PREPARATION AND CATALYTIC PROPERTIES OF CATIONIC AND ANIONIC CLAYS

The structure, main properties and preparation methods of cationic and anionic clays are reviewed in Light of the versatility and potential of these materials. Recently reported catalytic applications in some f ields of high industrial and scientific relevance (organic or fine che mistry, environmental catalysis, etc.) are also summarized. Clays exhi bit many profitable features (such as low cost, wide range of preparat ion variables, use in catalytic amounts, ease of set-up and work-up, g ain in yield and/or selectivity, etc.) which may be useful tools in th e move towards establishing environmentally friendly technologies. Fur thermore, the preparation and properties of pillared layer cationic or anionic clays are also discussed, considering that the upgrading of t hese materials by the pillaring process opens new and interesting pers pectives, on account also of possible shape selective effects. (C) 199 8 Elsevier Science B.V. All rights reserved.