METHOD AND SYSTEM FOR TREATING CARBON GASES BY ELECTROCHEMICAL HYDROGENATION IN ORDER TO OBTAIN A CxHyOz COMPOUND

Abstract

The present invention relates to a method for treating CO 2 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 CO 2 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 CO 2 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 x H y O z compounds, where x≧1; 0<y≦(2x+2) and 0≦z≦2x.

1 . A Method for treating CO 2  and/or CO by electrochemical hydrogenation in order to obtain a C x H y O z  type compound, where x≧1; 0<y≦(2x+2) and z is comprised between 0 and 2x, said CO 2  and/or CO being obtained by the combustion of carbon products via heating means, said method comprising:
 a step of transferring heat from the heating means to a proton-conducting electrolyser such that said electrolyser reaches an operating temperature (T1) suitable for electrolysing steam, said proton-conducting electrolyser comprising a proton-conducting membrane arranged between an anode and a cathode; 
 a step of feeding the CO 2  and/or CO produced by said heating means at the cathode of the proton-conducting electrolyser, 
 a step of feeding steam at the anode of said electrolyser; 
 a step of oxidising the steam at the anode; 
 a step of generating protonated species in the proton-conducting membrane after said step of oxidation; 
 a step of migrating said protonated species in said proton-conducting 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 electrolyser by means of said reactive hydrogen atoms, said hydrogenation step making it possible to form C X H y O Z  type compounds where x≧1; 0<y≦(2x+2) and 0≦z≦2x. 
 
     
     
         2 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1  wherein said method comprises a step of using C X H y O Z  type compounds produced by hydrogenation as fuel for said heating means. 
     
     
         3 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein prior to the use of C X H y O Z  type compounds as fuel for said heating means, said method comprises a step of phase separation making it possible to inject into the heating means uniquely gaseous C X H y O z  type compounds: 
     
     
         4 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein prior to said step of introducing the CO 2  and/or the CO produced by said heating means at the cathode of the electrolyser, said method comprises a step of purifying the CO 2  and/or the CO produced by said heating means so as to obtain pure CO 2  and/or CO. 
     
     
         5 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein said step of oxidising the steam at the anode generates oxygen at the outlet of the electrolyser. 
     
     
         6 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 5  wherein said method comprises a step of phase separation of the oxygen produced by said electrolyser. 
     
     
         7 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein said method comprises a step of re-injecting gaseous oxygen into said heating means. 
     
     
         8 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein the method comprises a step of controlling the nature of the C X H y O Z  type compounds formed as a function of the potential and/or the current applied at the cathode ( 33 ) or at the terminals of the electrolyser. 
     
     
         9 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein the C X H y O Z  type compounds formed belong to the family of alkanes or alkenes or alkynes, substituted or not, being able to include one or more alcohol or aldehyde or ketone or acetal or ether or peroxide or ester or anhydride functions. 
     
     
         10 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein the C X H y O Z  type compounds formed are carbon compound fuels. 
     
     
         11 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein said step of heat transfer from the heating means to said electrolyser is carried out by means of a heat exchanger. 
     
     
         12 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein said step of heat transfer from the heating means to said electrolyser is carried out by direct heat transfer, said electrolyser being positioned in a heat area in the vicinity of said heating means. 
     
     
         13 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein said heat transfer from the heating means to a proton-conducting electrolyser is carried out such that said electrolyser reaches a temperature (T1) not less than 200° C. and not more than 800° C., advantageously comprised between 350° C. and 650° C. 
     
     
         14 . The Method for treating CO 2  and/or CO by electrochemical hydrogenation according to  claim 1 , wherein said heat transfer from the heating means to a proton-conducting electrolyser is carried out such that said electrolyser reaches a temperature (T1) comprised between 500° C. and 600° C. 
     
     
         15 . A System for treating carbon gases by electrochemical hydrogenation for the implementation of the method according to  claim 1 , said system comprising:
 heating means emitting CO 2  and/or CO through the combustion of carbon products;   a proton-conducting electrolyser comprising an electrolyte in the form of a proton-conducting membrane, an anode and a cathode; said electrolyser being positioned in the vicinity of the heating means;   means for inserting under pressure steam into said electrolyte via said anode;   means for feeding under pressure the CO 2  and/or the CO produced by the heating means on the surface of the cathode of the electrolyser;   means for evacuating the C X H y O Z  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 steam electrolysis reaction.   
     
     
         16 . The System for treating carbon gases by electrochemical hydrogenation according to  claim 15  wherein the heating means are formed of a boiler.