section or from the synthesis stage.

[0111] Where the plant includes a reforming section which is an autothermal reforming (ATR) section, at least a portion of the oxygen stream from the electrolysis section is suitably arranged to be supplied to the RWGS section as said fifth oxygen-containing feed.

[0112] The electrolysis section may be arranged to convert a feed of CO to a stream comprising CO and CO, and wherein at least a portion of said stream comprising CO and CO from the electrolysis section is arranged to be fed to the RWGS section as at least a portion of said second carbon dioxide containing feed.

[0113] An electrolysis section may be located upstream of the eRWGS to convert the CO2 feed and the water or steam feed into some or all of the combined feed including hydrogen and carbon dioxide. In other words, a single electrolysis section converts both the CO2 feed and the water / steam feed into the combined stream.

[0114] In one embodiment, the electrolysis section is selected from the group consisting of an alkaline electrolysis unit, a proton exchange membrane unit, and / or a solid oxide cell electrolysis unit.

[0115] Feed pretreatment In one embodiment, the plant further comprises a gas purification unit and / or a pre-reforming unit upstream of the RWGS section. The gas purification unit is, for example, a desulfurization unit, such as a hydrodesulfurization unit.

[0116] In one embodiment, the plant includes a pretreatment section, where the second feed is pretreated to remove undesirable components, which may be, for example, sulfur compounds, higher hydrocarbons, and inorganic species, such as alkaline metals.

[0117] In the pre-reformer, the hydrocarbon gases undergo pre-reforming together with water steam, and potentially with hydrogen and / or other components (e.g. carbon dioxide) in the temperature range of about 350-550°C to convert higher hydrocarbons as an initial step in the process, which is usually performed downstream of the desulfurization step. This eliminates the risk of carbon formation from the higher hydrocarbons on the catalyst in the next process step. Optionally, carbon dioxide or other components can be mixed with the gas leaving the pre-reforming step to form the feed gas.

[0118] Methods of the Invention The present invention relates to - providing a plant as defined in any of the preceding claims, - feeding a first hydrogen-containing feed to the RWGS section and a second carbon dioxide-containing feed to the RWGS section or feeding said combined feed comprising hydrogen and carbon dioxide to the RWGS section, - removing water from the first syngas stream in a water removal section to produce a dehydrated syngas stream and a water condensate; - compressing the dehydrated syngas stream to form a compressed syngas stream; - separating the compressed syngas stream into a CO2-depleted syngas stream and a CO2-rich condensate in a cryogenic CO2 separation section; and - recycling at least a portion of the CO2-rich condensate to the RWGS section or to the feed to the RWGS section, The present invention relates to a method comprising the steps of:

[0119] In one embodiment of the process of the present invention, the CO2-rich condensate is recycled to the RWGS section without being subjected to compression.

[0120] In one embodiment of the process of the present invention, the CO2-depleted syngas stream is subjected to processing in a synthesis stage downstream of the cryogenic CO2 separation section.

[0121] In one embodiment of the process of the present invention, the synthesis stage comprises a synthetic fuel synthesis section, an alcohol synthesis section or an olefin synthesis section.

[0122] In one embodiment of the process of the present invention, the synthesis stage comprises a synthetic fuel synthesis section, wherein the synthesis stage further comprises a Fischer-Tropsch (FT) section upstream of the synthetic fuel synthesis section.

[0123] In one embodiment of the process of the present invention, the CO2-depleted syngas stream is not subjected to compression.

[0124] In one embodiment of the process of the present invention, the cryogenic CO2 separation section is operated at a temperature of about −30° C. to −80° C. In one embodiment of the process of the present invention, the amount of CO2 condensed in the cryogenic separation is increased by decreasing the operating temperature.

[0125] In one embodiment of the process of the present invention, the CO2-depleted syngas stream has a modulus of (H2-CO2) / (CO+CO2) in the range of 1.8 to 2.2, wherein the synthesis stage comprises a methanol synthesis section.

[0126] In one embodiment of the process of the present invention, the synthesis stage comprises a Fischer-Tropsch synthesis reactor system for the production of crude oil and / or wax.

[0127] In one embodiment of the method of the invention, the CO2-depleted syngas stream has a modulus of (CO+H2) / (CO2+H2O) >7.5.

[0128] In one embodiment of the process of the invention, the CO2-depleted syngas stream has a H2 / CO ratio of <1.5.

[0129] In one embodiment of the process of the present invention, both the reverse water gas shift reaction and the methanation reaction occur in the RWGS section.

[0130] Specific aspects FIG. 1 shows an embodiment of a plant 100 of the present invention comprising a RWGS section A, a water removal section B, a compressor C and a cryogenic CO2 separation section D. An H2 feed 1 and a CO2 feed 2 are fed to the RWGS section A where the feeds are converted into a first syngas stream 10. The first syngas stream 10 is fed to a water removal section B where a water condensate 25 is removed and from there a dehydrated syngas stream 20 is fed to a compressor C. A dehydrated, compressed syngas stream 30 exits the compressor C and is fed to a cryogenic CO2 separation section D where the dehydrated, compressed syngas stream 30 is separated into a CO2-depleted syngas 40 and a CO2-rich condensate 45, the latter of which is recycled to the RWGS section A.

[0131] Figure 2 shows an embodiment of the invention based on the same plant as shown in Figure 1, with the same reference numerals used, where CO2-depleted syngas 40 is fed to a synthesis stage E, e.g. a Fischer-Tropsch (FT) section and a synthetic fuel synthesis section. From the synthesis stage E, a synthetic fuel stream 50 is discharged and a FT off-gas 55 is discharged and fed to an off-gas pre-treatment section F, where the off-gas 55 is pre-treated before being recycled to the RWGS section. EXAMPLES

[0132] Three syngas plant designs were compared with respect to the compressor power consumption required for operation.

[0133] Case 1: No CO2 removal. The CO2 feed stream is adjusted to obtain a H2 / CO2 ratio of 1.22 in the syngas product stream. A compressor is used to increase the pressure of the syngas product stream. The syngas product has high levels of CO2, which is undesirable for many downstream synthesis processes.

[0134] Case 2: As in Case 1, except with conventional amine-based CO2 removal from a portion of the produced syngas stream. A first compressor is used to increase the pressure of the syngas product stream after amine-based CO2 removal. A second compressor is used to increase the pressure of the recycled CO2.

[0135] Case 3: As in Case 1, but with a water removal section and a cryogenic CO2 separation section. A compressor is present between the water removal section and the cryogenic CO2 separation section to compress the dehydrated syngas stream. No separate compressor for CO2 recycle is required.

[0136] The operating parameters and power consumption for cases 1 to 3 are shown in Table 1.

[0137] [Table 1] As is evident from Table 1, the power consumption for compressor required to operate the plant is less in case 3 (plant of the present invention) than in case 2 (conventional plant). Case 3 also offers the possibility to avoid compressor in recycling CO2 to the RWGS section and therefore save CAPEX and OPEX costs.

Claims

1. A reverse water gas shift (RWGS) section, a first hydrogen-containing feed to the RWGS section and a second carbon dioxide-containing feed to the RWGS section; or A combined feed to the RWGS section comprising hydrogen and carbon dioxide; a reverse water gas shift (RWGS) section, - a water removal section downstream of said RWGS section; a compressor downstream of the water removal section, and - a cryogenic CO2 separation section downstream of said compressor; A plant comprising: the RWGS section is configured to convert the first feed and the second feed, or the combined feed, into a first syngas stream and supply the first syngas stream to the water removal section; the water removal section is configured to remove water from the first syngas stream to produce a dehydrated syngas stream and a water condensate; the compressor is positioned to compress the dehydrated syngas stream to produce a compressed syngas stream; the cryogenic CO2 separation section is arranged to separate the compressed syngas stream into a CO2-depleted syngas stream and a CO2-rich condensate; The plant has means for recycling at least a portion of the CO2-rich condensate to the RWGS section or to a feed to the RWGS section; and the RWGS section is an electrically heated RWGS (e-RWGS) section; The plant.

2. 2. The plant of claim 1, wherein the means for recycling at least a portion of the CO2-rich condensate does not include a compressor for compressing the CO2-rich condensate.

3. 3. The plant of claim 1 or 2, wherein the water removal section is selected from the group consisting of a flash separation unit, a pressure swing adsorption (PSA) unit, a temperature swing adsorption (TSA) unit, or a combination thereof.

4. A plant according to any one of claims 1 to 3, wherein the deep cryogenic CO2 separation section comprises a cooling unit, a downstream flash separation unit and a further downstream heating unit.

5. 5. The plant of claim 1, wherein the H2 / CO ratio in the CO2-depleted syngas stream is between approximately 0.5 and 4.

5.

6. 6. A plant according to any one of claims 1 to 5, further comprising a synthesis stage downstream of the cryogenic CO2 separation section, the cryogenic CO2 separation section being arranged to supply the CO2-depleted syngas to the synthesis stage.

7. 7. The plant of claim 6, wherein the synthesis stage comprises a synthetic fuel synthesis section, an alcohol synthesis section or an olefin synthesis section.

8. 8. The plant of claim 7, wherein the synthesis stage comprises a synthetic fuel synthesis section, the synthesis stage further comprising a Fischer-Tropsch (FT) section upstream of the synthetic fuel synthesis section.

9. A plant according to any one of claims 6 to 8, which does not include a compressor downstream of the cryogenic CO2 separation section.

10. The plant according to any one of claims 1 to 9, wherein the first feed is at least partly provided from an electrolysis unit, such as alkaline electrolysis, proton exchange membrane and / or solid oxide cell electrolysis.

11. The plant according to any one of claims 1 to 10, wherein the plant comprises a pre-treatment section, in which the second feed is pre-treated to remove undesirable components.

12. 12. The plant of any one of claims 1 to 11, wherein the e-RWGS section comprises a structured catalyst comprising macrostructures of electrically conductive material capable of catalyzing both the reverse water gas shift reaction and the methanation reaction.

13. Next steps: - providing a plant as defined in any one of claims 1 to 12, - feeding the first hydrogen-containing feed to the RWGS section and feeding the second carbon dioxide-containing feed to the RWGS section or feeding the combined feed comprising hydrogen and carbon dioxide to the RWGS section; removing water from the first syngas stream in the water removal section to produce a dehydrated syngas stream and a water condensate; - compressing the dehydrated syngas stream to form a compressed syngas stream; - separating the compressed syngas stream into a CO2-depleted syngas stream and a CO2-rich condensate in the cryogenic CO2 separation section; and - recycling at least a portion of said CO2-rich condensate to said RWGS section or to the feed to said RWGS section, A method comprising:

14. 14. The method of claim 13, wherein the CO2-rich condensate is recycled to the RWGS section without being subjected to compression.

15. 15. The method according to claim 13 or 14, wherein the CO2-depleted syngas stream is subjected to processing in a synthesis stage downstream of the cryogenic CO2 separation section.

16. 16. The method of claim 15, wherein the synthesis stage comprises a synthetic fuels synthesis section, an alcohol synthesis section or an olefins synthesis section.

17. 17. The method of claim 16, wherein the synthesis stage comprises a synthetic fuel synthesis section, and wherein the synthesis stage further comprises a Fischer-Tropsch (FT) section upstream of the synthetic fuel synthesis section.

18. The method according to any one of claims 15 to 17, wherein the CO2-depleted syngas stream is not subjected to compression.

19. The CO2-depleted syngas stream is in the range of 1.8 to 2.2 (H ２ -CO ２ ) / (CO + CO ２ 19. The method according to claim 15, wherein the synthesis stage comprises a methanol synthesis section.

20. The method of any one of claims 15 to 18, wherein the synthesis stage comprises a Fischer-Tropsch synthesis reactor system for the production of crude oil and / or wax.

21. The CO2-depleted syngas stream has a CO+H ２ ) / (CO ２ +H ２ The method according to any one of claims 15 to 18, further comprising a module of:

22. The CO2-depleted syngas stream has a H ２ The method according to any one of claims 15 to 18, wherein the ratio of

23. The method of any one of claims 13 to 22, wherein both the reverse water gas shift reaction and the methanation reaction occur in the RWGS section.

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