Surface evolution of the Sn–Ce–O powders in various atmospheres

Abstract

Tin and cerium based oxide ceramics, due to their peculiar properties, are good candidates for using as sensors, solid electrolytes in fuel cells, and catalysts. In the present work, Sn-Ce-O powders with the composition of interest for catalysis applications were obtained by solid state reactions and by thermal decomposition of the different tin and cerium precursors. The structural characterization of the resulted samples was performed by X-ray diffraction. Morphological characteristics were evaluated from X-ray microstructural parameters and BET surface areas measurements. Surface evolution of the studied powders was investigated by electrical measurements in various atmospheres in the 25-400°C temperature range. The samples studied behave as a n-type semiconductor. The catalytic activity for CO oxidation was measured in gas flow between 25 and 400°C. The conversion degree depends on the preparation method of the samples. Magnetic susceptibility measurements at room temperature of the samples before and after catalytic test indicated a paramagnetic behavior. Higher values of magnetic susceptibility of the samples after catalytic test compared to initial ones could indicate the influence of CeO 2 on the catalytic activity.

Effects of Zr Addition on CO and CH₄ Catalytic Oxidation over PdO/PdO/Ce_1-<i>x</i>Pd_<i>x</i>O_2-<i>δ</i> Catalyst

“…Doping of ceria with different cations, such as Fe, Co, Ni, Cu, Zr, La, Pd, Pt, Pr, Y, Gd, Sn 9 -14 , could improve the oxygen storage-release capacity (OSC) or the redox properties and thus enhancing the catalytic activities of ceria. The enhanced OSC of ceria can be attributed to the substitution of isovalent and aliovalant metal ion in CeO2, in the form of solid solutions Ce1-xCuxO2 15 , Ce1-xPdxO2 and Ce1-xPtxO2 16 , Ce1-xZrxO2 17 , Ce1-xSnxO2 18 , Ce1-xYxO2 19 . It is generally accepted that oxygen storage capacity is related to the oxygen vacancy formation on reduced CeO2 20 .…”