Ethanol synthesis by catalytic hydrogenation of CO2 over Rh---Fe/SiO2 catalysts

Ethanol synthesis by catalytic hydrogenation of CO2 was carried out over Rh---Fe/SiO2 catalysts prepared by coimpregnation. The added amount of Fe influenced ethanol selectivity as well as CO2 conversion in the range Fe/Rh = 0–3. Product selectivity was correlated with %Fe0 evaluated by XPS. The ethanol selectivity was correlated with the amount of bridged-CO adsorbed species evaluated by in situ FT-IR. It has been suggested that Fe changed the electronic states of Rh and that Fe0 promoted methanation and prevented ethanol formation, as well as CO and methanol formation. An ethanol selectivity of 16.0% and a CO2 conversion of 26.7% were obtained at 5 MPa and 533 K in a flow of H2---CO2 premixed gas (H2/CO2 = 3) with a flow rate of 100 cm3/min over 5 wt% Rh---Fe(1 : 2)/SiO2 catalysts.