The use of clays as sorbents and catalysts

摘要

This paper attempts to show how the structural, physical and chemical properties of clay minerals relate to their laboratory, industrial and environmental uses as sorbents and catalysts. A brief review of the formulae, structures of clays and their relationship to their chemical and physical properties is given. Isonorphous substitution of layer cations generates layer charges, which are neturalised by the presence of exchangeable, compensating ions in the interlayer. Acid activation increases clay surface areas, acidity and sorption characteristics producing large volumes of acidic aluminium salt waste. Cationic clays often have high Brnsted and Lewis acidity, which enable the clays to be used as clean, often highly specific catalysts in organic and inorganic reactions or as supports for catalysts or reagents.