Electrolyser device and method for carbon dioxide reduction

Abstract

An electrolyser for carbon dioxide reduction, having an electrolytic cell, with a cathode gas diffusion electrode and an anode gas diffusion electrode, in which a first side of the cathode gas diffusion electrode adjoins a cathode gas chamber in a planar manner and likewise a first side of the anode gas diffusion electrode adjoins an anode gas chamber, and an electrolyte chamber common to both gas diffusion electrodes is provided, which extends from the cathode gas diffusion electrode to the anode gas diffusion electrode and is at least partially delimited by the two gas diffusion electrodes with their second sides facing away from the respectively associated gas chambers.

1 .- 13 . (canceled) 
     
     
         14 . An electrolyzer for carbon dioxide reduction, comprising:
 an electrolytic cell, having a cathode gas diffusion electrode and also having an anode gas diffusion electrode,   wherein the cathode gas diffusion electrode at a first side areally adjoins a cathode gas space and the anode gas diffusion electrode likewise with a first side adjoins an anode gas space, and   wherein an electrolyte space common to both gas diffusion electrodes is provided, which reaches from the cathode gas diffusion electrode to the anode gas diffusion electrode and is bounded at least in sections by the two gas diffusion electrodes with their second sides facing away from the respectively assigned gas spaces,   wherein the anode gas diffusion electrode has a cation-selective coating,   wherein the anode gas diffusion electrode is coated with an ion-conducting polymer, and   wherein the cathode gas space has a reactant gas supply apparatus and a product gas outlet apparatus.   
     
     
         15 . The electrolyzer as claimed in  claim 14 ,
 wherein the electrolyte space is provided with an electrolyte feedline and an electrolyte drain line, which together with a pumping apparatus form an electrolyte circuit.   
     
     
         16 . The electrolyzer as claimed in  claim 14 ,
 wherein a CO 2  deposition apparatus is provided in the electrolyte circuit.   
     
     
         17 . The electrolyzer as claimed in  claim 16 ,
 wherein there is a connecting line from the CO 2  deposition apparatus to the reactant gas supply apparatus.   
     
     
         18 . The electrolyzer as claimed in  claim 14 ,
 wherein an oxygen exhaust apparatus is provided at the anode gas space.   
     
     
         19 . A method for operating an electrolyzer, comprising:
 introducing a CO 2 -containing reactant gas into a cathode gas space,   reducing the CO 2  at least partly to CO at a cathode gas diffusion electrode, wherein the cathode gas diffusion electrode abuts the cathode gas space with a first side and abuts an electrolyte space with the opposite second side,   flowing a liquid electrolyte through the electrolyte space,   dissolving CO 2  in the electrolyte, and   releasing molecular oxygen O 2  at an anode gas diffusion electrode surface and diffusing the molecular oxygen O 2  through an anode gas diffusion electrode,   wherein both the cathode gas diffusion electrode and the anode gas diffusion electrode, each with a second side, adjoin the common electrolyte space, and   discharging the CO 2  dissolved in the electrolyte therefrom outside the electrolyte space,   wherein the anode gas diffusion electrode has a cation-selective coating, where the anode gas diffusion electrode is coated with an ion-conducting polymer.   
     
     
         20 . The method as claimed in  claim 19 ,
 wherein the electrolyte comprises an aqueous salt solution, where the dissolved salt is not based on a salt of carbonic acid.   
     
     
         21 . The method as claimed in  claim 19 ,
 wherein the pH of the electrolyte is less than 7.   
     
     
         22 . The method as claimed in  claim 21 ,
 wherein pH of the electrolyte is between 2 and 7.   
     
     
         23 . The method as claimed in  claim 19 ,
 wherein the CO 2  discharged from the electrolyte is supplied to the CO 2 -containing reactant gas.   
     
     
         24 . The method as claimed in  claim 19 ,
 wherein a gas volume flow of the CO 2  at the gas diffusion cathode is at least 5 times as great as at the gas diffusion anode.   
     
     
         25 . The method as claimed in  claim 24 ,
 wherein a gas volume flow of the CO 2  at the gas diffusion cathode is at least 15 times as great as at the gas diffusion anode