Catalytic properties of nanocomposites based on cobalt ferrites dispersed in sol-gel silica

In this work, composites based on cobalt ferrite (CoFe2O4) dispersed in a porous silica matrix have been prepared via sol-gel method using tetraethylorthosilicate (TEOS) as a silica precursor, and iron and cobalt nitrates as precursors. In this process, Co and Fe ions dispersed in a sol-gel matrix reacted upon thermal treatment to form Co-Fe crystallites with nanometric dimensions. The structural, morphological, and textural changes of the composites treated at various temperatures were studied by X-ray diffraction, electronic microprobe, and gas adsorption. The treated composites had surface areas in the range 263-359 m(2) g(-1) with mesopore contribution. These materials were active as catalysts in the total oxidation of chlorobenzene in air. The most active catalyst was the composite treated at 500degreesC, which was stable at a temperature as high as 600degreesC for 72h. (C) 2004 Elsevier B.V. All rights reserved.