Determination of Si/Al Ratio of Faujasite-type Zeolite by Single-crystal X-ray DiffractionTechnique. Single-crystal Structures of Fully Tl+- and Partially K+-exchangedZeolites Y (FAU), |Tl71|[Si121Al

Bulletin of the Korean chemical society

Oh Seuk Lee¹  Ik-Jo Chun¹  Dong Han Bae¹  Woo Taik Lim¹  Hu Sik Kim¹  Sung Man Seo¹ 

关键词: Faujasite-type zeolite;    Si/Al ratio;    Crystal structure;    Thallium;    Potassium;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

Large colorless single crystals of faujasite-type zeolite with diameters up to 200 レm have been synthesized from gels with the composition of 3.58SiO2:2.08NaAlO2:7.59NaOH:455H2O:5.06TEA:1.23TCl. Two of these, colorless octahedron about 200 レm in cross-section have been treated with aqueous 0.1 M TlC₂H₃O₂ and KNO₃ in order to prepare Tl⁺- and K⁺-exchanged faujasite-type zeolites, respectively, and then determined the Si/Al ratio of the zeolite framework. The crystal structures of |Tl₇₁|[Si₁₂₁Al₇₁O₃₈₄]-FAU and |K₅₃Na₁₈|[Si₁₂₁Al₇₁O₃₈₄]-FAU per unit cell, a = 24.9463(2) and 24.9211(16) A, respectively, dehydrated at 673 K and 1 �? 10^-6 Torr, have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd m at 294 K. The two single-crystal structures were refined using all intensities to the final error indices (using only the 905 and 429 reflections for which F_o > 4_�?(F_o)) R₁/R₂ = 0.059/0.153 and 0.066/0.290, respectively. In the structure of fully Tl⁺-exchanged faujasite-type zeolite, 71 Tl⁺ ions per unit cell are located at four different crystallographic sites. Twenty-nine Tl⁺ ions fill site I` in the sodalite cavities on 3-fold axes opposite double 6-rings (Tl-O = 2.631(12) A and O-Tl-O = 93.8(4)o). Another 31 Tl<sup>+</sup> ions fill site II opposite single 6-rings in the supercage (Tl-O = 2.782(12) A and O-Tl-O = 87.9(4)o). About 3 Tl<sup>+</sup> ions are found at site III in the supercage (Tl-O = 2.91(6) and 3.44(3) A), and the remaining 8 occupy another site III (Tl-O = 2.49(5) and 3.06(3) A). In the structure of partially K<sup>+</sup>-exchanged faujasite-type zeolite, 53 K<sup>+</sup> ions per unit cell are found at five different crystallographic sites and 18 Na<sup>+</sup> ions per unit cell are found at two different crystallographic sites. The 4 K<sup>+</sup> ions are located at site I, the center of the hexagonal prism (K-O = 2.796(8) A and O-K-O = 89.0(3)o). The 10 K<sup>+</sup> ions are found at site I` in the sodalite cavity (K-O = 2.570(19) A and O-KO = 99.4(9)o). Twenty-two K+ ions are found at site II in the supercage (K-O = 2.711(9) A and O-K-O = 94.7(3)o). The 5 K⁺ ions are found at site III deep in the supercage (K-O = 2.90(5) and 3.36(3) A), and 12 K⁺ ions are found at another site III` (K-O = 2.55(3) and 2.968(18) A). Twelve Na<sup>+</sup> ions also lie at site I` (Na-O = 2.292(10) and O-Na-O = 117.5(5)o). The 6 Na⁺ ions are found at site II in the supercage (Na-O = 2.390(17) A and O-Na-O = 113.1(11)o). The Si/Al ratio of synthetic faujasite-type zeolite is 1.70 determined by the occupations of cations, 71, in two single-crystal structures.

【 授权许可】

Unknown