APPLICATION OF COMPUTER MODELING TO THE MECHANISMS OF SYNTHESIS OF MICROPOROUS CATALYTIC MATERIALS

We present results of a study of species present during the hydrotherm al synthesis of zeotype materials. We have studied the interactions of typical silica fragments, which condense to form the framework struct ure, with both solvent (water) and the organic molecules used as struc ture-directing agents. The hydrophobic nature of the fragments results in the collapse of the fragment structure on solvation, resulting in geometries far removed from their configuration in the crystalline mat erial. The presence of the organic template provides stabilisation for the hydrated fragments, effectively shielding them from the water and allowing them to maintain their open structure. The impact of these r esults on possible mechanisms of crystallisation is discussed.