TOPOLOGY AND MAXIMUM CONTENT OF ISOLATED SPECIES (AL, GA, FE, B, SI, ...) IN A ZEOLITIC FRAMEWORK - AN APPROACH TO ACID CATALYSIS

The use of a topological density makes possible the calculation of the maximum concentration of isolated atoms A with no second A neighbors in a framework containing two types of atoms (Al in Si-Al zeolites for instance) or three types (Si in SAPO's for example). The structures with the lowest topological density can accept the highest level of atom A in the isolated form. The results are related to the maxima obtained in acidity and catalysis as a function of A atoms concentration.