Synthesis and Characterization of the Large Single Crystal of Fully K⁺-exchanged Zeolite X (FAU), |K₈₀|[Si₁₁₂Al₈₀O₃₈₄]-FAU (Si/Al=1.41)

Abstract

Large colorless single crystals of sodium zeolite X, stoichiometry |Na80|[Si112Al80O384]-FAU, with diameters up to 200 μm and Si/Al = 1.41 have been synthesized from gels with the composition of 2.40SiO2 : 2.00NaAlO2 : 7.52NaOH : 454H2O : 5.00TEA. One of these, a colorless octahedron about 200 μm in cross-section has been treated with aqueous 0.1 M KNO3 for the preparation of K + -exchanged zeolite X. The crystal structure of |K80|[Si112Al80O384]-FAU per unit cell, a = 24.838(4) Å, dehydrated at 673 K and 1 × 10 −6 Torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd at 294 K. The structure was refined using all intensities to the final error indices (using only the 707 reflections for which Fo > 4σ (Fo)) R1 = 0.075 (based on F) and R2 = 0.236 (based on