Tandem Electrocatalytic-Thermocatalytic Reaction Scheme for CO2 Conversion to C-3 Oxygenates

A two-step tandem electrochemical-thermochemical re-action scheme is demonstrated to convert CO2 into value-added C-3 oxygenate molecules: CO2 was electrochemically reduced to ethylene, CO, and H-2, followed by the thermochemical hydroformylation reaction to produce 1-propanol and propanal. The CO2 electrolyzer 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 Rh1Co(3)/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 C3 oxygenate product selectivity (on a basis of reduced CO2) of similar to 18%, representing over a 4-fold improvement compared to direct electrochemical CO2 conversion to 1-propanol in flow cells. Additionally, the CO2 electrolyzer was scaled to a 25 cm(2) device to enhance the C3 oxygenate production rate up to 11.8 mu mol min(-1) and demonstrate potential scalability of the tandem system.