A high-resolution solid-state29 Si n.m.r. study of ZSM—5 type zeolites

Boxhoorn, G.; Kortbeek, A.G.T.G.; Hays, Gary R.; Alma, N.C.M.

doi:10.1016/0144-2449(84)90066-6

Cited by 69 publications

(17 citation statements)

References 16 publications

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“…The positions of the Q3 peaks in magadiite and octosilicate are similar to that of the Q3 peak reported by Boxhorn et al (1984) for ZSM-5. As shown above, the intensity of this peak decreased on heating the samples to about 250~ in excellent agreement with the behavior of ZSM-5 (Boxhorn et al, 1984).…”

Section: Clays and Clay Mineralssupporting

confidence: 70%

“…As shown above, the intensity of this peak decreased on heating the samples to about 250~ in excellent agreement with the behavior of ZSM-5 (Boxhorn et al, 1984). Likewise, the location of the Q4 signal for these layered solids is within the range observed in the NMR spectra of samples of silicalite and 5-member ring zeolites (Klinowski, 1984).…”

Section: Clays and Clay Mineralssupporting

confidence: 65%

“…Recent IR and NMR evidence has suggested the presence of intemal Si-OH groups in samples of highly siliceous ZSM-5 (Woolery et al, 1986;Boxhorn et al, 1984;Brtmner, 1987). If zeolite-like domains exist in magadiite as postulated above, the presence of internal silanol groups in siliceous zeolites may possibly be tak- The a-and b-axis projections of the idealized structure of ZSM-5 (Kokotailo et al, 1978) and the c-axis projection of mordenite (Meier, 1974) are shown in Figure 7.…”

Section: Proposed Structurementioning

confidence: 99%

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Hypothetical Structures of Magadiite and Sodium Octosilicate and Structural Relationships Between the Layered Alkali Metal Silicates and the Mordenite- and Pentasil-Group Zeolites

Garcés

1988

Clays and clay miner.

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Abstract--Hypothetical model structures for magadiite and sodium octosilicate, based on the structure of the zeolite dachiardite, are proposed that consist of layers of 6-member tings of tetrahedra and blocks containing 5-member rings attached to both sides of the layers. The infrared (IR) and nuclear magnetic resonance spectra of magadiite and sodium octosilicate have features in common with spectra of zeolites in the ZSM-5 and mordenite groups. A peak at 1225 cm l in the IR spectra of magadiite and sodium octosilicate is characteristic of zeolites containing 5-member rings, such as ZSM-5-and mordenite-type zeolites. The defect structures of pentasil zeolites may therefore be akin to layered alkali metal silicates containing zeolite-like domains, in which part of the silanol groups from adjacent silicate layers are condensed (cross-linked) forming siloxane linkages.

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Section: Clays and Clay Mineralssupporting

confidence: 70%

Section: Clays and Clay Mineralssupporting

confidence: 65%

Section: Proposed Structurementioning

confidence: 99%

See 1 more Smart Citation

Hypothetical Structures of Magadiite and Sodium Octosilicate and Structural Relationships Between the Layered Alkali Metal Silicates and the Mordenite- and Pentasil-Group Zeolites

Garcés

1988

Clays and clay miner.

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“…This finding is in broad agreement with reported results from MAS NMR studies. Several authors 4,5, 33 have found that the 29 Si NMR signal corresponding to silanols in H-ZSM-5 samples is much greater (by at least one order of magnitude) than the value obtained from a calculation of the concentration of SiOH groups at the crystal faces. Although these calculations involve some degree of approximation regarding the morphology of the zeolite crystals and the value obtained depends also on the crystal size (about 1 µm in the reported NMR studies), the fact remains that internal silanols are much more abundant than is often assumed.…”

Section: Characterization By Fourier-transform Ir Spectroscopy: O᎐h Smentioning

confidence: 87%

Zeolite-supported metal carbonyls: sensitive probes for infrared spectroscopic characterization of the zeolite surface

Areán¹,

Palomino²,

Platero³

et al. 1997

J. Chem. Soc., Dalton Trans.

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The metal carbonyls [M(CO) 6 ] (M = Mo or W) were found to be molecularly adsorbed on the surface of H-ZSM-5 zeolite crystals. Three types of adsorbed species were detected by IR spectroscopy: weakly physisorbed metal carbonyls and [M(CO) 6 ] molecules interacting (via a CO ligand) with OH groups or with Lewis-acid sites (co-ordinatively unsaturated Al 3+ ions). For physisorbed species a single C᎐O stretching mode (T 1u ) was observed, around 1990 cm Ϫ1 . The (OC) 5 MCO ؒ ؒ ؒ HOSi species gave a band at 1965 cm Ϫ1 (anchored CO ligand) and the corresponding E + 2A 1 modes at higher frequency. O-Bonding between the metal hexacarbonyls and Lewis-acid centres gives rise to a characteristic IR absorption band in the range 1750-1850 cm Ϫ1 , and corresponding E + 2A 1 modes at ν˜C O > 2000 cm Ϫ1 . Close inspection of these spectroscopic features, and comparison with IR spectra of adsorbed CO, enables characterization of the zeolite surface. For medium-pore zeolites an important feature of this method is that [M(CO) 6 ] molecules cannot penetrate inside the zeolite channels, therefore discrimination between internal and external surface sites can be accomplished. Thus, it was found that both Brønsted-acid sites [bridged Si(OH)Al groups] and silanols are located mainly inside the zeolite channels.

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“…An ideal channel structure is depicted in Figure 1 e. However, it has been demonstrated that SL-1 contains many defects when produced from a basic gel-containing structure-directing agent. [30][31][32] The most common defect is the Si absence, giving rise to creation of internal hydroxyl groups (Figure 1 f). The channels become hydrophilic, thereby blocking the passage of HC-n molecules with long hydrophobic alkyl chains.…”

Section: Tung Cao Thanh Pham Hyun Sung Kim and Kyung Byung Yoon*mentioning

confidence: 99%

Large Increase in the Second‐Order Nonlinear Optical Activity of a Hemicyanine‐Incorporating Zeolite Film

2013

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A second-order nonlinear optical (2NLO) material generates a second harmonic (2w) from an incident laser beam with the frequency of w and shows electro-optic properties. 2NLO materials are currently widely used as key materials for optical communication, optical switching, laser components, IR detectors for medical and military applications, and so on. Although some 2NLO materials are commercially available, their tensor components of the quadratic NLO susceptibilities (d mn ) are not high enough to be used in miniature integrated photonic devices. Therefore, the search for 2NLO materials with exceptionally high activities has to be continued not only to enhance their functions in current applications but also to help expedite the materialization of photonics in which photons instead of electrons are used for signal processing, transmission, and storage.The general approach has been to organize the molecules with large second-order hyperpolarizability (b) values into 2NLO materials. The first methodology has been noncentrosymmetric crystallization of 2NLO molecules. [1,2] However, this methodology has been of limited success. The second methodology has been orientation-controlled layerby-layer deposition of 2NLO molecules on substrates. [3][4][5][6][7][8][9] However, the procedures are highly time-consuming, and the obtained materials bear no practical applicability arising from their poor mechanical and thermal stabilities. The third methodology has been random incorporation of dipolar molecules into polymer matrices followed by subsequent electric field-assisted forced alignment of the molecules into a uniform direction, a process often called poling. [10][11][12][13][14] This methodology can also be named as a host-guest composite formation methodology, where a polymer is serving as a flexible organic host. However, the gradual orientation relaxation of the 2NLO molecules into the original random orientations under the application conditions or often called depoling has been a serious problem.To overcome such problems associated with depoling, orientation-controlled insertion of 2NLO molecules into rigid inorganic hosts has received great attention. Thus Stucky, [15,16] Marlow, [17,18] Caro, [17][18][19] and Qiu, [20] and others started testing zeolites as the rigid hosts. The tested zeolites were AlPO 4 -5, [15][16][17]19] silicalite-1, [18,20] ZSM-5, [18,19] and others. [21,22] The studied 2NLO molecules were para-nitroaniline and the related molecules. [17][18][19][20][21] Through these works, the potential of zeolites as versatile rigid inorganic hosts for preparation of practically viable inorganic-organic host-guest second-harmonic generating materials was demonstrated. However, the employed zeolite hosts were limited to powders and small single crystals that bear limited practical applicability. Furthermore, the b values of the tested 2NLO molecules were low (about 35 10 À30 esu at 1064 nm). [23,24] Therefore, to develop commercially viable zeolite-molecule host-guest 2NLO materials, methods to grow tr...

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A high-resolution solid-state29 Si n.m.r. study of ZSM—5 type zeolites

Cited by 69 publications

References 16 publications

Hypothetical Structures of Magadiite and Sodium Octosilicate and Structural Relationships Between the Layered Alkali Metal Silicates and the Mordenite- and Pentasil-Group Zeolites

Hypothetical Structures of Magadiite and Sodium Octosilicate and Structural Relationships Between the Layered Alkali Metal Silicates and the Mordenite- and Pentasil-Group Zeolites

Zeolite-supported metal carbonyls: sensitive probes for infrared spectroscopic characterization of the zeolite surface

Large Increase in the Second‐Order Nonlinear Optical Activity of a Hemicyanine‐Incorporating Zeolite Film

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