Preparation and structural study of fully dehydrated, highly Mg super(2+)-exchanged zeolite Y (FAU, Si/Al = 1.56) from undried methanol solution

• Published in: Journal of porous materials 2014-10, Vol.21 (5), p.659-665
• Main Authors: Kim, Hu Sik, Choi, Sang June, Lim, Woo Taik
• Format: Article
• Language: English
• Subjects: Aluminum; Dehydration; Holes; Magnesium; Methyl alcohol; Prisms; Sodalite; Unit cell
• ISSN: 1380-2224; 1573-4854
• DOI: 10.1007/s10934-014-9812-9

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Single-crystal of fully dehydrated, Mg super(2+)-exchanged zeolite Y, |Mg sub(34.5)Na sub(6)|[Si sub(117)Al sub(75)O sub(384)]-FAU (Si/Al = 1.56), was successfully prepared from undried methanol solution (water concentration 0.02 M). A crystal of Na-Y was treated with 0.05 M MgCl sub(2) .6H sub(2)O in the solvent at 333 K, followed by vacuum dehydration at 723 K and 1 10 super(-6) Torr for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques, in the cubic space group ... at 100 K. It was refined to the final error indices R sub(1)/wR sub(2) = 0.0587/0.2210 with 1,294 reflections for which F sub(o) > 4 sigma (F sub(o)). In the structure of |Mg sub(34.5)Na sub(6)|[Si sub(117)Al sub(75)O sub(384)]-FAU, 34.5 Mg super(2+) ions per unit cell are found at four different crystallographic sites: 15 per unit cell are located at site I at the center of the hexagonal prism [Mg-O = 2.216(2) Aa], two are at site I' in the sodalite cavity near the hexagonal prism [Mg-O = 2.20(3) Aa], only one is located at site II' in the sodalite cavity [Mg-O = 2.197(23) Aa], and the remaining 16.5 are at site II near single 6-oxygen rings in the supercage [Mg-O = 2.103(3) Aa]. The residual 6 Na super(+) ions per unit cell are found at site II [Na-O = 2.218(7) Aa]. No water molecules are found in this structure.