Single-crystal Synchrotron X-ray Diffraction Techniques Research Articles

Facile quantization of semiconductor compounds in the zeolite: characterization of quantum dots of Zn4S6+ and Zn2S2+ in zeolite Y

The extra-framework zinc sulfide cationic clusters, Zn4S6+ and Zn2S2+, have been introduced into zeolite Y (FAU, Si/Al = 1.56). The |Zn24.5Na12(Zn4S6+)0.5(Zn2S2+)5.5|[Si117Al75O384]-FAU was prepared by allowing aqueous 0.1 M Na2S solution to flow past a |Zn37.5|[Si117Al75O384]-FAU at 294 K for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques. The crystallographic study showed that one sulfide ion at the center of the sodalite cavity coordinates to four Zn2+ ions at site I’ to give a centered-tetrahedral cationic cluster, Zn4S6+, and the other sulfide ion opposite 6-ring in the sodalite cavity bridges between two Zn2+ ions at site I’ to give a cationic cluster with bent arrangement, Zn2S2+, in 6.3% and 68.8% of the sodalite cavity of zeolite Y, respectively. Through high-resolution transmission electron microscope image, zinc sulfide quantum dots (QDs) group with the size of one unit cell (ca. 3 nm) in which hundreds were distributed was identified. By using UV–vis diffuse reflectance spectroscopy, it was confirmed that the zinc sulfide QDs occupied in the structure of zeolite Y exhibited enhanced optical activity because of the quantum size effect compared with that of bulk zinc sulfide. In this study, a method for quantizing semiconducting compounds in the cavity of zeolite Y was presented more easily, and its properties were investigated in more depth. The results proved that zeolite could be applied and used as a quantum container for the quantization of semiconductor compounds.

Synthesis and single-crystal structure of sodium sulfide cationic cluster in the sodalite cavity of zeolite Y (FAU, Si/Al = 1.56)

The extraframework sodium sulfide cationic cluster, Na4S2+, has been introduced into zeolite Y (FAU, Si/Al = 1.56). A single crystal of |Na73(Na4S2+)1.0|[Si117Al75O384]-FAU was prepared by allowing aqueous 0.1 M Na2S solution to flow past a |Na75|[Si117Al75O384]-FAU crystal, and followed by vacuum dehydration at 723 K. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd $$\overline{3}$$ m. The structure was refined using all intensities to the final error index R1/wR2 = 0.044/0.125. About 77 Na+ ions per unit cell are found at the crystallographically distinct positions, six. One Na+ ion per unit cell is at the center of double 6-ring. Two site-I′ positions are occupied by 26.5 and 4 Na+ ions, respectively, per unit cell. Thirty-two Na+ ions per unit cell are found at site II, in the supercage opposite single 6-rings. The remaining 4.5 and 9 Na+ ions per unit cell occupy two sites III′ near triple 4-rings in the supercage. Finally, one sulfide ion per unit cell, associated with Na+ ions, is found at the center of sodalite cavity. The 4 Na+ ions at site I′ coordinate to a sulfide ion at the center of sodalite cavity to give tetrahedral cationic cluster, Na4S2+. In |Na73(Na4S2+)1.0|[Si117Al75O384]-FAU, tetrahedral Na4S2+ ions center about 12.5% of the sodalite cavities.

Crystallographic Study of Water Distribution, Dehydration, Rehydration, Demethylation, and Decomposition Processes in Zeolitic Imidazolate Framework ZIF-8

The structures of 19 single crystals of ZIF-8 that were subjected to different thermal treatments have been determined. Crystal 1 was as-synthesized from an in situ synthetic batch. Crystals 2–12 were thermally treated at various temperatures under dynamic vacuum for 48 h. A dehydrated ZIF-8 was rehydrated by flowing distilled water at 293 K for 1 h (crystal 13). Crystals 14–19 were thermally treated at 798 K under dynamic vacuum for 1, 2, 3, 4, 5, and 6 h, respectively. Their crystal structures were completely determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group I4̅3m at 100(1) K. In the structures of crystals 1 and 2, about 20 and 0.8 water molecules per unit cell occupied two crystallographic sites at O1 (opposite 4-ring) and O2 (center of 6-ring plane). Unlike the crystals 1 and 2, a trace amount of water molecules found only one crystallographic site at O2 in the structures of crystals 3–10. The crystals 11, 12, and 14 were completely dehydrated. In the structure of crystal 13, about 33 water molecules were readsorbed not only at O1 and O2 sites but also at the new site O3. In the structures of crystals 15–19, partial demethylation of 2-methylimidazolate ligands in ZIF-8 occurred, and the remaining methyl group of 2-methylimidazolate ligands were found with the occupancies of 22.4(3), 21.8(3), 20.7(5), 20.6(4), and 16.6(13), respectively.

A crystallographic study of Sr2+ and K+ ion-exchanged zeolite Y (FAU, Si/Al = 1.56) from binary solution with different mole ratio of Sr2+ and K+

To study the Sr2+-ion selectivity of zeolite Y (Si/Al = 1.56) in binary solution with different Sr2+ and K+ concentration during exchange, two single-crystals of fully dehydrated, Sr2+- and K+-exchanged zeolites Y were prepared by the flow method using a mixed ion-exchange solution whose Sr(NO3)2:KNO3 mol ratios were 1:1 (crystal 1) and 1:100 (crystal 2), respectively, with a total concentration of 0.05 M, followed by vacuum dehydration at 723 K. Their crystal structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $$ Fd\bar{3}m $$, respectively, and were refined to the final error indices R1/wR2 = 0.0429/0.1437 and 0.0356/0.1239 for crystals 1 and 2, respectively. In the structure of |Sr28K19|[Si117Al75O384]-FAU (crystal 1), 28 Sr2+ ions per unit cell occupy four different crystallographically distinct sites; 15, 2, 2, and 9 are at sites I, I′, II′, and II, respectively, whereas, the K+ ions occupy only one site: 19 are at site II. In the structure of |Sr17K41|[Si117Al75O384]-FAU (crystal 2), 17 Sr2+ ions per unit cell occupy three equipoints; 10.5, 2, and 4.5 are at sites I, I′, and II, respectively. The residual 41 K+ ions per unit cell are found at four different sites; 8, 24, 3, and 6 are at sites I′, II, III′a, and III′b, respectively. The degrees of ion exchange are 74.7 and 45.3% for crystals 1 and 2, respectively. This result shows that the degree of Sr2+ exchange decreased sharply by decreasing the initial Sr2+ concentration and increasing the initial K+ concentration in the given ion-exchange solution.

Crystal structure of a hydrogen sulfide sorption complex of anhydrous Mn2+-exchanged zeolite Y (FAU, Si/Al = 1.56)

Abstract The structure of a hydrogen sulfide sorption complex of anhydrous Mn2+-exchanged zeolite Y, |Mn37.5(H2S)16.5|[Si117Al75O384]-Y, has been determined at 100(1) K by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd 3 ¯ m. The complex was prepared by treating Mn37.5-Y with H2S(g), followed by evacuation for 0.5 h. The structure was refined using all intensities to the final error index R1 = 0.062 (for Fo > 4σ(Fo)). Mn2+ ions occupy four crystallographic sites. The 16 double 6-rings per unit cell are fully occupied, about 11 with a Mn2+ ion at their centers and 5 with a Mn2+ ion on each side. The remaining Mn2+ ions are found at two single-6-ring sites, about 11.5 in supercages and 5 in sodalite cavities. H2S molecules occupy two crystallographic sites, about 11.5 in supercages and 5 in sodalite cavities. Each supercage H2S molecule coordinates to a Mn2+ ion in a single 6-ring, and each sodalite H2S molecule bridges between two double-6-ring Mn2+ ions. The Mn-S bond lengths are 2.410(20) A and 2.49(23) A, respectively.

Structure of a cyclohexane sorption complex of partially dehydrated, fully Mn2+-exchanged zeolite Y (FAU, Si/Al = 1.56)

The structure of a cyclohexane sorption complex of partially dehydrated, fully Mn2+-exchanged zeolite Y has been determined at 100(1) K by single-crystal synchrotron X-ray diffraction techniques. It was refined using all intensities to the final error indices R1 = 0.052 and wR2 = 0.174. Cyclohexane molecules of symmetry 3¯2/m (D3d, chair form) occupy 5.7 of the 16 12-rings per unit cell. Each cyclohexane molecule is held in place by 18 weak hydrogen bonds between its six equatorial hydrogen atoms and all 12 oxygen atoms of its 12-ring: C⋯O ca. 3.85 Å. Mn2+ ions are found at four crystallographic sites, I, I′, II′, and II. Each of the 17.7(2) Mn2+ ions per unit cell at site II (opposite 6-rings in the supercage) coordinates tetrahedrally to three framework oxygen atoms and a water molecule. The cyclohexane molecules interact neither with the Mn2+ ions nor with the water molecules.

Crystallographic studies of fully dehydrated partially Zn2+-exchanged zeolite Y (FAU, Si/Al = 1.56) depending on Zn2+ concentration of aqueous solution during exchange

Four single crystals of fully dehydrated and partially Zn2+-exchanged zeolites Y (Si/Al = 1.56) were prepared by the static ion-exchange method using a mixed ion-exchange solution in which Zn(NO3)2:NaCl mole ratios were 1:1 (crystal 1), 1:25 (crystal 2), 1:50 (crystal 3), and 1:100 (crystal 4), respectively, with a total concentration of 0.05 M, and followed by vacuum dehydration at 673 K. Their single-crystal structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd\(\bar {3}\)m and refined to the final error indices R1/wR2 = 0.0459/0.1454, 0.0449/0.1283, 0.0427/0.1284, and 0.0486/0.1680, respectively. Their unit-cell formulas are |Zn25Na25|[Si117Al75O384]-FAU (crystal 1), |Zn19.5Na36|[Si117Al75O384]-FAU (crystal 2), |Zn19.5Na36|[Si117Al75O384]-FAU (crystal 3), and |Zn7Na61|[Si117Al75O384]-FAU (crystal 4), respectively. The degree of Zn2+ exchange decreases from 67 to 19% as the initial concentration of Zn2+ decrease and the initial concentration of Na+ increases in given ion-exchange solutions.

Time-Dependent Ni2+-Ion Exchange in Zeolites Y (FAU, Si/Al = 1.56) and Their Single-Crystal Structures

Seven single crystals of fully dehydrated Ni2+-exchanged zeolite Y (Si/Al = 1.56) were prepared via cation exchange of Na75-Y (|Na75|[Si117Al75O384]-FAU) by flowing 0.05 M aqueous solutions of Ni(NO3)2·6H2O (pH = 4.9, at 294 K) with various ion-exchange time. Their crystal structures were completely determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd–3m at 100(1) K. In all seven structures, Ni2+ ions occupy sites I, I’, II, and sometimes II’ or a second II, or both, preferring site I; residual Na+ ions in crystals 1 and 2 are found at site III and/or a second III. The level of Ni2+ exchange monotonically increased from 75.2% to 89.6% (from 28.2(2) to 33.6(8) Ni2+ per unit cell) with increasing exchange time until 18 h. The dealumination of zeolite frameworks was observed in the center of sodalite cavities after 24 h, suggesting that this process occurs during ion-exchanges, or subsequent dehydration. H+ ions are present in all seven crystals for a charge balan...

Crystallographic studies on the site selectivity of Ca2+, K+, and Rb+ ions within zeolite Y (Si/Al = 1.56)

The single-crystals of Ca2+, K+-exchanged zeolite Y, and Ca2+, Rb+-exchanged zeolite Y were prepared by using flow method with mixed ion-exchange solution, whose Ca(NO3)2:KNO3 mole ratios were 1:1 (crystal 1) and 1:100 (crystal 2), and Ca(NO3)2:RbNO3 mole ratios were 1:1 (crystal 3) and 1:100 (crystal 4), respectively, with a total concentration of 0.05 M. They were fully dehydrated by vacuum dehydration at 723 K and 1 × 10−6 Torr for 2 days. Their crystals were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $$Fd \overline{3}$$ m, respectively, and were refined to the final error indices R 1/wR 2 = 0.057/0.196, 0.073/0.223, 0.055/0.188, and 0.049/0.175 for crystals 1, 2, 3, and 4, respectively. In the structure of crystal 1 (|Ca23K29|[Si117Al75O384]-FAU), 23 Ca2+ ions per unit cell occupy sites I, II′, and II; 29 K+ ions per unit cell are at sites II′, II, and III′. In the structure of crystal 2 (|Ca18.5K38|[Si117Al75O384]-FAU), 18.5 Ca2+ ions per unit cell occupy sites I, I′, and II; 38 K+ ions are at sites I′, II, and III′. In the structure of crystal 3 (|Ca27Rb21|[Si117Al75O384]-FAU), 27 Ca2+ ions per unit cell occupy sites I, II′, and II; 21 Rb+ ions per unit cell are at sites II′, II, and III. In the structure of crystal 4 (|Ca18Rb39|[Si117Al75O384]-FAU), 18 Ca2+ ions per unit cell occupy sites I and II; 39 Rb+ ions per unit cell are at sites I′, II′, II, III, and III′. In the four crystals, the Ca2+ ion which has much smaller size and higher charge than other cations such as K+ and Rb+ energetically preferred at site I and so the first to be filled on it. Unlike Ca2+ ion, no K+ and Rb+ ions are found at site I, which are clearly less favorable for K+ and Rb+ ions.

Behavior of cesium cation in zeolite Y (FAU, Si/Al = 1.56) and their single-crystal structures, |Cs75−xNax|[Si117Al75O384]-FAU (x = 35 and 54)

To study the tendency of Cs+ exchange into zeolite Y (Si/Al = 1.56) dependence on Cs+ and Na+ concentration of aqueous solution during exchange, two single-crystals of fully dehydrated, Cs+-and Na+-exchanged zeolites Y were prepared by the flow method using a mixed ion-exchange solution whose CsNO3:NaNO3 mol ratios were 1:1 (crystal 1) and 1:100 (crystal 2), respectively, with a total concentration of 0.1 M, followed by vacuum dehydration at 723 K. Their crystals were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd $$\overline{ 3}$$ m, respectively, and were refined to the final error indices R 1/wR 2 = 0.084/0.248 and 0.088/0.274 for crystals 1 and 2, respectively. In the structure of |Cs40Na35|[Si117Al75O384]-FAU (crystal 1), 40 Cs+ ions per unit cell occupy five different equipoints; 3, 3, 14, 9, and 11 are at sites I, II′, II, IIIa and IIIb, respectively, whereas, the remaining 35 Na+ ions occupy three different sites: 9, 11, and 15 are at sites I, I′, and II, respectively. In the structure of |Cs21Na54|[Si117Al75O384]-FAU (crystal 2), 21 Cs + ions per unit cell occupy three equipoints; 4, 6, and 11 are at sites II, IIIa, and IIIb, respectively. The residual 54 Na+ ions per unit cell are found at three different sites; 6, 20 and 28 are at sites I, I′, and II, respectively. The degrees of ion exchange are 53 and 28 % for crystals 1and 2, respectively. This result shows that the degree of Cs+ exchange decreased sharply by decreasing the initial Cs+ concentration and increasing the initial Na+ concentration in given ion-exchange solution.

Structural comparison of partially dehydrated partially Co2+-exchanged zeolites X (FAU, Si/Al = 1.40) and Y (FAU, Si/Al = 1.70)

The structures of partially dehydrated and partially Co2+-exchanged zeolites X (Si/Al = 1.40) and Y (Si/Al = 1.70) were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd $$\overline{3}$$ m and were refined to the final error indices R 1/wR 2 = 0.0773/0.2152 and 0.0683/0.2184, respectively. Their unit-cell formulas are |Co26.1Na21(H3O)7.1(H2O)14.2|[Si112Al80O384]-FAU (a = 24.7892(2) A) and |Co29.3Na6.2(H3O)5.9(H2O)5.9|[Si121Al71O384]-FAU (a = 24.7346(2) A), respectively. In the structure of Co2+-X, Co2+ ions occupy sites I′, II′, II, and III′; the Na+ ions are at sites I′ and II. In the structure of Co2+-Y, Co2+ ions occupy sites I′, II′, II, and III′; the Na+ ions are at site I′. Because of the low pH of the Co2+ exchange solution, some H3O+ ions are observed in both structures. The number of Co2+ ions in zeolite was increased slightly as Si/Al ratio increased, and Na+ content and the unit cell constant of the framework were decreased.

High-pressure behavior of cuprospinel CuFe2O4: Influence of the Jahn-Teller effect on the spinel structure

The Jahn-Teller effect at Cu2+ in cuprospinel CuFe2O4 was investigated using high-pressure single-crystal synchrotron X-ray diffraction techniques at beamline BL10A at the Photon Factory, KEK, Japan. Six data sets were collected in the pressure range from ambient to 5.9 GPa at room temperature. Structural refinements based on the data were performed at 0.0, 1.8, 2.7, and 4.6 GPa. The unit-cell volume of cuprospinel decreases continuously from 590.8(6) to 579.5(8) A3 up to 3.8 GPa. Least-squares fitting to a third-order Birch-Murnaghan equation of state yields the zero-pressure volume V = 590.7(1) A3 and bulk modulus K = 188.1(4.4) GPa with K ′ fixed at 4.0. The structural formula determined by electron microprobe analysis and site occupancy refinement is represented as T (Fe3+0.90Cu2+0.10) M (Fe3+1.10Fe2+0.40Cu2+0.50)O4. Most of the Cu2+ are preferentially distributed onto the octahedrally coordinated ( M ) site of the spinel structure. With pressure, the arrangement of the oxygen atoms around the M cation approaches a regular octahedron. This leads to an increase in the electrostatic repulsion between the coordinating oxygen ions and the 3 d z2 orbital of M Cu2+. At 4.6 GPa, a cubic-tetragonal phase transition is indicated by a splitting of the a axis of the cubic structure into a smaller a axis and a longer c axis, with unit-cell parameters a = 5.882(1) A and c = 8.337(1) A. The tetragonal structure with space group I 41/ amd was refined to R 1 = 0.0332 and wR 2 = 0.0703 using 38 observed reflections. At the M site, the two M -O bonds parallel to the c -axis direction of the unit cell are stretched with respect to the four M -O bonds parallel to the a-b plane, which leads to an elongated octahedron along the c -axis. The cubic-to-tetragonal transition induced by the Jahn-Teller effect at Cu2+ is attributable to this distortion of the CuO6 octahedron and involves Cu 3 d z2 orbital, ab initio quantum chemical calculations support the observation. At the tetrahedrally coordinated ( T ) site, on the other hand, the tetrahedral O- T -O bond angle increases from 109.47° to 111.7(7)°, which generates a compressed tetrahedral geometry along the c -axis. As a result of the competing distortions between the elongated octahedron and the compressed tetrahedron, the a unit-cell parameter is shortened with respect to the c unit-cell parameter, giving a c / a ′ ratio ( ![Formula][1] ) slightly greater than unity as referred to cubic lattice ( c / a ′ = 1.002). The c / a ′ value increases to 1.007 with pressure, suggesting further distortions of the elongated octahedron and compressed tetrahedron. [1]: /embed/mml-math-1.gif

Characterization of Li+-ion Exchanged Zeolite Y using Organic Solvents

To investigate the tendency of Li + exchange from polar organic solvents, Li + -ion exchange into zeolite Y (Si/Al = 1.56) was attempted by undried methanol (crystal 1) and formamide (crystal 2) solvent. Two single crystals of Na-Y were treated with 0.1 M LiNO3 in each of the two solvents at 323 K, followed by vacuum dehydration at 723 K. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd3m, at 100(1) K. In both structures, Li + for Na + ions filled preferentially sites I’ and II. The remaining Na+ ions occupied sites I’, II, and III’ in both structures, in additional to above sites, and Na + ions occupied site I in crystal 2. While the 68 % exchange of Li + for Na + was achieved from undried methanol, only 40 % exchange was observed from undried formamide, indicating that the undried methanol was more effective than undried formamide as solvent for Li + exchange under the conditions employed.

Single-crystal structures of Zn2+-exchanged zeolite A: dependence on Zn2+ concentration of aqueous solution during exchange

To study the tendency of Zn2+ exchange into zeolite A, two single-crystals of fully dehydrated Zn2+-and Na+-exchanged zeolite A were prepared by the static ion-exchange method using a mixed ion-exchange solution whose Zn(NO3)2:NaNO3 mol ratios were 1:4 (crystal 1) and 3:2 (crystal 2), respectively, with a total concentration of 0.05 M, followed by vacuum dehydration at 623 K. Their single-crystal structures and chemical compositions were determined by single-crystal synchrotron X-ray diffraction techniques and electron probe microanalysis. Their structures were refined to the final error indices R 1/wR 2 = 0.0678/0.2154 and 0.0619/0.1938 for crystals 1 and 2, respectively. In both structures, the 4 Zn2+ ions are located in sodalite unit, whereas, the remaining 4 Na+ ions are located in large cavity. Unit-cell formula of two single-crystal structures is approximately |Zn4Na4|[Si12Al12O48]-LTA. This work shows that the degree of Zn2+ exchange by increasing the initial Zn2+ concentration and decreasing the initial Na+ concentration in given ion-exchange solution does not differ significantly.

Preparation and structural study of fully dehydrated, highly Mg2+-exchanged zeolite Y (FAU, Si/Al = 1.56) from undried methanol solution

Single-crystal of fully dehydrated, Mg2+-exchanged zeolite Y, |Mg34.5Na6|[Si117Al75O384]-FAU (Si/Al = 1.56), was successfully prepared from undried methanol solution (water concentration 0.02 M). A crystal of Na-Y was treated with 0.05 M MgCl2 ·6H2O in the solvent at 333 K, followed by vacuum dehydration at 723 K and 1 × 10−6 Torr for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques, in the cubic space group $$Fd\overline{3} m$$ at 100 K. It was refined to the final error indices R 1/wR 2 = 0.0587/0.2210 with 1,294 reflections for which F o > 4σ(F o). In the structure of |Mg34.5Na6|[Si117Al75O384]-FAU, 34.5 Mg2+ ions per unit cell are found at four different crystallographic sites: 15 per unit cell are located at site I at the center of the hexagonal prism [Mg–O = 2.216(2) A], two are at site I’ in the sodalite cavity near the hexagonal prism [Mg–O = 2.20(3) A], only one is located at site II’ in the sodalite cavity [Mg–O = 2.197(23) A], and the remaining 16.5 are at site II near single 6-oxygen rings in the supercage [Mg–O = 2.103(3) A]. The residual 6 Na+ ions per unit cell are found at site II [Na–O = 2.218(7) A]. No water molecules are found in this structure.

Single-Crystal Structures of Sr2+ and Cs+-Exchanged Zeolites X and Y, |Sr40Cs12|[Si100Al92O384]-FAU and |Sr29Cs17|[Si117Al75O384]-FAU

Two single-crystals of fully dehydrated, Sr2+-and Cs+-exchanged zeolites X (|Sr40Cs12|[Si100Al92O384]-FAU (Si/Al = 1.09, crystal 1)) and Y (|Sr29Cs17|[Si117Al75O384]-FAU (Si/Al = 1.56, crystal 2)) were prepared by the flow method using a mixed ion-exchange solution whose Sr(NO3)2:CsNO3 mol ratio was 1:1 with a total concentration of 0.1 M. The crystals were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $$Fd\overline{ 3}$$ and $$Fd\overline{ 3} m,$$ respectively, and were refined to the final error indices R 1/wR 2 = 0.070/0.209 and 0.052/0.155 for crystals 1 and 2, respectively. In the structure of |Sr40Cs12|[Si100Al92O384]-FAU, 40 Sr2+ ions per unit cell occupy three different equipoints; 16, 1.5, and 22.5 are at sites I, II′, and II, respectively. The 12 Cs+ ions per unit cell occupy three equipoints; 1, 6, and 5 are at sites II′, II, and IIIa, respectively. In the structure of |Sr29Cs17|[Si117Al75O384]-FAU, 29 Sr2+ ions per unit cell occupy four equipoints; 15, 1.5, 2.5, and 10 are at sites I, I′, II′, and II, respectively. The 17 Cs+ ions per unit cell are found at four different sites; 2.5, 9, 4, and 1.5 are at sites II′, II, IIIa, and IIIb, respectively. The Sr2+ ions occupy smaller pore size such as the centers of the double 6-rings and the positions near the center of single 6-rings planes, whereas, Cs+ ions preferentially occupy large-cavity sites in the supercage. Two single-crystals of fully dehydrated, Sr2+-and Cs+-exchanged zeolites X (|Sr40Cs12|[Si100Al92O384]-FAU (Si/Al = 1.09, crystal 1)) and Y (|Sr29Cs17|[Si117Al75O384]-FAU (Si/Al = 1.56, crystal 2)) were determined by single-crystal synchrotron X-ray diffraction techniques.

Preparation of excessively Ni2+-exchanged zeolite Y (FAU, Si/Al = 1.70) and its single-crystal structure

A single crystal of excessively Ni2+-exchanged zeolite Y (FAU, Si/Al = 1.70) was prepared by exchange of |Na71|[Si121Al71O384]-FAU with an aqueous stream 0.05 M Ni(NO3)2 at 293 K and pH 4.9, followed by vacuum evacuation at room temperature and 1.3 × 10−4 Pa. 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 = 0.0554/0.1557 for |Ni24.7(NiOH)12.1(Ni2O(OH)2)4.8(Ni4AlO4)1.7Na17.0(H3O)6.9|[Si117Al75O384]-FAU. Crystal has about 53 Ni2+ ions per unit cell, indicating the uptake of excess Ni(OH)2, perhaps as NiOH+ ions. Some dealumination of the framework occurred during Ni2+ exchange. In this structure, Ni2+ ions occupy sites I, I′, II′, II, and III′. The residual Na+ ions are found at sites II′ and II. Due to the low pH of the Ni2+ exchange solution, some H3O+ ions are observed. Nonframework oxygen atoms as oxide and hydroxide ions and orthoaluminate coordinate to some of Ni2+ ions to give NiOH+, Ni2O(OH)2, and Ni4AlO4 3+ groups.

Single-Crystal Structure of Fully Dehydrated and Partially Dealuminated Zeolite Y (FAU, Si/Al = 1.56) Mn2+ Exchanged by Flow Method

The single-crystal structure of fully dehydrated zeolite Y (FAU, Si/Al = 1.56) Mn2+ exchanged by flow method, |Mn31(Mn4AlO4)H10|[Si117Al75O384]-FAU, was determined by single-crystal synchrotron X-ray diffraction techniques. It was refined to the final error indices R 1/wR 2 = 0.0692/0.2026 in the cubic space group $$Fd\overline{3}m$$ at 100(1) K. In this structure, 35 Mn2+ ions per unit cell are found at four crystallographic positions: 11 and 7 are at the centers of the double 6-rings (site I) and in the sodalite cavity opposite the double 6-rings (site I′), respectively. The remaining 4 and 13 are found at sites II′ (near 6-ring in the sodalite cavity) and II (near 6-ring in the supercage), respectively. Some dealumination of the zeolite framework occurred during Mn2+ exchange. The four non-framework oxygen atoms coordinate to a aluminate ion at the center of sodalite cavity (site U) and 4 Mn2+ ions at site II′ to give Mn4AlO4 3+. The 10 H+ ions are required for charge balance in fully dehydrated Mn2+-Y. The single-crystal structure of fully dehydrated, partially dealuminated, and Mn2+-exchanged zeolite Y (FAU (Si/Al = 1.56) was determined by single-crystal synchrotron X-ray diffraction techniques.

Complete Li+ exchange into zeolite X (FAU, Si/Al = 1.09) from undried methanol solution

Complete exchange of Li+ into zeolite Na-X, |Na92|[Si100Al92O384]-FAU, was accomplished using undried methanol solvent (water concentration 0.02 M). A crystal of Na-X was treated with 0.1 M LiNO3 in the solvent at 333 K, followed by vacuum dehydration at 673 K and 1 × 10−6 Torr for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques, in the cubic space group \( Fd\overline{3} \) at 100(1) K. The 92 Li+ ions per unit cell are found at three different crystallographic sites. The 32 Li+ ions occupy at site I’ in the sodalite cavity: these Li+ ions are recessed 0.28 A into the sodalite cavity from their 3-oxygens plane [Li–O = 1.903(5) A and O–Li–O = 117.8(3)°]. Another 32 Li+ ions are found at site II in the supercage, being recessed 0.26 A into the supercage [Li–O = 1.968(5) A and O–Li–O = 118.3(3)°]. The remaining 28 Li+ ions are located at site III in the supercage [Li–O = 2.00(8) A].

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

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. 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.