A highly selective catalyst of Co/La4Ga2O9 for CO2 hydrogenation to ethanol

A new catalyst of Co/La4Ga2O9 for CO2 hydrogenation to produce ethanol was prepared by reducing LaCo0.5Ga0.5O3, which showed excellent selectivity to ethanol (≈35C-mol%) at mild reaction conditions (270 °C, 3.5 MPa, 3000 mL g−1 h−1). The catalysts were characterized by N2 adsorption/desorption, XRD, XAFS, CO and CO2-TPD, H2 chemisorption, XPS and TEM techniques. The interaction between Co nanoparticles (NPs) and La4Ga2O9 oxide resulted in Co0-Co2+ on the surface of Co NPs. It was proposed that La4Ga2O9 could catalyze reverse water gas shift reaction (r-WGS), which converted CO2 to CO. Then, the CO migrated to Co0-Co2+ on Co NPs, where it was hydrogenated to form ethanol like higher alcohols synthesis from syngas. The results suggest that by controlling the oxidation state of cobalt, and combined with a kind of active site for activating CO2 to form CO, a catalyst with excellent selectivity to ethanol could be obtained for CO2 hydrogenation, which means that the complex reaction may be proceed with high selectivity using only one active metal component.