Sodalite Cavities Research Articles

Crystal structure of a hydrogen sulfide sorption complex of zeolite LTA

3 ¯ m at 21(1) °C. The structure was refined to the final error indices R = 0.047 and R w = 0.033 with 153 reflections for which I > 3σ(I). Twelve H 2 S molecules are sorbed per unit cell. Eight Na + ions are found at two different 6-oxygen-ring sites, where each coordinates to three framework oxygens at ca. 2.32(2) Å. Six of the eight Na + ions extend 0.47(1) Å into the large cavity from the (111) planes of the 6 rings, where each coordinates at 2.98(2) Å to one H 2 S sulfur in the large cavity. The remaining two 6 ring Na + ions do not associate with H 2 S and are located near the centers of their 6 rings. Three Na + ions are found in 8-oxygen-ring planes, where each coordinates to one framework oxygen at 2.39(2) Å and to two H 2 S sulfurs in the large cavities at 2.74(3) Å. The twelfth Na + ion coordinates to the four framework oxygens of a 4-ring at 2.71 (3) Å, and to one or two of the above H 2 S molecules at 2.78(6) Å. The sodalite cavities are empty.

The properties of salt-filled sodalites. Part 4. Synthesis and heterogeneous reactions of iodate-enclathrated sodalite Na8[AlSiO4]6(IO3)2−x(OH·H2O)x; 0.7 < x < 1.3

Sodalite solid solutions Na8[AlSiO4]6(IO3)2−x(OH·H2O)x; (0.7 < x < 1.3) have been obtained in the system Na2O2SiO2Al2O3NaIO3H2O under hydrothermal conditions and characterized by X-ray powder diffraction, IR and MAS-NMR spectroscopy, as well as by simultaneous thermoanalysis in different gas atmospheres. Syntheses have been performed by the alkaline transformation of kaolinite at a temperature of 473 K in the presence of different amounts of sodium iodate salt. The composition range could only be varied down to x = 0.7, even with high amounts of sodium iodate in the initial mixtures. For the synthesis of a solid solution with a low content of iodate, a certain high concentration of the template salt has been found to be essential for the formation of a homogeneous sodalite solid solution. As well as its synthesis, the thermal properties of basic iodate sodalite have been investigated. A discontinuity of the thermal expansion could be detected as a result of temperature-induced host-guest interactions. Whereas at room temperature and during the initial heating process the aluminosilicate framework of sodalite is partially collapsed, at elevated temperatures (T = 773 K) an onset of a maximal expansion of the unit cell volume was apparent from the high-temperature X-ray powder diffraction results. Further investigations of the thermal behaviour of basic iodate sodalite (Na8[AlSiO4]6 (IO3)2−x(OH·H2O)x; x = 1) in different gas atmospheres gave evidence for intra-cage heterogeneous reactions, resulting in the formation of carbonate, nitrate or sulphite anions inside those sodalite cages, formerly filled with the “hydrated-hydroxide”. During this high temperature process, the decomposition of the iodate to iodide could be observed inside the sodalite cavities, causing high thermal stability in the resulting carbonate/iodide-, nitrate/iodide- or sulphite/iodide-sodalite solid solution.

Discussion on the Coordination of Ni2+ Ions to Lattice Oxygens in Calcined Faujasite-Type Zeolites Followed by Diffuse Reflectance Spectroscopy

The coordination of Ni2+ ions to lattice oxygens in calcined X and Y zeolites has been extensively studied. A survey of the literature is presented here. From X-ray diffraction, Ni2+ ions are known to occupy preferentially the hexagonal prisms (SI) in octahedral symmetry. The main d−d absorption bands of Ni2+ ions in calcined NiX and NiY were assigned on this basis. The corresponding low value of the crystal field (10Dq ≈ 6400 cm-1) was accounted for by unusual long Ni−O bond lengths at SI sites. We demonstrate here that this assignment is not consistent with recently reported extended X-ray absorption fine structure measurements and that the absorption bands should be reassigned to Ni2+ cations in distorted tetrahedral and trigonal (D3h) coordinations. These cations are located in the supercages and/or sodalite cavities.

Influence of the presence of NaF on the crystallization of zeolite A (LTA): First evidence for the existence of fluorosodalite, the missing end-member of the halosodalite series

During the attempt to synthesize zeolite A (LTA) with F − anions, a new sodalite material containing these anions was obtained. Fluoride anions play the role of mineralizer and template. According to the 19F MAS n.m.r. results, the localization of the F − anions in the sodalite cavities is proposed. This new compound completes the series of halo- and hydroxysodalites.

Structure of the tetrahedral sodium Na54+ cluster in zeolite X

A single crystal of zeolite Na 78 Rb 28 -X (approximate composition) was prepared by exposing Na 9 + 2 -X at 350 o C to 0.1 Torr of rubidium vapor, and its structure was determined by single-crystal X-ray diffraction methods in the cubic space group, Fd3, a=25.042(4) A. Only about 28 of the 92 Na + ions per unit cell we reduced, and only about 14 of the 28 Na 0 atoms produced were retained within the zeolite. A Na 5 4+ cluster is present within each sodalite cavity. It is a centered tetrahedron (like CH 4 ) with bond length 2.80(2) A and angle tetrahedral by symmetry, and show the full symmetry of its site, T d , at the center of the sodalite cavity

Crystal structure of zeolite A with potassium clusters and continua

A single crystal of fully dehydrated sodium zeolite A reacted with 0.3 Torr of potassium vapor at 300 o C. Its structure was determined by X-ray diffraction methods at 24 o C in the cubic space group Pm3m. Not only have all Na + ions have been replaced with K + by redox reaction, but additional potassium atoms were sorbed to give K n -A, n=14 to 1 5, per 12.298(2) A unit cell. Crystallographic results show that cationic tetrahedral K 4 and/or triangular K 3 clusters have formed in the sodalite cavities of zeolite A. The partially reduced ions of these clusters interact primarily with oxygen atoms of the zeolite structure rather than with each other

ChemInform Abstract: Crystal Structures of the Potassium Clusters in the Sodalite Cavities of Zeolites A and X.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Pulsed-neutron powder-diffraction study of lead sulfide and deuterium ions in zeolite Y

Sodium zeolite Y was largely ion exchanged with Pb[sup 2+] at 100[degree]C, evacuated at 400[degree]C, and treated with D[sub 2]S at 25[degree]C. Its structure (1) was determined by pulsed-neutron powder-diffraction methods. After further treatment, evacuation at 400[degree]C, its structure (2), now of composition Pb[sub 26]S[sub 4]Na[sub 11]Si[sub 137]Al[sub 55]O[sub 384], was determined again. Two different positions are found for deuterium ions in sample 1. Each of 18 deuterium ions in the large cavities bonds to an O(1) oxygen and lies in the plane of that oxygen and the two Si(Al) atoms to which O(1) is bound. In sodalite cavities, 16 deuterium ions bind similarly to O(3) oxygens. In structure 2, Pb[sup 2+] ions prefer site II, in the supercage opposite single six-oxygen rings. Although some uncertainty remains about the S[sup 2[minus]] positions in 2, it appears that S[sup 2[minus]] is responsible for the movement of some Pb[sup 2+] ions into sodalite cavities. If so, each S[sup 2[minus]] ion, located at the center of a double six-oxygen ring, bridges between two Pb[sup 2+] ions to form a linear (Pb-S-Pb)[sup 2+] cluster (Pb-S = 2.93(2) A). Excess lead was imbibed into the zeolite as lead oxide/hydroxide species during the aqueous ion-exchange process.more » After initial evacuation at 400[degree]C, only oxide of the initial oxide/hydroxide should have remained. After treatment with D[sub 2]S and subsequent evacuation at 400[degree]C, all nonframework oxides appear to have been replaced by sulfides. 34 refs., 5 figs., 5 tabs.« less

Crystal structures of the potassium clusters in the sodalite cavities of zeolites A and X

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structures of the potassium clusters in the sodalite cavities of zeolites A and XTao Sun and Karl SeffCite this: J. Phys. Chem. 1993, 97, 20, 5213–5214Publication Date (Print):May 1, 1993Publication History Published online1 May 2002Published inissue 1 May 1993https://doi.org/10.1021/j100122a007RIGHTS & PERMISSIONSArticle Views101Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Bromine-81 and chlorine-35 NMR investigation of sodium,silver,halo-sodalite semiconductor supralattices

81 Br and 35 Cl NMR yields, respectively, bromide and chloride site-specific information pertinent to the structural and electronic properties of Na 8-n-p- Ag n X 2-p -sodalite, semiconductor cluster supralattices, where X=Br, Cl; 0≤n≤8; 0≤p≤2. The 81 Br and 35 Cl MAS chemical shifts and line shapes observed for encapsulated Na 4 X and Ag 4 X clustcrs within the sodalite cavities provide insight into the nature of the intracluster bonding (ionic-covalent character) and the extent of intercavity coupling

A Cationic Cesium Continuum in Zeolite X

A cesium continuum that fills the channels and cavities of zeolite X has been prepared, and its structure has been determined by single-crystal x-ray crystallography. The three-dimensional continuum is cationic to balance the negative charge of the zeolite framework. Its valence electrons, only 0.3 per Cs(+) ion, are widely delocalized over 95 percent of the cesium ions in the crystal. The continuum has a unit cell formula of (Cs(122))(86+) and contains Cs(13) and Cs(14) clusters (one per supercage) arranged like the atoms in diamond, with one Cs(2) appendix (in the sodalite cavity) per cluster.

Guest-host interactions in sodium zeolite Y: structural and dynamical 23Na double-rotation NMR study of water, trimethylphosphine, molybdenum hexacarbonyl, and Mo(CO)4(PMe3)2 adsorption in Na56Y

[sup 23]Na double-rotation NMR (DOR) provides site-specific structural and dynamical information on guest-host interactions within sodium zeolite Y pores. Quantitative adsorption of H[sub 2]O, PMe[sub 3], and Mo(CO)[sub 6] guests affects both the positions and line shapes of the [sup 23]Na resonances from specific extraframework Na[sup +] sites. The evolution of the [sup 23]Na DOR spectra with the progressive introduction of guest molecules allows one to probe direct solvation' effects involving the Na[sup +] cations in the larger supercages, as well as indirect effects on the Na[sup +] cations in adjacent smaller sodalite cavities. [sup 23]Na DOR experiments conducted at two magnetic field strengths confirm that PMe[sub 3] coadsorption in 8[l brace]Mo(CO)[sub 6][r brace],16[l brace]PMe[sub 3][r brace]-Na[sub 56]Y, and PMe[sub 3] ligand-substitution in 8[l brace]cis-Mo(CO)[sub 4](PMe[sub 3])[sub 2][r brace]-Na[sub 56]Y give rise to progressive deshielding and enhanced quadrupolar interactions of the anchoring Na[sup +] cations in the [alpha]-cages, relative to those of the starting material, 8[l brace]Mo(CO)[sub 6][r brace]-Na[sub 56]Y. Spin-lattice relaxation measurements indicate that adsorption of PMe[sub 3] facilitates an increased motion of the Na[sup +] cations and/or guest species inside the [alpha]-cages. 22 refs., 6 figs., 1 tab.

Multinuclear magic-angle spinning and double-rotation NMR study of the synthesis and assembly of a sodalite semiconductor supralattice

{sup 29} Si-magic-angle spinning, {sup 27}Al and {sup 23}Na magic-angle spinning, and double rotation NMR provide structural and electronic details for the newly developed sodalite semiconductor quantum supralattices. The evolution of the nucleation and crystallization processes of sodium halide sodalites is monitored, and the appearance of anion-empty sodalite cages is detected. Subtle changes in the electronic and quadrupole interactions of sodium and aluminum nuclei occur upon loading chloride, bromide, and iodide into the sodalite cages. The NMR results suggest that the development of electronic coupling occurs throughout the lattice in mixed-halide chloro,iodosodalites. A preference for silver exchange of sodium cations in halide-containing cages, over hydroxide-containing and anion-empty sodalite cavities, is detected. Extraction of the isotropic chemical shift and quadrupole contributions to the sodium resonances is achieved by performing the NMR experiments at two magnetic field strengths. The parameters obtained indicate a change in the charge distribution around the sodium nuclei upon exchanging approximately one-quarter of the extraframework Na{sup +} cations with silver, which parallels other data pointing to the onset of a semiconductor supralattice within the sodalite matrix. 30 refs., 15 figs., 3 tabs.

NMR Relaxation of quadrupolar Nuclei as a Probe of the Motion of Guest Species in Sodalite Cavities

AbstractUseful information on interactions and motion of guest molecules in sodalite cavities is obtained by estimating the spin-lattice and spin-echo decay rates of encapsulated Br− ions. An extremely fast spin-lattice relaxation rate is observed for 81Br nuclei, adjacent to Br−-empty cages which contain rapidly tumbling water molecules. We detect a further significant different T1 of the 81Br in Na8Br2- sodalite and AgsBr2-sodalite, respectively, which probably indicates a less restricted motion within the cavities of the Ag+-exchanged material. Spin-echo decay experiments additionally indicate a difference between the dynamic properties of the Br− anion in the encapsulated Na4Br and Ag4Br clusters, respectively.

Crystal structure of partially desolvated (NiOH+)2(NH4+)10-A, with some discussion of the fully solvated structure

The crystal structure of Ni{sup 2+}, NH{sub 4}{sup +}-exchanged zeolite A, partially desolvated by evacuation at 23{degree}C (a = 12.289 (1) {angstrom}), has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m. The structure was refined to final R{sub 1} and R{sub 2} indices of 0.063 and 0.072, respectively. Two Ni{sup 2+} ions are located on threefold axes very close to 6-ring planes of the aluminosilicate framework. Each is equatorially coordinated to three O(3) framework oxygens and axially to OH{sup {minus}} (in the sodalite cavity) in a trigonal pyramidal configuration. Seven NH{sub 4}{sup +} ions on threefold axes are associated by hydrogen bonding to oxygens of the remaining empty 6-rings. Six of these are located in the large cavity and one, in the sodalite unit, shares a 6-ring with one of these six and bridges between the two OH{sup {minus}} ions. Three more NH{sub 4}{sup +} ions occupy 8-ring sites.

ChemInform Abstract: Two Crystal Structures of Dehydrated Ag+ and Rb+ Exchanged Zeolite A, Ag12‐xRbx‐A, x = 2 and 3.

AbstractSingle crystals of Ag10Rb2‐A and Ag9Rb3‐A, prepared by a flow technique using exchange solutions in which the mole ratios of AgNO3 and RbNO3 are 1:5 and 1:50, resp., and the total cationic concentration is kept at 0.05 M, belong to the cubic space group Pm3m. In both the structures, one reduced Ag atom per unit cell is found inside the sodalite cavity, which may be present as a Ag6 cluster in 1/6 of the sodalite units or as an isolated Ag atom coordinated to 4 Ag+ ions in each sodalite unit.

Crystal structure of cesium zeolite A prepared by complete aqueous exchange

The complete exchange of zeolite 4A with Cs + has been achieved by the reaction of a single crystal of hydrated NH 4 +-A with a modest excess of CsOH slush. Its structure was determined by X-ray crystallographic methods. Up to one additional molecule of CsOH is taken up per sodalite cavity. To avoid close Cs +-Cs + contacts through 6-rings, four Cs + ions per large cavity are found nearly opposite 4-rings rather than opposite 6-rings as is usually seen. The hydroxide ion is presumed to be between the two Cs + ions found in each sodalite cavity.

Adsorption and Mössbauer studies of partially dehydrated FeCaA zeolites

AbstractThe physicochemical properties of the iron exchanged A‐type zeolites are affected by the degree of dehydration of the samples. Mössbauer and adsorption techniques were used to investigate the cation distributions in these zeolites. At lower degrees of hydration, a significant number of iron ions are located inside the sodalite cavities. A systematic study of the adsorption of probe gases, such as CH4, CO and CO2, was subsequently carried out and the results were correlated to the structural features of the dehydration.

Oxidation–reduction behaviour of highly dispersed ruthenium in RuNaY zeolite

The thermal decomposition of the [Ru(NH3)6]3+ complex ion exchanged in a NaY zeolite followed by reduction in H2 at 623 K leads to highly dispersed Ru metal in the zeolitic pore system. X-ray diffraction techniques have been used to identify atomically dispersed Ru0 inside the sodalite cavity at the site II′. This high dispersion sample can be produced either by heating under high vacuum conditions or by heating under hydrolysing conditions where an H2O+H2 mixture is present in the system. The Ru0 in the sodalite cavity is not stable under oxidation as it is irreversibly removed upon the addition of O2 at ambient temperature and cannot be regenerated by subsequent reduction in H2. Na+ ions within the zeolite always occupy sites I′ and II and are generally unaffected by the redox chemistry involving the ruthenium.