Crystal Structure of Dehydrated Rb+-Exchanged Zeolite X, Rb71Na21Si100Al92O384

摘要

The crystal structure of dehydrated Rb+-exchanged zeolite X, stoichiometry Rb71Na21-X (Rb71Na21Si100Al92O384) per unit cell, has been determined from single-crystal X-ray diffraction date gathered by counter methods. The structure was solved and refined in the cubic space group Fd3, a=25.007(3) ∈ at 21(1) ∩. The crystal was prepared by ion exchange in a flowing stream using a 0.05 M aqueous RbOH solution (pH=12.7). The crystal was then dehydrated at 360 ∩ and 2】10-6 torr for two days. The structure was refined to the final error indices, R1=0.047 and R2=0.040 with 239 reflections for which I 3ヲ(I). In this structure, 71 Rb+ ions per unit cell are found at six different crystallographic sites and 21 Na+ ions per unit cell are found at two different crystallographic sites. Four and a half Rb+ ions are located at site グ, the center of the hexagonal prism. Nine Rb+ ions are found at site グ` in the sodalite cavity (Rb-O=2.910(15) ∈ and O-Rb-O=78.1(4)∑). Eighteen Rb+ ions are found at site ケ in the supercage (Rb-O=2.789(9) ∈ and O-Rb-O=92.1(4)∑). Two and a half Rb+ ions, which lie at site ケ`, are recessed ca. 2.07 ∈ into the sodalite cavity from their three O(2) oxygen planes (Rb-O=3.105(37) ∈ and O-Rb-O=80.6(5)∑). Thirty-two Rb+ ions are found at site ゲ deep in the supercage (Rb-O=2.918(12) ∈ and O-Rb-O=71.9(4)∑), and five Rb+ ions are found at site ゲ`. Seven Na+ ions also lie at site グ. Fourteen Na+ ions are found at site ケ in the supercage (Na-O=2.350(19) ∈ and O-Na-O=117.5(6)∑).