Production of synthetic fuels from CO2 with by-product conversion and CO2 separation

Abstract

A device / method for capturing / converting CO2, comprising / using a CO2 capture unit (2), a water electrolysis unit (5), an RWGS unit (8), an FT unit (13), a by-product-to-synthesis gas conversion unit (28), and a hydrogen unit (20), wherein a carbon dioxide separation unit (34) is arranged to: treat a first synthesis gas (12) and a second synthesis gas (29); produce a carbon dioxide-depleted gaseous effluent (18) and a carbon dioxide-enriched gaseous effluent (35); and recycle the carbon dioxide-enriched gaseous effluent (35) to the inlet of the RWGS section (8). Figure 1 to be published

Description

Title of the invention: Production of synthetic fuels from CO2 with conversion of by-products and separation of CO 2 Technical field

[0001] The present invention relates to the production of synthetic fuels, namely gasoline, kerosene, diesel, and / or other hydrocarbon products, such as naphtha, or lubricating bases, of very high quality (essentially free of sulfur, aromatics, nitrogen). More particularly, an object of the present invention is to produce synthetic fuels from carbon dioxide (CO2) and water.

[0002] The conversion of carbon dioxide into a fuel base according to the invention relates in particular to the following steps: the capture of carbon dioxide, the electrolysis of water, the conversion of carbon dioxide and hydrogen into synthesis gas composed mainly of carbon monoxide (CO) and H2, the conversion of synthesis gases into synthesis hydrocarbons by the Fischer-Tropsch (FT) process and the conversion of by-products present in the gaseous effluent from the FT process into a second synthesis gas rich in CO and H2. The properties of the products from the Fischer-Tropsch process can be adjusted by post-treatment operations adapted to obtain the desired fuel specifications. Prior art

[0003] The use of the reverse water-gas shift (RWGS) process to convert a mixture of carbon dioxide and hydrogen into CO+H2 synthesis gas has been known to those skilled in the art for a very long time. The same is true for the Fischer-Tropsch synthesis process which makes it possible to convert said synthesis gas into a mixture of paraffins, and / or olefins and / or oxygenates depending on the catalyst and the operating conditions. In the case where paraffins are produced, it is preferable to improve certain properties to make them usable for transport applications.

[0004] Sequences of unit operations have been the subject of patent applications, these sequences of unit operations aim to convert carbon dioxide into a base for fuels, often known under the term e-fuels (in French e-carburants or electro-carburants).

[0005] For example, we can cite patent application US2010 / 0280135 A1 which describes a renewable Fischer-Tropsch synthesis process which makes it possible to produce hydrocarbons and alcohols from wind energy, residual carbon dioxide and of water. The process comprises the following unit operations: electrolysis of water to produce hydrogen and oxygen, a RWGS reactor for the production of synthesis gas, Fischer-Tropsch synthesis in a high-temperature multi-tubular reactor. Various recycling options are described (e.g. recycle after separation of unconverted carbon dioxide from RWGS, recycle carbon dioxide ex-FT to RWGS, recycle unconverted H2 and CO ex-FT to FT).

[0006] Patent application US2007 / 0244208 A1 relates to a process for producing high octane fuel from carbon dioxide and water. The raw material is industrial carbon dioxide and water. The end product may be high octane gasoline, high cetane diesel or other liquid hydrocarbon mixtures suitable for driving conventional combustion engines or hydrocarbons suitable for further industrial processing or commercial use. Products, such as dimethyl ether or methanol may also be removed from the production line. The heat generated by exothermic reactions in the process is fully utilized, as is the heat generated by the production process, as is the heat generated by reprocessing hydrocarbons that are not suitable for liquid fuel.

[0007] Patent application US2012 / 0079767 A1 describes a method and system for producing syngas by combining hydrogen and carbon monoxide from separate sources while controlling the molar ratio (H2 / CO) of the produced syngas. Hydrogen is produced by electrolysis of water. Carbon monoxide is produced by reacting carbon dioxide captured from the exhaust gases of stationary combustion engines, with hydrogen in a RWGS reactor. Hydrocarbon fuels are produced from the syngas by Fischer-Tropsch synthesis.

[0008] Patent application US2007 / 0142481 A1 describes a process for synthesizing hydrocarbons comprising introducing hydrogen and carbon monoxide into a first Fischer-Tropsch reaction stage allowing the hydrogen and carbon monoxide to partially react catalytically to form hydrocarbons. At least a portion of a tail gas which comprises unreacted hydrogen and carbon monoxide obtained from the first reaction stage is introduced into a second Fischer-Tropsch reaction stage which is a two-phase high-temperature catalytic Fischer-Tropsch reaction stage. The hydrogen and carbon monoxide can at least partially react catalytically in the second reaction stage to form gaseous hydrocarbons. This patent application is characterized by the presence of two Fischer-Tropsch reactors in series, the second one treating the unconverted synthesis gas from the first one.There is no recycling of carbon dioxide or recycling of water.

[0009] Patent application WO2022 / 232936 A1 describes a method for increasing carbon monoxide production and recycling carbon dioxide during syngas processing using a carbon dioxide to carbon monoxide conversion unit, such as a Reverse Water Gas Shift (RWGS) reactor, converting excess CO2 from the produced syngas into additional CO, using an external source of green, renewable or low-carbon hydrogen.

[0010] Thus, the analysis of the prior art highlights that the sequence of unit operations of RWGS and Fischer-Tropsch makes it possible to produce synthetic bases for fuels from carbon dioxide and hydrogen, said hydrogen being able in certain cases to be produced by electrolysis of water with a low-carbon electricity source, such as solar or wind for example or even nuclear.

[0011] On the other hand, the prior art does not mention the possibility of integrating additional units making it possible to increase the conversion of carbon dioxide. Summary of the invention

[0012] The invention relates to the capture and conversion of carbon dioxide, so as to produce a CO+H2 synthesis gas, and to the conversion of said synthesis gas into synthetic hydrocarbons by the Fischer-Tropsch reaction. The characteristics of the effluents from the Fischer-Tropsch synthesis can then be adjusted by a post-treatment process ("upgrading" according to the English terminology; known to those skilled in the art) so that they are compatible with use for land, air and maritime fuels. The gases produced at the outlet of the Fischer-Tropsch reactor can also be upgraded to synthetic methane (e-methane), synthetic natural gas SNG (e-SNG) or synthetic LPG (e-LPG).

[0013] Specifically, the present invention relates to a device and a method for producing synthetic fuels from carbon dioxide and water, allowing improved production of the products of interest. Advantageously, the method also makes it possible, by original thermal integration, to minimize the energy requirements for the production of said fuels.

[0014] The present invention is based on the presence of a unit for separating the carbon dioxide contained in the synthesis gas upstream of the Fischer-Tropsch reaction unit, the carbon dioxide separated from this gaseous effluent is recycled to the inlet of the RWGS reaction unit. Thus the synthesis gas sent to the Fischer-Tropsch reaction unit contains substantially no more carbon dioxide.

[0015] The invention is also based on the presence of a unit for converting by-products into synthesis gas supplied by the gaseous effluent from the Fischer-Tropsch reaction unit to mainly produce a second synthesis gas rich in H 2 and CO. Advantageously, the second synthesis gas is returned to the inlet of the carbon dioxide separation unit, making it possible to recycle the CO2 from the RWGS and synthesis gas by-product conversion units to the RWGS unit and to recover additional CO in the Fischer-Tropsch reaction unit.

[0016] The carbon dioxide separation unit is therefore supplied by the first synthesis gas from the RWGS unit and by the second synthesis gas from the unit for converting by-products into synthesis gas.

[0017] The energy integration of the process also makes it possible to produce electricity from heat recovery. This heat converted into electricity makes it possible to provide energy both for the water electrolysis and / or the RWGS unit and / or the capture unit and / or the carbon dioxide separation unit and / or the unit for converting by-products into synthesis gas.

[0018] Advantageously, hydrogen produced by water electrolysis can be used for carbon dioxide conversion, Fischer-Tropsch synthesis and post-treatment. Preferably, the hydrogen required in the process is entirely supplied by a water electrolysis unit. Thus, the process according to the invention may not require an external supply of hydrogen, for example produced by steam reforming of natural gas. The electrolyser will preferably operate with low-carbon electricity, which will contribute to the renewable nature of the fuels and gases produced. In addition, the water used for hydrogen production can come at least in part from the recycling of the water produced in the various stages of the process, which has the advantage of limiting the external supply of water.

[0019] Advantageously, the oxygen produced by the electrolysis of water can feed the section for converting by-products into synthesis gas.

[0020] According to a first aspect, the aforementioned objects, as well as other advantages, are obtained by a device for capturing and converting a charge containing carbon dioxide, comprising the following units: - a unit for capturing carbon dioxide from the feedstock using, for example, at least one amine-based solvent, at least one physical solvent such as, for example, polyethylene glycol dimethyl ether-based, and / or physical adsorption equipment operated by alternating temperature adsorption, and being suitable for producing an effluent rich in carbon dioxide; - a water electrolysis unit adapted to convert water to produce oxygen and hydrogen; - a reverse water gas conversion reaction unit RWGS adapted to treat the carbon dioxide-rich effluent with hydrogen and produce a first synthesis gas and a first water effluent optionally recycled at least in part at the entrance of the water electrolysis unit; - a carbon dioxide separation unit adapted to treat the first synthesis gas, produce a carbon dioxide-depleted gaseous effluent and a carbon dioxide-rich gaseous effluent, and recycle the carbon dioxide-rich gaseous effluent to the inlet of the RWGS section; - a Fischer-Tropsch reaction unit adapted to convert the depleted gaseous effluent into carbon dioxide, and produce a hydrocarbon effluent, a second water effluent optionally recycled at least in part to the inlet of the water electrolysis unit, and a gaseous effluent, and optionally generate a first water vapor, generated for example by the vaporization of water in a heat exchanger located inside the Fischer-Tropsch reaction unit, to supply thermal energy to the carbon dioxide capture unit and / or the carbon dioxide separation unit; - a reaction unit for converting by-products into synthesis gas adapted to convert at least part of the gaseous effluent, and produce a second synthesis gas rich in carbon monoxide and hydrogen which is sent to the carbon dioxide separation unit; and - a hydrogen reaction unit (hydrotreatment and / or hydrocracking and / or hydroisomerization unit) adapted to treat the hydrocarbon effluent and produce at least one hydrocarbon cut, for example to specifications for transport applications.

[0021] According to one or more embodiments, the reaction unit for converting by-products into synthesis gas is adapted to produce heat used to provide calories to the RWGS reaction unit and / or the carbon dioxide capture unit.

[0022] According to one or more embodiments, the device comprises a hydrogen supply adapted to supply hydrogen into the gaseous effluent depleted in carbon dioxide.

[0023] According to one or more embodiments, the device comprises a first turbine for treating at least a portion of the gaseous effluent to produce electricity.

[0024] According to one or more embodiments, the RWGS unit is adapted to produce a second water vapor by (indirect) heat exchange between water (not shown) and an effluent leaving a RWGS reactor, to optionally supply thermal energy to the carbon dioxide capture unit and / or the carbon dioxide separation unit; and / or the reaction unit for converting by-products into synthesis gas is adapted to produce a third water vapor by (indirect) heat exchange between water (not shown) and an outgoing effluent of a reactor for converting by-products into synthesis gas, to optionally supply thermal energy to the carbon dioxide capture unit and / or the carbon dioxide separation unit.

[0025] According to one or more embodiments, the device comprises a second turbine adapted to process at least in part the first water vapor and / or the second water vapor and / or the third water vapor to produce electricity.

[0026] According to one or more embodiments, the electricity (eg produced by the turbine(s)) is used to supply calories to the RWGS reaction unit and / or the carbon dioxide capture unit and / or the carbon dioxide separation unit and / or the water electrolysis unit and / or pumps or compressors present in a unit of the device according to the invention.

[0027] According to one or more embodiments, electricity is used to supply calories to the regeneration section of the carbon dioxide capture unit and / or the carbon dioxide separation unit.

[0028] According to one or more embodiments, the water electrolysis unit treats water from a make-up line and / or the RWGS reaction unit and / or the Fischer-Tropsch reaction unit and / or the by-product conversion to synthesis gas reaction unit.

[0029] According to one or more embodiments, the carbon dioxide-rich effluent and / or the carbon dioxide-rich gaseous effluent are purified, separately or after mixing, before being introduced into the RWGS reaction unit. According to one or more embodiments, the carbon dioxide-depleted gaseous effluent is purified before being introduced into the Fischer-Tropsch reaction unit. According to one or more embodiments, the first water effluent, and / or the second water effluent is purified before being introduced into the water electrolysis unit. The effluent purification steps aim to at least partially remove at least one of the following compounds: organic compounds, ionic species, sulfur compounds, nitrogen compounds, halogenated compounds, metals (e.g. heavy metals), transition metals.

[0030] According to a second aspect, the aforementioned objects, as well as other advantages, are obtained by a process for capturing and converting carbon dioxide, comprising the following steps: - treat a load in a carbon dioxide capture unit to produce an effluent rich in carbon dioxide; - convert water in a water electrolysis unit to produce oxygen and hydrogen; - treat the carbon dioxide-rich effluent with hydrogen in a reverse water gas conversion reaction unit RWGS to produce a first gas of synthesis and a first water effluent optionally recycled at least in part to the inlet of the water electrolysis unit; - treating the first synthesis gas in a carbon dioxide separation unit to produce a carbon dioxide-depleted gaseous effluent and a carbon dioxide-rich gaseous effluent; - recycle the carbon dioxide-rich gaseous effluent at the entrance to the RWGS section; - converting the depleted gaseous effluent into carbon dioxide in a Fischer-Tropsch reaction unit to produce a hydrocarbon effluent, a second water effluent optionally recycled at least in part to the inlet of the water electrolysis unit, and a gaseous effluent; - converting at least a portion of the gaseous effluent in a by-product conversion reaction unit into synthesis gas to produce a second synthesis gas rich in carbon monoxide and hydrogen which is sent to the carbon dioxide separation unit; and - treat the hydrocarbon effluent in a hydrogen reaction unit to produce at least one hydrocarbon cut, for example to specifications for transport applications.

[0031] According to one or more embodiments, the RWGS reaction unit comprises at least one reactor used under at least one of the following operating conditions: - temperature between 700°C and 1200°C, preferably between 800°C and 1100°C, and even more preferably between 850°C and 1050°C; - pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, and more preferably between 0.1 MPa and 3.5 MPa; - space velocity of the gas at the reactor inlet between 2000 NL / kgcata / h and 40000 NL / kgcata / h; - catalysts comprising a metal or a combination of metals selected from the group consisting of the elements Ni, Cu, Fe, Co, Pt, Pd, Ru, Ag and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises a support, for example based on alumina, silica, silica-alumina, alumina-silica.

[0032] According to one or more embodiments, the FT reaction unit comprises at least one reactor used under at least one of the following operating conditions: - temperature between 170°C and 280°C, preferably between 190°C and 260°C and preferably between 210°C and 240°C; - absolute pressure between 1.0 MPa and 6.0 MPa, preferably between 1.5 MPa and 3.5 MPa and preferably between 2.0 MPa and 3.0 MPa; - catalyst comprising cobalt or iron, preferably cobalt, the catalyst optionally comprising a support, for example based on alumina, silica, silica-alumina, alumina-silica or titanium.

[0033] According to one or more embodiments, the reaction unit for converting by-products into synthesis gas comprises at least one reactor used under at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 9 MPa; - temperature between 600°C and 2000°C.

[0034] According to one or more embodiments, the carbon dioxide capture unit and / or the carbon dioxide separation unit implements separation by chemical solvent and / or physical solvent and / or membrane and / or adsorption on a solid.

[0035] Embodiments of the device and the method according to the aforementioned aspects as well as other characteristics and advantages will appear on reading the description which follows, given for illustrative and non-limiting purposes only, and with reference to the following drawing. List of figures

[0036] [Fig.l] shows a schematic representation of a device according to the present invention in which the first synthesis gas and the second synthesis gas are in particular sent to a carbon dioxide separation unit. Description of the embodiments

[0037] Embodiments of the device according to the first aspect and the method according to the second aspect will now be described in detail. In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the device. However, it will be apparent to those skilled in the art that the device can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0038] In the present description, the term "comprise" is synonymous with (means the same as) "include" and "contain", and is inclusive or open and does not exclude other elements not recited. It is understood that the term "comprise" includes the exclusive and closed term "consist". Furthermore, in the present description, an effluent comprising essentially, substantially, or solely a compound A corresponds to an effluent comprising at least 95% by weight, preferably at least 98% by weight, very preferably at least 99% by weight, or even 100%, of compound A.

[0039] In the present description, the term "physical solvent" is synonymous with (means the same as) a solvent forming weak bonds (e.g. hydrogen bond, van der Waals bond) with the solute, a solvent not forming a strong bond (e.g. covalent bond, ionic bond) with the solute.

[0040] The present invention can be defined as a device and a method comprising a sequence of unit operations making it possible to produce synthetic hydrocarbons, such as synthetic fuels, for example gasoline, kerosene, diesel and / or naphtha or lubricating bases, preferably of very high quality from carbon dioxide from a capture unit.

[0041] The device and the method according to the invention are notably characterized in that they comprise and use units for capturing carbon dioxide, for converting reverse water gas (RWGS), for separating carbon dioxide from a gaseous effluent, for Fischer-Tropsch (FT) synthesis, for hydrogen treatment (hydrotreatment, and / or hydrocracking and / or hydroisomerization) of the hydrocarbon cuts from the FT reaction unit, and for converting the gaseous hydrocarbon by-products of the process (RWGS and / or Fischer-Tropsch synthesis and / or hydrogen treatment). Advantageously, the necessary hydrogen can be produced by a water electrolysis unit, said water being able to come from the RWGS, Fischer-Tropsch and by-product conversion to synthesis gas reaction units.Advantageously, the oxygen required for the conversion of by-products into synthesis gas can be produced by electrolysis of water, and optionally by another unit such as an air separation unit.

[0042] One of the characteristics of the present invention can be summarized in the use of carbon dioxide for the production of synthetic fuels, gasoline, kerosene, diesel and / or naphtha or very high quality lubricating bases. The present invention is based in particular on the presence of a carbon dioxide separation unit to extract the carbon dioxide from the other gaseous compounds of the process and recycle it. Said carbon dioxide separation unit can be located near the other units included in the invention or be remote, involving transport of the carbon dioxide by any means known to those skilled in the art (transport by pipeline, transport in tanks for transport by train, truck or ship).The present invention also relies on a by-product conversion unit into synthesis gas adapted to treat the gaseous hydrocarbon by-products to produce a second synthesis gas rich in carbon monoxide and hydrogen in order to improve the production of products of interest.

[0043] According to one or more embodiments, the present invention also makes it possible to minimize the quantity of carbon energy external to the process and therefore the impact on the environment, by means of an original energy integration based on the use of the heat at the outlet of the Fischer-Tropsch reaction unit and optionally of the RWGS reaction unit and / or the conversion of by-products into synthesis gas, to desorb carbon dioxide, for example. complexed with an amine in the carbon dioxide capture unit and / or the carbon dioxide separation unit and more particularly in a solvent regeneration unit.

[0044] According to one or more embodiments, electricity can also be produced by a turbine powered by an effluent from the Fischer-Tropsch reaction unit and / or by water vapor (e.g. produced at the outlet of the Fischer-Tropsch reaction unit and / or the RWGS reaction unit and / or the unit for converting by-products into synthesis gas), this electricity making it possible, for example, to supply calories to the device according to the invention, for example to the RWGS reaction unit.

[0045] Thus the combination of carbon dioxide capture, separation and chemical conversion units, preferably with original thermal integration, makes it possible to produce bases for fuels, and in particular for fuel for the aviation sector, while minimizing the environmental impact of the process.

[0046] Preferably, the use of the water produced by the RWGS reaction unit and / or the Fischer-Tropsch unit and / or the unit for converting by-products into synthesis gas, in the water electrolysis unit, also makes it possible to minimize the environmental impact of the process.

[0047] With reference to [Fig.l], the device for converting carbon dioxide into liquid hydrocarbons comprises: - a carbon dioxide capture unit 2 adapted to treat a load 1 containing carbon dioxide and produce an effluent (gaseous) rich in carbon dioxide 3 (i.e., enriched in carbon dioxide compared to load 1); - a water electrolysis unit 5 adapted to treat water 4 (fresh or recycled) to produce oxygen 6 and hydrogen 7; - a RWGS reaction unit 8 adapted to at least partially convert the carbon dioxide of the carbon dioxide-rich effluent 3 into a first synthesis gas 12, and a first water effluent 11; - a carbon dioxide separation unit 34 adapted to treat the first synthesis gas 12 and produce a gaseous effluent depleted in carbon dioxide 18 and a gaseous effluent rich in carbon dioxide 35, and recycle the gaseous effluent rich in carbon dioxide 35 to the inlet of the RWGS section 8; - a Fischer-Tropsch FT reaction unit 13 adapted to convert the depleted gaseous effluent into carbon dioxide 18 and produce at least one hydrocarbon effluent 17, one gaseous effluent 33, and a second water effluent 16 produced by the Fischer-Tropsch synthesis resulting from the condensation of gaseous water under the operating conditions of the Fischer-Tropsch reaction, and optionally adapted to generate a first water vapor 22, generated for example by the vaporization of water in a heat exchanger located inside the reaction unit FT 13, for supplying thermal energy to the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34; - a reaction unit for converting by-products into synthesis gas 28 adapted to convert at least a portion 24 of the gaseous effluent 33, produce a second synthesis gas 29 rich in carbon monoxide and hydrogen, and send the second synthesis gas 29 into the carbon dioxide separation unit 34; - a hydrogen reaction unit 20 (hydrotreatment and / or hydrocracking and / or hydroisomerization unit) adapted to treat the hydrocarbon effluent 17 with hydrogen 7 and separate at least one hydrocarbon fraction 21 comprising for example at least one of the following fractions: naphtha, gasoline, kerosene, diesel, and lubricant base; - optionally a first turbine 26 adapted to treat at least a portion 24 of the gaseous effluent 33 to produce electricity.

[0048] Advantageously, the Fischer-Tropsch FT reaction unit 13 and optionally the RWGS reaction unit 8 and optionally the by-product conversion reaction unit into synthesis gas 28 are adapted to produce water vapor by heat exchange. Advantageously, the use of water vapor makes it possible to supply energy to the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34, for example by regenerating an amine-based solvent (or a physical solvent) loaded with carbon dioxide in a regeneration unit of the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34, or by supplying alternating temperature adsorption equipment.

[0049] To avoid unnecessarily complicating the description and the figures, it will be apparent to those skilled in the art that the water supplies to the Fischer-Tropsch reaction unit FT 13, the RWGS reaction unit 8 and the reaction unit for converting by-products into synthesis gas 28 for generating water vapour have not been described in detail. The same applies to the water outlet of the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34. Carbon dioxide capture unit

[0050] The carbon dioxide capture unit 2 makes it possible to separate the carbon dioxide from the rest of the feedstock 1, the carbon dioxide then being able to be compressed or liquefied for recovery or for storage, including a possible transport step. According to one or more embodiments, the feedstock 1 comprises at least 0.04% vol of carbon dioxide, preferably at least 2% vol of carbon dioxide, very preferably at least 10% vol of carbon dioxide.

[0051] According to one or more embodiments, the charge 1 comprises or consists of oxycombustion fumes. According to one or more embodiments, the feed 1 comprises gaseous effluents from at least one unit selected from the group consisting of: a refinery, an incinerator, a petrochemical unit, a chemical unit, a thermal power plant, a paper mill, an ethanol factory, a sugar factory. According to one or more embodiments, the feed 1 comprises gaseous effluents from a cement plant, and / or gaseous effluents from a lime production unit, and / or gaseous effluents from blast furnaces. According to one or more embodiments, the oxycombustion fumes come from an oxycombustion chamber (e.g. boiler) adapted to burn a fuel, such as coal, natural gas, fuel oil, biogas, biomass, organic waste, urban waste, with an oxidizer, generally air.

[0052] According to one or more embodiments, feedstock 1 comprises or consists of biogas, natural gas, synthesis gas, refinery gas, biomass fermentation gas, cement plant gas and blast furnace gas.

[0053] The carbon dioxide may also be carbon dioxide present in the air. According to one or more embodiments, the load 1 comprises or consists of air. For example, the carbon dioxide capture unit 2 may comprise a direct air capture device (“Direct Air Capture” or “DAC” according to English terminology) and / or a direct ocean capture device (“Direct Ocean Capture” or “DOC” according to English terminology).

[0054] For the capture, several agents can be used, such as solvents and solids. According to the invention, the carbon dioxide capture unit 2 uses at least one amine-based solvent, and / or at least one physical solvent such as, for example, based on polyethylene glycol dimethyl ether), and / or alternating temperature adsorption (physical adsorption) equipment.

[0055] A widely used carbon dioxide capture technology relies on the phenomenon of absorption, namely the passage of a chemical species from a gas to a liquid. The gas containing the impurities, or the species to be separated, is sent to a column where it is brought into contact with a liquid solvent, the two flows being able to be implemented according to different hydrodynamic configurations (co-current, cross-current or counter-current, the latter solution being preferred for reasons of favorable thermodynamic equilibrium). This absorption is carried out using an absorbent solution, comprising a chemical solvent or a physical solvent, this distinction being linked to the fact whether or not there is a chemical reaction between the absorbed component and the solvent.

[0056] Physical absorption is preferred in order to minimize the energy cost of the process; this is particularly suitable in the case of high partial pressure of the species to be separated.

[0057] Chemical absorption is preferred in the case of high dilution and low partial pressure of the species to be separated and / or in the case where a high recovery rate of this species is desired or finally if a strict specification is desired as to the maximum admissible concentration of this species in the gas flow once washed. Thus for the capture of carbon dioxide on (industrial) fumes with a low carbon dioxide concentration value, typically between 3 and 15% by volume (typically in low pressure gases), washing by chemical absorption, for example using an amine solvent, for example of the alkanolamine type, is well suited.

[0058] The absorbent solutions commonly used today are aqueous solutions comprising one or more reactive compounds or having a physicochemical affinity with acidic compounds. The reactive compounds may be, for example and without limitation, amines (primary, secondary, tertiary, cyclic or not, aromatic or not, saturated or not), alkanolamines, polyamines, amino acids, alkali salts of amino acids, amides, ureas, phosphates, carbonates or borates of alkali metals. According to one or more embodiments, the absorbent solution is an aqueous solution comprising one or more reactive compounds with an amine function and whose structure is described from page 6, line 1 to page 7, line 3, of patent application WO2007 / 104856.

[0059] According to one or more embodiments, the reactive compounds represent from 10% by weight to 90% by weight, preferably between 20% by weight and 50% by weight, very preferably between 25% by weight and 40% by weight, of the total weight of the absorbent solution.

[0060] Chemical absorption with amine solvents is based on acid-base equilibria, with low temperature favoring the reaction between the basic amine and the acidic carbon dioxide, and high temperature favoring the reverse reaction. Thus, amine processes, using for example an aqueous phase containing 20-50% by mass of amine, use two columns (not shown) in which the solvent circulates from one to the other. In the first column, called the absorber, the stream to be washed (i.e., feed 1) is brought into contact with the amine solvent at low temperature. The amine solvent flows into the column and captures the carbon dioxide. At the bottom of the column, the amine solvent ("rich" solvent) reaches a predetermined loading rate, the ratio between the number of moles of carbon dioxide captured and the number of moles of amines.At the top of the column, the gas stream exits at predetermined specifications, namely a carbon dioxide content, for example, nearly 10 times lower than the initial content in the fumes. The rich solvent is sent to the second column, called the regenerator, which operates in a similar way to a distillation column, operating at high temperature. The regenerated amine solvent (the "lean" solvent) can be returned to the absorber. The amine solvent thus circulates continuously in a closed loop from one column to another, preferably passing through a load / effluent heat exchanger to cool the lean solvent and preheat the rich solvent while saving energy on the process scale.

[0061] According to one or more embodiments, the regenerator operates at a high temperature between 90°C and 250°C, preferably between 110°C and 240°C, very preferably between 120°C and 200°C at the bottom of the column.

[0062] The carbon dioxide released from the regenerator can then optionally be compressed or liquefied and recovered. According to one or more embodiments, the carbon dioxide-rich effluent 3 comprises at least 90% vol. of carbon dioxide, preferably at least 95% vol. of carbon dioxide, very preferably at least 98% vol. of carbon dioxide. According to one or more embodiments, the carbon dioxide-rich effluent 3 has a temperature of between 20°C and 250°C, preferably between 30°C and 200°C, very preferably between 40°C and 150°C, at the outlet of the carbon dioxide capture unit 2. According to one or more embodiments, the carbon dioxide-rich effluent 3 has a pressure of between 0.20 MPa and 4 MPa, preferably between 0.30 MPa and 3.5 MPa, very preferably between 0.4 MPa and 3 MPa, at the outlet of the carbon dioxide capture unit 2.

[0063] A key aspect of industrial fume treatment operations using solvents is the step of regenerating the separation agent. Depending on the type of absorption (physical and / or chemical), regeneration by expansion, and / or by distillation and / or by entrainment by a vaporized gas called "stripping gas" is generally considered.

[0064] One of the main limitations of the solvents commonly used today is the need to implement high flow rates of absorbent solution, which results in high energy consumption for solvent regeneration, but also large equipment sizes (columns, pumps, etc.). This is particularly true in the case where the partial pressure of carbon dioxide is low. Such energy consumption represents a considerable operating cost for the carbon dioxide capture process. The regeneration energy depends on the nature of the amines and the partial pressure of carbon dioxide and is typically between 2 GJ / t and 4 GJ / t of captured carbon dioxide. New capture processes tend to reduce this energy in order to tend towards values ​​lower than 2 GJ / t carbon dioxide.In the context of air treatment, carbon dioxide concentrations being very low, the energy consumed is very high, in the order of 5 GJ / t carbon dioxide to 7.5 GJ / t carbon dioxide.

[0065] Another possible implementation is based on the principle of adsorption by means of of a solid adsorbent with a strong chemical affinity for carbon dioxide. To ensure continuous operation, the processes operate with several reactors in parallel. The carbon dioxide is adsorbed on the solid adsorbent and the flow to be treated (i.e., feed 1) becomes depleted as it advances through the bed of solids, and, at the outlet, the flow contains little or no carbon dioxide. However, the solid adsorbent gradually becomes saturated and can no longer adsorb carbon dioxide. The flow to be treated is then sent to another reactor containing a solid adsorbent not saturated with carbon dioxide and the capture operation continues. In parallel, the reactors saturated with carbon dioxide are subject to a regeneration operation: - by a rise in temperature, we then speak of alternating temperature adsorption (or “TSA” for “Temperature Swing Adsorption” according to Anglo-Saxon terminology); and - by partial vacuum, we then speak of adsorption by pressure inversion (or "VPSA" for "Vacuum Pressure Swing Adsorption" according to Anglo-Saxon terminology, or simply "VS A" or "PSA", possibly in the presence of a gas promoting desorption).

[0066] The bottlenecks of TSA processes are the large amount of heat required for regeneration. The thermal integration proposed in the present invention makes it possible to remove this bottleneck.

[0067] According to one or more embodiments, the solid adsorbent for carbon dioxide capture is chosen from the following compounds: activated carbon, zeolites, aluminas, silicas, synthetic fibers with or without impregnated amines, solids of the metal-organic framework type ("Metal-Organic Framework" or "MOF" according to English terminology), supported alkali carbonates. These solid adsorbents are increasingly used in the case of carbon dioxide capture from the air. The regeneration energy of adsorbents with physisorption in these cases, for example on zeolites, is of the order of 0.6 to 0.9 GJ / t carbon dioxide. For amines supported on solid, the regeneration energy is between 5.4 and 7.2 GJ / t carbon dioxide.

[0068] Advantageously, the energy required for the regeneration of the amine solvent and / or the increase in temperature of the solid adsorbent can be provided at least partially by the first water vapor 22 and optionally the second water vapor 23. Energy, for example in the form of a third water vapor, can be provided by the reaction unit for converting the by-products into synthesis gas 28. This supply of energy to the carbon dioxide capture unit 2 makes it possible to improve the energy efficiency of the process.

[0069] According to one or more embodiments, the temperature of the water vapor (for example 22 and / or 23) is at least 110°C, preferably at least 120°C, very preferably at least 130°C, for example at the outlet of the RWGS reaction unit 8 and / or the FT reaction unit 13 and / or the reaction unit for converting by-products into synthesis gas 28. According to one or more embodiments, the temperature of the water vapor is between 110°C and 270°C, preferably between 120°C and 260°C, very preferably between 130°C and 220°C. According to one or more embodiments, the water vapor has a pressure between 0.1 MPa and 6 MPa, preferably between 0.1 MPa and 3.5 MPa, very preferably between 0.1 MPa and 1.7 MPa. Water electrolysis unit

[0070] The water electrolysis unit 5 treats water 4 coming from a make-up line and / or from the RWGS reaction unit 8 and / or from the FT reaction unit 13.

[0071] According to one or more embodiments, the water electrolysis unit 5 comprises a pre-treatment section adapted to extract oxygenated compounds from the water 4, for example from the second water effluent 16.

[0072] According to one or more embodiments, the water electrolysis unit 5 comprises at least one alkaline type electrolyzer. Other electrolyzer technologies may be used for the water electrolysis unit, such as proton exchange membrane (PEM) electrolysis, solid oxide electrolysis (SOE), or anion exchange membrane (AEM) electrolysis. The operating conditions (temperature, pressure, nature of the electrolyte, electrodes and diaphragm / membrane) are then specific to each technology.

[0073] According to one or more embodiments, the water electrolysis unit 5 comprises at least one reactor used in at least one of the following operating conditions: Alkaline type electrolyzer: - temperature between 60°C and 90°C, - pressure between 0.1 MPa and 20 MPa, preferably between 0.1 MPa and 4 MPa, - electrolyte comprising KOH, - electrodes comprising a metal alloy, - diaphragm comprising asbestos, polytetrafluoroethylene and / or nickel oxide; Proton exchange membrane (PEM) electrolyser: - temperature between 50°C and 80°C, - pressure between 0.1 MPa and 20 MPa, preferably between 1.8 MPa and 5.5 MPa, - electrolyte comprising a polymer membrane, - electrodes comprising a metal alloy; Solid oxide electrolyzer (SOE): - temperature between 800°C and 900°C, - pressure between 0.1 MPa and 2 MPa, preferably between 0.1 MPa and 0.5 MPa, - electrolyte comprising a ceramic membrane (eg perovskite type), - electrodes comprising a metal alloy; Anion exchange membrane (AEM) type electrolyzer: - temperature between 50°C and 70°C, - pressure between 0.1 MPa and 20 MPa, preferably between 0.1 MPa and 3.5 MPa, - electrolyte comprising a polymer membrane, - electrodes comprising a metal alloy.

[0074] According to one or more embodiments, the oxygen 6 produced by the water electrolysis unit 5 comprises between 99.0% by weight and 99.8% by weight of O2 (after drying).

[0075] According to one or more embodiments, the hydrogen 7 produced by the water electrolysis unit 5 comprises between 99.5% by weight and 99.999% by weight of H2 (after drying).

[0076] Advantageously, oxygen 6 can be used for the conversion of by-products into synthesis gas. The oxygen 6 produced by the water electrolysis unit 5 can be used for this purpose. According to one or more embodiments, the oxygen 6 can be purified if necessary and compressed if the conversion of by-products into synthesis gas is carried out at a pressure higher than the pressure at which the oxygen 6 is produced in the water electrolysis unit 5.

[0077] Thus the invention can make it possible to recover the oxygen 6 produced by the water electrolysis unit 5 within the unit for converting by-products into synthesis gas. Thus, part of the energy used for the electrolysis can be reintroduced into the system in the form of oxygen 6 as an energy vector. This represents an advantage compared to the conventional operation of producing pure oxygen from the separation of oxygen from the air, a step which is energy-intensive.

[0078] According to one or more embodiments, the water electrolysis unit 5 is based on a solid oxide electrolyser (SOE) technology for which at least a portion of the water 4 may be in the form of steam supplied at least partially by a unit of the device according to the invention, for example by the first water vapour 22 and / or the second water vapour 23 and / or the third water vapour. This supply of energy to the electrolysis unit 5 makes it possible to improve the energy efficiency of the process.

[0079] Reverse Water Gas Switching (RWGS) Reaction Unit

[0080] The RWGS reaction unit 8 produces a first synthesis gas 12 rich in CO, preferably rich in hydrogen, and containing unconverted carbon dioxide, and produces a first water effluent 11 optionally recycled to the water electrolysis unit 5. The hydrogen 7 required for the RWGS reaction comes from the water electrolysis unit 5. Optionally, hydrogen 7 can be supplied in excess to meet the hydrogen requirements of the Fischer-Tropsch reaction unit 13.

[0081] According to one or more embodiments, the RWGS reaction unit 8 comprises at least one reactor used under at least one of the following operating conditions: - temperature between 700°C and 1200°C, preferably between 800°C and 1100°C, and even more preferably between 850°C and 1050°C; - pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, and more preferably between 0.1 MPa and 3.5 MPa; - space velocity of the gas at the reactor inlet between 2000 NL / kgcata / h and 40000 NL / kgcata / h; - catalysts based on the elements Ni, Cu, Fe, Co or precious metals such as Pt, Pd, Ru, Ag and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises a support, for example based on alumina, silica, silica-alumina, alumina-silica.

[0082] According to one or more embodiments, the quantity of hydrogen at the inlet of the RWGS reaction unit 8 is adjusted so that the H2 / CO molar ratio in the first synthesis gas 12 is compatible with the requirement of the Fischer-Tropsch unit, i.e. between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5.

[0083] According to one or more embodiments, the temperature of the effluent leaving the RWGS reactor(s) is at least 700°C, preferably at least 750°C, very preferably at least 800°C.

[0084] According to one or more embodiments, the RWGS reaction unit 8 produces a second water vapor 23 by (indirect) heat exchange between water (not shown) and the effluent from the RWGS reactor, preferably directly at the outlet of the reactor(s).

[0085] According to one or more embodiments, the second water vapor 23 supplies energy to the regeneration unit of the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34.

[0086] According to one or more embodiments, the first synthesis gas 12 comprises less than 2 mol% of water.

[0087] The first synthesis gas 12 is sent to the carbon dioxide separation unit 34. According to one or more embodiments, the first synthesis gas 12 can be compressed and then optionally cooled before being sent to the carbon dioxide separation unit 34. Carbon dioxide separation unit

[0088] In the carbon dioxide separation unit 34, the first synthesis gas 12 and the second synthesis gas 29 are treated to produce: - the gaseous effluent depleted in carbon dioxide 18; and - the gaseous effluent rich in carbon dioxide 35, compared to the carbon dioxide content of the sum of synthesis gases 12 and 29.

[0089] If the first synthesis gas 12 and / or the second synthesis gas 29 contains H2S, the H2S is separated like carbon dioxide, i.e. the carbon dioxide-depleted gaseous effluent 18 is depleted in H2S and the carbon dioxide-rich gaseous effluent 35 is rich in H2S, relative to the H2S content of the sum of the synthesis gases 12 and 29.

[0090] For the separation of carbon dioxide, several agents can be used, such as solvents and solids. Preferably, the carbon dioxide separation unit 34 uses at least one chemical solvent based on amines, and / or at least one physical solvent such as, for example, based on polyethylene glycol dialkyl ether or methanol, and / or physical adsorption equipment at alternating temperature.

[0091] Advantageously, the recovery of carbon dioxide makes it possible to limit the carbon dioxide content in the feedstock of the Fischer-Tropsch reaction unit 13.

[0092] According to one or more embodiments, the carbon dioxide separation unit 34 implements washing by chemical absorption using a solvent, such as an aqueous solvent, comprising one or more reactive compounds or having a physicochemical affinity with the acidic compounds. The reactive compounds may be, for example and in a non-limiting manner, amines (primary, secondary, tertiary, cyclic or not, aromatic or not, saturated or not), alkanolamines (for example monoethanolamine, diethanolamine, methyldiethanolamine), polyamines, amino acids, alkali salts of amino acids, amides, ureas, phosphates, carbonates or borates of alkali metals. According to one or more embodiments, the carbon dioxide separation unit 34 implements washing by chemical absorption, for example using an amine-based solvent, for example of the alkanolamine type.

[0093] Thus, amine processes, using for example an aqueous phase with 20-50% by mass of amine, use two columns (not shown) in which the solvent circulates from one to the other. In the first column, called the absorber, the flow to be washed (i.e., 12 + 29) is brought into contact with the amine solvent at low temperature. The amine solvent flows into the column and captures the carbon dioxide. At the bottom of the column, the amine solvent (the "rich" solvent) reaches a predetermined loading rate, the ratio between the number of moles of carbon dioxide captured and the number of moles of amines. At the top of the column, the outgoing gaseous effluent 18 is depleted in carbon dioxide. The rich solvent is sent to the second column, called the regenerator, whose operation is similar to that of a distillation column, operating at high temperature. The gaseous effluent rich in carbon dioxide 35 leaves at the top of the regenerator and the regenerated amine solvent ("lean" solvent) leaving at the bottom of the regenerator can be returned to the absorber. The amine solvent thus circulates continuously in a closed loop from one column to the other, preferably passing through a load / effluent heat exchanger to cool the lean solvent and preheat the rich solvent while saving energy on a process scale.

[0094] According to one or more embodiments, the regenerator operates at a temperature between 90°C and 250°C, preferably between 110°C and 240°C, very preferably between 120°C and 200°C at the bottom of the column.

[0095] This regeneration step can advantageously be carried out in two steps in order to eliminate on the one hand a gaseous flow rich in carbon dioxide 35 and on the other hand a gaseous flow rich in H2S (not shown in [Fig.l]). In a variant of the method according to the invention, said gaseous flow rich in carbon dioxide 35 is purified of H2S and advantageously recycled to the inlet of the RWGS section 8.

[0096] The regeneration energy depends on the nature of the amines and the partial pressure of carbon dioxide and is typically between 1 GJ / t and 4 GJ / t of separated carbon dioxide.

[0097] According to a second embodiment, the carbon dioxide separation unit 34 is a membrane separation unit. Membrane separation processes were, initially, not recommended for the separation of carbon dioxide in post-combustion, gas-liquid absorption processes in a chemical solvent being considered as the most mature and most suitable technology to ensure this operation. However, the most recent technologies make it possible to separate carbon dioxide in an economical manner with membranes (dense polymers, inorganic materials, hybrid matrices, liquid membranes). Reference may be made to the journal article: Oil Gas Sci. Technol. - Rev. IFP Energies nouvelles, Volume 69, Number 6, November-December 2014. The main performance is a capture rate and a purity of carbon dioxide greater than 90%.

[0098] According to a third embodiment, the carbon dioxide separation unit 34 is based on the principle of adsorption by means of a solid adsorbent having a strong chemical affinity for carbon dioxide.

[0099] According to one or more embodiments, the solid adsorbent for the separation of carbon dioxide is chosen from the following compounds: activated carbon, zeolites, aluminas, silicas, synthetic fibers with or without amines im pregnates, metal-organic framework (MOF) solids, supported alkali carbonates. The regeneration energy of adsorbents with physisorption in these cases, for example on zeolites, is of the order of 0.6 to 0.9 GJ / t carbon dioxide. For amines supported on solids, the regeneration energy is between 5.4 and 7.2 GJ / t carbon dioxide.

[0100] Advantageously, the energy required for the regeneration of the amine solvent and / or the temperature increase of the solid adsorbent can be provided at least partially by the first water vapor 22 and optionally the second water vapor 23 and optionally the third water vapor. This supply of energy to the carbon dioxide separation unit 34 makes it possible to improve the energy efficiency of the process.

[0101] The carbon dioxide-18-depleted gaseous effluent is sent to the Fischer-Tropsch reaction unit 13. The carbon dioxide-18-depleted gaseous effluent may be compressed before being sent to the Fischer-Tropsch reaction unit 13.

[0102] The carbon dioxide-rich gaseous effluent 35 is sent to the RWGS reaction unit 8. The carbon dioxide-rich gaseous effluent 35 may be compressed before being sent to the RWGS reaction unit 8. Fischer-Tropsch synthesis reaction unit

[0103] According to the invention, in the Fischer-Tropsch reaction unit 13, the carbon monoxide and hydrogen present in the carbon dioxide-depleted gaseous effluent 18 react to produce a hydrocarbon effluent 17, a gaseous effluent 33, and a second water effluent 16.

[0104] According to one or more embodiments, the carbon dioxide-depleted gaseous effluent 18 sent to the FT reaction unit 13 comprises carbon monoxide and hydrogen with a H2 / CO molar ratio of between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5. According to one or more embodiments, the quantity of hydrogen upstream (eg at the inlet) of the FT reaction unit 13 is adjusted, for example by means of an optional hydrogen supply 36, so that the H2 / CO molar ratio is as defined above.

[0105] The FT 13 reaction unit is implemented in a reaction unit comprising one or more suitable reactors, the technology of which is known to those skilled in the art. This may be, for example, one or more multitubular fixed bed reactors, or one or more slurry bubble column type reactors, or one or more microchannel reactors.

[0106] According to one or more embodiments, the Fischer-Tropsch reaction unit implements implement one or more bubble column type reactors. Since the synthesis is highly exothermic, this embodiment allows, among other things, to improve the thermal control of the reactor and to create little pressure loss.

[0107] The catalyst used in this Fischer-Tropsch synthesis is generally any catalytic solid known to those skilled in the art for carrying out the Fischer-Tropsch synthesis. According to one or more embodiments, the catalyst used in the Fischer-Tropsch synthesis comprises cobalt or iron, preferably cobalt. The catalyst used is generally a supported catalyst. The support may be, for example, based on alumina, silica, silica-alumina, alumina-silica or titanium.

[0108] According to one or more embodiments, the reaction unit FT 13 comprises at least one reactor used in at least one of the following operating conditions: - temperature between 170°C and 280°C, preferably between 190°C and 260°C and preferably between 210°C and 240°C, - absolute pressure between 1.0 MPa and 6.0 MPa, preferably between 1.5 MPa and 3.5 MPa and preferably between 2.0 MPa and 3.0 MPa.

[0109] According to one or more embodiments, the Fischer-Tropsch reaction unit 13 is adapted to produce the first water vapor 22 and supply thermal energy to the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34. The first water vapor 22 is generated for example by the vaporization of water (not shown) in a heat exchanger located inside the FT reaction unit 13 making it possible to eliminate the calories from the Fischer-Tropsch reaction, an exothermic reaction.

[0110] At the outlet of the FT reaction unit 13, the hydrocarbon effluent 17 is sent to the hydrogen reaction unit 20, and the second water effluent 16 is optionally sent to the water electrolysis unit 5.

[0111] According to one or more embodiments, the hydrocarbon effluent 17 comprises: n-paraffins, olefins and oxygenated compounds resulting from the condensation of gaseous hydrocarbons under the operating conditions of the Fischer-Tropsch reaction.

[0112] According to one or more embodiments, the hydrocarbon effluent 17 comprises less than 5% by weight of water, preferably less than 2% by weight of water, very preferably less than 1% by weight of water.

[0113] According to one or more embodiments, the second water effluent 16 is produced by Fischer-Tropsch synthesis and comes from the condensation of gaseous water under the operating conditions of the Fischer-Tropsch reaction.

[0114] According to one or more embodiments, the gaseous effluent 33 comprises unconverted synthesis gas, carbon dioxide and gaseous hydrocarbons such as paraffins from C1 to C5 (predominantly), olefins from C2 to C5, and compounds oxygenated from Cl to C5.

[0115] According to one or more embodiments, the gaseous effluent (33 or 24) is treated at least in part by the first turbine 26 to produce electricity, the gas 27 leaving the first turbine 26 is sent to the reaction unit for converting the by-products into synthesis gas 28.

[0116] Reaction unit for converting by-products into synthesis gas

[0117] According to the invention, in the reaction unit for converting by-products into synthesis gas 28, the hydrocarbon compounds (i.e., paraffins and olefins of 1 to 10 carbon atoms per molecule, and oxygenated compounds of 1 to 5 carbon atoms per molecule) present in the gaseous effluent 27 are converted, to produce a second synthesis gas 29 comprising (essentially) carbon monoxide and hydrogen.

[0118] Different catalytic and non-catalytic processes, known to those skilled in the art, can be used to convert the by-products present in the gaseous effluent 27 and produce a synthesis gas 29: - steam reforming (“Steam methane reforming” or “SMR” in Anglo-Saxon terminology); - partial oxidation (“Partial oxidation” or “POX” according to Anglo-Saxon terminology), which can be catalytic or thermal; - autothermal reforming (“Autothermal reforming” or “ATR” in Anglo-Saxon terminology); - combined reforming (“Combined reforming” or “CR” in Anglo-Saxon terminology); and - dry reforming (“Dry reforming of methane” or “DRM” in Anglo-Saxon terminology). Steam reforming (SMR)

[0119] Steam reforming (SMR) consists of reacting a hydrocarbon feedstock (gas, naphtha) on a catalyst in the presence of excess water vapor to obtain a synthesis gas rich in CO and H2. This reaction is endothermic and balanced and can be summarized as 1 CH4 and 1 H2O producing 1 CO and 3 H2 (in the case of methane for example).

[0120] Steam reforming is typically carried out by circulating the feedstock with added steam in tubes filled with catalyst, generally a nickel catalyst, for example comprising from 5 to 30% by weight of nickel deposited on a support comprising mainly alumina, or a mixture of alumina and one or more other refractory compounds. The tubes are typically heated by radiation in tube furnaces.

[0121] Excess steam is used to limit carbon deposits and increase the conversion.

[0122] This process is well suited to gaseous feedstocks, particularly natural gas, but also naphtha. The steam reforming reaction is favored by high temperatures and is generally carried out in a furnace. The heat required for the reaction is produced by the combustion with air of a fuel (e.g., natural gas or the hydrocarbon feedstock) in the steam reforming furnace.

[0123] The synthesis gas obtained by the steam reforming reaction mainly contains hydrogen, carbon monoxide, carbon dioxide, as well as water vapor and unconverted hydrocarbon feedstock.

[0124] Steam reforming is typically carried out at a temperature between 600°C and 900°C and at a pressure of up to 2.5 MPa, but can also be carried out at a temperature above 900°C.

[0125] The synthesis gas leaving the steam reforming furnace is then cooled and the condensed water is separated from the synthesis gas. The cooling of the synthesis gas leaving the steam reforming furnace can be done in an exchanger which produces steam.

[0126] Other technical elements relating to the steam reforming process can be found in the reference work: “Conversion processes”, P. Leprince, Editions Technip, 2001, Paris 15th, pages 455-495.

[0127] According to one or more embodiments, the unit for converting by-products into synthesis gas 28 comprises a steam reforming unit and a section for cooling the synthesis gas and separating condensed water, the steam reforming unit comprising at least one reactor used in at least one of the following operating conditions: - absolute pressure between 0.1 Mpa and 4 Mpa, and preferably between 1 Mpa and 3 Mpa; - temperature between 600°C and 1500°C, preferably between 700°C and 900°C; and - presence of a catalyst comprising nickel. Partial oxidation (POX)

[0128] Partial oxidation (POX), sometimes called partial oxidation gasification, is combustion with less than stoichiometric amounts of oxygen to form carbon dioxide and steam. Partial oxidation is slightly exothermic and can be used as an alternative to steam methane reforming to produce syngas. Partial oxidation can process light and heavy hydrocarbon feedstocks, asphalts, petroleum coke, but also coal and biomass (e.g., wood, green waste, etc.). Partial oxidation is preferably conducted at high temperatures (e.g., between 1100°C and 1500°C), high pressure (eg between 1 MPa and 9 MPa or more), in the presence of almost pure oxygen (purity greater than 98% by volume). The partial oxidation reaction itself corresponds to the reaction between 1 CH4 and 0.5 O2 to produce 1 CO and 2 H2 (in the case of methane for example). Partial oxidation is a reaction that brings the gas mixture to a temperature between 1100°C and 1500°C, by preheating the feedstock and the oxygen, for example to 250°C. A high temperature allows almost all of the feedstock to be converted and avoids the formation of soot. The quantity of oxygen typically used corresponds to 35% of the stoichiometric oxygen required for complete oxidation to CO2 and water.

[0129] To control the adiabatic flame temperature, which can rise to 1900°C with air and to 2800°C with 95% O2, an inert gas can be used, such as water vapor or carbon dioxide. The addition of water vapor will increase the molar ratio of H2 to CO in the synthesis gas produced, while the addition of carbon dioxide will reduce the molar ratio of H2 to CO in the synthesis gas produced.

[0130] The synthesis gas leaving the partial oxidation reactor is then cooled and the condensed water is separated from the synthesis gas. The cooling of the synthesis gas leaving the partial oxidation reactor can be done in an exchanger which produces steam.

[0131] The industrial process of partial oxidation is well known to those skilled in the art, a process marketed by Shell, Texaco, BASF-Lurgi, Air Liquide, etc. See, for example, the chapters Hydrogen, 2. Production (p. 249 vol. 18) and Carbon Monoxide (p. 679 vol. 6) of Ullmann's Encyclopedia of Industrial Chemistry.

[0132] Other technical elements relating to the partial oxidation process can be found in the reference work: "Conversion processes", P. Leprince, Editions Technip, 2001, Paris 15th, pages 455-495.

[0133] According to one or more embodiments, the unit for converting by-products into synthesis gas 28 comprises a partial oxidation unit preferably operated at oxygen stoichiometry so as to obtain the oxidation of the hydrocarbon mixture and so as to have a maximum concentration of carbon monoxide in the second synthesis gas 29.

[0134] According to one or more embodiments, the by-product conversion unit into synthesis gas 28 comprises a partial oxidation unit operated with an oxygen flow rate adjusted to have the desired temperature in the partial oxidation chamber and to minimize the light hydrocarbon content in the second synthesis gas 29.

[0135] According to one or more embodiments, the by-product conversion unit into synthesis gas 28 comprises a non-catalytic partial oxidation unit followed of a section for cooling the synthesis gas and separating the condensed water, the partial oxidation unit comprising at least one reactor used under at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 9 MPa, and preferably between 1 MPa and 4 MPa; - temperature between 600°C and 2000°C, preferably between 800°C and 1700°C, preferably between 1100°C and 1500°C; and - presence of oxygen used for combustion, with an oxygenation rate between 0.2 and 0.6, preferably between 0.25 and 0.5, in order to promote the formation of carbon monoxide. The oxygenation rate is defined as the ratio of the flow rate of oxygen consumed to the theoretical flow rate of oxygen for complete oxidation of all hydrocarbons into CO2 and water.

[0136] According to one or more embodiments, the unit for converting by-products into synthesis gas 28 comprises a catalytic partial oxidation unit followed by a section for cooling the synthesis gas and separating the condensed water, the partial oxidation unit comprising at least one reactor used in at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 9 MPa, and preferably between 0.1 MPa and 4 MPa; - temperature between 600°C and 2000°C, preferably between 800°C and 1700°C, preferably between 900°C and 1500°C; and - presence of oxygen used for combustion, with an oxygenation rate between 0.2 and 0.6, preferably between 0.25 and 0.5, in order to promote the formation of carbon monoxide. The oxygenation rate is defined as the ratio of the molar flow rate of injected oxygen to the theoretical oxygen flow rate for complete oxidation of all hydrocarbons; - presence of a catalyst containing nickel. Autothermal reforming (ATR)

[0137] Autothermal reforming (ATR), also called catalytic partial oxidation, consists of partial oxidation immediately followed by catalytic steam reforming in adiabatic regime at high temperature, for example in the outlet temperature range 900°C -1000°C. Autothermal reforming can tightly control the final composition of the syngas by combining non-catalytic partial oxidation with catalytic steam reforming in a single reactor. It consumes less oxygen than partial oxidation, but requires a catalytic bed. As with steam reforming, autothermal reforming can only process light feedstocks (gas, naphtha). The autothermal reforming reaction corresponds to the reaction between 1 CH4, 0.25 O2 and 0.5 H2O to produce 1 CO and 2.5 H2 (in the case of methane for example). In the autothermal reforming process, the hydrocarbon feedstock is mixed with steam and then optionally heated in a furnace before being introduced into an autothermal reactor. Oxygen is also introduced into the autothermal reactor. The heat required for the reaction is provided by the partial combustion of the feedstock with oxygen. The feedstock arrives at a pressure typically between 3 MPa and 10 MPa.

[0138] The autothermal reforming reactor comprises two successive zones: a first zone corresponding to a combustion chamber and a second zone with a catalytic bed. In the combustion chamber, the partial oxidation of the hydrocarbon feedstock takes place with oxygen burners. In the second zone, the synthesis gas produced in the combustion chamber passes through a catalytic bed in which the steam reforming reaction takes place.

[0139] The synthesis gas leaving the autothermal reforming reactor is then cooled and the condensed water is separated from the synthesis gas. The cooling of the synthesis gas leaving the autothermal reforming reactor can be done in an exchanger which produces steam.

[0140] Other technical elements relating to autothermal reforming processes can be found in the reference work: "Conversion processes", P. Leprince, Editions Technip, 2001, Paris 15th, pages 455-495.

[0141] According to one or more embodiments, the unit for converting by-products into synthesis gas 28 comprises an autothermal reforming unit followed by a section for cooling the synthesis gas and separating the condensed water, the autothermal reforming unit comprising at least one reactor used in at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 10 MPa, and preferably between 1 MPa and 4 MPa; - temperature between 800°C and 1100°C, preferably between 900°C and 1000°C; and - presence of a nickel catalyst. Combined Reforming (CR)

[0142] Combined reforming (CR), or two-stage reforming, comprises a first tubular steam reformer (steam reforming furnace) combined in series with a second autothermal reformer (reforming reactor) in which oxygen is added. A fraction of the feedstock may be sent directly to the second autothermal reformer.

[0143] As with steam reforming, the feedstock is mixed with steam and then preheated to about 500°C before entering the steam reforming furnace. The synthesis gas leaving the reforming furnace, rich in unconverted feedstock, is mixed with oxygen and sent to the autothermal reforming reactor. The synthesis gas leaving the autothermal reforming reactor has a temperature between 900°C and 1000°C. The synthesis gas leaving the autothermal reforming reactor is then cooled and the condensed water is separated from the synthesis gas. Cooling of the synthesis gas leaving the autothermal reforming reactor can be done in an exchanger that produces steam.

[0144] According to one or more embodiments, the unit for converting by-products into synthesis gas 28 comprises a combined reforming unit followed by a section for cooling the synthesis gas and separating the condensed water, the combined reforming unit comprising at least one reactor used in at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 10 MPa, and preferably between 1 MPa and 4 MPa; - temperature between 800°C and 1100°C, preferably between 900°C and 1000°C; and - presence of a nickel catalyst. Dry Reforming (DRM)

[0145] Dry reforming, also called carbon dioxide reforming, corresponds to the reaction between 1 CH4 and 1 CO2 to produce 2 CO and 2 H2 (in the case of methane for example). The name carbon dioxide reforming comes from the fact that carbon dioxide replaces the steam in conventional steam reforming. Dry reforming is particularly interesting if one is looking for a synthesis gas with a low H2 to CO molar ratio, of around 1. Dry reforming operates at a temperature generally between 900°C and 1000°C and at an operating pressure between 0.1 MPa and 2 MPa. The catalysts used are noble metal catalysts, nickel or nickel alloy.

[0146] The synthesis gas leaving the dry reforming reactor is then cooled and the condensed water is separated from the synthesis gas. Cooling of the synthesis gas leaving the dry reforming reactor can be done in an exchanger which produces steam.

[0147] According to one or more embodiments, the unit for converting by-products into synthesis gas 28 comprises a dry reforming unit followed by a section for cooling the synthesis gas and separating the condensed water, the dry reforming unit comprising at least one reactor used in at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 10 MPa, and preferably between 0.1 MPa and 4 MPa; - temperature between 800°C and 1100°C, preferably between 900°C and 1000°C; and - presence of a nickel catalyst.

[0148] According to one or more embodiments, a so-called "light" hydrocarbon cut (not shown) from the hydrogen reaction unit 20 is sent at least in part to the reaction unit for converting by-products into synthesis gas 28. According to one or more embodiments, the hydrocarbon cut comprises gaseous hydrocarbons such as paraffins from C1 to C4 (predominantly).

[0149] According to one or more embodiments, the second synthesis gas 29 produced in the reaction unit for converting by-products into synthesis gas 28, has an absolute pressure of between 0.1 MPa and 9 MPa, preferably between 0.1 MPa and 4 MPa.

[0150] According to one or more embodiments, the reaction unit for converting by-products into synthesis gas 28 provides the necessary calories to the RWGS reaction unit 8 and / or the carbon dioxide capture unit 2 and / or the carbon dioxide separation unit 34 via one or more heat exchanges.

[0151] According to one or more embodiments, the reaction unit for converting by-products into synthesis gas (28) is adapted to produce a third water vapor by (indirect) heat exchange between water (not shown) and an effluent leaving a reactor for converting by-products into synthesis gas, to optionally supply thermal energy to the carbon dioxide capture unit (2) and / or the carbon dioxide separation unit (34).

[0152] According to one or more embodiments, the reaction unit for converting by-products into synthesis gas 28 produces water, which is optionally sent to the water electrolysis unit 5.

[0153] Advantageously, the reaction unit for converting by-products into synthesis gas 28 makes it possible to convert substantially all of the hydrocarbon by-products of the process into CO, and therefore to recover them in the form of the desired products. Thus, the yield of desired products from the process according to the invention is improved.

[0154] The second synthesis gas 29 at the outlet of the reaction unit for converting by-products into synthesis gas 28 is recycled to the inlet of the carbon dioxide separation unit 34. The second synthesis gas 29 can be compressed and then optionally cooled before being sent to the carbon dioxide separation unit 34.

[0155] Hydrogen reaction unit (hydrotreatment and / or hydrocracking and / or hydroisomerization unit)

[0156] The hydrocarbon effluent 17 is sent to the hydrogen reaction unit 20 to undergo a hydrotreatment and / or hydrocracking and / or hydroisomerization reaction, in which one or more hydrocarbon cuts 21 can be recovered, in particular synthetic fuels, namely gasoline, kerosene, diesel, and / or other hydrocarbon products, such as naphtha, or very high-quality lubricating bases (essentially free of sulfur, aromatics, nitrogen). A possible option is the production of paraffinic cuts, basic products for petrochemical processes, for example the production of a C10-C13 cut intended for the production of linear alkyl benzene (or “LAB” for “Linear Alkyl Benzene” according to English terminology), or even waxes for various industrial applications. According to one or more embodiments, the hydrogen reaction unit 20 also produces by-products 41, comprising for example water and / or incondensable compounds, such as light gases comprising hydrocarbon compounds comprising from 1 to 4 carbon atoms.

[0157] According to one or more embodiments, the hydrogen reaction unit 20 comprises at least one reactor used under at least one of the following operating conditions: - temperature between 250°C and 450°C, more preferably between 280°C and 450°C, and even more preferably between 320°C and 420°C; - pressure between 0.2 MPa and 15 MPa, preferably between 0.5 MPa and 12 MPa, more preferably between 1 MPa and 10 MPa; - space velocity defined as being the ratio of the volume flow rate of the feed at ambient temperature and pressure to the volume of the catalyst, between 0.1 h 1 and 10 h 1, preferably between 0.2 h 1 and 7 h 1, more preferably between 0.5 h 1 and 5 h 1; - hydrogen flow rate between 100 and 2000 normal liters of hydrogen per liter of charge per hour and preferably between 150 and 1500 normal liters of hydrogen per liter of charge and more preferably between 300 and 1500 normal liters of hydrogen per liter of charge.

[0158] According to one or more embodiments, the hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst comprises at least one hydrogenating-dehydrogenating metal chosen from the group comprising the metals of group VIB and group VIIIB of the periodic table and at least one solid which is a Bronsted acid, i.e. a solid capable of releasing one or more protons, and optionally a binder.

[0159] According to one or more embodiments, the hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst comprises at least one noble metal from group VIIIB chosen from ruthenium, rhodium, palladium, osmium, iridium and platinum, taken alone or as a mixture, and preferably from platinum and palladium taken alone or as a mixture, and preferably used in their reduced form.

[0160] According to one or more embodiments, the hydrotreatment catalyst and / or hydrocracking and / or hydroisomerization comprises: at least one metal chosen from nickel, molybdenum, tungsten, cobalt, ruthenium, indium, palladium, platinum; at least one support chosen from aluminas, boron oxides, magnesias, zirconias, titanium oxides, clays. According to one or more embodiments, the support is an alumina, silica-alumina, alumina-silica, silica.

[0161] According to one or more embodiments, the hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst comprises at least one base metal from group VIIIB chosen from nickel and cobalt in combination with at least one metal from group VIB chosen from molybdenum and tungsten, used alone or as a mixture, and preferably used in their sulfurized form.

[0162] According to one or more embodiments, in the case where said hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst comprises at least one noble metal from group VIIIB, the noble metal content of said catalyst is between 0.01% and 5% by weight relative to the finished catalyst, preferably between 0.05% and 4% by weight and very preferably between 0.10% and 2% by weight.

[0163] According to one or more embodiments, in the case where said hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst comprises at least one metal from group VIB in combination with at least one non-noble metal from group VIII chosen from nickel and cobalt, the content of metal from group VIB in said catalyst is comprised in oxide equivalent between 5% and 40% by weight relative to the finished catalyst, preferably between 10% and 35% by weight, and the content of metal from group VIIIB in said catalyst is comprised in oxide equivalent between 0.5% and 15% by weight relative to the finished catalyst, preferably between 1% and 10% by weight, preferably between 1% and 8% by weight, and very preferably between 1.5% and 6% by weight.

[0164] According to one or more embodiments, the hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst comprises or consists of at least one noble metal and a support comprising or consisting of at least one zeolite and at least one binder.

[0165] According to one or more embodiments, the zeolite-based hydrotreatment and / or hydrocracking and / or hydroisomerization catalyst is advantageously of the bifunctional type, that is to say that it has a hydro-dehydrogenating function and a hydro-isomerizing function. Turbine (optional)

[0166] With reference to [Fig.l], according to one or more embodiments, the present invention makes it possible to recover energy in the form of electricity by means of at least one turbine 26.

[0167] According to one or more embodiments, the first turbine 26 is adapted to treat at least a portion 24 of the gaseous effluent 33 to produce electricity.

[0168] According to one or more embodiments, a second turbine (not shown) is adapted to process at least in part the first water vapor 22 and / or the second water vapor 23 and / or the third water vapor to produce electricity (not shown).

[0169] According to one or more embodiments, electricity is used to supply calories to the RWGS reaction unit 8 and / or to the carbon dioxide capture unit 2 and / or to the carbon dioxide separation unit 34 and / or to the water electrolysis unit 5. According to one or more embodiments, electricity 25 is used to supply calories to the RWGS reaction unit 8. According to one or more embodiments, electricity 25 can be used to power an electric furnace for preheating the feedstock of the RWGS reaction unit 8.

[0170] Effluent purification units (optional)

[0171] According to one or more embodiments, the carbon dioxide-rich effluent 3 and / or the carbon dioxide-rich gaseous effluent 35 are purified, separately or after mixing, before being introduced into the RWGS reaction unit 8. According to one or more embodiments, the carbon dioxide-depleted gaseous effluent 18 is purified before being introduced into the Fischer-Tropsch reaction unit 13. According to one or more embodiments, the first water effluent 11, and / or the second water effluent 16 is purified before being introduced into the water electrolysis unit 5. The effluent purification steps aim to at least partially remove organic compounds, ionic species, sulfur compounds, nitrogen compounds, halogenated compounds, metals such as heavy metals (e.g. density greater than 5 g / cm3) and transition metals.The main gas purification technologies are: adsorption, absorption, catalytic reactions. The main technologies for purifying aqueous effluents are known to those skilled in the art (e.g. distillation, filtration, reverse osmosis, ion exchange, precipitation).

[0172] In the present description, the groups of chemical elements are given by default according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIIIB according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUP AC classification; group VIB according to the CAS classification corresponds to the metals of column 6 according to the new IUPAC classification. Examples

[0173] The different examples concern sequences, compliant or non-compliant to the invention, the objective of which is to produce a hydrocarbon cut from fumes containing 21% by weight of carbon dioxide. The flow rate of fumes 1 to be treated (85000 kg / h) and the carbon dioxide capture unit 2 are identical for all the examples. The flow rate of effluent rich in carbon dioxide 3 is therefore 16025 kg / h for all the examples.

[0174] Example 1 not in accordance with the invention

[0175] Example 1 is not in accordance with the invention according to [Fig.l]. Example 1 is a process comprising the same units as the invention but in a different order. The carbon dioxide separation unit is located downstream of the Fischer-Tropsch reaction unit 13. Example 1 illustrates the operation of the RWGS unit 8, followed by the mixing of the first synthesis gas 12 with the second synthesis gas 29 from the reaction unit for converting by-products into synthesis gas 28. The mixture, the amount of H2 of which is adjusted with the optional hydrogen feed 36, is sent to the Fischer-Tropsch reaction unit 13. A portion of the gaseous effluent from the FT unit 24 is then sent to a carbon dioxide separation unit.The carbon dioxide-rich off-gas is sent to the inlet of RWGS section 8 and the carbon dioxide-lean off-gas is sent to the by-product conversion reaction unit into synthesis gas 28.

[0176] The electrical consumption of the water electrolysis unit 5 is 137.8 MWe.

[0177] The steam requirements of the reboiler of the carbon dioxide capture unit 2 and of the carbon dioxide separation unit 34 are completely covered by the first water vapor 22 generated by the FT reaction unit 13 and the second water vapor 23.

[0178] The reaction unit for converting by-products into synthesis gas 28 is a POX partial oxidation unit. The oxygen flow rate for the partial oxidation reaction unit 28 corresponds to the oxygen required to reach a temperature of 1350°C in the partial oxidation reactor.

[0179] Table 1 summarizes the input and output flow rates of the overall process of example 1 not in accordance with the invention.

[0180] [Tables 1] Input flow Flow rate in kg / h CO2 (3) 16025 H2 (7) 2756 O2 for 28 3847 Output flow Flow rate in kg / h 1st water effluent (11) 7391 2nd water effluent (16) 9112 Water produced by 28 990 Gaseous effluent (40) 60 Hydrocarbon cut (21) 4996 By-products (41) 79

[0181] The production of products of interest, i.e. hydrocarbon cut 21, is 4996 kg / h, i.e. a mass yield of 22.1% by weight relative to the sum of the charges (3 + 7 + O2).

[0182] Example 2 in accordance with the invention

[0183] Example 2 is in accordance with the invention according to [Fig.l]. This example illustrates the operation of the RWGS unit 8, followed by the mixing of the first synthesis gas 12 with the second synthesis gas 29 from the reaction unit for converting by-products into synthesis gas 28. The mixture is treated in the carbon dioxide separation unit 34 and the carbon dioxide-depleted gaseous effluent 18 is sent to the Fischer-Tropsch reaction unit 13. A portion of the gaseous effluent from the FT unit 24 is then sent to the reaction unit for converting by-products into synthesis gas 28.

[0184] The electrical consumption of the water electrolysis unit 5 is 130.8 MWe in the process according to the invention, i.e. 5% less than in example 1. It should be noted that the electrical consumption for the electrolysis of water 5 is the parameter which has the greatest weight for producing the hydrocarbon cut 21.

[0185] The steam requirements of the reboiler of the carbon dioxide capture unit 2 and of the carbon dioxide separation unit 34 are completely covered by the first water vapor 22 generated by the FT reaction unit 13 and the second water vapor 23.

[0186] The reaction unit for converting by-products into synthesis gas 28 is a POX partial oxidation unit. The oxygen flow rate for the partial oxidation reaction unit 28 corresponds to the oxygen required to reach a temperature temperature of 1350°C in the partial oxidation reactor.

[0187] Table 2 summarizes the input and output flow rates of the overall process of example 2 in accordance with the invention.

[0188] [Tables2] Input flow Flow rate in kg / h CO2 (3) 16025 H2 (7) 2615 O2 for 28 2607 Output flow Flow rate in kg / h 1st water effluent (11) 7017 2nd water effluent (16) 8564 Water produced by 28 530 Gaseous effluent (40) 60 Hydrocarbon cut (21) 4996 By-products (41) 80

[0189] The production of products of interest, i.e. the hydrocarbon cut 21, is 4996 kg / h, i.e. a mass yield of 23.5% by weight relative to the sum of the feed flow rates (3 + 7 + O2). The yield of product of interest is therefore improved in the process according to the invention.

Claims

Claims

1. Device for capturing and converting a feedstock containing carbon dioxide, comprising the following units: - a unit for capturing carbon dioxide (2) from the feedstock (1) adapted to produce a carbon dioxide-rich effluent (3); - a water electrolysis unit (5) adapted to convert water (4) to produce oxygen (6) and hydrogen (7); - a reverse water gas conversion reaction unit RWGS (8) adapted to treat the carbon dioxide-rich effluent (3) with hydrogen (7) and produce a first synthesis gas (12) and a first water effluent (11) optionally recycled at least in part to the inlet of the water electrolysis unit (5);- a carbon dioxide separation unit (34) adapted to treat the first synthesis gas (12), to produce a carbon dioxide-depleted gaseous effluent (18) and a carbon dioxide-rich gaseous effluent (35), and recycle the carbon dioxide-rich gaseous effluent (35) to the inlet of the RWGS section (8); - a Fischer-Tropsch reaction unit (13) adapted to convert the carbon dioxide-depleted gaseous effluent (18), produce a hydrocarbon effluent (17), a second water effluent (16) optionally recycled at least in part to the inlet of the water electrolysis unit (5), and a gaseous effluent (33); - a reaction unit for converting by-products into synthesis gas (28) adapted to convert at least a portion (24) of the gaseous effluent (33), produce a second synthesis gas (29) rich in carbon monoxide and hydrogen, and recycle the second synthesis gas (29) in the carbon dioxide separation unit (34);and - a hydrogen reaction unit (20) adapted to treat the hydrocarbon effluent (17) and produce at least one hydrocarbon cut (21).;

2. Device according to claim 1, in which the reaction unit for converting by-products into synthesis gas (28) is adapted to produce heat used to supply calories to the RWGS reaction unit (8) and / or the carbon dioxide capture unit (2).

3. A device according to claim 1 or claim 2, comprising a hydrogen supply (36) adapted to provide hydrogen in the carbon dioxide-depleted gaseous effluent (18).

4. A device according to any preceding claim, comprising a first turbine (26) for treating at least a portion (24) of the gaseous effluent (33) to produce electricity.

5. Device according to any one of the preceding claims, wherein: - the RWGS unit (8) is adapted to produce a second water vapor (23) by heat exchange between water and an effluent leaving a RWGS reactor, to optionally supply thermal energy to the carbon dioxide capture unit (2) and / or the carbon dioxide separation unit (34); and / or - the reaction unit for converting by-products into synthesis gas (28) is adapted to produce a third water vapor by heat exchange between water and an effluent leaving a reactor for converting by-products into synthesis gas, to optionally supply thermal energy to the carbon dioxide capture unit (2) and / or the carbon dioxide separation unit (34).

6. Device according to claim 5, comprising a second turbine adapted to process at least in part the first water vapor (22) and / or the second water vapor (23) and / or the third water vapor.

7. Device according to claim 6, wherein the electricity is used to supply calories to the RWGS reaction unit (8) and / or the carbon dioxide capture unit (2) and / or the carbon dioxide separation unit (34) and / or the water electrolysis unit (5).

8. A device according to claim 7, wherein the electricity is used to supply calories to the regeneration section of the carbon dioxide capture unit (2) and / or the carbon dioxide separation unit (34).

9. A device according to any preceding claim, wherein the water electrolysis unit (5) processes water from a make-up line and / or the RWGS reaction unit (8) and / or the Fischer-Tropsch reaction unit (13) and / or the by-product to synthesis gas conversion reaction unit (28).

10. A device according to any preceding claim, wherein the carbon dioxide-rich effluent (3) and / or the carbon dioxide-rich gaseous effluent (35) are purified, separately or after mixing, before being introduced into the RWGS reaction unit (8).

11. A method of capturing and converting carbon dioxide, comprising the following steps: - treating a load in a carbon dioxide capture unit (2) to produce an effluent rich in carbon dioxide (3); - converting water (4) in a water electrolysis unit (5) to produce oxygen (6) and hydrogen (7); - treating the carbon dioxide-rich effluent (3) with hydrogen (7) in a reverse water gas conversion reaction unit RWGS (8) to produce a first synthesis gas (12) and a first water effluent (11) optionally recycled at least in part to the inlet of the water electrolysis unit (5); - treating the first synthesis gas (12) in a carbon dioxide separation unit (34) to produce a carbon dioxide-depleted gaseous effluent (18) and a carbon dioxide-rich gaseous effluent (35); - recycle the carbon dioxide-rich gaseous effluent (35) at the entrance to the RWGS section (8); - converting the depleted gaseous effluent into carbon dioxide (18) in a Fischer-Tropsch reaction unit (13) to produce a hydrocarbon effluent (17), a second water effluent (16) optionally recycled at least in part to the inlet of the water electrolysis unit (5), and a gaseous effluent (33); - converting at least a portion (24) of the gaseous effluent (33) in a by-product conversion reaction unit into synthesis gas (28) to produce a second synthesis gas (29) rich in carbon monoxide and hydrogen; - recycle the second synthesis gas (29) into the carbon dioxide separation unit (34); and - treating the hydrocarbon effluent (17) in a hydrogen reaction unit (20) to produce at least one hydrocarbon cut (21).

12. A method according to claim 11, wherein the reaction unit of RWGS (8) comprises at least one reactor used under at least one of the following operating conditions: - temperature between 700°C and 1200°C, preferably between 800°C and 1100°C, and even more preferably between 850°C and 1050°C; - pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, and more preferably between between 0.1 MPa and 3.5 MPa; - gas space velocity at the reactor inlet of between 2000 NL / kgcata / h and 40000 NL / kgcata / h; - catalysts comprising a metal or a combination of metals chosen from the group consisting of the elements Ni, Cu, Fe, Co, Pt, Pd, Ru, Ag and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises a support, for example based on alumina, silica, silica-alumina, alumina-silica.

13. A method according to claim 11 or claim 12, wherein the Fischer-Tropsch reaction unit (13) comprises at least one reactor used under at least one of the following operating conditions: - temperature between 170°C and 280°C, preferably between 190°C and 260°C and preferentially between 21 CFC and 240°C; - absolute pressure between 1.0 MPa and 6.0 MPa, preferably between 1.5 MPa and 3.5 MPa and preferentially between 2.0 MPa and 3.0 MPa; - catalyst comprising cobalt or iron, preferably cobalt, the catalyst optionally comprising a support, for example based on alumina, silica, silica-alumina, alumina-silica or titanium.

14. A method according to any one of claims 11 to 13, wherein the reaction unit for converting by-products into synthesis gas (28) comprises at least one reactor used under at least one of the following operating conditions: - absolute pressure between 0.1 MPa and 9 MPa; - temperature between 600°C and 2000°C.

15. A method according to any one of claims 11 to 14, wherein the carbon dioxide capture unit (2) and / or the carbon dioxide separation unit (34) implements separation by chemical solvent and / or physical solvent and / or membrane and / or adsorption on a solid.

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