High Pressure Electrochemical Reduction of CO2 to Formic Acid/Formate: A Comparison between Bipolar Membranes and Cation Exchange Membranes

Mahinder Ramdin; Andrew R T Morrison; Mariette de Groen; Rien van Haperen; Robert de Kler; Leo J P van den Broeke; J P Martin Trusler; Wiebren de Jong; Thijs J H Vlugt

doi:10.1021/acs.iecr.8b04944

High Pressure Electrochemical Reduction of CO₂ to Formic Acid/Formate: A Comparison between Bipolar Membranes and Cation Exchange Membranes

Ind Eng Chem Res. 2019 Feb 6;58(5):1834-1847. doi: 10.1021/acs.iecr.8b04944. Epub 2019 Jan 14.

Authors

Mahinder Ramdin¹, Andrew R T Morrison², Mariette de Groen³, Rien van Haperen³, Robert de Kler³, Leo J P van den Broeke³, J P Martin Trusler⁴, Wiebren de Jong², Thijs J H Vlugt¹

Affiliations

¹ Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
² Large-Scale Energy Storage, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
³ Coval Energy, Wilhelminasingel 14, 4818AA Breda, The Netherlands.
⁴ Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.

Abstract

A high pressure semicontinuous batch electrolyzer is used to convert CO₂ to formic acid/formate on a tin-based cathode using bipolar membranes (BPMs) and cation exchange membranes (CEMs). The effects of CO₂ pressure up to 50 bar, electrolyte concentration, flow rate, cell potential, and the two types of membranes on the current density (CD) and Faraday efficiency (FE) for formic acid/formate are investigated. Increasing the CO₂ pressure yields a high FE up to 90% at a cell potential of 3.5 V and a CD of ∼30 mA/cm². The FE decreases significantly at higher cell potentials and current densities, and lower pressures. Up to 2 wt % formate was produced at a cell potential of 4 V, a CD of ∼100 mA/cm², and a FE of 65%. The advantages and disadvantages of using BPMs and CEMs in electrochemical cells for CO₂ conversion to formic acid/formate are discussed.