Iron-ceria-zirconia fluorite catalysts for methane selective oxidation to formaldehyde

Ceria-zirconia catalysts modified by partial substitution of zirconium by iron were investigated for the reaction of the selective oxidation of methane to formaldehyde. The insertion of iron was ensured by the preparation method, based on decomposition of the mixed precursors. The crystalline structure was studied by XRD and the iron state was determined by Mossbauer spectroscopy. The insertion of Fe3+ into the lattice of the mixed oxide and the partial substitution of zirconium ions with iron cations up to 25% have not resulted in any phase rejection of the formed iron oxide. The reducibility of Ce4+ in the modified ternary oxide is enhanced by doping with iron. Despite their low specific surface area, the catalysts are efficient at activating the methane independently of the iron content. The selectivity to formaldehyde strongly depends on the amount of the iron inserted in the mixed oxide. (c) 2009 Elsevier B.V. All rights reserved.