Highly effective synthesis of ethanol by CO2-hydrogenation on well balanced multi-functional FT-type composite catalysts Original Research Article

Novel composite catalysts for selective synthesis of ethanol by hydrogenation of carbon dioxide have been developed. The three different kinds of elementary reaction functions for ethanol synthesis were undertaken. These catalytic functions were partial-reduction of CO2 to CO, C–C bond formation, and –OH group formation. Furthermore, in order to stabilize the optimum reductive state of the catalyst during reaction under a high conversion or a high reaction rate condition, both hydrogen spillover and inverse spillover functions were combined with the above-mentioned composite catalysts. Based on the properties of the elemental catalysts to be combined, their adopting ratios and configurations were most appropriately chosen. As a result, ethanol could be synthesized by exceeding the value, which was expected from the Schultz–Flory (SF) probability law for the distribution of alcohols having different carbon numbers. The highest STY of ethanol amounted to 874 or 476 g l−1 h−1 under the conditions of CO2 conversion of 31.1% or 54.5%, respectively, applying different catalyst combinations and reaction conditions.