Carbon dioxide conversion to low carbon hydrogen and hydrogen derivatives

Abstract

The present invention relates to a method and a system for producing hydrogen and / or hydrogen derivatives by capturing carbon dioxide (CO2), converting the captured CO2 to carbon monoxide (CO) and producing hydrogen (H2) and hydrogen derivatives.

Description

[0001] February 20, 2025 Abu Dhabi National Oil Company A175428WO MAJ / Kta

[0002] CARBON DIOXIDE CONVERSION TO LOW CARBON HYDROGEN AND HYDROGEN DERIVATIVES

[0003] 5 FIELD OF THE INVENTION

[0004] The present invention relates to a method and a system for producing low carbon hydrogen and low carbon hydrogen derivatives by capturing carbon dioxide (C02), converting the captured C02to carbon monoxide (CO) and producing low carbon o hydrogen (H2) and hydrogen derivatives.

[0005] BACKGROUND

[0006] Traditional hydrogen production relies on fossil fuels like natural gas and emits a 5 significant amount of C02. This process currently accounts for around 900 million tons of C02per year globally. By shifting to so-called low-carbon hydrogen, emissions from hydrogen production itself can be reduced. Low-carbon hydrogen is hydrogen produced with little to no greenhouse gas emissions and thus has a smaller carbon footprint than conventional hydrogen. Low-carbon hydrogen can be produced using several methods, 0 each aimed at reducing carbon emissions compared to traditional so-called “gray” hydrogen which is produced from fossil fuels without capturing C02.

[0007] For example, so called green hydrogen can be produced via electrolysis, wherein water is split into hydrogen and oxygen using electricity. The key to making this process low- 5 carbon is using renewable energy sources like wind, solar or hydropower to fuel the electrolysis. This process, however, is relatively expensive because of the high cost of renewable electricity. One challenge of low carbon hydrogen production lies in its upscale production in order to make it economically competitive with other methods.

[0008] 0 In this context, WO 2009065577 Al relates to a grid-connected power plant, with inter alia an electrochemical or solar-thermal H2synthesis system for the operating system.Another approach for producing low carbon hydrogen is the production of so-called blue hydrogen which is produced from natural gas through steam methane reforming (SMR) or autothermal reforming (ATR). In both processes, methane (CH4) reacts with steam to produce hydrogen and C02. However, to make this process low carbon, the C02is captured and stored underground using carbon capture and storage (CCS) technology. Blue hydrogen is considered a bridge solution because it leverages existing infrastructure for natural gas. However, one disadvantage of this process is that undesired leakage of captured C02can occur. Another disadvantage is that in case the capture rate is low, the environmental benefits are significantly reduced. Furthermore, there are concerns about methane leaks during natural gas extraction which is not desired due to environmental reasons.

[0009] A further approach for low carbon hydrogen production is based on methane pyrolysis, which splits natural gas into hydrogen and solid carbon. This process avoids releasing C02, making it a low-carbon method. This so-called turquoise hydrogen is still in the early stages of development. While the technology is promising, large-scale synthesis and application is yet limited. The main disadvantage in the process of turquoise hydrogen is that solid carbon needs to be managed or repurposed.

[0010] In this context, WO 2023 / 014397 Al concerns the efficient production of low-carbon methanol, ethanol or mixtures of methanol and ethanol from captured C02and renewable H2at a generation site.

[0011] An object of the present invention is therefore the provision of an improved method and a system in order to at least partially overcome all or some of the above-mentioned problems of the prior art.

[0012] SUMMARY OF THE INVENTION

[0013] The above-outlined problems are addressed by the aspects of the present invention.

[0014] According to a first aspect of the invention, a method is provided for producing hydrogen and / or hydrogen derivatives, the method comprising

[0015] capturing carbon dioxide (C02) from a source comprising C02;converting the captured C02via electrolysis thereby producing a gas comprising carbon monoxide (CO) and / or a mixture of carbon monoxide and C02;

[0016] producing hydrogen (H2) using a water gas shift reaction from the gas; and

[0017] producing hydrogen derivatives using the produced hydrogen.

[0018] The “source” for capturing C02may be understood as any C02containing stream, such as for example air. Preferably, the source for capturing C02may be a C02rich stream.

[0019] The terms “gas” or “produced gas” according to the invention is to be understood for example as a gas comprising a significant amount of CO. Oxygen is produced during the step of the C02conversion from the captured C02. The produced gas may comprise the CO in a mixture together with C02.

[0020] The method of the present invention offers a novel method and system for producing low carbon H2and its derivatives from non-fossil-based sources, achieving cost competitiveness through the relatively low energy required per kg of low carbon H2produced. Moreover, the method of the present invention offers numerous advantages in terms of environmental impact, energy security, and economic growth. The economic and technological advantages of the downstream applications, such as for example NH3, CH4, MeOH and DME are highly dependent on the efficiency and costeffectiveness of the H2production process. By using the method according to the invention, low carbon production of H2and its derivatives is provided in a efficient manner. Accordingly, the present method drastically reduces C02emissions compared to traditional methods like steam methane reforming (SMR), where carbon dioxide is released into the atmosphere. Traditional hydrogen production methods like SMR produce significant CO2 emissions. The method provides a beneficial impact on the climate.

[0021] The method according to the present invention can drastically reduce greenhouse gas emissions. Thus, the inventive method can be used to produce hydrogen as a clean energy source in e.g. sectors that are difficult to electrify, such as for example steel manufacturing, cement production, and heavy transport (e.g. for shipping or aviation), thus helping to reduce the overall carbon footprints in these sectors. Furthermore, lowcarbon hydrogen and its derivatives reduce the dependence on fossil fuels and help diversify energy sources, contributing to enhanced energy security.

[0022] Furthermore, the method according to the invention is ecological, as C02is efficiently captured from the source e.g. air and further utilized in a cost-effective and efficient manner. In particular, the method utilizes a novel system and feedstock material which is economically competitive due to its low costs and efficiency compared to traditional methods. Moreover, traditional approaches contribute to harmful air pollutants (e.g., NOx, SOx, particulate matter). Low carbon hydrogen and its derivatives according to the inventive method can be used as energy carriers or in transport, which lead to cleaner combustion and reduced air pollution.

[0023] Moreover, by harnessing the captured C02, the method provides not only for an ecological value, but also an economical as the captured C02may be monetized.

[0024] Furthermore, the method represents a cost-effective method for low carbon H2production and derivatives. The method according to the present invention aims to offer a new platform for low carbon hydrogen and its derivatives. Low carbon hydrogen production according to the invention significantly supports the achievement of international climate targets, by promoting deep decarbonization across sectors.

[0025] The hydrogen derivatives may be one or more of methane (CH4), ammonia (NH3), urea, alcohol, methanol (CH3OH), dimethyl ether (DME) or any combination thereof.

[0026] Due to the efficient method for producing hydrogen, the low carbon production of hydrogen derivatives, such as ammonia, methanol, alcohol, DME and the like is also provided in an efficient manner which offers numerous advantages from environmental, economic, and energy perspectives.

[0027] Hydrogen derivatives are crucial for decarbonizing industries that are challenging to electrify, such as for example chemical production. Hydrogen derivatives can act as energy carriers or storage mechanisms. For example, excess hydrogen can be converted into hydrogen derivatives and stored for later use.

[0028] Producing hydrogen derivatives may comprise producing methane (CH4) using the produced hydrogen and carbon monoxide from the produced gas and / or producingammonia (NH3) using the produced hydrogen and N2and / or producing mixed alcohol and / or methanol and / or DME using the produced H2and CO and C02from the produced gas.

[0029] By reusing the low carbon hydrogen produced by the method of the present invention, which is produced from captured C02, low carbon hydrogen derivatives can be produced in a desirable economic and ecological manner.

[0030] In other words, these derivatives that maybe used as fuels are manufactured by combining low carbon hydrogen with captured C02. This approach offers a sustainable alternative to traditional fossil fuels. Accordingly, the hydrogen derivatives according to the present invention for example are used as synthetic fuels and are produced from captured carbon. This enables a circular carbon economy where C02emissions are reused which results in a potentially carbon-neutral cycle. By using captured carbon from e.g. industrial processes in the method of the present invention, hydrogen derivatives as e.g. synthetic fuels or chemicals are produced. This reduces the overall waste and contributes to a more sustainable process.

[0031] For example, hydrogen derivatives according to the present invention may help for example stabilizing energy grids by absorbing surplus energy and releasing it during demand spikes or when renewables are not generating power. Moreover ammonia is a key ingredient in e.g. fertilizers. When producing it from low carbon hydrogen according to the method of the present invention, C02emissions in the agricultural sector are reduced. Furthermore, methanol which derives from low carbon hydrogen produced by the method of the present invention can be used as a cleaner fuel as conventional MeOH.

[0032] Producing of ammonia (NH3) using the produced H2and N2may comprise producing urea using the produced NH3and C02from the produced gas.

[0033] By using the method according to present invention, in the production of low carbon urea, the C02emissions compared to conventional urea production are reduced.

[0034] Accordingly, the method for producing urea significantly helps in reducing carbon dioxide footprint. By doing so, an improved energy-efficient process is provided whichleads to a reduced environmental impact. The method for producing may use nitrogen from e.g. soil, which in turn reduces nitrous oxide emissions. The latter is a potent greenhouse gas associated with traditional fertilizers. In this manner, the method for producing low carbon urea may prevent excessive nitrogen buildup which helps in maintaining healthier soils and promotes sustainable agriculture practices.

[0035] The C02conversion may be performed using plasma type reactor e.g. gilding, micro wave, electrolysis cell unit selected from the group comprising: a solid oxide electrolysis cell (SOEC), an alkaline C02reduction cell or any combinations thereof.

[0036] The electrolysis cell units according to the present invention have the potential for producing green energy solutions when powered by e.g. renewable electricity, and SOEC electrolyzers can generate hydrogen with no direct carbon emissions, while e.g. alkaline C02reduction cells help to capture and convert C02into valuable products. This directly reduces the amount of atmospheric C02. Accordingly, the CO2 converter units play crucial roles in reducing the carbon footprint, i.e. in sectors such as power generation, transportation, and heavy industry by enabling cleaner hydrogen production and C02utilization.

[0037] Typically, these C02converter units exhibit quick startup and shutdown times, which makes them ideal for integration with e.g. intermittent renewable energy sources such as wind and solar power. The C02converter units operate efficiently at low current densities and lead to better energy-to-hydrogen conversion rates compared to other electrolysis methods.

[0038] In high-temperature electrolysis for example by using SOECs, part of the energy required to split C02to CO and oxygen is supplied as heat. This reduces the amount of electrical energy needed in this step. This improves overall system efficiency which makes low-carbon hydrogen production more energy-efficient.

[0039] Gliding arc plasma reactor comprises a plasma arc gliding across electrodes, comprising a highly energetic environment. In this manner, CO2 molecules are split into carbon monoxide (CO), oxygen (O), or other intermediate species. The gliding arc allows for continuous operation, making it suitable for large-scale applications.Microwave plasma reactors comprise microwave radiation for e.g. generating a high-temperature plasma capable of breaking down e.g. CO2 molecules. The microwave radiation comprises gas molecules, creating a plasma wherein ions and radicals may be produced.

[0040] The method may further comprise preheating and mixing with steam the produced gas after the C02converter (C02conversion) unit before producing hydrogen.

[0041] In this manner, the produced gas in the method of the present invention is heated by the steam. This has the advantage of providing higher temperatures, which accelerate the kinetics of the subsequent reactions. In this manner, a faster hydrogen generation is provided while reducing energy losses within the overall process.

[0042] The WGS process may be performed using a low temperature (LTS), medium temperature (MTS), high temperature (HTS), iso-thermal (iso-shift) water as shift reactor (WGS) or any combination thereof, preferably a MTS reactor.

[0043] The WGS reactors according to the present invention enhance the method of hydrogen production, while maximizing its efficiency and balancing reaction kinetics and thermodynamics of the WGS reaction. It is conceivable that the WGS reactors according to the present invention are part of integrated processes where the heat which is generated in high-temperature stages (HTS) is reused in other parts of the process. This improves the overall efficiency of the method. Each WGS reactor type may be optimized for a specific catalytic performance. The HTS reactor may use ironbased catalysts. This has shown improved overall operation efficiency. The LTS reactor may use copper-based catalysts, which has shown improved efficiency at lower temperatures. Any combination of reactors is conceivable and may be implemented. For example, the HTS reactor may be followed by the LTS reactor. In this manner, the strengths of different catalysts are maximized, and the conversion and the hydrogen yield are enhanced.

[0044] The method may further comprise separating and / or purifying the produced hydrogen.When separating and purifying the hydrogen produced according to the method of the present invention, the subsequently purified hydrogen leads to better and more consistent performance in downstream applications. In this manner, the recovery of the maximum amount of the hydrogen from the reaction mixture is ensured while minimizing the total waste amount and improving the overall yield of the produced hydrogen.

[0045] The produced hydrogen may be purified using pressure swing adsorption (PSA), membrane filtration, cryogenic distillation, chemical looping, metal hydride separation or any combination thereof.

[0046] These specific purification methods of the present invention have the advantage of providing an energy-efficient process while efficiently separating the gases within the method and purifying the produced hydrogen. In particular PSA, membrane filtration, and cryogenic distillation may be especially effective in separating gases e.g. like hydrogen, oxygen, nitrogen, or CO2, while chemical looping and metal hydrides maybe used for hydrogen separation. Any combination of these purification methods is conceivable and may be implemented.

[0047] The method may further comprise separating CO and / or C02from the product of the WGS process in a CO and / or C02separation system. The method may further comprise recycling back separated C02from the C02separation system to the step of C02conversion unit / reactor.

[0048] When separating and recycling according to the method of the present invention, the overall C02demand is reduced which minimizes waste generation and decreases the environmental impact associated with the extraction and processing of newly captured C02. This further helps to reduce greenhouse gas emissions. In particular, recycling requires less energy compared to the capture of C02and production of CO, which leads to a more energy-efficient process overall.

[0049] The method may further comprise the step of producing steam and subjecting the same to the WGS process; and a step of heating the product of the WGS process using said steam in a heat exchanger prior to subjecting said steam to the WGS process.In this manner, an energy efficient method is provided by reusing heat within the process. By recovering heat from the steam less energy is desirably needed for heating the overall process, leading to higher overall energy efficiency.

[0050] The method may further comprise the step of compressing the product of the WGS process before producing hydrogen derivatives.

[0051] In this manner, the compressed product gas can mix more uniformly in the process of producing hydrogen derivatives. Furthermore, compressing the product of the WGS reactor leads to more efficient use of starting materials, while reducing waste and minimizing costs.

[0052] The method may further comprise isolating the hydrogen derivative after producing the same.

[0053] In this manner, unreacted starting materials, byproducts, and impurities are removed which provides a purer hydrogen derivative. Furthermore, subsequent storage of the hydrogen derivative produced according to the method of the present invention is simplified while enhancing its stability as compared in a non-isolated product in the reaction mixture.

[0054] The method may further comprise the step of pre-heating the product of the WGS process before the step of isolating the hydrogen and producing hydrogen derivatives.

[0055] By doing so, the required conditions of the WGS reaction are efficiently met. Preheating the product of the WGS reactor enhances achieving these conditions quickly which promotes better kinetics in the subsequent production of the hydrogen derivatives.

[0056] The method may further comprise the step of cooling the product stream from the step of producing ammonia (NH3); and / or may further comprise the step of separating the NH3from the product stream from the step of producing NH3thereby providing a residual gas essentially free of NH3; and wherein said residual gas may comprisehydrogen; and may further comprise the step of compressing and heating the residual gas and subjecting the same to the step of producing NH3.

[0057] The method may further comprise the step of heating the product stream from the step of producing methane (CH4) in a heat exchanger and separating condensate comprising water from the heated product stream from the step of producing CH4; and / or may further comprise the step of separating CH4from the product stream from the step of producing CH4thereby providing a residual gas essentially free of CH4; and / or wherein said residual gas may comprise one or more of hydrogen, CO and C02; and / or may further comprise the step of compressing and heating said residual gas and subjecting the same to the step of producing CH4using the produced hydrogen and carbon monoxide from the produced gas.

[0058] The method may further comprise the step of heating the product stream from the step of producing mixed alcohol and / or methanol and / or DME in a heat exchanger; and / or may further comprise the step of separating the heated mixed alcohol and / or methanol and / or DME from said product stream thereby providing a residual gas essentially free of mixed alcohol and / or methanol and / or DME; and wherein said residual gas may comprise one or more of hydrogen, CO and C02; and / or may further comprise the step of compressing and heating said residual gas and subjecting the same to the step of producing mixed alcohol and / or methanol and / or DME.

[0059] Separating condensate helps in obtaining purer products by removing contaminants, unreacted starting materials, and byproducts. Furthermore, isolating condensate simplifies the subsequent process wherein separated materials are required.

[0060] Cooling ammonia helps reducing its vapor pressure, decreasing the risk of exposure and making it safer to handle. Furthermore, cooling ammonia increases its density, which is advantageous for storage and subsequent handling such as transport. In this manner, denser ammonia is provided which occupies less volume, allowing for more efficient use of space e.g. in storage tanks.

[0061] By recycling the residual gases, the overall yield of the hydrogen derivative production is drastically improved. This practice ensures that less material is abandoned whilemaximizing the efficiency of the reaction. Moreover, this process of “recycling” allows for the reuse of valuable reactants, which reduces the need of producing new materials. This leads to substantial cost savings, especially when the method according to the present invention is used in a large-scale industrial process.

[0062] According to a second aspect of the invention, a system for producing H2and hydrogen derivatives is provided comprising a C02capture unit configured for capturing C02from a source; a C02converter unit configured for converting captured C02into CO and / or a mixture of CO and C02thereby producing a gas, a WGS reactor configured for producing hydrogen from the produced gas via water gas shift reaction; a second reactor configured for producing hydrogen derivatives using the produced H2.

[0063] The “second reactor” for producing hydrogen derivatives may be understood for example as a reactor capable of synthesizing the hydrogen derivatives. It is conceivable that a combination of more than one second reactor may be implemented in the system of the present invention.

[0064] The C02converter unit may be configured for converting captured C02into CO and / or a mixture of CO and C02via plasma and / or electrolysis thereby producing the gas.

[0065] The C02capture unit according to the invention may be for example a solvent based unit or sorbent-based technology.

[0066] The many advantages discussed in the context of the first aspect of the present invention apply also to the system. In particular, by implementing the inventive method according to the invention into the inventive system, the numerous advantages in terms of environmental impact, energy security, and economic growth are synergistically enhanced. This is due to the specifically designed system, which allows the efficient production of low carbon production of H2and its derivatives. In this manner, a cost-efficient and improved system is provided. The present system thus also helps to reduce C02emissions and provides an impact on the overall climate.

[0067] The second reactor for producing hydrogen derivatives may be configured for producing methane (CH4) using the produced hydrogen and carbon monoxide from theproduced gas; or wherein the second reactor may be configured for producing ammonia (NH3) using the produced hydrogen and N2; or wherein the second reactor is configured for producing mixed alcohol and / or methanol and / or DME using the produced hydrogen and carbon monoxide and C02from the produced gas.

[0068] The second reactor may be configured for producing urea from the ammonia produced from the second reactor configured for producing ammonia.

[0069] As explained in the context of the first aspect of the invention, ammonia and urea produced by the present invention act as an improved energy carrier and means for storage. For example, excess hydrogen is converted into hydrogen derivatives and subjected for storage for later processing. By reusing the low carbon hydrogen produced according to the invention, the subsequent low carbon hydrogen derivatives are produced in a desirable cost-efficient and ecologically valuable manner.

[0070] By using the system according to present invention, the production of low carbon ammonia and urea is reduced as well as C02emission compared to conventional ammonia and urea production. By doing so, an improved energy-efficient process for producing ammonia and urea is provided which leads to a reduced carbon dioxide footprint. The system for producing ammonia and urea may use nitrogen from any source. In this manner, by using the second reactor for producing low carbon ammonia or urea may prevent excessive nitrogen buildup, helping in maintaining e.g. healthier soils and thus promoting sustainable agriculture practices.

[0071] The C02converter unit may be selected from the group comprising: a plasma type reactor, a solid oxide electrolysis cell (SOEC), an alkaline C02reduction cell or any combinations thereof.

[0072] The C02converter units according to the present invention enhance the overall efficiency of the system. Furthermore, the C02converter unit may be powered by renewable electricity. Plasma and / or SOEC electrolyzers generate carbon monoxide with no direct carbon emission. This helps capturing and converting C02. Accordingly, the C02converter units used in the system of the resent invention reduce the carbonfootprint by enabling clean carbon monoxide and oxygen production and C0:utilization.

[0073] As explained in the context of the first aspect, these C02converter units exhibit quick startup and shutdown times. This enables their use with intermittent renewable energy sources e.g. like wind and solar power. The C02converter units operate efficiently due and leads to better energy-to-hydrogen conversion rates compared to other electrolysis methods.

[0074] The system may further comprise a mixing unit configured for mixing the produced gas with steam after the C02converter unit before the WGS reactor.

[0075] In this manner, the temperature of the produced gas is cooled while generating steam. This heating recovery improves the efficiency of the WGS reactor.

[0076] The WGS reactor may be a low temperature (LTS), medium temperature (MTS), high temperature (HTS), iso-thermal (iso-shift) water as shift reactor (WGS) or any combination thereof. The MTS reactor may be preferred.

[0077] The WGS reactors according to the present invention enhance the process of hydrogen production, while maximizing efficiency and balancing reaction kinetics and thermodynamics.

[0078] The many advantages for the WGS reactors explained in the context of the first aspect also apply for the WGS reactor of the system. It is conceivable that the WGS reactors according to the present invention are part of an integrated system unit wherein the generated heat in high-temperature stages (HTS) is reused in other parts of the system. This further improves the overall efficiency of the system. Each WGS reactor type may be optimized for a specific catalytic performance. Any combination of reactors is conceivable and maybe implemented. For example, the HTS reactor maybe followed by the LTS reactor. In this manner, the strengths of different catalysts are maximized, and the conversion and hydrogen yield is improved.The system may further comprise a purification unit configured for purifying the produced H2using pressure swing adsorption (PSA), membrane filtration, cryogenic distillation, chemical looping, metal hydride separation or any combination thereof.

[0079] In this manner, recovery of the maximum amount of the hydrogen from the reaction mixture is ensured while improving the overall yield.

[0080] These specific purification methods have the advantage of being energy-efficient and thus cost-efficient while effectively separating gases and purifying hydrogen. In particular PSA, membrane filtration, and cryogenic distillation are especially effective in separating gases like e.g. hydrogen, oxygen, nitrogen, or CO2. Chemical looping and metal hydrides are used for hydrogen separation. Any combination of these purification methods is conceivable and maybe implemented in the system.

[0081] The system may further comprise a separation system configured for separating CO and / or C02from the product of the WGS reactor.

[0082] Recycling C02minimizes waste generation within the system of the present invention which provides for a more efficient system. This further helps to reduce greenhouse gas emissions. In particular, recycling requires less energy compared to the capture of C02and production of CO, leading to a more energy-efficient process overall.

[0083] The system may further comprise a recycling line configured for feeding C02from the C02separation system to the C02converter unit.

[0084] Recycling of C02according to the present invention decreases the impact associated with the extraction and processing of newly captured C02.

[0085] The system may further comprise a heating unit configured for producing steam and subjecting the same to the WGS reactor; and a heat exchanger configured for heating the product of the WGS reactor using said steam prior to subjecting said steam to the WGS reactor.In this manner, an energy efficient system is provided. By reusing heat from the steam less energy is required for heating the overall system. This leads to higher overall energy efficiency of the system.

[0086] The system may further comprise a cooling unit configured for cooling the product stream from the second reactor for producing ammonia (NH3); and / or may further comprise a separation unit configured for separating the NH3from said product stream thereby providing a residual gas essentially free of NH3; and may further comprise a compression unit configured for compressing and heating said residual gas and subjecting the same to the second reactor for producing NH3.

[0087] The system may further comprise a heat exchanger configured for heating the product stream from the second reactor for producing methane (CH4); and a separation unit configured for separating condensate comprising water from said heated product stream; and / or may further comprise a separation unit configured for separating CH4from said product stream; and a recycle line configured for providing a residual gas essentially free of CH4; and / or may further comprise a compression unit configured for compressing and heating said residual gas and subjecting the same to the second reactor for producing CH4.

[0088] The system may further comprise a heat exchanger for heating the product stream from the second reactor for producing mixed alcohol and / or methanol and / or DME; and / or may further comprise a separation unit configured for separating the heated mixed alcohol and / or methanol and / or DME from said product stream thereby providing a residual gas essentially free of mixed alcohol and / or methanol and / or DME; and may further comprise a compression unit configured for compressing and heating said residual gas and subjecting the same to the second reactor for producing mixed alcohol and / or methanol and / or DME.

[0089] Separating condensate according to the present invention helps in obtaining purer hydrogen derivatives. Furthermore, isolating condensate simplifies the subsequent process wherein the separated materials are required.Cooling ammonia according to the present invention helps reducing its vapor pressure which decreases the risk of exposure and makes it safer to handle. Furthermore, cooling ammonia increases its density, which is advantageous for storage in the system and subsequent transport. In this manner, cooled ammonia allows for a more efficient use of space e.g. in storage tanks.

[0090] By recycling the residual gases, the overall yield of the hydrogen derivative is improved. In this manner, less material is wasted which maximizes the efficiency of the system.

[0091] The system may further comprise a separation unit for isolating hydrogen from the product of the WGS reactor.

[0092] When separating and purifying the hydrogen from the product of the WGS reactor, the subsequently purified hydrogen leads to better and more enhanced performance in downstream applications. Accordingly, recovery of the maximum amount of the hydrogen from the reaction mixture is ensured while minimizing waste and improving the overall yield of the system.

[0093] The system may further comprise a boiler unit for producing steam, and a line for transferring said steam to the WGS reactor; further comprising a heat exchanger configured for cooling the product of the WGS reactor while superheating the produced steam from the boiler unit.

[0094] By doing so, the heated steam is provided to the WGS reactor for producing hydrogen. The steam is further used to cool the product of the WGS reactor which is produced in the reactor. Accordingly, this arrangement provides for an efficient set-up that allows for reducing heat-loss and energy while enhancing the overall efficiency of the system.

[0095] The system may further comprise one or more recycle lines configured for recycling back unconverted starting materials to the C02converter unit, and / or to the WGS reactor and / or to the second reactor; wherein the recycle line of the one or more recycle lines may comprise preferably one or more heat exchangers and / or compression units.By recycling the unconverted starting materials, the overall yield of the hydrogen derivative is significantly improved. In this manner, less material goes to waste which maximizes the efficiency of the system.

[0096] The system may further comprise a storage unit configured for storing the produced hydrogen and / or produced hydrogen derivatives.

[0097] Storing products allows for better logistics and distribution management. Accordingly, bulk production followed by storage can lower production costs by optimizing manufacturing processes and reducing the frequency of production runs. This leads to an improved and energy-efficient system. Storing the produced hydrogen and hydrogen derivatives allows to scale up the system while ensuring a reliable supply of the produced hydrogen and hydrogen derivatives.

[0098] The system may further comprise a heating unit configured for heating the produced gas from the C02converter unit and / or the product of the WGS reactor and / or the product of the second reactor. The system may further comprise a compression unit configured for compressing the product of the WGS reactor prior to the second reactor.

[0099] In this manner, the heated and / or compressed product of the WGS reactor and / or C02converter unit and / or second reactor can mix more uniformly in the subsequent process. Furthermore, heating and compressing these products lead to more efficient use of starting materials, while reducing waste and thus minimizing costs.

[0100] The system may further comprise a heat exchanger configured for heating the product of the second reactor prior to the separation unit and comprising a recycle line configured for feeding the second reactor with unconverted starting material from said separation unit.

[0101] We emphasize that all aspects, features, and options discussed and disclosed above within the context of the first aspect may be applied to, or combined with, the discussion and disclosure of the second aspect, and vice versa, unless physically or technically ruled out, even if not every possible combination or sub-combination of features is explicitly spelled out in the following. The technical advantages of suchoptions and features that have already been discussed above are therefore not repeated, at least not to the same degree of detail, and reference is instead made to the corresponding explanations above, for conciseness.

[0102] SHORT DESCRIPTION OF THE FIGURES

[0103] Possible embodiments of the present invention are further described in the following detailed description with reference to the following figures:

[0104] Fig. 1: shows a flow chart of the method according to the invention.

[0105] Fig. 2: shows a schematic illustration of the system according to the invention.

[0106] Fig. 3: shows a preferred embodiment to produce ammonia.

[0107] Fig. 4: shows a preferred embodiment to produce DME / MeOH / alcohol.

[0108] Fig. 5: shows a preferred embodiment to produce methane.

[0109] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0110] Possible embodiments of the different aspects of the present invention and disclosure are described below. It is, however, once again emphasized that the different aspects may also be combined and are not limited to the specific embodiments set forth below.

[0111] Reference is further made to the fact that in the following only individual embodiments can be described in more detail. The skilled person will understand that the features and possible modifications described with reference to these specific embodiments may also be further modified and / or combined with one another in a different manner or in different sub-combinations, without departing from the scope of the present invention and disclosure. Individual features or sub-features may also be omitted if they are dispensable to obtain the desired result. In order to avoid redundancies, reference istherefore made to the explanations in the preceding sections, which also apply to the following detailed description.

[0112] Low-carbon hydrogen and low carbon hydrogen derivatives production

[0113] Fig. 1 presents a flowchart of the method 10 according to the invention. In step 105 of the method 10, C02is captured from a source. The C02is directly captured from air or from any C02rich stream. The carbon dioxide is separated using C02capturing technology, which is generally known to the skilled person.

[0114] In the next step of the method 10, step 110, the captured C02is used to produce CO via C02converter unit. The C02converter unit could be exemplary performed in a C02electrolysis cell using a solid oxide electrolysis cell (SOEC) or in plasma type reactor (gilding or microwave). The produced gas comprises a significant amount of CO.

[0115] However, in the produced gas, C02may be also present.

[0116] This produced gas is subjected to step 120, in which the hydrogen is produced using water gas shift reaction. In particular, the produced gas after C02converter unit is preheated and mixed with steam before producing hydrogen. The steam is provided by water via a Boiler feed water line (BFW). The steam is heated and compressed before entering the water gas shift reaction. In particular, the steam may advantageously also be used to heat the product of the WGS reaction, before the steam entering at step 120. The WGS reaction in step 120 is performed using a water as shift reactor (WGS). In step 120, the product of the WGS reaction is further compressed and pre-heated (by e.g., the steam as indicated above). Any unreacted CO and C02from the product of the WGS process is separated via a CO and C02separation system and is recycled back to the step of C02conversion and WGS reaction.

[0117] After step 120, unreacted gas is recycled back to the step of C02converion and the step of water gas shift reaction. By doing so, the overall efficiency of the method 10 is enhanced. In particular, the recycle mechanism provides for an energy- and resourceefficient method. The produced low carbon hydrogen is separated and isolated from the reaction mixture. Subsequently, the hydrogen is purified (not shown in Fig.i). For this pressure swing adsorption (PSA) and membrane filtration may be used.Subsequently, the low carbon hydrogen is used to produce a variety of different hydrogen derivatives in step 130, which will be described in the following. As can be seen in Fig. 1, the produced hydrogen is used for producing hydrogen derivatives, i.e. subjected to steps 140, 150, 160 and 170. These steps are performed in parallel or sequentially.

[0118] Low-carbon ammonia and urea production

[0119] In step 140, ammonia is produced using the produced low carbon hydrogen and N2via e.g. Haber-Bosch reaction. N2is captured from a N2source. For example, the N2 may be from flue gas, e.g. after the CO2 capture and / or from polishing and / or from a separate stream.

[0120] Any unreacted material, such as H2and N2, is recycled back to the step 160 of producing ammonia and to the step of producing hydrogen 120. The produced ammonia is separated and purified. In this manner, a residual gas is obtained which comprises N2and H2. Said residual gas is reused in the step of producing ammonia. For doing so, the residual gas is compressed and heated and subjected to step 140. The produced ammonia is cooled and stored in a cooling train.

[0121] In step 150 for producing urea, low carbon ammonia and the captured C02is used, e.g. in a Bazarov reaction. The reactants are compressed and heated (not shown in Fig. 1). The produced low carbon urea is then further processed, i.e. separated, purified and stored. Any unreacted material, i.e. residual gas after separating the desired urea, is recycled back to the step of producing urea.

[0122] Low-carbon methane production

[0123] In Fig. 1, the produced hydrogen from step 120 is subjected to step 160, in which low-carbon methane is produced. For doing so, the hydrogen and CO from the produced gas are used, providing low carbon methane and / or synthetic methane. The produced methane is separated from the mixture, purified and stored. By doing so, a residual gas is obtained, which comprises CO and C02. Said residual gas is compressed, heated and recycled back to the step of producing methane 160.Low-carbon alcohols and ethers

[0124]

[0125] The produced hydrogen of step 120 is subjected to step 170, for producing mixed alcohol, DME and methanol. For producing these derivatives, CO and C02from the produced gas and the low carbon hydrogen are used. In this manner, low carbon alcohol, DME and methanol are produced. The produced low carbon alcohol, DME and methanol are separated from the product of step 170 and purified and stored. The residual gas, which is obtained after separating the low carbon alcohol, DME and methanol comprises CO and C02, which is reused. In particular, said residual gas is recycled back to step 170. For doing so, the residual gas is compressed and heated before entering step 170.

[0126] It is noted that the residual gas obtained in any of steps 140, 150, 160 and 170 is subjected to the step of producing hydrogen 120.

[0127]

[0128] In Fig. 2, an illustration for the system 100a for producing H2and hydrogen derivatives is shown. System 100a comprises a C02capture unit 20a, which captures C02from a source containing C02. The C02separation unit uses C02capture technology (inclusive and not limited). The C02separation unit maybe solvent based and / or solid sorbent based. As can be seen, the system 100a comprises a line from the C02capture unit to the C02converter unit 30a. Alternating current is provided by the unit 25a and the electrolysis cell unit converts captured C02into CO and a mixture of CO and C02. The C02converter unit 30a is a solid oxide electrolysis cell (SOEC). This gas which is produced in the C02converter unit 30a is used for producing hydrogen.

[0129] In the system 100a, water is provided from the Boiler Feed Water (BFW) line 35a, which feeds the boiler unit 22a, producing steam, and also the WGS reactor 40a. The system further comprises a heat exchanger 45a arranged between the C02converter unit 30a, the boiler unit 22a and before the WGS reactor 40a. In Fig. 1, after the heat exchanger 45a, steam and produced gas from the C02capture unit 30a are mixed atmixing unit 26a. At point 26a’ the mixed components from mixing unit 26a are further mixed with steam at point 26a’.

[0130] As can be seen in Fig.2, system 100a comprises a further line feeding the heat exchanger 60a with the product of the WGS reactor 40a and steam, for transferring heat between the product and the steam. In Fig. 2, the product exits the heat exchanger 60a and is than subjected to the compression unit 52a. Afterwards, hydrogen is separated from said product stream in the H2separation unit 55a. The hydrogen may further be purified in a purification unit (not shown in Fig.2) using pressure swing adsorption (PSA) and membrane filtration.

[0131] Furthermore, in the separation system 55a CO and C02is separated from the product of the WGS reactor. Via recycle line 65a, the separated CO and C02is reused in the C02converter unit 30a. Another recycle line may be arranged between the separation system 55a and the WGS reactor 40a (not shown in Fig. 2), to lead separated CO and C02back to the WGS reactor 40a.

[0132] In general, the system 100a comprises one or more recycle lines arranged within the system for recycling back unconverted starting materials to any of the units of the system 100. These recycle lines may pass heat exchangers and compression units before being reused. The produced hydrogen is subjected to the second reactor (not shown in Fig.2) for producing hydrogen derivatives which will be described in more detail with reference to Figs. 3 to 5- In particular, the system 100 for producing ammonia (Fig. 3), CH4(Fig. 4) and mix alcohol / MeOH / DME (Fig. 5) is shown.

[0133] System for producing low carbon ammonia and urea

[0134] The system 100a as shown in Fig. 2 is part of the system 100b of Fig. 3. The differences occur only after the H2separation system 55a. To avoid redundancies, in the following only the differences to the described arrangements of Fig. 2 are described in detail. Identical reference numbers are used for identical items, differentiated by different letters in the different figures (like e.g., WGS reactor 40a in Fig. 2; WGS reactor 40b in Fig. 3; WGS reactor 40c in Fig. 4, etc.). The same observations apply for the systems shown in Figs. 4 and 5.In Fig. 3, the produced hydrogen after the separation system 55b is mixed with a nitrogen source and afterwards subjected to a compression unit 75b. After compression unit 75b, the compressed mixture is lead to a mixing unit 77b before entering the second reactor 50b for producing ammonia. The system 100b of Fig. 3 comprises a cooling unit 61b, in which the produced ammonia from the second reactor 50b is cooled. Furthermore, as can be seen in Fig. 3, the system 100b comprises a separation unit 62b configured for separating the NH3from said product stream. The residual gas is subjected via line 80b to a compression unit 82b wherein the residual gas is compressed (and heated). Subsequently, the compressed residual gas is fed to a mixing unit 77b, where it is mixed with the hydrogen / nitrogen mixture from the compression unit 75b. This mixture is subjected to the second reactor 50b for producing NH3. The produced ammonia is stored in the storage unit 70b. The produced ammonia may subsequently be used for the synthesis of low carbon urea (not shown in Fig. 3).

[0135]

[0136] methane

[0137] The system 100a as shown in Fig. 2 is also used in the system 100c of Fig. 4. To avoid redundancies, only differences to the describes arrangements are explained in the following with respect to the description of Fig 2, i.e., only the additional steps / systems following the H2separation unit 55b / c.

[0138] In Fig. 4, the separation unit 55c is a separator unit. For example the separation unit may comprise a spray nozzle. However, any gas liquid contact system or solid adsorbent system may be used in this regard. The system 100c comprises a further heater 76c after the compression unit 75c prior to the second reactor 50c for producing CH4. The product stream from the second reactor is heated in heat exchanger 61c and heater 62c. The separation unit 63c separates process condensate from the product stream exiting second reactor 50c. The process condensate is stored in storage unit 70c. The system 100c comprises a separation unit 55c for separating CH4which is further processed and stored (not shown in Fig. 4). The remaining components, in particular separated hydrogen and CO, are recycled back via line 80c and compressed in the compression unit 82c before being transferred to the heat exchanger 61c. After exitingthe heat exchanger 6ic, the remaining components are mixed in the mixing unit 77c with the product from separation system 55c.

[0139]

[0140] alcohols, MeOH and ethers

[0141] In Fig. 5 and just like in Fig. 4, the separation unit 55b is a separator using a spray nozzle. However, any gas liquid contact system or solid adsorbent system may be used in this regard. The system comprises a heat exchanger 6id and a heater 62d for heating the product stream from the second reactor sod. A separation unit 63d separates the heated alcohol and methanol and DME product, which is than stored in storage unit 70d. The residual gas from the separation unit 63d is transferred via line 8od to a compressor 82d. Afterwards, the compressed residual gas is passed through the heat exchanger 6id and transferred to mixing unit 77b, where it is mixed with the gas from the separation system 55b and reused in the second reactor sod.

[0142] It is to be noted that the above-described process steps are applicable to any hydrogen derivative using low carbon H2, C02, CO and other reactants. Moreover, the invention is not restricted to the described sequence of each step of the method and unit in the system but may comprise a sequential or parallel arrangement of the method steps / units of the system.

[0143] It is further noted that the above embodiments and / or examples may be combined with further aspects as described herein and details of the embodiments and / or examples may also be omitted, as will be understood by the skilled person. The scope of protection is determined by the claims and is not limited by the embodiments and / or examples disclosed in the above figures.

Claims

February 20, 2025 Abu Dhabi National Oil Company A175428WO MAJ / Kta CLAIMS1. A method (10) for producing hydrogen and / or hydrogen derivatives, the method comprising:capturing (105) carbon dioxide (C02) from a source comprising C02; 5 - converting (110) the captured C02to a gas comprising carbon monoxide (CO) and / or a mixture of carbon monoxide and C02;producing (120) hydrogen (H2) using a water gas shift reaction from the gas; andproducing (130) hydrogen derivatives using the produced hydrogen.

02. The method of claim 1, wherein hydrogen derivatives are one or more of methane (CH4), ammonia (NH3), urea, alcohol, methanol (CH3OH), dimethyl ether (DME) or any combination thereof.5 3. The method of claims 1 or 2, wherein producing hydrogen derivatives comprises producing methane (CH4) using the produced hydrogen and carbon monoxide from the produced gas (160); and / or producing ammonia (NH3) using the produced hydrogen and N2(140); and / or producing mixed alcohol and / or methanol and / or DME using the produced H2and CO and C02from the produced gas (170).

04. The method of claim 3, wherein after producing of ammonia (NH3) using the produced H2and N2(140): producing urea using the produced NH3and C02from the produced gas (150).5 5. The method of any of the preceding claims, wherein converting is performed using a C02converter comprising a plasma type unit and / or an electrolysis cell unit selected from the group comprising: a solid oxide electrolysis cell (SOEC), a gliding arc plasma reactor (GAP), an alkaline CO2reduction cell or any combinations thereof, preferably a solid oxide electrolysis cell (SOEC) and / or a gliding arc plasma reactor 0 (GAP).

6. The method of any of the preceding claims, further preheating (102) and mixing with steam the produced gas after electrolysis before producing hydrogen.

7. The method of any of the preceding claims, wherein the WGS process is performed using a low temperature (LTS), medium temperature (MTS), high temperature (HTS), iso-thermal (iso-shift) water as shift reactor (WGS) or any combination thereof, preferably a MTS reactor.

8. The method of any of the preceding claims, further separating and / or purifying (125) the produced hydrogen.

9. The method of any of the preceding claims, wherein the produced hydrogen is purified (125) using pressure swing adsorption (PSA), membrane filtration, cryogenic distillation, chemical looping, metal hydride separation or any combination thereof.

10. The method of any of the preceding claims, further separating CO and / or C02from the product of the WGS process in a CO and / or C02separation system (117).

11. The method of claim 10, further recycling back separated C02from the C02separation system to the step of C02conversion.

12. The method of any one of the preceding claims, further comprising the step of producing steam and subjecting the same to the WGS process; and a step of heating the product of the WGS process using said steam in a heat exchanger prior to subjecting said steam to the WGS process (141a, 151a, 161a, 171a).

13. The method of any one of the preceding claims, further comprising the step of compressing the product of the WGS process before producing hydrogen derivatives (141b, 151b, 161b, 171b).

14. The method of any one of the preceding claims, further isolating the hydrogen derivative after producing the same (143, 153, 163, 173).15- The method of the preceding claim, further comprising the step of pre-heating the product of the WGS process (142, 152, 162, 172) before the step of isolating the hydrogen (143, 153, 163, 173) and producing hydrogen derivatives (130).

16. The method of any one of the preceding claims in combination with claim 3, further comprising the step of cooling the product stream from the step of producing ammonia (NH3) (145);further comprising the step of separating the NH3from the product stream (147) from the step of producing NH3thereby providing a residual gas essentially free of NH3; andwherein said residual gas comprises hydrogen; andfurther comprising the step of compressing and heating the residual gas (148) and subjecting the same (149) to the step of producing NH3.

17. The method of any one of the preceding claims in combination with claim 3, further comprising the step of heating the product stream from the step of producing methane (CH4) in a heat exchanger (165) and separating condensate comprising water from the heated product stream (166) from the step of producing CH4;further comprising the step of separating CH4from the product stream (167) from the step of producing CH4thereby providing a residual gas essentially free of CH4;wherein said residual gas comprises one or more of hydrogen, CO and C02; further comprising the step of compressing and heating said residual gas (168) and subjecting the same to the step of producing CH4(169) using the produced hydrogen and carbon monoxide from the produced gas.

18. The method of any one of the preceding claims in combination with claim 3, further comprising the step of heating the product stream from the step of producing mixed alcohol and / or methanol and / or DME in a heat exchanger (175);further comprising the step of separating the heated mixed alcohol and / or methanol and / or DME from said product stream (177) thereby providing a residual gas essentially free of mixed alcohol and / or methanol and / or DME; andwherein said residual gas comprises one or more of hydrogen, CO and C02; andfurther comprising the step of compressing and heating said residual gas (178) and subjecting the same to the step of producing mixed alcohol and / or methanol and / or DME (179).

19. A system (100) for producing H2and hydrogen derivatives, the system comprising:a C02capture unit configured for capturing C02from a source (20a, 20b, 20c, 2od);a C02converter unit configured for converting captured C02into CO and / or a mixture of CO and C02thereby producing a gas (30a, 30b, 30c, 3od),a WGS reactor configured for producing hydrogen from the produced gas via water gas shift reaction (40a, 40b, 40c, 40d);a second reactor configured for producing hydrogen derivatives using the produced H2(50a, 50b, 50c, 50d).

20. The system (100) of claim 19, wherein the second reactor for producing hydrogen derivatives is configured for producing methane (CH4) using the produced hydrogen and carbon monoxide from the produced gas (140a);or wherein the second reactor is configured for producing ammonia (NH3) using the produced hydrogen and N2(140b);or wherein the second reactor is configured for producing mixed alcohol and / or methanol and / or DME using the produced hydrogen and carbon monoxide and C02from the produced gas (140c).

21. The system of any of claims 19 or 20, wherein the C02converter unit is selected from the group comprising: a solid oxide electrolysis cell (SOEC), an alkaline C02reduction cell, plasma type unit or any combinations thereof.

22. The system of any of claims 19-21, further comprising a mixing unit (26a, 26b, 26c, 28d) configured for mixing the produced gas with steam after the C02converter unit before the WGS reactor.

23. The system of any of claims 19-22, wherein the WGS reactor is a low temperature (LTS), medium temperature (MTS), high temperature (HTS), iso-thermal (iso-shift) water as shift reactor (WGS) or any combination thereof.

24. The system of any of claims 19-23, further comprising a purification unit configured for purifying the produced H2using pressure swing adsorption (PSA), membrane filtration, cryogenic distillation, chemical looping, metal hydride separation or any combination thereof.

25. The system of any of claims 19-24, further comprising a separation system (55a, 55b, 55c, 55b) configured for separating CO and / or C02from the product of the WGS reactor.

26. The system of the preceding claim, further comprising a recycling line (65a, 65b, 65c, 65b) configured for feeding C02from the C02separation system to the C02converter unit.

27. The system of any of claims 19-26, further comprising a heating unit configured for producing steam and subjecting the same to the WGS reactor; and a heat exchanger (60a, 60b, 60c, 6od) configured for heating the product of the WGS reactor using said steam prior to subjecting said steam to the WGS reactor.

28. The system of any of claims 19-27 in combination with claim 20, further comprising a cooling unit configured for cooling the product stream from the second reactor for producing ammonia (NH3);further comprising a separation unit configured for separating the NH3from said product stream thereby providing a residual gas essentially free of NH3; and further comprising a compression unit configured for compressing and heating said residual gas and subjecting the same to the second reactor for producing NH3.

29. The system of any claims 19-28 in combination with claim 20, further comprising a heat exchanger configured for heating the product stream from the second reactor for producing methane (CH4); and a separation unit configured for separating condensate comprising water from said heated product stream;further comprising a separation unit configured for separating CH4from said product stream; and a recycle line configured for providing a residual gas essentially free of CH4;further comprising a compression unit configured for compressing and heating said residual gas and subjecting the same to the second reactor for producing CH4.

30. The system of any claims 19-29 in combination with claim 20, further comprising a heat exchanger for heating the product stream from the second reactor for producing mixed alcohol and / or methanol and / or DME;further comprising a separation unit configured for separating the heated mixed alcohol and / or methanol and / or DME from said product stream thereby providing a residual gas essentially free of mixed alcohol and / or methanol and / or DME; and further comprising a compression unit configured for compressing and heating said residual gas and subjecting the same to the second reactor for producing mixed alcohol and / or methanol and / or DME.

31. The system (100) of any of claims 19-30, further comprising a separation unit for isolating hydrogen from the product of the WGS reactor.

32. The system (100) of any of claims 19-31, further comprising a boiler unit (22a, 22b, 22c, 22d) for producing steam, and a line for transferring said steam to the WGS reactor; further comprising a feed effluent heat exchanger configured for cooling the product of the WGS reactor while superheating the produced steam from the boiler unit (22a, 22b, 22c, 22d).

33. The system (100) of any of claims 19-32, further comprising one or more recycle lines (65a, 65b, 65c, 65b) configured for recycling back unconverted starting materials to the CO2 converter unit (30a, 30b, 30c, 3od), and / or to the WGS reactor (40a, 40b, 40c, 40d) and / or to the second reactor (50a, 50b, 50c, 50d); wherein the recycle line of the one or more recycle lines comprise preferably one or more heat exchangers and / or compression units.34- The system (too) of any of claims 19-33, further comprising a storage unit (70a, 70b, 70c, 7Od) configured for storing the produced hydrogen and / or produced hydrogen derivatives.35- The system (100) of any of claims 19-34, further comprising a heating unit (45a, 45b, 45c, 45b) configured for cooling the produced gas from the C02converter unit and / or the product of the WGS reactor (40a, 40b, 40c, 4od) and / or the product of the second reactor (50a, 50b, 50c, sod).

36. The system (100) of any of claims 19-35, further comprising a compression unit (75a, 75b, 75c, 75b) configured for compressing the product of the WGS reactor prior to the second reactor (50a, 50b, 50c, 5od).

37. The system (100) of any of claims 19-36, further comprising a heat exchanger configured for heating the product of the second reactor prior to the separation unit and comprising a recycle line configured for feeding the second reactor with unconverted starting material from said separation unit.

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