Synthetic Zeolites: Growth of Larger Single Crystals

Ciric, Julius

doi:10.1126/science.155.3763.689

Cited by 27 publications

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“…The latter problem is important for understanding the zeolite crystallization process as well as for providing specimens which are needed urgently for many aspects of zeolite research-e.g., x-ray crystal structure studies and other physical measurements. Table II The growth of zeolite X single crystals was reported by Ciric (30) and more recently in an interesting approach using nonaqueous solvents by Charnell (26), the latter resulting in 100-micron crystals of zeolite X.…”

Section: Some Recent Important Achievements In Zeolite Researchmentioning

confidence: 91%

Recent Advances in Zeolite Science

Breck¹

1974

Molecular Sieve Zeolites-I

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Zeolite properties are being studied by nearly every type of modern scientific discipline, and they are being utilized in many new chemical engineering processes. Important ad vances include detailed basic information on cations in zeo lites, more understanding of the mechanism of zeolite formation, the formation and character of structural defects and hydroxyl groups, the role of zeolite structure in adsorp tion and catalysis, and the increasing technology of the use of molecular sieve zeolites in catalysis and adsorption. 'Tihe discovery of synthetic crystalline zeolites has resulted in wide scientific interest and a great variety of applications in industry. The growth of scientific interest in zeolites may be measured by the increase in the number of related publications. From the early research on zeolite minerals in 1909 until 1969, over 4500 papers have been published in the open literature. The extensive interest is evidenced equally by over 1000 patents which have been issued in the United States alone. The funda mental properties and applications of molecular sieve zeolites involve many scientific disciplines and cross many of the traditional boundaries. Fields involved are inorganic and physical chemistry with emphasis on surface and colloid chemistry and catalysis, biochemistry, the geological sciences of geochemistry, geology, mineralogy, and physics, including crystallography, spectroscopy, and solid state physics. Applications in the engineering sciences include adsorption separa tions, hydrocarbon catalysis, and purifications. The molecular sieve zeo lites possess many unique properties which have resulted in their use in a great variety of applications such as hydrocarbon conversion catalysts, recovering radioactive ions from waste solutions, separating hydrogen isotopes, solubilizing enzymes, carrying active catalysts in the curing of plastics and rubber, transporting soil nutrients in fertilizers, and even filtering tars from cigarette smoke. Minato has presented an interesting review on industrial uses for mineral zeolites in Japan (65). Relatively 1 Downloaded by UNIV OF NEW ORLEANS on December 9, 2014 |

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Section: Some Recent Important Achievements In Zeolite Researchmentioning

confidence: 91%

Recent Advances in Zeolite Science

Breck¹

1974

Molecular Sieve Zeolites-I

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“…Two techniques are commonly adopted: namely, either the diffusion of one or more reactants into a preformed silica gel or the mixing of all components prior to gel formation. Both methods were explored in the 1960s and 1970s for the ambient-temperature growth of large single crystals of sodium-containing zeolites, − but neither has yet been investigated for the synthesis of organically templated framework materials. We here report the synthesis of four organically templated layered aluminum and gallium phosphates: (C 5 NH 6 )[Al(HPO 4 ) 2 (H 2 O) 2 ] (I), (C 5 NH 6 )[Ga(HPO 4 ) 2 (H 2 O) 2 ] (II), (C 3 N 2 H 5 )[Al(HPO 4 ) 2 (H 2 O) 2 ] (III) and (C 3 N 2 H 5 )[Ga(HPO 4 ) 2 (H 2 O) 2 ] (IV).…”

Section: Introductionmentioning

confidence: 99%

Ambient-Temperature Synthesis of New Layered AlPOs and GaPOs in Silica Gels

et al. 1998

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A method for synthesising open-framework phosphates under less-severe conditions than those employed in conventional solvothermal processes is described. Two new layered aluminum phosphates containing pyridine and imidazole templates and their gallium analogues have been grown in silica gel at room temperature, and the structures determined by single-crystal X-ray diffraction. Crystal data: general formula (C5NH6)[M(HPO4)2(H2O)2], triclinic, space group P1̄, lattice parameters a = 6.994(1), b = 7.2208(7), c = 12.114(1) Å, α = 105.080(8), β = 104.85(1), γ = 90.39(1)° when M = Al; a = 7.056(1), b = 7.315(1), c = 12.165(1) Å, α = 105.32(1), β = 105.49(1), γ = 90.25(1)° when M = Ga. General formula (C3N2H5)[M(HPO4)2(H2O)2], monoclinic, space group C2/c, a = 21.893(1), b = 7.1830(3), c = 6.9890(5) Å, β = 104.164(5)° when M = Al; a = 22.002(2), b = 7.262(1), c = 7.047(1) Å, β = 105.11(1)° when M = Ga. The four structures are closely related and contain MO6 (M = Al, Ga) and PO4 polyhedra linked to form corrugated layers. The pyridinium or imidazolium cations occupy sites between these layers and are linked through hydrogen bonding to one or two adjacent layers, respectively.

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“…J. CIRIC (Mobil Research and Development Corporation) kindly supplied us with a relatively large cr\-stal of Na-P 1 which was grown in acrylic acid gel (CIRIC, 1967). The crystal had an irregular shape with individual segments standing out, indicating that it was multiply twinned.…”

Section: Introductionmentioning

confidence: 99%

The crystal structure of synthetic zeolite Na-P 1, an isotype of gismondine

Baerlocher¹,

MEIER²

1972

Zeitschrift Für Kristallographie - Crystalline Materials

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AuszugDie Kristallstruktur des synthetischen Zeoliths Na-P 1 ("kubisches" Ρ) basiert auf dem Gismondin-Gerüst mit der Maximalsvmmetrie Ii\¡amd. Die Strukturanalyse wurde mangels Einkristalldaten mittels genauer Intensitäts-werte eines mehrfach verzwillingten Kristalls durchgeführt. Für die Gitterkonstanten wurden a = c = 10,04 Â gefunden; die Intensitäten ließen jedoch eindeutig eine Abweichung von kubischer Symmetrie erkennen. Schwache 6-Reflexe, für welche h -k + l = 2η + 1, wurden ebenfalls festgestellt, sind jedoch in der vorliegenden Arbeit nicht berücksichtigt worden. Die Struktur konnte unter Annahme der Raumgruppe Ii auf einen R(I)-Wert von 0,077 verfeinert werden. Die wahre Symmetrie der Struktur muß niedriger sein, wobei ausgeprägte Pseudosymmetrie in Erscheinung tritt.Präparate von Na-P 1 dürften fast ausnahmslos submikroskopisch verzwillingt sein. Die Zwillingsbildung wird durch die Topologie und die außer-ordentliche Flexibilität des Gerüstes begünstigt. Die große Flexibilität des Zeolithgerüstes spiegelt sich in den auffallenden Unterschieden in den Gitterkonstanten der bekannten gismondinartigen Strukturen, und das Auftreten scheinbar verschiedener P-Phasen läßt sich damit erklären. AbstractThe crystal structure of synthetic zeolite Na-P 1 (or Bi) has been solved using x-ray data obtained from a multiply twinned crystal. The structure is shown to be based on a gismondine-type framework with maximum possible symmetry IAi/amd.The cell dimensions were found to be α = c = 10.04 Â but the intensity data clearly indicated noncubic symmetry. Weak b reflections with h + k + I = 2/1+1 have also been recorded but were not used in this investigation. Refinement assuming space group 14 proceeded to an intensity R value of 0.077. The true symmetry must be lower and the structure appears to be highly pseudosymmetrie.The typical sphorulitic aggregates (if most Xa-P 1 preparations are thought to be Kiibmicroscopically twinned. The formation of twins is favoured by the topology and the extraordinary flexibility of the framework. Its flexibility also explains the comparatively large variations in cell dimensions and apparent symmetry of known gismondine isotypes, and could account for the occurrence of various Ρ phases.

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Synthetic Zeolites: Growth of Larger Single Crystals

Abstract: Synthetic zeolites 4A, P, and X were grown in acrylic gel to a size suitable for study of single crystals by x-ray diffraction.

Cited by 27 publications

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Recent Advances in Zeolite Science

Recent Advances in Zeolite Science

Ambient-Temperature Synthesis of New Layered AlPOs and GaPOs in Silica Gels

The crystal structure of synthetic zeolite Na-P 1, an isotype of gismondine

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