Synthesis of superficially modified Ce1−x(Zr + Y)xO2−δ solid solutions and thermogravimetric analysis of their performance in the catalytic soot combustion

Abstract

In this work, solid solutions of general formula Ce _1−x (Zr + Y)xO _2− _δ were chemically synthesized through the so-called citrate-EDTA complexing method, wherein the doping cations Zr and Y were substituted in the ceria lattice with an equimolar amount of 0.05 ≤ x ≤ = 0.25. The ternary oxides were heat-treated, and those that showed the best textural properties were superficially impregnated with Fe _2 O _3 particles by the thermal decomposition method using a metalorganic precursor. The X-ray diffraction results suggest that co-doping with Zr ^4+ and Y ^3+ promotes a slight distortion of the CeO _2 cubic cell. Nevertheless, the fluorite cubic structure of the oxides remains stable after being exposed to heat treatments. Furthermore, using scanning electron microscopy and Raman techniques, the presence of deposited Fe _2 O _3 and the formation of extrinsic vacancies in the materials could be corroborated. Finally, the oxides’ catalytic evaluation in the soot oxidation reaction was carried out using the thermogravimetry technique. The ternary oxide with cerium molar content equal to 0.9 and impregnated with Fe _2 O _3 presented excellent catalytic behavior for soot oxidation. T _10 , T _50 , and T _90 temperatures were 310, 383, and 416 °C, respectively.

Keywords

• CeO2
• citrate-EDTA complexing method
• co-doping
• catalytic soot combustion
• Fe2O3