Sodalite Cavities Research Articles

New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH3

5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NOx with NH3 (NH3-SCR) was evaluated on both fresh and aged catalysts. Physical/chemical characterizations such as X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) were performed, along with detailed in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) experiments including CO adsorption, NH3 adsorption, and NO + O2 reactions. Results showed that, for the 5Cu-USY catalyst, hydrothermal ageing treatment could somehow improve the low-temperature SCR activity, but it also led to significant formation of unfavorable byproducts NO2 and N2O. Such an activity change can be attributed to hydrothermal ageing inducing the migration of isolated Cu+ species in the sodalite cavities towards the super cages of the USY zeolites. The increased content of Cu+ species in the super cages was beneficial for the low-temperature activity improvement, but, at the same time, it also facilitated ammonia oxidation at high temperatures. Ce doping after hydrothermal ageing has a “double-edged sword” effect on the catalytic performance. First of all, Ce doping can inhibit Cu species migration by self-occupying the internal cage sites; thus, the catalytic performance of 5Cu8Ce-USY-700H remains stable after ageing. Secondly, Ce doping introduces a CuOx–CeO2 strong interaction, which facilitates lattice oxygen mobility by forming more oxygen vacancies so as to increase the concentration of surface active oxygen. These changes, on the one hand, could help to promote further oxidative decomposition of nitrate/nitrite intermediates and improve the catalytic performance. But, on the other hand, it also causes the byproduct generation to become more severe.

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.

Minireview of pentatomic cations in sodalite cavities

Centered-tetrahedral cationic clusters are frequently found in the sodalite cavities of zeolites and in the cavities of analogues of the mineral sodalite. Examples are Mn4S6+, Fe4Te6+, Zn4Se6+, Cd4S6+, Cu4Cl7+, Na4Cl3+, Na4I3+, Na54+, In57+, Ga57+, and Sn512+.

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.

Disproportionation of an Element in a Zeolite. III. Crystal Structure of a High-Temperature Sulfur Sorption Complex of Zeolite LTA Containing Two New Ions: Perthiosulfite, S42–, and the Trisulfur Cation, S32+

The structure of a high-temperature sulfur sorption complex of zeolite Na-A (LTA) has been determined by single-crystal crystallography. It was prepared by treating anhydrous Na-A with sulfur vapor at 623 K. Its crystal structure was refined in the space group Pm3m (a = 12.192(1) A) to the error index R1 = 0.075. Upon sorption, sulfur disproportionated fully to give one perthiosulfite anion, S42–, and one trisulfur cation, S32+, per unit cell. The perthiosulfite anion (S–S = 2.16(5) A and S–S–S = 105.4(22)°) is the perthio form of SO32–. It is in the large cavity where it bonds to one 6-ring and three 8-ring Na+ ions (S–Na = 2.83(6) A, 2.80(5) A, and 2.43(5) A). It appears to be the first example of a branched polysulfide ion. The electron-deficient trisulfur cation, S32+ (S–S = 2.11(8) A and S–S–S = 102.0(14)°), bonds to framework oxygen atoms in the sodalite cavity (S–O = 2.64(7) A). Twelve Na+ ions are found per unit cell at five crystallographic sites similar to but different from those in anhydrous ...

The Pentatin Cation in Zeolite Y: Thallous Ion Exchange and Crystal Structure of |Sn36Cl11|[Si128Al64O384]-FAU Containing Sn512+, Sn2Cl3+, and Sn3Cl5+

Sn512+, Sn2Cl3+, and Sn3Cl5+ have replaced all of the Tl+ ions in the zeolite Tl71–Y (|Tl71|[Si121Al71O384]-FAU) by thallous ion exchange (TIE), a vapor phase ion exchange method. SnCl2(g) was allowed to react with Tl71–Y under anhydrous conditions at 673 K for 48 h. The crystal structure of the product, |(Sn512+)1.70Sn2+27.4Cl–10.8|[Si127.6Al64.4O384]-FAU per unit cell, was determined by single-crystal crystallography at 294 K using synchrotron X-radiation (Fd3m, a = 24.758(1) A). It was refined with all 1465 unique data to the final error indices R1 = 0.061 and R2 = 0.208. Its composition was confirmed by scanning electron microscopy energy-dispersive X-ray analysis. Centered tetrahedral Sn512+ clusters center 21% of the sodalite cavities. About 10 Sn2+ ions per unit cell near 12-rings are bridged by Cl– ions to form five Sn2Cl3+ clusters. Similarly, six Sn3Cl5+ clusters have formed, each containing one 6-ring and two 12-ring Sn2+ ions.

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...

Encapsulating Luminescent Materials in Zeolites. III. Crystal Structure and Scintillation Properties of Cs,Na-LTA Treated with Zirconium Chloride Vapor

With the purpose of developing a new zeolite scintillator, fully dehydrated Cs,Na-A was exposed to ZrCl4 (g, 3.7 × 103 Pa) at 523 K. The crystal structures of Cs,Na-A and of the product, |Zr0.14Cs5.69Na4.13Cl0.85|[Si12Al12O48]-LTA (Zr,Cs,Na,Cl-A), were determined by single-crystal crystallography using synchrotron X-radiation. The structure of Zr,Cs,Na,Cl-A was refined in the space group Pm3̅m (a = 12.230(1) Å) with all unique data to the final error index R1 = 0.069 for the 639 reflections for which Fo > 4σ(Fo). Its composition was confirmed by scanning electron microscopy energy-dispersive X-ray analysis (SEM-EDX). Octahedral ZrCl62– ions center 14% of the large cavities; each Cl– ion bonds to an 8-ring Cs+ ion. These Cs+ ions bridge between ZrCl62– ions to form a continuum with unit cell formula Cs3ZrCl6+ in the near-surface volume of the crystal. Other Cs+ ions lie opposite 6-rings in the sodalite and large cavities; Na+ ions occupy the remaining 6-rings. Upon X-irradiation, Zr,Cs,Na,Cl-A luminesces bright sky blue; the emission band is broad, ranging from 370 to 750 nm, peaking at 480 nm. The integrated intensity of the emission is ca. 16 times greater than that of anthracene, a well documented scintillator. This intense luminescence appears to result from charge transfer within the ZrCl62– ions.

Structures of the Subnanometer Clusters of Cadmium Sulfide Encapsulated in Zeolite Y: Cd4S6+ and Cd(SHCd)46+

The structures of the subnanometer clusters of CdS that form in zeolite Y (FAU), prepared as follows, have been determined. A single crystal of Cd2+-exchanged zeolite Y was prepared by the exchange of Na75–Y (|Na75|[Si117Al75O384]–Y with aqueous Cd(NO3)2 at 294 K, followed by vacuum dehydration at 723 K (crystal 1). A second crystal, similarly prepared, was exposed to 6.7 × 104 Pa of dry H2S(g) for 6 h at 294 K and evacuated (crystal 2). Their structures were determined crystallographically using synchrotron X-rays and were refined using all data to the final error indices (calculated using only Fo > 4σ(Fo)) of R1/wR2 = 0.040/0.156 and 0.049/0.186, respectively. In crystal 1, Cd2+ ions primarily occupy sites I and II. In crystal 2, |Cd27(Cd4S6+)0.6(Cd(SHCd)46+)0.9H12|[Si117Al75O384]–FAU, tetrahedral Cd4S6+ ions center about 7.5% of the sodalite cavities and tetrahedral Cd(SHCd)46+ ions center about 11% of the supercages. In Cd(SHCd)46+, a Cd2+ ion at the center of a supercage bonds tetrahedrally to four S...

Effect of preparation conditions on the indium species in fully indium exchanged zeolite LTA

Three fully indium-exchanged zeolite A (LTA) crystals, In-A, were prepared by the reaction of fully dehydrated Tl-A with indium metal at 623, 673, and 723 K. Three additional crystals were prepared as above and then hydrated, washed with water, and redehydrated (post-treatment). All six structures were determined crystallographically with synchrotron X-radiation and refined in the space group Pm3¯m. Monatomic In+ ions predominate in all crystals: ca. 63–83 atomic % of the In atoms present are monatomic In+ at 6- and 8-ring positions. Tetrahedral In57+ clusters are always found in the sodalite cavities, occupying from 9% to 82% of them. Before post-treatment, only In+, In57+, and In3+ were found, and the In+ population was greatest after the 673 K reaction. The In57+ population decreases monotonically with increasing reaction temperature due to its disproportionation to In+ and In3+. Between 673 K and 723 K, In+ begins to disproportionate also, to In3+ and In0. Post-treatment continues the extent of these disproportionations to In3+ and In0. Some of the In0 atoms produced bridge between remaining In+ ions to form In32+ and In75+. The remainder have moved to the surface of the zeolite crystal.

Optical properties of the hydrated charged silver tetramer and silver hexamer encapsulated inside the sodalite cavity of an LTA-type zeolite.

The optical spectra in the UV-VIS region of the hydrated doubly charged tetramer Ag4(2+) and hydrated multiply charged hexamer Ag6(p+) silver clusters encapsulated inside the sodalite cavity of an LTA-type zeolite have been systematically predicted using DFT, TD-DFT and CASSCF/CASPT2 methods. The optical behaviour of the model hydrated clusters [Ag6(H2O)8(Si24H24O36)](p+) is very sensitive to their charge. Among the cations [Ag6(H2O)8(Si24H24O36)](p+), only the embedded hydrated quadruply charged silver hexamer [Ag6(H2O)8(Si24H24O36)](4+) shows a strong absorption band at ∼420 nm (blue light) and emits light in red color. The absorption spectrum of the hydrated doubly charged silver tetramer cluster [Ag4(H2O)m(Si24H24O36)](2+), which shifts slightly and steadily with the increasing amount of interacting water molecules to longer wavelengths, has a strong peak in the blue region. The water environment forces the silver tetramer to relocate into one side of the cavity instead of at its center as in the case of the non-hydrated [Ag4(Si24H24O36)](2+) cluster. Water molecules act as ligands significantly splitting the energy levels of excited states of the Ag4(2+) and Ag6(4+) clusters. This causes the absorption spectra of the clusters to broaden and the emission to shift to the green-yellow and red part of the visible region.

Encapsulating Photoluminescent Materials in Zeolites. II. Crystal Structure of Fully Dehydrated Ce21H46O18–Y (Si/Al = 1.69) Containing Ce4O44+, CeOH2+, Ce3+, and H+

Encapsulating photoluminescent centers within zeolites may give them long-term stability and enhanced luminosity. A single crystal of zeolite Na–Y (FAU, Si/Al = 1.69) was fully exchanged with Tl+, then exchanged with Ce3+ and dehydrated at 623 K and 2 × 10–4 Pa to give |Ce4O44+3.5CeOH2+4.6Ce3+2.1H+41.7|[Si121Al71O384]–FAU. Its structure was determined crystallographically (space group Fd3m, a = 24.909(1) A) with synchrotron X-radiation and was refined using all 1236 unique data to R1 = 0.067 (Fo > 4σ(Fo)) and R2 = 0.247. The 20.5 Ce3+ ions per unit cell occupy four crystallographically distinct cation sites: 0.5 are octahedral at site I, 1.6 trigonal at site I′, 13.8 octahedral at a second site I′, and 4.6 tetrahedral at site II. The 13.8 Ce3+ ions at the second site I′ are members of Ce4O44+ clusters, tetrahedrally distorted cubes occupying 43% of the sodalite cavities. Each of these Ce3+ ions bonds octahedrally to three oxygen atoms of the zeolite framework (2.482(7) A) and to three extraframework oxid...

Using the Thallous Ion Exchange Method to Exchange Tin into High Alumina Zeolites. 1. Crystal Structure of |Sn2+5.3Sn4+0.8Cl–1.8|[Si12Al12O48]-LTA

Sn2+ and Sn4+ ions have replaced all of the Tl+ ions in the zeolite Tl12-A (|Tl12|[Si12Al12O48]-LTA) by thallous ion exchange (TIE), a vapor phase ion exchange method: SnCl2(g) was allowed to react with Tl12-A under anhydrous conditions at 723 K for 48 h. The tin content of the product, |Sn2+5.3Sn4+0.8Cl–1.8|[Si12Al12O48]-LTA, is 32.6 wt %, much higher than previously reported for any zeolite. Its structure was determined by single-crystal crystallography at 294 K using synchrotron X-radiation (Pm3m, a = 12.075(1) A, R1 = 0.069, R2 = 0.224), and its composition was confirmed by scanning electron microscopy energy-dispersive X-ray analysis. Sn2+ is found at four crystallographic positions, Sn4+ at two, and Cl– at two. Among the 5.3 Sn2+ ions per unit cell, 2.7 (3-coordinate) lie opposite 6-rings in large cavities, 0.3 (4-coordinate) are opposite 6-rings in sodalite cavities, 1.5 are in 8-rings, and 0.7 approach a framework oxygen atom and two chloride ions in a trigonal planar manner. Among the 0.8 Sn4+ i...

On the Lewis acidity of protonic zeolites

IR spectra of hydroxyl groups, adsorbed CO, pivalonitrile and pyridine on three H-MFI zeolite samples and on two H-Y faujasites are reported and discussed. Samples richer in Al (H-MFI (Si/Al2=30) and H-Y (Si/Al2=5.1)) show the presence of extraframework species and the presence of Lewis acidity together with Brønsted acidity. H-MFI with lowest Al content (Si/Al2=280) does not show any extraframework species (EF) and only presents Brønsted acidity. H-MFI with intermediate Al content (Si/Al2=50) possess very small amount of EF species and of Lewis acidity. H-Y with low Al content (Si/Al2=30) does not show extraframework species but shows the presence of Lewis acidity together with Brønsted acidity. The role of extraframework material as carrier of Lewis acidity is confirmed. It is proposed that Lewis acidity of low Al-content H-Y can arise from framework tetrahedral Al ions, which can enlarge their coordination to five without any previous dehydroxylation. A support for this hypothesis is given by the reversible shift of the LF OH stretching band, whose extent depends on the strength of the basic molecules: this is certainly not due to a direct interaction of the OH groups responsible for the LF band, which are located in cavities (sodalite cavity and hexagonal prisms) where the molecular probes cannot access.

First Successful Application of the Thallous Ion Exchange (TIE) Method. Preparation of Fully Indium-Exchanged Zeolite Y (FAU, Si/Al = 1.69)

Fully indium-exchanged zeolite Y, |In+62.6(In57+)1.2|[Si121Al71O384], was prepared by thallous ion exchange (TIE), a vapor phase ion exchange method. InCl(g, 510 Pa) was allowed to react with a single crystal of Tl71–Y under anhydrous conditions at 623 K. A second crystal prepared as above was washed with deionized water and redehydrated to give |In+39.7 (In57+)4.5|[Si121Al71O384]. The structures of fully dehydrated Tl71–Y and these two forms of In–Y were determined by single-crystal crystallography using synchrotron X-radiation. Then the two In–Y crystals were subjected to scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis. Both methods indicated that no Tl remained in the In–Y crystals. The additional steps of washing and redehydration caused some of the In+ ions in the first In–Y crystal to disproportionate to give additional In57+ clusters in the sodalite cavities and In0 atoms on the crystal surface. Most of the In+ ions in both forms of In–Y are easily accessible to guest molecu...

Introducing copper ions into zeolite Y by the thallous ion exchange method: single crystal structure of |Cu21.6Tl39.2|[Si121Al71O384]–FAU

The thallous ion exchange (TIE) method was used for the first time in an attempt to introduce copper ions into zeolite Y (FAU, Si/Al = 1.69). |Cu 10.9 + Cu 10.7 2+ Tl 39.2 + |[Si121Al71O384]–FAU was prepared by reacting fully dehydrated and fully Tl+-exchanged zeolite Y (Tl71–Y) with CuCl2(g) and its decomposition products CuCl(g) and Cl2(g) at 673 K under anhydrous conditions. Its structure was determined using single-crystal crystallography with synchrotron X-radiation and was refined in the space group $${Fd}\bar{3}$$ m (a = 24.769(1) A) with all 903 unique data; the final error index, R 1 = 0.075, was calculated using only the 858 reflections with F o > 4σ(F o). About 45 % of the Tl+ ions were replaced by 21.6 copper ions per unit cell at the following sites (distances to nearest framework oxygen atoms are given): 10.7 Cu2+ at site I′ in the sodalite cavity opposite double 6-rings (Cu2+–O = 2.093(9) A), 3.5 Cu+ at site II opposite single 6-rings in the supercage (Cu+–O = 2.24(3) A), and 7.4 Cu+ at site III near 12-rings in the supercage (Cu+–O = 2.45(7) A). All Cu+ ions are in supercages where they are easily accessible to guest molecules. The remaining ca. 39 Tl+ ions per unit cell occupy three distinct positions: 12 are at a second site I′ (Tl+–O = 2.571(9) A), 23 are at a second site II (Tl+–O = 2.732(10) A), and 4 are at site III′ (Tl+–O = 2.871(16) A) near triple 4-rings in the supercages.

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.

Using CuCl vapor to ion exchange copper into zeolite Na–Y. Single crystal structure of |Cu30Na30Cl9|[Si121Al71O384]–FAU containing [formula omitted], Cu4Cl7+, Cu3Cl2+, and Cu2+

A single crystal of zeolite Na–Y (FAU, Si/Al=1.69) was treated with 1.6Pa of anhydrous CuCl vapor at 623K to yield Cu30Na30Cl9–Y, in more detail ∣Na+30Cu2+2(Cu16Cl721+)0.44(Cu4Cl7+)3.2(Cu3Cl2+)2.8|[Si121Al71O384]–FAU. Its structure was determined crystallographically with synchrotron X-radiation and was refined in the space group Fd3¯m (a=24.644(1)Å) with all 1159 unique data; the final error index, R1=0.064, was calculated using only the 1028 reflections with Fo>4σ(Fo). About 58% of the Na+ ions in the zeolite were replaced by Cu2+, Cu3Cl2+, Cu4Cl7+, and Cu16Cl721+. Cu4Cl7+ clusters center 41% of the sodalite cavities. Each is a centered tetrahedron with Cu–Cl=2.931(3)Å; each terminal Cu2+ ion bonds to three framework oxygen atoms of one ring of a double 6-ring with Cu–O=2.222(4)Å and O–Cu–O=110.8(5)°. Cu16Cl721+ clusters center 5.5% of the supercages. Four Cu+ ions coordinate tetrahedrally to the chloride ion at its center (Cu–Cl=2.66(11)Å). Each pair of these Cu+ ions is bridged by a Cl− ion (Cu–Cl=3.03(7)Å) along each tetrahedral edge. Each of these Cl− ions then coordinates to two Cu2+ ions (Cu–Cl=2.58(7)Å), each of which bonds to two 12-ring oxygen atoms (Cu–O=2.35(3) and 2.41(4)Å with O–Cu–O=67.8(8)°). About 17.5% of the 12-rings are centered by near trigonal planar Cu3Cl2+ clusters (Cl− at the center, Cu–Cl–Cu=117.2(3)°, and Cu–O=2.52(4)Å). The single 6-rings are fully occupied by the remaining 2.0(5) Cu2+ ions (Cu–O=2.158(7)Å) and the 30.0(5) Na+ ions (Na–O=2.297(4) Å) per unit cell. Most of the Cu+ and Cu2+ ions in this material are accessible to guest molecules via the 12-ring channel system.

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].