Single-crystal Structure of Fully Dehydrated and Largely NH₄⁺-exchanged Zeolite Y (FAU, Si/Al = 1.70), │(NH₄)₆₀Na₁₁│[Si₁₂₁Al₇₁O₃₈₄]-FAU

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 Fd 3 m (a = 24.9639(2) Å) 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) Å 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) (14) o ).