Self-cleaning co2 reduction system and related methods

Abstract

A self-cleaning CO2 reduction strategy is proposed herein including alternating operation and regeneration of the CO2 electrolysis system. The strategy includes application of short and periodic reductions in applied voltage, thereby avoiding saturation and prevention of carbonate salt formation.

1 - 32 . (canceled) 
     
     
         33 . A method for reducing CO 2  in an electrolytical system and/or for self-cleaning a gas diffusion electrode in an electrolytical system operating CO 2  reduction, the method comprising:
 applying an operational voltage to the electrolytical system to operate CO 2  reduction for a first period of time defining an operation cycle, thereby forming carbonate ions at a cathode side of the electrolytical system and having a local carbonate ion concentration; and   subsequently applying a regeneration voltage to the electrolytical system for a second period of time defining a regeneration cycle to force electromigration of the formed carbonate ions to an anode side of the electrolytical system;   characterized in that the regeneration voltage is lower than the operational voltage and the operational voltage is between −3.0 and −4.5 V.   
     
     
         34 . The method of  claim 33 , characterized in that the duration of the operation cycle is chosen to maintain the local carbonate ion concentration at the cathode side below a carbonate salt solubility limit. 
     
     
         35 . The method of  claim 33 , characterized in that the first period of time is at between 1 second and 1200 seconds. 
     
     
         36 . The method of  claim 33 , characterized in that the first period of time is at between 60 seconds and 300 seconds. 
     
     
         37 . The method of  claim 33 , characterized in that the second period of time is between 1 second and 60 seconds. 
     
     
         38 . The method of  claim 33 , characterized in that said method further comprises repeating the operation cycle and the regeneration cycle by alternating a voltage applied to the electrolytic system between the operational voltage and the lower regeneration voltage. 
     
     
         39 . The method of  claim 38 , characterized in that each operation cycle is performed for the same duration. 
     
     
         40 . The method of  claim 38 , characterized in that each regeneration cycle is performed for the same duration. 
     
     
         41 . The method of  claim 38 , characterized in that the duration of each operation cycle varies between 1 second and 1200 seconds. 
     
     
         42 . The method of  claim 38 , characterized in that the duration of each regeneration cycle varies between 1 second and 60 seconds. 
     
     
         43 . The method of  claim 33 , characterized in that the regeneration voltage is chosen to obtain a CO 2  reduction rate below 1 mA·cm −2 . 
     
     
         44 . The method of  claim 33  characterized in that the operational voltage is between −3.2 and −4.0 V. 
     
     
         45 . The method of  claim 33 , characterized in that the regeneration voltage is between −2.5 V and −5.0 V. 
     
     
         46 . The method of  claim 33 , characterized in that the electrolytical system is a membrane electrode assembly (MEA) comprising a gas diffusion electrode serving as a cathode. 
     
     
         47 . The method of  claim 33 , characterized in that the electrolytical system is a flow cell system comprising a liquid catholyte and a gas diffusion electrode serving as a cathode. 
     
     
         48 . The method of  claim 46 , characterized in that the cathode comprises a metal layer deposited on substrate. 
     
     
         49 . The method of  claim 48 , characterized in that the cathode comprises a silver layer deposited on a carbon paper substrate. 
     
     
         50 . The method of  claim 48 , characterized in that the cathode comprises a copper layer deposited on a PTFE substrate. 
     
     
         51 . The method of  claim 33 , characterized in that the electrolytical system comprises an anolyte. 
     
     
         52 . The method of  claim 51 , characterized in the anolyte is an aqueous solution of one or more alkaline compounds, said one or more alkaline compounds comprising one alkali metal cations selected from lithium, sodium, potassium, rubidium, caesium and any combination thereof.