Gold/Iron oxide supported catalysts for environmental applications

A novel preparation method was developed for the preparation of gold/iron supported catalysts on TiO2 and CeO2 by employing bi-metallic carbonyl cluster salts. All prepared catalysts were fully characterized and tested in toluene and methanol total oxidation and in PROX reaction. The novel preparation method resulted in small gold metallic nanoparticles surrounded by highly dispersed amorphous iron oxide species on the supports. Results confirmed that FeOx species stabilize small Au particles. Partial encapsulation of gold atoms by iron species was also observed together with a strong interaction between gold and oxide species (both iron oxide and reducible supports). The presence of gold has been found to enhance the activity of iron oxide towards both the complete oxidation of toluene and methanol to CO2 and the PROX reaction. The extent of this positive effect resulted to be dependent on the adsorption properties of the organic molecule (toluene vs methanol), the support used and the interaction degree between FeOx and Au species. Moreover, CO preferential oxidation was found to strongly depend on Au particle size and surface oxygen reducibility, being related to the different oxide species which can be formed using different thermal treatment conditions or iron loadings over the support. The use of carbonyl clusters to synthesize bimetallic catalysts is a promising way to obtain iron stabilized gold nanoparticles and could find application even on support on which stabilization of gold is usually very difficult. In this way catalysts with highly dispersed active phase and an enhanced catalytic activity were obtained.