Location of Na+ and Cs+ cations in CsNaY zeolites studied by 23Na and 133Cs magic-angle spinning nuclear magnetic resonance spectroscopy combined with X-ray structure analysis by Rietveld refinement

Synthesis of Fully Dehydrated Partially Cs+-exchanged Zeolite Y (FAU, Si/Al = 1.56), |Cs45Na30|[Si117Al75O384]-FAU and Its Single-crystal Structure

“…However, the highest Cs + -exchanged level (60%) in the single-crystal structure of faujasite-type zeolite was achieved by the conventional aqueous solution method at room temperature (see Table 6). In addition, differences are found in the cation distributions between previously reported structures of fully dehydrated partially Cs + -exchanged zeolites 8,[10][11][12] and that of this work. With an increasing Si/Al ratio, the population of Na + ions at site I are decreased.…”

“…[10][11][12][14][15][16][17] In addition, they reported that the highest exchange level of Cs + ions per unit cell was about 70% in faujasite-type zeolites by the conventional aqueous solution method at room temperature. 13 Incomplete exchange with cesium may be the reason for the large cation size relative to zeolite aperture diameters.…”

“…Kim et al 10 and Bae 11 reported that fully dehydrated partially Cs + -exchanged zeolite X (Si/Al = 1.09) were determined by single-crystal X-ray diffraction techniques in the space group Fd 3 at 294 K. Kim et al 10 Cs magic-angle spinning NMR with combination of Rietveld refinement. 12 They observed that calcinations and rehydration of a 72% Cs + -exchanged zeolite Y led to a partial migration of Na + ions from the sodalite units into the supercages making them accessible to further ion exchange. They could obtain a 90% Cs + -exchanged zeolite Y by a three-fold exchange-calcination cycle of the 72% Cs + -exchanged sample without damage to the zeolite structure.…”

“…7 The crystal structures of Cs + -exchanged faujasite-type zeolites have been reported by several scientists. [8][9][10][11][12] Smolin et al investigated hydrated and dehydrated partially Cs + -exchanged zeolite X (Si/Al = 1.11 (2)) with an exchanged level of 0.48 (4) by using the single-crystal X-ray diffraction technique. 8 They suggested Cs + ions were located only in the supercage by the analysis of the cation distribution in the hydrated forms.…”

Crystal Structure of Fully Dehydrated Partially Cs+-Exchanged Zeolite X, Cs52Na40-X (The Highest Cs+-Exchanged Level Achieved by Conventional Method and Confirmation of Special Site Selectivity)

“…Consequently, cesium exchange levels up to 90% were achieved by a threefold exchange-calcination cycle of the 72% cesium-exchanged sample without damage of the zeolite structure. 34 In addition, the Cs + ions get through all 6-ring windows and are located at all different crystallographic sites. The site I' and II' positions in the sodalite cavities are occupied by only cesium cations (Cs(2) and Cs(4)) (see Figures 4 and 5).…”