PPh3 enhanced catalytic conversion of CO2 to ethanol over a Ru-Co catalyst.

CO2 is a major greenhouse gas as well as an abundant, cheap, and renewable carbon resource. Synthesis of ethanol from CO2 using a homogeneous catalyst represents a promising protocol for CO2 utilization, yet achieving high catalytic performance with a cost-effective catalyst remains a challenge. Herein, we report a highly efficient Ru-Co-PPh3 bimetallic catalyst for ethanol synthesis using CO2, methanol, and H2. The ethanol space time yield (STY) reached as high as 4.4 g L-1 h-1, with a turnover frequency (TOF) of 23.2 h-1 and an ethanol selectivity of 85.6 C-mol% in total products, outperforming the previous reports of homogeneous catalytic systems for conversion of CO2 to ethanol. The PPh3 ligand enabled the high-efficiency reaction by direct utilization of much cheaper Ru-Co precursors and with lower catalyst dosage. Notably, the PPh3 ligand played multiple roles in improving the activity, selectivity and stability of the catalyst. The reaction mechanism was also discussed based on a series of control experiments. This work provides a sustainable and practical way of ethanol synthesis using CO2 as a feedstock.