Preparation of high surface area MgAl₂O₄ particles from colloidal solution using filter expansion aerosol generator

Magnesium aluminate particles with high surface area were directly prepared from colloidal solutions by spray pyrolysis using a filter expansion aerosol generator. The colloidal solution was prepared by hydrolysis of aluminum isopropoxide (AIP) and magnesium salts. The spinel particles began to form from 900°C. When prepared from colloidal solutions, the particles have porous and hollow morphology in contrast to particles prepared from aqueous solutions which have solid morphology. In the colloidal solution, the mean size of the spinel particles measured from the SEM photographs was increased from 0·42 to 0·95 μm when the overall solution concentration was increased from 0·075 to 0·1 mol l^-1. The specific surface areas of particles prepared from colloidal solutions were 264 and 259m² g^-1 when acetate and nitrate was used as magnesium source, respectively. On the other hand, particles prepared from aqueous solutions had low surface areas (18 and 23m² g^-1) when acetate and nitrate were used as magnesium source, respectively.