Synthesis and Characterization of Nano CexOy/Al2O3 Mixed Oxide by Sol-Gel Method

Reference	Presenter	Authors (Institution)	Abstract
06-133	Antonio José Nascimento Dias	Dias, A.J.(Instituto Nacional de Tecnologia); Nascimento, S.(Universidade do Estado do Rio de Janeiro); Caldeira, H.S.(Universidade do Estado do Rio de Janeiro);	Sol-gel method was applied to synthesize ultrafine particles using aqueous solutions of f aluminum isopropoxide and cerium(III) nitrate hexahydrate employing acetylacetone as a complexant agent varying the cerium precursor concentration. The prepared solution was stirred for 22 hours at 85°C, then the resultant gelled mass was lyophhilized and thermally treated at 980°C. The samples were characterized by different techiniques such as X-ray diffraction, Thermogravimetry analysis, Scanning electron microscopy and Energy-dispersive X-ray spectroscopy. From the X-Ray ditratograms of lyophilized gel was observed only boehmite (AlOOH) with crystallite size varying betwenn 2.9 and 3.4nm. Also was observed that the presence of acetylacetona had no influence over the boehmite crystallite size while the increase of cerium precursor concentration caused a lowering of boemmite crystallitr size. The presence of acetylacetona seems to inhibit the crystallization of CeO2. The presence of CeO2 only was observed after the thermal treatment. Thermogravimetry analysis showed an exothermic band from 600°C with peaks at 949°C due the dehydration of aluminum oxyhydroxides to alumina. The lyophilized soils show different shapes and agglomeration grades. From the Energy-dispersive X-ray spectroscopy was observed a homogeneous distribution of aluminum and cerium. The results show that is possible the obtention of a ultrafine nano CexOy/Al2O3 mixed oxide employing the studied synthesis method but the conditions employed have a strong influence over the morphology, crystallite size and the phase relation obtained.
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