Single crystal structure of fully dehydrated fully K+-exchanged zeolite Y (FAU), K71Si121Al71O384

摘要: Abstract The crystal structure of K71-Y (FAU), K71Si121Al71O384 per unit cell, a = 24.9976(7) A, dehydrated at 653 K and 8 × 10−6 Torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 ¯ m 294 K. was refined using all intensities to final error indices (using only 695 reflections for which Fo > 4σ(Fo)) R1 = 0.045 (based on F) R2 = 0.136 F2). About 71 K+ ions cell are found an unusually large number crystallographically distinct positions, eight. They exhibit same degree cation crowding seen K92-X (FAU) as continue crowd into sites I I′. Six centers double 6-rings (D6Rs, site I; K–O = 2.733(5) A O–K–O (octahedral) = 89.90(14)° 90.10(14)°). Five additional near (K–O = 2.530(11) 2.972(15) A); each is pushed off center a ion site-I′ position. Two positions (in sodalite cavities opposite D6Rs) occupied ten five ions, respectively, cell; these recessed 1.30 A 1.68 A from their 3-oxygen planes (K–O = 2.581(15) 2.69(3) A, O–K–O = 96.9(7)° 84.9(14)°, respectively). These push site-I (K+ ⋯ K+ = 3.65(4) A), and, turn, themselves deeper cavities. Nearly filling II supercages 30.3(3) extends 1.36 A supercage its plane (K–O = 2.688(4) A O–K–O = 96.86(13)°). 9.4(4) III lie central ring triple 4-ring (K–O = 2.894(11) A twice O–K–O = 81.2(4)°). remaining 2.0(7) 1.5(6) occupy two III′ 4-rings (K–O = 2.41(10), 2.89(5), 2.57(8), 2.97(4) A). 20 fewer than K92-X; other much smaller occupancy differences seen.