Aging effects on the nucleation and crystallization kinetics of colloidal TPA-silicalite-1

Li, Qinghua; Mihailova, Boriana; Creaser, Derek; Sterte, Johan

doi:10.1016/s1387-1811(00)00346-2

Cited by 131 publications

(72 citation statements)

References 28 publications

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“…Partial dissolution is also thought to have occurred as can be shown by ICP analysis. The observations noted in this study support the effects of ageing which have been reported to results in acceleration of the overall crystallization process [32,40]. Cundy and Cox [29] suggested that ageing facilitates 'product-formation' effects such as introduction of reaction mixture entities 'nuclei' or increasing their number hence generating a different nucleation profile which would have otherwise not been the case if the reaction mixture followed a straight-forward (conventional) synthesis procedure.…”

Section: Discussionsupporting

confidence: 84%

In situ ultrasonic monitoring of zeolite A crystallization from coal fly ash

Musyoka

Petrik

Hums³

et al. 2012

Catalysis Today

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In this study, high phase purity of zeolite A was prepared from coal fly ash precursors. The molar regime of both the clear solution extract and unseparated fly ash slurry was adjusted to achieve the right com-position for zeolite A crystallization. The formation process for zeolite A from coal fly ash precursors was monitored in detail using an in situ ultrasonic system and was complemented by use of ex situ techniques such as XRD, FTIR, SEM and FTIR. The findings from both the in situ ultrasonic monitoring process and ex situ techniques clearly contributed significantly in unmasking the formation process of zeolite A from coal fly ash compared to previous studies reported in the literature. The study also enriches the existing body of literature by deeply investigating the gel-solutioncrystal interactions starting from this complex feedstock. Comparable ultrasonic signals were generated when both clear and unseparated fly ash based precursor solutions were used during the zeolite synthesis process.

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Section: Discussionsupporting

confidence: 84%

In situ ultrasonic monitoring of zeolite A crystallization from coal fly ash

Musyoka

Petrik

Hums³

et al. 2012

Catalysis Today

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“…There was an obvious hole in the membrane prepared without aging (Figure 1(a)), and the dimensions of the zeolite crystals were larger along the aand b-axes than those of membranes that were prepared with aging. Li et al [16] found that aging decreased the crystal size, and this is consistent with the results obtained in the present study. The thickness of the membrane prepared without aging was about 35-40 m (Figure 1(b)).…”

Section: Pervaporation Measurementssupporting

confidence: 93%

Preparation of high selectivity silicalite-1 membranes by two-step in situ hydrothermal synthesis

Chen

Jiao

et al. 2011

Chin. Sci. Bull.

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High selectivity silicalite-1 membranes were synthesized on silica tubes by in situ hydrothermal synthesis. Using a two-step synthesis, a membrane with a separation factor of 99 was prepared for separating an ethanol/water mixture at 60°C. The average (n = 4) flux and separation factor of the membranes were 0.47 kg m 2 h 1 and 89, respectively. The membranes exhibited high reproducibility, and the relative standard deviation of the average (n = 4) flux and separation factor were only 5.3% and 9.2%, respectively. These results suggest that silica is a suitable support for synthesis of high-performance silicalite-1 membranes.high-selectivity, silicalite-1 membrane, hydrothermal synthesis, pervaporation, silica tube In recent years, much progress has been made in the preparation, characterization, and industrial application of zeolite membranes [1][2][3]. Zeolite membranes with excellent separation performance in a wide range of industrial processes, including gas separation, catalysis, pervaporation, and membrane reactors, have been produced [4][5][6]. Zeolite membranes can be used to separate different mixtures, and have low energy consumption and are environmentally friendly. Consequently, zeolite membranes have attracted attention in the field of separation technology [7][8][9]. In 2001, Morigami group [10] reported the first largescale pervaporation plant made of 16 NaA membrane modules, which produced 530 L/h of solvents at less than 0.2 wt% of water from 90 wt% solvent at 120°C. Compared with NaA or FAU membrane, FMI (including ZSM-5 and silicalite-1) membranes are still prepared and used within different laboratories up to now, and this may be caused by the following reasons: one is the higher preparation cost compared with NaA or FAU membranes, and another reason is that MFI membranes should be calcined in order to remove the templates, and this often results in the formation of cracks, which decreases the separation performance of the as-synthesized membranes [11]. Furthermore, the low separation performance and low reproducibility may be the main reason to limit the preparation of MFI membranes in largescale [12].An important potential application of hydrophobic silicalite-1 membranes is the separation of organic compounds, such as ethanol, 1-butanol, and other fermentation products, from fermentation broth [13,14]. In this application, silicalite-1 membranes show higher separation performance than polymer membranes [15]. Hydrophobic silicalite-1 membranes may also be used to extract small organic molecules from wastewater for recycling and to reduce environmental pollution. In order to prepare silicalite-1 membranes, in situ hydrothermal synthesis is often used to prepare silicalite-1 membranes because the conditions are simple to control. However, it is not easy to obtain high-performance membranes with this method. High-performance silicalite-1 membranes can be obtained by using the secondary growth

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“…[25][26][27] For instance, in the synthesis of nanosize Silicalite-1, long ageing times at room temperature followed by fast heating provokes massive formation of nanocrystals. [25,26] Departing from polymeric silicon sources the hydrothermal gel method for zeolite synthesis, when adapted for nanocrystal synthesis, generally results in difficult to separate aggregates. [14] Such aggregates of elongated nanoparticles are encountered with zeolites that have TON framework topology [28] called ZSM-22, Theta-1, KZ-2, ISI-1 and Nu-10.…”

Section: Introductionmentioning

confidence: 99%

Formation of ZSM‐22 Zeolite Catalytic Particles by Fusion of Elementary Nanorods

Hayasaka

Liang

Huybrechts

et al. 2007

Chemistry A European J

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An ZSM-22 aluminosilicate zeolite was synthesized using the hydrothermal gel method at 150 degrees C. Products obtained after different synthesis times were characterized using various techniques and catalytic testing. Massive formation of ZSM-22 nanocrystals occurs after only a short synthesis time, appearing as isolated rods with a cross section of 12+/-4 nm. Nanorods have aluminum enriched at their external surface. Later in the crystallization process nanorods align and fuse sideways, whereby the external surface is systematically converted into an internal micropore surface. The formation of aluminum bearing micropores by the joining of nanorod surfaces is responsible for the enhanced catalytic activity. For this, the zeolite synthesis of nanoscale crystallites is ineffective for enhancing catalytic activity.

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Aging effects on the nucleation and crystallization kinetics of colloidal TPA-silicalite-1

Cited by 131 publications

References 28 publications

In situ ultrasonic monitoring of zeolite A crystallization from coal fly ash

In situ ultrasonic monitoring of zeolite A crystallization from coal fly ash

Preparation of high selectivity silicalite-1 membranes by two-step in situ hydrothermal synthesis

Formation of ZSM‐22 Zeolite Catalytic Particles by Fusion of Elementary Nanorods

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