High resolution 29Si n.m.r. of dealuminated and ultrastable Y-zeolites

Engelhardt, G.; Lohse, U.; Samoson, Ago; Mägi, Μ.; Tarmak, M.; Lippmaa, É.

doi:10.1016/s0144-2449(82)80042-0

Cited by 175 publications

(89 citation statements)

References 8 publications

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“…When the spectrum was run with cross-polarization from 1 H, only the signal at d ‫מ‬ 103 was enhanced (Figure 1b). This signal therefore is a composite of that from (SiO) 3 Si-O-Al and that from (SiO) 3 Si-OH, in agreement with the literature [17]. The spectra were deconvoluted in terms of gaussian peak shapes and the areas of the individual deconvoluted peaks were used to calculate the ratio of tetrahedral Si and Al in the zeolite framework from the formula…”

Section: Characterization Of the Zeolite Y Bysupporting

confidence: 78%

Reaction of the hydroxy groups of zeolites with phosphorylating agents

et al. 1998

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Section: Characterization Of the Zeolite Y Bysupporting

confidence: 78%

Reaction of the hydroxy groups of zeolites with phosphorylating agents

et al. 1998

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“…-95 to -105 ppm) are in the same range as those for Si(3Si,OH) units (ca. -lOO to -lO3 ppm) [213] . [184,213) In the same manner as described for 29Si MAS NMR spectroscopy on aluminosilicate-type zeolites, the chemical composition of zincosilicates and of the gallium analogue of ZSM-5 (Ga-MFI) can be determined.…”

Section: Two-dimensional Nmr Spedroscopymentioning

confidence: 99%

“…-lOO to -lO3 ppm) [213] . [184,213) In the same manner as described for 29Si MAS NMR spectroscopy on aluminosilicate-type zeolites, the chemical composition of zincosilicates and of the gallium analogue of ZSM-5 (Ga-MFI) can be determined. The 29Si MAS NMR spectra of zeolites VPI -7 and VPI -9, examined by Camblor and Davis [214], show signals of Si(lZn) and Si(2Zn) units at resonance positions between -88.5 ppm and -95.6 ppm and between -77.9 ppm and -81.0 ppm, respectively.…”

Section: Two-dimensional Nmr Spedroscopymentioning

confidence: 99%

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

Karge¹,

Hunger²,

Beyer³

1999

Catalysis and Zeolites

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“…When performing cluster calculations it seems absolutely necessary to take into account the proper electric field connected with the real structure of the solid. The major role of the overall structure in stabilizing ^)A1-O-Al^ pairings in aluminosilicate lattices is demonstrated by the striking difference found between the A-and X-type zeolites both having a Si/Al ratio of 1.0: yAl-O-Al^ pairings w r ere observed in the former [1] but not in the latter case [19].…”

mentioning

confidence: 99%

Relative Stability of ᗒAl—O—Al ᗕ Linkages in Zeolites. A Nonempirical Molecular Orbital Study

Sauer¹,

Engelhardt²

1982

Zeitschrift Für Naturforschung A

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Nonempirical quantum chemical ST0-3G calculations were performed for cluster models of two oxygen-bridged T04 tetrahedra (T = Si, Al). The models are based on [(H0)3T0T(0H)3]"-structures and, in case of Al-containing models (n = 1,2), their electric neutrality is ensured by adding positive point charges.The calculations suggest the occurrence of X4.I -O -Al^ pairings provided certain electric fields act at the corresponding sites. In what follow s we report on nonempirical quantum chemical calculations on the energetics of equilibriawhere M, M', and M" denote appropriate molecular cluster models for two oxygen-bridged TO4 tetra- (1) are not explicitly considered-therein. Thus, complementary information may emerge from both studies. For treating homodesmic reactions such as equilibrium (1) the Hartree-Fock level of quantum chemistry is generally accepted. Although the use of a basis set of "double zeta plus polarization" quality would be desirable, the size of the models specified below confines us to minimum or near minimum basis sets. Actually all calculations were made by means of the ST0-3G method [9].As in previous studies [7,8,10], the models M, M', and M" are primarily represented by the molecular clusters

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High resolution 29Si n.m.r. of dealuminated and ultrastable Y-zeolites

Cited by 175 publications

References 8 publications

Reaction of the hydroxy groups of zeolites with phosphorylating agents

Reaction of the hydroxy groups of zeolites with phosphorylating agents

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

Relative Stability of ᗒAl—O—Al ᗕ Linkages in Zeolites. A Nonempirical Molecular Orbital Study

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