SOLID-STATE REACTION AS A WAY TO TRANSITION-METAL CATION INTRODUCTION INTO HIGH-SILICA ZEOLITES

A detailed review is given of transition metal cation incorporation into zeolites by a solid-state reaction. The procedures and techniques suitable for investigation of solid-state ion exchange in zeolites are described. It is shown that a solid-state reaction is a promising way for introduction of one or several transition metal ions into cationic positions of high-silica zeolites. The majority of these polyvalent cations cannot be introduced into these matrices by other methods. The influence of different factors (temperature and atmosphere of calcination, Al3+ Content in zeolitic lattice, presence of either co-cations or anionic species) on cationic species stabilization is analyzed. It is shown that pentasil-based systems with discrete types of isolated transition metal cations are unique objects for studying the relationship between catalytic properties and local topography of isolated redox sites. A solid state modification of pentasils permits the preparation of active and stable catalysts both for complete oxidation of alkanes and for NO(x) decomposition.