GROWTH OF POUROUS AGGREGATES DURING TEMPLATE DIRECTED SAPO34 ZEOLITE SYNTHESIS

The formation of nanoparticles of zeolite Sapo-34 grown on a amine terminated polyamidoamine (PAMAM) dendrimer has been investigated by means of the small angle xray scattering (SAXS) technique performed at the SAXS Beamline at the Elettra Synchrotron Radiation Facility. Sapo-34 zeolites, in general, are obtained by a hydrothermal synthesis in presence of a tetraethylammonium hydroxide (TEAOH) template which acts as a structuredirecting agent and which is responsible for the final porosity. Among the templates of SAPO-34, in fact, TEAOH has become well-known as it gives rise to good catalytic properties for various reactions. More specifically we observe that the addition of a dendrimer template, in place of the traditional tetraethylammonium hydroxide (TEAOH) template, to the synthesis environment modified the crystallites aggregation with a strong influence on the long-range assembly conditions for the zeolite growth. In order to obtain direct information of the morphological features of the generated aggregates during nanoparticles formation the SAXS measurements have been performed 10 minutes after the mixing of the main reactants in the presence of the water solution of generation G4 PAMAM dendrimers [1] at the concentration of c=4 wt%.