Tuning the interaction between Na and Co2C to promote selective CO2 hydrogenation to ethanol

Abstract Direct CO2 hydrogenation to ethanol is one of the promising alternatives to realize “carbon-neutral” protocol. However, stabilizing catalyst structure and modulating CO activation remain challenging. Herein, we obtained stable Na-Co2C active sites by tuning the interaction between Na and Co species. Enhancing the interaction of Na with Co2C through forming Na-Co bond induced the dispersion of Co2C and the reduction of particle size, evidently improving RWGS reaction rate and ethanol space time yield (STY). In situ adsorption experiments and density functional theory (DFT) calculations demonstrated that the amount of CO2 and CO adsorption was increased with the increase of the interaction, while CO dissociative activation on Na-Co2C (111) surface was inhibited, thereby regulating the surface CO/CHx ratio and facilitating subsequent CO coupling to synthesize ethanol. Excessive interaction weakened the strength of CO adsorption resulting in higher CO selectivity. The moderate interaction was obtained at 2 wt% Na and the ethanol STY reached as high as 1.1 mmol g-1 h-1 (C2+OH/ROH fraction of 91.3%), which is 10 times higher than that without Na. This work brings an enabling strategy to tune reaction processes and design stable and efficient catalysts.