Zero-crossover electrochemical CO2 reduction to ethylene with co-production of valuable chemicals

Abstract

To date, electrochemical reduction of CO2 (eCO2R) is plagued by undesirable carbonate formation and crossover that adds an energy penalty. Using a bipolar membrane, copper cathode, and gold nano-dendrite (Au-ND) anode, we report eCO2R to C2H4 on cathode coupled with glycerol oxidation on anode with zero carbonate crossover. The co-electrolysis system operated at high current densities of 175–225 mA/cm2 and C2H4 faradaic efficiency (FE) of 50%. The full cell voltages were between 3.9 and 4.4 V, which represented a decrease of 0.8 V versus conventional eCO2R. In addition, the Au-ND catalyst demonstrated high FE of 50% for glycolic acid (GA) production, which helped drive economic feasibility of the process. Our techno-economic analysis indicated that, while it would be improbable to commercialize a conventional eCO2R-to-C2H4 process, a co-electrolysis process to produce C2H4 from CO2 and GA from crude glycerol, with zero carbonate crossover, can attain a competitive minimum selling price (MSP) of C2H4 ∼$1.1/kgC2H4.