The single-crystal structure of partially Mg2+-exchanged zeolite Y, |Mg35.5Na4(H2O)3|[Si117Al75O384]-FAU per unit cell, a = 24.4661(1) �, dehydrated at 723 K and 1 � 10-6 Torr, has been determined by single-crystal X-ray diffraction technique in the cubic space group Fd-3m at 100(1) K.  The structure was refined using all intensities to the final error indices (using only the 1287 reflections with Fo > 4s(Fo)) R1 = 0.0547 (Based on F) and R2 = 0.1552 (Based on F2).  About 35.5 Mg2+ ions per unit cell are found at four different crystallographic sites.  The 13 Mg2+ ions occupied at site I, at the center of double 6-ring (D6Rs, Mg-O = 2.233(2) � and O-Mg-O = 90.50(8)�).  Six Mg2+ ions are found at site I' in the sodalite cavity; the Mg2+ ions were recessed 1.20 � into the sodalite cavity from their 3-oxygen plane (Mg-O = 2.189(12) � and O-Mg-O = 92.9(6)�).  Site II' positions (opposite single 6-rings in the sodalite cage) are occupied by 3 Mg2+ ions, each coordinated to an H2O molecule (Mg-O = 2.181(7) � and O-Mg-O = 112.3(5)�).  The 13.5 Mg2+ ions are filled at site II in the supercage, being recessed 0.11 � into the supercage (Mg-O = 2.094(3) � and O-Mg-O = 119.73(5)�).  About 4 Na+ ions per unit cell are found at one crystallographic site; the Na+ ions are located at site II in the supercage (Na-O = 2.219(6) � and O-Na-O = 109.4(4)�).

Crystallographic study of Mg2+-exchanged zeolite Y (FAU, Si/Al = 1.56) from aqueous solution at 333 K, |Mg35.5Na4(H2O)3|[Si117Al75O384]-FAU

248th National Meeting (2014)

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