PREPARATION OF COBALT OXIDE FINE PARTICLES FROM VARIOUS AQUEOUS-SOLUTIONS BY SPRAY-PYROLYSIS

Cobalt oxide (CoO) fine particles were prepared by spray-pyrolysis from four aqueous solutions of different cobalt salts : CoSO4 ·7H2O, Co(NH4)2 (SO4)2·6H2O, Co (CH3COO)2·4H2O and Co(NO3)2.6H2O. It was found that CoO fine particles with a diameter smaller than 1.0μm could be made from all of the cobalt salt solutions studied under the present experimental conditions (concentration range : 0.05~1.0kmol·m-3, decomposition temperature : 1133.2K ; and residence time : 1.5~3.0s). The CoO particles produced were different in shape and had different particle size distributions. Spherical fine particles with porous structure were prepared from CoSO4·7H2O and Co(NH4)2(SO4)2·6H2O solutions. Hollow spherical fine particles were obtained from Co(NO3)2·6H2O. The fine particles from Co (CH3 COO)2·4H2O solution were composed of chain-like agglomerates of ultrafine particles below 0.1 μm in diameter. It was concluded that formation mechanisms of CoO fine particles differ according to the feed cobalt salt solution. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.