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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 30, Number 3
BKCSDE 30(3)
March 20, 2009 

 
Title
Single-crystal Structure of Fully Dehydrated and Largely NH4+-exchanged Zeolite Y (FAU, Si/Al = 1.70), |(NH4)60Na11|[Si121Al71O384]-FAU
Author
Sung Man Seo, Ghyung Hwa Kim*, Young Hun Kim, Lianzhou Wang, Gao Qing Lu, Woo Taik Lim*
Keywords
Zeolite Y, Ammonium-exchange, Single-crystal X-ray diffraction, Crystal structure
Abstract
The single-crystal structure of largely ammonium-exchanged zeolite Y dehydrated at room temperature (293 K) and 1 × 10-6 Torr. has been determined using synchrotron X-radiation in the cubic space group Fd3m (a = 24.9639(2) A) at 294 K. The structure was refined to the final error index R1 = 0.0429 with 926 reflections where Fo > 4σ(Fo); the composition (best integers) was identified as |(NH4)60Na11|[Si121Al71O384]-FAU. The 11 Na+ ions per unit cell were found at three different crystallographic sites and 60 NH4+ ions were distributed over three sites. The 3 Na+ ions were located at site I, the center of the hexagonal prism (Na-O = 2.842(5) A and O-Na-O = 85.98(12)o). The 4 Na+ and 22 NH4+ ions were found at site I' in the sodalite cavity opposite the double 6-rings, respectively (Na-O = 2.53(13) A, O-Na-O = 99.9(7)o, N-O = 2.762(11) A, and O-N-O = 89.1(5)o). About 4 Na+ ions occupied site II (Na-O = 2.40(4) A and O-Na-O = 108.9(3)o) and 29 NH4+ ions occupy site II (N-O = 2.824(9) A and O-N-O = 87.3(3)o) opposite to the single 6-rings in the supercage. The remaining 9 NH4+ ions were distributed over site III' (N-O = 2.55(3), 2.725(13) A and O-N-O = 94.1(13), 62.16(15), 155.7(14)o).
Page
543 - 550
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