Synthesis and Characterization of Breck Structure Six, Faujasite, ZSM-3, and ZSM-20 and Their Structural Relationships

Skeels, G.W.; Blackwell, C. S.; Reuter, Kathleen B.; McGuire, N.K.; Bateman, Charles A.

doi:10.1016/b978-1-4832-8383-8.50048-9

Cited by 3 publications

(3 citation statements)

References 8 publications

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“…ZSM-20 (figure 4/) grows as pseudo-hexagonal platelets ). The platelets typically contain 50-100 layers, 50-70% of which are arranged to form emt intergrowths Skeels 1992;Skeels et al 1993). Platelets tend (a) to intergrow at angles of ~ 70° (as noted above, ECR-35 also contains such inter growths).…”

Section: Intergrowth Segregation In F a U -E M T Zeolite Materials 821mentioning

confidence: 97%

Intergrowth segregation in FAU-EMT zeolite materials

Treacy

Vaughan

Strohmaier

et al. 1996

Proc. R. Soc. Lond. A

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Intergrowths of cubic (fau) and hexagonal (em t) structural phases in a number of faujasite-related zeolite materials have been studied using transmission electron mi croscopy, and high-resolution powder X-ray diffraction. In Y, CSZ-1, CSZ-3, ZSM-2, ZSM-3, ZSM-20, ECR-35, ECR-30 and EMC-2 materials, the fau and emt com ponents segregate non-randomly into contiguous blocks. This segregation is most pronounced in ZSM-20 and ECR-35. ECR-30 and EMC-2 are both predominantly emt framework materials, within which fau intergrowths occur in clumps of 1, 2 or 3 layers. No evidence is found for extended superlattice ordering of intergrowths. Intergrowth segregation acts to reduce both the configurational entropy associated with the stacking statistics and the elastic energy associated with coherency strain. In tr o d u c tio nIt was first reported by Breck (1974) that the cubic faujasite (fau) framework could support recurrent twinning on 111 planes to produce a hexagonal framework struc ture. The hexagonal framework possesses straight 12-ring channels axially aligned along the six-fold axis, each channel being connected to its six neighbours through the 12-ring apertures of a secondary cage. It has been referred to in the literature as 'Breck structure 6' (bss)-in reference to Breck's list of six frameworks, including the faujasite framework fau, that can be generated by connecting sodalite cages (Breck 1974), and, erroneously, as 'hexagonal faujasite'. More recently, the Structure Com mission of the International Zeolite Association has assigned the framework code emt to the hexagonal polymorph, with material EMC-2 designated as the type species (Meier & Olson 1992; Newsam Sz Treacy 1993).Evidence for the existence of domains of the emt framework was originally limited to sightings of twin faults in fau framework materials. The framework in the vicinity of each twin plane would support cages that, locally, were topologically equivalent to those found in the emt framework. Audier et al. (1982) observed low densities of 111 twin planes in transmission electron micrographs of zeolite Y samples. In some materials, twin faults were observed to occur close to one another, suggestive of a superlattice structure (Audier et al. 1982). Kokotailo & Ciric (1976) reported a recurrently twinned ca. 7 nm superstructure in ZSM-3 materials based on selectedarea electron-diffraction data, implying that ZSM-3 contained ca. 20% of EMT-type cages.

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Section: Intergrowth Segregation In F a U -E M T Zeolite Materials 821mentioning

confidence: 97%

Intergrowth segregation in FAU-EMT zeolite materials

Treacy

Vaughan

Strohmaier

et al. 1996

Proc. R. Soc. Lond. A

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“…Methods to treat MFI samples using AHFS solutions were adapted and modified from the literature, 24,25,42–44 which are based on methods introduced by Skeels and Breck. 45,46 First, desired concentrations of AHFS and ammonium acetate solutions were prepared. In an example treatment for Zeolyst CBV2314, for a desired 1 : 1 molar ratio of Si (in AHFS) to Al (in zeolite), or Si AHFS /Al zeolite = 1, 0.24 g of AHFS (NH 4 SiF 6 ; Sigma Aldrich, 99.999%) was dissolved with deionized water (18.2 MΩ cm) in a 50 cm 3 polypropylene copolymer volumetric flask (Thermo Scientific Nalgene ASTM Class B) to obtain 50 cm 3 of 0.27 M AHFS solution [safety: in addition to basic lab PPE (goggles, gloves, lab coat), additional PPE (thicker gloves, face shield) and engineering controls ( e.g.…”

Section: Methodsmentioning

confidence: 99%

Quantification of extracrystalline acid sites in MFI zeolites after post-synthetic passivation treatments using mesitylene benzylation kinetics

Ezenwa,

Hopping,

Sauer

et al. 2024

React. Chem. Eng.

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“…Many researchers have found that dealumination reduced the amount of acid site per gram of zeolite, resulting in higher conversion of hydrocarbons . Most prevailing methods for dealumination include steaming or treatment in an acidic medium, or further silicification with either SiCl 4 or (NH 4 ) 2 SiF 6 …”

Section: Introductionmentioning

confidence: 99%

Synthesis of EMT Zeolite by a Steam-Assisted Crystallization Method Using Crown Ether as a Structure-Directing Agent

Matsukata

Kizu

Ogura

et al. 2001

Crystal Growth & Design

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A high-silica hexagonal faujasite EMT was crystallized by a steam-assisted crystallization (SAC) method using a crown ether of 1,4,7,10,13,16-hexaoxacyclooctadecane, 18-crown-6, as a structure-directing agent. The growth mechanism of EMT by SAC is quite different from that of EMT by the conventional hydrothermal synthetic method, in which layer-by-layer growth occurs. Another characteristic of SAC is that nanoparticles fuse and the surface of the dry gel is rearranged, resulting in a distinct hexagonal shape for the EMT crystals. Sodium content must be strictly defined when the SAC method is used, and the crystallization temperature must be kept below 408 K to keep the crown ether in the dry gel to obtain a pure phase of EMT.

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Synthesis and Characterization of Breck Structure Six, Faujasite, ZSM-3, and ZSM-20 and Their Structural Relationships

Cited by 3 publications

References 8 publications

Intergrowth segregation in FAU-EMT zeolite materials

Intergrowth segregation in FAU-EMT zeolite materials

Quantification of extracrystalline acid sites in MFI zeolites after post-synthetic passivation treatments using mesitylene benzylation kinetics

Synthesis of EMT Zeolite by a Steam-Assisted Crystallization Method Using Crown Ether as a Structure-Directing Agent

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