The Crystal Structure of Fully Dehydrated Fully Ba2+-Exchanged Zeolite X

摘要

The crystal structure of Ba46-X, Ba46Al92Si100O384 [a= 25.297(1) ∈], has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd&bar{3}at 21(1) ∩. The crystal was prepared by ion exchange in flowing stream of 0.05 M Ba(OH)2 aqueous solution for 5 days. The crystal was then dehydrated at 380 ∩ and 2 】 10-6 Torr for 2 days. The structure was refined to the final error indices R1= 0.051 and Rw= 0.054 with 369 reflections for which I > 3ヲ (I). In this structure, all Ba2+ ions are located at the three different crystallographic sites: fourteen Ba2+ ions are located at site グ, the centers of the double six rings, two Ba2+ ions lie at site グ`, in the sodalite cavity opposite double six rings(D6R`s) and another thirty Ba2+ ions are located at site ケ in the supercage. Two Ba2+ ions are recessed ca. 0.27 ∈ into the sodalite cavity from their three O(3) oxygen plane and thirty Ba2+ ions are recessed ca. 1.11 ∈ into the supercage from their three O(2) oxygen planes, respectively (Ba(1)-O(3) = 2.76(1) ∈, O(3)-Ba(1)-O(3) = 180(0)∑, Ba(2)-O(3) = 2.45(1) ∈, O(3)-Ba(2)-O(3) = 108(1)∑, Ba(3)-O(2)=2.65(1) ∈, and O(2)-Ba(3)-O(2)=103.9(4)∑).