Tandem Electrocatalytic-Thermocatalytic Reaction Scheme for CO₂Conversion to C₃Oxygenates

A two-step tandem electrochemical-thermochemical reaction scheme is demonstrated to convert CO₂into value-added C₃oxygenate molecules: CO₂was electrochemically reduced to ethylene, CO, and H₂, followed by the thermochemical hydroformylation reaction to produce 1-propanol and propanal. The CO₂electrolyzer was evaluated with Cu catalysts containing different oxidation states and with modifications to the gas diffusion layer hydrophobicity, while the hydroformylation reactor was tested over a Rh₁Co₃/MCM-41 catalyst. In situ X-ray absorption spectroscopy showed minimal changes to the Cu and Rh catalysts in the electrochemical and thermochemical reactions, respectively. The tandem configuration achieved a total C₃oxygenate product selectivity (on a basis of reduced CO₂) of ∼18%, representing over a 4-fold improvement compared to direct electrochemical CO₂conversion to 1-propanol in flow cells. Additionally, the CO₂electrolyzer was scaled to a 25 cm²device to enhance the C₃oxygenate production rate up to 11.8 μmol min^-1and demonstrate potential scalability of the tandem system.