Phase selectivity in the syntheses of cage-based zeolite structures: An investigation of thermodynamic interactions between zeolite hosts and structure directing agents by molecular modeling

Burton, Allen W.; Lee, Greg S.; Zones, Stacey I.

doi:10.1016/j.micromeso.2005.11.022

Cited by 103 publications

(125 citation statements)

References 35 publications

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“…Additionally, since the syntheses of ECNU‐16 and IM‐16 were carried out under similar conditions, involving relative low water content (H 2 O/Si=10), the difference of the influence of solvent water on two crystal growth processes was expected to be minor. It might be reasonable, because the water/OSDA interaction should be minor compared to the OSDA/zeolite interaction . Therefore, a detailed computational study based on the molecular mechanics simulations was carried out to reveal the different structure‐directing effects observed for the “dimer” 4BI and the “monomer” 1E3MI.…”

Section: Figuresupporting

confidence: 67%

“…In another viewpoint, it is reasonable to speculate that the energy difference is not as sensitive for the smaller 1E3MI molecule as for the bulkier 4BI molecule to adjust the conformation inside the host channels. Thus, the 1E3MI has more rotation freedom since the activation barrier may be easily overcome by the thermal energy, whereas the 4BI has limited opportunity to rotate due to the large energetic barriers . This observation provides the evidence to the previous hypothesis that the entropy of the OSDA also has influence on zeolite phase selectivity under specific conditions …”

Section: Figurementioning

confidence: 99%

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Crystallization of a Novel Germanosilicate ECNU‐16 Provides Insights into the Space‐Filling Effect on Zeolite Crystal Symmetry

Zhang

et al. 2018

Chemistry A European J

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Synthesis of new zeolites involving organic molecules relies heavily on the trial-and-error approach, because it is difficult to interpret the determining effects of organics on zeolite crystal symmetry. Here, the intrinsic relationships among the space-filling of organics, included volume of channels, and zeolite crystal symmetry, are systematically demonstrated by experimental and computational means. Under controlled conditions, the "dimer" and "monomer" organics of 1-ethyl-3-methylimidazolium selectively direct different, but related, germanosilicates, the ECNU-16 with a new topology and the existing IM-16 with the UOS topology, respectively. The comprehensive computational study reveals that the zeolite phase selectivity is determined by the unique space-filling behavior of the "dimer" and "monomer" organics, which is closely correlated to their rotation freedom, as well as the included volume of host zeolite channels. The elucidation of this crucial space-filling effect from the fundamental viewpoint will provide new guidelines for the rational design and synthesis of new zeolites in future.

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Section: Figuresupporting

confidence: 67%

Section: Figurementioning

confidence: 99%

Crystallization of a Novel Germanosilicate ECNU‐16 Provides Insights into the Space‐Filling Effect on Zeolite Crystal Symmetry

Zhang

et al. 2018

Chemistry A European J

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“…Therefore this pair is ideal for comparisons of zeolite phase selectivity based solely upon framework -SDA interactions. We recently have performed energy optimization calculations for piperidine derivatives and polycyclic quaternary ammonium compounds occluded within the AEI and CHA frameworks [26]. These calculations show excellent agreement between the energetically preferred framework and the observed zeolite product.…”

Section: Effect Of Sda Size and Shapementioning

confidence: 90%

“…Recently we have compared phase selectivity with the results of molecular modeling calculations in the synthesis of cage-based zeolite structures from gels with varying aluminum content [26]. This work examines the stabilization of pure silica frameworks through van der Waals contacts with SDA molecules.…”

Section: Combined Influence Of Framework Energy and Sda/ Framework Inmentioning

confidence: 99%

The chemistry of phase selectivity in the synthesis of high-silica zeolites

Burton

Zones

Elomari

2005

Current Opinion in Colloid & Interface Science

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122

109

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“…3 These transitions could be relevant to the phase selectivity, which is a fundamental question, but still not well understood presently. [34][35][36] The pH values of mother liquids with different times showed that the phase transformation occurred under strong basic conditions (Table 3). At the early crystallization stage of t e 1.5 h, the pH value of mother liquid was lowered down to about 11.10, as compared with the initial value of 12.23.…”

Section: Mechanism Investigation Of Phase Transformationmentioning

confidence: 99%

Phase-Transformation Synthesis of SAPO-34 and a Novel SAPO Molecular Sieve with RHO Framework Type from a SAPO-5 Precursor

Tian

Wang

et al. 2011

Chem. Mater.

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SAPO-34 and a novel SAPO molecular sieve with the RHO framework (designated as DNL-6) were synthesized using SAPO-5 (the denser phase) as the precursor and diethylamine (DEA) as the template. The entire transition process had been investigated by XRD, SEM, XRF, and NMR spectroscopy, which clearly revealed a solution-mediated transport mechanism attributed to the transformation from SAPO-5 precursor to SAPO-34 via oscillating phases [SAPO-5 (FD = 16.9 T/nm 3 ) => SAPO-34 (15.1) þ DNL-6 (14.5) f DNL-6 f SAPO-34]. The initially formed SAPO-34 was different from the final one in this transformation due to very different percentages of organic inclusions, indicating that the host-guest interactions played important roles for the phase selectivity during the synthesis. DNL-6, obtained as an intermediate of the transformation process, possessed good thermal stability, large microporous surface area (724 m 2 /g), and high micropore volume (0.36 cm 3 /g). Rietveld refinement showed that the framework of calcined DNL-6 had typical features of the RHO structure with a high symmetry [I23, a = 15.08429(9) Å], composed of a body-centered cubic arrangement of R cages linked via double 8-rings.

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Phase selectivity in the syntheses of cage-based zeolite structures: An investigation of thermodynamic interactions between zeolite hosts and structure directing agents by molecular modeling

Cited by 103 publications

References 35 publications

Crystallization of a Novel Germanosilicate ECNU‐16 Provides Insights into the Space‐Filling Effect on Zeolite Crystal Symmetry

Crystallization of a Novel Germanosilicate ECNU‐16 Provides Insights into the Space‐Filling Effect on Zeolite Crystal Symmetry

The chemistry of phase selectivity in the synthesis of high-silica zeolites

Phase-Transformation Synthesis of SAPO-34 and a Novel SAPO Molecular Sieve with RHO Framework Type from a SAPO-5 Precursor

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