Now, a team led by Jingguang Chen and Feng Jiao reports a tandem approach to boost the formation of C3 oxygenates by connecting an electrochemical reactor and a thermochemical reactor, where the gaseous products from the former feed the latter. First, the researchers optimize both reactions separately, using two different copper catalysts — which are known for their selectivity to C2+ products — and a modification to the gas diffusion layer for the electrochemical reaction, to increase the ratio of ethylene in the gaseous product mixture, and various feed ratios and temperatures on a Rh1Co3/MCM-41 catalyst for the subsequent hydroformylation thermochemical process. Moreover, the state of each of these catalysts under reaction conditions is assessed by in situ X-ray absorption spectroscopy.
The tandem strategy is first conducted using a 5 cm2 membrane electrode assembly (MEA) electrolyser operating at a current density of 220 mA cm–2 and a flow rate of 10 sccm. When an oxide-derived Cu/C electrocatalyst is combined with the hydroformylation reactor at 160 °C, 18.4% of C3 oxygenate products is obtained — 16.2% being 1-propanol — whereas using a Cu/reinforced C cathode and the hydroformylation operating at 200 °C results in a similar combined selectivity of 18.0%. With a 25 cm2 MEA electrolyser and decreasing the current density to 195 mA cm–2 while increasing the CO2 flow rate to 40 sccm, steady-state production rates of C3 oxygenates of 9.3 and 11.8 μmol min−1 are obtained, respectively, with the setup and conditions detailed before.
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