Recent advances in the synthesis and catalytic applications of pillared clays

New methods have been developed in recent years that are now being successf ully applied in the preparation of pillared interlayered clays (PILCs). Var iations in the procedures concern different parameters involved in the synt hesis, such as the starting clay, the intercalating solution, the intercala tion process, and the drying and calcination steps of the pillared solids, among others. In the present article, the latest results obtained when intr oducing modifications in the chemical aspects of PILC synthesis are reviewe d. These include (1) pillaring with mixed solutions containing two or more cations, (2) using coordination or organometallic compounds, (3) using poly mers and surfactants, (4) pillaring of acid-activated clays, and (5) enhanc ement of PILC acidity. A separate section is devoted to the specific featur es of preparing these solids in amounts large enough to make their manufact ure on an industrial scale economically feasible. Recent developments in th e catalytic applications of PILCs are also reviewed, with emphasis on the p rogressively more extended use of these materials as catalytic supports.