Molecular sieves are crystalline materials with open framework structures. Of the almost two billion pounds of molecular sieves produced in 1990, 1.4 billion pounds were used in detergents, 160 million pounds as catalysts, and about 70 million pounds as adsorbents or desiccants [1]. Zeolites, composed of aluminosilicates, represent a large fraction of known molecular sieves. The primary building blocks of zeolites are [SiO4 ]4 and [A1O4]5 tetrahedra which are linked by their corners to form channels and cages or cavities of discrete size The pore openings to these channels and cages generally range from about 3 to 20 A. As a result of the difference in charge between the [SiO4 ]4 and [A1O4]5 tetrahedra, the total framework charge of an aluminum-containing molecular sieve is negative and hence must be balanced by cations, typically protons, alkali, or alkaline earth metal ions.