Enhanced ethanol synthesis from CO2 hydrogenation over Fe and Na co-modified Rh/CeO2 catalysts

Abstract

Rh catalyst is investigated as a strong candidate for CO2 hydrogenation to ethanol, but it is still challenging because of the poor conversion efficiency. Here, by screening the promotors systematically and varying the amounts of components simultaneously, the optimized catalyst of 2Rh0.5Fe0.5Na/CeO2 was found to highly efficient catalytic CO2 hydrogenation to ethanol, giving a high ethanol selectivity of 29.8 % with a superior CO2 conversion of 13.0 % at 250 °C, 3 MPa, and the ethanol productivity reached 116.7 mmol·gRh−1·h−1. Characterization results revealed that the modification of Fe and Na, can promote the dispersion of Rh and the formation of Rh+ species, enhancing the capacities of CO2 adsorption and dissociation. In situ DRIFT experiment illuminated that the Rh active sites synergized with Fe and Na can stabilize the adsorbed species of m-CO32− and CO3H−, and promote the generation of HCOO* and CO* intermediates, which can be provided to couple with the CHx species, resulting in the high efficacy for ethanol synthesis from CO2 hydrogenation.