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

It is of interest to extend the reach of CO 2 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 C 4 H 10 selectively at ambient conditions. In a C 2 H 4 dimerization reactor, we directly upgrade the gas outlet stream of the CO 2 or CO electrolyser without purification. We find that CO, which is present alongside C 2 H 4 , enhances C 2 H 4 dimerization selectivity to give C 4 H 10 to 95%, a much higher performance than when a CO 2 electrolyser is used instead. We achieve an overall two-stage CO-to-C 4 H 10 cascade selectivity of 43%. Mechanistic investigations, complemented by density functional theory calculations reveal that increased CO coverage favours C 2 H 4 dimerization and hydrogenation of *C x H y adsorbates, as well as destabilizes the *C 4 H 9 intermediate, and so promotes the selective production of the target alkane.