Correlations between XPS binding energies and composition of aluminasilicate and phosphate molecular sieves

Silica alumina and silicoaluminophosphate-based molecular sieves were investigated by means of X-ray photoelectron spectroscopy. For all network elements, only one symmetrical peak of the binding energy was observed, indicating a very homogeneous distribution of the electron densities around the atoms throughout the lattice. Nevertheless, the strongest effects are related to the most nearest-neighbor environment. The binding energies of Si2p, O1s, and AI2p in silica alumina molecular sieves increased with increasing concentration of aluminum. Phosphorus decreases the binding energy of the oxygen without a large effect upon either aluminum or silicon. The implication of these observations for the polar properties of molecular sieve networks and their thermal stabilities are discussed.