Metal-exchanged zeolites as catalysts

Zeolites can serve as a host to activate metal ions. In this mode they can provide a unique ligand system which provides multiple types for coordination of the cation, thus providing active sites for catalyzing a variety of reactions. It is clear that cation-exchanged zeolites offer unique and high catalytic activity for a wide variety of important reactions. Over the past few years, we have studied a number of seemingly unrelated reactions which all share the result that the exchange of a transition metal cation into the zeolite offers high activity, always beyond the activity of a traditional oxide support. Examples of this phenomena will be illustrated with six very different reactions. (C) 1998 Elsevier Science B.V. All rights reserved.