The synthesis of discrete colloidal particles of TPA-silicalite-1

Persson, A.E.; Schoeman, Brian J.; Sterte, Johan; Otterstedt, Jan-Erik

doi:10.1016/0144-2449(94)90191-0

Cited by 433 publications

(267 citation statements)

References 11 publications

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“…When comparing growth rates, one has to keep in mind that these are strongly dependent on factors like the chemical composition of the synthesis mixture, the temperature, aging histories, and agitation or stirring. Therefore, even when taking into account the differences in reaction temperature by an Arrhenius relationship with an activation energy for crystal growth of 50 kJ/mol (approximate average of values reported in literature 44,14 ), faster 45 as well as slower 15 growth rates can be found. In agreement with light scattering results of Persson et al 15 we found the growth rate to be about the same for synthesis mixtures of varying alkalinity.…”

Section: Saxs/waxs and Usaxs Resultsmentioning

confidence: 99%

“…14,15 A disadvantage of visible light scattering for our system is that it cannot be used for turbid samples, and, in the case of an aggregating system, the size of the individual particles cannot be determined. Therefore it can only be used ex situ at advanced stages of the crystallization process by diluting the samples and cannot be used for samples in which a heterogeneous gel phase is formed.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Investigation of Si-TPA-MFI Crystallization Using (Ultra-) Small- and Wide-Angle X-ray Scattering

et al. 1997

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The formation of precursors and the growth and aggregation of silicalite-1 crystals using tetrapropylammonium as a template (Si-TPA-MFI) has been studied in situ using X-ray scattering techniques. Simultaneous smallangle and wide-angle X-ray scattering (respectively SAXS and WAXS) experiments using synchrotron light showed that the formation of amorphous colloidal aggregates in water clear synthesis mixtures was dependent on the alkalinity of the solutions. In situ time-resolved ultra-small-angle X-ray scattering (USAXS) showed the form factor oscillations of the growing crystals. Fitting of the USAXS patterns to the scattering pattern of spherical particles having a normal particle size distribution showed a linear growth of the average crystal diameter, which was approximately the same for both alkalinities studied. The final size of the crystals was highest for the synthesis mixture having the highest alkalinity, which can be explained in terms of number of viable nuclei formed. At the end of the linear growth the crystals form aggregates corresponding with a diffusion limited aggregation process (mass fractal dimension of 1.8).

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Section: Saxs/waxs and Usaxs Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In Situ Investigation of Si-TPA-MFI Crystallization Using (Ultra-) Small- and Wide-Angle X-ray Scattering

et al. 1997

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“…So far these reactions have only been studied for severely diffusion limited MFI-and MEL-type zeolite crystals. Very small MFI-type crystals have become available, [523][524][525][526] that should afford redoing the experiments with minimal mass transfer limitations and establishing to what extent mass transport effects interfere with pure transition state shape selectivity. Interestingly, the explanation for the difference in product slate between MFI-and MEL-type zeolites does not necessarily involve transition state shape selectivity.…”

Section: Transition State Selectivitymentioning

confidence: 99%

Molecular Simulations of Zeolites: Adsorption, Diffusion, and Shape Selectivity

2008

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“…These are typically lumped together in agglomerates or even intergrowths which resist to a complete breakdown to single crystals. Thanks to the pioneering work by Verduijn [3][4][5][6] and by Schoeman and coworkers [7][8][9], it is also possible to prepare zeolites consisting of single crystals with diameters around 100 nm or less. These syntheses produce colloidal sols of zeolites in uniform crystals sizes and have been developed for the preparation of zeolite films and membranes.…”

Section: Introductionmentioning

confidence: 99%

“…The preparation methods for colloidal zeolites as described by Verduijn and by Schoeman and Sterte are identical to a large extent, and they are applicable to the structure types FAU, LTA, SOD [7], MFI [3,4,[7][8][9], MEL [3,4], OFF [4,5], LTL [4,6] and BEA [4]. The crystallisation is performed from clear solutions in open vessels at low temperature and ambient pressure.…”

Section: Introductionmentioning

confidence: 99%

Comparing synthesis routes to nano-crystalline zeolite ZSM-5

Reding

Maurer

Kraushaar‐Czarnetzki

2003

Microporous and Mesoporous Materials

104

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Aiming at the identification of a suitable synthesis route to zeolite ZSM-5 with acidic properties and crystal diameters of about 100 nm or less, we have evaluated four different preparation methods. Three of these have been adopted from the literature, and one was developed by ourselves. The products, all of which synthesised from mixtures with a fixed Si/Al ratio of 60, were inspected by means of X-ray diffraction, scanning electron microscopy, laser-Doppler anemometry and temperature-programmed desorption of ammonia. Two methods turned out to be successful and well reproducible. The first one comprises hydrothermal crystallisation from clear solutions under autogenous pressure and has been described previously by van Grieken et al. The other approach is based on the use of colloidal silicalite-1 seed crystals in an open-vessel crystallisation at atmospheric pressure. The crystal size distribution and the Si/Al ratio of the products can be well controlled. The products from both synthesis types could be transferred into the H-form by conventional means without causing collapse of the crystal structure.

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The synthesis of discrete colloidal particles of TPA-silicalite-1

Cited by 433 publications

References 11 publications

In Situ Investigation of Si-TPA-MFI Crystallization Using (Ultra-) Small- and Wide-Angle X-ray Scattering

In Situ Investigation of Si-TPA-MFI Crystallization Using (Ultra-) Small- and Wide-Angle X-ray Scattering

Molecular Simulations of Zeolites: Adsorption, Diffusion, and Shape Selectivity

Comparing synthesis routes to nano-crystalline zeolite ZSM-5

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