(622h) Tandem Reactors and Reactions for CO2 Conversion

Carbon dioxide (CO₂) valorization is a promising pathway for mitigating greenhouse gas emissions from the chemical sector and reducing the reliance of chemical manufacturing on fossil fuel feedstocks. The electrochemical CO₂reduction reaction (CO₂RR) has been widely studied in recent years as one such promising strategy for reducing atmospheric CO₂ concentration via both decarbonization and CO₂ utilization, but real-world implementation of electrochemical CO₂RR is limited by low selectivities for valuable multicarbon products. Many well-established thermochemical processes, however, use simple CO₂RR products (e.g. C₂H₄ CO, and H₂) as reactants. By coupling an initial electrocatalytic reaction with a downstream thermocatalytic reaction, it is possible to achieve high selectivities for the desired products at commercially relevant production rates. Optimizing electrochemical CO₂RR in the context of this tandem system, rather pursuing high single-single pass selectivities, will accelerate the deployment of electrochemical CO₂RR. Furthermore, this tandem approach can be applied to produce molecules that are more complex than can be produced via direct electrochemical CO₂RR. This work discusses tandem catalytic paradigms for sustainable CO₂ conversion that have potential advantages over processes using single-functional catalysts, with a focus on tandem electrocatalytic-thermocatalytic processes. We will use several recent examples of tandem electrochemical-thermochemical (EC-TC) reactor systems from our group to illustrate the advantages of these tandem processes for CO₂ conversion. We also provide guidance on criteria for choosing between the single reactor configuration with a multifunctional catalyst and tandem reactors with multiple catalysts, as well as a brief overview of opportunities for tandem catalytic processes for CO₂ conversion that leverage biocatalysis, photocatalysis, and plasma-assisted catalysis.