Structure of the new zeolite theta-1 determined from X-ray powder data

Highcock, Rona M.; Smith, G. W.; Wood, D. H.

doi:10.1107/s0108270185007892

Cited by 20 publications

(17 citation statements)

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“…The commercial (c-ZSM-22) and in house prepared (m-ZSM-22) zeolites have Si/Al ratios of 49 and 38, respectively, which are within the optimal Si/Al ratio found for mesopore generation for MFI zeolites [19,24,29]. Both samples consist of a highly crystalline ZSM-22 structure [50][51][52][53], as indicated by the diffractograms shown in Fig. S1.…”

Section: Parent Materials Descriptionsupporting

confidence: 54%

“…The TON topology is characterized by a pore structure of non-intersecting 5.7 x 4.6 Å 10-member ring channels and crystallizes preferentially as needles, with the micropore channels running in the direction of the needles [49][50][51][52][53]. Zeolites having the TON topology (ZSM-22, NU-10, Theta-1) are certainly strongly affected by diffusion limitations.…”

Section: Introductionmentioning

confidence: 99%

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Influence of post-synthetic modifications on the composition, acidity and textural properties of ZSM-22 zeolite

et al. 2018

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In this work, an extensive investigation of the preparation of a large body of desilicated ZSM-22 zeolites and their basic characterization is presented. We investigate the effects of the properties of the starting zeolite, and we employ mixtures of NaOH with CTAB or TBAOH as well as subsequent acid washings to create mesoporous zeolites. Scanning and transmission microscopy and nitrogen adsorption revealed that the crystal morphology of the starting zeolite appears to be the dominant parameter which influences the mesopore generation. Mesopores were effectively created within the rodlike commercial crystallites, whereas the thinner dimensions of the needle-shaped particles of the in house prepared zeolite represent an obstacle for an intra-mesopore creation. The alkaline, surfactant-assisted or combined NaOH/TBAOH desilication methods resulted in mesopores with different shape and size from the commercial 2 zeolite. The sequential acid washing generally resulted in increased the micropore volume with respect to the desilicated samples. Elemental analysis showed that extraframework Al species were generated upon the desilication treatments, which are eventually removed by the acid treatment. The acidity studied by FTIR demonstrated that this occurs without a marked modification of the Brønsted acidity, whereas the concentration of surface silanol hydroxyl groups is increased. The comparison between the total Al concentration and the amount of Al in acidic sites shows that the acidity was recovered after the acid washing and suggests that original non-acidic Al species in the starting materials may have a role in the formation of both Lewis and extra-framework species upon desilication.

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Section: Parent Materials Descriptionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Influence of post-synthetic modifications on the composition, acidity and textural properties of ZSM-22 zeolite

et al. 2018

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“…Our results are in agreement, within 0.1-0-15 A, with the structure as illustrated in the c-axis projection by Highcock, Smith & Wood (1985), but indicate substantial revision of some of the z coordinates, Si(3) and Si (4) …”

Section: Results Comparison With Powder Diffraction Studysupporting

confidence: 79%

Structure of α-trans-cinnamic acid. Addendum

Wierda¹,

Feng²,

Barron³

1990

Acta Crystallogr C

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An addendum [Wierda, Feng & Barron (1989). Acta Cryst. C45, 838] of a recent report of a determination of the structure of the title compound [Wierda, Feng & Barron (1989). Acta Cryst. CA5,[338][339]] drew attention to a reference * To whom correspondence should be addressed.0108-2701/90/010173-01 $03.00 [Bryan & Freyberg (1975). J. Chem. Soc. Perkin Trans. 2, pp. 1835-1840 overlooked by the authors in their original report. The addendum failed to make clear that this reference contained a report of a complete room-temperature determination of the crystal structure in question. The two structures are in good agreement, except for variations attributed to differences in temperature.All relevant information is contained in the Abstract.

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“…They differ from the profile-fitting method in the manner in which the contribution of instrumental and spectral factors to the integrated peak intensities are taken into account and are known as "trial-anderror" methods. The profile-fitting method and the related "trial-and-error" procedures have been successfully used to determine the crystal structure of some zeolites, e.g., Theta-1 [447] and, as a straight classical example, ZSM-S [448]. However, in most cases these methods were applied for the determination of lattice positions of cations and their occupancy by different cations.…”

Section: Profile-fitting Methodsmentioning

confidence: 99%