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

Abstract

Large single crystals of zeolite, vertical bar Na-75 vertical bar[Si117Al75O384]-FAU (Na-Y, Si/Al = 1.56), were synthesized from gels with composition of 3.58SiO(2) : 2.08NaAlO(2) : 7.59NaOH : 455H(2)O : 5.06TEA : 2.23TCl. One of these, a colorless single-crystal was ion exchanged by allowing aqueous 0.02 M CsOH to flow past the crystal at 293 K for 3 days, followed by dehydration at 673 K and 1 x 10(-6) Torr for 2 days. The crystal structure of fully dehydrated partially Cs+-exchanged zeolite Y, vertical bar Cs45Na30 vertical bar[Si117Al75O384]-FAU per unit cell (a = 24.9080(10) angstrom) was determined by single-crystal X-ray diffraction technique in the cubic space group Fd (3) over barm at 294(1) K. The structure was refined using all intensities to the final error indices (using only the 877 reflections with F-o > 4 sigma(F-o)) R-1 = 0.0966 (Based on F) and R-2 = 0.2641 (Based on F-2). About forty-five Cs+ ions per unit cell are found at six different crystallographic sites. The 2 Cs+ ions occupied at site 1, at the centers of double 6-ring (D6Rs, Cs-O = 2.774(10) angstrom and O-Cs-O = 88.9(3) and 91.1(3)degrees). Two Cs+ ions are found at site I' in the sodalite cavity

the Cs+ ions were recessed 2.05 angstrom into the sodalite cavity from their 3-oxygen plane (Cs-O = 3.05(3) angstrom and O-Cs-O = 77.4(13)degrees). Site-II' positions (opposite single 6-rings in the sodalite cage) are occupied by 7 Cs+ ions, each of which extends 2.04 angstrom into the socialite cage from its 3-oxygen plane (Cs-O = 3.067(11) angstrom and O-Cs-O = 80.1(3)degrees). The 26 Cs+ ions are nearly three-quarters tilled at site II in the supercage, being recessed 2.34 angstrom into the supercage (Cs-O = 3.273(8) angstrom and O-Cs-O = 74.3(3)degrees). The 4 Cs+ ions are found at site III deep in the supercage (Cs-O = 3.321(19) and 3.08(3) angstrom), and 4 Cs+ ions at another site III' (Cs-O = 2.87(4) and 3.38(4) angstrom). About 30 Na+ ions per unit cell are found at one crystallographic site

The Na+ ions are located at site I' in the socialite cavity opposite double 6-rings (Na-O = 2.578(11) angstrom and O-Na-O = 97.8(4)degrees).