Introduction of Cations into Zeolites by Solid-State Reaction

Abstract

A brief review is given of early observations of cation incorporation into zeolites through solid-state reaction. The general procedure and techniques suitable for investigation of solid-state ion exchange in zeolites are described. Results of systematic studies on introduction of alkaline, alkaline earth, rare earth, transition metal and noble metal cations into hydrogen, ammonium and sodium forms of zeolites are reported. In these studies, halides or oxides of the in-going cations are preferentially employed. Particular attention is paid to the stoichiometry of the solid-state ion exchange. It is shown that in several cases a one-step solid-state reaction leads to a 100% cation incorporation, whereas such a high degree of exchange is difficult to obtain by conventional methods. As is illustrated by a few selected examples, solid-state ion exchange might be an interesting way to prepare active acid and bifunctional catalysts.