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

2009년 8월 14일 14시 06분 12초
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목 <발표Ⅱ>
저자 및
서성만, 김경화1, 이석희2, 임우택
안동대학교 응용화학과, Korea
1포항가속기연구소 빔라인부 엑스선운영2팀, Korea
2부산교육대학교 과학교육과, Korea
Large single crystals of zeolite, |Na75|[Si117Al75O384]-FAU (Na-Y, Si/Al = 1.56), were synthesized from gels with composition of 3.58SiO2 : 2.08NaAlO2 : 7.59NaOH : 455H2O : 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 × 10-6 Torr for 2 days. The crystal structure of fully dehydrated partially Cs+-exchanged zeolite Y, |Cs45Na30|[Si117Al75O384]-FAU per unit cell (a = 24.9080(10) Å) was determined by single-crystal X-ray diffraction technique in the cubic space group Fd3-m at 294 K. The structure was refined using all intensities to the final error indices (using only the 877 reflections for which Fo > 4σ(Fo)) R1 = 0.0966 (based on F) and R2 = 0.2641 (based on F2). About forty-five Cs+ ions per unit cell are found at six different crystallographic sites. The 2 Cs+ ions occupied at site I, at the centers of double 6-ring (D6Rs, Cs-O = 2.774(10) Å and O-Cs-O = 88.9(3) and 91.1(3)o). Two Cs+ ions are found at site I' in the sodalite cavity; the Cs+ ions were recessed 2.05 Å into the sodalite cavity from their 3-oxygen plane (Cs-O = 3.05(3) Å and O-Cs-O = 77.4(13)o). Site-II' positions (opposite single 6-rings in the sodalite cage) are occupied by 7 Cs+ ions, each of which extends 2.04 Å into the sodalite cage from its 3-oxygen plane (Cs-O = 3.067(11) Å and O-Cs-O = 80.1(3)o). The 26 Cs+ ions are nearly three-quarters filled at site II in the supercage, being recessed 2.34 Å into the supercage (Cs-O = 3.273(8) Å and O-Cs-O = 74.3(3)o). The 4 Cs+ ions are found at site III deep in the supercage (Cs-O = 3.321(19) and 3.08(3) Å), and 4 Cs+ ions at another site III' (Cs-O = 2.87(4) and 3.38(4) Å). About 30 Na+ ions per unit cell are found at one crystallographic site; the Na+ ions are located at site I' in the sodalite cavity opposite double 6-rings (Na-O = 2.578(11) Å and O-Na-O = 97.8(4)o).