SYNTHESIS OF MAGNESIUM-OXIDE BY THE SOL-GEL METHOD - EFFECT OF THE PH ON THE SURFACE HYDROXYLATION

Magnesium oxide was prepared by the sol-gel method. The method involves the hydrolysis of magnesium alkoxide in the presence of acid or basic catalysts followed by a polycondensation reaction. The synthesized solids were characterized by IR spectroscopy, X-ray diffraction, DTA, TGA, and electron microscopy. It is shown that the hydrolysis process depends on the catalyst's pH (HCl > CH3COOH > H2C2O4 > H2O > NH4OH). This effect can be explained by the reaction mechanism. The reaction is controlled by the hydrolysis at acid pH and by the polycondensation at a basic one. Solids prepared by this method are chemically homogeneous, very pure, and specifically hydroxylated. They can be widely used in the study of magnesium support effects in different catalytic reactions. © 1991.