Improvement of oxygen storage capacity using mesoporous ceria-zirconia solid solutions

Mesoporous phases of ceria (CeO2) and ceria-zirconia solid solutions up to 50% of Zr have been synthesized using hard template method. The structures of the obtained metal oxides replicas correspond to the chosen structures of the KIT-6 and SBA-15 silica. This method allows obtaining materials with a uniform and homogenous porous size distribution as replica of the used nanotemplate. This structure facilitates the interaction with the gas molecules, their diffusivity inside the material and the porous size control. Obtained replicas were analysed using a variety of characterization techniques. TEM results reveal successful formation of the expected structures which were also supported by BET measurements. Replicas obtained applying SBA-15 and KIT-6 nanotemplates present similar behaviour although KIT-6 shows a slightly higher (about 5%) active surface with values in the range of 125 m(2)/g after thermal annealing. XRD and Raman spectra confirm formation of solid solutions with cubic structure up to 20% of zirconium above which, formation of tetragonal phase was observed. Functionally, besides their high active surface, these ceria-zirconia solid solutions show significant improvement in their oxygen storage capacity (OSC). In comparison with pure mesoporous ceria, it has been found that due to the introduction of zirconium even for a few percentage of zirconium (5%) the OSC increases (more than 30 times) which is attributed to the presence of substitutional zirconium in the ceria lattice. (C) 2011 Elsevier B.V. All rights reserved.