Amine-functionalized polymer membrane for the electrochemical reduction of CO2 to hydrocarbons

Abstract

The study deals with the electrochemical reduction of carbon dioxide (ERCO₂) at room temperature and pressure using an indigenously developed electrochemical reactor that employs impeded bulkier quaternary ammonium ions in a solid polymer structure. Solid polymer electrolytes possess the same polymer backbone but have distinct fixed functional groups. Polyethylenamine (PEI) is combined with alkali-doped polyvinyl alcohol (PVA) to form an anionic electrolyte PEI/PVA. Quaternary PEI/PVA electrolyte is generated by converting PEI to quaternary form followed by combining it with PVA. It is observed that fixed functional groups bonded in the solid polymer can greatly aid in tuning the reaction region. The synthesized quaternary PEI/PVA electrolyte exhibited better tensile strength (29.0 MPa) and ionic conductivity (9.06 mS cm⁻¹) than primary PEI (tensile strength = 18.0 MPa and ionic conductivity = 6.12 mS cm⁻¹). Furthermore, the selectivities of ethane and methane produced are 60.85% and 78.85%, respectively. A simple alteration of the functional group present in the membrane can have a profound effect on the selectivity of the reaction. This technique might pave the way for even further investigation into the potential for converting carbon dioxide gas into hydrocarbons.