Cobalt–Nickel Catalysts for Selective Hydrogenation of Carbon Dioxide into Ethanol

Abstract

Selective hydrogenation of CO 2 into valuable ethanol proceeds by the coupling of appropriate C 1 intermediates to form C 2 -oxygenates. Matching the different C 1 intermediates is crucial for this process but is difficult to control. We found that incorporation of nickel species into the cobalt catalyst could boost the formation of relatively stable *CH x intermediate from CO 2 hydrogenation, which significantly avoids an occurrence of methanation. The *CH x species subsequently insert into the *HCOO, another intermediate that is easily formed, to produce C 2 -oxygenates. Following this pathway, the optimized catalyst, Co 0.52 Ni 0.48 AlO x, gives the ethanol yield at 15.8 mmol g cat –1 with selectivity at 85.7% in the CO 2 hydrogenation at 200 °C for 12 h, which even outperforms those of noble metal catalysts.