Apparatus and method of preparing carbonate and/or formate from carbon dioxide

An apparatus for preparing carbonate and/or formate from carbon dioxide (CO2), comprising:

• an electrolysis reactor comprising (i) an anode which contains an aqueous solution of a Group I metal salt as an electrolytic solution, (ii) an ion-exchange membrane through which metal cations derived from the Group I metal salt and water flow from the anode to a cathode, (iii) the cathode, and (iv) a gas diffusion layer which supplies a carbon dioxide-containing gas to the cathode;
• a power supply unit for applying a voltage between the anode and the cathode;
• a first gas-liquid separator for recovering the electrolytic solution from products formed in the anode;
• a second gas-liquid separator for recovering carbonate and/or formate from products formed in the cathode;
• an ion electrode for measuring the concentration of the carbonate and/or formate recovered from the second gas-liquid separator;
• a pH meter for measuring a pH of the electrolytic solution recovered from the first gas-liquid separator;
• a first reactant supply unit for supplying (a) the electrolytic solution recovered from the first gas-liquid separator and (b) the aqueous solution of the Group I metal salt with which the recovered electrolytic solution is replenished according to the pH of the electrolytic solution, to the anode;
• and
• a second reactant supply unit for supplying carbon dioxide or a mixture comprising carbon dioxide and water vapor to the cathode;
• wherein, when a voltage is applied between the anode and the cathode,
• in the anode, water undergoes electrolysis to generate hydrogen ions, oxygen, and electrons, and the metal cations in the Group I metal salt are substituted with the hydrogen ions, while the generated metal cations move to the cathode through the ion-exchange membrane and the electrons move to the cathode through an external electric line;
• and
• in the cathode, the carbon dioxide, water, metal cations, and electrons are reacted and produce carbonate and/or formate;
• wherein the apparatus is configured to supply water to the cathode from the anode through the ion-exchange membrane;
• wherein the apparatus does not comprise a unit for supplying a cathode electrolytic solution to the cathode;
• wherein the electrolysis reactor comprises:
• (ii) the ion-exchange membrane;
• (i) the anode, which comprises an anode catalyst layer applied to a first surface of (ii) the ion-exchange membrane;
• an electrically conductive structure for providing a space for the flow of the electrolytic solution;
• and a current collector in which a flow path for supplying reactants of the water and metal cations and a flow path for releasing the products are formed;
• and
• (iii) the cathode, which comprises a cathode catalyst layer applied to a second surface of (ii) the ion-exchange membrane;
• (iv) the gas diffusion layer;
• and a current collector in which a flow path for supplying reactants of the carbon dioxide and a flow path for releasing the products are formed;
• wherein the water which moves from the anode to the cathode through the ion-exchange membrane, the water vapor in the carbon dioxide-containing gas, or both forms a water film on the surface of a cathode catalyst layer;
• wherein the cathode catalyst layer has a particulate structure or a porous structure, and the cathode catalyst layer is configured to promote formation of the water film on the surface of the cathode catalyst layer;
• wherein the electrolytic solution to be supplied to the anode is the aqueous solution of a Group I metal salt at a concentration of 0.1 M to 2 M;
• and
• wherein the concentration of the carbonate and/or formate recovered from the second gas-liquid separator is regulated by supplying additional water vapor to the cathode according to the concentration of the carbonate and/or formate recovered from the second gas-liquid separator.