Membrane-Coupled Cathode for the Reduction of Carbon Dioxide in Acid-Based Electrolytes Without Mobile Cations

Abstract

Various embodiments include an electrolysis cell comprising: a cathode space housing a cathode for the reduction of CO 2 ; a first ion exchange membrane including an anion exchanger and/or an anion transporter, the first ion exchange membrane adjoining the cathode space and in direct contact with the cathode; an anode space housing an anode; a first separator membrane; and a salt bridge space housing an electrolyte disposed between the first ion exchange membrane and the first separator membrane. The electrolyte in the salt bridge space comprises a liquid acid and/or a solution of an acid.

What is claimed is: 
     
         1 . An electrolysis cell comprising:
 a cathode space housing a cathode for the reduction of CO 2 ;   a first ion exchange membrane including an anion exchanger and/or an anion transporter, the first ion exchange membrane adjoining the cathode space and in direct contact with the cathode;   an anode space housing an anode;   a first separator membrane; and   a salt bridge space housing an electrolyte disposed between the first ion exchange membrane and the first separator membrane;   wherein the electrolyte in the salt bridge space comprises a liquid acid and/or a solution of an acid.   
     
     
         2 . An electrolysis cell comprising:
 a cathode space housing a cathode for reducing CO 2 ;   a first ion exchange membrane including an anion exchanger and/or anion transporter, the first ion exchange membrane adjoining the cathode space and in direct contact with the cathode; and   an anode space housing an anode and containing an electrolyte, the anode space adjoining the first ion exchange membrane;   wherein the electrolyte in the anode space comprises a liquid acid and/or a solution of an acid.   
     
     
         3 . The electrolysis cell as claimed in  claim 1 , wherein the second ion exchange membrane is selected from the group consisting of: an ion exchange membrane containing a cation exchanger, a bipolar membrane, and a diaphragm. 
     
     
         4 . The electrolysis cell as claimed in  claim 1 , wherein the anode space houses an anolyte comprising a liquid and/or dissolved acid. 
     
     
         5 . The electrolysis cell as claimed in  claim 2 , wherein the anode is in direct contact with the first ion exchange membrane. 
     
     
         6 . The electrolysis cell as claimed in  claim 1 , wherein the electrolysis is conducted with a current density of more than 50 mAcm −2 . 
     
     
         7 . The electrolysis cell as claimed in  claim 1 , wherein:
 an acid of the electrolyte in the salt bridge space has a pK A  of 6 or less; and   the liquid and/or dissolved acid comprises at least one acid selected from the group consisting of: dilute or neat H 2 SO 4 , a solution of H 2 N—SO 2 —OH, dilute or neat HClO 4 , a solution of H 3 PO 4 , dilute or neat CF 3 —COOH, dilute or neat CF 3 —SO 2 —OH, a solution of (CF 3 —SO 2 ) 2 —NH, a solution of HF, dilute or neat HCOOH, dilute or neat CH 3 —COOH, a solution of HCl, a solution of HBr, and a solution of HI.   
     
     
         8 . An electrolysis cell comprising:
 a cathode space housing a cathode;   a first ion exchange membrane including an anion exchanger and/or anion transporter, the first ion exchange membrane adjoining the cathode space in direct contact with the cathode;   an anode space housing an anode;   a diaphragm adjoining the anode space; and
 a salt bridge space disposed between the first ion exchange membrane and the diaphragm; 
   wherein the diaphragm is non-ion conductive.   
     
     
         9 . The electrolysis cell as claimed in  claim 8 , wherein at least one of:
 the anode is in contact with the diaphragm;   the anode is in contact with a conductive structure on the side remote from the salt bridge space; or   the cathode is in contact with a conductive structure on the side remote from the salt bridge space.   
     
     
         10 . The electrolysis cell as claimed in  claim 8 , wherein at least one of the cathode or the anode comprises at least one structure selected from the group consisting of: a gas diffusion electrode, a porous bound catalyst structure, a particulate catalyst on a support, a coating of a particulate catalyst on the first and/or second ion exchange membrane, a porous conductive carrier impregnated with a catalyst, and a noncontinuous sheetlike structure. 
     
     
         11 . The electrolysis cell as claimed in  claim 10 , wherein:
 the cathode comprises at least one structure selected from the group consisting of: a gas diffusion electrode, a porous bound catalyst structure, a particulate catalyst on a support, a coating of a particulate catalyst on the first and/or second ion exchange membrane, a porous conductive carrier impregnated with a catalyst, and of a noncontinuous sheetlike structure containing an anion exchange material and/or anion transport material; and   the anode comprises at least one structure selected from the group consisting of: a gas diffusion electrode, a porous bound catalyst structure, a particulate catalyst on a support, a coating of a particulate catalyst on the first and/or second ion exchange membrane, a porous conductive carrier impregnated with a catalyst, and a noncontinuous sheetlike structure containing a cation exchange material.   
     
     
         12 . The electrolysis cell as claimed in  claim 8 , wherein at least one of the first ion exchange membrane or the diaphragm is hydrophilic. 
     
     
         13 . The electrolysis cell as claimed in  claim 8 , wherein the electrolyte in the salt bridge space comprises a liquid acid and/or a solution of an acid. 
     
     
         14 . An electrolysis system comprising an electrolysis cell comprising:
 a cathode space housing a cathode;   a first ion exchange membrane including an anion exchanger and/or anion transporter, the first ion exchange membrane adjoining the cathode space in direct contact with the cathode;   an anode space housing an anode;   a diaphragm adjoining the anode space; and   a salt bridge space disposed between the first ion exchange membrane and the diaphragm;   wherein the diaphragm is non-ion conductive.   
     
     
         15 . The electrolysis system as claimed in  claim 14 , further comprising a recycling device connected to an outlet from the salt bridge space and an inlet to the cathode space, to return a reactant from the cathode reaction that can be formed in the salt bridge space to the cathode space. 
     
     
         16 . (canceled)