DIRECT DETERMINATION OF PROTON POSITIONS IN D-Y AND H-Y ZEOLITE SAMPLES BY NEUTRON POWDER DIFFRACTION

The high-resolution neutron powder diffraction study of D-Y containing water and completely dehydrated D-Y and H-Y is reported. The preferred proton positions near the framework oxygens O(1) and O(3) are confirmed. The highest occupation of protons in Na3H53Al56Si136O384, however, was found near O(1). The site occupations followed the order O(1) > O(3) > O(2). No protons were located near O(4) in all three samples. The geometry of the T-OH-T hydroxyl bridge is in good agreement with those derived from NMR data. H2O in D-Y leads to a displacement of the deuterium near O(3) in the direction of the H2O molecule located in the sodalite cage. The formation of hydroxonium ions is suggested.