Abstract
Fe/SiO2 and Rh-Fe/SiO2 catalysts with increasing Fe/Rh ratio have been prepared and characterized by TEM, XRD, oxygen adsorption and Mossbauer spectroscopy. It was confirmed that Fe/SiO2 catalysts cannot be reduced under hydrogen flow, to more than 50 % whatever the temperature in the 200-500 A degrees C range and shown that the presence of even a small amount of Rh (Fe/Rh a parts per thousand currency sign2,000) promoted the reduction of iron up to 85-95 %. This promoting effect also took place with a Fe/SiO2 + Rh/SiO2 physical mixture (Fe/Rh a parts per thousand currency sign2,000). Therefore, the occurrence of a hydrogen spillover effect may be involved in the observed process.