Open AccessJournal Article
The framework topology of zeolite beta
John B. Higgins,R.B. LaPierre,John L. Schlenker,A.C. Rohrman,J.D. Wood,G.T. Kerr,W.J. Rohrbaugh +6 more
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TLDR
The tetrahedral framework structure of zeolite beta is disordered along (001) planes as mentioned in this paper, and the disordered structure is related by a/3 and/or b/3 displacements on (1) planes to three ordered polytype structures with triclinic, monoclinic and tetragonal symmetry.Abstract:
The tetrahedral framework structure of zeolite beta is disordered along (001). The disordered structure is related by a/3 and/or b/3 displacements on (001) planes to three ordered polytype structures with triclinic, monoclinic, and tetragonal symmetry. Three mutually perpendicular 12-ring channel systems are characteristic of the three ordered polytypes and the disordered beta structure. The proposed framework structures are consistent with the known diffraction, sorption an cation exchange properties of zeolite beta.read more
Citations
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Characterizing the atomic structure in low concentrations of weakly ordered, weakly scattering materials using the pair distribution function
Abstract: Characterizing the atomic structure in low concentrations of weakly ordered, weakly scattering materials using the pair distribution function Maxwell W. Terban Nanoscale structural characterization is critical to understanding the physical underpinnings of properties and behavior in materials with technological applications. The work herein shows how the pair distribution function technique can be applied to x-ray total scattering data for material systems which weakly scatter x-rays, a typically difficult task due to the poor signal-to-noise obtained from the structures of interest. Characterization and structural modeling are demonstrated for a variety of molecular and porous systems, along with the detection and characterization of disordered, minority phases and components. In particular, reliable detection and quantitative analysis are demonstrated for nanocrystals of an active pharmaceutical ingredient suspended in dilute solution down to a concentration of 0.25 wt. %, giving a practical limit of detection for ordered nanoscale phases within a disordered matrix. Further work shows that minority nanocrystalline phases can be detected, fingerprinted, and modeled for mixed crystalline and amorphous systems of small molecules and polymers. The crystallization of amorphous lactose is followed under accelerated aging conditions. Melt quenching is shown to produce a different local structure than spray drying or freeze drying, along with increased resistance to crystallization. The initial phases which form in the spray dried formulation are identified as a mixture of polymorphs different from the final α-lactose monohydrate form. Hard domain formation in thermoplastic polyurethanes is also characterized as a function of methylene diphenyl diisocyanate and butanediol component ratio, showing that distinct and different hard phase structures can form and are solved by indexing with structures derived from molecular dynamics relaxation. In both cases, phase fractions can be quantified in the mixed crystalline and amorphous systems by fitting with both standards or structure models. Later chapters, demonstrate pair distribution function characterization of particle incorporation, structure, and synthesis of nanoporous materials. Nanoparticle size distributions are extracted from platinum nanoparticles nucleating within a zeolite matrix through structural modeling, and validated by transmission electron microscope studies. The structure of zirconium phosphonate-phosphate unconventional metal organic framework is determined to consist of turbostratically disordered nanocrystalline layers of Zr-phenylphosphonate, and the local environment of terbium intercalated between the layers is found to resemble the local environment in scheelite-type terbium phosphate. Finally, the early stages of reaction between aqueous zinc dinitrate hexahydrate and methanolic 2-methylimidazole are characterized using in situ total scattering measurements, showing that secondary building units of tetrahedrally coordinated by 2-methylimidazole initially form upon reaction. Overall, the methodologies are developed and applied toward phase detection, identification, solution, and behavior in pharmaceuticals, polymers, and nanoporous materials. Advice is given for carrying out experiments and analysis on such materials so that these techniques can be applied to other similar systems.
Book ChapterDOI
Zeolite structure determination using electron crystallography
Junliang Sun,Daliang Zhang,Zhanbing He,Sven Hovmöller,Xiaodong Zou,Fabian Gramm,Christian Baerlocher,Lynne B. McCusker,Avelino Corma,Manuel Moliner,María J. Díaz-Cabañas +10 more
TL;DR: In this paper, the structures of zeolite beta polymorph B and of IM-5 have been determined by combining selected area electron diffraction (SAED) patterns and high resolution transmission electron microscopy (HRTEM) images.
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Theoretical and Experimental Study on the 7‐Hydroxy‐4‐Methylcoumarin Synthesis with H‐Beta Zeolite
Sorasak Klinyod,Bundet Boekfa,Suwapich Pornsatitworakul,Thana Maihom,Nongpanga Jarussophon,Piti Treesukol,Chularat Wattanakit,Jumras Limtrakul +7 more
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Design of Organic Structure Directing Agents for Chiral Zeolite Beta A
Frits Daeyaert,Michael W. Deem +1 more
Dissertation
Transformation des alcools sur zéolithes protoniques : "rôle paradoxal du coke
TL;DR: In this article, the coke composition depends on the catalyst morphology: over HBEA(11) zeolite of large pores, 17 families were detected while 4 over HZSM-5(40) of intermediate pore size.
References
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Journal ArticleDOI
The crystal structure of mordenite (ptilolite)
TL;DR: Mordenite, a zeolite, was derived by superposition of the three-dimensional Patterson function and partially refined assuming the centric symmetry Cmcm or Cmc2t as discussed by the authors.
Journal ArticleDOI
The framework topology of ZSM-12: A high-silica zeolite
TL;DR: In this article, the structure of ZSM-12, a high-silica zeolite, was determined by analysis of electron and X-ray powder diffraction data combined with model building.
Journal ArticleDOI
The framework topology of ZSM-22: A high silica zeolite
TL;DR: ZSM-22 as discussed by the authors, an orthorhombic high silica zeolite (Cmcm, a = 13.86 ± 0.03A, b = 17.41± 0.04A, and c = 5.5 × 4.5 A), has a framework consisting of 5-, 6- and 10-rings.
Journal ArticleDOI
The framework topology of ZSM-48: A high silica zeolite
TL;DR: In this article, a disordered structure consisting of ferrierite sheets linked via bridging oxygens located on mirror planes is proposed for this material, characterized by ten-ring noninterpenetrating linear channels whose ideal dimensions are 5.3 × 5.6 A.
Journal ArticleDOI
The framework topology of ZSM-23: A high silica zeolite
A.C. Rohrman,R.B. LaPierre,J.L. Schlenker,J.D. Wood,Ernest W. Valyocsik,M.K. Rubin,J.B. Higgins,W.J. Rohrbaugh +7 more
TL;DR: ZSM-23 as discussed by the authors is a high-silica zeolite with lattice parameters of: a = 5.01 ± 0.02A, b = 21.52± 0.04A, and c = 11.13 ± 1.03A.