engleski

High surface area ceria nanoparticles via hydrothermal synthesis experiment design

Hydrothermal synthesis of CeO2 was optimized on two reactant concentrations and synthesis temperature and duration, in order to achieve material having the greatest specific surface area (SSA). Taguchi method of experimental design was employed in evaluation of the relative importance of synthesis parameters. CeO2 nanoparticles were characterized using X- ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. Optimum conditions for obtaining particles with greater SSA were calculated according to Taguchi’s model “the-higher-the-better.” Synthesis temperature was found to be the only parameter significant for enabling nanoparticleswith greater SSA.Mesoporous nanocrystalline ceria with SSA as great as 226m2 g−1 was achieved, which is unprecedented for the hydrothermally synthesized ceria. The reason for this achievement was found in temperature dependence of the diffusion coefficient which, when low, favors nucleation yielding with fine particles, while when high it favors crystal growth and formation of one- dimensional structures.The occurrence of 1D- structure in sample exhibiting the smallest SSA was confirmed. Very fine crystallites with crystallite size as low as 5.9nm have been obtained being roughly inverse proportional to SSA. Selected samples were tested as catalyst for soot oxidation. Catalyst morphology turned out to be decisive factor for catalytic activity.

hydrothermal synthesis ; Taguchi method of experimental design ; nanoparticles ; specific surface area

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