Artigo
Sol-gel entrapped cobalt complex
Fecha
2003-03-01Registro en:
Materials Characterization. New York: Elsevier B.V., v. 50, n. 2-3, p. 101-108, 2003.
1044-5803
10.1016/S1044-5803(03)00074-3
WOS:000186249900003
2998503841917815
6446047463034654
Autor
Univ Franca
Universidade Estadual Paulista (Unesp)
Resumen
This work describes optimized conditions for preparation of a cobalt complex entrapped in alumina amorphous materials in the form of powder. The hybrid materials, CoNHG, were obtained by a nonhydrolytic sol-gel route through condensation of aluminum chloride with diisopropylether in the presence of cobalt chloride. The materials were calcined at various temperatures. The presence of cobalt entrapped in the alumina matrix is confirmed by ultraviolet visible spectroscopy. The materials have been characterized by X-ray diffraction (XRD), surface area analysis, thermogravimetric analysis (TGA), differential thermal analyses (DTA) and transmission electron microscopy (TEM). The prepared alumina matrix materials are amorphous, even after heat treatment up to 750 degreesC. The XRD, TGA/DTA and TEM data support the increase of sample crystallization with increasing temperature. The specific surface area, pore size and pore diameter changed as a function of the heat treatment temperature employed. Different heat treatment temperatures result in materials with different compositions and structures, and influence their catalytic activity. The entrapped cobalt materials calcined at 750 degreesC efficiently catalyzed the epoxidation of (Z)-cyclooctene using iodozylbenzene as the oxygen donor. (C) 2003 Elsevier B.V. All rights reserved.