Two-membrane construction for electrochemically reducing CO2
Various embodiments include an electrolysis cell comprising: a cathode space housing a cathode; a first ion exchange membrane including an anion exchanger and adjoining the cathode space; an anode space housing an anode; a second ion exchange membrane including a cation exchanger and adjoining the anode space; and a salt bridge space disposed between the first ion exchange membrane and the second ion exchange membrane. The cathode comprises: a gas diffusion electrode having a porous bound catalyst structure of a particulate catalyst on a support; a coating of a particulate catalyst on the first and/or second ion exchange membrane; and a porous conductive support impregnated with a catalyst.
1. An electrolysis system comprising:
an electrolysis cell comprising:
a cathode space housing a cathode;
a first ion exchange membrane including an anion exchanger and adjoining the cathode space;
an anode space housing an anode;
a second ion exchange membrane comprising a bipolar membrane including a cation exchanger and an anion exchanger, the second ion exchange membrane adjoining the anode space;
a salt bridge space disposed between the first ion exchange membrane and the second ion exchange membrane; and
an electrolyte fed into the salt bridge space, the electrolyte comprising an aqueous solution of conductive salts;
wherein the cathode comprises a porous conductive support impregnated with a catalyst comprising an ionomer at least partially penetrating the porous conductive support and acting as a fixed electrolyte; and
a recycling unit connected to an outlet from the salt bridge and an inlet into the cathode space.
2. The electrolysis system as claimed in claim 1 ,
wherein the recycling unit conducts a reactant from the cathode reaction formed in the salt bridge space back into the cathode space.
3. The electrolysis cell as claimed in claim 1 , wherein the cathode is in contact with the first ion exchange membrane.
4. The electrolysis cell as claimed in claim 1 , wherein the anode is in contact with the second ion exchange membrane.
5. The electrolysis cell as claimed in claim 1 , wherein the second ion exchange membrane comprises a bipolar membrane.
6. The electrolysis cell as claimed in claim 1 , wherein at least one of the first ion exchange membrane and the second ion exchange membrane is hydrophilic.
7. The electrolysis cell as claimed in claim 1 , wherein at least one of the anode and the cathode is in contact with a conductive structure on a side remote from the salt bridge space.