To study the tendency of Cs+ exchange into zeolite Y (Si/Al = 1.56) dependence on Cs+ concentration of aqueous solution during exchange, two single-crystals of fully dehydrated, Cs+-and Na+-exchanged zeolites Y were prepared by the flow method using a mixed ion-exchange solution whose Cs(NO3)2:NaNO3 mole ratios were 1:1 (crystal 1) and 1:100 (crystal 2), respectively, with a total concentration of 0.05 M, followed by vacuum dehydration at 723 K. Their crystals were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd3- m, respectively, and were refined to the final error indices R1/wR2 = 0.084/0.248 and 0.088/0.274 for crystals 1 and 2, respectively. In the structure of |Sr40Cs12|[Si100Al92O384]-FAU (crystal 1), 40 Cs+ ions per unit cell occupy five different equipoints; 3, 3, 14, 9, and 11 are at sites I, II’, II, IIIa and IIIb, respectively, whereas, the remaining 35 Na+ ions occupy three different sites: 9, 11, and 15 are at sites I, I’, and II, respectively. In the structure of |Sr29Cs17|[Si117Al75O384]-FAU (crystal 2), 21 Cs + ions per unit cell occupy three equipoints; 4, 6, 2, and 11 are at sites II, IIIa, and IIIb, respectively. The residual 54 Na+ ions per unit cell are found at three different sites; 6, 20 and 28 are at sites I, I’, and II, respectively. The degrees of ion exchange are 53 and 28% for crystals 1and 2, respectively. This result shows that the degree of Cs+ exchange decreased sharply by decreasing the initial Cs+ concentration and increasing the initial Na+ concentration in given ion-exchange solution.

Single-crystal structures of Cs+-exchanged Zeolite Y:dependence on Cs+ concentration of aqueous solution during exchange

250th National Meeting (2015)

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