Single-Crystal Structure of Fully Dehydrated, Largely Rb⁺-Exchanged Zeolite Y (FAU, Si/Al = 1.56), |Rb₅₉Na₁₆|[Si₁₁₇Al₇₅O₃₈₄]-FAU

Abstract

A single crystal of fully dehydrated, largely Rb⁺-exchanged zeolite Y, |Rb₅₉Na₁₆|[Si₁₁₇Al₇₅O₃₈₄]-FAU (Si/Al = 1.56), prepared by exchange of |Na₇₅|[Si₁₁₇Al₇₅O₃₈₄]-FAU with an aqueous stream 0.1 M RbOH at 293 K, followed by vacuum dehydration at 673 K and at 1 × 10⁻⁶ Torr. Its crystal structure was determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd $\overline{3}$ m and was refined to the final error indices R ₁/wR ₂ = 0.0392/0.1189. In the structure of |Rb₅₉Na₁₆|[Si₁₁₇Al₇₅O₃₈₄]-FAU, about 59 Rb⁺ ions per unit cell occupy five different equipoints; 9 are at site I, 9 at site I′, 3 at site II′, 28 at site II, and the remaining 10 are at site III, preferring II. The residual 16 Na⁺ ions occupy three equipoints; 5 are at site I′, 3 at site II, and 8 are at site III. These Rb⁺ and Na⁺ ions filled full from hexagonal prism to supercage. This work achieved the highest level of Rb⁺-exchange (ca. 81 %) in the single-crystal structure of zeolite Y by conventional method using aqueous solution at room temperature. The distributions of Rb⁺ and Na⁺ ions in this structure, as compared to fully dehydrated partially Rb⁺-exchanged zeolite X, are different due to local Si/Al order among the T atoms.

Graphical Abstract

The single-crystal structure of fully dehydrated, largely Rb⁺-exchanged zeolite Y, |Rb₅₉Na₁₆|[Si₁₁₇Al₇₅O₃₈₄]-FAU (Si/Al = 1.56), was determined by single-crystal synchrotron X-ray diffraction techniques.