Selective synthesis of butane from carbon monoxide using cascade electrolysis and thermocatalysis at ambient conditions

It is of interest to extend the reach of CO2 and CO electrochemistry to the synthesis of products with molecular weights higher than the C-1 and C-2 seen in most prior reports carried out near ambient conditions. Here we present a cascade C-1-C-2-C-4 system that combines electrochemical and thermochemical reactors to produce C4H10 selectively at ambient conditions. In a C2H4 dimerization reactor, we directly upgrade the gas outlet stream of the CO2 or CO electrolyser without purification. We find that CO, which is present alongside C2H4, enhances C2H4 dimerization selectivity to give C4H10 to 95%, a much higher performance than when a CO2 electrolyser is used instead. We achieve an overall two-stage CO-to-C4H10 cascade selectivity of 43%. Mechanistic investigations, complemented by density functional theory calculations reveal that increased CO coverage favours C2H4 dimerization and hydrogenation of *CxHy adsorbates, as well as destabilizes the *C4H9 intermediate, and so promotes the selective production of the target alkane.

Automated summary

We present a cascade C-1-C-2-C-4 system that combines electrochemical and thermochemical reactors to selectively produce C4H10 from CO2 or CO gas at ambient conditions. The use of a C2H4 dimerization reactor directly upgrades the gas outlet stream and significantly enhances the selectivity for C4H10 production.