EP2766514A2

EP2766514A2 - Method and system for treating carbon gases by electrochemical hydrogenation in order to obtain a cxhyoz compound

Info

Publication number: EP2766514A2
Application number: EP12780242.9A
Authority: EP
Inventors: Béatrice Sala; Frédéric GRASSET; Olivier Lacroix; Abdelkader SIRAT; Elodie TETARD; Kamal Rahmouni; Joel ZOYER
Original assignee: Areva SA
Current assignee: Areva SA
Priority date: 2011-10-12
Filing date: 2012-10-11
Publication date: 2014-08-20
Also published as: RU2014118837A; CN104024479A; WO2013054053A2; FR2981369B1; US20140291162A1; IN2014DN03032A; FR2981369A1; JP2014528519A; BR112014008751A2; WO2013054053A3

Abstract

The present invention relates to a method for treating CO₂ by electrochemical hydrogenation, said method comprising: a step of transferring heat from a heating means (160) towards a proton-conductive electrolyser (110) such that said electrolyser (110) reaches an operating temperature suitable for electrolysing steam; a step of feeding the CO₂ produced by said heating means (160) at the cathode of the electrolyser; a step of feeding the steam at the anode; a step of oxidising the steam at the anode; a step of generating protonated species in the membrane with proton conduction; a step of migrating said protonated species into said proton-conductive membrane; a step of reducing said protonated species on the surface of the cathode into reactive hydrogen atoms; and a step of hydrogenating the CO₂ on the surface of the cathode of the electrolyser (110) by means of said reactive hydrogen atoms, said hydrogenation step enabling the formation of C_xH_yO_z compounds, where x≥1; 0<y≤(2x+2) and 0≤z≤2x.

Description

Process and system for treating carbonaceous gases by electrochemical hydrogenation to obtain a compound of the type C _x H _y O _z

The present invention relates to a method and a system for treating carbonaceous gases - carbon dioxide (CO 2) and / or carbon monoxide (CO) - from highly reactive hydrogen generated by electrolysis of water to produce water. obtaining a compound of the type CxH _y O _z , in particular with x>1; 0 <y≤ (2x + 2) and 0 <z≤2x.

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:

- the electrolysis of water at high temperature for the production of hydrogen,

in the treatment of carbonaceous gases (C0 ₂ , CO) by electrochemical hydrogenation to obtain compounds of the CxH _y Oz type (x>1; 0 <y≤ (2x + 2) and 0 <z≤2x), 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 production method, illustrated in Figure 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 1 1 providing the electrolyte function separating an anode 12 and a cathode 13.

The application of a potential difference between the anode 12 and the cathode 13 causes an oxidation of the water vapor H ₂ O on the anode side 12. The water vapor introduced into the anode 12 is thus oxidized to form oxygen 0 ₂ and H ⁺ ions (or OH ₀ in the Kröger-Vink notation), this reaction releasing electrons e ^" following the equation:

H ₂ 0 + 20o → 20H ₀ + ^ 0 ₂ + 2e '

The H ⁺ ions (or OH ₀ in the Kröger-Vink notation) migrate through the electrolyte 11, to form hydrogen H ₂ on the surface of the cathode 13 according to the equation:

2nd + 20H ₀ → 20 * + H ₂

Thus, this process provides at the outlet of the electrolyzer 10 pure hydrogen - cathode compartment - and oxygen mixed with water vapor - anodic compartment.

More specifically, the formation of H ₂ passes through 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 radical hydrogen atoms ^. (or H _tectrode in the Kröger-Vink notation). These species being highly reactive, they usually recombine to form hydrogen H ₂ according to the equation:

Electrode ^→ ^ 2

These highly reactive species are used to carry out the treatment of carbonaceous gases (CO ₂ , CO) by electrochemical hydrogenation so as to obtain at the outlet of the electrolyser 10 compounds of the type C _x H _y Oz. (X>1; 0 < y≤ (2x + 2) and 0 <z≤2x, according to the following relation:

(4x - 2z + y) H * _electrode + xC0 ₂ → C _x H _y O _z + (2x - z) H ₂ 0

The object of the invention is to promote the carbonaceous gases resulting for example from the production of heating from carbon products (coal, wood, oil), or the incineration of waste, and to optimally reduce the production of gas. greenhouse effect for carrying out the hydrogenation treatment.

To this end, the invention proposes a method for treating CO ₂ and / or CO by electrochemical hydrogenation to obtain a compound of type C _x H _y O _z, with x>1; 0 <y≤ (2x + 2) and z between 0 and 2x, said CO ₂ and / or CO being obtained by the combustion of carbonaceous products via heating means (160), said method comprising:

a step of transferring heat from the heating means to a proton conductive electrolyser so that said electrolyzer reaches an operating temperature T1 for electrolysis of water vapor, said proton conduction electrolyser comprising a membrane with protonic conduction 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 anode of said electrolyzer;

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 hydrogenation of 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 C _x H _y O type; _z , with x>1; 0 <y≤ (2x + 2) and 0 <z≤2x.

By reactive hydrogen atoms are meant atoms absorbed on the surface of the cathode and / or radical hydrogen atoms H (or Hf _{ieci: rode} in the Kröger-Vink notation).

Thus, the process according to the invention makes it possible to recover the carbon dioxide produced by heating means resulting from the combustion of carbonaceous products by jointly using the electrolysis of water vapor, which generates highly reactive hydrogen at the cathode. the electrolyser with electrocatalyzed hydrogenation of the carbonaceous products injected cathode level of the electrolyzer by reaction with highly reactive hydrogen.

By way of example, these compounds of the C _x H _y O _{z type} are paraffins C _n H _{2n + 2} , olefins C _2n H ₂ n, alcohols C _n H ₂ n ₊ ₂ 0H or Ο _η Η _2η - ιΟΗ, aldehydes and ketones C _n H _2n O.

Advantageously, the compounds C _x H _y O _z produced are components for feeding the combustion of the heating means so as to reduce the external input of carbon 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 conducting electrolyser into temperature, the setting of the temperature of the electrolyser being necessary for the production of 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 method 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 compounds of the type

CxHyOz produced by hydrogenation as fuel of said heating means:

prior to the use of the compounds of the type C _x H _y O _z as fuel of said heating means, said method comprises a phase separation step for injecting into the heating means the compounds of the type C _x H _y O _z 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 means of heating to obtain pure CO ₂ and / or CO;

said step of oxidizing the water vapor at 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 electrolyser,

said method comprises a step of reinjection of oxygen in gaseous form into said heating means;

the method comprises a step of controlling the nature of the CxH _y Oz type compounds formed as a function of the potential and / or the current applied to the cathode or to the terminals of the electrolyser;

the compounds of the type C _x H _y O _z 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 compounds of the type C _x H _y O _z are formed carbonaceous combustibles;

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 electrolyser being positioned in said 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. to 650 ° C. ° 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 subject of the invention is also a system for treating carbonaceous gases by electrochemical hydrogenation for implementing the method according to the invention, said system comprising:

heating means emitting CO ₂ and / or CO by the combustion of carbonaceous 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 pressurized insertion of water vapor into said electrolyte via said anode:

means for introducing under pressure the CO ₂ and / or CO produced by the heating means on the surface of the cathode of the electrolyser;

means for evacuating the CxH _y Oz type compounds formed by hydrogenation on the surface of the cathode of the electrolyzer;

means for evacuating 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, as an indication and in no way limiting, with reference to the appended figures, among which:

FIG. 1, already described, is a simplified schematic representation of a proton-conductive water vapor electrolyser,

FIG. 2 is a schematic representation of a system for treating carbonaceous gases produced by a boiler during the combustion of carbonaceous products; 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 carbonaceous gas treatment system 100 for implementing the method according to the invention.

The treatment system 100 comprises:

heating means 160, such as a boiler, discharging CO ₂ 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 CO ₂ and / or CO;

a proton conduction electrolyser 1 10 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 1 10;

means 41 for inserting, preferably under pressure, steam pH ₂ 0 in the electrolyte through the anode 32;

means 42 for introducing, advantageously under pressure, the pCO ₂ and / or purified pCO on the surface of the cathode 33 of the electrolyser 1 10;

means for discharging the CxH _y Oz compounds formed by hydrogenation on the surface of the cathode 33 of the electrolyser 1 10; means for evacuating the oxygen generated at the anode 32 by the electrolysis reaction of the water vapor.

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 1 used to form compounds of the CxH _y Oz type, (with x> 1, 0 <y≤ (2x + 2) and 0 <z <2x) following the reduction of CO ₂ and / or CO. At the anode 32, the water is oxidized by releasing electrons while H ⁺ ions (in OH ₀ form) are generated.

These H ⁺ ions migrate through the electrolyte 31 and are therefore likely to react with various compounds that would be injected at the cathode 33, the carbon compounds of the type C0 ₂ and / or CO reacting at the cathode 33 with these H ⁺ ions to form compounds of type C _x H _y O _z (with x> 1, 0 <y≤ (2x + 2) and 0 <z≤2x) and water at cathode 33.

The chemical equations of the different reactions can be written in particular:

(end + 2) H _E ^x _electrode + nC0 ₂ → C _n H _{2n + 2} + 2nH ₂ 0

6 "H Electrode + nC0 ₂ → C _n H _2n + 2nH ₂ 0

6nH _E ^x _electrode + nC0 ₂ → C _n H _{2n + 2} 0 + (2n - 1) H ₂ 0

(end - 2) H _E ^x _electrode + nC0 ₂ → C _n H _2n O + (2n - 1) H ₂ 0

Since the nature of the compound formed depends on the operating conditions, the overall formation reaction of C _x H _y O _z can therefore be written as follows:

(4x - 2z + y) H _E ^x _electrode + xC0 ₂ → C _x H _y O _z + (2x - z) H ₂ 0

The nature of the compounds C _x H _y O _z synthesized at the cathode 33 depends on numerous operating parameters such as, for example, the pressure of the cathode compartment, the partial pressure of the gases, the operating temperature T1, the potential / current / torque. voltage applied to the cathode 33 or the terminals of the electrolyzer, 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 1 10 a combustible compound capable of supplying the combustion of the boiler 160.

It is also advantageous that these operating parameters are defined so as to produce hydrogen at the same time as the compound C _x HyOz _. The hydrogen / compound mixture C _x H _y O _z has the advantage of aiding the combustion of the compound C _x H _y O _z 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 having the particularity of not oxidizing 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 electrodes 32 and 33 and electrolyte 31 is a zirconate perovskite of formula of general formula AZrO 3 that 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 (H ₂ ) and argon (Ar) or 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 type 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 AZr0 ₃ . 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. Ceramic 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 compound C _x H _y O _z synthesized at the cathode 33 of the electrolyser 1 10. The condenser 130 makes it possible to separate the compound C _x H _y O _z in the state gas and water that are produced by the hydrogenation reaction. Thus, the condenser 130 traps the water in liquid form making it possible to obtain, at the outlet of the condenser 130, only the compound C _x H _y O _z synthesized in the gaseous state (combustible carbon compounds in the embodiment shown in FIG. Figure 2). The compound CxH _y O _z is then injected into the carbonaceous feed system of the boiler 160 after dehydration in a desiccant cartridge 170. The addition of the synthesized compound C _x H _y O _z reduces the specific carbon 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 C _x H _y O _z 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. Oxygen being mixed with the water at the outlet of the electrolyser 1 10, the condenser 140 makes it possible to separate 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 1 10 is brought to temperature by heat transfer from the boiler 160 to the electrolyser 1 10 so that the electrolyser reaches the temperature T1 greater than or equal to 200 ° C. and less than or equal to 800 ° 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 1 10 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 (not shown) making it possible to transfer 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 electrolyser, 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 electrolyzer so as to forming the water vapor capable of being 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 carbon products (coal, wood, oil), or the incineration of waste.

Claims

A method of treating CO ₂ and / or CO by electrochemical hydrogenation to obtain a C _x H _y O _z compound with x>1; 0 <y≤ (2x + 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 step of transferring heat from the heating means (160) to a proton conduction electrolyser (1 10) so that said electrolyser (1 10) reaches an operating temperature (T1) for electrolysis of steam of water, said proton conduction electrolyser (1 10) 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 conduction electrolyser (1 10),

a step of introducing water vapor at the anode (32) of said electrolyser (1 10);

a step of oxidizing the water vapor at 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 electrolyser (1 10) by means of said reactive hydrogen atoms, said hydrogenation step making it possible to form compounds of the type C _x H _y O _z, with x>1; 0 <y≤ (2x + 2) and 0 <z≤2x. A method for treating CO ₂ and / or CO by electrochemical hydrogenation according to claim 1 characterized in that said process comprises a step of using CxHyO 2 type compounds produced by hydrogenation as fuel of said heating means (160).

3. A method for treating CO ₂ and / or CO by electrochemical hydrogenation according to one of claims 1 to 2 characterized in that prior to the use of compounds CxHyOz type as fuel of said heating means (160), said method comprises a phase separation step for injecting into the heating means (160) type compounds CxH _y O _z only gaseous: 4. a method of treatment of CO ₂ and / or CO by electrochemical hydrogenation according to the 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 (1 10) said method comprises a step of purifying CO ₂ and / or CO produced by said heating means so as to obtain pure CO ₂ and / or CO.

Process for treating CO ₂ and / or CO by electrochemical hydrogenation according to one of Claims 1 to 4, characterized in that the said step of oxidation of the water vapor at the level of the anode (32) generates oxygen at the outlet of the electrolyser (1 10). 6. A method for treating CO ₂ 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 electrolyser (1 10).

7. A method of treating CO ₂ 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 in said heating means (160).

8. A method for treating CO ₂ 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 the compounds CxH _y Oz type formed according to the potential and / or current applied to the cathode (33) or the terminals of the electrolyser (1 10).

9. Process for treating CO ₂ and / or CO by electrochemical hydrogenation according to one of claims 1 to 8, characterized in that the compounds of CxH _y Oz type 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.

10. A method of treating CO ₂ and / or CO by electrochemical hydrogenation according to one of claims 1 to 9 characterized in that the CxHyOz type compounds formed are combustible carbon compounds.

1 1. Process for treating CO ₂ and / or CO by electrochemical hydrogenation according to one of Claims 1 to 10, characterized in that the said step of transferring heat from the heating means (160) to the said electrolyser (1 10) is carried out at means of a heat exchanger.

12. A method for treating CO ₂ 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 (1 10) is produced by direct heat transfer, said electrolyser (1 10) being positioned in a heat zone (150) in the vicinity of said heat means (160).

13. A method for treating CO ₂ 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 conductive electrolyser (1 10) is carried out so that said electrolyser (1 10) reaches a temperature (T1) greater than or equal to 200 ° C and less than or equal to 800 ° C, preferably between 350 ° C and 650 ° C.

14. A method of treating CO ₂ 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 conductive electrolyser (1 10) is carried out so that said electrolyser (1 10) reaches a temperature (T1) of between 500 ° C and 600 ° C.

15. A system for treating carbonaceous gases by electrochemical hydrogenation (100) for implementing the method according to one of claims 1 to 14, said system comprising:

heating means (160) emitting CO ₂ and / or CO by the combustion of carbonaceous products;

a proton-conductive electrolyser (1 10) comprising an electrolyte (31) in the form of a proton conducting membrane, an anode (32) and a cathode (33); said electrolyser (1 10) being positioned near the heating means (160);

means (42) for the insertion under pressure of water vapor into said electrolyte (1 10) via said anode (32):

- means (41) for introducing under pressure CO ₂ and / or CO produced by the heating means (160) on the surface of the cathode (33) of the electrolyser (1 10); means for evacuating the CxH _y Oz type compounds formed by hydrogenation on the surface of the cathode (33) of the electrolyzer (1 10);

means for evacuating the oxygen and water generated at the anode by the electrolysis reaction of the water vapor.

16. A system for treating electrochemically hydrogenated carbonaceous gases (100) according to claim 15, characterized in that the heating means are formed by a boiler.