FR2981369A1 - METHOD AND SYSTEM FOR TREATING CARBON GASES BY ELECTROCHEMICAL HYDROGENATION FOR OBTAINING A CXHYOZ-TYPE COMPOUND - Google Patents

Abstract

The present invention relates to a method for treating CO by electrochemical hydrogenation, said method comprising a step of transferring heat from heating means (160) to a proton conduction electrolyser (110) so that said electrolyser (110) reaches an operating temperature for performing electrolysis of water vapor, said electrolyser; a CO introduction step produced by said heating means (160) at the cathode of the electrolyser; a step of introducing water vapor at the level of the anode; a step of oxidation of the water vapor at the level of the anode; a step of generating protonated species in the proton-conduction membrane; a step of migration of said protonated species in said proton-conduction membrane; a step of reducing said protonated species on the surface of the cathode in the form of reactive hydrogen atoms; a step of hydrogenation of CO on the surface of the cathode of the electrolyzer (110) by means of said reactive hydrogen atoms, said hydrogenation step making it possible to form compounds of the type C H O, with x> = 1; 0 <y <= (2x + 2) and 0 <= z <= 2x.

Description

The present invention relates to a process and system for the treatment of carbonaceous gases - carbon dioxide (CO2) and / or carbon monoxide (CO). carbon (CO) - from highly reactive hydrogen generated by electrolysis of water to obtain a compound of CxHyOz type, in particular with; O <K2x + 2) and Oz2x. Conductive ceramic membranes are now the subject of much research to increase their performance; in particular, these membranes find particularly interesting applications in the fields of: - the electrolysis of water at high temperature for the production of hydrogen, - in the treatment of carbonaceous gases (CO2, CO) by electrochemical hydrogenation for the obtaining compounds of the type CxHyOz (; O <K2x + 2) and Oz2x), the patent application WO2009150352 describes an example of such a method. At present, two methods of producing electrolysis of water vapor are known: electrolysis using anionic conductors O 2 and operating at temperatures generally between 750 ° C. and 1000 ° C .; electrolysis using the protonic conductors involved in this patent.

The mode of production, illustrated in FIG. 1, uses an electrolyte capable of driving the protons and operating at temperatures generally between 200 ° C. and 800 ° C. More precisely, this FIG. 1 schematically represents an electrolyzer 10 comprising a proton-conducting ceramic membrane 11 providing the electrolyte function separating an anode 12 and a method 13. The application of a potential difference between the anode 12 and the method 13 causes oxidation of the water vapor H2O at the anode side 12. The water vapor introduced into the anode 12 is thus oxidized to form oxygen O 2 and ions H + (or 014 in Kffiger-Vink notation), this reaction releasing electrons e- following the equation: H + 200x 20H +102 + 2e + H + ions (or 014 in Kffiger-Vink notation) migrate through the electrolyte 11, to form hydrogen H2 on the surface of the cathode 13 according to the equation: + 201- -> 20 + H2 Thus, this process provides at the output of the electrolyser 10 of pure hydrogen - cathodic compartment - and oxygen mixed with water vapor -compartment nodique. Specifically, the formation of H 2 involves the formation of intermediate compounds which are hydrogen atoms adsorbed on the surface of the cathode with varying energies and degrees of interaction and / or hydrogen atoms radicals H '(or H EXlectrode in Kffiger-Vink notation). Since these species are highly reactive, they usually recombine to form hydrogen H2 according to the equation: 2H EXlectrode -> H2 These highly reactive species are used to treat carbonaceous gases (CO2, CO) by electrochemical hydrogenation in order to obtain at the outlet of the electrolyser 10 compounds of the type CxHyOz (; O <K2x + 2) and Oz2x, in the following relation: (4x - 2z + y) Heiectrode xCO2 -> CxHyOz + (2x - z) The aim of the invention is to enhance the carbonaceous gases resulting for example from the production of heating from carbonaceous products (charcoal, wood, oil), or the incineration of waste, and to reduce in an optimum manner the production of greenhouse gases for carrying out the hydrogenation treatment. To this end, the invention proposes a process for treating CO 2 and / or CO by electrochemical hydrogenation to obtain a CxHyO 2 type compound, with x 1; O <K2x + 2) and z ranging between 0 and 2x, said CO 2 and / or CO being obtained by the combustion of carbonaceous products via heating means (160), said process comprising: a heat transfer step of heating means to a proton-conductive electrolyser so that said electrolyzer reaches an operating temperature T1 to effect electrolysis of water vapor, said proton conduction electrolyser comprising a proton-conduction membrane disposed between an anode and a cathode; a step of introducing CO 2 and / or CO produced by said heating means at the cathode of the proton conducting electrolyser, a step of introducing water vapor at the level of the anode of said electrolyser; a step of oxidation of the water vapor at the level of the anode; a step of generating protonated species in the proton-conduction membrane following said oxidation step; a step of migration of said protonated species into said proton-conduction membrane; a step of reducing said protonated species on the surface of the cathode in the form of reactive hydrogen atoms; a step of hydrogenating CO 2 and / or CO on the surface of the cathode of the electrolyzer by means of said reactive hydrogen atoms, said hydrogenation step making it possible to form compounds of the CxHyO 2 type, with x 1; 0 <K2x + 2) and 0z2x. Reactive hydrogen atoms are understood to be atoms absorbed on the surface of the cathode and / or radical hydrogen atoms H (or Helectrode in the Kffiger-Vink notation). Thus, the process according to the invention makes it possible to recover the carbon gases produced by heating means resulting from the combustion of carbonaceous products by jointly using the electrolysis of water vapor which generates highly reactive hydrogen with the cathode of the electrolyzer with electrocatalyzed hydrogenation of the carbonaceous products injected at the cathode of the electrolyzer by reaction with highly reactive hydrogen. By way of example, these compounds of the CxHyO 2 type are CnH 2n + paraffins, C2nH2n olefins, CnH2n + 20H or CnH2n_10H alcohols, CnH2nO aldehydes and ketones. Advantageously, the CxHyO 2 compounds produced are components making it possible to feed the combustion of the heating means so as to reduce the external supply of carbonaceous products. Advantageously, the compounds formed are combustible carbonaceous products, such as for example aliphatics or aromatics belonging to the family of alkanes, alkenes or alkynes, substituted or unsubstituted, which may include one or more functions alcohol, aldehyde, ketone, acetal, ether, peroxide, ester, anhydride. The invention also makes it possible to advantageously use the heat produced by the heating means (resulting from the combustion of carbonaceous products) to bring the proton-conductive electrolyser into temperature, the temperature setting of the electrolyser being necessary for carrying out the electrolysis reaction and the electrocatalyzed hydrogenation reaction. Thus, the electrolyser does not require the use of expensive specific heating means and greenhouse gas generator. The process according to the invention may also have one or more of the following characteristics, considered individually or in any technically possible combination: the process comprises a step of using the CxHyO 2 type compounds produced by hydrogenation as fuel for said heating means: - prior to the use of the CxHyO 2 type compounds as fuel of said heating means, said method comprises a phase separation step for injecting into the heating means the CxHyO 2 type compounds only in gaseous form: prior to said step of introducing CO 2 and / or CO produced by said heating means into the cathode compartment of the electrolyser, said method comprises a step of purifying the CO 2 and / or CO produced by said heating means in order to obtain pure CO2 and / or CO; said step of oxidation of the water vapor at the level of the anode generates oxygen at the outlet of the anode compartment; said method comprises a step of phase separation of the oxygen produced by said electrolyzer; said method comprises a step of reinjection of the oxygen in gaseous form into said heating means; the method comprises a step of controlling the nature of the CxHyO 2 type compounds formed as a function of the potential and / or of the current applied to the cathode or to the terminals of the electrolyzer; - CxHyOz type compounds formed belong to the family of alkanes or alkenes or alkynes, substituted or unsubstituted, which may include one or more functions alcohol or aldehyde or ketone or acetal or ether or peroxide or ester or anhydride; the CxHyO 2 type compounds formed are combustible carbon compounds; said step of transferring heat from the heating means to said electrolyser is carried out by means of a heat exchanger: said step of transferring heat from the heating means to said electrolyser is carried out by direct heat transfer, said elec- a trolyser being positioned in a heat zone in the vicinity of said heat means; the heat transfer from the heating means to a proton-conductive electrolyser is carried out so that said electrolyser reaches a temperature greater than or equal to 200 ° C. and less than or equal to 800 ° C., advantageously lying in the range 350 ° C. C and 650 ° C; the heat transfer from the heating means to a proton-conductive electrolyser is carried out in such a way that said electrolyser reaches a temperature of between 500 ° C. and 600 ° C. The invention also relates to a system for treating carbonaceous gases by electrochemical hydrogenation for carrying out the process according to the invention, said system comprising: heating means emitting CO2 and / or CO by the combustion of carbon products; a proton-conductive electrolyser comprising an electrolyte in the form of a proton conducting membrane, an anode and a cathode; said electrolyser being positioned near the heating means; means for the insertion under pressure of water vapor into said electrolyte via said anode; means for introducing under pressure CO2 and / or CO produced by the heating means on the surface of the cathode of the the electrolyser; means for evacuating the CxHyO 2 type compounds formed by hydrogenation on the surface of the cathode of the electrolyser; means for evacuating the oxygen and water generated at the anode by the electrolysis reaction of the water vapor. According to an advantageous embodiment of the invention, the heating means are formed by a boiler. Other features and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the appended figures, among which: FIG. 1, already described 2 is a schematic representation of a system for treating carbonaceous gases produced by a boiler during the combustion of products. carbonaceous; FIG. 3 is a general simplified schematic representation of an electrolysis cell for implementing the method according to the invention. FIG. 2 schematically represents a carbon gas treatment system 100 enabling the method according to the invention to be implemented. The treatment system 100 comprises: - heating means 160, such as a boiler, discharging CO2 and / or CO and other gases resulting from the combustion of carbonaceous products used for the production of heat; a purifier 120 making it possible to purify gases discharged by the boiler 160 so as to isolate the CO2 and / or CO; a proton conducting electrolyser 110 comprising an electrolyte 31 in the form of a proton conducting membrane, an anode 32 and a cathode 33 (FIG. 3); means 34 (FIG. 3) for inducing a current flowing between the anode 32 and the cathode 34 of the electrolyser 110; means 41 for inserting, advantageously under pressure, water vapor pH2O into the electrolyte via the anode 32; means 42 for introducing, advantageously under pressure, the pCO2 and / or purified pCO on the surface of the cathode 33 of the electrolyser 110; means for evacuating the CxHyO 2 type compounds formed by hydrogenation on the surface of the cathode 33 of the electrolyzer 110; means for evacuating the oxygen generated at the anode 32 by the electrolysis reaction of the steam. The means 34 for inducing a current flowing between the anode 32 and the cathode 34 may be a voltage generator, a current generator or a potentiostat (in this case, the cell will also comprise at least one cathodic or anodic reference electrode).

FIG. 3 illustrates in more detail an exemplary embodiment of an electrolysis cell 30 of the electrolyser 110 used to form compounds of the CxHyOz type, (with x1, 0 <K2x + 2) and (:) z 2x ) following the reduction of CO2 and / or CO.

At the anode 32, the water is oxidized by releasing electrons while H + ions (in form 014) are generated. These H + ions migrate through the electrolyte 31 and are therefore capable of reacting with various compounds that would be injected at the cathode 33, the carbon compounds of the CO 2 and / or CO type reacting at the cathode 33 with these H + ions to form compounds of the type CxHy0, (with x1, O <K2x + 2) and Oz2x) and water at the cathode 33. The chemical equations of the various reactions can in particular be written: (6n + 2) 1 / Exi ' ## STR1 ## ) H20 (6n - 2) HExi''ode + nCO2-> C'112,, 0 + (2n -1) H20 The nature of the compound formed depends on the operating conditions, the global formation reaction of CxHyOz can therefore be written The nature of the CxHyO 2 compounds synthesized at cathode 33 depends on numerous operating parameters such as, for example, the pressure of the compartment. cathodic, partial pressure of gases, temperature e T1 of operation, the potential / current / voltage torque applied to the cathode 33 or to the terminals of the electrolyser, the residence time of the gas and the nature of the electrodes. The operating temperature T1 of the electrolyser is in the range between 200 and 800 ° C, preferably between 350 ° C and 650 ° C. The operating temperature T1 in this temperature range will also depend on the nature of the CxHyO 2 carbon compounds that it is desired to generate.

These operating parameters are defined so as to form, at the outlet of the cathode 33 of the electrolyser 110, a combustible compound capable of supplying the combustion of the boiler 160. It is also advantageous if these operating parameters are defined so as to produce hydrogen at the same time as the compound CxHyOz. The hydrogen / CxHyO 2 compound mixture has the advantage of aiding the combustion of the CxHyO 2 compound in the heating means. According to an exemplary embodiment, the operating parameters are defined so as to obtain a mixture formed by 90% of CxHyO 2 compound and 10% of hydrogen. According to a first embodiment, the anode 32 and the cathode 33 are preferably formed by a cermet constituted by the mixture of a proton-conductive ceramic and an electrically conductive passivable alloy which is capable of forming an oxide layer protection so as to protect it in an oxidizing environment (ie at the anode of an electrolyser). This passivable alloy is preferably a metal alloy. The passivable alloy comprises, for example, chromium (and preferably at least 40% of chromium) so as to have a cermet exhibiting the particularity of not oxidizing in temperature. The chromium content of the alloy is determined so that the melting point of the alloy is greater than the sintering temperature of the ceramic. By sintering temperature is meant the sintering temperature necessary to sinter the electrolyte membrane so as to make it gas tight.

The chromium alloy may also include a transition metal so as to maintain an electronic conductive character of the passive layer. Thus, the chromium alloy is an alloy of chromium and one of the following transition metals: cobalt, nickel, iron, titanium, niobium, molybdenum, tantalum, tungsten, etc.

The ceramic of the anode and cathode electrodes 32 and 33 is advantageously the same ceramic as that used for producing the electrolyte membrane of the electrolyte 31.

According to an advantageous embodiment of the invention, the proton-conducting ceramic used for producing the cermet of the electrodes 32 and 33 and of the electrolyte 31 is a zirconate perovskite of formula of general formula AZrO 3 which can advantageously be doped with an element A selected from lanthanides. The use of this type of ceramic for the production of the membrane therefore requires the use of a high sintering temperature in order to obtain a densification sufficient to be gastight. The sintering temperature of the electrolyte 31 is more particularly defined according to the nature of the ceramic but also as a function of the desired porosity level. Conventionally, it is estimated that to be gas-tight, the electrolyte 31 must have a porosity of less than 6% (or a density greater than 94%). Advantageously, the sintering of the ceramic is carried out under a reducing atmosphere so as to avoid the oxidation of the metal at high temperature, that is to say under an atmosphere of hydrogen (H2) and argon (Ar), even carbon monoxide (CO) if there is no risk of carburation. The electrodes 32 and 33 of the cell 30 are also sintered at a temperature above 1500 ° C. (according to the example of sintering a zirconate ceramic). According to a second embodiment, the anode 32 and the cathode 33 may also be formed by a ceramic material which is a perovskite doped with a lanthanide. Perovskite can be a zirconate of formula AZrO3. The zirconate is doped with a lanthanide which is, for example, erbium. In addition, the lanthanide-doped perovskite is doped with a doping element taken from the following group: niobium, tantalum, vanadium, phosphorus, arsenic, antimony, bismuth. These doping elements are chosen to dope the ceramic since they can go from an oxidation degree of 5 to an oxidation degree of 3, which allows to release oxygen during sintering. More specifically, the doping element is preferably niobium or tantalum. Each electrode may also comprise a metal mixed with the ceramic so as to form a cermet. The ceramic comprises for example between 0.1% and 0.5% by weight of niobium, between 4 and 4.5% by weight of erbium and the remainder of zirconate. Boosting the ceramic with niobium, tantalum, vanadium, phosphorus, arsenic, antimony or bismuth makes the ceramic conductive electrons. The ceramic is then a mixed conduction ceramic; in other words, it is conducting both electrons and protons while in the absence of these doping elements, the perovskite doped with a lanthanide with a single degree of oxidation is not electron conducting. Such a configuration makes it possible to have electrodes made of a material of the same nature as the solid electrolyte which has good conductivity of both protons and electrons, even when the ceramic is not mixed with a metal ( as is the case of the first embodiment). The system 100 further comprises a condenser 130 receiving as input the CxHyO 2 compound synthesized at the cathode 33 of the electrolyser 110. The condenser 130 makes it possible to separate the CxHyO 2 compound in the gaseous state and the water which are produced by the reaction. hydrogenation. Thus, the condenser 130 traps water in liquid form to obtain at the outlet of the condenser 130 only the compound CxHyOz synthesized in the gaseous state (combustible carbon compounds in the embodiment shown in Figure 2). The CxHyO 2 compound is then injected into the carbonaceous feed system of the boiler 160 after dehydration in a desiccant cartridge 170. The addition of the synthesized CxHyO 2 compound makes it possible to reduce the specific supply of carbonaceous products. The system according to the invention therefore makes it possible to operate in a semi-closed circuit, the external supply of fuel being reduced by supplying the boiler with the compound CxHyO 2 synthesized. The water recovered in the condenser 130 is then reinjected into the water supply circuit so as to limit the external influx of water. Similarly to the preceding paragraph, the system 100 also comprises a condenser 140 receiving as input the oxygen produced by electrolysis of the water vapor at the anode 31. The oxygen being mixed with the outlet water of the electrolyser 110, the condenser 140 separates the oxygen from the water. The oxygen is then reinjected into the boiler 160 to feed the combustion of the carbonaceous products, and the water is reinjected into the water supply circuit. The oxygen thus injected makes it possible to carry out an oxy-combustion by directly using the oxygen leaving the electrolyser as an oxidizer instead of air. The condensers 130 and 140 also have the function of cooling the compounds entering the condensers so as to reinject into the various circuits of the system 100 compounds cooled to a temperature between 80 and 85 ° C. The electrolyser 110 is brought to temperature by heat transfer from the boiler 160 to the electrolyser 110 so that the electrolyser reaches the temperature T1 greater than or equal to 200 ° C. and less than or equal to 800 ° C. C, advantageously between 350 ° C and 650 ° C. In order to obtain hydrogenated organic compounds, the temperature T1 of the electrolyser must advantageously be between 500 ° C. and 600 ° C. According to a first exemplary embodiment, the heat transfer is carried out by positioning the electrolyser 110 in a heat zone 150 around the boiler 160. According to a second exemplary embodiment, the heat transfer is carried out by means of a heat exchanger heat (not shown) for transferring the thermal energy produced by the boiler to the electrolyser.

According to a particular non-limiting embodiment, the system further comprises a turbine positioned at the outlet of the electrolyzer, and more specifically at the anode outlet (steam) and / or cathode of the electrolyser. In FIG. 2, such a turbine is illustrated as a dashed example by reference numeral 50. In this example, the turbine is positioned in the path of the output gas stream at the anode of the electrolyser . Such a turbine is adapted to generate electricity by passing the gas stream. According to an advantageous embodiment of the invention, the electricity produced then makes it possible to feed the electrolyser electrically.

Thus, this particular embodiment makes it possible to reduce the power consumption of a specific generator in order to generate a potential difference across the electrolyser. According to a particular non-limiting embodiment, the system according to the invention comprises thermoelectric devices advantageously placed so as to recover the heat of the products formed by the electrolysis reaction of the water. According to a particular non-limiting embodiment, the system comprises a heat exchanger adapted to cool the oxygen / water mixture generated at the anode by the electrolysis reaction and to heat the water entering the reactor. electrolyzer so as to form water vapor adapted to be inserted into the electrolyte via the anode. The invention finds a particularly advantageous application for upgrading carbonaceous gases resulting for example from the production of heating from carbonaceous products (coal, wood, oil), or the incineration of waste.

Claims (16)

REVENDICATIONS1. Process for the treatment of CO2 and / or CO by Claims 1. Process for the treatment of CO2 and / or CO by electrochemical hydrogenation to obtain a compound of the CxHyOz type, with x1; O <K2x + 2) and z ranging from 0 to 2x, said CO 2 and / or CO being obtained by the combustion of carbonaceous products via heating means (160), said process comprising: - a transfer step of heat of the heating means (160) to a proton-conductive electrolyser (110) so that said electrolyser (110) reaches an operating temperature (T1) for electrolysis of water vapor, said electrolyser proton conduction (110) having a proton conduction membrane (31) disposed between an anode (32) and a cathode (33); a step of introducing CO 2 and / or CO produced by said heating means (160) at the cathode (33) of the proton conducting electrolyser (110); water at the anode (32) of said electrolyzer (110); a step of oxidation of the water vapor at the level of the anode (32); a step of generating protonated species in the proton-conduction membrane (31) following said oxidation step; a step of migration of said protonated species into said proton-conduction membrane (31); a step of reducing said protonated species on the surface of the cathode (33) in the form of reactive hydrogen atoms; a step of hydrogenation of CO 2 and / or CO on the surface of the cathode (33) of the electrolyzer (110) by means of said reactive hydrogen atoms, said hydrogenation step making it possible to form compounds of the type CxHyOz, with x1; 0 <K2x + 2) and Oz2x. 2. A method for treating CO2 and / or CO by electrochemical hydrogenation according to claim 1 characterized in that said method comprises a step of using CxHyOz type compounds produced by hydrogenation as fuel of said heating means (160). 3. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 2 characterized in that prior to the use of CxHyOz type compounds as fuel of said heating means (160), said method comprises a phase separation step for injecting into the heating means (160) the compounds of CxHyOz only gaseous type: 4. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 3 characterized in that prior to said step of introducing CO 2 and / or CO produced by said heating means (160). ) at the cathode (32) of the electrolyser (110), said method comprises a step of purifying the CO2 and / or CO produced by said heating means so as to obtain pure CO2 and / or CO. 5. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 4 characterized in that said step of oxidation of the water vapor at the anode (32) generates the oxygen at the outlet of the electrolyser (110). 6. A method for treating CO2 and / or CO by electrochemical hydrogenation according to claim 5 characterized in that said method comprises a step of phase separation of the oxygen produced by said electrolyzer (110). 7. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 5 to 6 characterized in that said method comprises a step of reinjection of gaseous oxygen into said heating means (160). 8. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 7 characterized in that the method comprises a step of controlling the nature of compounds of CxHyOz type formed according to the potential and / or current applied to the cathode (33) or to the terminals of the electrolyser (110). 9. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 8 characterized in that the CxHyOz type compounds formed belong to the family of alkanes or alkenes or alkynes, substituted or unsubstituted , which may include one or more alcohol or aldehyde or ketone or acetal or ether or peroxide or ester or anhydride functions. 10. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 9 characterized in that the compounds CxHyOz type formed are combustible carbon compounds. 11. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 10 characterized in that said step of transferring heat from the heating means (160) to said electrolyzer (110) is carried out at means of a heat exchanger. 12. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 10 characterized in that said step of transferring heat from the heating means (160) to said electrolyzer (110) is carried out bytransfert direct heat, said electrolyzer (110) being positioned in a heat zone (150) in the vicinity of said heat means (160). 13. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 12 characterized in that said heat transfer from the heating means (160) to a proton conduction electrolyzer (110) is realized in such a way that said electrolyser (110) reaches a temperature (T1) greater than or equal to 200 ° C and less than or equal to 800 ° C, advantageously between 350 ° C and 650 ° C. 14. A method for treating CO2 and / or CO by electrochemical hydrogenation according to one of claims 1 to 12 characterized in that said heat transfer from the heating means (160) to a proton conduction electrolyzer (110) is achieved in such a way that said electrolyser (110) reaches a temperature (T1) of between 500 ° C and 600 ° C. 15. A system for treating carbonaceous gases by electrochemical hydrogenation (100) for carrying out the method according to one of claims 1 to 14, said system comprising: - heating means (160) emitting CO2 and / or CO by the combustion of carbonaceous products; a proton-conductive electrolyser (110) comprising an electrolyte (31) in the form of a proton conducting membrane, an anode (32) and a cathode (33); said electrolyser (110) being positioned near the heating means (160); means (42) for the insertion under pressure of water vapor into said electrolyte (110) via said anode (32); means (41) for introducing under pressure CO2 and / or CO produced by the heating means (160) on the surface of the cathode (33) of the electrolyser (110); - means for discharging the CxHyO 2 type compounds formed by hydrogenation on the surface of the cathode (33) of the electrolyser ( 110); means for evacuating the oxygen and water generated at the anode by the electrolysis reaction of the water vapor. 16. A system for treating carbonaceous gases by electrochemical hydrogenation (100) according to claim 15 characterized in that the heating means are formed by a boiler.