La-Ce-O modified Rh-LaFeO3 on SiO2 for direct ethanol synthesis from syngas

Abstract A new catalyst for direct ethanol synthesis (DES) from syngas composed of Rh nanoparticles (NPs) highly dispersed on La-Ce-O modified LaFeO3 which was loaded on SiO2 support was studied in this work. Over the best catalyst 40.6% of the reacted CO could be directly converted into ethanol with CO conversion of 14.2% at 250 °C, 3 MPa and GHSV of 3900 mL (gcat h)-1. The results indicated that adding cerium into LaFe0.5Rh0.5O3/SiO2 resulted in La1-xCexFe0.5Rh0.5O3/SiO2, the incorporation of Ce effectively regulated the interface electronic states of Rh NPs. The well matched catalyzing process by the active sites of Rh0, Rh+(or Rhδ+) and the oxygen vacancies on the surface of LaFeO3, of those, Rh0 dissociatively adsorbed CO and the latter two associatively adsorbed CO could effectively improve the activity and selectivity for DES. Moreover, the interaction of La-Ce-O and LaFeO3 strengthened the CO adsorption on the oxygen vacancies on LaFeO3, which improved the capacity of assistance in activating CO associatively, thus further increasing the selectivity to ethanol. The catalyst exhibited excellent resistance to carbon deposition and sintering, attributing to the small size of Rh NPs and the carbon eliminating effect of La2O3 and oxygen vacancies on the surface of LaFeO3.