Promoting effect of Fe in preferential oxidation of carbon monoxide reaction (PROX) on Au/CeO2

Abstract

Ce–Fe mixed oxides were prepared by impregnation (IM) method and co-precipitation method (CP). Gold supported on Ce–Fe mixed oxides prepared by direct anionic exchange (DAE) was used as catalyst for preferential oxidation of carbon monoxide (PROX). The influence of the atomic ratio Ce/Fe and of the preparation method (CP or IM) was investigated. It was found that gold supported on modified ceria by iron displayed better catalytic performances. However, the selectivity of Au/CeFe-CP was lower than that of Au/CeO2 catalyst, which could be ascribed to the formation of defects in CeFe support prone to accumulate carbonate species on the surface. The characterization by means of XRD, XPS, H2-TPR and HRTEM indicated that the doping of iron in ceria prepared by CP promoted the formation of a Ce–Fe solid solution, decreased the particle size of ceria and enhanced the dispersion of gold. In the case of the IM catalysts, iron is segregated in the form of Fe2O3, which impedes the activity in PROX. The strong interaction between CeO2 and Fe2O3 supports led to higher oxygen mobility and to the formation of Au3+, which may also contribute to the higher catalytic activity of Au/Ce85Fe15.