Process and system for the selective electrochemical reduction of CO2 in acidic conditions

A method for electrochemical production of ethylene comprising the steps of:

• providing an acidic catholyte;
• providing a multilayer cathode in said acidic catholyte;
• wherein the multilayer cathode comprises a gas diffusion layer and a cathode catalyst layer;
• contacting carbon dioxide with the multilayer cathode, such that the carbon dioxide diffuses through the gas diffusion layer and contacts the cathode catalyst layer;
• applying a voltage to provide a current density to cause the carbon dioxide contacting the cathode catalyst layer to be electrochemically reduced into the ethylene;
• and
• recovering ethylene;
• wherein the multilayer cathode comprises a surface-modified catalyst deposited on the gas diffusion layer, wherein the surface-modified catalyst comprises:
• a cathode catalyst material with a surface presenting at least one active site for sustaining reduction of CO2 into ethylene, wherein the cathode catalyst material is copper or an alloy thereof;
• and
• one or more heterocyclic organic molecules which are adsorbed on the surface of the cathode catalyst material, wherein the one or more heterocyclic organic molecules are or comprise one or more aromatic heterocyclic amine molecules selected from 1,7-phenanthroline, 1,10-phenanthroline, adenine, and benzotriazole;
• the acidic catholyte has a pH ranging from 0.5 to 2.8
• the one or more heterocyclic organic molecules are provided in the acidic catholyte stream that flows along the cathode catalyst layer at a concentration ranging from 0.1 mM to 1.0 mM.