The effect of flue gas contaminants on electrochemical reduction of CO2 to methyl formate in a dual methanol/water electrolysis system

CO2 electroreduction to value-added products has promise as a scalable technique for mitigating climate change, but CO2 purification requirements raise the overall process cost. Here, direct reduction of flue gas is thus an attractive approach, but the sensitivity of the catalyst activity to flue gas contaminants and increased hydrogen evolution with diluted CO2 have been major challenges. Herein, flue gas electroreduction in a methyl formate synthesis route has been investigated on a Pb-catalyzed electrode in acidic methanol catholyte with an aqueous anolyte for promotion of a sustainable water oxidation half-reaction. Contaminant concentrations of 50 ppm SO2 and NO each had a minimal effect on the product faradaic efficiencies, while 4% O2 led to a notable improvement in partial current density for methyl formate attributed to the improved durability of the catalyst surface oxide. Decreased CO2 concentration showed a corresponding decline in current density attributed to CO2 mass transfer limitations.