Overall mass balance evaluation of electrochemical reactors: The case of CO2 reduction

Abstract

The overall mass balance of an electrochemical reactor is a key factor in determining the economic potential of a process. We provide a method to estimate the overall mass balance and electrolyte composition of electrochemical conversion systems and apply it to several CO2 conversion systems. Next to the reactions at the electrodes, the influence of transport across the membrane and homogeneous reactions are considered. It is thereby shown that potassium bicarbonate – an often proposed electrolyte for aqueous CO2 reduction - does not provide the conditions required for CO2 conversion to formic acid. The requirements for an electrolyte that does result in that conversion are described. The simplicity and versatility of the simplified method and the necessity of establishing a complete mass balance make the method a valuable addition to the electrochemist’s toolbox.